Negative ion formation mechanism and velocity distribution in laser desorption/ionization of C60
University of IcelandDepartment of Chemistry, and Science
2 Interdisciplinary Nanoscience Center (iNANO), Department of Physics and Astronomy, University of Aarhus, Ny Munkegade, 8000 Aarhus C, Denmark
Received in final form: 17 January 2012
Published online: 27 March 2012
In UV laser desorption/ionization (LDI) of C60, both molecular cations and anions are formed. While the C60+ formation has been discussed in a number of studies and is fairly well understood, the C60- formation has received less attention. Here, we present measurements of C60- and C60+ formation and its fluence dependence in UV-LDI of C60 from both metallic and non-metallic substrates. The data show clearly that the C60- formation is coupled to the C60+ formation, indicating that C60- is predominantly formed through electron transfer early in the expanding laser desorption plume. The velocity distribution of desorbed C60- ions was also determined and was found to be best described by two Maxwell-Boltzmann distributions with superimposed stream velocities.
Key words: Topical issue: Electron/Positron Collision. Guest editors: Michael Brunger, Anne Lafosse, Gaetana Laricchia, Paulo Limao-Vieira and Nigel Mason
© EDP Sciences, Società Italiana di Fisica and Springer-Verlag 2012