阿尔法

Vapor adsorption is an important process influencing themigration and the fates of many organic pollutants in theenvironment. In this study, adsorption of ethylene glycol (EG)vapor onto single crystal R-Al2O3 (0001) and fused SiO2(amorphous) surfaces was studied with sum frequencygeneration spectroscopy, a well-suited surface specifictechnique for probing interfacial phenomena at the molecularscale. Air-aqueous EG solutions were also investigatedto compare to the adsorption at the air-solid interface inthe presence of water vapor. The gauche conformer ofEG molecules dominates the air-aqueous EG solutioninterface, and EG molecules act as hydrogen acceptorsat the air-liquid interface. Water and surface hydrophilic/hydrophobic properties play important roles for theadsorption of EG onto silica and alumina surfaces. Theadsorbed EG molecules interact in different ways at the twodifferent oxide surfaces. EG molecules weakly physisorbonto the R-Al2O3 (0001) surface by forming relatively weakhydrogen bonds with surface water molecules. On thesilica surface, the suppression of the silanol OH stretchingpeak indicates that EG molecules form hydrogen bondswith silanol OH groups.Introduction