Differential scanning calorimetry and temperature-modulated differential scanning calorimetry:: an extension to lower temperatures

Temperature-modulated differential scanning calorimetry (TMDSC) has become a versatile technique for determining the specific heat (c(p)) properties of condensed matter, but commercial instruments do not allow TMDSC measurements below 130 K. A top-loading cryostat incorporated within a commercial TMDSC instrument is presented, which allows c(p) measurements down to about 80 K with the use of liquid nitrogen as a coolant. As a consequence of the optimised thermodynamic properties of the heat exchanger the coolant consumption is appreciably low; the consumption of nitrogen at 90 K is below 1 l h(-1). The power of this new TMDSC unit will be demonstrated by the presentation of c(p) results measured on two test materials at intermediate low temperatures, namely sapphire because of its well-known c(p) data, and 2-methylpentane.