Salt-induced Long-to-Short Range Orientational Transition in Water

Phys Rev Lett. 2018 Jun 29;120(26):263001. doi: 10.1103/PhysRevLett.120.263001.

Abstract

We report the long-range orientational organization of water using polarization-resolved second harmonic scattering operated in a right-angle configuration. A transition is observed between the neat water orientational organization involving an azimuthal molecular orientation distribution towards a radial molecular orientation distribution when salt is added. These two orientational phases are quantitatively described using a molecular model of the second harmonic scattering response. It is observed that the long-range correlation present in the neat water phase abruptly disappears and is replaced by a shorter range correlation centered around the ions as the salt concentration is increased.