Measurement of Cesium and Rubidium Charge-Transfer Cross Sections

Perel, Julius; Vernon, Richard H.; Daley, Howard L.

doi:10.1103/physrev.138.a937

Cited by 97 publications

(34 citation statements)

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“…The calculations on the resonant charge-exchange total cross sections were by formulas different from Eqs. (1) and (2), and utilized the ab initio potential computations of Michels. 14 On Fig.…”

Section: Check Case: LI + -Limentioning

confidence: 99%

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Determination of the Difference Potential from Resonant Charge-Exchange Total Cross Sections: Analysis of RB+-Rb andCs
Olson
¹

1969
Phys. Rev.
26
1
6
0
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Within a two-state formalism, a systematic procedure is developed for deriving the difference between the gerade and ungerade state potentials from resonant charge-exchange total cross sections. It is shown that three potential constants may be derived from (i) the relative monotonic velocity dependence of the cross sections, (ii) the absolute scaling factor, and (iii) the frequency of the interference oscillations. The method is applied to the Rb -Rb and Cs + -Cs experimental cross-section measurements of Perel, Vernon, and Daley. The difference potential for Rb + -Rb is found to exhibit a maximum at 5.6 a.u. with a magnitude of 3.0 eV. The Cs + -Cs data are likewise analyzed and a maximum of 2.3 eV is located at 6.5 a.u. In both cases, the error estimates are about ±25%. INTRODUCTION THEORYWithin the boundaries of the validity of the twostate approximation and in the low-keV energy region, it is well established that the difference potential between the gerade and ungerade ground states of a symmetric system controls the resonant charge-exchange total cross sections. 1 Experimental measurements, such as those by Perel, Vernon, and Daley on the Rb and Cs systems, 2 may hence be used to deduce information about this difference potential.In the above experimental observations, the cross sections were found to obey the general relationship Q 1/2 =a -blnv.The most interesting aspect, however, was an oscillatory structure that was seen superimposed upon this monotonic velocity dependence. This oscillatory structure may be interpreted by a two-state stationary phase argument 3 that predicts its occurrence whenever the difference potential between the gerade and ungerade states exhibits a maximum. This same concept has been used to predict that oscillations would also appear in the cross sections of the Li -Li system. 4 The object of this work is to provide a convenient method for analyzing the resonant chargeexchange cross sections. A systematic procedure is set up for determining three parameters of the difference potential from (i) the relative monotonic velocity dependence of the cross sections, (ii) the absolute scaling factor, and (iii) the frequency of the interference oscillations. A hypothetical test case is examined and explained. Then, using the methods described within, the Rb -Rb and Cs + -Cs experimental cross sections 2 are analyzed. A check is also made by retrieving the difference potential from Li -Li theoretical cross sections 4 which were calculated by an independent method.In the two-state region of validity, the resonant charge-exchange total cross section is given by 1Here k is the wave number of the colliding system, we have k = \xv/H as usual, and 77 j are the phase shifts for the gerade and ungerade states. Except at small impact parameters b and at low velocities, the difference in phase shifts may be approximatedwhere the semi classical relation b = (Z 4-- §)/& has been utilized. If the difference potential V (r)-V~(r) possesses a maximum or a minimum, interference effects will arise from co...

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Section: Check Case: LI + -Limentioning

confidence: 99%

“…In the two-state region of validity, the resonant charge-exchange total cross section is given by 1 Q 01 = (Wk 2 )E(2l + l)sin 2 …”

Section: Introduction Theorymentioning

confidence: 99%

Determination of the Difference Potential from Resonant Charge-Exchange Total Cross Sections: Analysis of RB+-Rb andCs
Olson
¹

1969
Phys. Rev.
26
1
6
0
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“…AE stands for the energy defect of the reaction. AE=O gives rise to "resonant", AE~O to "nonresonant" charge transfer [11] with cross sections of typically 10-14cm 2 and 10-15cm 2, respectively. It follows, that almost complete neutralization can be achieved in a gas with a pressure of about 10-a mbar and an interaction length of a few centimeters.…”

Section: Methodsmentioning

confidence: 99%

Neutralization of mass-selected cluster ions by charge transfer reactions

et al. 1985

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Mass-separated beams of clusters with a single, well-defined number of atoms or molecules are indispensable for studies of cluster properties. This paper presents a technique with the potential to generate such a beam which contains neutral clusters of one size only. For this purpose mass-selected cluster ions have been neutralized by charge transfer reactions in metal and sulphur vapors. Relative charge exchange cross sections were measured for different cluster sizes. They reveal pronounced variations of the electronic structure of these particles. Thus, the study of charge transfer processes is introduced as a method to probe the positions of electronic energy levels in neutral clusters.

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“…During the last 50 years, charge exchange studies of atom-atom [1], ion-alkali [2,3] and ion-Rydberg collisions [4] at the total cross section level have systematically indicated the presence of oscillatory structures which were either interpreted as due to a region of stationary phase in the difference between the incident and outgoing channels or, in a classical picture, the number of swaps the electron undergoes across the potential saddle before it is captured by the projectile [5]. A more detailed inspection of the physical mechanisms responsible for those oscillations was experimentally prohibitive in those days while the limited computational facilities also restricted the theoretical capabilities to further refine our understanding of those collision processes at the highly differential level.…”

Section: Introductionmentioning

confidence: 99%

Oscillatory patterns in angular differential ion-atom charge exchange cross sections: The role of electron saddle swaps

Otranto

Blank

Olson

et al. 2013

AIP Conference Proceedings

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Abstract. In this work, we have performed an experimental/theoretical study of state selective charge exchange cross sections in 1-10 keV/amu Ne 8+ +Na(3s) collisions. Theoretical calculations provided by the classical trajectory Monte Carlo method (CTMC) are contrasted to data obtained at KVI by means of the magneto-optical trap recoil-ion momentum spectroscopy technique (MOTRIMS). We find that for electron capture to n 10, a two-step mechanism which involves an initial electronic excitation followed by electron capture at a later stage of the collision applies. Oscillatory structures in the n-state selective capture cross sections and recoil ion transverse momentum distributions are present in the experimental data as well as in the theoretical results, and are ascribed to the number of swaps the electron undergoes across the potential energy saddle during the collision process.

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Measurement of Cesium and Rubidium Charge-Transfer Cross Sections

Cited by 97 publications

References 8 publications

Determination of the Difference Potential from Resonant Charge-Exchange Total Cross Sections: Analysis of RB+-Rb andCs
Olson
¹

1969
Phys. Rev.
26
1
6
0
View full text Add to dashboard Cite

Determination of the Difference Potential from Resonant Charge-Exchange Total Cross Sections: Analysis of RB+-Rb andCs
Olson
¹

1969
Phys. Rev.
26
1
6
0
View full text Add to dashboard Cite

Neutralization of mass-selected cluster ions by charge transfer reactions

Oscillatory patterns in angular differential ion-atom charge exchange cross sections: The role of electron saddle swaps

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Measurement of Cesium and Rubidium Charge-Transfer Cross Sections

Cited by 97 publications

References 8 publications

Determination of the Difference Potential from Resonant Charge-Exchange Total Cross Sections: Analysis of RB+-Rb andCsOlson1 1969Phys. Rev.26160View full textAdd to dashboardCite

Determination of the Difference Potential from Resonant Charge-Exchange Total Cross Sections: Analysis of RB+-Rb andCsOlson1 1969Phys. Rev.26160View full textAdd to dashboardCite

Neutralization of mass-selected cluster ions by charge transfer reactions

Oscillatory patterns in angular differential ion-atom charge exchange cross sections: The role of electron saddle swaps

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Determination of the Difference Potential from Resonant Charge-Exchange Total Cross Sections: Analysis of RB+-Rb andCs
Olson
¹

1969
Phys. Rev.
26
1
6
0
View full text Add to dashboard Cite

Determination of the Difference Potential from Resonant Charge-Exchange Total Cross Sections: Analysis of RB+-Rb andCs
Olson
¹

1969
Phys. Rev.
26
1
6
0
View full text Add to dashboard Cite