Photon-Correlation Spectroscopy
This method is also referred to as dynamic light scattering and quasi-elastic light scattering. It is applicable to particles suspended in a liquid, which are in a state of random movement due to Brownian Motion (i.e. particles generally of 2 -3 µm diameter and smaller). The pace of the movement is inversely proportional to particle size (the smaller the particles are, the faster they move, or diffuse), and the pace can be detected by analyzing the time dependency of the light intensity fluctuations scattered from the particles when they are illuminated with a laser beam. Coulter Corporation was the first company to commercialize an instrument for the Particle Technologist which was known as the COULTER® NANO-SIZER® particle sizer; it presented average particle size within the range of 3 µm down to 40 nm, and also gave an indication of the width of the size distribution.
The current COULTER® N4 Plus provides not only mean particle size, but also size distributions computed by the industry standard CONTIN algorithm, and six measurement angles to enhance the detection of populations of particles of different sizes. A 10mW Helium Neon laser provides detection of weakly scattering particles.The particle size range is from 3nm to 3 µm. An 80-channel multi-tau correlator (the hard-wired computation circuit which characterizes the rate of fluctuations in scattered light intensity) optimizes resolution across the dynamic range of the instrument. In addition, a software package running in the Microsoft Windows environment provides the user with a database format for storing data, easy-to-use toolbar functionality, and real time status of measurements.
© Coulter International Corporation, 1996. All rights reserved. Copyrights and Trademarks
 |
 |
 |
 |