Probe particle collisions and measurement accuracy of diffusion coefficient via Brownian motion

  • Adrielle Theresa De Lara Cusi National Institute of Physics, University of the Philippines Diliman
  • Giovanni Tapang National Institute of Physics, University of the Philippines Diliman
  • Caesar Saloma National Institute of Physics, University of the Philippines Diliman

Abstract

We determine the relationship between the accuracy of the measured diffusion coefficient and the number of elastic probe particle collisions through numerical simulation. Individual Brownian motion trajectories are first generated for identical probe particles that are simultaneously placed on the liquid sample. Conservation laws for linear momentum and mechanical energy are both applied during particle collisions to determine the ensuing dynamics. The diffusion coefficient is then measured through ensemble averaging of the Brownian motion mean-squared-displacements. We have observed a direct relationship between the particle diameter and the most probable number of collisions within a 60 s observation period. In addition, the probe particle collisions introduce a deviation on the mean-squared-displacement that affects the measurement accuracy of the diffusion coefficient. A linear relationship is found between the number of observed collisions and the deviation between the measured diffusion coefficients.

Published
2018-05-19
How to Cite
[1]
A. T. Cusi, G. Tapang, and C. Saloma. Probe particle collisions and measurement accuracy of diffusion coefficient via Brownian motion, Proceedings of the Samahang Pisika ng Pilipinas 36, SPP-2018-PC-01 (2018). URL: https://paperview.spp-online.org/proceedings/article/view/SPP-2018-PC-01.
Section
Poster Session C (Mathematical Physics, Optics, and Interdisciplinary Topics)