Analysis of a Quasi-Elastic Laser Scattering Spectrum Using the Maximum Entropy Method

Abstract

We have applied the maximum entropy method (MEM) to the analysis of quasi-elastic laser scattering (QELS) spectra and have established a technique for determining capillary wave frequencies with a higher time resolution than that of the conventional procedure. Although the QELS method has an advantage in time resolution over mechanical methods, it requires the averaging of at least 20 - 100 power spectra for determining capillary wave frequencies. We find that the MEM analysis markedly improves the S/N ratio of the power spectra, and that averaging the spectra is not necessary for determining the capillary wave frequency, i.e., it can be estimated from one power spectrum. The time resolution of the QELS attains the theoretical limit by using MEM analysis.