title: Measurement of the index of refraction of single microparticles.
abstract: The refractive index of single microparticles is derived from precise measurement and rigorous modeling of the stiffness of a laser trap. We demonstrate the method for particles of four different materials with diameters from 1.6 to 5.2 microm and achieve an accuracy of better than 1%. The method greatly contributes as a new characterization technique because it works best under conditions (small particle size, polydispersion) where other methods, such as absorption spectroscopy, start to fail. Particles need not be transferred to a particular fluid, which prevents particle degradation or alteration common in index matching techniques. Our results also show that advanced modeling of laser traps accurately reproduces experimental reality.
authors.affiliation: Centre for Biophotonics and Laser Science, School of Physical Sciences, The University of Queensland, Brisbane QLD 4072, Australia.
authors.forename: Gregor
authors.initials: G
authors.lastname: Knöner
authors.forename: Simon
authors.initials: S
authors.lastname: Parkin
authors.forename: Timo A
authors.initials: TA
authors.lastname: Nieminen
authors.forename: Norman R
authors.initials: NR
authors.lastname: Heckenberg
authors.forename: Halina
authors.initials: H
authors.lastname: Rubinsztein-Dunlop
mesh_terms: D008954:Models, Biological; D008956:Models, Chemical; D008962:Models, Theoretical; D010316:Particle Size; D012031:Refractometry