Direct Observation of the Transition-State Region in the Photodissociation of CH 3 I by Femtosecond Extreme Ultraviolet Transient Absorption Spectroscopy
- Department of Chemistry, University of California, Berkeley, California 94720, United States, Chemical Sciences Division, Lawrence Berkeley National Laboratory, Berkeley, California 94720, United States
- Department of Chemistry, University of California, Berkeley, California 94720, United States, Chemical Sciences Division, Lawrence Berkeley National Laboratory, Berkeley, California 94720, United States, Department of Physics, University of California, Berkeley, California 94720, United States
Femtosecond extreme ultraviolet (XUV) pulses produced by high harmonic generation are used to probe the transition-state region in the 266 nm photodissociation of CH3I by the real-time evolution of core-to-valence transitions near the iodine N-edge at 45-60 eV. During C-I bond breaking, new core-to-valence electronic states appear in the spectra, which decay concomitantly with the rise of the atomic iodine resonances of I(2P3/2) and I*(2P1/2). The short-lived features are assigned to repulsive valence-excited transition-state regions of 3Q0 and 1Q1, which can connect to transient core-excited states via promotion of 4d(I) core electrons. A simplified one-electron transition picture is described that accurately predicts the relative energies of the transient states observed. The transition-state resonances reach a maximum at ~40 fs and decay to complete C-I dissociation in ~90 fs, representing the shortest-lived chemical transition state observed by core-level, XUV, or X-ray spectroscopy.
- Research Organization:
- Lawrence Berkeley National Laboratory (LBNL), Berkeley, CA (United States)
- Sponsoring Organization:
- USDOE Office of Science (SC), Basic Energy Sciences (BES)
- Grant/Contract Number:
- AC02-05CH11231
- OSTI ID:
- 1229692
- Alternate ID(s):
- OSTI ID: 1532172
- Journal Information:
- Journal of Physical Chemistry Letters, Journal Name: Journal of Physical Chemistry Letters Vol. 6 Journal Issue: 24; ISSN 1948-7185
- Publisher:
- American Chemical SocietyCopyright Statement
- Country of Publication:
- United States
- Language:
- English
Web of Science
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