Laser induced, dispersed fluorescence spectroscopy, and ab initio calculations of p-cyanophenol

Abstract

The electronic origin of p-cyanophenol has been assigned to the strongest transition in the jet cooled vibronic spectrum at 35547.5 cm⁻¹. Vibrations of the electronic ground state have been measured by means of dispersed fluorescence and those of the first electronically excited state by laser induced fluorescence. An assignment of the S₀ state vibrations is presented based upon ab initio calculations at the MP2 and DFT level of theory. Additional CASSCF calculations are presented for both electronic states. The vibronic activity of several low frequency modes points towards a substantial change in geometry of the cyano group upon excitation.