The intensities of vibrational transitions in photoelectron spectra are typically governed by Franck-Condon factors. In the absence of vibronic coupling, this means that starting from the anion ground vibrational state, one only observes progressions in totally symmetric vibrational modes for which there is a normal coordinate displacement upon photodetachment. For symmetry reasons, there is no such displacement for non-totally symmetric modes, and while CH, NH, and OH stretches in molecules can be totally symmetric, changes in the corresponding bond lengths upon anion photodetachment are generally very small. Hence, the situation on the left side of Figure holds, in which transition intensities from the anion ground state to the 𝑣 = 1 level of a non-totally symmetric mode or a mode in which there is no normal coordinate displacement are either zero by symmetry or negligibly small.