On the Use of Resonant Raman Intensities and Bond‐Order Calculations to Refine Molecular Force Fields

Publisher Website
Google Scholar
Abstract
In this paper a theory is presented for calculating the resonant Raman intensities for all 3N‐6 molecular vibrations of a molecule excited by a Π → Π* electronic transition using only the known geometry of the molecule, the force constants (i. e. force field) for the internal coordinates and a molecular orbital calculation of all of the C‐ C and C‐ N bond orders in the ground and excited electronic states. Criteria are presented for the refining of a force field on the basis of observed and calculated resonant Raman intensities. — The method has been applied to 1‐methyl uracil. excited states which occur at 260 nm and 190 nm. The calculated intensities are compared with measured resonant Raman intensities using exciting light at 266 nm, 257 nm, and 212.8 nm. The agreement is satisfactory in that only the observed resonant Raman bands are calculated to have intensity.