Multiphoton mass spectra of Xe2 molecules in the range of excited Xe*(6p, 5d) atoms

The (2 + 1) photoionization mass spectra of Xe₂ molecules are studied in a supersonic jet upon excitation by laser radiation in the energy range 80321.3–77821 cm^?1, corresponding to the dissociation of the Xe₂ molecule into atoms Xe(¹ S ₀) + Xe*(6p, 5d). Several vibrational progressions are observed, which are attributed to two-photon transitions of Xe₂ from the ground state to the excited states of the O ⁺ _g, 1_g, and 2_g symmetries. Based on the analysis of these progressions, the molecular constants of a number of excited states of Xe₂ are estimated.     

Multiple Auger Decay Following Xe+(4p3−1/2)Ionization

The Auger decay for the many-electron Xe+(4p3^?1/2)state is studied in detail,using multistep approaches.It is found that the single Auger decay channels are primarily Coster–Kronig processes,which is in accord with other theoretical and experimental results.The double and triple Auger decays result primarily from cascade processes,i.e.,the sequential two-step and three-step Auger decay,and as such,the contributions from direct processes can be neglected.Level-to-level rates for single,double,and triple decays are obtained,based on which comprehensive Auger electron spectra and ion yields are obtained.Our decay paths and Auger electron spectra are in agreement with the experimental analysis[Hikosaka et al.,Phys.Rev.A 76(2007)032708],and our ion yield ratios(Xe²⁺:Xe³⁺:Xe⁴⁺=4.6:87.0:8.4)are also in line with their values(5.0:86.0:9.0).However,with respect to the ion yield ratios,a discrepancy still remains among the experimental and theoretical results.Taking into account the complexity of Xe’s electronic structure,further,more detailed experiments are still required.     

Determination of the 5d6p 3F4-5d2 3F transition probabilities of Ba I

Whether the transitions between 6s5d ³D and 5d6p ³F can be used for laser cooling of barium heavily depends upon the transition probabilities of 5d6p ³F-5d^{2 3}F. Taking the transition 6s5d ³D₃-5d6p ³F⁴ as a scale, the leakage rate of 5d6p ³F₄-5d^{2 3}F was used to evaluate the transition probabilities. 706 nm laser pulses with different durations were applied to a barium atomic beam for 6s5d ³D₃-5d^{2 3}F₄ optical pumping, and the remaining percentages in 6s5d ³D₃ were measured. After exponential fitting, the transition probability of 5d6p ³F₄-5d^{2 3}F_3,4 was determined to be 2.1(4)×10⁴ s^?1, which is in agreement with theoretical calculations using the scaled Thomas-Fermi-Dirac method.     

Isotope shift and hyperfine structure of the transition5d6s 2 2 D 3/2-5d6s6p 4 F 3/2 of Lu175 and Lu176

Using a tunable single mode dye laser the isotope shift of the 573.7 nm-line between the isotopes Lu¹⁷⁵ and Lu¹⁷⁶ has been determined to be IS(176?175, 573.7 nm)=?394(5) MHz yielding a change of mean square nuclear radii ofδ〈r ²〉=0.022(5) fm². In addition from our measurements the following values of the hyperfine splitting constantsA andB could be deduced Lu¹⁷⁶ 5d6s6p ⁴ F _3/2:A=?651.4(0.3) MHz,B=2,494(4) MHz 5d6s ^{2 2} D _3/2:A=138.0(0.3) MHz,B=2,131(3) MHz Lu¹⁷⁵ 5d6s6p ⁴ F _3/2:A=?924.7(0.5) MHz,B=1,767(4) MHz.     

Hyperfine structure and isotope shifts in the 5d6s2 a2D3/2--5d6s(a3D)6p z4F5/2 ° transition of Hf II

The hyperfine structure and isotope shifts of the transition between the 5d6s² a²D_3/2 ground state and the 5d6s(a³D)6p z⁴F_5/2 ^° excited state of singly ionized hafnium at \lambda=340 nm have been investigated by laser spectroscopy using a radio-frequency quadrupole ion trap. The magnetic dipole coupling constant A and electric quadrupole coupling constant B of the two atomic levels for both stable isotopes ¹⁷⁷Hf and ¹⁷⁹Hf are determined. The changes of mean square nuclear charge radii \delta[ r²] of the stable Hf isotopes and the radioactive isotope ¹⁷²Hf (T_1/2=1.87a) have been extracted from the data. This revised version was published online in August 2006 with corrections to the Cover Date.     

Observation and characterization of the fluorescence decay of the 2s2p(6)np 1P(o) excited states of Ne

Fluorescence decay of the 2s2p(6)np (1)P(o) excited states of neon has been observed directly for the first time. This process has also been observed indirectly by threshold photoelectron spectroscopy and in electron/photon coincidences. The measurements have allowed this weak decay channel to be characterized and branching ratios derived. The fluorescence excitation spectrum is well described by a simple Rydberg model that highlights the interplay and competition between the decay channels of autoionization and fluorescence.     

The study of ungerade electronic states of the Xe2 molecules in the region of Xe*(5p 56p, 5d, 7s, 6d) by the resonance multiphoton ionization method

Electronic spectra of the Xe2 molecules in the energy range of 77700?C89300 cm^?1 are recorded. The method of resonance enhanced multiphoton ionization of molecules in a supersonic molecular beam was used, in which excitation of the molecules by three photons was followed by ionization caused by a fourth photon (the (3+1) REMPI method). Analysis of the vibrational structure of observed systems of bands yielded information about the dissociation energy and the molecular constants for ungerade states of molecules. On the basis of the Franck-Condon principle, the equilibrium distances for potential curves were estimated from the relative intensities in vibrational progressions. Data on 16 new electronic states of diatomic xenon molecules with the dissociation limits Xe ₂ ^* ?? XE(5p ^{6 1} S ₀) + Xe*(5p ⁵6p,5d, 7s, 7p) were obtained.     

Measurement of absolute cross sections for excitation of the 3s(2)3p(5) 2P(o)(3/2)- 3s(2)3p(5) 2P(o)(1/2) fine-structure transition in Fe9+

Experimental cross sections are reported for the 3s(2)3p(5) 2P(o)(3/2)- 3s(2)3p(5) 2P(o)(1/2) transition in Fe9+ located at 1.945 eV. The center-of-mass interaction energies are in the range of 1.72 eV (below threshold) through threshold, to 5.6 eV (2.9 x threshold). Data are compared with results of a 49-state Breit-Pauli R-matrix theory. The experiment detects structures at 3.5 and 4.6 eV corresponding to enhancement of the direct excitation via many narrow, closely spaced resonances about these energies calculated by the theory. Iron is present in practically every astrophysical object, as well as being an impurity in fusion plasmas. Present data are the first electron-energy-loss measurements on a highly charged iron ion.     

Photoionization cross section of Xe+ ion in the pure 5p5 2P3/2 ground level

Coupling an ion trap with synchrotron radiation is shown here to be a powerful approach to measure photoionization cross sections on ionic species relaxed in their ground state. The photoionization efficiency curve of Xe+ ions stored in a Fourier transform ion cyclotron resonance ion trap was recorded at ELETTRA in the 20-23 eV photon energy range. Absolute cross sections were derived by comparison of the photoionization yield of Xe+ with measurements from the ASTRID merged-beam experiment. Multiconfiguration Dirac-Fock calculations were performed for the interpretation of these new data.     

C~+离子内壳激发共振态1s2s(~3S)2p~3的Auger能量和Auger分支率(英文)

利用精确的鞍点变分波函数和鞍点复数转动方法,计算了C⁺离子五电子原子系统内壳激发共振态1s2s（³S）2p^32,4P°,^2,4D°的俄歇能量和俄歇分支率,考察了俄歇跃迁的收敛性,对300 keV C⁺离子和CH₄气体碰撞实验产生的高分辨率俄歇电子谱进行了标定,并指出这些类硼C⁺离子的内壳激发共振态对253～273 eV范围的实验谱线有重要贡献.本文计算结果与实验数据符合得很好.     

C+离子内壳激发共振态1s2s(3S)2p3的Auger能量和Auger分支率

利用精确的鞍点变分波函数和鞍点复数转动方法,计算了C+离子五电子原子系统内壳激发共振态1s2s(3S)2p3 2,4Po, 2,4Do 的俄歇能量和俄歇分支率,考察了俄歇跃迁的收敛性,对300-keV C+离子和CH4气体碰撞实验产生的高分辨率俄歇电子谱进行了标定,并指出这些类硼C+离子的内壳激发共振态对253-273eV范围的实验谱线有重要贡献. 本文计算结果与实验数据符合得很好.     

Origin of threshold electrons produced in decay of the Xe 4d−1 np resonance

Coincidence spectra of energetic electrons with threshold electrons were measured following photo-excitation of the Xe 4d_3/2, 5/2 → np resonances, in order to investigate the origin of threshold electrons, and the mechanism leading to formation of the Xe²⁺ 5p⁻² and 5s⁻¹5p⁻¹ final states. A two-step decay process was observed in the production of Xe²⁺ 5p⁻²(¹D) following decay of the 7p resonance, where the intermediate state is Xe^+* 5p⁻²(¹S)8p that autoionizes emitting a pseudo-threshold electron. This process was confirmed in a time-of-flight analysis of the coincidence spectra of the energetic electrons with the threshold photoelectrons. It is suggested that a similar two-step process also contributes to the population of excited Xe²⁺ states and is the main origin for the production of threshold electrons in decay of the 4d⁻¹ np resonances.     

Analysis of the 5d 3-5d 26p transitions in a Hg X ion

Optics and Spectroscopy - Results are presented of an experimental and theoretical analysis of the spectrum of the Hg X ion in the far VUV spectral range. The spectra were excited in the plasma of...     

Characteristic of a negative corona discharge in active media of Xe(6p−5d) and eximer lasers

The article contains results of a study of electric and optical characteristics of a negative corona discharge in a “needles-grid” electrode system in the mixtures He/Xe and He/Xe(Kr)/HCl, which are used in periodic pulsed electric-discharge Xe(6p−5d), XeCl, and KrCl lasers. The corona discharge was ignited in a multielectrode system whose length is commensurable with the length of the active medium of the lasers. Voltage-current characteristics, radiation spectra of the discharge plasma, and the dependences of the radiation intensity of atomic spectral lines and the band λ=308 nm of XeCl (B-X) on parameters of the corona discharge are studied. For the mixture He/Xe the corona discharge exists as a spatially homogeneous discharge that is intermediate between corona and glow discharges and is transformed into an anode streamer at higher charge voltages. Collisional purification of the 6p states of the Xe atom by helium was observed. In the mixture He/Xe/HCl the corona discharge is ignited in the form of individual generation zones and a dark external region and can be used in electric systems for pumping the active media of XeCl and KrCl lasers. Uzhgorod State University, 46, Pidgirna St., Uzhgorod, 294000, Ukraine. Translated from Zhurnal Prikladnoi Spektroskopii, Vol. 65, No. 2, pp. 205–210, March–April, 1998.     

Two-color cesium magneto-optical trap with 6S_(1/2)-6P_(3/2)-7S_(1/2)(852 nm + 1470 nm) ladder-type system

A 1470 nm+ 852 nm two-color(TC) cesium(Cs) magneto-optical trap(MOT) with a 6S_(1/2)-6P_(3/2)-7S_(1/2) laddertype system is proposed and experimentally investigated. To the best of our knowledge, it is the first report about the 1470 nm + 852 nm Cs TC-MOT. One of the three pairs of the 852 nm cooling and trapping beams(CTBs) in a conventional Cs MOT is replaced with a pair of the 1470 nm CTBs. Thus, the TC-MOT partially employs the optical radiation forces from photon scattering of the 6P_(3∕2)(F'= 5)-7S_(1∕2)(F'= 4) excited-state transition(1470 nm). This TC-MOT can cool and trap Cs atoms on both the red-and blue-detuning sides of the twophoton resonance. This work may have applications in cooling and trapping of atoms using inconvenient wavelengths and background-free detection of cold and trapped Cs atoms.     

超高泵浦功率下的Xe(6p[1/2]0, 6p[3/2]2, 和6p[5/2]2)原子的能量转移过程

本文研究了Xe(6p[1/2]₀, 6p[3/2]₂, and 6p[5/2]₂)原子在聚焦条件下的动力学过程. 激发能级的原子密度在聚焦条件下会显著地增加,因此两个高激发态原子之间的energy-pooling碰撞的概率也会增加. 这种energy-pooling碰撞主要有三种类型. 第一种类型为energy-pooling碰撞导致的电离. 一旦将激发激光聚焦,就可以从侧面的窗口观察到非常明显的电离现象,不论激发能级是6p[1/2]₀、6p[3/2]₂或6p[5/2]₂能级. 这种电离的产生机理是energy-pooling电离或者一个Xe^*原子再吸收一个光子产生电离. 第二种类型为跨越较大能极差的energy-pooling碰撞. 当激发能级为6p[1/2]₀能级的情况下,两个6p[1/2]₀原子碰撞会产生一个5d[3/2]₁原子和一个6s''[1/2]₀原子. 第三种类型为跨越较小能级差的energy-pooling碰撞. 以5个二次产生的6p能级为上能级的荧光强度都变得更强,并且这些荧光的上升沿都变得更陡峭. 产生这些6p原子的主要机理是energy-pooling碰撞并非简单的碰撞弛豫. 基于理想气体原子之间的碰撞概率公式,推导出两个6p[1/2]₀原子的energy-pooling碰撞速率为6.39x10⁸s^-1. 此外,6s原子在聚焦条件下的密度也会增加. 因此所有的荧光曲线会因为辐射俘获效应而出现非常严重的拖尾.     

类镓等电子序列ZrX—RhXV离子的4s^24p—4s^24d,4s^24p—4s4p^2,4s^24 …

本文对类镓等电子序列ＧａＩ－ＸｅＸＸＩＶ离子４ｓ＾２４ｐ、４ｓ＾２４ｐ、４ｓ＾２４ｄ、４ｓ４ｐ＾２、４ｐ＾３和４ｓ＾２５ｓ组态组级结果和组态相互作用了理论分析，找出沿等电子序列的变化规律。