Ab initio calculations and Franck-Condon analysis of photoelectron spectra of PO2-

Geometry optimization and harmonic vibrational frequency calculations have been performed on the X˜2A1 state of PO2 radicals and X˜1A1 state of PO2- anions. Franck-Condon analysis and spectral simulations were carried out on the PO2(X2A1)-PO2-(X1A1) photodetachment process. The theoretical spectra obtained by using CCSD/6-311+G(2p, d) values are in agreement with the observed one. In addition, the equilibrium geometry parameters, r(PO) = 1.504 ± 0.005 Å and ∠(OPO) = 119.0 ± 0.2°, of the X˜1A1 state of PO2- are derived by employing an iterative Franck-Condon analysis procedure in the spectral simulation. Furthermore, through the different methods, our best calculated electron affinity is 78.80 cal mol−1, which is in excellent agreement with the experimental value and other theoretical values.