Silver ions adsorbed to self-assembled monolayers of alkanedithiols on gold surfaces form Ag–dithiol–Au multilayer structures

Abstract.

Double-ended alkanedithiols, 1,9-nonanedithiol and 1,5-pentanedithiol, formed self-assembled monolayers (SAMs) on Au(l11) substrates and were used to adsorb silver ions from an ethanolic solution of silver nitrate and formed Ag–dithiol–Au multilayer structures. Ellipsometry, contact angle measurement and X-ray photoelectron spectroscopy (XPS) confirmed that the alkanedithiol molecules formed SAMs with only one-ended thiol groups attached to the Au substrates, which was supported by molecular mechanics calculation. XPS and X-ray Auger electron spectroscopy (XAES) indicated that silver ions were deposited onto the SAMs from the solution by the chemical reaction of silver nitrate with another-ended thiol groups of the SAMs. Atomic force microscopy (AFM) was used to observe SAMs and multilayer structures.