AN IN-SITU X-RAY PHOTOELECTRON STUDY OF THE INTERACTION BETWEEN VAPOR-DEPOSITED TI ATOMS AND FUNCTIONAL-GROUPS AT THE SURFACES OF SELF-ASSEMBLED MONOLAYERS

X-ray photoelectron spectroscopy (XPS) was used to study in situ the interface chemistry and film morphology during titanium metal deposition on functionalized surfaces prepared by self-assembly of end-functional alkanethiols, X-(CH2)(15)-SH, on gold (X = COOCH3, OH, CN, and CH3). The high reactivity of Ti with the COOCH3, ON, and CN groups on the surface results in the consumption of all functional groups at about one monolayer coverage, and the formation of oxide or nitride species, accordingly. At higher coverage the Ti atoms form direct metal-carbon bonds with the surface without altering the structure of the monolayer. The data also support the formation of metal clusters during film growth, and indicate a strong dependence of the Ti film morphology during the early stages of growth on the strength of the Ti-surface interaction. The strongest Ti-surface interaction results in the smallest cluster size (COOCH3 approximate to CN < OH < CH3) as indicated by a larger surface core-level shift.