The Franck–Condon region structure dynamics of p-nitrobenzoic acid from resonance Raman spectroscopy

Resonance Raman spectra were obtained for p-nitrobenzoic acid using 266, 252.7, and 228.7 nm excitations. The spectra display overtones of the nominal NO2 symmetric stretch mode ν12 and the nominal NO2 antisymmetric stretch ν8, and their combination bands with other four vibrational modes ν19, ν22, ν17 and ν10. A preliminary resonance Raman intensity analysis was done and the results for p-nitrobenzoic acid were compared with nitrobenzene, p-nitroaniline and p-nitrophenone. The results presented here indicate that the Franck–Condon region structure dynamics of nitroaromatic molecules will be dominated by nitro group when both –NO2 and –COOH or –COCH3 chromophores are coexisted in these kinds of molecules.