Study of low-lying electronic states of molecules in relation to photodissociation

The possibility of using photofragment spectroscopy to detect complex molecules in the gas phase is considered. Aliphatic alcohols CnH2n+1OH (n=2–4) as well as formaldehyde, acetaldehyde, and benzaldehyde are discussed from this stand-point. The state S1 for alcohols is shown to be labile in regard to both the detachment of the OH radical and the detachment of a hydrogen atom. The arrangement of the terms is such that decomposition with the formation of OH(A2Σ+) becomes possible as the structure of the alcohol becomes more complex. The rate constants of the dissociation of aldehydes via a molecular channel are evaluated within the framework of the RRKM theory. The dissociation rate constant is found to decrease substantially as the structure of the aldehyde becomes more complex.