IR spectroscopy of 2-fluoropyridine–water clusters in the electronic excited states

The IR spectra of hydrogen-bonded clusters of 2-fluoropyridine (2-FP)–water were studied experimentally in a supersonic free jet. These IR spectra of the clusters were observed with the fluorescence detected infrared depletion (FDIR) technique in the OH stretching vibrational region for the electronic ground and excited states. The frequency decrease of the hydrogen-bonded OH stretching vibration of 2-FP–(H2O)1 with electronic excitation is considerably smaller than that observed for phenol–(H2O)1. All the hydrogen-bonded OH stretching vibrations in 2-FP–(H2O)n become lower in the electronic excited state compared with those in the ground state.