Thin Hexatic B Films

Using Monte-Carlo simulations, we have investigated the role of herringbone order on the liquid-hexatic transition of nmOBC [42]. Based on the coupled XY Hamilton- 

Heat capacity data from thin 3(10)OBC free-standing films of various thicknesses are shown in Fig. 8. Using information from specular X-ray diffraction [16], electron diffraction [44], and the evolution of this set of 

Although surface enhanced order is commonly found for various liquid crystal transitions, the layer-by-layer transitions have only been characterized in the following five cases the SmA-SmI transition of 90.4 [47], the SmA-SmB ex transition of nmOBC [45], the SmA-SmB ex transition of 54COOBC [48], the SmA-B transition of 40.8 [49] and the SmA-isotropic transition [50, 51]. Thus far the sequence of the transition temperatures can be described by the following simple power law [52]  

2 Physical Properties of Non-Chiral Smectic Liquid Crystals 

Here L gives the separation (measured in units of layers) between the nearest film/ vapor interface and the layer in question. The fittings yield Lq= 0.24 0.01, u=0.37 0.02 for 90.4 [47], Lq=0.31 0.02, u=0.32 0.02 for 3(10)OBC [45], Lq=0.34 0.05, u=0.30 0.05 for 54COOBC [48] andLo=0.32 0.01,u=0.36 0.02 for 40.8 [49]. The experimental data and fitting results near the SmA-SmI transition of 90.4 are shown in Fig. 9. The critical exponent i)= 1/3 indicates that simple van der Waals forces are responsible for the interlayer interaction. Although the layer-by-layer transition near a first order transition has been theoretically predicted [52], that near a second order transition is totally counterintuitive. Further experimental and theoretical work is necessary to address this unresolved puzzle. 

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