FOUR-WAVE MIXING TECHNIQUE AND COHERENCE EFFECT ON ELECTRONIC STATES OF DYE MOLECULE M.T. PORTELLA, P. MONTELMACHER, A. BOURDON, P. EVESQUE and J. DURAN J. Phys. Colloques, 48 C7 (1987) C7-521-C7-523 DOI: 10.1051/jphyscol:19877124