The Sodium and Potassium Absorption Bands

Abstract

Vibrational relations.—Formulas for the heads of the bands are: $\mathrm{Green} {\mathrm{Na}}_2: \nu =20301.62+(123.84\mathrm{}{n}^{\prime }-0.79\mathrm{}{n}^{\prime 2})-(157.57\mathrm{}{n}^{\prime \prime }-0.57\mathrm{}{n}^{\prime \prime 2})$ $\mathrm{Red} {\mathrm{Na}}_2: \nu =15006.68+(115.69\mathrm{}{n}^{\prime }-0.427\mathrm{}{n}^{\prime 2})-(157.81\mathrm{}{n}^{\prime \prime }-0.538\mathrm{}{n}^{\prime \prime 2})$ $\mathrm{Near}\mathrm{red} {\mathrm{K}}_2: \nu =15368.63+(74.58\mathrm{}{n}^{\prime }-0.30\mathrm{}{n}^{\prime 2})-(92.01\mathrm{}{n}^{\prime \prime }-0.34\mathrm{}{n}^{\prime \prime 2})$ Since the coefficients of the $n^{\prime \prime }$ terms for the green and red ${\mathrm{Na}}_2$ bands are the same, the two systems must have the same initial state (${}_{}{}^1{}_{}{}^{}S$) in absorption. The similarity of the green ${\mathrm{Na}}_2$ and the near red ${\mathrm{K}}_2$ band systems is pointed out. The $n^{\prime }$ progressions are very large for small $n^{\prime \prime }$ values, especially in the red ${\mathrm{Na}}_2$ system.