Binding Energies in Atomic Negative Ions: III

Andersen, T.; Haugen, H.K.; Hotop, H.

doi:10.1063/1.556047

Cited by 539 publications

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“…(J Am Soc Mass Spectrom 2010, 21, 1944 -1946) © 2010 American Society for Mass Spectrometry T he chemical concept of metals producing positive ions (cations) and non-metals negative ions (anions) is a fundamental precept taught as early as in high school and reinforced throughout a person's university career. However, under certain conditions, metal anions can be created and, as such, their electron affinities are well characterized and calculated both experimentally and theoretically [1]. In solution, alkali metal anions (except lithium) in 'supra molecule complexes' have been prepared in THF and crown ethers.…”

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confidence: 99%

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Old acid, new chemistry. Negative metal anions generated from alkali metal oxalates and others

Curtis

Renaud

Holmes

et al. 2010

J. Am. Soc. Mass Spectrom.

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A brief search in Sci Finder for oxalic acid and oxalates will reward the researcher with a staggering 129,280 hits. However, the generation of alkali metal and silver anions via collision-induced dissociation of the metal oxalate anion has not been previously been reported, though Tian and coworkers recently investigated the dissociation of lithium oxalate [18]. The exothermic decomposition of alkali metal oxalate anion to carbon dioxide in the collision cell of a triple quadrupole mass spectrometer leaves no place for the electron to reside, resulting in a double electron-transfer reaction to produce an alkali metal anion. This reaction is facilitated by the negative electron affinity of carbon dioxide and, as such, the authors believe that metal oxalates are potentially unique in this respect. The observed dissociation reactions for collision with argon gas (1.7-1.8 ϫ 10 Ϫ3 mbar) for oxalic acid and various alkali metal oxalates are discussed and summarized. Silver oxalate is also included to demonstrate the propensity of this system to generate transition-metal anions, as well. (J Am Soc Mass Spectrom 2010, 21, 1944 -1946) © 2010 American Society for Mass Spectrometry T he chemical concept of metals producing positive ions (cations) and non-metals negative ions (anions) is a fundamental precept taught as early as in high school and reinforced throughout a person's university career. However, under certain conditions, metal anions can be created and, as such, their electron affinities are well characterized and calculated both experimentally and theoretically [1]. In solution, alkali metal anions (except lithium) in 'supra molecule complexes' have been prepared in THF and crown ethers. These characteristically blue solutions are now fabricated to control the amount of metal ions, including metal anions. Such solutions have been extensively studied for use in organic synthesis and elucidation of charge-transfer to solvent dynamics (CTTS) [2][3][4][5][6][7][8][9]. In the gas phase, a beam of positively charged alkali cations created from metal vapor can undergo double electron capture to generate a low density negative ion beam [10]. Other means of negative ion generation include discharge and sputter ion sources, namely Cs ϩ ions with a suitable metal cathode [11]. Studies in ion traps utilize dissociative electron attachment to create metal anions [12]. Thus, metal anions are created only via complex experimental procedures or specific experimental apparatus. This paper outlines a method for the production of metal anions requiring a simple oxalate salt solution and a commercially available triple quadrupole mass spectrometer.Oxalic acid is one of the oldest known acids, first isolated from wood sorrel (Oxalis acetosella). It is often found as salt oxalates in many biological systems; particular well known is calcium oxalate found in rhubarb root, known for both its medicinal properties and as a potential poison. Ammonium oxalate is found in guano and there is evidence for the sodium and potassium salts pres...

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mentioning

confidence: 99%

“…However, under certain conditions, metal anions can be created and, as such, their electron affinities are well characterized and calculated both experimentally and theoretically [1]. In solution, alkali metal anions (except lithium) in 'supra molecule complexes' have been prepared in THF and crown ethers.…”

mentioning

confidence: 99%

Old acid, new chemistry. Negative metal anions generated from alkali metal oxalates and others

Curtis

Renaud

Holmes

et al. 2010

J. Am. Soc. Mass Spectrom.

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“…Since there are no previous calculations of this process, the only comparison that can be made is with a number of calculations for reactions (4) involving (anti)hydrogen and incident Ps with n = 1-3. When examining these results, one should have in mind that our method is by far the simplest, and that it is not expected to be accurate for low n and the relatively strongly bound H − or e + H (ε b = 0.754 eV [71]). What we are looking for here is a broad order-of-magnitude agreement and correct energy dependence of the cross sections (except in the narrow near-threshold energy range).…”

Section: A Comparisons With Existing Calculations For Ps-h Collisionsmentioning

confidence: 99%

Formation of positron-atom bound states in collisions between Rydberg Ps and neutral atoms

Swann¹,

Cassidy

Deller

et al. 2016

Phys. Rev. A

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Predicted twenty years ago, positron binding to neutral atoms has not yet been observed experimentally. A new scheme is proposed to detect positron-atom bound states by colliding Rydberg positronium (Ps) with neutral atoms. Estimates of the charge-transfer reaction cross section are obtained using the first Born approximation for a selection of neutral atom targets and a wide range of incident Ps energies and principal quantum numbers. We also estimate the corresponding Ps ionization cross section. The accuracy of the calculations is tested by comparison with earlier predictions for Ps charge transfer in collisions with hydrogen and antihydrogen. We describe an existing Rydberg Ps beam suitable for producing positron-atom bound states and estimate signal rates based on the calculated cross sections and realistic experimental parameters. We conclude that the proposed methodology is capable of producing such states and of testing theoretical predictions of their binding energies.

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“…When the depletion laser was added, the remaining population in the 2 D excited state was further reduced (see figure 4). For a given laser beam flux Φ (photons×cm −2 ×s −1 ) and photodetachment cross section σ (cm 2 ), the fraction of negative ions not neutralized by the laser is given by n n 0 = e −σΦt (1) where n 0 is the initial number of negative ions, n is the number of remaining ions, and t is the laser-ion interaction time. Figure 5 shows the relative excited 2 D state population as a function of the depletion laser power, normalized to the value without the depletion laser.…”

Section: Siliconmentioning

confidence: 99%

“…The addition of an extra electron to an otherwise neutral system changes the fundamental properties of the quantum system [1]. An atomic negative ion only supports a few bound states, and its binding energy is typically an order of magnitude smaller than the ionization potential of the neutral atom.…”

Section: Introductionmentioning

confidence: 99%

Depletion of the excited state population in negative ions using laser photodetachment in a gas-filled RF quadrupole ion guide

Lindahl¹,

Hanstorp²,

Forstner³

et al. 2010

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

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Abstract. The depopulation of excited states in beams of negatively charged carbon and silicon ions was demonstrated using collisional detachment and laser photodetachment in a radio frequency quadrupole ion guide filled with helium. The high lying, loosely bound 2 D excited state in C − was completely depleted through collisional detachment alone, which was quantitatively determined within 6%. For Si − the combined signal from the population in the 2 P and 2 D excited states was only partly depleted through collisions in the cooler. The loosely bound 2 P state was likely to be completely depopulated and the more tightly bound 2 D state was partly depopulated through collisions. 98(2)% of the remaining 2 D population was removed by photodetachment in the cooler using less than 2 W laser power. The total reduction of the excited population in Si − , including collisional detachment and photodetachment, was estimated to be 99(1)%. Employing this novel technique to produce a pure ground state negative ion beam offers possibilities to enhance selectivity, as well as accuracy, in high precision experiments on atomic as well as molecular negative ions.

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Binding Energies in Atomic Negative Ions: III

Cited by 539 publications

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Old acid, new chemistry. Negative metal anions generated from alkali metal oxalates and others

Old acid, new chemistry. Negative metal anions generated from alkali metal oxalates and others

Formation of positron-atom bound states in collisions between Rydberg Ps and neutral atoms

Depletion of the excited state population in negative ions using laser photodetachment in a gas-filled RF quadrupole ion guide

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