共查询到20条相似文献,搜索用时 31 毫秒
1.
YANG Zhi-Hu XIAO Guo-Qing CHEN Xi-Meng ZHANG Yan-Ping ZHAO Yong-Tao ZHANG Xiao-An SU Hong CUI Yin ZHANG Hong-Qiang XU Xu SHAO Jian-Xiong 《中国物理C(英文版)》2004,28(11):1231-1233
The X-ray emission from the highly charged Ar17+ ion interacting with Mo surface are measured on the 14.5GHz Electron Cyclotron Resonance ion source facility at Institute of Modern, the Chinese Academy of Sciences in Lanzhou. Ar17+ ions came from Electron Cyclotron Resonance ion source and impacted on Mo surface.The incident ion with vacancy of inner shell captures electrons emitted from surface into highly excited Rydberg states, outer shell electron cascades into K vacancy giving rise to Kα X-ray emission of the incidentionsions. 相似文献
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We report the creation of an interacting cold Rydberg gas of strontium atoms. We show that the excitation spectrum of the inner valence electron is sensitive to the interactions in the Rydberg gas, even though they are mediated by the outer Rydberg electron. By studying the evolution of this spectrum we observe density-dependent population transfer to a state of higher angular momentum l. We determine the fraction of Rydberg atoms transferred, and identify the dominant transfer mechanism to be l-changing electron-Rydberg collisions associated with the formation of a cold plasma. 相似文献
4.
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
5.
A study is made of the Rydberg levels in CH2 and CH3 which are associated with the outer electron in a carbon 3d-orbital. A preliminary discussion of some Rydberg states in the lithium atom showed that penetration and exchange effects between the Rydberg orbital and the core were of comparable magnitude, and strongly dependent on the correct form of the Rydberg orbital wave function in the region where this overlaps the core. In the cases of CH3 and CH2 some conclusions of G. Herzberg about the symmetry of excited states where a 3d-orbital is involved have been confirmed, and certain other ionization potentials estimated. In CH2 spin-orbit forces were included, but comparison with experiment is limited. The need to orthogonalize the Rydberg orbital to any core orbitals of similar overall symmetry, and to allow mixing with other orbitals (e.g. carbon 3s with carbon 3d0) is stressed. One of the chief causes of error at present is our ignorance about the degree of validity of Koopman's theorem for situations of this kind. It is important to know to what extent the core changes its charge distribution after the ejection of the Rydberg electron. 相似文献
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A number of processes in which highly excited states of atoms and molecules participate are investigated. These processes are of interest for the kinetics of a low-temperature plasma, for atomic and molecular spectroscopy, and for astrophysics. A quasiclassical theory is developed for transitions between Rydberg states with change of the principal quantum number, and also for the processes of direct and associative ionization of highly excited atoms, which result from collisions between a neutral particle and its atomic core. The state of the inner electrons of a quasimolecular (molecular) ion is not altered by transitions of the outer electrons. Specific calculations are carried out for the case of the collision of hydrogen H(n) with helium He (1s2) atoms. It is shown that the cross sections and the rate constants of these processes are determined in this case by the mechanism investigated in the paper, and not by scattering of the Rydberg electron by the neutral particle. The cross sections for dipole excitation and dissociation of molecular ions from high vibrational energy levels by electron impact is calculated in the Born-Coulomb approximation. The cross sections and the rates of dissociative and three-particle attachment of electrons to ions are determined. The processes of autoionization and autodissociation decay of Rydberg states of vibrationally excited molecules are determined. Also investigated are radiative transitions near the dissociation limit of diatomic molecular ions and neutral molecules, viz., photodissociation and radiative decay of high vibrational levels, and photodissociation and translational (inverse-bremsstrahlung) absorption in collision of atomic particles.Translated from Trudy Ordena Lenina Fizicheskogo Instituta im. P. Lebedeva AN SSSR, Vol. 145, pp. 80–130, 1984. 相似文献
7.
Nuclear dissociation after the O 1s $\rightarrow (^4\Sigma_\text{u}^-)$3sσ excitation in O$_2$ molecules
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Bocheng Ding 《中国物理 B》2022,31(8):83301-083301
We investigate the dissociation dynamics of core-excited $\mathrm{O}_2$ molecules using a high-resolution energy-resolved electron-ion coincidence experimental setup. The excited cationic states with two valence holes and one Rydberg electron are created after spectator Auger decay induced by $\mathrm{O}$ 1s $\rightarrow (^4\Sigma_{\rm u}^-)3{\rm s}\sigma$ core excitation in $\mathrm{O}_2$. From the energy correlation between the kinetic energy of the Auger electron and the ion kinetic energy release, we distinguish several dissociation channels. Rather complex dissociation channels of the spectator Auger final states are disclosed, which can be explained by the increased number of the crossing point due to the existence of Rydberg electron. The quantum system will evolve into different dissociation limits at each crossing point between the potential energy curves. 相似文献
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Farooqi SM Tong D Krishnan S Stanojevic J Zhang YP Ensher JR Estrin AS Boisseau C Côté R Eyler EE Gould PL 《Physical review letters》2003,91(18):183002
We present evidence for molecular resonances in a cold dense gas of rubidium Rydberg atoms. Single UV photon excitation from the 5s ground state to np Rydberg states (n=50-90) reveals resonances at energies corresponding to excited atom pairs (n-1)d+ns. We attribute these normally forbidden transitions to avoided crossings between the long-range molecular potentials of two Rydberg atoms. These strong van der Waals interactions result in avoided crossings at extremely long range, e.g., approximately 58 000 times the Bohr radius (a(0)) for n=70. 相似文献
9.
The electron and nuclear dynamics of C60 fullerenes
irradiated with femtosecond laser pulses are investigated with
photoelectron and photoion spectroscopy. The focus of this work is
the detailed exploration of the population mechanism of Rydberg
levels within the excitation process of neutral C60. The effect
of excitation wavelength, intensity, chirp, and polarization on the
kinetic energy distribution of photoelectrons in single-pulse
experiments gives first insight into the underlying processes. In
combination with time-resolved two-color pump-probe spectroscopy
depending on either pump, or probe pulse intensity, a more complete
picture of the interaction can be drawn. The results point towards a
very interesting but nevertheless complex behavior including four
steps: (i) non-adiabatic multielectron excitation of the HOMO
(hu) → LUMO+1 (t1g) transition; (ii)
thermalization within the hot electron cloud on a time scale below
100 fs, followed by a coupling of energy to vibrational modes of
the molecule via doorway state(s); (iii) population of
electronically excited Rydberg states by multiphoton absorption, and
(iv) single photon ionization from the excited Rydberg states. This
excitation process results in a characteristic sequence of
photoelectron lines in the photoemission spectra. The comparison of
the experimental results with recent theoretical work gives
convincing evidence that non-adiabatic multielectron dynamics (NMED)
plays a key role for the understanding of the response of C60
to short-pulse laser radiation. 相似文献
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Lambourne JG Penent F Lablanquie P Hall RI Ahmad M Zitnik M Bucar K Odling-Smee MK Harries JR Hammond P Waterhouse DK Stranges S Richter R Alagia M Coreno M Ferianis M 《Physical review letters》2003,90(15):153004
Two recent theoretical studies [C. Liu, Phys. Rev. A 64, 010501 (2001)]; M. Zitnik, ibid. 65, 032520 (2002)]] predict that the fluorescence lifetimes of helium doubly excited states converging to He+ N=2 should be longer than that of the He+ 2p ion state. This effect is caused by the electric field of the outer electron which, through Stark mixing, gives the inner fluorescing electron some series specific, stabilizing 2s character. We have obtained the first experimental evidence that confirms this effect by measuring the lifetime of the 2p3d(1P0) doubly excited state. This was determined to be 190+/-30 ps compared to 100 ps for the He+ 2p ion state. The measurements were performed using short pulses of synchrotron radiation to form doubly excited states and recording the arrival time of photons from fluorescence. 相似文献
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The observation of a new class of long-lived outer well states of ungerade symmetry (B"B1Sigma+u) in molecular hydrogen, lying above the ionization threshold, is reported. Rovibrational levels within a potential extended over internuclear separations of R = 7-25 a.u. are experimentally investigated in a triple resonance scheme. Good agreement ( <0.5 cm(-1)) with updated ab initio calculations is found for vibrational levels up to v = 26, demonstrating that such calculations can now be extended to this energetic range above ionization, as long as interaction with the Rydberg manifolds is shielded by a barrier. The dynamical behavior (predissociation and autoionization) of this class of " u" symmetry states is remarkably different from similar outer well states of " g" symmetry; this phenomenon can be understood from the structure of doubly excited electronic states. 相似文献
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Dutta SK Feldbaum D Walz-Flannigan A Guest JR Raithel G 《Physical review letters》2001,86(18):3993-3996
Cold, dense Rydberg gases produced in a cold-atom trap are investigated using spectroscopic methods and time-resolved electron counting. Optical excitation on the discrete Rydberg resonances reveals long-lasting electron emission from the Rydberg gas ( >20 ms). Our observations are explained by lm-mixing collisions between Rydberg atoms and slow electrons that lead to the population of long-lived high-angular-momentum Rydberg states. These atoms thermally ionize slowly and with large probabilities. 相似文献
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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
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Our (e,3-1e) measurements for studying the post-collision interaction (PCI) after electron impact inner shell ionization of argon were continued and completed at different energy conditions. Emitted LMM Auger electrons are detected in coincidence with the ionizing scattered electrons and the energy of the slow PCI inducer ejected electron was calculated from energy conservation. Particularly the effect of the very low energy (i.e. 0–5 eV) ejected electrons (strongly asymmetric energy sharing) is studied at 500 and 460 eV primary electron energies. In the latter case, the background caused by outer-shell electrons was measured by itself and then removed from the coincident spectrum. Nevertheless, the evaluation of PCI distorted Auger lines is still considerably disturbed by the resonant Auger electrons from the high Rydberg states, their (e,2e) contribution was estimated in the paper. 相似文献
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U. Reus W. Westmeier R. A. Esterlund A. Rox M. Rajagopalan P. Patzelt 《Zeitschrift für Physik A Hadrons and Nuclei》1981,302(4):363-364
The pronounced isotope shift of87Sr versus87Sr observed recently in 5sns1S0 Rydberg states reflects the singlet-triplet mixing solely caused by magnetic hyperfine interaction. Using semiempirical estimates for the hyperfine coupling constant a5 s and the singlet-triplet splitting ΔEST (n) excellent agreement between experimental and calculated values is obtained. 相似文献
18.
J. E. Palmer 《Molecular physics》2019,117(21):3108-3119
Matter-wave interferometry has been performed with helium atoms in high Rydberg states. In the experiments the atoms were prepared in coherent superpositions of Rydberg states with different electric dipole moments. Upon the application of an inhomogeneous electric field, the different forces on these internal state components resulted in the generation of coherent superpositions of momentum states. Using a sequence of microwave and electric field gradient pulses the internal Rydberg states were entangled with the momentum states associated with the external motion of these matter waves. Under these conditions matter-wave interference was observed by monitoring the populations of the Rydberg states as the magnitudes and durations of the pulsed electric field gradients were adjusted. The results of the experiments have been compared to, and are in excellent quantitative agreement with, matter-wave interference patterns calculated for the corresponding pulse sequences. For the Rydberg states used, the spatial extent of the Rydberg electron wavefunction was ~320?nm. Matter-wave interferometry with such giant atoms is of interest in the exploration of the boundary between quantum and classical mechanics. The results presented also open new possibilities for measurements of the acceleration of Rydberg positronium or antihydrogen atoms in the Earth's gravitational field. 相似文献
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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
20.
J.-P. Connerade S. D. Hogan H.-P. Liu M.-S. Zhan 《The European Physical Journal D - Atomic, Molecular, Optical and Plasma Physics》2008,46(3):431-435
The current controversy over the need for an
experimental test of String Theory is considered. We report recent
experiments on quasi-bound electrons in crossed electric and
magnetic fields, in which states of very large electric dipole
moment are excited. The excited electron is confined to one side
of the atomic nucleus in the outer well of a controllable
double-well potential. These states are discussed in relation to a
recent theoretical proposal to test the spatial non-commutativity
underpinning String Theory by studying Penning orbits of Rydberg
atoms in crossed electric and magnetic fields. 相似文献