Calculation of Delocalization Contribution to Infrared Intensity

Publisher Website
Google Scholar
Abstract
Infrared intensity may be related to energies and intensities of electronic transitions by using the theory of the vibrational perturbation of electronic transitions and holding the electronic state quantum number fixed. This suggests in particular relating the infrared intensity of an appropriate normal mode to the strong ultraviolet absorption in dye‐like molecules having conjugated π‐electron systems. The perturbation theory is tested by applying it to a displaced hydrogen atom and the hydrogen molecule ion. The results suggest the need for modifying the theory to employ floating orbitals. A floating orbital theory of infrared intensity which still brings in ultraviolet transition energies and moments is then constructed. This theory is next applied to the model compounds H3+, H5+ and H7+ and there is predicted an extraordinarily high delocalization contribution to the intensity for the anti‐symmetric stretch. Values for the dipole derivatives are calculated ranging up to 65 debyes/A.

This publication has 10 references indexed in Scilit: