Fisch, M. R.Sorensen, L. B.Pershan, Peter2013-03-041981Fisch, M. R., L. B. Sorensen, and Peter S. Pershan. 1981. Absolute measurement of the critical properties of second sound at the smectic-A-to-nematic phase transition in 8OCB. Physical Review Letters 47(1): 43–46.0031-9007http://nrs.harvard.edu/urn-3:HUL.InstRepos:10361977Light scattered from the driven free surface of the smectic-A phase of octyloxy cyanobiphenyl (8OCB) provides a low-frequency measurement of second sound. This yields an absolute measurement of the smectic elastic constant, B. There is no dispersion in either the angular or frequency dependence of B for angles \(35^{\circ}-83^{\circ}\) from the normal and for frequencies from 10-100 kHz. Near the smectic-A-to-nematic phase transition the smectic elastic constant can be described by \(B=(6.03 \pm 0.05) \times 10^7 (T_{NA}-T)^{0.32 \pm 0.015} dyn/cm^2\).en-USJournal Article2013-03-0410.1103/PhysRevLett.47.43