DENSITY-ESTIMATION OF LIQUID LIQUID INTERFACIAL REGIONS USING A QUASI-ELASTIC LASER SCATTERING METHOD/

We developed a quasi-elastic laser scattering method and applied it to the density estimation of liquid/liquid (alcohol/water, carboxylic ac id/water) interfacial regions. The observed densities are smaller than the expected values in most of the cases, indicating that the interfa cial densities are smaller than the bulk phase densities. Moreover, th en is a marked tendency for the observed density to become smaller as the hydrophobic group in the alcohol and carboxylic acid molecules bec omes larger. The results are consistent with theoretical predictions u sing the molecular dynamics method. The interfacial structure is discu ssed in connection with these results.