On the quest for a molecular vibration whose absolute intensity is described solely by fluctuations of atomic dipoles: Can we find it?

Wagner Eduardo Richter

doi:10.1016/j.saa.2023.122321

On the quest for a molecular vibration whose absolute intensity is described solely by fluctuations of atomic dipoles: Can we find it?

Spectrochim Acta A Mol Biomol Spectrosc. 2023 Apr 15:291:122321. doi: 10.1016/j.saa.2023.122321. Epub 2023 Jan 4.

Author

Wagner Eduardo Richter¹

Affiliation

¹ Department of Chemistry, Federal University of Technology - Paraná, 84.017-220, Ponta Grossa, PR, Brazil. Electronic address: richter@utfpr.edu.br.

PMID: 36621029
DOI: 10.1016/j.saa.2023.122321

Abstract

The conditions for a molecular vibration to be active in the infrared spectrum while its absolute intensity is described solely by fluctuations of atomic dipoles are presented. A quick recipe of features of such a system is presented, to guide the seek for it. If such a system can be found, it will then be proved that population analyses based solely on a point-charge approximation are unrealistic as they cannot properly describe this intensity, a real, measurable, unambiguous property.

Keywords: Atomic charges; Atomic dipoles; IR intensities; Molecular dipole; Out-of-plane vibration.