A high-resolution photoelectron spectroscopic and computational study of TaX- (X = C, N, O).

We report on the high-resolution photoelectron spectroscopy of diatomic molecules TaX- (X = C, N, O) anions using a cryogenic ion trap combined with the slow electron velocity imaging (cryo-SEVI) method. We determined the electron affinities of TaC, TaN, and TaO to be 2.098(2), 1.576(2), and 1.069(2) eV, respectively. In addition, the electron affinities of TaX molecules were calculated using the CCSD(T) method with the complete basis sets. To interpret the complicated photoelectron spectra, we predicted the excited states of TaX molecules using the MRCI + Q method, accounting for the spin-orbit coupling effects. Several new excited states of these molecules were observed.