Kinetics of clustering

These days, remarkably high-resolution spectra are obtained for positive and negative ions using coaxial-beam spectrometers and various microwave and IR absorption teclmiques as described earlier. Infonnation on molecular bond strengths, isomeric fonus and energetics may also be obtained from the teclmiques discussed earlier. The kinetics of cluster-ion fonuation, as studied in a selected-ion flow tube (SIFT) or by high-pressure... 

We have conducted studies to investigate general factors influencing the kinetics of cluster formation.139,140 Extensive experiments were carried out with Na+, partly... 

The topochemical model, however, describes the origination and growth of macrostructures. In principle one could construct kinetic models accounting for the kinetics of cluster (or nucleate) formation as a model for the system or reverse consecutive reactions [114, 121]. 

To describe the thermodynamics and kinetics of clusters with due regard for the multiplicity of the structure states (SS) of these nuclei, it is necessary to introduce the SS sets. The mutual transformations of clusters by atom attach ment or detachment, or by atom rearrangements are possible. It means that the SS set may be ordered to form a space. Then, it is possible to consider the nucleation of noncrystalline nuclei (clusters) as a diffusion process in an extended space of cluster structure states (CSS), which is, in fact, the join of hierarchy of ultrametric subspaces. The kinetic criterion of glass transition can be formulated as a condition of the overwhelming transformation of a liquid into a noncrystalline amorphous solid. 

An important role in thermodynamics and kinetics of cluster formation is played by SSD, F(l/, N) ... 

Ziff RM, McGrady ED. The kinetics of cluster fragmentation and depolymerisation. J Phys A 1985 18 3027-3037. 

KHATOURI, J., RIDARD, J., MOSTAFAVI, M., AMBLARD, J., BELLONI, J., Kinetics of Cluster Aggregation in Competition with a Chemical Growth Reaction , Z. Phys. D 1995, 34, 57-64. 

Determinatioii of Critical Size and fcf It has been shown (Ji) that the features of the kinetics of cluster coalescence in competition with a... 

The structural and functional properties of the iron and sulfide donor proteins (frataxin and IscS/NifS, respectively) that mediate [2Fe-2S] cluster assembly on the scaffold protein ISU/IscU are reviewed in light of the developing mechanistic understanding of cluster biosynthesis. The structural information now available for each class of protein provides a context for understanding recent measurements of die kinetics of cluster assembly and the thermodynamics of iron binding and scaffold-partner interactions. The protein NFU is discussed as a mediator of persulfide bond cleavage to yield inorganic sulfide for cluster assembly. 

Monte Carlo simulations have been used in some cases to study kinetics of clusters. For example, evaporation kinetics lends itself to this method. The method has been used to study kinetics of passage between pairs of adjacent minima, a subject discussed in a bit more detail later. A Monte Carlo study has described how a cluster of CO2 molecules containing a single 12 molecule relaxes when the extra electron is suddenly removed from the foreign molecule. ... 

Master equations have been used to describe relaxation and kinetics of clusters. The first approaches were extremely approximate, and served primarily as proof-of-principle. ° Master equations had been used to describe relaxation in models of proteins somewhat earlier and continue to be used in that context. " More elaborate master-equation descriptions of cluster behavior have now appeared. These have focused on how accurate the rate coefficients must be in order that the master equation s solutions reproduce the results of molecular dynamics simulations and then on what constitutes a robust statistical sample of a large master equation system, again based on both agreement with molecular dynamics simulations and on the results of a full master equation.These are only indications now of how master equations may be used in the future as a way to describe and even control the behavior of clusters and nanoscale systems of great complexity. ... 

Void swelling occurs because the vacancies and interstitials created by radiation are absorbed preferentially at different sinks (cf. Allen, 2004). Preferentially, interstitials are absorbed at dislocations due to stress fields excess vacancies cluster together to form voids. The kinetics of formation of such clusters are controlled by the physical and chemical nature of the material. In pure metals, the kinetics of cluster nucleation and growth are determined in terms of the mobility of interstitials (vacancies), the irradiation time, radiation flux, and the mobility of the defects. In the... 

Good, A. Durden, D.A. Kebarle, P., Ion-molecule reactions in pure nitrogen and nitrogen containing traces of water at total pressures 0.5-4 torr. Kinetics of clustering reactions forming H (H20) , J. Chem. Phys. 1970, 52, 212-221. 

The data on kinetics of clustering reactions presented in the present section are far from complete. Nevertheless, they provide an important background with which many estimates can be made. Significantly, practically all data shown in Tables I-III were obtained in the last three years. Further rapid progress in this field can be expected. 

Ernst, M. H. Kinetics of cluster formation at irreversible aggregation. In book Fractals in Physics. Ed Pietronero, L. Tosatti, E. Amsterdam, Oxford, New York, Tokyo, North-Holland, 1986, 399-429. 

Several authors have modeled the kinetics of cluster growth. Nucleation occurs at specific sites, often associated with lattice defects on the substrate. Cluster growth commences as atoms impinge near each other in a series of experiments it was found that gold atoms will be captured if they land within 6.5 A of a growing cluster. 

At time intervals t tw the non-stationary kinetics of clusters of leirge enough size (j 1) is described by the Zeldovich-Frenkel equation (Venables et al. 1984)... 

A recent investigation gives some insights into one aspect of the kinetics of cluster formation, both above and below Tg. In a study of the expansion coefficients of the styrene ionomers as a function of ion contentit was.found that the equilibrium values were independent of ion content. However, whenever the sample had been allowed to remain at room temperature for a few hours after cooling from above Tg, and subsequently heated again above the glass transition temperature, the first run yielded a value of the liquid expansion coefficient ca 25% lower than that... 

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