Candidate for Laser Cooling of a Negative Ion: Observations of Bound-Bound Transitions in<mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" display="inline"><mml:mrow><mml:msup><mml:mrow><mml:mi>La</mml:mi></mml:mrow><mml:mrow><mml:mo>−</mml:mo></mml:mrow></mml:msup></mml:mrow></mml:math>

Walter, C. W.; Gibson, N. D.; Matyas, D.J.; Crocker, Clayton; Dungan, Kristina; Matola, Brad; Rohlén, J.

doi:10.1103/physrevlett.113.063001

Cited by 54 publications

(67 citation statements)

References 27 publications

(48 reference statements)

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“…In particular, the detection of molecular anions in various astrophysical environments (coma of comets 4 , interstellar molecular clouds 5 , and extraterrestrial atmospheres 6 ), the recent prospects for laser cooling of atomic 7 and molecular 8 anions, and the possibility of using anions for sympathetic cooling of anti-protons 9 are some of the exciting topics which have broadened the interest on the structure and dynamics of molecular anions.…”

Section: Introductionmentioning

confidence: 99%

“…Direct laser cooling method are routinely used to reach the utracold regime for neutral and cationic atoms (mostly alkali and alkaline earth) but have so far never been applied to anions even tough some atomic anions such as La − and Os − exhibit stable excited electronic states and represent potential candidates for laser cooling 7,42 . The direct laser cooling of molecules is complicated by the lack of closed transition cycles and requires advanced cooling schemes.…”

Section: Introductionmentioning

confidence: 99%

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Ab initio study of the neutral and anionic alkali and alkaline earth hydroxides: Electronic structure and prospects for sympathetic cooling of OH−

Kas

Loreau

Liévin

et al. 2017

The Journal of Chemical Physics

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We have performed a systematic ab initio study on alkali and alkaline earth hydroxide neutral (MOH) and anionic (MOH − ) species where M = Li, Na, K, Rb, Cs or Be, Mg, Ca, Sr, Ba. The CCSD(T) method using extended basis sets and MDF electron core potentials as been used to study their equilibrium geometries, interaction energies, adiabatic electron affinities and potential energy surfaces. All neutral and anionic species exhibit a linear shape with the exception of BeOH, BeOH − and MgOH − , for which the equilibrium structure is bent. In the context of sympathetic cooling of OH − by collision with ultracold alkali and alkaline earth atoms, we investigate the M-OH − potential energy surfaces and the associative detachment reaction M+OH − → MOH+e − , which is the only energetically allowed reactive channel in the cold regime. We discuss the implication for the sympathetic cooling of OH − and conclude than Li and K are the best candidates for ultracold buffer gas.

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Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Ab initio study of the neutral and anionic alkali and alkaline earth hydroxides: Electronic structure and prospects for sympathetic cooling of OH−

Kas

Loreau

Liévin

et al. 2017

The Journal of Chemical Physics

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“…Like the ionization potential, the electron affinity (EA) is a fundamental parameter for understanding chemical properties of elements2122. The detailed knowledge of fine structures of anions is also required by laser cooling of negative ions232425262728.…”

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confidence: 99%

Accurate Electron Affinity of Iron and Fine Structures of Negative Iron ions

Chen

Luo

et al. 2016

Sci Rep

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Ionization potential (IP) is defined as the amount of energy required to remove the most loosely bound electron of an atom, while electron affinity (EA) is defined as the amount of energy released when an electron is attached to a neutral atom. Both IP and EA are critical for understanding chemical properties of an element. In contrast to accurate IPs and structures of neutral atoms, EAs and structures of negative ions are relatively unexplored, especially for the transition metal anions. Here, we report the accurate EA value of Fe and fine structures of Fe− using the slow electron velocity imaging method. These measurements yield a very accurate EA value of Fe, 1235.93(28) cm−1 or 153.236(34) meV. The fine structures of Fe− were also successfully resolved. The present work provides a reliable benchmark for theoretical calculations, and also paves the way for improving the EA measurements of other transition metal atoms to the sub cm−1 accuracy.

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“…The accurate theoretical description of these ions still challenges the state-of-the-art quantum computations although the numbers of their bound states are generally finite. The low-excitation levels of negative ions are readily accessible by laser spectroscopy (see, e.g., [3][4][5][6]). Therefore, this technique has been a prime source of experimental information about the mutual interactions among the valence electrons.…”

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confidence: 99%

Prominent role of multielectron processes inK-shell double and triple photodetachment of oxygen anions

et al. 2016

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The photon-ion merged-beams technique was used at a synchrotron light source for measuring absolute cross sections of double and triple photodetachment of O − ions. The experimental photon energy range of 524-543 eV comprised the threshold for K-shell ionization. Using resolving powers of up to 13000, the position, strength and width of the below-threshold 1s 2s 2 2p 6 2 S resonance as well as the positions of the 1s 2s 2 2p 5 3 P and 1s 2s 2 2p 5 1 P thresholds for K-shell ionization were determined with high-precision. In addition, systematically enlarged multi-configuration Dirac-Fock calculations have been performed for the resonant detachment cross sections. Results from these abinitio computations agree very well with the measurements for the widths and branching fractions for double and triple detachment, if double shake-up (and -down) of the valence electrons and the rearrangement of the electron density is taken into account. For the absolute cross sections, however, a previously found discrepancy between measurements and theory is confirmed. Negative atomic ions play an important role in lowtemperature plasmas such as the upper atmosphere or the interstellar medium [1] and also in technical applications. For example, in the context of antihydrogen production, it has been proposed to use an ensemble of laser-cooled anions as a coolant for antiprotons [2]. Negative ions are fundamentally different from neutral atoms or positive ions since the extra electron in a negative ion is not only bound by the long-range Coulomb interaction with the atomic nucleus but, more importantly, also by a short-range attractive force due to the polarization of the atomic core. The accurate theoretical description of these ions still challenges the state-of-the-art quantum computations although the numbers of their bound states are generally finite. The low-excitation levels of negative ions are readily accessible by laser spectroscopy (see, e.g., [3][4][5][6]). Therefore, this technique has been a prime source of experimental information about the mutual interactions among the valence electrons.A sensitive tool for studying the interactions between the valence and the core electrons is inner-shell ionization of negative ions [7,8]. Here, we apply the photon-ion merged-beams technique (see [9] for a recent overview) to determine the absolute cross sections for double and triple ionization (detachment) of oxygen anions in the photon energy range 524-543 eV. In this energy range, a K-shell vacancy may be produced either by direct ionization of an initial 1s electron or via the formation of a resonance state by exciting one 1s electron to a higher shell such as 2p. In either case, the K-vacancy decays subsequently by a cascade of radiative and nonradiative processes leading to a distribution of final charge states with O + and O 2+ as the most prominent charged reaction products. To test and better understand the theoretical prediction of such cascades, we performed extremely comprehensive quantum calculations for the formation...

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Candidate for Laser Cooling of a Negative Ion: Observations of Bound-Bound Transitions inLa−

Cited by 54 publications

References 27 publications

Ab initio study of the neutral and anionic alkali and alkaline earth hydroxides: Electronic structure and prospects for sympathetic cooling of OH−

Ab initio study of the neutral and anionic alkali and alkaline earth hydroxides: Electronic structure and prospects for sympathetic cooling of OH−

Accurate Electron Affinity of Iron and Fine Structures of Negative Iron ions

Prominent role of multielectron processes inK-shell double and triple photodetachment of oxygen anions

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