Microheterogeneity of ethanol-water binary mixtures observed at the cluster level

The microscopic structures in ethanol-water binary mixtures were examined by analyzing the mass spectra of clusters generated through fragmentation of liquid droplets. From the effects of temperature and mixing ratios on the cluster structures, we have demonstrated that the ethanol-water binary mixtures have microscopic phase separation at the cluster level in wide mixing ratios: 10 vol.% < [EtOH] < 90 vol.%. In this region, ethanol-rich clusters whose molecular composition is independent of the mixing ratio were observed at lower temperatures, and the ethanol-rich clusters interacted with water molecules with increasing temperature. Furthermore, we would like to present the mechanism for the formation of ethanol-rich clusters, induced by the contact with water molecules. (C) 2006 Elsevier B.V. All rights reserved.