WITHDRAWN: Fragmentation of charged aqueous nanodroplets

The whole evaporating process of charged aqueous nanodroplets is studied by systematic molecular dynamics simulations until most of the solvent molecules are evaporated. % The solvent evaporation makes the droplet smaller and smaller, and at a certain point the repulsive force among ions causes an instability, where typically single ion and 10 to 20 water molecules are disintegrated from the main droplet. % This ion fragmentation occurs around 70 to 80\% of the charge predicted by the Rayleigh theory [Lord Rayleigh, Phil. Mag. {\bf 14}, 184 (1882)]. % The numerical results are summarized in the function $R(z)$ which is the fragmentation radius at the charge $z$. From the fitting by the power law $R\propto z^\beta$, we find that at lower temperature $T=350$ and $370$ K the result is close to the Rayleigh theory $\beta = 2/3$, while at higher temperature $T=400$ and $450$ K it is like $\beta = 1/2$. % Another fitting on $R(z)$ by the extended ion evaporation mechanism [M. {Gamero-Casta\~{n}o} and J. {Fern\'{a}ndez de la Mora}, Anal. Chim. Acta {\bf 406}, 67 (2000)] works well for both cases. % The final state of the evaporation process is typically a single ion with several water molecules. If we put an alanine dipeptide in zwitterionic form at the beginning, two charges remain in some cases.