VIBRATIONAL AND ELECTRONIC ABSORPTION-SPECTRA OF SOME DIFLUOROBENZALDEHYDES

The electronic absorption spectra of 2,3-, 2,4-, 2,5-and 3,4-difluorobenzaldehydes in the UV region in vapour phase have been recorded on medium quartz and Hilger large quartz spectrographs and on a Hitachi model U-3200 UV/VIS ratio recording spectrophotometer. All the molecules investigated have exhibited, two, pi* <-- pi-band systems corresponding to 1B2u <-- 1A1g (lambda-2600 angstrom) and 1B1u <-- 1A1g (lambda-2100 angstrom) systems of benzene. The infrared and laser Raman spectra of all the molecules studied have also been recorded and analysed. These vibrational spectral data have been taken to help to analyse the UV spectra of the molecules studied.