INFRARED-SPECTRUM OF THE NU-9-BANDS AND 2-NU-9-NU-9-BANDS OF DEUTERATED NITRIC-ACID (DNO3)

The high-resolution Fourier transform infrared spectrum of deuterated nitric acid (DNO3) has been measured in the ν9 region between 320 and 384 cm-1 with a resolution of 0.0035 cm-1. As expected for an out-of-plane vibrational fundamental, and accompanying hot bands, only C-type transitions were observed. Using a Watson Hamiltonian, 1772 infrared transitions have been assigned and fitted to give 9 rovibrational constants for the v9 = 1 state. With the knowledge of these constants, an analysis was made of 598 assigned transitions for the hot band 2ν9-ν9 in order to provide rovibrational constants for the v9 = 2 state. Both bands show no evidence of perturbation, although the v9 = 2 state is expected to be crossed by the v6 = 1 state above J = 40. The band centers are at 343.8496 ± 0.0001 cm-1 for ν9 and 333.7331 ± 0.0001 cm-1 for 2ν9-ν9. © 1991.