Anion photoelectron spectroscopy of small boron nitride clusters:: adiabatic detachment energies and vibrational frequencies of low-lying electronic states in B2N and B3N

Vibrationally resolved photoelectron spectra of B2N- and B3N- at 266 nm are reported. The spectroscopy of B3N was studied experimentally for the first time. The spectra allow us to determine adiabatic detachment energies and vibrational frequencies for several low-lying electronic states of the neutral species. Both ground state anions are shown to have linear geometries. For B2N- transitions to two electronic states of the neutral are observed. The electron affinity of B2N ((X) over tilde(2)Sigma(u)(+)) is 3.098 +/- 0.010 eV. The term energy of the electronically excited state ((A) over tilde(2)Sigma(g)(+)) is 0.785 eV. Transitions to three electronic states of B3N are observed, of which the first two show vibrational structure. The adiabatic detachment energies for these two states are 2.919 eV and 3.062 eV. Preliminary calculations indicate that the photodetachment transition between the electronic ground states of B3N- and B3N is spin-forbidden and therefore not observed in our spectra.