Correlation of the Fluorescent and Absorption Spectra of Iodine

The lines near Hg5460 in Wood's fluorescent spectrum of iodine excited by the quartz mercury arc are identified with definite lines in the absorption spectrum. This identification furnishes the key to the analysis of the absorption spectrum. Values of the constants of the iodine spectrum, based on new measurements, are as follows: for the unexcited state ${B_0}^{\prime \prime }=0.037300\mathrm{}\pm 0.000003$, ${I_0}^{\prime \prime }=7.42\mathrm{}\times {10}^{-38\mathrm{}}$ g.${\mathrm{cm}}^2$, ${r_0}^{\prime \prime }=2.66\mathrm{}\times {10}^{-8\mathrm{}}$ cm; for the excited state $B^{\prime }\mathrm{}\left(26\right)=0.023368\mathrm{}\pm 0.000005$, $I^{\prime }\mathrm{}\left(29\right)=11.83\mathrm{}\times {10}^{-38\mathrm{}}$ g.${\mathrm{cm}}^2$, $r^{\prime }\mathrm{}\left(29\right)=3.37\mathrm{}\times {10}^{-8\mathrm{}}$ cm; $C(29, 0)=-0.013932$, ${m_H}^{\prime \prime }(29, 0)=1.677$. The identification, in the absorption bands, of both components of the fluorescent doublets makes possible the calculation of absolute rotation quantum numbers; and these furnish direct evidence for the hypothesis of half quantum numbers. Lines in Wood's magnetic rotation spectrum which show the "normal" direction of rotation are found to belong to $P$ branches; those which show the opposite direction, to $R$ branches.