تأثير مجال الليزر على عملية الالتصاق الكيميائي لجزئية ثنائية الذرة على سطح الصلب

الملخص EN

I n this study ,a mathematical model to study the chemisorption of two interacting atoms on solid surface in the presence of laser field is presented .

Our study has aim only , the study the effect of laser field on determining the ionization and dissociation states to describe the molecule – surface interaction dynamics .

Our mathematical model is based on the occupation numbers formula that depends on the laser field and which is derived according to Anderson model for single atom adsorbed on solid surface.

Occupation numbers formula and chemisorption energy formula are derived for two interacting atoms (as a diatomic molecule )as they approach to the surface taking into account the correlation effects on each atom and between atoms as well as the image effect on each one .

This model is characterized by the obvious dependence of the relations on the system variables and the laser field characteristics which gives precise description for the molecule – surface interaction dynamics (i.e.

the charge and spin on the interacting atoms ) as a function of the normal distance from the surface and the distance between atoms .Our mathematical model is applied to the H2 / W(100) system for academic and experimental reasons, where the moleculesurface interaction dynamics is investigated by calculating the occupation numbers and all the chemisorption functions as a function of all variables when the distance between the atoms is parallel to the surface.It is found that the type of interaction between the atoms and surface , whether it is repulsive or attractive , is determined by the laser strength where the repulsion between the two atoms increases with the laser strength increasing .

The orientation effects are taken into account throughout the broadening functions due to the coupling with surface energy levels and as well as due to the laser field.Extended calculations for all functions, that describe the system dynamics, are presented as a function of all variables as well as the orientation angle.

By comparing the orientation effect and laser field effect, it is concluded that the laser field effect is dominant .It is found that by taking the orientation effects, the interaction is repulsive for both strength values that used (0.1a.u.,0.2a.u.) in this research as compared with the case of incorporating laser field only or orientation effect only.

So it makes sure that the laser field as well as the orientation effects can be consider as a tool to control the ionization and dissociation processes that happen on the solid surface .