Fine and hyperfine structure of the Li- spectrum

The fine and hyperfine structures of the doubly excited, quintet states of the Li-7 ion are of comparable magnitude. This leads to strong second-order hyperfine corrections and to significant distortion of the Landé interval rule. We discuss the results of our many-body calculations in this system, and also in the analogous lithium quartet systems for which experimental data exist. We find that the hyperfine matrix elements of these few-electron systems may be adequately computed without detailed consideration of the electron correlations. Fine structure is significantly affected by such correlations. Experimental verification of the Li- structure is underway. © 1984 The American Physical Society