Eur. Phys. J. D 22, 75-79 (2003)
https://doi.org/10.1140/epjd/e2002-00220-2

Electron capture and loss by protonated peptides and proteins in collisions with C₆₀ and Na

¹ Department of Physics and Astronomy, University of Aarhus, 8000 Aarhus C, Denmark
² Physics Department, Stockholm University, SCFAB, 106 91 Stockholm, Sweden

Corresponding author: ^a hvelplun@phys.au.dk

Received: 23 May 2002
Published online: 6 November 2002

Abstract

Electron capture and loss cross-sections have been measured for collisions between fast multiply charged peptide and protein ions [ M+nH] and Na or C₆₀. The ions were produced in an electrospray ion source (ESI) and accelerated to an energy of  keV. We find that the size of the cross-sections depend strongly on molecule size, ionization energy and projectile charge state n. For multiply charged ubiquitin projectiles, the cross-sections for electron capture are found to be several times larger with a Na target than with a C₆₀ target. This observation is qualitatively explained by means of an over-the-barrier model for electron transfer using metal-sphere descriptions for the electronic responses of the collision partners.