Diffusion optical interference microscopy

Karge HG, Karger J (2008) Application of IR Spectroscopy, IR Microscopy and Optical Interference Microscopy on Diffusion in Zeolites, in this volimie... 

Karger et al. [18,19] and later on developed by Schemmert [20] and Karger et al. [21] to a very sophisticated method, when employing optical interference microscopy (IFM). The design of the experiments using interference microscopy for diffusion studies (DIFM), the data acquisition through this type of experiment, and the evaluation of selected data obtained by DIFM are described in Sect. 3. 

The evidence from these methods suggests that lower values of diffusion constants are obtained from methods which are sensitive to factors important over longer distances, and so indicate that defects can have a controlling effect in diffusional rates. This is shown clearly in interference optical microscopy studies of methanol adsorbing into crystals of CrAPO-5, where the hexagonal prismatic crystals are found to possess large sectors that are inaccessible to adsorbate molecules. The existence of barriers to molecular adsorbates at the external surfaces of zeolites has also frequently been reported and can be visualised directly by comparative interference microscopy on as-prepared and also surface-etched ZSM-5 crystals. ... 

To understand the release mechanism, cryomicrotomy was used to slice 10 m-thick sections throughout the matrices. Viewed under an optical microscope, polymer films cast without proteins appeared as nonporous sheets. Matrices cast with proteins and sectioned prior to release displayed areas of either polymer or protein. Matrices initially cast with proteins and released to exhaustion (e.g., greater than 5 months) appeared as porous films. Pores with diameters as large as 100 /xm, the size of the protein particles, were observed. The structures visualized were also confirmed by Nomarski (differential interference contrast microscopy). It appeared that although pure polymer films were impermeable to macromolecules (2), molecules incorporated in the matrix dissolved once water penetrated the matrix and were then able to diffuse to the surface through pores created as the particles of molecules dissolved. Scanning electron microscopy showed that the pores were interconnected (7). 

Interference optical microscopy is a recent and highly attractive experimental method to study diffusion processes on an intermediate length seale of microns as a single crystal is exposed to molecules in the gas phase... 

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