Heat capacities of freely evaporating charged water clusters
Journal article, 2009

We report on evaporation studies on positively charged water clusters (H$^+$(H$_2$O)$_N$) and negatively charged mixed clusters (X$^-$(H$_2$O)$_N$) with a small core ion $X$ ($X$=O$_2$,CO$_3$ or NO$_3$), in the size range $N=5$ to $300$. The clusters were produced by corona discharge in ambient air, accelerated to 50 keV and mass selected by an electromagnet. The loss of monomers during the subsequent 3.4 m free flight was recorded. The average losses are proportional to the clusters' heat capacities and this allowed the determination of size-dependent heat capacities. The values are found to increase almost linearly with clusters size for both species, with a rate of 6-8 $k_B$ per added molecule. For clusters with $N<21$ the heat capacities per molecule are lower but the incremental increase higher. For $N>21$ the values are intermediate between the bulk liquid and the solid water 0 $^o$C values.

water clusters

thermodynamics properties


Erika Sundén

University of Gothenburg

K Stöchkel

Aarhus University

S Panja

Aarhus University

U Kadhane

Aarhus University

P. Hvelplund

Aarhus University

S. Brøndsted Nielsen

Aarhus University

H. Zettergren

Aarhus University

Bertil Dynefors

Chalmers, Applied Physics

Klavs Hansen

University of Gothenburg

Journal of Chemical Physics

0021-9606 (ISSN) 1089-7690 (eISSN)

Vol. 130 22 224308- 224308

Subject Categories

Atom and Molecular Physics and Optics



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