Generation of high-frequency phonons by defect-induced one-phonon absorption

By defect-induced one-phonon absorption of pulsed infrared radiation, we excited in diamond phonons at 28 THz. Their anharmonic decay leads to nonthermal frequency distributions of acoustic phonons which we investigated in a frequency range between 0.5 THz and 6 THz by use of vibronic sideband spectroscopy.