High-pressure Raman and photoluminescence of highly anisotropic CdS nanowires

Raman and photoluminescence of CdS nanowires of diameter 80 nm and lengths up to several tens of micrometers were studied at pressure up to 60 kbar using a Jobin-Yvon T64000 micro-Raman system in conjunction with the diamond-anvil cell technique. The phase transition pressure of wurtzite to rock salt was observed at 38 kbar, which is higher than that of bulk CdS. In contrast with the transition pressure of different-sized CdS nanocrystal, this elevated phase transition pressure cannot be explained well by the size effect. Thus the contribution of particle morphology of such a system, which represents the low-energy surface structure, should be considered. The pressure dependence of photoluminescence is also discussed. Copyright (C) 2007 John Wiley & Sons, Ltd.