Direct Experimental Evidence for a Negative Heat Capacity in the Liquid-to-Gas Phase Transition in Hydrogen Cluster Ions: Backbending of the Caloric Curve

F. Gobet, B. Farizon, M. Farizon, M. J. Gaillard, J. P. Buchet, M. Carré, P. Scheier, and T. D. Märk
Phys. Rev. Lett. 89, 183403 – Published 11 October 2002

Abstract

By selecting specific decay reactions in high-energy collisions (60keV/amu) of hydrogen cluster ions with a helium target (utilizing event-by-event data of a recently developed multicoincidence experiment) and by deriving corresponding temperatures for these microcanonical cluster ensembles (analyzing respective fragment distributions), we are able to construct caloric curves for H3+(H2)m cluster ions (6m14). All individual curves and the mean of these curves show a backbending in the plateau region, thus constituting direct evidence for a negative microcanonical heat capacity in the liquid-to-gas transition of these finite systems.

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  • Received 5 May 2002

DOI:https://doi.org/10.1103/PhysRevLett.89.183403

©2002 American Physical Society

Authors & Affiliations

F. Gobet, B. Farizon, M. Farizon, and M. J. Gaillard

  • Institut de Physique Nucléaire de Lyon, IN2P3-CNRS et Université Claude Bernard, 43 boulevard du 11 Novembre 1918, F-69622 Villeurbanne Cedex, France

J. P. Buchet and M. Carré

  • Laboratoire de Spectrométrie Ionique et Moléculaire, CNRS UMR 5579 et Université Claude Bernard, 43 boulevard du 11 Novembre 1918, F-69622 Villeurbanne Cedex, France

P. Scheier and T. D. Märk

  • Institut für Ionenphysik, Leopold Franzens Universität, Technikerstrasse 25, A-6020 Innsbruck, Austria

Comments & Replies

Comment on “Direct Experimental Evidence for a Negative Heat Capacity in the Liquid-to-Gas Phase Transition in Hydrogen Cluster Ions: Backbending of the Caloric Curve”

M. Chabot and K. Wohrer
Phys. Rev. Lett. 93, 039301 (2004)

Gobet et al. Reply

F. Gobet, B. Farizon, M. Farizon, M. J. Gaillard, J. P. Buchet, M. Carré, P. Scheier, and T. D. Märk
Phys. Rev. Lett. 93, 039302 (2004)

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Vol. 89, Iss. 18 — 28 October 2002

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