#physical adsorption

• Adsorbate — A fluid substance (gas, liquid, or dissolved solute) whose molecules are attracted, retained, and concentrated as an extremely thin molecular film upon the surface of a solid or liquid substrate (the adsorbent). The adsorbate constitutes the mobile component within the system prior to adhesion and the resulting layer on the interface after the process. Its energetic state and molecular dynamics change radically upon interacting with active sites.
• Adsorption — The spontaneous physical-chemical phenomenon consisting of the adhesion and concentration of fluid molecules (gas or liquid) onto the surface of a solid or liquid substrate. Unlike absorption (a bulk phenomenon), adsorption is strictly a surface phenomenon driven by the imbalance of intermolecular forces at the adsorbent's boundary layer. It is categorized into physical adsorption (physisorption) and chemical adsorption (chemisorption).