New infrared absorption bands of sodium vapor

Abstract

We have seen a new region of absorption in saturated sodium vapor in the infrared region of the spectrum (0.83–2.5 μ). The absorption from 0.83 to 1.18 μ may be the analog of the ultraviolet emission continuum of H2, possibly arising from the sodium dimer (3Σu+→3Σg+) transition, along with contributions from higher sodium polymers. Absorption at longer wavelength is most likely due to higher polymers of sodium (Na3, Na4,...).