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80 results on '"Barbara Cunha"'

1. Physical simulation as a tool to understand friction stir processed X80 pipeline steel plate complex microstructures

Author

Julian Avila, Julian Escobar, Barbara Cunha, William Magalhães, Paulo Mei, Johnnatan Rodriguez, Haroldo Pinto, and Antonio Ramirez

Subjects
Mining engineering. Metallurgy, TN1-997
Abstract

The thermal cycles associated to friction stir welding and processing produce a wide range of microstructures, resulting in different mechanical behaviors along the weld. Most research efforts have focused on the development of welding parameters to obtain sound welds, yet there is still an opportunity for performance improvement based on the understanding of how microstructures are produced. This work explored the different microstructures obtained after physical simulation of an X80 pipeline steel, as a function of the cooling rate and the isothermal transformation temperature. The aim was to study the development of complex mixed microstructures under controlled conditions, in order to compare them to the ones obtained after friction stir processing. As result of the continuous cooling and isothermal thermal simulations, intermediated and high cooling rates, the microstructures matched with those found at the processed plates. These results might help developing a better cooling control after welding. Keywords: Friction stir processing, Heat-affected zone, X80 pipeline steel, Bainite, Continuous cooling transformation

Published
2019
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2. Time-resolved inner-shell photoelectron spectroscopy: from a bound molecule to an isolated atom

Author

Brauße, Felix, Goldsztejn, Gildas, Amini, Kasra, Boll, Rebecca, Bari, Sadia, Bomme, Cédric, Brouard, Mark, Burt, Michael, de Miranda, Barbara Cunha, Düsterer, Stefan, Erk, Benjamin, Géléoc, Marie, Geneaux, Romain, Gentleman, Alexander S., Guillemin, Renaud, Ismail, Iyas, Johnsson, Per, Journel, Loïc, Kierspel, Thomas, Köckert, Hansjochen, Küpper, Jochen, Lablanquie, Pascal, Lahl, Jan, Lee, Jason W. L., Mackenzie, Stuart R., Maclot, Sylvain, Manschwetus, Bastian, Mereshchenko, Andrey S., Mullins, Terence, Olshin, Pavel K., Palaudoux, Jérôme, Patchkovskii, Serguei, Penent, Francis, Piancastelli, Maria Novella, Rompotis, Dimitrios, Ruchon, Thierry, Rudenko, Artem, Savelyev, Evgeny, Schirmel, Nora, Techert, Simone, Travnikova, Oksana, Trippel, Sebastian, Underwood, Jonathan G., Vallance, Claire, Wiese, Joss, Simon, Marc, Holland, David M. P., Marchenko, Tatiana, Rouzée, Arnaud, and Rolles, Daniel

Subjects
Physics - Chemical Physics
Abstract

Due to its element- and site-specificity, inner-shell photoelectron spectroscopy is a widely used technique to probe the chemical structure of matter. Here we show that time-resolved inner-shell photoelectron spectroscopy can be employed to observe ultrafast chemical reactions and the electronic response to the nuclear motion with high sensitivity. The ultraviolet dissociation of iodomethane (CH$_3$I) is investigated by ionization above the iodine 4d edge, using time-resolved inner-shell photoelectron and photoion spectroscopy. The dynamics observed in the photoelectron spectra appear earlier and are faster than those seen in the iodine fragments. The experimental results are interpreted using crystal field and spin-orbit configuration interaction calculations, and demonstrate that time-resolved inner-shell photoelectron spectroscopy is a powerful tool to directly track ultrafast structural and electronic transformations in gas-phase molecules.

Published
2019
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3. Coulomb explosion imaging of concurrent CH$_{2}$BrI photodissociation dynamics

Author

Burt, Michael, Boll, Rebecca, Lee, Jason W. L., Amini, Kasra, Köckert, Hansjochen, Vallance, Claire, Gentleman, Alexander S., Mackenzie, Stuart R., Bari, Sadia, Bomme, Cédric, Düsterer, Stefan, Erk, Benjamin, Manschwetus, Bastian, Müller, Erland, Rompotis, Dimitrios, Savelyev, Evgeny, Schirmel, Nora, Techert, Simone, Treusch, Rolf, Küpper, Jochen, Trippel, Sebastian, Wiese, Joss, Stapelfeldt, Henrik, de Miranda, Barbara Cunha, Guillemin, Renaud, Ismail, Iyas, Journel, Loïc, Marchenko, Tatiana, Palaudoux, Jérôme, Penent, Francis, Piancastelli, Maria Novella, Simon, Marc, Travnikova, Oksana, Brausse, Felix, Goldsztejn, Gildas, Rouzée, Arnaud, Géléoc, Marie, Geneaux, Romain, Ruchon, Thierry, Underwood, Jonathan, Holland, David M. P., Mereshchenko, Andrey S., Olshin, Pavel K., Johnsson, Per, Maclot, Sylvain, Lahl, Jan, Rudenko, Artem, Ziaee, Farzaneh, Brouard, Mark, and Rolles, Daniel

Subjects
Physics - Chemical Physics
Abstract

The dynamics following laser-induced molecular photodissociation of gas-phase CH$_{2}$BrI at 271.6 nm were investigated by time-resolved Coulomb explosion imaging using intense near-IR femtosecond laser pulses. The observed delay-dependent photofragment momenta reveal that CH$_{2}$BrI undergoes C-I cleavage, depositing 65.6% of the available energy into internal product states, and that absorption of a second UV photon breaks the C-Br bond of CH$_{2}$Br. Simulations confirm that this mechanism is consistent with previous data recorded at 248 nm, demonstrating the sensitivity of Coulomb explosion imaging as a real-time probe of chemical dynamics., Comment: 19 pages, 6 figures. Accepted for publication in Physical Review A

Published
2017
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6. Escala de Crenças sobre a 'Cura' da Homossexualidade (ECVH): desenvolvimento e evidências psicométricas/Escala de creencias sobre la 'Cura' de la homosexualidad (ECCH): desarrollo y evidencias psicométricas/Scale of Beliefs on the 'Cure' of Homosexuality (ECCH): Development and Psychometric Evidences

Author

Rezende, Alessandro Teixeira, Gouveia, Valdiney Veloso, Moizeis, Heloisa Barbara Cunha, Silva, Francicleia Lopes, and Nunes, Jessyca Cristina Freitas

Published
2021
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7. UV-induced dissociation of CH2BrI probed by intense femtosecond XUV pulses

Author

Kockert, Hansjochen, Lee, Jason W. L., Allum, Felix, Amini, Kasra, Bari, Sadia, Bomme, Cedric, Brausse, Felix, Brouard, Mark, Burt, Michael, de Miranda, Barbara Cunha, Duesterer, Stefan, Eng-Johnsson, Per, Erk, Benjamin, Geleoc, Marie, Geneaux, Romain, Gentleman, Alexander S., Guillemin, Renaud, Goldsztejn, Gildas, Holland, David M. P., Ismail, Iyas, Journel, Loic, Kierspel, Thomas, Kuepper, Jochen, Lahl, Jan, Mackenzie, Stuart R., Maclot, Sylvain, Manschwetus, Bastian, Mereshchenko, Andrey S., Mullins, Terence, Olshin, Pavel K., Palaudoux, Jerome, Penent, Francis, Piancastelli, Maria Novella, Rompotis, Dimitrios, Rouzee, Arnaud, Ruchon, Thierry, Rudenko, Artem, Schirmel, Nora, Simon, Marc, Techert, Simone, Travnikova, Oksana, Trippel, Sebastian, Vallance, Claire, Wang, Enliang, Wiese, Joss, Ziaee, Farzaneh, Marchenko, Tatiana, Rolles, Daniel, Boll, Rebecca, Kockert, Hansjochen, Lee, Jason W. L., Allum, Felix, Amini, Kasra, Bari, Sadia, Bomme, Cedric, Brausse, Felix, Brouard, Mark, Burt, Michael, de Miranda, Barbara Cunha, Duesterer, Stefan, Eng-Johnsson, Per, Erk, Benjamin, Geleoc, Marie, Geneaux, Romain, Gentleman, Alexander S., Guillemin, Renaud, Goldsztejn, Gildas, Holland, David M. P., Ismail, Iyas, Journel, Loic, Kierspel, Thomas, Kuepper, Jochen, Lahl, Jan, Mackenzie, Stuart R., Maclot, Sylvain, Manschwetus, Bastian, Mereshchenko, Andrey S., Mullins, Terence, Olshin, Pavel K., Palaudoux, Jerome, Penent, Francis, Piancastelli, Maria Novella, Rompotis, Dimitrios, Rouzee, Arnaud, Ruchon, Thierry, Rudenko, Artem, Schirmel, Nora, Simon, Marc, Techert, Simone, Travnikova, Oksana, Trippel, Sebastian, Vallance, Claire, Wang, Enliang, Wiese, Joss, Ziaee, Farzaneh, Marchenko, Tatiana, Rolles, Daniel, and Boll, Rebecca

Abstract

The ultraviolet (UV)-induced dissociation and photofragmentation of gas-phase CH2BrI molecules induced by intense femtosecond extreme ultraviolet (XUV) pulses at three different photon energies are studied by multi-mass ion imaging. Using a UV-pump-XUV-probe scheme, charge transfer between highly charged iodine ions and neutral CH2Br radicals produced by C-I bond cleavage is investigated. In earlier charge-transfer studies, the center of mass of the molecules was located along the axis of the bond cleaved by the pump pulse. In the present case of CH2BrI, this is not the case, thus inducing a rotation of the fragment. We discuss the influence of the rotation on the charge transfer process using a classical over-the-barrier model. Our modeling suggests that, despite the fact that the dissociation is slower due to the rotational excitation, the critical interatomic distance for charge transfer is reached faster. Furthermore, we suggest that charge transfer during molecular fragmentation may be modulated in a complex way.

Published
2022
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8. UV-induced dissociation of CH2BrI probed by intense femtosecond XUV pulses

Author

Hansjochen Köckert, Jason W L Lee, Felix Allum, Kasra Amini, Sadia Bari, Cédric Bomme, Felix Brauße, Mark Brouard, Michael Burt, Barbara Cunha de Miranda, Stefan Düsterer, Per Eng-Johnsson, Benjamin Erk, Marie Géléoc, Romain Geneaux, Alexander S Gentleman, Renaud Guillemin, Gildas Goldsztejn, David M P Holland, Iyas Ismail, Loïc Journel, Thomas Kierspel, Jochen Küpper, Jan Lahl, Stuart R Mackenzie, Sylvain Maclot, Bastian Manschwetus, Andrey S Mereshchenko, Terence Mullins, Pavel K Olshin, Jérôme Palaudoux, Francis Penent, Maria Novella Piancastelli, Dimitrios Rompotis, Arnaud Rouzée, Thierry Ruchon, Artem Rudenko, Nora Schirmel, Marc Simon, Simone Techert, Oksana Travnikova, Sebastian Trippel, Claire Vallance, Enliang Wang, Joss Wiese, Farzaneh Ziaee, Tatiana Marchenko, Daniel Rolles, Rebecca Boll, University of Oxford, Deutsches Elektronen-Synchrotron DESY, Physique à Haute Intensité (PHI), Institut Rayonnement Matière de Saclay (IRAMIS), Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Université Paris-Saclay-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Université Paris-Saclay-Laboratoire Interactions, Dynamiques et Lasers (ex SPAM) (LIDyl), Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Université Paris-Saclay-Centre National de la Recherche Scientifique (CNRS)-Centre National de la Recherche Scientifique (CNRS), Max-Born-institut, Berlin, Dynamique Réactionnelle (DyR), Deutsches Elektronen-Synchrotron [Hamburg] (DESY), Lund University [Lund], Laboratoire Interactions, Dynamiques et Lasers (ex SPAM) (LIDyl), Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Université Paris-Saclay-Centre National de la Recherche Scientifique (CNRS), Laboratoire de Chimie Physique - Matière et Rayonnement (LCPMR), Institut de Chimie du CNRS (INC)-Sorbonne Université (SU)-Centre National de la Recherche Scientifique (CNRS), Center for Free-Electron Laser Science (CFEL), Universität Hamburg (UHH), Deutsches Elektronen-Synchrotron [Zeuthen] (DESY), Helmholtz-Gemeinschaft = Helmholtz Association, Saint Petersburg State University (SPBU), Department of Physics and Astronomy [Uppsala], Uppsala University, European XFEL Gmbh, Kansas State University, and ANR-16-CE30-0001,ATTOMEMUCHO,Dynamique électronique attoseconde dans les molécules organiques isolées par la spectroscopie 'core-hole clock'(2016)

Subjects
[CHIM.THEO]Chemical Sciences/Theoretical and/or physical chemistry, Atom and Molecular Physics and Optics, charge transfer, free-electron lasers, Atom- och molekylfysik och optik, ddc:530, Condensed Matter Physics, Atomic and Molecular Physics, and Optics, ultrafast molecular dynamics
Abstract

Journal of physics / B 55(1), 014001 (2022). doi:10.1088/1361-6455/ac489d, The ultraviolet (UV)-induced dissociation and photofragmentation of gas-phase CH$_2$BrI molecules induced by intense femtosecond extreme ultraviolet (XUV) pulses at three different photon energies are studied by multi-mass ion imaging. Using a UV-pump���XUV-probe scheme, charge transfer between highly charged iodine ions and neutral CH$_2$Br radicals produced by C���I bond cleavage is investigated. In earlier charge-transfer studies, the center of mass of the molecules was located along the axis of the bond cleaved by the pump pulse. In the present case of CH$_2$BrI, this is not the case, thus inducing a rotation of the fragment. We discuss the influence of the rotation on the charge transfer process using a classical over-the-barrier model. Our modeling suggests that, despite the fact that the dissociation is slower due to the rotational excitation, the critical interatomic distance for charge transfer is reached faster. Furthermore, we suggest that charge transfer during molecular fragmentation may be modulated in a complex way., Published by IOP Publ., Bristol

Published
2022
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10. AVALIAÇÃO DA PRESSÃO PARCIAL DO DIÓXIDO DE CARBONO EXPIRADO (PETCO2) PELO CAPNÓGRAFO-MDCAP EM INDIVÍDUOS INTERNADOS EM HOSPITAL DE REFERÊNCIA NO DISTRITO FEDERAL

Author

Lima, Paula Fernanda Freitas, primary, Cavalcanti, Caroline Barreto, additional, Barreto, Barbara Cunha, additional, Carneiro, Bruno Ramos, additional, Silva, Gabriela de Oliveira, additional, Bragatto, Maria Alice Ramalho, additional, Meireles, Luis Moreira da Silva de Azevedo, additional, and Lima, Alexandra Corrêa Gervazoni Balbuena, additional

Published
2022
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11. Psychomotor consequences in children with Tourette’s Syndrome

Author

Barbara Cunha Vasconcellos, Tamie Mota Arbex, Aline Silva Ziehe, Lara Cruz de Senna-Fernandes, Samantha Golçalves Barbosa, Tatiana Virgínia Fidélis Cordeiro, and Caio Andrade Prins Rodrigues

Abstract

Background: Tourette’s Syndrome (TS) has a neuropsychiatric aspect and a chronic repertoire of motor-phonic tics. The common onset is in infants and remission in adults. Objective: investigate psychomotor consequences in children with TS. Design and settings: literature review. Methods: eleven studies were selected from a group of 20 after searching the MEDLINE database for “psychomotor performance OR psychomotor development” and “Tourette’s Syndrome”. Only articles with full texts available and published from 2011-2021 were included. Results: the response time (RT) of children with TS was longer. Throughout Do/Don’t tasks, with/without false alarms, the RT was lower while the accuracy of movement (AM) was greater. A study on RT and AM with different levels of complexity showed greater difficulty in ST group (p

Published
2021
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12. The management of migraine through Acupuncture: a literature review

Author

Tatiana Virgínia Fidélis Cordeiro, Aline Silva Ziehe, Tamie Mota Arbex, Barbara Cunha Vasconcellos, Lara Cruz de Senna Fernandes, and Maria teresa de Castro Lima Pereira

Abstract

Background: Migraine is one of the most disabling conditions worldwide, and acupuncture can be used as prophylaxis. This practice is indicated to relieve tension, stress, induce analgesia, and has been gaining space due to its A level evidence. Objectives: Investigate the impact of acupuncture on the management of migraine disorders. Design and Settings: literature review. Methods: After searching the MEDLINE database for “migraine disorders OR headache”, “acupuncture” and “integrative medicine OR alternative medicine”, 271 articles were found and 6 used. Only those with full text available and published between 2011-2021 were included. Those that addressed a specific type of migraine were excluded. Results: Acupuncture was analyzed in 4 studies as prophylaxis for migraine, in which there was a general reduction in symptoms and 50% reduction in frequency of episodes (p

Published
2021
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13. Influence of the seasons on the water quality of the Marmeleiro River (Paraná, Brazil) using different bioindicators

Author

Fernando César Manosso, Barbara Cunha Tesch De Oliveira, Elisângela Düsman, Ivane Benedetti Tonial, Alessandra Suzin Bertan, Marilete Chiarelotto, Lorrana Melo Ramalho Ferreira, Juan Carlos Pokrywiecki, Ticiane Sauer Pokrywiecki, Nathana Andressa Thiel, Clarice Fieira, and Anna Gabriela Drummond Xavier Teles

Subjects
biology, General Chemical Engineering, Phosphorus, Chemical oxygen demand, General Engineering, General Physics and Astronomy, chemistry.chemical_element, Lactuca, biology.organism_classification, Total dissolved solids, Horticulture, chemistry, Germination, General Earth and Planetary Sciences, Environmental science, General Materials Science, Water quality, Artemia salina, Bioindicator, General Environmental Science
Abstract

The use of environmental bioindicators and biomarkers has shown promising to evaluate water quality. In this study, the biological indicators Lactuca sativa L., Allium cepa L., and Artemia salina L. were used to verify the water quality of the Marmeleiro River (Parana, Brazil). Water samples were collected at six points along the river, covering urban and rural areas over the four seasons. The experiment of germination and initial growth of the A. cepa seeds showed changes between seasons, but no difference between the collection points. Regarding L. sativa seeds, the results showed changes between the points and the seasons. In general, it was possible to correlate the highest numbers of germinated seeds, size of the germinated roots, percentage, and germination speed with the highest levels of phosphorus and lowest levels of chemical demand for oxygen, oils and greases, and total solids. The results of the cytotoxicity test with A. cepa showed an increase in the mitotic indices of Points 3 (spring, summer, and winter), 4 (spring and winter), 5, and 6 (summer and autumn) correlated with higher levels of phosphorus and chemical oxygen demand in water samples. For the immobility/mortality test with A. salina, in the spring and summer, all collection points were toxic, possibly due to the lower levels of dissolved oxygen in these samples. Therefore, bioindicators proved to be efficient to determine and monitor the Marmeleiro River toxicity and indicate that preservation actions should be implemented for this watershed.

Published
2020
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14. Effects of collision energy and vibrational excitation of CH3+ cations on its reactivity with hydrocarbons: But-2-yne CH3CCCH3 as reagent partner.

Author

Cernuto, Andrea, Lopes, Allan, Romanzin, Claire, de Miranda, Barbara Cunha, Ascenzi, Daniela, Tosi, Paolo, Tonachini, Glauco, Maranzana, Andrea, Polášek, Miroslav, Žabka, Jan, and Alcaraz, Christian

Subjects
HYDROCARBONS, CARBOCATIONS, METHYLATION, ION beams, MASS spectrometry
Abstract

The methyl carbocation is ubiquitous in gaseous environments, such as planetary ionospheres, cometary comae, and the interstellar medium, as well as combustion systems and plasma setups for technological applications. Here we report on a joint experimental and theoretical study on the mechanism of the reactionCH3+ +CH3CCCH3 (but-2-yne, also known as dimethylacetylene), by combining guided ion beam mass spectrometry experiments with ab initio calculations of the potential energy hypersurface. Such a reaction is relevant in understanding the chemical evolution of Saturn's largest satellite, Titan. Two complementary setups have been used: in one case, methyl cations are generated via electron ionization, while in the other case, direct vacuum ultraviolet photoionization with synchrotron radiation of methyl radicals is used to study internal energy effects on the reactivity. Absolute reactive cross sections have been measured as a function of collision energy, and product branching ratios have been derived. The two most abundant products result from electron and hydride transfer, occurring via direct and barrierless mechanisms, while other channels are initiated by the electrophilic addition of the methyl cation to the triple bond of but-2-yne. Among the minor channels, special relevance is placed on the formation of C5H7+, stemming from H2 loss from the addition complex. This is the only observed condensation product with the formation of new C [ABSTRACT FROM AUTHOR]

Published
2017
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15. Psychomotor consequences in children with Tourette’s Syndrome

Author

Vasconcellos, Barbara Cunha, primary, Arbex, Tamie Mota, additional, Ziehe, Aline Silva, additional, Senna-Fernandes, Lara Cruz de, additional, Barbosa, Samantha Golçalves, additional, Cordeiro, Tatiana Virgínia Fidélis, additional, and Rodrigues, Caio Andrade Prins, additional

Published
2021
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17. O método documentário na análise de um vídeo com conteúdo matemático

Author

Fontes, Barbara Cunha and De Carvhalo, Marcelo

Subjects
Teórica, Recursos informáticos, A distancia, Inicial, Grabaciones
Abstract

Este artigo faz parte de um mosaico de textos que abordam o tema “Metodologia de Pesquisa e tecnologias digitais”, com o objetivo de apresentar a análise qualitativa de um vídeo com conteúdo matemático produzido por estudantes do curso de licenciatura em matemática da Universidade Federal do Mato Grosso do Sul na modalidade a distância, baseada numa adaptação do método documentário. Ao buscar por conhecimentos e visões implícitas (conhecimento ateórico) no vídeo, a adaptação do método documentário foi essencial ao propor uma maneira para realizar tal ação, por meio de etapas que indicam caminhos a seguir. Como resultado, percebeu-se que o vídeo possui implicitamente a visão dos licenciandos a respeito dos processos de ensino e aprendizagem de matemática: formalista clássica e tecnicista mecanicista. Além disso, refletiu o ensino que os sujeitos tiveram e uma possível futura prática docente.

Published
2020

18. Threshold photoelectron spectroscopy of unstable N-containing compounds: Resolution of ΔK subbands in HNCO+ and vibrational resolution in NCO+.

Author

Holzmeier, Fabian, Lang, Melanie, Fischer, Ingo, Tang, Xiaofeng, de Miranda, Barbara Cunha, Romanzin, Claire, Alcaraz, Christian, and Hemberger, Patrick

Subjects
PHOTOELECTRON spectroscopy, EXCITED states, GROUND state (Quantum mechanics), NITROGEN, ISOCYANIC acid, VIBRATIONAL spectra, SYNCHROTRON radiation
Abstract

The threshold photoelectron spectra (TPES) of two unstable nitrogen-containing species, HNCO and NCO, were recorded utilizing vacuum ultraviolet synchrotron radiation. Both are intermediates in combustion processes and play a role in the removal of nitrogen oxides from exhaust gases. The rovibronic structure of the first band in the TPES of HNCO+ was analyzed within the framework of an orbital ionization model, and the resolved structure of the origin band was assigned to ΔK subbands. An ionization energy of 11.602 ± 0.005 eV was determined and the vibrational structure of the cationic ground state was analyzed by a Franck-Condon fit. Low lying electronically excited states of HNCO+ were also observed. In a second series of experiments, the NCO radical was generated by flash pyrolysis from chlorine isocyanate. The ionization energy to the X+ ³Σ- ground state was determined to be 11.76 ± 0.02 eV, while for the a+ ¹Δ state, a value of 12.93 ± 0.02 eV was obtained. Vibrational structure was observed for both states, and bands were assigned by Franck-Condon simulations. [ABSTRACT FROM AUTHOR]

Published
2015
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19. Coulomb explosion imaging of CH

Author

Felix, Allum, Michael, Burt, Kasra, Amini, Rebecca, Boll, Hansjochen, Köckert, Pavel K, Olshin, Sadia, Bari, Cédric, Bomme, Felix, Brauße, Barbara, Cunha de Miranda, Stefan, Düsterer, Benjamin, Erk, Marie, Géléoc, Romain, Geneaux, Alexander S, Gentleman, Gildas, Goldsztejn, Renaud, Guillemin, David M P, Holland, Iyas, Ismail, Per, Johnsson, Loïc, Journel, Jochen, Küpper, Jan, Lahl, Jason W L, Lee, Sylvain, Maclot, Stuart R, Mackenzie, Bastian, Manschwetus, Andrey S, Mereshchenko, Robert, Mason, Jérôme, Palaudoux, Maria Novella, Piancastelli, Francis, Penent, Dimitrios, Rompotis, Arnaud, Rouzée, Thierry, Ruchon, Artem, Rudenko, Evgeny, Savelyev, Marc, Simon, Nora, Schirmel, Henrik, Stapelfeldt, Simone, Techert, Oksana, Travnikova, Sebastian, Trippel, Jonathan G, Underwood, Claire, Vallance, Joss, Wiese, Farzaneh, Ziaee, Mark, Brouard, Tatiana, Marchenko, and Daniel, Rolles

Abstract

The photodissociation dynamics of CH

Published
2018

20. The surprisingly high ligation energy of CO to ruthenium porphyrins

Author

Laurent Nahon, Niloufar Shafizadeh, Satchin Soorkia, Séverine Boyé-Péronne, Gustavo A. Garcia, Shufeng Chen, Aurélien de la Lande, Lionel Poisson, Barbara Cunha de Miranda, Benoît Soep, Institut des Sciences Moléculaires d'Orsay (ISMO), Université Paris-Sud - Paris 11 (UP11)-Centre National de la Recherche Scientifique (CNRS), Synchrotron SOLEIL (SSOLEIL), Centre National de la Recherche Scientifique (CNRS), Laboratoire de Chimie Physique D'Orsay (LCPO), Université Paris-Sud - Paris 11 (UP11)-Institut de Chimie du CNRS (INC)-Centre National de la Recherche Scientifique (CNRS), Dynamique Réactionnelle (DyR), Institut Rayonnement Matière de Saclay (IRAMIS), Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Université Paris-Saclay-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Université Paris-Saclay-Laboratoire Interactions, Dynamiques et Lasers (ex SPAM) (LIDyl), Université Paris-Saclay-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Centre National de la Recherche Scientifique (CNRS)-Centre National de la Recherche Scientifique (CNRS), ANR-11-IDEX-0003,IPS,Idex Paris-Saclay(2011), and Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Université Paris-Saclay-Centre National de la Recherche Scientifique (CNRS)-Centre National de la Recherche Scientifique (CNRS)

Subjects
Spin states, 010405 organic chemistry, Chemistry, Ligand, Binding energy, General Physics and Astronomy, chemistry.chemical_element, 010402 general chemistry, 01 natural sciences, 0104 chemical sciences, Ruthenium, [CHIM.THEO]Chemical Sciences/Theoretical and/or physical chemistry, chemistry.chemical_compound, Tetraphenylporphyrin, Physical chemistry, [CHIM.COOR]Chemical Sciences/Coordination chemistry, Singlet state, Physical and Theoretical Chemistry, Bond energy, Ionization energy
Abstract

A combined theoretical and experimental approach has been used to investigate the binding energy of a ruthenium metalloporphyrin ligated with CO, ruthenium tetraphenylporphyrin [RuII TPP], in the RuII oxidation degree. Measurements performed with VUV ionization using the DESIRS beamline at Synchrotron SOLEIL led to adiabatic ionization energies of [RuII TPP] and its complex with CO, [RuII TPP–CO], of 6.48 ± 0.03 eV and 6.60 ± 0.03 eV, respectively, while the ion dissociation threshold of [RuII TPP–CO]+ is measured to be 8.36 ± 0.03 eV using the ground-state neutral complex. These experimental data are used to derive the binding energies of the CO ligand in neutral and cationic complexes (1.88 ± 0.06 eV and 1.76 ± 0.06 eV, respectively) using a Born–Haber cycle. Density functional theory calculations, in very satisfactory agreement with the experimental results, help to get insights into the metal–ligand bond. Notably, the high ligation energies can be rationalized in terms of the ruthenium orbital structure, which is singular compared to that of the iron atom. Thus, beyond indications of a strengthening of the Ru–CO bond due to the decrease in the CO vibrational frequency in the complex as compared to the Fe–CO bond, high-level calculations are essential to accurately describe the metal ligand (CO) bond and show that the Ru–CO bond energy is strongly affected by the splitting of triplet and singlet spin states in uncomplexed [Ru TPP].

Published
2018
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21. Time-resolved inner-shell photoelectron spectroscopy: From a bound molecule to an isolated atom

Author

Claire Vallance, Jérôme Palaudoux, Stefan Düsterer, Marc Simon, Evgeny Savelyev, Tatiana Marchenko, Hansjochen Köckert, Kasra Amini, Jongmin Lee, Benjamin Erk, R. Guillemin, Marie Géléoc, Cédric Bomme, Per Johnsson, Sebastian Trippel, Nora Schirmel, David M. P. Holland, Francis Penent, Barbara Cunha de Miranda, Jonathan G. Underwood, Rebecca Boll, Pavel K. Olshin, Sadia Bari, Thomas Kierspel, Maria Novella Piancastelli, Jochen Küpper, Jan Lahl, Michael Burt, I. Ismail, Simone Techert, Serguei Patchkovskii, Sylvain Maclot, Alexander S. Gentleman, Gildas Goldsztejn, Artem Rudenko, Felix Brauße, Terence Mullins, Daniel Rolles, Mark Brouard, Oksana Travnikova, Thierry Ruchon, Andrey S. Mereshchenko, Bastian Manschwetus, Dimitrios Rompotis, Joss Wiese, Arnaud Rouzée, Pascal Lablanquie, Romain Géneaux, Stuart R. Mackenzie, Loïc Journel, Max-Born-Institut für Nichtlineare Optik und Kurzzeitspektroskopie (MBI), University of Oxford, Deutsches Elektronen-Synchrotron [Hamburg] (DESY), Laboratoire de Chimie Physique - Matière et Rayonnement (LCPMR), Institut de Chimie du CNRS (INC)-Sorbonne Université (SU)-Centre National de la Recherche Scientifique (CNRS), Laboratoire Interactions, Dynamiques et Lasers (ex SPAM) (LIDyl), Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Université Paris-Saclay-Centre National de la Recherche Scientifique (CNRS), Structures BioMoléculaires (SBM), Institut Rayonnement Matière de Saclay (IRAMIS), Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Université Paris-Saclay-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Université Paris-Saclay-Laboratoire Interactions, Dynamiques et Lasers (ex SPAM) (LIDyl), Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Université Paris-Saclay-Centre National de la Recherche Scientifique (CNRS)-Centre National de la Recherche Scientifique (CNRS), Attophysique (ATTO), Lund University [Lund], Center for Free-Electron Laser Science (CFEL), Universität Hamburg (UHH), Saint Petersburg State Polytechnical University (SPSPU), Department of Physics and Astronomy [Uppsala], Uppsala University, Kansas State University, Max-Planck-Institut für Biophysikalische Chemie - Max Planck Institute for Biophysical Chemistry [Göttingen], Max-Planck-Gesellschaft, Department of Physics and Astronomy [UCL London], University College of London [London] (UCL), ANR-14-CE32-0010,Xstase,Étude du moment angulaire de faisceaux lumineux XUV: synthèse et transferts(2014), ANR-16-CE30-0001,ATTOMEMUCHO,Dynamique électronique attoseconde dans les molécules organiques isolées par la spectroscopie 'core-hole clock'(2016), European Project: 238671,EC:FP7:PEOPLE,FP7-PEOPLE-ITN-2008,ICONIC(2009), European Project: 641789,H2020,H2020-MSCA-ITN-2014,MEDEA(2015), University of Oxford [Oxford], Université Paris-Saclay-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Centre National de la Recherche Scientifique (CNRS), and Université Paris-Saclay-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Centre National de la Recherche Scientifique (CNRS)-Centre National de la Recherche Scientifique (CNRS)

Subjects
Chemical Physics (physics.chem-ph), Physics, 010304 chemical physics, Atom and Molecular Physics and Optics, Chemical structure, Photodissociation, technology, industry, and agriculture, FOS: Physical sciences, Configuration interaction, 01 natural sciences, Molecular physics, Dissociation (chemistry), 3. Good health, [CHIM.THEO]Chemical Sciences/Theoretical and/or physical chemistry, X-ray photoelectron spectroscopy, Ionization, Physics - Chemical Physics, 0103 physical sciences, Physics::Atomic and Molecular Clusters, Molecule, ddc:530, Atom- och molekylfysik och optik, [PHYS.PHYS.PHYS-CHEM-PH]Physics [physics]/Physics [physics]/Chemical Physics [physics.chem-ph], 010306 general physics, Spectroscopy
Abstract

International audience; Due to its element and site specificity, inner-shell photoelectron spectroscopy is a widely used technique to probe the chemical structure of matter. Here, we show that time-resolved inner-shell photoelectron spectroscopy can be employed to observe ultrafast chemical reactions and the electronic response to the nuclear motion with high sensitivity. The ultraviolet dissociation of iodomethane (CH3I) is investigated by ionization above the iodine 4d edge, using time-resolved inner-shell photoelectron and photoion spectroscopy. The dynamics observed in the photoelectron spectra appear earlier and are faster than those seen in the iodine fragments. The experimental results are interpreted using crystal-field and spin-orbit configuration interaction calculations, and demonstrate that time-resolved inner-shell photoelectron spectroscopy is a powerful tool to directly track ultrafast structural and electronic transformations in gas-phase molecules.

Published
2018
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23. Energy Pricing Policies for Inclusive Growth in Latin America and the Caribbean

Author

Guillermo Beylis, Barbara Cunha, Guillermo Beylis, and Barbara Cunha

Subjects
Energy policy--Latin America, Energy policy--Caribbean Area, Power resources--Subsidies--Caribbean Area, Power resources--Prices--Government policy--Latin America, Power resources--Prices--Government policy--Caribbean Area, Power resources--Subsidies--Latin America
Abstract

Government strategies for setting energy prices are not uniform across the Latin America and the Caribbean (LAC) region—or even across fuels. Instead, they cover a full spectrum, ranging from discretionary price-fixing at one end to pure market-based approaches at the other. In between is a wide variety of other schemes such as price stabilization funds, import or export parity pricing, price smoothing through tax levels, and targeted direct price subsidies or vouchers. Governments in the LAC region, however, tend to be small as measured by government revenues as a percentage of GDP. So their limited government resources have to be used wisely and be better targeted to the poor and vulnerable. Although energy subsidies are an inefficient policy tool for protecting the welfare of the poor, energy price increases can have a big impact on these households. Energy Pricing Policies for Inclusive Growth in Latin America and the Caribbean finds that energy subsidies are highly regressive in an absolute sense—that is, the lion's share of every dollar spent on keeping energy prices low benefits wealthier households. However, subsidies for fuels that are widely used for cooking and heating—liquefied petroleum gas (LPG), natural gas, and kerosene—as well as for electricity, can be relatively neutral or progressive, implying that lower-income households capture benefits that are proportionate to their expenditures. In other words, although poorer households receive very little from every dollar spent on energy subsidies, that small amount may represent an important share of their expenditures. It is important, then, that governments expand the coverage and depth of their social safety nets to provide relief for poor households if energy prices rise. This report also finds that aggregate price impacts and the competitiveness effects of energy price increases are moderate to small and can be smoothed out through macropolicy responses.

Published
2017

24. Coulomb explosion imaging of CH3I and CH2CII photodissociation dynamics

Author

Barbara Cunha de Miranda, Per Johnsson, Romain Géneaux, Stuart R. Mackenzie, I. Ismail, Hansjochen Köckert, David M. P. Holland, Dimitrios Rompotis, Marie Géléoc, Jérôme Palaudoux, Loic Journel, Jonathan G. Underwood, Farzaneh Ziaee, Jan Lahl, Robert Mason, Kasra Amini, Mark Brouard, Gildas Goldsztejn, Artem Rudenko, Stefan Düsterer, Sylvain Maclot, Maria Novella Piancastelli, Arnaud Rouzée, Thierry Ruchon, Daniel Rolles, Michael Burt, Jongmin Lee, Rebecca Boll, Oksana Travnikova, Andrey S. Mereshchenko, Joss Wiese, Sebastian Trippel, Marc Simon, Francis Penent, Felix Allum, Felix Brauße, Bastian Manschwetus, Simone Techert, Evgeny Savelyev, Tatiana Marchenko, Henrik Stapelfeldt, Renaud Guillemin, Nora Schirmel, Cédric Bomme, Benjamin Erk, Alexander S. Gentleman, Claire Vallance, Pavel K. Olshin, Sadia Bari, Jochen Küpper, University of Oxford, Deutsches Elektronen-Synchrotron [Hamburg] (DESY), Saint Petersburg State Polytechnical University (SPSPU), KVI Atomic and Molecular Physics (KVI), University of Groningen [Groningen], Max-Born-Institut für Nichtlineare Optik und Kurzzeitspektroskopie (MBI), Synchrotron SOLEIL (SSOLEIL), Centre National de la Recherche Scientifique (CNRS), Laboratoire Interactions, Dynamiques et Lasers (ex SPAM) (LIDyl), Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Université Paris-Saclay-Centre National de la Recherche Scientifique (CNRS), Attophysique (ATTO), Institut Rayonnement Matière de Saclay (IRAMIS), Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Université Paris-Saclay-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Université Paris-Saclay-Laboratoire Interactions, Dynamiques et Lasers (ex SPAM) (LIDyl), Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Université Paris-Saclay-Centre National de la Recherche Scientifique (CNRS)-Centre National de la Recherche Scientifique (CNRS), Laboratoire de Chimie Physique - Matière et Rayonnement (LCPMR), Université Pierre et Marie Curie - Paris 6 (UPMC)-Institut de Chimie du CNRS (INC)-Centre National de la Recherche Scientifique (CNRS), Microbiology Laboratory, Middlemore Hospital, Laboratoire des collisions atomiques et moléculaires (LCAM), Université Paris-Sud - Paris 11 (UP11)-Centre National de la Recherche Scientifique (CNRS), Department of Physics, Lund Institute of Technology, Lund University [Lund]-Lund University [Lund], Lund University [Lund], Centre de recherche sur les Ions, les MAtériaux et la Photonique (CIMAP - UMR 6252), Université de Caen Normandie (UNICAEN), Normandie Université (NU)-Normandie Université (NU)-École Nationale Supérieure d'Ingénieurs de Caen (ENSICAEN), Normandie Université (NU)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Centre National de la Recherche Scientifique (CNRS)-Institut de Recherche sur les Matériaux Avancés (IRMA), Normandie Université (NU)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Université de Rouen Normandie (UNIROUEN), Normandie Université (NU)-Institut national des sciences appliquées Rouen Normandie (INSA Rouen Normandie), Institut National des Sciences Appliquées (INSA)-Normandie Université (NU)-Institut National des Sciences Appliquées (INSA)-Centre National de la Recherche Scientifique (CNRS)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Université de Rouen Normandie (UNIROUEN), Institut National des Sciences Appliquées (INSA)-Normandie Université (NU)-Institut National des Sciences Appliquées (INSA)-Centre National de la Recherche Scientifique (CNRS), Physical and Theoretical Chemistry Laboratory, Institut de Chimie du CNRS (INC)-Sorbonne Université (SU)-Centre National de la Recherche Scientifique (CNRS), Laboratoire Interdisciplinaire Carnot de Bourgogne (ICB), Université de Bourgogne (UB)-Centre National de la Recherche Scientifique (CNRS), Kansas State University, Georg-August-University = Georg-August-Universität Göttingen, Department of Physics and Astronomy [UCL London], University College of London [London] (UCL), Center for Free-Electron Laser Science (CFEL), ANR-16-CE30-0001,ATTOMEMUCHO,Dynamique électronique attoseconde dans les molécules organiques isolées par la spectroscopie 'core-hole clock'(2016), University of Oxford [Oxford], Université Paris-Saclay-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Centre National de la Recherche Scientifique (CNRS), Université Paris-Saclay-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Centre National de la Recherche Scientifique (CNRS)-Centre National de la Recherche Scientifique (CNRS), Normandie Université (NU)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Centre National de la Recherche Scientifique (CNRS), Laboratoire Interdisciplinaire Carnot de Bourgogne (LICB), Georg-August-University [Göttingen], Centre National de la Recherche Scientifique (CNRS)-École Nationale Supérieure d'Ingénieurs de Caen (ENSICAEN), Normandie Université (NU)-Normandie Université (NU)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Université de Caen Normandie (UNICAEN), and Normandie Université (NU)

Subjects
Atom and Molecular Physics and Optics, Imaging spectrometer, General Physics and Astronomy, 02 engineering and technology, Physical Chemistry, 01 natural sciences, Molecular physics, Mass spectrometry imaging, Ion, 0103 physical sciences, Molecule, ddc:530, Physical and Theoretical Chemistry, 010306 general physics, ComputingMilieux_MISCELLANEOUS, Fysikalisk kemi, Physics, Coupling, Range (particle radiation), Photodissociation, Coulomb explosion, 021001 nanoscience & nanotechnology, 3. Good health, Atom- och molekylfysik och optik, [PHYS.PHYS.PHYS-CHEM-PH]Physics [physics]/Physics [physics]/Chemical Physics [physics.chem-ph], 0210 nano-technology
Abstract

The journal of chemical physics 149(20), 204313 (2018). doi:10.1063/1.5041381, The photodissociation dynamics of CH$_3$I and CH$_2$ClI at 272 nm were investigated by time-resolved Coulomb explosion imaging, with an intense non-resonant 815 nm probe pulse. Fragment ion momenta over a wide m/z range were recorded simultaneously by coupling a velocity map imaging spectrometer with a pixel imaging mass spectrometry camera. For both molecules, delay-dependent pump-probe features were assigned to ultraviolet-induced carbon-iodine bond cleavage followed by Coulomb explosion. Multi-mass imaging also allowed the sequential cleavage of both carbon-halogen bonds in CH$_2$ClI to be investigated. Furthermore, delay-dependent relative fragment momenta of a pair of ions were directly determined using recoil-frame covariance analysis. These results are complementary to conventional velocity map imaging experiments and demonstrate the application of time-resolved Coulomb explosion imaging to photoinduced real-time molecular motion., Published by American Institute of Physics, Melville, NY

Published
2018
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25. Effects of collision energy and vibrational excitation of CH

Author

Andrea, Cernuto, Allan, Lopes, Claire, Romanzin, Barbara, Cunha de Miranda, Daniela, Ascenzi, Paolo, Tosi, Glauco, Tonachini, Andrea, Maranzana, Miroslav, Polášek, Jan, Žabka, and Christian, Alcaraz

Abstract

The methyl carbocation is ubiquitous in gaseous environments, such as planetary ionospheres, cometary comae, and the interstellar medium, as well as combustion systems and plasma setups for technological applications. Here we report on a joint experimental and theoretical study on the mechanism of the reaction CH

Published
2017

26. Coulomb-explosion imaging of concurrent CH2BrI photodissociation dynamics

Author

Renaud Guillemin, Maria Novella Piancastelli, Alexander S. Gentleman, Artem Rudenko, Jérôme Palaudoux, Thierry Ruchon, O. Travnikova, Rebecca Boll, Felix Brausse, Rolf Treusch, Marc Simon, Arnaud Rouzée, Mark Brouard, Stefan Düsterer, Joss Wiese, Stuart R. Mackenzie, Jochen Küpper, Sebastian Trippel, Loic Journel, Jonathan G. Underwood, Claire Vallance, Michael Burt, Nora Schirmel, Kasra Amini, David M. P. Holland, Farzaneh Ziaee, Francis Penent, Benjamin Erk, Jan Lahl, Per Johnsson, Romain Géneaux, Barbara Cunha de Miranda, Hansjochen Köckert, Andrey S. Mereshchenko, Jongmin Lee, Marie Géléoc, Gildas Goldsztejn, Bastian Manschwetus, Sylvain Maclot, Henrik Stapelfeldt, Daniel Rolles, Cédric Bomme, Iyas Ismail, Simone Techert, Evgeny Savelyev, Tatiana Marchenko, Erland Müller, Dimitrios Rompotis, Pavel K. Olshin, and Sadia Bari

Subjects
Physics, Photon, Photodissociation, Coulomb explosion, 010402 general chemistry, medicine.disease_cause, Laser, 01 natural sciences, 0104 chemical sciences, Chemical Dynamics, law.invention, law, Ionization, 0103 physical sciences, Femtosecond, medicine, Atomic physics, 010306 general physics, Ultraviolet
Abstract

The dynamics following laser-induced molecular photodissociation of gas-phase CH2BrI at 271.6 nm were investigated by time-resolved Coulomb-explosion imaging using intense near-IR femtosecond laser pulses. The observed delay-dependent photofragment momenta reveal that CH2BrI undergoes C-I cleavage, depositing 65.6% of the available energy into internal product states, and that absorption of a second UV photon breaks the C-Br bond of CH2Br. Simulations confirm that this mechanism is consistent with previous data recorded at 248 nm, demonstrating the sensitivity of Coulomb-explosion imaging as a real-time probe of chemical dynamics.

Published
2017
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35. Energy Pricing Policies

Author

Guillermo Beylis and Barbara Cunha

Subjects
Microeconomics, Average cost pricing, Investment theory, Energy pricing, Variable pricing, Consumption-based capital asset pricing model, Economics
Published
2017
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36. Energy Pricing Policies for Inclusive Growth in Latin America and the Caribbean

Author

Guillermo Beylis and Barbara Cunha

Subjects
PROGRESSIVITY, PRICE REFORM, ELECTRICITY TARIFFS, FISCAL COSTS, ENERGY PRICES, OIL AND GAS, SUBSIDIES, INEQUALITY, DISTRIBUTIONAL EFFECTS, ELECTRICITY, PRICING POLICIES, REGRESSIVITY, INCIDENCE
Abstract

Government strategies for setting energy prices are not uniform across the Latin America and the Caribbean (LAC) region—or even across fuels. Instead, they cover a full spectrum, ranging from discretionary price-fixing at one end to pure market-based approaches at the other. In between is a wide variety of other schemes such as price stabilization funds, import or export parity pricing, price smoothing through tax levels, and targeted direct price subsidies or vouchers. Governments in the LAC region, however, tend to be small as measured by government revenues as a percentage of GDP. So their limited government resources have to be used wisely and be better targeted to the poor and vulnerable. Although energy subsidies are an inefficient policy tool for protecting the welfare of the poor, energy price increases can have a big impact on these households. Energy Pricing Policies for Inclusive Growth in Latin America and the Caribbean finds that energy subsidies are highly regressive in an absolute sense—that is, the lion’s share of every dollar spent on keeping energy prices low benefits wealthier households. However, subsidies for fuels that are widely used for cooking and heating—liquefied petroleum gas (LPG), natural gas, and kerosene—as well as for electricity, can be relatively neutral or progressive, implying that lower-income households capture benefits that are proportionate to their expenditures. In other words, although poorer households receive very little from every dollar spent on energy subsidies, that small amount may represent an important share of their expenditures. It is important, then, that governments expand the coverage and depth of their social safety nets to provide relief for poor households if energy prices rise. This report also finds that aggregate price impacts and the competitiveness effects of energy price increases are moderate to small and can be smoothed out through macropolicy responses.

Published
2017

37. VUV Photodynamics and Chiral Asymmetry in the Photoionization of Gas Phase Alanine Enantiomers

Author

Steven F. Daly, Gustavo A. Garcia, Maurice Tia, Barbara Cunha de Miranda, Laurent Nahon, Ivan Powis, and François Gaie-Levrel

Subjects
Aerosols, Photons, Quantitative Biology::Biomolecules, Circular dichroism, Alanine, Vacuum, Ultraviolet Rays, Chemistry, Photoelectron Spectroscopy, Stereoisomerism, Photoelectron photoion coincidence spectroscopy, Photoionization, Dichroism, Photochemical Processes, Electron spectroscopy, X-ray photoelectron spectroscopy, Ionization, Physics::Atomic and Molecular Clusters, Mass spectrum, Thermodynamics, Gases, Volatilization, Physical and Theoretical Chemistry, Atomic physics, Synchrotrons
Abstract

The valence shell photoionization of the simplest proteinaceous chiral amino acid, alanine, is investigated over the vacuum ultraviolet region from its ionization threshold up to 18 eV. Tunable and variable polarization synchrotron radiation was coupled to a double imaging photoelectron/photoion coincidence (i(2)PEPICO) spectrometer to produce mass-selected threshold photoelectron spectra and derive the state-selected fragmentation channels. The photoelectron circular dichroism (PECD), an orbital-sensitive, conformer-dependent chiroptical effect, was also recorded at various photon energies and compared to continuum multiple scattering calculations. Two complementary vaporization methods-aerosol thermodesorption and a resistively heated sample oven coupled to an adiabatic expansion-were applied to promote pure enantiomers of alanine into the gas phase, yielding neutral alanine with different internal energy distributions. A comparison of the photoelectron spectroscopy, fragmentation, and dichroism measured for each of the vaporization methods was rationalized in terms of internal energy and conformer populations and supported by theoretical calculations. The analytical potential of the so-called PECD-PICO detection technique-where the electron spectroscopy and circular dichroism can be obtained as a function of mass and ion translational energy-is underlined and applied to characterize the origin of the various species found in the experimental mass spectra. Finally, the PECD findings are discussed within an astrochemical context, and possible implications regarding the origin of biomolecular asymmetry are identified.

Published
2014
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38. Time-resolved inner-shell photoelectron spectroscopy: From a bound molecule to an isolated atom

Author

Brauße, Felix, primary, Goldsztejn, Gildas, additional, Amini, Kasra, additional, Boll, Rebecca, additional, Bari, Sadia, additional, Bomme, Cédric, additional, Brouard, Mark, additional, Burt, Michael, additional, de Miranda, Barbara Cunha, additional, Düsterer, Stefan, additional, Erk, Benjamin, additional, Géléoc, Marie, additional, Geneaux, Romain, additional, Gentleman, Alexander S., additional, Guillemin, Renaud, additional, Ismail, Iyas, additional, Johnsson, Per, additional, Journel, Loïc, additional, Kierspel, Thomas, additional, Köckert, Hansjochen, additional, Küpper, Jochen, additional, Lablanquie, Pascal, additional, Lahl, Jan, additional, Lee, Jason W. L., additional, Mackenzie, Stuart R., additional, Maclot, Sylvain, additional, Manschwetus, Bastian, additional, Mereshchenko, Andrey S., additional, Mullins, Terence, additional, Olshin, Pavel K., additional, Palaudoux, Jérôme, additional, Patchkovskii, Serguei, additional, Penent, Francis, additional, Piancastelli, Maria Novella, additional, Rompotis, Dimitrios, additional, Ruchon, Thierry, additional, Rudenko, Artem, additional, Savelyev, Evgeny, additional, Schirmel, Nora, additional, Techert, Simone, additional, Travnikova, Oksana, additional, Trippel, Sebastian, additional, Underwood, Jonathan G., additional, Vallance, Claire, additional, Wiese, Joss, additional, Simon, Marc, additional, Holland, David M. P., additional, Marchenko, Tatiana, additional, Rouzée, Arnaud, additional, and Rolles, Daniel, additional

Published
2018
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39. Coulomb explosion imaging of CH3I and CH2CII photodissociation dynamics

Author

Allum, Felix, Burt, Michael, Amini, Kasra, Boll, Rebecca, Kockert, Hansjochen, Olshin, Pavel K., Bari, Sadia, Bomme, Cedric, Brausse, Felix, de Miranda, Barbara Cunha, Duesterer, Stefan, Erk, Benjamin, Geleoc, Marie, Geneaux, Romain, Gentleman, Alexander S., Goldsztejn, Gildas, Guillemin, Renaud, Holland, David M. P., Ismail, Iyas, Johnsson, Per, Journel, Loic, Kuepper, Jochen, Lahl, Jan, Lee, Jason W. L., Maclot, Sylvain, Mackenzie, Stuart R., Manschwetus, Bastian, Mereshchenko, Andrey S., Mason, Robert, Palaudoux, Jerome, Piancastelli, Maria Novella, Penent, Francis, Rompotis, Dimitrios, Rouzee, Arnaud, Ruchon, Thierry, Rudenko, Artem, Savelyev, Evgeny, Simon, Marc, Schirmel, Nora, Stapelfeldt, Henrik, Techert, Simone, Travnikova, Oksana, Trippel, Sebastian, Underwood, Jonathan G., Vallance, Claire, Wiese, Joss, Ziaee, Farzaneh, Brouard, Mark, Marchenko, Tatiana, Rolles, Daniel, Allum, Felix, Burt, Michael, Amini, Kasra, Boll, Rebecca, Kockert, Hansjochen, Olshin, Pavel K., Bari, Sadia, Bomme, Cedric, Brausse, Felix, de Miranda, Barbara Cunha, Duesterer, Stefan, Erk, Benjamin, Geleoc, Marie, Geneaux, Romain, Gentleman, Alexander S., Goldsztejn, Gildas, Guillemin, Renaud, Holland, David M. P., Ismail, Iyas, Johnsson, Per, Journel, Loic, Kuepper, Jochen, Lahl, Jan, Lee, Jason W. L., Maclot, Sylvain, Mackenzie, Stuart R., Manschwetus, Bastian, Mereshchenko, Andrey S., Mason, Robert, Palaudoux, Jerome, Piancastelli, Maria Novella, Penent, Francis, Rompotis, Dimitrios, Rouzee, Arnaud, Ruchon, Thierry, Rudenko, Artem, Savelyev, Evgeny, Simon, Marc, Schirmel, Nora, Stapelfeldt, Henrik, Techert, Simone, Travnikova, Oksana, Trippel, Sebastian, Underwood, Jonathan G., Vallance, Claire, Wiese, Joss, Ziaee, Farzaneh, Brouard, Mark, Marchenko, Tatiana, and Rolles, Daniel

Abstract

The photodissociation dynamics of CH3I and CH2CII at 272 nm were investigated by time-resolved Coulomb explosion imaging, with an intense non-resonant 815nmprobe pulse. Fragment ion momenta over a widem/z range were recorded simultaneously by coupling a velocity map imaging spectrometer with a pixel imaging mass spectrometry camera. For both molecules, delay-dependent pump-probe features were assigned to ultraviolet-induced carbon-iodine bond cleavage followed by Coulomb explosion. Multi-mass imaging also allowed the sequential cleavage of both carbon-halogen bonds in CH2ClI to be investigated. Furthermore, delay-dependent relative fragment momenta of a pair of ions were directly determined using recoil-frame covariance analysis. These results are complementary to conventional velocity map imaging experiments and demonstrate the application of time-resolved Coulomb explosion imaging to photoinduced real-time molecular motion.

Published
2018
Full Text
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40. Time-resolved inner-shell photoelectron spectroscopy : From a bound molecule to an isolated atom

Author

Brasse, Felix, Goldsztejn, Gildas, Amini, Kasra, Boll, Rebecca, Bari, Sadia, Bomme, Cedric, Brouard, Mark, Burt, Michael, de Miranda, Barbara Cunha, Duesterer, Stefan, Erk, Benjamin, Geleoc, Marie, Geneaux, Romain, Gentleman, Alexander S., Guillemin, Renaud, Ismail, Iyas, Johnsson, Per, Journel, Loic, Kierspel, Thomas, Kockert, Hansjochen, Kuepper, Jochen, Lablanquie, Pascal, Lahl, Jan, Lee, Jason W. L., Mackenzie, Stuart R., Maclot, Sylvain, Manschwetus, Bastian, Mereshchenko, Andrey S., Mullins, Terence, Olshin, Pavel K., Palaudoux, Jerome, Patchkovskii, Serguei, Penent, Francis, Piancastelli, Maria Novella, Rompotis, Dimitrios, Ruchon, Thierry, Rudenko, Artem, Savelyev, Evgeny, Schirmel, Nora, Techert, Simone, Travnikova, Oksana, Trippel, Sebastian, Underwood, Jonathan G., Vallance, Claire, Wiese, Joss, Simon, Marc, Holland, David M. P., Marchenko, Tatiana, Rouzee, Arnaud, Rolles, Daniel, Brasse, Felix, Goldsztejn, Gildas, Amini, Kasra, Boll, Rebecca, Bari, Sadia, Bomme, Cedric, Brouard, Mark, Burt, Michael, de Miranda, Barbara Cunha, Duesterer, Stefan, Erk, Benjamin, Geleoc, Marie, Geneaux, Romain, Gentleman, Alexander S., Guillemin, Renaud, Ismail, Iyas, Johnsson, Per, Journel, Loic, Kierspel, Thomas, Kockert, Hansjochen, Kuepper, Jochen, Lablanquie, Pascal, Lahl, Jan, Lee, Jason W. L., Mackenzie, Stuart R., Maclot, Sylvain, Manschwetus, Bastian, Mereshchenko, Andrey S., Mullins, Terence, Olshin, Pavel K., Palaudoux, Jerome, Patchkovskii, Serguei, Penent, Francis, Piancastelli, Maria Novella, Rompotis, Dimitrios, Ruchon, Thierry, Rudenko, Artem, Savelyev, Evgeny, Schirmel, Nora, Techert, Simone, Travnikova, Oksana, Trippel, Sebastian, Underwood, Jonathan G., Vallance, Claire, Wiese, Joss, Simon, Marc, Holland, David M. P., Marchenko, Tatiana, Rouzee, Arnaud, and Rolles, Daniel

Abstract

Due to its element and site specificity, inner-shell photoelectron spectroscopy is a widely used technique to probe the chemical structure of matter. Here, we show that time-resolved inner-shell photoelectron spectroscopy can be employed to observe ultrafast chemical reactions and the electronic response to the nuclear motion with high sensitivity. The ultraviolet dissociation of iodomethane (CH3I) is investigated by ionization above the iodine 4d edge, using time-resolved inner-shell photoelectron and photoion spectroscopy. The dynamics observed in the photoelectron spectra appear earlier and are faster than those seen in the iodine fragments. The experimental results are interpreted using crystal-field and spin-orbit configuration interaction calculations, and demonstrate that time-resolved inner-shell photoelectron spectroscopy is a powerful tool to directly track ultrafast structural and electronic transformations in gas-phase molecules.

Published
2018
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41. Chiral Asymmetry in the Photoionization of Gas-Phase Amino-Acid Alanine at Lyman-α Radiation Wavelength

Author

Steven F. Daly, Gustavo García, François Gaie-Levrel, Ivan Powis, Maurice Tia, Barbara Cunha de Miranda, and Laurent Nahon

Subjects
Quantitative Biology::Biomolecules, Circular dichroism, education.field_of_study, Chemistry, media_common.quotation_subject, Population, Photoionization, Electron, Photon energy, Asymmetry, Ion, General Materials Science, Physical and Theoretical Chemistry, Atomic physics, education, Circular polarization, media_common
Abstract

Gas-phase pure enantiomers of alanine, the simplest proteinaceous chiral amino acid, are investigated by photoelectron circular dichroism, a direct chiroptical, orbital-sensitive effect giving rise to large asymmetries in the photoelectron angular distribution upon photoionization by circularly polarized light. Here we report electron imaging measurements made at the Lyman-α radiation photon energy (10.2 eV) that reveal a strong overall asymmetry for the outermost orbital. Despite the anticipated presence of different conformers, this asymmetry is effectively independent of sample temperature (and hence of conformer population). Furthermore, because of the associated recoiling of the corresponding ion, photoionization by circularly polarized light can generate an asymmetric flux of gas-phase alanine cations, allowing us to deduce an enantiomeric excess, in a given line of sight, of up to 4%. In addition to the implications for the origin of biomolecular asymmetry, these studies pave the way for future chi...

Published
2013
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42. Coulomb-explosion imaging of concurrent CH 2 BrI photodissociation dynamics

Author

Michael Burt, Rebecca Boll, Jason W. L. Lee, Kasra Amini, Hansjochen Köckert, Claire Vallance, Alexander S. Gentleman, Stuart R. Mackenzie, Sadia Bari, Cédric Bomme, Stefan Düsterer, Benjamin Erk, Bastian Manschwetus, Erland Müller, Dimitrios Rompotis, Evgeny Savelyev, Nora Schirmel, Simone Techert, Rolf Treusch, Jochen Küpper, Sebastian Trippel, Joss Wiese, Henrik Stapelfeldt, and Barbara Cunha

Published
2017
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43. Selected Ion Flow Tube Study of Ion–Molecule Reactions of N+(3P) and Kr+ with C3 Hydrocarbons Propane, Propene, and Propyne

Author

Kseniya Dryahina, Ján Žabka, Zdenek Herman, Christian Alcaraz, Barbara Cunha de Miranda, and Patrik Španěl

Subjects
chemistry.chemical_classification, Chemistry, Analytical chemistry, Propyne, Ion, Propene, chemistry.chemical_compound, Electron transfer, Hydrocarbon, Reaction rate constant, Propane, Organic chemistry, Molecule, Physical and Theoretical Chemistry
Abstract

Reactions of (14)N(+)((3)P), (15)N(+)((3)P), and Kr(+) with propane, propene, and propyne were studied using the selected ion flow tube, SIFT, technique. Thermal rate constants in all N(+)/C(3) systems were k = (2 ± 0.4) × 10(-9) cm(3) molecule(-1) s(-1), close to the collisional rate constants. With propane and propene, only hydrocarbon ions were found among the products of reactions with N(+); in propyne about 15% of the products were N-containing ions (C(3)H(2)N(+), C(2)H(4)N(+), C(2)H(3)N(+), C(2)H(2)N(+)), and the rest were hydrocarbon ions. A comparison with product ions from electron transfer between Kr(+) (of recombination energy similar to that for N(+)((3)P)) and the C(3) hydrocarbons and further analysis of the results led to an estimation of an approximate ratio of electron transfer vs hydride-ion transfer reactions leading to the hydrocarbon product ions: in propane the ratio was 2:1, in propene 3:1, and in propyne 5:1. A fraction of product ions resulted from reactions leading to the excited neutral product N*.

Published
2011
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44. Photoionization of Propargyl and Bromopropargyl Radicals: A Threshold Photoelectron Spectroscopic Study

Author

Barbara Cunha de Miranda, Bastian Noller, Patrick Hemberger, Héloïse Soldi-Lose, Melanie Lang, Christian Alcaraz, Gustavo A. Garcia, and Ingo Fischer

Subjects
Flash (photography), Chemistry, Radical, Propargyl, Reactive intermediate, Photoionization, Physical and Theoretical Chemistry, Photochemistry, Pyrolysis, Spectral line
Abstract

In this Article, we present mass-selected threshold photoelectron spectra of propargyl as well as the 1- and 3-bromopropargyl radicals. The reactive intermediates were produced by flash pyrolysis of suitable precursors and ionized by VUV synchrotron radiation. The TPES of the propargyl radical was simulated using data from a recent high-level computational study. An ionization energy (IE) of 8.71 ± 0.02 eV was obtained, in excellent agreement with computations, but slightly above previous experimental IEs. The pyrolysis of 1,3-dibromopropyne delivers both 1- and 3-bromopropargyl radicals that can be distinguished by their different ionization energies (8.34 and 8.16 eV). To explain the vibrational structure, a Franck-Condon simulation was performed, based on DFT calculations, which can account for all major spectral features. Bromopropargyl photoionizes dissociatively beginning at around 10.1 eV. Cationic excited states of 1- and 3-bromopropargyl were tentatively identified. The dissociative photoionization of the precursor (1,3-dibromopropyne) was also examined, delivering an AE(0K) (C(3)H(2)Br(+)/C(3)H(2)Br(2)) of 10.6 eV.

Published
2011
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45. Age of first deciduous tooth eruption in a Portuguese children population: a cross-sectional study

Author

Bárbara Cunha, Manuel Salgado, Francisco Caramelo, and Ana Luísa Costa

Subjects
age of eruption, deciduous tooth, tooth eruption, Dentistry, RK1-715
Abstract

Objectives: To define the timing of the first deciduous tooth eruption in a sample of Portuguese children. Methods: Observational study including a convenience sample of 2115 healthy Portuguese children aged between 1-24 months. A single clinician performed the oral observation under an artificial light source, identifying the first erupted deciduous tooth and registering age (in months). Data were analyzed with IBM® SPSS® v24, R v3.3.2, and Python v3.7.1 (α=0.05). The percentiles of the age of first tooth eruption were determined, along with the cumulative probability curve for both genders and the proportion of first erupted tooth type per gender with its confidence interval. Results: The age of first tooth eruption was slightly inferior in males (mean=7.01 (± 2.24); median=6.0 months; 95% CI [5.8, 6.2]) than in females (mean=7.55 (± 2.41); median=6.5 months; 95% CI [6.3, 6.7]), with a statistically significant difference. The first deciduous tooth erupting was the mandibular central incisor, on average, at 6.94 (± 2.10) months in males and 7.49 (± 2.17) months in females. Conclusions: The present study indicates that, unequivocally, the mandibular central incisor was most often the first deciduous tooth to erupt, and, on average, that happened at 6.94 months for males and at 7.49 months for females.

Published
2022
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47. Molecular Isomer Identification of Titan’s Tholins Organic Aerosols by Photoelectron/Photoion Coincidence Spectroscopy Coupled to VUV Synchrotron Radiation

Author

Benjamin Fleury, Barbara Cunha de Miranda, Nathalie Carrasco, Gustavo García, Thomas Gautier, Pascal Pernot, Laurent Nahon, François Gaie-Levrel, Ahmed Mahjoub, Synchrotron SOLEIL (SSOLEIL), Centre National de la Recherche Scientifique (CNRS), Laboratoire National de Métrologie et d'Essais [Trappes] (LNE ), PLANETO - LATMOS, Laboratoire Atmosphères, Milieux, Observations Spatiales (LATMOS), Université de Versailles Saint-Quentin-en-Yvelines (UVSQ)-Université Pierre et Marie Curie - Paris 6 (UPMC)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS)-Université de Versailles Saint-Quentin-en-Yvelines (UVSQ)-Université Pierre et Marie Curie - Paris 6 (UPMC)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS), NASA Goddard Space Flight Center (GSFC), Laboratoire de Chimie Physique D'Orsay (LCPO), Université Paris-Sud - Paris 11 (UP11)-Institut de Chimie du CNRS (INC)-Centre National de la Recherche Scientifique (CNRS), Institut Universitaire de France (IUF), Ministère de l'Education nationale, de l’Enseignement supérieur et de la Recherche (M.E.N.E.S.R.), and European Project: 636829,H2020,ERC-2014-STG,PRIMCHEM(2015)

Subjects
Earth and Planetary Astrophysics (astro-ph.EP), Chemical Physics (physics.chem-ph), 010304 chemical physics, Chemistry, Analytical chemistry, [SDU.ASTR.EP]Sciences of the Universe [physics]/Astrophysics [astro-ph]/Earth and Planetary Astrophysics [astro-ph.EP], FOS: Physical sciences, Synchrotron radiation, Tholin, Photoelectron photoion coincidence spectroscopy, 010402 general chemistry, 01 natural sciences, Synchrotron, Spectral line, 0104 chemical sciences, law.invention, Ion, Beamline, law, Physics - Chemical Physics, 0103 physical sciences, Molecule, Physical and Theoretical Chemistry, Astrophysics - Earth and Planetary Astrophysics
Abstract

International audience; The chemical composition of Titan organic haze is poorly known. To address this issue, laboratory analogues named tholins are synthesized and analyzed by methods often requiring an extraction process in a carrier solvent. These methods exclude the analysis of the insoluble tholins’ fraction and assume a hypothetical chemical equivalence between soluble and insoluble fractions. In this work, we present a powerful complementary analysis method recently developed on the DESIRS VUV synchrotron beamline at SOLEIL. It involves soft pyrolysis of tholins at ∼230 °C and electron/ion coincidence analysis of the emitted volatile compounds photoionized by tunable synchrotron radiation. By comparison with reference photoelectron spectra (PES), the spectral information collected on the detected molecules yields their isomeric structure. The method is more readily applied to light species (m/z ≤ 69), while for heavier ones, the number of possibilities and the lack of PES reference spectra in the literature limit its analysis. A notable pattern in the analyzed tholins is the presence of species containing adjacent doubly bonded N atoms, which might be a signature of heterogeneous incorporation of N2 in tholins.

Published
2016
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48. Coulomb-explosion imaging of concurrent CH2BrI photodissociation dynamics

Author

Burt, Michael, primary, Boll, Rebecca, additional, Lee, Jason W. L., additional, Amini, Kasra, additional, Köckert, Hansjochen, additional, Vallance, Claire, additional, Gentleman, Alexander S., additional, Mackenzie, Stuart R., additional, Bari, Sadia, additional, Bomme, Cédric, additional, Düsterer, Stefan, additional, Erk, Benjamin, additional, Manschwetus, Bastian, additional, Müller, Erland, additional, Rompotis, Dimitrios, additional, Savelyev, Evgeny, additional, Schirmel, Nora, additional, Techert, Simone, additional, Treusch, Rolf, additional, Küpper, Jochen, additional, Trippel, Sebastian, additional, Wiese, Joss, additional, Stapelfeldt, Henrik, additional, de Miranda, Barbara Cunha, additional, Guillemin, Renaud, additional, Ismail, Iyas, additional, Journel, Loïc, additional, Marchenko, Tatiana, additional, Palaudoux, Jérôme, additional, Penent, Francis, additional, Piancastelli, Maria Novella, additional, Simon, Marc, additional, Travnikova, Oksana, additional, Brausse, Felix, additional, Goldsztejn, Gildas, additional, Rouzée, Arnaud, additional, Géléoc, Marie, additional, Geneaux, Romain, additional, Ruchon, Thierry, additional, Underwood, Jonathan, additional, Holland, David M. P., additional, Mereshchenko, Andrey S., additional, Olshin, Pavel K., additional, Johnsson, Per, additional, Maclot, Sylvain, additional, Lahl, Jan, additional, Rudenko, Artem, additional, Ziaee, Farzaneh, additional, Brouard, Mark, additional, and Rolles, Daniel, additional

Published
2017
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49. Vibronic structure of the 2 Π u ground electronic state of dicyanoacetylene cation revisited by PFI-ZEKE photoelectron spectroscopy and ab initio calculations

Author

Barbara Cunha de Miranda, Christian Alcaraz, Bérenger Gans, Michel Broquier, Séverine Boyé-Péronne, Jacques Liévin, Jean-Claude Guillemin, Nicolas Lamarre, Institut des Sciences Moléculaires d'Orsay (ISMO), Université Paris-Sud - Paris 11 (UP11)-Centre National de la Recherche Scientifique (CNRS), Laboratoire de Chimie Physique D'Orsay (LCPO), Université Paris-Sud - Paris 11 (UP11)-Institut de Chimie du CNRS (INC)-Centre National de la Recherche Scientifique (CNRS), Laboratoire de Chimie Physique - Matière et Rayonnement (LCPMR), Université Pierre et Marie Curie - Paris 6 (UPMC)-Institut de Chimie du CNRS (INC)-Centre National de la Recherche Scientifique (CNRS), Institut des Sciences Chimiques de Rennes (ISCR), Centre National de la Recherche Scientifique (CNRS)-Institut de Chimie du CNRS (INC)-Université de Rennes 1 (UR1), Université de Rennes (UNIV-RENNES)-Université de Rennes (UNIV-RENNES)-Ecole Nationale Supérieure de Chimie de Rennes (ENSCR)-Institut National des Sciences Appliquées - Rennes (INSA Rennes), Institut National des Sciences Appliquées (INSA)-Université de Rennes (UNIV-RENNES)-Institut National des Sciences Appliquées (INSA), Centre Laser de l'Université Paris Sud (CLUPS), Université Paris-Sud - Paris 11 (UP11), Service de Chimie Quantique et Photophysique, Université libre de Bruxelles (ULB), Université de Rennes (UR)-Institut National des Sciences Appliquées - Rennes (INSA Rennes), and Institut National des Sciences Appliquées (INSA)-Institut National des Sciences Appliquées (INSA)-Ecole Nationale Supérieure de Chimie de Rennes (ENSCR)-Institut de Chimie du CNRS (INC)-Centre National de la Recherche Scientifique (CNRS)

Subjects
Coupling constant, Renner–Teller effect, PFI-ZEKE PES, Photoemission spectroscopy, Chemistry, ab initio calculations, Biophysics, spin–orbit interaction, Spin–orbit interaction, 2-butynedinitrile, Condensed Matter Physics, 7. Clean energy, Dicyanoacetylene, dicyanoacetylene, [CHIM.THEO]Chemical Sciences/Theoretical and/or physical chemistry, chemistry.chemical_compound, Ab initio quantum chemistry methods, Physics::Atomic and Molecular Clusters, Complete active space, Physical and Theoretical Chemistry, Atomic physics, Ground state, Molecular Biology
Abstract

International audience; (2015): Vibronic structure of the 2 Π u ground electronic state of dicyanoacetylene cation revisited by PFI-ZEKE photoelectron spectroscopy and ab initio calculations, Molecular Physics, The X +2 u ← X 1 + g transition of dicyanoacetylene has been recorded for the first time using pulsed-field-ionisation zero-kinetic-energy photoelectron spectroscopy. The analysis of the photoelectron spectrum allowed an accurate determination of the adiabatic ionisation potential of C 4 N 2 (E i, ad. /hc = 95,479 ± 2 cm −1) and a description of the vibrational structure of the electronic ground state of the cation which is affected by the Renner–Teller effect and the spin–orbit interaction. The spin–orbit coupling constant was measured as −52 ± 2 cm −1. These results are supported by ab initio calculations performed at the complete active space self-consistent field and second-order perturbation theory levels of theory, with extrapolation to the complete basis set limit.

Published
2015
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