孤子振动模的定域性

对于聚乙炔中孤子的五个定域振动模,本文研究了它们的位形随链长的变化而演变的情况,从而可确定其定域性。本文同时考察了开链和闭环两种情况。对于闭链,五个定域模定域于孤子附近,其形状与链长无关。对于开链,定域模g₁,g₂,g₃和g₅的位形不随链长而改变,因而是完全定域的,但是g₄的两翼随链长增加而变宽,定域性不完全。 关键词：     

扰动对一维局域模的影响

在紧束缚模型基础上，考虑到缺陷、温度、掺杂等外界因素的影响，用方形随机分布模拟了格点原子扰动对一维局域模的影响.给出了不同扰动参数σ下，孤子和极化子中各个局域模的变化情况.计算发现，由于孤子g₁模的钉扎效应，扰动后，弱模g₄定域性会得到加强，还会产生两个新定域模g′₁和g′₂，它们与相应的g₁和g₂模有相同的节点和宇称 ；极化子的g₇模在畸变较大时将 关键词： 扰动 局域模 聚合物     

掺杂的非晶态硅基合金薄膜的高温电子自旋共振研究

本文研究了掺杂(B和P)和未掺杂的a-Si_1-xC_x:H和a-Si_1-xN_x:H膜在高温下的电子自旋共振(ESR)特性。ESR的测量是在温度连续变化的过程中进行的。实验结果表明:掺B的a-Si_1-xC_x:H和a-Si_1-xN_x:H膜的ESR吸收谱,可以分解成两种性质不同的ESR吸收谱的叠加(g₁≈2.005和g₂≈2.010),g₁是硅悬挂键(Si)的贡献,g₂是价带尾态定域化空穴的贡献。随温度的上升,定域化空穴的密度比Si下降得更快。在温度不太高时,定域化空穴的密度远大于Si,但在温度较高时,Si的贡献是主要的。 关键词：     

一维极化子的定域振动模

本文研究了一维电子-晶格耦合系统中极化子的晶格振动,发现了两个新的定域振动模g₆和g′₆,它们分别在一定的耦合参量λ的范围内存在。本文还给出了各个定域振动模的频率和位形随λ的变化情况。 关键词：     

Mo-SiO2-C3H6催化反应体系的ESR动态表征

文章考察了Mo-SiO₂催化剂体系在丙烯歧化反应过程中的动态ESR波谱,发现在催化歧化反应过程中有两种Mo⁵⁺顺磁中心,一种为扰动八面体配位,g_||=1.89,g_⊥=1.94;另一种为扰动四棱锥配位,g_||=1.86,g_⊥=1.95。测得同位素^95,97Mo⁵⁺的各向异性超精细耦合常数A_||=90.3×10^-4cm^-1,A_⊥=44.8×10^-4cm^-1;观测到反应产生的积炭信号,g≈2.0O₂;氧阴离子自由基信号g₁=2.018,g₂=2.011,g₃=2.005。用LCAO-MO理论对上述Mo⁵⁺的ESR波谱进行计算,求得分子轨道系数,发现并总结出△g_||/△g_⊥与△g成直线关系,并建议用△g_||/△g_⊥=4(△E(B₂→E))/(△E(B₂→B₁)(β₁/ε)²之比值作为衡量C_4v扰动程度的尺度。     

铜化合物ESR g张量和A张量的相关性及其与结构的关系

对于某些含有特定配位原子的钢化合物,找出了钢的ESR g_‖和A_‖之间的线性相关性;总结了相关性与钢化合物的分子结构间的联系;认为相关性与分子对称性及分子轨道性有关,分子对称性的提高和钢-配体间成键分子轨道共价性的降低引起g_‖的增大和A_‖绝对值的减小,对某些钢化合物,g_‖与β₁²,A_‖与β₁²之间存在线性关系.总结出由实测的g_‖和A_‖估算分子轨道系数β₁²值的方法.     

四角或三角畸变立方晶场中(3d)1过渡金属离子的劈裂因子

对四角或三角畸变立方晶场中的(3d)¹离子,在已有的静电晶场理论的基础上,采用“集团模型”,进一步引入Γ_∥, Γ_⊥及K_∥, K_⊥,R_∥, R_⊥,并考虑E_g混入T_2g,导出适用于四角或三角畸变立方晶场各种可能情况的g_∥, g_⊥公式。讨论了g_∥, g 关键词：     

三角畸变立方晶场中d2离子的吸收光谱

用不可约张量方法,由广义Wigner-Eckart定理得出两个推论及有关结果。对三角畸变立方晶场中的d²离子,提出了从统一模型出发,计入V_c及(V_tr+H_s)产生的所有可能的相互作用,全面处理光谱与D,g_‖,g_⊥问题的有效方法。应用于钒刚玉,通过全面拟合光谱与D,g_‖,g_⊥实验值,得到的结果与实验值满意地符合。对所用的模型、方法等问 关键词：     

用角动量投影壳模型研究129La的单准质子带

将角动量投影壳模型应用到¹²⁹La核,对单准质子带理论计算与实验结果进行了比较,与组态为πh_11/2的yrast带和组态为πg_7/2带的拟合令人满意-还确认了一个组态为πg_7/2［νh_11/2］²的扁椭球带- 关键词：     

三角畸变立方晶场中d2离子的零场分裂与劈裂因子

用不可约张量方法,利用由广义Winier-Eckart定理得出的两个推论及有关结果,对三角畸变立方晶场中的d²离子,考虑到V_c及(V_t+H_s)产生的所有可能的相互作用,并用缩小因子来计入共价键与J-T效应,通过逐级微扰求得基态波函数,从而导出了g_∥, g_⊥与D的公式。应用于钒刚玉,通过全面拟合光谱与g_∥, g_⊥,D实验值,得到的结果与实验值较好的符合。对所用模型、方法、结果与考虑所有相互作用的重要性等问题作了讨论。 关键词：     

Variable-temperature Raman scattering study on anatase titanium dioxide nanocrystals

The temperature dependence of the Raman modes in anatase TiO₂ nanocrystals has been investigated over the temperature range 77-873 K. With increasing temperature, the frequency of the E_g mode at 639 cm⁻¹ shifts sublinearly to the lower frequencies, however, the frequency of the lowest-frequency E_g mode shifts sublinearly to the higher frequencies from 138 cm⁻¹ at 77 K to 152 cm⁻¹ at 873 K and the frequency of the B_1g mode at 397 cm⁻¹ increases firstly and attains a maximum near 350 K. The linewidth of all of the three modes increases linearly with increasing temperature. The anharmonic effects contribute a lot to the temperature dependence behavior of the frequency and linewidth of Raman modes in anatase TiO₂ nanocrystals.     

关于光激射器的线宽

本文从描述光激射器工作的基本方程出发,讨论了光激射器光束线宽的“短期”(short-time)部分。通常都以下式描写这部分线宽:△v_s=(8πhv(△v′)²)/P,(1)其中△v′是谐振腔电磁模的半宽度;v为光束频率;P为输出功率。我们的主要结论可以归结为以下三点:(1)线宽主要是由与电磁模耦合的耗散体系引起的,与分子耦合的耗散体系的贡献是可以忽略的;(2)在单模近似下,只要分子的线宽比电磁模的线宽大得多,则(1)式是正确的;(3)如果多模谐振腔中激发模与其他模之间的相互作用是强的,则式(1)将被推广为 △v_s=(8πhv(△v′)²)/P+(4hv(△v′))/P somefromn=(λ′≠λ)(r_λλ′²/(rλ′),(2) 其中r_λλ′是相关弛豫系数;r_λ′是模λ′的线宽。在某些情况下,式(2)中第二项可以比其第一项还大。所以,这可能是目前关于线宽的实验结果与由式(1)计算结果不相符合的原因之一。     

High pressure raman study of Bi-2212

The hydrostatic pressure dependence of the Raman spectra of Bi₂Sr₂CaCu₂O₈ single crystals has been investigated. The energy of the A _g and B _1g modes was found to increase with pressure in agreement with previously reported measurements, except the strong mode at ～465 cm^?1, which softens with pressure, while another peak at ～458 cm^?1 appears more pronounced at low temperatures and high pressures. The energy of both modes does not seem to change with increasing pressure, up to ～5 GPa, although the average energy of the wide band has been found to soften, which is in disagreement with previously published results. Based on the modifications observed in some phonons at ～1.8 GPa, which correlate with the reduction of T _c and the deformations of the CuO₅ pyramids, we attribute the mode at ～465 cm^?1 to the vibrations of the apex oxygen atoms. All modes due to the oxygen atoms were found to be strongly anharmonic.     

Softening of charge density wave excitations at the superstructure transition in 2H-TaSe2

Raman scattering measurements performed between 5 K and 300 K on 2H-TaSe₂ reveal new modes which are assigned to the modes of the charge density wave, observed in light scattering due to the Fermi surface induced distortion. The mode at 49 cm^?1 of E_2g symmetry softens (with concurrent line-width broadening) towards 122 K, the transition temperature from the incommensurate distorted to the undistorted phase. The mode at 82 cm^?1 of A_1g symmetry appears to be connected with the transition at 90 K from the commensurate to the incommensurate superstructure. The mode at 24.5 cm^?1 of E_2g shows no temperature dependence and is clearly due to the rigid-layer vibration.     

Pressure dependence study on the electron-phonon coupling of thulium hexachloroelpasolite

Raman spectra of Cs₂NaTmCl₆ have been recorded using a diamond anvil cell at ambient temperature. The vibrational energy of each of the Raman-active TmCl₆⁻³ moiety modes increases linearly with pressure. The integrated band areas of the ν₁(a_1g) and ν₂(e_g) modes are independent of applied pressure. However, the band area of the ν₅(t_2g) mode shows an anomalous behaviour, which has been qualitatively interpreted as due to electron-phonon coupling of the aΓ₅ electronic state with the Γ₁+ν₅(t_2g) vibronic state. This interaction between the coupled states is strongest between ca. 10 and 13 GPa at ambient temperature. The results serve to emphasize the specificity of the occurrence of strong electron-phonon coupling for particular transitions of a given rare earth ion.     

Lattice vibrations in the orthorhombic commensurate charge density wave phase of 2H-TaSe2

Lattice vibrations in 2H-TaSe₂ have been reinvestigated by Raman scattering in view of the recent orthorhombic structure of the commensurate charge density wave (CCDW) phase. The renormalization of six charge density waves on two layers gives four A_g modes and two B_1g modes in the orthorhombic CCDW phase, in place of two A_1g modes and two E_2g modes in the hexagonal CCDW phase which had been believed. The splitting of the E_2g modes to the A_g and B_1g modes in the orthorhombic symmetry depends on the interlayer interaction. The observed small splitting less than 3 cm^-1 shows the weak interlayer interaction. The energies of the four A_g modes and the two B_1g modes are presented as a function of temperature.     

Polarized Raman study of lattice modes in ammonium perchlorate at low temperatures

The Raman spectra of oriented single crystals of ammonium perchlorate have been measured as a function of temperature between 12 and 300 K. The results are consistent with the assignment of NH₄ClO₄ to the D_2h¹⁶ space group at all temperatures. A weak B_1g mode at 180 cm^?1 is assigned as an NH₄⁺ libration. Anomalous temperature dependence is observed for low frequency B_1g and B_3g lattice modes. Detailed results are presented for these modes in the range 18–80 K.     

LnP5O14铁弹相变的喇曼光谱研究

在200—300℃范围测量了单斜I镧系五磷酸盐LnP₅O₁₄(Ln=La,Ce,Pr、Nd,Sm,Eu,Gd,Tb)晶体的软光学模喇曼谱。不同LnP₅O₁₄的A_g-B_2g和A_g-A_g软模在铁弹相变点都软化到20cm^-1,另一个B_g-B_3g软模则软化到38cm^-1。软模频率对温度的依赖关系表明,这些晶体是很好的平均场理论系统。A_g-B_2g软模与e₅的耦合对铁弹相变起主要作用,此软模的强度变化可由双向线性模耦合模型来解释。这个系统T_c从La到Tb的增高是镧系收缩的结果。 关键词：     

Raman scattering in Ag-intercalated TiS2

Ag-intercalated TiS₂ has been investigated using electron diffraction and Raman scattering. The energies of the E_g-1 and A_1g modes in 1T-TiS₂ at 300 K were found to be 232 and 336 cm^-1, respectively. In Ag_0.3TiS₂, at an ambient temperature of 4.2 K, modes were observed at 207, 239, 277, 311, and 347 cm^-1. Three of these modes have been associated with the formation of a superlattice at low temperatures. The superlattice formation was observed by electron diffraction and is attributed to an ordering of the silver atoms at interlayer interstices.