Mass analyzed threshold ionization spectroscopy of 4-aminobenzonitrile cation Original Research Article

Mass analyzed threshold ionization (MATI) and two-color resonant two-photon ionization (R2PI) methods were used to investigate the ionic properties of 4-aminobenzonitrile (4-ABN). The adiabatic ionization energy of this molecule was determined to be 66 493±4 cm−1 by the MATI spectroscopy and 66 494±7 cm−1 by the two-color R2PI spectroscopy. The active vibrations of the 4-ABN cation include the in-plane ring deformation, CC stretching, C–CN stretching, and CH bending motions. The present experimental results are well supported by our ab initio and density functional theory calculations.