The relaxation mechanisms of local vibrational modes in solids are of central importance in understanding how such modes decay into phonons, the diffusion of impurities, and the loss of hydrogen passivation in technologically important materials. Interstitial oxygen in silicon is a model system for studying the relaxation of local vibrational modes into extended vibrational modes by measuring the interactions between the two. We have used hydrostatic pressure to bring the antisymmetric stretch mode of Si: 18O i into resonance with the second harmonic of the 18O i resonant mode and observed an anticrossing between the two vibrational modes near pressures of 4 GPa. A theoretical model of this interaction produced excellent agreement with the experimentally observed frequencies and linewidths.
- Local vibrational mode
- Resonant interaction