半导体泵浦铯蒸气实现激光输出

采用线宽0.26 nm的Littrow外腔巴条半导体激光器泵浦增益长度8 mm缓冲气体为80 kPa甲烷的铯（Cs）蒸气室,在Cs蒸气室温度120 ℃时,我们获得了394 mW的894.6 nm线偏振Cs蒸气激光,光光效率7.4%,斜率效率11.2%,阈值功率为1.72 W。     

Electrical resistivity of liquid cesium

The temperature dependences of liquid cesium resistivity are calculated using smooth nonlocal model pseudopotentials (SNMP). The calculations were performed for temperatures of 35, 150, 280, 310, 470, and 630°C, both with temperature-dependent SNMP parameter variations and without them. The SNMP parameters of liquid cesium were determined based only on the experimental values of free ion terms without applying any methods of adjustment to the electrical resistivity of cesium. Application of SNMP makes it possible to substantially improve the similarity of the temperature dependences for calculated and experimentally obtained electrical resistivities of liquid cesium as compared to the calculations based on local model potentials.     

Stage structure in cesium doped pentacene

We have prepared the cesium doped pentacene film and have investigated the electrical properties, in order to investigate a new molecular conductive film based on pentacene. It was found that cesium is doped in the pentacene film and that electrical resistivity decreases drastically below 10 Ω cm. Moreover, in the doping process, we found the step-wise decrease of electrical resistivity. It is deduced from this result that the cesium doped pentacene forms stage structures. In addition, we have carried out the measurements of the X-ray diffraction pattern in the cesium doped pentacene film. It was found from these results that the cesium doped pentacene becomes a highly orientated intercalated conductive film. Furthermore, in the cesium doped pentacene we have observed the shift of (00l) diffraction peak to low diffraction angle. This result indicates that by doping of pentacene the c-axis lattice constant which is the length of the interval between the (001) planes becomes 1.59 nm in the stage-1 structure of the cesium doped pentacene.     

半导体泵浦铯蒸气实现激光输出

采用线宽0.26nm的Littrow外腔巴条半导体激光器泵浦增益长度8mm缓冲气体为80kPa甲烷的铯(Cs)蒸气室,在Cs蒸气室温度120℃时,我们获得了394mW的894.6nm线偏振Cs蒸气激光,光光效率7.4%,斜率效率11.2%,阈值功率为1.72W。     

Graphene traps for cesium atoms

A significant increase in the surface concentration of cesium atoms intercalated under graphene islands on rhodium has been revealed when annealing the adsorbed layer in a ultrahigh vacuum. Heating leads to a decrease in the area of graphene islands due to the solution of carbon atoms in the metal bulk. At the same time, the edge carbon atoms in the islands, which are coupled with the surface by chemisorptive forces, prevent the leakage of the alkali metal from under the islands. This leads to the significant compression of cesium and to an increase in its surface concentration under the islands by a factor of almost 10. The desorption of cesium is observed only after the complete thermal destruction of graphene islands.     

Diode-pumped 10 W continuous wave cesium laser

An efficient cesium vapor laser pumped with a continuous wave laser diode array has been demonstrated. The linewidth of the pump source was narrowed using the external cavity to match it to the cesium absorption line. The output power of the continuous wave cesium laser was 10 W, which exceeds previous results by more than a factor of 10, and the slope efficiency was 68%. The overall optical efficiency was 62%, which is a factor of 6 higher than previous pulsed laser results for alkali lasers with diode laser array pumping.     

Theoretical and experimental determinations of cesium oscillator strengths

The oscillator strengths of the cesium atom have been calculated theoretically using a semi-empirical construction of the effective potential acting on the valence electron. The results are compared with those deduced from an experimental determination in a quiescent cesium plasma.     

基于艳原子线性法拉第磁光效应的应用

分析了(銫) (Cs)原子作为旋光介质的线性法拉第磁光效应.采用二能级模型解释了(銫)原子与光的相互作用,并利用琼斯矩阵推导了当激光器的频率处于(銫)原子共振线时,经过(銫)气室的线偏振光的旋转角与外加磁场的关系式,利用此关系式可测量磁场强度的大小和气室内(銫)原子的浓度.实验采用852nm分布反馈半导体激光器作为光源...     

Electron-stimulated desorption of cesium atoms from cesium layers deposited on a germanium-coated tungsten surface

The yield and energy distribution of Cs atoms from cesium layers adsorbed on germanium-coated tungsten were measured, using the time-of-flight technique with a surface-ionization-based detector, as a function of the energy of bombarding electrons, germanium film thickness, the amount of adsorbed cesium, and substrate temperature. The threshold for the appearance of Cs atoms is ～30 eV, which correlates well with the germanium 3d-level ionization energy. As the electron energy increases, the Cs atom yield passes through a broad maximum at ～120 eV. For germanium film thicknesses from 0.5 to 2 monolayers, resonance Cs yield peaks were observed at electron energies of 50 and 80 eV, which can be related to the tungsten 5p and 5s core-level ionization energies. As the cesium coverage increases, the Cs atom yield passes through a flat maximum at monolayer coverage. The energy distribution of Cs atoms follows a bell-shaped curve. With increasing cesium coverage, this curve shifts to higher energies for thin germanium films and to lower energies for thick films. The Cs energy distribution measured at a substrate temperature T = 160 K exhibits two bell-shaped peaks, namely, a narrow peak with a maximum at ～0.35 eV, associated with tungsten core-level excitation, and a broad peak with a maximum at ～0.5 eV, deriving from the excitation of the germanium 3d core level. The results obtained can be described within a model of Auger-stimulated desorption.     

微通道板碘化铯膜层抗潮解超薄保护膜层北大核心CSCD

碘化铯膜层对紫外光以及X射线具有很高的光电转换效率,但在空气中容易发生潮解。介绍了微通道板碘化铯膜层抗潮解超薄保护膜层的制备与保护效果。使用扫描式电子显微镜(scanning electron microscope,SEM)对碘化铯薄膜光阴极微通道板的镀膜深度和厚度进行测试,采用氧化铝作为碘化铯薄膜光阴极的保护膜层,并分别制备了厚度为2 nm、5 nm和10 nm的氧化铝保护膜层。在空气中存放不同时间后,碘化铯薄膜光阴极微通道板表面未发生明显潮解变化,其增益约为8800,暗计数率约为4.1 counts·s^(−1)·cm^(−2)。试验证明,氧化铝能够作为微通道板碘化铯膜层抗潮解超薄保护膜层。     

Cold cesium molecules produced directly in a magneto-optical trap

We report on the observation of ultracold ground electric-state cesium molecules produced directly in a magneto- optical trap with a good signal-to-noise ratio. These molecules arise from the photoassociation of magneto-optical trap lasers and they are detected by resonantly enhanced multiphoton ionization technology. The production rate of ultracold cesium molecules is up to 4×10⁴ s^-1. We measure the characteristic time of the ground electric-state cesium molecules generated in the experiment and investigate the Cs₂⁺ molecular ion intensity as a function of the trapping laser intensity and the ionization pulse laser energy. We conclude that the production of cold cesium molecules may be enhanced by using appropriate experimental parameters, which is useful for future experiments involving the production and trapping of ultracold ground electric-state molecules.     

High pressure effect on the thermopower of cesium

The thermopower of cesium has been measured in the region of existence of four phases (I, II, III, and IV) at high pressures up to 7 GPa. The initial phase of cesium and three phases formed under pressure with various crystal structures have a positive thermopower. The thermopower of all three high-pressure phases decreases in magnitude as the pressure increases.     

Observation of electromagnetically induced transparency in cesium molecules

We have studied electromagnetically induced transparency (EIT) in diatomic cesium molecules in a vapor cell by using tunable diode lasers. We have observed a sub-natural Λ-resonance in absorption molecular band B ¹Π _u − X ¹Σ _g ⁺ at different cesium vapor pressures. The width of the EIT resonance shows a linear dependence on a cesium vapor pressure.     

长程铯里德堡分子的势能曲线

本文介绍了半经典近似下的低能电子-原子散射理论, 引入贋势描述里德堡电子与基态原子的相互作用, 数值计算了铯原子nS (n=30-60)里德堡态与6S基态原子形成的长程里德堡分子的势能曲线. 并对最外层势阱进行分析, 获得长程里德堡分子的势阱深度、平衡距离与主量子数n的关系. 为实验制备里德堡分子并进一步分析其性质提供理论依据. 里德堡分子对外界非常敏感, 可用于微弱信号的检测.     

Electronic properties of cesium ultrathin coatings on the Ga-rich GaAs(100) surface

The cesium submonolayer coatings on the Ga-rich GaAs(100) surface at different coverages have been investigated by threshold photoemission spectroscopy. The electronic spectra of surface states and the ion-ization energies are analyzed. At a cesium coverage of about one-half the monolayer, the spectrum exhibits two narrow adsorption-induced bands below the Fermi level. This indicates that cesium atoms interacting with gallium dimers occupy two nonequivalent positions. It is found that the gallium broken bonds are saturated at the cesium coverage of ～0.7 monolayer, and the adsorption bonding is predominantly covalent in character. At the coverages close to the monolayer, broad bands with energies of 1.9, 2.05, and 2.4 eV have been observed for the first time. These bands can be associated with the excitation of cesium islands, cesium clusters, and surface cesium plasmon, respectively. The results obtained suggest two adsorption stages characterized by the formation of strong and weak bonds.     

Optical pumping of cesium atoms with second resonance light

We report the first successful optical pumping of cesium atoms to a state of high spin polarization with a CW dye laser tuned to the D₁ second resonance line (4593 Å) of the cesium atom. Results of spin polarization versus laser power measurements for cells containing high-density cesium vapors (10¹³–10¹⁵ cm^-3) plus mixtures of nitrogen (10–200 torr) and helium (≈1 atmosphere) gases are presented. These experiments have revealed unexpected limits to the spin polarization of dense alkali vapors.     

The optical properties of expanded liquid cesium

Abstract

The density dependence of the optical properties of expanded cesium has been investigated by means of reflectivity measurements in the range 0.5 – 4.0 eV. The dielectric functions ?₁ (ω) and ?₂(ω) have been derived by means of a modified Kramers-Kronig analysis. The data give useful information about the variation of the electronic structure of liquid cesium with large changes in density, large enough to reveal the existence of precursors of the metal-nonmental transition.     

Measurement and modeling of work function changes during low energy cesium sputtering

In this paper, a H-terminated silicon wafer was bombarded by low energy cesium ions during ToF-SIMS analysis and work function variations of the target were measured for different analysis conditions. This measurement was performed by measuring the shift of the secondary ions energy distributions with a reflectron type analyzer. At first, the silicon’s work function change was found to be −2.3 eV during 500 eV Cs⁺ bombardment at 45°. This effect is due to the creation of a dipolar layer at the surface of the silicon by the implanted cesium. Then the work function variation was measured at 300 eV for varying cesium surface concentrations. The work function was found to decrease monotonously with the increasing cesium surface concentration, as during cesium adsorption experiments. The results were modeled following three different approaches and the value of the effective polarizability α of cesium was found to be equal to 1.9 × 10⁻³⁹ C m²/V. Finally, the effect of the bombardment energy on the work function variation was studied for beams with energies ranging from 250 to 2000 eV. The effective polarizability of cesium was found to increase with increasing Cs beam energy.     

Modeling of a diode transverse-pumped cesium vapor laser

A physical model is established to demonstrate the mechanism and the kinetic process of a diode transverse-pumped cesium vapor laser. The distribution of pump laser power is described, and the effects of parameters such as the temperature, the cell length and the output coupler reflectivity on the output performance of a cesium vapor laser are simulated and analyzed. The simulation results agree well with the experiment data which shows the validity of this model. A set of optimization parameters is achieved for improving the output characteristics of a diode transverse-pumped Cs vapor laser.