Emission and absorption spectra of 2,3,4-, 2,3,5- and 2,4,5-trifluorobenzaldehyde vapors

Emission and absorption spectra have been measured for 2,3,4-, 2,3,5- and 2,4,5-trifluorobenzaldehyde vapors at different temperatures along with the Raman spectra of the pure samples. The observed emission is shown to consist of the T1(n, π∗) phosphorescence accompanied by the weak S1(n. π∗) delayed fluorescence for all the molecules. The vibrational analyses of the fluorescence and phosphorescence spectra based on the results of the DFT calculation at the B3LYP/6-311+G(p,d) level indicate that the observed emission and absorption originates from only the stable conformer (anti). The measured Raman spectra also agreed well with those calculated for the stable (anti) conformer.