Time-resolved site-selective imaging of predissociation and charge transfer dynamics: the CH3I B-band
Year: 2020
Type: article
Abstract: The predissociation dynamics of the 6s (B 2 E) Rydberg state of gas-phase CH 3 I were investigated by time-resolved Coulomb-explosion imaging using extreme ultraviolet (XUV) free-electron laser pulses. Inner-shell ionization at the iodine 4d edge was utilized to provide a site-specific probe of the ensuing dynamics. The combination of a velocity-map imaging (VMI) spectrometer coupled with the pixel imaging mass spectrometry (PImMS) camera permitted three-dimensional ionic fragment momenta to be recorded simultaneously for a wide range of iodine charge states. In accord with previous studies, initial excitation at 201.2 nm results in internal conversion and subsequent dissociation on the lower-lying A-state surface on a picosecond time scale. Examination of the time-dependent yield of low kinetic energy iodine fragments yields mechanistic insights into the predissociation and subsequent charge transfer following multiple ionization of the iodine products. The effect of charge transfer was observed through differing delay-dependencies of the various iodine charge states, from which critical internuclear distances for charge transfer could be inferred and compared to a classical over-the-barrier model. Time-dependent photofragment angular anisotropy parameters were extracted from the central slice of the Newton sphere, without Abel inversion, and highlight the effect of rotation of the parent molecule before dissociation, as observed in previous works. Our results demonstrate the ability to perform three-dimensional ion imaging at high event rates and showcase the potential benefits of this approach, particularly in relation to further time-resolved studies at free-electron laser facilities.
Authors: Ruaridh Forbes, Felix Allum, Sadia Bari, Rebecca Boll, Kurtis Borne, Mark Brouard, Philip H Bucksbaum, Nagitha Ekanayake, Benjamin Erk, Andrew J Howard, Per Johnsson, Jason W L Lee, Bastian Manschwetus, Robert Mason, Christopher Passow, Jasper Peschel, Daniel E Rivas, Aljoscha Rörig, Arnaud Rouzée, Claire Vallance, Farzaneh Ziaee, Daniel Rolles, Michael Burt
Language: English
Subfield: Atomic and Molecular Physics, and Optics
Field: Physics and Astronomy
Domain: Physical Sciences
Open Access status: hybrid
Estimated APC paid: $3,325
Funders: National Science Foundation, U.S. Department of Energy, CALIPSOplus, Stiftelsen för Strategisk Forskning, Bundesministerium für Bildung und Forschung, Max-Planck-Gesellschaft, Vetenskapsrådet, Helmholtz Association, Office of Science, Engineering and Physical Sciences Research Council, Deutsches Elektronen-Synchrotron, Horizon 2020, Basic Energy Sciences, Chemical Sciences, Geosciences, and Biosciences Division
Awards: G1077140421, G1797787269, G1815137805, Chemical Applications of Velocity and Spatial Imaging, G2197341383, G222768804, G2573442069, STRUCTURE AND DYNAMICS OF ATOMS, IONS, MOLECULES AND SURFACES, G2978581158, G333714909, G3530777102, G3826261775, INVESTIGATING CHARGE TRANSFER AND CHARGE MIGRATION ON THE FEW- TO SUB-FEMTOSECOND TIME SCALE, G4336652674, Verbundprojekt: FSP 301 - FLASH: Nanoskopische Systeme. Teilprojekt 1.1: Universelle Experimentierkammer für Streuexperimente mit kohärenten Femtosekunden-Röntgenpulsen Multi Purpose Coherent Scattering Chamber for FLASH and XFEL 'MPscatt'., Verbundprojekt FSP 302 - Freie-Elektronen-Laser: Nanoskopische Systeme. Teilprojekt 4: Dynamik einzelner Nanoteilchen in Femtosekunden-Zeitlupe - Filmen mit ultrakurzen Röntgen-Doppelpulsen., G516729603, G5368910837, Imaging Chemical Dynamics with Ultrafast Laser Spectroscopy, G5648016710, G585716984, G6033966476, G6315639276, ATOMIC PHYSICS WITH HIGHLY CHARGED IONS, Verbundprojekt: FSP 301 - FLASH: Nanoskopische Systeme. Teilprojekt 1.2: Universelle Experimentierkammer für Streuexperimente mit kohärenten Femtosekunden-Röntgenpulsen Multi Purpose Coherent Scattering Chamber for FLASH and XFEL 'MPscatt'., G786475436, G788120174, G8395316192, Verbundprojekt 05K2016 - Nanoteilchenstruktur: Hochaufgelöste Struktur und Dynamik einzelner Nanoteilchen. Teilprojekt 1., STRUCTURE AND DYNAMICS OF ATOMS, IONS, MOLECULES AND SURFACES
OpenAlex ID: W3080425654