Communication: State-to-state photoionization and photoelectron study of vanadium methylidyne radical (VCH)Rovibrationally selected and resolved state-to-state photoionization of ethylene using the infrared-vacuum ultraviolet pulsed field ionization-photoelectron method Vacuum ultraviolet laser pulsed field ionization photoelectron study of cis-2-butene By employing the two-color infrared ͑IR͒-vacuum ultraviolet ͑VUV͒ laser photoionization ͑PI͒ schemes, we have determined the C-H stretching frequencies 12 ϭ3097.7 cm Ϫ1 for trichloroethene (CHClvCCl 2 ) and 12 ϩ ϭ3066 cm Ϫ1 for CHClvCCl 2 ϩ . On the basis of the IR-VUV-pulsed field ionization-photoelectron ͑PFI-PE͒ measurement, the ratio of the state-to-state PI cross section for CHClvCCl 2 ϩ ( 12 ϩ ϭ1)←CHClvCCl 2 ( 12 ϭ1) 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 ͑PIE͒ spectrum for CHClvCCl 2 and IR-VUV-PIE spectrum for CHClvCCl 2 ( 12 ϭ1) show that the state-to-state PI cross section for the formation of CHClvCCl 2 ϩ in the ground state from CHClvCCl 2 ( 12 ϭ1) is Ϸ0.006 that from CHClvCCl 2 in its ground state. As expected, the IR-VUV-PIE onset for CHClvCCl 2 ( 12 ϭ1) exhibits less hot-band tailing than the VUV-PIE onset for supersonically cooled CHClvCCl 2 . After taking into account the 12 frequency, the ionization energy values for CHClvCCl 2 determined based on the IR-VUV-PIE and VUV-PFI-PE measurements are found to be in excellent agreement.