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The application of inelastic electron tunnelling spectroscopy (IETS) to the study of surfactant adsorption upon an aluminium oxide surface
Author(s) -
Langley A. J.,
Oxley D. P.,
Smith E. G.
Publication year - 1982
Publication title -
surface and interface analysis
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.52
H-Index - 90
eISSN - 1096-9918
pISSN - 0142-2421
DOI - 10.1002/sia.740040105
Subject(s) - aqueous solution , chemistry , adsorption , chemisorption , inorganic chemistry , raman spectroscopy , oxide , aluminium , stearate , pulmonary surfactant , analytical chemistry (journal) , sodium , inelastic electron tunneling spectroscopy , quantum tunnelling , materials science , chromatography , organic chemistry , biochemistry , physics , optics , optoelectronics , scanning tunneling spectroscopy
Inelastic electron tunnelling spectroscopy has been applied to the study of sodium dodecanoate (laurate) adsorption, from aqueous solution, upon an aluminium oxide surface. AlAl 2 O 3 Pb tunnel junctions, whose oxides have been exposed to aqueous solutions of sodium dodecanoate are found to exhibit a maximum in resistance with increasing solution concentration. Spectral quality is dependent upon solution concentration, and optimum spectra are only obtained when junction resistance is near this maximum. The resistance maximum and decline in spectral quality with increasing solution concentration, are explained in terms of surfactant aggregation at a critical concentration. An optimum IET spectrum of sodium dodecanoate is presented and compared with the bulk infra‐red and Raman spectra of aluminium dodecanoate. A chemisorption mechanism is proposed. Other surfactants have also been investigated. These were sodium octadecanoate (stearate), sodium dodecyl sulphate and sodium hexadecyl sulphate. Problems specific to the application of inelastic electron tunnelling spectroscopy to these surfactants are reported.