Probing the Chemistry of Reactive Molecules with Synchrotron Radiation

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In this project we will employ synchrotron radiation (SR) in the vacuum-ultraviolet and soft X-ray regime to probe the chemistry of reactive molecules. This includes (a) unimolecular reactions like dissociative photoionization, (b) bimolecular reactions of open-shell species with stable molecules, and (c) reactions that lead to the formation of hitherto unexplored molecules. We will focus on species and reactions that are of interest in combustion, interstellar and atmospheric chemistry, but also on boron-containing molecules of fundamental interest in inorganic chemistry. Measurements will be conducted at the storage rings Swiss Light Source (SLS) at the Paul Scherrer Institute (Villigen/CH) and the Synchrotron SOLEIL in St. Aubin/Paris. The experiments will rely on the detection of ions and electrons. For data analysis and interpretation we will continue to cooperate with theory groups.In addition to pyrolysis, i.e. thermal radical generation we will employ a new photolysis flow reactor setup available at the SLS. It permits to produce radicals in bimolecular reactions that are not easily accessible by thermal processes, for example oxyradicals. Furthermore this reactor permits to investigate the kinetics of radical/molecule reactions and to determine reaction rates. We will start with the reaction of allyl, C3H5 + O2 and then proceed to other hydrocarbon radicals and carbenes. We will also expand our research program to the soft X-ray regime and explore the fragmentation dynamics after excitation of core electrons in isocyanic acid, HNCO. This molecule contains the major atoms of organic molecules and combines the advantages of a small few-atom molecule with a considerable degree of complexity. As a first step we will record resonant Auger-spectra of HNCO and in the next step study the site-selectivity of fragmentation upon excitation of the various resonances. The VUV photoionization and dissociative photoionization of reactive molecules will continue to be an important part of our research. We will determine the ionization energies of reactive molecules and the appearance energies AE0K of relevant dissociative photoionization channels. We will focus on species with heteroatoms, for example the isomers of picolyl, C6H6N. Furthermore we are interested in boron-containing molecules like BH3 and B2Hx. For generating boron compounds, we will employ a discharge flow reactor available at Soleil in addition to pyrolysis and photolysis sources.