Wittenberg Joshua S, Merkle Maxwell G, Alivisatos A Paul
Department of Chemistry, University of California, Berkeley, California 94720, USA.
Phys Rev Lett. 2009 Sep 18;103(12):125701. doi: 10.1103/PhysRevLett.103.125701. Epub 2009 Sep 17.
The behavior of CdSe nanocrystals shocked to stresses of 2-3.75 GPa has been studied. Above 3 GPa a near-complete disappearance of the first excitonic feature and broadening of the low-energy absorption edge were observed, consistent with a wurtzite to rocksalt structural transformation. The transformation pressure is reduced relative to hydrostatic compression in a diamond anvil cell, and the rate increases, attributed to shock induced shear stress along the reaction coordinate. The especially rapid rate observed for a 3.75 GPa shock suggests multiple nucleation events per particle.
研究了在2 - 3.75吉帕压力下受冲击的CdSe纳米晶体的行为。在3吉帕以上，观察到第一个激子特征几乎完全消失，低能吸收边变宽，这与纤锌矿到岩盐的结构转变一致。相对于金刚石对顶砧中静水压力压缩，转变压力降低，且速率增加，这归因于沿反应坐标的冲击诱导剪切应力。在3.75吉帕冲击下观察到的特别快速的速率表明每个粒子有多个成核事件。
