Experimental, theoretical and numerical studies of line broadening by disorder: the CO vibrational transition in solid α-(CON2) alloy Original Research Article

Solid α-(CON2) alloy shows a substitutional disorder and an orientational disorder since the CO molecules take their CO or OC orientation at random. This fact leads to diagonal and off diagonal disorder in the description of the vibrational states of this molecular alloy. A simple model of crystal Hamiltonian is proposed to calculate the Raman band shape corresponding to the 0 → 1 vibrational transition of CO. The theoretical predictions allow a qualitative description of the line broadening behaviour over the full concentration range and the numerical results are in good agreement with the experimental data. The respective influence of diagonal and off-diagonal disorder to the line broadening is also discussed.