Adsorption of di-L-alanine on Cu(110) investigated with scanning tunneling microscopy

Sub-monolayer growth of a small chiral peptide, di-L-alanine, on Cu(1 1 0) was investigated by variable temperature scanning tunneling microscopy (STM). At low coverage and for temperatures above approximate to-220 K the molecules nucleate along the [(3) over bar 3 2] direction to form short, mainly one-dimensional islands. An increase in coverage leads to the formation of [(3) over bar 3 2]-directed, elongated islands. Images with sub-molecular resolution reveal that the orientation of the molecules within one particular island depends on the deposition temperature. At higher coverage, up to one monolayer, the islands coalesce, giving rise to phase boundaries between domains of opposite orientation. An atomic-scale model for di-L-alanine on Cu(1 1 0) is presented. (C) 2003 Elsevier B.V. All rights reserved.