Frequency dependent dielectric investigations of polycarbonate from 40 mK to 300 K at hydrostatic pressures

We measured the dielectric response, epsilon'(omega) + i epsilon"(omega), o f polycarbonate (PC) at various frequencies (1-200 kHz) in the temperature range between 40 mK and 300 K. Under the application of hydrostatic pressur e (up to 0.6 GPa) the low temperature properties due to two level tunnellin g systems could be examined as well as thermally activated processes in the high temperature regime. (C) 1999 Elsevier Science B.V. All rights reserve d.