IUPAC - vibrational term value (08709)

vibrational term value

symbol:

G

, units:

m^{- 1}

{cm}^{- 1}

https://doi.org/10.1351/goldbook.08709

Vibrational energy, $E$ , expressed in wavenumber units. $G = E / (h c)$ , 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: $G = ω_{e} (ν + 1 / 2) - ω_{e} x_{e} (ν + 1 / 2)^{2} + ω_{e} y_{e} (ν + 1 / 2)^{3} + h i g h e r o r d e r t e r m s,$ and for a polyatomic molecule $G = \sum_{k} ω_{k} (ν_{k} + g_{k} / 2) + \sum_{i \leq j} X_{i j} (ν_{i} + g_{i} / 2) (ν_{j} + g_{j} / 2) + h i g h e r o r d e r t e r m s,$ where $ν$ , $ν_{k}$ , etc. = 0, 1, 2, 3,··· , and $g$ is the degeneracy of a vibration. $X_{i j}$ are the anharmonic constants.
SI unit: $m^{- 1}$ . Common unit: ${cm}^{- 1}$ .

Source:
PAC, 2021, 93, 647. (Glossary of methods and terms used in analytical spectroscopy (IUPAC Recommendations 2019)) on page 769 [Terms] [Paper]

Citation: 'vibrational term value' in IUPAC Compendium of Chemical Terminology, 5th ed. International Union of Pure and Applied Chemistry; 2025. Online version 5.0.0, 2025. https://doi.org/10.1351/goldbook.08709 RIS BibTex EndNote

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vibrational term value