Measurements of the Molecular Absorption Cross Section and the Photoionization of Sodium Vapor between 1600 and 3700 Å

Abstract

The absorption cross section of molecular sodium has been measured, using photoelectric techniques, from 1600 to 3700 Å. The bandwidth of the monochromator was 0.75 Å and values of the cross section were obtained at 2 Å or smaller intervals. The photoionization of sodium vapor was also investigated and the ionization potential of the molecule was found to be 4.90±0.01 eV. Ion peaks were observed at energies corresponding to the 3s¹S₀—np²P₀ series lines. A discussion of this phenomenon is given with reference to results obtained by other workers for the alkali metals. The conclusion reached is that the ground states of the molecular ions are more stable than the corresponding neutral ground molecular states.