High-resolution threshold photoelectron spectroscopy of molecular fluorine

Abstract

The threshold photoelectron spectrum of molecular fluorine has been recorded in the 5.6–21.9 eV photon energy range, at resolutions ranging from 3 to 12 meV, using synchrotron radiation and a penetrating-field electron spectrometer. In addition to observing the three known band systems of F 2 + at higher resolution than previously achieved with conventional photoelectron spectroscopy, extensive vibrational structure is found in the Franck-Condon gaps between the main electronic systems of F 2 +. This extended vibrational structure is attributed to resonance autoionization of neutral Rydberg states.