Journal of Surface Science and Technology

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Evidence for the Chemical Nature of Capping in CdSe Nanoparticles


Affiliations
1 Department of Physics, Radiation Laboratory, University of Notre Dame, Notre Dame, Indiana, IN 46556, United States
2 Radiation Laboratory, University of Notre Dame, Notre Dame, Indiana, IN 46556, United States
     

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The CdSe nanocrystals were grown by TOPO (trioctyl phosphine oxide)capping method using CdO as a precursor. CdSe nanoparticles of size 30-40 Å have been prepared at different Cd:Se ratios. Extended X-ray Absorption Fine Structure (EXAFS) analysis was used on a variety of CdSe nanocrystallites to study the surface structure. Our EXAFS results show that TOPO binds to the CdSe particles via Cd-O bond and not through the Se-O bond. Use of excess Cd initially (Cd : Se = 2 : 1), caps the CdSe particles with an extra layer of Cd. This extra cap renders further stability to the particles against oxidation and light, as is evident from the more stable emission properties of these particles. However, when the excess Cd is not present as in the case of Cd : Se = 1 : 1, then the particles are less stable to oxidation and light.

Keywords

Nanoparticles, Topo Capping, Extended X-Ray Absorption Fine Structure, Semiconductor Materials.
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  • Evidence for the Chemical Nature of Capping in CdSe Nanoparticles

Abstract Views: 196  |  PDF Views: 2

Authors

Debdutta Lahiri
Department of Physics, Radiation Laboratory, University of Notre Dame, Notre Dame, Indiana, IN 46556, United States
Shailesh N. Sharma
Radiation Laboratory, University of Notre Dame, Notre Dame, Indiana, IN 46556, United States
S. Zeena
Radiation Laboratory, University of Notre Dame, Notre Dame, Indiana, IN 46556, United States
Bruce A. Bunker
Department of Physics, Radiation Laboratory, University of Notre Dame, Notre Dame, Indiana, IN 46556, United States

Abstract


The CdSe nanocrystals were grown by TOPO (trioctyl phosphine oxide)capping method using CdO as a precursor. CdSe nanoparticles of size 30-40 Å have been prepared at different Cd:Se ratios. Extended X-ray Absorption Fine Structure (EXAFS) analysis was used on a variety of CdSe nanocrystallites to study the surface structure. Our EXAFS results show that TOPO binds to the CdSe particles via Cd-O bond and not through the Se-O bond. Use of excess Cd initially (Cd : Se = 2 : 1), caps the CdSe particles with an extra layer of Cd. This extra cap renders further stability to the particles against oxidation and light, as is evident from the more stable emission properties of these particles. However, when the excess Cd is not present as in the case of Cd : Se = 1 : 1, then the particles are less stable to oxidation and light.

Keywords


Nanoparticles, Topo Capping, Extended X-Ray Absorption Fine Structure, Semiconductor Materials.