运用光电流光谱测定钬原子能级的超精细结构

用自制钬空心阴极灯,运用光电流光谱技术在569nm～600nm谱区内首次测定了元素钬的9条谱线,确定其相应跃迁能级,及超精细结构常数.     

Wavelength calibration of narrowband ArF laser with iron hollow cathode lamp

Accurate and precise wavelength controlling of narrowband excimer lasers is essential for the lithography of an integrated circuit. High-precision wavelength tuning and calibration of a line-narrowed Ar F laser are presented in this work. The laser spectrum is narrowed to a sub-picometer with a line narrowing system. Absolute wavelength calibration of the line-narrowed laser is performed based on the optogalvanic(OG) effect using iron hollow cathode discharge(HCD). An sccuracy of better than 0.1 pm for wavelength tuning and calibration is achieved with our homemade wavemeter.     

Analysis of dynamical optogalvanic effect of Ne in the μs region observed by chopped CW laser. Evidence for collisional mixing and the role of the atoms near the cathode surface

The transient optogalvanic spectrum of Ne 585.2, 588.2, and 603.0 nm lines was observed using a chopped CW dye laser in the negative glow region of a hollow cathode lamp. The analysis revealed that the signal originates mainly from the vicinity of the cathode surface and that the hitherto utilized model of the effect has to be generalized to include the colisional mixing among nearby levels into the rate equations for the population distribution among atomic levels.     

Magnetic Field Enhancement of the Optogalvanic Signal in a Hollow Cathode Discharge

An optogalvanic signal enhancement was obtained in a magnetic field applied on a hollow cathode discharge-detector. In this magnetic field a mutual correlation was observed between optogalvanic signal behaviour, discharge current change and lower level population of the transition corresponding to the 632,8 nm laser irradiation spectral line.     

Optogalvanic spectroscopy of sputtered atoms

Optogalvanic Spectroscopy (OGS) is finding wide ranging applications in atomic structure studies, laser wavelength calibration, intensity and frequency stabilization of lasers and analytical chemistry. Sputtered atoms produced in a hollow cathode lamp by the bombardment of a rare gas discharge is a convenient source for optogalvanic spectroscopy work. Here, we discuss the sputtered ion/atom optogalvanic spectroscopy applications to low resolution atomic spectroscopy, laser wavelength calibration, studies of radioactive samples available in limited quantities, studies of atoms in highly excited states and Rydberg atoms and high resolution laser spectroscopy. For the sake of completeness, we list other applications of OGS without going into details.     

Theory of Optogalvanic Signals Originating from Metastable States in Hollow Cathode Neon Discharges

A previous theoretical model is enlarged to elucidate some features of the optogalvanic signals originating from the metastable states in hollow cathode neon discharges. Numerical experiments were performed on the basis of this model to obtain the time evolution of the optogalvanic signals in pulsed and chopped cw experiments at 588.2 nm for different discharge currents and different laser intensities. The predictions of the numerical experiments were found to be in qualitative agreement with real experimental results.     

Spatial variation of the linewidth of Kr atomic lines as observed on optogalvanic signals in cathode fall region of hollow cathode discharge

An abrupt change in the spectral width of optogalvanic (OG) signals of Kr atomic lines has been observed at a distance from the cathode wall where the signal itself changes its sign, by using a hollow cathode lamp whose cathode has its both ends open. The width is broader near the cathode wall with its magnitude varying by discharge current while the narrower width which is obtained on passing the laser beam in the central region of cathode cylinder is independent of the current. It is suggested that a well-defined region, where the particles of larger cross section of collisions with Kr atom are confined, is present in front of the cathode wall.     

A simple method for the optogalvanic detection of argon ion transitions in hollow-cathode lamps

Summary We describe a simple method for the observation of argon ion transitions in hollow-cathode lamps, using the optogalvanic effect, and report the first optogalvanic detection of the six ArII transitions: 457.9 nm, 476.5 nm, 488.0 nm, 496.5 nm, 501.7 nm and 514.5 nm. We also study the optogalvanic signal as a function of the incident laser power and the lamp current. Partial financial support of CNPq and FINEP (Brazil).     

铥原子激发能级超精细结构常数的测定

用铥空心阴极灯,采用光电流光谱技术测得铥原子21条一级跃迁谱线,确定了相应跃迁上能级的超精细结构常数,其中7个能级的参数为首次发表,运用同一空心阴极灯,采用双色双光子级联共振技术,由荧光法首次测得4个第二激发能级的超精细结构常数.     

Chopped CW laser-induced optogalvanic effect in a neon hollow cathode discharge

A detailed model for the optogalvanic effect in a neon hollow cathode discharge irradiated by a chopped CW dye laser is presented. A rate equation formalism is used to calculate the evolution of the first and second electronic configuration populations coupled by the laser and of the electric charges number density. Processes as ambipolar-like electrons loss, electronic collisional coupling of level populations and electron emission by the cathode due to VUV radiation from the 1s ₂ resonant level are taken into account and further discussed.The transients and steady-state magnitude of the optogalvanic signal are calculated, compared with experimental data and related to population changes. We predict sign changes of the optogalvanic signal when the laser is tuned over transitions originating from the resonant level with respect to transitions involving the metastables states. The optogalvanic signal is shown to be basically determined by the laser-induced variations of the excited-state populations while changes in the electron temperature, due to laser energy transfer by collisions between electrons and excited atoms, play a negligible role.     

Optogalvanic Indication of Small Continuous Spectrum Distribution Shift

An optogalvanic method based on the shift of the continuous spectrum frequency distribution is proposed. The accuracy of the shift indication depends on the frequency distribution of the absorbing transitions in the optogalvanic detector spectrum. The absorption in Ne/Cu hollow cathode discharge lamp is analysed in order to investigate the behaviour of the spectrum emitted by a red AC EL panel.     

Hyperfine structure in the atomic spectrum of niobium

We report on hyperfine structure measurements in 21 lines of atomic niobium in the spectral region from 640 nm to 870 nm by means of optogalvanic laser spectroscopy and laser induced fluorescence spectroscopy using a hollow cathode discharge and a tunable single-mode cw ring laser. Hyperfine structure constants A and B of altogether 29 excited energy levels were determined, 18 of them for the first time. Received 18 July 2002 / Received in final form 8 November 2002 Published online 4 February 2003 RID="a" ID="a"e-mail: sk@kalium.physik.tu-berlin.de     

Observation of the opto-galvanic effect in neon and argon using a nanosecond dye laser

The dynamic behavior of the opto-galvanic-effect (OGE) in Ar and Ne using a ns-dye-laser is described. The OEG signals observed by us can be subdivided into two types, which show characteristic differences in the dependence of the OEG signal on the hollow cathode lamp current.     

Optogalvanic detection of velocity-selective optical pumping in an open, cascade atomic medium

We performed two-color spectroscopy of the (4s²) ¹S₀ → (4s4p) ¹P₁ → (4p²) ¹D₂ calcium atomic transition and observed velocity-selective optical pumping in a calcium hollow cathode lamp by means of optogalvanic detection. The optical pumping signature in optogalvanic detection is compared to that of fluorescence and transmission detections. The optogalvanic technique is found to be a very sensitive method of detecting optical pumping and could be used in distinguishing optical pumping from electromagnetically induced transparency.     

Non-Resonant Photoionization Optogal Vanic Effect in Hollow Cathode Glow Discharge

Abstract

This non-resonant optogalvanic effect caused by photoionization of the atoms lying at high excited levels is investigated in this work on the base of Neatoms in a hollow cathode glow discharge.     

光电偶效应和光束整形对激光稳定气体保护焊接的增益

为了开发和改进激光诱导稳定焊接加工技术,需要通过激光辐射使电弧的导电率达到最大值。光电偶效应是控制该过程的主导因素,该过程的优化将会保证电弧的稳定性。光电偶效应提高了等离子体粒子电离的概率,从而提高了电弧的导电率。激光光子和氩原子之间的电子-原子碰撞相互作用产生了带电粒子。电离率越高,电弧的导电率就越高。为了充分利用光电偶效应,我们还应考虑工件上的光束焦点位置、光束形状和激光波长因素。     

空心阴极元素灯光谱的空间分布测量方法

提出利用成像光谱仪研究空心阴极元素灯光谱空间分布的检测方法。自制了基于Offner成像系统的推扫式凸面光栅成像光谱仪,覆盖波长范围400~1 000 nm,视场角22°,光谱分辨率2~3 nm;利用该光谱仪第一次得到得到Hg元素灯光谱的空间分布,给出了不同波长下的空间图像和不同空间位置的光谱分布信息,具有较高的空间分辨率和光谱分辨率;并同时获取了不同工作电流条件下的元素灯高光谱数据,对比分析了处于不同工作状态下光谱空间分布的差异。这为空心阴极元素灯光谱的空间分布等性能研究提供了一个很好的工具,相关方法也可以用来研究其他类型的光源。     

Laser excited population redistribution in the 2p3p multiplet in neon

Using neon hollow cathode lamp and employing laser optogalvanic technique, we have studied population redistribution in the 2p⁵3p multiplet. The spectra recorded in the laser energy region of 23300 cm^− 1 -23600 cm^− 1 show transitions originating from both the laser excited levels as well as from an adjacent level whose population builds up as a result of collisional deactivation. Employing the optical delay technique, we have been able to extract decay rates associated with the collisional population mixing of the p levels.     

Color center laser optogalvanic spectroscopy of lithium,barium, neon and argon Rydberg states in hollow cathode discharges

Numerous infrared transitions between Rydberg states of neon and argon have been measured by optogalvanic spectroscopy in commercial hollow cathode lamps using a color center laser operating in the range 3600–4100 cm^-1. Transitions in lithium and barium atoms sputtered from the cathodes were also detected. The generality and high sensitivity of this technique indicates potential applications for frequency calibration in the infrared, atomic and molecular spectroscopy, and plasma diagnostics.     

Frequency stabilization of a 399-nm laser by modulation transfer spectroscopy in an ytterbium hollow cathode lamp

The modulation transfer spectroscopy in an ytterbium hollow cathode lamp at 399 nm is measured. The error signal for frequency locking is optimized by measuring the dependences of its slope, linewidth and magnitude on various parameters. Under the optimum condition, the laser frequency at 399 nm can be stabilized. The long-term stability of laser frequency is measured by monitoring the fluorescence signal of the ytterbium atomic beam induced by the locked laser. The laser frequency is shown to be tightly locked, and the stabilized laser is successfully applied to the cooling of ytterbium atoms.