Role of the Pressure Transmitting Medium for the Pressure Effects in Single-Walled Carbon Nanotubes

We present the pressure-dependent infrared absorbance spectra of unoriented single-walled cat-boil nanotube films for pressures Lip to 8 GPa. Various pressure transmitting media (helium, argon, CsI, and alcohol mixture) were employed to verify the influence of the pressure medium on the observed pressure effects. For all pressure transmitting media, a pressure-induced redshift of the absorption bands is observed, with all anomaly at the critical pressure P-c = 2-3 GPa. This anomaly can be attributed to the circular-to-oval structural phase transition. The pressure transmitting medium Only affects the results quantitatively, namely, the value of P-c and the broadening of the bands.