Experimental studies of the absorption spectrum of the ${\mathrm{Rb}}_2$ dimer are performed in the $600–1100\mathrm{nm}$ wavelength range for temperatures between 615 and $745\mathrm{K}$. The reduced absorption coefficient is measured by spatially resolved white light absorption in overheated rubidium vapor with a radial temperature gradient, which enables simultaneous measurements at different temperatures. Semiclassical and quantum spectral simulations are obtained by taking into account all possible transitions involving the potential curves stemming from the 5 ${}^{2}S+5$ ${}^{2}S$ and 5 ${}^{2}S+5$ ${}^{2}P$ asymptotes. The most accurate experimental potential curves are used where available, and newly calculated potential curves and transition dipole moments otherwise. The overall consistency of the theoretical model with the experimental interpretation is obtained only if the radial dependence of both the calculated transition dipole moments and the spin-orbit coupling is taken into account. This highlights the low-resolution absorption spectroscopy as a valuable tool for checking the accuracy of molecular electronic structure calculations.

For pt.I see ibid., vol.10, no.3, p.2631 (1977). Calculates the oscillator strengths from the ground level to the first excited states of the long-range alkali homonuclear dimers. Using the known resonance interaction potential curves and these oscillator strengths the authors calculated the quasi-static wing profiles of the self-broadened first resonance alkali lines.