The Fine Structure of the Sharp Series Triplet,2P0,1,23−2S13, of Optically Excited Mercury Radiation

Measurements on the fine structure of the sharp series triplet, lines of wavelengths $\lambda \lambda 5461$, 4358 and 4047 were made with two Lummer-Gehrcke plates under two conditions of optical excitation. The first condition of optical excitation was obtained by having mercury vapor only in the resonance tube, giving excitation by absorption of $\lambda 4358$, the second by having mercury vapor with nitrogen present at a pressure of 2 to 4 mm, giving excitation by absorption of both $\lambda 4358$ and $\lambda 4047$. For the first condition of excitation the wave-length differences in milli-angstroms are for $\lambda 5461$, $d\lambda 0$; for $\lambda 4358$, $d\lambda -157\mathrm{}$, -107, -20, 0, +30, +46, +183; for $\lambda 4047$, $d\lambda -116\mathrm{}$, -62, -52, 0. For the second condition the wave-length differences are for $\lambda 5461$, $d\lambda -235\mathrm{}$, 0; for $\lambda 4358$, $d\lambda -107\mathrm{}$, -20, 0, +30, +183; for $\lambda 4047$, $d\lambda -110\mathrm{}$, -62, -53, 0. Certain fine structure energy differences of interest in the construction of energy diagrams are pointed out but it was not found possible with the data available to construct a complete energy diagram of the triplet. A comparison of the fine structure observed under the two conditions of optical excitation with one another and with the fine structure of the arc shows striking differences which make it evident that differences in fine structure exist which depend on the method of excitation.