An Investigation of the Tungsten X-Ray Emission and Absorption Spectrum with a Vacuum Spectrometer

M series lines of tungsten.—Using a cast bronze x-ray tube and a vacuum spectrometer, the M series of tungsten has been studied both in emission and absorption. A new type of window for the x-ray tube was made by grinding lampblack with collodion. In the emission spectrum between 7A and 5A, two faint lines have been observed: ${\eta }_1=6.857\mathrm{}$ and ${\eta }_2=6.789\mathrm{}$A. Two components of the $\alpha$ and $\beta$ lines have been measured ${\alpha }^{\prime }=6.948\mathrm{}$, ${\beta }^{\prime }=6.720\mathrm{}$A, confirming the work of Hjalmar. In the absorption spectrum five lines ${\mathrm{M}}_1$-${\mathrm{M}}_5$ have been observed at 6.708, 6.475, 5.416, 4.800, 4.365A. The wave-length of the first two are less than their predicted values by an amount (about 2 percent) which is greater than the probable limits of error (±.006A). ${\mathrm{M}}_3$ has a component ${\mathrm{M}}_3$′ = 5.380A. ${\mathrm{M}}_5$ is very weak.