Optical-optical double resonance and Fourier transform spectroscopy: The Rb 2 B 1Πu electronic state up to the quasibound energy levels

Abstract

Nearly all quasibound vibrational energy levels of the Rb 2 B 1Π u state were accessed via a double resonance excitation scheme. A resonant excitation process, X 1 Σ g + → A 1 Σ u + → (2) 1 Π g has been used to populate single ro-vibrational levels of the upper (2) 1Π g state. Spectra of the (2) 1 Π g → B 1 Π u infrared fluorescence were recorded by high resolution Fourier transform spectroscopy. Taking account of previously studied B 1 Π u → X 1 Σ g + fluorescence spectra led to accurate effective molecular constant for the B 1Π u state. The line broadening due to the tunneling effect was observed for the uppermost vibrational levels. The barrier height was found to be /2~ 205 cm −1 above its asymptotic limit ( 5S 1 2 + 5P 3 2 ) at 9.14Å.