Excitation and DE-Excitation of Yb3+ in Inp and Er3+ in Si: Photoluminescence and Impact Ionization Studies

1996 ◽  
Vol 422 ◽  
Author(s):  
T. Gregorkiewicz ◽  
I. Tsimperidis ◽  
C. A. J. Ammerlaan ◽  
F. P. Widdershoven ◽  
N. A. Sobolev
Keyword(s):  
Energy Transfer ◽  
Impact Ionization ◽  
Crystalline Silicon ◽  
Optical Excitation ◽  
Nonradiative Recombination ◽  
Energy Transfer Mechanism ◽  
Excitation Mechanism ◽  
Conduction Electrons ◽  
The One

AbstractIn the paper the existing information on the optical excitation of the erbium ion in crystalline silicon is critically reviewed. The proposed excitation mechanism is compared to the one which is believed to be responsible for the luminescence of ytterbium in indium phosphide. To this end the influence of constant and microwave electric field on the photoluminescence of both systems is inspected. It is shown that, although both systems show some similarities, their analogy is limited.The particular role of excitons and electrons in both the excitation as well as the de-excitation mechanism is investigated for the Si:Er system. The results of photoluminescence decay studies (T=4.2 K) are presented. It is argued that a nonradiative energy transfer to conduction electrons is responsible for the limitation of the energy transfer to the Er core and for its nonradiative recombination. Also, a prominent role of excitons in the energy transfer mechanism is confirmed. Finally, the origin of the 873 meV photoluminescence band recently reported in Er-implanted Si is discussed in relation to a possible defect-mediated activation of Er.

Adiabatic large polarons in anisotropic molecular crystals

2011 ◽  
Vol 35 (1) ◽  
pp. 15-27
Author(s):  
Zoran Ivić ◽  
Željko Pržulj
Keyword(s):  
Energy Transfer ◽  
Effective Mass ◽  
Molecular Crystals ◽  
Single Chain ◽  
Proper Understanding ◽  
One Dimensional ◽  
Interchain Coupling ◽  
Large Polaron ◽  
The One

Adiabatic large polarons in anisotropic molecular crystals We study the large polaron whose motion is confined to a single chain in a system composed of the collection of parallel molecular chains embedded in threedimensional lattice. It is found that the interchain coupling has a significant impact on the large polaron characteristics. In particular, its radius is quite larger while its effective mass is considerably lighter than that estimated within the one-dimensional models. We believe that our findings should be taken into account for the proper understanding of the possible role of large polarons in the charge and energy transfer in quasi-one-dimensional substances.

Vibration suppression and energy transfer by parametric excitation in drive systems

2012 ◽  
Vol 226 (8) ◽  
pp. 2000-2014 ◽  
Author(s):  
Horst Ecker ◽  
Thomas Pumhössel
Keyword(s):  
Energy Transfer ◽  
Parametric Excitation ◽  
Vibration Suppression ◽  
Negative Impact ◽  
Energy Transfer Mechanism ◽  
Engineering Systems ◽  
Excitation Mechanism ◽  
Electrical Drive ◽  
Excitation Mechanisms ◽  
Drive Systems

Drive systems may experience torsional vibrations due to various kinds of excitation mechanisms. In many engineering systems, however, such vibrations may have a negative impact on the performance and must be avoided or reduced to an acceptable level by all means. Self-excited vibrations are especially unwanted, since they may grow rapidly and not only degrade the performance but even damage machinery. In this contribution it is suggested to employ parametric stiffness excitation to suppress self-excited vibrations. In the first part of the article we study the basic energy transfer mechanism that is initiated by parametric excitation, and some general conclusions are drawn. In the second part, a hypothetic drivetrain, consisting of an electrical motor, a drive shaft and working rolls is investigated. A self-excitation mechanism is assumed to destabilize the drive system. Parametric excitation is introduced via the speed control of the electrical drive, and the capability of stabilizing the system by this measure is investigated. It is shown that the damping available in the system can be used much more effectively if parametric stiffness excitation is employed.

Eu and Yb Excitation Mechanisms in ZnS, CaS, SrS and InP

1993 ◽  
Vol 301 ◽  
Author(s):  
M. Godlewski ◽  
K. Światek ◽  
B. Monemar
Keyword(s):  
Energy Transfer ◽  
Rare Earth ◽  
Excited State ◽  
Exciton State ◽  
Experimental Results ◽  
Excitation Mechanism ◽  
Core State ◽  
Excitonic State ◽  
Excitation Mechanisms

ABSTRACTThe role of the excitonic excitation mechanism of the rare earth (RE) intra-shell emission is discussed. Two cases are analyzed. For Yb ion in InP 4f-4f emission of Yb3+ is induced by energy transfer from bound exciton state to the RE core state. For Eu in CaS and SrS RE emission is induced by carrier trapping directly to the excited state of Eu2+ ion. Also in this case the intermediate excitonic state may participate in RE excitation, as suggested by some experimental results.

scholarly journals THE ROLE OF PHOSPHOCREATINE AND ADENOSINE-TRIPHOSPHATE IN MUSCULAR CONTRACTION

1953 ◽  
Vol 37 (1) ◽  
pp. 63-70 ◽  
Author(s):  
Emil Bozler
Keyword(s):  
Energy Transfer ◽  
Muscular Contraction ◽  
Energy Transfer Mechanism ◽  
Contracting Muscle ◽  
Low Concentrations ◽  
Strong Contraction ◽  
Autocatalytic Process ◽  
Ca Ions ◽  
Tension Curve

In the presence of 20 mM PC a strong contraction is produced in glycerol-extracted muscle fibers by ATP and AMP in concentrations as low as 10–6 M per liter. At low concentrations of nucleotide tension rises very slowly. This rise is interpreted as being due to absorption of nucleotide by the contractile elements. AMP gives an S-shaped tension curve, indicating that the conversion of AMP into ATP is an autocatalytic process. Tension is maintained in a contracted muscle even in PC solutions free of ATP. PC alone produces a contraction if applied within 5 minutes after ATP has been washed out from a contracting muscle. It is concluded from these results that PC is the substrate for the enzymatic activity of the contractile elements and that this activity depends on the presence of bound nucleotide which acts as an energy transfer mechanism. PC accelerates relaxation which is caused by ATP under certain conditions. In the presence of PC even very low concentrations of ATP can produce relaxation. A strong contraction can be produced under these conditions by the addition of Ca ions. These observations support the conclusion that relaxation depends on the rephosphorylation of nucleotide bound by the contractile elements.

scholarly journals Reduced Thermal Conductivity in Ultrafast Laser Heated Silicon Measured by Time-Resolved X-ray Diffraction

Crystals ◽  
2021 ◽  
Vol 11 (2) ◽  
pp. 186
Author(s):  
Wonhyuk Jo ◽  
Yong Chan Cho ◽  
Seongheun Kim ◽  
Eric Carl Landahl ◽  
Sooheyong Lee
Keyword(s):  
Crystalline Silicon ◽  
Effective Means ◽  
Optical Excitation ◽  
Carrier Dynamics ◽  
High Angular Resolution ◽  
Nonradiative Recombination ◽  
X Ray Diffraction ◽  
Time Resolved ◽  
Near Surface ◽  
X Ray

We investigate the effect of free carrier dynamics on heat transport in bulk crystalline Silicon following femtosecond optical excitation of varying fluences. By taking advantage of the dense 500 MHz standard fill pattern in the PLS-II storage ring, we perform high angular-resolution X-ray diffraction measurements on nanosecond-to-microsecond time-scales with femtometer spatial sensitivity. We find noticeably slowed lattice recovery at increasingly high excitation intensities. Modeling the temporal evolution of lattice displacements due to the migration of the near surface generated heat into the bulk requires reduced thermal diffusion coefficients. We attribute this pump-fluence dependent thermal transport behavior to two separate effects: first, the enhanced nonradiative recombination of free carriers, and, second, reduced size of the effective heat source in the material. These results demonstrate the capability of time-resolved X-ray scattering as an effective means to explore the connection between charge carrier dynamics and macroscopic transport properties.

scholarly journals 1,4-Bis (β-Pyridyl-2-Vinyl) Benzene (P2VB) and 2,5-Distyryl-pyrazine (DSP) as Blue Laser Dyes

1985 ◽  
Vol 5 (4) ◽  
pp. 223-230 ◽  
Author(s):  
E. M. Ebeid ◽  
M. M. F. Sabry ◽  
S. A. El-Daly
Keyword(s):  
Energy Transfer ◽  
Laser Excitation ◽  
Blue Laser ◽  
Quantum Yields ◽  
Nitrogen Laser ◽  
Laser Dyes ◽  
Energy Transfer Mechanism ◽  
Fluorescence Quantum Yields ◽  
Critical Transfer Distance

Solutions of P2VB and DSP in dimethyl-sulphoxide (DMSO) of concentration ca. 10–3 M/l act as laser dyes on pumping with nitrogen laser. P2VB and DSP are lasing in the ranges 390–440 nm (λmax = 416 nm) and 435–465 nm (λmax = 447 nm) respectively. An equimolar mixture of P2VB and DSP behaves as an energy transfer dye laser (ETDL) and is lasing in the range 429–455 nm (λmax = 438 nm). Such ETDL system obeys a long range coulombic energy transfer mechanism with a critical transfer distance R0 = 7.5 nm.The fluorescence quantum yields of both dyes have been measured, and in DMSO φf = 0.46 and 0.35 for P2VB and DSP respectively.Both dyes show a remarkable photostability upon nitrogen laser excitation. This has been attributed to the role of the 337 nm light in inducing a back photo-chemical reaction of the initially formed photoproducts consisting mainly of photo-oligomers and cis-photoisomers.

Role of the Spacer in the Singlet−Singlet Energy Transfer Mechanism (Förster vs Dexter) in Cofacial Bisporphyrins

2004 ◽  
Vol 126 (4) ◽  
pp. 1253-1261 ◽  
Author(s):  
Sébastien Faure ◽  
Christine Stern ◽  
Roger Guilard ◽  
Pierre D. Harvey
Keyword(s):  
Energy Transfer ◽  
Transfer Mechanism ◽  
Energy Transfer Mechanism

On the Excitation Mechanism of Erbium and Ytterbium in the Quaternary Compounds InGaAsP

1996 ◽  
Vol 422 ◽  
Author(s):  
Peter Wellmann ◽  
Albrecht Winnacker ◽  
Gerhard Pensl
Keyword(s):  
Energy Transfer ◽  
Excitation Energy ◽  
Bandgap Energy ◽  
Energy Transfer Mechanism ◽  
Doped Semiconductors ◽  
Quaternary Compounds ◽  
The One ◽  
Back Transfer ◽  
Lattice Matched ◽  
Efficient Transfer

AbstractAn efficient transfer of excitonic energy to rare earth (RE) ions is crucial for possible optoelectronic applications of RE doped semiconductors. In order to investigate the energy transfer mechanism to RE ions after optical above bandgap excitation we studied the intensity of the 4I13/2 →4 4I15/2-transition of Er3+ (1.54μm) and the one of the 2F5/2 →2F7/2 -transition of Yb3+ (lμm) (loped into InGaAsP-layers lattice matched to InP. By varying the composition of the quaternary compoun ds, the bandgap energy together with the RE bound exciton energy were tuned relative to the RE excitation energy, and the effect on the RE luminescence intensity was observed. The results can be interpreted by stating a) that the energy transfer to the RE proceeds via the RE bound exciton, and b) that the intensity of the RE luminescence is essentially determined by the rate of back transfer of the RE excitation energy ERE to the bound exciton (with excitation energy Ebe). In this back transfer the energy of the excited RE ion plus the energy of 0, 1, 2 ... L0-phonons (energy Elo) is used to reexcite the bound exciton, instead of being emitted as an RE luminescence photon. For compositions where Ebe = ERE + n. Elo (n = 0, 1, 2...) we have a maximum of back transfer and correspondingly a, minimum in RE luminescence. In between the intensity has a, maximum.

You Are the One I Want to Communicate With!

2013 ◽  
Vol 44 (1) ◽  
pp. 16-25 ◽  
Author(s):  
Sabrina Pierucci ◽  
Olivier Klein ◽  
Andrea Carnaghi
Keyword(s):  
Memory Bias ◽  
Shared Reality ◽  
Communication Partner ◽  
Shared Reality Theory ◽  
The One ◽  
Study Participants

This article investigates the role of relational motives in the saying-is-believing effect ( Higgins & Rholes, 1978 ). Building on shared reality theory, we expected this effect to be most likely when communicators were motivated to “get along” with the audience. In the current study, participants were asked to describe an ambiguous target to an audience who either liked or disliked the target. The audience had been previously evaluated as a desirable vs. undesirable communication partner. Only participants who communicated with a desirable audience tuned their messages to suit their audience’s attitude toward the target. In line with predictions, they also displayed an audience-congruent memory bias in later recall.

The Formation of Intermediate Product I in a Purified System The Role of Factor IX or of its Precursor and of a Hageman Factor-PTA Fraction

1961 ◽  
Vol 6 (02) ◽  
pp. 224-234 ◽  
Author(s):  
E. T Yin ◽  
F Duckert
Keyword(s):  
Intermediate Product ◽  
Factor Ix ◽  
Assay Method ◽  
Lag Phase ◽  
Factor X ◽  
Haemophilia B ◽  
Hageman Factor ◽  
One Stage ◽  
The One

Summary1. The role of two clot promoting fractions isolated from either plasma or serum is studied in a purified system for the generation of intermediate product I in which the serum is replaced by factor X and the investigated fractions.2. Optimal generation of intermediate product I is possible in the purified system utilizing fractions devoid of factor IX one-stage activity. Prothrombin and thrombin are not necessary in this system.3. The fraction containing factor IX or its precursor, no measurable activity by the one-stage assay method, controls the yield of intermediate product I. No similar fraction can be isolated from haemophilia B plasma or serum.4. The Hageman factor — PTA fraction shortens the lag phase of intermediate product I formation and has no influence on the yield. This fraction can also be prepared from haemophilia B plasma or serum.

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