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.