Accession Number : ADP007927

Title :   Vibrational Spectroscopy of Competitive Adsorption at a Liquid/Solid Interface using IR-Visible Sum-Frequency Generation,

Corporate Author : EXXON RESEARCH AND ENGINEERING CO ANNANDALE NJ

Personal Author(s) : Miragliotta, J. ; Polizzotti, R. S. ; Rabinowitz, P. ; Hall, R. B.

Report Date : 22 MAY 1992

Pagination or Media Count : 4

Abstract : Optical IR-Visible sum-frequency generation (SFG), a surface vibrational spectroscopy, has been used to study competitive adsorption at a hydroxylated ZrO2 surface in contact with a number of binary solutions. This technique is similar to surface second harmonic generation (SHG) in that it is forbidden (in the dipole approximation) in spatial regions possessing inversion symmetry. Therefore, systems consisting of an interface bound by centrosymmetric media give rise to a nonlinear response which is dominated by that of the interfacial region. In addition to being surface specific, the SFG signal from the liquid/solid interface can be resonantly enhanced when the incident IR laser source used in the generation process is tuned through a vibrational mode in the adsorbed species, provided the mode is both Raman and IR active. This vibrational information allows identification of the adsorbed molecule as well as measurements of surface coverage, molecular orientation, and adsorbate interactions for a number of the two-component liquid systems.

Descriptors :   *MOLECULAR VIBRATION, *ZINC OXIDES, ADSORBATES, ADSORPTION, DIPOLES, FREQUENCY, HARMONICS, IDENTIFICATION, INTERACTIONS, INTERFACES, INVERSION, LIQUIDS, MEASUREMENT, MOLECULES, RESPONSE, SIGNALS, SOLIDS, SPECTROSCOPY, SURFACES, SYMMETRY, LASER PUMPING.

Subject Categories : Atomic and Molecular Physics and Spectroscopy

Distribution Statement : APPROVED FOR PUBLIC RELEASE