Fragmentation dynamics of chlorobenzene and toluene studied by time-of-flight mass spectrometry and coincidence techniques

Full text. X-ray absorption and ultra-violet light probe the geometric and electronic structure of different molecular systems, while time-of-flight mass spectrometry (TOF-MS) with multi-coincidence ion detection (PEPICO and PEPIPICO) provides information on the photo fragmentation dynamics of the initially produced inner-shell state. Auger decay of inner-shell excited and ionized states is an efficient source of multiply charged ions. We wish to study ionic fragmentation following core excitation of a series of aromatic gas phase molecules, using the time-of-flight multi-ion coincidence apparatus. We have a particular interest in the aromatic molecules with donor and acceptor groups attached on the aromatic ring, known as push-pull system. In this work the ionic fragmentation of chlorobenzene (C6H5Cl) and toluene (C6H5CH3) have been measured with tuned synchrotron light and TOF-MS. Our goal is to investigate the fragmentation dynamics of those aromatic molecules aiming to answer the following question: how the both donor and acceptor groups influencing the charge transfer into the aromatic ring and, consequently, their fragmentation dynamics? Spectra of the Partial Ion Yield (PIY) of some channels and their Branching ratios (BR) are also presented. The experiments have been performed using the Spherical Grating Monochromator (SGM) beamline at the National Laboratory of Synchrotron Light (LNLS) in Campinas-SP, Brazil (research proposals D08A-SGM-7250 and 8730)