Spectroscopic evidence for a gold-coloured metallic water solution
Spectroscopic evidence for a gold-coloured metallic water solution
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DOI：
10.1038/s41586-021-03646-5
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发表时间：
2021-07-29
期刊：
影响因子：
64.8
通讯作者：
Jungwirth, Pavel
中科院分区：
文献类型：
--
作者：
Mason, Philip E.;Schewe, H. Christian;Jungwirth, Pavel
光谱测量证实，当水在低压下吸附在碱性合金液滴上时，随着电子从液滴迅速移动到水中，就会形成金色的金属层。原则上，绝缘材料可以通过施加压力而变成金属。在纯水的情况下，这估计需要48兆巴的压力，这超出了目前的实验能力，可能只存在于大型行星或恒星的内部。事实上，最近的估计和实验表明，在实验室中可获得的压力下，水充其量是具有高质子电导率的超离子（5），但不是具有导电电子的金属（1）。在这里，我们表明，金属水溶液可以通过大量掺杂电子后，水与碱金属反应制备。尽管具有高浓度溶剂化电子的液氨的类似金属溶液早已为人们所知并已被表征（6-9），但碱金属和水之间的爆炸性相互作用（10，11）迄今为止仅允许制备具有低的亚金属电子浓度的水溶液（12-14）。我们发现，水-碱金属反应的爆炸行为可以通过在约10（-4）毫巴的低压下将水蒸气吸附到喷射到真空室中的液态钠-钾合金液滴上来抑制。这种设置导致形成覆盖金属合金液滴的金属水溶液的瞬时金色层。该层的金属特征，掺杂约5 × 10（21）电子每立方厘米，证实使用光学反射和同步X射线光电子能谱。
Spectroscopic measurements confirm that when water is adsorbed on drops of an alkali alloy at low pressure a gold-coloured metallic layer forms as electrons rapidly move from the drop into the water.Insulating materials can in principle be made metallic by applying pressure. In the case of pure water, this is estimated(1) to require a pressure of 48 megabar, which is beyond current experimental capabilities and may only exist in the interior of large planets or stars(2-4). Indeed, recent estimates and experiments indicate that water at pressures accessible in the laboratory will at best be superionic with high protonic conductivity(5), but not metallic with conductive electrons(1). Here we show that a metallic water solution can be prepared by massive doping with electrons upon reacting water with alkali metals. Although analogous metallic solutions of liquid ammonia with high concentrations of solvated electrons have long been known and characterized(6-9), the explosive interaction between alkali metals and water(10,11) has so far only permitted the preparation of aqueous solutions with low, submetallic electron concentrations(12-14). We found that the explosive behaviour of the water-alkali metal reaction can be suppressed by adsorbing water vapour at a low pressure of about 10(-4) millibar onto liquid sodium-potassium alloy drops ejected into a vacuum chamber. This set-up leads to the formation of a transient gold-coloured layer of a metallic water solution covering the metal alloy drops. The metallic character of this layer, doped with around 5 x 10(21) electrons per cubic centimetre, is confirmed using optical reflection and synchrotron X-ray photoelectron spectroscopies.