Coulomb trajectory effects on electron-impact detachment of negative ions and on mutual neutralization cross sections

Lin, Jiunn-Yuan; Jiang, Tsin-Fu; Lin, C. D.

doi:10.1088/0953-4075/29/24/023

Cited by 24 publications

(20 citation statements)

References 16 publications

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“…Cross section (cm 2 ) ACV5Z+G ACV5Z ET-mid ET-Li Croft et al 1999Lin et al 1996Expt Peart & Hayton 1994. Comparison of the theoretical total cross section for Li + + D − mutual neutralization obtained with different basis sets (see text for details) and compared to the present experimental results, to the experimental data of Peart & Hayton (1994), and to the theoretical calculations of Croft et al (1999a) and Lin et al (1996). while D is in the ground state following the loss of its extra electron. Due to the resolution of about 10 meV, we can unambiguously assign the peaks to the 3s, 3p, and 3d states of Li, even though the 3p and 3d states are separated by only 44 meV.…”

Section: -11mentioning

confidence: 99%

“…For instance, Mendez et al (1990) calculated cross sections at energies above 25 eV based on ab initio potential energy curves and non-adiabatic couplings, while Ermolaev (1992) computed partial and total cross sections for energies above 100 eV by means of a one-active electron model and a large atomic basis set. With a similar procedure initially employed at a collision energy of 375 eV, Lin et al (1996) extrapolated their results to lower energies assuming the same transition probabilities. The agreement between their results and experimental data is rather good at 0.7 eV and above 50 eV, but between these energies, the total cross section is considerably underestimated.…”

Section: Introductionmentioning

confidence: 99%

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Mutual Neutralization in Li⁺−D⁻ Collisions: A Combined Experimental and Theoretical Study

Launoy

Loreau

Dochain³

et al. 2019

ApJ

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We present a combined experimental and theoretical study of the mutual neutralization process in collisions of lithium ions (Li + ) with deuterium anions (D − ) at collision energies below 1 eV. We employ a merged-beam apparatus to determine total and state-to-state mutual neutralization cross sections. We perform nuclear dynamics calculations using the multi-channel Landau-Zener model based on accurate ab initio molecular data. We obtain an excellent agreement between the experimental and theoretical results over the energy range covered in this work. We show that the basis sets used in the ab initio calculations have a limited influence on the total cross section, but strongly impacts the results obtained for the partial cross sections or the reaction branching ratios. This demonstrates the important role of high-precision measurements to validate the theoretical approaches used to study gas-phase reactive processes. Finally, we compute mutual neutralization rate coefficients for Li + + H − and Li + + D − , and discuss their significance for astrochemistry models.

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Section: -11mentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Mutual Neutralization in Li⁺−D⁻ Collisions: A Combined Experimental and Theoretical Study

Launoy

Loreau

Dochain³

et al. 2019

ApJ

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“…The method is somewhat sensitive to the potential in which the electron waves are calculated, but the theoretical cross sections are in qualitative agreement with experiment. The fourth method [11][12][13] is a semiquantum technique in which the electron that is attached to the atom is treated quantum mechanically while the projectile electron is treated as a classical particle. The trajectory of the "classical electron" is a hyperbola that arises when a charged particle of incident energy E i interacts with an infinitely massive object of the same charge.…”

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confidence: 99%

Electron Impact Detachment of Weakly Bound Negative Ions

Robicheaux

1999

Phys. Rev. Lett.

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A method is presented for accurately calculating the total electron impact detachment cross section for weakly bound negative ions. The results are compared to recent experiments for electron impact detachment of H 2 and B 2 . Cross sections differential in energy are presented which elucidate some of the dynamics of the detachment process. A scaling law for the cross section is proposed. [S0031-9007(98) PACS numbers: 34.80. Kw, 34.10. + x There have been several recent experiments measuring the electron impact detachment of atomic and molecular negative ions [1][2][3][4][5][6][7][8]. These experiments exemplify one of the more important processes in physics: the breaking of a target by a projectile giving at least three distinct bodies in the final state. This process is especially difficult to describe theoretically due to the necessity for describing two continua. In this paper, I describe an accurate method for calculating cross sections that takes advantage of the nature of the double continua for electron detachment of negative ions. The calculated cross sections have been dissected in order to gain an understanding of the dynamics governing the detachment process. The insight thus obtained leads to scaling rules for detachment from weakly bound negative ions (ions for which the weakly bound electron is most likely found outside of the region that contains the atomic electrons).There have been four previous methods used to describe electron impact detachment of negative ions. A brief description of these calculations may give some insight into the difficulties that must be overcome. The first method [9] used what is now called an R-matrix pseudostate method to calculate the detachment as an excitation to a positive energy pseudostate. This method did not achieve converged cross sections due to the slow decrease of cross section with increasing total angular momentum. The second method [5] utilized a classical, phenomenological technique. The total detachment cross section is estimated to be the cross section for a classical electron moving in a repulsive Coulomb potential to be absorbed by a partially absorbing sphere of radius r 0 . This radius and the absorbing fraction are fitted to the experimentally measured detachment cross section.The third method [10] used a fully quantum first order distorted wave theory. Electron wave functions separable in r 1 and r 2 (the two outgoing electron's coordinates) are used for both the initial and the final states. The initial state is nearly separable in r 1 and r 2 since it describes one electron weakly bound to the atom/molecule and the projectile electron in a continuum state. However, the final state is not expected to be separable in these coordinates since the final state wave function describes two highly correlated electrons that are both in the continuum. The method is somewhat sensitive to the potential in which the electron waves are calculated, but the theoretical cross sections are in qualitative agreement with experiment. The fourth method [11][12][...

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“…Electron-impact detachment is a process that has been extensively studied for atoms and small molecules [7][8][9][10][11][12][13][14][15]. Because of the high degree of electron correlation in the negative systems, these experiments are sensitive to the electronic structure.…”

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confidence: 99%

Size-Dependent Electron-Impact Detachment of Internally ColdCn−andAln
Diner
¹
,
Toker
²
,
Strasser
³

et al. 2004
Phys. Rev. Lett.
17
0
10
0
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The cross sections for electron detachment of internally cold Cn- and Aln- clusters were measured using an electrostatic ion beam trap fitted with an internal electron target. The measured electron-impact detachment cross sections for the Cn- (n = 1-9) clusters exhibit even-odd oscillations reflecting the binding energy trend, namely, higher cross sections for weaker binding. Surprisingly, however, these cross sections increase on the average with cluster size, n, in spite of the increase in electron binding. In contrast, the Aln- (n = 2-5) clusters follow the known scaling laws for electron detachment. We suggest that the size-dependent polarizability of these clusters is responsible for the observed behavior.

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Coulomb trajectory effects on electron-impact detachment of negative ions and on mutual neutralization cross sections

Cited by 24 publications

References 16 publications

Mutual Neutralization in Li⁺−D⁻ Collisions: A Combined Experimental and Theoretical Study

Mutual Neutralization in Li⁺−D⁻ Collisions: A Combined Experimental and Theoretical Study

Electron Impact Detachment of Weakly Bound Negative Ions

Size-Dependent Electron-Impact Detachment of Internally ColdCn−andAln
Diner
¹
,
Toker
²
,
Strasser
³

et al. 2004
Phys. Rev. Lett.
17
0
10
0
View full text Add to dashboard Cite

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Coulomb trajectory effects on electron-impact detachment of negative ions and on mutual neutralization cross sections

Cited by 24 publications

References 16 publications

Mutual Neutralization in Li+−D− Collisions: A Combined Experimental and Theoretical Study

Mutual Neutralization in Li+−D− Collisions: A Combined Experimental and Theoretical Study

Electron Impact Detachment of Weakly Bound Negative Ions

Size-Dependent Electron-Impact Detachment of Internally ColdCn−andAlnDiner1, Toker2, Strasser3 et al. 2004Phys. Rev. Lett.170100View full textAdd to dashboardCite

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Mutual Neutralization in Li⁺−D⁻ Collisions: A Combined Experimental and Theoretical Study

Mutual Neutralization in Li⁺−D⁻ Collisions: A Combined Experimental and Theoretical Study

Size-Dependent Electron-Impact Detachment of Internally ColdCn−andAln
Diner
¹
,
Toker
²
,
Strasser
³

et al. 2004
Phys. Rev. Lett.
17
0
10
0
View full text Add to dashboard Cite