Adsorption of sodium and cesium on aggregates of C60

Abstract

Abstract: We explore the formation of C60sodium and C60cesium complexes in superfluid helium nanodroplets.Anomalies in mass spectra of these doped droplets reveal anomalies in the stability ofions. (C60)mCs+nions (m ≤6) are particularly abundant if they containn = 6m +1 cesium atoms; (C60)mCs2+ndications (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 unoccupiedorbital of C60,resulting in particularly stable C60A6building blocks. However, (C60)4CsCs2+ndications display an entirely different pattern;instead of an expected anomaly at n = 6 × 4 + 2 = 26 we observe a strong odd-evenalternation starting at n =6. Also surprising is the effect of adding one H2O or CO2molecule to (C60)mCsnmono- or dications; anomalies shiftby two units as if the impurity were acting as an acceptor for two valence electrons fromthe alkali metal atoms. Graphical abstract: [Figure not available: see fulltext.]