Optical reflectance imaging of dye-saturated, c-oriented MFI membranes is employed for the first time as an in situ technique to conclusively identify the fluorescing features imaged simultaneously through fluorescence confocal optical microscopy (FCOM). For relatively thick (10-25 μm), well-oriented membranes, the reflectance image reveals the crystalline grains at the membrane surface. It provides low-resolution insight reminiscent of SEM, and augments FCOM techniques enabling direct correlation of the fluorescing regions of the membrane with the peripheries of the crystal grains (i.e., grain boundaries). Direct comparison of reflectance, fluorescence, and SEM images of an identical region of the membrane, rather than qualitative comparison of images from different membranes, conclusively confirms that molecular probes (dyes) of maximum diameter greater than the MFI pore dimensions access grain boundaries within the polycrystalline MFI membranes.
Bibliographical noteFunding Information:
This work is supported in part by NSF/ITR DMS-0219211, CTS-0312117, and CTS-0091406. In addition, the authors express their gratitude for the imaging expertise shared by Dr. Kirk J. Czymmek, Associate Professor in the Department of Biological Sciences and Director of the Delaware Biotechnology Institute Bio-Imaging Center at the University of Delaware.
Copyright 2008 Elsevier B.V., All rights reserved.
- Confocal microscopy
- Grain boundaries
- Reflectance imaging
- Zeolite membranes