Division of Synchrotron Radiation Research, Department of Physics, Lund University, Box 118, 221 00 Lund, Sweden.
Langmuir. 2011 Sep 20;27(18):11466-74. doi: 10.1021/la201923y. Epub 2011 Aug 22.
Using X-ray photoelectron spectroscopy we studied the coadsorption of the amino acid L-cysteine and gold on a rutile TiO(2)(110) surface under ultrahigh vacuum conditions. Irrespective of the deposition order, i.e., irrespective of whether L-cysteine or gold is deposited first, the primary interaction between L-cysteine and the gold clusters formed at the surface takes place through the deprotonated thiol group of the molecule. The deposition order, however, has a profound influence on the size of the gold clusters as well as their location on the surface. If L-cysteine is deposited first the clusters are smaller by a factor two to three compared to gold deposited onto the pristine TiO(2)(110) surface and then covered by L-cysteine. Further, in the former case the clusters cover the molecules and thus form the outermost layer of the sample. We also find that above a minimum gold cluster size the gold cluster/L-cysteine bond is stronger than the L-cysteine/surface bridging oxygen vacancy bond, which, in turn, is stronger than the gold cluster/vacancy bond.
使用 X 射线光电子能谱，我们在超高真空条件下研究了氨基酸 L-半胱氨酸和金在金红石 TiO(2)(110)表面上的共吸附。无论沉积顺序如何，即无论 L-半胱氨酸还是金首先沉积，L-半胱氨酸与表面形成的金簇之间的主要相互作用都是通过分子的去质子化硫醇基团进行的。然而，沉积顺序对金簇的大小及其在表面上的位置有深远的影响。如果 L-半胱氨酸首先沉积，则与金沉积在原始 TiO(2)(110)表面上然后被 L-半胱氨酸覆盖的金簇相比，金簇小了两到三倍。此外，在前一种情况下，簇覆盖分子，从而形成样品的最外层。我们还发现，在最小金簇尺寸以上，金簇/L-半胱氨酸键比 L-半胱氨酸/表面桥连氧空位键强，而后者又比金簇/空位键强。
