The K-, L- and M-Auger and L-Coster-Kronig spectra of platinum

The K-, L- and M-Auger and L-Coster-Kronig spectra of platinum in the electron capture decay of ¹⁹⁵Au was measured by means of the Vanderbilt iron-free, double-focussing spectrometer. The energies and relative intensities of 55 peaks were measured in the L-Auger spectrum in the energy range of 5 to 12 keV. The intensities are compared to those calculated theoretically for silver by Asaad. The total L-Coster-Kronig plus M-Auger intensity (0 to 3.25 keV) was measured relative to the L-Auger intensity. The measured relative intensities of the KLL Auger lines are compared to the theoretical and experimental results of others. The measured KLL energies agree with those calculated semi-theoretically by Hörnfeldt and by Listengarten. A value of KLX/KLL = 0.548±0.044 was measured. A measurement of the KL₃L₃(³P₀)/KL₃L₃(³P₀+³P₂) ratio, the first reported in this Z-region, gave a value of 0.095±0.024.     

High-resolution KLM Auger spectra of Ni metal excited by X-rays

KLM Auger spectra of Ni metal were measured with high energy resolution and high statistical accuracy using monochromatic synchrotron radiation. The spectra were corrected for the background from inelastically scattered electrons using partial intensity analysis where the electron trajectories were calculated by Monte Carlo simulation. Following background correction, the corrected spectra were fitted to model peaks taking into account intrinsic excitations. The measured transition energy of the most intense KL₂M₃ (¹D₂) Auger line is 7388.1 eV (0.4). The obtained relative intensities and energies of the Auger diagram lines are compared to published calculations as well as to experimental data for other 3d transition metals. In addition, the presence of Ni 3s, 3p photoelectron peaks in the spectra excited internally by Ni K X-rays is shown.     

Interaction of atomic oxygen (N2O) with a clean Si(001) surface: O adsorption geometries as derived from the O KVV Auger lineshape

The room temperature adsorption of N₂O on the clean Si(001)2 × 1 surface was used as a model system in an Auger electron spectroscopy (AES) study presented in this paper. Earlier experimental and recent theoretical work have provided evidence that this reaction evolves in discernible stages each exhibiting different adsorption geometries for the oxygen atom. In this AES study the intensity ratio of the KL₁L₁ and KL_2,3L_2,3 O Auger transitions, , was measured as a function of the fractional oxygen coverage, θ, and compared with our calculated intensity ratios and binding energy measurements of the O 1s photoelectron from literature. As a result we have found, for the first time, that (θ) can be related to a specific adsorption geometry in the submonolayer range. Moreover, we have found experimental evidence for an intermediate stable O adsorption state on the dimer at low coverage (θ 0.2 monolayer), as proposed earlier from theoretical studies.     

锶原子互组跃迁谱的实验研究

观测了热原子束中锶原子(5s²)¹S₀—(5s5p)³P₁ 互组跃迁的荧光谱和饱和荧光谱, 实验测定了不同的参量下 ⁸⁸Sr(5s²)¹S₀—(5s5p)³P₁ 互组跃迁荧光谱. 研究结果表明: 不同的实验参数(温度、激光光强、激光扫描频率)对谱线有较大的影响, (5s5p)³P₁态的长寿命特点导致谱线强度随激光扫描频率呈倒数关系变化; 由于Doppler增宽, 渡越增宽等因素的影响, 谱线线宽远大于其自然线宽且随激光扫描频率呈正比关系变化.     

Investigation of the HFS in the 4d 5p zP3,4 states of Mo and Mo by levelcrossing spectroscopy

The hyperfine structures of the z⁷P₃ and z⁷P₄ states of ⁹⁵Mo and ⁹⁷Mo have been investigated by levelcrossing spectroscopy. A fit of the experimental signal curves yields the magnetic and electric hfs coupling constants: ⁹⁵Mo z⁷P₃ |A| = 86.19(10) MHz, |B|=5.2(30) MHz, A/B0⁹⁵Mo z⁷P₄ |A|=64.05(30) MHz, |B|=4.3(30) MHz, A/B<0; ⁹⁷Mo z⁷P₃|A|= 88.0(1) MHz, |B|=60.0(20) MHz, A/B<0; ⁹⁷Mo z⁷P₄ |A|=65.4(3) MHz, |B|=50.0(50) MHz, A/B0. For the ratio of the electric quadrupole moments we fine ⁹⁷Q/⁹⁵ Q= -11.5(70).     

Electronic and vibronic spectra of Pr in LiYF4

The polarized absorption and fluorescence spectra of Pr³⁺ in single crystals of LiYF₄ having the scheelite structure have been investigated and assignments made on the basis of S₄ site symmetry. Strong vibronic coupling associated with the ³H₄→³H₅, ¹D₂ transitions in absorption and the ³P₀→³H_4,6 transitions in fluorescence was observed. Using selection rules for vibronic coupling and the known k = 0 phonons, these “extra” features of the spectrum can be accounted for in polarization and frequency.     

Optical pumping of the 2p3sP0 State of Ne (I = 3/2): g factor and metastability exchange cross section

A C.W. multi-mode dye laser is used to obtain by optical pumping an orientation of the 2p⁵ 3s³P₀ (F = 3/2) state of ²¹Ne. A magnetic resonance experiment leads to the measurement of the g factor g (³P₀) = 3.027 (8) × 10⁻⁴ to be compared with the theoretical prediction (3.025(6) × 10⁻⁴). One obtains also the metastability exchange cross section σ(³P₀) = 18.4 ± 4 Ų for collisions between metastable (³P₀) Ne atoms and ground state Ne atoms. This result is compared with other measurements and theoretical evaluation.     

THEORETICAL INVESTIGATION OF THE ISOSPIN VIOLATING HADRONIC TRANSITIONS Ψ'→Ψ(11P1)+π° AND T"→T(11P1)+π°

The isospin violating processes Ψ'→Ψ(1¹P₁)+π° and T"→T(1¹P₁)+π° are investigated in the framework of the multipole expansion in quantum chromodynamics. Using the rate of Ψ'→Ψ+π° as an input to determine the isospin violating vertex, we obtain the following branching ratios for the processes BR(Ψ'→Ψ(1¹P₁)+π°)～10^-6-10^-5, BR(T"→T(1¹P₁)+π°)～10^-5-10^-3 for M₁1_p1=1/9(5M₁3_p2+3M₁3_p1+M₁3_p0). These are too small to be detected in the present experiments.     

The Hanle effect for the 3 S1/2 ↔ 3 P1/2 transition of sodium

Experimental results are reported for the Hanle effect on the 3 ²S_1/2 ↔ 3 ²P_1/2 transition of sodium at vapour densities between 10⁹ and 10¹² at/cm³.     

Analysis of temperature and 1 MeV proton irradiation effects on the light emission in bulk silicon (npn) emitter-base bipolar junctions

In this work, we present the temperature and 1 MeV irradiation proton effects on the light emission in bulk silicon emitter-base junctions for direct and reverse polarizations. Our samples were exposed at room temperature to 5.3 × 10⁸, 5.3 × 10¹⁰, 5 × 10¹¹, 5 × 10¹² and 5 × 10¹³ p cm⁻². The spectral range for which electroluminescence spectrums were recorded for forward and reverse polarizations is 0.6–2 eV. For forward bias, EL maximum intensity occurs at 1.0923 ± 0.0001 eV (structure (a)) which decreases as function of irradiation fluencies. For reverse bias, the spectra contain two structures (b) and (c). The first structure (c) occurred at 1.6243 ± 0.0013 eV is independent of irradiation while the second structure (b) decreases as function of fluencies irradiation. The Gaussian deconvolution of (b) shows two sub-structures (b₁) and (b₂) which are located, respectively, at 0.8064 ± 0.0004 eV and 0.9917 ± 0.0016 eV. We studied temperature dependence of full width at half-maximum (FWHM) and we found that the phonons involved in (a), (b₁) and (b₂) on the one hand and (c) on the other hand are not the same. Moreover, we obtained from the study of EL intensity temperature dependence that the activation energies of (a), (b₁) and (b₂) are identical and differ from that of (c). These effects enable us to conclude that visible light emission does not have the same origin as that in infra-red. From these observations, we can attribute the structures (a) and (b) to indirect inter-bands transitions and (c) to a direct intra-band transitions.     

双波长Pr3+掺杂12CaO·7Al2O3的光存储特性

采用化学共沉淀法制备了Pr3+掺杂的12CaO·7Al2O3(C12A7:Pr3+)材料.通过X射线衍射(XRD)、发射光谱、激发光谱、余辉衰减曲线、热释发光及光激励发光等测试手段系统研究了C12A7:Pr3+材料的微观结构和光学性质.结果表明,C12A7是一种理想的适合Pr3+掺杂的基质材料,C12A7:Pr3+具有...     

The role of excitons and substrate temperature in low-energy (5–50 eV) electron-stimulated dissociation of amorphous D2O ice

We have studied the interaction of low-energy (5–50 eV) electrons with nanoscale (10 ML) ice films by probing the yields and quantum-state distributions of the neutral dissociation products using laser resonance-enhanced multiphoton ionization spectroscopy. In particular, we have observed the electron-stimulated desorption (ESD) of D (²S), O (³P₂) and O (¹D₂) from amorphous D₂O films. These products are observed at threshold energies (relative to the vacuum level) between 6.5–7 eV and desorb with low kinetic energies (60–85 meV) which are independent of the incident electron energy. We associate the ESD of atomic fragments from ice with dissociation of Frenkel-type excitons of 4a₁ character which are near the bottom of the ice conduction band. These excitons are created either directly or via electron-ion recombination. Changing the surface temperature from 88 to 145 K results in an increase in the thermal component of the time-of-flight (kinetic energy) distributions and an overall increase in the neutral fragment yield. We suggest that the change in neutral yield with substrate temperature results from a combination of: (1) increased electron-ion recombination; (2) exciton transport to the near-surface region; and (3) dissociation followed by inelastic scattering and desorption.     

AlH~+离子5个Λ-S态和10个?态的光谱性质以及激光冷却的理论研究

利用考虑Davidson修正的内收缩多参考组态相互作用(icMRCI+Q)方法结合相关一致基组aug-ccpV6Z计算了AlH~+离子前两个离解极限对应的5个Λ-S态和10个?态的势能曲线.为了提高势能曲线的可靠性和精确性,计算中考虑了自旋轨道耦合效应、芯电子价电子相关和标量相对论修正以及将势能外推至完全基组极限.基于得到的势能曲线,获得了束缚和准束缚的4个Λ-S态和8个?态的光谱常数和振动能级,与已有的实验结果符合.计算了2(1/2)→X~2Σ_(1/2)~+和A~2Π_(3/2)→X~2Σ_(1/2)~+跃迁的跃迁偶极距.利用计算的精确的势能曲线和跃迁偶极矩,获得了2(1/2)~(第一势阱)(υ′=0, 1)→X~2Σ_(1/2)~+(υ′′)和A~2Π_(3/2)(υ′=0, 1)→X~2Σ_(1/2)~+(υ′′)跃迁的高度对角化分布的Franck-Condon因子(f_(00)和f_(11))和大的振动分支比;预测了2(1/2)~(第一势阱)(υ′=0, 1)和A~2Π_(3/2)(υ′=0, 1)态短的自发辐射寿命和窄的辐射宽度,这适合于AlH~+离子的快速激光致冷.所需的3束激光冷却波长都在紫外区域.这些结果表明了激光冷却AlH~+离子的可行性.此外,评估了自旋轨道耦合效应对光谱常数、振动能级和激光冷却AlH~+离子的影响.     

Laser frequency locking based on the normal and abnormal saturated absorption spectroscopy of ~(87)Rb

We present a practical method to avoid the mis-locking phenomenon in the saturated-absorption-spectrum laserfrequency-locking system and set up a simple theoretical model to explain the abnormal saturated absorption spectrum. The method uses the normal and abnormal saturated absorption spectra of the same transition 5~2S_(1/2), F = 2–5~2P_(3/2), F'= 3 saturated absorption of the ~(87)Rb D_2resonance line. After subtracting these two signals with the help of electronics, we can obtain a spectrum with a single peak to lock the laser. In our experiment, we use the normal and inverse signals of the transitions 5~2S_(1/2), F = 2–5~2P_(3/2), F'= 3 saturated absorption of the ~(87)Rb D_2 resonance line to lock a 780-nm distributed feedback(DFB) diode laser. This method improves the long-term locking performance and is suitable for other kinds of diode lasers.     

小型化锶光钟物理系统的研制

光钟物理系统的小型化是制约可搬运光钟及空间冷原子光钟发展的重要因素.主要介绍了小型化锶原子光钟物理系统的研制实验.采用真空腔内置反亥姆霍兹线圈,构建一个小电流、低功耗及小体积的磁光阱.实验中测得真空线圈通电电流仅为2 A时,磁光阱中心区域轴向磁场梯度可达到43 Gs/cm,完全满足锶原子多普勒冷却与俘获对磁场梯度的要求.目前已经成功将锶原子光钟物理系统体积缩小至60 cm×20 cm×15 cm,约为实验室原锶光钟物理系统体积的1/10,并且实现了锶原子的一级冷却,测得俘获区冷原子团的直径为1.5 mm,温度约为10.6 mK.锶同位素~(88)Sr和~(87)Sr的冷原子数目分别为1.6×10~6和1.5×10~5.重抽运激光707和679 nm的加入,消除了冷原子在~3P_2和~3P_0两能态上的堆积,最终可将冷原子数目提高5倍以上.     

kiow.to Search for 'p1 State of CC at BEPC-The Electromagnetic Transition Ψ' -+Ψ('p1) + 2Y1

Decay rate of the process Ψ'→Ψ(¹P₁)+2γ is calculated with all possible intermediate states included in the context of potential model. Out calculation shows that the branching ratio for this channel is about 10^-5.For a total production of 2×10Ψ' particles, it is possible to find out Ψ' (¹P₁) at BEPC through searching for 3γ signals.     

氦原子2~3S—2~3P精密光谱研究

氦原子是最基本的多电子原子,其精密谱是十分理想的检验多电子量子电动力学计算的平台,同时也是利用原子能级结构测定精细结构常数α的理想体系,还能获得原子核结构信息.本文结合我们团队的工作,综述基于氦原子的少体原子精密光谱研究.其中,主要包括氦原子2~3P_J精细结构分裂,以及2~3S—2~3P跃迁频率测定等研究,并对相关工作的前景进行了展望.     

Nb/Au/(1 1 0)YBa2Cu3O7−δ Josephson junctions: evidence against atomic scaled “corner junctions”

We report on I–V characteristics for in situ formed Nb/Au/(1 1 0)YBa₂Cu₃O_7−δ (YBCO) Josephson junction, where the homoepitaxial (1 1 0)YBCO film shows ultra-smooth surface morphology. The field dependence of critical supercurrent I_c shows anisotropic large junction behavior with normal Fraunhofer patterns expected from BCS model of d_x²−y² wave superconductors. This strongly suggests that the Nb/Au/(1 1 0)YBCO junctions cannot be regarded as atomic scaled corner junctions, in contrast with (0 0 1)/(1 1 0)YBCO grain boundary junctions to show “π-junction” with a pronounced dip near zero fields in field modulation of I_c.     

新型电子俘获型光存储材料Sr2SnO4:Sb3+的发光性能研究

采用高温固相法在1300℃的温度获得了一种新型电子俘获型光存储材料 Sr₂SnO₄:Sb³⁺. 结果表明: 208 nm (Sb³⁺ 的¹S₀→¹P₁)和265 nm (¹S₀→³P₁)的紫外光是Sr₂SnO₄:Sb³⁺ 的最有效信息写入光源; 其发射是覆盖400---700 nm的宽带(³P_0,1→^XXS₀), 肉眼可看到淡黄色白光, 色坐标为(0.341, 0.395). 热释光谱研究结果表明: Sr₂SnO₄:Sb³⁺ 有分别位于39℃, 124℃, 193℃和310℃的四个热释峰. 其中, 39~℃的热释峰强度很低, 因而Sr₂SnO₄:Sb³⁺ 只具有不到140 s的微弱余辉. 而310℃的高温热释峰在空置1天后, 仍能保持约45.6%的初始强度, 并对980 nm的红外光有很好的红外上转换光激励响应. 因此, Sr₂SnO₄:Sb³⁺ 是一种具有一定的信息存储应用潜力的新型光存储发光材料.     

Auger-vacancy satellites in the decay of 82Pb (RaD)

The L-Auger spectrum of ²¹⁰Bi from RaD (²¹⁰Pb) has been studied with a resolution of 0.18% and a very thin source but with some sacrifice in statistics. A total of 65 lines or line groups have been wholly or partially identified. The L₃-MM lines, most of which result from filling L₃ vacancies created by the L₁-L₃M_{4, 5} Coster-Kronig process, are displaced an average of −36±5 eV with respect to the energies expected from the L_{1, 2}-MM spectra. This effect is the Auger analogue of the phenomenon of X-ray satellites. The L₃-M₄M₅ and L₃-M₅M₅ displacements agree within experimental error with predictions from the displacements of the strongest L₁ and L₂ X-ray satellites. We suggest the term Auger-vacancy satellites for these displaced Auger lines to distinguish them from the weak lines of the K-LL spectrum for which we suggest the term Auger Intermediate-Coupling Satellites. The ratio (L₁-M₄M₅ Auger Line)/L₁-vacancies = R = 32.5±3.5, which may have importance in determining L₁ capture as distinct from L-capture, was also measured for the first time. The end-point of the low-energy beta spectrum of ²¹⁰Pb was found to be 17.0±0.5 keV.