SELF-ASSEMBLED MONOLAYERS ON GOLD GENERATED FROM ALIPHATIC DITHIOCARBOXYLIC ACIDS

Self-assembled monolayers (SAMs) were prepared by the adsorption of al iphatic dithiocarboxylic acids (ADTCAs) onto the surface of gold. Thes e new SAMs were characterized by optical ellipsometry, contact angle g oniometry, and polarization modulation infrared reflection absorption spectroscopy. The data are consistent with a model in which the ADTCAs generate well-packed and highly oriented monolayer films. Comparison of the wettabilities of these new SAMs to those prepared from normal a lkanethiols reveals an unusually large ''odd-even'' effect when hexade cane is used as the contacting liquid. The origin of this effect is at tributed to chelation of the ADTCA headgroup to the surface of gold.