화학공학소재연구정보센터
Journal of Physical Chemistry, Vol.98, No.1, 245-251, 1994
Energy Disposal and Target Effects in Hyperthermal Collisions of Ferrocene Molecular-Ions at Surfaces
Ferrocene molecular ions undergo inelastic collisions at Si(100) and alkanethiol self-assembled monolayer surfaces (SAMs). Dissociation of the activated projectile follows its recoil from the surface; viz., surface-induced dissociation (SID) occurs by a two-step mechanism, and the fragmentation pattern is independent of the nature of the surface. On the other hand, the SID efficiency for collisions at the SAM surfaces is much greater than that for the Si(100) single-crystal surface as a result of a decrease in neutralization at the organic surfaces. The fragmentation pathways of a ferrocene molecular ion are elucidated as a function of collision energy and presented as energy-resolved mass spectra (ERMS) on the SAM and Si(100) surfaces. Translational to vibrational energy partitioning is similar for Si(100) and a hydrocarbon surface (ca. 13%) but greater for a fluorocarbon surface (ca. 20%). The ferrocene molecular ion displays a high SID efficiency (total scattered ion yield) on the organic surfaces compared to other common projectile ions due to its low ionization energy. Because charge exchange between the projectile molecular ion and the surface is minimized, ferrocene does not undergo ion/surface reactions.