475 



S. S. Brody and M. Brody 



position of the new band reported here for dilute solutions of chlorophyll. 



We have made a preliminary survey of the materials which quench the 

 emission at 698 mp.. These include nitrobenzene, p-phenylenediamine, and the 

 'residue' of the petroleunn ether washings of the crystalline chlorophyll. The 

 petroleum ether 'residue' completely quenches the emission at 698 mfj.; add- 

 ing 'residue' to the same sample which gives curve I (Fig. 18) yields curve 

 in (Fig. 18). Materials which do not quench the emission are commerical 

 P carotene and vitamin K, as well as crude xanthophylls and carotenes 

 extracted from spinach. 



A comparison of curves II and III shows that the petroleum ether 'residue' 

 modifies the main emission band by decreasing its width, shifting its 

 emission maximum to shorter wavelengths and increasing its intensity. By 

 "subtracting" curve III from curve II (using as a condition no negative 

 values), we have obtained the emission spectrum of the "698 m|j. species" 

 Fig. 19. In addition to the maximum at 698 mfj., there is an even larger 

 maximum at 680 mjj.. We presume that this difference spectrum corresponds 

 to one band with two maxima, but it is possible that the two peaks represent 

 two bands. 



680 70O 



WAVELENGTH , m/i 



720 



700 

 WAVELENGTH , m/t 



Fig. 18 Emission spectra for specially 

 prepared chlorophyll in acetone (see text) 

 at 10"^M, Curve I - emission obtained 

 with chlorophyll before purification. 

 Curve II - spectrum showing new emission 

 band, Curve III - same sample as for curve 

 II but with quencher added. All excitations 

 at 436 m|jL. 



Fig. 19 Spectrum obtained by 

 taking the difference between 

 curves II and III in Fig. 18. 



