The recent discovery of the new smectic-C(d6)(*) (SmC(d6)(*)) phase [S. Wang et al., Phys. Rev. Lett. 104, 027801 (2010)] also revealed the existence of a noisy region in the temperature window between the SmC(d6)(*) phase and the smectic-C(d4)(*) (SmC(d4)(*)) phase. Characterized by multiple resonant peaks spanning a wide region in Q(Z), the corresponding structure of this temperature window h...

Ultrafast nonthermal melting of femtosecond laser-irradiated germanium was observed directly for the first time using sub-picosecond, 1.54-angstrom x-ray diffraction. Such measurements allow the study of transient atomic motion fundamental to many processes in physics, chemistry, and biology.

A biaxial nematic phase had been predicted with D(2h) symmetry, wherein the mesogen's long and short transverse axes are simultaneously aligned along the two orthogonal, primary and secondary directors, n and m, respectively. The unique low-angle x-ray diffraction patterns in the nematic phases exhibited by three rigid bent-core mesogens clearly reveal their biaxiality. The results of x-ray dif...

Analysis of x-ray diagrams of oriented hydrated cytoplasmic microtubules shows that the tubule wall extends from about 70 to 150 A radially. The central region of the wall appears homogeneous, but the outside surface is subdivided by vertical grooves separating the 13 protofilaments and by a steep 10-fold family of grooves. The inside surface is dominated by the 10-start grooves with no clear s...

Grazing-incidence x-ray diffraction measurements were carried out to observe the surface structure of [bmim][PF(6)]. At an incident angle of less than the critical angle, a diffraction pattern from 10 nm beneath the surface was obtained. A broad Debye-Scherrer ring was observed in the diffraction patterns, indicating that the [bmim][PF(6)] molecules near the surface are randomly orientated, sim...

In those cases where charge-stripe order has been observed in cuprates, the crystal structure is such that the average rotational symmetry of the CuO2 planes is reduced from fourfold to twofold. As a result, one could argue that the reduced lattice symmetry is essential to the existence of stripe order. We use pressure to restore the average fourfold symmetry in a single crystal of La1.875Ba0.1...

The atomic-scale structure of germanium diselenide (GeSe(2)) glass has been revisited using a combination of high-energy x-ray diffraction and constrained reverse Monte Carlo simulations. The study shows that the glass structure may be very well described in terms of a continuous network of corner- and edge-sharing Ge-Se(4) tetrahedra. The result is in contrast to other recent studies asserting...

Determination of a macromolecular structure using x-ray diffraction is a multistep process that involves a plethora of techniques involving molecular biology, bioinformatics, and physical sciences. Counterintuitively, the success of any or all individual steps does not guarantee the success of the overall process. This review examines the difficulties presented by each step on the path from a g...

Using an in situ combination of tensile tests and x-ray diffraction, we have determined the mechanical properties of both the crystalline and the disordered phase of the biological nanocomposite silk by adapting a model from linear viscoelastic theory to the semicrystalline morphology of silk. We observe a strong interplay between morphology and mechanical properties. Silk's high extensibility ...

We have utilized resonant x-ray diffraction at the Mn L(II,III) edges in order to directly compare magnetic and orbital correlations in Pr0.6Ca0.4MnO3. Comparing the widths of the magnetic and orbital diffraction peaks, we find that the magnetic correlation length exceeds that of the orbital order by nearly a factor of 2. Furthermore, we observe a large (approximately 3 eV) spectral weight shif...