Ultrafast energy transfer between water molecules
Ultrafast energy transfer between water molecules
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DOI：
10.1038/nphys1498
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发表时间：
2010-02-01
期刊：
影响因子：
19.6
通讯作者：
Doerner, R.
中科院分区：
文献类型：
--
作者：
Jahnke, T.;Sann, H.;Doerner, R.
在水从气相转变为液相时，出现了许多新现象，而这些现象是孤立的 H2O 分子所不存在的。其中许多对于生命的存在、天体物理学和大气科学都很重要。特别是，随着更多的自由度变得可用，对电子激励的响应完全改变。在这里，我们报告了对 (H2O)(2)（所谓的水二聚体）中氢桥超快能量转移的直接观察。这种分子间库仑衰变导致低能电子从最初激发的分子的邻近分子中喷射出来。我们观察到这种衰变比质子转移更快，质子转移通常是电子激发小水簇的重要途径，并导致水二聚体解离成两个 H2O+ 离子。由于最近发现低能量电子（类似于 0.7-20 eV）可以有效分解 DNA 成分(1,2)，因此观察到的衰变通道可能会成为导致生物物质辐射损伤的电子源。
At the transition from the gas to the liquid phase of water, a wealth of new phenomena emerge, which are absent for isolated H2O molecules. Many of those are important for the existence of life, for astrophysics and atmospheric science. In particular, the response to electronic excitation changes completely as more degrees of freedom become available. Here we report the direct observation of an ultrafast transfer of energy across the hydrogen bridge in (H2O)(2) (a so-called water dimer). This intermolecular coulombic decay leads to an ejection of a low-energy electron from the molecular neighbour of the initially excited molecule. We observe that this decay is faster than the proton transfer that is usually a prominent pathway in the case of electronic excitation of small water clusters and leads to dissociation of the water dimer into two H2O+ ions. As electrons of low energy (similar to 0.7-20 eV) have recently been found to efficiently break-up DNA constituents(1,2), the observed decay channel might contribute as a source of electrons that can cause radiation damage in biological matter.