Max-Born-Institut für Nichtlineare Optik und Kurzzeitspektroskopie, 12489 Berlin, Germany.
Phys Rev Lett. 2012 Oct 5;109(14):147402. doi: 10.1103/PhysRevLett.109.147402. Epub 2012 Oct 2.
Transient polarizations connected with a spatial redistribution of electronic charge in a mixed quantum state are induced by optical fields of high amplitude. We determine for the first time the related transient electron density maps, applying femtosecond x-ray powder diffraction as a structure probe. The prototype ionic material LiBH4 driven nonresonantly by an intense sub-40 fs optical pulse displays a large-amplitude fully reversible electron transfer from the BH4(-) anion to the Li+ cation during excitation. Our results establish this mechanism as the source of the strong optical polarization which agrees quantitatively with theoretical estimates.
强振幅光场诱导混合量子态中电子电荷的空间再分布产生瞬态极化。我们首次应用飞秒 X 射线粉末衍射作为结构探针来确定相关的瞬态电子密度图。原型离子材料 LiBH4 非共振地被强亚 40fs 光脉冲驱动，在激发过程中 BH4(-)阴离子到 Li+阳离子发生了大振幅完全可逆的电子转移。我们的结果确立了该机制为强光学极化的来源，其与理论估计定量一致。
