COLL 252 |
| Soon Jung Jung, Jun Young Lee, and Sehun Kim. Department of Chemistry, KAIST, 373-1 Guseong-dong Yuseong-gu, Daejeon, 305-701, South Korea |
| The adsorption of purine molecule onto the Ge(100)-2x1 surface was investigated using both scanning tunneling microscopy (STM) and the density functional calculation. We find that purine molecules adsorb with very high order and selectivity onto Ge(100) via the formation of Ge-N dative bond through a Lewis acid-base type reaction. Figure 1(a) shows a filled-state STM image (Vs=-2.0 V) of Ge(100) surface after adsorption of 0.01 ML of purine at room temperature. The round shape protrusions are purine molecules resided between the buckled dimer rows. The STM image shows that the adsorption of purine molecule induces a local rearrangement of the Ge(100) surface from a c(4x2) to p(2x2) structure. This STM result indicates that the adsorption of purine on the Ge(100) surface proceeds preferentially via multi Ge-N dative bondings with three N atoms. We also investigated the adsorption structure using density functional calculation with the four-dimer cluster. We find that making three dative bond between N-atoms of purine and down Ge-atoms is the energetically most favored adsorption structure, as shown in figure 1. (b). At the saturation coverage (0.25 ML) (Figure3(a)), the STM image contains only a perfectly ordered array consisting of round shape features. Based on this result we may conclude that purine molecules adsorb on every other dimer via only Ge-N dative linkage and form the c(4x2) structure. In this work, we find that purine molecules form a highly oriented layers on the Ge(100) surface through a Lewis acid-base type reaction. A closely packed monolayer of purine molecules having multifunctional groups (three N atoms) bonded to the surface by the Ge-N bonding may be used for the further subsequent reaction. |
|
Posters: Fundamental Research in Surface and Colloid Chemistry
6:00 PM-8:00 PM, Monday, March 29, 2004 Disneyland -- North Exhibit Hall, Poster
Division of Colloid and Surface Chemistry |
