The structure of mixed methanol/chloroform clusters from core-level photoelectron spectroscopy and modeling

Mixed neutral molecular clusters have been produced by co-expansion of chloroform and methanol and characterized by carbon 1s photoelectron spectroscopy and theoretical modeling. The produced clusters are in the range 50–150 molecules and the clusters are not homogeneously mixed: chloroform is enriched in the bulk and methanol is found on or close to the surface. This is based on evidence from photoelectron depth profiling and molecular dynamics simulations of mixed clusters. The simulations suggest that methanol forms cyclic or linear oligomers in the surface layers of the mixed clusters. From thermodynamic models, the enrichment of methanol on the cluster surface can be rationalized from the difference in surface tension between the two pure components, which is connected to the qualitative differences in the respective bonding patterns.