Berlin 2008 – wissenschaftliches Programm
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CPP: Fachverband Chemische Physik und Polymerphysik
CPP 6: Electronic+Optical Properties
CPP 6.10: Vortrag
Montag, 25. Februar 2008, 16:30–16:45, C 230
Photoinduced Formation of N2 Molecules in Ammonium Compounds — •Emad Flear Aziz1, Johan Grasjo2, Johan Forsberg3, Egil Andersson3, Johan Söderström3, Laurent Duda3, Wenhua Zhang4, Jinglong Yang5, Stefan Eisebitt1, Christel Bergström2, Yi Luo4, Joseph Nordgren3, Wolfgang Eberhardt1, and Jan-Erik Rubensson1 — 1BESSY GmbH, Berlin, Germany — 2Department of Pharmacy, Uppsala UniVersity, Sweden — 3Department of Physics, Uppsala UniVersity, Sweden — 4Theoretical Chemistry, Royal Institute of Technology, Stockholm, Sweden — 5Hefei National Laboratory of Physical Sciences, at the Microscale, UniVersity of Science and Technology of China
Via fluorescence yield (FY) and resonant inelastic scattering spectroscopy in the soft X-ray range we find that soft X-rays induce formation of N2 molecules in solid NH4Cl and in related compounds. The nitrogen molecules form weak bonds in NH4Cl, so that a substantial fraction of the molecules remains in the sample. From measurements of the FY as a function of exposure and temperature, the rates for the photochemical processes are estimated. At elevated temperatures (363 K), several nitrogen atoms are removed from the sample per incoming photon. At lower temperatures (233 K), the rate is reduced to around 0.02 nitrogen atoms for each incoming photon. Virtually all these atoms form N2 molecules which are bound in the sample. The generality and implications of these results are briefly discussed.
Emad F. Aziz, et. al. J. Phys. Chem. A 111, 9662-9669 (2007)