First Analysis of the 3ν9 − ν9, 3ν9 − ν5, and 3ν9 − 2ν9 Bands of HNO3: Torsional Splitting in the ν9 Vibrational Mode

The rotational spectra of the 7191, 6191, and 72 vibrational states of nitric acid

“…The splitting for the 9 3 state of 1760 MHz was taken from our unpublished preliminary analysis similar to the ones reported here for $60 mm/submm-wave transitions in the symmetric-top limit. This agrees with the previously observed splitting in the infrared spectrum by Perrin et al [23] of $1710 MHz. The predicted cubic force constants of / 699 = 59.2 cm À1 and / 799 = 43.9 cm À1 were taken from the DFT calculation and lead to a predicted percent mixing of 1.88% between the 6 1 9 1 and 9 3 states and 0.58% between 7 1 9 1 and 9 3 states.…”

“…where DE n99 is the difference in the observed band origins between the 9 3 state and either the 7 1 9 1 or 6 1 9 1 state, which were determined from [1,23]. The predicted induced torsional splitting is given by a 2 n99 D, where D is the torsional splitting observed in the 9 3 state spectra.…”

The Energy Levels of the ν5/2ν9 Dyad of HNO3 from Millimeter and Submillimeter Rotational Spectroscopy

“…To initially generate the IAS Hamiltonian, we used the experimentally determined equilibrium structure from Cox et al (15) and the potential barrier to internal rotation from Perrin et al (16) as inputs for a series of programs written by Pickett (14), MOIAM and IAMCALC. As part of the output, these programs determined the first order parameters for the IAS Hamiltonian and generated the constants ρ, E ρ , A, B, C, and D ab for the 2ν 9 vibrational state.…”

Rotational Spectrum of HNO3in the ν5and 2ν9Vibrational States

“…(7,12), where it is shown All of these data have been analyzed to within experimen-that the large amplitude torsional motion splits the energy tal accuracy (Ç0.1 MHz/3 1 10 06 cm 01 ) by means of a levels into two sublevels, half of which are not populated. Hamiltonian which includes: (1) a set of rotation/distortion This leads to two torsional states which share one set of constants for each of the torsional states of 2n 9 and a single rotational labels, half in each torsional state.…”