E.C. Looi

Infrared Spectrum of the ν6 and ν7 Bands of Deuterated Nitric Acid (DNO3)

Abstract The high-resolution Fourier transform infrared spectrum of deuterated nitric acid (DNO 3 ) has been measured in the ν 9 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 v 9 = 1 state. With the knowledge of these constants, an analysis was made of 598 assigned transitions for the hot band 2 ν 9 - ν 9 in order to provide rovibrational constants for the v 9 = 2 state. Both bands show no evidence of perturbation, although the v 9 = 2 state is expected to be crossed by the v 6 = 1 state above J = 40. The band centers are at 343.8496 ± 0.0001 cm −1 for ν 9 and 333.7331 ± 0.0001 cm −1 for 2 ν 9 - ν 9 .

High resolution FTIR measurement and analysis of the ν8 band of deuterated nitric acid (DNO3)

Abstract The infrared spectrum of the ν 8 band of deuterated nitric acid (DNO 3 ) has been measured with a resolution of 0.002 cm −1 in the frequency range of 730 to 794 cm −1 . A total of 1888 assigned transitions have been analyzed to provide rovibrational constants for the upper state with a standard deviation of 0.00022 cm −1 . In the course of the analysis, the constants for the ground state were improved. Because of the absence of perturbations, the constants can be used to accurately calculate the infrared line positions for the band. The band is C -type with a band center at 762.8738 ± 0.0001 cm −1 . As was found for ν 8 of HNO 3 , the P branch is much weaker than the R branch. Effective Herman-Wallis correction factors are given for the band.

High resolution FTIR spectrum of the ν5 and 2ν9 bands of HNO3

Abstract The Fourier transform infrared (FTIR) spectrum of the ν 5 and 2ν 9 bands of nitric acid (HNO 3 ) has been measured with a resolution of 0.004 cm −1 in the frequency range of 856–910 cm −1 . By fitting a total of 744 unperturbed transitions of ν 5 with a standard deviation (SD) of 0.00051 cm −1 , using a Watson Hamiltonian, a set of nine improved rovibrational constants for the upper state was obtained. Some transitions of 2ν 9 were perturbed by a Femi resonance with the nearby ν 5 state. A total of 280 unperturbed transitions of 2ν 9 have been analyzed to provide nine rovibrational constants for the υ 9 = 2 state with a SD of 0.00058 cm −1 . The ν 5 and 2ν 9 bands are mainly A -type with band centres at 879.108200 ± 0.000045 and 896.44881 ± 0.00011 cm −1 , respectively. A comparison of calculated line intensities of ν 5 with measured values gives the transition moment as 0.155 ± 0.031 D and the integrated band intensity as 282 ± 56 cm −2 atm −1 (or 68 ± 14 km mol −1 ). The transition moment of the 2ν 9 band is therefore estimated to be 0 17 ± 0.03 D which gives an integrated band intensity of 356 ± 71 cm −2 atm −1 (or 86 ± 17 km mol −1 ).

Hot-band spectrum of OCS near 850 cm−1

A global rovibrational analysis of OCS based on data from different measurements has been reported by Fayt et al. Their work has provided good estimates of effective level constants, including those of the present study, up to 4950 cm −1 . In the course of collecting the spectra of the ν 1 fundamental band of OCS for calibration standard studies we found that these hot bands of OCS have sufficient intensity for an analaysis

FTIR measurements on the 3ν2-ν2 band of carbonyl sulfide

During the course of work on calibration standard studies on the 2ν 2 band of OCS it was discovered that the spectrum of the 3ν 2 -ν 2 hot band was present with sufficient intensity for attempting accurate measurements. The increased resolution and sensitivity of FTS have made this possible. Because our Fourier transform measurements of the hot band involve a high level of accuracy and a wide range of J values in both its P and R branches, it is of interest to report our measurements and make a comparison with the heterodyne frequency measurements