Knowledge Bank

By a joint effort of three research groups (National Bureau of Standards, Washington, D.C.; Instituto de Optica ""Daza de Vald\’{e}s"", Madrid; Zeeman Laboratory, Amsterdam) the analysis of the Re are spectrum has been improved and extended to include 2769 classified lines in the spectral region 1700-12000\AA. To the existing level system 12 low even, 3 high even and 46 odd levels could be added, so that there are now 51 low even, 20 high even and 212 odd levels known. Thanks to extensive Zeeman effect observations on plates obtained at the M.I.T Spectroscopy Laboratory g-values could be evaluated for 75% of all levels. These confirmed most of the earlier identifications, but a few had to be changed and many levels could be interpreted for the first time. In the ground systems the evidence for $5d7$-levels has not been confirmed. In the high even group the term $5d46s2(5D)7s6D$ was detected except the level $\mathrm{<mrow\; data-mjx-texclass="ORD">6</mrow>}D1/2$. In the odd group the $\mathrm{<mrow\; data-mjx-texclass="ORD">6</mrow>}D$ and $\mathrm{<mrow\; data-mjx-texclass="ORD">6</mrow>}F$ terms from $5d46s2(5D$) could be located and also $5d56s(5G)6p6G$ in close agreement with the low position of the $\mathrm{<mrow\; data-mjx-texclass="ORD">5</mrow>}G$ parent term in Re II and with correspondingly irregular spacings. A few $\mathrm{<mrow\; data-mjx-texclass="ORD">6</mrow>}D$-levels derived from the parent term $5d56s5P$ have been detected. The spectrum is characterized by wide hyperfine structure patterns which were used as additional evidence for the correctness of the classifications.