Adsorption mode of the chiral modifier cinchonidine on Au(1 1 1)

The adsorption of the chiral modifier cinchonidine on Au(l 1 1) in UHV has been studied by means of TPD, LEED and XPS. In the monolayer the molecule is bound via nitrogen lone pair electrons of its quinoline part rather than via the π-system of this aromatic moiety. Intact molecular desorption is only observed for the multilayers. Decomposition in the first monolayer upon heating occurs above 400 K, indicating a stronger interaction in the monolayer. No long-range ordered structures were observed via LEED. Long-time exposure leads to rearrangement and further stabilization of the first molecular monolayer. Quinoline is bound to gold via the nitrogen lone pair as well. The binding energy of 9.6 kcal/mol is characteristic for physisorption.