Energy transfer models

Based on solutions of the master equation (ME) (see below) for model systems, Troe [11,12] developed a relationship between the collision efficiency parameter (fie) and the average energy transferred per collision, A aii  

The energy-dependence factor of the density of states Fe is a function introduced by Troe [13] and it is defined for vibrational densities of 

In this equation we explicitly write Fe as a function of temperature to emphasize that it is not a constant number. Evaluation of Fe requires knowledge of Pvib( and in a later section we will describe methods to accurately calculate this function. 

Gilbert et al. [14] showed that the approximation given by equation (41) leads to inaccurate results for high values of Fe and suggested the following alternative formulation  

In this equation ac represents the average energy transferred in deactivating ( down ) collisions, is related to A aii via 

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On the other hand, the similarity between metals is a characteristic of the electron-mediated vibrational energy transfer models. Here one must only calculate the population of excited electron-hole pairs at the energy of vibrational excitation, a quantity that is quite similar for many metals.b... 

Energy transfer modeled as a classical event orientation effects... 

Most of the modern theories of the photoconductivity sensitization consider that local electron levels play the decisive role in filling up the energy deficit The photogeneration of the charge carriers from these local levels is an essential part of the energy transfer model. Regeneration of the ionized sensitizer molecule due to the use of the carriers on the local levels takes place in the electron transfer model. The existence of the local levels have now been proved for practically all sensitized photoconductors. The nature of these levels has to be established in any particular material. A photosensitivity of up to 1400 nm may be obtained for the known polymer semiconductors. There are a lot of sensitization models for different types of photoconductors and these will be examined in the corresponding sections. 

Within the frame of the simplified energy transfer model ( S 3T Ln ), eq. (11)... 

Van Patten PG, Shreve AP, Lindsey JS, Donohoe RJ. Energy transfer modelling for the rational design of multiporphyrin light-harvesting arrays. J Phys Chem B 1998 102 4209-16. 

MRRKM theory, from RIT, from direct trajectory simulations, and, for reference purposes, from the RRKM theory. In particular, a test of the effect of the RRKM choice of transition state on the predicted rate of isomerization is made by neglecting the contribution of intramolecular energy transfer (Model No. 1). It is seen that the RRKM choice of transition state leads to considerable error the isomerization rate constant predicted is greater than those from the MRRKM theory and RIT by as much as a factor of 4. With intramolecular bottlenecks taken into account, both RIT and the MRRKM theory agree well with trajectory calculations. 

The phenomenon of LLP is a complicated behavior that varies from materials to materials. Up to now, there are several models such as electron or hole transfer model, configurational coordinate model and energy transfer model proposed to try to describe the process of LLP phenomenon in details [14]. In the present article, we propose a thermal-assistant recombination mechanism of electrons and holes to illustrate the LLP phenomenon with combination to the results of measurements above obtained in the sample. 

Fig. 2. Polymer fraction vs. irradiation time for a 4-BCMU film, 1300 A thick. Data points are experimental, full curves are obtained for the energy transfer model for various quenching parameters k, = k To (from Ref. >)...

Keywords compensation effect, isokinetic effect, Rochow synthesis, transition metal silicide phases, selective energy transfer model... 

We would like to emphasize that this attempt to ply the selective energy transfer model to our results does not mean that we reject other concepts for interpreting the compensation effect. 

We have used trajectory calculations to calculate this quantity [26]. Our method distinguishes between effective trajectories that contribute to P(E ,E) and those with very large impact parameter which do not. The P(E ,E) thus found, obeys conservation of probability and detailed balance and is independent of the impact parameter. The method is demonstrated for benzene-Ar collisions at various temperatures and internal energies. With this method, it is possible to combine ab initio inter and intramolecular potentials with trajectory calculations, obtain P(E ,E) and use that in master equation calculations to obtain rate coefficients and population distributions without resorting to any a priori assumptions and energy transfer models. 

Gas-phase reactions in this pressure regime are described in more detail by the Lindemann energy transfer model for association reactions which is represented by the following equations [33,187,188] ... 

While the energy transfer model is remtarkably successful in summarizing the polymerization kinetics of vinyl monomer solutions, there may be other explanations w ith certain monomer-... 

Marcoux and Setser investigated chemically activated CHaCFst and reported preferred energy transfer models and values for several bath gases (4). The typical experimental range employed in these non-... 

Comparison of Pressure Falloff Curves. The assignment of energy transfer models and values has often been based upon comparisons between the curvatures of experimental vs. calculated (ka/ka ) vs. (S/D) plots. This type of comparison obviates the requirement for accurately known ka values in s units, because the ka values are scaled by dividing by ka °. 

The construction of energy-transfer model systems by use of noncovalently linked donor-acceptor pairing is also of great interest in that it helps the understanding of biological photochemical behavior. In 1990, Hamilton and coworkers presented the first example of noncovalently linked donor-... 

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