Deformationally self-consistent treatment of high-resolution coherent Raman spectra of14N2 and15N2 in the X1Σ+G electronic ground state

Abstract

The coherent Raman spectra of electrically discharged 14 N 2 and 15 N 2 were analysed using the deformationally self-consistent procedure for the treatment of spectral data. By making use of eight independent unconstrained parameters, 356 measured spectral lines were reproduced with s = 0.0023 cm −1 ,ŝ = 1.96 and F = 8.74 × 10 13 . From a marginally evaluated value of the parameter t N 0 , related to non-adiabatic rotational effects, we predicted a rough value of the rotational g-factor for 15 N 2 g 0 = −0.37(21), near the known experimental value g 0 = −0.2593(5). Fit with the constrained t N 0 yielded s = 0.0023 cm −1 ,ŝ = 1.96, F = 1.00×10 14 , and the set of seven well evaluated parameters representing the Born-Oppenheimer potential energy function and non-adiabatic vibrational effects.

An accurate analytic potential function for ground-state N2 from a direct-potential-fit analysis of spectroscopic data

“…In previous combined-isotopologue analyses of the CARS data for N 2 by Orlov et al 14 and by Molski, 68,69 the leading parameter in the expression for the BOB correction to the centrifugal potential, t 0 N of Eq. ͑17͒, was held fixed at a value based on the magnitude of the rotational g factor ͓͉g J ͉ = 0.2593͑5͒ nm/ J͔ determined from molecular beam measurements on 15,15 N 2 .…”

Improved rotating Kratzer–Fues oscillator: eigenenergies, eigenfunctions, coherent states and ladder operators

“…In such circumstances, in theoretical reproduction of the spectral data the diagonal Born-Oppenheimer corrections (mass shift dominating for light molecules) and isotopic field shifts contributing significantly to heavy species [28] should be taken into consideration. In the quantitative analysis of the highly resolved IR and MW spectra usually the adiabatic and non-adiabatic vibrational and rotational corrections during simultaneous fitting of the data for various isotopomers are taken into account [13,17,29,30]. The high accuracy of data reproduction using the IKF energy formula (21) with additional parameters k i , D j indicates that these effects are correctly reproduced by them, leading to the satisfactory agreement between theoretical and experimental results (see Supplementary Materials).…”

Improved Energy Formula for Highly Excited Vibrational States of Kratzer-Fues Oscillator

“…which reveals the vibrational v-dependence of the equilibrium bond length r 0 and potential depth D 0 (see Figures 1 and 2). With a high degree of probability, nonadiabatic vibrational effects are responsible for this type of effects, which have a significant impact on the energy levels in highly excited vibrational states [40]. Because such effects are not explicitly included in the KF model, the original KF energy formula does not reproduce experimental vibrational transitions and energy levels accurately (see Tables 2 and 4).…”