Electromechanics of the liquid water vapour interface. Issue 19 (6th February 2020)

• Record Type: Journal Article
• Authors: Zhang, Chao; Sprik, Michiel
• Is Part Of: Physical chemistry chemical physics. Volume 22:Issue 19(2020)
• Page Start: 10676
• Page End: 10686
• Publication Date: 2020-02-06
• Subjects: Chemistry, Physical and theoretical -- Periodicals; 541.3
• DOI: 10.1039/c9cp06901a
• Languages: English
• ISSNs: 1463-9076

Abstract

Abstract : The response of the anisotropic stress at the liquid water vapor interface to a finite electric suggests that the surface potential of water can be seen as an electro-capillary effect coupled to the Maxwell stress tensor. Abstract : Two collective properties distinguishing the thin liquid water vapour interface from the bulk liquid are the anisotropy of the pressure tensor giving rise to surface tension and the orientational alignment of the molecules leading to a finite dipolar surface potential. Both properties can be regarded as capillary phenomena and are likely to be coupled. We have investigated this coupling by determining the response of the tangential component of the surface tension to the application of an electric field normal to the surface using finite field molecular dynamics simulations. We find an upside down parabola with a maximum shifted away from zero field. Comparing the molecular dynamics results to a phenomenological electromechanical model we relate the zero field derivative of the tangential part of the surface tension to the electrostatic potential generated by the spontaneous interface polarization. When interpreted with this model our simulations also indicate that Kelvin forces due to electric field gradients at a polarized interface play an important role in the effective dielectric response.