Ultraviolet free-exciton light emission in Er-passivated SnO2 nanocrystals in silica

2006 ◽  
Vol 89 (15) ◽  
pp. 153126 ◽  
Author(s):  
S. Brovelli ◽  
N. Chiodini ◽  
F. Meinardi ◽  
A. Lauria ◽  
A. Paleari
Keyword(s):  
Light Emission ◽  
Free Exciton ◽  
Sno2 Nanocrystals

Nanocrystalline Silicon for Optoelectronic Applications

MRS Bulletin ◽  
1998 ◽  
Vol 23 (4) ◽  
pp. 33-38 ◽  
Author(s):  
Leonid Tsybeskov
Keyword(s):  
Binding Energy ◽  
Light Emission ◽  
Crystalline Silicon ◽  
Free Exciton ◽  
Nanocrystalline Silicon ◽  
Momentum Conservation ◽  
Exciton Binding Energy ◽  
Electron Hole ◽  
Energy Plus ◽  
Hole Recombination

Light emission in silicon has been intensively investigated since the 1950s when crystalline silicon (c-Si) was recognized as the dominant material in microelectronics. Silicon is an indirect-bandgap semiconductor and momentum conservation requires phonon assistance in radiative electron-hole recombination (Figure 1a, top left). Because phonons carry a momentum and an energy, the typical signature of phonon-assisted recombination is several peaks in the photoluminescence (PL) spectra at low temperature. These PL peaks are called “phonon replicas.” High-purity c-Si PL is caused by free-exciton self-annihilation with the exciton binding energy of ~11 meV. The TO-phonon contribution in conservation processes is most significant, and the main PL peak (~1.1 eV) is shifted from the bandgap value (~1.17 eV) by ~70 meV—that is, the exciton binding energy plus TO-phonon energy (Figure 1a).

scholarly journals Photoluminescence in quantum-confined SnO2 nanocrystals: Evidence of free exciton decay

2004 ◽  
Vol 84 (10) ◽  
pp. 1745-1747 ◽  
Author(s):  
E. J. H. Lee ◽  
C. Ribeiro ◽  
T. R. Giraldi ◽  
E. Longo ◽  
E. R. Leite ◽  
...  
Keyword(s):  
Free Exciton ◽  
Sno2 Nanocrystals ◽  
Exciton Decay ◽  
Quantum Confined

Origins of Light Emission and Efficiency Saturation of the Photoluminescence of GaN Nanocrystallites

2003 ◽  
Vol 798 ◽  
Author(s):  
Xiang-Bai Chen ◽  
John L. Morrison ◽  
Margaret K. Penner ◽  
Jennifer Elle ◽  
Leah Bergman ◽  
...  
Keyword(s):  
Thin Films ◽  
Emission Line ◽  
Laser Heating ◽  
Laser Power ◽  
Room Temperature ◽  
Light Emission ◽  
Free Exciton ◽  
Strong Emission ◽  
Intensity Saturation ◽  
Pl Intensity

ABSTRACTThe photoluminescence (PL) properties of GaN nanorods were studied utilizing UV micro-photoluminescence. The room temperature PL of the GaN nanorods exhibits one strong emission line. The PL intensity as a function of the laser power was investigated in order to determine whether this emission originates from an excitonic or a bandgap recombination process. Our analysis indicates that the PL of the rods is excitonic-like and very similar to the behavior of the free exciton A in GaN thin films. However, for a relatively large and compact ensemble of rods, the PL intensity exhibits a significant saturation occurring already at relatively low laser power. We attribute the intensity saturation to the laser heating and heat trapping which takes place in the enclosure of the ensemble.

Excitonic light emission decay time measurements in moderatelyδ-doped GaAs/AlAs multiple quantum wells

2016 ◽  
Vol 55 (4) ◽  
Author(s):  
Jurgis Kundrotas ◽  
Aurimas Čerškus ◽  
Gintaras Valušis ◽  
Edmund Harold Linfield ◽  
Eric Johannessen ◽  
...  
Keyword(s):  
Quantum Wells ◽  
Decay Time ◽  
Light Emission ◽  
Single Photon ◽  
Free Exciton ◽  
Photon Counting ◽  
Reduction Rate ◽  
Decay Rates ◽  
Multiple Quantum Wells ◽  
Multiple Quantum

The radiative recombination rate of moderately dopedn-type andp-type GaAs/AlAs multiple quantum wells using a timecorrelated single photon counting system is presented. The experimental study has been obtained within a wide temperature range from liquid helium to room temperature and the work has focused on identifying photoluminescence decay rates based on freeexciton recombinations. It was found that the free exciton decay time was reduced in doped multiple GaAs/AlAs quantum wells, and that the reduction rate depends on both the concentration and doping type.

Renilla Bioluminescence: A Morphologic Approach to the Location of Photocytes

1974 ◽  
Vol 32 ◽  
pp. 208-209
Author(s):  
Ben O. Spurlock ◽  
Milton J. Cormier
Keyword(s):  
Excited State ◽  
Ground State ◽  
Molecular Basis ◽  
Light Emission ◽  
Chemical Basis ◽  
Electronic Excited State ◽  
Colonial Form ◽  
The Common ◽  
Eighteenth And Nineteenth Centuries ◽  
Catalyzed Oxidation

The phenomenon of bioluminescence has fascinated layman and scientist alike for many centuries. During the eighteenth and nineteenth centuries a number of observations were reported on the physiology of bioluminescence in Renilla, the common sea pansy. More recently biochemists have directed their attention to the molecular basis of luminosity in this colonial form. These studies have centered primarily on defining the chemical basis for bioluminescence and its control. It is now established that bioluminescence in Renilla arises due to the luciferase-catalyzed oxidation of luciferin. This results in the creation of a product (oxyluciferin) in an electronic excited state. The transition of oxyluciferin from its excited state to the ground state leads to light emission.

Scanning luminescence x-ray microscopy: Progress toward selective staining using microspheres

1994 ◽  
Vol 52 ◽  
pp. 74-75
Author(s):  
C. Jacobsen ◽  
J. Fu ◽  
S. Mayer ◽  
Y. Wang ◽  
S. Williams
Keyword(s):  
Visible Light ◽  
Active Sites ◽  
Light Emission ◽  
Chinese Hamster ◽  
Polystyrene Spheres ◽  
Good Resistance ◽  
X Ray ◽  
Selective Staining ◽  
Visible Light Emission ◽  
Specific Labelling

In scanning luminescence x-ray microscopy (SLXM), a high resolution x-ray probe is used to excite visible light emission (see Figs. 1 and 2). The technique has been developed with a goal of localizing dye-tagged biochemically active sites and structures at 50 nm resolution in thick, hydrated biological specimens. Following our initial efforts, Moronne et al. have begun to develop probes based on biotinylated terbium; we report here our progress towards using microspheres for tagging.Our initial experiments with microspheres were based on commercially-available carboxyl latex spheres which emitted ~ 5 visible light photons per x-ray absorbed, and which showed good resistance to bleaching under x-ray irradiation. Other work (such as that by Guo et al.) has shown that such spheres can be used for a variety of specific labelling applications. Our first efforts have been aimed at labelling ƒ actin in Chinese hamster ovarian (CHO) cells. By using a detergent/fixative protocol to load spheres into cells with permeabilized membranes and preserved morphology, we have succeeded in using commercial dye-loaded, spreptavidin-coated 0.03μm polystyrene spheres linked to biotin phalloidon to label f actin (see Fig. 3).

The Advantages of Cryotechniques: Application To Bioluminescent Cells

1990 ◽  
Vol 48 (1) ◽  
pp. 486-487
Author(s):  
Gisèle Nicolas ◽  
Jean-Marie Bassot ◽  
Marie-Thérèse Nicolas
Keyword(s):  
Endoplasmic Reticulum ◽  
Striated Muscle ◽  
Light Emission ◽  
Stable State ◽  
Freeze Substitution ◽  
Initial Step ◽  
Point Of Interest ◽  
Cell Components ◽  
Excellent Preservation ◽  
External Water

The use of fast-freeze fixation (FFF) followed by freeze-substitution (FS) brings substantial advantages which are due to the extreme rapidity of this fixation compared to the conventional one. The initial step, FFF, physically immobilizes most molecules and therefore arrests the biological reactions in a matter of milliseconds. The second step, FS, slowly removes the water content still in solid state and, at the same time, chemically fixes the other cell components in absence of external water. This procedure results in an excellent preservation of the ultrastructure, avoids osmotic artifacts,maintains in situ most soluble substances and keeps up a number of cell activities including antigenicities. Another point of interest is that the rapidity of the initial immobilization enables the capture of unstable structures which, otherwise, would slip towards a more stable state. When combined with electrophysiology, this technique arrests the ultrastructural modifications at a well defined state, allowing a precise timing of the events.We studied the epithelium of the elytra of the scale-worm, Harmothoe lunulata which has excitable, conductible and bioluminescent properties. The intracellular sites of the light emission are paracrystals of endoplasmic reticulum (PER), named photosomes (Fig.1). They are able to flash only when they are coupled with plasma membrane infoldings by dyadic or triadic junctions (Fig.2) basically similar to those of the striated muscle fibers. We have studied them before, during and after stimulation. FFF-FS showed that these complexes are labile structures able to diffentiate and dedifferentiate within milliseconds. Moreover, a transient network of endoplasmic reticulum was captured which we have named intermediate endoplasmic reticulum (IER) surrounding the PER (Fig.1). Numerous gap junctions are found in the membranous infoldings of the junctional complexes (Fig.3). When cryofractured, they cleave unusually (Fig.4-5). It is tempting to suggest that they play an important role in the conduction of the excitation.

Structural Optimization of Silicon for High Efficiencies of Light Emission

2018 ◽  
Vol 138 (4) ◽  
pp. 375-380
Author(s):  
Yuma Sugishita ◽  
Keisuke Inukai ◽  
Keishiro Goshima
Keyword(s):  
Structural Optimization ◽  
Light Emission
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