Carrier multiplication is demonstrated in a solid-state dispersion of germanium nanocrystals in a silicon–dioxide matrix.This is performed by comparing ultrafast photo-induced absorption transients at different pump ...Carrier multiplication is demonstrated in a solid-state dispersion of germanium nanocrystals in a silicon–dioxide matrix.This is performed by comparing ultrafast photo-induced absorption transients at different pump photon energies below and above the threshold energy for this process.The average germanium nanocrystal size is approximately 5–6 nm,as inferred from photoluminescence and Raman spectra.A carrier multiplication efficiency of approximately 190%is measured for photo-excitation at 2.8 times the optical bandgap of germanium nanocrystals,deduced from their photoluminescence spectra.展开更多
Aluminum is the third most abundant metal in the Earth’s crust.Despite its ubiquitous nature it is present in small amount in living organisms.Aluminum toxicity has been implicated in the pathogenesis of renal distin...Aluminum is the third most abundant metal in the Earth’s crust.Despite its ubiquitous nature it is present in small amount in living organisms.Aluminum toxicity has been implicated in the pathogenesis of renal distinct clinical syndromes,including progressive and fatal encephalopathy and bone diseases.In the present study,Al was selected for the analysis by complexometric method.This method was based on the formation of a red colored ternary complex by the reaction of Aluminum with Aluminon(Aurin tricarboxylic acid triammonium salt)in the presence of micellar medium.The ternary complex of Aluminum with the surfactant Triton X-100 shows a maximum absorbance at 530 nm wavelength at pH 4.0 while with the sodium dodecyl sulfate it shows a maximum absorbance at 525 nm and at pH 5.0.The reaction was proceeded by the variation in pH and concentrations of surfactants,aluminon,aluminum.Their effects on the reaction of aluminum with aluminon complex in micellar media were recorded by UV-visible spectrophotometer.The reaction was found to be extremely rapid at room temperature.The system obeys Lambert Beer’s law between 0.24 and 21.74μg/mL concentrations with Triton X-100.The values of slope,intercept and correlation coefficients were 0.07,0.348 and 0.989,respectively.The concentration varied between 0.24 and 24.14μg/mL with sodium dodecyl sulfate and the values of slope,intercept and correlation coefficients were 0.029,0.148 and 0.962,respectively.The foreign ion effect was also tested by keeping the constant concentration of metal ion and determining its concentration in the presence of different foreign ions.The method was also applied for the determination of Al(III)in pharmaceutical formulations and water samples,which showed an excellent resemblance between reported and obtained results.展开更多
基金This work was financially supported by the Foundation for Fundamental Research on Matter(FOM).
文摘Carrier multiplication is demonstrated in a solid-state dispersion of germanium nanocrystals in a silicon–dioxide matrix.This is performed by comparing ultrafast photo-induced absorption transients at different pump photon energies below and above the threshold energy for this process.The average germanium nanocrystal size is approximately 5–6 nm,as inferred from photoluminescence and Raman spectra.A carrier multiplication efficiency of approximately 190%is measured for photo-excitation at 2.8 times the optical bandgap of germanium nanocrystals,deduced from their photoluminescence spectra.
文摘Aluminum is the third most abundant metal in the Earth’s crust.Despite its ubiquitous nature it is present in small amount in living organisms.Aluminum toxicity has been implicated in the pathogenesis of renal distinct clinical syndromes,including progressive and fatal encephalopathy and bone diseases.In the present study,Al was selected for the analysis by complexometric method.This method was based on the formation of a red colored ternary complex by the reaction of Aluminum with Aluminon(Aurin tricarboxylic acid triammonium salt)in the presence of micellar medium.The ternary complex of Aluminum with the surfactant Triton X-100 shows a maximum absorbance at 530 nm wavelength at pH 4.0 while with the sodium dodecyl sulfate it shows a maximum absorbance at 525 nm and at pH 5.0.The reaction was proceeded by the variation in pH and concentrations of surfactants,aluminon,aluminum.Their effects on the reaction of aluminum with aluminon complex in micellar media were recorded by UV-visible spectrophotometer.The reaction was found to be extremely rapid at room temperature.The system obeys Lambert Beer’s law between 0.24 and 21.74μg/mL concentrations with Triton X-100.The values of slope,intercept and correlation coefficients were 0.07,0.348 and 0.989,respectively.The concentration varied between 0.24 and 24.14μg/mL with sodium dodecyl sulfate and the values of slope,intercept and correlation coefficients were 0.029,0.148 and 0.962,respectively.The foreign ion effect was also tested by keeping the constant concentration of metal ion and determining its concentration in the presence of different foreign ions.The method was also applied for the determination of Al(III)in pharmaceutical formulations and water samples,which showed an excellent resemblance between reported and obtained results.
