Band Spectra and Energy of Dissociation of the Rubidium Molecule

Measurements and vibrational analysis of the violet and blue band systems of ${\mathrm{Rb}}_2$ have been made in absorption. Quantum numbers have been assigned to 118 and 160 bands in the two systems, respectively. The upper vibrational frequency of the violet system is 40.42 ${\mathrm{cm}}^{-1\mathrm{}}$ and that of the blue one, 36.46 ${\mathrm{cm}}^{-1\mathrm{}}$. The lower level, common to the two systems, is ${}_{}{}^1{}_{}{}^{}\Sigma$ ground state, and its vibrational frequency is found to be 57.45 ${\mathrm{cm}}^{-1\mathrm{}}$. The energies of dissociation of the three states of the molecule have been determined by means of extrapolation, and the value for the ground state is 0.49 ± 0.02 volt. A green edge of the blue system at 5032A has been observed.