Sirota, E. B.Pershan, PeterSorensen, L. B.Collett, J.2013-03-011987Sirota, E. B., Peter S. Pershan, L. B. Sorensen, and J. Collett. 1987. X-ray and optical studies of the thickness dependence of the phase diagram of liquid-crystal films. Physical Review A 36(6): 2890-2901.1050-29471094-1622http://nrs.harvard.edu/urn-3:HUL.InstRepos:10357473A comprehensive study of the thickness dependence of the phase diagram of freely suspended films of the liquid crystal 4-n-heptyloxybenzylidene-4-n-heptylaniline (7O.7) between \(50 and 69^{\circ}C\) is reported. In thick films (thicker than about 300 layers and characteristic of bulk samples) there is a low-temperature crystalline-G phase followed by five crystalline-B phases with different stacking arrangements at higher temperatures. In thinner films there are two additional crystalline-B phases and two tilted hexatic phases, smectic-F and smectic-I, which do not appear in bulk samples. The in-plane and interlayer correlations in the tilted hexatic phases are anisotropic with a clear dependence on the molecular tilt direction; the in-plane correlations are more developed (longer range) perpendicular to the molecular tilt direction and the interlayer correlations are more developed parallel to the tilt direction.en-USJournal Article2013-03-0110.1103/PhysRevA.36.2890