Modelling of the 2ν1-ν1 and ν1 band transitions of 13CH4 using high resolution Raman spectroscopy measurements

The pump-probe technique for investigating vibrationally excited states via high resolution Raman spectroscopy was applied to (CH4)-C-13 methane isotopologue. The dipole transitions between A(1) totally symmetric vibrational states are not active in IR spectra but these states can be efficiently studied using selective high resolution Raman spectroscopy. 80 vibration-rotation transitions, most of which belong to the 2 nu(1) - nu(1) band have been assigned in the observed Raman spectra reported in this work. Including the Raman transitions in the simultaneous data fit improves the accuracy of the effective Hamiltonian and also rovibrational upper state levels of the.1, 2(nu 1) and 2.3 (A(1)) bands. A more accurate model of the nu(1) vibration-rotation transitions improves the interpretation of the temperature dependence of Raman spectra involving the Pentad and Tetradecad polyads. (C) 2021 Elsevier Ltd. All rights reserved.

Automated summary

The pump-probe technique using high resolution Raman spectroscopy was applied to investigate vibrationally excited states in (CH4)-C-13 methane isotopologue. The dipole transitions between A(1) totally symmetric vibrational states, inactive in IR spectra, can be efficiently studied using selective high resolution Raman spectroscopy. In this work, 80 vibration-rotation transitions, mainly belonging to the 2 nu(1) - nu(1) band, have been assigned in the observed Raman spectra.