Semiclassical calculation of ionisation rate for Rydberg helium atoms in an electric field

2011 ◽  
Vol 20 (1) ◽  
pp. 013403 ◽  
Author(s):  
De-Hua Wang
Keyword(s):  
Electric Field ◽  
Helium Atoms ◽  
Ionisation Rate

scholarly journals Classical Dynamics of Rydberg States of Muonic-Electronic Helium and Helium-Like Ions in a Weak Electric Field: Counter-Intuitive Linear Stark Effect

Dynamics ◽  
2021 ◽  
Vol 1 (1) ◽  
pp. 1-8
Author(s):  
Eugene Oks
Keyword(s):  
Electric Field ◽  
External Electric Field ◽  
Stark Effect ◽  
Rydberg States ◽  
Critical Value ◽  
Weak Electric Field ◽  
Classical Dynamics ◽  
Static Electric Field ◽  
Hydrogen Atoms ◽  
Helium Atoms

According to the existing paradigm, helium atoms and helium-like ions (hereafter, heliumic systems) in a relatively weak external static electric field do not exhibit the linear Stark effect—in distinction to hydrogen atoms and hydrogen-like ions. In the present paper we consider the classical dynamics of a muonic-electronic heliumic system in Rydberg states–starting from the concept from our previous paper. We show that there are two states of the system where the averaged electric dipole moment is non-zero. Consequently, in these states the heliumic system should exhibit the linear Stark effect even in a vanishingly small electric field, which is a counter-intuitive result. We also demonstrate the possibility of controlling the overall precession of the electronic orbit by an external electric field. In particular, we show the existence of a critical value of the external electric field that would “kill” the precession and make the electronic orbit stationary. This is another counter-intuitive result. We calculate analytically the value of the critical field and show that it is typically smaller or even much smaller than 1 V/cm.

Helium Quench Radiation and Transition Polarizability

1972 ◽  
Vol 50 (17) ◽  
pp. 1896-1902 ◽  
Author(s):  
G. W. F. Drake
Keyword(s):  
Field Strength ◽  
Electric Field ◽  
Oscillator Strength ◽  
Constant Electric Field ◽  
Accurate Calculation ◽  
Quenching Rate ◽  
Transition Dipole ◽  
Helium Atoms ◽  
S States ◽  
Dipole Polarizabilities

An accurate calculation of the quenching rate for metastable singlet helium atoms and helium-like ions in a constant electric field is presented. The theoretical rate for helium is (0.932 ± 0.001)F2 s−1, where F is the field strength in kV/cm, in agreement with the recent experimental value (0.926 ± 0.02)F2 s−1.In addition, several oscillator strength sums are evaluated, along with the static and transition dipole polarizabilities of the 1 1S, 2 1S, and 2 3S states for the helium-like ions up to Ne IX.

Ionization of highly excited helium atoms in an electric field

1984 ◽  
Vol 30 (5) ◽  
pp. 2399-2412 ◽  
Author(s):  
Willem van de Water ◽  
David R. Mariani ◽  
Peter M. Koch
Keyword(s):  
Electric Field ◽  
Helium Atoms ◽  
Excited Helium

scholarly journals The production of radiation and ionization from helium atoms by potassium positive ions

1936 ◽  
Vol 155 (884) ◽  
pp. 123-141 ◽  
Author(s):  
Ann Catherine Davies ◽  
Ernest Rutherford
Keyword(s):  
Alkali Metal ◽  
Electric Field ◽  
Opposite Direction ◽  
Rare Gases ◽  
Neutral Atoms ◽  
Helium Atoms ◽  
Positive Ions ◽  
Order Of Magnitude

The production of ionization and radiation by collision of relatively slow positive ions with neutral atoms constitutes a less completely explored field of investigation than that of the absorption of ions by scattering, neutralization, and retardation. Many of the apparent discrepancies among the earlier results of investigations of the disappearance of ions from a beam on passing through a gas have now been reconciled by an appreciation of the important part played by the geometry of the apparatus, but as regards the production of ionization and radiation by slow positive ions many of the results are still somewhat conflicting. Investigations of this problem are beset with difficulties because of the relative inefficiency of the process and the necessity of eliminating the effects of other processes of a comparable order of magnitude. Experiments on the ionization of the rare gases by alkali metal positive ions, some of which include the ionization of helium by K + ions, have been carried out by Sutton, Mouzon, an d Beeck, and by Frische, and Nordmeyer. The method employed in all these investigations consisted in the measurement of the current due to the electrons produced in the gas by the positive ions, the electrons being driven to the collector by an electric field which urged them in the opposite direction to that in which the beam of positive ions was travelling.

Resolution in photoelectron microscopy

1991 ◽  
Vol 49 ◽  
pp. 458-459
Author(s):  
G. F. Rempfer
Keyword(s):  
Electron Microscopy ◽  
Electric Field ◽  
Ultraviolet Light ◽  
Uniform Field ◽  
Virtual Image ◽  
Lens System ◽  
Photoemission Electron Microscopy ◽  
Planar Electrode ◽  
Electron Lens ◽  
Photoemission Electron

In photoelectron microscopy (PEM), also called photoemission electron microscopy (PEEM), the image is formed by electrons which have been liberated from the specimen by ultraviolet light. The electrons are accelerated by an electric field before being imaged by an electron lens system. The specimen is supported on a planar electrode (or the electrode itself may be the specimen), and the accelerating field is applied between the specimen, which serves as the cathode, and an anode. The accelerating field is essentially uniform except for microfields near the surface of the specimen and a diverging field near the anode aperture. The uniform field forms a virtual image of the specimen (virtual specimen) at unit lateral magnification, approximately twice as far from the anode as is the specimen. The diverging field at the anode aperture in turn forms a virtual image of the virtual specimen at magnification 2/3, at a distance from the anode of 4/3 the specimen distance. This demagnified virtual image is the object for the objective stage of the lens system.

Field-assisted ionization theory for microscopists

1994 ◽  
Vol 52 ◽  
pp. 820-821
Author(s):  
Patrick P. Camus
Keyword(s):  
Electric Field ◽  
Electron Tunneling ◽  
Ionization Probability ◽  
Critical Distance ◽  
Tunneling Probability ◽  
Field Ionization ◽  
Radius Of Curvature ◽  
Field Evaporation ◽  
A Value ◽  
Ion Emission

The theory of field ion emission is the study of electron tunneling probability enhanced by the application of a high electric field. At subnanometer distances and kilovolt potentials, the probability of tunneling of electrons increases markedly. Field ionization of gas atoms produce atomic resolution images of the surface of the specimen, while field evaporation of surface atoms sections the specimen. Details of emission theory may be found in monographs.Field ionization (FI) is the phenomena whereby an electric field assists in the ionization of gas atoms via tunneling. The tunneling probability is a maximum at a critical distance above the surface,xc, Fig. 1. Energy is required to ionize the gas atom at xc, I, but at a value reduced by the appliedelectric field, xcFe, while energy is recovered by placing the electron in the specimen, φ. The highest ionization probability occurs for those regions on the specimen that have the highest local electric field. Those atoms which protrude from the average surfacehave the smallest radius of curvature, the highest field and therefore produce the highest ionizationprobability and brightest spots on the imaging screen, Fig. 2. This technique is called field ion microscopy (FIM).

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