610 



ABSORPTION SPECTRA OF PIGMENTS IN VITRO 



CHAP. 21 



appear at 325 and 375 mn. Below the region shown in figure 21.3, both 

 components have an absorption maximum at 250 m/i (asp. ^^ 30). 



An absorption band at 330 mix was first noticed in the spectrum of alcoholic extracts 

 from nettle leaves by Lewkowitsch (1928). 



The absorption spectra of chlorophyll, ethyl chlorophyllide and phytol 

 in the infrared were described by van Gulik (1914) and Stair and Coblentz 



80 



72 



64 



56 - 



48 



40 



32 



24 



16 



\ Chlorophyll b 



\_'' 



260 280 300 320 340 360 



WAVE LENGTH, m/i 



380 



400 



420 



Fig. 21.3. Ultraviolet spectrum of chlorophylls a and b in ethyl ether (after 

 Harris and Zscheile 1943). Specific extinction coefficients; c in g./l. 



(1933). Chlorophyll is transparent between 0.7 and 3 n (this may be useful 

 in preventing the overheating of leaves in direct sunlight). It has several 

 absorption bands at 3-4, and 5.8 yu; most of them are found also in the 

 spectrum of phytol, and are absent from that of ethyl chlorophyllide (c/. 

 fig. 21.4 and Table 21.IIA); they thus belong to the phytyl chain rather 



