Electron spectroscopy using excited atoms and photons V. Penning ionization of water,alcohols and ethers

The Penning electron spectra of water, methanol, ethanol, isopropyl alcohol, tertiary butyl alcohol, dimethyl ether, ethylene oxide, diethyl ether, tetrahydrofuran and 1,4 dioxane, obtained using helium metastable atoms (2¹S, 2³S), are compared to their respective photoelectron spectra at 584 Å. An analysis of the Penning electron band shape and the position of the peak maximum for the ground state ions suggest significant changes in the Franck—Condon factors in comparison with photoelectron spectra. This may be ascribed to modifications of the target potential energy curves. It is also observed that the relative populations of the ionic states differ appreciably for Penning ionization and photoionization.