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283 results on '"Brouard, Mark"'

1. The Kinetic Energy of PAH Dication and Trication Dissociation Determined by Recoil-Frame Covariance Map Imaging

Author

Lee, Jason W. L., Tikhonov, Denis S., Allum, Felix, Boll, Rebecca, Chopra, Pragya, Erk, Benjamin, Gruet, Sebastian, He, Lanhai, Heathcote, David, Kazemi, Mehdi M., Lahl, Jan, Lemmens, Alexander K., Loru, Donatella, Maclot, Sylvain, Mason, Robert, Müller, Erland, Mullins, Terry, Passow, Christopher, Peschel, Jasper, Ramm, Daniel, Steber, Amanda L., Bari, Sadia, Brouard, Mark, Burt, Michael, Küpper, Jochen, Eng-Johnsson, Per, Rijs, Anouk M., Rolles, Daniel, Vallance, Claire, Manschwetus, Bastian, and Schnell, Melanie

Subjects
Physics - Chemical Physics
Abstract

We investigated the dissociation of dications and trications of three polycyclic aromatic hydrocarbons (PAHs), fluorene, phenanthrene, and pyrene. PAHs are a family of molecules ubiquitous in space and involved in much of the chemistry of the interstellar medium. In our experiments, ions are formed by interaction with 30.3 nm extreme ultraviolet (XUV) photons, and their velocity map images are recorded using a PImMS2 multi-mass imaging sensor. Application of recoil-frame covariance analysis allows the total kinetic energy release (TKER) associated with multiple fragmentation channels to be determined to high precision, ranging 1.94-2.60 eV and 2.95-5.29 eV for the dications and trications, respectively. Experimental measurements are supported by Born-Oppenheimer molecular dynamics (BOMD) simulations.

Published
2022
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2. X-ray induced Coulomb explosion imaging of transient excited-state structural rearrangements in CS2

Author

Unwin, James, Allum, Felix, Britton, Mathew, Gabalski, Ian, Bromberger, Hubertus, Brouard, Mark, Bucksbaum, Philip H., Driver, Taran, Ekanayake, Nagitha, Garg, Diksha, Gougoula, Eva, Heathcote, David, Howard, Andrew J., Hockett, Paul, Holland, David M. P., Kumar, Sonu, Lam, Chow-shing, Lee, Jason W. L., McManus, Joseph, Mikosch, Jochen, Milesevic, Dennis, Minns, Russell S., Papadopoulou, Christina C., Passow, Christopher, Razmus, Weronika O., Röder, Anja, Rouzée, Arnaud, Schuurman, Michael, Simao, Alcides, Stolow, Albert, Tul-Noor, Atia, Vallance, Claire, Walmsley, Tiffany, Rolles, Daniel, Erk, Benjamin, Burt, Michael, and Forbes, Ruaridh

Published
2023
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3. Stereodynamical control of a quantum scattering resonance in cold molecular collisions

Author

Jambrina, Pablo G., Croft, James F. E., Guo, Hua, Brouard, Mark, Balakrishnan, Naduvalath, and Aoiz, F. Javier

Subjects
Quantum Physics, Physics - Atomic Physics
Abstract

Cold collisions of light molecules are often dominated by a single partial wave resonance. For the rotational quenching of HD(v=1,j=2) by collisions with ground state para-H2, the process is dominated by a single L=2 partial wave resonance centered around 0.1 K. Here, we show that this resonance can be switched on or off simply by appropriate alignment of the HD rotational angular momentum relative to the initial velocity vector, thereby enabling complete control of the collision outcome.

Published
2019
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4. Gas-phase structural isomer identification by Coulomb explosion of aligned molecules

Author

Burt, Michael, Amini, Kasra, Lee, Jason W. L., Christiansen, Lars, Johansen, Rasmus R., Kobayashi, Yuki, Pickering, James D., Vallance, Claire, Brouard, Mark, and Stapelfeldt, Henrik

Subjects
Physics - Chemical Physics
Abstract

The gas-phase structures of four difluoroiodobenzene and two dihydroxybromobenzene isomers were identified by correlating the emission angles of atomic fragment ions created following femtosecond laser-induced Coulomb explosion. The structural determinations were facilitated by confining the most polarizable axis of each molecule to the detection plane prior to the Coulomb explosion event using one-dimensional laser-induced adiabatic alignment. For a molecular target consisting of two difluoroiodobenzene isomers, each constituent structure could additionally be singled out and distinguished., Comment: 13 pages, 4 figures. Published as a communication in the Journal of Chemical Physics

Published
2019
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5. 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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6. 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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7. Probing the UV-Induced Photodissociation of CH$_\text{3}$I and C$_\text{6}$H$_\text{3}$F$_\text{2}$I with Femtosecond Time-Resolved Coulomb Explosion Imaging at FLASH

Author

Amini, Kasra, Savelyev, Evgeny, Brauße, Felix, Berrah, Nora, Bomme, Cédric, Brouard, Mark, Burt, Michael, Christensen, Lauge, Düsterer, Stefan, Erk, Benjamin, Höppner, Hauke, Kierspel, Thomas, Krecinic, Faruk, Lauer, Alexandra, Lee, Jason W. L., Müller, Maria, Müller, Erland, Mullins, Terence, Redlin, Harald, Schirmel, Nora, Thøgersen, Jan, Techert, Simone, Toleikis, Sven, Treusch, Rolf, Trippel, Sebastian, Ulmer, Anatoli, Vallance, Claire, Wiese, Joss, Johnsson, Per, Küpper, Jochen, Rudenko, Artem, Rouzée, Arnaud, Stapelfeldt, Henrik, Rolles, Daniel, and Boll, Rebecca

Subjects
Physics - Atomic Physics, Physics - Atomic and Molecular Clusters, Physics - Chemical Physics
Abstract

We explore time-resolved Coulomb explosion induced by intense, extreme ultraviolet (XUV) femtosecond pulses from the FLASH free-electron laser as a method to image photo-induced molecular dynamics in two molecules, iodomethane and 2,6-difluoroiodobenzene. At an excitation wavelength of 267\,nm, the dominant reaction pathway in both molecules is neutral dissociation via cleavage of the carbon--iodine bond. This allows investigating the influence of the molecular environment on the absorption of an intense, femtosecond XUV pulse and the subsequent Coulomb explosion process. We find that the XUV probe pulse induces local inner-shell ionization of atomic iodine in dissociating iodomethane, in contrast to non-selective ionization of all photofragments in difluoroiodobenzene. The results reveal evidence of electron transfer from methyl and phenyl moieties to a multiply charged iodine ion. In addition, indications for ultrafast charge rearrangement on the phenyl radical are found, suggesting that time-resolved Coulomb explosion imaging is sensitive to the localization of charge in extended molecules.

Published
2017
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8. Alignment, Orientation, and Coulomb Explosion of Difluoroiodobenzene Studied with the Pixel Imaging Mass Spectrometry (PImMS) Camera

Author

Amini, Kasra, Boll, Rebecca, Lauer, Alexandra, Burt, Michael, Lee, Jason W L, Christensen, Lauge, Brauße, Felix, Mullins, Terence, Savelyev, Evgeny, Ablikim, Utuq, Berrah, Nora, Bomme, Cédric, Düsterer, Stefan, Erk, Benjamin, Höppner, Hauke, Johnsson, Per, Kierspel, Thomas, Krecinic, Faruk, Küpper, Jochen, Müller, Maria, Müller, Erland, Redlin, Harald, Rouzée, Arnaud, Schirmel, Nora, Thøgersen, Jan, Techert, Simone, Toleikis, Sven, Treusch, Rolf, Trippel, Sebastian, Ulmer, Anatoli, Wiese, Joss, Vallance, Claire, Rudenko, Artem, Stapelfeldt, Henrik, Brouard, Mark, and Rolles, Daniel

Subjects
Physics - Chemical Physics, Quantum Physics
Abstract

Laser-induced adiabatic alignment and mixed-field orientation of 2,6-difluoroiodobenzene (C6H3F2I) molecules are probed by Coulomb explosion imaging following either near-infrared strong-field ionization or extreme-ultraviolet multi-photon inner-shell ionization using free-electron laser pulses. The resulting photoelectrons and fragment ions are captured by a double-sided velocity map imaging spectrometer and projected onto two position-sensitive detectors. The ion side of the spectrometer is equipped with the Pixel Imaging Mass Spectrometry (PImMS) camera, a time-stamping pixelated detector that can record the hit positions and arrival times of up to four ions per pixel per acquisition cycle. Thus, the time-of-flight trace and ion momentum distributions for all fragments can be recorded simultaneously. We show that we can obtain a high degree of one- and three-dimensional alignment and mixed- field orientation, and compare the Coulomb explosion process induced at both wavelengths.

Published
2017
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9. Time-resolved multi-mass ion imaging: femtosecond UV-VUV pump-probe spectroscopy with the PImMS camera

Author

Forbes, Ruaridh, Makhija, Varun, Veyrinas, Kévin, Stolow, Albert, Lee, Jason W. L., Burt, Michael, Brouard, Mark, Vallance, Claire, Wilkinson, Iain, Lausten, Rune, and Hockett, Paul

Subjects
Physics - Chemical Physics
Abstract

The Pixel-Imaging Mass Spectrometry (PImMS) camera allows for 3D charged particle imaging measurements, in which the particle time-of-flight is recorded along with $(x,y)$ position. Coupling the PImMS camera to an ultrafast pump-probe velocity-map imaging spectroscopy apparatus therefore provides a route to time-resolved multi-mass ion imaging, with both high count rates and large dynamic range, thus allowing for rapid measurements of complex photofragmentation dynamics. Furthermore, the use of vacuum ultraviolet wavelengths for the probe pulse allows for an enhanced observation window for the study of excited state molecular dynamics in small polyatomic molecules having relatively high ionization potentials. Herein, preliminary time-resolved multi-mass imaging results from C$_2$F$_3$I photolysis are presented. The experiments utilized femtosecond UV and VUV (160.8~nm and 267~nm) pump and probe laser pulses in order to demonstrate and explore this new time-resolved experimental ion imaging configuration. The data indicates the depth and power of this measurement modality, with a range of photofragments readily observed, and many indications of complex underlying wavepacket dynamics on the excited state(s) prepared.

Published
2017
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10. Distinguishing the XUV-induced Coulomb explosion dynamics of iodobenzene using covariance analysis.

Author

Walmsley, Tiffany, Allum, Felix, Harries, James R, Kumagai, Yoshiaki, Lim, Suzanne, McManus, Joseph, Nagaya, Kiyonobu, Britton, Mathew, Brouard, Mark, Bucksbaum, Philip, Fushitani, Mizuho, Gabalski, Ian, Gejo, Tatsuo, Hockett, Paul, Howard, Andrew J, Iwayama, Hiroshi, Kukk, Edwin, Lam, Chow-shing, Minns, Russell S, and Niozu, Akinobu

Subjects
FREE electron lasers, ANALYSIS of covariance, MOLECULAR spectroscopy, ELECTRON spectroscopy, LASER spectroscopy
Abstract

The primary and secondary fragmentation dynamics of iodobenzene following its ionization at 120 eV were determined using three-dimensional velocity map imaging and covariance analysis. Site-selective iodine 4d ionization was used to populate a range of excited polycationic parent states, which primarily broke apart at the carbon-iodine bond to produce I+ with phenyl or phenyl-like cations (C n H x + or C n H x 2 + , with n = 1 – 6 and x = 1 – 5). The molecular products were produced with varying degrees of internal excitation and dehydrogenation, leading to stable and unstable outcomes. This further allowed the secondary dynamics of C 6 H x 2 + intermediates to be distinguished using native-frame covariance analysis, which isolated these processes in their own centre-of-mass reference frames. The mass resolution of the imaging mass spectrometer used for these measurements enabled the primary and secondary reaction channels to be specified at the level of individual hydrogen atoms, demonstrating the ability of covariance analysis to comprehensively measure the competing fragmentation channels of aryl cations, including those involving intermediate steps. [ABSTRACT FROM AUTHOR]

Published
2024
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11. A localized view on molecular dissociation via electron-ion partial covariance

Author

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

Published
2022
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12. The Role of Momentum Partitioning in Covariance Ion Imaging Analysis

Author

Walmsley, Tiffany, primary, McManus, Joseph W., additional, Kumagai, Yoshiaki, additional, Nagaya, Kiyonobu, additional, Harries, James, additional, Iwayama, Hiroshi, additional, Ashfold, Michael N. R., additional, Britton, Mathew, additional, Bucksbaum, Philip H., additional, Downes-Ward, Briony, additional, Driver, Taran, additional, Heathcote, David, additional, Hockett, Paul, additional, Howard, Andrew J., additional, Lee, Jason W. L., additional, Liu, Yusong, additional, Kukk, Edwin, additional, Milesevic, Dennis, additional, Minns, Russell S., additional, Niozu, Akinobu, additional, Niskanen, Johannes, additional, Orr-Ewing, Andrew J., additional, Owada, Shigeki, additional, Robertson, Patrick A., additional, Rolles, Daniel, additional, Rudenko, Artem, additional, Ueda, Kiyoshi, additional, Unwin, James, additional, Vallance, Claire, additional, Brouard, Mark, additional, Burt, Michael, additional, Allum, Felix, additional, and Forbes, Ruaridh, additional

Published
2024
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14. Exploring the ultrafast and isomer-dependent photodissociation of iodothiophenes via site-selective ionization.

Author

Razmus, Weronika O., Allum, Felix, Harries, James, Kumagai, Yoshiaki, Nagaya, Kiyonobu, Bhattacharyya, Surjendu, Britton, Mathew, Brouard, Mark, Bucksbaum, Philip H., Cheung, Kieran, Crane, Stuart W., Fushitani, Mizuho, Gabalski, Ian, Gejo, Tatsuo, Ghrist, Aaron, Heathcote, David, Hikosaka, Yasumasa, Hishikawa, Akiyoshi, Hockett, Paul, and Jones, Ellen

Abstract

C–I bond extension and fission following ultraviolet (UV, 262 nm) photoexcitation of 2- and 3-iodothiophene is studied using ultrafast time-resolved extreme ultraviolet (XUV) ionization in conjunction with velocity map ion imaging. The photoexcited molecules and eventual I atom products are probed by site-selective ionization at the I 4d edge using intense XUV pulses, which induce multiple charges initially localized to the iodine atom. At C–I separations below the critical distance for charge transfer (CT), charge can redistribute around the molecule leading to Coulomb explosion and charged fragments with high kinetic energy. At greater C–I separations, beyond the critical distance, CT is no longer possible and the measured kinetic energies of the charged iodine atoms report on the neutral dissociation process. The time and momentum resolved measurements allow determination of the timescales and the respective product momentum and kinetic energy distributions for both isomers, which are interpreted in terms of rival 'direct' and 'indirect' dissociation pathways. The measurements are compared with a classical over the barrier model, which reveals that the onset of the indirect dissociation process is delayed by ∼1 ps relative to the direct process. The kinetics of the two processes show no discernible difference between the two parent isomers, but the branching between the direct and indirect dissociation channels and the respective product momentum distributions show isomer dependencies. The greater relative yield of indirect dissociation products from 262 nm photolysis of 3-iodothiophene (cf. 2-iodothiophene) is attributed to the different partial cross-sections for (ring-centred) π∗ ← π and (C–I bond localized) σ∗ ← (n/π) excitation in the respective parent isomers. [ABSTRACT FROM AUTHOR]

Published
2024
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15. Scattering in extreme environments: general discussion.

Author

Alexandrowicz, Gil, Babikov, Dmitri, Brouard, Mark, Butler, Alexander, Chadwick, Helen, Chandler, David W., Fárník, Michal, Fingerhut, Jan, Hua Guo, Győri, Tibor, Haakansson, Christian T., Harding, Dan J., Heard, Dwayne, Heazlewood, Brianna R., Heathcote, David, Hertl, Nils, Jambrina, Pablo G., Kroes, Geert-Jan, Krohn, Olivia A., and Lane, Paul D.

Abstract

The article focuses on a discussion about scattering in extreme environments, specifically addressing the impact of molecular orientation on nuclear spin coupling measurements. Topics include the effect of relative orientation on measurement outcomes, the role of angular momentum in molecular collisions, and the absence of significant orientation effects in the studied system.

Published
2024
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16. Scattering of larger molecules – part 1: general discussion.

Author

Babikov, Dmitri, Balucani, Nadia, Bergeat, Astrid, Brouard, Mark, Chandler, David W., Costen, Matthew L., Fárník, Michal, Hua Guo, Győri, Tibor, Heard, Dwayne, Heathcote, David, Hertl, Nils, Jambrina, Pablo G., Kidwell, Nathanael M., Krohn, O. A., Duc, Viet Le, Loreau, Jérôme, Mackenzie, Stuart R., McCrea, Max, and McKendrick, Kenneth G.

Abstract

The article focuses on a general discussion about the scattering of larger molecules, particularly examining the differences in potential energy surfaces (PES) between HDO, H2O, and D2O. Topics include the reason for stronger back scattering in HDO compared to H2O and D2O, the role of symmetry and potential terms in scattering phenomena, and specific insights into the n10 term affecting back-scattering.

Published
2024
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17. Concluding remarks: Reflections on the Faraday Discussion on New Directions in Molecular Scattering.

Author

Brouard, Mark

Abstract

These concluding remarks summarize the Faraday Discussion on New Directions in Molecular Scattering. The discussion brought together scientists from a wide range of disciplines, from astrochemistry to coherent quantum control, and the submitted papers highlighted the need for innovation in experimental methods and computational tools to tackle more complex systems, relevant to chemistry in the real world. As recorded in the previous pages of this discussion, the meeting saw lively debate on numerous topical issues. This summary outlines some of the highlighted key developments in the field, and points towards future directions of molecular scattering research. [ABSTRACT FROM AUTHOR]

Published
2024
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18. Direct momentum imaging of charge transfer following site-selective ionization

Author

Allum, Felix, primary, Kumagai, Yoshiaki, additional, Nagaya, Kiyonobu, additional, Harries, James, additional, Iwayama, Hiroshi, additional, Britton, Mathew, additional, Bucksbaum, Philip H., additional, Burt, Michael, additional, Brouard, Mark, additional, Downes-Ward, Briony, additional, Driver, Taran, additional, Heathcote, David, additional, Hockett, Paul, additional, Howard, Andrew J., additional, Lee, Jason W. L., additional, Liu, Yusong, additional, Kukk, Edwin, additional, McManus, Joseph W., additional, Milsesevic, Dennis, additional, Niozu, Akinobu, additional, Niskanen, Johannes, additional, Orr-Ewing, Andrew J., additional, Owada, Shigeki, additional, Robertson, Patrick A., additional, Rudenko, Artem, additional, Ueda, Kiyoshi, additional, Unwin, James, additional, Vallance, Claire, additional, Walmsley, Tiffany, additional, Minns, Russell S., additional, Rolles, Daniel, additional, Ashfold, Michael N. R., additional, and Forbes, Ruaridh, additional

Published
2023
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19. Ultrafast dynamics of polycyclic aromatic hydrocarbons initiated by highly intense laser fields

Author

Garg, Diksha, primary, Chopra, Pragya, additional, Lee, Jason W. L., additional, Tikhonov, Denis, additional, Kumar, Sonu, additional, Akcaalan, Oender, additional, Allum, Felix, additional, Boll, Rebecca, additional, Butler, Alexander A., additional, Erk, Benjamin, additional, Gougoula, Eva, additional, Gruet, Sébastien P., additional, He, Lanhai, additional, Heathcote, David, additional, Jones, Ellen, additional, Kazemi, Mehdi M., additional, Lahl, Jan, additional, Lemmens, Alexander K., additional, Liu, Zhihao, additional, Loru, Donatella, additional, Maclot, Sylvain, additional, Mason, Robert, additional, Merrick, James, additional, Müller, Erland, additional, Mullins, Terry, additional, Papadopoulou, Christina C., additional, Passow, Christopher, additional, Peschel, Jasper, additional, Plach, Marius, additional, Ramm, Daniel, additional, Robertson, Patrick, additional, Rompotis, Dimitrios, additional, Simao, Alcides, additional, Steber, Amanda L., additional, Tajalli, Ayhan, additional, Trippel, Sebastian H., additional, Tul-Noor, Atia, additional, Vadassery, Nidin, additional, Vinklarek, Ivo S., additional, Techert, Simone, additional, Küpper, Jochen, additional, Rijs, Anouk M., additional, Rolles, Daniel, additional, Brouard, Mark, additional, Bari, Sadia, additional, Eng-Johnsson, Per, additional, Vallance, Claire, additional, Burt, Michael, additional, Manschwetus, Bastian, additional, and Schnell, Melanie, additional

Published
2023
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24. X-ray induced Coulomb explosion imaging of transient excited-state structural rearrangements in CS2.

Author

Unwin, James, Allum, Felix, Britton, Mathew, Gabalski, Ian, Bromberger, Hubertus, Brouard, Mark, Bucksbaum, Philip H., Driver, Taran, Ekanayake, Nagitha, Garg, Diksha, Gougoula, Eva, Heathcote, David, Howard, Andrew J., Hockett, Paul, Holland, David M. P., Kumar, Sonu, Lam, Chow-shing, Lee, Jason W. L., McManus, Joseph, and Mikosch, Jochen

Subjects
MOLECULAR physics, COULOMB explosion, SOFT X rays, CARBON disulfide, STRUCTURAL dynamics, X-rays, PHOTODISSOCIATION, ULTRASHORT laser pulses
Abstract

Structural imaging of transient excited-state species is a key goal of molecular physics, promising to unveil rich information about the dynamics underpinning photochemical transformations. However, separating the electronic and nuclear contributions to the spectroscopic observables is challenging, and typically requires the application of high-level theory. Here, we employ site-selective ionisation via ultrashort soft X-ray pulses and time-resolved Coulomb explosion imaging to interrogate structural dynamics of the ultraviolet photochemistry of carbon disulfide. This prototypical system exhibits the complex motifs of polyatomic photochemistry, including strong non-adiabatic couplings, vibrational mode couplings, and intersystem crossing. Immediately following photoexcitation, we observe Coulomb explosion signatures of highly bent and stretched excited-state geometries involved in the photodissociation. Aided by a model to interpret such changes, we build a comprehensive picture of the photoinduced nuclear dynamics that follows initial bending and stretching motions, as the reaction proceeds towards photodissociation. Coulomb Explosion imaging is a promising technique to study the ultrafast nuclear dynamics which underpin molecular photochemistry. By initiating Coulomb explosion through soft X-ray ionization, the authors are able to image ultrafast nuclear dynamics of a prototypical photoreaction. [ABSTRACT FROM AUTHOR]

Published
2023
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25. Multiparticle Cumulant Mapping for Coulomb Explosion Imaging

Author

Cheng, Chuan, primary, Frasinski, Leszek J., additional, Moğol, Gönenç, additional, Allum, Felix, additional, Howard, Andrew J., additional, Rolles, Daniel, additional, Bucksbaum, Philip H., additional, Brouard, Mark, additional, Forbes, Ruaridh, additional, and Weinacht, Thomas, additional

Published
2023
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27. Fragmentation Dynamics of Fluorene Explored Using Ultrafast XUV-Vis Pump-Probe Spectroscopy

Author

Garg, Diksha, Lee, Jason Wai Lung, Tikhonov, Denis, Chopra, Pragya, Steber, Amanda, Lemmens, Alexander, Erk, Benjamin, Allum, Felix, Boll, Rebecca, Cheng, Xuemei, Duesterer, Stefan, Gruet, Sebastien Patrice, He, Lanhai, Heathcote, David, Johny, Melby, Mohammad Kazemi, Mehdi, Koeckert, Hansjochen, Lahl, Jan, Loru, Donatella, Maclot, Sylvain, Mason, Robert, Mueller, Erland, Mullins, Terence, Olshin, Pavel, Passow, Christopher, Peschel, Jasper, Ramm, Daniel, Rompotis, Dimitrios, Trippel, Sebastian, Wiese, Joss, Ziaee, Farzaneh, Bari, Sadia, Burt, Michael, Küpper, Jochen, Rijs, Anouk, Rolles, Daniel, Techert, Simone, Eng-Johnsson, Per, Brouard, Mark, Vallance, Claire, Manschwetus, Bastian, Schnell, Melanie, BioAnalytical Chemistry, and AIMMS

Subjects
FELIX Molecular Structure and Dynamics, Materials Science (miscellaneous), Biophysics, General Physics and Astronomy, Physics::Optics, free electron laser, polycylic aromatic hydrocarbon (PAH), time-resolved spectroscopy, velocity-map imaging mass spectrometry, Physics::Atomic and Molecular Clusters, ddc:530, Physical and Theoretical Chemistry, ultrafast dynamics of molecules, Mathematical Physics, Astrophysics::Galaxy Astrophysics, FELIX - Free Electron Lasers for Infrared Experiments
Abstract

Frontiers in physics 10, 880793 (2022). doi:10.3389/fphy.2022.880793 special issue: "Electronic and Nuclear Quantum Dynamics of Molecules in Intense Laser Fields", We report on the use of extreme ultraviolet (XUV, 30.3 nm) radiation from the Free-electron LASer in Hamburg (FLASH) and visible (Vis, 405 nm) photons from an optical laser to investigate the relaxation and fragmentation dynamics of fluorene ions. The ultrashort laser pulses allow to resolve the molecular processes occurring on the femtosecond timescales. Fluorene is a prototypical small polycyclic aromatic hydrocarbon (PAH). Through their infrared emission signature, PAHs have been shown to be ubiquitous in the universe, and they are assumed to play an important role in the chemistry of the interstellar medium. Our experiments track the ionization and dissociative ionization products of fluorene through time-of-flight mass spectrometry and velocity-map imaging. Multiple processes involved in the formation of each of the fragment ions are disentangled through analysis of the ion images. The relaxation lifetimes of the excited fluorene monocation and dication obtained through the fragment formation channels are reported to be in the range of a few tens of femtoseconds to a few picoseconds., Published by Frontiers Media, Lausanne

Published
2022
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31. 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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33. Ultrafast probing of charge transfer dynamics with an XUV free-electron laser

Author

Allum, Felix, primary, Kumagai, Yoshiaki, additional, Nagaya, Kiyonobu, additional, Harries, James, additional, Iwayama, Hiroshi, additional, Niozu, Akinobu, additional, Ashfold, Mike, additional, Britton, Matthew, additional, Bucksbaum, Phillip, additional, Brouard, Mark, additional, Burt, Michael, additional, Heathcote, David, additional, Hockett, Paul, additional, Liu, Yusong, additional, Kukk, Edwin, additional, Lee, Jason, additional, McManus, Joseph, additional, Milesevic, Dennis, additional, Minns, Russell, additional, Niskannen, Johannes, additional, Orr-Ewing, Andrew, additional, Rolles, Daniel, additional, Rudenko, Artem, additional, Ueda, Kiyoshi, additional, Unwin, James, additional, Vallance, Claire, additional, Walmsley, Tiffany, additional, and Forbes, Ruaridh, additional

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

Author

Köckert, Hansjochen, primary, Lee, Jason W L, additional, Allum, Felix, additional, Amini, Kasra, additional, Bari, Sadia, additional, Bomme, Cédric, additional, Brauße, Felix, additional, Brouard, Mark, additional, Burt, Michael, additional, Cunha de Miranda, Barbara, additional, Düsterer, Stefan, additional, Eng-Johnsson, Per, additional, Erk, Benjamin, additional, Géléoc, Marie, additional, Geneaux, Romain, additional, Gentleman, Alexander S, additional, Guillemin, Renaud, additional, Goldsztejn, Gildas, additional, Holland, David M P, additional, Ismail, Iyas, additional, Journel, Loïc, additional, Kierspel, Thomas, additional, Küpper, Jochen, additional, Lahl, Jan, 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, Penent, Francis, additional, Piancastelli, Maria Novella, additional, Rompotis, Dimitrios, additional, Rouzée, Arnaud, additional, Ruchon, Thierry, additional, Rudenko, Artem, additional, Schirmel, Nora, additional, Simon, Marc, additional, Techert, Simone, additional, Travnikova, Oksana, additional, Trippel, Sebastian, additional, Vallance, Claire, additional, Wang, Enliang, additional, Wiese, Joss, additional, Ziaee, Farzaneh, additional, Marchenko, Tatiana, additional, Rolles, Daniel, additional, and Boll, Rebecca, additional

Published
2022
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36. Time-resolved Imaging of Transient Charge Transfer Dynamics

Author

Allum, Felix, primary, Kumagai, Yoshiaki, additional, Nagaya, Kiyonobu, additional, Harries, James, additional, Iwayama, Hiroshi, additional, Niozu, Akinobu, additional, Ashfold, Mike, additional, Britton, Mathew, additional, Bucksbaum, Philip, additional, Brouard, Mark, additional, Burt, Michael, additional, Heathcote, David, additional, Hockett, Paul, additional, Howard, Andrew, additional, Kukk, Edwin, additional, Lee, Jason, additional, Liu, Yusong, additional, McManus, Joseph, additional, Milesevic, Dennis, additional, Minns, Russell, additional, Niskannen, Johannes, additional, Orr-Ewing, Andrew, additional, Rolles, Daniel, additional, Rudenko, Artem, additional, Ueda, Kiyoshi, additional, Unwin, James, additional, Vallance, Claire, additional, Walmsley, Tiffanny, additional, and Forbes, Ruaridh, additional

Published
2022
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37. The kinetic energy of PAH dication and trication dissociation determined by recoil-frame covariance map imaging

Author

Lee, Jason W. L., primary, Tikhonov, Denis S., additional, Allum, Felix, additional, Boll, Rebecca, additional, Chopra, Pragya, additional, Erk, Benjamin, additional, Gruet, Sebastian, additional, He, Lanhai, additional, Heathcote, David, additional, Kazemi, Mehdi M., additional, Lahl, Jan, additional, Lemmens, Alexander K., additional, Loru, Donatella, additional, Maclot, Sylvain, additional, Mason, Robert, additional, Müller, Erland, additional, Mullins, Terry, additional, Passow, Christopher, additional, Peschel, Jasper, additional, Ramm, Daniel, additional, Steber, Amanda L., additional, Bari, Sadia, additional, Brouard, Mark, additional, Burt, Michael, additional, Küpper, Jochen, additional, Eng-Johnsson, Per, additional, Rijs, Anouk M., additional, Rolles, Daniel, additional, Vallance, Claire, additional, Manschwetus, Bastian, additional, and Schnell, Melanie, additional

Published
2022
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38. Disentangling sequential and concerted fragmentations of molecular polycations with covariant native frame analysis

Author

McManus, Joseph W., primary, Walmsley, Tiffany, additional, Nagaya, Kiyonobu, additional, Harries, James R., additional, Kumagai, Yoshiaki, additional, Iwayama, Hiroshi, additional, Ashfold, Michael N.R., additional, Britton, Mathew, additional, Bucksbaum, Philip H., additional, Downes-Ward, Briony, additional, Driver, Taran, additional, Heathcote, David, additional, Hockett, Paul, additional, Howard, Andrew J., additional, Kukk, Edwin, additional, Lee, Jason W. L., additional, Liu, Yusong, additional, Milesevic, Dennis, additional, Minns, Russell S., additional, Niozu, Akinobu, additional, Niskanen, Johannes, additional, Orr-Ewing, Andrew J., additional, Owada, Shigeki, additional, Rolles, Daniel, additional, Robertson, Patrick A., additional, Rudenko, Artem, additional, Ueda, Kiyoshi, additional, Unwin, James, additional, Vallance, Claire, additional, Burt, Michael, additional, Brouard, Mark, additional, Forbes, Ruaridh, additional, and Allum, Felix, additional

Published
2022
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42. Multi-channel photodissociation and XUV-induced charge transfer dynamics in strong-field-ionized methyl iodide studied with time-resolved recoil-frame covariance imaging

Author

Allum, Felix, primary, Anders, Nils, additional, Brouard, Mark, additional, Bucksbaum, Philip, additional, Burt, Michael, additional, Downes-Ward, Briony, additional, Grundmann, Sven, additional, Harries, James, additional, Ishimura, Yudai, additional, Iwayama, Hiroshi, additional, Kaiser, Leon, additional, Kukk, Edwin, additional, Lee, Jason, additional, Liu, Xiaojing, additional, Minns, Russell S., additional, Nagaya, Kiyonobu, additional, Niozu, Akinobu, additional, Niskanen, Johannes, additional, O’Neal, Jordan, additional, Owada, Shigeki, additional, Pickering, James, additional, Rolles, Daniel, additional, Rudenko, Artem, additional, Saito, Shu, additional, Ueda, Kiyoshi, additional, Vallance, Claire, additional, Werby, Nicholas, additional, Woodhouse, Joanne, additional, You, Daehyun, additional, Ziaee, Farzaneh, additional, Driver, Taran, additional, and Forbes, Ruaridh, additional

Published
2021
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44. Product state resolved dynamics of elementary reactions

Author

Brouard, Mark, O'Keeffe, Patrick, and Vallance, Claire

Subjects
Chemistry, Physical and theoretical -- Research, Chemical reactions -- Analysis, Molecular dynamics -- Research, Photons -- Physiological aspects, Quantum chemistry -- Research, Chemicals, plastics and rubber industries
Published
2002

47. Time-resolved site-selective imaging of predissociation and charge transfer dynamics: the CH3I B-band

Author

Forbes, Ruaridh, primary, Allum, Felix, additional, Bari, Sadia, additional, Boll, Rebecca, additional, Borne, Kurtis, additional, Brouard, Mark, additional, Bucksbaum, Philip H, additional, Ekanayake, Nagitha, additional, Erk, Benjamin, additional, Howard, Andrew J, additional, Johnsson, Per, additional, Lee, Jason W L, additional, Manschwetus, Bastian, additional, Mason, Robert, additional, Passow, Christopher, additional, Peschel, Jasper, additional, Rivas, Daniel E, additional, Rörig, Aljoscha, additional, Rouzée, Arnaud, additional, Vallance, Claire, additional, Ziaee, Farzaneh, additional, Rolles, Daniel, additional, and Burt, Michael, additional

Published
2020
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