Surface vibrational spectroscopy of sulfuric acid-water mixtures at the liquid-vapor interface

Infrared-visible sum-frequency generation has been used to obtain vibrational spectra of sulfuric acid-water mixtures at the liquid-vapor interface in the OH stretch region. The spectral peaks gradually disappear with increase of sulfuric acid concentration, the dangling OH mode first, followed by the bonded OH modes. The results can be understood if the liquid surfaces are assumed to possess a more or less ordered hydrogen-bonding network.