Combined Experimental and Theoretical Study on Photoionization Cross Sections of Benzonitrile and o/m/p-Cyanotoluene

Toluene is one of the most abundant aromatic compounds in the atmosphere of Titan, and CN group has been regarded as an indicator for observing aromatic compounds in interstellar medium due to the large dipole moments resulted from the CN substituents. In the present work, the photoionization cross-sections (PICS) of benzonitrile and o/m/p-cyanotoluene, which are the products of CN + toluene were obtained at the photon energy ranging from ionization threshold to 14 eV combining experimental and theoretical methods. The synchrotron vacuum ultraviolet photoionization mass spectrometry (SVUV-PIMS) was employed, and theoretical calculations based on the frozen-core Hartree-Fock approximation and Franck-Condon simulations were carried out to cross-verify the measurements. In addition, the generalized charge decomposition analysis was used to investigate the characteristics of ionized molecular orbitals. Our results are valuable for quantifying these key species (especially by the SVUV-PIMS technique) and estimating related parameters such as dissociation rates in interstellar space.