Determination of Internal Structures of Heterogeneous Nanocrystals Using Variable-Energy Photoemission Spectroscopy

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• 作者：Sumanta Mukherjee ; Abhijit Hazarika ; Pralay K. Santra ; Ahmed L. Abdelhady ; Mohammad Azad Malik ; Mihaela Gorgoi ; P. O鈥橞rien ; O. Karis ; D. D. Sarma
• 刊名：Journal of Physical Chemistry C
• 出版年：2014
• 出版时间：July 17, 2014
• 年：2014
• 卷：118
• 期：28
• 页码：15534-15540
• 全文大小：414K
• ISSN：1932-7455

文摘

This article describes the determination of the internal structure of heterogeneous nanoparticle systems including inverted core鈥搒hell (CdS core and CdSe shell) and alloyed (CdSeS) quantum dots using depth-resolved, variable-energy X-ray photoelectron spectroscopy (XPS). A unique feature of this work is the combination of photoelectron spectroscopy performed at lower X-ray energies (400鈥?00 eV), to achieve surface sensitivity, with bulk sensitive measurements at high photon energies (>2000 eV), thereby providing detailed information about the whole nanoparticle structure with a great accuracy. The use of high photon energies furthermore allows us to investigate nanoparticles much larger than those studied thus far. This capability is a consequence of the much-increased mean free path of the photoelectron achieved at high excitation energies. Our results show that the actual structures of the synthesized nanoparticles are considerably different from the nominal, targeted structures, which can be post facto rationalized in terms of the reactivity of different constituents.