Experiments on the Reported Fine Structure and the Wave-Length Separation of theKβDoublet in the Molybdenum X-Ray Spectrum

A nomenclature is suggested for describing the possible positions of the double x-ray spectrometer. A position may be defined by ($n_A,n_B$) where $n_A$ is the order of reflection on crystal $A$; $n_B$ the order on $B$. $n_A$ is to be considered always positive. $n_B$ is negative if the position of crystal $B$ for the reflection of a wave-length incident upon it is such that by turning $B$ through an angle of less than 90° the reflecting surface of $B$ can be made parallel to that of $A$, and the given wave-length be reflected in this parallel position. If this convention be adopted it is shown that general equations for the instrument may be easily set up. Experiments on the separation of the $K{\beta }_1$ doublet of molybdenum at the position (2, 2) at 43-46 kv and 22 m.a. show that if the line $K{\beta }^{\prime }$ reported by Davis and ${\mathrm{Purks}}^1$ exists, its intensity is less than 1/10 that of ${\beta }_1$ at these voltages. An average of eight determinations of $\Delta \lambda$ for $\mathrm{Mo}K$, ${\beta }_1{\beta }_3$ gives 0.572±0.003 XU.