76 KINETICS OF CHEMILUMINESCENCE 



minus the rate of internal quenching 



A*^A + heat (3) 



the rates of external quenching 



J^(A* + Qi -^ A + Q, + heat) (4) 



^ • -t- Vt 



1 = 4 



and the rate of emission of light 



A*^A^ hv (5) 



The concentration of excited molecules as a function of time is given 

 by 



dA* 



dt 



= hB - (^-1 + h + Yj ^'^Qi)^* (6) 



1 = 4 



The fraction of the excited molecules that produce light is 



« = '^- 



1 ^ 71 



ki + ^-3 + X) ^^Q- (7) 



This fraction is equal to the rate of emitting light divided by the total 

 rate of destruction of the excited molecules. If one knows the relation- 

 ship between these various reaction rates, it is possible to relate the 

 intensity of the light to the rate of production of excited states and 

 therefore to the rate of the reaction. However, for the purpose of this 

 paper, it is assumed that (f>, the fraction of excited molecules that 

 produce light, is independent of the concentration and nature of the 

 oxidants employed. This would be true as long as the principal mode 

 of quenching is by means of intramolecular transfer of energy or 

 when the concentrations of the external quenchers remain constant. 

 The effect of temperature on 4, will be determined by an experimental 

 study of the quantum yield of a particular reaction as a function of 

 temperature. 



Historical 



The DPD's and, in particular, luminol are well suited for kinetic 

 studies. The light emitted on oxidation is relatively bright and luminol 

 at least is readily available. Because of the availability of luminol, 



