THE ROLE OF STRUCTURAL-CHANGES IN THE EXCITATION OF CHEMICAL WAVES INTHE SYSTEM RH(110) NO+H-2/

Previous investigations have demonstrated that the formation of chemic al waves in the NO+H-2 reaction on Rh(110) involves a cyclic transform ation of the surface structure via various N,O-induced reconstructions , i.e., starting form the c(2X6)-O a cycle is initiated comprising the formation of a (2X3)/(3X1)-N and a mixed c(2X4)-2O,N structure. The s tability and reactivity of these structures has been investigated in t itration experiments as well as under stationary reaction conditions e mploying LEED, work function, rate measurements, and thermal desorptio n spectroscopy. It was shown that the c(2X6)-O and c(2X4)-2O,N structu res exhibit a low reactivity whereas the (2x1)/(2X1)-N displays only a small to moderate decrease in catalytic activity (approximate to 20%- 30%) compared to the clean surface, On the basis of these results, an excitation mechanism for pulses in the NO+H-2 reaction on Rh(110) was constructed consisting of the sequence c(2X6)-O, (2X1)/(3X1)-N c(2X4)- 2O,N, c(2X6)-O. (C) 1997 American Institute of Physics.