Theoretical Study Of Adsorption, Diffusion And Dissociation Mechanism On Gas-state Surfaces

The dynamics of gas-surface interaction is awaking more and more interest in the community of physicists and chemists. Whether multi-phase catalysis or colloid catalyzed interaction is related to the interaction between reactants as well as between reactant and catalyzer surface. Therefore, the study on the interaction between atom, molecule and catalyzer surface, especially the interaction with active sites by theory is necessary.The main content in this paper is as follows:In chapter 1, the elementary theory for calculation in this paper and the surface cluster model are given.The H-Cu, N-Cu, H-Pd(311 )Ni(311) interaction systems entirely investigated by constructing atom-surface interaction potential named five parameters Morse potential (5-MP for short) in chapter 2.The analytical potential of gaseous diatom molecule interaction system, i.e. LEPS potential has been constructed. And the NO-Ni and 62-Ag systems are studied in chapter 3.The main research fruit in this work is as follows:1. The adsorption system of H atom on the Cu metal surface. The vibration frequencies are easy to measure in experiment, and are the most important critical characters to ascertain the adsorption sites and states. However, the experiments are made under different conditions, and obtained bitty information. Moreover, the problem on the attribution of frequencies is usually inconsistent. Our calculation results excluded the adsorption on bridge site, and H atom adsorbs on the three-fold site. Moreover, we obtained the 130 (129) meV and 117(119) meV, which are attributed to the vertical and parallel vibration respectively. Calculation results not only reproduced the vibration frequencies but also ascertained adsorption sites and states. On Cu (110) surface, only appear long-bridge and fake three-fold sites, notshort-bridge.This paper has been published on journal of chemistry, 2004, 62 (4), 436?41. 2.With regard to the competition between adsorption sites on H-Pd(311)Ni(311) system. For many adsorption sites and states are exist on the stepped surfaces, and the clear understanding about adsorption sites and geometry is necessary to the dynamics research. It is well known that the adsorbed atom is apt to the high-cooperated site. And the (311) surface has three adsorption sites: fourfold, fee threefold and hep threefold respectively. However, only two kinds of adsorption states appeared. Whether threefold or fourfold sites are taken up is the controversial focus among experimental scientists. The adsorption and diffusion mechanism is as follows: due to the H atom is very small, and can get into the subsurface. And at the very low coverage, H atom firstly adsorbs on the three-fold site lying on topmost surface, because the fourfold site lying on the subsurface has lower adsorption energy, the small H atom diffuses easily to the place. With the covering increasing, the three-fold site was also taken up, however, the three-fold site near to the four-fold was annihilated owe to the competition. And with the covering further increasing, all the three and four-fold sites were taken up and the substrate was saturated. So from the viewpoint of the experiment, adsorption was mainly found on the four-fold at low coverage, of course, thee-fold sites were also occupied partially. Therefore, the peak intense of fourfold sites are higher, and the threefold sites are lower, our theory is in good agreement with experiments.The paper has been accepted by Chinese Journal of Chemistry, and finalized a manuscript.3.N atom of adsorption and diffusion on Cu surface. Whether experimental or corresponding theoretical researches are scarce, especially opinions vary on the reconstruction problem. Therefore, we constructed the (1 ll)-r model according to corresponding experimental guesses. And obtained the good agreement with the EELS experiment, which suggests that the existence of aberrant Cu(lOO) structure and only the top-layer Cu atoms reconstruct. The adsorption of N atoms lead to the reconstruction, and form order phase and N atom takes...