Extrapolation of data on adsorbed xenon density in the nanoporous materials. Experimental xenon adsorption isotherm measurements were available in the adsorbents only up to ca. 1 bar (see Fig. ). We fitted the Langmuir adsorption model to this data, then used the Langmuir model to, essentially, extrapolate the adsorption data to pressures much higher than 1 bar. See Fig. . Though we excluded nanoporous materials from our study whose adsorption isotherm data did not exhibit a plateau for reliable estimation of M, this extrapolation could still introduce significant error.