Arc Spectrum of Nitrogen in the Extreme Ultra-Violet

Analysis and classification of lines in the arc spectrum of nitrogen.—Excitation of nitrogen by controlled electron impact was found to bring out many lines in the arc spectrum of nitrogen. These were observed with a vacuum spectrograph in the region from 500 to 1200A. The lines thus found, together with material of Hopfield, Bowen, and Fowler in the extreme ultra-violet, and of Merton and Pilley in the visible, and the multiplets already found by Kiess have led to a fairly complete analysis of the spectrum, in good agreement with the predictions of the Hund theory. The ionization potential is 14.48 volts, and the metastable levels ${}_{}{}^2{}_{}{}^{}D$ and ${}_{}{}^2{}_{}{}^{}P$ have energies corresponding to 2.37 and 3.56 volts respectively, in good agreement with the predictions of Kaplan and Cario from a study of active nitrogen.