Nonlinear optical studies of the molecular structure in CH3 OH/H2O and CH3CN/H2O binary liquid mixtures

Hydrogen bonding liquids, such as methanol and water, exhibit peculiar thermodynamic behaviors. These liquids as well as the binary mixtures are important solvents and relevant to many chemical and biochemical processes appearing in our daily living. Unfortunately, the understanding of these liquid systems are rather poor owing to the lack of suitable techniques with which the molecular structure can be probed. In the past, the structural information of liquids was obtained indirectly by the measurements of thermodynamic quantities. The authors show in the report that important structural information of liquids can be deduced by use of third-harmonic generation (THG) and infrared-visible sum-frequency generation (IVSFG)