Temperature Dependence of Hydrogen Adsorption Isotherms

In the past it has already been shown that adsorption isotherms of liquid or solid lms are not described completely by the Frenkel Halsey Hill theory. Substrate roughness as well as thermal uctuations have to be taken into account in understanding the adsorption behavior. The inclusion of thermal uctuations into the adsorption theory has already been addressed and proven to provide an explanation for the deviations found in many experiments. However, a resulting temperature dependence of such isotherms has not yet been veri ed. In our investigations we have addressed this issue with a series of adsorption isotherms of hydrogen on gold in a temperature range from 11K to 19.5K (i.e., below and above the triple-point temperature of hydrogen). Our measurements are compared with existing theories and the nature of the remaining discrepancies is discussed. PACS numbers: 68.08Bc, 68.15+e, 68.43 h