Collision Energy Resolved Penning Ionization Spectroscopy for Cyclic Ethers with He*(23S)

Masayo Yamauchi, Kohji Okamura, Hideo Yamakado, and Koichi Ohno
(Faculty of Science, Tohoku University; College of Arts and Sciences, University of Tokyo)

State-resolved collision-energy dependence of Penning ionization cross sections σ(E) was measured for tetrahydropyran,1,4-dioxane,tetrahydrofuran with He*(23S) by detecting energy-analyzed electrons as functions of time-of-flight of He*. The partial ionization cross sections for ionic states of which corresponding molecular orbitals have nonbonding-oxygen character show negative dependence on collision energy, and this suggests attractive interaction potential surface. On the other hand, CH-bonding character is related to repulsive potential. This feature of σ(E) is common for all of these cyclic ethers as well as chain compounds. On the basis of this knowledge, we discussed the assignment of UPS spectra and anisotropy of interaction potentials of He* and target molecules.