scholarly journals Role of Laser Power, Wavelength, and Pulse Duration in Laser Assisted Tin-Induced Crystallization of Amorphous Silicon

2018 ◽  
Vol 2018 ◽  
pp. 1-11 ◽  
Author(s):  
V. B. Neimash ◽  
A. O. Goushcha ◽  
L. L. Fedorenko ◽  
P. Ye. Shepelyavyi ◽  
V. V. Strelchuk ◽  
...  
Keyword(s):  
Laser Pulse ◽  
Amorphous Silicon ◽  
Temporal Distribution ◽  
Laser Pulses ◽  
Time Interval ◽  
Silicon Sample ◽  
Laser Pulse Intensity ◽  
Formation And Evolution ◽  
Induced Crystallization

This work describes tin-induced crystallization of amorphous silicon studied with Raman spectroscopy in thin-film structures Si-Sn-Si irradiated with pulsed laser light. We have found and analyzed dependencies of the nanocrystals’ size and concentration on the laser pulse intensity for 10 ns and 150 μm duration laser pulses at the wavelengths of 535 nm and 1070 nm. Efficient transformation of the amorphous silicon into a crystalline phase during the 10 ns time interval of the acting laser pulse in the 200 nm thickness films of the amorphous silicon was demonstrated. The results were analyzed theoretically by modeling the spatial and temporal distribution of temperature in the amorphous silicon sample within the laser spot location. Simulations confirmed importance of light absorption depth (irradiation wavelength) in formation and evolution of the temperature profile that affects the crystallization processes in irradiated structures.

scholarly journals Production of ion beams in high-power laser–plasma interactions and their applications

2004 ◽  
Vol 22 (1) ◽  
pp. 19-24 ◽  
Author(s):  
F. PEGORARO ◽  
S. ATZENI ◽  
M. BORGHESI ◽  
S. BULANOV ◽  
T. ESIRKEPOV ◽  
...  
Keyword(s):  
Laser Pulse ◽  
Medical Physics ◽  
Ion Beam ◽  
Laser Pulses ◽  
Ion Beams ◽  
Laser Plasma Interactions ◽  
Physical Mechanisms ◽  
Short Laser Pulses ◽  
Laser Pulse Intensity ◽  
Target Design

Energetic ion beams are produced during the interaction of ultrahigh-intensity, short laser pulses with plasmas. These laser-produced ion beams have important applications ranging from the fast ignition of thermonuclear targets to proton imaging, deep proton lithography, medical physics, and injectors for conventional accelerators. Although the basic physical mechanisms of ion beam generation in the plasma produced by the laser pulse interaction with the target are common to all these applications, each application requires a specific optimization of the ion beam properties, that is, an appropriate choice of the target design and of the laser pulse intensity, shape, and duration.

High pressure SF6 pulse transmission near 10.4 μm

1977 ◽  
Vol 55 (22) ◽  
pp. 1956-1961 ◽  
Author(s):  
E. A. Ballik ◽  
B. K. Garside ◽  
R. S. Taylor ◽  
T. A. Znotins
Keyword(s):  
High Pressure ◽  
Absorption Spectrum ◽  
Laser Pulse ◽  
Laser Pulses ◽  
Transmission Characteristics ◽  
Dynamical Characteristics ◽  
Pulse Intensity ◽  
Pulse Transmission ◽  
Laser Pulse Intensity

Measurements were performed to determine the dynamical characteristics of high pressure SF6 absorption at the 10.4 μm band of CO2 as a function of laser pulse intensity. Both long (~ 200 ns FWHM) and short (~ 5 ns FWHM) CO2 laser pulses were employed. The observed pulse transmission characteristics can be accounted for using a vibrational bath model, which allows for the very large number of levels in the absorption spectrum of SF6.

scholarly journals Diode Laser Spectroscopy of the Dynamics of Multiphoton Excitation of SF6 Molecules by CO2 Laser Pulses

1988 ◽  
Vol 8 (2-4) ◽  
pp. 151-168 ◽  
Author(s):  
Yu. A. Kuritsyn ◽  
G. N. Makarov ◽  
I. Pak ◽  
M. V. Sotnikov ◽  
I. I. Zasavitsky ◽  
...  
Keyword(s):  
Laser Pulse ◽  
Vibrational State ◽  
Rotational Quantum Number ◽  
Laser Pulses ◽  
Diode Laser Spectroscopy ◽  
Strong Disagreement ◽  
Theoretical Predictions ◽  
Excited Molecules ◽  
Theory And Experiments

The dynamics of excitation by CO2 laser pulses of SF6 molecules from individual rotational sublevels J″ of the ground vibrational state have been investigated in a pulsed molecular jet under essentially collisionless conditions. At different energy fluences of exciting laser pulse Φ = 10−5 + 10−1 J/cm2, the dependences of the fraction fJ of excited molecules on the rotational quantum number J″ have been obtained, when SF6 molecules were excited on the 10P(16) CO2 laser line, as well as on the 10P(18) and 10P(14) lines at Φ = 0.1 J/cm2. Comparison of experimental results with theoretical predictions18–20 shows rather strong disagreement between theory and experiments both in the population of the υ3 = 1 state and in the role of multiphoton transitions. It is shown that the narrowing of the exciting laser pulse spectrum (the 10P(16) line, Φ ≲ 10−2 J/cm2) results in drastic decrease of the fraction of excited molecules from the (υ3 = 0, J″ = 4) state which is most resonant with laser radiation.

A Laser Triggered Self-Sustaining Metals-Compound Semiconductor Transition for AlSb

1981 ◽  
Vol 4 ◽  
Author(s):  
R. Andrew ◽  
L. Baufay ◽  
A. Pigeolet ◽  
L.D. Laude
Keyword(s):  
Laser Pulse ◽  
Laser Annealing ◽  
Pulsed Laser ◽  
Laser Pulses ◽  
Pulsed Laser Annealing ◽  
Short Laser Pulses ◽  
Thermally Triggered ◽  
Heat Of Transformation ◽  
Complete Transformation

ABSTRACTThe preparation of AlSb thin films by pulsed laser annealing of Al/Sb sandwiches is studied in order to resolve some past controversy about the temperature rise induced by the laser pulse. Using 1000 Ȧ thick two layer films supported by TEM grids, we investigate the energy threshold for complete transformation as a function of pulse duration from 15 nsec to 100 msec, and of ambient temperature from −100°C to 250°C.We thence calculate the temperature effect directly induced by the laser to be about 930°C, or approximately the melting point of the metals, whereas inert gas furnace anneals of comparable films show transformation at this temperature occuring only in about 100 sec. We discuss the isoenergetic nature of the system for short laser pulses and the role of the heat of transformation, and thus conclude that the reaction is thermally triggered by the laser pulse but is to some extent self-sustaining via the heat of transformation locally distributed. This model is also shown to have equal validity for the systems CdTe, CdSe and AlAs.

scholarly journals Temporal Characterization of a Plasma Produced by Interaction of Laser Pulses with Water Solutions

2002 ◽  
Vol 20 (2-4) ◽  
pp. 111-122 ◽  
Author(s):  
J. Ben Ahmed ◽  
N. Terzi ◽  
Z. Ben Lakhdar ◽  
G. Taieb
Keyword(s):  
Laser Pulse ◽  
Emission Spectra ◽  
Laser Pulses ◽  
Time Interval ◽  
Stark Broadening ◽  
Electronic Density ◽  
Electronic Temperature ◽  
Intensity Measurements ◽  
A Value

The temporal evolution of a plasma formed by the interaction of a Nd-YAG 10 ns laser pulse with the surface of aqueous solutions of CaCl2, has been observed by analyzing the variation of the emission spectra of ions and neutral atoms in the time interval after the laser pulse, 500 ns < t < 5000 ns. The intensity measurements of the lines of CaII at 3158 Å, 3179 Å, 3706 Å, 3736 Å, 3933 Å, 3968 Å were used to obtain the electronic temperature Te using a Saha-Boltzmann analysis. The broadening of the resonance line of CaI at 4227 Å was used to deduce the electronic density Ne, with the aid of the semiclassical theory of Stark broadening. A value of Te ≈ 28000 K decreasing slightly to 21000 K, and an exponential decay for Ne were found, with Ne ≈ 1:25 × 1018 cm-3 at 500 ns and τe=(1200±50) ns.

scholarly journals Абляция кремния в воздухе моно- и бихроматическими импульсами лазерного излучения с длинами волн 355 и 532 nm

2022 ◽  
Vol 92 (1) ◽  
pp. 36
Author(s):  
А.Н. Чумаков ◽  
В.В. Лычковский ◽  
И.С. Никончук ◽  
А.С. Мацукович
Keyword(s):  
Electron Microscopy ◽  
Scanning Electron Microscopy ◽  
Material Removal ◽  
Laser Pulses ◽  
Time Interval ◽  
Silicon Sample ◽  
Laser Irradiance ◽  
Video Registration ◽  
532 Nm ◽  
Scanning Electron

Ablation of silicon sample in air under irradiance of single and double laser pulses with wavelengths 355 and 532 nm was studied by means of optical and scanning electron microscopy, raman spectroscopy, profilometry of laser craters as well as video registration of plasma’s plume radiation in time. Dependence of specific sample’s material removal on laser fluence and time interval between coupled pulses of bichromatic laser irradiance was established. Spallation of silicon was found in broad range of irradiance parameters and parameters of craters formed by ablation and spallation under the action of bichromatic laser radiation were determined.

Effect of Dipyridamole on Spontaneous Platelet Aggregation in Whole Blood Decreases with the Time After Venepuncture: Evidence for the Role of ADP

1987 ◽  
Vol 58 (02) ◽  
pp. 744-748 ◽  
Author(s):  
A R Saniabadi ◽  
G D O Lowe ◽  
J C Barbenel ◽  
C D Forbes
Keyword(s):  
Platelet Aggregation ◽  
Correlation Coefficient ◽  
Whole Blood ◽  
Blood Platelet ◽  
Inhibitory Effect ◽  
Time Interval ◽  
Adp Receptor ◽  
Spontaneous Platelet Aggregation

SummarySpontaneous platelet aggregation (SPA) was studied in human whole blood at 3, 5, 10, 20, 30, 40 and 60 minutes after venepuncture. Using a whole blood platelet counter, SPA was quantified by measuring the fall in single platelet count upon rollermixing aliquots of citrated blood at 37° C. The extent of SPA increased with the time after venepuncture, with a correlation coefficient of 0.819. The inhibitory effect of dipyridamole (Dipy) on SPA was studied: (a) 10 μM at each time interval; (b) 0.5-100 μM at 3 and 30 minutes and (c) 15 μM in combination with 100 μM adenosine, 8 μM 2-chloroadenosine (2ClAd, an ADP receptor blocker) and 50 μM aspirin. There was a rapid decrease in the inhibitory effect of Dipy with the time after venepuncture; the correlation coefficient was -0.533. At all the concentrations studied, Dipy was more effective at 3 minutes than at 30 minutes after venepuncture. A combination of Dipy with adenosine, 2ClAd or aspirin was a more effective inhibitor of SPA than either drug alone. However, when 15 μM Dipy and 10 μM Ad were added together, the inhibitory effect of Dipy was not increased significantly, suggesting that Dipy inhibits platelet aggregation independent of Ad. The increase in SPA with the time after venepuncture was abolished when blood was taken directly into the anticoagulant containing 5 μM 2ClAd. It is suggested that ADP released from the red blood cells is responsible for the increased platelet aggregability with the time after venepuncture and makes a serious contribution to the artifacts of in vitro platelet function studies.

The role of density reduction in lithiated amorphous silicon: Molecular dynamics and ab-initio studies

2021 ◽  
Author(s):  
Jay Krishan Dora ◽  
Charchit Saraswat ◽  
Ashish Gour ◽  
Sudipto Ghosh ◽  
Natraj Yedla ◽  
...  
Keyword(s):  
Molecular Dynamics ◽  
Ab Initio ◽  
Amorphous Silicon ◽  
Density Reduction

scholarly journals Electron Symmetry Breaking during Attosecond Charge Migration Induced by Laser Pulses: Point Group Analyses for Quantum Dynamics

Symmetry ◽  
2021 ◽  
Vol 13 (2) ◽  
pp. 205
Author(s):  
Dietrich Haase ◽  
Gunter Hermann ◽  
Jörn Manz ◽  
Vincent Pohl ◽  
Jean Christophe Tremblay
Keyword(s):  
Laser Pulse ◽  
Symmetry Breaking ◽  
Electric Fields ◽  
Quantum Dynamics ◽  
Point Group ◽  
Laser Pulses ◽  
Charge Migration ◽  
Laser Control ◽  
The One ◽  
Superposition States

Quantum simulations of the electron dynamics of oriented benzene and Mg-porphyrin driven by short (<10 fs) laser pulses yield electron symmetry breaking during attosecond charge migration. Nuclear motions are negligible on this time domain, i.e., the point group symmetries G = D6h and D4h of the nuclear scaffolds are conserved. At the same time, the symmetries of the one-electron densities are broken, however, to specific subgroups of G for the excited superposition states. These subgroups depend on the polarization and on the electric fields of the laser pulses. They can be determined either by inspection of the symmetry elements of the one-electron density which represents charge migration after the laser pulse, or by a new and more efficient group-theoretical approach. The results agree perfectly with each other. They suggest laser control of symmetry breaking. The choice of the target subgroup is restricted, however, by a new theorem, i.e., it must contain the symmetry group of the time-dependent electronic Hamiltonian of the oriented molecule interacting with the laser pulse(s). This theorem can also be applied to confirm or to falsify complementary suggestions of electron symmetry breaking by laser pulses.

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