Concerning the Shape of the Compton Lines (From a Letter to A. H. Compton)

Abstract

The structure of the spectrum of the modified x-radiation scattered by bound electrons is discussed. It is shown that the well-known continuous Compton band must have a definite limit on the short wave side (i.e., toward the unmodified line). Between this limit and the unmodified Rayleigh line, theory predicts the existence of a spectrum of discrete lines, which are appropriately classed as Raman lines. They are composed of those scattered photons which have excited, but not ionized the scattering atom. The conditions under which it might be possible to observe these Raman lines are discussed. There is no abrupt change in the specific intensity (per unit wave-length interval) as the limit of the discrete spectrum is crossed. It is suggested that the lines reported by B. B. Ray in 1930 may be interpreted as residue of Compton bands cut off by the foresaid limit.