Accession Number : ADA116777

Title :   Photoacoustic Spectroscopy of Chemically Modified Surfaces.

Descriptive Note : Doctoral thesis,

Corporate Author : AIR FORCE INST OF TECH WRIGHT-PATTERSON AFB OH

Personal Author(s) : Burggraf,Larry Wilson

PDF Url : ADA116777

Report Date : Aug 1981

Pagination or Media Count : 278

Abstract : The ultimate goal of this research was to apply photoacoustic spectroscopy to the study of surface species on chemically modified surfaces. The study begins with a review of the theory of photoacoustic spectroscopy developed by Rosencwaig and Gersho. The theory for thermally thick samples is cast into a form more suitable for quantification. The photoacoustic magnitude and phase information are combined in a response function which is linear with optical absorption. The theory is extended to account for scattered-light effects in intensely light-scattering materials. Also, a method to correct for the effects of stray light in photoacoustic spectroscopy is presented. The potential of this spectroscopic technique for obtaining ultraviolet absorption spectra of organic functionald groups immobilized on silica surfaces by silylation is demonstrated. The complexation of copper (II) by an ethylenediammine analog immobilized on silica gel by silylation was characterized by photoacoustic spectroscopy and heterogeneous binding studies. Independent mono and bis binding sites are formed on the silica surface. Photoacoustic spectroscopy was used to study Ni/gamma-Al2O3, Co/gamma-Al2O3 and Co-Mo/gamma-Al2O3 catalysts. Visible spectrtal features are identified with octahedrally and tetrahedrally coordinated metal ions and metal oxides. A model is advanced to account for the dependence of speciation on metal loading and calcination temperature.

Descriptors :   *Surfaces, *Spectroscopy, *Light scattering, *Ultraviolet spectroscopy, Ethylenediamine, Copper compounds, Complex compounds, Bonding, Heterogeneity, Catalysts, Aluminum oxides, Nickel, Cobalt, Molybdenum, Theses

Subject Categories : Atomic and Molecular Physics and Spectroscopy

Distribution Statement : APPROVED FOR PUBLIC RELEASE