A two-state model analysis of the melting of sodium clusters: Insights in the enthalpy-entropy compensation

Sébastien Zamith (1) , Fabien Chirot (2) , Jean-Marc L'Hermite (1)

1 Agrégats (LCAR)
2 SA - Sciences Analytiques

Experimental melting temperatures and associated latent heats of size-selected sodium clusters are analyzed in the frame of a two-state model of melting. The strong variations of these quantities as a function of size make clusters an excellent benchmark for testing speculative ideas about melting. The relation between cohesive energy of clusters and their latent heat of melting is demonstrated, and a correlation between cohesive energy and vibrational frequency in the solid state is found. It is shown that this relation may throw light on the enthalpy-entropy compensation, which is observed in a variety of systems undergoing a first-order phase transition. A relation is established between the Lindemann melting criterion, the variation of the vibrational frequency with the cohesive energy, and the enthalpy-entropy compensation.

Mots clés: Heat capacities and heats of phase transitions; Phase transitions in clusters

Domaines: Agrégats Moléculaires et Atomiques [physics.atm-clus]

Sébastien Zamith, Fabien Chirot, Jean-Marc L'Hermite. A two-state model analysis of the melting of sodium clusters: Insights in the enthalpy-entropy compensation. EPL - Europhysics Letters, 2010, 92 (1), pp.13004. ⟨10.1209/0295-5075/92/13004⟩. ⟨hal-00530359⟩