1496 



PHOTOCHEMISTRY OF CHLOROPHYLL 



CHAP. 35 



versibly bleached" form was designated by Livingston) are shown in table 

 35.IA. 



The reduction product of chlorophyll, observed by Krasnovsky et al. 

 in the reaction with ascorbic acid (c/, section 4) and the oxidation product 

 observed by Rabinowitch, and by Linschitz et al., in reactions with ferric 

 ions and quinone, respectively (c/. section 3), are similar to the phototrope 

 observed in the reversible bleaching of chlorophyll in air-free methanol 



t X 10 sec 



Fig. 35. 2A. Decaj^ of chlorophyll h absorption at 468 m^ after a flash (Living- 

 ston and Ryan 1953). Solid line, uncorrected observations; dashed line, correction 

 for scattering of flash light; dotted line, corrected decay curve. 



which has (according to table 35. lA) a region of sharply increased absorp- 

 tion in the middle of the visible spectrum (439-525 m^u for a; 525 m^ for 

 h), and sharply decreased absorption in the red (528-645 m/n); however, 

 the spectrum of the phototrope does not appear to be identical Math that 

 of the two other unstable photoproducts (could it be a mixture of both?). 



The second set of measurements by Livingston and Ryan (1953) was 

 made with four photoflash lamps surrounding the chlorophyll solution; a 

 scanning beam — photomultiplier — oscilloscope system permitted changes 

 in absorption with a resolving time of 0.1 msec, to be registered. Correc- 

 tion for scattered flash light was made by subtracting the results obtained 

 in air-saturated solution (where no reversible bleaching occurs) from those 



