A Comparison of Non-destructive and Non-invasive material depth profiling using FT-Raman fiber optics and microspectroscopy

摘要

The purpose of this study is to obtain chemical information from complex materials at different depths, without destroying the structure, by using a FT-Raman fiber-optic probe. This concept combines the fiexibility of a fiber-optic probe with depth profiling capabilities similar to those of a confocal microscopy. The fact heat the numerical aperture of the probe is lower than in microscope objectives explains the improvement in the range of depth penetration, from micrometers to millimeters, as well as the loss observed in depth resolution. Since the design of the filtered probe is based on confocal optics, it is possible to guide the focus through 6-7 m thick material thereby providing detailed chemical information on different layers at different depths. The confocal properties of the fiber optic probe have been characterized by profiling a 6 micrometer polystyrene film, and comparing the results with those obtained on a FT-Raman microscope. We will present results of molecular depth profiling studies on multi-layer sheets of different polymers, including the determination of chromatic shift, layer thickness nad polymer chemistry. Applicatiosn on other material depth profiling will also be discussed.