Journal of Chemical Physics, Vol.103, No.12, 4879-4886, 1995
Photodissociation of HNO3 at 193 nm - Near-Infrared Emission of No Detected by Time-Resolved Fourier-Transform Spectroscopy
Rotationally resolved emission of NO, produced from photolysis of HNO3 at 193 nm, in the near infrared region (8900-9300 cm(-1)) was recorded with a step-scan Fourier-transform interferometer at a resolution of 0.1 cm(-1). The emission is assigned as NO D (2) Sigma(+) -A (2) Sigma(+) (nu’,nu")=(0,0) band with rotational states N’=17-42. Emission from selective rotational states of NO D (2) Sigma(+) was observed when HNO3 was photolyzed with an ArF excimer laser having a narrow bandwidth approximate to 0.01 nm. The experimental results indicate that the D (2) Sigma(+) state of NO is formed via absorption of another 193 nm photon by NO (nu"=1) in the ground electronic state. The measured distribution of intensity implies that NO is produced highly rotationally excited; the most likely mechanism for formation of NO is from the unstable NO2 fragment undergoing secondary dissociation.
Keywords:LASER-INDUCED GRATINGS;1ST ABSORPTION-BAND;NITRIC-ACID;STATE DISTRIBUTIONS;UNIMOLECULAR DECOMPOSITION;2-PHOTON PHOTODISSOCIATION;QUANTUM YIELDS;COOLED NO2;FREE JETS;248 NM