Pressure effects on single wall carbon nanotube bundles

We report high pressure Raman studies on single wall carbon nanotube bundles under hydrostatic conditions using two different pressure transmitting media, alcohol mixture and pure water. The radial and tangential modes show a blue shift when SWNT bundle is immersed in the liquids at ambient pressures. The pressure dependence of the radial modes is the same in both liquids. However, the pressure derivatives d omega /dP of the tangential modes are slightly higher fur the water medium. Raman results are compared with studies under non-hydrostatic conditions and with recent high-pressure X-ray studies. it is seen that the mode frequencies of the recovered sample after pressure cycling from 26 GPa are downshifted by similar to7-10 cm(-1) as compared to the starting sample.