Reactivity and anisotropie interaction of 1,3,5-C6H3F3 and C6F6 with He (23S) atoms: comparison with mono- and di-fluorobenzenes

Two-dimensional (collision-energy/electron-energy-resolved) Penning ionization electron spectroscopy (2DPIES) have been applied to the reaction of 1,3,5-C6H3F3 and C6F6 with metastable He (23S) atoms. Collision energy dependence of the partial ionization cross sections (CEDPICS), which reflects interaction potential energy between the molecule and the He (23S) atom, indicated anisotropic interaction around the molecules. Assignments of the Penning ionization electron spectra and He I ultraviolet photoelectron spectra have been made by the characteristics of the 2D-PIES. Furthermore, substituent effects on the reactivity of molecular orbitals and also on the interactions around the molecules for various fluorobenzenes were investigated. It was found that the reactivity of the molecular orbitals were closely related to the amount of F atomic orbital components in the orbital. Furthermore, an elucidation of the substituent effect on the interaction behaviors around the molecules gives us important insights on the dynamics of the colliding particles.