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Full-Text Articles in Chemistry
Smectic-A —Smectic-C* —Smectic-C Multicritical Point In Ferroelectric Liquid Crystals, Shankar B. Rananavare, V. G. K. M. Pisipati, E. W. Wong
Smectic-A —Smectic-C* —Smectic-C Multicritical Point In Ferroelectric Liquid Crystals, Shankar B. Rananavare, V. G. K. M. Pisipati, E. W. Wong
Chemistry Faculty Publications and Presentations
We report a smectic-A–smectic-C–smectic-C* (ACC*) multicritical point in mixtures of chiral DOBAMBC [p-(n-decyloxybenzylidene)-p-amino-(2-methyl-butyl)] cinnamate and achiral 10O.8 (4-decyloxybenzylidene-4-octylaniline). Studies of the phase diagram, tilt angle (θ), polarization (P), and helix pitch (p) indicate an ACC* Lifshitz point that can be described in terms of the extended Landau theory. Specifically, the T*AC and the maximum polarization (Pm) exhibit quadratic composition dependence while the helical pitch length (p=2π/q) varies linearly. Both q and Pm vanish discontinuously at the C-C* …
Structure And Phase Transition Of The 6,5-Annulene Isomer Of C_{61}H_{2}, Andrea N. Lommen, Paul A. Heiney, Gavin B. M. Vaughan, Peter W. Stephens, Dengfa Liu, Dayin Li, Allan L. Smith, Andrew R. Mcghie, Robert M. Strongin, Laurent Brard, Amos B. Smith Iii
Structure And Phase Transition Of The 6,5-Annulene Isomer Of C_{61}H_{2}, Andrea N. Lommen, Paul A. Heiney, Gavin B. M. Vaughan, Peter W. Stephens, Dengfa Liu, Dayin Li, Allan L. Smith, Andrew R. Mcghie, Robert M. Strongin, Laurent Brard, Amos B. Smith Iii
Chemistry Faculty Publications and Presentations
We have used differential scanning calorimetry and x-ray diffraction to study the crystalline phases of the 6,5-annulene isomer of C61H2. At 308 K the methylenated fullerenes are orientationally disordered in a face-centered cubic lattice with lattice parameter 14.19±0.02 Å. Below Tc=290 K the symmetry is lowered to Pa3¯, a simple-cubic structure. At 20 K the lattice parameter is 14.06±0.02 Å, with substantial statistical disorder remaining. The transition temperature in C61H2 is slightly higher than in C60O and higher still than in C60, but the three compounds exhibit orientationally …
Neutron-Scattering Study Of Librations And Intramolecular Phonons In Rb_{2.6}K_{0.4}C_{60}, D. Reznik, W. A. Kamitakahara, D. A. Neumann, J. R. D. Copley, J. E. Fischer, Robert M. Strongin, M. A. Cichy, Amos B. Smith Iii
Neutron-Scattering Study Of Librations And Intramolecular Phonons In Rb_{2.6}K_{0.4}C_{60}, D. Reznik, W. A. Kamitakahara, D. A. Neumann, J. R. D. Copley, J. E. Fischer, Robert M. Strongin, M. A. Cichy, Amos B. Smith Iii
Chemistry Faculty Publications and Presentations
We report the results of inelastic neutron-scattering measurements on Rb2.6K0.4C60. Librational modes were observed as broad peaks with maxima between 4.1 and 4.7 meV, as the temperature is lowered from 300 to 12 K. As in K3C60, no change in the width or position of the librational peak was observed when the sample was cooled through the superconducting transition. Thus any coupling of the librations to electronic states is small. The magnitude of the orientational potential barrier was estimated from the librational peak frequency. A flat background observed in the …