(Late Paper)ROTATIONAL ANALYSIS OF ELECTRONIC BANDS OF $La^{18}O$
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Date
1972
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Ohio State University
Abstract
The emission spectrum of $LaO^{18}$ has been photographed at a resolution of at least 300 000 using low and high tension arcs at reduced pressure. The rotational analysis of the green-yellow system is already complete. The fine doubling seen in the spectrum (about $0.5 cm^{-1}$) is attributed to nuclear hyperfine effects. As previously suggested on theoretical basis, added to experimental evidences obtained in the violet system, we can also conclude that the ground state of LaO is $^{2}{\Sigma}$ showing a good example of a $b_{\beta S}$ coupling case. The high tension spectrogramme provides lines with high N values that we used to search for uncoupling leading to $b_{\beta J}$ case without finding it. Analysis of the red system of $LaO^{18}$ is still incomplete, but part of the work leads to lower state combination differences in excellent agreement with those observed in the green-yellow bands. Some branches of the red system have been resolved to very low N values. This fact has been used to check for the features expected for earlier assumption of a $^{4}{\Sigma}$ ground state which would have shown a measurable splitting at such N values. However, this splitting was not detected, and thus this also supports the above mentioned $^{2}{\Sigma}$ ground state conclusion.
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Author Institution: Department of Physics, University of La Plata