150 



Daniel Rubinstein 



This is the equation for a straight line when Iq/OD is plotted against 



1/ (OD ^ - OD) 

 ' ^ max ' 



O.D. 



max 



-O.D. 



Figure 1 

 The intercept on the abscissa and the ordinate are respectively: 



k^. 



and 



(11) 



(12) 



eK 



The intercept on the abscissa is related to the quantum requirement l/y 

 by the following expression: 



1 , . ^^ k, e (13) 



( 



y 



- 1 ) OD 



max 



\ ' 



The knowledge of the absolute number of absorbed quanta, K I^ is not 

 needed, to calculate the quantum requirement, since the constant, K, is 

 absent from equation (13). The only terms needed for this determination 

 are the change in OD reached at high light intensity. Calculation of the 

 extinction coefficient from the intercept on the ordinate (fig. 1) requires, 

 on the other hand, the knowledge of the number of absorbed light quanta, 

 since the constant, K, remains in the expression (12). 



