Water at interfaces - some recent experimental results from surface spectroscopy

Fundamental aspects of interfacial phenomena in aqueous systems are determined by the properties of interfacial water It has become evident that interfacial water must be characterized spectroscopically in order to explain the recently identified non DLVO forces observed by atomic force microscopy and with the surface force apparatus. In the past little information was available regarding the spectroscopic characteristics of interfacial water due to the difficulty in differentiating between bulk and interfacial water. However, with the advent of FTIR and Raman internal reflection spectroscopy (IRS) and the recent non-linear optical technique, sum frequency generation (SFG), more information on interfacial water is now available as is evident from the results of recent spectroscopic studies. Thus the non DLVO forces eventually may be explained by the extent of hydrogen bonding as revealed by surface spectroscopic techniques.