GROUP ADDITIVITY FOR THE BAND STRENGTH OF THE CF-CHROMOPHORE FOR IR-PHOTOCHEMISTRY.

Article abstract of DOI:10.1002/bbpc.19830870709

Integrated band strengths for rovibrational absorption in the frequency range of the CF-chromophore (800 to 1300 cm** minus **1) have been obtained from vapor phase IR-spectra of twelve fluoroalkanes containing one or more CF groups. It is found that the chromophore band strength is about 1. 7 (pm)**2 for each CF group with some minor variations due to neighboring substituents at the CF carbon atom. These variations can be accounted for by a simple, empirical equation. The results are discussed in relation to the chromophore principle in IR-photochemistry. The frequency distribution of the chromophore absorption for primary, secondary, and tertiary alkyl fluorides is considered. The primary CF-chromophore (R-CH//2-F) is suggested to be a particularly useful general chromophore for CO//2-laser pumping. The foundations of the group additivity for chromophore band strengths and some further applications are discussed as well.