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1.
G. A. Puchkovskaya A. G. Tereshchenko L. I. Shanskii O. V. Yaroshchuk 《Journal of Applied Spectroscopy》1998,65(1):124-129
The process of optical anisotropy indiction in azopolymer films upon irradiation by polarized UV light is studied by means
of UV and IR birefringence spectroscopy. A substantial dependence of the character of the relaxation of the induced anisotropy
on the exposure time to the exciting light is revealed: whereas the process of anisotropy induction is reversible at small
exposure times, at large exposure times the induced anisotropy virtually does not relax and even increases after the irradiation
is terminated. A difference between kinetic curves of dichroism and birefringence induction is shown: at exposure times corresponding
to the saturation of the induced dichroism a slow increase in the birefringence curve is observed. Results obtained are explained
in terms of the assumption of partial ordering of macrochain fragments in irradiated films. The assumption is substantiated
by measurements of polarized IR spectra.
Institute of Physics of the National Academy of Sciences of Ukraine, 46, Nauka Ave., Kiev, 252650, Ukraine. Translated from
Zhurnal Prikladnoi Spektroskopii, Vol. 65, No. 1, pp. 121–125, January–February, 1998. 相似文献
2.
Electro-optical properties of polymer stabilized cholesteric liquid crystal film 总被引:1,自引:0,他引:1
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Liquid crystals (LCs) and polymers are extensively used in various electro-optical applications.In this paper,normal mode polymer stabilized cholesteric LC film is prepared and studied.The effects of chiral dopant and monomer concentrations on the electro-optical properties,such as contrast ratio,driving voltage,hysteresis width and response time,are investigated.The reasons of electro-optical properties influenced by the concentrations of the materials are discussed.Through the proper material recipe,the electro-optical properties of polymer stabilized cholesteric LC film can be optimized. 相似文献
3.
Electroluminescence in anthracene doped with anthraquinone (10?3 mole%) films are presented. Films are deposited at room temperature in a vacuum of 10?5 torr. It is observed that at constant frequency the brightness/voltage relationship follows the relation . The results show that electroluminescent brightness increases linearly with frequency. At lower frequencies green electroluminescent (EL) emission and at higher frequencies blue EL emission is observed. Similar nature for I–V and brightness/voltage relationship are found in anthracene doped with 10?4 mole% anthraquinone. 相似文献
4.
5.
Electro-optical properties of high birefringence liquid crystal compounds with isothiocyanate and naphthyl group
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Liquid crystal(LC) compound with isothiocyanate and naphthyl group is an attractive high birefringence LC material,and can be used in optical devices. In this paper, the electro-optical properties of a series of this type of LC compounds were investigated. The melting points and enthalpy values of these LC compounds were higher than those of corresponding compounds with the phenyl group. These compounds exhibited high birefringence with a maximum value of 0.66. Fluorine substitution in the molecular almost does not affect the birefringence value. When these LC compounds with the naphthyl group were dissolved in a commercial LC mixture, the electro-optical properties depending on temperature were investigated. In the low-temperature region, LC mixtures with the naphthyl-group LC compounds exhibited higher viscosity than pure commercial LCs. In the high-temperature region, viscosity values very closely approached each other. When response performance was investigated, figure-of-merit(Fo M) values were measured. The Fo M values of LC mixtures containing LC compounds with naphthyl group were lower than those of reference benzene LCs in the low-temperature region. However, in the high-temperature region, the results were reversed. These isothiocyanate LC compounds with naphthyl group can be applied in special fast-response LC device, particularly the ones used under high-temperature conditions. 相似文献
6.
7.
E. Vahedi H. Tajalli A. Ghanadzadeh Gilani J. Parka H. Nasirzadeh Milani 《Phase Transitions》2013,86(6):432-439
We have experimentally studied for the first time the electro-optical Kerr effect and the pre-transitional behavior in the isotropic phase of two antiferroelectric liquid crystal mixtures, W-232 and W-204D, composed of rod-like ester molecules exhibiting the direct smectic-A to isotropic (SmA-I) phase transition. The Kerr law has been confirmed for the two compounds and the variation of inverse Kerr constant with temperature above the smectic–isotropic transition temperatures were determined. Both the mixtures with very broad antiferroelectric phase around room temperature have similar sequence of the phases (i.e., Cr-SmC*A-SmC*-SmA-I). Although, the pre-transitional behavior is usually complex in the isotropic phase of the chiral smectic liquid crystal compounds, the investigated compounds showed a similar behavior compared to that of nematic–isotropic behavior. 相似文献
8.
9.
Eugen Bîrsan 《Central European Journal of Physics》2008,6(2):296-305
In the last few years there has been significant interest in the field of thin films, due to numerous specific phenomena related
to the low dimension of these systems, and to the large opportunities in development of high technologies based on their specific
magnetic and electronic properties. When dealing with systems of reduced dimensionality it is important to take into account
the influence of magnetic anisotropies. In this paper we investigate the magnetic properties of bilayer thin film. This behavior
is modeled using Monte Carlo simulations, in the Extended Anisotropic Heisenberg Model. The magnetization, out-of-plane and
in-plane magnetic susceptibilities, and also the specific heat bearings according to temperature are investigated in order
to find the potential magnetic ordering phases and the critical temperatures, for two sets parameter assignments. For quasi-uniform
anisotropy parameters of the film we detect the ferromagnetism-paramagnetism transition and then, by changing the model parameters
values, we relieve a short range ferromagnetic ordering phase arising from the antiferromagnetic base layer coupling influence
and from easy-plane anisotropy discontinuity on the layers interface.
相似文献
10.
R. Gontarz H. Ratajczak Z. Sczaniecki L. Vatskichev 《Czechoslovak Journal of Physics》1971,21(4-5):519-521
Galvanomagnetic effect was used for studying the magnetization reversal processes in thin NiFe-NiFeMn films with the unidirectional anisotropy. The experimental results were compared with the simple coherent magnetization rotation model. A large contribution of rotation of the magnetization vectorM
s
to the reversal process in easy direction was found (around 22°). The dependence of angular dispersion
45 on external fieldH
was also measured. 相似文献
11.
. Mekinis R. Gudaitis V. Kopustinskas S. Tamulevi
ius 《Applied Surface Science》2008,254(16):5252-5256
In present study diamond like carbon (DLC) films were deposited by closed drift ion source from the acetylene gas. The electrical and piezoresistive properties of ion beam synthesized DLC films were investigated. Diode-like current–voltage characteristics were observed both for DLC/nSi and DLC/pSi heterostructures. This fact was explained by high density of the irradiation-induced defects at the DLC/Si interface. Ohmic conductivity was observed for DLC/nSi heterostructure and metal/DLC/metal structure at low electric fields. At higher electric fields forward current transport was explained by Schottky emission and Poole–Frenkel emission for the DLC/nSi heterostructures and by Schottky emission and/or space charge limited currents for the DLC/pSi heterostructures. Strong dependence of the diamond like carbon film resistivity on temperature has been observed. Variable range hopping current transport mechanism at low electric field was revealed. Diamond like carbon piezoresistive elements with a gauge factor in 12–19 range were fabricated. 相似文献
12.
Semiconducting thin films of cadmium selenide have been grown by conventional thermal evaporation technique on glass substrate. Films evaporated at substrate temperature equal 523 K are stoichiometric and homogeneous. Effect of various growth parameters like rate of deposition and substrate temperature on the electrical properties has been studied in details. Also, the annealed at 673 K under vacuum for 1 h films have been analyzed for resistivity and Hall effect. 相似文献
13.
14.
M. Dressler F. Bassani G. Czajkowski 《The European Physical Journal B - Condensed Matter and Complex Systems》1999,10(4):681-686
We show how to compute the optical functions (reflectivity, transmission, and absorption) of polydiacetylene chains diluted
in their monomer matrix exposed to a uniform electric field in the chain direction, in the excitonic energy region. Adopting
a model electron-hole potential, we derived an analytical expression for the effective chain susceptibility, which gives the
optical functions. The resulting absorption shows excitonic peaks below the gap and Franz-Keldysh oscillations above the gap.
The method has been applied for a 3BCMU polydiacetylene chain, showing a good agreement with experimental spectra.
Received 5 November 1998 and
Received in final form 23 February 1999 相似文献
15.
Sławomir Zalewski 《Phase Transitions》2016,89(4):383-392
ABSTRACTIn this article we present results concerning phase transitions and physical properties of the ferroelectric phase of the compound (S)-4-(1-methylheptyloxy)biphenyl–4'-(heptyloxy phenyl)-4-carboxylate (MHOBOPO7). The compound has the following phases: smectic ferroelectric C (SmC*), chiral nematic N*, and two defected phases, TGBC and blue phase. The mesomorphic properties were investigated by means of three complementary methods: differential scanning calorimetry, polarizing light optical microscopy, and transmitted light intensity. The electro-optical measurements were carried out on an ordered sample in a middle electric field during very slow cooling from the nematic phase to the ferroelectric phase. 相似文献
16.
有效地控制有机半导体分子取向和堆积特性对实现高性能电子器件具有非常重要的意义,而发展简便高效的溶液相成膜技术是实现这一目的的重要途径.本文采用改进的溶液浸涂法,成功地成长出大面积宏观取向的半导体聚合物P(NDI2OD-T2)和PTHBDTP薄膜.偏光显微镜和极化的紫外-可见光吸收谱测量显示,薄膜中聚合物分子主链骨架沿成膜时液面下移方向择优取向.原子力显微镜观察到聚合物薄膜由纳米尺度的取向有序晶畴构成,畴的取向与分子链的取向一致.采用衬底-溶液界面处表面张力和溶剂蒸发诱导的分子自组织过程来解释浸涂法生长聚合物取向薄膜的微观机理.使用取向的P(NDI2OD-T2)薄膜制备场效应晶体管,显著地提高了电子迁移率(可达4倍),并实现高达19的迁移率各向异性度.这可归因于共轭的聚合物主链骨架择优取向引起电荷传导通路的变化. 相似文献
17.
Summary Films of cobalt and nickel were electroplated in the presence of an external magnetic-induction field. This resulted in the
deposition of magnetic films which show, in addition to a magnetic anisotropy, also thermo-e.m.f. anisotropy. The latter is
a new effect, not deriving from the anisotropy in electrical conduction deduced earlier by Kornevet al. on the basis of measurements of transmission coefficients of polarized RF field. 相似文献
18.
张国玺 《原子与分子物理学报》2016,33(6)
通过化学溶液沉积法制备的BiFeO3-BaTiO3薄膜在室温下能够同时显现铁电性及铁磁性。在600-700℃的条件下,以Pt/TiOx/SiO2/Si为载体,能够成功得到钙钛矿单相0.7BiFeO3-0.3BaTiO3薄膜。随着结晶温度上升,晶粒持续增长,最终在700℃到达更高的结晶度。由于0.7BiFeO3-0.3BaTiO3薄膜的绝缘电阻较低,它所显现的极化(P)-电场(E)磁滞回线较弱。尽管如此,由于在0.7BiFeO3-0.3BaTiO3薄膜铁的位置上添加锰,高作用场的漏电流有效地减少,最终铁电性质得到了提高。在室温下,添加了摩尔分数5%的锰的0.7BiFeO3-0.3BaTiO3薄膜同时显现铁电极化和铁磁磁化磁滞回线。 相似文献
19.
张国玺 《原子与分子物理学报》2015,32(6)
通过化学溶液沉积法制备的BiFeO3-BaTiO3薄膜在室温下能够同时显现铁电性及铁磁性。在600-700℃的条件下,以Pt/TiOx/SiO2/Si为载体,能够成功得到钙钛矿单相0.7BiFeO3-0.3BaTiO3薄膜。随着结晶温度上升,晶粒持续增长,最终在700℃到达更高的结晶度。由于0.7BiFeO3-0.3BaTiO3薄膜的绝缘电阻较低,它所显现的极化(P)-电场(E)磁滞回线较弱。尽管如此,由于在0.7BiFeO3-0.3BaTiO3薄膜铁的位置上添加锰,高作用场的漏电流有效地减少,最终铁电性质得到了提高。在室温下,添加了摩尔分数5%的锰的0.7BiFeO3-0.3BaTiO3薄膜同时显现铁电极化和铁磁磁化磁滞回线。 相似文献
20.
张国玺 《原子与分子物理学报》2017,34(6)
通过化学溶液沉积法制备的BiFeO3-BaTiO3薄膜在室温下能够同时显现铁电性及铁磁性。在600-700℃的条件下,以Pt/TiOx/SiO2/Si为载体,能够成功得到钙钛矿单相0.7BiFeO3-0.3BaTiO3薄膜。随着结晶温度上升,晶粒持续增长,最终在700℃到达更高的结晶度。由于0.7BiFeO3-0.3BaTiO3薄膜的绝缘电阻较低,它所显现的极化(P)-电场(E)磁滞回线较弱。尽管如此,由于在0.7BiFeO3-0.3BaTiO3薄膜铁的位置上添加锰,高作用场的漏电流有效地减少,最终铁电性质得到了提高。在室温下,添加了摩尔分数5%的锰的0.7BiFeO3-0.3BaTiO3薄膜同时显现铁电极化和铁磁磁化磁滞回线。 相似文献