THEORETICAL STUDIES OF THE VALENCE ELECTRONIC STATES AND THE 1PIU]-X1SIGMA+G ABSORPTION-SPECTRUM OF THE F2 MOLECULE

The twelve electronic states of F2 dissociating into ground state F(2P) atoms have been investigated with ab initio polarization configuration interaction wave functions. Using a [3s2pld] contracted Gaussian basis, the theoretical spectroscopic constants (with experimental values in parentheses) for the 1Σg+ ground state are: Re = 1.427 Å(1.412 Å), De = 1.85 eV(1.66 eV), ωe= 946 cm-1 (924 cm-1), and ωexe, = - 10.6 cm-1 ( - 22.2 cm -1). The 3Πu state is also found to be very weakly bound (Re = 1.881 Å, De =0.15 eV), while the remaining nine electronic states are strictly repulsive (aside from van der Waals minima). Molecular properties are reported for the 1Σ g+ state and a detailed analysis of the 1Πu← 1Σg+ absorption is carried out. The 3Πu state appears to be the lower state in the 157 nm laser emission observed recently, which would correspond to the 23Πg→13Π u electronic transition. © 1979 American Institute of Physics.