Surface Science Letters A fast XPS investigation of NO-promoted acetylene cyclotrimerisation on Pd{1 1 1}

The strong promotion by NO of acetylene cyclotrimerisation to benzene on Pd{1 1 1} has been investigated by fast XPS,supported by LEED and D/ data. Islands of NO act to compress co-existing islands of acetylene. The resulting increase in acetylene density dramatically lowers the nominal threshold acetylene coverage required for reaction. In addition,the threshold reaction temperature is reduced from 150 to <100 K,and increased lateral interactions within the organic domains promote formation of tilted benzene. Co-adsorption of NO with benzene itself accelerates the desorption of both tilted and flat-lying benzene at low temperatures. These factors act to increase the yield of reactively formed benzene to 100%,completely suppressing carbon deposition that would otherwise result from decomposition of reactant and product. 2002 Published by Elsevier Science B.V.