Article,
The adsorption dynamics of molecular carbon dioxide on Pt(1 1 1) and Pd(1 1 1)
Surf. Sci., 497 (1-3): 356 - 372 (2002)
DOI: DOI: 10.1016/S0039-6028(01)01674-0
Abstract
The dynamics of the nondissociative adsorption of carbon dioxide on
Pt(1 1 1) and Pd(1 1 1) were investigated by supersonic molecular
beam techniques at a surface temperature of 80 and 60 K, well below
the desorption temperatures of 95 and 88 K, respectively. The initial
trapping probability of CO2 on both Pt(1 1 1) and Pd(1 1 1) scale
with normal and near-normal energy scaling functions, indicating
smooth gas�surface potentials. On the other hand, trapping on the
carbon dioxide-saturated Pt(1 1 1) exhibits a more corrugated gas�surface
potential, on which trapping scales as ETcos0.7 theta. The probability
of carbon dioxide trapping increases with self-coverage and is successfully
described by the modified Kisliuk model, indicating that trapping
into the extrinsic precursor state is more efficient than trapping
on the clean surface. The coverage of carbon dioxide into Pt(1 1
1) saturates at about 0.275 ML at a surface temperature of 80 K as
a result of beam exposure at normal incidence at 8.5 kJ/mol. The
stochastic, three-dimensional classical dynamics for the simulation
of CO2 on Pt(1 1 1) indicates that the excitation of surface phonons
on the first bounce determines trapping on Pt(1 1 1). The same set
of Morse potentials were employed to predict the CO2 trapping on
Pd(1 1 1). In general, the prediction agrees reasonably with the
experimental results. The difference between the calculated trapping
probabilities from simulations and the experimental values is within
20%.
Tags
- adsorption
- adsorption;
- carbon
- crystal
- dioxide;
- dynamics;
- kinetics;
- molecular
- palladium;
- physical
- platinum;
- single
- sticking;
- surfaces
