Photolysis of zinc azide in the solid state
Abstract
The photolysis of anhydrous zinc azide prepared by (1) dehydration of Zn(N 3) 2·2H 2O and (2) precipitation by acetone from aqueous solution, under the action of high pressure mercury arc is reported here. The pressure of nitrogen developed during photolysis under steady-state conditions at constant intensity is a linear function of t {1}/{2} in both the samples. The rate of photolysis is a linear function of intensity at constant temperature. A detailed analysis of the dark rate suggests that the dependence on t {1}/{2} should be due to the diffusion of nitrogen from the reaction site to the surface of the solid azide. An appropriate mathematical analysis is presented. The linear dependence of the rate of photolysis on the intensity of irradiation is interpreted in terms of the reaction of a trapped exciton with an adjacent azide ion. Absence of any detectable photoconduction in the wavelength range of the irradiating radiation suggests that excitons are the most probable reactive species. The sample of zinc azide obtained by the first method decomposes faster than the other under identical conditions, and has a slightly lower energy of activation of 1.4 kcal/mole compared to 1.75 kcal/mole for the second. These differences are discussed in terms of the defect concentrations of the two azide samples.
- Publication:
-
Journal of Solid State Chemistry France
- Pub Date:
- August 1974
- DOI:
- 10.1016/0022-4596(74)90041-3
- Bibcode:
- 1974JSSCh..10..323Y