Spectroscopy of F-2 in Ne matrices

The excited states of free and matrix-isolated F-2 were investigated in the windowless VUV region by absorption and excitation spectroscopy. In emission the f (3) Pi(g)-->a (3) Pi(u) laser band of F-2 at 7.72 eV with a radiative lifetime of 2 ns and a weaker and broader band at 7.47 eV attributed to emission of F-2 aggregates are observed in an Ne matrix independent on excitation energy, The Franck-condon envelope of the charge transfer state C (1) Sigma(u)(+) extends further to the blue by more than 1 eV in Ne (12 to 14 eV) compared to the gas phase due to a blueshift-of the avoided crossing with the Rydberg 3p pi(u)((1) Sigma(u)(+)) state. The H (1) Pi(u) Rydberg state remains unperturbed in the Ne matrix but is blueshifted by 1.24 eV and significantly broadened due to electron-phonon coupling. A previously unreported broad absorption is observed both in the gas phase and in the matrix around 15 eV and is assigned to a strongly perturbed charge transfer state with Sigma symmetry corresponding to F+*(S-1) and F-(S-1) ions in the dissociation limit. This charge transfer state is strongly perturbed in the gas phase by the high density of np pi(u)((1) Sigma(u)(+)) Rydberg states (n greater than or equal to 4) while in Ne matrix it is mixed mainly with the low-lying 4p pi(u)((1) Sigma(u)(+)) state. The analogy of the resulting two separated groups of bands with irregular vibrational progressions to the Cl-2 case is shown. Further np pi(u) and np sigma(u) Rydberg progressions and the repulsive (3) Sigma(u)(+) valence state are treated. The utility of matrix-isolated F-2 for a solid state laser is discussed. (C) 1996 American Institute of Physics.