PHOTOLUMINESCENCE AND PHOTOCATALYTIC ACTIVITY OF MGO POWDERS

Photoluminescence properties and photocatalyzed isomerization reaction of 2-butenes have been investigated using a standard JRC-MgO-I sample. The effects of the degassing temperature of the MgO sample and of the added quencher molecules such as O//2, CO, and H//2 indicated that the photoluminescence with a lifetime of 10** minus **4 sec is the radiative decay process from the charge transfer excited complex associated with the lower co-ordinated surface ions. It has been found that U. V. irradiation of degassed MgO samples in the presence of 2-butenes leads catalytically to trans - cis geometrical isomerization reaction with high efficiency, together with less efficient double bond shift isomerization reaction. The addition of CO or CO//2 led to the inhibition of this photocatalyzed isomerization as well as the photoluminescence of MgO samples. A complete parallel between the intensity of photoluminescence and the rate of photocatalyzed isomerization of butenes indicated that the lower co-ordinated surfaces ions play a significant role in the photocatalytic activity of degassed MgO powders.