Observation of small long-lived diatomic dications<mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" display="inline"><mml:msup><mml:mi>BeH</mml:mi><mml:mrow><mml:mn>2</mml:mn><mml:mo>+</mml:mo></mml:mrow></mml:msup></mml:math>and<mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" display="inline"><mml:msup><mml:mi>BeD</mml:mi><mml:mrow><mml:mn>2</mml:mn><mml:mo>+</mml:mo></mml:mrow></mml:msup></mml:math>

Franzreb, Klaus; Sobers, Richard C.; Lörinčı́k, Jan; Williams, Peter W.

doi:10.1103/physreva.71.024701

Cited by 11 publications

(4 citation statements)

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“…[22]). Note that BeH ++ and AlH ++ have been recently observed to survive flight times of about 4 and 7 µs, respectively [33], thus supporting our calculations.…”

supporting

confidence: 90%

Simple Three-Parameter Model Potential for Diatomic Systems: From Weakly and Strongly Bound Molecules to Metastable Molecular Ions

Xie

Gong

2005

Phys. Rev. Lett.

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Based on a simplest molecular orbital theory of H + 2 , a three-parameter model potential function is proposed to describe ground-state diatomic systems with closed-shell and/or S-type valence-shell constituents over a significantly wide range of internuclear distances. More than 200 weakly and strongly bound diatomics have been studied, including neutral and singly-charged diatomics (e.g., H2, Li2, LiH, Cd2, Na + 2 , and RbH − ), long-range bound diatomics (e.g., NaAr, CdNe, He2, CaHe, SrHe, and BaHe), metastable molecular dications (e.g., BeH++ , AlH ++ , Mg ++ 2 , and LiBa ++ ), and molecular trications (e.g., YHe+++ and ScHe +++ ).PACS numbers: 34.20.-b, 33.15.-e, 21.45.+v, 36.40.-c, 83.10.-y, 82.20.-w Modeling the interaction potential of diatomic systems is of fundamental importance to many issues [1,2,3,4,5,6,7,8], including atom-atom collisions, molecular spectroscopy, prediction of cluster structures, molecular dynamics simulation, chemical reactivity, matter-wave interferometry, and transport properties for more complex systems. Also of great interest are the potential functions for long-lived metastable doubly-or multiplycharged ions [9] that are relevant to high-density energy storage materials and to characterization and analytical methods for biosystems.Modern spectroscopy, diffraction, and scattering techniques [1, 3] provide a direct experimental approach to studies of interaction potentials of diatomic systems. In particular, diatomic potentials can be inferred from the spectroscopy data by three general approaches [10]: (i) the Wentzel-Kramers-Brillouin (WKB) Rydberg-KleinRees (RKR) method, (ii) the WKB-based Dunham approach, and (iii) semiempirical or empirical procedures. On the theoretical side, a diatomic potential curve may be predicted directly by ab initio calculations [11] and quantum Monte Carlo simulations [12]. These theoretical methods can, in principle, be very accurate when sufficient electronic configurations are included in the calculations, but can be prohibitively expensive in weakly bound systems [2] and/or many-electron systems [3].Numerous attempts to analytically model diatomic potentials have been made [3,5,10,13,14,15,16]. The well-known potential functions include Morse, Born-Mayer, Hulburt-Hirschfelder, Rosen-Morse, Rydberg, Pöschl-Teller, Linnett, Frost-Musulin, Varshni III, Lippincott, Lennard-Jones, and Maitland-Smith potentials [3,10], as well as the celebrated Tang-Toennies potential [5] and the recently proposed Morse-based potentials [13]. These potentials usually aim to describe either strongly or weakly bound, neutral or singlycharged diatomics and often lose their validity for either small or relatively large internuclear distance (denoted R hereafter). Thus, recent effort has been devoted to the construction of hybrid potentials, which use different functions for different interaction regions of The goal of this Letter is twofold. First, we propose a molecular-orbital theory based approach to obtain a very simple analytical potential of diatomic systems. ...

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“…[22]). Note that BeH ++ and AlH ++ have been recently observed to survive flight times of about 4 and 7 µs, respectively [33], thus supporting our calculations.…”

supporting

confidence: 90%

Simple Three-Parameter Model Potential for Diatomic Systems: From Weakly and Strongly Bound Molecules to Metastable Molecular Ions

Xie

Gong

2005

Phys. Rev. Lett.

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“…39͒ using additional toluene vapor flooding. 40 In order to test this interpretation, we made an effort to produce this dianion BeC 6 2− by toluene flooding of a Cs + -bombarded Be metal foil.…”

Section: −mentioning

confidence: 98%

Small gas-phase dianions produced by sputtering and gas flooding

Franzreb

Williams

2005

The Journal of Chemical Physics

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We have extended our previous experiment [Schauer et al., Phys. Rev. Lett. 65, 625 (1990)] where we had produced small gas-phase dianion clusters of C(n) (2-)(n > or =7) by means of sputtering a graphite surface by Cs(+) ion bombardment. Our detection sensitivity for small C(n) (2-) could now be increased by a factor of about 50 for odd n. Nevertheless, a search for the elusive pentamer dianion of C(5) (2-) was not successful. As an upper limit, the sputtered flux of C(5) (2-) must be at least a factor of 5000 lower than that of C(7) (2-), provided that the lifetime of C(5) (2-) is sufficiently long to allow its detection by mass spectrometry. When oxygen gas (flooding with either O(2) or with N(2)O) was supplied to the Cs(+)-bombarded graphite surface, small dianions of OC(n) (2-)(5< or =n < or =14) and O(2)C(7) (2-) were observed in addition to C(n) (2-)(n > or =7). Similarly, Cs(+) sputtering of graphite with simultaneous SF(6) gas flooding produced SC(n) (2-)(6< or =n< or =18). Mixed nitrogen-carbon or fluorine-carbon dianion clusters could not be observed by these means. Attempts to detect mixed metal-fluoride dianions for SF(6) gas flooding of various Cs(+)-bombarded metal surfaces were successful for the case of Zr, where metastable ZrF(6) (2-) was observed. Cs(+) bombardment of a silicon carbide (SiC) wafer produced SiC(n) (2-) (n=6,8,10). When oxygen gas was supplied to the Cs(+)-bombarded SiC surface, small dianions of SiOC(n) (2-) (n=4,6,8) and of SiO(2)C(n) (2-) (n=4,6) as well as a heavier unidentified dianion (at mz=98.5) were observed. For toluene (C(7)H(8)) vapor flooding of a Cs(+)-bombarded graphite surface, several hydrocarbon dianion clusters of C(n)H(m) (2-)(n> or =7) were produced in addition to C(n) (2-)(n> or =7), while smaller C(n)H(m) (2-) with n< or =6 could not be observed. BeC(n) (2-) (n=4,6,8,10), Be(2)C(6) (2-), as well as BeC(8)H(m) (2-) (with m=2 and/or m=1) were observed for toluene vapor flooding of a Cs(+)-bombarded beryllium metal foil. The metastable pentamer (9)Be(12)C(4) (2-) at mz=28.5 was the smallest and lightest dianion molecule that we could detect. The small dianion clusters of SC(n) (2-), OC(n) (2-), BeC(n) (2-), and SiO(m)C(n) (2-) (m=0,1,2) have different abundance patterns. A resemblance exists between the abundance patterns of BeC(n) (2-) and SiC(n) (2-), even though calculated molecular structures of BeC(6) (2-) and SiC(6) (2-) are different. The abundance pattern of SC(n) (2-) is fairly similar to that of C(n) (2-).

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“…We also found that eight and twelve vibrational levels are observed for using the three-and five-parameter model potentials constructed for meta-stable dication BeH ++ and AlH ++ , respectively. The estimated lifetimes [10] for the lowest four vibrational states of BeH ++ and those for the lowest six vibrational states of AlH ++ are supported well by experiment [30,31]. All the dication cases that we have studied by using the three-parameter model potentials are presented in Figs.…”

Section: Diatomic Dicationsmentioning

confidence: 73%

“…A large number of XH ++ dications composed of first-or second-row atoms have been characterized both theoretically and experimentally [26][27][28][29][30][31][32]. Such species are usually thermodynamically unstable with respect to dissociation into two mono-cations, but significant kinetic stability may result if sufficiently high barriers impede fragmentation.…”

Section: Diatomic Dicationsmentioning

confidence: 99%