title: Quantifying electron transfer during hyperthermal scattering of C60+ from Au(111) and n-alkylthiol self-assembled monolayers.
abstract: A tandem time-of-flight mass spectrometer with an intermediate surface was used to quantify electron transfer during glancing incidence scattering of hyperthermal C(60) (+) (E(coll)=250-500 eV, theta(in)=75 degrees ) from (i) self-assembled monolayers of n-alkylthiols on gold (of various chain lengths), (ii) partly fluorinated alkylthiols on gold, as well as (iii) clean gold surfaces. Self-assembled monolayers (SAMs) behave as insulating layers with their thicknesses determining the electron tunneling probability during collision. Correspondingly, a roughly exponential dependence of the neutralization probability on the chain length n was found. A pronounced dependence of the neutral yield on the primary beam kinetic energy indicates that dynamic SAM deformation and associated projectile penetration depth also play a role in determining electron transfer efficiency. Results are consistent with the molecular deformability of SAMs as determined with other experimental methods.
authors.affiliation: Lehrstuhl für die Physikalische Chemie Mikroskopischer Systeme, Institut für Physikalische Chemie, Universität Karlsruhe, Karlsruhe, Germany.
authors.forename: Stefan-Sven
authors.initials: SS
authors.lastname: Jester
authors.forename: Patrick
authors.initials: P
authors.lastname: Weis
authors.forename: Matthias
authors.initials: M
authors.lastname: Hillenkamp
authors.forename: Oli T
authors.initials: OT
authors.lastname: Ehrler
authors.forename: Artur
authors.initials: A
authors.lastname: Böttcher
authors.forename: Manfred M
authors.initials: MM
authors.lastname: Kappes