Rich stochastic dynamics of co-doped Er:Yb fluorescence upconversion nanoparticles in the presence of thermal, nonconservative, harmonic and optical forces

RENE A. NOME; BEATRIZ C. BARJA; VINICIUS F. AGUIAR; CECILIA SORBELLO; MATÍAS JOBBAGY; VITOR SANCHES; JOYCE S. CRUZ

Methods and applications in fluorescence

IOP

Año: 2017 vol. 5 p. 1 - 6

The stochastic dynamics of individual co-doped Er:Yb upconversion nanoparticles (UCNP) wereinvestigated from experiments and simulations. The UCNP were characterized by high-resolutionscanning electron microscopy, dynamic light scattering, and zeta potential measurements. SingleUCNPmeasurements were performed by fluorescence upconversion micro-spectroscopy and optical trapping. The mean-square displacement (MSD) from singleUCNPexhibited 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 ofindividualUCNPrevealed correlated two-dimensional nanoparticle motion. The measurements werecompared with stochastic trajectories calculated in the presence of a non-conservative rotational forcefield. Overall, the complex interplay of UCNP adhesion, thermal fluctuations and optical forces led to a rich stochastic behavior of these nanoparticles.