Showing papers by "David S. Cannell published in 1976"

Experimental study of a two-dimensional gas-liquid phase transition

Abstract: The surface pressure exerted by a monomolecular layer of pentadecanoic acid spread on a pH-2 distilled-water substrate has been measured as a function of temperature and surface density in the vicinity of the gas-liquid critical point for this two-dimensional system. From these measurements, the shape of the gas-liquid coexistence curve and the isothermal compressibility along both sides of the coexistence curve and above the critical temperature are deduced. In agreement with the findings of Hawkins and Benedek obtained on pure distilled water, we find that a true phase transition exists between the liquid and gaseous states of the film and that the behavior of the film in the vicinity of its critical point can be characterized by power-law behavior with mean-field exponents. We do not, however, find it possible to interpret all of our data in terms of a simple mean-field phase transition.

Accurate method for the simultaneous determination of the thermal conductivity and specific heat of nonconducting solids

Abstract: A relatively simple technique employing a two‐dimensional form of the temperature wave method is described. With reasonable care, both the specific heat and the thermal conductivity may be measured with an accuracy of 1% and a precision of 0.1%. Samples as small as 5×7 mm may readily be studied. The region of the sample in which the measurements are made is quite small and may be maintained isothermal to better than 15 mK, making the method suitable for use near phase transitions. The method should also be useful in applied fields and at high pressures or temperatures.