Probing the presence and absence of metal-fullerene electron transfer reactions in helium nanodroplets by deflection measurements

• Published in: Physical chemistry chemical physics : PCCP Vol. 24; no. 17; pp. 1378 - 1383
• Main Authors: Niman, John W, Kamerin, Benjamin S, Villers, Thomas H, Linker, Thomas M, Nakano, Aiichiro, Kresin, Vitaly V
• Format: Journal Article
• Language: English
• Published: England Royal Society of Chemistry 04.05.2022
• Subjects: Charge transfer; Deflection; Dipole moments; Electric dipoles; Electron transfer; Fluids; Fullerenes; Helium; Liquid helium; Rare earth elements; Superfluidity
• ISSN: 1463-9076; 1463-9084
• DOI: 10.1039/d2cp00751g

Metal-fullerene compounds are characterized by significant electron transfer to the fullerene cage, giving rise to an electric dipole moment. We use the method of electrostatic beam deflection to verify whether such reactions take place within superfluid helium nanodroplets between an embedded C 60 molecule and either alkali (heliophobic) or rare-earth (heliophilic) atoms. The two cases lead to distinctly different outcomes: C 60 Na n ( n = 1-4) display no discernable dipole moment, while C 60 Yb is strongly polar. This suggests that the fullerene and small alkali clusters fail to form a charge-transfer bond in the helium matrix despite their strong van der Waals attraction. The C 60 Yb dipole moment, on the other hand, is in agreement with the value expected for an ionic complex. Electrostatic deflection of a beam of helium nanodroplets containing fullerenes and metal atoms reveals whether these dopants are able to form charge-transfer complexes.