Vibrational energy,
\(E\), expressed in
wavenumber units.
\(G = E/(hc)\), where
\(h\) is the Planck constant and
\(c\) is the speed of light in vacuum.
Notes: - \(G\) is usually written with zero-energy at the minimum of the potential energy curve for a diatomic molecule as: \[G = \omega_{\rm{e}}(\nu +1/2) - \omega_{\rm{e}} x_{\rm{e}}(\nu +1/2)^{2} + \omega_{\rm{e}} y_{\rm{e}}(\nu + 1/2)^{3} + higher\ order\ terms,\] and for a polyatomic molecule \[G = \sum_{k} \omega_{k}(\nu_{k} + g_{k}/2) + \sum_{i\le j} X_{ij}(\nu_{i} + g_{i}/2)(\nu_{j} + g_{j}/2) + higher\ order\ terms,\] where \(\nu\), \(\nu_{k}\), etc. = 0, 1, 2, 3,ยทยทยท , and \(g\) is the degeneracy of a vibration. \(X_{ij}\) are the anharmonic constants.
- SI unit: \(\pu{m-1}\). Common unit: \(\pu{cm-1}\).
Source:
PAC, 2021, 93, 647. 'Glossary of methods and terms used in analytical spectroscopy (IUPAC Recommendations 2019)' on page 769 (https://doi.org/10.1515/pac-2019-0203)