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Self-assembly of fractal liquid crystal colloids
摘要： Nematic liquid crystals are anisotropic fluids that self-assemble into vector fields, which are governed by geometrical and topological laws. Consequently, particulate or droplet inclusions self-assemble in nematic domains through a balance of topological defects. Here, we use double emulsions of water droplets inside radial nematic liquid crystal droplets to form various structures, ranging from linear chains to three-dimensional fractal structures. The system is modeled as a formation of satellite droplets, distributed around a larger, central core droplet and we extend the problem to explain the formation of fractal structures. We show that a distribution of droplet sizes plays a key role in determining the symmetry properties of the resulting geometric structures. The results are relevant to a variety of inclusions, ranging from colloids suspensions to multi-emulsion systems. Such systems have potential applications for novel switchable photonic structures as well as providing wider insights into the packing of self-assembled structures.
关键词： Self-assembly,Fractal structures,Topological defects,Colloids,Liquid crystals
更新于2025-09-23 15:22:29
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Semiclassical theory of laser-assisted radiative recombination
摘要： We study the process of laser-assisted radiative recombination of an electron with a proton by using a semiclassical approach involving calculation of classical trajectories in combined laser and Coulomb fields. Due to chaotic scattering in the combined fields, the radiation probability as a function of the impact parameter and the constant phase of the laser field exhibits chaotic behavior and fractal structures. We obtain a strong enhancement of the recombination cross section as compared to the laser-free case due to the Coulomb focusing effect. For sufficiently low incident electron velocities the cross section becomes infinite, and we limit it by assuming a finite laser pulse duration. With the pulse duration tp = 5 ps we obtain the gain factor for capture into the ground state of the hydrogen atom of about 220 for infrared fields in the intensity range 109–1012 W/cm2. The gain factor grows with tp but slower than linearly.
关键词： chaotic scattering,fractal structures,semiclassical approach,Coulomb focusing effect,laser-assisted radiative recombination
更新于2025-09-23 15:21:01
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Fourier Optics of Fractal Structures
摘要： The scaling characteristics of Fourier spectra of fractal structures are determined. Their stability and influence on cognitive processes associated in particular with the aesthetic aspects of perceiving objects with self-similarity criteria are estimated. Evidence of their heuristic importance for Fourier analysis results is presented using an example in which the properties of aperiodic multilayer structures and chaotic processes are considered.
关键词： scaling characteristics,fractal structures,aperiodic multilayer structures,Fourier optics,cognitive processes,chaotic processes
更新于2025-09-04 15:30:14