Related Experiment Video
Updated: Mar 29, 2026

Computation of Atmospheric Concentrations of Molecular Clusters from ab initio Thermochemistry
Published on: April 8, 2020
Ab initio variational predictions for understanding highly congested spectra: rovibrational assignment of 108 new
Michaël Rey1, Andrei V Nikitin, Alain Campargue
1Groupe de Spectrométrie Moléculaire et Atmosphérique, UMR CNRS 7331, BP 1039, F-51687, Reims Cedex 2, France. michael.rey@univ-reims.fr.
Abstract:
A detailed study of methane spectra in the highly congested icosad range of 6280-7800 cm(-1) has been performed using global variational calculations derived from accurate ab initio potential energy and dipole moment surfaces. About 13,000 (12)CH4 lines of the WKLMC line lists recorded at 80 and 296 K using very sensitive laser techniques (DAS, CRDS) have been rovibrationally assigned from first principles predictions. Overall, a total of 7436 upper energy levels were determined. Among the 20 bands and the 134 sub-levels contained in the icosad system, 20 and 108 have been identified for the first time, respectively. The assigned transitions represent 98% of the sum of the experimental intensity at 80 K. This work demonstrates for the first time how accurate first principles global calculations allow assigning complicated spectra of a molecule with more than 4 atoms.
More Related Videos
08:54Vibrational Spectra of a N719-Chromophore/Titania Interface from Empirical-Potential Molecular-Dynamics Simulation, Solvated by a Room Temperature Ionic Liquid
Published on: January 25, 2020
08:49Author Spotlight: Unveiling the Potential of VSFG Microscopy in Studying Mesoscopically Heterogeneous Self-Assembled Structures
Published on: December 1, 2023
Related Concept Videos
IR Spectroscopy: Molecular Vibration Overview
Stretching vibrations are vibrational motions that occur along the bond line, changing the bond length or distance between two bonded atoms. They are further distinguished as symmetric or asymmetric. In symmetric stretching, the...
UV–Vis Spectroscopy: Molecular Electronic Transitions
Mass Spectrum
¹H NMR of Conformationally Flexible Molecules: Temporal Resolution
IR Frequency Region: X–H Stretching
IR Spectroscopy: Hooke's Law Approximation of Molecular Vibration
According to Hooke's law, the vibrational frequency is directly proportional to...