Fast scanning calorimetry-fast thermal desorption technique: The thin wire approach

Abstract

For the first time, we give an exceptionally detailed description of the fast scanning calorimetry (FSC) apparatus developed in our laboratory at the George Washington University. Our experimental approach is based on using a thin (10 µm in diameter) filament for vapor deposition of bulk-like and ultrathin films of model organic glass formers and noncrystalline aqueous phases at temperatures from 95 to 180 K. These samples are then subjected to rapid heating with rates in excess of 105 K/s, and the effective heat capacity is measured as a function of temperature. Because the filament acts simultaneously as both a heater and a temperature sensor, the FSC apparatus utilizes a very simple design for data acquisition and other systems. We discuss the fundamental advantages of our FSC approach, describe new temperature calibration procedures and other instrumental tests, point out potential pitfalls and experimental design mistakes, and illustrate the capabilities of the FSC approach with selected results from our most recent studies.