Microscopic Measurement of Diffusion
In order to engineer materials with controlled diffusive properties, we need to be able to measure the diffusive process in situ. Ideally, we would like a technique that provides molecular information with resolution on a microscopic scale, that is non destructive of the samples, and can be set up and used on a laboratory bench top with a minimum of time and effort involved in sample preparation. Raman microprobe spectroscopy is an ideal candidate for this type of studies. Use of visible light combined with a confocal microscope provides a probe with spatial resolution of a micron or better, and coupling of such a microscope to a modern Raman spectrometer equipped with holographic notch filters and CCD multi channel detectors allows rapid acquisition of Raman spectra which can be correlated with the chemical state of the species and its physical environment.
