title: Rich stochastic dynamics of co-doped Er:Yb fluorescence upconversion nanoparticles in the presence of thermal, non-conservative, harmonic and optical forces.
abstract: The stochastic dynamics of individual co-doped Er:Yb upconversion nanoparticles (UCNP) were investigated from experiments and simulations. The UCNP were characterized by high-resolution scanning electron microscopy, dynamic light scattering, and zeta potential measurements. Single UCNP measurements were performed by fluorescence upconversion micro-spectroscopy and optical trapping. The mean-square displacement (MSD) from single UCNP exhibited a time-dependent diffusion coefficient which was compared with Brownian dynamics simulations of a viscoelastic model of harmonically bound spheres. Experimental time-dependent two-dimensional trajectories of individual UCNP revealed correlated two-dimensional nanoparticle motion. The measurements were compared with stochastic trajectories calculated in the presence of a non-conservative rotational force field. Overall, the complex interplay of UCNP adhesion, thermal fluctuations and optical forces led to a rich stochastic behavior of these nanoparticles.
authors.affiliation: Institute of Chemistry, University of Campinas, Campinas, SP, Brazil.
authors.forename: Rene A
authors.initials: RA
authors.lastname: Nome
authors.forename: Cecilia
authors.initials: C
authors.lastname: Sorbello
authors.forename: Matías
authors.initials: M
authors.lastname: Jobbágy
authors.forename: Beatriz C
authors.initials: BC
authors.lastname: Barja
authors.forename: Vitor
authors.initials: V
authors.lastname: Sanches
authors.forename: Joyce S
authors.initials: JS
authors.lastname: Cruz
authors.forename: Vinicius F
authors.initials: VF
authors.lastname: Aguiar