HEATING AND COOLING OF LOCAL AND QUASILOCAL VIBRATIONS BY A NONRESONANCE FIELD.

The dynamics of an anharmonic oscillator interacting with phonons in a nonresonant quasimonochromatic field is studied. The field-induced decay effects alter considerably the effective oscillator temperature. When an induced decay corresponds to simultaneous excitation of the oscillator and creation of a phonon, a runaway effect occurs for strong pumping, i. e. , the oscillator energy increases exponentially with time. Mechanisms limiting the runaway effect are proposed. The limiting mechanisms lead to an inverse population of the oscillator levels in a certain energy interval. The luminescence and absorption spectra corresponding to local and quasilocal vibrations are studied. For an inverted population, the anharmonic vibrations can amplify light near the fundamental absorption frequency. If the frequency of the pumping field is higher than the oscillator frequency, the pumping field amplifes light and phonons at the difference frequency.