Surface-melting transitions and phase coexistence in argon solvent clusters

Abstract

Electronic spectra of carbazole⋅${\mathrm{Ar}}_{\mathrm{n}}$ clusters in supersonic beams exhibit specific size-dependent spectral features, showing only sharp intermolecular vibrational bands for n=1 to 3, both broad and narrow spectral bands for n=4 to 6, and only broad bands for n≥7. Monte Carlo simulations indicate that the change from sharp to broad structure is due to surface melting transitions of the solvent clusters relative to the substrate, and predict a finite-width solidlike-liquidlike coexistence range in agreement with the experimental observations.