title: Ensemble method to measure the potential energy of nanoparticles in an optical trap.
abstract: A method is described for measuring the potential energy of nanoparticles in an optical trap by trapping an ensemble of particles with a focused laser beam. The force balance between repulsive osmotic and confining gradient-force pressures determines the single-particle trapping potential independent of interactions between the particles. The ensemble nature of the measurement permits evaluation of single-particle trapping energies much smaller than kBT. Energies obtained by this method are compared to those of single-particle methods as well as to theoretical calculations based on classical electromagnetic optics.
authors.affiliation: Department of Physics, Lehigh University, Bethlehem, Pennsylvania 18015, USA.
authors.forename: Joseph
authors.initials: J
authors.lastname: Junio
authors.forename: Jack
authors.initials: J
authors.lastname: Ng
authors.forename: Joel A
authors.initials: JA
authors.lastname: Cohen
authors.forename: Zhifang
authors.initials: Z
authors.lastname: Lin
authors.forename: H Daniel
authors.initials: HD
authors.lastname: Ou-Yang
mesh_terms: D053758:Nanoparticles / Q000737:chemistry*; D052898:Optical Tweezers; D010316:Particle Size; D011312:Pressure