34 



H. LINHCHITZ AND K. \\ . ABRAHAMSON 



excited by resonative transfer of energy from the rest of the chloro- 

 phyll aggregate (()). The flash data show that, in agreement with 

 Franck's postulate, the metastable form of chlorophyll does indeed 

 have an absorption band strategically placed to permit trapping of 



C 

 Fig. 2. Changes in light transmission through chlorophvll-6 sohitions, following 

 flash illumination. Solvent, deoxygenated 1)5 '/ti methanol; concentration, 1.2 X 

 10 ~* M; upper sweep, flash plus measuring light; middle sweep, flash alone (base 

 line); lower sweep, 10,000 cycle time marker. A, 655 niM (red peak); B. 700 m/x; 

 C, 525 niM. 



energy from the first excited singlet levels of adjacent molecules. It is 

 of interest to point out that other " reversibly bleached" chlorophylls, 

 such as the phenylhydrazine reduction product, do not show any 

 appreciable absorption beyond the original red peaks. 



The curves given here are taken with considerably better signal-to- 



