Max Planck Institute for Biophysical Chemistry, Am Fassberg 11, 37077 Göttingen, Germany.
Laser-Laboratorium Göttingen e. V., Hans-Adolf-Krebs-Weg 1, 37077 Göttingen, Germany.
Int J Mol Sci. 2009 Nov 4;10(11):4754-4771. doi: 10.3390/ijms10114754.
Home-based soft X-ray time-resolved scattering experiments with nanosecond time resolution (10 ns) and nanometer spatial resolution were carried out at a table top soft X-ray plasma source (2.2-5.2 nm). The investigated system was the lyotropic liquid crystal C(16)E(7)/paraffin/glycerol/formamide/IR 5. Usually, major changes in physical, chemical, and/or optical properties of the sample occur as a result of structural changes and shrinking morphology. Here, these effects occur as a consequence of the energy absorption in the sample upon optical laser excitation in the IR regime. The liquid crystal shows changes in the structural response within few hundred nanoseconds showing a time decay of 182 ns. A decrease of the Bragg peak diffracted intensity of 30% and a coherent macroscopic movement of the Bragg reflection are found as a response to the optical pump. The Bragg reflection movement is established to be isotropic and diffusion controlled (1 micros). Structural processes are analyzed in the Patterson analysis framework of the time-varying diffraction peaks revealing that the inter-lamellar distance increases by 2.7 A resulting in an elongation of the coherently expanding lamella crystallite. The present studies emphasize the possibility of applying TR-SXRD techniques for studying the mechanical dynamics of nanosystems.
采用具有纳秒时间分辨率（10 ns）和纳米空间分辨率的台式软 X 射线等离子体源（2.2-5.2 nm），进行了基于家庭的软 X 射线时间分辨散射实验。所研究的系统是溶致液晶 C(16)E(7)/石蜡/甘油/甲酰胺/IR 5。通常，样品的物理、化学和/或光学性质的主要变化是由于结构变化和收缩形态而发生的。在这里，这些效应是由于在红外区域的光激光激发下，样品中的能量吸收而产生的。液晶在几百纳秒内显示出结构响应的变化，表现出 182 ns 的时间衰减。发现布拉格峰衍射强度降低了 30%，布拉格反射的相干宏观运动作为光泵的响应。布拉格反射运动被确定为各向同性和扩散控制（1 微秒）。通过时变衍射峰的 Patterson 分析框架分析结构过程，发现层间距离增加了 2.7 A，导致相干扩展层状微晶的伸长。本研究强调了应用 TR-SXRD 技术研究纳米系统力学动力学的可能性。
