MEASUREMENT BY PHOTOELECTRIC FRINGE SCANNING OF THE PRESSURE SHIFT OF Hg-198 EMISSION LINES

Abstract

Photoelectric fringe scanning apparatus has been developed at the National Research Laboratories for the measurement of very small wavelength changes (of the order of 5 × 10−5 Å). This paper describes its application to a direct measurement of the shift of some of the visible lines of Hg-198 caused by the presence of the various rare gases used as a carrier. The values found for the shift in wave number are all of the order of 2 × 10−4 cm−1 per mm. (Torr) pressure and to the red, except for He, for which it is somewhat less than 1 × 10−4 cm−1 per mm. and to the blue.