Angular Intensity Distribution of a Molecular Oxygen Beam Scattered from a Graphite Surface

Abstract

The scattering of the oxygen molecule from a graphite surface has been studied using a molecular beam scattering technique. The angular intensity distributions of scattered oxygen molecules were measured at incident energies from 291 to 614 meV with surface temperatures from 150 to 500 K. Every observed distribution has a single peak at a larger final angle than the specular angle of 45° which indicates that the normal component of the translation energy of the oxygen molecule is lost by the collision with the graphite surface. The amount of the energy loss by the collision has been roughly estimated as about 30-41% based on the assumption of the tangential momentum conservation during the collision. The distributions have also been analyzed with two theoretical models, the hard cubes model and the smooth surface model. These results indicate that the scattering is dominated by a single collision event of the particle with a flat surface having a large effective mass. The derived effective mass of the graphite surface for the incoming oxygen is 9-12 times heavier than that of a single carbon atom, suggesting a large cooperative motion of the carbon atoms in the topmost graphene layer.

Dynamics of the Oxygen Molecules Scattered from the Graphite (0001) Surface and Comparison with Experimental Data

“…Oh et al 3,4 stated by using a HCM that the translational energy of the molecules should be reduced by the collision with the graphite surface, in a similar manner as QCT results show (Figures 4a and 4b).…”

“…The application of a hard cube model (HCM with an effective mass of 108 amu) fitting the experimental peak positions allow to explain the aforementioned experimental trends 3 although with less accuracy than the present QCT results, which are only based on first principles. The introduction of the internal modes of O2 on the scattering through a smooth surface model 3 or by using classical rigid molecular scattering calculations 4 (both with an effective mass of 129.6 amu) improve the agreement with the experiment. However, the authors conclude that the small differences still observed between the theoretical and experimental distributions could be originated by other possible mechanisms caused by the presence of surface defects 4 , neither included in present QCT calculations.…”

Alignment-resolved O2 scattering from highly oriented pyrolytic graphite and LiF(001) surfaces

“…• is associated with direct inelastic scattering following the previous O 2 scattering study on HOPG [27]. The peak intensity depends strongly on the geometry, and this dependency is larger at lower temperature.…”

Ab Initio Molecular Dynamics Study of Alignment-Resolved O2 Scattering from Highly Oriented Pyrolytic Graphite

“…Regarding the specific system studied here, there are several experimental − and theoretical − studies focused on the interaction of O 2 with highly oriented pyrolytic graphite (HOPG). The reason is the importance of this model system for understanding the behavior of carbon-based materials in different applications, such as processes of burning phenomena in nature, coal gasification, reactions at nuclear reactor walls, and the degradation mechanism of the spacecraft vehicle shielding, among others.…”