Thermal diffusion of Kerr nanobead under a tightly-focused laser beam

• Main Authors: Pobre, Romeric F., Saloma, C. A.
• Format: text
• Published: Animo Repository 2007
• Subjects: Nanoparticles; Brownian movements; Langevin equations; Physics
• Online Access: https://animorepository.dlsu.edu.ph/faculty_research/1702; https://animorepository.dlsu.edu.ph/context/faculty_research/article/2701/type/native/viewcontent
• Institution: De La Salle University

We investigated thermal diffusion of Kerr nanobead under a tightly-focused laser beam. Kerr nanobeads refer to small beads whose refractive index is governed by n2=n2(0)+n2(1)│E*E│; where n2(0)is the linear component of the refractive index, n2(1)is the nonlinear component, and │E*E│ is the intensity of linearly-polarized laser beam. Thermal fluctuation of the surrounding medium (water in this case) of the optical trap is apparent when the bead radius is appreciably small near the nanometric order. Theoretical model of three dimensional motion of Kerr nanobead under water appropriates the use of Langevin equation to account for both Brownian force and radiation force experienced by a Kerrnanobead. Diffusion of 30 nm sized dielectric bead requires 3.1 kbT (T=300K) of total energy to confine a Kerr nanobead within 0.4 um from the central optical trap based from the probability density calculations. With this confinement, Kerr nanobead can be an alternative probe handler for photonic force microscope imaging hollow microbiological structures. © International Federation for Medical and Biological Engineering 2007.