In this paper, we show a low temperature normal pressure synthesis of a blue emissive organic fluorophore. The organic fluorophore molecule - 1, 2, 3, 5-tetrahydro-5-oxo-imidazo [1, 2-a] pyridine-7-carboxylic acid (IPCA) - consists of derivatives of imidazole and benzoic rings with a carboxylic group. The molecule has a strong emission maximum at around 450 nm when excitation of 350 nm us used and is correlated with PL spectra of carbon nanoparticles. The quantum yield was found to be relatively high: around 55%. IPCA luminescent properties are similar to the reported for some carbon nanostructures, obtained via hydrothermal synthesis from citric acid and ethylenediamine.
Photoluminescent (PL) carbon nanoparticles (CNPs) have been synthesized by one-step microwave irradiation from water solution of sodium dextran sulfate (DSS) as the sole carbon source. Microwave (MW) method is very simple and cheap and it provides fast synthesis of CNPs. We have varied synthesis time for obtaining high luminescent CNPs. The synthesized CNPs exhibit excitation-dependent photoluminescent. Final CNPs water solution has a blue- green luminescence. CNPs have low cytotoxicity, good photostability and can be potentially suitable candidates for bioimaging, analysis or analytical tests.
Photoluminescent (PL) properties of carbon-based nanomaterials obtained on the base of sodium dextran sulfate (DS) were compared. DS water solution, dry powder and co-precipitated inside pores of CaCO<sub>3</sub> microparticles solution were thermally treated and clear difference between these materials was found. Effect of spatial restriction of CaCO<sub>3</sub> pores showed itself in the identity of PL properties for material, obtained by thermal and hydrothermal treatment; in the absence of CaCO<sub>3</sub> microparticles the PL spectra were quite different.
New porous silicon preparation technique has been suggested and realized with using vapor etching of silicon in iodine and HF contained vapors. It has been shown that vapor etching allows the preparation of luminescent porous layers on heavy doped (n<sup>++</sup> and p<sup>++</sup> type) silicon. Comparison of Raman and CW excitation PL measurements of vapor etched porous layer with typical anodized luminescent porous silicon indicated that they have in general similar structural and PL properties. Time resolved photoluminescence measurements reveal however that excitation recombination for iodine contained vapor etched samples is two times faster with higher photoluminescence efficiency, which can be interpreted as increasing of radiative recombination rate for luminescence centers in new nanocrystalline silicon.