Low-temperature adsorption isotherms of3He and para-H2on grafoil and their normalization

✍ Scribed by J. G. Daunt; S. G. Hegde; S. P. Tsui; E. Lerner

• Publisher: Springer US
• Year: 1981
• Tongue: English
• Weight: 415 KB
• Volume: 44
• Category: Article
• ISSN: 0022-2291
• DOI: 10.1007/bf00115083

✦ Synopsis

Measurements have been made of the adsorption isotherms of 3He and of para-hydrogen (p-He), on bare Grafoil, the former in the temperature range 0.88-1.23 K, and the latter in the temperature range 10.0-20.0K. For p-He the quantity of material adsorbed plotted against (p/pO) T yields a single temperature-independent curve, as would follow from the potential theory for multilayer adsorption, and as emphasized by Chester et al. in 1974. The same behavior was found for 3He on Grafoil, except that deviations from a single temperature-independent curve occurred at the higher temperatures. For p-He on Grafoil it is to be noted that the isotherms taken below the triple point of free, bulk p-He fit the same single temperature-independent curve as do the isotherms measured at temperatures between the triple point and the boiling point. From the data, the isosteric heats of adsorption were calculated over a wide range of coverage and this provided further experimental evidence for the similarity between the uppermost layers of thick adsorbed films and the free liquid of the same substance.