Resonance effects active particles

Some interesting resonance effects on scattering by "active" particles have been pointed out recently by ALEXOPOULOS and UZUNOGLU [4.44] and amplified by KERKER... 

Since SERS is a resonance effect related to the SPR of colloidal particles, its sensitivity is affected by size, shape, and structure of their arrays. The abihty to tailor colloid size, size distribution, and shape motivates examination of the influence of these fectors on SERS [280]. The optimal particle size for the SERS effect was found to be between 30 and 150 nm, with decreasing enhancement in smaller and larger particles [280,281]. Cotton and coworkers checked the influence of the interparticle distance in silver and gold NP (40 nm) arrays on their SERS activity. It was found that only arrays with aggregates (NPs in contact) showed the Raman enhancement, whereas arrays composed of NPs with any interparticle distance had no SERS activity [282]. These findings are in agreement with other research that found that the strongest enhancement comes from molecules situated between particles [278,283]. 

In this chapter, we discussed the principle quantum mechanical effects inherent to the dynamics of unimolecular dissociation. The starting point of our analysis is the concept of discrete metastable states (resonances) in the dissociation continuum, introduced in Sect. 2 and then amply illustrated in Sects. 5 and 6. Resonances allow one to treat the spectroscopic and kinetic aspects of unimolecular dissociation on equal grounds — they are spectroscopically measurable states and, at the same time, the states in which a molecule can be temporally trapped so that it can be stabilized in collisions with bath particles. The main property of quantum state-resolved unimolecular dissociation is that the lifetimes and hence the dissociation rates strongly fluctuate from state to state — they are intimately related to the shape of the resonance wave functions in the potential well. These fluctuations are universal in that they are observed in mode-specific, statistical state-specific and mixed systems. Thus, the classical notion of an energy dependent reaction rate is not strictly valid in quantum mechanics Molecules activated with equal amounts of energy but in different resonance states can decay with drastically different rates. 

Recently, ultrafine metai particles have attracted much interest because of their unique properties which differ from those of buiK metals, e.g., quantum size effect, such as low melting point, plasmon resonance absorption and so an It is well known that ultrafine metal particles are quite active because of their large surface area and that they are liable to aggregate and grow in size. Thus, it is necessary to maintain them in stable form in a matrix for size control and tor narrow size distribution. Ultrafine metal partides-polymer composites, which are prepared by embedding ntetal particles in a polymer, can be used as electrical, magnetic, optical or chemically useful materials. The techniques to prepare ultrafine metal partides-polymer composites have been explored end reported by many researchers. Many of these involve co-evaporation or co-sputtering of a metal and polymer . In the case of thesb methods, however, metal-polymer composites have to be prepared at a rate below ca. 10 nm/min so that ultrafine metal particles will not... 

With the possible exception of clay, feldspar is the most essential ceramic material in the whiteware industry. It is the universal flux used in aU types of ceramic bodies, and should be ground very fine. The fluxing effect of feldspar may be noted in a whiteware body as low as cone 09. As temperature increases, the feldspar becomes more active, dissolving first the clay substance and finally the flint particles. Above cone 10, muUite begins to crystallize in the glassy matrix formed by the feldspar at cone 12, it is present in sufficient quantities to improve ware properties. It affects practically aU fired body properties, including even translucency, resonance and expansion. In some cases, the... 

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