Knowledge Bank

The electronic spectrum of ethyl bromide from 250 to 120 nm is discussed in terms of its relationship to the absorptions observed in the spectrum of methyl bromide. The spin-orbit splitting of the lower Rydberg members is discussed along with the splitting that is expected by the lowering of the symmetry from $C3v$ in methyl bromide (yielding $E3/2$ and $E1/2$ ion states) to $Cs$ in ethyl bromide (yielding and ion states). The expected changes in the selection rules for the Rydberg transitions as a result of the symmetry reduction are used in the assignment of the absorptions observed in the spectrum.