Abstract
We detected fluorescence of OH (Α 2 Σ + -Χ 2 Π) from nitric acid photolyzed at 193 nm. Transitions for spin-orbit states are resolved; the population ratio of these states is Π 3/2 /Π 1/2 ≈ 1.1 ± 0.1. About 3% of available energy is distributed to rotation of the OH fragment; no vibrationally excited OH was observed. The translational energies of OH and NO 2 are estimated from the Doppler widths to be 2332 and 861 cm -1 , respectively. These results indicate about 87.8% of the excess energy to be directed to internal energy of NO 2 . The experimental data indicate that NO 2 may be produced in an electronically excited state.