Dynamics of ammonia borane using neutron scattering

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• 作者：Craig M. Brown ; Teresa L. Jacques ; Nancy J. Hess ; Luke L. Daemen ; Eugene Mamontov ; John C. Linehan ; Ashley C. Stowe ; Tom Autrey
• 关键词：Hydrogen storage ; Dynamics ; Neutron ; Quasielastic scattering ; Backscattering
• 刊名：Physica B
• 出版年：2006
• 出版时间：15 November 2006
• 年：2006
• 卷：385-386
• 期：Part 1
• 页码：266-268
• 全文大小：130 K

文摘

We have used both the backscattering (HFBS) and time-of-flight (DCS) neutron spectrometers to investigate proton dynamics in ammonia borane, a compound of intense interest as a model for ‘chemical hydrogen storage’ materials. Results indicate that the deposition of ammonia borane on a mesoporous silicate results in longer proton residence times and lower energy barriers for proton motion compared to bulk ammonia borane. The reduced activation energy for proton motions may partly explain the improved thermolysis and lowering the activation barrier for the loss of the first equivalent of H₂. In addition, the phonon density of states for neat ammonia borane compares well with other spectroscopic results, with the intense peak at 22 meV assigned to the librational NH₃ and BH₃ modes, whereas ammonia borane on MCM-41 displays a broad, featureless spectrum indicating a poorly crystalline material.