1832 



SPECTROSCOPY AND FLUORESCENCE OF PIGMENTS CHAP. 37C 



the observations of Weiss and Weil-Malherbe as an artefact caused by 

 re-absorption. 



Above 2 X 10~' M, self-quenching was found to be about the same for 

 the two chlorophylls, a and h, with blue or red exciting light, in ether or in 



o 



0.2 - 



2 4 6 



m X 10' 



20 



40 



60 



m X 



Fig. 37C.22. Concentration quenching of the fluorescence of chlorophyll solutions: 

 (•) chlorophyll a (in ether) excited with 435.8 mn; (O) chlorophyll b (in ether) ex- 

 cited with 435.8 m^; (®) chlorophyll b (in acetone) excited with 642.5 m^; (Q) chloro- 

 phj^U b (in acetone) excited with 435.8 m/x (after Watson and Livingston (1950)). Solid 

 line is from eq. (37C.3); dashed line from an equation based on the assumption that 

 dimerization (to non-fluorescent dimers) is the reason for concentration quenching. 



acetone (fig. 37C.22). The results fitted the one-constant equation (solid 

 curve) : 



(37C.3) 



^„/^ = 1 + 4300 [Chi ]2 



