We describe the synthesis of glass incorporating photoluminescent semiconductor nanocrystals through a sol-gel processing and discuss the characterization of their properties. CdTe nanocrystals with a mean size between 3 and 6 nm are embedded in a glass matrix made from silane coupling agent functionalized with amine groups. The synthesis process was optimized to avoid nanocrystals agglomeration and to prevent surface deterioration of nanocrystals. The nanocrystals embedded in the glass matrix remained almost unmodified during preparation. Their photoluminescent spectra were about 41 to 65 nm in width at half maximum and can be tuned from green to red with luminescent efficiency up to 41%. The nanocrystals embedded in glass exhibit enhanced long-term stability over several months keeping. They also display high stability even after heat treatment.
Photochemical hole-burning phenomenon is discussed with regard to its application in high-density optical memory systems. A theory is introduced to express the recording density limit of this memory as a function of readout time and material parameters. Experiments in dye-doped polymer systems show that the main factor limiting the attainable recording density is hole filling brought about by the irradiation of another wavelength. This hole filling occurs because the doped chromophore in an amorphous matrix has various energy levels. Extent of hole filling is related to the molecular structure of the chromophore. When a chromophore is rigid and does not have a low energy vibration mode, the extent of filling becomes smaller.
KEYWORDS: Near infrared, Blood, Tissue optics, Time resolved spectroscopy, In vitro testing, Tissues, Oxygen, In vivo imaging, Scattering, Statistical analysis
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