Absolute I* quantum yields for the ICN Ã state by diode laser gain-vs-absorption spectroscopy

Absolute I* quantum yields have been measured as a function of wavelength for room temperature photodissociation of the ICN Ã state continuum. The yields are obtained by the technique of time-resolved diode laser gain-vs-absorption spectroscopy. Quantum yields are evaluated at seven wavelengths from 248 to 284 nm. The yield at 266 nm is 66.0±2% and it falls off to 53.4±2% and 44.0±4% at 284 and 248 nm, respectively. The latter values are significantly higher than those obtained by previous workers using infrared fluorescence. Estimates of I* quantum yields obtained from analysis of CN photofragment rotational distributions, as discussed by other workers, are in good agreement with the I* yields reported here. The results are considered in conjunction with recent theoretical and experimental work on the CN rotational distributions and with previous I* quantum yield results.