Mass analyzed threshold ionization spectroscopy of p-cyanophenol cation and the CN substitution effect

The adiabatic ionization energy of p-cyanophenol has been determined to be 72 698 ± 5 cm−1 (9.0134 ± 0.0006 eV) on the basis of mass analyzed threshold ionization (MATI) spectrscopy. Analysis of the newly obtained MATI spectra gives the respective frequencies of 399, 517 and 820 cm−1 for the ring deformation 6a, C–CN bending, and breathing vibrations of the p-cyanophenol cation. Comparing these experimental data with those of phenol leads to a better understanding about the influence of the CN substituent on the ionization energy and molecular vibration.