A survey of our present sources of information on the conversion constant, Λ(=λg/λs) and the absolute wavelengths of x-ray emission lines

Origin of the "X-Unit" and the Scale of X-Ray Wavelengths. - The wavelengths of X-ray emission lines measured relative to each other by the high precision methods of crystal diffraction are mostly known with a precision of 1 part in 10^(4) to 10^(5). By refined and very careful measurements with the 2-crystal spectrometer, an imprecision approaching and in some cases perhaps even smaller than a part in a million can be obtained