A new type of excimer atom: electron + ionized helium cluster

Golov, A. I.; Sekatskiǐ, S. K.

doi:10.1007/bf01437468

Cited by 23 publications

(80 citation statements)

References 28 publications

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“…Our experiments can also be seen as the first step for the creation of new kinds of atoms comprising a large, ionized doped cluster neutralized by an ''outside'' electron which occupies a Rydberg orbit as proposed by Golov and Sekatskii [35,36].…”

Section: Discussionmentioning

confidence: 95%

Spectroscopy of alkali atoms (Li, Na, K) attached to large helium clusters

Stienkemeier

Higgins

Callegari

et al. 1996

Z Phys D - Atoms, Molecules and Clusters

228

278

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Large liquid helium clusters (He L , n+10) produced in a supersonic jet are doped with alkali atoms (Li, Na, K) and characterized by means of laser induced fluorescence. Each cluster contains, on average, less than one dopant atom. Both excitation and emission spectra have been recorded. The observed excitation spectra are analyzed, calculating the transitions within an approach based on the hypothesis that the chromophores are trapped in a dimple on the cluster's surface as predicted by the theoretical calculations of Ancilotto et al. [9]. The results of the model calculations are in good qualitative agreement with the experimental findings. In spite of the very weak binding energy (a few cm\), some of the excited atoms remain bound to the surface, provided the excitation occurs at frequencies not too far from the alkali's gas phase absorptions. These bound-bound excitations produce very broad, red shifted emission spectra. At other, blue shifted frequencies, the excited atoms desorb from the cluster's surface, giving rise to unshifted, free atom, emission spectra. The heavier alkali metals (Na, K) show, compared to the calculations, an additional broadening which is attributed to surface excitations on the helium droplet.

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Section: Discussionmentioning

confidence: 95%

Spectroscopy of alkali atoms (Li, Na, K) attached to large helium clusters

Stienkemeier

Higgins

Callegari

et al. 1996

Z Phys D - Atoms, Molecules and Clusters

228

278

View full text Add to dashboard Cite

show abstract

“…Those authors believe that the lifetime of a Rydberg state around n = 10 should be about 10 −6 s and above n = 10, should scale as in a free atom. 27 With such estimates, questions arise as to which excitation the description of the pseudodiatomic model holds, how Rydberg state observation can be achieved, and how excited states with moderate principal quantum numbers, e.g., n =6-8 for Rb, can be identified and modeled. Loginov 18 used pulsed laser excitation followed by an ionizing pulse and ion detection, a method that can be applied up to the ionization limit but assignments have been hampered by the need of high accuracy calculations.…”

Section: Discussionmentioning

confidence: 99%

“…25,26 The small size of a droplet makes this delocalization rather intriguing and has prompted speculations about the existence and stability of a Rydberg "superatom" where the positive core consists of the ionized dopant plus the whole He droplet, and the Rydberg electron orbits just outside the droplet. 27,28 Synchrotron-radiation spectroscopy data for pure He droplets have been interpreted in this sense. 29 In this article, we present laser-induced-fluorescence ͑LIF͒ excitation spectra of K, Rb, and Cs atoms, specifically the one-photon excitation of the ͑n +1͒p ← ns transition ͑n = 4, 5, and 6, respectively͒ and the two-photon one-color excitation of the 5d ← 5s transition of Rb.…”

Section: Introductionmentioning

confidence: 99%

One- and two-photon spectroscopy of highly excited states of alkali-metal atoms on helium nanodroplets

Pifrader

Allard

Auböck

et al. 2010

The Journal of Chemical Physics

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Alkali-metal atoms captured on the surface of superfluid helium droplets are excited to high energies (≈3 eV) by means of pulsed lasers, and their laser-induced-fluorescence spectra are recorded. We report on the one-photon excitation of the (n+1)p←ns transition of K, Rb, and Cs (n=4, 5, and 6, respectively) and on the two-photon one-color excitation of the 5d←5s transition of Rb. Gated-photon-counting measurements are consistent with the relaxation rates of the bare atoms, hence consistent with the reasonable expectation that atoms quickly desorb from the droplet and droplet-induced relaxation need not be invoked.

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“…On the other hand, Sekatskii (1993 and1994) proposed several years ago the existence of Rydberg states in He clusters. They considered a positive charge which was delocalized over the cluster together with an electron which was orbiting outside the cluster on Rydberg trajectories around the cluster core.…”

Section: Introductionmentioning

confidence: 99%

The electronically excited states of helium clusters: an unusual example for the presence of Rydberg states in condensed matter

Haeften

Laarmann

Wabnitz

et al. 2005

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

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The nature of the electronically excited states of He clusters and their relaxation mechanisms are investigated by spectroscopy using monochromatized synchrotron radiation. Time correlated fluorescence excitation and energy resolved luminescence spectra of the clusters are recorded in separate wavelength ranges. The size of the clusters and the isotopic constitution is also varied. The spectral features are analysed and discussed particularly with regard to the high lying states and their possible Rydberg nature. While Rydberg states seem not to exist in the interior region of large clusters there is experimental evidence that sharp lines in the spectrum are either due to He Rydberg atoms or excimer molecules in high vibrational states bound at the surface of large clusters or due to very small positively charged clusters with the Rydberg electron outside. The spectra of large 3 He clusters exhibit a larger contribution of Rydberg lines than 4 He clusters. He clusters also emit fluorescence at energies above the ionization energy of He atoms. This is attributed to the barrier for the injection of electrons into the conduction band which was found to be 1.35 eV for 4 He and 0.95 eV for 3 He clusters, respectively.

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A new type of excimer atom: electron + ionized helium cluster

Cited by 23 publications

References 28 publications

Spectroscopy of alkali atoms (Li, Na, K) attached to large helium clusters

Spectroscopy of alkali atoms (Li, Na, K) attached to large helium clusters

One- and two-photon spectroscopy of highly excited states of alkali-metal atoms on helium nanodroplets

The electronically excited states of helium clusters: an unusual example for the presence of Rydberg states in condensed matter

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