Smekhova Alevtina, Novotná Vladimíra, Fekete Ladislav, Abrudan Radu, Fondell Mattis, Hamplová Věra, Ostrovskii Boris I
Helmholtz-Zentrum Berlin für Materialien und Energie, Berlin 12489, Germany.
Institute of Physics of the Czech Academy of Sciences, Prague 8, Czech Republic.
Soft Matter. 2021 Dec 22;18(1):89-96. doi: 10.1039/d1sm01543e.
The spontaneous formation of chiral structures offers a variety of liquid crystals (LC) phases that could be further tailored for practical applications. In our work, the characteristic features of spiral ordering in the cholesteric phase of EZL10/10 LC were evaluated. To disclose resonant reflections related to a nanoscale helix pitch, resonant soft X-ray scattering at the carbon K edge was employed. The angular positions of the observed element-specific scattering peaks reveal a half-pitch of the spiral ordering /2 ≈ 52 nm indicating the full pitch of about 104 nm at room temperature. The broadening of the peaks points to a presence of coherently scattering finite-size domains formed by cholesteric spirals with lengths of about five pitches. No scattering peaks were detectable in the EZL10/10 isotropic phase at higher temperatures. The characteristic lengths extracted from the resonant soft X-ray scattering experiment agree well with the periodicity of the surface "fingerprint" pattern observed in the EZL10/10 cholesteric phase by means of atomic force microscopy. The stability of LC molecules under the incident beam was proven by X-ray absorption spectroscopy in transmission geometry.
手性结构的自发形成提供了多种液晶（LC）相，这些相可以进一步定制以用于实际应用。在我们的工作中，评估了EZL10/10液晶胆甾相螺旋排列的特征。为了揭示与纳米级螺旋螺距相关的共振反射，采用了碳K边的共振软X射线散射。观察到的元素特异性散射峰的角位置揭示了螺旋排列的半螺距 /2 ≈ 52 nm，表明在室温下全螺距约为104 nm。峰的展宽表明存在由长度约为五个螺距的胆甾螺旋形成的相干散射有限尺寸域。在较高温度下的EZL10/10各向同性相中未检测到散射峰。从共振软X射线散射实验中提取的特征长度与通过原子力显微镜在EZL10/10胆甾相中观察到的表面“指纹”图案的周期性非常吻合。通过透射几何中的X射线吸收光谱法证明了LC分子在入射光束下的稳定性。
