AVS 47th International Symposium
    Material Characterization Tuesday Sessions
       Session MC-TuA

Paper MC-TuA1
Molecular Secondary Particle Emission from UHV-Prepared Molecular Overlayers

Tuesday, October 3, 2000, 2:00 pm, Room 207

Session: Quantitative Surface Analysis
Presenter: A. Schnieders, Physikalisches Institut der Universität Münster, Germany
Authors: A. Schnieders, Physikalisches Institut der Universität Münster, Germany
M. Schröder, Physikalisches Institut der Universität Münster, Germany
K. Rüschenschmidt, Physikalisches Institut der Universität Münster, Germany
A. Benninghoven, Physikalisches Institut der Universität Münster, Germany
H.F. Arlinghaus, Physikalisches Institut der Universität Münster, Germany
Correspondent: Click to Email
Secondary particle yields in organic SIMS and SNMS are not determined by the surface concentration of the respective particles only. Furthermore, the chemical interaction between substrate and adsorbed molecules determines the secondary particle emission, in particular from the first molecular monolayer. Especially the intrinsic ionization but also the fragmentation of the sputtered particles is influenced by this so-called matrix effect. Additionally, secondary particle emission depends on primary ion properties such as species or energy. In continuation of recent investigations, mainly focussing on the sputter process, we used UHV-prepared molecular overlayers of adenine and alanine prepared on liquid-nitrogen cooled substrates. We extended our investigations to a broader range of substrate/molecule combinations to determine the influence of the matrix effect. The flux of sputtered secondary neutrals and secondary ions in dependence on the layer thickness was continuously monitored under static sputtering conditions during overlayer formation. The detection of the sputtered neutrals was achieved by efficient laser postionization. As substrates we chose Au, Ag, Cu, Ni, Si, Al and C surfaces to cover different types of surface chemistry. A comparison between secondary ion and secondary neutral emissions showed a distinct ionization matrix effect depending on the respective substrate material for @beta@-alanine but not for adenine.