论文标题
金属水：超快电子激发下的瞬时状态
Metallic water: transient state under ultrafast electronic excitation
论文作者
论文摘要
飞秒激光器或迅速重离子束受控辐照的现代手段可以在样品中瞬时产生这种能量密度，这些样品达到温度致密物质的集体电子激发水平，其中颗粒相互作用的势能与其动能相当（几次EV的温度）。这种巨大的电子激发严重改变了原子间电位，从而产生了异常的物质和不同化学的非平衡状态。我们采用密度功能理论和紧密的结合分子动力学形式主义来研究大量水对其电子超快激发的反应。一定的阈值电子温度后，水通过其带隙的崩溃进行电子导电。在高剂量下，它伴随着离子在100 fs时间尺度内的几千种海尔文温度的非热加速度。我们确定了这种非热机制与电子离子耦合的相互作用，从而增强了电子对离子的能量传递。根据沉积的剂量，由分解的水分子形成各种化学活性片段。
The modern means of controlled irradiation by femtosecond lasers or swift heavy ion beams can transiently produce such energy densities in samples that reach collective electronic excitation levels of the warm dense matter state where the potential energy of interaction of the particles is comparable to their kinetic energies (temperatures of a few eV). Such massive electronic excitation severely alters the interatomic potentials, producing unusual nonequilibrium states of matter and different chemistry. We employ density functional theory and tight binding molecular dynamics formalisms to study the response of bulk water to ultrafast excitation of its electrons. After a certain threshold electronic temperature, the water becomes electronically conducting via the collapse of its band gap. At high doses, it is accompanied by nonthermal acceleration of ions to a temperature of a few thousand Kelvins within sub-100 fs timescales. We identify the interplay of this nonthermal mechanism with the electron-ion coupling, enhancing the electron-to-ions energy transfer. Various chemically active fragments are formed from the disintegrating water molecules, depending on the deposited dose.
