Energy loss, mechanisms

Between 1923 and 1927, the concepts of quantum efficiency (number of photons emitted divided by number of photons absorbed by a sample) and quantum yield (fraction of excited molecules that emit) had been defined and values determined for many compounds by Vavilov (34). The quantum yield indicates the extent that other energy loss mechanisms compete with emission in an excited molecule. Although the quantum yield is influenced by the molecular environment of the emitter, for a given environment it depends on the nature of the emitting compound and is independent of concentration and excitation wavelength, at least at low concentrations (35). Tlius, it serves as another measurable parameter that can be used to identify the compounds in a sample and also, because of its sensitivity to the surroundings of the luminophore, to probe the environment of the emitter. 

The Fokker-Planck equation is essentially a diffusion equation in phase space. Sano and Mozumder (SM) s model is phenomenological in the sense that they identify the energy-loss mechanism of the subvibrational electron with that of the quasi-free electron slightly heated by the external field, without delineating the physical cause of either. Here, we will briefly describe the physical aspects of this model. The reader is referred to the original article for mathematical and other details. SM start with the Fokker-Planck equation for the probability density W of the electron in the phase space written as follows ... 

In general, low concentrations of the active ion, of the order of 1 %, are used. At these concentrations, the ions form point defects well isolated from each other. At higher concentrations, dopant ions tend to cluster and other energy loss mechanisms interfere with up-conversion. 

Changes in energy loss mechanisms operating when the Auger electron is... 

It is possible to combine lifetime measurements with Doppler broadening techniques. In so-called Age-Momentum-Correlated measurements (AMOC), Doppler broadening information is collected as a function of time since positron implantation into the sample [76]. The energy loss mechanism for positronium as it traps in pores can be investigated. This might reveal material dependent effects that have not been included in any porosity studies by positrons. 

In conclusion, although a detailed outline of both the chemistry and energy transfer processes in / -diketonates of Eu " has emerged in the last few years, it is clear that much experimental and theoretical work needs to be done, especially on chelate-solvent interactions and energy loss mechanisms within the europium ion manifold. 

A large amount of the studies on this field are devoted to the analysis of the energy loss of atomic particles scattered off surfaces under grazing angle of incidence. The aim of this work is to review some recent developments on this problem. We focus on the theoretical approaches that have been used to characterize and understand the energy loss mechanisms under these conditions. 

This can be produced by ordinary bremsstrahlung and is an important energy loss mechanism in hot white dwarfs. 

An increase in pressure results in an increase in T. When the polymer chains are subjected to pressure, more therma energy is required to activate the energy loss mechanisms. Heydemann and Guicking (23) determined the specific volume of unplasticized and DOP plasticized PVC by dilatometry over the temperature range of -80 to 150 °C at hydrostatic pressures of 1-1000 atm. Figure 19 shows... 

Structural losses are characteristic of structured disperse systems. In free disperse systems these losses play a role at high concentration of dispersed phase. Structural losses are related to the oscillations of the network of particles, which may be viewed as a number of interconnected oscillators. As pointed out by Dukhin [26,27], structural losses provide a link that bridges acoustics with rheology. At this time there is no adequate theoretical description of this energy loss mechanism. 

The most important energy loss mechanism is typically backside cooling. The gap between the wafer and the electrode is expected to be some tens of microns. At low pressures, at which the mean free path of gas species is much larger than the wafer-electrode gap, the heat transfer coefficient for backside cooling is independent of the gap width and is given by... 

One of the main differences between the one-dimensional and the multidimensional turnover theory comes from the change between the one-dimensional and multidimensional energy loss mechanism. 

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