First observation of E2 coherent phonon modes in CdS using a noncollinear optical parametric amplifier

Abstract

We report the first observation of E2 coherent phonon modes in CdS using a noncollinear optical parametric amplifier. We studied the intensity, temperature and excitation energy dependences of the high- and low-frequency E2 modes. We obtain that generation mechanism under non- and near resonant regions is impulsive stimulated Raman scattering (ISRS) and E 2 modes are barely affected by Fröhlich interaction. As temperature increases, E2 modes are affected by anharmonic effect. The observed phonon lifetime of the low- and high-E2 modes in CdS is 243 37 and 11.4 0.4 ps, respectively, at 83 K. From fitting, we can estimate the lifetime of the high-E2 mode at the low-temperature limit to be 49.3 ps. © 2009 IOP Publishing Ltd.