Origin of Resonant Raman Excitation Profiles Red-Shifted from Optical Absorption Profiles

Abstract

We observe that the Raman excitation profile in matrix-isolated ${\mathrm{Br}}_2$ is significantly red-shifted from the absorption maximum and show that a straightforward relationship between the two can in general not be expected. A simple theory considering only the resonant contributions describes our data reasonably well. In addition, we discuss the effect on our results of interference between the $B$ and ${}_{}{}^1{}_{}{}^{}\Pi _{1\mathrm{u}}^{}{}_{}{}^{}$ states.