ゆらぎで探る溶液の構造－混合状態の直接表現－

Abstract

Radial distribution functions are commonly used to study the structures of many non-crystalline materials. The present author proposed a completely different method to describe the solution structure by expressing the inhomogeneity in distribution of molecules and in concentration as “density fluctuation” and “concentration fluctuation”, respectively; namely the structure of a solution is described in terms of the “mixing state” or “mixing scheme.” This paper introduces the fluctuations, as well as Kirkwood-Buff Integrals. Fluctuations of solutions become more pronounced in the mesoscale region. The relationship with solution thermodynamics, which represents the macroscopic limit, is also discussed. The features and cautions of experiments to measure the fluctuations are described. Finally, as analytical examples, temperature and concentration dependences of mixing schemes for two solution systems with upper critical and lower critical solution temperatures are presented.