The Spectrum of Scattered X-Rays

The spectrum of molybdenum Kα rays scattered by graphite at 45^∘{}, 90^∘{} and 135^∘{} has been compared with the spectrum of the primary beam. A primary spectrum line when scattered is broken up into two lines, an "unmodified" line whose wave-length remains unchanged, and a "modified" line whose wave-length is greater than that of the primary spectrum line. Within a probable error of about 0.001 A, the difference in the wave-lengths (λ-λ₀) increases with the angle θ between the primary and the scattered rays according to the quantum relation (λ-λ₀)=λ(1-cosθ), where λ=h/mc=0.0242 A. This wave-length change is confirmed also by absorption measurements. The modified ray does not seem to be as homogeneous as the unmodified ray; it is less intense at small angles and more intense at large angles than is the unmodified ray.An x-ray tube of small diameter and with a water-cooled target is described, which is suitable for giving intense x-rays.