scholarly journals Mechanisms of fluorescence decays of colloidal CdSe–CdS/ZnS quantum dots unraveled by time-resolved fluorescence measurement

2015 ◽  
Vol 17 (41) ◽  
pp. 27588-27595 ◽  
Author(s):  
Hao Xu ◽  
Volodymyr Chmyrov ◽  
Jerker Widengren ◽  
Hjalmar Brismar ◽  
Ying Fu
Keyword(s):  
Quantum Dots ◽  
Radiative Recombination ◽  
Energy Relaxation ◽  
Fluorescence Decay ◽  
Fluorescence Measurement ◽  
Time Resolved Fluorescence ◽  
Time Resolved ◽  
Decay Spectrum

The fluorescence decay spectrum of colloidal CdSe-based quantum dots is characterized by energy relaxation and radiative recombination of photoexcited excitons.

Picosecond dynamics of excitation-energy relaxation of dye molecules in Langmuir–Blodgett monolayers

1990 ◽  
Vol 68 (9) ◽  
pp. 1013-1022 ◽  
Author(s):  
Naoto Tamai ◽  
Tomoko Yamazaki ◽  
Iwao Yamazaki
Keyword(s):  
Excitation Energy ◽  
Energy Transport ◽  
Stokes Shift ◽  
Energy Relaxation ◽  
Fluorescence Decay ◽  
Ultrametric Space ◽  
Time Resolved Fluorescence ◽  
Time Resolved ◽  
Langmuir Blodgett ◽  
Dye Molecule

Fluorescence-decay curves and time-resolved fluorescence spectra of N, N′-dioctadecylrhodamine B in Langmuir–Blodgett monolayers have been measured by means of a picosecond time-resolved fluorescence spectrophotometer. The excitation energy relaxation of the dye molecule in the monolayers was compared at 295 and 80 K in the concentration range from 0.02 to 31 mol%. The relaxation of the dynamic Stokes shift was found to decay logarithmically with time in longer time regions when the concentration of N, N′-dioctadecylrhodamine B < 5 mol%. The fluorescence decays can be analyzed by an equation including a stretched exponential function. The mechanisms of singlet excitation-energy relaxation were interpreted in terms of (i) the energy migration among energetically disordered monomer sites represented by ultrametric space (hierarchical energy distribution) or the Gaussian distribution of the density of excited states and (ii) the energy trapping by two-dimensional aggregates. It was found that the relaxation of the dynamic Stokes shift and the fluorescence decay can be estimated by the diffusion length of the excitation-energy transport.

scholarly journals Architecture of Polyglutamine-containing Fibrils from Time-resolved Fluorescence Decay

2014 ◽  
Vol 289 (39) ◽  
pp. 26817-26828 ◽  
Author(s):  
Christoph Röthlein ◽  
Markus S. Miettinen ◽  
Tejas Borwankar ◽  
Jörg Bürger ◽  
Thorsten Mielke ◽  
...  
Keyword(s):  
Fluorescence Decay ◽  
Time Resolved Fluorescence ◽  
Time Resolved

FRET Study Between Carbon Quantum Dots and Malachite Green by Steady-State and Time-Resolved Fluorescence Spectroscopy

2020 ◽  
Vol 10 (3) ◽  
pp. 178-188
Author(s):  
Bipin Rooj ◽  
Ankita Dutta ◽  
Debojyoti Mukherjee ◽  
Sahidul Islam ◽  
Ujjwal Mandal
Keyword(s):  
Quantum Dots ◽  
Energy Transfer ◽  
Fluorescence Spectroscopy ◽  
Malachite Green ◽  
Dye Degradation ◽  
Fluorescence Emission ◽  
Carbon Quantum Dots ◽  
Time Resolved Fluorescence ◽  
Physical Processes ◽  
Time Resolved

Background: Understanding the interaction between different organic dyes and carbon quantum dots helps us to understand several photo physical processes like electron transfer, energy transfer, molecular sensing, drug delivery and dye degradation processes etc. Objective: The primary objective of this study is to whether the carbon quantum dots can act as an electron donor and can participate in the different photo physical processes. Methods: In this work, Carbon Quantum Dots (CQDLs) are synthesized in most economical and simple carbonization method where petals of Nelumbo nucifera L. are used as a carbon precursor. The synthesized CQDLs were characterized by using experimental techniques like UV−Vis absorption, FT-IR, Transmission Electron Microscopy (TEM), steadystate and time-resolved fluorescence spectroscopy. Results: The spectral analysis shows that the so synthesized CQDLs are spherical in shape and its diameter is around 4.2 nm. It shows the fluorescence emission maximum at 495 nm with a quantum yield of 4%. In this work the interaction between Carbon Quantum Dots (CQDLs) and an organic dye Malachite Green (MG) is studied using fluorescence spectroscopic technique under ambient pH condition (At pH 7). The quenching mechanism of CQDLs with MG was investigated using Stern-Volmer equation and time-resolved fluorescence lifetime studies. The results show that the dominant process of fluorescence quenching is attributed to Forster Resonance Energy Transfer (FRET) having a donor acceptor distance of 53 Å where CQDLs act as a donor and MG acts as an acceptor. Conclusion: This work has a consequence that CQDLs can be used as a donor species for different photo physical processes such as photovoltaic cell, dye sensitized solar cell, and also for antioxidant activity study.

Steady-state and time-resolved fluorescence studies on interactions of carbon “quantum” dots with nitrotoluenes

2017 ◽  
Vol 468 ◽  
pp. 300-307 ◽  
Author(s):  
Gregory E. LeCroy ◽  
K.A. Shiral Fernando ◽  
Christopher E. Bunker ◽  
Ping Wang ◽  
Nicholas Tomlinson ◽  
...  
Keyword(s):  
Quantum Dots ◽  
Steady State ◽  
Carbon Quantum Dots ◽  
Time Resolved Fluorescence ◽  
Time Resolved ◽  
Fluorescence Studies

Maximum likelihood method for the analysis of time-resolved fluorescence decay curves

1991 ◽  
Vol 20 (5) ◽  
pp. 247-262 ◽  
Author(s):  
?eljko Bajzer ◽  
Terry M. Therneau ◽  
Joseph C. Sharp ◽  
Franklin G. Prendergast
Keyword(s):  
Maximum Likelihood ◽  
Maximum Likelihood Method ◽  
Fluorescence Decay ◽  
Likelihood Method ◽  
Time Resolved Fluorescence ◽  
Time Resolved
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