AVS 51st International Symposium
    Surface Science Monday Sessions
       Session SS1-MoM

Paper SS1-MoM10
Co-Adsorption of Polar Molecules with SF@sub6@ on Ru(0001): Effect on Adsorption Geometry, Ion Yields and Electron-Mediated Chemistry

Monday, November 15, 2004, 11:20 am, Room 210B

Session: Electronic Structure and Excitations
Presenter: D.O. Kusmierek, Rutgers, the State University of New Jersey
Authors: D.O. Kusmierek, Rutgers, the State University of New Jersey
N.S. Faradzhev, Rutgers, the State University of New Jersey
T.E. Madey, Rutgers, the State University of New Jersey
Correspondent: Click to Email
SF@sub6@ is widely used as an electron scavenger for high voltage applications, and is a potent greenhouse gas; the electron-induced reactivity of gaseous and condensed SF@sub6@ is an environmentally important issue. The present work focuses on the effect of polar co-adsorbates H@sub2@O and NH@sub3@ on (1) adsorption geometry of SF@sub6@ on Ru(0001) at 25K, (2) formation and desorption probabilities of ions (F@super+@, F@super-@,) generated by electron stimulated desorption (ESD) of SF@sub6@, passing through condensed overlayers, and (3) chemical reactions activated by low-energy electrons. Electron stimulated desorption ion angular distribution (ESDIAD) and temperature programmed desorption (TPD) reveal predominantly molecular adsorption of SF@sub6@ on Ru(0001) via three F atoms, with the other three pointing away from the surface. Deposition of a polar molecule overlayer leads to changes in both intensities and trajectories of desorbing F@super+@ and F@super-@ ions. Low-energy electron-irradiation of SF@sub6@ films causes a step-wise decomposition of the molecules, and new chemical species are detected for electron-irradiated SF@sub6@ adsorbed on water (ice) surface. Analysis of the angular distributions of F@super+@ and F@super-@ as a function of temperature, co-adsorbate coverage and electron irradiation, in conjunction with TPD data, give insight into the structure of the molecular film, the ESD mechanisms, the ion/molecule scattering processes and the radiation chemistry observed here.