Improved spectroscopic constants for the ν2 infrared band of HNO3

The High-Resolution Infrared Spectrum of the ν5Band of Deuterated Formic Acid (DCOOH)

“…In fitting the assigned transitions we have used the nonlinear least-squares program (10,11). The program for fitting asymmetric rotor spectra uses a Watson Hamiltonian (13).…”

The 5.8 µm absorption bands for nitric acid (H14N16O3): line positions and intensities for the ν2 band at 1709.567 cm−1 and for its first associated hot bands (ν2+ν9−ν9, ν2+ν7−ν7, ν2+ν6−ν6)

“…The first laboratory measurement of this band was performed by A. Maki [18] using diode laser spectroscopy in the 1688 to 1737 cm -1 spectral region. Later, a more complete investigation of the 2 band was performed by Tan et al [19] using high resolution Fourier transform spectra. In this way 4459 B-type transitions were identified, involving rotational quantum numbers up to J72 and Ka 45.…”

“…Most of the 2 transitions appear unperturbed and could be reproduced satisfactorily using an A-type Watson-type Hamiltonian written in Ir reduction [20]. However, both Maki [18] and Tan et al [19] noticed that several local resonances affect transitions in the 1675, 1684, 1730 and 1737 cm -1 spectral regions. Therefore, in these two studies, the band center and the set of rotational constants for the 2 1 vibrational state were obtained during a least squares fit calculation performed on the observed transitions, after removing the perturbed lines from that list.…”

“…[15] using an A-type Watson I r reduced rotational Hamiltonian, and the (0) lower and (2 1 ) upper state energy levels were computed using the ground and upper state parameters collected in Refs. [21] and [19], respectively. Most of the lines are not affected by vibration rotation resonances.…”

“…It appeared that for the mainly B-type 2 band, the existence of a (very) small A-type component 1 1 Debye =3.33564 x10 -30 C.m. In their papers Maki [18] and Tan et al [19] use the values 𝜇 2,0 1 𝐵 = 0.2845 and 0.249 Debye, respectively. We presume that they use a different value of the partition function.…”