Orientational ordering in argon-diluted nitrogen films adsorbed on graphite

The orientational ordering in dilute nitrogen films ${\left({\mathrm{N}}_2\right)}_{1-x}{\mathrm{Ar}}_x$ is studied using high-precision heat-capacity techniques. In the submonolayer regime, significant depression in the transition temperature $T_c\mathrm{}\left(x\right)\mathrm{}$, decrease in height and increase in width of the heat capacity peaks are seen upon slight addition of Ar impurities. Mean-field theory is used to analyze the results.