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按照叠加模型与EPR零场分裂参量的三阶微扰理论,建立了KCdF3:Cr3+晶体EPR零场分裂参量与四角对称Cr3+-Cd2+缺陷中心局域结构之间的定量关系.证实Cd2+空位与晶格畸变的存在,我们获得:围绕Cr3+离子的六个F-配体分别向中心Cr3+移动Δ1=0.00294nm,Δ2=0.0010nm,Δ3=0.0028nm (参见图2).EPR零场分裂参量与实验一致表明:Cd2+空位与晶格畸变的假设是合理的.尽管四角晶场主要来自Cd2+空位,但晶格畸变的贡献不可忽略. 相似文献
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KCdF3晶体中Cr3+-Li+中心局域结构研究 总被引:2,自引:0,他引:2
利用零场分裂参量与晶体结构之间的定量关系,研究了双掺杂晶体KCdF3:Cr3+,Li+的局域结构。指出,对于KCdF3:Cr3+,Li+晶体,四角晶场的形成包含两个方面:(1)由于电荷补偿而产生的等效电荷形成的四角对称晶场;(2)Cr3+的局域结构发生晶格畸变而产生的四角对称晶场。事实上,当Cr3+和Li+掺入KCdF3晶体时,Cr3+代替了Cd2+离子;由于Cr3+离子与Cd2+离子的半径不同、电荷不同、质量不同,导致Cr3+的局域结构发生晶格畸变,由此而产生四角对称晶场;由于电荷补偿,Li+离子取代了[001]方向与Cr3+离子邻近的Cd2+离子,由此产生的等效电荷而形成的四角晶场。这样,Cr3+的局域结构由Oh对称变为C4v点对称。文中建立了ZFS参量和晶体结构之间的定量关系。在考虑晶格畸变和等效电荷的基础上,研究了KCdF3:Cr3+,Li+晶体的ZFS参量,理论结果和实验符合很好。得到了F-离子向中心离子分别移动为ΔR1=0.00268nm,ΔR2=0.001nm,ΔR3=0.00165nm。 相似文献
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基于配位场理论,建立d3组态离子在三角晶场中的完全能量矩阵,采用完全能量矩阵的对角化计算方法,研究了绿宝石晶体Cr3+:Be3Al2(SiO3)6的光谱和EPR谱,理论值与实验值符合得很好.通过分析绿宝石晶体中(CrO6)9-团簇的光谱和EPR谱,研究了配体在络合物中的极化现象.结果表明由于周围配位环境的影响,绿宝石晶体中(CrO<
关键词:
3+:Be3Al2(SiO3)6体系')" href="#">Cr3+:Be3Al2(SiO3)6体系
光谱
EPR谱
局域结构极化 相似文献
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采用完全对角化方法,以尖晶石结构的ZnAl2O4:Cr3+,ZnGa2O4:Cr3+和MgAl2O4:Cr3+系列晶体为例,联系晶格局域结构,对三角对称下3d3离子2E态g因子性质进行了研究.研究中考虑了包括自旋与自旋相互作用、自旋与另一轨
关键词:
2E态g因子')" href="#">2E态g因子
3离子')" href="#">3d3离子
尖晶石结构
磁相互作用 相似文献
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文章用提拉法生长出Li6Gd(BO3)3:Ce晶体,并对其光谱性能与发光过程进行了探索. 借助于真空紫外-紫外透过光谱测试,发现晶体的透过光谱中存在Ce3+离子和Gd3+的特征吸收峰,同时还存在与Ce4+离子相关的电荷迁移带. 对晶体的真空紫外-紫外激发发射光谱进行研究发现,在晶体存在着Ce3+离子的5d→4f辐射跃迁发光与Gd3+离子的4f→4f辐射跃迁发光,而且存在着Gd3+→Ce3+之间的能量传递. 对Li6Gd(BO3)3:Ce晶体的X射线与γ射线激发发射光谱研究可知,晶体在高能射线激发下的闪烁光主要是Ce3+离子的发光.
关键词:
6Gd(BO3)3:Ce晶体')" href="#">Li6Gd(BO3)3:Ce晶体
真空紫外-紫外透过光谱
真空紫外-紫外激发发射光谱
能量传递 相似文献
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本文从层子模型的结构观点出发,应用文献[1]中的层子与轻子的弱相互作用等效哈密顿量和文献[2]中给出的(1/2)+重子波函数及文献[3]中定出的参数,对(1/2)+重子的半轻子衰变和高能中微子的弹性和准弹性反应进行了讨论。文中得到的(1/2)+重子的半轻子衰变的理论结果与实验符合较好;得到的ΔS=0过程的轴矢形状因子和νμ+n→p+μ-过程的截面在误差范围内均与实验相符合;得到的ΔS=1过程的轴矢形状因子和νμ+p→Λ+μ+过程的截面与目前实验给出的粗略结果也是符合的。特别需要指出的是,本文在讨论反应问题时,理论中所包含的参数全部从电磁过程定出,在给出的轴矢形状因子和截面公式中没有引进新的参数。 相似文献
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A. Perrin J. Vander Auwera Z. Zelinger 《Journal of Quantitative Spectroscopy & Radiative Transfer》2009,110(9-10):743-755
Using high-resolution Fourier transform spectra of trans-HCOOH recorded at 5.6 μm, we carried out an extensive analysis of the strong ν3 fundamental band (carbonyl stretching mode) at 1776.83 cm?1, starting from results of a previous analysis [Weber WH, Maker PD, Johns JWC, Weinberger E. J Mol Spectrosc 1987; 121: 243–60]. As pointed out in the literature, the ν3 band is significantly perturbed by resonances due to numerous dark bands. We were able to assign series belonging to the ν5+ν7, ν5+ν9, ν6+ν7 and ν6+ν9 dark bands, located at 1843.48, 1792.63, 1737.96 and 1726.40 cm?1, respectively. The model used to calculate energy levels accounts partly for the observed resonances, and enabled us to reproduce most of the observed line positions, within their experimental uncertainties. We also determined absolute line intensities with an accuracy estimated to 15%. Finally, we generated, for the first time, a list of line parameters for the 5.6 μm region of trans-formic acid. 相似文献
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DAVID L. CEDEÑO JINGPING PENG DOVIE REYNOLDS NAIRMEN MINA-CAMILDE CARLOS MANZANARES I 《Molecular physics》2013,111(12):1745-1755
The spectra of fluoroform (CF3H) in the solvents Ar, N2, and Xe have been obtained in the fundamental region (400–4000cm?1) using a low temperature cryostat and a Fourier transform infrared spectrophotometer. Ab initio calculations at the HF/6-31G? level have been performed to obtain the calculated vibrational frequencies of the isolated CF3H molecule and CF3H in the presence of the solvents (Ar, N2, and Xe). Comparison of the frequency shifts of CF2H in solution with respect to the gas phase frequencies is made for the experimental and theoretical results. Lorentzian functions were used to fit the bands and obtain the wavenumber at the peak absorbance and the vibrational band widths. An analysis of the dynamics of relaxation has been made based on the infrared time correlation functions for three of the fundamental modes (ν1, ν3, and ν4). Bandwidths, band moments, and relaxation times were obtained by appropriate fitting of the experimental correlation functions to theoretical models. In liquid argon, the temperature dependence of the second moment (M 2) indicates that rotational relaxation explains the bandwidth of the ν3 mode. For the ν4 mode, the temperature dependence of M 2 can be attributed to rotational relaxation if it is corrected with a Coriolis coupling term. The bandwidths of the ν1 mode do not follow the rotational relaxation model, and probably vibrational relaxation is the dominant mechanism. 相似文献
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《Physics letters. [Part B]》1986,179(3):307-312
The results of an experiment which searched for νe events arising from oscillations of a low-energy νμ beam are presented. The BEBC heavy liquid bubble chamber, placed at a distance of 825 m from an external proton target at the CERN PS, was used as a neutrino detector. The appearance of νe CC interactions provides a sensitive indication of νμ→νe oscillations. 470 νμ CC events and 4 νe events, with an estimated background of 3 νc CC events, have been observed. The resulting limits on the oscillation parameters are: δm2⩽0.09 eV2 (for maximal mixing) and sin2θ⩽0.013 for δm2=2.2 eV2, at the 90% confidence level. 相似文献
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本文在Thomas-Fermi势能基础上,导出了全射程R的解析解:R=2/a[E1/2-A1(arctg(2E1/2-f)/△1/2+arctg f/△1/2)+B1ln((E1/2-f)2)/(E-fE1/2+d) ·d/f2],其中A1,B1,f,d和△均为与离子及靶的质量、原子序数有关的常数。结合导出的η=R/(Rp)(Rp指投影射程)比值的双曲线函数关系 η=F(μ)[A2(μ)+(B2(μ))/(ε1/2+C)],和ω=Rp/△Rp(△Rp指投影射程的标准偏差)比值的线性关系ω=A3(μ)ε1/21/2+B3(μ),可简便而又准确地计算R,△Rp,Rp.这里F(μ),A2(μ),B2(μ), B3(μ)和A3(μ)为μ的代数函数,μ为离子与靶的质量比,C是经验常数.并对η等关系式的物理意义作了讨论。上述公式的计算结果与Gibbons的数值解结果及有关实验结果作了比较,表明可用于元素半导体如Si、二元化合物如GaAs以及三元化合物如SiO2等;既对较轻离子适用,也对重离子适用,具有一定的普适范围。 相似文献
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The temperature dependence of the bending ν2, combination ν2 + ν L , and stretching (ν1, ν3, 2ν2) absorption bands in the infrared spectra of supercooled water with a temperature-change step Δt from 2 to 2.5°C was studied using an advanced infrared Fourier spectrometer. It was found that the frequency of the maximum of the stretching absorption band (2700–3700 cm?1) decreases with the reduction of the water temperature from ?0.5 to ?5.0°C. The frequency of the maximum of the combination absorption band (2130 cm?1) increases with the reduction of the water temperature in a range from ?3.0 to ?5.0°C. The frequency of the maximum of the absorption band of bending oscillation (1640 cm?1) is invariable with a reduction of the water temperature from ?0.5 to ?5.0°C. 相似文献
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B. A. Popov 《Physics of Atomic Nuclei》2000,63(7):1111-1118
The NOMAD experiment has sought νμ ? ντ oscillations by looking for the emergence of τ? in events from the CERN SPS neutrino beam. With some improvements in the techniques of analysis in relation to the results published previously and with the inclusion of data from the 1998 run, no evidence for the oscillations has been found, which results in an updated limit on the oscillation probability [P(νμ → ντ) < 0.5 × 10?3 at a 90% C.L.]. The corresponding limit on the oscillation mixing angle is given by sin22θμτ < 1.0 × 10?3 for large Δm 2. By using a 1% contamination of νe in the neutrino beam, we can also rule out ν e ? ντ oscillations and constrain the probability of the relevant transition as P(ν e → ντ) < 3 × 10?2 at a 90% C.L. (sin22θ eτ < 6 × 10?2 at large Δm 2). 相似文献
18.
Agnes Perrin Jean Demaison 《Journal of Quantitative Spectroscopy & Radiative Transfer》2011,112(8):1266-1279
A list of line positions and, for the first time, of line intensities was generated for the ν1, ν2, and ν3 fundamental bands of the 12C16OF35Cl and 12C16OF37Cl isotopologs of carbonyl chlorofluoride, located at 5.3, 9.1, and 13.1 μm, respectively. In addition, for the most abundant isotopolog (12C16OF35Cl) this linelist includes also the contributions from the first two associated hot bands. The parameters included in this database were generated by combining the results of previous experimental analyses and ab initio calculations [Perrin A, Flaud JM, Bürger H, Pawelke G, Sander S, Willner H. First high resolution analysis of the six fundamental bands ν1, ν2, ν3, ν4, ν5 and ν6 of COF35Cl in the 340 to 2000 cm−1 region. J Mol Spectrosc 2001;209:122-232; Demaison J, Perrin A, Bürger H. Ab initio anharmonic force field and equilibrium structure of carbonyl chlorofluoride. J Mol Spectrosc 2003;221:47-56]. For the purpose of the present work, a partial re-investigation of the ν1 of COF35Cl was performed, together with the first identification of the ν2 band of COF37Cl.These parameters were generated in order to improve the quality of remote sensing of the atmosphere in the mid-IR. Analyses of atmospheric solar occultation spectra measured by the JPL MkIV interferometer show that the new linelist not only improves the quality of retrievals of COFCl, but also of several other gases whose absorptions overlap those of COFCl. 相似文献
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Two-sample (Allan) variance with a modified algorithm was applied to the determination of the experimental linewidth of a thermoelectrically-cooled continuous-wave distributed feedback quantum cascade laser at a wavelength of 4.333 μm. From successive laser transmittance scans over the CO2 ν3, (0111 − 0110) P(33) absorption line at 2307.653 cm− 1, two-sample variances were calculated for the laser frequency difference between different points on the sides of the absorption peak. From the minimum two-sample variance of the laser frequency difference between two adjacent points (5 μs between the points) on the same side of the absorption line the experimental laser linewidth was estimated to be less than 36(7) kHz at a laser power of ~ 25 mW, a laser current of 976 mA and a laser temperature of + 19.5 °C. 相似文献
20.
J.-M. Flaud F. Kwabia Tchana W. J. Lafferty A. Perrin L. Manceron M. Ndao 《Molecular physics》2018,116(23-24):3463-3467
ABSTRACTA Fourier transform spectrum of phosgene (Cl2CO) has been recorded in the 17.3-μm spectral region at a temperature of 180 K and at a resolution of 0.00102 cm?1 using a Bruker IFS125HR spectrometer coupled to synchrotron radiation, leading to the observation of the ν2 and ν4 vibrational bands of the two isotopologues 35Cl2CO and 35Cl37ClCO. The corresponding upper-state ro-vibrational levels were fit using a Hamiltonian model accounting for the A-type Coriolis interaction linking the rotational levels of the 21 and 41 vibrational states. In this way, it was possible to reproduce the upper-state ro-vibrational levels to within the experimental uncertainty, i.e. ~0.30 × 10?3 cm?1. Very accurate rotational and centrifugal distortion and interaction constants were derived from the fit, together with the following band centres: ν0(ν2, 35Cl2CO) = 572.526299(30) cm?1, ν0(ν4, 35Cl2CO) = 582.089026(30) cm?1, ν0(ν2, 35Cl37ClCO) = 568.951791(35) cm?1 and ν0(ν4, 35Cl37ClCO) = 581.758279(35) cm?1. 相似文献