Oriented thiocyanate anions at the air-electrolyte interface and its implications on interfacial water - A vibrational sum frequency spectroscopy study

We used infrared-visible sum frequency spectroscopy (IR-VIS SFG) to study the interfacial composition and structure of aqueous potassium thiocyanate electrolyte solutions. The IR-VIS SFG spectra reveal an enrichment of the thiocyanate ions at the air-electrolyte interface. They also give access to the vibrational features of the interfacial water, which are affected by the presence of the ions. Polarization-dependent measurements have been used for a determination of the orientation of the pseudohalide anion. The combined data gives a picture of the interfacial architecture on a molecular scale.