DYNAMICS OF LUMINESCENCE 145 



The effect of temperature on luminescence is of special, 

 interest because it gives us a means of analysis for deter- 

 mining if the luminescence depends on reaction velocity. 

 We know that photochemical reactions are very littl^ 

 affected by temperature because the reaction is dependent 

 Dn the absorption of light, a physical process, and thi^ 

 increases only a small per cent, for a rise of temperature! 

 af 10° C. To put it in the usual way, its temperature] 

 3oefficient (QiJ for a 10° interval is usually less than 1.1. 

 On the other hand, we should expect photogenic reactions, 

 in which some of the chemical energy is converted into 

 -adiant energy, to give off much more light the 

 greater the reaction velocity. As reaction velocity in- 

 ;rea.ses so rapidly with temperature (Qio^2 to 3), 

 uminescence intensity should rapidly increase with 

 ncrease iri^flTr^jigT^jviTrp^ ^ 



Trautz (1905), from his extensive study of the chemi- 

 uminescence of phenol and aldehyde compounds came to 

 he conclusion that luminescence intensity was propor- 

 ional to reaction velocity. He based his conclusions 

 argely on the effects of temperature and concentration otf 

 •eacting substances and went so far as to declare that any 

 ■eaction would produce luminescence if the reaction veloc- 

 ty were sufficiently increased. It is quite true that increaS* 

 ng the temperature does increase the intensity of chemi- 

 aminescenee, but this is only within certain limits. As 

 re raise the temperature, chemiluminescence becomes 

 Qore intense but we soon reach a temperature for maxi- 

 lum luminescence and above this the intensity diminishes. 

 ?his is especially well seen in the action of various 

 xidizers on pyrogallol and H2O2 recorded in Table 10. 

 Lt 100° C. practically no light is produced by many 



