VIBRATIONAL MODES IN A ONE DIMENSIONAL "QUASI-ALLOY" : THE MORSE CASE F. AXEL, J.P. ALLOUCHE, M. KLEMAN, M. MENDES-FRANCE et J. PEYRIERE J. Phys. Colloques, 47 C3 (1986) C3-181-C3-186 DOI: 10.1051/jphyscol:1986318