Dr. Kislon Voitchovsky from the University of Durham will give a seminar at the School of Mathematics and Physics, on Wednesday 9th of December 2015, 1.15 pm (room ENG209 in Engineering hub, building 13 on the uni map).

Direct observation of the self-assembly and dynamics of single ions at the solid-water interface

The behaviour of water and ions at the interface with immersed solids plays a central role in processes as disparate as crystal growth, electrochemistry, and biological function. Experimentally, gaining insights into the molecular mechanism underlying these processes remains challenging, partly because of the need to probe the system in-situ, locally and with sub-nanometre resolution.

Atomic force microscopy (AFM) can in principle overcome these difficulties, with recent developments making it possible to map sub-nanometre details of the liquid at the interface with immersed solids [1] and gather quantitative information about its local dynamics [1-2]. Here AFM is used to create images of single metal ions close to biological [3] and mineral [4-5] surfaces immersed in aqueous solutions. The behaviour of the water molecules can control the organisation of ions at the interface, create unforeseen structures, and considerably slow down their dynamics, depending on their hydration properties. Results obtained near surface singularities such as protein surfaces, atomic steps, or adsorbed organics highlight the impact that these local perturbations have on the behaviour of the interfacial water and ions, with consequences for the fate of the system studied.

[1] Voitchovsky et al., Nat. Nanotechnol., 5, 401, (2010)
[2] Ortiz-Young et al., Nat. Commun., 4, 2482, (2013)
[3] Contera et al,. Nanoscale, 2, 222, (2010)
[4] Ricci et al., Langmuir, 29, 2207, (2013)
[5] Ricci et al., Nat. Commun., 5, 4400, (2014)