Anharmonic aerosol particle dynamics at Mie resonances in modulated counter-propagating optical tweezers

Abstract

We analyze the trapping potential of a setup of counter propagating optical tweezers and test the validity of the harmonic approximation in the dimension parallel to the trapping beam axis. While the dynamics of spherical droplets is very well described by a harmonic oscillator, we find that the trapping potential changes drastically for particles at resonance with the trapping laser, at so called Mie resonances. Our findings are discussed with regard to possible origins of this phenomenon.

Hygroscopic growth of single atmospheric sea salt aerosol particles from mass measurement in an optical trap

“…This additional delay leads to an articial increase in the phase 4 in the harmonic oscillator model and thus to an increase of the mass and density. This phenomenon is prevalent in CPTs with parallel polarized trapping beams, 30 and is therefore not signicant in this work where we use perpendicular polarized beams, although a residual artefact of 2-3% cannot be ruled out.…”