Homomolecular process

It is emphasized that the terms excimer2 and exciplex3,4 are reserved here for homomolecular and heteromolecular excited double molecules formed after the act of light absorption by one component in a process of photoassociation, in the absence of spectroscopic or cryoscopic evidence for molecular association in the ground state. Recent findings indicate that excimer (or exciplex) formation may also result from triplet-triplet annihilation,5,8 cation-anion combination7 (doublet-doublet-annihilation), and electron capture by the (relatively stable) dimer (or complex) cation8 these processes are discussed in Section VII. 

If both A and B are polyatomic relaxing gases, there will also be two collision processes, corresponding to (1) and (2), for vibration-translation energy transfer from B in homomolecular and heteromolecular collisions. In addition there can be a vibration-vibration transfer between A and B, making five transfer processes in all... 

Nucleation processes, especially in nature, are rarely homomolecular and homogeneous usually two species are involved (binary heteromolecular nucleation), and foreign surfaces may also be present (heterogeneous... 

Cunningham and co-workersl have monitored the atomic fraction 18 ( fa) to distinguish the homomolecular and heterolytic exchange processes ... 

Studies of the homomolecular and heterolytic exchange processes are generally in the form of the measurement of rates under isothermal conditions. However, studies have also been made of temperature programmed isotopic exchange, in which the oxide is subjected to a temperature ramp under the reaction atmosphere, and the partial pressures of various isotopic oxygen species is determined as a function of temperature (e.g., Refs. 20-21). The photoactivation of oxygen exchange has also been reported in a number of studies which have been performed under UV irradiation (e.g.. Refs. 18, 22, 23). 

The systems having components which interact by means of donor-acceptor bond (without proton transfer) belong to the same type of solvents (e.g., pyridine-chloracetyl, dimethylsulfoxide-tetrachloroethylene, etc.). Components of mixed solvents of such type are more or less associated in their individual states. Therefore, processes of heteromolecular association in such solvents occur along with processes of homomolecular association, which tend to decrease heteromolecular associations. 

MIXED SOLVENT EFFECT ON THE POSITION OF EQUILIBRIUM OF HOMOMOLECULAR ASSOCIATION PROCESS... 

All questions this part deals with are considered based on the example of a special and wide-studied type of homomolecular association process, namely, monomer-dimer equilibrium ... 

Homogeneous nucleation is the formation of the condensed phase (particles) from purely gaseous molecules. If only a single molecular species is involved, the process is termed homomolecular, while it is called heteromolecular when more than one such species participates. Aspects of homogeneous nucleation depend to a great extent upon collision rates this leads to highly mixed results upon treatment by kinetic theoretic means. Undoubtedly, any ultimate description will necessitate details not only of kinetics but also of dynamics and microparticle microphysics to account for the rates and structure of critical (i.e., stable) cluster formation. 

By integrating eq. (8-23) and using eq. (8-22), we can calculate the concentration of electronic charge carriers at the surface,, and thus we can calculate the rate of dissociation, if we assume a certain type of disorder in the thin film layer, and if the proper boundary conditions are used. As an example [22, 23], let us consider the oxidation of Ni to NiO. For thin oxide layers, the oxidation process approximately obeys a cubic rate law between 250 °C and 400 °C. Simultaneous studies of oxidation and homomolecular isotope exchange according to the reaction = 2 at the NiO surface have been carried out. These... 

Three processes that are of major importance in the phenomenon of photoconductivity are carrier generation, carrier recombination, and carrier transport. These will be discussed in that order, as they relate to homomolecular polycyclic aromatic hydrocarbon (PAH) crystals. It is surprising that the mechanisms of carrier generation and carrier transport in well-characterized crystalline compounds are still subjects for heated dispute. 

Type 1 isotherm eorresponds to the experimental isotherm with isotherms [8.1.24] or [8.1.26] of the liquid systems without interaction. The additive e inerease is eompensated by 8 decrease, due to homomolecular association process. The system diethyl ether-m-cresol illustrates this type of isotherm. 

Mixed solvent effect on the position of equilibrium of homomolecular association process... 

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