Rotamers of 3,4-difluorophenol studied by two-color resonant two-photon mass-analyzed threshold ionization spectroscopy

• We report the vibronic and cation spectra of cis and trans 3,4-difluorophenol.
• The electronic excitation and ionization energies are precisely measured.
• The molecular geometry of the cation resembles that in the neutral S1 state.

We applied the resonant two-photon ionization and mass-analyzed threshold ionization techniques to record the vibrational spectra of 3,4-difluorophenol in the first electronically excited and the ionic ground states. The band origins of the S1 ← S0 electronic transition of the cis and trans rotamers are found to be 35,486 ± 2 and 35,704 ± 2 cm−1 and the adiabatic ionization energies are 70,016 ± 5 and 70,203 ± 5 cm−1, respectively. The distinct 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.

Figure optionsDownload as PowerPoint slide