Metastable<mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" display="inline"><mml:mrow><mml:msubsup><mml:mrow><mml:mi mathvariant="normal">He</mml:mi></mml:mrow><mml:mrow><mml:mn>2</mml:mn></mml:mrow><mml:mrow><mml:mi mathvariant="normal">−</mml:mi></mml:mrow></mml:msubsup></mml:mrow></mml:math>ions formed by two-electron attachment to the excited<mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" display="inline"><mml:mrow><mml:msubsup><mml:mrow><mml:mi mathvariant="normal">He</mml:mi></mml:mr

Adamowicz, Ludwik; Pluta, Tadeusz

doi:10.1103/physreva.44.2860

Cited by 16 publications

(5 citation statements)

References 25 publications

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“…This provides the reason for their metastability and thus, long finite life times of (359.0 ± 0.7) μs (for j = 5/2, where j denotes the total angular momentum quantum number) for He * − [15] and (135 ± 15) μs for He 2 * − [16]. He * − and He 2 * − have received a substantial amount of interest from a theoretical point of view, see for example Ref [17] and references therein. To this solid basis of work we add (i) the validation that standard quantum chemical tools are capable of describing these states and the interactions of interest and (ii) an interpretation of the following experimental observations [1]:…”

Section: Introductionmentioning

confidence: 98%

On the properties of charged and neutral, atomic and molecular helium species in helium nanodroplets: interpreting recent experiments

Huber

Mauracher

2013

Molecular Physics

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Properties of ground state He(=He(1s 2 1 S)), He + (=He(1s 2 S)), He + 2 (=He 2 (1σ 2 g 1σ u 2 + u )) and excited (metastable) He * (=He(1s2s 3 S)), He 2 * (=He 2 (1σ 2 g 1σ u 2σ g 3 + u )), He * − (=He(1s2s2p 4 P)) and He 2 * − (=He 2 (1σ 2 g 1σ u 2σ g 1π u 4 g )) are calculated using the coupled-cluster method and basis sets multiply augmented with diffuse functions. The aim of this work is to capture the essential physics needed to describe the qualitatively different behaviour of the above mentioned helium species dissolved in liquid helium. By studying their interaction with atomic ground state helium it is found that ground state He, He + , He 2 + and excited (metastable) He * − are well bound within a helium droplet. In comparison excited (metastable) He * , He 2 * and He 2 * − are found to be squeezed out due to the high energetic cost associated with the large volume they require inside a helium droplet. In particular, the molecular species He 2 * and He 2 * − consist of a positive core in the form of a He 2 + which is surrounded by a diffuse electronic cloud accounting for one or two electrons, respectively. The implications of these results for recent experimental studies on helium nanodroplets are discussed, particularly for the negatively charged species He * − and He 2 * − . We find that the latter species experience completely different dynamcis in a helium droplet although they are very similar in various other respects (e.g. diffuse electron clouds, size) in good agreement with experimental observations.

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Section: Introductionmentioning

confidence: 98%

On the properties of charged and neutral, atomic and molecular helium species in helium nanodroplets: interpreting recent experiments

Huber

Mauracher

2013

Molecular Physics

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“…Both, He*  and He2*  have received substantial amount of interest from experiment [225][226][227] and theory [228][229][230][231][232][233][234]. For both helium anions, fast, non-relativistic Coulomb autodetachment on the fstime scale is forbidden [226], which explains their metastability and thus long life times of (359  0.7) µs (for total angular momentum quantum number j = 5/2) for the atomic helium anion [226] and (135  15) µs for the molecular helium anion [235].…”

Section: Formation Of Anionic Speciesmentioning

confidence: 99%

Cold physics and chemistry: Collisions, ionization and reactions inside helium nanodroplets close to zero K

et al. 2018

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“…In addition to previous theoretical studies on the metastable states of both atomic and diatomic helium, 11 the interaction of He * − and He * − 2 with He atoms has been recently investigated by means of quantum mechanical (QM) calculations of the coupled cluster with single, double and (perturbative) triple excitations CCSD(T) type. 5 Ab initio energies for the He( 1 S)-He * − ( 4 P) and He( 1 S)-He * − 2 ( 4 Σ g ) interactions were calculated for different interparticle distances and angular orientations.…”

Section: Introductionmentioning

confidence: 99%

A configurational study of helium clusters doped with He∗− and He2∗−

Rodríguez‐Cantano

González‐Lezana

Villarreal

et al. 2015

The Journal of Chemical Physics

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Path integral Monte Carlo simulation of the absorption spectra of an Al atom embedded in helium J. Chem. Phys. 123, 134319 (2005) Helium clusters doped with electronically excited atomic and molecular helium anions He * − and He * − 2 at T = 0.4 K are studied by means of path integral Monte Carlo calculations. Geometry and energetics of the systems with up to 32 solvating He atoms are characterised. The interactions between the anions and the neutral He atoms have been described by fitting previously reported ab initio points to analytical expressions. The He N -He * − clusters with N > 6 display a structure defined by a bipyramid which completely solvates the atomic anion, whereas the rest of surrounding He atoms form a dimple around that initial cage. On the contrary, the structures observed for the He N -He * − 2 clusters clearly show the dopant located outside the helium droplet, thereby confirming the heliophobic character of He * − 2 . C 2015 AIP Publishing LLC. [http://dx

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MetastableHe2−ions formed by two-electron attachment to the excitedHe

Cited by 16 publications

References 25 publications

On the properties of charged and neutral, atomic and molecular helium species in helium nanodroplets: interpreting recent experiments

On the properties of charged and neutral, atomic and molecular helium species in helium nanodroplets: interpreting recent experiments

Cold physics and chemistry: Collisions, ionization and reactions inside helium nanodroplets close to zero K

A configurational study of helium clusters doped with He∗− and He2∗−

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