Light scattering in an ideal defect-free crystalline ( non-metallic ) solid which provides " no scattering centers " for incoming light will be due primarily to any effects of anharmonicity within the ordered lattice.
22.
In a system of oscillators with natural frequencies \ omega _ \ alpha, \ omega _ \ beta, . . . anharmonicity results in additional oscillations with frequencies \ omega _ \ alpha \ pm \ omega _ \ beta.
23.
*Note : Light scattering in an ideal defect-free crystalline ( non-metallic ) solid which provides " no scattering centers " for incoming lightwaves will be due primarily to any effects of anharmonicity within the ordered lattice.
24.
In practice, such plots often give curves because of unaccounted anharmonicity in the potential; furthermore, the low population of the higher states ( or the Franck Condon principle ) makes it difficult to experimentally obtain data at high values of v.
25.
Further examples of anharmonic oscillators include the large-angle pendulum; nonequilibrium semiconductors that possess a large hot carrier population, which exhibit nonlinear behaviors of various types related to the effective mass of the carriers; and ionospheric plasmas, which also exhibit nonlinear behavior based on the anharmonicity of the plasma.
