OBSERVATION OF THE 5dnl EVEN DOUBLY-EXCITED STATES IN NEUTRAL BARIUM USING TWO-STEP OPTOGALVANIC SPECTROSCOPY P. Camus, M. Dieulin et A. El Himdy J. Phys. Colloques, 44 C7 (1983) C7-271-C7-274 DOI: 10.1051/jphyscol:1983724