Electronic transitions of Rb2 above 25 000 cm−1

Rubidium dimers were formed by thermal vaporization of the metal followed by continuous co-expansion with argon through a small pinhole into a vacuum chamber. The dimers were detected by laser-induced fluorescence. Vibrationally resolved excitation spectra were recorded for two new band systems in the wavelength regions around 394 nm and 353 nm. The well known D-X system near 430 nm was also observed. All three band systems exhibited long vibrational progressions, indicative of substantial changes in the equilibrium bond lengths on electronic excitation. Isotope splittings between the bands of 85Rb2 and 85Rb87Rb were resolved for the band system centered at 353 nm. Vibrational analyses were carried out, and the upper state vibrational constants are reported. Possible assignments of the electronic configurations for the newly observed states are considered.

Band system of Rb2 near 25000 cm−1 showing a perturbation centered near v = 7.Highlights► New electronic band systems for Rb2 found near 394 and 353 nm. ► Homogeneous perturbation of the 394 nm band observed near v′ = 7. ► Predissociation of the 353 nm band detected. Emission from Rb(6p) observed.