The 193 nm photolysis of NO2: NO(ν) vibrational distribution,O(1D) quantum yield and emission from vibrationally excited NO2

Time resolved Fourier transform infrared emission has been used to study the photolysis of NO2 and its dimer N2O4 at 193 nm. NO(ν) populations from the photolysis of NO2 show a bimodal distribution, peaking at ν = 5 and with a subsidiary maximum at ν = 14, close to the energetically allowed limit. The results are discussed in terms of previous measurements near this photolysis wavelength of the kinetic energies of the two possible O atomic fragments, O(3P) and O(1D), and on the electronic states of the parent molecule which can be populated. The O(1D) yield has been measured as 0.51 ± 0.04, in good agreement with previously reported values. Emission from vibrationally excited NO2 arises from the dissociation of N2O4 and is similar to that observed from photolysis at 248 nm.