Magnetic iron oxide nanoclusters with tunable optical response

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• 作者：Athanasia Kostopoulou^a ; ^b ; ^{akosto@iesl.forth.gr"" rel=""nofollow} ; Ioannis Tsiaoussis^c ; Alexandros Lappas^a ; ^{lappas@iesl.forth.gr"" rel=""nofollow}
• 关键词：Magnetic nanoclusters ; Photonic crystals ; Iron oxide nanocrystals ; Secondary structures
• 刊名：Photonics and Nanostructures - Fundamentals and Applications
• 出版年：2011
• 出版时间：April 2011
• 年：2011
• 卷：9
• 期：2
• 页码：201-206
• 全文大小：453 K

文摘

We have developed a modified synthetic protocol for the growth of monodispersed, superparamagnetic, flower-like colloidal nanoclusters (CNCs), which are consisted of smaller iron oxide nanocrystals with adjustable size. We show that their optical properties can be tuned by applying an external magnetic field. The latter controls the subtle balance of the CNCs’ mutual interactions (magnetic versus electrostatic) and drives their assembly in aqueous media. Spectrophotometric measurements reveal that a diffuse reflectance maximum, in the visible range, is related to the CNCs organization. As the strength of the external magnetic field increases, in the range 160–600 G, the spectral weight of this feature shifts towards the blue region of the spectrum. The induced photonic crystal-like response entails a remarkable magneto-optical behavior, closely associated with the size-dependent characteristics of the CNCs ensemble. Such materials pave the way for promising technological implementations in photonics.