Table of Contents
Laser Chemistry
Volume 9, Issue 4-6, Pages 289-315

The State-selected Predissociation Dynamics of CClF2NO Ã(n,π*)

1Department of Chemistry, Heriot-Watt University, Riccarton, Edinburgh EH14 4AS, Scotland
2School of Chemical Sciences, University of East Anglia, Norwich NR4 7TJ, UK
3Proctor and Gamble (NTC), Whitley Road, Longbenton, Newcastle NE12 9TS, UK

Received 20 May 1988

Copyright © 1988 Hindawi Publishing Corporation. This is an open access article distributed under the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.


The photodissociation of gaseous CClF2NO at 300 K and <20 K in a supersonic jet has been studied in the wavelength range 568 to 705 nm of the S1(n,π*)S0 electronic transition. Energy disposal into, rates of formation and product-state distributions of the nascent NO(X2Πi) photofragment have been measured in detail, and have been compared with statistical (Prior) calculations. The rotational population distributions of the NO fragment are statistical up to the highest excess energies investigated, while the spin-orbit branching ratios are very non-statistical and non-thermal, favouring the lower component. The lack of evidence for state-specific effects in the energy disposal and appearance times of the NO indicate that excess energy randomises prior to dissociation. Intersystem crossing to T1 dominates the predissociation of all but the lowest S1 levels. Levels close to the O,O origin predissociate either by internal conversion to the ground state or by vibrational predissociation on an S1 potential energy surface that is weakly bound in the dissociation coordinate. A bond dissociation energy of 13 700 ± 350 cm−1 (164 kJ mol−1) has been evaluated for the C—N bond.