Emission Spectra of Alkali-Metal Molecules Observed with a Heat-Pipe Discharge Tube

Abstract
Intense molecular emission spectra from vapors of each of the alkali metals with the exception of lithium have been observed using a new device, the heat‐pipe discharge tube. For Na2, K2, and Br2 the total emission appears to be almost entirely comprised of transitions 1 Σ u + → 1 Σ g + from the first excited singlet state. For Cs2, emission from a low‐lying 3 Π u state appears to contribute as well.