Bosonic helium clusters doped by alkali metal cations: interaction forces and analysis of their most stable structures

Marinetti, F.; Coccia, Emanuele; Bodo, Enrico; Gianturco, F. A.; Yurtsever, E.; Yurtsever, Mine; Yıldırım, Erol

doi:10.1007/s00214-006-0240-z

Cited by 33 publications

(40 citation statements)

References 24 publications

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“…A sudden decrease of the binding energies per atom is found when adding an additional He atom to a snowball of regular structure. This is attributed to the newly-added atom pushing the already bound atoms away from the ion [12]. The number of atoms in the first shell is found as N 1 =10, 12 and 15 for Li + , Na + and K + , respectively, in perfect agreement with the work cited above [8].…”

Section: Introductionsupporting

confidence: 86%

“…The data for Na and K allow only the study of rather small snowballs of size up to Na + He 3 and K + He 10 . The results for the heavier alkali species permit comparison with variational Monte Carlo simulations [8,12]. The number of atoms observed in the first helium shell around Rb + and Cs + ions is found to agree with theoretical predictions.…”

Section: Discussionsupporting

confidence: 52%

“…4: We note a sudden drop in intensity after Cs + He 12 , hinting at another relatively stable structure in addition to Cs + He 16 . By means of Monte Carlo simulations of alkali-ion doped helium clusters, strong variations of the single-atom evaporative energy were found when adding an additional He atom to an ensemble of regularly arranged solvent atoms like the icosahedral K + He 12 [12]. These variations are explained by the large difference between the structures of the regular snowball Ak + He N and the subsequent cluster Ak + He N+1 : the additional He atom pushes out the regularly bound solvent atoms to a position further away from the ion, thus decreasing their binding energy.…”

Section: Resultsmentioning

confidence: 99%

“…The geometric structure of He shells in alkali-ion doped clusters was studied by quantum variational and diffusion Monte Carlo calculations [12,13,14]. By subsequently adding He atoms to the ion and computing the resulting cluster structure, marked differences in the Ak + He N geometry depending on N are found [13].…”

Section: Introductionmentioning

confidence: 99%

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Alkali-helium snowball complexes formed on helium nanodroplets

Müller

Mudrich

Stienkemeier

2009

The Journal of Chemical Physics

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We systematically investigate the formation and stability of snowballs formed by femtosecond photoionization of small alkali clusters bound to helium nanodroplets. For all studied alkali species Ak=(Na, K, Rb, Cs) we observe the formation of snowballs Ak + HeN when multiply doping the droplets. Fragmentation of clusters AkN upon ionization appears to enhance snowball formation. In the case of Na and Cs we also detect snowballs Ak + 2 HeN formed around Ak dimer ions. While the snowball progression for Na and K is limited to less than 11 helium atoms, the heavier atoms Rb and Cs feature wide distributions at least up to Ak + He41. Characteristic steps in the mass spectra of Cs-doped helium droplets are found at positions consistent with predictions on the closure of the 1 st shell of helium atoms around the Ak + ion based on variational Monte Carlo simulations.

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Section: Introductionsupporting

confidence: 86%

Section: Discussionsupporting

confidence: 52%

Section: Resultsmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

See 2 more Smart Citations

Alkali-helium snowball complexes formed on helium nanodroplets

Müller

Mudrich

Stienkemeier

2009

The Journal of Chemical Physics

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“…More details on these potentials and on the bound states supported by them can be found in ref. [27].…”

Section: The Potentialsmentioning

confidence: 99%

Bosonic helium droplets with cationic impurities: Onset of electrostriction and snowball effects from quantum calculations

Coccia

Bodo

Marinetti

et al. 2007

The Journal of Chemical Physics

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Variational MonteCarlo and Diffusion MonteCarlo calculations have been carried out for cations like Li + , Na + and K + as dopants of small helium clusters over a range of cluster sizes up to about 12 solvent atoms.The interaction has been modelled through a sum-of-potential picture that disregards higher order effects beyond atom-atom and atom-ion contributions. The latter were obtained from highly correlated ab-initio calculations over a broad range of interatomic distances.This study focuses on two of the most striking features of the microsolvation in a quantum solvent of a cationic dopant: electrostriction and snowball effects. They are here discussed in detail and in relation with the nanoscopic properties of the interaction forces at play within a fully quantum picture of the clusters features.

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Lessons from biomass planning at national and regional level in the EU

Kautto

Peck

2012

Biofuels Bioprod Bioref

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Action plans are an important tool for meeting the EU renewable energy targets. Planning of biomass at national level has recently shifted from biomass action plans to renewable energy action plans; the latter still assigning special attention to biomass. A number of regions have also developed or are developing biomass plans. However, even though such plans are to assist the delivery of bioenergy development, the processes leading to successful implementation are not well documented. Little is known of the roles and function of these plans. This paper examines factors underlying plans and draws lessons from the planning processes that appear to support successful bioenergy development. The work presents views of actors involved in biomass planning in eleven countries and nine regions in Europe with an analytical framework employed to condense and present interview content. The analysis shows that while planning processes at both national and regional levels have encountered barriers – most of them common to policy implementation in general, but some specific to bioenergy policy – the national level appears to have better dealt with such barriers. Stakeholder commitment, continuity of policy, and flexibility of planning guidelines and processes were found as some of the keys to successful implementation. While biomass plans were demonstrated to serve several roles, approaches looking beyond energy use are still limited. The work concludes that coordination of planning between jurisdictional levels needs to be strengthened and regional stimuli recognized at higher levels in order for biomass policy and planning to better achieve goals. © 2012 Society of Chemical Industry and John Wiley & Sons, Ltd

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Bosonic helium clusters doped by alkali metal cations: interaction forces and analysis of their most stable structures

Cited by 33 publications

References 24 publications

Alkali-helium snowball complexes formed on helium nanodroplets

Alkali-helium snowball complexes formed on helium nanodroplets

Bosonic helium droplets with cationic impurities: Onset of electrostriction and snowball effects from quantum calculations

Lessons from biomass planning at national and regional level in the EU

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