The role of mid-gap states in all-inorganic CsPbBr3 nanoparticle one photon up-conversion

2018 ◽  
Vol 54 (50) ◽  
pp. 6851-6854 ◽  
Author(s):  
Benjamin J. Roman ◽  
Matthew Sheldon
Keyword(s):  
Quantum Yield ◽  
Energy Of Activation ◽  
Free Surfaces ◽  
Gap States ◽  
Arrhenius Analysis

CsPbBr3 nanoparticles that have been treated with NH4SCN to produce essentially trap-free surfaces show an increase of one photon up-conversion quantum yield with little change to the up-conversion energy of activation, as estimated using an Arrhenius analysis.

scholarly journals Спектральное исследование фотодинамических процессов в системе C-=SUB=-60-=/SUB=--(н-метилпирролидон)-кислород

2021 ◽  
Vol 129 (12) ◽  
pp. 1493
Author(s):  
И.М. Кисляков ◽  
И.М. Белоусова ◽  
В.М. Киселев ◽  
И.В. Багров ◽  
А.М. Стародубцев ◽  
...  
Keyword(s):  
Quantum Yield ◽  
Singlet Oxygen ◽  
Transient Absorption ◽  
Rapid Quenching ◽  
Quenching Rate ◽  
Broadband Absorption ◽  
Laser Pumping ◽  
Time Dependencies ◽  
Quenching Rate Constant

The processes of photoexcitation and energy transfer in an air-saturated solution of fullerene C60 in n-methylpyrrolidone are studied. With femtosecond laser pumping at a wavelength л(p) = 520 nm, transient absorption spectra were obtained in the range 470-750 nm. Broadband absorption is observed at л > 650 nm as a result of aggregation of fullerene molecules, characterized by a short decay time of the picosecond scale. The analysis of the time dependencies indicates the presence of several processes. Within the proposed interpretation, we state a remarkable reduction in the time of singlet-triplet intersystem crossing with an increase of nanocluster size while the rapid quenching of the singlet state varies only slightly. The quantum yield of the triplet state can therefore increase, reaching 0.14. The phosphorescence spectra of singlet oxygen with a maximum at л = 1276 nm were measured with LED excitation at various wavelengths in the range 370-625 nm. The lifetime and quenching rate constant of singlet oxygen in n-methylpyrrolidone are determined. The combined quantum yield of triplet fullerene and singlet oxygen in n-methylpyrrolidone is estimated as 0.74. The efficiency spectra of the singlet oxygen photosensibilization in the C60-(n-methylpyrrolidone)-oxygen system are obtained, indicating the increasing role of large nanoclusters in this process during aging of the solution.

Di-amidosils with tunable structure, morphology and emission quantum yield: the role of hydrogen bonding

2015 ◽  
Vol 3 (26) ◽  
pp. 6844-6861 ◽  
Author(s):  
S. C. Nunes ◽  
J. Hümmer ◽  
V. T. Freitas ◽  
R. A. S. Ferreira ◽  
L. D. Carlos ◽  
...  
Keyword(s):  
Quantum Yield ◽  
Variable Structure ◽  
Photoluminescence Properties ◽  
Experimental Conditions ◽  
Yield Value ◽  
Structure Morphology ◽  
Tunable Structure ◽  
Degree Of Order ◽  
Emission Quantum Yield

Di-amidosil hybrids with variable structure, morphology and photoluminescence properties were obtained using different experimental conditions. A correlation between the emission quantum yield value and the degree of order of the amide–amide hydrogen-bonded array was established for mono- and di-amidosils.

scholarly journals The Quantum Yield of Photosynthesis in Porphyridium cruentum, and the Role of Chlorophyll a in the Photosynthesis of Red Algae

1959 ◽  
Vol 43 (2) ◽  
pp. 251-264 ◽  
Author(s):  
Marcia Brody ◽  
Robert Emerson
Keyword(s):  
Quantum Yield ◽  
Red Algae ◽  
Photosynthetic Efficiency ◽  
Red Alga ◽  
Porphyridium Cruentum ◽  
Maximum Efficiency ◽  
Minor Role ◽  
Algal Groups ◽  
A Minor

Quantum yield measurements were made with the red alga Porphyridium cruentum, cultured so as to give different proportions of chlorophyll and phycobilins. Totally absorbing suspensions were used so that there was no uncertainty in the amount of energy absorbed. These measurements have shown that chlorophyll, in this alga, has a photosynthetic efficiency as high as in other algal groups, and higher than the phycobilins—at least at wave lengths shorter than about 650 mµ. Wave lengths longer than this are beyond the range of maximum efficiency of chlorophyll. Under specified conditions of temperature and supplementary light full efficiency may be extended to longer wave lengths. The results of these measurements have made it unnecessary to suppose that in red algae chlorophyll plays a minor role while the phycobilins are the photosynthetic sensitizers of primary importance.

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