Laser induced electronic excitation of surface hydroxide ions and scattering background in laser raman spectra of oxide surfaces

✍ Scribed by H. Jeziorowski; H. Knözinger

• Publisher: Elsevier Science
• Year: 1977
• Tongue: English
• Weight: 358 KB
• Volume: 51
• Category: Article
• ISSN: 0009-2614
• DOI: 10.1016/0009-2614(77)85415-8

✦ Synopsis

The laser excited so-called "fluorescence" background from MgO and q-Al203 surfaces was studied. Surface hydroxide ions are found to be responsible for this phenomenon, since a clear correlation between background intensity and hydrosyl group density of the surface is observed.

The so-called "fluorescence" background is usually a major problem when one attempts to record laser Raman spectra of species adsorbed on oxide surfaces, since its intensity may be higher by several orders of magnitude than the intensity of the weak Raman lines. It had been shown that the fluorescence could be reduced by heating the samples in oxygen at roughly 773 K [l-6] _ This treatment eliminates hydrocarbon contaminations.

A further decrease of the scattering background was observed on heating the oxide samples at increasingly higher temperatures up to 1200-1300 K in vacua [6--8]_ The actual origin of this "fluorescence" is still not well understood although several possible explanations have