Photodissociation of N₂O₄ Adsorbed on Amorphous and Crystalline Water−Ice Films

The photodissociation dynamics of N 2 O 4 adsorbed on amorphous and polycrystalline water−ice films has been studied at 193, 248, and 351 nm. The adsorbed states of N 2 O 4 on the ice films at 80−140 K were investigated by infrared-absorption and temperature-programmed desorption measurements. Time-of-flight (TOF) spectra of the photofragments were measured by probing the resonance-enhanced multiphoton ionization signals of NO( v, J ) and O( 3 P j ). Internally and translationally relaxed NO photofragments were observed. Their energy distributions were mostly independent of the states of the ice films and the photolysis laser wavelengths. The TOF distributions of NO( v = 0) consist of fast and slow components. The slow component is dominant. A large difference in the dissociation yields between amorphous and crystalline ice experiments was observed.