Scanning Tunneling Microscopy Characterization of Organoselenium Monolayers on Au(111)

Self-assembled monolayers were formed by immersing Au(111) surfaces into solutions of benzeneselenol and diphenyl diselenide. Chemisorption of benzeneselenol produced numerous gold islands (20−200 Å in diameter) on the surface and a selenium-containing monolayer with a fundamental repeat unit of (3√3 × 2√3)R30°. Upon annealing at 60 °C in air, these gold islands coalesce to form larger, hexagonal-shaped islands. Chemisorption of diphenyl diselenide is qualitatively similar and upon annealing appears to produce the same surface structures observed with benzeneselenol. These organoselenium-modified surfaces were investigated by scanning tunneling microscopy (STM) and Auger electron spectroscopy (AES).