Yuji Shitara

Tribochemical activation of gold surface by scratching

Abstract Fresh gold surfaces were formed by scratching under high vacuum conditions, and adsorption and reactions of organic compounds on the surface were monitored with a quadrupole mass spectrometer. It was found that the gold surface was activated tribochemically by scratching, and various organic compounds chemisorbed on the fresh surface. The estimated chemisorption activities were closely related to the functional group of the organic compounds. Hydrogen evolution due to decomposition of adsorbed molecules was observed even after the termination of scratching. Hydrocarbons were also evolved on adsorption of organic iodide. It is conclude that gold surface becomes so active by scratching that chemisorption and decomposition of organic compounds occur on it even at room temperature.

Chemically active surface of gold formed by scratching

Abstract Chemisorption of organic compounds was carried out on fresh gold surfaces which were formed by scratching under high-vacuum conditions. Although chemisorption of ester (methyl acetate) was not observed, benzene, 1-hexene and cyclo-hexene which have π-electrons were chemisorbed on the fresh gold surface. This indicates that the chemisorption activity on fresh gold surfaces is dependent on the molecular structure of the adsorbents. It is concluded that the gold surface acquires an unexpectedly high chemical activity by mechanical activation.

Mechanochemical activity of nascent surfaces of gold, silver and copper

Nascent surfaces of gold, silver and copper were formed by scratching under high vacuum conditions, and their chemical activity was investigated by a newly developed method. Chemisorption of organic compounds on the nascent surfaces was observed from the partial pressure change detected by a quadrupole mass spectrometer. It was found that nascent gold surface became so active by scratching that organic compounds chemisorbed on it, and hydrogen due to decomposition of adsorbed molecules was detected even at room temperature. Olefins and aromatic compounds which have /spl pi/-electrons chemisorbed on the nascent surfaces of gold and copper, but no chemisorption was observed on the nascent silver surface. Some hydrocarbons were detected during scratching these metals under organic sulfides and organic iodides. It can be concluded that surface defects on nascent surfaces act as an active site for the chemisorption and the decomposition of organic compounds.