OBSERVATION OF OPTICAL RAMSEY FRINGES IN THE 10 µm SPECTRAL REGION USING A SUPERSONIC BEAM OF SF6 Ch. J. Bordé, S. Avrillier, A. Van Lerberghe, Ch. Salomon, D. Bassi et G. Scoles J. Phys. Colloques, 42 C8 (1981) C8-15-C8-19 DOI: 10.1051/jphyscol:1981802