The Coriolis Interaction between the v2 = 1 and v3 = 2 States of Nitrosyl Bromide: Anomalous Quadrupole Patterns and Interstate Transitions in the Millimeter-Wave Spectrum.
The millimeter-wave rotational spectra of 79BrNO and 81BrNO in the v2 = 1 and v3 = 2 vibrational states have been reinvestigated. Measurements of the rotational spectrum in the region of maximum c-type Coriolis interaction between the two states allowed the previous analysis to be extended to account for some uncommon effects. For the most perturbed transitions the nuclear quadrupole hyperfine structure arises from coupling of not only the bromine nucleus, but also the nitrogen nucleus with the rotational angular momentum. These effects were satisfactorily fitted with a Hamiltonian describing Coriolis coupling in a molecule with two quadrupolar nuclei. The successful analysis of pure rotational transitions then allowed accurate prediction of rovibrational transitions, six of which were measured for 79BrNO and four for 81BrNO. Copyright 1998 Academic Press.
The Rotational Spectrum of ClClO2 in Its v4=1 and v6=1 Vibrationally Excited States: An Example of Strong Coriolis Interaction
Abstract The two lowest vibrational states of 35 Cl 35 ClO 2 , v 4 =1 ( A ′) and v 6 =1 ( A ″), were investigated between 223 and 500 GHz. More than 250 rotational transitions were recorded with J and K a up to 71 and 34, respectively. The spectra are heavily perturbed by strong c -type and weaker a -type Coriolis interactions. Near degeneracies of rotational levels of the two vibrational states having Δ J =0, Δ K a =5 to 1, and Δ K a +Δ K c = odd cause moderate to severe perturbations in the rotational structure, preventing the states from being fit as isolated ones. Distortions in the hyperfine structure facilitated the assignment of rotational quantum numbers. Several resonantly interacting levels with Δ K a =5 to 2 were accessed, and a number of transitions between the states were observed. While resonant Coriolis interaction with Δ K a =1 occurs only at K a >40, the effects of this interaction are so severe that nonresonant interaction considerably perturbs the highest K a Q -branches observed. The observed transitions could be fit to within experimental uncertainties employing the first-order Coriolis coupling constants fixed to those from the harmonic force field, sextic distortion constants fixed to those of the ground state, and some higher order Coriolis terms. The energy difference calculated from the fit agrees well with that obtained from the matrix-isolation infrared spectrum. Quadrupole coupling constants were determined for both Cl nuclei and both vibrational states.
Millimeter wave spectra of NOCl and NOBr and force constant determination
Abstract First order centrifugal distortion constants of NO35Cl and NO37Cl and of NO79Br have been obtained from millimeter wave rotational spectra. Their values in KHz are: DJ = 6·35 ± 0·2 DJK = −58·5 ± 2 for NO35Cl DJ = 6·01 ± 0·2 DJK = −57·4 ± 2 for NO37Cl DJ = 3·05 ± 0·1 DJK = −54·8 ± 2 for NO79Br Using microwave and infra-red data all the force constants of the general force field have been determined for both molecules.