Manifestation of Rayleigh instability in droplets containing multiply charged macroions.
The Rayleigh limit and manifestations of instability in liquid droplets containing charged macroions are examined by molecular simulations. It is found that beyond the Rayleigh limit, the spherical droplets become unstable and form structures with distinct features. Regardless of the nature of the charged macroion, an assembly of spines of highly ordered polar solvent molecules form on the droplet surface. The surface charge distribution of the spiny droplet is highly nonuniform, and the macroscopic description of the droplet energy as a sum of electrostatic and surface terms is no longer valid. When the macroion is a charge-saturated polyhistidine chain, it is shown that the changes in the structure of the droplet are accompanied by the chain extension. Contrary to the conventional point of view, it is found that single ions present in droplets containing a highly charged macroion do not escape spontaneously but rather form complexes stable on the nanosecond time scale, depending on the degree of deviation from the Rayleigh limit and the nature of the ion. The effect of the instability in the disintegration mechanism of charged droplets in electrospray mass spectrometry experiments is discussed.
Consta
Styliani
S
Department of Chemistry, The University of Western Ontario, London, Ontario, Canada N6A 5B7. styliani.constas@gmail.com