Reflection Absorption Infrared Spectroscopy (RAIRS) has been
employed in a study of carbon monoxide, hydrogen and ethylene
adsorption on a Pt(lll) single crystal model catalyst. The
experiments have been performed on apparatus consisting of a UHV
system with isolable high pressure cell, the latter being interfaced
to a Fourier Transform Infrared Spectrometer.
In situ RAIRS studies have yielded activation energies for the
formation and subsequent decomposition of the ethylidyne species on
Pt(lll). The kinetic parameters have been found to compare
favourably with those previously determined by less direct methods.
Rates of hydrogenation of the ethylidyne adlayer have been
monitored in situ as a function of hydrogen pressure up to 1 atm.
At pressures above approximately 1 mbar there is evidence for the
population of an ’on t o p ’ form of adsorbed hydrogen, the presence of
which brings about the onset of ethylidyne hydrogenation.