Rotamers of 2,5-difluorophenol studied using mass-analyzed threshold ionization spectroscopy
Pei-Ying Wu, Sheng-Yuan Tzeng, Ching-Yun Tsai, Wen-Bih Tzeng
Acta Physico-Chimica Sinica, 32, 893-900 (2016)
We applied resonant two-photon ionization (R2PI) and mass-analyzed threshold ionization (MATI) techniques to record the vibronic and cationic spectra of 2,5-difluorophenol. The distinct bands at 36448 and 36743 cm-1 were confirmed as the origins of the S1 ← S0 electronic transition of the cis and trans rotamers, respectively. The corresponding adiabatic ionization energies were found to be 71164 and 71476 cm-1 for these two rotameric species. The observed spectral features mainly result from the in-plane ring deformation and substituent-sensitive bending vibrations. Spectral analysis suggests that the molecular geometry and vibrational coordinates of the cation in the D0 state resemble those of the neutral species in the S1 state for both cis and
trans rotamers.