ISOLATION OF AN INTRINSIC PRECURSOR TO MOLECULAR CHEMISORPTION

Over the past 70 years, numerous gas-surface adsorption studies have i ndicated the existence of a weakly bound, mobile intermediate that is a precursor to chemical bond formation, The direct observation and cha racterization of such a species are presented. Precursor and chemisorb ed benzene on a silicon surface were clearly distinguished with the us e of a tunable-temperature scanning tunneling microscope. Precursor de cay to chemisorption was observed, allowing the salient features of th e potential energy surface to be determined.