SPECTRAL PROPERTIES OF CELLULAR PIGMENTS 



21 



600 



650 



700 



750 



0.2 



0.1 



0.0 



672 



Sum, 0-90; Diffusing 

 plott at vesiel 



600 



650 700 



Wavelength ,m^ 



750 



Fig. 4. Top set of curves, apparent absorption spectra of the same 

 Chlorella suspension measured with a special spectrophotometer arranged 

 to gather light from the suspension at various angles. The peak position 

 varies greatly with the angle at which the light is collected. Bottom curve, 

 the same suspension measured with an opal glass plate averaging all 

 angles (Latimer, 1957). 



the upper part a line with solid black points shows the apparent 

 absorption spectrum of a Chlorella suspension when measured with a 

 narrow beam. The position of the maximum is 688 m/u. The shape of 

 this curve is primarily determined by wavelength-selective scattering 

 of the pigment particles, and the curve has very little relation to the 

 actual absorption spectrum. By measuring at an angle of about 3.4° 

 ± 0.2°, the apparent peak position is shifted to 682 ni//.. In taking a 



