Abstract
Infrared fluorescence of Rb2 in the region 6800-8000 cm-1, arising when the levels of the C 1Π u state are pumped by the 472·7, 476·5, 488·0 and 496·5 nm lines of an argon-ion laser, has been recorded by Fourier transform spectrometry. The fluoresence is assigned to the system C 1Π u → 2 1Σ+ g . The 2 1Σ+ g state energy levels up to v = 24 have been determined. The main spectroscopic constants for this 2 1Σ+ g state are The unusual spacing of the vibrational levels reflects the ionic character of the 2 1Σ+ g state.