Hollow Iron Cathode Discharge as Source for Wavelength and Intensity Standards*

A sealed-off hollow cathode discharge tube with iron electrodes and rare gas filling is described which will give an iron spectrum with very sharp lines and intensities of high reproducibility. Extensive data are given of the dependence of the iron intensities on the character of the rare gas, its pressure, and the discharge current. For most purposes a neon filling at about 3 mm pressure is recommended. The lines of such a tube are recommended for wavelength standards. They may serve as intensity standards with the proper precautions.