Adsorption structures of benzene on a Si(5 5 12)-2X1 surface: A combined scanning tunneling microscopy and theoretical study

摘要

In the first ever attempt to study the adsorption of organic molecules on high-index Si surfaces,we investigated the adsorption of benzene on Si(5 5 12)-(2X1) by using variable-low-temperature scanning tunneling microscopy and density-functional theory (DFT) calculations.Several distinct adsorption structures of the benzene molecule were found.In one structure,the benzene molecule binds to two adatoms between the dinners of D3 and D2 units in a tilted butterfly configuration.This structure is produced by the formation of di-sigma bonds with the substrate and of two C=C double bonds in the benzene molecule.In another structure,the molecule adsorbs on honeycomb chains with a low adsorption energy because of strain effects.Our DFT calculations predict that the adsorption energies of benzene are 1.03-1.20 eV on the adatoms and 0.22 eV on the honeycomb chains.