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Single- and multi-photon-induced ultraviolet excitation and photodissociation of CH3I probed by coincident ion momentum imaging

Journal Article · · Physical Chemistry Chemical Physics. PCCP
DOI:https://doi.org/10.1039/d3cp00498h· OSTI ID:2006863

The UV-induced photodissociation dynamics of iodomethane (CH3I) in its A-band are investigated by time-resolved coincident ion momentum imaging using strong-field ionization as a probe. The delay-dependent kinetic energy distribution of the photofragments resulting from double ionization of the molecule maps the cleavage of the carbon–iodine bond and shows how the existence of a potential well in the di-cationic potential energy surfaces shapes the observed distribution at small pump–probe delays. Furthermore, the competition between single- and multi-photon excitation and ionization of the molecule is studied as a function of the intensity of the UV-pump laser pulse. Two-photon excitation to Rydberg states is identified by tracking the transformation of the delay-dependent singly-charged iodomethane yield from a pure Gaussian distribution at low intensity to a Gaussian with an exponentially decaying tail at higher intensities. In conclusion, dissociative ionization induced by absorption of three UV photons is resolved as an additional delay-dependent feature in the kinetic energy of the fragment ions detected in coincidence.

Research Organization:
SLAC National Accelerator Laboratory (SLAC), Menlo Park, CA (United States). Linac Coherent Light Source (LCLS)
Sponsoring Organization:
USDOE Office of Science (SC), Basic Energy Sciences (BES). Chemical Sciences, Geosciences & Biosciences Division (CSGB)
Grant/Contract Number:
AC02-76SF00515; FG02-86ER13491
OSTI ID:
2006863
Alternate ID(s):
OSTI ID: 1963331
Journal Information:
Physical Chemistry Chemical Physics. PCCP, Journal Name: Physical Chemistry Chemical Physics. PCCP Journal Issue: 14 Vol. 25; ISSN 1463-9076
Publisher:
Royal Society of ChemistryCopyright Statement
Country of Publication:
United States
Language:
English

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  • Poullain, Sonia Marggi; Chicharro, David V.; Rubio-Lago, Luis
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