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本文采用Cu2+斜方对称电子顺磁共振(EPR)参量的高阶微扰公式计算了晶体Cu1-xHxZr2(PO4)3中Cu2+的EPR参量(g因子和超精细结构常数A因子).计算结果表明,晶体Cu1-xHxZr2(PO4)3中[CuO6]10-基团的Cu-O键长分别为R||≈0.241 nm,R⊥≈0.215 nm,平面键角τ≈80.1°;由于对称性降低,中心金属离子基态2A1g(θ)和2A1g(ε)有一定程度混合,混合系数α≈0.995.所得EPR谱图的理论计算值与实验数据符合得很好. 相似文献
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组氨酸铜络合物是构成铜蛋白的重要组份之一。研究组氨酸铜络合物中Cx2+ 离子的电子顺磁共振(EPR)波谱对了解铜蛋白所参与的许多重要的生理生化过程是很重要的。本文采用电子顺磁共振技术在4.2K研究了嵌入离子Cx2+的盐酸组氨酸晶体。Cu2+离子的电子顺磁共振波谱表明,Cx2+离子嵌入到L-盐酸组氨酸晶体中的位置与天然的L-组氨酸铜络合物中Cx2+离子处于完全不同的化学环境中。嵌入到L-盐酸组氨酸晶体的Cx2+离子的基态是一个Kramer双重态。应用实验测定的g张量主值计算了双重态的分子轨道系数,并由此计算得到铜原子的超精细偶合常数Acu。实验结果分析指出、半充满的d轨道是3dx2型轨道,并在Z轴方向有轴向的轻微压缩。单电子d轨道的次序:3dx2 > 3dx2-y2 > 3dyz > 3dxz > 3dxy。Cu2+离子嵌入到L-盐酸组氨酸晶体中的位置具有一个畸变的六配位体环境,近似有D2点群对称性。 相似文献
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GeFe2O4是一种单晶化合物,考虑到由3个〈111〉方向之一的一个 轴,从一个中心位置 到另一个中心位置之间,以Fe2+离子为中心离子和O2-为配体构 成了三角(C 3v)对称体系.利用不可约张量理论,建立了3d4/3d6离子三角(C3 v)对称的晶体场和 自旋相互作用哈密顿矩阵,因此,由完全对角化的晶体场和自旋-轨道相互作用哈密顿矩阵 和电子顺磁共振理论公式求出单晶GeFe2O4中Fe2+离子 的电子顺磁共振零场分 裂参量D和F-a.并研究了自旋三重态对电子顺磁共振(EPR)零场分裂的贡献.结果显示自旋 三重态对基态零场分裂的贡献是较强的,理论计算结果与实验值相符.
关键词:
自旋三重态
晶体场
低自旋态
高自旋态
零场分裂 相似文献
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掺杂晶体材料Al2O3∶Ni2+中顺磁离子N2+局域结构及其电子顺磁共振参量的研究 总被引:6,自引:0,他引:6
按照叠加模型和微扰理论,建立了电子顺磁共振(EPR)参量(D, g∥, g⊥)与Al2O3∶Ni2+晶体局域结构之间的定量关系. 利用EPR参量决定了Al2O3∶N i2+晶体的局域结构. 通过考虑适当的晶格畸变,成功地解释了Al2O3∶Ni2+晶体基态很大的零场分裂和各向异性的g因子. 获得了Ni2+ 离子上方最近邻的三个O2-离子偏向111〕晶轴0.603°, 而Ni2+离子下方的三个O2-离子偏向〔111〕晶轴0.598°. 相似文献
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该文表达了一个研究Yb3+掺杂PbMoO4晶体的光谱和电子顺磁共振谱(EPR)的理论方法. 采用晶体场理论,推导了有关光谱和电子顺磁共振谱的公式. 基于这些理论公式,构建了4f13电子组态在D2d晶体对称下包括Zeeman磁相互作用的14阶能量矩阵. 通过对角化这一能量矩阵,研究了Yb3+掺杂PbMoO4晶体的光谱和电子顺磁共振谱. 所得的理论结果与实验值很好符合. 而且,相关的晶体场参量也在研究中确定. 相似文献
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采用高温固相法制备了Na2SrMg(PO4)2: Ce3+, Mn2+ (NSMP: Ce3+, Mn2+) 荧光粉, 并对其发光性质及Ce3+ 对Mn2+ 的能量传递机理进行了研究. Ce3+ 和Mn2+ 在334 nm 和617 nm 的发射峰分别为Ce3+ 的5d→4f 跃迁和Mn2+ 的4T1(4G)→6A1(6S) 跃迁产生. Ce3+ 对Mn2+ 的发光有较强的敏化作用, 根据Dexter能量传递效率公式判断Na2SrMg(PO4)2 中Ce3+ 对Mn2+ 的能量传递属于电偶极-电四极相互作用引起的共振能量传递. 相似文献
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Cd3Al2Ge3O12:Mn2+锗酸盐石榴石光谱性质 总被引:1,自引:1,他引:0
本文报道室温下Cd3Al2Ge3O12:Mn2+(简称CAGG:Mn2+)锗酸盐石榴石的漫反射光谱、激发和发射光谱.在UV光激发下,在CAGG中Mn2+离子发射强黄光,这是基质到Mn2+离子无辐射能量传递的结果.Mn2+的黄发射带是由一个弱的红带和一个强的绿带所组成.讨论了这两个Mn2+发射带的起因. 相似文献
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The defect (Mn2+,Ni2+,Fe2+) induced magnon gap modes in the layered antiferromagnets K2CoF4 and Rb2CoF4 were investigated with the methods of FIR absorption-and IR emission spectroscopy. The anisotropic exchange-parameters describing the strongly localized Mn2+ spin excitations far below the host lattice magnon band and the Ni2+ excitations in the vacinity of this band are presented. In the diluted system K2Co1-cMncF4 localized Mn2+ cluster modes up to about C≈0.1 were observed. The excitation energy of these modes can only be explained by assuming an anisotropic Mn2+-Mn2+ exchange which is in contrast to the pure isomorphous system K2MnF4. In the spin mismatch system K2CoF4: Fe the magnetic moments of the isolated Fe2+ impurities are pulled from the plane perpendicular to the c-axis and aligned parallel to the easy axis of the magnetic crystal. 相似文献
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Position and intensity of (ΔM=1, Δm=1) forbidden hyperfine lines arising in the central transition of the Mn2+:La2O3 ESR spectrum are analyzed by means of the existing theories. This permitted us to determine the quadrupole coupling constant and the nuclear Zeeman term. 相似文献
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The reversible photostructural change is studied from a microscopic point of view using ESR of Mn2+ doped in As2Se3 films. It is observed that the hyperfine structure constant changes reversibly corresponding to the reversible optical absorption edge shift. The result is explained in terms of increasing randomness by photoirradiation. 相似文献
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We have determined the pressure dependence of both impurity and host exchange fields in MnF2 : Fe2+ by measuring the frequency shifts of far infrared active modes in MnF2 : Fe2+, MnF2, and ZnF2 : Fe2+ at pressure up to 7.1 kbar. 相似文献
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V. Ramesh Kumar N.O. Gopal R.P.S. Chakradhar 《Journal of Physics and Chemistry of Solids》2004,65(7):1367-1372
Electron paramagnetic resonance (EPR), luminescence and infrared spectra of Mn2+ ions doped in zinc gallate (ZnGa2O4) powder phosphor have been studied. The EPR spectra have been recorded for zinc gallate phosphor doped with different concentrations of Mn2+ ions. The EPR spectra exhibit characteristic spectrum of Mn2+ ions (S=I=5/2) with a sextet hyperfine pattern, centered at geff=2.00. At higher concentrations of Mn2+ ions, the intensity of the resonance signals decreases. The number of spins participating in the resonance has been measured as a function of temperature and the activation energy (Ea) is calculated. The EPR spectra of ZnGa2O4: Mn2+ have been recorded at various temperatures. From the EPR data, the paramagnetic susceptibility (χ) at various temperatures, the Curie constant (C) and the Curie temperature (θ) have been evaluated. The emission spectrum of ZnGa2O4: Mn2+ (0.08 mol%) exhibits two bands centered at 468 and 502 nm. The band observed at 502 nm is attributed to 4T1→6A1 transition of Mn2+ ions. The band observed at 468 nm is attributed to the trap-state transitions. The excitation spectrum exhibits two bands centered at 228 and 280 nm. The strong band at 228 nm is attributed to host-lattice absorption and the weak band at 280 nm is attributed to the charge-transfer absorption or d5→d4s transition band. The observed bands in the FT-IR spectrum are assigned to the stretching vibrations of M-O groups at octahedral and tetrahedral sites. 相似文献
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A novel two-color photoluminescence (PL) is found in MnF2 at room temperature (RT) under high pressure. In contrast to the low-temperature PL, the observation of room-temperature PL is unusual in transition-metal concentrated materials like MnF2 since the de-excitation process at RT is fully governed by energy transfer to non-radiative centers. We show that room-temperature MnF2 emissions originate in the pressure-induced cotunnite phase. Both the nine-fold Mn2+ coordination and the Mn–F–Mn exchange pathway inhibit exciton migration among Mn2+, favoring two-band PL at RT. The electronic structure and the excited-state dynamics are investigated by time-resolved emission and excitation spectroscopies under pressure. The two PL bands at 2.34 and 1.87 eV above 15 GPa are assigned to Mn2+ emissions arising from two distinct Mn2+ centers formed in the MnF2 high-pressure phase. The microscopic origin of the two-color PL is analyzed in terms of exciton dynamics in the MnF2 cotunnite structure. 相似文献
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This paper reports on the luminescence and electron paramagnetic resonance (EPR) investigations on MgSrAl10O17:Mn2+ green-emitting phosphor. Single-phase MgSrAl10O17 was successfully synthesized by the one-step solution combustion route without the need for post-annealing at a higher temperature. Crystallization of the powder was confirmed by X-ray diffraction. The luminescence of Mn2+- activated MgSrAl10O17 shows a strong green-emission peak around 515 nm due to the 4T1→6A1 transition of Mn2+ ions under the excitation (453 nm). The EPR spectra of Mn2+ ions exhibit a sextet hyperfine structure centered at g ≈1.995. The Mn2+ ion occupies Mg sites which are in tetrahedral symmetry. The magnitude of the hyperfine splitting (A) indicates that Mn2+ is in a moderately ionic environment. The number of spins participating in resonance (N), the paramagnetic susceptibility (χ) and the zero-field splitting parameter (D) have been evaluated and discussed. 相似文献
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Gerard Bacquet Claude Bouysset Sushil K. Misra 《Journal of Physics and Chemistry of Solids》1980,41(4):397-400
X-band room temperature EPR spectra have been recorded for Mn2+ ion doping unannealed (La2O3)0.95(CeO2)0.05 host crystal. The data are analysed using a rigorous least-squares fitting procedure in which a large number of lines characterized by ΔM = ± 1, Δm = 0 transition, obtained for several orientations of the static magnetic field, are simultaneously fitted. Combined with the knowledge of the absolute sign of the hyperfine interaction parameter. A, the hyperfine Hamiltonian parameters A, B, Q as reported in this paper, are given with their correct signs. The information on the linewidth is used to deduce the deviation of the crystal-field axes of different Mn2+ ions from the c axis; on the basis of the model proposed here these deviations are found to be between 0 and 10°. 相似文献
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The pure rotational spectrum of the molecular ion TiF+ in its 3Φr ground state has been measured in the range 327-542 GHz using millimeter-wave direct absorption techniques combined with velocity modulation spectroscopy. TiF+ was made in an AC discharge from a mixture of TiCl4, F2 in He, and argon. Ten transitions of this ion were recorded. In every transition, fluorine hyperfine interactions, as well as the fine structure splittings, were resolved. The fine structure pattern was found to be regular with almost equal spacing in frequency between the three spin components, in contrast to TiCl+, which is perturbed in the ground state. The data were fit with a case (a) Hamiltonian and rotational, fine structure, and hyperfine constants were determined. The bond length established for TiF+, r0 = 1.7775 Å, was found to be shorter than that of TiF, r0 = 1.8342 Å—also established from mm-wave data. The hyperfine parameters determined are consistent with a δ1π1 electron configuration with the electrons primarily located on the titanium nucleus. The nuclear spin-orbit constant a indicates that the unpaired electrons are closer to the fluorine nucleus in TiF+ relative to TiF, as expected with the decrease in bond length for the ion. The shorter bond distance is thought to arise from increased charge on the titanium nucleus as a result of a Ti2+F− configuration. A similar decrease in bond length was found for TiCl+ relative to TiCl. 相似文献
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An approximate L.C.A.O.-M.O. calculation based upon the one-electron ionic hamiltonian initially derived by Sugano and Shulman, gives satisfactory agreement with measurements of superhyperfine interactions at the ligand shell and outer shell nuclei, for Mn2+ in AMF3 crystals, when one takes into account an external crystal potential acting on the |MnF6|4? complex. The results obtained for cubic symmetry are extrapolated to an independent bond model in order to discuss the covalency contribution to axial zero field splitting. 相似文献