28 



STUDIES IN LUMINESCENCE. 



Dissolved in absolute alcohol it is bright red in color, with a sharply defined 

 fluorescence band extending from 0.54 p. to the limits of the visible spectrum 

 in the red. The transmission spectrum given in Table 2 and Fig. 23 shows 

 the absorption band corresponding to this, and also a smaller absorption 

 band in the violet. 



Different concentrations of resorufin were used. These are merely rela- 

 tive and are indicated as "concentration , J, |, /,;, J.,, t .} A , and ^os," the 

 original solution being taken as ] . All curves corresponding to the above 

 concentrations are indicated by the letters A,B,C, D, E, F, and G respectively. 



Table 2. 



Transmission through layer of resorufin 1.075 cm. thick. Concentration |. X = Wave- 

 length. 7 = Intensity of light before transmission. 1= Intensity of light after 

 transmission. 



ABSORPTION AND THICKNESS. 



The first problem under consideration was, as stated above, to find 

 whether a fluorescent solution acts like an optically perfect substance in 

 obeying Lambert's law of absorption, i. e., whether 



where To and / are the intensities before and after transmission, and x is 

 the thickness of the absorbing layer. 



-v 



Wovo l_r.gtK ^ 



Fig. 23. 



Transmission spectrum of layer 1.075 cm. thick. Concentration i. 



