Mass-analyzed-threshold-ionization (MATI) spectroscopy of 1,2,3-substituted halogenated benzenes via different intermediate vibrational states in the S 1 state

For the first time, two color resonant mass analyzed threshold ionization (MATI) spectroscopy has been applied in order to investigate the ionic properties of 1,3-dichloro-2-fluoro-benzene (1,3,2-DCFB) and 1,3-difluoro-2-chloro-benzene (1,3,2-DFCB) radical cations in their electronic ground state. The ionic ground state of the different samples has been investigated via different S 1 intermediate states and compared to 1,2,3-trichlorobenzene measured in previous work. Additionally quantum chemical calculations at DFT (density functional theory) and TDDFT (time-dependent density functional theory) level of theory have been performed to support experimental findings. From the MATI spectra the adiabatic ionization energies of 1,3-dichloro-2-fluorobenzene and 1,3-fluoro-2-chlorobenzene could be determined to be 75.242 ± 6 cm −1 and 75.627 ± 6 cm −1 , respectively. Several vibrational modes of both compounds have been assigned by comparison of the experimental and theoretical results.