Probing possible structural models at the air/H2SO4(aq) interface: a second harmonic generation study

Abstract

The second harmonic generation (SHG) signal from the air/H₂SO₄(aq) interface shows that the nature of the surface changes as a function of the concentration of the acid. In the low concentration region a comparison is made with the simple electrolyte NaCl. In the intermediate region the formation of molecular hydrates can rationalise the increased surface response in terms of hydrogen bonded layer structures similar to those seen in the crystal structures with the response falling as the pure acid is approached.