Nanorods spectroscopic properties

Figure 12.4 Fluorescence emission from biomolecules on ZnO NRs versus various control substrates after performing the identical biotreatment processes. (A) No fluorescence signal is detected on control substrates including glass, quartz, silicon oxide, silicon nanorods (SiNRs), and polymeric surfaces. On the other hand, strong fluorescence signal is observed from individual and striped ZnO NR platforms regardless of the spectroscopic properties fluorophores. (B) Normalized fluorescence intensity observed from biomolecules on various substrates. (C) Fluorescence...

Ishizumi and Kanemitsu (2005) have studied PL properties of Eu3+ doped ZnO nanorods fabricated by a microemulsion method. The PL of bound exciton recombination and ZnO defects was observed near 370 and 650 nm under 325-nm light excitation, but no emission of Eu3+ occurred. On the other hand, the sharp PL peaks due to the intra-4f transitions of Eu3+ ions appeared under nonresonant excitation below the band-gap energy of ZnO (454 and 457.9 nm) in addition to direct excitation to 5D2 (465.8 nm). Therefore the authors concluded that the energy transfer occurs from the ZnO nanorods to Eu3+ ions through ZnO-defect states. This energy transfer mechanism seems very different from the previous one and more spectroscopic evidence is required to confirm it. 

The geometric and surface properties of supported nanostructures (nanoparticles, nanorods, and other nanoscale objects) are closely related to many of their important applications. On relatively inert substrates, such as graphite, oxides, and nitrides, many nanostmctures can be fabricated in a nearly free-standing state by simple physical vapor deposition, and be characterized using electron microscopy, scanning probe microscopy, and various spectroscopic methods. Their intrinsic properties, including the interaction among them, can be measured. In addition, the nanostructures on an inert support provide us with an arena to examine their interactions with other nanoobjects, such as biomolecules, without the influence of a solution. 

---