The Jahn-Teller and pseudo-Jahn-Teller effects in the anion photoelectron spectroscopy of B3 cluster.

The photodetachment spectroscopy of B3 anion is theoretically studied with the aid of a quantum dynamical approach. The theoretical results are compared with the available experimental photoelectron spectra of B3. Both B3 and B3 possess D-3h symmetry at the equilibrium configuration of their electronic ground state. Distortion of B3 along its degenerate vibrational mode nu(2) splits the degeneracy of its excited <(C)over tilde>E-2' electronic manifold and exhibits (E circle times e)-Jahn-Teller (JT) activity. The components of the JT split potential energy surface form conical intersections, and they can also undergo pseudo-Jahn-Teller (PJT) crossings with the (chi) over tilde (2)A'(1) electronic ground state of B3 via the degenerate nu(2) vibrational mode. The impact of the JT and PIT interactions on the nuclear dynamics of B-3 in its (chi) over tilde (2)A'(1)-2E' electronic states is examined here by establishing a diabatic model Hamiltonian. The parameters of the electronic part of this Hamiltonian are calculated by performing electronic structure calculations and the nuclear dynamics on it is simulated by solving quantum eigenvalue equation. The theoretical results are in good accord with the experimental data.