I22 Transmission SAXS/WAXS

Transmission mode is the most common mode we run on I22. It includes use of the bimorph mirrors for standard focusing. It is possible to run a "collimated" mode for some Transmission SAXS/WAXS experiments including our f-switch. This involves using our bimorph mirrors to focus on the secondary source point, installed as part of phase 1 of the BCO upgrade recently carried out. The beam then expands onto the f-switch which comprises all of our CRL's (100 lenses) where the requisite number are introduced to the beam to ensure "collimated" mode for a given energy, e.g. 19 for 12.4keV. Both Pilatus detectors are available in transmission mode with overlap in q-scale between detectors possible for isotropic configuration out to 9m cameras, q_min0.003Å^-1, approx. 5000Å or 500nm.

A polymethylsiloxane (PMS) liquid crystal with rod-like aromatic side-groups forms a unique cubic structure: a four-network gyroid (4NG), where each network splits into two aromatic strands winding around the polysiloxane core as double helices. Unlike typical LC double gyroids, the helix twist in 4NG is opposite to the subspace. X-ray, DSC, and DF analyses reveal reversible changes in mixing between side groups and backbones at 120–130 °C, and increased system mobility only occurs about 40 °C above melting, suggesting persistent local double helices in the melt.

Gyroid Labyrinth of Supertwisted Double Helices in a Liquid Crystal Polymer

Tang, Y., Xue, Y.-.n., Yang, S.-.G., Zhang, R., Liu, F., Zeng, X. & Ungar, G.

Angewandte Chemie International Edition, 2025, Pages e22314

DOI: 10.1002/anie.202522314