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Method for determining surface properties of microparticles

United States Patent

April 25, 2000
View the Complete Patent at the US Patent & Trademark Office
Second harmonic generation (SHG), sum frequency generation (SFG) and difference frequency generation (DFG) can be used for surface analysis or characterization of microparticles having a non-metallic surface feature. The microparticles can be centrosymmetric or such that non-metallic molecules of interest are centrosymmetrically distributed inside and outside the microparticles but not at the surface of the microparticles where the asymmetry aligns the molecules. The signal is quadratic in incident laser intensity or proportional to the product of two incident laser intensities for SFG, it is sharply peaked at the second harmonic wavelength, quadratic in the density of molecules adsorbed onto the microparticle surface, and linear in microparticles density. In medical or pharmacological applications, molecules of interest may be of drugs or toxins, for example.
Eisenthal; Kenneth B. (Ridgewood, NJ)
The Trustees of Columbia University in the City of New York (New York, NY)
09/ 066,280
April 24, 1998
The United States Government has certain rights in this invention under Awards No. CHE-93-13778 by the National Science Foundation and No. DE FG02 91ER14226 A006 by the Department of Energy.