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1. Mutual neutralization of C$_{60}^+$ and C$_{60}^-$ ions: Excitation energies and state-selective rate coefficients

Author

Gatchell, Michael, Paul, Raka, Ji, MingChao, Rosén, Stefan, Thomas, Richard D., Cederquist, Henrik, Schmidt, Henning T., Larson, Åsa, and Zettergren, Henning

Subjects
Astrophysics - Astrophysics of Galaxies, Physics - Chemical Physics
Abstract

Context: Mutual neutralization between cations and anions play an important role in determining the charge-balance in certain astrophysical environments. However, empirical data for such reactions involving complex molecular species has been lacking due to challenges in performing experimental studies, leaving the astronomical community to rely on decades old models with large uncertainties for describing these processes in the interstellar medium. Aims: To investigate the mutual neutralization (MN) reaction, C$_{60}^+$ + C$_{60}^-$ $\rightarrow$ C$_{60}^*$ + C$_{60}$, for collisions at interstellar-like conditions. Methods: The mutual neutralization reaction between C$_{60}^+$ and C$_{60}^-$ at collision energies of 100\,meV was studied using the Double ElectroStatic Ion Ring ExpEriment, DESIREE, and its merged-beam capabilities. To aid in the interpretation of the experimental results, semi-classical modeling based on the Landau-Zener approach was performed for the studied reaction. Results: We experimentally identify a narrow range of kinetic energies for the neutral reaction products. Modeling was used to calculate the quantum state-selective reaction probabilities, absolute cross sections, and rate coefficients of these MN reactions, using the experimental results as a benchmark. The MN cross sections are compared with model results for electron attachment to C$_{60}$ and electron recombination with C$_{60}^+$. Conclusions: The present results show that it is crucial to take mutual polarization effects, the finite sizes, and the final quantum states of both molecular ions into account for reliable predictions of MN rates expected to strongly influence the charge-balance and chemistry in, e.g., dense molecular clouds., Comment: 9 pages, 4 figures

Published
2024

2. PDRs4All VIII: Mid-IR emission line inventory of the Orion Bar

Author

Van De Putte, Dries, Meshaka, Raphael, Trahin, Boris, Habart, Emilie, Peeters, Els, Berné, Olivier, Alarcón, Felipe, Canin, Amélie, Chown, Ryan, Schroetter, Ilane, Sidhu, Ameek, Boersma, Christiaan, Bron, Emeric, Dartois, Emmanuel, Goicoechea, Javier R., Gordon, Karl D., Onaka, Takashi, Tielens, Alexander G. G. M., Verstraete, Laurent, Wolfire, Mark G., Abergel, Alain, Bergin, Edwin A., Bernard-Salas, Jeronimo, Cami, Jan, Cuadrado, Sara, Dicken, Daniel, Elyajouri, Meriem, Fuente, Asunción, Joblin, Christine, Khan, Baria, Lacinbala, Ozan, Languignon, David, Gal, Romane Le, Maragkoudakis, Alexandros, Okada, Yoko, Pasquini, Sofia, Pound, Marc W., Robberto, Massimo, Röllig, Markus, Schefter, Bethany, Schirmer, Thiébaut, Tabone, Benoit, Vicente, Sílvia, Zannese, Marion, Colgan, Sean W. J., He, Jinhua, Rouillé, Gaël, Togi, Aditya, Aleman, Isabel, Auchettl, Rebecca, Baratta, Giuseppe Antonio, Bejaoui, Salma, Bera, Partha P., Black, John H., Boulanger, Francois, Bouwman, Jordy, Brandl, Bernhard, Brechignac, Philippe, Brünken, Sandra, Buragohain, Mridusmita, Burkhardt, Andrew, Candian, Alessandra, Cazaux, Stéphanie, Cernicharo, Jose, Chabot, Marin, Chakraborty, Shubhadip, Champion, Jason, Cooke, Ilsa R., Coutens, Audrey, Cox, Nick L. J., Demyk, Karine, Meyer, Jennifer Donovan, Foschino, Sacha, García-Lario, Pedro, Gerin, Maryvonne, Gottlieb, Carl A., Guillard, Pierre, Gusdorf, Antoine, Hartigan, Patrick, Herbst, Eric, Hornekaer, Liv, Issa, Lina, Jäger, Cornelia, Janot-Pacheco, Eduardo, Kannavou, Olga, Kaufman, Michael, Kemper, Francisca, Kendrew, Sarah, Kirsanova, Maria S., Klaassen, Pamela, Kwok, Sun, Labiano, Álvaro, Lai, Thomas S. -Y., Floch, Bertrand Le, Petit, Franck Le, Li, Aigen, Linz, Hendrik, Mackie, Cameron J., Madden, Suzanne C., Mascetti, Joëlle, McGuire, Brett A., Merino, Pablo, Micelotta, Elisabetta R., Morse, Jon A., Mulas, Giacomo, Neelamkodan, Naslim, Ohsawa, Ryou, Omont, Alain, Paladini, Roberta, Palumbo, Maria Elisabetta, Pathak, Amit, Pendleton, Yvonne J., Petrignani, Annemieke, Pino, Thomas, Puga, Elena, Rangwala, Naseem, Rapacioli, Mathias, Rho, Jeonghee, Ricca, Alessandra, Roman-Duval, Julia, Roser, Joseph, Roueff, Evelyne, Salama, Farid, Sales, Dinalva A., Sandstrom, Karin, Sarre, Peter, Sciamma-O'Brien, Ella, Sellgren, Kris, Shenoy, Sachindev S., Teyssier, David, Thomas, Richard D., Witt, Adolf N., Wootten, Alwyn, Ysard, Nathalie, Zettergren, Henning, Zhang, Yong, Zhang, Ziwei E., and Zhen, Junfeng

Subjects
Astrophysics - Astrophysics of Galaxies
Abstract

Mid-infrared emission features probe the properties of ionized gas, and hot or warm molecular gas. The Orion Bar is a frequently studied photodissociation region (PDR) containing large amounts of gas under these conditions, and was observed with the MIRI IFU aboard JWST as part of the "PDRs4All" program. The resulting IR spectroscopic images of high angular resolution (0.2") reveal a rich observational inventory of mid-IR emission lines, and spatially resolve the substructure of the PDR, with a mosaic cutting perpendicularly across the ionization front and three dissociation fronts. We extracted five spectra that represent the ionized, atomic, and molecular gas layers, and measured the most prominent gas emission lines. An initial analysis summarizes the physical conditions of the gas and the potential of these data. We identified around 100 lines, report an additional 18 lines that remain unidentified, and measured the line intensities and central wavelengths. The H I recombination lines originating from the ionized gas layer bordering the PDR, have intensity ratios that are well matched by emissivity coefficients from H recombination theory, but deviate up to 10% due contamination by He I lines. We report the observed emission lines of various ionization stages of Ne, P, S, Cl, Ar, Fe, and Ni, and show how certain line ratios vary between the five regions. We observe the pure-rotational H$_2$ lines in the vibrational ground state from 0-0 S(1) to 0-0 S(8), and in the first vibrationally excited state from 1-1 S(5) to 1-1 S(9). We derive H$_2$ excitation diagrams, and approximate the excitation with one thermal (~700 K) component representative of an average gas temperature, and one non-thermal component (~2700 K) probing the effect of UV pumping. We compare these results to an existing model for the Orion Bar PDR and highlight the differences with the observations., Comment: 26 pages, 12 figures, 3 tables. Submitted to A&A, under review (1st revision)

Published
2024
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3. A far-ultraviolet-driven photoevaporation flow observed in a protoplanetary disk

Author

Berné, Olivier, Habart, Emilie, Peeters, Els, Schroetter, Ilane, Canin, Amélie, Sidhu, Ameek, Chown, Ryan, Bron, Emeric, Haworth, Thomas J., Klaassen, Pamela, Trahin, Boris, Van De Putte, Dries, Alarcón, Felipe, Zannese, Marion, Abergel, Alain, Bergin, Edwin A., Bernard-Salas, Jeronimo, Boersma, Christiaan, Cami, Jan, Cuadrado, Sara, Dartois, Emmanuel, Dicken, Daniel, Elyajouri, Meriem, Fuente, Asunción, Goicoechea, Javier R., Gordon, Karl D., Issa, Lina, Joblin, Christine, Kannavou, Olga, Khan, Baria, Lacinbala, Ozan, Languignon, David, Gal, Romane Le, Maragkoudakis, Alexandros, Meshaka, Raphael, Okada, Yoko, Onaka, Takashi, Pasquini, Sofia, Pound, Marc W., Robberto, Massimo, Röllig, Markus, Schefter, Bethany, Schirmer, Thiébaut, Simmer, Thomas, Tabone, Benoit, Tielens, Alexander G. G. M., Vicente, Sílvia, Wolfire, Mark G., Aleman, Isabel, Allamandola, Louis, Auchettl, Rebecca, Baratta, Giuseppe Antonio, Baruteau, Clément, Bejaoui, Salma, Bera, Partha P., Black, John H., Boulanger, Francois, Bouwman, Jordy, Brandl, Bernhard, Brechignac, Philippe, Brünken, Sandra, Buragohain, Mridusmita, Burkhardt, Andrew, Candian, Alessandra, Cazaux, Stéphanie, Cernicharo, Jose, Chabot, Marin, Chakraborty, Shubhadip, Champion, Jason, Colgan, Sean W. J., Cooke, Ilsa R., Coutens, Audrey, Cox, Nick L. J., Demyk, Karine, Meyer, Jennifer Donovan, Engrand, Cécile, Foschino, Sacha, García-Lario, Pedro, Gavilan, Lisseth, Gerin, Maryvonne, Godard, Marie, Gottlieb, Carl A., Guillard, Pierre, Gusdorf, Antoine, Hartigan, Patrick, He, Jinhua, Herbst, Eric, Hornekaer, Liv, Jäger, Cornelia, Janot-Pacheco, Eduardo, Kaufman, Michael, Kemper, Francisca, Kendrew, Sarah, Kirsanova, Maria S., Knight, Collin, Kwok, Sun, Labiano, Álvaro, Lai, Thomas S. -Y., Lee, Timothy J., Lefloch, Bertrand, Petit, Franck Le, Li, Aigen, Linz, Hendrik, Mackie, Cameron J., Madden, Suzanne C., Mascetti, Joëlle, McGuire, Brett A., Merino, Pablo, Micelotta, Elisabetta R., Morse, Jon A., Mulas, Giacomo, Neelamkodan, Naslim, Ohsawa, Ryou, Paladini, Roberta, Palumbo, Maria Elisabetta, Pathak, Amit, Pendleton, Yvonne J., Petrignani, Annemieke, Pino, Thomas, Puga, Elena, Rangwala, Naseem, Rapacioli, Mathias, Ricca, Alessandra, Roman-Duval, Julia, Roueff, Evelyne, Rouillé, Gaël, Salama, Farid, Sales, Dinalva A., Sandstrom, Karin, Sarre, Peter, Sciamma-O'Brien, Ella, Sellgren, Kris, Shannon, Matthew J., Simonnin, Adrien, Shenoy, Sachindev S., Teyssier, David, Thomas, Richard D., Togi, Aditya, Verstraete, Laurent, Witt, Adolf N., Wootten, Alwyn, Ysard, Nathalie, Zettergren, Henning, Zhang, Yong, Zhang, Ziwei E., and Zhen, Junfeng

Subjects
Astrophysics - Astrophysics of Galaxies
Abstract

Most low-mass stars form in stellar clusters that also contain massive stars, which are sources of far-ultraviolet (FUV) radiation. Theoretical models predict that this FUV radiation produces photo-dissociation regions (PDRs) on the surfaces of protoplanetary disks around low-mass stars, impacting planet formation within the disks. We report JWST and Atacama Large Millimetere Array observations of a FUV-irradiated protoplanetary disk in the Orion Nebula. Emission lines are detected from the PDR; modelling their kinematics and excitation allows us to constrain the physical conditions within the gas. We quantify the mass-loss rate induced by the FUV irradiation, finding it is sufficient to remove gas from the disk in less than a million years. This is rapid enough to affect giant planet formation in the disk.

Published
2024

4. PDRs4All III: JWST's NIR spectroscopic view of the Orion Bar

Author

Peeters, Els, Habart, Emilie, Berne, Olivier, Sidhu, Ameek, Chown, Ryan, Van De Putte, Dries, Trahin, Boris, Schroetter, Ilane, Canin, Amelie, Alarcon, Felipe, Schefter, Bethany, Khan, Baria, Pasquini, Sofia, Tielens, Alexander G. G. M., Wolfire, Mark G., Dartois, Emmanuel, Goicoechea, Javier R., Maragkoudakis, Alexandros, Onaka, Takashi, Pound, Marc W., Vicente, Silvia, Abergel, Alain, Bergin, Edwin A., Bernard-Salas, Jeronimo, Boersma, Christiaan, Bron, Emeric, Cami, Jan, Cuadrado, Sara, Dicken, Daniel, Elyajour, Meriem, Fuente, Asuncion, Gordon, Karl D., Issa, Lina, Joblin, Christine, Kannavou, Olga, Lacinbala, Ozan, Languignon, David, Gal, Romane Le, Meshaka, Raphael, Okada, Yoko, Robberto, Massimo, Roellig, Markus, Schirmer, Thiebaut, Tabone, Benoit, Zannese, Marion, Aleman, Isabel, Allamandola, Louis, Auchettl, Rebecca, Baratta, Giuseppe Antonio, Bejaoui, Salma, Bera, Partha P., Black, John H., Boulanger, Francois, Bouwman, Jordy, Brandl, Bernhard, Brechignac, Philippe, Brunken, Sandra, Buragohain, Mridusmita, Burkhardt, Andrew, Candian, Alessandra, Cazaux, Stephanie, Cernicharo, Jose, Chabot, Marin, Chakraborty, Shubhadip, Champion, Jason, Colgan, Sean W. J., Cooke, Ilsa R., Coutens, Audrey, Cox, Nick L. J., Demyk, Karine, Meyer, Jennifer Donovan, Foschino, Sacha, Garcia-Lario, Pedro, Gerin, Maryvonne, Gottlieb, Carl A., Guillard, Pierre, Gusdorf, Antoine, Hartigan, Patrick, He, Jinhua, Herbst, Eric, Hornekaer, Liv, Jager, Cornelia, Janot-Pacheco, Eduardo, Kaufman, Michael, Kendrew, Sarah, Kirsanova, Maria S., Klaassen, Pamela, Kwok, Sun, Labiano, Alvaro, Lai, Thomas S. -Y., Lee, Timothy J., Lefloch, Bertrand, Petit, Franck Le, Li, Aigen, Linz, Hendrik, Mackie, Cameron J., Madden, Suzanne C., Mascetti, Joelle, McGuire, Brett A., Merino, Pablo, Micelotta, Elisabetta R., Misselt, Karl, Morse, Jon A., Mulas, Giacomo, Neelamkodan, Naslim, Ohsawa, Ryou, Paladini, Roberta, Palumbo, Maria Elisabetta, Pathak, Amit, Pendleton, Yvonne J., Petrignani, Annemieke, Pino, Thomas, Puga, Elena, Rangwala, Naseem, Rapacioli, Mathias, Ricca, Alessandra, Roman-Duval, Julia, Roser, Joseph, Roueff, Evelyne, Rouille, Gael, Salama, Farid, Sales, Dinalva A., Sandstrom, Karin, Sarre, Peter, Sciamma-O'Brien, Ella, Sellgren, Kris, Shenoy, Sachindev S., Teyssier, David, Thomas, Richard D., Togi, Aditya, Verstraete, Laurent, Witt, Adolf N., Wootten, Alwyn, Ysard, Nathalie, Zettergren, Henning, Zhang, Yong, Zhang, Ziwei E., and Zhen, Junfeng

Subjects
Astrophysics - Astrophysics of Galaxies
Abstract

(Abridged) We investigate the impact of radiative feedback from massive stars on their natal cloud and focus on the transition from the HII region to the atomic PDR (crossing the ionisation front (IF)), and the subsequent transition to the molecular PDR (crossing the dissociation front (DF)). We use high-resolution near-IR integral field spectroscopic data from NIRSpec on JWST to observe the Orion Bar PDR as part of the PDRs4All JWST Early Release Science Program. The NIRSpec data reveal a forest of lines including, but not limited to, HeI, HI, and CI recombination lines, ionic lines, OI and NI fluorescence lines, Aromatic Infrared Bands (AIBs including aromatic CH, aliphatic CH, and their CD counterparts), CO2 ice, pure rotational and ro-vibrational lines from H2, and ro-vibrational lines HD, CO, and CH+, most of them detected for the first time towards a PDR. Their spatial distribution resolves the H and He ionisation structure in the Huygens region, gives insight into the geometry of the Bar, and confirms the large-scale stratification of PDRs. We observe numerous smaller scale structures whose typical size decreases with distance from Ori C and IR lines from CI, if solely arising from radiative recombination and cascade, reveal very high gas temperatures consistent with the hot irradiated surface of small-scale dense clumps deep inside the PDR. The H2 lines reveal multiple, prominent filaments which exhibit different characteristics. This leaves the impression of a "terraced" transition from the predominantly atomic surface region to the CO-rich molecular zone deeper in. This study showcases the discovery space created by JWST to further our understanding of the impact radiation from young stars has on their natal molecular cloud and proto-planetary disk, which touches on star- and planet formation as well as galaxy evolution., Comment: 52 pages, 30 figures, submitted to A&A

Published
2023
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5. PDRs4All II: JWST's NIR and MIR imaging view of the Orion Nebula

Author

Habart, Emilie, Peeters, Els, Berné, Olivier, Trahin, Boris, Canin, Amélie, Chown, Ryan, Sidhu, Ameek, Van De Putte, Dries, Alarcón, Felipe, Schroetter, Ilane, Dartois, Emmanuel, Vicente, Sílvia, Abergel, Alain, Bergin, Edwin A., Bernard-Salas, Jeronimo, Boersma, Christiaan, Bron, Emeric, Cami, Jan, Cuadrado, Sara, Dicken, Daniel, Elyajouri, Meriem, Fuente, Asunción, Goicoechea, Javier R., Gordon, Karl D., Issa, Lina, Joblin, Christine, Kannavou, Olga, Khan, Baria, Lacinbala, Ozan, Languignon, David, Gal, Romane Le, Maragkoudakis, Alexandros, Meshaka, Raphael, Okada, Yoko, Onaka, Takashi, Pasquini, Sofia, Pound, Marc W., Robberto, Massimo, Röllig, Markus, Schefter, Bethany, Schirmer, Thiébaut, Tabone, Benoit, Tielens, Alexander G. G. M., Wolfire, Mark G., Zannese, Marion, Ysard, Nathalie, Miville-Deschenes, Marc-Antoine, Aleman, Isabel, Allamandola, Louis, Auchettl, Rebecca, Baratta, Giuseppe Antonio, Bejaoui, Salma, Bera, Partha P., Black, John H., Boulanger, Francois, Bouwman, Jordy, Brandl, Bernhard, Brechignac, Philippe, Brünken, Sandra, Buragohain, Mridusmita, Burkhardt, rew, Candian, Alessandra, Cazaux, Stéphanie, Cernicharo, Jose, Chabot, Marin, Chakraborty, Shubhadip, Champion, Jason, Colgan, Sean W. J., Cooke, Ilsa R., Coutens, Audrey, Cox, Nick L. J., Demyk, Karine, Meyer, Jennifer Donovan, Foschino, Sacha, García-Lario, Pedro, Gavilan, Lisseth, Gerin, Maryvonne, Gottlieb, Carl A., Guillard, Pierre, Gusdorf, Antoine, Hartigan, Patrick, He, Jinhua, Herbst, Eric, Hornekaer, Liv, Jäger, Cornelia, Janot-Pacheco, Eduardo, Kaufman, Michael, Kemper, Francisca, Kendrew, Sarah, Kirsanova, Maria S., Klaassen, Pamela, Kwok, Sun, Labiano, Álvaro, Lai, Thomas S. -Y., Lee, Timothy J., Lefloch, Bertrand, Petit, Franck Le, Li, Aigen, Linz, Hendrik, Mackie, Cameron J., Madden, Suzanne C., Mascetti, Joëlle, McGuire, Brett A., Merino, Pablo, Micelotta, Elisabetta R., Misselt, Karl, Morse, Jon A., Mulas, Giacomo, Neelamkodan, Naslim, Ohsawa, Ryou, Omont, Alain, Paladini, Roberta, Palumbo, Maria Elisabetta, Pathak, Amit, Pendleton, Yvonne J., Petrignani, Annemieke, Pino, Thomas, Puga, Elena, Rangwala, Naseem, Rapacioli, Mathias, Ricca, Alessandra, Roman-Duval, Julia, Roser, Joseph, Roueff, Evelyne, Rouillé, Gaël, Salama, Farid, Sales, Dinalva A., Sandstrom, Karin, Sarre, Peter, Sciamma-O'Brien, Ella, Sellgren, Kris, Shenoy, Sachindev S., Teyssier, David, Thomas, Richard D., Togi, Aditya, Verstraete, Laurent, Witt, Adolf N., Wootten, Alwyn, Zettergren, Henning, Zhang, Yong, Zhang, Ziwei E., and Zhen, Junfeng

Subjects
Astrophysics - Astrophysics of Galaxies
Abstract

The JWST has captured the most detailed and sharpest infrared images ever taken of the inner region of the Orion Nebula, the nearest massive star formation region, and a prototypical highly irradiated dense photo-dissociation region (PDR). We investigate the fundamental interaction of far-ultraviolet photons with molecular clouds. The transitions across the ionization front (IF), dissociation front (DF), and the molecular cloud are studied at high-angular resolution. These transitions are relevant to understanding the effects of radiative feedback from massive stars and the dominant physical and chemical processes that lead to the IR emission that JWST will detect in many Galactic and extragalactic environments. Due to the proximity of the Orion Nebula and the unprecedented angular resolution of JWST, these data reveal that the molecular cloud borders are hyper structured at small angular scales of 0.1-1" (0.0002-0.002 pc or 40-400 au at 414 pc). A diverse set of features are observed such as ridges, waves, globules and photoevaporated protoplanetary disks. At the PDR atomic to molecular transition, several bright features are detected that are associated with the highly irradiated surroundings of the dense molecular condensations and embedded young star. Toward the Orion Bar PDR, a highly sculpted interface is detected with sharp edges and density increases near the IF and DF. This was predicted by previous modeling studies, but the fronts were unresolved in most tracers. A complex, structured, and folded DF surface was traced by the H2 lines. This dataset was used to revisit the commonly adopted 2D PDR structure of the Orion Bar. JWST provides us with a complete view of the PDR, all the way from the PDR edge to the substructured dense region, and this allowed us to determine, in detail, where the emission of the atomic and molecular lines, aromatic bands, and dust originate.

Published
2023
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6. PDRs4All IV. An embarrassment of riches: Aromatic infrared bands in the Orion Bar

Author

Chown, Ryan, Sidhu, Ameek, Peeters, Els, Tielens, Alexander G. G. M., Cami, Jan, Berné, Olivier, Habart, Emilie, Alarcón, Felipe, Canin, Amélie, Schroetter, Ilane, Trahin, Boris, Van De Putte, Dries, Abergel, Alain, Bergin, Edwin A., Bernard-Salas, Jeronimo, Boersma, Christiaan, Bron, Emeric, Cuadrado, Sara, Dartois, Emmanuel, Dicken, Daniel, El-Yajouri, Meriem, Fuente, Asunción, Goicoechea, Javier R., Gordon, Karl D., Issa, Lina, Joblin, Christine, Kannavou, Olga, Khan, Baria, Lacinbala, Ozan, Languignon, David, Gal, Romane Le, Maragkoudakis, Alexandros, Meshaka, Raphael, Okada, Yoko, Onaka, Takashi, Pasquini, Sofia, Pound, Marc W., Robberto, Massimo, Röllig, Markus, Schefter, Bethany, Schirmer, Thiébaut, Vicente, Sílvia, Wolfire, Mark G., Zannese, Marion, Aleman, Isabel, Allamandola, Louis, Auchettl, Rebecca, Baratta, Giuseppe Antonio, Bejaoui, Salma, Bera, Partha P., Black, John H., Boulanger, Francois, Bouwman, Jordy, Brandl, Bernhard, Brechignac, Philippe, Brünken, Sandra, Buragohain, Mridusmita, Burkhardt, Andrew, Candian, Alessandra, Cazaux, Stéphanie, Cernicharo, Jose, Chabot, Marin, Chakraborty, Shubhadip, Champion, Jason, Colgan, Sean W. J., Cooke, Ilsa R., Coutens, Audrey, Cox, Nick L. J., Demyk, Karine, Meyer, Jennifer Donovan, Foschino, Sacha, García-Lario, Pedro, Gavilan, Lisseth, Gerin, Maryvonne, Gottlieb, Carl A., Guillard, Pierre, Gusdorf, Antoine, Hartigan, Patrick, He, Jinhua, Herbst, Eric, Hornekaer, Liv, Jäger, Cornelia, Janot-Pacheco, Eduardo, Kaufman, Michael, Kemper, Francisca, Kendrew, Sarah, Kirsanova, Maria S., Klaassen, Pamela, Kwok, Sun, Labiano, Álvaro, Lai, Thomas S. -Y., Lee, Timothy J., Lefloch, Bertrand, Petit, Franck Le, Li, Aigen, Linz, Hendrik, Mackie, Cameron J., Madden, Suzanne C., Mascetti, Joëlle, McGuire, Brett A., Merino, Pablo, Micelotta, Elisabetta R., Misselt, Karl, Morse, Jon A., Mulas, Giacomo, Neelamkodan, Naslim, Ohsawa, Ryou, Omont, Alain, Paladini, Roberta, Palumbo, Maria Elisabetta, Pathak, Amit, Pendleton, Yvonne J., Petrignani, Annemieke, Pino, Thomas, Puga, Elena, Rangwala, Naseem, Rapacioli, Mathias, Ricca, Alessandra, Roman-Duval, Julia, Roser, Joseph, Roueff, Evelyne, Rouillé, Gaël, Salama, Farid, Sales, Dinalva A., Sandstrom, Karin, Sarre, Peter, Sciamma-O'Brien, Ella, Sellgren, Kris, Shenoy, Sachindev S., Teyssier, David, Thomas, Richard D., Togi, Aditya, Verstraete, Laurent, Witt, Adolf N., Wootten, Alwyn, Zettergren, Henning, Zhang, Yong, Zhang, Ziwei E., and Zhen, Junfeng

Subjects
Astrophysics - Astrophysics of Galaxies, Astrophysics - Solar and Stellar Astrophysics
Abstract

(Abridged) Mid-infrared observations of photodissociation regions (PDRs) are dominated by strong emission features called aromatic infrared bands (AIBs). The most prominent AIBs are found at 3.3, 6.2, 7.7, 8.6, and 11.2 $\mu$m. The most sensitive, highest-resolution infrared spectral imaging data ever taken of the prototypical PDR, the Orion Bar, have been captured by JWST. We provide an inventory of the AIBs found in the Orion Bar, along with mid-IR template spectra from five distinct regions in the Bar: the molecular PDR, the atomic PDR, and the HII region. We use JWST NIRSpec IFU and MIRI MRS observations of the Orion Bar from the JWST Early Release Science Program, PDRs4All (ID: 1288). We extract five template spectra to represent the morphology and environment of the Orion Bar PDR. The superb sensitivity and the spectral and spatial resolution of these JWST observations reveal many details of the AIB emission and enable an improved characterization of their detailed profile shapes and sub-components. While the spectra are dominated by the well-known AIBs at 3.3, 6.2, 7.7, 8.6, 11.2, and 12.7 $\mu$m, a wealth of weaker features and sub-components are present. We report trends in the widths and relative strengths of AIBs across the five template spectra. These trends yield valuable insight into the photochemical evolution of PAHs, such as the evolution responsible for the shift of 11.2 $\mu$m AIB emission from class B$_{11.2}$ in the molecular PDR to class A$_{11.2}$ in the PDR surface layers. This photochemical evolution is driven by the increased importance of FUV processing in the PDR surface layers, resulting in a "weeding out" of the weakest links of the PAH family in these layers. For now, these JWST observations are consistent with a model in which the underlying PAH family is composed of a few species: the so-called 'grandPAHs'., Comment: 25 pages, 10 figures, to appear in A&A

Published
2023
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7. PDRs4All: A JWST Early Release Science Program on radiative feedback from massive stars

Author

Berné, Olivier, Habart, Émilie, Peeters, Els, Abergel, Alain, Bergin, Edwin A., Bernard-Salas, Jeronimo, Bron, Emeric, Cami, Jan, Cazaux, Stéphanie, Dartois, Emmanuel, Fuente, Asunción, Goicoechea, Javier R., Gordon, Karl D., Okada, Yoko, Onaka, Takashi, Robberto, Massimo, Röllig, Markus, Tielens, Alexander G. G. M., Vicente, Silvia, Wolfire, Mark G., Alarcon, Felipe, Boersma, C., Canin, Ameélie, Chown, Ryan, Dicken, Daniel, Languignon, David, Gal, Romane Le, Pound, Marc W., Trahin, Boris, Simmer, Thomas, Sidhu, Ameek, Van De Putte, Dries, Cuadrado, Sara, Guilloteau, Claire, Maragkoudakis, Alexandros, Schefter, Bethany R., Schirmer, Thiébaut, Aleman, Isabel, Allamandola, Louis, Auchettl, Rebecca, Baratta, Giuseppe Antonio, Bejaoui, Salma, Bera, Partha P., Bilalbegovic, Goranka, Black, John H., Boulanger, Francois, Bouwman, Jordy, Brandl, Bernhard, Brechignac, Philippe, Brunken, Sandra, Burkhardt, Andrew, Candian, Alessandra, Cernicharo, Jose, Chabot, Marin, Chakraborty, Shubhadip, Champion, Jason, Colgan, Sean W. J., Cooke, Ilsa R., Coutens, Audrey, Cox, Nick L. J., Demyk, Karine, Meyer, Jennifer Donovan, Engrand, Cécile, Foschino, Sacha, Garcıa-Lario, Pedro, Gavilan, Lisseth, Gerin, Maryvonne, Godard, Marie, Gottlieb, Carl A., Guillard, Pierre, Gusdorf, Antoine, Hartigan, Patrick, He, Jinhua, Herbst, Eric, Hornekaer, Liv, Jaeger, Cornelia, Janot-Pacheco, Eduardo, Joblin, Christine, Kaufman, Michael, Kemper, Francisca, Kendrew, Sarah, Kirsanova, Maria S., Klaassen, Pamela, Knight, Collin, Kwok, Sun, Labiano, Alvaro, Lai, Thomas S. -Y., Lee, Timothy J., Lefloch, Bertrand, Petit, Franck Le, Li, Aigen, Linz, Hendrik, Mackie, Cameron J., Madden, Suzanne C., Mascetti, Joelle, McGuire, Brett A., Merino, Pablo, Micelotta, Elisabetta R., Misselt, Karl, Morse, Jon A., Mulas, Giacomo, Neelamkodan, Naslim, Ohsawa, Ryou, Omont, Alain, Paladini, Roberta, Palumbo, Maria Elisabetta, Pathak, Amit, Pendleton, Yvonne J., Petrignani, Annemieke, Pino, Thomas, Puga, Elena, Rangwala, Naseem, Rapacioli, Mathias, Ricca, Alessandra, Roman-Duval, Julia, Roser, Joseph, Roueff, Evelyne, Rouille, Gael, Salama, Farid, Sales, Dinalva A., Sandstrom, Karin, Sarre, Peter, Sciamma-O'Brien, Ella, Sellgren, Kris, Shannon, Matthew J., Shenoy, Sachindev S., Teyssier, David, Thomas, Richard D., Togi, Aditya, Verstraete, Laurent, Witt, Adolf N., Wootten, Alwyn, Ysard, Nathalie, Zettergren, Henning, Zhang, Yong, Zhang, Ziwei E., and Zhen, Junfeng

Subjects
Astrophysics - Astrophysics of Galaxies
Abstract

Massive stars disrupt their natal molecular cloud material through radiative and mechanical feedback processes. These processes have profound effects on the evolution of interstellar matter in our Galaxy and throughout the Universe, from the era of vigorous star formation at redshifts of 1-3 to the present day. The dominant feedback processes can be probed by observations of the Photo-Dissociation Regions (PDRs) where the far-ultraviolet photons of massive stars create warm regions of gas and dust in the neutral atomic and molecular gas. PDR emission provides a unique tool to study in detail the physical and chemical processes that are relevant for most of the mass in inter- and circumstellar media including diffuse clouds, proto-planetary disks and molecular cloud surfaces, globules, planetary nebulae, and star-forming regions. PDR emission dominates the infrared (IR) spectra of star-forming galaxies. Most of the Galactic and extragalactic observations obtained with the James Webb Space Telescope (JWST) will therefore arise in PDR emission. In this paper we present an Early Release Science program using the MIRI, NIRSpec, and NIRCam instruments dedicated to the observations of an emblematic and nearby PDR: the Orion Bar. These early JWST observations will provide template datasets designed to identify key PDR characteristics in JWST observations. These data will serve to benchmark PDR models and extend them into the JWST era. We also present the Science-Enabling products that we will provide to the community. These template datasets and Science-Enabling products will guide the preparation of future proposals on star-forming regions in our Galaxy and beyond and will facilitate data analysis and interpretation of forthcoming JWST observations., Comment: Submitted to PASP

Published
2022
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8. A localized view on molecular dissociation via electron-ion partial covariance

Author

Allum, Felix, Music, Valerija, Inhester, Ludger, Boll, Rebecca, Erk, Benjamin, Schmidt, Philipp, Baumann, Thomas M., Brenner, Günter, Burt, Michael, Demekhin, Philipp V., Dörner, Simon, Ehresmann, Arno, Galler, Andreas, Grychtol, Patrik, Heathcote, David, Kargin, Denis, Larsson, Mats, Lee, Jason W. L., Li, Zheng, Manschwetus, Bastian, Marder, Lutz, Mason, Robert, Meyer, Michael, Otto, Huda, Passow, Christopher, Pietschnig, Rudolf, Ramm, Daniel, Schubert, Kaja, Schwob, Lucas, Thomas, Richard D., Vallance, Claire, Vidanović, Igor, von Korff Schmising, Clemens, Wagner, René, Walter, Peter, Zhaunerchyk, Vitali, Rolles, Daniel, Bari, Sadia, Brouard, Mark, and Ilchen, Markus

Published
2022
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9. PDRs4All

Author

Peeters, Els, primary, Habart, Emilie, additional, Berné, Olivier, additional, Sidhu, Ameek, additional, Chown, Ryan, additional, Van De Putte, Dries, additional, Trahin, Boris, additional, Schroetter, Ilane, additional, Canin, Amélie, additional, Alarcón, Felipe, additional, Schefter, Bethany, additional, Khan, Baria, additional, Pasquini, Sofia, additional, Tielens, Alexander G. G. M., additional, Wolfire, Mark G., additional, Dartois, Emmanuel, additional, Goicoechea, Javier R., additional, Maragkoudakis, Alexandros, additional, Onaka, Takashi, additional, Pound, Marc W., additional, Vicente, Sílvia, additional, Abergel, Alain, additional, Bergin, Edwin A., additional, Bernard-Salas, Jeronimo, additional, Boersma, Christiaan, additional, Bron, Emeric, additional, Cami, Jan, additional, Cuadrado, Sara, additional, Dicken, Daniel, additional, Elyajouri, Meriem, additional, Fuente, Asunción, additional, Gordon, Karl D., additional, Issa, Lina, additional, Joblin, Christine, additional, Kannavou, Olga, additional, Lacinbala, Ozan, additional, Languignon, David, additional, Le Gal, Romane, additional, Meshaka, Raphael, additional, Okada, Yoko, additional, Robberto, Massimo, additional, Röllig, Markus, additional, Schirmer, Thiébaut, additional, Tabone, Benoit, additional, Zannese, Marion, additional, Aleman, Isabel, additional, Allamandola, Louis, additional, Auchettl, Rebecca, additional, Baratta, Giuseppe Antonio, additional, Bejaoui, Salma, additional, Bera, Partha P., additional, Black, John H., additional, Boulanger, Francois, additional, Bouwman, Jordy, additional, Brandl, Bernhard, additional, Brechignac, Philippe, additional, Brünken, Sandra, additional, Buragohain, Mridusmita, additional, Burkhardt, Andrew, additional, Candian, Alessandra, additional, Cazaux, Stéphanie, additional, Cernicharo, Jose, additional, Chabot, Marin, additional, Chakraborty, Shubhadip, additional, Champion, Jason, additional, Colgan, Sean W. J., additional, Cooke, Ilsa R., additional, Coutens, Audrey, additional, Cox, Nick L. J., additional, Demyk, Karine, additional, Meyer, Jennifer Donovan, additional, Foschino, Sacha, additional, García-Lario, Pedro, additional, Gerin, Maryvonne, additional, Gottlieb, Carl A., additional, Guillard, Pierre, additional, Gusdorf, Antoine, additional, Hartigan, Patrick, additional, He, Jinhua, additional, Herbst, Eric, additional, Hornekaer, Liv, additional, Jäger, Cornelia, additional, Janot-Pacheco, Eduardo, additional, Kaufman, Michael, additional, Kendrew, Sarah, additional, Kirsanova, Maria S., additional, Klaassen, Pamela, additional, Kwok, Sun, additional, Labiano, Álvaro, additional, Lai, Thomas S.-Y., additional, Lee, Timothy J., additional, Lefloch, Bertrand, additional, Le Petit, Franck, additional, Li, Aigen, additional, Linz, Hendrik, additional, Mackie, Cameron J., additional, Madden, Suzanne C., additional, Mascetti, Joëlle, additional, McGuire, Brett A., additional, Merino, Pablo, additional, Micelotta, Elisabetta R., additional, Misselt, Karl, additional, Morse, Jon A., additional, Mulas, Giacomo, additional, Neelamkodan, Naslim, additional, Ohsawa, Ryou, additional, Paladini, Roberta, additional, Palumbo, Maria Elisabetta, additional, Pathak, Amit, additional, Pendleton, Yvonne J., additional, Petrignani, Annemieke, additional, Pino, Thomas, additional, Puga, Elena, additional, Rangwala, Naseem, additional, Rapacioli, Mathias, additional, Ricca, Alessandra, additional, Roman-Duval, Julia, additional, Roser, Joseph, additional, Roueff, Evelyne, additional, Rouillé, Gaël, additional, Salama, Farid, additional, Sales, Dinalva A., additional, Sandstrom, Karin, additional, Sarre, Peter, additional, Sciamma-O’Brien, Ella, additional, Sellgren, Kris, additional, Shenoy, Sachindev S., additional, Teyssier, David, additional, Thomas, Richard D., additional, Togi, Aditya, additional, Verstraete, Laurent, additional, Witt, Adolf N., additional, Wootten, Alwyn, additional, Ysard, Nathalie, additional, Zettergren, Henning, additional, Zhang, Yong, additional, Zhang, Ziwei E., additional, and Zhen, Junfeng, additional

Published
2024
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10. Mutual Neutralization of NO plus with O

Author

Poline, Mathias, Dochain, Arnaud, Rosén, Stefan, Ji, MingChao, Reinhed, Peter, Simonsson, Ansgar, Larsson, Mats, Schmidt, Henning T., Zettergren, Henning, Thomas, Richard D., Ard, Shaun G., Shuman, Nicholas S., Viggiano, Albert A., Poline, Mathias, Dochain, Arnaud, Rosén, Stefan, Ji, MingChao, Reinhed, Peter, Simonsson, Ansgar, Larsson, Mats, Schmidt, Henning T., Zettergren, Henning, Thomas, Richard D., Ard, Shaun G., Shuman, Nicholas S., and Viggiano, Albert A.

Abstract

We have studied the mutual neutralization reaction of vibronically cold NO+ with O- at a collision energy of approximate to 0.1 eV and under single-collision conditions. The reaction is completely dominated by production of three ground-state atomic fragments. We employ product-momentum analysis in the framework of a simple model, which assumes the anion acts only as an electron donor and the product neutral molecule acts as a free rotor, to conclude that the process occurs in a two-step mechanism via an intermediate Rydberg state of NO which subsequently fragments.

Published
2024
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11. The mutual neutralization of hydronium and hydroxide

Author

Bogot, Alon, Poline, Mathias, Ji, MingChao, Dochain, Arnaud, Simonsson, Ansgar, Rosén, Stefan, Zettergren, Henning, Schmidt, Henning T., Thomas, Richard D., Strasser, Daniel, Bogot, Alon, Poline, Mathias, Ji, MingChao, Dochain, Arnaud, Simonsson, Ansgar, Rosén, Stefan, Zettergren, Henning, Schmidt, Henning T., Thomas, Richard D., and Strasser, Daniel

Abstract

Mutual neutralization of hydronium (H3O+) and hydroxide (OH−) ions is a very fundamental chemical reaction. Yet, there is only limited experimental evidence about the underlying reaction mechanisms. Here, we report three-dimensional imaging of coincident neutral products of mutual-neutralization reactions at low collision energies of cold and isolated ions in the cryogenic double electrostatic ion-beam storage ring (DESIREE). We identified predominant H2O + OH + H and 2OH + H2 product channels and attributed them to an electron-transfer mechanism, whereas a minor contribution of H2O + H2O with high internal excitation was attributed to proton transfer. The reported mechanism-resolved internal product excitation, as well as collision-energy and initial ion-temperature dependence, provide a benchmark for modeling charge-transfer mechanisms.

Published
2024
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12. A far-ultraviolet-driven photoevaporation flow observed in a protoplanetary disk

Author

Ministerio de Ciencia e Innovación (España), Centre National D'Etudes Spatiales (France), Université Pierre et Marie Curie, Institut Universitaire de France, Centre National de la Recherche Scientifique (France), Canadian Space Agency, Natural Sciences and Engineering Research Council of Canada, San Jose State University Research Foundation, National Aeronautics and Space Administration (US), Japan Society for the Promotion of Science, Royal Society (UK), United Arab Emirates University, National Natural Science Foundation of China, German Research Foundation, Department of Science and Technology (India), Chinese Academy of Sciences, Chinese Academy of Sciences South America Center for Astronomy, Swedish Research Council, #NODATA#, Berné, Olivier, Habart, Emilie, Peeters, Els, Schroetter, Ilane, Canin, Amélie, Sidhu, Ameek, Chown, Ryan, Bron, Emeric, Haworth, Thomas J., Klaassen, Pamela, Trahin, Boris, Abergel, Alain, Wootten, Alwyn, Ysard, Nathalie, Zettergren, Henning, Zhang, Yong, Zhang, Ziwei E., Zhen, Junfeng, Bergin, Edwin A., Bernard-Salas, Jeronimo, Boersma, Christiaan, Bera, Partha P., Cami, Jan, Cuadrado, Sara, Dartois, Emmanuel, Dicken, Daniel, Elyajouri, Meriem, Fuente, Asunción, Goicoechea, Javier R., Gordon, Karl D., Issa, Lina, Joblin, Christine, Black, John H, Kannavou, Olga, Khan, Baria, Lacinbala, Ozan, Languignon, David, Le Gal, Romane, Maragkoudakis, Alexandros, Meshaka, Raphael, Okada, Yoko, Onaka, Takashi, Pasquini, Sofia, Boulanger, Francois, Pound, Marc W., Robberto, Massimo, Röllig, Markus, Schefter, Bethany, Schirmer, Thiébaut, Simmer, Thomas, Tabone, Benoit, Tielens, Alexander G. G.M., Vicente, Sílvia, Wolfire, Mark G., Bouwman, Jordy, Aleman, Isabel, Allamandola, Louis, Auchettl, Rebecca, Baratta, Giuseppe Antonio, Baruteau, Clément, Bejaoui, Salma, Brandl, Bernhard, Brechignac, Philippe, Brünken, Sandra, Buragohain, Mridusmita, Burkhardt, Andrew, Candian, Alessandra, Le Petit, Franck, Cazaux, Stéphanie, Cernicharo, José, Chabot, Marin, Chakraborty, Shubhadip, Champion, Jason, Colgan, Sean W. J., Cooke, Ilsa R., Coutens, Audrey, Cox, Nick L J, Demyk, Karine, Li, Aigen, Meyer, Jennifer Donovan, Engrand, Cécile, Foschino, Sacha, García-Lario, Pedro, Gavilan, Lisseth, Gerin, Maryvonne, Godard, Marie, Gottlieb, Carl A., Guillard, Pierre, Gusdorf, Antoine, Linz, Hendrik, Hartigan, Patrick, He, Jinhua, Herbst, Eric, Hornekaer, Liv, Jäger, Cornelia, Janot-Pacheco, Eduardo, Kaufman, Michael, Kemper, Francisca, Kendrew, Sarah, Kirsanova, Maria S., Mackie, Cameron J., Knight, Collin, Kwok, Sun, Labiano, Álvaro, Lai, Thomas S.-Y., Lee, Timothy J., Lefloch, Bertrand, Madden, Suzanne C., Mascetti, Joëlle, McGuire, Brett A., Merino, Pablo, Micelotta, Elisabetta R., Morse, Jon A., Van De Putte, Dries, Mulas, Giacomo, Neelamkodan, Naslim, Ohsawa, Ryou, Paladini, Roberta, Palumbo, Maria Elisabetta, Pathak, Amit, Pendleton, Yvonne J., Petrignani, Annemieke, Pino, Thomas, Puga, Elena, Alarcón, Felipe, Rangwala, Naseem, Rapacioli, Mathias, Ricca, Alessandra, Roman-Duval, Julia, Roueff, Evelyne, Rouillé, Gaël, Salama, Farid, Sales, Dinalva A., Sandstrom, Karin, Sarre, Peter, Zannese, Marion, Sciamma-O'Brien, Ella, Sellgren, Kris, Shannon, Matthew J., Simonnin, Adrien, Shenoy, Sachindev S., Teyssier, David, Thomas, Richard D., Togi, Aditya, Verstraete, Laurent, Witt, Adolf N., Ministerio de Ciencia e Innovación (España), Centre National D'Etudes Spatiales (France), Université Pierre et Marie Curie, Institut Universitaire de France, Centre National de la Recherche Scientifique (France), Canadian Space Agency, Natural Sciences and Engineering Research Council of Canada, San Jose State University Research Foundation, National Aeronautics and Space Administration (US), Japan Society for the Promotion of Science, Royal Society (UK), United Arab Emirates University, National Natural Science Foundation of China, German Research Foundation, Department of Science and Technology (India), Chinese Academy of Sciences, Chinese Academy of Sciences South America Center for Astronomy, Swedish Research Council, #NODATA#, Berné, Olivier, Habart, Emilie, Peeters, Els, Schroetter, Ilane, Canin, Amélie, Sidhu, Ameek, Chown, Ryan, Bron, Emeric, Haworth, Thomas J., Klaassen, Pamela, Trahin, Boris, Abergel, Alain, Wootten, Alwyn, Ysard, Nathalie, Zettergren, Henning, Zhang, Yong, Zhang, Ziwei E., Zhen, Junfeng, Bergin, Edwin A., Bernard-Salas, Jeronimo, Boersma, Christiaan, Bera, Partha P., Cami, Jan, Cuadrado, Sara, Dartois, Emmanuel, Dicken, Daniel, Elyajouri, Meriem, Fuente, Asunción, Goicoechea, Javier R., Gordon, Karl D., Issa, Lina, Joblin, Christine, Black, John H, Kannavou, Olga, Khan, Baria, Lacinbala, Ozan, Languignon, David, Le Gal, Romane, Maragkoudakis, Alexandros, Meshaka, Raphael, Okada, Yoko, Onaka, Takashi, Pasquini, Sofia, Boulanger, Francois, Pound, Marc W., Robberto, Massimo, Röllig, Markus, Schefter, Bethany, Schirmer, Thiébaut, Simmer, Thomas, Tabone, Benoit, Tielens, Alexander G. G.M., Vicente, Sílvia, Wolfire, Mark G., Bouwman, Jordy, Aleman, Isabel, Allamandola, Louis, Auchettl, Rebecca, Baratta, Giuseppe Antonio, Baruteau, Clément, Bejaoui, Salma, Brandl, Bernhard, Brechignac, Philippe, Brünken, Sandra, Buragohain, Mridusmita, Burkhardt, Andrew, Candian, Alessandra, Le Petit, Franck, Cazaux, Stéphanie, Cernicharo, José, Chabot, Marin, Chakraborty, Shubhadip, Champion, Jason, Colgan, Sean W. J., Cooke, Ilsa R., Coutens, Audrey, Cox, Nick L J, Demyk, Karine, Li, Aigen, Meyer, Jennifer Donovan, Engrand, Cécile, Foschino, Sacha, García-Lario, Pedro, Gavilan, Lisseth, Gerin, Maryvonne, Godard, Marie, Gottlieb, Carl A., Guillard, Pierre, Gusdorf, Antoine, Linz, Hendrik, Hartigan, Patrick, He, Jinhua, Herbst, Eric, Hornekaer, Liv, Jäger, Cornelia, Janot-Pacheco, Eduardo, Kaufman, Michael, Kemper, Francisca, Kendrew, Sarah, Kirsanova, Maria S., Mackie, Cameron J., Knight, Collin, Kwok, Sun, Labiano, Álvaro, Lai, Thomas S.-Y., Lee, Timothy J., Lefloch, Bertrand, Madden, Suzanne C., Mascetti, Joëlle, McGuire, Brett A., Merino, Pablo, Micelotta, Elisabetta R., Morse, Jon A., Van De Putte, Dries, Mulas, Giacomo, Neelamkodan, Naslim, Ohsawa, Ryou, Paladini, Roberta, Palumbo, Maria Elisabetta, Pathak, Amit, Pendleton, Yvonne J., Petrignani, Annemieke, Pino, Thomas, Puga, Elena, Alarcón, Felipe, Rangwala, Naseem, Rapacioli, Mathias, Ricca, Alessandra, Roman-Duval, Julia, Roueff, Evelyne, Rouillé, Gaël, Salama, Farid, Sales, Dinalva A., Sandstrom, Karin, Sarre, Peter, Zannese, Marion, Sciamma-O'Brien, Ella, Sellgren, Kris, Shannon, Matthew J., Simonnin, Adrien, Shenoy, Sachindev S., Teyssier, David, Thomas, Richard D., Togi, Aditya, Verstraete, Laurent, and Witt, Adolf N.

Abstract

Most low-mass stars form in stellar clusters that also contain massive stars, which are sources of far-ultraviolet (FUV) radiation. Theoretical models predict that this FUV radiation produces photodissociation regions (PDRs) on the surfaces of protoplanetary disks around low-mass stars, which affects planet formation within the disks. We report James Webb Space Telescope and Atacama Large Millimeter Array observations of a FUV-irradiated protoplanetary disk in the Orion Nebula. Emission lines are detected from the PDR; modeling their kinematics and excitation allowed us to constrain the physical conditions within the gas. We quantified the mass-loss rate induced by the FUV irradiation and found that it is sufficient to remove gas from the disk in less than a million years. This is rapid enough to affect giant planet formation in the disk.

Published
2024

13. The mutual neutralization of hydronium and hydroxide

Author

Bogot, Alon, primary, Poline, Mathias, additional, Ji, MingChao, additional, Dochain, Arnaud, additional, Simonsson, Ansgar, additional, Rosén, Stefan, additional, Zettergren, Henning, additional, Schmidt, Henning T., additional, Thomas, Richard D., additional, and Strasser, Daniel, additional

Published
2024
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14. Stability and Cooling of the C2−7 Dianion

Author

Najeeb, P. K., Stockett, Mark H., Anderson, Emma K., Kristiansson, Moa, Reinhed, Peter, Simonsson, Ansgar, Rosén, Stefan, Thomas, Richard D., Chartkunchand, K. C., Gnaser, H., Golser, R., Hanstorp, D., Larson, Åsa, Cederquist, Henrik, Schmidt, Henning T., Zettergren, Henning, Najeeb, P. K., Stockett, Mark H., Anderson, Emma K., Kristiansson, Moa, Reinhed, Peter, Simonsson, Ansgar, Rosén, Stefan, Thomas, Richard D., Chartkunchand, K. C., Gnaser, H., Golser, R., Hanstorp, D., Larson, Åsa, Cederquist, Henrik, Schmidt, Henning T., and Zettergren, Henning

Abstract

We have studied the stability of the smallest long-lived all carbon molecular dianion () in new time domains and with a single ion at a time using a cryogenic electrostatic ion-beam storage ring. We observe spontaneous electron emission from internally excited dianions on millisecond timescales and monitor the survival of single colder molecules on much longer timescales. We find that their intrinsic lifetime exceeds several minutes—6 orders of magnitude longer than established from earlier experiments on . This is consistent with our calculations of vertical electron detachment energies predicting one inherently stable isomer and one isomer which is stable or effectively stable behind a large Coulomb barrier for →+e− separation.

Published
2023
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17. Competition between ring-puckering and ring-opening excited state reactions exemplified on 5H-furan-2-one and derivatives.

Author

Schalk, Oliver, Galiana, Joachim, Geng, Ting, Larsson, Tobias L., Thomas, Richard D., Fdez. Galván, Ignacio, Hansson, Tony, and Vacher, Morgane

Subjects
EXCITED states, RING-opening reactions, PHOTOELECTRON spectroscopy, WAVE packets, TIME-resolved spectroscopy, MOLECULAR dynamics, QUANTUM dot synthesis, ISOTOPOLOGUES
Abstract

The influence of ring-puckering on the light-induced ring-opening dynamics of heterocyclic compounds was studied on the sample 5-membered ring molecules γ-valerolactone and 5H-furan-2-one using time-resolved photoelectron spectroscopy and ab initio molecular dynamics simulations. In γ-valerolactone, ring-puckering is not a viable relaxation channel and the only available reaction pathway is ring-opening, which occurs within one vibrational period along the C—O bond. In 5H-furan-2-one, the C=C double bond in the ring allows for ring-puckering which slows down the ring-opening process by about 150 fs while only marginally reducing its quantum yield. This demonstrates that ring-puckering is an ultrafast process, which is directly accessible upon excitation and which spreads the excited state wave packet quickly enough to influence even the outcome of an otherwise expectedly direct ring-opening reaction. [ABSTRACT FROM AUTHOR]

Published
2020
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19. Final-state-resolved mutual neutralization in I+ - I− collisions

Author

Poline, Mathias, Yuan, Xiang, Badin, Sylvain, Ji, Mingchao, Rosén, Stefan, Indrajith, Suvasthika, Thomas, Richard D, Schmidt, Henning, Zettergren, Henning, Severo Pereira Gomes, André, Sisourat, Nicolas, Department of Physics [Stockholm], Stockholm University, Laboratoire de Physique des Lasers, Atomes et Molécules - UMR 8523 (PhLAM), Université de Lille-Centre National de la Recherche Scientifique (CNRS), Physico-Chimie Moléculaire Théorique (PCMT), Université de Lille-Centre National de la Recherche Scientifique (CNRS)-Université de Lille-Centre National de la Recherche Scientifique (CNRS), Department of Theoretical Chemistry and Amsterdam Center for Multiscale Modeling, Vrije Universiteit Amsterdam [Amsterdam] (VU), Laboratoire de Chimie Physique - Matière et Rayonnement (LCPMR), Institut de Chimie du CNRS (INC)-Sorbonne Université (SU)-Centre National de la Recherche Scientifique (CNRS), Theoretical Chemistry, ANR-16-IDEX-0004,ULNE,ULNE(2016), Department of Theoretical Chemistry and Amsterdam Centre for Multiscale Modeling (ACMM) VU University Amsterdam (ACMM), MESONM International Associated Laboratory (LAI, Grant No. ANR-16-IDEX-0004), French national supercomputing facilities (Grant No. DARI A0090801859), DESIREE (Swedish Research Council Contracts No. 2017-00621 and No. 2021-00155), Project 'Probing charge- and mass- transfer reactions on the atomic level,' supported by the Knut and Alice Wallenberg Foundation (Grant No. 2018.0028), COST Action (CA18212)-Molecular Dynamics in the GAS phase (MD- GAS), supported by COST (European Cooperation in Science and Technology)., Swedish Research Council (Contracts No. 2018-04092 and No. 2020-03437), This material is based upon work supported by the Air Force Office of Scientific Research under Award No. FA9550-19-1-7012 (R.D.T.)., and ANR-11-LABX-0005,Cappa,Physiques et Chimie de l'Environnement Atmosphérique(2011)

Subjects
[CHIM.THEO]Chemical Sciences/Theoretical and/or physical chemistry, [PHYS.PHYS]Physics [physics]/Physics [physics], [CHIM]Chemical Sciences, SDG 7 - Affordable and Clean Energy
Abstract

International audience; We have studied the mutual neutralization reaction of atomic iodine ions (i.e., I++I−→I+I) in a cryogenic double electrostatic ion-beam storage-ring apparatus. Our results show that the reaction forms iodine atoms either in the ground-state configuration (I(5p5 2P0), ∼40%) or with one atom in an electronically excited state (I(6s2 [2]), ∼60%), with no significant variation over the branching ratios in the studied collision-energy range (0.1–0.8 eV). We estimate the total charge-transfer cross section to be of the order of 10-13cm2 at 0.1 eV collision energy. Ab initio relativistic electronic structure calculations of the potential-energy curves of I2 suggest that the reaction takes place at short internuclear distances. The results are discussed in view of their importance for applications in electric thrusters.

Published
2022
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20. A field ionizer for photodetachment studies of negative ions

Author

Welander, J., Navarro Navarrete, J. E., Rohlén, J., Leopold, T., Thomas, Richard D., Pegg, D. J., Hanstorp, D., Welander, J., Navarro Navarrete, J. E., Rohlén, J., Leopold, T., Thomas, Richard D., Pegg, D. J., and Hanstorp, D.

Abstract

In this paper, we present an apparatus for studies into the photodetachment process of atomic negative ions. State-selective detection of the residual atom following the initial photodetachment step is achieved by combining resonant laser excitation of the photo-detached atom with electric field ionization. The resonance ionization technique in combination with a co-linear ion–laser beam geometry gives an experimental apparatus that has both high selectivity and sensitivity. In addition to measurements of a single selected partial photodetachment channel, the apparatus also can be used to study a manifold of photodetachment channels in which the residual atom is left in a high-lying Rydberg state and for investigation of the double electron-detachment process. Ion-optical simulations in SIMION are used to illustrate the operation of the apparatus for studying such processes. Successful performance of the apparatus against the simulation is demonstrated by a high resolution study of the photodetachment of cesium, where the sharp s-wave threshold of the photodetachment processes leaving the residual atom in the excited 6p state was investigated.

Published
2022
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21. Storage-ring study of the mutual neutralization of N+ with O−

Author

Poline, Mathias, primary, Rosén, Stefan, additional, Ji, MingChao, additional, Simonsson, Ansgar, additional, Reinhed, Peter, additional, Larsson, Mats, additional, Schmidt, Henning T., additional, Thomas, Richard D., additional, Dochain, Arnaud, additional, Urbain, Xavier, additional, Grumer, Jon, additional, Barklem, Paul S., additional, Ard, Shaun G., additional, Shuman, Nicholas S., additional, and Viggiano, Albert A., additional

Published
2022
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22. PDRs4All: A JWST Early Release Science Program on Radiative Feedback from Massive Stars

Author

Berné, Olivier, additional, Habart, Émilie, additional, Peeters, Els, additional, Abergel, Alain, additional, Bergin, Edwin A., additional, Bernard-Salas, Jeronimo, additional, Bron, Emeric, additional, Cami, Jan, additional, Dartois, Emmanuel, additional, Fuente, Asunción, additional, Goicoechea, Javier R., additional, Gordon, Karl D., additional, Okada, Yoko, additional, Onaka, Takashi, additional, Robberto, Massimo, additional, Röllig, Markus, additional, Tielens, Alexander G. G. M., additional, Vicente, Sílvia, additional, Wolfire, Mark G., additional, Alarcón, Felipe, additional, Boersma, C., additional, Canin, Amélie, additional, Chown, Ryan, additional, Dicken, Daniel, additional, Languignon, David, additional, Le Gal, Romane, additional, Pound, Marc W., additional, Trahin, Boris, additional, Simmer, Thomas, additional, Sidhu, Ameek, additional, Van De Putte, Dries, additional, Cuadrado, Sara, additional, Guilloteau, Claire, additional, Maragkoudakis, Alexandros, additional, Schefter, Bethany R., additional, Schirmer, Thiébaut, additional, Cazaux, Stéphanie, additional, Aleman, Isabel, additional, Allamandola, Louis, additional, Auchettl, Rebecca, additional, Antonio Baratta, Giuseppe, additional, Bejaoui, Salma, additional, Bera, Partha P., additional, Bilalbegović, Goranka, additional, Black, John H., additional, Boulanger, Francois, additional, Bouwman, Jordy, additional, Brandl, Bernhard, additional, Brechignac, Philippe, additional, Brünken, Sandra, additional, Burkhardt, Andrew, additional, Candian, Alessandra, additional, Cernicharo, Jose, additional, Chabot, Marin, additional, Chakraborty, Shubhadip, additional, Champion, Jason, additional, Colgan, Sean W. J., additional, Cooke, Ilsa R., additional, Coutens, Audrey, additional, Cox, Nick L. J., additional, Demyk, Karine, additional, Donovan Meyer, Jennifer, additional, Engrand, Cécile, additional, Foschino, Sacha, additional, García-Lario, Pedro, additional, Gavilan, Lisseth, additional, Gerin, Maryvonne, additional, Godard, Marie, additional, Gottlieb, Carl A., additional, Guillard, Pierre, additional, Gusdorf, Antoine, additional, Hartigan, Patrick, additional, He, Jinhua, additional, Herbst, Eric, additional, Hornekaer, Liv, additional, Jäger, Cornelia, additional, Janot-Pacheco, Eduardo, additional, Joblin, Christine, additional, Kaufman, Michael, additional, Kemper, Francisca, additional, Kendrew, Sarah, additional, Kirsanova, Maria S., additional, Klaassen, Pamela, additional, Knight, Collin, additional, Kwok, Sun, additional, Labiano, Álvaro, additional, Lai, Thomas S.-Y., additional, Lee, Timothy J., additional, Lefloch, Bertrand, additional, Le Petit, Franck, additional, Li, Aigen, additional, Linz, Hendrik, additional, Mackie, Cameron J., additional, Madden, Suzanne C., additional, Mascetti, Joëlle, additional, McGuire, Brett A., additional, Merino, Pablo, additional, Micelotta, Elisabetta R., additional, Misselt, Karl, additional, Morse, Jon A., additional, Mulas, Giacomo, additional, Neelamkodan, Naslim, additional, Ohsawa, Ryou, additional, Omont, Alain, additional, Paladini, Roberta, additional, Elisabetta Palumbo, Maria, additional, Pathak, Amit, additional, Pendleton, Yvonne J., additional, Petrignani, Annemieke, additional, Pino, Thomas, additional, Puga, Elena, additional, Rangwala, Naseem, additional, Rapacioli, Mathias, additional, Ricca, Alessandra, additional, Roman-Duval, Julia, additional, Roser, Joseph, additional, Roueff, Evelyne, additional, Rouillé, Gaël, additional, Salama, Farid, additional, Sales, Dinalva A., additional, Sandstrom, Karin, additional, Sarre, Peter, additional, Sciamma-O’Brien, Ella, additional, Sellgren, Kris, additional, Shannon, Matthew J., additional, Shenoy, Sachindev S., additional, Teyssier, David, additional, Thomas, Richard D., additional, Togi, Aditya, additional, Verstraete, Laurent, additional, Witt, Adolf N., additional, Wootten, Alwyn, additional, Ysard, Nathalie, additional, Zettergren, Henning, additional, Zhang, Yong, additional, Zhang, Ziwei E., additional, and Zhen, Junfeng, additional

Published
2022
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23. Clinical and radiographic predictors of the need for facial CT in pediatric blunt trauma: a multi-institutional study

Author

Nguyen, Brittany N, primary, Edwards, Mary J, additional, Srivatsa, Shachi, additional, Wakeman, Derek, additional, Calderon, Thais, additional, Lamoshi, Abdularouf, additional, Wallenstein, Kim, additional, Fabiano, Tiffany, additional, Cantor, Brittany, additional, Bass, Kathryn, additional, Narayan, Ananth, additional, Zohn, Ralph, additional, Chess, Mitchell, additional, and Thomas, Richard D, additional

Published
2022
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24. Double-core-hole spectroscopy for chemical analysis with an intense X-ray femtosecond laser

Author

Berrah, Nora, Fang, Li, Murphy, Brendan, Osipov, Timur, Ueda, Kiyoshi, Kukk, Edwin, Feifel, Raimund, van der Meulen, Peter, Salen, Peter, Schmidt, Henning T., Thomas, Richard D., Larsson, Mats, Richter, Robert, Prince, Kevin C., Bozek, John D., Bostedt, Christoph, Wada, Shin-ichi, Piancastelli, Maria N., Tashiro, Motomichi, and Ehara, Masahiro

Published
2011

25. Storage-ring study of the mutual neutralization of N+ with O

Author

Poline, Mathias, Rosén, Stefan, Ji, MingChao, Simonsson, Ansgar, Reinhed, Peter, Larsson, Mats, Schmidt, Henning T., Thomas, Richard D., Dochain, Arnaud, Urbain, Xavier, Grumer, Jon, Barklem, Paul S., Ard, Shaun G., Shuman, Nicholas S., Viggiano, Albert A., and UCL - SST/IMCN/NAPS - Nanoscopic Physics

Abstract

The double ion storage ring DESIREE has been used in combination with position- and time-sensitive detectors to study the mutual neutralization of N+ with O− at 40 meV collision energy. Several previously unassigned spectral features observed in a recent single-pass merged-beams experiment at 7 meV collision energy [Phys. Rev. Lett. 121, 083401 (2018)], were also observed in the present experiment. It was found that neutralization channels of the first metastable state of the cation [N+(1D), τ ≈ 256 s] could explain the majority of these features, while the second metastable state [N+(1S), τ ≈ 0.9 s] was not found to contribute significantly. The branching ratios into the different electronically excited states of N were determined and found to be in good agreement between the two experiments. Theoretical calculations using the multichannel Landau-Zener model were found to yield good results for a number of channels, but could not describe some observed contributions, possibly due to the presence of other processes not accounted for in the model.

Published
2022

26. Storage-ring study of the mutual neutralization of N plus with O minus

Author

Poline, Mathias, Rosen, Stefan, Ji, MingChao, Simonsson, Ansgar, Reinhed, Peter, Larsson, Mats, Schmidt, Henning T., Thomas, Richard D., Dochain, Arnaud, Urbain, Xavier, Grumer, Jon, Barklem, Paul, Ard, Shaun G., Shuman, Nicholas S., and Viggiano, Albert A.

Subjects
Atom and Molecular Physics and Optics, Atom- och molekylfysik och optik
Abstract

The double ion storage ring DESIREE has been used in combination with position- and time-sensitive detectors to study the mutual neutralization of N+ with O- at 40 meV collision energy. Several previously unassigned spectral features observed in a recent single-pass merged-beams experiment at 7 meV collision energy [Phys. Rev. Lett. 121, 083401 (2018)], were also observed in the present experiment. It was found that neutralization channels of the first metastable state of the cation [N+(1D), τ≈ 256 s] could explain the majority of these features, while the second metastable state [N+(1S), τ≈ 0.9 s] was not found to contribute significantly. The branching ratios into the different electronically excited states of N were determined and found to be in good agreement between the two experiments. Theoretical calculations using the multichannel Landau-Zener model were found to yield good results for a number of channels, but could not describe some observed contributions, possibly due to the presence of other processes not accounted for in the model.

Published
2022

30. Final-state-resolved mutual neutralization of Na+ and D

Author

Eklund, Gustav, Grumer, Jon, Barklem, Paul, Rosen, Stefan, Ji, MingChao, Simonsson, Ansgar, Thomas, Richard D., Cederquist, Henrik, Zettergren, Henning, and Schmidt, Henning T.

Subjects
Astronomi, astrofysik och kosmologi, Atom and Molecular Physics and Optics, Astronomy, Astrophysics and Cosmology, Atom- och molekylfysik och optik, Acceleratorfysik och instrumentering, Accelerator Physics and Instrumentation
Abstract

The present paper reports on a merged-beam experiment on mutual neutralization between Na+ and D-. For this experiment, we have used the DESIREE ion-beams storage-ring facility. The reaction products are detected using a position- and time-sensitive detector, which ideally allows for determination of the population of each individual quantum state in the final atomic systems. Here, the 4s, 3d, and 4p final states in Na are observed and in all cases the D atom is in its ground state 1s S-2. The respective branching fractions of the states populated in Na are determined by fitting results from a Monte Carlo simulation of the experiment to the measured data. The center-of-mass collision energy is controlled using a set of biased drift tubes, and the branching fractions are measured for energies between 80 meV and 393 meV. The resulting branching fractions are found to agree qualitatively with the only available theoretical calculations for this particular system, which are based on a multichannel Landau-Zener approach using dynamic couplings determined with a linear combination of atomic orbitals model.

Published
2021

31. Mutual neutralisation of O+ with O−: investigation of the role of metastable ions in a combined experimental and theoretical study

Author

Poline, Mathias, Dochain, Arnaud, Rosén, Stefan, Grumer, Jon, Ji, MingChao, Eklund, Gustav, Simonsson, Ansgar, Reinhed, Peter, Blom, Mikael, Shuman, Nicholas S., Ard, Shaun G., Viggiano, Albert A., Larsson, Mats, Cederquist, Henrik, Schmidt, Henning T., Zettergren, Henning, Urbain, Xavier, Barklem, Paul S., Thomas, Richard D., Poline, Mathias, Dochain, Arnaud, Rosén, Stefan, Grumer, Jon, Ji, MingChao, Eklund, Gustav, Simonsson, Ansgar, Reinhed, Peter, Blom, Mikael, Shuman, Nicholas S., Ard, Shaun G., Viggiano, Albert A., Larsson, Mats, Cederquist, Henrik, Schmidt, Henning T., Zettergren, Henning, Urbain, Xavier, Barklem, Paul S., and Thomas, Richard D.

Published
2021
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32. Mutual neutralisation of O+ with O−: investigation of the role of metastable ions in a combined experimental and theoretical study

Author

UCL - SST/IMCN/NAPS - Nanoscopic Physics, Poline, Mathias, Dochain, Arnaud, Rosén, Stefan, Grumer, Jon, Ji, MingChao, Eklund, Gustav, Simonsson, Ansgar, Reinhed, Peter, Blom, Mikael, Shuman, Nicholas S., Ard, Shaun G., Viggiano, Albert A., Larsson, Mats, Cederquist, Henrik, Schmidt, Henning T., Zettergren, Henning, Urbain, Xavier, Barklem, Paul S., Thomas, Richard D., UCL - SST/IMCN/NAPS - Nanoscopic Physics, Poline, Mathias, Dochain, Arnaud, Rosén, Stefan, Grumer, Jon, Ji, MingChao, Eklund, Gustav, Simonsson, Ansgar, Reinhed, Peter, Blom, Mikael, Shuman, Nicholas S., Ard, Shaun G., Viggiano, Albert A., Larsson, Mats, Cederquist, Henrik, Schmidt, Henning T., Zettergren, Henning, Urbain, Xavier, Barklem, Paul S., and Thomas, Richard D.

Abstract

The mutual neutralisation of O+ with O- has been studied in a double ion-beam storage ring with combined merged-beams, imaging and timing techniques. Branching ratios were measured at the collision energies of 55, 75 and 170 (_15) meV, and found to be in good agreement with previous single-pass merged-beams experimental results at 7 meV collision energy1. Several previously unidentified spectral features were found to correspond to mutual neutralisation channels of the first metastable state of the cation (O+(2Do), t _ 3.6 hours), while no contributions from the second metastable state (O+(2Po), t _ 5 seconds) were observed. Theoretical calculations were performed using the multi-channel Landau-Zener model combined with the anion centered asymptotic method, and gave good agreement with several experimentally observed channels, but could not describe well observed contributions from the O+(2Do) metastable state as well as channels involving the O(3s 5So) state.

Published
2021

33. Acetabula Osteoid Osteoma Mimicking Juvenile Idiopathic Arthritis and Chronic Recurrent Multifocal Osteomyelitis

Author

Abd El Baky, Hend, Thomas, Richard D., Kuechle, Joseph, and Abdul-Aziz, Rabheh

Subjects
musculoskeletal diseases, Article Subject
Abstract

Osteoid osteoma (OO) is a benign bone tumor that usually presents between 10 and 35 years of age. The metaphysis and diaphysis of the femur and tibia are the typical locations. The diagnosis is usually straightforward when images reveal a radiolucent nidus surrounded by reactive sclerosis. However, the diagnosis is more difficult when it occurs at atypical locations with nonspecific and misleading appearance on images. OO may mimic juvenile idiopathic arthritis (JIA), bone infection, or malignancy. We present a 14-year-old male with a 4-month history of left hip pain. His pain was worse with playing hockey and lacrosse and in the morning and sometimes woke him up at night. His examination was significant for pain with flexion and external rotation of the left hip and for mild limitation of full external rotation. Blood work revealed normal complete blood count, erythrocyte sedimentation rate, and C-reactive protein. Left hip X-ray was unremarkable. Left hip MR arthrogram showed marked edema of the medial and posterior walls of the left acetabulum. CT-guided biopsy of the left acetabulum showed unremarkable flow cytometry and chronic inflammatory component raising concern about chronic recurrent multifocal osteomyelitis (CRMO). Bone scan revealed focal increased uptake in the left acetabulum and no additional abnormality. Repeat MRI with intravenous contrast showed a left hip effusion, focal synovial enhancement in the medial left hip, and acetabula edema. The patient failed treatment for presumed JIA and CRMO with nonsteroidal anti-inflammatory drugs (NSAIDs), steroids, methotrexate, and adalimumab. CT scan of the left hip was performed for further evaluation of the bone and showed 11 × 6 mm low attenuation focus with subtle internal nidus in the posteromedial aspect of the acetabular rim, suggestive of intra-articular OO. Radiofrequency ablation was performed with no complications, and the left hip pain improved. The atypical location resulted in delay of diagnosis for 12 months after presentation. We highlight the diagnostic pitfalls observed in atypical OO locations and the difficulties this creates with making the diagnosis. OO mimicking JIA has previously been described. We submit CRMO as another differential diagnosis which may be mimicked and demonstrate the vital role of CT scan in the diagnosis.

Published
2020
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34. Cryogenic merged-ion-beam experiments in DESIREE : Final-state-resolved mutual neutralization of Li+ and D

Author

Eklund, Gustav, Grumer, Jon, Rosen, Stefan, Ji, MingChao, Punnakayathil, Najeeb, Kallberg, Anders, Simonsson, Ansgar, Thomas, Richard D., Stockett, Mark H., Reinhed, Peter, Lofgren, Patrik, Bjorkhage, Mikael, Blom, Mikael, Barklem, Paul S., Cederquist, Henrik, Zettergren, Henning, Schmidt, Henning T., Eklund, Gustav, Grumer, Jon, Rosen, Stefan, Ji, MingChao, Punnakayathil, Najeeb, Kallberg, Anders, Simonsson, Ansgar, Thomas, Richard D., Stockett, Mark H., Reinhed, Peter, Lofgren, Patrik, Bjorkhage, Mikael, Blom, Mikael, Barklem, Paul S., Cederquist, Henrik, Zettergren, Henning, and Schmidt, Henning T.

Abstract

We have developed an experimental technique to study charge-and energy-flow processes in sub-eV collisions between oppositely charged, internally cold, ions of atoms, molecules, and clusters. Two ion beams are stored in separate rings of the cryogenic ion-beam storage facility DESIREE, and merged in a common straight section where a set of biased drift tubes is used to control the center-of-mass collision energy locally in fine steps. Here, we present measurements on mutual neutralization between Li+ and D- where a time-sensitive imaging-detector system is used to measure the three-dimensional distance between the neutral Li and D atoms as they reach the detector. This scheme allows for direct measurements of kinetic-energy releases, and here it reveals separate populations of the 3s state and the (3p + 3d) states in neutral Li while the D atom is left in its ground state 1s. The branching fraction of the 3s final state is measured to be 57.8 +/- 0.7% at a center-of-mass collision energy of 78 +/- 13 meV. The technique paves the way for studies of charge-, energy-, and mass-transfer reactions in single collisions involving molecular and cluster ions in well-defined quantum states.

Published
2020
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35. Photoionization Dynamics of the Tetraoxo Complexes OsO4 and RuO4

Author

Schio, Luca, Alagia, Michele, Toffoli, Daniele, Decleva, Piero, Richter, Robert, Schalk, Oliver, Thomas, Richard D., Mucke, Melanie, Salvador, Federico, Bertoch, Paolo, Benedetti, Davide, Dri, Carlo, Cautero, Giuseppe, Sergo, Rudi, Stebel, Luigi, Vivoda, Davide, Stranges, Stefano, Schio, Luca, Alagia, Michele, Toffoli, Daniele, Decleva, Piero, Richter, Robert, Schalk, Oliver, Thomas, Richard D., Mucke, Melanie, Salvador, Federico, Bertoch, Paolo, Benedetti, Davide, Dri, Carlo, Cautero, Giuseppe, Sergo, Rudi, Stebel, Luigi, Vivoda, Davide, and Stranges, Stefano

Abstract

The photoionization dynamics of OsO4 and RuO4, chosen as model systems of small-size mononuclear heavy-metal complexes, has been theoretically studied by the time-dependent density functional theory (TDDFT). Accurate experimental measurements of photoionization dynamics as a benchmarking test for the theory are reported for the photoelectron asymmetry parameters of outer valence ionizations of OsO4, measured in the 17–90 eV photon energy range. The theoretical results are in good agreement with the available experimental data. The observed dynamical behavior of partial cross sections and asymmetry parameters has been related to both the coupling to the continuum of discrete excited states, giving strong modulations in the photon energy dependency, and the atomic composition of the initial ionized states, which determines the rate of decay of ionization probability for increasing excitation energies. Overall, an extensive analysis of the photoionization dynamics for valence and core orbitals is presented, showing good agreement with all the available experimental data. This provides confidence for the validity of the TDDFT approach in describing photoionization of heavy transition element compounds, with the perspective of being used for larger systems. Further experimental work is suggested for RuO4 to gather evidence of the sensitivity of the theoretical method to the nature of the metal atom.

Published
2020
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36. Final-state-resolved mutual neutralization of Na+ and D−

Author

Eklund, Gustav, Grumer, Jon, Barklem, Paul S, Rosén, Stefan, Ji, MingChao, Simonsson, Ansgar, Thomas, Richard D, Cederquist, Henrik, Zettergren, Henning, Schmidt, Henning T, Eklund, Gustav, Grumer, Jon, Barklem, Paul S, Rosén, Stefan, Ji, MingChao, Simonsson, Ansgar, Thomas, Richard D, Cederquist, Henrik, Zettergren, Henning, and Schmidt, Henning T

Published
2020

37. Non-covalently bonded diastereomeric adducts of amino acids and (S)-1-phenylethanol in low-energy dissociative collisions

Author

Rebrov, Oleksii, Poline, Mathias, Ryding, M. J., Thomas, Richard D., Uggerud, E., Larsson, Mats, Rebrov, Oleksii, Poline, Mathias, Ryding, M. J., Thomas, Richard D., Uggerud, E., and Larsson, Mats

Abstract

We have studied the collision induced dissociation reactions of proton-bound diastereomeric adducts of S-1-phenylethanol and enantiomers of three different amino acids (tryptophan, phenylalanine, methionine). In all cases, the loss of S-1-phenylethanol from the adduct ion is the only observed process, and the relative abundance is found to be independent of the chirality of the amino acid. This is in contrast to earlier experiments on the dissociation of protonated tryptophan-2-butanol adducts, where chirality affected the results. Results obtained from quantum chemical computations support and provide a rationale for the experimental observations and highlight temperature as a possible factor of importance for the chiral effect in these types of systems. [GRAPHICS] .

Published
2020
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38. Final-state-resolved mutual neutralization of Na+ and D−

Author

Eklund, Gustav, primary, Grumer, Jon, additional, Barklem, Paul S., additional, Rosén, Stefan, additional, Ji, MingChao, additional, Simonsson, Ansgar, additional, Thomas, Richard D., additional, Cederquist, Henrik, additional, Zettergren, Henning, additional, and Schmidt, Henning T., additional

Published
2021
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40. Mutual neutralisation of O+ with O-: Investigation of the role of metastable ions in a combined experimental and theoretical study

Author

Poline, Mathias, primary, Dochain, Arnaud, additional, Rosén, Stefan, additional, Grumer, Jon, additional, Ji, Mingchao, additional, Eklund, Gustav, additional, Simonsson, Ansgar, additional, Reinhed, Peter, additional, Blom, Mikael, additional, Shuman, Nicholas S., additional, Ard, Shaun G., additional, Viggiano, Albert A., additional, Larsson, Mats, additional, Cederquist, Henrik, additional, Schmidt, Henning, additional, Zettergren, Henning, additional, Urbain, Xavier, additional, Barklem, Paul S., additional, and Thomas, Richard D., additional

Published
2021
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41. Dynamics in higher lying excited states: Valence to Rydberg transitions in the relaxation paths of pyrrole and methylated derivatives.

Author

Ting Geng, Schalk, Oliver, Neville, Simon P., Hansson, Tony, and Thomas, Richard D.

Subjects
RYDBERG states, ATOMIC spectra, MOLECULAR shapes, PHOTOCHEMICAL curing, PHOTOELECTRON spectra
Abstract

The involvement of intermediate Rydberg states in the relaxation dynamics of small organic molecules which, after excitation to the valence manifold, also return to the valence manifold is rarely observed. We report here that such a transiently populated Rydberg state may offer the possibility to modify the outcome of a photochemical reaction. In a time resolved photoelectron study on pyrrole and its methylated derivatives, N-methyl pyrrole and 2,5-dimethyl pyrrole, 6.2 eV photons (200 nm) are used to excite these molecules into a bright ππ* state. In each case, a π3p-Rydberg state, either the B1(π3py) or theA2(π3pz) state, is populated within 20-50 fs after excitation. Thewavepacket then proceeds to the lower lyingA2(πσ*) state within a further 20 fs, at which point two competing reaction channels can be accessed: prompt N-H (N-CH3) bond cleavage or return to the ground state via a conical intersection accessed after ring puckering, the latter of which is predicted to require an additional 100-160 fs depending on the molecule. [ABSTRACT FROM AUTHOR]

Published
2017
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42. Cryogenic merged-ion-beam experiments in DESIREE: Final-state-resolved mutual neutralization of Li+ and D−

Author

Eklund, Gustav, primary, Grumer, Jon, additional, Rosén, Stefan, additional, Ji, MingChao, additional, Punnakayathil, Najeeb, additional, Källberg, Anders, additional, Simonsson, Ansgar, additional, Thomas, Richard D., additional, Stockett, Mark H., additional, Reinhed, Peter, additional, Löfgren, Patrik, additional, Björkhage, Mikael, additional, Blom, Mikael, additional, Barklem, Paul S., additional, Cederquist, Henrik, additional, Zettergren, Henning, additional, and Schmidt, Henning T., additional

Published
2020
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43. Photoionization Dynamics of the Tetraoxo Complexes OsO4 and RuO4

Author

Schio, Luca, primary, Alagia, Michele, additional, Toffoli, Daniele, additional, Decleva, Piero, additional, Richter, Robert, additional, Schalk, Oliver, additional, Thomas, Richard D., additional, Mucke, Melanie, additional, Salvador, Federico, additional, Bertoch, Paolo, additional, Benedetti, Davide, additional, Dri, Carlo, additional, Cautero, Giuseppe, additional, Sergo, Rudi, additional, Stebel, Luigi, additional, Vivoda, Davide, additional, and Stranges, Stefano, additional

Published
2020
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45. Excited state dynamics of acrylonitrile: Substituent effects at conical intersections interrogated via time-resolved photoelectron spectroscopy and ab initio simulation.

Author

MacDonell, Ryan J., Schalk, Oliver, Ting Geng, Thomas, Richard D., Feifel, Raimund, Hansson, Tony, and Schuurman, Michael S.

Subjects
EXCITED states, ACRYLONITRILE, SUBSTITUENTS (Chemistry), PHOTOELECTRON spectroscopy, VIBRONIC coupling, FEMTOSECOND pulses
Abstract

We report a joint experimental and theoretical study on the photoinitiated ultrafast dynamics of acrylonitrile (AN) and two methylated analogs: crotonitrile (CrN) and methacrylonitrile (MeAN). Time-resolved photoelectron spectroscopy (TRPES) and ab initio simulation are employed to discern the conical intersection mediated vibronic dynamics leading to relaxation to the ground electronic state. Each molecule is pumped with a femtosecond pulse at 200 nm and the ensuing wavepackets are probed by means of one and two photon ionization at 267 nm. The predominant vibrational motions involved in the de-excitation process, determined by ab initio trajectory simulations, are an initial twisting about the C=C axis followed by pyramidalization at a carbon atom. The decay of the time-resolved photoelectron signal for each molecule is characterized by exponential decay lifetimes for the passage back to the ground state of 60 ± 10, 86 ± 11, and 97 ± 9 fs for AN, CrN, and MeAN, respectively. As these results show, the excited state dynamics are sensitive to the choice of methylation site and the explanation for the observed trend may be found in the trajectory simulations. Specifically, since the pyramidalization motion leading to the conical intersection with the ground state is accompanied by the development of a partial negative charge at the central atom of the pyramidal group, the electron donation of the cyano group ensures that this occurs exclusively at the medial carbon atom. In this way, the donated electron density from the cyano group "directs" the wavepacket to a particular region of the intersection seam. The excellent agreement between the experimental and simulated TRPES spectra, the latter determined by employing trajectory simulations, demonstrates that this mechanistic picture is consistent with the spectroscopic results. [ABSTRACT FROM AUTHOR]

Published
2016
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46. Mutual neutralisation of O+ with O−: investigation of the role of metastable ions in a combined experimental and theoretical study.

Author

Poline, Mathias, Dochain, Arnaud, Rosén, Stefan, Grumer, Jon, Ji, MingChao, Eklund, Gustav, Simonsson, Ansgar, Reinhed, Peter, Blom, Mikael, Shuman, Nicholas S., Ard, Shaun G., Viggiano, Albert A., Larsson, Mats, Cederquist, Henrik, Schmidt, Henning T., Zettergren, Henning, Urbain, Xavier, Barklem, Paul S., and Thomas, Richard D.

Abstract

The mutual neutralisation of O+ with O− has been studied in a double ion-beam storage ring with combined merged-beams, imaging and timing techniques. Branching ratios were measured at the collision energies of 55, 75 and 170 (± 15) meV, and found to be in good agreement with previous single-pass merged-beams experimental results at 7 meV collision energy. Several previously unidentified spectral features were found to correspond to mutual neutralisation channels of the first metastable state of the cation (O+(2Do), τ ≈ 3.6 hours), while no contributions from the second metastable state (O+(2Po), τ ≈ 5 seconds) were observed. Theoretical calculations were performed using the multi-channel Landau–Zener model combined with the anion centered asymptotic method, and gave good agreement with several experimentally observed channels, but could not describe well observed contributions from the O+(2Do) metastable state as well as channels involving the O(3s 5So) state. [ABSTRACT FROM AUTHOR]

Published
2021
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48. Dissociation kinetics of excited ions : PEPICO measurements of Os3(CO)12 - The 7-35 eV single ionization binding energy region

Author

Schalk, Oliver, Josefsson, Ida, Geng, Ting, Richter, Robert, Sa'adeh, Hanan, Thomas, Richard D., Mucke, Melanie, Schalk, Oliver, Josefsson, Ida, Geng, Ting, Richter, Robert, Sa'adeh, Hanan, Thomas, Richard D., and Mucke, Melanie

Abstract

In this article, we study the photoinduced dissociation pathways of a metallocarbonyl, Os-3(CO)(12), in particular the consecutive loss of CO groups. To do so, we performed photoelectron-photoion coincidence (PEPICO) measurements in the single ionization binding energy region from 7 to 35 eV using 45-eV photons. Zero-energy ion appearance energies for the dissociation steps were extracted by modeling the PEPICO data using the statistical adiabatic channel model. Upon ionization to the excited ionic states above 13 eV binding energy, non-statistical behaviorwas observed and assigned to prompt CO loss. Double ionization was found to be dominated by the knockout process with an onset of 20.9 similar to 0.4 eV. The oscillator strength is significantly larger for energies above 26.6 similar to 0.4 eV, corresponding to one electron being ejected from the Os3 center and one from the CO ligands. The cross section for double ionization was found to increase linearly up to 35 eV ionization energy, at which 40% of the generated ions are doubly charged. Published by AIP Publishing.

Published
2018
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49. Time-Resolved Photoelectron Studies of Thiophene and 2,5-Dimethylthiophene

Author

Schalk, Oliver, Larsen, M. A. B., Skov, A. B., Liisberg, M. B., Geng, Ting, Sølling, T. I., Thomas, Richard D., Schalk, Oliver, Larsen, M. A. B., Skov, A. B., Liisberg, M. B., Geng, Ting, Sølling, T. I., and Thomas, Richard D.

Abstract

The photoinduced dynamics of thiophene and 2,S-dimethylthiophene (2,5-DMT) were investigated upon excitation at 200 and 255 nm (2,5-DMT only) using time-resolved photoelectron spectroscopy and compared with results from ab initio coupled cluster calculations. For thiophene, depopulation of the initially excited B 2 (pi(3)pi(4)*) state to the lower-lying A(1) (pi(3)pi(4)*) state occurs within 25 +/- 20 fs, with a subsequent bifurcation into a ring-puckering channel and a ring-opening channel with lifetimes of 80 +/- 20 and 450 +/- 50 fs, respectively. For 2,5-DMT, the dynamics following excitation at 200 nm is described by a monoexponential decay with a time constant of 120 +/- 20 fs, while that following excitation at 255 nm is best fit by a biexponential decay with time constants of 115 +/- 20 fs and 15 +/- 3 ps, respectively. The fast signal observed after excitation of 2,5-DMT is assigned to the ring-opening channel, which is favored with respect to thiophene due to a lower excited-state barrier along the ring-opening coordinate and an increased inertia toward the ring-puckering channel. Coupled cluster calculations have been undertaken to compare the relaxation dynamics of thiophene to thiazole and isothiazole. For the latter two molecules, we find a strong gradient along the ring-opening coordinate in the Franck-Condon region of the initially populated pi pi* state and predict that ring-opening is the dominating relaxation channel after photoexcitation. We use the extracted information for a comparison of the thiophene dynamics with the light-induced processes observed in other five-membered heterocyclic molecules.

Published
2018
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50. The ring-opening channel and the influence of Rydberg states on the excited state dynamics of furan and its derivatives

Author

Schalk, Oliver, Geng, Ting, Hansson, Tony, Thomas, Richard D., Schalk, Oliver, Geng, Ting, Hansson, Tony, and Thomas, Richard D.

Abstract

One important relaxation pathway for photo-excited five-membered heterocyclic organic molecules is ring-opening via a dissociative pi sigma* state. In this study, we investigate the influence of this pathway in furan and several hydrogenated and methylated derivatives by combining time-resolved photoelectron spectroscopy with time-dependent density functional theory and coupled cluster calculations. We find strong experimental evidence that the ring-opening channel is the major relaxation channel in furan, 2,3-dihydrofuran, and 2-methylfuran (2-MF). In 2,5-dimethylfuran (25-DMF), however, we observe that the molecules relax either via a pi 3s Rydberg state or through a direct return to the ground state by undergoing ring-puckering motions. From the supporting calculations, for 2-MF and 25-DMF, we predict that there is strong mixing between the pi sigma* state and the pi 3s Rydberg state along the ring opening pathway. However, in 25-DMF, no crossing between the pi sigma*/pi 3s state and the initially excited pi pi* state can be found along the ring opening coordinate, effectively blocking this channel.

Published
2018
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