Max-Born-Institut für Nichtlineare Optik und Kurzzeitspektroskopie, Max-Born-St. 2 a, Berlin, 12489, Germany.
Phys Chem Chem Phys. 2012 May 14;14(18):6156-9. doi: 10.1039/c2cp24072f. Epub 2012 Mar 22.
Transient electron density maps of potassium dihydrogen phosphate (KH(2)PO(4), KDP) are derived from femtosecond X-ray powder diffraction patterns. Upon photoexcitation, the low-frequency TO soft mode is elongated impulsively and modulates the electronic charge distribution on the length scale of interatomic distances, much larger than the vibrational amplitude. The results demonstrate a charge transfer from the volumes around the P-atoms and K(+)-ions to those containing the O-HO units and a quadrupolar distortion of the K(+) charge distribution. This behavior reflects the interplay of nuclear motions and electric polarizations in the ionic crystal lattice.
通过飞秒 X 射线粉末衍射图谱，我们得到了磷酸二氢钾（KH(2)PO(4)，KDP）的瞬态电子密度图。光激发后，低频 TO 软模会被瞬间拉长，并在原子间距离的尺度上调制电子电荷分布，其幅度远大于振动幅度。结果表明，电荷从 P 原子和 K(+)离子周围的区域转移到含有 O-HO 单元的区域，并且 K(+)电荷分布发生了四极变形。这种行为反映了离子晶格中核运动和极化的相互作用。
