High-Resolution STM Imaging and Molecular Modeling
(Result of the month 10/2008)

Organic nanostructures on semiconductors are currently investigated but the surfaces are known to interact strongly with molecules. To reduce the molecule-surface interaction, we used the Si(111)-B √3 x √3R30°. Deposition of isolated 2; 4; 6-tri(2'-thienyl)-1; 3; 5-triazine, was achieved at room temperature without modification of their _ skeleton. This fascinating arrangement, observed by STM, has been validated by full density functional theory computations onto the entire system. The theoretical results give a clear explanation for the specific adsorption sites of molecules on the substrate.

High-resolution STM images of the Si-B surface before (top) and after (bottom) deposition of 2; 4; 6-tri(2'-thienyl)-1; 3; 5-triazine molecules (Vs =1.0 V, It = 0,4 nA, 20 nm x 20 nm).

STM image (empty states) showing two 2; 4; 6-tri(2'-thienyl)-1; 3; 5-triazine molecules adsorbed on the Si-B substrate (Vs = 1.2 V, It = 0.3 nA, 14 nm x 9 nm).

Same STM image (empty states) with two linear (left) and high contrasted multicolor (right) look-up tables showing one 2; 4; 6-tri(2'-thienyl_-1; 3; 5-triazine molecule adsorbed on the Si-B surface. (Vs = 1.2 V, It = 0.3 nA, 7 nm x 6 nm).