Adsorption of sodium and cesium on aggregates of C-60

作者：Harnisch Martina; Daxner Matthias; Scheier Paul; Echt Olof

来源：European Physical Journal D, 2016, 70(9): 192.

DOI：10.1140/epjd/e2016-70438-4

We explore the formation of C-60 sodium and C-60 cesium complexes in superfluid helium nano-droplets. Anomalies in mass spectra of these doped droplets reveal anomalies in the stability of ions. (C-60)(m)Cs-n(+) ions (m <= 6) are particularly abundant if they contain n = 6m + 1 cesium atoms; (C-60)(m)Cs-n(2+) 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 C-60, resulting in particularly stable C(60)A(6) building blocks. However, (C-60)4Cs(n)(2+) dications display an entirely different pattern; instead of an expected anomaly at n = 6 x 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 (C-60)(m)Cs-n 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.

• 出版日期2016-9-15