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Nonthermal Surface Reaction
In the field of physical chemistry Physical chemistry is the study of macroscopic and microscopic phenomena in chemical systems in terms of the principles, practices, and concepts of physics such as motion, energy, force, time, thermodynamics, quantum chemistry, statistica ..., a nonthermal surface reaction refers to an elementary reaction between a thermally accommodated adsorbed surface species and a reactant which has not yet thermally accommodated to the surface. The two main mechanisms classified as nonthermal are the Eley-Rideal and hot atom mediated mechanisms. Surface science {{physical-chemistry-stub ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Physical Chemistry
Physical chemistry is the study of macroscopic and microscopic phenomena in chemical systems in terms of the principles, practices, and concepts of physics such as motion, energy, force, time, thermodynamics, quantum chemistry, statistical mechanics, analytical dynamics and chemical equilibria. Physical chemistry, in contrast to chemical physics, is predominantly (but not always) a supra-molecular science, as the majority of the principles on which it was founded relate to the bulk rather than the molecular or atomic structure alone (for example, chemical equilibrium and colloids). Some of the relationships that physical chemistry strives to resolve include the effects of: # Intermolecular forces that act upon the physical properties of materials ( plasticity, tensile strength, surface tension in liquids). # Reaction kinetics on the rate of a reaction. # The identity of ions and the electrical conductivity of materials. # Surface science and electrochemistry of cell membrane ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Reactions On Surfaces
Reactions on surfaces are reactions in which at least one of the steps of the reaction mechanism is the adsorption of one or more reactants. The mechanisms for these reactions, and the rate equations are of extreme importance for heterogeneous catalysis. Via scanning tunneling microscopy, it is possible to observe reactions at the solid gas interface in real space, if the time scale of the reaction is in the correct range. Reactions at the solid–gas interface are in some cases related to catalysis. Simple decomposition If a reaction occurs through these steps: : A + S ⇌ AS → Products where A is the reactant and S is an adsorption site on the surface and the respective rate constants for the adsorption, desorption and reaction are ''k''1, ''k''−1 and ''k''2, then the global reaction rate is: :r=k_2 C_\mathrm=k_2 \theta C_\mathrm where: * ''r'' is the rate, mol·''m''−2·s−1 *C_Ais the concentration of adsorbate, ''mol·m−3'' *C_\mathrm is the surface concentrati ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Hot Atom
In physical chemistry, a hot atom is an atom that has a high kinetic or internal energy. When molecule AB adsorbs on a surface dissociatively, # both A and B adsorb on the surface, or # only A adsorbs on the surface, and B desorbs from the surface. In case 2, B gains a high translational energy from the adsorption energy of A, and hot atom B is generated. For example, the hydrogen molecule, because of its light mass, gets a high translational energy. Such a hot atom does not fly into vacuum but is trapped on the surface, where it diffuses with high energy. Hot atoms are expected to play important roles in catalytic reactions. For example, a reaction of a hydrogen atom with hydrogen atoms on a silicon surface and a reaction of an oxygen atom with oxygen molecules on Pt(111) have been reported. Hot atoms can also be generated by degenerating molecules on a metal surface with UV light. It has been reported that the reactivity of an oxygen atom generated in such a way on a plati ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
