State-selected and state-to-state photoionization study of trichloroethene using the two-color infrared-vacuum ultraviolet scheme

Abstract

By employing the two-color infrared (IR)-vacuum ultraviolet (VUV) laser photoionization (PI) schemes, we have determined the C–H stretching frequencies ν12=3097.7 cm−1 for trichloroethene (CHCl=CCl2) and ν12+=3066 cm−1 for CHCl=CCl2+. On the basis of the IR-VUV-pulsed field ionization-photoelectron (PFI-PE) measurement, the ratio of the state-to-state PI cross section for CHCl=CCl2+(ν12+=1)←CHCl=CCl2(ν12=1) to that for the formation of the ground state ion from the ground state neutral is determined to be 0.24. The VUV-PI efficiency (PIE) spectrum for CHCl=CCl2 and IR-VUV-PIE spectrum for CHCl=CCl2(ν12=1) show that the state-to-state PI cross section for the formation of CHCl=CCl2+ in the ground state from CHCl=CCl2(ν12=1) is ≈0.006 that from CHCl=CCl2 in its ground state. As expected, the IR-VUV-PIE onset for CHCl=CCl2(ν12=1) exhibits less hot-band tailing than the VUV-PIE onset for supersonically cooled CHCl=CCl2. After taking into account the ν12 frequency, the ionization energy values for CHCl=CCl2 determined based on the IR-VUV-PIE and VUV-PFI-PE measurements are found to be in excellent agreement.