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16 results on '"Champenois E"'

2. Conformer-specific Chemistry Imaged in Real Space and Time

Author

Champenois, E. G., Sanchez, D. M., Yang, J., Nunes, J. P. F., Attar, A., Centurion, M., Forbes, R., Gühr, M., Hegazy, K., Ji, F., Saha, S. K., Liu, Y., Lin, M. -F., Luo, D., Moore, B., Shen, X., Ware, M. R., Wang, X. J., Martínez, T. J., and Wolf, T. J. A.

Subjects
Physics - Chemical Physics
Abstract

Conformational isomers or conformers of molecules play a decisive role in chemistry and biology. However, experimental methods to investigate chemical reaction dynamics are typically not conformer-sensitive. Here, we report on a gas-phase megaelectronvolt ultrafast electron diffraction investigation of {\alpha}-phellandrene undergoing an electrocyclic ring-opening reaction. We directly image the evolution of a specific set of {\alpha}-phellandrene conformers into the product isomer predicted by the Woodward-Hoffmann rules in real space and time. Our experimental results are in quantitative agreement with nonadiabatic quantum molecular dynamics simulations, which provide unprecedented detail of how conformation influences time scale and quantum efficiency of photoinduced ring-opening reactions. Due to the prevalence of large numbers of conformers in organic chemistry, our findings impact our general understanding of reaction dynamics in chemistry and biology.

Published
2021
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3. Resonance signatures in the body-frame valence photoionization of CF 4

Author

Larsen, KA, Trevisan, CS, Lucchese, RR, Heck, S, Iskandar, W, Champenois, E, Gatton, A, Moshammer, R, Strom, R, Severt, T, Jochim, B, Reedy, D, Weller, M, Landers, AL, Williams, JB, Ben-Itzhak, I, Dörner, R, Slaughter, D, McCurdy, CW, Weber, Th, and Rescigno, TN

Subjects
Physical Sciences, Chemical Sciences, Atomic, Molecular and Optical Physics, Physical Chemistry, Chemical Physics
Abstract

We present a combined experimental and theoretical investigation of the electron dynamics and body-frame angular dependence of valence photo-single ionization of CF4 and subsequent dissociation into CF3+ and F. Ionization from a valence t2 orbital shows overlapping shape resonances close to threshold that couple to the same total symmetry, leading to striking changes in the photoelectron angular distributions when viewed in the body-frame.

Published
2018

4. Conformer-specific photochemistry imaged in real space and time

Author

Champenois, E. G., primary, Sanchez, D. M., additional, Yang, J., additional, Figueira Nunes, J. P., additional, Attar, A., additional, Centurion, M., additional, Forbes, R., additional, Gühr, M., additional, Hegazy, K., additional, Ji, F., additional, Liu, Y., additional, Lin, M.-F., additional, Luo, D., additional, Moore, B., additional, Saha, S. K., additional, Shen, X., additional, Ware, M. R., additional, Wang, X. J., additional, Martínez, T. J., additional, and Wolf, T. J. A., additional

Published
2022
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5. Conformer-specific photochemistry imaged in real space and time

Author

Champenois, E. G., primary, Sanchez, D. M., additional, Yang, J., additional, Figueira Nunes, J. P., additional, Attar, A., additional, Centurion, M., additional, Forbes, R., additional, Gühr, M., additional, Hegazy, K., additional, Ji, F., additional, Saha, S. K., additional, Liu, Y., additional, Lin, M.-F., additional, Luo, D., additional, Moore, B., additional, Shen, X., additional, Ware, M. R., additional, Wang, X. J., additional, Martínez, T. J., additional, and Wolf, T. J. A., additional

Published
2021
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6. Two-dimensional correlation analysis for x-ray photoelectron spectroscopy

Author

Li, S, primary, Driver, T, additional, Al Haddad, A, additional, Champenois, E G, additional, Agåker, M, additional, Alexander, O, additional, Barillot, T, additional, Bostedt, C, additional, Garratt, D, additional, Kjellsson, L, additional, Lutman, A A, additional, Rubensson, J-E, additional, Sathe, C, additional, Marinelli, A, additional, Marangos, J P, additional, and Cryan, J P, additional

Published
2021
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7. Two-dimensional correlation analysis for x-ray photoelectron spectroscopy

Author

Li, S., Driver, T., Al Haddad, A., Champenois, E. G., Agåker, Marcus, Alexander, O., Barillot, T., Bostedt, C., Garratt, D., Kjellsson, Ludvig, Lutman, A. A., Rubensson, Jan-Erik, Sathe, C., Marinelli, A., Marangos, J. P., Cryan, J. P., Li, S., Driver, T., Al Haddad, A., Champenois, E. G., Agåker, Marcus, Alexander, O., Barillot, T., Bostedt, C., Garratt, D., Kjellsson, Ludvig, Lutman, A. A., Rubensson, Jan-Erik, Sathe, C., Marinelli, A., Marangos, J. P., and Cryan, J. P.

Abstract

X-ray photoelectron spectroscopy (XPS) measures the binding energy of core-level electrons, which are well-localised to specific atomic sites in a molecular system, providing valuable information on the local chemical environment. The technique relies on measuring the photoelectron spectrum upon x-ray photoionisation, and the resolution is often limited by the bandwidth of the ionising x-ray pulse. This is particularly problematic for time-resolved XPS, where the desired time resolution enforces a fundamental lower limit on the bandwidth of the x-ray source. In this work, we report a novel correlation analysis which exploits the correlation between the x-ray and photoelectron spectra to improve the resolution of XPS measurements. We show that with this correlation-based spectral-domain ghost imaging method we can achieve sub-bandwidth resolution in XPS measurements. This analysis method enables XPS for sources with large bandwidth or spectral jitter, previously considered unfeasible for XPS measurements.

Published
2021
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8. Tracing inter-Coulombic decay of molecular dimers

Author

Iskandar, W, primary, Gatton, A S, additional, Gaire, B, additional, Sturm, F P, additional, Larsen, K A, additional, Champenois, E G, additional, Shivaram, N, additional, Moradmand, A, additional, Williams, J B, additional, Berry, B, additional, Severt, T, additional, Ben-Itzhak, I, additional, Metz, D, additional, Sann, H, additional, Weller, M, additional, Jahnke, T, additional, Dörner, R, additional, Slaughter, D, additional, and Weber, Th, additional

Published
2020
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9. Symmetry breaking in the body-fixed electron emission pattern due to electron-retroaction in the photodissociation of H2+ and D2+ close to threshold

Author

Heck, S., primary, Gatton, A., additional, Larsen, K. A., additional, Iskandar, W., additional, Champenois, E. G., additional, Strom, R., additional, Landers, A., additional, Reedy, D., additional, Dailey, C., additional, Williams, J. B., additional, Severt, T., additional, Jochim, B., additional, Ben-Itzhak, I., additional, Moshammer, R., additional, Dörner, R., additional, Slaughter, D. S., additional, and Weber, Th., additional

Published
2019
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10. Resonance signatures in the body-frame valence photoionization of CF4

Author

Larsen, KA, Trevisan, CS, Lucchese, RR, Heck, S, Iskandar, W, Champenois, E, Gatton, A, Moshammer, R, Strom, R, Severt, T, Jochim, B, Reedy, D, Weller, M, Landers, AL, Williams, JB, Ben-Itzhak, I, Dörner, R, Slaughter, D, McCurdy, CW, Weber, Th, and Rescigno, TN

Subjects
Engineering, Chemical Physics, Physical Sciences, Chemical Sciences, Physics::Atomic and Molecular Clusters
Abstract

We present a combined experimental and theoretical investigation of the electron dynamics and body-frame angular dependence of valence photo-single ionization of CF4 and subsequent dissociation into CF3+ and F. Ionization from a valence t2 orbital shows overlapping shape resonances close to threshold that couple to the same total symmetry, leading to striking changes in the photoelectron angular distributions when viewed in the body-frame.

Published
2018

11. Tracing intermolecular Coulombic decay of carbon-dioxide dimers and oxygen dimers after valence photoionization

Author

Iskandar, W., primary, Gatton, A. S., additional, Gaire, B., additional, Sturm, F. P., additional, Larsen, K. A., additional, Champenois, E. G., additional, Shivaram, N., additional, Moradmand, A., additional, Williams, J. B., additional, Berry, B., additional, Severt, T., additional, Ben-Itzhak, I., additional, Metz, D., additional, Sann, H., additional, Weller, M., additional, Schoeffler, M., additional, Jahnke, T., additional, Dörner, R., additional, Slaughter, D., additional, and Weber, Th., additional

Published
2019
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12. A co-axial velocity map imaging spectrometer for electrons

Author

Li, S., primary, Champenois, E. G., additional, Coffee, R., additional, Guo, Z., additional, Hegazy, K., additional, Kamalov, A., additional, Natan, A., additional, O’Neal, J., additional, Osipov, T., additional, Owens, M., additional, Ray, D., additional, Rich, D., additional, Walter, P., additional, Marinelli, A., additional, and Cryan, J. P., additional

Published
2018
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15. Resonance signatures in the body-frame valence photoionization of CF4.

Author

Larsen, K. A., Trevisan, C. S., Lucchese, R. R., Heck, S., Iskandar, W., Champenois, E., Gatton, A., Moshammer, R., Strom, R., Severt, T., Jochim, B., Reedy, D., Weller, M., Landers, A. L., Williams, J. B., Ben-Itzhak, I., Dörner, R., Slaughter, D., McCurdy, C. W., and Weber, Th.

Abstract

We present a combined experimental and theoretical investigation of the electron dynamics and body-frame angular dependence of valence photo-single ionization of CF4 and subsequent dissociation into CF3+ and F. Ionization from a valence t2 orbital shows overlapping shape resonances close to threshold that couple to the same total symmetry, leading to striking changes in the photoelectron angular distributions when viewed in the body-frame. [ABSTRACT FROM AUTHOR]

Published
2018
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16. Multichannel photodissociation dynamics in CS 2 studied by ultrafast electron diffraction.

Author

Razmus WO, Acheson K, Bucksbaum P, Centurion M, Champenois E, Gabalski I, Hoffman MC, Howard A, Lin MF, Liu Y, Nunes P, Saha S, Shen X, Ware M, Warne EM, Weinacht T, Wilkin K, Yang J, Wolf TJA, Kirrander A, Minns RS, and Forbes R

Abstract

The structural dynamics of photoexcited gas-phase carbon disulfide (CS 2 ) molecules are investigated using ultrafast electron diffraction. The dynamics were triggered by excitation of the optically bright 1 B 2 ( 1 Σ u + ) state by an ultraviolet femtosecond laser pulse centred at 200 nm. In accordance with previous studies, rapid vibrational motion facilitates a combination of internal conversion and intersystem crossing to lower-lying electronic states. Photodissociation via these electronic manifolds results in the production of CS fragments in the electronic ground state and dissociated singlet and triplet sulphur atoms. The structural dynamics are extracted from the experiment using a trajectory-fitting filtering approach, revealing the main characteristics of the singlet and triplet dissociation pathways. Finally, the effect of the time-resolution on the experimental signal is considered and an outlook to future experiments provided.

Published
2022
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