Fabrication of chemical templates via selective laser-induced desorption of hexadecanethiol self-assembled monolayers

摘要

A nonlinear photothermal laser patterning technique for rapid fabrication of chemical templates is demonstrated. Hexadecanethiol monolayers on Au-coated Si substrates are processed at λ = 532 nm, a 1/e~2 spot diameter of d_(1/e)2 = 2.8 μm and ambient conditions. Local laser irradiation at high laser powers and short irradiation times in the micro-/millisecond range induces desorption of thiol molecules. The laser-depleted areas are backfilled with mercaptohexadecanoic acid in order to build up chemical templates. Atomic force microscopy, scanning electron microscopy and scanning Auger electron spec-troscopy are used for characterization of these templates. In agreement with a selective laser process, the results indicate the formation of flat chemical patterns with well-defined boundaries. Complementary condensation experiments demonstrate the functionality of the patterns as hydrophilic/hydrophobic templates. In particular, upon decreasing the temperature below the dew point, selective formation of water droplets on the backfilled areas is observed.