Knowledge Bank

“The first spectra of all the noble gases have been observed, described, and interpreted in the 4 $\mu$ region. Except for scattered Ritzian combinations of levels of different origin, the observed features are accounted for as transitions between levels originating in the 4f and 5g configurations respectively. By application of theoretical formulas developed by Shortley and $Fried,1$ by $Racah,2$ and by $Eriksson,2$ the 5g levels of Ne I, Ar I, and Kr I may be shown to be examples of pair coupling completely developed within the limits of observational error. The significant energy parameters which provide a shorthand coded presentation of the energy levels are tabulated as follows: [FIGURE] The 5g levels of Xe I have been established by identification of the pair differences associated with, the 4f levels. In this instance the departure from pair coupling will require a. more treatment.”