THE VIBRATIONAL STRUCTURE OF THE NO2 CATION

Zero kinetic energy photoelectron spectroscopy is combined with triple-resonant multiphoton absorption to obtain the first experimental measurement of the fundamental vibrational frequencies of isolated NO2+. Analysis of observed vibrational structure yields values for the quadratic force constants in both normal coordinate space as well as internal symmetry coordinates. Results are compared with recent ab initio calculations of Lee, with excellent agreement between the two. We obtain values for the fundamental frequencies of 1396.8 +/- 1.0, 639.0 +/- 1.0, and 2362.0 +/- 1.0 cm-1 for the symmetric, bending, and asymmetric vibrations, respectively.