Microscopic Roots of Alcohol-Ketone Demixing: Infrared Spectroscopy of Methanol-Acetone Clusters

Infrared spectra Of isolated methanol acetone clusters up to tetramers are experimentally characterized for the flint time. They show evidence for a nanometer-scale demixing trend of the cold species. In combination with quantum calculations, the mutual repulsion is demonstrated to start beyond three molecular, units, whereas individual molecules still prefer to form a mixed complex.