Hello scientific community,
I would like to ask you a question concerning the adsorption. one could give a clear explanation about the difference between " the weak chimisorption" and "physisorption". to my knowledge, the simplest definition of each of the processes is the interaction of chemical substance with a solid without giving rise to an exchange of charges. Do you have any idea about a difference between them ?
Best regards,
abdelmounaim
Dear Abdelmounaim,
Please read the following text:
Molecules interact with surfaces with forces originating either from the “physical” Van der Waals interaction or from the “chemical” hybridization of their orbitals with those of the atoms of the substrate. Depending on which contribution dominates we speak of physisorption or of chemisorption. These are limiting cases since hybridization is always present at small enough adsorption distances, even for adsorbed rare gases.
Physisorption
absence of chemical bonds the molecule retains its gas phase electronic structure, although some distortion is still possible. The binding energy depends on the polarizability and on the number of atoms involved of the atoms and varies between few meV (light gases) and several eV (large organic molecules).
Chemisorption
stronger perturbation of the molecular electronic structure with formation of chemical bonds with the substrate. Energies typically of several eV.
For more information illustrated by mathematical equations, please see the attached file.
Hoping this will be helpful,
Rafik
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