Macroscopic extension of RRK and Weisskopf models of unimolecular evaporation

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

1 Agrégats (LCAR)

The macroscopic behavior of two microscopic unimolecular evaporation models is examined. The temperature dependences of bulk equilibrium vapor pressures deduced from the Rice-Ramsperger-Kassel (RRK) model and from the Weisskopf model, respectively, are compared. The bulk vapor pressures of sodium given by both models are compared, over a wide temperature range, with the experimental vapor pressures. The Weisskopf model is in better agreement with the experimental data than the RRK theory: from the melting temperature to the critical temperature (~ 370 K-2500 K), the vapor pressures of sodium calculated using the Weisskopf model agree with experimental values within 2%, whereas the RRK theory leads to errors of more than 40%. The Weisskopf theory satisfying the detailed balance principle, whereas the RRK theory does not, may explain this result.

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

Jean-Marc L'Hermite, Sébastien Zamith. Macroscopic extension of RRK and Weisskopf models of unimolecular evaporation. EPL - Europhysics Letters, 2012, 100 (2), pp.23001. ⟨10.1209/0295-5075/100/23001⟩. ⟨hal-00747636⟩