Bi₂Ne: Weakly bound cluster of diatomic bismuth with neon

The A-X transition of diatomic bismuth, Bi₂, was revisited by laser induced fluorescence in solid Ne at 3 K. Molecular constants, i.e., vibrational frequencies of 137 cm^-1 and 174 cm^-1, were reproduced for the upper and lower electronic states as reported by Bondybey et al. [Chem. Phys. Lett. 76, 30 (1980)]. Two-dimensional mapping of emission spectra confirmed satellite bands in higher and lower excitation/emission energies for each of the major bands in the vibrational progression of v′-v″ (v′ = 0-5, v″ = 5-12). Based on the molecular orbital calculations, presence of clusters, Bi₂Ne_n (n = 1-6), is proposed for possible carriers of the observed satellites. For the relatively large matrix shift of ∼67 cm^-1 in solid Ne for the term energy of the A state, the diatomic bismuth is supposed to exist as a linearly coordinated cluster of Bi₂Ne in the matrix.