Abstract: | The diffuse reflection spectroscopy technique was used to investigate the color centers (CC) in the products of thermolysis
and photolysis of disperse Al(OH)3 in a vacuum. The spectra were recorded in situ in the region of 2.5–6.0 eV and 4000–12,000 cm−1. It was found that in thermolysis of Al(OH3) production of Al is accompanied, by transformation of the IR spectra of the compound and overtone vibrations of OH groups
and by the appearance of an absorption band (AB) at 4.0 eV with a shoulder at 4.4 eV. A similar AB is induced by UV irradiation
of Al(OH)3 in a vacuum. In the position of the maximum and shape, the AB at 4.0 eV in aluminum oxide produced by thermolysis of Al(OH)3 coincides with the AB of CC responsible for light- and temperature-stimulated degradation of white anode oxide coatings on
Al(Al-AOC). This suggests that in Al-AOC, CC are formed in decay of structural OmHn groups. In Al oxide and in Al-AOC, their nature is discussed with the use of data on optical absorption of radiation-induced
defects in Al2O3.
Research Institute of Physics at St. Petersburg State University, St. Petersburg 1, Ul’yanovskaya St., Petrodvorets St. Petersburg,
198904, Russia. Translated from Zhurnal Prikladnoi Spektroskopii, Vol. 65, No. 3, pp. 400–404, May–June, 1998. |