Temperature and Self-Absorption in an Atmospheric Chromium Arc, and f Values for Near-Infrared Lines of Chromium I, from Spectrometric Measurements with Refrigerated Photomultiplier Tubes

Abstract

A 5-A dc are was struck between pure chromium electrodes in nitrogen at 1 atm. The chromium I excitation temperature, averaged over atoms in the center of the arc image, determined by relative emission-line intensities in the near infrared, was found to be (4893 ± 190) °K. The extent of self-absorption was determined from the same lines. Relative f values for 63 lines of chromium I, including the 21 used initially, were determined with precision of 0.33 in log gf. Existing instrumentation and current improvements to the experiment are described.