Electronic structure of K<i>x</i>C60− in the gas phase

Wang, Lai‐Sheng; Cheshnovsky, Ori; Smalley, R. E.; Carpenter, J. P.; Hwu, Shiou‐Jyh

doi:10.1063/1.461853

Cited by 40 publications

(20 citation statements)

References 32 publications

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“…Photoelectron spectra of C 60 K n (n 3) indicate essentially ionic bonding [46]. Spectra of C 60 Na − n (n 12), however, suggest that sodium atoms on C 60 tend to form trimers or perhaps tetrahedral tetramers rather than uniformly covering C 60 as expected if Coulomb repulsion between the adsorbed cations would prevail [47][48][49], in agreement with the theoretical work mentioned above [37].…”

Section: Discussionsupporting

confidence: 76%

Adsorption of sodium and cesium on aggregates of C60

et al. 2016

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Abstract.We explore the formation of C60 sodium and C60 cesium complexes in superfluid helium nanodroplets. Anomalies in mass spectra of these doped droplets reveal anomalies in the stability of ions. (C60)mCs + n ions (m 6) are particularly abundant if they contain n = 6m + 1 cesium atoms; (C60)mCs 2+ n dications (m 3 or 5) are abundant if n = 6m + 2. These findings are consistent with the notion that alkali metal atoms (A) transfer their valence electrons into the three-fold degenerate lowest unoccupied orbital of C60, resulting in particularly stable C60A6 building blocks. However, (C60)4Cs 2+ n dications display an entirely different pattern; instead of an expected anomaly at n = 6 × 4 + 2 = 26 we observe a strong odd-even alternation starting at n = 6. Also surprising is the effect of adding one H2O or CO2 molecule to (C60)mCsn mono-or dications; anomalies shift by two units as if the impurity were acting as an acceptor for two valence electrons from the alkali metal atoms.

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Section: Discussionsupporting

confidence: 76%

Adsorption of sodium and cesium on aggregates of C60

et al. 2016

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“…[17][18][19][20][21][22][23][24][25][26][27][28][29] Coverage of fullerenes with semiconductor atoms or clusters has also been investigated. 30,31 For alkaline earth materials it is now commonly accepted that many atoms homogeneously surround the C 60 molecule in spherically centred shells.…”

Section: Introductionmentioning

confidence: 99%

Nucleation of a sodium droplet onC60

et al. 2003

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We investigate theoretically the progressive coating of C60 by several sodium atoms. Density functional calculations using a nonlocal functional are performed for NaC60 and Na2C60 in various configurations. These data are used to construct an empirical atomistic model in order to treat larger sizes in a statistical and dynamical context. Fluctuating charges are incorporated to account for charge transfer between sodium and carbon atoms. By performing systematic global optimization in the size range 1 ≤ n ≤ 30, we find that NanC60 is homogeneously coated at small sizes, and that a growing droplet is formed above n ≥ 8. The separate effects of single ionization and thermalization are also considered, as well as the changes due to a strong external electric field. The present results are discussed in the light of various experimental data.

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“…Sodium-C 60 compounds have also received much attention [3,4]. More recently, several groups investigated experimentally the gas phase properties of exohedral alkali-C 60 compounds [5,6,7], to further predict the solid state of alkali-doped fullerite.Using mass spectrometry, Martin and coworkers [6] inferred from the most stable "magic numbers" that sodium covers the C 60 molecule in a continuous and homogeneous fashion, and that metallic bonding starts above 6 metal atoms. Palpant and coworkers [7] deduced from photoelectron spectroscopy measurements that coating proceeds by trimers units rather than single atoms.…”

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Wetting-to-Nonwetting Transition in Metal-CoatedC60

et al. 2003

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Based on ab initio and density-functional theory calculations, an empirical potential is proposed to model the interaction between a fullerene molecule and many sodium atoms. This model predicts homogeneous coverage of C60 below 8 Na atoms, and a progressive droplet formation above this size. The effects of ionization, temperature, and external electric field indicate that the various, and apparently contradictory, experimental results can indeed be put into agreement. PACS numbers: 61.48.+c,36.40.Qv,34.70.+e Fullerene molecules are now commonly used as building blocks of complex materials having unusual physical and chemical properties [1]. The possibilities offered by molecules such as C 60 or C 70 in terms of electric or optical devices have laid ground for the rapidly expanding nanotechnology area. The interaction between fullerenes and alkali atoms has attracted a lot of attention after the discovery of superconductivity in the K 3 C 60 solid [2]. Sodium-C 60 compounds have also received much attention [3,4]. More recently, several groups investigated experimentally the gas phase properties of exohedral alkali-C 60 compounds [5,6,7], to further predict the solid state of alkali-doped fullerite.Using mass spectrometry, Martin and coworkers [6] inferred from the most stable "magic numbers" that sodium covers the C 60 molecule in a continuous and homogeneous fashion, and that metallic bonding starts above 6 metal atoms. Palpant and coworkers [7] deduced from photoelectron spectroscopy measurements that coating proceeds by trimers units rather than single atoms. They also estimated that metallic bonding only appears at n = 13 sodium atoms. Very recently, Dugourd and coworkers [8] measured the electric polarizability of Na n C 60 clusters in the range 1 ≤ n ≤ 34. They concluded that a sodium droplet is formed on the surface of the fullerene. These apparent contradictory results are surprising, as far as they rely on similar experimental conditions but different interpretations.The situation is in fact even more intricate due to the variety of theoretical conclusions on the very same systems [9,10,11,12]. With the exception of the study by Rubio and coworkers [9], which assumes complete wetting of C 60 by sodium in a continuous two-shell jellium description, the electronic structure calculations by Hira and Ray [10,11], and by Hamamoto et al.[12] reach different conclusions as to whether the Na 2 molecule remains as a dimer or dissociates into atoms, which locate on opposite sides of C 60 . At the unrestricted HartreeFock level, Hira and Ray find that charge transfer is negligible in NaC 60 , in apparent contradiction with experiments [7,8], and also that Na 2 remains as a dimer loosely bound to C 60 . On the other hand, the more realistic density-functional theory (DFT) calculations performed by Hamamoto and coworkers [12] at the local density approximation level tend to favor regular coating, preferentially by trimers, in agreement with the picture of Palpant et al. [7]. However, all these ab initio investig...

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Electronic structure of KxC60− in the gas phase

Cited by 40 publications

References 32 publications

Adsorption of sodium and cesium on aggregates of C60

Adsorption of sodium and cesium on aggregates of C60

Nucleation of a sodium droplet onC60

Wetting-to-Nonwetting Transition in Metal-CoatedC60

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