SrAl12O19:Pr3+中4f2→4f2电偶极跃迁强度参量化

对SrAl12O19:Pr3+中4f2→4f2电偶极跃迁强度的参量化进行了研究.考虑明确的4f5d组态成分与4f2跃迁能级混杂对4f2组态内跃迁的影响.引入新的强度参数Tkq,参数值由3P0能级的相关实验数据拟合.利用拟合的参数T33和T53计算1S0向下各能级发射的跃迁强度,计算值与实验及Judd-Ofelt理论的结果进行了比较.     

Role of Lanthanide in the Electronic Properties of RbLn2Fe4As4O2(Ln=Sm and Ho)Superconductors

We focus on the effect of ionic radius of lanthanides and the number of electrons in 4f orbitals on the superconducting temperature in 12442-type iron-based superconductors RbLn₂Fe₄As₄O₂ (Ln=Sm and Ho).Electronic properties of RbSm₂Fe₄As₄O₂ and RbHo₂Fe₄As₄O₂ with the largest differences of ionic radii and numbers of electrons in 4f orbital,and the largest difference...     

LaⅡ5d2 1G4→4f5d 1F3超精 细结构光谱测量

利用少有的共线快离子激光光谱学方法研究了LaⅡ的超精细结构,测量了5d² < sup>1G₄态→4f5d ¹F₃态的超精细结构光谱,分 别得出了相应的磁偶极矩和电四极矩的超精细相互作用常数. 关键词： 共线快离子束激光光谱学 超精细结构 共振激发     

Eu,Dy共掺杂SrAl2O4长余辉材料制备新工艺

活化Al-Sr合金粉末水解制备SrAl₂O₄长余辉材料的前驱体,并采用高温固相反应法制备出Eu,Dy共掺杂的SrAl₂O₄长余辉材料,对其微观结构和发光特性进行了研究。实验结果表明:前驱体中Al、Sr元素在微观状态下分布均匀,所制成的长余辉发光材料的发射主峰位于520nm附近,为典型的Eu²⁺离子4f5d-4f的特征发射,初始亮度达到18cd/m²,余辉时间长达46h。     

Ca4LaNbMo4O20:Pr3+荧光粉的发光性质

采用高温固相法成功制备出荧光粉Ca₄LaNbMo₄O₂₀:Pr³⁺,通过X射线衍射分析了样品的结构,其结构与CaMoO₄结构相似。在Ca₄LaNbMo₄O₂₀:Pr³⁺的激发光谱中出现了NbO₄^3-和MoO₄^2-的电荷迁移(CTS)吸收和Pr³⁺离子的4f→4f5d激发跃迁,以及Pr³⁺-金属离子的价间电荷迁移(IVCT)吸收;另外在420~520 nm处,还观测到属于Pr³⁺离子的典型f-f激发跃迁。发射光谱中,在452 nm激发下,主要出现绿光和红光两种发射,其峰值位于490 nm和607 nm处,分别是Pr³⁺的³P₀→³H₄和¹D₂→³H₄的跃迁作用;在紫外287 nm激发下出现NbO₄^3-和MoO₄^2-发射和Pr³⁺离子的4f5d→4f跃迁宽带,以及Pr³⁺离子的4f→4f发射峰。     

关于Eu2+的f—f跃迁

文章综述了Eu2+在某些基质化合物中的f-f跃迁.在考察文献数据基础上,总结出Eu2+在氟化物(或氧化物)中产生f-f跃迁的某些规律性,并根据电负性、配位数及离子半径等提出一种判断Eu2+产生尖峰结构光谱的经验方法.在缺少结晶学数据情况下,该方法有可能用来预测Eu2+产生线状峰的新基质化合物.镧系离子的电子结构早已为人们所熟知.三价铕离子(Eu3+),有六个自旋平行的4f电子[1、2、3].根据洪德规则,Eu3+很容易变成Eu2+,4f壳层呈现半充满状态(4f7),获得与Gd3+具有相同的电子构型,从而趋于稳定.     

SrAl12O19：Pr3+中4f2→4f2电偶极跃迁强度参量化

对SrAl₁₂O₁₉：Pr³⁺中4f²→4f²电偶极跃迁强度的参量化进行了研究.考虑明确的4f5d组态成分与4f²跃迁能级混杂对4f²组态内跃迁的影响.引入新的强度参数T_kq，参数值由³P₀能级的相关实验数据拟合.利用拟合的参数T₃₃和T₅₃计算¹S₀向下各能级发射的跃迁强度，计算值与实验及Judd-Ofelt理论的结果进行了比较. 关键词： 12O₁₉：Pr³⁺')" href="#">SrAl₁₂O₁₉：Pr³⁺ 宇称态混杂 4f5d组态 强度参数     

铕原子4f76p3/2nd自电离态的光谱

利用三步三色孤立实激发技术(ICE),系统地研究了铕原子4f76p3/2 nd自电离态的光谱,同时首次研究了激光偏振对复杂原子的光谱的影响.为了研究铕原子4f76p3/2 nd自电离态的光谱,首先设计并采用了不同的激发路径,分别将原子布居到同一高激发能域并探测它们在该能域的自电离光谱.通过比较这些光谱的异同并结合上述激发路径所对应的跃迁选择定则,便可唯一地确定这些高激发态的总角动量.为了研究激光偏振对铕原子的影响,设计并使用了两种偏振组合:三步激光都是垂直(πππ),三步激光都是平行(σσσ)(激光偏振方向相对于探测器垂直或平行).为了得到有偏振影响的光谱,分别使3部激光器处于同一偏振,依次对铕原子进行激发,激发路径与终态同上.通过对同一路径不同偏振下的光谱的比较,发现仅能确定极少数的高激发态的总角动量,同时在光谱中一些峰独立于另一偏振光谱存在.     

BaB2O4-K2O和BaB2O4-K2B2O4赝二元系相图的研究

用X射线衍射和差热分析方法研究了BaB₂O₄-K₂O和BaB₂O₄-K₂B₂O₄赝二元系的相平衡关系。BaB₂O₄-K₂B₂O₄属共晶体系,共晶温度为850±3℃,共晶点成分为45mol％K₂O。在Ba 关键词：     

J/ψ→fJФ→ππK＋K－反应的各种一维角分布是否足以鉴别f0和f2?

基于螺旋度分波分析公式,我们探讨在J ψ→fJ(θ1,1)、fJ→ππ(θ2 ,2 )、→K+ K-(θ3 ,3 )级联衰变过程中是否可以通过各种一维角分布投影鉴别出f0 和f2 共振态.结果表明,f0 和f2 可以同时给出完全相同的(θ1,1,θ2 ,2 )一维投影,但不能同时给出完全相同的(θ1,1,θ2 ,2 ,3 )一维投影.因此,要想保证从角分布的一维投影鉴别出f0 和f2 ,必须同时考虑所有三个衰变顶角的角分布信息.     

Eu原子4f~76p_(3/2)ns自电离态的光谱的研究(英文)

采用孤立实激发技术,对铕原子4f~76p_(3/2)ns(n=7,8)自电离态的光谱进行了系统的研究,同时是首次在不同激光偏振组合下进行的研究。首先,用前两束激光分步将铕原子从基态4f~76s~2经中间4f~76s6p态激发至4f~76sns里德堡态,然后再用第三束激光通过离子实4f~76s~+→4f~76p~+_(3/2)的跃迁将其进一步激发至4f~76p_(3/2)7s自电离态或4f~76p_(3/2)8s自电离态。对铕原子4f~76p_(3/2)ns(n=7,8)自电离态复杂的光谱分别给出了详细的解释,从中我们可以获得一些重要的光谱信息,比如自电峰的能级位置和线宽等,同时还可以观察到收敛于不同离子限的自电离系列之间的组态相互作用。最后,通过比较不同激光偏振组合下的自电离光谱,确定了一些自电离态的总角动量的值。     

Eu原子4f~76p_(3/2)ns自电离衰变分支比和弹射电子角分布

首先运用孤立实激发技术将Eu原子从基态4f~76s~(28)S_(7/2)经中间态4f~76s6p共振激发到4f~76sns Rydberg态,然后再将其进一步激发至4f~76p_(3/2)ns(n=7,8)自电离态.其次,采用速度影像技术对Eu原子自电离弹射出的电子进行探测,以便来研究自电离衰变分支比和弹射电子角分布.在研究自电离衰变分支比时,重点讨论了粒子数反转的可能性,并依据此现象可为实现自电离激光器提供有价值的信息.另外,还探讨了各向异性参数对弹射电子角分布的影响;以及在Eu原子不同自电离几率位置处,讨论了弹射电子角分布形状的变化情况.     

Eu原子4f~76p_(3/2)6d自电离过程的动力学特性

采用孤立实激发技术(isolated-core excitation, ICE)及速度影像技术(velocity-map imaging,VMI),研究了Eu原子4f~76p_(3/2)6d自电离过程的动力学特性.孤立实激发技术用于将Eu原子从基态4f~76s~(2 8)S_(7/2)经中间态4f~76s6p激发到4f~76s6d里德堡态,然后将其进一步激发至4f~76p_(3/2)6d自电离态;速度影像技术用于探测其自电离过程的动力学特性,从而获得自电离衰变的分支比(branch ratio, BR)和弹射电子的角分布(angular distribution, AD).自电离衰变的分支比代表离子的能量分布,从中获得VMI影像的径向信息;而通过各向异性参数描述的弹射电子的角分布揭示了VMI影像的角向信息.此外,讨论了自电离衰变分支比和弹射电子角分布在整个自电离共振能域内的变化情况.基于4f~76s~+和4f~75d~+两个离子态的分支比,讨论了实现Eu离子粒子数反转的可能性.     

Acoustic distortion products in humans: systematic changes in amplitudes as a function of f2/f1 ratio

The effects of primary-tone separation on the amplitude of distortion-product emissions (DPEs) at the 2f1-f2 frequency were systematically examined in ten ears of five subjects. All individuals had normal hearing and middle-ear function based upon standard clinical measures. Acoustic-distortion products were elicited at 1, 2.5, and 4 kHz by equilevel primaries at 65, 75, and 85 dB SPL, while f2/f1 ratios were varied in 0.02 increments from 1.01-1.41 (4 kHz), 1.01-1.59 (2.5 kHz), or 1.01-1.79 (1 kHz). A principal outcome reflected in the detailed structure of both average and individual ratio functions was a nonmonotonic change in DPE amplitude as the ratio of f2/f1 increased. Despite the presence of amplitude nonmonotonicities, there was clearly a region of f1 and f2 separation that generated a maximum DPE. The effects of primary-tone separation on DPE amplitudes were systematically related to DPE frequency and primary-tone level. For all three levels of stimulation, the f2/f1 ratio was inversely related to DPE frequency. Thus larger ratios reflecting a greater separation of f1 and f2 were more effective in generating DPEs at 1 kHz rather than at 4 kHz. The optimal ratio for 2.5 kHz fell at an intermediate value. Conversely, acoustic distortion-product amplitude as a function of primary-tone level was directly related to the frequency separation of the primary tones. Regardless of the frequency region of the primary tones, smaller f2/f1 ratios were superior in generating DPEs in response to 65-dB stimuli, whereas larger ratios elicited bigger DPEs with primaries at 75 and 85 dB SPL. Within any specific stimulus-parameter combination, individual variability in DPE amplitude was noted. When all stimulus conditions describing the variations in frequency and level were considered, an f2/f1 ratio of 1.22 was most effective in maximizing DPE amplitude.     

Site selective 4f5d spectroscopy of CaF2 : Pr

Spectroscopic investigations were performed on a single crystal of CaF₂ doped with 0.05% Pr³⁺. Three different Pr³⁺ sites with different luminescent properties were identified. The 4f² →4f¹5d¹ excitation spectrum of the first site has a sharp maximum at 221.3 nm. Excitation in the 4f5d bands of this site yields strong 4f5d emissions in the UV/VIS part of the spectrum and also weaker intraconfigurational 4f² emissions. By comparing the intraconfigurational 4f emissions and their decay times with data from the literature, these 4f5d bands are assigned to transitions on Pr³⁺ ions on a site with C_4V symmetry. The fd excitation spectrum of the second site has a zero phonon line at 223.3 nm. Upon selective excitation in this band, only 4f5d emission is observed. Probably, these 4f5d bands correspond to Pr³⁺ ions on a O_h site. The third set of 4f5d bands has a 4f5d onset at 208 nm. By comparison of the luminescence spectra of the intraconfigurational 4f² transitions with literature data, these transitions are assigned to Pr³⁺ on an L site. Excitation in these 4f5d band yields ¹S₀ emission followed by emission from the ³P₀ state. The present results clarify some contradictions reported in the literature.     

Localized 4f states and dynamic Jahn-Teller effect in PrO2

Neutron spectroscopic measurements of the magnetic excitations in PrO2 reveal (1) sharp peaks characteristic of transitions between levels of the 4f(1) configuration of Pr4+ split by the cubic crystal field, and (2) broad bands of scattering centered near 30 and 160 meV. We present a simple model based on a vibronic Hamiltonian that accounts for these contrasting features of the data. The analysis shows that 90%+/-10% of the Pr ions have a localized 4f(1) configuration and provides strong evidence for a dynamic Jahn-Teller effect in the gamma(8) electronic ground state.     

Electric-dipole allowed (E1) and forbidden (E2, M1 and M2)transition probabilities of 4f for N+

By applying systematically enlarged multi-configuration Dirac-Fock wavefunction,the transitions for electricdipole allowed(E1) and forbidden(E2,M1 and M2) lines are studied among 4f pair coupling and low-lying configurations for singly ionized nitrogen.Most important effects of relativity,electron correlation,the rearrangement of electron density,Breit interaction,and quantum electrodynamic effects are included in the computation.Then,allowed(E1) and forbidden(E2,M1 and M2) transition probabilities of 4f for N+ are obtained and compared with experimental results.Good agreement with available experimental results is found and most of the data of 4f are presented for the first time.     

The 4s- and 4p- XPS spectra of Xe, XeF2 and XeF4

The 4s- and 4p- XPS spectra of Xe gas, XeF₂ molecule and XeF₄ molecule are calculated by an ab-initio atomic many-body theory. The 4s-peak and the prominent ‘4p’-peak are predicted well by the present theory. In XeF₂ and XeF₄ the spectral lines observed below the 4d-double ionization threshold are the 4d⁻²4f multiplet states strongly perturbed by the interaction with the initial 4p_1/2-hole state. They are very similar to the spectral lines which emerge with an increase in atomic number (e.g. Ba).     

Apodized 2f/1f wavelength modulation spectroscopy method for calibration-free trace detection of carbon monoxide in the near-infrared region: theory and experiment

We introduce the basics of an apodized 2f/1f wavelength modulation method for the spectroscopy of the R(9) transition line in the first overtone band of carbon monoxide (¹²C¹⁶O) in near-infrared (NIR) region around 2.33 μm. Performance of the method is investigated for high gas concentrations beyond the optically thin limit to generalize common 2f/1f wavelength modulation spectroscopy (WMS) reported by Rieker et al. (Appl Opt 48:5546, [28]). Numerical simulations are performed based on real experimental parameters associated with a NIR spectrometer designed in our laboratory. The results primarily show a more linear response and less error than occurred in the common WMS-2f/1f method for an optically thick sample. It is also theoretically shown that the apodized method enables sharpening the spectrum without peak displacement compared to the common WMS-2f/1f method. The validity of the method is verified experimentally by the trace detection of an air-broadened R(9) CO absorption line centered at 4,294.637 cm^?1 at atmospheric pressure and room temperature. The effect of a so-called scaling k-factor on the sharpening of WMS-2f/1f signal is investigated through trace simulation and detection of CO and methane (CH₄) lines in the scanning range of a distributed feedback laser. The obtained results show very good agreement between simulation and experiment.