scholarly journals Laser-induced fluorescence measurements on CdSe quantum dots

2010 ◽  
Vol 4 (1) ◽  
pp. 33-38 ◽  
Author(s):  
Zoltan Győri ◽  
Dávid Tátrai ◽  
Ferenc Sarlós ◽  
Gábor Szabó ◽  
Ákos Kukovecz ◽  
...  
Keyword(s):  
Quantum Dots ◽  
Laser System ◽  
Laser Induced Fluorescence ◽  
Growth Time ◽  
Single Shot ◽  
Cdse Quantum Dots ◽  
Time Resolved ◽  
Fluorescence Measurements ◽  
Decay Times ◽  
Growth Method

In this paper, we report on photoluminescence decay measurements on CdSe quantum dots (QDs) as a function of size in the diameter range of 2.1 to 3.5 nm. The nanoparticles were synthesized by the kinetic growth method from CdO and elemental Se precursors. We studied the effects of growth time on the diameter, emission spectrum and the fluorescence lifetime of the synthesized QDs. The decay time measurements were performed using single shot time-resolved laser-induced fluorescence techniques using a Nd:YAG laser system. Two different decay times were measured on each CdSe sample, a fast one and a relatively slow one. The slow decay was found to be size dependent whereas the fast one was independent of the QD diameter. .

Optical Properties of Heavily Doped n-type CdSe Quantum Dots for Intersubband Device Applications

2006 ◽  
Vol 959 ◽  
Author(s):  
Shengkun Zhang ◽  
Xuecong Zhou ◽  
Aidong Shen ◽  
Wubao Wang ◽  
Robert Alfano ◽  
...  
Keyword(s):  
Quantum Dots ◽  
Optical Properties ◽  
Quantum Wells ◽  
Ir Absorption ◽  
Cdse Quantum Dots ◽  
Nonradiative Recombination ◽  
Time Resolved ◽  
Luminescence Efficiency ◽  
Decay Times ◽  
Heavily Doped

ABSTRACTIn this research, interband and intersubband optical properties of heavily doped n-type CdSe quantum dots were investigated by temperature dependent photoluminescence (PL) spectroscopy, picosecond time-resolved PL spectroscopy and Fourier transform infrared (FTIR) spectroscopy. Two doped and one undoped CdSe quantum dot samples with multiple QD layers were grown over ZnCdMgSe barrier layers on InP (001) substrate by molecular beam epitaxy. Heavy doping leads to decreasing of activation energy of nonradiative recombination centers, however, does not affect the luminescence efficiency of doped quantum wells. Time resolved PL experiments show that the PL decay times of the doped samples have weak dependence on well width and are much longer than that of the undoped sample. The two doped CdSe QD samples show strong Intersubband IR absorption that peaked at 2.54 μm, 2.69 μm and 3.51 μm. The ISB absorption is found to be strongly polarization dependent due to the large size of the QDs.

scholarly journals Time-resolved laser-induced fluorescence measurements of Rydberg states in Lu I and comparison with theory

2003 ◽  
Vol 36 (3) ◽  
pp. 479-487 ◽  
Author(s):  
Zhenwen Dai ◽  
Jiang Zhankui ◽  
Huailiang Xu ◽  
Zhang Zhiguo ◽  
S Svanberg ◽  
...  
Keyword(s):  
Rydberg States ◽  
Laser Induced Fluorescence ◽  
Time Resolved ◽  
Fluorescence Measurements

Solution Precipitation of CdSe Quantum Dots

1992 ◽  
Vol 283 ◽  
Author(s):  
Cherie R. Kagan ◽  
Michael J. Cima
Keyword(s):  
Quantum Dots ◽  
Elevated Temperatures ◽  
Heat Treating ◽  
Solution Temperature ◽  
Supersaturated Solution ◽  
Thermal Mass ◽  
Cdse Quantum Dots ◽  
Glass Film ◽  
Optical Absorbance ◽  
Fluorescence Measurements

ABSTRACTSynthesis of CdSe quantum dots with a high degree of monodispersity is achieved by nucleation from a supersaturated solution followed by growth to the desired particle size. The effects of temperature on the kinetic mechanisms of nucleation and growth were observed. A reaction vessel equipped with a low thermal mass internal heating element enabled controlled ramping of the solution temperature during the reaction. Nanocrystallite diameter is determined by the reaction time and the solution temperature during particle growth.A method was developed to fabricate ∼1μm thick glass films containing ∼3 vol% CdSe quantum dots. A sol was prepared by mixing a silica organosol with a nanocrystallite dispersion of CdSe and was applied to amorphous quartz substrates by spin-coating. The sols were dried at elevated temperatures in a nitrogen atmosphere. Optical absorbance and fluorescence measurements of the glass film were used to characterize the optical properties of the embedded nanocrystallites. Comparison of the excitonic absorbance of the quantum dot dispersion and the doped glass film shows that particle monodispersity is maintained upon incorporation into the dielectric matrix. Stokes shifts in the band-to-band fluorescence relative to the film absorbance were measured. Shifts in the wavelength of the excitonic absorbance and fluorescence were observed upon incorporation of the quantum dots into the glass film and upon heat treating the glass film to elevated temperatures.

Time-resolved, 3D, laser-induced fluorescence measurements of fine-structure passive scalar mixing in a tubular reactor

2004 ◽  
Vol 37 (1) ◽  
pp. 1-21 ◽  
Author(s):  
E. Van Vliet ◽  
S. M. Van Bergen ◽  
J. J. Derksen ◽  
L. M. Portela ◽  
H. E. A. Van den Akker
Keyword(s):  
Fine Structure ◽  
Tubular Reactor ◽  
Passive Scalar ◽  
Laser Induced Fluorescence ◽  
Scalar Mixing ◽  
Time Resolved ◽  
Fluorescence Measurements

scholarly journals Infrared–ultraviolet double resonance measurements on the temperature dependence of rotational and vibrational self-relaxation of NO(X2Π, υ = 2,j)

1994 ◽  
Vol 72 (3) ◽  
pp. 606-611 ◽  
Author(s):  
Michael J. Frost ◽  
Meezanul Islam ◽  
Ian W.M. Smith
Keyword(s):  
Ground State ◽  
Energy Exchange ◽  
Double Resonance ◽  
Excited Level ◽  
Laser Induced Fluorescence ◽  
Spin Orbit ◽  
Time Resolved ◽  
Fluorescence Measurements ◽  
Direct Measurements ◽  
Electronic Ground

Infrared–ultraviolet double resonance experiments have been performed to measure the rates of rotational and vibrational self-relaxation in NO at three temperatures: 295 K, 200 K, and 77 K. Pulses of tunable infrared radiation from an optical parameteric oscillator have been used to excite molecules into selected rotational levels (j = 0.5, 6.5, or 15.5) in the [Formula: see text] vibronic component of the X2Π electronic ground state of NO. Loss of population from the initially excited level was observed by making time-resolved laser-induced fluorescence measurements on appropriate lines in the A2Σ+ − X2Π(2,2) band. The rate constants for removal of population from specific rovibronic levels are essentially independent of j and at 295 K agree well with previous direct measurements on a range of υ, j levels. The rotationally thermalized population in υ = 2 relaxes by vibration–vibration (V–V) energy exchange, NO(υ = 2) + NO(υ = 0) → 2 NO(υ = 1), at a rate which is almost independent of temperature and which seems to be uninfluenced by the presence of spin-orbit degeneracy in, and attractive forces between, the NO collision partners.

scholarly journals Preparation of CdSe Quantum Dots using kinetic growth method

2014 ◽  
Vol 7 (9) ◽  
pp. 41-44
Author(s):  
Mekandan M ◽  
◽  
Senthil Kumar P ◽  
Sarala Ruby ◽  
Ponraj vikaram
Keyword(s):  
Quantum Dots ◽  
Cdse Quantum Dots ◽  
Kinetic Growth ◽  
Growth Method

scholarly journals Electron Tunneling from Colloidal CdSe Quantum Dots to ZnO Nanowires Studied by Time-Resolved Luminescence and Photoconductivity Experiments

2015 ◽  
Vol 119 (27) ◽  
pp. 15627-15635 ◽  
Author(s):  
Stephanie Bley ◽  
Michael Diez ◽  
Friederike Albrecht ◽  
Sebastian Resch ◽  
Siegfried R. Waldvogel ◽  
...  
Keyword(s):  
Quantum Dots ◽  
Electron Tunneling ◽  
Zno Nanowires ◽  
Cdse Quantum Dots ◽  
Time Resolved

scholarly journals Time-resolved terahertz spectroscopy reveals the influence of charged sensitizing quantum dots on the electron dynamics in ZnO

2017 ◽  
Vol 19 (8) ◽  
pp. 6006-6012 ◽  
Author(s):  
Sesha Bamini N. ◽  
Hynek Němec ◽  
Karel Žídek ◽  
Mohamed Abdellah ◽  
Mohammed J. Al-Marri ◽  
...  
Keyword(s):  
Quantum Dots ◽  
Charge Carrier ◽  
Transient Absorption ◽  
Terahertz Spectroscopy ◽  
Carrier Dynamics ◽  
Transient Absorption Spectroscopy ◽  
Cdse Quantum Dots ◽  
Electron Dynamics ◽  
Time Resolved ◽  
Charge Carrier Dynamics

Photoinitiated charge carrier dynamics in ZnO nanoparticles sensitized by CdSe quantum dots is studied using transient absorption spectroscopy and time-resolved terahertz spectroscopy.

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