Optical Phonon Lifetime Measured Directly with Picosecond Pulses

Abstract

The lifetime of the 1086-${\mathrm{cm}}^{\ensuremath{-}1}$ optical phonon in calcite is measured directly to be 8.5 \ifmmode\pm\else\textpm\fi{} 2 psec at 297\ifmmode^\circ\else\textdegree\fi{}K and 19.1 \ifmmode\pm\else\textpm\fi{} 4 psec at 100\ifmmode^\circ\else\textdegree\fi{}K by using a picosecond laser beam to create the phonons by stimulated Raman scattering, and then observing Raman scattering off the phonons at various delay times with a weaker picosecond beam at another frequency.