A Comparative Study of Accommodation Coefficients by the Temperature Jump and Low-Pressure Methods and Thermal Conductivities of He, Ne, and CO2

The temperature jump and low pressure methods are used to determine the accommodation coefficients of He, Ne, and CO2 on platinum under conditions as closely identical as compatible with the methods. Agreement is very close for He and for CO2, giving values centering about 0.176 for He and 0.78 for CO2. For Ne the results are ambiguous, giving good agreement with one sequence of preparation and giving temperature jump values 25 percent low with another. Variability is correlated with preparation history and variability with time is noted by both methods. Thermal conductivity values of He, Ne, and CO2 are given and compared briefly with values in the literature.