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. 2019 Mar 28;123(12):2379-2386.
doi: 10.1021/acs.jpca.8b12262. Epub 2019 Mar 11.

Magic Numbers for the Photoelectron Anisotropy in Li-Doped Dimethyl Ether Clusters

Jonathan V Barnes  1 , Bruce L Yoder  1 , Ruth Signorell  1
Affiliations

Magic Numbers for the Photoelectron Anisotropy in Li-Doped Dimethyl Ether Clusters

Jonathan V Barnes et al. J Phys Chem A. .

Abstract

Photoelectron velocity map imaging of Li(CH3OCH3) n clusters (1 ≤ n ≤ 175) is used to search for magic numbers related to the photoelectron anisotropy. Comparison with density functional calculations reveals magic numbers at n = 4, 5, and 6, resulting from the symmetric charge distribution with high s-character of the highest occupied molecular orbital. Since each of these three cluster sizes correspond to the completion of a first coordination shell, they can be considered as "isomeric motifs of the first coordination shell". Differences in the photoelectron anisotropy, the vertical ionization energies and the enthalpies of vaporization between Li(CH3OCH3) n and Na(CH3OCH3) n can be rationalized in terms of differences in their solvation shells, atomic ionization energies, polarizabilities, metal-oxygen bonds, ligand-ligand interactions and by cooperative effects.

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Conflict of interest statement

The authors declare no competing financial interest.

Figures

Figure 1
Figure 1
Inset: reconstructed photoelectron images of Li(CH3OCH3)n clusters with n = 1–4 solvent molecules. Full black line: β-trace as a function of the electron binding energy (eBE). Dotted red line: Photoelectron spectrum as a function of eBE.
Figure 2
Figure 2
(a) Photoelectron spectra of Li(CH3OCH3)n clusters as a function of eBE. Dashed black line: n = 1–4. Dotted green line: ⟨n⟩ = 20. Full red line: ⟨n⟩ = 63. (b) Mass spectrum for n = 1–4. (c) Mass spectrum for ⟨n⟩ = 63.
Figure 3
Figure 3
Properties of Li(CH3OCH3)n clusters as a function of the number of solvent molecules n: (a) calculated β-parameters, (b) calculated enthalpies of vaporization Hvap, (c) calculated vertical ionization energies IEvert, (d) calculated dipole moments, (e) experimental β-parameters, (f) representative mass spectrum for ⟨n⟩ = 20, and (g) experimental ionization energies determined at the maximum of the photoelectron bands IEmax. For the calculations, the open circles connected by lines are the values for the energetically lowest isomers. For other isomers see Table S2 in the Supporting Information.
Figure 4
Figure 4
Comparison of Li(CH3OCH3)n (open circles) and Na(CH3OCH3)n (open triangles) cluster data. (a) Calculated enthalpies of vaporization Hvap. (b) Experimental ionization energies IEmax. (c) Experimental β-parameters.
Figure 5
Figure 5
Isosurfaces of the HOMO of the most stable isomers of (a) the Li(CH3OCH3)4 cluster, (b) the Li(CH3OCH3)5 cluster, and (c) the Li(CH3OCH3)6 cluster. The calculated s-character of these HOMO are 100%, 95%, and 100%, respectively.
See this image and copyright information in PMC

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