The effect of initial internal energy on the extent of surface-induced fragmentation was investigated in a tandem mass spectrometer for CH3-, and CH4- ions prepared in different ion sources. The different initial internal energy content had a considerable effect on the extent of fragmentation of the surface-excited projectile ions: ions from a Nier source with a large amount of initial internal energy fragmented at much lower collision energies than internally relaxed projectile ions from a Colutron source. A quantitative estimation of this effect showed that the initial internal energy content of the projectile ions was entirely preserved in the projectile ion during the ion/surface collision. (C) 2003 Elsevier B.V. All rights reserved.