Radiation pressure exerted on particles can be used as an optical spring for characterizing physical and chemical interactions between particles and solid surfaces and foranalyzing atomic and molecular forces such as van der Waals and electric-double-layer forces. A three-dimensional potential produced by radiation pressure of a focused laser beam is observed on the basis of the Boltzmann distribution for thermal energy of an optically-trapped particle. The surface charge density of a single

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... ticle can be analyzed by the balance of radiation pressure with an electrostatic force that acts on the particle placed between microelectrodes. A noncontact and nondestructive technique for measuring an adhesion force between a particle and a solid surface is proposed, which utilizes strong radiation pressure of a nanosecond pulsed laser. Applications of these methods are also discussed.