共查询到18条相似文献,搜索用时 171 毫秒
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铜化合物ESR g张量和A张量的相关性及其与结构的关系 总被引:8,自引:0,他引:8
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. 相似文献
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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C4v扰动程度的尺度。 相似文献
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五种还原Keggin结构杂多阴离子的ESR谱 总被引:2,自引:0,他引:2
本文报道了五种具有Keggin结构的还原杂多阴离子的溶液和-150℃冷冻ESR谱,它们是SiV2Mo10O406-、bSiV2Mo9O407--、PV3Mo9O406-、PV3W9O406-和VV3W9O406-。在室温下pH≤3时,所有杂多酸阴离子均为8条锐线,pH=7-8时,均为8+15条线并且随着放置时间增长逐步变成8条线。在-150℃时均呈现出V4+8条线的复杂粉末谱,作者根据一种修正的Ble-aney方法成功地模拟了这些冷冻谱,得出g‖、g⊥、A‖、A⊥,按照DeArmond理论计算了近似的K、α值并讨论了它们的物理意义。最后从异构体的数目和简并度的观点初步解释了观察不到V3物种22条超精细线的原因。Back 相似文献
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本文考虑到d8电子组态中所有自旋三重态和自旋单态对基态的影响,用高阶微扰法导出了d8电子组态在三角对称晶场下光谱和基态EPR普遍公式。发现在三角对称晶场下,d8电子组态离子的g⊥ > g‖或g⊥ < g‖和D > 0或D < 0是以立方对称晶场为界,晶体中顺磁离子的配体沿C3轴伸长或压缩所致。利用所得公式计算了NiCl2和NiSiF6·6H2O晶体的EPR参量,其结果与实验吻合较好。 相似文献
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V. F. Meshcheryakov 《JETP Letters》2005,82(11):708-712
Experimental data on the magnetization of canted antiferromagnet CoCO3 (TN = 18.1 K) in the paramagnetic region are described by the isotropic g factor g‖ = g⊥ = 6.5 that differs from the anisotropic values g‖ = 3.05 and g⊥ = 4.95 obtained in electron paramagnetic resonance (EPR) measurements at T = 4.2 K on Co2+ ions in magnetically diluted crystals. The g-factor values calculated in the Abragam-Pryce and Weiss molecular field approximations using the magnetization data in the magnetic ordered region correspond to data obtained in EPR measurements. It is shown that the absence of the anisotropy of the g factor at high temperatures cannot be explained in the approximations used. Causes of the observed discrepancies are discussed. 相似文献
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Lawrence A. Kappers 《Solid State Communications》1977,21(9):883-885
The intrinsic V- center (a positive hole trapped at a cation vacancy) has been observed in single crystals of SrO following x-irradiation at 77 K. The ESR spectrum corresponds to a spin- defect having <100> axial symmetry with g6 = 2.0012(3) and g⊥ = 2.0703(3). The concentration of V- centers was enhanced significantly by heating crystals in oxygen at 1000°C and rapidly quenching. Vo centers (two holes trapped at a cation vacancy) were also observed after x-irradiation at low temperature, with g6 = 2.0011(3), g⊥ =2.0751(3), and D = 380.4(5) MHz. 相似文献
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An ENDOR study of a hole center in MgO with g|=2.0032±0.0001 and g⊥=2.0385±0.0001 reveals that the hole interacts with an axial aluminum ion with A⊥=±0.178±0.008 MHz, A⊥=±0.074±0.008 MHz, and P= ±0.366±0.002 MHz. The structure of the center is consistent with the label, VAl. It is suggested that the VAl center may have been mistaken in the past for the V- center because of the similarity of their g-values, method of production, and thermal properties. 相似文献
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G. R. Asatryan V. V. Badikov D. D. Kramushchenko V. A. Khramtsov 《Physics of the Solid State》2012,54(6):1245-1248
The results of electron paramagnetic resonance (EPR) studies of Dy3+ ions in lead thiogallate PbGa2S4 single crystals have been presented. It has been shown that the ground state of these ions corresponds to the lowest Stark sublevel Γ6 of the term 6 H 15/2. The spectra are well described by the axially symmetric spin Hamiltonian with the effective spin S = 1/2 with the factors g ‖ = 15.06 and g ⊥ = 2.47. The Dy3+ ions substitute Pb2+ ions in the crystal lattice of PbGa2S4. The observed hyperfine structure has allowed to unambiguously interpret the EPR spectra. The hyperfine interaction constants of two odd isotopes of dysprosium in lead thiogallate single crystals have been found to be A ‖ = 675 × 10?4 cm?1 and A ⊥ = 111 × 10?4 cm?1 for 163Dy and A ‖ = 472 × 10?4 cm?1 and A ⊥ = 77 × 10?4 cm?1 for 161Dy. 相似文献
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N. Okabe Y. Ohba S. Suzuki S. Kawata K. Kikuchi Y. Achiba S. Yamauchi M. Iwaizumi 《Applied magnetic resonance》1996,10(1-3):251-262
The temperature dependence of EPR spectrum of La@C82 in the powder of empty C60 and C70 mixed crystals was studied by EPR spectroscopy employing X- and Q-band microwave frequencies. The rigid limit spectra (at 4.2 K for the X-band and at 132 K for the Q-band) could be analyzed by static spectral simulation which yielded the EPR parameters,g ‖=2.0021,g ⊥=1.9970,La A ⊥=7.8 MHz,La A ‖~0 MHz and an isotropic13C coupling value of about 3 MHz. For higher temperatures an appreciable motional averaging effect was observed and the spectra were analyzed by using dynamic spectral simulation based on the stochastic Liouville equation, where we assumed an isotropic rotational motion with the Brownian diffusion. The calculated spectra reproduced the dominant feature of the temperature dependence of the spectra almost satisfactorily for both the X-and Q-band frequencies with the appropriate rotational correlation times. The Arrhenius plots of the correlation time gave two activation energies of 0.9 kcal/mol and 2.9–3.8 kcal/mol for the temperatures below and above 200 K, respectively. 相似文献
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Zheng Wen-Chen 《辐射效应与固体损伤》2013,168(3-4):323-328
Abstract The zero-field splitting D, the anisotropic g-factors g ∥, Δg(=g ∥ ? g ⊥) and the first excited state splitting Δ(2 E) for the trigonal Cr3+–VK center in KMgF3: Cr3+ crystals have been studied from Macfarlane's high-order perturbation formulas. From the studies, the local structure of the trigonal center is obtained. The local lattice distortions (i.e., the displacement directions of the ions in the center) are consistent with the expectation based on the electrostatic interaction. 相似文献
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Wen-Lin Feng 《Physica B: Condensed Matter》2012,407(18):3865-3867
The optical absorption spectra and electronic spin resonance parameters (ESR g factors g‖, g⊥ and hyperfine structure constants A‖, A⊥) for Cu2+ in shattuckite crystal are calculated from the two spin–orbital coupling parameters model, high-order perturbation formulas and complete diagonalization (of energy matrix) method (CDM) of 3d9 ion in tetragonal symmetry. The calculated results are in good agreement with the observed values. Since the ESR parameters are sensitive to the local structure of a paramagnetic impurity center, the defect structure of Cu2+ center in shattuckite crystal is estimated. The results are discussed. 相似文献
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Cheng-Gang Li Mei-Ling Duan Ya-Ru Zhao 《Journal of Physics and Chemistry of Solids》2010,71(11):1599-1602
The local lattice structure and EPR parameters (D, g‖, g⊥) have been studied systematically on the basis of the complete energy matrix for a d3 configuration ion in a trigonal ligand field. By simulating the calculated optical and EPR spectra data to the experimental results, the local distortion parameters (ΔR, Δθ) are determined for V2+ ions in CdCl2 and CsMgCl3 crystals, respectively. The results show that the local lattice structure of CdCl2:V2+ system exhibits a compression distortion (ΔR=−0.0868 Å) while that of CsMgCl3:V2+ system exists an elongation distortion (ΔR=0.0165 Å). The different distortion may be ascribed to the fact that the radius of V2+ ion is smaller than that of Cd2+ ion or larger than that of Mg2+ ion. Moreover, the relationships between EPR parameter D and local structure parameters (R, θ) as well as the orbital reduction factor k and g‐factors (g‖, g⊥) are discussed. 相似文献