DO ALKANE THIOLS FORM STABLE MONOLAYER FILMS ON THE SURFACES OF HIGH-TEMPERATURE SUPERCONDUCTORS (HTSCS)

Recently there has been significant interest in the chemical modification of HTSC surfaces with molecule-based reagents. We will describe a preliminary survey of the surface coordination chemistry of YBa{sub 2}Cu{sub 3}O{sub 7-{gamma}} and other HTSC materials. In this survey, we have used a series of redox-active ligands containing alkyl amine, aryl amine, thiol, phosphine, amide, and alcohol functionalities. Evidence supporting the strong adsorption of molecules with alkyl amine, aryl amine and thiol functionalities will be reported. Resistivity measurements for the HTSCs and modified HTSCs show that chemical modification does not significantly lower T{sub c} for the superconductor. This work presents the first example of the direct chemical modification of the surface of a high-T{sub c} superconductor with a monolayer of a molecular reagent. A surprising result is that alkyl thiols do form stable, robust monolayers on a variety of HTSCs. Others have reported that under similar conditions alkyl thiols do not stably chemisorb onto HTSCs. However, alkyl amines are the superior reagent for the chemical modification of the Cu-rich HTSCs.