The role of reconstruction in self-assembly of alkylthiolate monolayers on coinage metal surfaces

Abstract

Through a combination of standard laboratory-based surface science methods, together with synchrotron radiation-based NIXSW (normal incidence X-ray standing wave) experiments, the interface structure of simple alkylthiolate 'self-assembled monolayers' on Cu(111), Ag(111) and Au(111) has been investigated over the last ~15 years. A key conclusion is that in all cases the adsorbate produces a substantial, densitylowering, reconstruction of the outermost metal layer, although the nature of these reconstructions is quite different on the three metals. The main results of these investigations are briefly reviewed and contrasted.2

Modeling the Electronic Properties of π‐Conjugated Self‐Assembled Monolayers

“…[221,222] Due to differences in their lattice constants and their chemical nature, also different packing motifs and/or different surface reconstructions might be encountered on these substrates. Indeed, several possibilities have been proposed for SAMs of short-chain alkylthiols both from experiments [223][224][225] and from theory. [60,116,226,227] In contrast, little is known about the packing and the atomistic structure of the docking-group/substrate interface for conjugated SAMs, which are the focus of the present paper; it appears unreasonable, however, to simply assume the H3 Â H3 commensurability of S-atoms found on Au(111) also in calculation of SAMs on, for example, Cu(111), [228] due to the significantly smaller lattice constant of the latter.…”

The local structure of molecular reaction intermediates at surfaces

“…Rather, the surface reaction (deprotonation) provides a mechanism for the attachment of the molecule to the surface in a similar way that the deprotonation of thiols (particularly simple alkane thiols) is a necessary condition to produce self-assembled monolayers (SAMs) of thiolates on the surfaces of noble metals, and especially of Au(111) (systems that are much-studied in general [41,42], and which have also been subjected to some quantitative structural studies, e.g. [43]). However, of the fully-quantitative structural studies of deprotonated amino acids on surfaces, namely of glycine on Cu(110) [44,45] and Cu(100) [45], and alanine on Cu(110) [46], it is interesting to note that these are carboxylates that do not 'stand up' on the surface, but rather adopt an orientation that allows attachment to the surface not only through the two carboxylate O atoms, but also through the amino N atoms.…”

The local adsorption geometry of benzenethiolate on Cu(100)

“…The simplest model systems are the alkylthiolates (CH 3 (CH 2 ) n S-), and these have been the subject of most of the structural studies so far (see, e.g. [5]), although the structure of the archetypal Au(111)/alkylthiolate SAM interface is proving highly controversial [6,7,8].…”