The photodissociation of water-clustered HNO3 studied at 193 nm by the LIF method

We studied the photodissociation of water-clustered HNO3 molecules at 193 nm, a process relevant in atmospheric chemistry, by generating water clusters by adiabatic expansion and doping them with HNO3 using the pickup method. The nascent OH(X2Π) photofragments were probed by LIF, and the rotational state distribution in the exclusively produced vibrational ground state determined. These experiments were complemented by corresponding ones with argon and methanol clusters. The average cluster size was estimated to be n∼200–800 depending on the compound. The results of this study are compared with those previously obtained from the photodissociation of the HNO3 monomer.