FRET - Based technique for the characterization of contour lines

Catalysts that are made of composite particles may comprise several compounds, where each compound utilizes its own specific properties, thus providing synergistic effects that cannot be found when the constituents are used separately. Developing and quality control of such particles require measuring the shape of the domains and the length of the contact line between domains made from different compounds. In what follows, the feasibility of using Fluorescence Resonance Energy Transfer (FRET) in order to gain information on the length of contour lines between neighboring domains is demonstrated. The principle of the method is to selectively adsorb the donor on one type of domain while selectively adsorbing the acceptor on the second type of domain. The requirement for a short distance between the acceptor dye molecule and the donor dye molecule in order to obtain fluorescence is then translated into a linear dependence between the emission intensity and the contour line length. This facilitates, upon using calibrated standards, the calculation of the average length of the contour between domains.