共查询到20条相似文献,搜索用时 0 毫秒
1.
E. J. Prime J. Lassen T. Achtzehn D. Albers P. Bricault T. Cocolios M. Dombsky F. Labrecque J. P. Lavoie M. R. Pearson T. Stubbe N. Lecesne Ch. Geppert K. D. A. Wendt 《Hyperfine Interactions》2006,171(1-3):127-134
The range of isotopes available at the TRIUMF Isotope Separator Accelerator (ISAC) facility has been greatly enhanced by adding
a Resonance Ionization Laser Ion Source (RILIS). A large wavelength range is accessible with the fundamental, second and third
harmonic generation of titanium-sapphire laser light. In addition a dedicated laser is available for non-resonant laser ionization.
The first on-line beam 62Ga was delivered in Dec. 2004. In general RILIS improves the intensity, purity and emittance of ion beams. 62Ga and 26Al and Be beams have been delivered so far on-line.
This work was financed by TRIUMF which is federally funded via a contribution agreement through the National Research Council
of Canada. 相似文献
2.
3.
It is important to optimize the resonance ionization efficiency of the sputtered particle by evaluating the internal energy of it. And also the dependence of the change of the internal energy of it on primary ion species and accelerating voltages was investigated. For this study, we developed proto-type resonance laser ionization SNMS instrument, which is a quadrupole SIMS apparatus combined with a wavelength tunable laser. The internal energy of the sputtered aluminum atoms, which has lowly lying excited state (112 cm−1) on the ground state, was monitored. As the results, the internal energy of the sputtered aluminum atoms was not influenced by the change of the surface work function and primary ion beam energy at all. On the contrary, the density on lowly lying excited state drastically increased due to the existence of the oxygen on aluminum surface. 相似文献
4.
Xe-Kr laser induced collisional ionization system and experimental preparation of its initial state: Four-photon resonant excitation 下载免费PDF全文
This paper proposes a novel one-colour Xe-Kr laser induced collisional ionization system. Considering the level scheme of the system, it finds that the initial state of the reaction--the four 4f levels with even J of Xe-can be prepared through method of four-photon resonant excitation by dye laser with wavelength of -440 nm. Absorption of an additional photon (the transfer laser) of the same wavelength will complete the laser induced collisional ionization process. The resonance enhanced ionization spectrum of Xe by four laser photons at -440nm is measured through time-of-flight mass spectrometry, this aims at the preparation of the initial state of the system proposed. The Stark broadening of the measured spectrum is observed and consistent with the previous study. Analysis of the measured resonance ionization spectrum implies the feasibility of -440 nm four-photon resonant excitation of the initial 4f state of the Xe Kr system proposed in this paper, which prepares for a further experiment of laser induced collisional ionization. 相似文献
5.
K. Wies C. Geppert K. Blaum K. Brück H.-J. Kluge S. Schwarz K. Wendt 《Hyperfine Interactions》2005,162(1-4):29-38
A new type of resonance ionization laser ion source (RILIS) is presently being developed and tested at the off-line mass separator
at Mainz University for future use at on-line exotic rare isotopes production facilities. For highest isobaric selectivity,
this RILIS approach decouples the evaporation and ionization process. A further advantage is the generation of full temporal
control of the resulting high quality ion beam. These facts are realized by a combination of atomizer – ion repeller – ion
cooler and trap, which is operated together with a state-of-the-art, all solid state laser system. The principle and performance
of this laser ion source trap (LIST) system are discussed applying simulation studies for the repeller-trap combination and
first measurements for characterization. 相似文献
6.
使用100飞秒、1014 W/cm2的强激光与惰性气体Ar原子相互作用,我们利用飞行时间质谱仪结合Z扫描技术获得了各次电离的Ar原子在激光焦点附近不同位置处强度分布.测量得到的各个不同电离态Ar n+(n=1~4)的产额随激光焦点位置变化关系与不同电离态的空间分布理论预言相一致. 相似文献
7.
We study the ionization probabilities of atoms by a short laser pulse with three different theoretical methods,i.e.,the numerical solution of the time-dependent Schro¨dinger equation(TDSE),the Perelomov-Popov-Terent’ev(PPT) theory,and the Ammosov-Delone-Krainov(ADK) theory.Our results show that laser intensity dependent ionization probabilities of several atoms(i.e.,H,He,and Ne) obtained from the PPT theory accord quite well with the TDSE results both in the multiphoton and tunneling ionization regimes,while the ADK results fit well to the TDSE data only in the tunneling ionization regime.Our calculations also show that laser intensity dependent ionization probabilities of a H atom at three different laser wavelengths of 600 nm,800 nm,and 1200 nm obtained from the PPT theory are also in good agreement with those from the TDSE,while the ADK theory fails to give the wavelength dependence of ionization probability.Only when the laser wavelength is long enough,will the results of ADK be close to those of TDSE. 相似文献
8.
本文采用共振激光烧蚀技术研究了钛和铝样品中铁元素的激光共振电离谱,讨论了元素的含量与共振电离谱线强度的关系及基体效应的影响. 相似文献
9.
At the ISOLDE on-line isotope separation facility, the resonance ionisation laser ion source (RILIS) can be used to ionise
reaction products as they effuse from the target. The RILIS process of laser step-wise resonance ionisation of atoms in a
hot metal cavity provides a highly element selective stage in the preparation of the radioactive ion beam. As a result, the
ISOLDE mass separators can provide beams of a chosen isotope with greatly reduced isobaric contamination. With the addition
of a new three-step ionisation scheme for gold, the RILIS is now capable of ionising 26 of the elements. The optimal scheme
was determined during an extensive study of the atomic energy levels and auto-ionising states of gold, carried out by means
of in-source resonance ionisation spectroscopy. Details of the ionisation scheme and a summary of the spectroscopy study are
presented. 相似文献
10.
T. Achtzehn J. Lassen P. Bricault D. Albers T. E. Cocolios M. Dombsky V. Hanemaayer J. P. Lavoie N. Lecesne M. R. Pearson E. J. Prime K. D. A. Wendt 《Hyperfine Interactions》2007,174(1-3):27-32
Many experiments carried out at radioactive beam facilities require the production of intense, isotopically clean and isobar
free beams of a particular isotope. At TRIUMF the addition of a resonant ionization laser ion source (TRILIS) enables a multitude
of new beams and therefore new experiments to be carried out. 26Al was one of the first radioactive ion beams delivered to an experiment using TRILIS. This paper outlines the development
of the 26Al ion beam for nuclear astrophysics.
相似文献
11.
12.
利用飞行时间质谱仪,研究了功率密度为109~1011 W/cm2,波长为532 nm 的纳秒激光对苯、呋喃、甲醇及碘甲烷分子团簇的激光电离过程。实验观察到了高平动能的高价离子Cq+(q≤3),Oq+(q≤3)和Iq+(q≤4),该过程经历了以“初始的多光子电离引发-逆轫致吸收加热-电子碰撞电离模式”为主的激光团簇作用过程,后期经历了团簇的库仑爆炸过程。实验发现:即使激光能量变化一个量级以上时,主要高价离子的种类及占全部离子产物的比率也没有明显的变化,但是高价离子的初始平动能随激光强度的增大而增加;分子中含有较多个外壳层电子的氧、碘原子更容易电离产生高价离子,而碳离子的价态和强度相对较低。 相似文献
13.
利用带离化子程序的一维粒子模拟程序,对光脉冲与离化波前的相互作用进行了模拟研究,讨论了在原子多度电离的情况下光脉冲与离化波前的相互作用关系.研究表明,由于原子各级离化势的不连续性使得离化波前在空间上出现平台区;离化过程导致激光频率发生蓝移,这个蓝移又对脉冲形状产生调制,使脉冲前沿呈阶跃型增长;阶跃型的光脉冲包络使离化波前的平台区变短,直至整个离化波前分为几个不同梯度的区域.还讨论了不同元素和不同密度的气体中产生的离化波前的特点.同时分析了光脉冲频率随传播距离的关系,指出由于光脉冲宽度的增加,将导致出射的光
关键词:
激光等离子体
光电离
离化波前
激光频率上转换 相似文献
14.
采用三维粒子动力学模拟方法研究了甲烷团簇在超短强激光脉冲激励下的爆炸动力学行为,重点讨论了几种典型的内电离机理对团簇爆炸过程中离子的价态和动能的影响.研究表明,在激光脉冲强度比较小的情况下,团簇中的原子主要是在光场作用下通过隧道电离的方式发生电离.当激光场进一步增强时,势垒压低电离是电离的主要方式.在相同的较高激光强度下,团簇更容易通过势垒压低电离达到高的电离价态.团簇发生电离后,其内部库仑电场的点火电离效应和内部滞留自由电子的碰撞电离效应也将增强团簇的再次电离过程.
关键词:
超短强激光脉冲
甲烷团簇
内电离 相似文献
15.
The Coulomb effect on a low-energy structure in above-threshold ionization spectra induced by mid-infrared laser pulses 下载免费PDF全文
We investigate the low-energy structure(LES)in the above-threshold ionization spectrum at a mid-infrared laser wavelength with a semiclassical model.Using a softened Coulomb potential(CP)and changing the softening parameter,we show that though the very low-energy structure(VLES)and high low-energy structure(HLES)are both due to the interaction between the ionic CP and the electron,the two structures have different physical mechanisms:the VLES can be attributed to the electron–ion Coulomb interaction at a rather small distance and the HLES is more likely to be ascribed to the electron–ion Coulomb interaction at a large distance. 相似文献
16.
17.
18.
利用脉宽为25ns的脉冲Nd: YAG 532 nm的激光,在8×1010W/cm2的强度下,用飞行时间质谱对CS2的激光电离过程进行了研究.观察到了较强的C2+和S2+高价离子信号,这些高价离子C2+,S2+的最可几平动能高达144 eV,112 eV.不同进样方式,激光延迟以及束源压力的实验结果表明,这些高价离子可能来源于CS2团簇的库仑爆炸过程.多光子电离引发,逆韧致吸收加热-电子碰撞电离模型可能是高价离子产生的机理.
关键词:
2')" href="#">CS2
团簇
高价离子
激光电离 相似文献
19.
Modulation of ionization on laser frequency in ultra-short pulse intense laser--gas-target 下载免费PDF全文
Based on the dispersion relation of intense laser pulse propagating in gradually
ionized plasma, this paper discusses the frequency modulation induced by ionization
of an ultra-short intense laser pulse interacting with a gas target. The
relationship between the frequency modulation and the ionization rate, the plasmas
frequency variation, and the polarization of atoms (ions) is analysed. The numerical
results indicate that, at high frequency, the polarization of atoms (ions) plays a
more important role than plasma frequency variation in modulating the laser
frequency, and the laser frequency variation is different at different positions of
the laser pulse. 相似文献
20.
Electron correlations in nonsequential double ionization of argon atoms by elliptically polarized laser pulses 下载免费PDF全文
Using a classical ensemble model, we investigate the correlation behaviour of electrons originating from nonsequential double ionization (NSDI) of argon atoms by the elliptically polarized laser pulses. Because of the ellipticity, not only the first electron to return but also the later return of tunneled electrons contribute significantly to NSDI. We mainly discuss two kinds of events of NSDI originating from the first and the second return separately. For the NSDI resulting from the recollision of the first return, the correlated electron momentum spectrum along the long axis of the laser polarization plane reveals an obvious V-like shape, located at the first and third quadrant. However, for the NSDI resulting from the recollision of the second return, the momenta of two electrons are distributed in the four quadrants uniformly. By analysing the trajectories of these two kinds, we find that the recollision energy and the laser phase at recollision are different for the first and second returning trajectories, which are responsible for the difference in the correlated behavior of the final electron momentum. 相似文献