Vibrational Structure of the (2)1Σ+u–X(1)1Σ+gTransition of the Ba2Molecule

Abstract Resonant two photon ionization (R2PI) technique was used to obtain the excitation spectrum of the Ba 2 molecule. A group of 12 vibrational bands was found in the 740–764 nm region. As a result of mass selective detection, they were attributed unambiguously to the Ba 2 molecule. By comparison to recent theoretical calculations, those bands were assigned to the (2) 1 Σ + u – X (1) 1 Σ + g transition; they may be fitted to give the following vibrational constants (in cm −1 ): ω″ e = 33.2 ± 0.2, ω″ e x ″ e = 0.5 ± 0.2, ω e = 65.2 ± 0.2, and ω′ e x ′ e = 0.4 ± 0.2.