. Carnegie Institution of Washington publication. DISTRIBUTION OF ENERGY IN FLUORESCENCE; SPECTRA. 185. Fig. 179. For purposes of graphical computation we may conveniently express the approximate value of r" in terms of the distance DC, Fig. 179. If this dis- tance be called br it may be readily shown that r" = 28/a\ _di2 T _25r_iArA/~| d*? L 3 r 6 r f J In computing these correction terms the lumi- nosity curve given by Tufts was The values of Ar and br were taken from the curve showing the relation between X and the approxi- mate value of r. The correction depending upon br
. Carnegie Institution of Washington publication. DISTRIBUTION OF ENERGY IN FLUORESCENCE; SPECTRA. 185. Fig. 179. For purposes of graphical computation we may conveniently express the approximate value of r" in terms of the distance DC, Fig. 179. If this dis- tance be called br it may be readily shown that r" = 28/a\ _di2 T _25r_iArA/~| d*? L 3 r 6 r f J In computing these correction terms the lumi- nosity curve given by Tufts was The values of Ar and br were taken from the curve showing the relation between X and the approxi- mate value of r. The correction depending upon br is important only when the curvature of the r curve is con- siderable. In the present instance this correction is large for regions near the crest of the curve, but insignificant elsewhere. The importance of the correction is well shown in the curves for resorufin (Fig. 176), where the points marked with crosses show the curve after the slit correction has been applied. In the case of eosin and fluorescein the region near the crest was uncertain for the reasons already mentioned (p), so that the slit correction has not been applied in this region. The second correction term, depending upon the product ArAf, is negli- gible near the crest of the luminosity curve of the source, where A/is small. The term is thus of no significance in the case of eosin and fluorescein. Even with resorufin, where the whole luminescence spectrum lies well t? ths infra side of the crest of the luminosity curve, this correction is important only on the steep side of the curve. The result of applying the correction is shown by the points in Figs. 176 and 177 that are marked with crosses. THE CORRECTION FOR The fluorescent light which enters the slit of the spectrophotometer in the foregoing experiments comes from a layer of liquid in the fluorescence cell having a thickness determined by the opening de, Fig. 175, through which the exciting light enters the cell. This layer, which is to be
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