One-photon mass-analyzed threshold ionization spectroscopy (MATI) of cis-dichloroethylene (cis-C2H2Cl2): Cation structure determination via Franck–Condon fit

A high-quality one-photon mass-analyzed threshold ionization (MATI) spectrum of cis-C2H2Cl2 was obtained by using vacuum ultraviolet radiation generated by four-wave mixing in Kr. The ionization energy determined from the position of the 0–0 band in the spectrum was 9.6578 ± 0.0006 eV. Ten vibrational fundamentals for the cation were identified. Most of the overtones and combinations could be assigned properly by comparing with the quantum chemical calculation results. The equilibrium geometry of the cation was determined through Franck–Condon fit.