[OPTICAL REVIEW Vol. 21, No. 3 (2014) 378-381]
© 2014 The Japan Society of Applied Physics

Experimental Study on Air–Liquid Interface Effect of Brownian Dynamics Using Spectral-Domain Low-Coherence Dynamic Light Scattering

Toshiharu WATARAI and Toshiaki IWAI*

Graduate School of Bio-Applications and Systems Engineering, Research Institute of Technology, Tokyo University of Agriculture and Technology, Koganei, Tokyo 184-8588, Japan

(Received October 17, 2013; Accepted December 13, 2013)

Space-variant dynamics of Brownian particles near an air–liquid interface is investigated by a one-shot analysis technique based on spectral-domain low-coherence dynamic light scattering. The expression “one shot” refers to the simultaneous and seamless measurement of temporal autocorrelation functions of the time-varying intensity depending on the scattering position without any scanning operation. It is experimentally confirmed that the Brownian motion is suppressed in a region close to an air–liquid interface, is activated by increasing the distance from the interface, and becomes freely diffusive far from the interface. This work is considered to be the first experimental confirmation of space-variant Brownian dynamics in the vicinity of an air–liquid interface.

Key words: dynamic light scattering, optical coherence tomography, spectroscopy

*E-mail address: tiwai@cc.tuat.ac.jp