Determination of metal atoms incorporated in molecular intermediates: an STM study of acetylide on Ag(1 1 0)

Many inorganic molecular intermediates, such as imide, nitrate, and sulfite, incorporate a stoichiometric number of added metal atoms into their structures on Ag(1 1 0) or Cu(1 1 0). In this paper an example of such general behavior is illustrated with an organic molecular intermediate––acetylide (C2) on Ag(1 1 0). Acetylide is produced by reacting acetylene with oxygen atoms on the Ag(1 1 0)-p(2 × 1)-O surface. Acetylides form row structures along the 〈 1 1 ¯ 0 〉 axis, which, as coverage increases, are compressed along the 〈0 0 1〉 axis to form nominal “p(2 × 2)”, “p(2 × 3)”, “p(2 × 1)”, and “p(14 × 1)” structures. The final acetylide structure incorporates 0.55 ML silver atoms, which may be released upon titration with acetic acid. A buckled structure is proposed where acetylide bonds to two added silver atoms in a linear configuration in the trough along the 〈 1 1 ¯ 0 〉 axis with seven equally spaced silver atoms in a p(13 × 1) unit cell.