Direct measurement of picosecond and sub-picosecond phonon lifetimes in α-quartz

Using coherent Raman probe scattering of picosecond laser pulses, excited optical phonons at 465 cm^-1, close to the center of the Brillouin zone are investigated. A 3-phonon decay channel is suggested which accounts for the observed large variation of the phonon lifetime from 3.4 ps to 0.8 ps in the temperature range 23 to 295 K.