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Introduction to Nanotechnology

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202 OPTICAL AND VIBRATIONAL SPECTROSCOPY<br />

OH<br />

Figure 8.8. FTlR spectra of a y-alumina nanopowder surfaces after activation at 600°C (tracing<br />

a), and after subsequent deuteration (tracing b). [From M.4. Bara<strong>to</strong>n, in Nalwa (2000), Vol. 2,<br />

Chapter 2, p. 1 15.1<br />

the surface. The differences between the y-alumina and the 6-alumina spectra of Fig.<br />

8.9 provide evidence that the two aluminas differ in their allocations of Ai3+ <strong>to</strong><br />

octahedral and tetrahedral sites. In hrther work the adsorption of the heterocyclic<br />

six-membered ring compound pyridine, C5H5N, on y-alumina provided FTIR<br />

spectra of the pyridine coordinated <strong>to</strong> different Ai3+ Lewis acid sites. These infrared<br />

spectral results help clarify the coordination state of aluminum ions in the surface<br />

layer where Lewis acid sites play an important role in the catalytic activity.<br />

3000 2900 2800 2700 2600 2500 2400 2300 2200<br />

Wavenumber (cm-1)<br />

Figure 8.9. Details of FTlR surface spectra in the deuterated hydroxyl (OD) absorption region of<br />

y-Al2O3 (tracing a) and Q-A1203 (tracing b) nanopowders after activation at 500°C followed by<br />

deuteration. [From M.4. Bara<strong>to</strong>n, in Nalwa (2000), Vol. 2, Chapter 2 p. 11 7.1

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