The structure of polaronic electron cavities in lithium-ammonia solutions
The structure of polaronic electron cavities in lithium-ammonia solutions
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DOI：
10.1088/0953-8984/16/32/001
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发表时间：
2004-08
期刊：
影响因子：
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通讯作者：
Helen Thompson;Jonathan C. Wasse;N. Skipper;C. A. Howard;D. Bowron;A. Soper
中科院分区：
文献类型：
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作者：
Helen Thompson;Jonathan C. Wasse;N. Skipper;C. A. Howard;D. Bowron;A. Soper
中子衍射法与氢的氚同位素替代相结合，用于研究锂-氨溶液的结构，其浓度跨越了金属-非金属的转变。通过迭代改进三维分子模型，我们对实验数据进行了详细的分析和可视化，使我们能够对溶液中极化子电子空穴的形成有独特的见解。在低电子浓度下，溶液是非金属的，氨分子围绕空穴中心取向，形成Bjerrum类型的缺陷。随着电子含量的增加，溶液变成了金属，我们发现了通过溶剂的渗流通道的证据。因此，解离的电子在决定这些溶液的结构方面起着积极的作用，并破坏液氨中存在的氢键。
Neutron diffraction has been used in conjunction with isotopic substitution of deuterium for hydrogen to study the structure of lithium-ammonia solutions, at concentrations spanning the metal-nonmetal transition. Detailed analysis and visualization of our experimental data has been carried out via iterative refinement of a three-dimensional molecular model, allowing us to obtain unique insight into the formation of polaronic electron cavities in the solutions. At low electron concentrations the solutions are nonmetallic, and the ammonia molecules are orientated around cavity centres to form Bjerrum-type defects. As the electron content is increased, the solutions become metallic, and we find evidence of percolation channels through the solvent. The dissociated electrons therefore play an active role in determining the structure of these solutions, and serve to disrupt the hydrogen bonding present in liquid ammonia.