Journal Article

PUBDB-2026-00279

http://join2-wiki.gsi.de/foswiki/pub/Main/Artwork/join2_logo100x88.png Time-resolved momentum imaging of UV photodynamics in structural isomers of iodopropane probed by site-selective XUV ionization

Allum, F. (Corresponding author)Extern*DESY* ; Kumagai, Y. ; Nagaya, K. ; Harries, J. R. ; Iwayama, H. ; Britton, M. ; Bucksbaum, P. H. ; Burt, M. ; Brouard, M. ; Downes-Ward, B. ; Driver, T. ; Heathcote, D. ; Hockett, P. ; Howard, A. J. ; Lee, J. W. L.Extern*DESY* ; Liu, Y. ; Kukk, E. ; McManus, J. W. ; Milešević, D. ; Minns, R. S. ; Niozu, A. ; Niskanen, J. ; Orr-Ewing, A. J. ; Owada, S. ; Robertson, P. ; Rolles, D.Extern* ; Rudenko, A. ; Ueda, K. ; Unwin, J. ; Vallance, C. ; Walmsley, T. ; Ashfold, M. N. R. ; Forbes, R. (Corresponding author)Extern*XFEL.EU*

2025
RSC Publ. Cambridge

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Please use a persistent id in citations: doi:10.1039/D5CP02929E

Abstract: The photodynamics of 1- and 2-iodopropane (1 and 2-IP) were studied in a time-resolved scheme incorporating ultraviolet (UV) excitation and extreme ultraviolet (XUV) probing, which initiates photoionization selectively from the I 4d core orbital. UV absorption in the A-band of both isomers leads to prompt C–I bond fission, with significant disposal of internal energy into the propyl radical product. Site-selective ionization enables a range of charge transfer (CT) processes between the nascent highly charged iodine ions and neutral propyl radicals, dependent on the interfragment distance at the instant of ionization. Subtle differences in the dynamics of these CT processes between the two isomers are observed. In 1-IP, the kinetic energies of iodine ions produced by UV photodissociation and subsequent XUV multiple ionization increased notably over the first few hundred femtoseconds, which could be understood in terms of differing gradients along the photodissociation coordinates of the neutral and polycationic states involved in the pump and probe steps, respectively. Led by a recent report of HI elimination in UV photoexcited 2-IP [Todt et al., Phys. Chem. Chem. Phys., 22(46), 27338 (2020)], we also model the most likely signatures of this process in the present experiment, and can identify signal in the 2-IP data (that is absent or significantly weaker in the data from the unbranched 1-IP isomer) that is consistent with such a process occurring on ultrafast timescales.

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Contributing Institute(s):

1. FS-FLASH (CFEL-UDSS)

Research Program(s):

1. 631 - Matter – Dynamics, Mechanisms and Control (POF4-631) (POF4-631)

Experiment(s):

1. Measurement at external facility

Appears in the scientific report 2025

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Database coverage:
; Clarivate Analytics Master Journal List ; Current Contents - Physical, Chemical and Earth Sciences ; Essential Science Indicators ; IF < 5 ; JCR ; National-Konsortium ; SCOPUS ; Science Citation Index Expanded ; Web of Science Core Collection

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