Abstract

Understanding of interfacial properties of water is crucial for advances in many disciplines and for the solution of many technological problems. Although the problem has been extensively studied,¹ progress has been rather slow because of the lack of appropriate experimental techniques. Important and interesting questions still remain unresolved. For example: What are the orientations and arrangement of water molecules at the vapor-water interface or at a hydrophobic (or hydrophilic) substrate-water interface? Can an interface promote ice nucleation? We show in this paper that it is possible to use sum-frequency generation (SFG) to obtain vibrational spectra of water molecules at interfaces, and the results provide some answers to the above-stated questions.

© 1993 Optical Society of America