. Carnegie Institution of Washington publication. 192 STUDIES IN LUMINESCENCE. Having computed in this way the intensity of the rays which actually reach the region in the solution under observation, and which are therefore available for producing excitation, it was only necessary to find the amount of energy absorbed in each case by multiplying I0e~°,82a by a. Finally the absorbed fluorescence, divided by the absorbed energy which produced it, gave the quantity sought, that is, the intensity of fluorescence excited by unit quantity of absorbed energy of the particular wave-length in question.
. Carnegie Institution of Washington publication. 192 STUDIES IN LUMINESCENCE. Having computed in this way the intensity of the rays which actually reach the region in the solution under observation, and which are therefore available for producing excitation, it was only necessary to find the amount of energy absorbed in each case by multiplying I0e~°,82a by a. Finally the absorbed fluorescence, divided by the absorbed energy which produced it, gave the quantity sought, that is, the intensity of fluorescence excited by unit quantity of absorbed energy of the particular wave-length in question. In the case of eosin the observed data, as well as the derived quantities corresponding to several steps in the computation, are given in Table 27. In the case of resorufin the same thing is shown graphi- cally (Fig. 184). The ob- served points in each case are connected by full lines, while in the case of com- puted values the points are connected by broken lines. In curve / we have the in- tensity of the exciting light after reflection from mag- nesium carbonate. Curve 77 gives the intensity of the light actually reaching that flie ordinates of curve 77/ are Curve III. 62// Fig. 184. Resorufin. part of the solution opposite the slit S'. obtained by multiplying each of the ordinates of curve 77 by a. therefore gives the energy actually observed from the exciting light for each wave-length. When the ordinates of curve IV, which shows the observed fluorescence, are divided by the ordinates of curve 77/ we have the quan- tity desired, namely, the fluorescence excited per unit of observed energy (curve V). Table 27.—Eosin. I 2 3 4 5 6 7 8 9 10 Intensity Intensity Reflecting h corrected Rnergv in h (Energy.) Specific X of fluores- of exciting power of for C2H2 he-"* afoe—"x exciting cence. light. MgCOs reflection. spectrum. power. 0. 479/* 2 .2 I02 I. 15 9 3 485 103 3 53 49' 4 1 8-3 104 4 24
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