Based on the model polyimide systems the principal nonlinear optical features, such as laser induced refractive indices changes, nonlinear refraction and third order susceptibility have been established during their doping with fullerenes, shungites, carbon nanotubes, carbon nanofibers, quantum dots, etc. The evidence of the correlation between laser induced refractive indices and charge carrier mobility has been obtained. The features of new nanocomposites for their possible optoelectronics, laser techniques and solar energy applications have been considered.
A potassium bromide (KBr) material, which has been widely used as the key element in Fourier spectrometers and as the output window of the IR-lasers, was studied via applying carbon nanotubes in order to modify the potassium bromide surface. The laser-oriented deposition method was used to place the carbon nanotubes at the matrix material surface in the vertical position at different electric fields varying from 100 to 600 V × cm−1. The main idea of the improvement of the spectral properties of the potassium bromide structure is connected with the fact that the refractive index of the carbon nanotubes is substantially less than the refractive index of the studied material, and the small diameter of the carbon nanotubes allows one to embed these nano-objects in the voids of the lattice of the model matrix systems. Moreover, the mechanical characteristics and wetting features of potassium bromide structures have been investigated under the condition mentioned above. Analytical and quantum-chemical simulations have supported the experimental results.
В настоящей работе рассмотрены временны́е параметры (время реакции и релаксации среды) жидкокристаллической ячейки, сенсибилизированной наночастицами WS 2 и сконструированной с учетом модификации проводящего покрытия ITO углеродными нанотрубками. Углеродные нанотрубки осаждались на поверхность проводящего слоя вертикально с применением лазерного метода и ориентационного воздействия электрического поля с напряженностью 600 В/см. Использование двух управляющих функций, а именно процесса сенсибилизации объема мезофазы и наноструктурирование поверхности раздела твердое тело-жидкий кристалл, позволило повысить быстродействие переключения мезофазы и существенно снизить сопротивление проводящих слоев, выполняющих роль ориентанта и проводника. Ключевые слова: жидкие кристаллы, процесс сенсибилизации мезофазы, наночастицы WS 2 , рельеф поверхности границы раздела, углеродные нанотрубки, лазерный ориентированный метод осаждения.
Abstract. The advanced investigations of π-conjugated organic molecule COANP sensitized with fullerenes have been revealed to consider this system as an affective medium for optical limiting and phase modulation. The special accent has been given to influence of the nanostructured relief at the interface on the spectral and photoconductive features. IntroductionMaterials with π-conjugated organic molecules [1][2][3][4] are ones of the perspective media used for optical modulators, in particular for optical limiter. These materials can be polarized at a distance more than molecules dimension that leads to the appearance of nonlinear properties of the medium.In our previous works [5,6] we have considered the optical limiting properties of 2-cyclooctylamino-5-nitropyridine (COANP) solution doped with fullerenes C 70 . Experiments demonstrated the limiting of the laser radiation with energy density from 0.1 J/cm 2 up to 0.6 J/cm 2 . We have obtained the maximum attenuation of the laser radiation with energy density of 0.35 J/cm 2 for the solution COANP-C 70 with fullerene content of 20 wt.%. The energy value passed through solution has been decreased up to 18 times.Reverse saturable absorption (RSA) and the complex formation process have been considered as the main mechanisms responsible for the optical limiting (OL) of COANP-C 70 system. The RSA mechanism, as the first one, is based on a difference in cross section for excited state of the fullerene molecule and unexcited ones. The cross section of singlet-triplet excited states in the fullerene is larger than the one of the unexcited molecule. The population of excitation levels increases with laser energy increase, so absorption increases as well.The complex formation process, as the second OL mechanism, is corresponded to the following reason. Intermolecular charge transfer complex with large absorption cross section can be formed in π-conjugated organic system doped with C 70 due to the large electron affinity energy of fullerene. The electron affinity of acceptor fragment NO 2 in COANP is close to 0.45 eV. This parameter for fullerene is 2.65 eV that leads fullerene attracts weakly bound electrons from COANP donor part. Moreover, the distance for the electron pathway is larger for the intermolecular charge transfer than the one for the intramoleculat transfer process. These two facts provoke the formation of the large dipole moment correlated with the increased absorption cross section under the laser irradiations. The model of the
Functional nematic liquid crystal structures doped with nano- and bioobjects have been investigated. The self-assembling features and the photorefractive parameters of the structured liquid crystals have been comparatively studied via microscopy and laser techniques. Fullerene, quantum dots, carbon nanotubes, DNA, and erythrocytes have been considered as the effective nano- and biosensitizers of the LC mesophase. The holographic recording technique based on four-wave mixing of the laser beams has been used to investigate the laser-induced change of the refractive index in the nano- and bioobjects-doped liquid crystal cells. The special accent has been given to novel nanostructured relief with vertically aligned carbon nanotubes at the interface: solid substrate-liquid crystal mesophase. It has been shown that this nanostructured relief influences the orienting ability of the liquid crystal molecules with good advantage. As a result, it provokes the orientation of the DNA. The modified functional liquid crystal materials have been proposed as the perspective systems for both the photonics and biology as well as the medical applications.
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.
hi@scite.ai
10624 S. Eastern Ave., Ste. A-614
Henderson, NV 89052, USA
Copyright © 2024 scite LLC. All rights reserved.
Made with 💙 for researchers
Part of the Research Solutions Family.