Adsorption confinement free energy ($\Delta F_{\mathrm{conf}}=N{k}_{\mathrm{B}}T\ln [V/(A\Lambda )]$)

The translational Helmholtz free energy cost of restricting a dilute ideal gas from a volume $V$ to an area $A$ at the same temperature. For identical particle number and mass,Here $\Lambda$ is the thermal de Broglie wavelength. This contribution is positive for $V/A\gg \Lambda$; a favourable binding energy must be added separately to predict net adsorption.