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

One-photon mass-analyzed threshold ionization (MATI) spectrum of trans-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 9.6306 +/- 0.0006 eV. Ten vibrational fundamentals for the cation were identified. The spectrum also displayed abundant overtones and combinations, most of which could be assigned adequately by comparing with the quantum chemical results. It was found that channel interaction was not important for this system. The equilibrium geometry of the cation was estimated through the Franck-Condon fit.