Mixed Molecular and Atomic Phase of Dense Hydrogen
Mixed Molecular and Atomic Phase of Dense Hydrogen
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DOI：
10.1103/physrevlett.108.125501
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发表时间：
2012-03-19
影响因子：
8.6
通讯作者：
Gregoryanz, Eugene
中科院分区：
文献类型：
--
作者：
Howie, Ross T.;Guillaume, Christophe L.;Gregoryanz, Eugene
我们使用拉曼和可见光透射光谱来研究 300 K 下高达 315 (275) GPa 的稠密氢（氘）。在 200 GPa 左右，我们观察到相变，我们将其归因于 III 相，之前仅在低温下观察到。这在 220 GPa 下通过可逆转变到新的阶段 IV 得以成功，其特征是同时出现第二振动基本模式和新的低频声子激发以及第一振动基本模式的急剧软化和展宽。 IV 相的光学透射光谱显示吸收的整体增加和带隙的闭合，在 315 GPa 时达到 1.8 eV。拉曼光谱分析表明，第四相是类石墨烯层的混合物，由经历大配对波动的细长 H-2 二聚体和未结合的 H-2 分子组成。
We used Raman and visible transmission spectroscopy to investigate dense hydrogen (deuterium) up to 315 (275) GPa at 300 K. At around 200 GPa, we observe the phase transformation, which we attribute to phase III, previously observed only at low temperatures. This is succeeded at 220 GPa by a reversible transformation to a new phase, IV, characterized by the simultaneous appearance of the second vibrational fundamental and newlow-frequency phonon excitations and a dramatic softening and broadening of the first vibrational fundamental mode. The optical transmission spectra of phase IV show an overall increase of absorption and a closing band gap which reaches 1.8 eVat 315 GPa. Analysis of the Raman spectra suggests that phase IV is a mixture of graphenelike layers, consisting of elongated H-2 dimers experiencing large pairing fluctuations, and unbound H-2 molecules.