HYDROGEN DISSOCIATION ON PT(100) - NONLINEAR POWER-LAW IN HYDROGEN-INDUCED RESTRUCTURING

Using molecular beam sticking probability measurements at desorption temperatures we have made a dynamical measurement of the (1X1) island growth rate and the simultaneous D coverage on the rotated quasihexagonal reconstructed phase (hex-R) during the D-induced hex-R-->(1X1) phase transformation on Pt{100}. The island growth rate (r(g)) is described by a strongly nonlinear power hex) at surface temperatures in the law with respect to the local D coverage on the hex-R phase (theta(D)(hex)) at surface temperatures in the range 150-250 K. The apparent rate is given by r(g) alpha (theta(D)(hex))(4.0+/-0.5). These kinetics are shown to be consistent with the dependence of the temperature programmed desorption spectra on the surface temperature and rate of D-2 impingement during adsorption at similar to 245 K. In particular the intensity of the alpha(3) desorption peak is markedly sensitive to these parameters, consistent with its assignment to associative desorption from the (1x1) phase. (C) 1995 American Institute of Physics.