Iqbal, Azhar, Cheung, Michelle, Nix, Michael G. D. and Stavros, Vasilios G.. (2009) Exploring the time-scales of H-atom detachment from photoexcited phenol-h(6) and phenol-d(5): statistical vs nonstatistical decay. Journal of Physical Chemistry A, Vol.113 (No.29). pp. 8157-8163. ISSN 1089-5639

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Abstract

The prevalence of 1 pi sigma* states in the photochemistry of heteroaromatics is becoming increasingly clear from the recent literature. Photodissociation measurements have shown that following excitation of phenol molecules above the S-1/S-2 conical intersection, H-atoms are eliminated with two distinct ranges of kinetic energy release. Those with high kinetic energy are attributed to direct dissociation while those with low kinetic energy are traditionally attributed to indirect dissociation or statistical unimolecular decay, both pathways giving electronic ground-state phenoxyl fragments. Using a combination of femtosecond pump/probe spectroscopy and velocity map ion imaging techniques, the time and energy resolved H-atom elimination in phenol-h(6) and phenol-d(5), following excitation at 200 nm has been measured. At the lowest kinetic energies, the H-atom elimination from phenol-d(5) occurs in < 150 fs, in sharp contrast to what one expects from a statistical decay process. This implies that these H-atoms are formed through a direct dissociation process yielding electronically excited phenoxyl fragments.

Item Type:	Journal Article
Subjects:	Q Science > QD Chemistry Q Science > QP Physiology
Divisions:	Faculty of Science > Chemistry
Library of Congress Subject Headings (LCSH):	Photodissociation, Molecular dynamics, Tryptophan, Photochemistry, Pyrroles, Elimination reactions
Journal or Publication Title:	Journal of Physical Chemistry A
Publisher:	American Chemical Society
ISSN:	1089-5639
Date:	23 July 2009
Volume:	Vol.113
Number:	No.29
Number of Pages:	7
Page Range:	pp. 8157-8163
Identification Number:	10.1021/jp9031223
Status:	Peer Reviewed
Publication Status:	Published
Access rights to Published version:	Restricted or Subscription Access
Funder:	Royal Society (Great Britain), Engineering and Physical Sciences Research Council (EPSRC), University of Warwick
Grant number:	EP/E0 11187 (EPSRC)
URI:	http://wrap.warwick.ac.uk/id/eprint/27593

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