On the classification of the doubly excited states of the two-electron atom

Nikitin, S. I.; Ostrovsky, V N

doi:10.1088/0022-3700/9/18/005

Cited by 43 publications

(22 citation statements)

References 8 publications

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“…Recently we showed that X-dip phenomena are possible in spectral lines of helium-like ions from laser-produced plasmas [24,25]. The reason is the existence of an approximate additional conserved quantity for the corresponding two-center Coulomb system with two bound electrons [26]. This offers a new opportunity to extend the range of fundamental data on charge exchange.…”

Section: The Latest Development On X-dipsmentioning

confidence: 99%

Review of Langmuir-Wave-Caused Dips and Charge-Exchange-Caused Dips in Spectral Lines from Plasmas and their Applications

Dalimier

Oks

Renner

2014

Atoms

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We review studies of two kinds of dips in spectral line profiles emitted by plasmas-dips that have been predicted theoretically and observed experimentally: Langmuir-wave-caused dips (L-dips) and charge-exchange-caused dips (X-dips). There is a principal difference with respect to positions of L-dips and X-dips relative to the unperturbed wavelength of a spectral line: positions of L-dips scale with the electron density N e roughly as N e 1/2 , while positions of X-dips are almost independent of N e (the dependence is much weaker than for L-dips). L-dips and X-dips phenomena are important, both fundamentally and practically. The fundamental importance is due to a rich physics behind each of these phenomena. L-dips are a multi-frequency resonance phenomenon caused by a singlefrequency (monochromatic) electric field. X-dips are due to charge exchange at anticrossings of terms of a diatomic quasi-molecule, whose nuclei have different charges. As for important practical applications, they are as follows: observations of L-dips constitute a very accurate method to measure the electron density in plasmas-a method that does not require knowledge of the electron temperature. L-dips also allow measuring the amplitude of the electric field of Langmuir waves-the only spectroscopic method available for this purpose. Observations of X-dips provide an opportunity to determine rate coefficient of charge exchange between multi-charged ions. This is an important reference data, virtually inaccessible by other experimental methods. The rate coefficients of charge

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Section: The Latest Development On X-dipsmentioning

confidence: 99%

Review of Langmuir-Wave-Caused Dips and Charge-Exchange-Caused Dips in Spectral Lines from Plasmas and their Applications

Dalimier

Oks

Renner

2014

Atoms

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“…Hence, the quantum mathematics and the classical physics were well on their way to becoming understood and moderately accurate, as a result of this work. It should be added that Nikitin and Ostrovsky showed [15] that if the two electrons are in very different orbits (in a classical picture), or have very different principal quantum numbers (in a quantum picture), then, indeed, they hardly influence each other and the model of nearly unperturbed hydrogenic electrons is accurate. However, if the two electrons have the same or similar principle quantum numbers, the two electrons have very strong influence on each other.…”

Section: Symmetries and The Electronic Structures Of Atomsmentioning

confidence: 99%

Symmetry in atomic and molecular systems

Berry

1991

Computers & Mathematics with Applications

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Symmetry is used to define alternative categorizations to which real atomic and molecular systems may correspond. By constructing idealized models to correspond to limiting cases, it becomes possible to decide what are the best approximations and starting points for making mathematlcal representations of the real systems. Tiffs is illustrated with two examples: atoms with two valence electrons, and multidimensional potential surfaces of atomic clusters. In the first example, the question is whether an independent-particle, quantum analogue of a solar system or a collective, rotor-vibrator model is more appropriate, ht the second example, the problem is finding enough about the multidimensional potential to describe the dynamics of the atomic motion, without becoming overwhelmed with irrelevant data.

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“…The thrust of the present project is to study whether the x-dip phenomenon is also possible in spectral lines of helium-like ions from laser-produced plasmas. While helium-like ions and the corresponding two-Coulomb-centre systems having two electrons do not possess exact additional conserved quantities, they possess approximate additional conserved quantities [11]. This may be sufficient for the x-dips to occur also in these systems.…”

Section: Introductionmentioning

confidence: 99%

Analytical theory of charge-exchange-caused dips in spectral lines of He-like ions from laser-produced plasmas

Dalimier

Oks

2014

J. Phys. B: At. Mol. Opt. Phys.

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Previously we discovered a way for producing not-yet-available fundamental data on charge exchange between multicharged ions, virtually inaccessible by other experimental methods. It was based on the formation of dips (called x-dips) in spectral lines of hydrogen-like ions from laser-produced plasmas. At that time the x-dip phenomenon was considered to be possible only in spectral lines of hydrogenic systems: due to the existence of exact algebraic (higher than geometrical) symmetries relevant only to hydrogenic systems and to the corresponding two-Coulomb-centre systems (dicentres) having one electron. In the present paper, by engaging the concept of an approximate algebraic symmetry of two-electron dicentres (and of helium-like ions), we opened up the way to significantly broaden the scope of experimental studies of the x-dip phenomenon-to studies of possible x-dips in spectral line profiles emitted by He-like ions in laser-produced plasmas. We identified three prospective two-electron dicentres and calculated analytically theoretical positions of the x-dips in the corresponding He-like spectral lines (though future experimental and theoretical studies should not be limited to these three two-electron dicentres). Since future experimental and theoretical studies should not be limited to these three two-electron dicentres, we presented also a table containing 15 prospective He-like spectral lines and 10 corresponding solid targets for observing x-dips in laser-produced plasmas. For completeness we presented also a similar table for H-like lines. It presented 16 prospective H-like spectral lines and 11 corresponding solid targets for observing x-dips in laser-produced plasmas. From the shape of experimental x-dips it is possible to determine the rate coefficient of charge exchange in the corresponding dicentre, as demonstrated previously. Therefore the results of the present paper should very significantly extend the range of fundamental data on charge exchange between multicharged ions that can be obtained via the x-dip phenomenon, but not by any other method.

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On the classification of the doubly excited states of the two-electron atom

Cited by 43 publications

References 8 publications

Review of Langmuir-Wave-Caused Dips and Charge-Exchange-Caused Dips in Spectral Lines from Plasmas and their Applications

Review of Langmuir-Wave-Caused Dips and Charge-Exchange-Caused Dips in Spectral Lines from Plasmas and their Applications

Symmetry in atomic and molecular systems

Analytical theory of charge-exchange-caused dips in spectral lines of He-like ions from laser-produced plasmas

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