Direct observation of surface reactions of acetylene on Pd(111) with scanning tunneling microscopy

A study was conducted to analyze the cyclotrimerization of acetylene to benzene on a Pd(111) surface by scanning tunneling microscopy. An ultrahigh-vacuum chamber was utilized to perform the experiment. The Pd(111) sample was cleaned by circles of argon ion sputtering at room temperature. Results indicated cyclotrimerization reaction at 140 K in disordered areas. Findings also showed that the cyclotrimerization of acetylene to benzene correlated with a transient state of acetylene.