1ST OBSERVATION OF A PHOTON-INDUCED TRIPLY EXCITED-STATE IN ATOMIC LITHIUM

Using a dual laser plasma technique we have measured for the first tim e the photoabsorption spectrum of atomic lithium at energies correspon ding to the simultaneous excitation of both is electrons. We have obse rved the main triply excited 1s(2)2s(2S) --> 2s(2)2p(2P) transition wi th Fano parameters E0 = 142.32 +/- 0.05 ev, GAMMA = 0.20 +/- 0.04 eV, and q = -2.2 +/- 0.6. Our experiment represents the first step in phot oionization studies of this fundamental atomic system in which the mot ion of the three electrons in the field of the nucleus is so highly co rrelated.