These results can be explained through consideration of the selection rules for molecular photodetachment. Photodetachment to the NO3 ground state involves removal of an electron from an a2' molecular orbital and can occur by p-wave but not s-wave detachment. Hence, near threshold, p-wave detachment is the lowest allowed partial wave for the vibrational origin and all Franck-Condon allowed transitions. Peak B, the 4 0 1 transition, is allowed only through vibronic coupling to the higher lying 2 BE  state, and photodetachment to the 2 BE  state, in which an e' electron is removed, can occur via s-wave detachment. Since the vibronic wavefunction for the 4=1 level of the 2 2 XA  state is mixed with the ground vibrational level (or other totally symmetric vibrational levels) of the 2 BE  state, the 4 0 1 transition can occur via s-wave detachment. These considerations explain the experimental result that the intensity of peak A drops off more rapidly than that of peak B as the eKE is lowered, and lead to the somewhat counterintuitive result that at low eKE, the cryo-SEVI spectrum is dominated by vibronically allowed rather than FC allowed transitions.