S. Wehner et J. Kuppers, ABSTRACTION OF D-ADSORBED ON PT(111) SURFACES WITH GASEOUS H-ATOMS, The Journal of chemical physics, 108(8), 1998, pp. 3353-3359
The impact of gaseous H atoms at D covered Pt(111) surfaces at 85 K le
ads to the formation of gaseous HD and D-2 products. The kinetics of f
ormation of these products was measured simultaneously with H exposure
for different initial D coverages. The HD and D-2 rates as a function
of H fluence from the reaction start exhibit common characteristics;
a rate step, a rate maximum, and a subsequent exponential rate decay.
The HD and D-2 rate steps were observed not to scale linear with the D
coverage and to increase if on D covered surfaces H was coadsorbed pr
ior to reaction. Of the observed phenomena, only the exponential decay
of the HD rate is in line with expectations if an Eley-Rideal mechani
sm acts in the present reaction. D2 formation, the HD rate step as a f
unction of D coverage, and the presence of a H coadsorbate contradict
the Eley-Rideal picture. The results suggest that the reactions toward
s HD and D-2 proceed via hot atom type mechanisms. (C) 1998 American I
nstitute of Physics.