IUVSTA 15th International Vacuum Congress (IVC-15), AVS 48th International Symposium (AVS-48), 11th International Conference on Solid Surfaces (ICSS-11)
    Surface Science Thursday Sessions
       Session SS3-ThP

Paper SS3-ThP3
Multi-directional N@sub 2@ Desorption in Thermal Dissociation of N@sub 2@O on Pd(110) and Rh(110) at Low Temperatures

Thursday, November 1, 2001, 5:30 pm, Room 134/135

Session: Surface Reactions Poster Session
Presenter: H. Horino, Environ. Earth Sci. Hokkaido University, Japan
Authors: H. Horino, Environ. Earth Sci. Hokkaido University, Japan
T. Matsushima, CRC, Hokkaido University, Japan
Correspondent: Click to Email
Multi-directional N@sub 2@ desorption was found in N@sub 2@O dissociation on Pd(110) and Rh(110) below 170 K by angle-resolved TDS. N@sub 2@ desorption sharply collimates off the surface normal in the (001) plane. Hot-atom-assisted N@sub 2@ desorption is proposed in aligned N@sub 2@O(a) dissociation. N@sub 2@O(a) is mostly dissociated during heating procedures, emitting N@sub 2@(g) and leaving O(a). N@sub 2@ showed four desorption peaks. Pd(110);@beta@@sub 1@-N@sub 2@ peaks around 150 K, @beta@@sub 2@-N@sub 2@ 134 K, @beta@@sub 3@-N@sub 2@ 123 K, and @beta@@sub 4@-N@sub 2@ 110 K. @beta@@sub 4@-N@sub 2@ was clearly seen at low N@sub 2@O exposures. It sharply collimated at ±50° off the surface normal. @beta@@sub 3@-N@sub 2@ was significant and revealed inclined sharp emission centered at ±43° off the surface normal. A similar distribution was also found with @beta@@sub 1@-N@sub 2@ found at high N@sub 2@O exposures, whereas @beta@@sub 2@-N@sub 2@ showed a cosine distribution. The preference of each N@sub 2@ peak was sensitive to pre-adsorbed O(a). Rh(110);@beta@@sub 1@-N@sub 2@ peaks at 165K, @beta@@sub 2@-N@sub 2@ 140 K, @beta@@sub 3@-N@sub 2@ 120 K and @beta@@sub 4@-N@sub 2@ 110 K. @beta@@sub 3@-N@sub 2@ and @beta@@sub 4@-N@sub 2@ collimated at @theta@=±33° and ±75°, respectively. These were seen at small exposures. @beta@@sub 1@-N@sub 2@ showed a cosine distribution. @beta@@sub 2@-N@sub 2@ desorption collimated at @theta@=±30°. Sharp inclined desorption possesses high kinetic energy. Prior to dissociation, N@sub 2@O(a) must lie on the surface. For inclined desorption, a surface parallel momentum must be transferred from nascent hot oxygen atoms to desorbing N@sub 2@. Larger inclined angles and higher kinetic energy may be expected on Rh(110) because higher hot-atom energy comes from the stronger metal-O bonding.