Electronic emission spectra ofo- andm-fluorobenzaldehyde vapours

Abstract

The high resolutionnπ* electronic emission spectra ofo- andm-fluoro-benzaldehyde vapours in the region 365–560 nm excited in a discharge are reported for the first time. The spectra of both the compounds consist of theA ¹ A″ -X ¹ A′ fluorescence as well as thea ³ A″ -X ¹ A′ phosphorescence bands. In the case ofo-isomer, all the eleven out-of-plane vibrations have been observed in the fluorescence and the phosphorescence, though weakly in the latter, whereas in the case ofm-isomer, only ten have been observed in the fluorescence and nine in the phosphorescence. It is found that the most intense bands in both the fluorescence and the phosphorescence spectra of these molecules belong to the trans-O rotamer.