On the Spectrum of X-Rays from an Aluminium Target

Abstract

Aluminium Spectrum.—The object of the research has been to investigate the question whether or not the frequencies of the K series are the highest X-rays frequencies characteristic of a chemical element. Several investigators have found experimental evidence, which they interpret as indicating the existence of characteristic emission or absorption of frequency higher than those in the K series. For aluminium the wave-lengths corresponding to these frequencies are stated to be.37 × ${10}^{-8\mathrm{}}$ cm. and.49 × ${10}^{-8\mathrm{}}$ cm. The authors of this paper have examined the emission spectrum of aluminium between the wave-lengths.1820 × ${10}^{-8\mathrm{}}$ cm. and 1.259 × ${10}^{-8\mathrm{}}$ cm. Four small peaks appear on the curves, indicating characteristic radiation at wave-lengths.622 × ${10}^{-8\mathrm{}}$ cm.,.705 × ${10}^{-8\mathrm{}}$ cm.,.975 × ${10}^{-8\mathrm{}}$ cm. and 1.18 × ${10}^{-8\mathrm{}}$ cm. The first two belong to the K series of molybdenum, and undoubtedly come from the metallic molybdenum in the Coolidge carthode in the X-ray tube. The last two belong to the L series of lead, and undoubtedly come from the lead screens containing the slits through which the X-rays passed before they reached the X-ray spectrometer.