Two-color two-photon REMPI and ZEKE photoelectron spectroscopy of jet-cooled 2-chloropyrimidine

We report studies of supersonically cooled 2-chloropyrimidine (2-ClP) using two-color resonantly enhanced multiphoton ionization (REMPI) and two-color zero kinetic energy (ZEKE) photoelectron spectroscopy. With the aid of ab initio and density functional calculations, vibrational modes of the first electronically excited state (S1) of the neutral species and those of the ground state cation (D0) have been assigned, and the adiabatic ionization potential has been determined to be 77 106 ± 4 cm−1 (9.5600 ± 0.0005 eV). These results will be discussed in comparison with pyrimidine and other related compounds. Although the rate of intersystem crossing is affected by halosubstitution, 2-ClP and pyrimidine have qualitatively similar photophysical behaviors.