748 



FLUORESCENCE OF PIGMENTS IN VITRO 



CHAP. 23 



Chlorophyll d, too, was described by Manning and Strain (1943) as 

 exhibiting a deep red fluorescence. Its spectrum shows a first maximum at 

 693 mju (in ethereal sokition) and indications of a diffuse second maximum 



at 750 mM- 



No quantitative data appears to be available on the fluorescence spec- 

 trum of allomerized chlorophylls. 



Proiochlorophyll has a fluorescence band at 626.5 mju, in ether (Dh6r6 

 1930). The fluorescence bands of pheophytin a lie at 676 and 730.5 mju 

 in ether (Dhere and Raffy 1935) and at 677.5, 717, 750.5 and 804 mju in 

 dioxane (Stern and Wenderlein 1936). 



A photometric curve of the fluorescence spectrum of bacteriochlorophyU 

 in solution was obtained by Vermeulen, Wassink and Reman (1937). It 

 showed two bands, a weaker one at 695 mju, and a stronger one at 810 m/j 

 (fig. 23.4). The relationship of these two bands is not clear (c/. p. 751). 



The fluorescence of these and many other porphin derivatives was re- 

 viewed by Dhere (1937, 1939). 



c 



J3 

 O 





650 700 750 800 



WAVE LENGTH, m/i 



850 



Fig. 23.4. Fluorescence spectrum of bacteriochlorophyU in solution 

 (after Vermeulen, Wassink and Reman 1937). 



No counterpart of the strong blue-violet absorption band appears in chloro- 

 phyll fluorescence, even if white, violet or ultraviolet light is used for excita- 

 tion (c/. Dhere and Raffy 1935, Prins 1934, and Vermeulen, Wassink and 

 Reman 1937) . The same is true of the weaker absorption bands in the mid- 

 dle of the visible spectrum. True, Prins (1934) said that the red band oc- 

 curs in fluorescence without the yellow and orange bands only if fluores- 

 cence is excited by red light (660-680 m/x); and Ivnorr and Albers (1933, 

 1935) observed "subsidiary" fluorescence bands on the short-wave side of 

 the main one— at 633 and 637 mju in chlorophyll a and b, respectively (c/. 

 Table 23.1) ; but Zscheile and co-workers (1935, 1943), who excited fluores- 

 cence with white light, and Vermeulen, Wassink and Reman (1937), who 

 used ultraviolet and blue exciting light, obtained fluorescence curves with- 

 out any indication of such additional bands (cf. fig. 23.2). 



Zscheile and Harris (1943) foimd that the fluorescence spectmm of 

 chlorophyll was exactly the same whether excited by the mercury lines 



