. Carnegie Institution of Washington publication. . t '£ 3 Fig- 74- Decay curves with and without infra-red. •4 Sec. «5 « ^seey Fig- 75- X = m (Fig. 74) and X = m (Fig. 75). In all of these experiments the luminescence spectrum consisted of two bands, namely, the green band at /x and the violet band at about /x. It is possible that the infra-red rays retard the decay of phosphorescence in the case of the violet band and accelerate it in the case of the green band. In the curves of Fig. 75 we are dealing with the violet band only; in Figs. 70, 71, 72, and 74 the light is alm
. Carnegie Institution of Washington publication. . t '£ 3 Fig- 74- Decay curves with and without infra-red. •4 Sec. «5 « ^seey Fig- 75- X = m (Fig. 74) and X = m (Fig. 75). In all of these experiments the luminescence spectrum consisted of two bands, namely, the green band at /x and the violet band at about /x. It is possible that the infra-red rays retard the decay of phosphorescence in the case of the violet band and accelerate it in the case of the green band. In the curves of Fig. 75 we are dealing with the violet band only; in Figs. 70, 71, 72, and 74 the light is almost entirely from the green band; but at wave-lengths M (Fig. 73) and /x (Fig. 74) the light entering the collimator slit comes partly from one of these bands and partly from the other. The violet band apparently decays more rapidly than the green band. (Compare the slant of the line for J~* in Fig. 75 and Fig. 72.) If the violet band is initially the brighter of the two the retarding effect of the infra-red upon the decay of this band will predominate in the early stages of decay. Later, when the violet band has nearly died out and the light is chiefly due to the green band, the opposite effect will predominate. The two curves / and /' will therefore intersect, as shown in Fig. 72 and Fig. 74- Two objections may be urged to this explanation. If the light in the case of Figs. 73 and 74 is from two bands that decay at different rates we should hardly expect the relation between / and J~* to be as simple as the. Please note that these images are extracted from scanned page images that may have been digitally enhanced for readability - coloration and appearance of these illustrations may not perfectly resemble the original Carnegie Institution of Washington. Washington, Carnegie Institution of Washington
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