Structural phase transitions of small molecules at air/water interfaces
نویسندگان
چکیده
Structural phase transitions have been observed using IR-VIS sum frequency generation (SFG) at the air/acetonitrile-water and the air/propionitrile-water interfaces but not at the air/butyronitrile-water interface. The phase transitions were detected by abrupt changes in the CN vibrational frequency and in the orientation of the CN chromophore as the interface nitrile density was varied. A model based on the orientational effects of hydrogen bonding and solvation of the CN group by water molecules competing with the density and orientationally dependent dipole-dipole repulsions among the CN chromophores is used to explain the results.
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