Vibrational spectrum of vinyl bromide cation in the ground electronic state was obtained by one-photon mass-analyzed threshold ionization (MATI) spectroscopy using coherent vacuum ultraviolet radiation generated by four-wave difference frequency mixing in Kr. From MATI spectrum, ionization energy to the ground state of the cation was determined to be 9.8171+/-0.0006 eV (79 180+/-5 cm-1). Almost complete vibrational assignments for the peaks in the MATI spectrum were possible by utilizing vibrational frequencies and Franck-Condon factors calculated at the Becke three parameter Lee-Yang-Parr (B3LYP)/6-311++G(df,pd) level. Franck-Condon analysis for one-photon MATI spectra is especially useful because calculations of only the ground electronic states are involved while that for two-photon MATI spectra requires excited state calculations. (C) 2003 American Institute of Physics.