Vibrational mode of polaron in trans-(CH)x

The vibrational frequency of polaron configuration in trans-(CH)_x is calculated, and we find the obtained wavenumber v_p = 578 cm^?1 coincides with the observed feature of the infrared absorption spectra at the region of 500–600 cm^-1.     

Possible evidence for a glass transition in trans-(CH)x

A dilatometric investigation has been carried out in the temperature region around 150K where other workers have seen anomalies in other properties. An anomaly suggestive of a glass transition has been observed.     

The vibrational modes around the soliton lattice with next neighbor hopping interactions in highly doped trans-(CH) x

Starting from the extended SSH model that includes an external Coulomb potential arising from interchain charged solitons and counterions, the intrachain e-e interaction and the next neighbor hopping interactions, eight localized vibrational modes around the soliton lattice have been found for the doping levels from 3.33 at.% to 13.33 at.%. Among them three are infrared active and they can be used to interpret the three observed infrared absorption lines at 487, 1284 and 1362 cm^–1. Furthermore, the frequencies of localized modes are decreased and their localizations are weakened when the dopant concentrations increase.     

Stability of charged solitons

The stability of charged solitons described by the relativistic complex scalar field is investigated by the direct Lyapunov method. It is shown that the stability of pulson-type solitons can only be conditional. Some necessary and sufficient conditions for the stability of stationary solitons with fixed charge are established. Several examples are considered.     

星状C60(CH3)x(PAN)x共聚物的光致发光研究

利用物理喷束淀积（ＰＪＤ）技术制备Ｃ６０（ＣＨ３）ｘ（ＰＡＮ）ｘ共聚物的薄膜。这种共聚物中,Ｃ６０分子位于星状结构的中心,聚丙烯腈（ＰＡＮ）主链修饰在Ｃ６０分子的周围。吸收及荧光光谱表明：Ｃ６０分子与聚丙烯腈（ＰＡＮ）有明显的相互作用,而且这种相互作用与ＰＡＮ的链长有关。Ｃ６０分子与ＰＡＮ间存在一定的激发传递过程,从而导致ＰＡＮ荧光的部分猝灭。     

ESR studies of trans-(CH)x during photoexcitation

A series of spin resonance experiments on samples illuminated with light at photon energies ?ω>E_g are reported. The results set an upper limit on the quantum efficiency for photoproduction of unpaired spins, γ_s? 2×10^-7,implying that the photo-induced excited states and the photo-generated carriers are spinless and are to be associated with charged solitons.     

Semiconductor-metal transition in doped (CH)x: Thermoelectric power

Thermoelectric power studies of polyacetylene have been carried out as a function of dopant concentration and temperature. The thermopower of pure trans-(CH)_x is large $\text{(S =}\text{+850 μ V}\text{°K}\text{)}$ and positive consistent with p-type material. With iodine doping, (CHI_y)_x, the thermopower remains positive over the full range of concentration 0 < y < 0.22. The semiconductor-metal transition is clearly observed at n_c ? 3 mole %; S falls dramatically from $\text{S =}\text{+850 μ V}\text{°K}$ at y = 0.003 to $\text{S =}\text{+30 μ V}\text{°K}$ at y = 0.03. At higher concentrations, S remains nearly constant saturating at $\text{+18 μ V}\text{°K}$ in the heavily doped metallic polymer. Temperature dependences are consistent with metallic behavior at the highest dopant concentrations and hopping transport in the undoped and lightly doped polymer.     

Magnetic-field-induced terahertz photogeneration in PbTe(Ga)

It has been shown that a magnetic field in PbTe(Ga) single crystals induces the appearance of a positive photoresponse in the terahertz spectral range. Nonequilibrium charge carriers are generated from states located against the background of the continuum of the conduction band near the quasi-Fermi level. The density of states on the quasi-Fermi level is a critical parameter responsible for the process of generation.     

Lyapunov stability of scalar charged solitons

The direct Lyapunov method is used to investigate the stability of charged solitons of pulson type described by a relativistic complex scalar field in a model of general form. It is shown that the stability can only be conditional. Some necessary and sufficient conditions for stability of stationary solitons for a fixed charge are formulated. Examples of models with power-law and logarithmic nonlinearities are considered.Translated from Izvestiya Vysshikh Uchebnykh Zavedenii, Fizika, No. 1, pp. 56–60, January, 1981.     

Proton NMR studies of the structure of trans-(CH)x

The proton NMR line width in undoped and AsF₅ doped polyacetylene shows an abrupt change as a function of temperature, indicative of motional narrowing. The characteristic temperature for the onset of narrowing decreases with increasing AsF₅ concentration. The results are discussed in terms of large amplitude librational or translational motions of the trans-(CH)_x chains. The magnitudes obtained for the second moment at temperatures below and above the narrowing transition are used to obtain information on the chain packing of trans-(CH)_x within the three-dimensional crystal structure.     

Charge transport at mid-gap in trans-(CH)x: An electrochemical study

Electrochemical studies demonstrate that ～300 ppm of charge (equal to the number of neutral solitons in undoped $\text{trans}$-(CH)_x) is removed at mid-gap. These charges are transported through the polyacetylene electrode via hopping among states at the center of the energy gap, in agreement with Kivelson's theory. From analysis of the data, we have been able to determine the soliton creation energy, E_s ? 0.5eV, which is in good agreement with the theoretical value, E_s = (2/π)Δ.     

Reorientations and phase transitions in (Kr)1-x(CH4-nD n ) x

The condensed isotopic modifications of methane, CH₄, CH₂D₂, and CD₄ and their solutions with Kr were investigated using dielectric techniques. The polarizabilities were computed from the permittivities of the pure liquids. Phase diagrams of methane-krypton alloys were deduced in the liquid-solid coexistence region and for the low temperature phases (T<30 K). From the Curielaws, which described the permittivities of the (Kr)_1-x(CH₂D₂)_x mixed crystals, the permanent dioole moment of CH₂D₂ is calculated to be 4 mD. In the octopolar ordered phases of the solid solutions the effective dipole moments are enhanced significantly.     

Theoretical total ionization cross-sections of CH x,CF x,SiH x,SiF x ( ) and CCl 4 targets by electron impact

Total ionization cross-sections of electron impact are calculated for the molecular targets CH_x, CF_x, SiH_x, SiF_x (x = 1-4) and CCl₄ at incident energies 20-3 000 eV. The calculation is based on Complex Scattering Potential approach, as developed by us recently. This leads to total inelastic cross-sections, from which the total ionization cross-sections are extracted by reasonable physical arguments. Extensive comparisons are made here with the previous theoretical and experimental data. The present results are satisfactory except for the CF_x and SiF_x (x = 1-3) radicals, for which the experimental data are lower than most of the theories by more than 50%. Received 23 May 2002 / Received in final form 24 October 2002 Published online 21 January 2003 RID="a" ID="a"e-mail: knjoshipura@yahoo.com     

未掺杂反式聚乙炔(CH)x中核自旋晶格弛豫-孤子-维扩散模型

Nechtschein等人报道并分析了反式聚乙炔中质子自旋晶格弛豫时间对拉摩频率ω和温度T的依赖关系。观察到了质子自旋晶格弛豫速率T₁^-1和ω^-1/2的正比关系。但是在高频段,T₁^-1∝ω^-1/2关系发生偏离,且温度越低,发生偏离的频率也越低。 本文用另一种方法对这些实验结果作了分析。首先,论证了孤子一维扩散模型的合理性。排除了质子弛豫速率∝ω^-1/2的另一种解释,即仅仅是核自旋向着静止的顺磁中心扩散。孤子能处在运动状态或静止状态。当温度降低时,发生两个效应,即越来越少的孤子处于运动状态,且运动孤子的扩散系数减小。只有扩散的孤子对所观察到的质子弛豫有贡献,而固定孤子的贡献可以忽略。其次,描述了运动孤子的一维随机行走模型,计算了它的相关函数和谱密度函数。质子自旋晶格弛豫速率是: 其中C是运动孤子的浓度,τ是运动孤子沿链跳跃时,渡越相邻位置的跳跃时间,ω是质子的拉摩频率。 这个公式揭示了质子弛豫速率的频率和温度依赖关系的主要特征。它和Nechtschein的测量结果拟合得很好。从拟合中可以得到各个温度下运动孤子的跳跃时间和相对浓度。     

Photoinduced magnetization in the organic-based magnet Mn(TCNE)(x)* y(CH2Cl2)

Photoinduced magnetization in a magnet based on organic species is reported for the first time. Upon optical excitation in the blue region of spectrum, Mn(tetracyanoethylene)(x)*y(CH2Cl2) (x approximately 2, y is approximately 0.8) exhibits increased magnetic susceptibility at temperatures as high as 75 K, accompanied with photoinduced absorption in the visible and infrared spectral regions. These effects are partially reversible by lower energy visible light and fully reversible by thermal treatment. The results suggest trapping of the photoexcited charge in a metastable state with enhanced exchange interaction.     

Interacting noncommutative solitons (vacua)

We consider the dynamics of two interacting lumps/solitons in a noncommutative gauge model. We show that equations of motion describing this dynamics can be reduced to ones of a two-dimensional mechanical system which is well studied and was shown to exhibit stochastic behaviour. Presented at the 10th International Colloquium on Quantum Groups: “Quantum Groups and Integrable Systems”, Prague, 21–23 June 2001. This work was supported by RFBR grant #99-01-00190, INTAS grants #00 262, Scientific School support grant # 00-15-96046. My participation to the Conference was supported by the Votruba-Blochincev Czech-Dubna collaboration grant. (Special thank also to the Coordinator of Bogoliubov-Infeld program).     

The orientational glass instability and localization in (KCN) x (KBr)1−x and (KCN) x (NaCN)1−x

Substitutional disorder in mixed crystals with orientational and translational degrees of freedom leads to the appearance of random strain fields. The strains act as static scattering centers for dynamic modes. Near a ferroelastic phase transition where the crystal is very soft, internal friction processes dominate the dynamic restoring forces. The resulting nonergodic instability marks the onset of the orientational glass state, which is characterized by a freezing-in of orientational and translational modes without long range order. The method is based on the study of dynamic equations of mode-coupling type and was originally developed by Götze for the Anderson localization.Dedicated to Professor Harry Thomas on the occasion of his 60th birthday     

Electromagnetic correction to the domain of Q-stability of charged scalar solitons

The effect of electromagnetic interaction on the domain of Q-stability of charged scalar solitons is studied. The necessary and sufficient conditions, under which the electromagnetic stabilization of such solitons can take place, are established using the direct Lyapunov method.     

Ge self-diffusion in epitaxial Si(1)-(x)Ge(x) layers

Diffusion coefficients and activation energies have been determined for Ge diffusion in strain-relaxed Si(1)-(x)Ge(x) with x = 0.00, 0.10, 0.20, 0.30, 0.40, and 0.50. The activation energy drops from 4.7 eV in Si and Si(0.90)Ge(0.10) to 3.2 eV at x = 0.50. This value compares with the literature value for Ge self-diffusion in Ge, suggesting Ge-like diffusion already at x approximately equal to 0.5. The effect of strain on the diffusion was also studied showing a decrease in diffusion coefficient and an increase in activation energy upon going from compressive over relaxed to tensile strain.