THRESHOLD PHOTOELECTRON-SPECTRA OF ATMOSPHERIC MOLECULES .1. DESCRIPTION OF METHOD AND APPLICATION TO H-2, D2, AND N2

Threshold photoelectron spectra (TPES) are presented for H2, D2, and N2 with a resolution of 28 meV full width at half maximum. The results are compared with Franck-Condon transition probabilities, previous TPES and electron attachment threshold photoelectron spectra. Peaks in the TPES not predicted by Franck-Condon calculations are explained by autoionization processes. These processes in N2 make possible the observation of vibrational levels of the ions not visible spectroscopically or in photoelectron spectra. Peaks between the v = 0 and v = 1 vibrational levels of the X 2Σg+state of N2+ consist of near monoenergetic electrons implying little or no change in the rotational quantum number in the autoionization process. © 1979 American Institute of Physics.