Abstract
We show that fourth-order dispersion functions of solid-phase polymers can be determined by multicolor optical diffraction. Electrodynamically trapped microparticles of polyethylene glycol with different molecular weights were probed by two-dimensional optical diffraction with four different laser wavelengths (632.8, 514.5, 488.0, and 457.9 nm); subsequent Mie analysis of one-dimensional scattering patterns yielded size and refractive index (both real and imaginary parts). Using a single wavelength as a size reference, the nonlinear dependence of the refractive index of solid (nonevaporating) polymer microparticles was determined by finding the refractive index for a given wavelength that best matched a Mie calculation subject to the reference size constraint. The experimentally determined refractive index values were fit to a standard fourth-order Cauchy function to obtain values for n0, n1, and n2.
Original language | English |
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Pages (from-to) | 2515-2517 |
Number of pages | 3 |
Journal | Applied Physics Letters |
Volume | 77 |
Issue number | 16 |
DOIs | |
State | Published - Oct 16 2000 |