Transit Time Distributions in Complex Chemical Systems

123 Transit Time Distributions in Complex Chemical Systems 

Response experiments that can be interpreted in terms of lifetime distributions are limited to the study of the response of an excitation of the same species. Because of this constraint the information acquired is local and refers to a single species, which is usually part of a large reaction network. In order to obtain global information about reaction mechanisms and kinetics, we need to involve responses to excitations involving at least two species, preferably more. 

We consider a complex chemical system and focus on a set of S species M , u = 1. 5, which can carry one or more identical molecular fragments that are unchanged during the process in the following we refer to these species as carriers. For simplicity, in this section we limit ourselves to the case of isothermal, well-stirred, homogeneous systems, for which the concentrations c = c (t), u = 1. 5, of the chemicals M , m = 1. 5, are space independent and depend only on time. Later on we consider the more complicated case of reaction-diffusion systems. The deterministic kinetic equations of the process can be expressed in the following form  

We denote by Zu the number of fragments in the carrier species u. We use the notation 

In the system a fragment is transferred from one carrier to another. These transfer processes involving fragments u, u =, S, among different carriers can be formally 

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