Direct in situ determination of the mechanisms controlling nanoparticle nucleation and growth.
Direct in situ determination of the mechanisms controlling nanoparticle nucleation and growth.
复制标题
DOI：
10.1021/nn303371y
复制
发表时间：
2012-10-23
期刊：
影响因子：
17.1
通讯作者：
Browning, Nigel D.
中科院分区：
文献类型：
--
作者：
Woehl, Taylor J.;Evans, James E.;Arslan, Like;Ristenpart, William D.;Browning, Nigel D.
关键词：
虽然使用常规胶体合成可控制纳米晶形态，但通常需要多种表征技术来确定关键性质，如成核速率、诱导时间、生长速率和所得形态。最近，研究人员通过原位电子束还原证明了纳米晶体的生长，提供了对单个纳米晶体的直接观察，并消除了对多种表征技术的需要;然而，他们发现，对于相同的电子束参数，纳米晶体的形貌与两种不同的生长机制一致。在这里，我们表明，电子束电流起着类似的作用，在传统的合成中的还原剂的浓度，通过控制的生长机制和最终形态的银纳米晶体生长通过原位电子束还原。我们表明，低束流鼓励反应限制生长，产生纳米晶体的多面结构，而较高的束流鼓励扩散限制生长，产生球形纳米晶体。通过隔离这两个增长制度，我们证明了一个新的水平的控制，控制的基本增长机制的形态。我们发现成核的感应阈值剂量与束流、像素停留时间和放大倍数无关。我们的研究结果表明，原位电子显微镜数据可以解释经典模型，通过允许同时测量成核诱导时间，生长速率，和演化的结晶形态。结果表明，系统的剂量实验应进行所有未来的原位液体研究，以确认核和生长的观察背后的确切机制。
Although nanocrystal morphology is controllable using conventional colloidal synthesis, multiple characterization techniques are typically needed to determine key properties like the nucleation rate, induction time, growth rate, and the resulting morphology. Recently, researchers have demonstrated growth of nanocrystals by in situ electron beam reduction, offering direct observations of single nanocrystals and eliminating the need for multiple characterization techniques; however, they found nanocrystal morphologies consistent with two different growth mechanisms for the same electron beam parameters. Here we show that the electron beam current plays a role analogous to the concentration of reducing agent in conventional synthesis, by controlling the growth mechanism and final morphology of silver nanocrystals grown via in situ electron beam reduction. We demonstrate that low beam currents encourage reaction limited growth that yield nanocrystals with faceted structures, while higher beam currents encourage diffusion limited growth that yield spherical nanocrystals. By isolating these two growth regimes, we demonstrate a new level of control over nanocrystal morphology, regulated by the fundamental growth mechanism. We find that the induction threshold dose for nucleation is independent of the beam current, pixel dwell time, and magnification being used. Our results indicate that in situ electron microscopy data can be interpreted by classical models, by allowing simultaneous measurement of nucleation induction times, growth rates, and evolution of nanocrystal morphology. The results suggest that systematic dose experiments should be performed for all future in situ liquid studies to confirm the exact mechanisms underlying observations of nucleation and growth.
登录
查看更多内容
影响因子：
41.2
作者：
Williamson, MJ;Tromp, RM;Ross, FM
通讯作者：
Ross, FM
影响因子：
64.8
作者：
Peng, XG;Manna, L;Alivisatos, AP
通讯作者：
Alivisatos, AP
DOI：
10.1098/rspa.1993.0035
发表时间：
1993-03-08
期刊：
PROCEEDINGS OF THE ROYAL SOCIETY OF LONDON SERIES A-MATHEMATICAL PHYSICAL AND ENGINEERING SCIENCES
影响因子：
--
作者：
KIRKLAND, AI;JEFFERSON, DA;SMITH, DJ
通讯作者：
SMITH, DJ
影响因子：
3.8
作者：
Jiang, Shanfeng;ter Horst, Joop H.
通讯作者：
ter Horst, Joop H.
影响因子：
2.2
作者：
Noh, Kyong Wook;Liu, Yin;Dillon, Shen J.
通讯作者：
Dillon, Shen J.