Studies of Titanium Primers for Adhesion by I.E.T.S.

Abstract

Inelastic Electron Tunnelling Spectroscopy (IETS) permits the vibrational and, in some cases, the electronic modes of adsorbed molecules to be determined with high resolution at picogram concentrations. This information can be used to define substrate interactions of importance, for example in:-

• (i) Heterogeneous catalysis [1,2,3,4]

• (ii) Corrosion studies [5,6]

• (iii) Adhesion [7,8,9,10]

as well as other topics [11]. The technique also allows the analytical determination of very low concentrations of a wide variety of molecules in gas phase or solution. A review of the chemical applications of IETS is available [12], which affords an outline of the fundamental physical aspects involved in IETS and the various methods of tunnelling junction fabrication are considered. Briefly, however, the aluminium electrode of an Al-AlO_x-Pb tunnel junction (the geometry of which is illustrated in figure l)is vacuum evaporated onto a glass fibre support. An oxide film 30–70 Å thick is produced by corona discharge in an oxygen atmosphere. Then the species to be studied is adsorbed onto the alumina surface. The junction is completed by the vacuum evaporation of the lead electrode.