Characterization of Hexatic Order in Thick Films

This single-domain SmI sample enables one to obtain high quality X-ray data describing the bond-orientational order. In order to characterize the bond-orientational order quantitatively, a nonlinear least-squares fit of the data between 60° and 120° to the following Fourier cosine series [90] 

Here x ll angle between the in-plane component of the scattering vector q and the magnetic field/f. I q is the background term. Below the transition temperature, one expects to see harmonics. The coefficients measure the strength of -fold harmonics. Each of the yields an independent degree of bond-orientational order. The temperature dependence of the first seven members of the set Cf, is obtained from such a fit and plotted in Fig. 17. The results explicitly show that as the temperature decreases the sample smoothly develops first C5 order, then C12 order, then C,g order and so on. This transition evolves smoothly and 

The Cg s are found to satisfy the simple scaling relation [90] The aver- 

2 Physical Properties of Non-Chiral Smectic Liquid Crystals 

DOBAMBC and 4-layer 2M4P80BC films show two separate heat capacity anomalies near their SmC-SmI transitions therefore we believe that only two-layer tilms of DOBAMBC or 2M4P80BC with a single heat capacity peak exhibit two-dimensional behavior. 

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