Decay Time of Hot TO Phonons in Diamond

For a duration of several times ${10}^{-12\mathrm{}}$ sec, TO modes are excited to an occupation number exceeding the equilibrium value (at 300°K) by more than thirteen orders of magnitude. The relaxation times of these phonos are measured directly and found to agree with the known anharmonic decay at low power level. Phonon breakdown is not significant in our experiments.