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STM image of a quinacridone adsorbate.The self-assembled supramolecular chains of the organic semiconductor are adsorbed on a graphite surface.. Surface science is the study of physical and chemical phenomena that occur at the interface of two phases, including solid–liquid interfaces, solid–gas interfaces, solid–vacuum interfaces, and liquid–gas interfaces.
Schematic of the electrical double layer (EDL) in aqueous solution at the interface with a negatively-charged surface of a mineral solid. Blue + sphere: cations; red – spheres: anions. The number of cations is larger in the EDL close to the negatively-charged surface in order to neutralize these negative charges and to maintain electroneutrality.
The surface area of an adsorbent depends on its structure: the more pores it has, the greater the area, which has a big influence on reactions on surfaces. If more than one gas adsorbs on the surface, we define as the fraction of empty sites, and we have:
Langmuir was awarded the Nobel Prize in 1932 for his work concerning surface chemistry. He hypothesized that a given surface has a certain number of equivalent sites to which a species can "stick", either by physisorption or chemisorption. His theory began when he postulated that gaseous molecules do not rebound elastically from a surface, but ...
The surface acidity and basicity of the oxide depends on the crystal structure and surface orientation. [20] The surfaces of zirconia have hydroxyl groups, which can act as Brønsted acids or bases, and coordination-unsaturated Zr 4+ O 2− acid base pairs which contribute to its overall acid–base properties. [ 20 ]
is the rate constant for surface adsorption, m 3 ·mol −1 ·s −1 k − 1 {\displaystyle k_{-1}} is the rate constant for surface desorption, s −1 C S {\displaystyle C_{\mathrm {S} }} is highly related to the total surface area of the adsorbent: the greater the surface area, the more sites and the faster the reaction.
Desorption is the physical process where adsorbed atoms or molecules are released from a surface into the surrounding vacuum or fluid. This occurs when a molecule gains enough energy to overcome the activation barrier and the binding energy that keep it attached to the surface.
This spacing is called the electron affinity (note that this has a different meaning than the electron affinity of chemistry); in silicon for example the electron affinity is 4.05 eV. [16] If the electron affinity E EA and the surface's band-referenced Fermi level E F-E C are known, then the work function is given by