Nonadiabatic dynamics in the photodissociation of ICH2CN at 266 and 304 nm studied by the velocity map imaging

Title
Nonadiabatic dynamics in the photodissociation of ICH2CN at 266 and 304 nm studied by the velocity map imaging
Authors
Lee, K.S.; Lim, J.S.; Ahn, D.S.; Choi, K.W.; Kim, S.K.; Choi, Y.S.
Keywords
ENHANCED MULTIPHOTON IONIZATION, TRIATOMIC PHOTOFRAGMENT SPECTRA
Issue Date
2006-03
Publisher
AMER INST PHYSICS
Abstract
Photodissociation dynamics of iodoacetonitrile (ICH2CN) have been investigated at pump wavelengths of 266 and 304 nm using a photofragment ion image velocity mapping technique. At both wavelengths, the prompt C-I bond rupture takes place on the repulsive excited states to give I(P-2(3/2)) and I-*(P-2(1/2)), and their speed and spatial distributions are simultaneously measured. The recoil anisotropy parameter (beta) at 266 nm is determined to be 1.10 and 1.60 for I and I-*, respectively, while it is found to be much higher at 304 nm to give beta=1.70 and 1.90 for I and I-*, respectively. The branching ratios for I-*/I channels are measured to be 0.724 and 0.136 at 266 and 304 nm, respectively, giving insights on nonadiabatic transition phenomena and relative oscillator strengths of optically accessible transitions of ICH2CN. Accordingly, relative oscillator strengths of parallel/perpendicular transitions and nonadiabatic transitions among the excited states are quantitatively characterized. A large portion of the available energy (41%-48%) goes into the internal energy of the CH2CN fragment. A modified impulsive model in which the CH2CN fragment is assumed to be rigid predicts the energy disposal quite well. Delocalization of an unpaired electron of the CH2CN radical during the C-I bond cleavage, leading to a large structural change of the CH2CN moiety, may be responsible for internally hot fragments. (c) 2006 American Institute of Physics.
URI
http://dspace.inha.ac.kr/handle/10505/1950
ISSN
0021-9606
Appears in Collections:
School of Arts & Sports(예술체육학부) > Visual Communication Design (시각정보디자인) > Journal Papers & Peports (시각정보디자인_논문,보고서)
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