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1.
T. Prosen D. L. Shepelyansky 《The European Physical Journal B - Condensed Matter and Complex Systems》2005,46(4):515-518
We establish analogy between a microwave ionization of Rydberg
atoms and a charge transport through a chaotic quantum dot
induced by a monochromatic field in a regime with a potential
barrier between dot contacts.
We show that the quantum coherence leads to dynamical localization
of electron excitation in energy
so that only a finite number of photons is absorbed inside the dot.
The theory developed determines the dependence of localization length
on dot and microwave parameters showing that the microwave power
can switch the dot between metallic and insulating regimes.
ultiphoton ionization and excitation to highly excited states
(e.g., Rydberg states) 相似文献
2.
Above threshold ionization of two structurally different systems is presented namely a rare gas such as argon and the more complex C60 fullerene. We show that the ionization dynamics is different and is dominated by the presence of high-lying Rydberg states in Ar and low-lying bound states in C60. The study is based on a theoretical (solving the time dependent Schrödinger equation) and/or experimental (using measurements from a photoelectron imaging spectrometer) aspect.Received: 20 December 2002, Published online: 24 April 2003PACS:
33.80.Rv Multiphoton ionization and excitation to highly excited states (e.g., Rydberg states) - 32.80.Fb Photoionization of atoms and ions - 36.40.-c Atomic and molecular clusters - 33.60.-q Photoelectron spectra - 61.48.+c Fullerenes and fullerene-related materials 相似文献
3.
利用三步双色共振激发技术和三步三色孤立实激发技术,系统地研究了铕原子在42250—44510 cm~(-1)能域内的光谱特性,提供了该能域内56个束缚高激发态的光谱信息.为了能确定这些态的光谱归属,进行了两方面的探索:第一,观察能否利用孤立实激发技术,把处于这些态上的铕原子进一步共振激发到自电离态,从而推断这些态属于单电子激发的束缚Rydberg态还是属于双电子激发的价态,并对Rydberg态的电子组态进行了光谱确认;第二,通过计算这些态相对于各个电离阈的量子亏损并观察它们分别收敛于哪个电离阈,以便获取其主量子数的信息.最后,设计并采用了三种不同的激发路径,分别将原子布居到同一高激发能域并探测它们在该能域的光电离光谱.通过比较这些光谱的异同并结合上述激发路径所对应的跃迁选择定则,便可惟一地确定这些高激发态的总角动量.研究发现:所探测到的高激发束缚态只有三个属于单电子激发的束缚Rydberg态,其余都是价态.本文确定了这三个Rydberg态的电子组态和原子状态. 相似文献
4.
用可调谐激光两步激发Na原子高激发发里德堡态布居,在光激发后施加脉冲电场测量激发态的场电离阈,利用阈值电场和延迟场电离方法测定了ns(n=20~24)和nd(n=19~23)态的寿命值,并与计算值进行了比较,对影响寿命的因素作了讨论。 相似文献
5.
Photoelectron angular distribution (PAD) of atoms irradiated by a train of identical, circularly polarized few-cycle laser pulses is studied in the frame of a nonperturbative scattering theory. Our study shows that the PADs vary with the kinetic energy of photoelectron, the carrier-envelope phase, and the pulse duration. We find that along with increasing of the kinetic energy of photoelectron or with decreasing of the pulse duration or the both, the original one maximum of PAD splits into two maxima; the newly produced two maxima evolve to the opposite pole of the symmetric axis, and finally incorporate as a new maximum located in the symmetric axis.Received: 26 February 2004, Published online: 10 August 2004PACS:
32.80.Rm Multiphoton ionization and excitation to highly excited states (e.g., Rydberg states) - 42.50.Hz Strong-field excitation of optical transitions in quantum systems; multiphoton processes; dynamic Stark shift - 42.65.Re Ultrafast processes; optical pulse generation and pulse compression 相似文献
6.
We study two-photon double ionization of helium in its ground state at sufficiently low laser intensities so that three and more photon absorptions are negligible. In the regime where sequential ionization dominates, the two-photon double ionization one-electron energy spectrum exhibits a well defined double peak structure directly related to the electron-electron correlation in the ground state. We demonstrate that when helium is exposed to subfemtosecond or attosecond pulses, both peaks move and their displacement is a signature of the time needed by the He+ orbital to relax after the ejection of the first electron. This result rests on the numerical solution of the corresponding non-relativistic time-dependent Schrödinger equation.Received: 17 January 2003, Published online: 18 March 2003PACS:
32.80.Rm Multiphoton ionization and excitation to highly excited states (e.g., Rydberg states) - 32.80.Dz Autoionization 相似文献
7.
Resonance ionization mass spectrometry (RIMS) has proven to be a powerful method for isotope selective ultra-trace analysis of long-lived radioisotopes. For plutonium detection limits of
to
atoms have been achieved for various types of samples. So far a three-step, three-color laser excitation scheme was applied for efficient ionization. In this work, a two-photon transition from an excited state into a high-lying autoionizing state, will be presented, yielding a similar overall efficiency as the three-step, three-color ionization scheme. In this way, only two tunable lasers are needed, while the advantages of a three-step, three-color excitation (high selectivity, good efficiency and low non-resonant background) are preserved. The two-photon transition has been characterized with respect to saturation behavior and line width. The three-step, two-color ionization is a possibility for an improved RIMS procedure.Received: 6 January 2004, Published online: 24 February 2004PACS:
82.80.Ms Mass spectrometry (including SIMS, multiphoton ionization and resonance ionization mass spectrometry, MALDI) - 32.80.Rm Multiphoton ionization and excitation to highly excited states (e.g., Rydberg states) - 32.80.Dz Autoionization 相似文献
8.
We present calculated results for the optimization highly-charged fragment ion formation in the Coulomb explosion of I2 in an intense laser field. Calculations are performed using a simple genetic algorithm and a classical model for the Coulomb explosion process. We find that at low intensity the production of highly-charged fragment ions is optimized by a Fourier-limited pulse, whereas at higher intensity the Coulomb explosion is optimized by a sequence of pulses, with a time-separation determined by enhanced ionization at the critical internuclear distance. Our calculations provide insight into the sensitivity of adaptive pulse shaping experiments to the parameters and evolutionary approaches used.Received: 6 January 2003, Published online: 15 July 2003PACS:
33.80.Rv Multiphoton ionization and excitation to highly excited states (e.g., Rydberg states) - 82.53.Eb Pump probe studies of photodissociation - 02.60.Pn Numerical optimization 相似文献
9.
10.
A new technique is described which allows Doppler-free, isotope-selective excitation of atoms by continuous wave laser radiation and continuous ionization of the atoms by an electric field. The atoms are excited to high Rydberg states in an electric-field-free region of a collimated atomic beam. Because the lifetimes of Rydberg atoms are long they can reach a spatially separated region of the atomic beam where they are ionized by a continuous electric field with a probability of unity. In the case of lithium we obtained a 103 times larger ion signal by field ionization of Rydberg atoms than by direct photoionization from low excited states. 相似文献
11.
Aoto T Ito K Hikosaka Y Shigemasa E Penent F Lablanquie P 《Physical review letters》2006,97(24):243401
Properties of the interatomic Coulombic decay (ICD) process in Ne dimers have been obtained by tracking the formation of energetic Ne+ ions. The double photoionization cross section, deduced from the Ne+/Ne+ coincidence signal, is dominated by the ICD process and presents a threshold 280 meV below the atomic Ne+2s(-1) threshold. Rydberg excitation of a 2s electron in the dimer creates molecular Rydberg states whose Sigma and Pi symmetries have been resolved. These excited states decay by a resonant ICD process releasing an energetic Ne+ ion and a neutral excited Ne* fragment. Subsequent autoionization of the Ne* fragment explains a double photoionization threshold below the dimer 2s ionization threshold. 相似文献
12.
A NEW EXPERIMENTAL METHOD IN THE STUDY OF IONIC RYDBERG STATES BY RESONANCE IONIZATION MASS SPECTROSCOPY
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We report a new method for detecting highly excited ions. With a strong constant electric field ionization following the extracting of ions by a pulsed electric field in a time-of-flight mass spectrometer, the direct multi-photon ionization background can be eliminated in laser multi-step resonance ionization mass spectroscopy of ionic Rydberg states. A high detection efficiency call be obtained for law members of ionic Rydberg states by use of this method. We have applied the method in the study of the spectroscopy of ionic Rydberg states ia ytterbium. 相似文献
13.
P. V. Kashtanov M. I. Myasnikov B. M. Smirnov 《Journal of Experimental and Theoretical Physics》2009,108(1):18-26
The standard classical method of computer simulation is used for evaluation of the inelastic cross section in electron collisions
with a highly excited (Rydberg) atom. In the course of collision, the incident and bound electrons move along classical trajectories
in the Coulomb field of the nucleus, and the scattering parameters are averaged over many initial conditions. The reduced
ionization cross section of a Rydberg atom by electron impact approximately corresponds to that of atoms in the ground states
with valence s-electrons and coincides with the results of the previous Monte Carlo calculations. The cross section of an atom transition
between Rydberg atom states as a result of electron impact is used for finding the stepwise ionization rate constant of atoms
in collisions with electrons or the rate constant of three-body electron-ion recombination in a dense ionized gas because
these processes are determined by kinetics of highly excited atom states. Surprisingly, the low-temperature limit of electron
temperatures is realized when the electron thermal energy is lower than the atom ionization potential by about three orders
of magnitude, as follows from the kinetics of excited atom states.
The article is published in the original. 相似文献
14.
15.
In this work, a three-step autoionization detection method and direct
photoionization detection method are employed to measure the highly
excited even-parity states of the Sm atom in the energy region
between 36360~cm-1 and 40800~cm-1. Comparisons between
the results from the two detection techniques enable us to
discriminate the Rydberg states from the valence states in the same
energy region with the information of level energies, possible J
values and their relative intensities. Furthermore, in the
experiment two different excitation schemes are designed to obtain
the spectra of highly excited even-parity states of the Sm atom.
With a detailed analysis of the experimental data, this work not
only confirms the results about many spectral data from the
literature with different excitation schemes, but also reports new
spectral data on 29 Rydberg states and 23 valence states. 相似文献
16.
The interaction of a 60 fs 790 nm laser pulse with beams of Ar+, C+, H2
+, HD+ and D2
+ are discussed. Intensities up to 1016 Wcm-2 are employed. An experimental z-scanning technique is used to resolve the intensity dependent processes in the confocal volume.Received: 6 January 2003, Published online: 15 July 2003PACS:
32.80.Fb Photoionization of atoms and ions - 33.80.Rv Multiphoton ionization and excitation to highly excited states (e.g., Rydberg states) - 42.50.Hz Strong-field excitation of optical transitions in quantum systems; multiphoton processes; dynamic Stark shift 相似文献
17.
We have observed electron impact ionization of highly excited sodium Rydberg atoms in ns and nd states, n=35-51, below E=2 eV electron kinetic energy with energy resolution 0.25 eV. Measured absolute cross sections near 0 eV range from sigma(35d) approximately 7 x 10(-10) to sigma(50d) approximately 4 x 10(-9) cm(2). The energy dependence is consistent with that of widely used binary encounter approximation cross sections, and sigma(n) follows a power law in n. The measured cross sections are 14 to 24 times larger than theoretically predicted values. This enhancement may signal the effect of large polarizabilities of high Rydberg states not yet accounted for in ionization theories. 相似文献
18.
The threshold electron impact spectrum of molecular oxygen has been studied using a high energy resolution electron spectrometer in the energy region 2-15.2 eV and the penetrating field method for scattered electrons. The measured features such as core excited resonances as well as Rydberg and valence states are measured in threshold and metastable spectra. They are identified and assigned according to their energy positions, energy spacing between vibrational levels and compared with similar data from the literature. A good agreement was found in the energy positions between measured features and corresponding potential energy diagram for Rydberg states for molecular oxygen given by Morrill et al. [1].Received: 13 January 2004, Published online: 20 April 2004PACS:
34.80.Gs Molecular excitation and ionization by electron impact 相似文献
19.
Accurate and efficient grid based techniques for the solution of the time-dependent Schrödinger equation for few-electron diatomic molecules irradiated by intense, ultrashort laser pulses are described. These are based on hybrid finite-difference, Lagrange mesh techniques. The methods are applied in three scenarios, namely H2
+ with fixed internuclear separation, H2
+ with vibrating nuclei and H2 with fixed internuclear separation and illustrative results presented.Received: 19 November 2002, Published online: 24 April 2003PACS:
02.60.Cb Numerical simulation; solution of equations - 02.70.Bf Finite-difference methods - 33.80.Rv Multiphoton ionization and excitation to highly excited states (e.g., Rydberg states) - 33.80.-b Photon interactions with molecules 相似文献
20.
钠分子^1Пg里德堡态光谱研究 总被引:1,自引:1,他引:0
通过光学-光学以共振(OODR)光谱方法,研究了钠分子六个高激发^1Пg态,对它们进行了振动和转动归属,获得了分子常数和势能曲线。根据里德堡轨道的nlλ特性,将1-10^1Пg态划分为实贯穿里德堡态和实非贯穿里堡态。 相似文献