Absorption of D(g) atoms in ultrathin Mg films and Pd-catalyzed decomposition of MgD2

• Published in: Journal of industrial and engineering chemistry (Seoul, Korea) 2009, 15(2), , pp.253-256
• Main Authors: Kim, Tae Seung, Song, Jun Woo, Lee, Seung June, Lee, Jihwa
• Format: Article
• Language: English
• Subjects: 화학공학
• ISSN: 1226-086X; 1876-794X
• DOI: 10.1016/j.jiec.2008.09.008

We have investigated the interaction of the gas-phase D atoms with ultrathin Mg films thermally evaporated on SiO2 by temperature programmed desorption. The gas-phase D atoms impinging upon a Mg (100A˚ ) film directly penetrate into the bulk with a constant probability of 0.22 until the top 16A˚ is deuterated, whereafter the MgD2(s) growth quickly slows down. Upon heating the partially deuterated Mg film, Mg atoms diffuse out to the surface to desorb at the same temperature as a pure Mg film. On the other hand, MgD2(s) decomposes to result in simultaneous desorption of D2 and Mg at 590 K with an activation energy of 133 5 kJ/mol. A Pd layer of 20A˚ thickness deposited on top of MgD2(s) acts as a catalyst to greatly reduce the decomposition temperature from 590 to 350 K. Weinterpret the catalytic effect of Pd in terms of reverse spill-over, in which the surface of Pd clusters in contact with MgD2(s) provides an intermediate adsorption sites with a low activation energy for the recombinative desorption of D atoms. 2009 The Korean Society of Industrial and Engineering Chemistry. Published by Elsevier B.V. All rights reserved. KCI Citation Count: 0