CORE-EXCITATION IN MOLECULES - FORMATION OF CATIONS AND ANIONS

The formation of positively and negatively charged ions is reported fo r core-excited carbon dioxide (CO2) and nitrous oxide (N2O) in the sof t X-ray regime using monochromatized synchrotron radiation. These mole cules are investigated in the energy regimes of the C(1s)- and N(1s)-a bsorption edges. It is found that the shape of photoion yield spectra of mass selected cations depends strongly on the dominating fragmentat ion mechanism which leads to the product ion. Anion formation is ident ified as a primary process in the core ionization regime. Both CO2 and N2O decay exclusively into the anion channel O-, predominantly upon 1 s-->pi-excitation. The formation mechanisms of cations and anions in core-excited molecules are discussed.