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1. A perfect X-ray beam splitter and its applications to time-domain interferometry and quantum optics exploiting free-electron lasers

Author

Reiche, S., Knopp, G., Pedrini, B., Prat, E., Aeppli, G., and Gerber, S.

Subjects
Physics - Accelerator Physics, Condensed Matter - Materials Science, Condensed Matter - Strongly Correlated Electrons, Physics - Atomic and Molecular Clusters, Quantum Physics
Abstract

X-ray free-electron lasers (FEL) deliver ultrabright X-ray pulses, but not the sequences of phase-coherent pulses required for time-domain interferometry and control of quantum states. For conventional split-and-delay schemes to produce such sequences the challenge stems from extreme stability requirements when splitting Angstrom wavelength beams where tiniest path length differences introduce phase jitter. We describe an FEL mode based on selective electron bunch degradation and transverse beam shaping in the accelerator, combined with a self-seeded photon emission scheme. Instead of splitting the photon pulses after their generation by the FEL, we split the electron bunch in the accelerator, prior to photon generation, to obtain phase-locked X-ray pulses with sub-femtosecond duration. Time-domain interferometry becomes possible, enabling the concomitant program of classical and quantum optics experiments with X-rays. The scheme leads to new scientific benefits of cutting-edge FELs with attosecond and/or high-repetition rate capabilities, ranging from the X-ray analog of Fourier transform infrared spectroscopy to damage-free measurements.

Published
2020
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2. Investigations of ultrafast dynamics in electronically excited alkylbenzenes

Author

Maksyutenko P., Sych Y., Radi P., Gerber T., Liu Y., and Knopp G.

Subjects
Physics, QC1-999
Abstract

We investigate ultrafast dynamics in electronically excited states of some typical alkylbenzenes by time-resolved two-colour four wave mixing and velocity map imaging as complementary methods. In this context an upgraded double-sided time-resolved velocity map imaging setup is also proposed.

Published
2013
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4. Nanoseconds field emitted current pulses from ZrC needles and field emitter arrays

Author

Ganter, R., Bakker, R. J., Betemps, R., Dehler, M., Gerber, T., Gobrecht, J., Gough, C., Johnson, M., Kirk, E., Knopp, G., Pimpec, F. Le, Li, K., Paraliev, M., Pedrozzi, M., Rivkin, L., Sehr, H., Schulz, L., and Wrulich, A.

Subjects
Physics - Accelerator Physics
Abstract

The properties of the electron source define the ultimate limit of the beam quality in linear accelerators like Free Electron Lasers (FEL). The goal is to develop an electron gun delivering beam emittance lower than current state of the art. Such a gun should reduce the cost and size of an X-ray Free Electron Laser (XFEL). In this paper we present two concepts of field emitter cathodes which could potentially produce low emittance beam. The first challenging parameter for such cathode is to emit peak current as high as 5 A. This is the minimum current requirement for the XFEL concept from Paul Scherrer Institut.1 Maximum current of 0.12 A and 0.58 A have been reached respectively with field emitter arrays (FEA) and single needle cathodes. Laser assisted field emission gave encouraging results to reach even higher peak current and to pre-bunch the beam., Comment: 23 pages, 1 table, 9 figures Accepted for publication in JVST B

Published
2006
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5. All X-Ray Four-Wave Mixing on a Gas Phase Sample

Author

Morillo-Candas, A.S., primary, Al-Haddad, A., additional, Augustin, S., additional, Cannizzo, A., additional, Deng, Y., additional, Feurer, T., additional, Knurr, J., additional, Ott, C., additional, Prat, E., additional, Rebholz, M., additional, Sarracini, A., additional, Schnorr, K., additional, Sun, Z., additional, Xie, X., additional, Yang, N., additional, Zerdane, S., additional, Zhang, H., additional, Pfeifer, T., additional, Bostedt, C., additional, and Knopp, G., additional

Published
2023
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6. Time Resolved Hard X-ray/Optical Transient Grating Spectroscopy on a Liquid Jet

Author

Morillo-Candas, A.S., primary, Al-Haddad, A., additional, Augustin, S., additional, Bacellar, C., additional, Cannizzo, A., additional, Cirelli, C., additional, David, C., additional, Fainozzi, D., additional, Feurer, T., additional, Johnson, P., additional, Maznev, A., additional, Nelson, K., additional, Mamyrbayev, T., additional, Schnorr, K., additional, Svetina, C., additional, Vila-Comamala, J., additional, Chergui, M., additional, Bostedtl, C., additional, and Knopp, G, additional

Published
2023
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8. Ultrafast Energy Transfer from Photoexcited Tryptophan to the Haem in Cytochrome c

Author

Bacellar C., Rouxel J.R., Ingle R.A., Mancini G.F., Kinschel D., Cannelli O., Zhao Y., Cirelli C., Knopp G., Szlachetko J., Lima F.A., Menzi S., Ozerov D., Pamfilidis G., Kubicek K., Khakhulin D., Gawelda W., Rodriguez-Fernandez A., Biednov M., Bressler C., Arrell C.A., Johnson P.J.M., Milne C.J., Chergui M., Bacellar C., Rouxel J.R., Ingle R.A., Mancini G.F., Kinschel D., Cannelli O., Zhao Y., Cirelli C., Knopp G., Szlachetko J., Lima F.A., Menzi S., Ozerov D., Pamfilidis G., Kubicek K., Khakhulin D., Gawelda W., Rodriguez-Fernandez A., Biednov M., Bressler C., Arrell C.A., Johnson P.J.M., Milne C.J., and Chergui M.

Published
2023

9. Time Resolved Hard X-ray/Optical Transient Grating Spectroscopy on a Liquid Jet

Author

Morillo-Candas A.S., Al-Haddad A., Augustin S., Bacellar C., Cannizzo A., Cirelli C., David C., Fainozzi D., Feurer T., Johnson P., Maznev A., Nelson K., Mamyrbayev T., Schnorr K., Svetina, Cristian, Vila-Comamala J., Chergui M., Bostedt C., Knopp G., Morillo-Candas A.S., Al-Haddad A., Augustin S., Bacellar C., Cannizzo A., Cirelli C., David C., Fainozzi D., Feurer T., Johnson P., Maznev A., Nelson K., Mamyrbayev T., Schnorr K., Svetina, Cristian, Vila-Comamala J., Chergui M., Bostedt C., and Knopp G.

Published
2023

10. Noncollinear, inelastic four-wave mixing in the extreme ultraviolet

Author

Mincigrucci R., Cannizzo A., Capotondi F., Cinquegrana P., Cucini R., Dallari F., Danailov M.B., De Ninno G., Mitri S.Di., Feurer T., Foglia L., Frei H.-M., Manfredda M., Maznev A.A., Monaco G., Naumenko D., Nikolov I., Ollmann Z., Paltanin E., Pamfilidis G., Pedersoli E., Principi E., Rehault J., Simoncig A., Svetina, Cristian, Knopp G., Masciovecchio C., Bencivenga F., Mincigrucci R., Cannizzo A., Capotondi F., Cinquegrana P., Cucini R., Dallari F., Danailov M.B., De Ninno G., Mitri S.Di., Feurer T., Foglia L., Frei H.-M., Manfredda M., Maznev A.A., Monaco G., Naumenko D., Nikolov I., Ollmann Z., Paltanin E., Pamfilidis G., Pedersoli E., Principi E., Rehault J., Simoncig A., Svetina, Cristian, Knopp G., Masciovecchio C., and Bencivenga F.

Published
2023

11. Frequency and spatially chirped free-electron laser pulses

Author

Reiche, S., primary, Bacellar, C., additional, Bougiatioti, P., additional, Cirelli, C., additional, Dijkstal, P., additional, Ferrari, E., additional, Juranić, P., additional, Knopp, G., additional, Malyzhenkov, A., additional, Milne, C., additional, Nass, K., additional, Prat, E., additional, Vila-Comamala, J., additional, and David, C., additional

Published
2023
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12. Accurate ground state potential of Cu2 up to the dissociation limit by perturbation assisted double-resonant four-wave mixing.

Author

Bornhauser, P., Beck, M., Zhang, Q., Knopp, G., Marquardt, R., Gourlaouen, C., and Radi, P. P.

Subjects
FOUR-wave mixing, SCHRODINGER equation, ENERGY function, POTENTIAL functions, POTENTIAL energy
Abstract

Perturbation facilitated double-resonant four-wave mixing is applied to access high-lying vibrational levels of the X 1 Σ g + ( 0 g + ) ground state of Cu2. Rotationally resolved transitions up to v ″ = 102 are measured. The highest observed level is at 98% of the dissociation energy. The range and accuracy of previous measurements are significantly extended. By applying the near dissociation equation developed by Le Roy [R. J. Le Roy, J. Quant. Spectrosc. Radiat. Transfer 186, 197 (2017)], a dissociation energy of De = 16 270(7) hc cm−1 is determined, and an accurate potential energy function for the X 1 Σ g + ( 0 g + ) ground state is obtained. Molecular constants are determined from the measured transitions and by solving the radial Schrödinger equation using this function and are compared with results from earlier measurements. In addition, benchmark multi-reference configuration interaction computations are performed using the Douglas–Kroll–Hess Hamiltonian and the appropriate basis of augmented valence quadruple ζ type. Coupled-cluster single, double, and perturbative triple calculations were performed for comparison. [ABSTRACT FROM AUTHOR]

Published
2020
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13. Influence of pump laser fluence on ultrafast structural changes in myoglobin

Author

Barends, T., Bhattacharyya, S., Gorel, A., Schiro, G., Bacellar, C., Cirelli, C., Colletier, J., Foucar, L., Grünbein, M., Hartmann, E., Hilpert, M., Johnson, P., Kloos, M., Knopp, G., Marekha, B., Nass, K., Nass Kovacs, G., Ozerov, D., Stricker, M., Weik, M., Doak, R., Shoeman, R., Milne, C., Huix-Rotllant, M., Cammarata, M., and Schlichting, I.

Abstract

SummaryHigh-intensity femtosecond pulses from an X-ray free-electron laser enable pump probe experiments for investigating electronic and nuclear changes during light-induced reactions. On time scales ranging from femtoseconds to milliseconds and for a variety of biological systems, time-resolved serial femtosecond crystallography (TR-SFX) has provided detailed structural data for light-induced isomerization, breakage or formation of chemical bonds and electron transfer1. However, all ultra-fast TR-SFX studies to date have employed such high pump laser energies that several photons were nominally absorbed per chromophore2-14. As multiphoton absorption may force the protein response into nonphysiological pathways, it is of great concern15whether this experimental approach16allows valid inferences to be drawn vis-à-vis biologically relevant single-photon-induced reactions17. Here we describe ultrafast pump-probe SFX experiments on photodissociation of carboxymyoglobin, showing that different pump laser fluences yield markedly different results. In particular, the dynamics of structural changes and observed indicators of the mechanistically important coherent oscillations of the Fe-CO bond distance (predicted by recent quantum wavepacket dynamics15) are seen to depend strongly on pump laser energy. Our results confirm both the feasibility and necessity of performing TR-SFX pump probe experiments in the linear photoexcitation regime. We consider this to be a starting point for reassessing design and interpretation of ultrafast TR-SFX pump probe experiments16such that biologically relevant insight emerges.

Published
2022
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15. Decreasing time to antiretroviral therapy initiation after HIV diagnosis in a clinic‐based observational cohort study in four African countries

Author

Esber, Allahna L., Coakley, Peter, Ake, Julie A., Bahemana, Emmanuel, Adamu, Yakubu, Kiweewa, Francis, Maswai, Jonah, Owuoth, John, Robb, Merlin L., Polyak, Christina S., Crowell, Trevor A., Parikh, A, Hern, J, Falodun, O, Song, K, Milazzo, M, Dear, N, Francisco, L, Mankiewicz, S, Schech, S, Golway, A, Mebrahtu, T, Lee, E, Bohince, K, Hamm, T, Lombardi, K, Imbach, M, Eller, L, Peel, S, Malia, J, Kroidl, A, Kroidl, I, Geldmacher, C, Kafeero, C, Nambuya, A, Tegamanyi, J, Birungi, H, Mugagga, O, Nassali, G, Wangiri, P, Nantabo, M, Nambulondo, P, Atwijuka, B, Asiimwe, A, Nabanoba, Ct, Semwogerere, M, Mwesigwa, R, Jjuuko, S, Namagembe, R, Bagyendagye, E, Tindikahwa, A, Rwomushana, I, Ssentongo, F, Kibuuka, H, Millard, M, Kapkiai, J, Wangare, S, Mangesoi, R, Chepkwony, P, Bor, L, Maera, E, Kasembeli, A, Rotich, J, Kipkoech, C, Chepkemoi, W, Rono, A, Kesi, Zeddy, Ngeno, Janet, Langat, Edwin, Labosso, Keneddy, Langat, Ken, Kirui, Robert, Rotich, L, Mabwai, M, Chelangat, E, Agutu, J, Tonui, C, Changwony, E, Bii, M, Chumba, E, Korir, J, Sugut, J, Gitonga, D, Ngetich, R, Kiprotich, S, Rehema, W, Ogari, C, Ouma, I, Adimo, O, Ogai, S, Okwaro, C, Maranga, E, Ochola, J, Obambo, K, Sing'Oei, V, Otieno, L, Nyapiedho, O, Sande, N, Odemba, E, Wanjiru, F, Khamadi, S, Chiweka, E, Lwilla, A, Mkondoo, D, Somi, N, Kiliba, P, Nwando, M, Mwaisanga, G, Muhumuza, J, Mkingule, N, Mwasulama, O, Sanagare, A, Kishimbo, P, David, G, Mbwayu, F, Mwamwaja, J, Likiliwike, J, Mcharo, R, Mtafya, B, Lueer, C, Kisinda, A, Mbena, T, Mfumbulwa, H, Mwandumbya, L, Edwin, P, Olomi, W, Adamu, Y, Akintunde, A, Tiamiyu, Ab, Afoke, K, Mohammed, S, Harrison, Ne, Agbaim, Uc, Adegbite, Oa, Parker, Z, Adelakun, Ga, Oni, Fo, Ndbuisi, Ro, Elemere, J, Azuakola, N, Williams, Tt, Ayogu, M, Enas, O, Enameguono, O, Odo, Af, Ukaegbu, Ic, Ugwuezumba, O, Odeyemi, So, Okeke, Nc, Umeji, L, Rose, A, Daniel, H, Nwando, H, Nicholas, Ei, Iyanda, T, Okolo, C, Mene, Vy, Dogonyaro, B, Olabulo, O, Akinseli, O, Onukun, F, and Knopp, G

Subjects
Practice guidelines (Medicine) -- Evaluation, Antiviral agents -- Dosage and administration, HIV infection -- Diagnosis -- Drug therapy, Health
Abstract

: Introduction: World Health Organization (WHO) guidelines have shifted over time to recommend earlier initiation of antiretroviral therapy (ART) and now encourage ART initiation on the day of HIV diagnosis, if possible. However, barriers to ART access may delay initiation in resource‐limited settings. We characterized temporal trends and other factors influencing the interval between HIV diagnosis and ART initiation among participants enrolled in a clinic‐based cohort across four African countries. Methods: The African Cohort Study enrols adults engaged in care at 12 sites in Uganda, Kenya, Tanzania and Nigeria. Participants provide a medical history, complete a physical examination and undergo laboratory assessments every six months. Participants with recorded dates of HIV diagnosis were categorized by WHO guideline era ( Results and discussion: From January 2013 to September 2019, a total of 2888 adults living with HIV enrolled with known diagnosis dates. Median time to ART initiation decreased from 22.0 months (interquartile range (IQR) 4.0 to 77.3) among participants diagnosed prior to 2006 to 0.5 months (IQR 0.2 to 1.8) among those diagnosed in 2016 and later. Comparing those same periods, CD4 nadir increased from a median of 166 cells/mm[sup.3] (IQR: 81 to 286) to 298 cells/mm[sup.3] (IQR: 151 to 501). In the final adjusted model, participants diagnosed in each subsequent WHO guideline era had increased rates of ART initiation compared to those diagnosed before 2006. CD4 nadir ≥500 cells/mm[sup.3] was independently associated with a lower rate of ART initiation as compared to CD4 nadir 50 years at diagnosis was independently associated with shorter time to ART initiation as compared to 18 to 29 years (HR: 1.38; 95% CI: 1.19 to 1.61). Conclusions: Consistent with changing guidelines, the interval between diagnosis and ART initiation has decreased over time. Still, many adults living with HIV initiated treatment with low CD4, highlighting the need to diagnose HIV earlier while improving access to immediate ART after diagnosis., Introduction The introduction of antiretroviral therapy (ART) proved a turning point in the fight against HIV, leading to dramatic decreases in HIV‐related morbidity and mortality. However, the first ART regimens [...]

Published
2020
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18. NmHR light state structure at 55 ms (50 - 60 ms) after photoexcitation determined by serial millisecond crystallography

Author

Mous, S., primary, Gotthard, G., additional, Ehrenberg, D., additional, Sen, S., additional, James, D., additional, Johnson, P., additional, Weinert, T., additional, Nass, K., additional, Furrer, A., additional, Kekilli, D., additional, Ma, P., additional, Bruenle, S., additional, Casadei, C., additional, Martiel, I., additional, Dworkowski, F., additional, Gashi, D., additional, Skopintsev, P., additional, Wranik, M., additional, Knopp, G., additional, Panepucci, E., additional, Panneels, V., additional, Cirelli, C., additional, Ozerov, D., additional, Schertler, G., additional, Wang, M., additional, Milne, C., additional, Standfuss, J., additional, Schapiro, I., additional, Heberle, J., additional, and Nogly, P., additional

Published
2022
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19. Anomalous bromide substructure of NmHR under dark state conditions determined at 13.7 keV with serial crystallography

Author

Mous, S., primary, Gotthard, G., additional, Ehrenberg, D., additional, Sen, S., additional, James, D., additional, Johnson, P., additional, Weinert, T., additional, Nass, K., additional, Furrer, A., additional, Kekilli, D., additional, Ma, P., additional, Bruenle, S., additional, Casadei, C., additional, Martiel, I., additional, Dworkowski, F., additional, Gashi, D., additional, Skopintsev, P., additional, Wranik, M., additional, Knopp, G., additional, Panepucci, E., additional, Panneels, V., additional, Cirelli, C., additional, Ozerov, D., additional, Schertler, G., additional, Wang, M., additional, Milne, C., additional, Standfuss, J., additional, Schapiro, I., additional, Heberle, J., additional, and Nogly, P., additional

Published
2022
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20. Erratum: “Nonlinear XUV-optical transient grating spectroscopy at the Si L2,3-edge” [Appl. Phys. Lett. 114, 181101 (2019)]

Author

Bohinc, R., primary, Pamfilidis, G., additional, Rehault, J., additional, Radi, P., additional, Milne, C., additional, Szlachetko, J., additional, Bencivenga, F., additional, Capotondi, F., additional, Cucini, R., additional, Foglia, L., additional, Masciovecchio, C., additional, Mincigrucci, R., additional, Pedersoli, E., additional, Simoncig, A., additional, Mahne, N., additional, Cannizzo, A., additional, Frey, H. M., additional, Ollmann, Z., additional, Feurer, T., additional, Maznev, A. A., additional, Nelson, K., additional, and Knopp, G., additional

Published
2021
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21. Nonlinear XUV-optical transient grating spectroscopy at the Si L2,3–edge

Author

Massachusetts Institute of Technology. Department of Chemistry, Bohinc, R., Pamfilidis, G., Rehault, J., Radi, P., Milne, C., Szlachetko, J., Bencivenga, F., Capotondi, F., Cucini, R., Foglia, L., Masciovecchio, C., Mincigrucci, R., Pedersoli, E., Simoncig, A., Mahne, N., Cannizzo, A., Frey, H.M., Ollmann, Z., Feurer, T., Maznev, A. A., Nelson, K., Knopp, G., Massachusetts Institute of Technology. Department of Chemistry, Bohinc, R., Pamfilidis, G., Rehault, J., Radi, P., Milne, C., Szlachetko, J., Bencivenga, F., Capotondi, F., Cucini, R., Foglia, L., Masciovecchio, C., Mincigrucci, R., Pedersoli, E., Simoncig, A., Mahne, N., Cannizzo, A., Frey, H.M., Ollmann, Z., Feurer, T., Maznev, A. A., Nelson, K., and Knopp, G.

Abstract

Time-resolved transient grating (TG) spectroscopy facilitates detailed studies of electron dynamics and transport phenomena by means of a periodic excitation of matter with coherent ultrashort light pulses. Several current and next generation free-electron laser (FEL) facilities provide fully coherent pulses with few femtosecond pulse durations and extreme ultraviolet (XUV) photon energies. Thus, they allow for transient grating experiments with periodicities as small as tens of nanometers and with element specific photon energies. Here, we demonstrate the element specificity of XUV TG (X-TG) experiments by tuning the photon energy across the Si L₂,₃-edge of Si₃N₄. We observe a shortening of the signal decay when increasing the XUV photon energy above the absorption edge. The analysis of the wavelength dependent signal shows that the faster decay is driven by the increase in the charge carrier density. From the decay constants the interband Auger coefficient at elevated temperatures and high electron densities has been determined., Swiss National Science Foundation (SNF) (Grant 200021_165550/1)

Published
2021

22. Identification of a new low energy 1u state in dicopper with resonant four-wave mixing.

Author

Visser, B., Beck, M., Bornhauser, P., Knopp, G., van Bokhoven, J. A., Marquardt, R., Gourlaouen, C., and Radi, P. P.

Subjects
COPPER, RESONANT states, FOUR-wave mixing, ELECTRONIC structure, MOLECULAR spectroscopy, MOLECULAR rotation, EXCITED states
Abstract

The low energy electronic structure of the copper dimer has been re-investigated using non-linear four-wave mixing spectroscopy and high level ab initio calculations. In addition to the measurement of the previously reported A, B, and C electronic states, a new state denoted A' is identified with T0 = 20 100.4090(16) cm-1 (63Cu2). Rotational analysis of the A'-X (0,0) and (1,0) transitions leads to the assignment of A' 1u. Ab initio calculations present the first theoretical description of the lowenergy states of the copper dimer in Hund's case (c) and confirm the experimental assignment. The discovery of this new low energy excited state emphasizes that spin-orbit coupling is significant in states with d-hole electronic configurations and resolves a decades-long mystery in the initial assignment of the A state. [ABSTRACT FROM AUTHOR]

Published
2017
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23. Experimental and theoretical investigation of the vibrational band structure of the 1 5Πu - 1 5Πg high-spin system of C2.

Author

Bornhauser, P., Visser, B., Beck, M., Knopp, G., van Bokhoven, J. A., Marquardt, R., and Radi, P. P.

Subjects
EXCITED states, NUCLEAR spin, FLUORESCENCE, POTENTIAL energy surfaces, SPECTRUM analysis
Abstract

Vibrational levels of the recently observed high-spin transition (1 5Πu - 1 5&3928;g) of dicarbon [P. Bornhauser et al., J. Chem. Phys. 142, 094313 (2015)] are explored by applying non-linear doubleresonant four-wave mixing and laser-induced fluorescence methods. The deperturbation of the d 3Πg, 3 = 8 and 1 5Πg, 3 = 3 states results in accurate molecular constants for the 3 = 3 "dark" quintet state. In addition, the spin-orbit interaction constant is determined and parameters for the upper Swan level d 3Πg, 3 = 8 are improved. The first excited vibrational state of 1 5Πu is observed by performing perturbation-assisted intersystem crossing via "gateway" states in the d 3Πg, 3 = 6 ~ 1 5Πg, 3 = 0 system. The rotationally resolved spectra yield 11 transitions to 1 5Πu, 3 = 1 that include four spinsubstates. Data reduction results in accurate molecular constants of this vibrational level in the shallow potential energy surface of this state. Finally, 3 = 1 and 2 of the lower quintet state (1 5Πg) are measured by performing perturbation-assisted double-resonant excitation to the 1 5Πu, 3 = 0 state and observing dispersed fluorescence. The obtained molecular constants are compared with high level ab initio computations at the multi-reference configuration interaction (MRCI) level of theory by using a large correlation consistent basis set or, alternatively, by applying the computationally less demanding method of explicitly correlated multi-reference configuration interaction (MRCI-F12). The spectroscopic accuracy of both methods is evaluated by comparison with the experimental findings. [ABSTRACT FROM AUTHOR]

Published
2017
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25. Structure of thaumatin determined at SwissFEL using native-SAD at 4.57 keV from 20,000 diffraction patterns

Author

Nass, K., primary, Cheng, R., additional, Vera, L., additional, Mozzanica, A., additional, Redford, S., additional, Ozerov, D., additional, Basu, S., additional, James, D., additional, Knopp, G., additional, Cirelli, C., additional, Martiel, I., additional, Casadei, C., additional, Weinert, T., additional, Nogly, P., additional, Skopintsev, P., additional, Usov, I., additional, Leonarski, F., additional, Geng, T., additional, Rappas, M., additional, Dore, A.S., additional, Cooke, R., additional, Nasrollahi Shirazi, S., additional, Dworkowski, F., additional, Sharpe, M., additional, Olieric, N., additional, Steinmetz, M.O., additional, Schertler, G., additional, Abela, R., additional, Patthey, L., additional, Schmitt, B., additional, Hennig, M., additional, Standfuss, J., additional, Wang, M., additional, and Milne, J.C., additional

Published
2020
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26. Structure of thaumatin determined at SwissFEL using native-SAD at 6.06 keV from 50,000 diffraction patterns.

Author

Nass, K., primary, Cheng, R., additional, Vera, L., additional, Mozzanica, A., additional, Redford, S., additional, Ozerov, D., additional, Basu, S., additional, James, D., additional, Knopp, G., additional, Cirelli, C., additional, Martiel, I., additional, Casadei, C., additional, Weinert, T., additional, Nogly, P., additional, Skopintsev, P., additional, Usov, I., additional, Leonarski, F., additional, Geng, T., additional, Rappas, M., additional, Dore, A.S., additional, Cooke, R., additional, Nasrollahi Shirazi, S., additional, Dworkowski, F., additional, Sharpe, M., additional, Olieric, N., additional, Steinmetz, M.O., additional, Schertler, G., additional, Abela, R., additional, Patthey, L., additional, Schmitt, B., additional, Hennig, M., additional, Standfuss, J., additional, Wang, M., additional, and Milne, J.C., additional

Published
2020
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27. Structure of thaumatin determined at SwissFEL using native-SAD at 6.06 keV from all available diffraction patterns

Author

Nass, K., primary, Cheng, R., additional, Vera, L., additional, Mozzanica, A., additional, Redford, S., additional, Ozerov, D., additional, Basu, S., additional, James, D., additional, Knopp, G., additional, Cirelli, C., additional, Martiel, I., additional, Casadei, C., additional, Weinert, T., additional, Nogly, P., additional, Skopintsev, P., additional, Usov, I., additional, Leonarski, F., additional, Geng, T., additional, Rappas, M., additional, Dore, A.S., additional, Cooke, R., additional, Nasrollahi Shirazi, S., additional, Dworkowski, F., additional, Sharpe, M., additional, Olieric, N., additional, Steinmetz, M.O., additional, Schertler, G., additional, Abela, R., additional, Patthey, L., additional, Schmitt, B., additional, Hennig, M., additional, Standfuss, J., additional, Wang, M., additional, and Milne, J.C., additional

Published
2020
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28. Structure of the A2A adenosine receptor determined at SwissFEL using native-SAD at 4.57 keV from all available diffraction patterns

Author

Nass, K., primary, Cheng, R., additional, Vera, L., additional, Mozzanica, A., additional, Redford, S., additional, Ozerov, D., additional, Basu, S., additional, James, D., additional, Knopp, G., additional, Cirelli, C., additional, Martiel, I., additional, Casadei, C., additional, Weinert, T., additional, Nogly, P., additional, Skopintsev, P., additional, Usov, I., additional, Leonarski, F., additional, Geng, T., additional, Rappas, M., additional, Dore, A.S., additional, Cooke, R., additional, Nasrollahi Shirazi, S., additional, Dworkowski, F., additional, Sharpe, M., additional, Olieric, N., additional, Steinmetz, M.O., additional, Schertler, G., additional, Abela, R., additional, Patthey, L., additional, Schmitt, B., additional, Hennig, M., additional, Standfuss, J., additional, Wang, M., additional, and Milne, J.C., additional

Published
2020
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29. Structure of thaumatin determined at SwissFEL using native-SAD at 4.57 keV from all available diffraction patterns

Author

Nass, K., primary, Cheng, R., additional, Vera, L., additional, Mozzanica, A., additional, Redford, S., additional, Ozerov, D., additional, Basu, S., additional, James, D., additional, Knopp, G., additional, Cirelli, C., additional, Martiel, I., additional, Casadei, C., additional, Weinert, T., additional, Nogly, P., additional, Skopintsev, P., additional, Usov, I., additional, Leonarski, F., additional, Geng, T., additional, Rappas, M., additional, Dore, A.S., additional, Cooke, R., additional, Nasrollahi Shirazi, S., additional, Dworkowski, F., additional, Sharpe, M., additional, Olieric, N., additional, Steinmetz, M.O., additional, Schertler, G., additional, Abela, R., additional, Patthey, L., additional, Schmitt, B., additional, Hennig, M., additional, Standfuss, J., additional, Wang, M., additional, and Milne, J.Ch., additional

Published
2020
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30. Structure of the A2A adenosine receptor determined at SwissFEL using native-SAD at 4.57 keV from 50,000 diffraction patterns

Author

Nass, K., primary, Cheng, R., additional, Vera, L., additional, Mozzanica, A., additional, Redford, S., additional, Ozerov, D., additional, Basu, S., additional, James, D., additional, Knopp, G., additional, Cirelli, C., additional, Martiel, I., additional, Casadei, C., additional, Weinert, T., additional, Nogly, P., additional, Skopintsev, P., additional, Usov, I., additional, Leonarski, F., additional, Geng, T., additional, Rappas, M., additional, Dore, A.S., additional, Cooke, R., additional, Nasrollahi Shirazi, S., additional, Dworkowski, F., additional, Sharpe, M., additional, Olieric, N., additional, Steinmetz, M.O., additional, Schertler, G., additional, Abela, R., additional, Patthey, L., additional, Schmitt, B., additional, Hennig, M., additional, Standfuss, J., additional, Wang, M., additional, and Milne, J.C., additional

Published
2020
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31. Femtosecond to millisecond structural changes in a light-driven sodium pump: 1ns+16ns structure of KR2 with extrapolated, light and dark datasets

Author

Skopintsev, P., primary, Ehrenberg, D., additional, Weinert, T., additional, James, D., additional, Kar, R., additional, Johnson, P., additional, Ozerov, D., additional, Furrer, A., additional, Martiel, I., additional, Dworkowski, F., additional, Nass, K., additional, Knopp, G., additional, Cirelli, C., additional, Gashi, D., additional, Mous, S., additional, Wranik, M., additional, Gruhl, T., additional, Kekilli, D., additional, Bruenle, S., additional, Deupi, X., additional, Schertler, G.F.X., additional, Benoit, R., additional, Panneels, V., additional, Nogly, P., additional, Schapiro, I., additional, Milne, C., additional, Heberle, J., additional, and Standfuss, J., additional

Published
2020
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32. Femtosecond to millisecond structural changes in a light-driven sodium pump: Dark structure in acidic conditions

Author

Skopintsev, P., primary, Ehrenberg, D., additional, Weinert, T., additional, James, D., additional, Kar, R., additional, Johnson, P., additional, Ozerov, D., additional, Furrer, A., additional, Martiel, I., additional, Dworkowski, F., additional, Nass, K., additional, Knopp, G., additional, Cirelli, C., additional, Gashi, D., additional, Mous, S., additional, Wranik, M., additional, Gruhl, T., additional, Kekilli, D., additional, Bruenle, S., additional, Deupi, X., additional, Schertler, G.F.X., additional, Benoit, R., additional, Panneels, V., additional, Nogly, P., additional, Schapiro, I., additional, Milne, C., additional, Heberle, J., additional, and Standfuss, J., additional

Published
2020
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33. Femtosecond to millisecond structural changes in a light-driven sodium pump: 30us+150us structure of KR2 with extrapolated, light and dark datasets

Author

Skopintsev, P., primary, Ehrenberg, D., additional, Weinert, T., additional, James, D., additional, Kar, R., additional, Johnson, P., additional, Ozerov, D., additional, Furrer, A., additional, Martiel, I., additional, Dworkowski, F., additional, Nass, K., additional, Knopp, G., additional, Cirelli, C., additional, Gashi, D., additional, Mous, S., additional, Wranik, M., additional, Gruhl, T., additional, Kekilli, D., additional, Bruenle, S., additional, Deupi, X., additional, Schertler, G.F.X., additional, Benoit, R., additional, Panneels, V., additional, Nogly, P., additional, Schapiro, I., additional, Milne, C., additional, Heberle, J., additional, and Standfuss, J., additional

Published
2020
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34. Femtosecond to millisecond structural changes in a light-driven sodium pump: 800fs+2ps structure of KR2 with extrapolated, light and dark datasets

Author

Skopintsev, P., primary, Ehrenberg, D., additional, Weinert, T., additional, James, D., additional, Kar, R., additional, Johnson, P., additional, Ozerov, D., additional, Furrer, A., additional, Martiel, I., additional, Dworkowski, F., additional, Nass, K., additional, Knopp, G., additional, Cirelli, C., additional, Gashi, D., additional, Mous, S., additional, Wranik, M., additional, Gruhl, T., additional, Kekilli, D., additional, Bruenle, S., additional, Deupi, X., additional, Schertler, G.F.X., additional, Benoit, R., additional, Panneels, V., additional, Nogly, P., additional, Schapiro, I., additional, Milne, C., additional, Heberle, J., additional, and Standfuss, J., additional

Published
2020
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35. Femtosecond to millisecond structural changes in a light-driven sodium pump: 20ms structure of KR2 with extrapolated, light and dark datasets

Author

Skopintsev, P., primary, Ehrenberg, D., additional, Weinert, T., additional, James, D., additional, Kar, R., additional, Johnson, P., additional, Ozerov, D., additional, Furrer, A., additional, Martiel, I., additional, Dworkowski, F., additional, Nass, K., additional, Knopp, G., additional, Cirelli, C., additional, Gashi, D., additional, Mous, S., additional, Wranik, M., additional, Gruhl, T., additional, Kekilli, D., additional, Bruenle, S., additional, Deupi, X., additional, Schertler, G.F.X., additional, Benoit, R., additional, Panneels, V., additional, Nogly, P., additional, Schapiro, I., additional, Milne, C., additional, Heberle, J., additional, and Standfuss, J., additional

Published
2020
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36. Femtosecond to millisecond structural changes in a light-driven sodium pump: Dark structure in neutral conditions with attached light datasets at 800fs, 2ps, 100ps, 1ns, 16ns, 1us, 30us, 150us, 1ms and 20ms

Author

Skopintsev, P., primary, Ehrenberg, D., additional, Weinert, T., additional, James, D., additional, Kar, R., additional, Johnson, P., additional, Ozerov, D., additional, Furrer, A., additional, Martiel, I., additional, Dworkowski, F., additional, Nass, K., additional, Knopp, G., additional, Cirelli, C., additional, Gashi, D., additional, Mous, S., additional, Wranik, M., additional, Gruhl, T., additional, Kekilli, D., additional, Bruenle, S., additional, Deupi, X., additional, Schertler, G.F.X., additional, Benoit, R., additional, Panneels, V., additional, Nogly, P., additional, Schapiro, I., additional, Milne, C., additional, Heberle, J., additional, and Standfuss, J., additional

Published
2020
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40. Femtosecond time-resolved CARS spectroscopy on binary gas-phase mixtures: a theoretical and experimental study of the benzene/toluene system

Author

Rubner, O., Schmitt, M., Knopp, G., Materny, A., Kiefer, W., and Engel, V.

Subjects
Benzene -- Research, Toluene -- Research, Molecular dynamics -- Research, Chemicals, plastics and rubber industries
Abstract

Benzene, toluene and binary mixtures of these molecules in the gas phase are studied using femtosecond time-resolved anti-Stokes Raman scattering (CARS). Results show that the CARS signal indicates no oscillatory patterns and decays for benzene while temporal variations reflecting the vibrational periods of the system are observed for toluene. For benzene and toluene mixtures, a strong oscillation in the transient signal corresponding to a beat between the vibrational mode in the benzene and toluene is found.

Published
1998

41. The application of femtosecond time-resolved coherent anti-Stokes Raman scattering for the investigation of ground and excited state molecular dynamics of molecules in the gas phase

Author

Schmitt, M., Knopp, G., Materny, A., and Kiefer, W.

Subjects
Molecular dynamics -- Research, Molecular rotation -- Research, Molecules -- Analysis, Chemicals, plastics and rubber industries
Abstract

The molecular dynamics evolving on the electronic excited and ground state potential energy surfaces of iodine and bromine in the gas phase were investigated using femtosecond time-resolved coherent anti-Stokes Raman scattering spectroscopy. Fast Fourier transform calculations and a simple model outlining the rotational contribution were employed in the analysis of the coherences of the wave packet in the temporal transients of the molecules excited by the ultrashort laser pulses. It was found that the model can describe the rotational coherence for the excited state vibrations, but not the rotational structure of the ground-state transients.

Published
1998

42. Generation of coherent phonons by coherent extreme ultraviolet radiation in a transient grating experiment

Author

Massachusetts Institute of Technology. Department of Physics, Maznev, A. A., Bencivenga, F., Cannizzo, A., Capotondi, F., Cucini, R., Duncan, R. A., Feurer, T., Frazer, T. D., Foglia, L., Frey, H.-M., Kapteyn, H., Knobloch, J., Knopp, G., Masciovecchio, C., Mincigrucci, R., Monaco, G., Murnane, M., Nikolov, I., Pedersoli, E., Simoncig, A., Vega-Flick, A., Nelson, K. A., Massachusetts Institute of Technology. Department of Physics, Maznev, A. A., Bencivenga, F., Cannizzo, A., Capotondi, F., Cucini, R., Duncan, R. A., Feurer, T., Frazer, T. D., Foglia, L., Frey, H.-M., Kapteyn, H., Knobloch, J., Knopp, G., Masciovecchio, C., Mincigrucci, R., Monaco, G., Murnane, M., Nikolov, I., Pedersoli, E., Simoncig, A., Vega-Flick, A., and Nelson, K. A.

Abstract

We investigate the excitation of coherent acoustic and optical phonons by ultrashort extreme ultraviolet (EUV) pulses produced by a free electron laser. Two crossed femtosecond EUV (wavelength 12.7 nm) pulses are used to excite coherent phonons at a wavelength of 280 nm, which are detected via diffraction of an optical probe beam. Longitudinal and surface acoustic waves are measured in BK-7 glass, diamond, and Bi4Ge3O12; in the latter material, the excitation of a coherent optical phonon mode is also observed. We discuss probing different acoustic modes in reflection and transmission geometries and frequency mixing of surface and bulk acoustic waves in the signal. The use of extreme ultraviolet radiation will allow the creation of tunable GHz to THz acoustic sources in any material without the need to fabricate transducer structures., United States. Department of Energy (Award DE-FG02-00ER15087)

Published
2020

43. Perturbation-facilitated detection of the first quintet-quintet band in C2.

Author

Bornhauser, P., Marquardt, R., Gourlaouen, C., Knopp, G., Beck, M., Gerber, T., van Bokhoven, J. A., and Radi, P. P.

Subjects
QUANTUM perturbations, MOLECULAR beams, FOUR-wave mixing, CARBON, SPECTRUM analysis, SPIN crossover, ENERGY bands
Abstract

The first high-spin transition in C2 (1 5Πu - 1 5Πg) is observed by perturbation-facilitated opticaloptical double resonance spectroscopy. The experiment is performed by applying unfolded two-color resonant four-wave mixing. C2 radicals in the initial a ³Πu, v = 5 state are produced by using a discharge source in a molecular beam environment. The final quintet state is excited via intermediate "gateway" states exhibiting both substantial triplet and quintet character due to a perturbation between the 1 5Πg, v = 0 and the d 5Πg, v = 6 states. Fifty seven rotational transitions in the P, Q, and R branches of all spin sub-states are measured and yield accurate molecular constants of the newly found upper level 1 5Πu. In addition, satellite transitions (ΔJ ≠ ΔN) are observed and allow an accurate determination of the spin-orbit constant. The results are compared with high-level ab initio computations at the multi-reference configuration interaction level of theory. The high-lying quintet state is found to be predissociative and displays a shallow potential that accommodates three vibrational levels only. [ABSTRACT FROM AUTHOR]

Published
2015
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44. Nonlinear XUV-optical transient grating spectroscopy at the Si L 2,3 –edge

Author

Bohinc, R., Pamfilidis, G., Rehault, J., Radi, P., Milne, C., Szlachetko, J., Bencivenga, F., Capotondi, F., Cucini, R., Foglia, L., Masciovecchio, C., Mincigrucci, R., Pedersoli, E., Simoncig, A., Mahne, N., Cannizzo, A., Frey, H. M., Ollmann, Z., Feurer, T., Maznev, A. A., Nelson, K., and Knopp, G.

Subjects
530 Physics, 500 Science, 620 Engineering
Published
2019
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45. Nonlinear XUV-optical transient grating spectroscopy at the Si L2,3–edge

Author

Bohinc, R., primary, Pamfilidis, G., additional, Rehault, J., additional, Radi, P., additional, Milne, C., additional, Szlachetko, J., additional, Bencivenga, F., additional, Capotondi, F., additional, Cucini, R., additional, Foglia, L., additional, Masciovecchio, C., additional, Mincigrucci, R., additional, Pedersoli, E., additional, Simoncig, A., additional, Mahne, N., additional, Cannizzo, A., additional, Frey, H. M., additional, Ollmann, Z., additional, Feurer, T., additional, Maznev, A. A., additional, Nelson, K., additional, and Knopp, G., additional

Published
2019
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47. Inception of electronic damage of matter by photon-driven post-ionization mechanisms

Author

Blachucki, W., Kayser, Y., Czapla-Masztafiak, J., Guo, Meiyuan, Juranic, P., Kavcic, M., Källman, Erik, Knopp, G., Lundberg, Marcus, Milne, C., Rehanek, J., Sá, Jacinto, Szlachetko, J., Blachucki, W., Kayser, Y., Czapla-Masztafiak, J., Guo, Meiyuan, Juranic, P., Kavcic, M., Källman, Erik, Knopp, G., Lundberg, Marcus, Milne, C., Rehanek, J., Sá, Jacinto, and Szlachetko, J.

Abstract

"Probe-before-destroy" methodology permitted diffraction and imaging measurements of intact specimens using ultrabright but highly destructive X-ray free-electron laser (XFEL) pulses. The methodology takes advantage of XFEL pulses ultrashort duration to outrun the destructive nature of the X-rays. Atomic movement, generally on the order of >50 fs, regulates the maximum pulse duration for intact specimen measurements. In this contribution, we report the electronic structure damage of a molecule with ultrashort X-ray pulses under preservation of the atoms' positions. A detailed investigation of the X-ray induced processes revealed that X-ray absorption events in the solvent produce a significant number of solvated electrons within attosecond and femtosecond timescales that are capable of coulombic interactions with the probed molecules. The presented findings show a strong influence on the experimental spectra coming from ionization of the probed atoms' surroundings leading to electronic structure modification much faster than direct absorption of photons. This work calls for consideration of this phenomenon in cases focused on samples embedded in, e.g., solutions or in matrices, which in fact concerns most of the experimental studies.

Published
2019
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48. Perturbation facilitated two-color four-wave-mixing spectroscopy of C3.

Author

Sych, Y., Bornhauser, P., Knopp, G., Liu, Y., Gerber, T., Marquardt, R., and Radi, P. P.

Subjects
PERTURBATION theory, APPROXIMATION theory, SPECTRUM analysis, WAVES (Physics), MOLECULES
Abstract

Perturbation-facilitated two-color resonant four-wave-mixing spectroscopy is realized to access the (dark) triplet manifold of the C3 molecule from the singlet X1Σg+ ground state. The inherent nonlinear signal dependence and coherence of the technique result in a favorable detection of the excited triplet states of interest. The observation of a newly found 3Δu electronic state is achieved by a two-step excitation via 'gate-way' levels (i.e., singlet-triplet mixed levels). Additionally, by fixing the probe laser on a transition exhibiting mainly triplet-triplet character and scanning the pump laser, we demonstrate an effective spin-filtering in a four-wave mixing measurement where only transitions to the perturber 3Σu- state appear exclusively in an otherwise congested spectral range of the Comet band. Ab initio calculations of excited triplet states complement our analysis with the electronic assignment of the observed resonances. [ABSTRACT FROM AUTHOR]

Published
2013
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49. Towards X-ray transient grating spectroscopy

Author

Svetina, C., primary, Mankowsky, R., additional, Knopp, G., additional, Koch, F., additional, Seniutinas, G., additional, Rösner, B., additional, Kubec, A., additional, Lebugle, M., additional, Mochi, I., additional, Beck, M., additional, Cirelli, C., additional, Krempasky, J., additional, Pradervand, C., additional, Rouxel, J., additional, Mancini, G. F., additional, Zerdane, S., additional, Pedrini, B., additional, Esposito, V., additional, Ingold, G., additional, Wagner, U., additional, Flechsig, U., additional, Follath, R., additional, Chergui, M., additional, Milne, C., additional, Lemke, H. T., additional, David, C., additional, and Beaud, P., additional

Published
2019
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50. Generation of coherent phonons by coherent extreme ultraviolet radiation in a transient grating experiment

Author

Maznev, A. A., primary, Bencivenga, F., additional, Cannizzo, A., additional, Capotondi, F., additional, Cucini, R., additional, Duncan, R. A., additional, Feurer, T., additional, Frazer, T. D., additional, Foglia, L., additional, Frey, H.-M., additional, Kapteyn, H., additional, Knobloch, J., additional, Knopp, G., additional, Masciovecchio, C., additional, Mincigrucci, R., additional, Monaco, G., additional, Murnane, M., additional, Nikolov, I., additional, Pedersoli, E., additional, Simoncig, A., additional, Vega-Flick, A., additional, and Nelson, K. A., additional

Published
2018
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