Photoluminescence and Scintillation Properties of Pb2+ Based Quantum Dots in CsCI Host Crystal

ABSTRACTThe spectral and kinetic properties of photoluminescence of Pb2+ aggregated phase in CsC1 host, together with scintillation characteristics of CsCI:Pb crystals, are reported in the 10 - 300 K temperature range. Absorption, steady-state excitation and emission spectra of Pb2+ phase in CsCI host are similar to those of CsPbCl3 bulk crystal (emission peak at 419 nm at 10 K). The decay of the 421 nm luminescence of the Pb2+ phase in CsCl shows single exponential behavior with extremely short decay time of 40 ps at 421 nm and 10 K,which is considerably shorter than the decay times found in the decay of CsPbCl3 bulk emission (0.45, 2.8 and 12 ns at 418 nm and 10 K). In the scintillation decay of CsCI:Pb, two components with 0.95-1 ns and 2-3 ns decay times were found and no slower component is present at room temperature.

Download Full-text

Quantum Dots—Assisted 2D Fluorescence for Pattern Based Sensing of Amino Acids, Oligopeptides and Neurotransmitters

Sensors ◽

10.3390/s19173655 ◽

2019 ◽

Vol 19 (17) ◽

pp. 3655 ◽

Cited By ~ 1

Author(s):

Marcin Zabadaj ◽

Patrycja Ciosek-Skibińska

Keyword(s):

Amino Acids ◽

Quantum Dots ◽

Emission Spectra ◽

Specific Interactions ◽

High Quantum Yield ◽

Huge Amount ◽

Broad Absorption ◽

Amount Of Information ◽

Decay Times ◽

Proof Of Principle

Quantum dots (QDs) are very attractive nanomaterials for analytical chemistry, due to high photostability, large surface area featuring numerous ways of bioconjugation with biomolecules, usually high quantum yield and long decay times. Their broad absorption spectra and narrow, sharp emission spectra of size-tunable fluorescence make them ideal tools for pattern-based sensing. However, almost always they are applied for specific sensing with zero-dimensional (0D) signal reporting (only peak heights or peak shifts are considered), without taking advantage of greater amount of information hidden in 1D signal (emission spectra), or huge amount of information hidden in 2D fluorescence maps (Excitation-Emission Matrixes, EEMs). Therefore, in this work we propose opposite strategy—non-specific interactions of QDs, which are usually avoided and regarded as their disadvantage, were exploited here for 2D fluorescence fingerprinting. Analyte-specific multivariate fluorescence response of QDs is decoded with the use of Partial Least Squares—Discriminant Analysis. Even though only one type of QDs is studied, the proposed pattern-based method enables to obtain satisfactory accuracy for all studied compounds—various neurotransmitters, amino-acids and oligopeptides. This is a proof of principle of the possibility of the identification of various bioanalytes by such fluorescence fingerprinting with the use of QDs.

Download Full-text

Steady-state and Time-resolved Spectroscopic Studies of Benzanilides

Zeitschrift für Naturforschung A ◽

10.1515/zna-1999-8-909 ◽

1999 ◽

Vol 54 (8-9) ◽

pp. 495-502 ◽

Cited By ~ 1

Author(s):

Józef Heldt ◽

Janina R. Heldt ◽

Jerzy Kamiński

Keyword(s):

Excited State ◽

Charge Transfer ◽

Steady State ◽

Proton Transfer ◽

Room Temperature ◽

Spectroscopic Studies ◽

Fluorescence Band ◽

Polar Solvents ◽

Time Resolved ◽

Decay Times

Steady-state and time-resolved spectroscopic studies of benzanilide (I) and jV-methylbenzanilide (II)were performed at 298 and 77 K in various solvents. The results indicate that benzanilide fluorescencein non-polar solvents at room temperature involves three independent modes of emission: F1 (LE) normalfluorescence from the initially excited state S1 (LE) with λmax = 320 nm, F2´(PT) fluorescence from the proton transfer tautomer with λmax = 468 nm, F2″CT) fluorescence from the species where intramolecular charge transfer appears, with λmax = 510 nm. At 77 K in MCH a new fluorescence band, Fag, appears at λmax=415 nm instead of the F2(PT) and F2″CT) fluorescence. This new emission originates from benzanilide dipolar aggregates or cis-imidol dimers. The decay times of these emission modes aredifferent.N-methylbenzanilide, dissolved in nonpopular and weakly polar solvents at room temperature and at77 K, shows only two fluorescence modes, i.e., the normal and the charge-transfer emissions at 320 nmand 520 nm, respectively. The fluorescence is deactivated with two decay times, 30 ps and 2.05 ns, inMCH solution.

Download Full-text

Asymmetrically strained quantum dots with non-fluctuating single-dot emission spectra and subthermal room-temperature linewidths

Nature Materials ◽

10.1038/s41563-018-0254-7 ◽

2019 ◽

Vol 18 (3) ◽

pp. 249-255 ◽

Cited By ~ 30

Author(s):

Young-Shin Park ◽

Jaehoon Lim ◽

Victor I. Klimov

Keyword(s):

Quantum Dots ◽

Room Temperature ◽

Emission Spectra

Download Full-text

Growing Features and Luminescence of Bi3+ Ions in Gd3Ga5O12 Epitaxial Films

Solid State Phenomena ◽

10.4028/www.scientific.net/ssp.200.215 ◽

2013 ◽

Vol 200 ◽

pp. 215-219 ◽

Cited By ~ 5

Author(s):

Andriy P. Luchechko ◽

Igor I. Syvorotka ◽

Yaroslav Zakharko ◽

I.M. Syvorotka

Keyword(s):

Room Temperature ◽

Emission Spectra ◽

Luminescent Properties ◽

Growth Conditions ◽

Excitation Wavelength ◽

Decay Kinetics ◽

Exponential Behavior ◽

Crystalline Films ◽

Kinetics Of ◽

Luminescence Decay Kinetics

Abstract. Excitation and emission spectra under UV and X-ray excitations, as well as the luminescence decay kinetics of Gd3Ga5O12: Bi single crystalline films were studied. The emission spectra observed in the spectral region 350-700 nm at room temperature consist two elementary bands peaked at 446 and 521 nm. The influence of growth conditions on the luminescent properties of Gd3Ga5O12: Bi3+ garnet have been revealed. The integral and relative intensities of the luminescence bands depend on the excitation wavelength. The Bi3+ decay curves of all investigated films show non-single exponential behavior at room temperature.

Download Full-text

Controlling Growth of InAs/GaAs Self-Assembled Quantum Dots to Give 1.3 μm Room Temperature Emission

MRS Proceedings ◽

10.1557/proc-571-273 ◽

1999 ◽

Vol 571 ◽

Author(s):

Surama Malik ◽

Philip Siverns ◽

David Childs ◽

Christine Roberts ◽

Jean-Michel Hartmann ◽

...

Keyword(s):

Quantum Dots ◽

Excited States ◽

Room Temperature ◽

Growth Parameters ◽

High Growth ◽

Growth Conditions ◽

Time Resolved ◽

Confining Potential ◽

Decay Times ◽

Self Assembled

ABSTRACTWe have investigated the extent to which the emission wavelength of self-assembled InAs/GaAs quantum dots can be controlled by growth parameters using conventional solid source MBE. Changing from conventionally high growth rates to a very low growth rate (LGR) and a relatively high substrate temperature, tunes the photoluminescence (PL) emission from 1.1 μm to 1.3 μm at room temperature. Atomic force micrographs obtained from uncapped samples reveal that these LGRQDs are larger, lower in density and extremely uniform in size. The improved size uniformity is reflected in the reduction of the PL linewidth from 78 meV to 22 meV. Under conditions of high excitation, emission from the ground and two excited states each separated by ∼70 meV is observed. This implies a parabolic confining potential. Time resolved photoluminescence (TRPL) measurements of dots grown under the various growth conditions yield radiative lifetimes which reflect the depth of the confining potential. A comparison of the decay times measured for the excited states show that the relaxation of carriers within the dots cannot be ascribed to phonon effects.

Download Full-text

Photoluminescence of Eu3+ Ions in Lu3(Ga,In)5O12:Eu3+ Films Grown by LPE Method

Solid State Phenomena ◽

10.4028/www.scientific.net/ssp.230.166 ◽

2015 ◽

Vol 230 ◽

pp. 166-171

Author(s):

Andriy Luchechko ◽

I.I. Syvorotka ◽

Yaroslav Zakharko ◽

Igor M. Syvorotka

Keyword(s):

Room Temperature ◽

Emission Spectra ◽

Epitaxial Films ◽

Decay Kinetics ◽

Exponential Behavior ◽

Efficient Energy Transfer ◽

Kinetics Of ◽

Uv Excitation ◽

The Eu ◽

Luminescence Decay Kinetics

High quality thin epitaxial films of Lu3(Ga,In)5O12:Eu3+ were grown by liquid phase epitaxy (LPE) method from Bi2O3-based flux. Excitation and emission spectra as well as luminescence decay kinetics of Lu3(Ga,In)5O12:Eu3+ epitaxial films were studied under UV excitation. The photoluminescence spectra of Eu3+ ions in Lu3(Ga,In)5O12:Eu3+ are characteristic to the f→f transition in the Eu3+ ions that occupied dodecahedral sites in the garnet structure. The efficient energy transfer between Bi3+→Eu3+ is observed at the excitation of Lu3(Ga,In)5O12:Eu3+ films in Bi3+ excitation band with maximum at 288 nm. The Eu3+ decay curves of all investigated films show non-single exponential behavior at room temperature.

Download Full-text

Photo and X-Rays Induced Optical Luminescence of Sm3+-Doped Bismuth Borate Glasses

Advanced Materials Research ◽

10.4028/www.scientific.net/amr.979.413 ◽

2014 ◽

Vol 979 ◽

pp. 413-416

Author(s):

Pruittipol Limkitjaroenporn ◽

Kitipun Boonin ◽

Patarawagee Yasaka ◽

Hong Joo Kim ◽

Jakrapong Kaewkhao

Keyword(s):

Emission Spectra ◽

Borate Glasses ◽

X Rays ◽

Melt Quenching ◽

Exponential Behavior ◽

Bismuth Borate ◽

Broad Emission ◽

Optical Luminescence ◽

The Relationship ◽

Single Exponential

Samarium doped bismuth borate glasses with composition 66.7Bi2O3: (33.3-x)B2O3: x Sm2O3(where x = 0.5, 1.0, 1.5, 2.0 and 2.5 mol%) have been prepared by melt quenching technique. The physical, optical, photoluminescence and X-rays luminescence properties were investigated. The densities and molar volumes were not found the relationship with the increasing samarium concentration. The photoluminescence emission spectra shows broad emission bands due to4G5/2→6HJ(J=5/2, 7/2, 9/2, 11/2) transitions when excited with 473 nm. The decay curves of4G5/2level exhibited single exponential behavior for all the concentrations and the measured lifetimes are found to depend strongly on samarium concentrations. The X-rays emission spectra were measured at the X-rays of intensity 100kV and current 1.5mA. The emission peaks observed at 569, 598, 641 and 705 nm. And the intensity of luminescence increase as samarium concentration increase.

Download Full-text

Studies on Water in the Hydration Chamber of a Modified Electron Microscope

Proceedings, annual meeting, Electron Microscopy Society of America ◽

10.1017/s0424820100069715 ◽

1970 ◽

Vol 28 ◽

pp. 544-545

Author(s):

R. C. Moretz ◽

G. G. Hausner ◽

D. F. Parsons

Keyword(s):

Thin Film ◽

Thin Films ◽

Electron Microscope ◽

Steady State ◽

Room Temperature ◽

Small Mass ◽

Equilibrium Pressure ◽

Biological Objects ◽

Mechanical Pump ◽

Differential Pumping

Use of the electron microscope to examine wet objects is possible due to the small mass thickness of the equilibrium pressure of water vapor at room temperature. Previous attempts to examine hydrated biological objects and water itself used a chamber consisting of two small apertures sealed by two thin films. Extensive work in our laboratory showed that such films have an 80% failure rate when wet. Using the principle of differential pumping of the microscope column, we can use open apertures in place of thin film windows.Fig. 1 shows the modified Siemens la specimen chamber with the connections to the water supply and the auxiliary pumping station. A mechanical pump is connected to the vapor supply via a 100μ aperture to maintain steady-state conditions.

Download Full-text