AVS 49th International Symposium
    Surface Science Wednesday Sessions
       Session SS1-WeA

Paper SS1-WeA6
Adsorption and Radiation Induced Decomposition of SF@sub 6@ on Ru(0001)

Wednesday, November 6, 2002, 3:40 pm, Room C-108

Session: Gas-Surface Dynamics
Presenter: N.S. Faradzhev, Rutgers, The State University of New Jersey
Authors: N.S. Faradzhev, Rutgers, The State University of New Jersey
D.O. Kusmierek, Rutgers, The State University of New Jersey
B.V. Yakshinskiy, Rutgers, The State University of New Jersey
T.E. Madey, Rutgers, The State University of New Jersey
Correspondent: Click to Email
Electron stimulated desorption ion angular distribution (ESDIAD) and temperature programmed desorption (TPD) techniques have been employed to study the adsorption and radiation-induced decomposition of fractional monolayers of octahedrally-coordinated SF@sub 6@ physisorbed on Ru(0001) at 25K. TPD reveals predominantly molecular adsorption of SF@sub 6@, which desorbs from 3 weakly-bound states below 100K. ESDIAD of both F@super +@ and F@super -@ ions at 25K demonstrate "halo-like" patterns, and heating the substrate to ~90K results in formation of hexagonal angular distributions for both ions. ESD of F@super +@ and F@super -@ occurs via different mechanisms but from the same chemical states of molecular SF@sub 6@, which appears to be adsorbed via three F atoms, with the other three pointed away from the surface. At low temperatures, the F atoms have a random azimuthal orientation, while upon annealing, lateral ordering occurs in two complementary domains. Prolonged electron beam exposure leads to dissociation of SF@sub 6@, and formation of SF@sub x@ (x=0 to 5) fragments. F@super -@ ions escape only from undissociated molecular SF@sub 6@, while F@super +@ ions also originate from dissociation fragments; both normal beams and off-normal beams are seen in hexagonal F@super +@ ESDIAD patterns, and intensities vary with electron exposure. Electron exposures >10@super 16@ e/cm@super 2@ result in complete decomposition of SF@sub 6@, as verified by TPD and ESDIAD.