Rotamers of m-cresol cation studied by mass-analyzed threshold ionization spectroscopy

We have applied two-color resonant two-photon mass-analyzed threshold ionization technique to record the vibrational spectra of the selected rotamers of m-cresol. The adiabatic ionization energies of cis and trans m-cresol are determined to be 66,933 ± 5 and 67,084 ± 5 cm−1, respectively. Frequencies of the in-plane ring vibrations 6a, 1, and 9b are measured to be 528, 720, 1167 cm−1 for the cis and 520, 698, and 1153 cm−1 for the trans m-cresol cation. This indicates that different orientation of the OH group with respect to the CH3 group slightly influences these ring vibrations.