Doublets in Spectral Series

Abstract

THE physicists of Petrograd have recently become acquainted with a paper by Wood and Mohler (Phil. Mag., April, 1919) on resonance in sodium vapour. When the excitation is produced by D₁, the ratio of intensities of the two resonating lines D₂ and D₁, which is very small when the temperature and density are low, rapidly increases to its normal value 2 with the number of atomic collisions per second. This number is thus given statistical significance. Until now there has been no strong evidence (Wood, 1914) as to its invariability at higher temperatures and pressures.