Nanocrystal Surface Structure Analysis by Analytical Ultracentrifugation
详细信息 查看全文
- 作者：Helmut Cö ; lfen ; Shay Tirosh ; and Arie Zaban
- 刊名：Langmuir
- 出版年：2003
- 出版时间：December 23, 2003
- 年：2003
- 卷：19
- 期：26
- 页码：10654 - 10659
- 全文大小：150K
- 年卷期：v.19,no.26(December 23, 2003)
- ISSN：1520-5827
文摘
Sedimentation velocity experiments on two TiO2 model colloids with similar properties but differentsurface structures were performed as a function of the solution pH in order to differentiate between similarsize particles. The particle sedimentation velocity is highly sensitive to the surface structure, which isindicative of the exposed crystal face of the nanocrystals. Increase of the pH from 1 to 3 resulted inaggregation of all particles in one sample, whereas only partial aggregation occurred for the other, althoughthe 
-potential of both samples is almost identical in that pH range indicating particle stability. Althoughthe particles are not distinguishable by the conventional methods for particle charge determination, theyare clearly different in terms of their sedimentation coefficient distributions. Furthermore, analyticalultracentrifugation (AUC) reveals a dependence of the onset of large aggregate formation on the particlesurface. This suggests that AUC has the potential to quantitatively determine differences in the particlesurface structure even for polydisperse samples with constant average charge where conventional -potentialmeasurements yield only a constant average value. As ultracentrifugation yields distributions, we furtherdiscuss whether a combination with a second independent method like flow-field-flow fractionation canyield particle size and charge distributions in a global analysis approach.
-potential of both samples is almost identical in that pH range indicating particle stability. Althoughthe particles are not distinguishable by the conventional methods for particle charge determination, theyare clearly different in terms of their sedimentation coefficient distributions. Furthermore, analyticalultracentrifugation (AUC) reveals a dependence of the onset of large aggregate formation on the particlesurface. This suggests that AUC has the potential to quantitatively determine differences in the particlesurface structure even for polydisperse samples with constant average charge where conventional -potentialmeasurements yield only a constant average value. As ultracentrifugation yields distributions, we furtherdiscuss whether a combination with a second independent method like flow-field-flow fractionation canyield particle size and charge distributions in a global analysis approach.