[13p-2K-1~11] 1.5 Instrumentation, measurement and Metrology

[13p-2K-5] Weighing a single Brownian particle

〇JUNYA TAMURA¹, MASAAKI HASEGAWA¹, KOSUKE GOTO¹, KOZO MOCHIJI¹, KOUSUKE MORITANI¹, NORIO INUI¹ (1.Univ. of Hyogo)

Keywords:nanoparticle,interface,brownian motion

The Brownian motion of a single small particle trapped on the surface of a suspended liquid droplet is studied and used to measure its mass. On the basis of the Ornstein-Uhlenbeck theory, the time dependence of the distance between the particle and the bottom of the suspended droplet is considered. The mass of the particle is determined from this timeaveraged distance independently of the size and shape of the particle. The uncertainty of the estimation depends mainly on the measurement time of the trajectory, and it can be evaluated by Monte Carlo simulations. We experimentally demonstrate that the mass of a single gold particle 0.3 μm in radius can be measured using an optical microscope.