IN-SITU MEASUREMENT OF ADHESION FORCE BETWEEN A SINGLE MICROPARTICLE AND A SURFACE USING RADIATION PRESSURE OF PULSED-LASER LIGHT

A new method is proposed for analyzing the adhesion force between a si ngle microparticle and a solid surface in air. The method is based on the mu N radiation force that is exerted on a particle by nanosecond p ulsed laser light, which pulls a particle from a transparent solid sur face against the adhesion force. The strength of the force is determin ed on the basis of the Mie scattering theory with the critical laser i ntensity at which the radiation pressure and the adhesion force are ba lanced. This optical force measurement has the advantages of no mechan ical contact, of applicability to micro similar to nanometer-sized par ticles and of causing no perturbations on the physical and chemical co nditions of a sample. The high potential of this method is clearly dem onstrated in the analysis of the adhesion force between polymer latexe s and glass surfaces.