Nanodiamonds fluorescence

Figure 5.22 Fluorescence spectrum of detonation nanodiamond with the luminescence maximum at 364 nm ( Springer / MAIK Nauka 1997).

Defects and impurities, in general, play a comparably important role for the luminescence properties of nanodiamond like they do for the bulk material. Owing to their existence, there are electronic states situated within the bandgap, which allow for inducing luminescence in nanodiamond samples also with longer wave radiation. Upon excitation with wavelengths between 300 and 365 nm, fluorescence bands are observed at more than 400 nm. They arise from various nitrogen defects. In comparison to bulk diamond, the Ufetime of the excited states is rather short, which possibly is due to the effect of surface states and to the increased density of excitons on the surface. 

It is especially nitrogen defects that may be detected this way, that is, by fluorescence microscopy (Figure 5.46). Defective nanodiamond particles with surface functionalization may also be employed as fluorescence label in in vivo experiments, so a system complementary to the metal chalcogenide quantum dots usually applied is available here. The nanodiamond adducts in these processes are characterized by their small particle size, stable fluorescence, and (at least according to current knowledge) by their nontoxicity. 

A multitude of potential further applications opens up to nanodiamond materials in a variety of technological areas. Examples hitherto described include, among others, the preparation of field emitters for display uses. Current research focuses, for instance, on utilizing the lattice defects and the resulting fluorescence as weU as the unpaired spins. More applications are expected to emerge in the field of scratch-resistant transparent coatings. Moreover, it should be possible to realize... 

Figure 5.46 (a) N-V-defect induced fluorescence of nanodiamond inside living cells (bright spots) (b) corresponding fluorescence spectrum of the diamond nanoparticles under test ( ACS 2005). 

Physical properties Nanodiamond stands out for its great hardness and surface conductivity, for field emission characteristics and for the possible fluorescence of defect centers. Spectroscopic examinations revealed both the band structure and the structural properties. 

L.C. Cheng, H.M. Chen, T.C. Lai, Y.C. Chan, R.S. Liu, Targeting polymeric fluorescent nanodiamond-gold/silver multi-functional nanoparticles as a light-transforming hyperthermia reagent for cancer cells. Nanoscale 5 (9) (2013) 3931-3940. 

Zhang Q, Mochalin VN, Neitzel 1, Knoke lY, Han J, King CA, et al. Fluorescent PLLA-nanodiamond composites for bone tissue engineering. Biomaterials 2011 32 87-94. 

V.N. Mochahn, and Y. Gogotsi, Wet chemistry route to hydrophobic blue fluorescent nanodiamond. Journal of American Chemical Society, 131 (13), 4594-4595, 2009. 

Komatsu, N. Ito, M. Surface modified nanodiamond, method for its manufacture, and nanodiamond which is surface modified for fluorescent labeling. Jpn. Kokai Tokkyo Koho JP 2010202458, 2010. 

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