AVS 49th International Symposium
    Applied Surface Science Monday Sessions
       Session AS-MoM

Paper AS-MoM2
G-SIMS - Molecular Structure

Monday, November 4, 2002, 8:40 am, Room C-106

Session: SIMS
Presenter: I.S. Gilmore, National Physical Laboratory, UK
Authors: I.S. Gilmore, National Physical Laboratory, UK
M.P. Seah, National Physical Laboratory, UK
Correspondent: Click to Email
G-SIMS or gentle SIMS has already been demonstrated to provide a straightforward way to simplify static SIMS spectra.@footnote 1,2@ These spectra are composed of parent fragment ions amongst a large number of high intensity degradation products. The fragmentation is quantified in terms of the partition functions of the fragments emitted from a surface plasma with effective temperature, T@sub p@. It is found that fragmentation is least for high mass incident ions at low energies. By extrapolation of the data to low T@sub p@, a new spectroscopy, known as gentle-SIMS or G-SIMS is formed. The significant peaks in the G-SIMS spectra are those peaks which would be emitted as a result of an ion impact that generates a surface plasma of very low T@sub p@ and thus have little post-emission rearrangement or fragmentation. Those peaks are, thus, directly characteristic of the material without rearrangement and enable direct interpretation and identification. G-SIMS has been successfully tested on a range of polymers, molecules and complex organics.@footnote 3@ G-SIMS not only provides the parent molecule mass, and hence composition in terms of numbers of C,H,O,N etc atoms, but is also allows the molecular structure to be evaluated. Current work explores the re-building of parent molecules using the fragmentation pathways which are mapped out as T@sub p@ is varied. This new dimension to the technique has significant potential information not previously obtainable in static SIMS. G-SIMS-MS has some of the attributes of MS-MS. These effects and the use of G-SIMS with mixtures will be discussed. @FootnoteText@ @footnote 1@I S Gilmore and M P Seah, Appl. Surf. Sci. 161 (2000) 465. @footnote 2@I S Gilmore and M P Seah, SIMS XIII proc, Appl. Surf. Sci. in the press. @footnote 3@I S Gilmore and M P Seah, Appl. Surf. Sci. 187 (2002) 89.