Physical Review Volume 30 (Paperback)

This historic book may have numerous typos and missing text. Purchasers can download a free scanned copy of the original book (without typos) from the publisher. Not indexed. Not illustrated. 1910 Excerpt: ...the assumption that the band at.454 fi was slightly increased, if not entirely developed, by heating. The latter suggestion is supported by the fact that the fluorescence at room temperature measured shortly after cooling showed very little variation from that measured at the same temperature a few days before cooling. Summary. The essential results of the above recorded observations may be stated as follows: 1. Decrease of temperature produces a decrease in the absorption throughout that region of the spectrum measured and a corresponding narrowing of the absorption band, a result consistent with the effect of increasing temperatures. 2. The main portion of the rather broad fluorescence band in the yellow-green portion of the spectrum increases very decidedly on cooling and breaks up into two narrow overlapping bands very close together. 3. On the side of the shorter wave-lengths the fluorescence intensity decreases at the extreme low temperatures thus narrowing the band on that side. 4. The fluorescence bands which develop on cooling appear to be the same ones which were practically destroyed at the higher temperatures and the band which persisted at the higher temperatures has been destroyed by cooling or else did not exist at room temperature. 5. The fluorescence of this specimen evidently depends, to a more or less small extent, upon the previous heat treatment and the period of recovery to normal fluorescence may extend over a considerable time. Physical Laboratory, Cornell University. SOME PHOTO-ELECTRIC PROPERTIES OF THE ALKALI METALS. III. The Dependence Of Photo-electric Current On The Wave-length Of The Incident Light.1 By F. K. Richtmyer. SOON after the discoveiy that the alkali metals were photo active in the visible spectrum Elster and Geitel2...