Commensurate-incommensurate transition of solid krypton monolayers on graphite

Abstract

Low-energy electron-diffraction (LEED) data for the commensurate-incommensurate transition in solid krypton monolayers on graphite are reanalyzed and compared to recent x-ray diffraction data. For the temperature range 52 to 89 K, the mean misfit versus chemical potential change for both sets of data can be expressed as a power law with an exponent of about $\frac{1}{3}$. The critical pressure at which the transition occurs is consistent with ${P}_{c}(T)=(4.5\ifmmode\times\else\texttimes\fi{}{10}^{+9}\mathrm{Torr}) \mathrm{exp}(\ensuremath{-}1990\frac{K}{T})$ for $52<T<123$ K. Analysis of the LEED photographs at 52 K indicates that the krypton monolayer starts to rotate in an apparently second-order transition when the mean misfit exceeds two percent.