Molecular mechanism of water bridge buildup: field-induced formation of nanoscale menisci.
We perform molecular dynamics calculations to describe, at the molecular level, the formation of a water bridge induced by an electric field. Restriction of orientational degrees of freedom (confinement) of water dipoles at the interfaces leads to a polarizability that depends on the shape of the water system, that is, droplet versus pillar. Above a threshold field of 1.2 V nm(-1), the competition between orientational confinement and electric field leads to the sudden formation of a water pillar. The formation of a water bridge is marked by a first order discontinuity in the total energy of the system. The simulations offer a molecular explanation for the threshold voltage and hysteresis behavior observed in the formation of nanoscale liquid bridges with a force microscope.
Cramer
Tobias
T
Dipartimento di Chimica G. Ciamician, Università di Bologna, V. F. Selmi 2, 40126 Bologna, Italy. tobias.cramer@unibo.it
Zerbetto
Francesco
F
García
Ricardo
R