The Fluorescence Spectrum of Sodium Vapor in the Vicinity of the D Lines

Abstract

Excitation of sodium $D$ lines by monochromatic radiation.—When sodium vapor is mixed with hydrogen, air or nitrogen at pressures between 2 and 3 mm it is possible to excite the $D$ lines by radiation in the region 5100 to 5250A. Since this radiation is absorbed only by the sodium molecules it is probable that the primary act is the excitation of the molecule. The excited molecule may then cause the $D$ line emission by collisions of the second kind with atoms, or by dissociating, either spontaneously or as a result of collisions with the foreign gas, into a normal and an excited atom. To distinguish between these processes further experiments are necessary.