A Reinvestigation of the Wave-lengths and Relative Intensities in the Molybdenum K series X-ray Spectrum

Abstract

The x-ray beam from a water-cooled target of a tube carrying 25 m-amp. from a 50 kv storage battery, was limited to 2 minutes and reflected from a calcite crystal of a spectrometer with a Genevoise scale reading to 2 seconds, into an ionisation chamber. The 3rd to 5th orders were used. The angle of reflection for each wave-length was determined by readings on both sides of the direct beam. Corrections were applied for the temperature of the crystal above 18°, for the eccentricity of the scale and for refraction. The wavelengths are found to be (taking $d=3.028\mathrm{}\mathrm{A}$): ${\alpha }_2=.\mathrm{}711835\mathrm{}$, ${\alpha }_1=.\mathrm{}707525\mathrm{}$, ${\beta }_3=.\mathrm{}631354\mathrm{}$, ${\beta }_1=.\mathrm{}630791\mathrm{}$, $\gamma =.\mathrm{}619526\mathrm{}$. From 3 to 5 determinations were made for each line, the average deviation from the mean being.000025. The mean deviation from the last results of A. Leide is.00003 except for ${\beta }_1$ for which his value seems too high. The separation ${\beta }_3-{\beta }_1$ is.000563 in good agreement with the separation ${\mathrm{L}\beta }_3-{\mathrm{L}\beta }_4$ determined by Coster. The wave-lengths taking $d=3.02904\mathrm{}\mathrm{A}$ and the $\frac{v}{R}$ and $\sqrt{\frac{v}{R}}$ values for the K lines and for the corresponding energy levels in the Mo spectrum are also given. The K absorption limit was found at.61830A. Relative intensities. Assuming each component of the $\beta$ doublet to be a single line of the same width, the relative intensities come out $\mathrm{K}\frac{{\beta }_1}{{\beta }_3}=2.0\mathrm{}$, in agreement with the theoretical predictions of Sommerfeld and of Coster and Goudsmit. In the case of the $\beta$ and $\gamma$ doublets the total intensity of each doublet was taken proportional to the area under it, correcting for the K absorption in the case of the $\gamma$ peak. The relative intensities then come out $K\frac{\beta }{\gamma }=7.7\mathrm{}$, which is greater than the corresponding ratio for tungsten, indicating a decrease with increasing atomic number.