AVS 47th International Symposium
    Material Characterization Wednesday Sessions
       Session MC-WeM

Invited Paper MC-WeM4
Chemometric Approaches to the Analysis of Surface Chemical Image Data

Wednesday, October 4, 2000, 9:20 am, Room 207

Session: Methods of Data Analysis
Presenter: K.G. Lloyd, E.I. DuPont de Nemours and Co., Inc.
Authors: K.G. Lloyd, E.I. DuPont de Nemours and Co., Inc.
D.J. Walls, E.I. DuPont de Nemours and Co., Inc.
G.S. Blackman, E.I. DuPont de Nemours and Co., Inc.
N. Tassi, E.I. DuPont de Nemours and Co., Inc.
J.P. Wyre, E.I. DuPont de Nemours and Co., Inc.
Correspondent: Click to Email
ToF-SIMS (Time-of-Flight Secondary Ion Mass Spectrometry) provides a mass spectrum from the topmost 10-20 Angstroms of a sample, which is in effect a composite of mass spectra from all species that co-exist at the surface. This makes it difficult to track surface compositional changes in multi-component systems, especially when molecular ions are not observed. In the area of chemical imaging, the generally comparable secondary ion yields from most organic species result in little/no contrast observed in total ion images of organic/polymeric samples. Recent advances in technology now allow us to acquire an entire spectrum at each image pixel. This approach results in a huge amount of data and requires an objective, robust, and automated means of data analysis. For all these reasons, chemometric methods such as Principal Components Analysis (PCA) and Partial Least Squares (PLS) have come to play an important role in surface characterization, not just for ToF-SIMS, but for all the surface chemical imaging techniques. We have had considerable success with the use of chemometric approaches for visualizing chemical contrast in chemical images from ToF-SIMS, Raman, and ESCA data. Our work has focused on how to take advantage of the complementary information content of these data sets. This talk will present examples of how we are using these multivariate statistical techniques today, and how we might expect to use them in the future.