C^SIUM-OXYGEN-SILVER PHOTOELECTRIC CELL 



355 



1 was nearer the end of the bulb at which the oxygen was introduced 

 and was apparently more oxidized than was position 2. The char- 

 acteristic spectral maximum for position 1, Fig. 8, is completely 

 suppressed and has not reappeared after 4.7 hours of baking at 75° C. 

 At position 2, Fig. 9, the height of the spectral maximum is greatly 

 reduced but recovers considerably on baking, moving towards the 

 longer wave-lengths, and accompanied by an increase in response at 

 10,000 A. till it exceeds that of the initial state. In this final state 



6000 



8000 

 WAVELENGTH IN A 



Fig. 9 — Relative spectral response to equal energy for cell A, position 2. 



the integral sensitivity of the cell as a whole had nearly recovered its 

 initial value. The large difference in behavior of the two ends of 

 the cathode is doubtless due to the fact that the oxygen was insuffi- 

 cient to oxidize even the superficial layer of free caesium and reacted 

 wherever it first struck the cathode. The difference between op- 

 posite ends of the cathode is less pronounced in the other cells treated 

 with more oxygen. 



In cell B, Figs. 10 and 11, which we have estimated to be treated 



