Effect of enantiomeric excess on surface structures and phase sequences in free-standing liquid-crystal films

We present differential optical reflectivity and null transmission ellipsometry data from several mixtures of MHPBC enantiomers. From this data, we have determined the chiral smectic phase sequence as a function of enantiomeric excess. The data suggest a change in the structure of the smectic-$C_{\alpha }^{*}$ phase and the surface tilt state as the enantiomeric excess is reduced. The results also show that the intermediate phases, smectic $C_{\mathrm{FI}2\mathrm{}}^{*},$ smectic $C_{\mathrm{FI}1\mathrm{}}^{*},$ and smectic $C_{\alpha }^{*},$ disappear sequentially on reducing the net chirality.