Investigation of Laser-Induced Etching of Ti in Phosphoric Acid

1995 ◽  
Vol 397 ◽  
Author(s):  
R. J. Nowak ◽  
S. M. Metev ◽  
K. B. Meteva ◽  
G. Sepold
Keyword(s):  
Phosphoric Acid ◽  
Laser Power ◽  
Threshold Value ◽  
Exponential Dependence ◽  
Time Resolved ◽  
Laser Illumination ◽  
Thermally Activated ◽  
Argon Lasers ◽  
Gaussian Mode ◽  
Laser Induced Etching

ABSTRACTLaser-induced chemical etching of Ti in phosphoric acid has been investigated using cw Nd:YAG (1.064 μιm) and Argon lasers (514 nm) operating in the fundamental Gaussian mode. Two different regions of etching were observed, which are separated by a characteristic threshold value of the laser power and ascribed to melting of the metal. Below the threshold an exponential dependence of etch rates on laser power suggest a thermally activated etching mechanism. Time-resolved measurements indicate in this region the dissolution of the passivation layer followed by surface etching of the metal grains. After laser illumination an immediate repassivation of the re-cooled surface stops the etch reaction.

Solvent Dependence of Structural Dynamics and Spin-flip Processes in 3,4,5-tri(9H-carbazole-9-yl)benzonitrile (ortho-3CzBN)

2020 ◽  
Author(s):  
Masaki Saigo ◽  
Kiyoshi Miyata ◽  
Hajime Nakanotani ◽  
Chihaya Adachi ◽  
Ken Onda
Keyword(s):  
Dft Calculations ◽  
Excited States ◽  
Structural Changes ◽  
Photophysical Properties ◽  
Delayed Fluorescence ◽  
Time Resolved ◽  
Thermally Activated Delayed Fluorescence ◽  
Thermally Activated ◽  
Solvent Dependence ◽  
Acetonitrile Solutions

We have investigated the solvent-dependence of structural changes along with intersystem crossing of a thermally activated delayed fluorescence (TADF) molecule, 3,4,5-tri(9H-carbazole-9-yl)benzonitrile (o-3CzBN), in toluene, tetrahydrofuran, and acetonitrile solutions using time-resolved infrared (TR-IR) spectroscopy and DFT calculations. We found that the geometries of the S1 and T1 states are very similar in all solvents though the photophysical properties mostly depend on the solvent. In addition, the time-dependent DFT calculations based on these geometries suggested that the thermally activated delayed fluorescence process of o-3CzBN is governed more by the higher-lying excited states than by the structural changes in the excited states.<br>

Solute Segregation and Dynamics of Solid-Phase Crystallization In in and Sb-Implanted Silicon

1981 ◽  
Vol 4 ◽  
Author(s):  
J. Narayan ◽  
G. L. Olson ◽  
O. W. Holland
Keyword(s):  
Laser Power ◽  
Solid Phase ◽  
Solute Segregation ◽  
Dislocation Loops ◽  
Solid Phase Crystallization ◽  
Time Resolved ◽  
Plan View ◽  
Ion Channeling ◽  
Retrograde Solubility ◽  
Transmission Electron

ABSTRACTTime-resolved-reflectivity measurements have been combined with transmission electron microscopy (cross-section and plan-view), Rutherford backscattering and ion channeling techniques to study the details of laser induced solid phase epitaxial growth in In+ and Sb+ implanted silicon in the temperature range from 725 to 1500 °K. The details of microstructures including the formation of polycrystals, precipitates, and dislocations have been correlated with the dynamics of crystallization. There were limits to the dopant concentrations which could be incorporated into substitutional lattice sites; these concentrations exceeded retrograde solubility limits by factors up to 70 in the case of the Si-In system. The coarsening of dislocation loops and the formation of a/2<110>, 90° dislocations in the underlying dislocation-loop bands are described as a function of laser power.

Pulsed Laser Melting of Amorphous Silicon: Time-Resolved and Post-Irradiation Studies

1983 ◽  
Vol 23 ◽  
Author(s):  
D. H. Lowndes ◽  
R. F. Wood ◽  
C. W. White ◽  
J. Narayan
Keyword(s):  
Pulsed Laser ◽  
Threshold Value ◽  
Dynamical Response ◽  
Cross Sectional ◽  
Time Resolved ◽  
Model Calculations ◽  
Fine Grained ◽  
Transmission Electron ◽  
Incident Laser Pulse ◽  
Thermal Melting

ABSTRACTMeasurements of the time of the onset of melting of self-implantation amorphized (a) Si, during an incident laser pulse, have been combined with modified melting model calculations and measurements of surface melt duration to demonstrate that the thermal conductivity, Ka, of a-Si is very low (≃0.02 W/cm-K). Ka is also shown to be the dominant parameter determining the dynamical response of ionimplanted Si to pulsed laser radiation; the latent heat and melting temperature of a-Si are relatively unimportant. Cross-sectional transmission electron micrographs on implantation-amorphized Si layers of several different thicknesses show that for energy densities less than the threshold value for complete annealing there are usually two distinct regions in the re-solidified a-Si, consisting of fine-grained and large-grained polycrystalline Si, respectively. The presence of the fine-grained poly-Si suggests that bulk nucleation occurs directly from the highly undercooled liquid phase. Thermal melting model calculations suggest that the nucleation temperature, Tn is ≃1200°C.

scholarly journals Thermally activated delayed fluorescence vs. room temperature phosphorescence by conformation control of organic single molecules

2019 ◽  
Vol 7 (22) ◽  
pp. 6616-6621 ◽  
Author(s):  
Przemyslaw Data ◽  
Masato Okazaki ◽  
Satoshi Minakata ◽  
Youhei Takeda
Keyword(s):  
Room Temperature ◽  
Single Molecules ◽  
Delayed Fluorescence ◽  
Room Temperature Phosphorescence ◽  
Time Resolved ◽  
Thermally Activated Delayed Fluorescence ◽  
Molecular Conformations ◽  
Thermally Activated ◽  
Luminescent Compound

The time-resolved photophysical analysis of a multi-color-changing mechanochromic luminescent compound has been disclosed, which reveals distinct different emission paths to boost TADF and RTP of the emitter depending on its molecular conformations.

Approach to a Limiting Cycle in Thermally Relaxing Media

SPIN ◽  
2015 ◽  
Vol 05 (01) ◽  
pp. 1550001
Author(s):  
Ivo Klik ◽  
Ching-Ray Chang
Keyword(s):  
Magnetic Field ◽  
Steady State ◽  
Hysteresis Loop ◽  
Point Of View ◽  
Exponential Dependence ◽  
Arbitrary State ◽  
Superparamagnetic Particle ◽  
Thermally Activated ◽  
Limiting Cycle ◽  
Minor Hysteresis Loop

The thermally activated dynamics of an uniaxial superparamagnetic particle are studied here from the point of view of approach towards a steady state minor hysteresis loop representing a limiting cycle. The particle is initially at an arbitrary state, and is driven by a sufficiently small external applied ac magnetic field till the limiting minor hysteresis loop is reached with a desired precision. The number of periods required to reach the limiting cycle is found to satisfy an Arrhenius-type law, with an exponential dependence on the inverse ambient temperature. We tentatively associate this result with energy dissipation, its origin, however, remains quite unclear.

Characterization of Rhodamine 6G-Doped Thin Sol-Gel Films

1993 ◽  
Vol 47 (2) ◽  
pp. 229-234 ◽  
Author(s):  
Upvan Narang ◽  
Frank V. Bright ◽  
Paras N. Prasad
Keyword(s):  
Excited State ◽  
Rhodamine 6G ◽  
Sol Gel ◽  
Decay Kinetics ◽  
Time Resolved ◽  
Laser Illumination ◽  
State Decay ◽  
Sol Gel Films ◽  
Microscope Slides

Rhodamine 6G- (R6G) doped thin sol-gel films were cast on glass microscope slides and characterized with the use of steady-state and time-resolved fluorescence spectroscopy. The fluorescence intensity, photodegradation under laser illumination, and excited-state decay kinetics were all investigated as a function of dopant concentration. The excited-state decay kinetics of highly doped films show clear evidence of R6G aggregation. Photodegradation under laser illumination is very interesting and is discussed in detail.

Carrier lifetimes in strained InGaAsP multiple-quantum-well laser structures

1992 ◽  
Vol 70 (10-11) ◽  
pp. 1017-1022 ◽  
Author(s):  
B. W. Takasaki ◽  
J. S. Preston ◽  
J. D. Evans ◽  
J. G. Simmons ◽  
S. Charbonneau ◽  
...  
Keyword(s):  
Quantum Well ◽  
Multiple Quantum Well ◽  
Thermionic Emission ◽  
Multiple Quantum ◽  
Time Resolved ◽  
Carrier Lifetimes ◽  
Thermally Activated ◽  
Quantum Well Laser ◽  
Electron Escape ◽  
Multiple Quantum Well Laser

We have investigated carrier sweepout in a series of strained InGaAsP multiple quantum well laser structures by time-resolved photoconductivity and CW photoluminescence. The electrons and holes exhibit very different escape times: the electrons less than 0.5 ns and the holes greater than 10 ns. With only the built-in field across the wells, the electron escape is thermally activated in both tensile samples, while it is unclear whether tunneling or thermionic emission is the dominant escape mechanism in the unstrained and compressive samples. Application of a 2 V reverse bias is sufficient to produce efficient tunneling escape of electrons in the tensile samples. A simple model of the competition between thermionic emission and radiative recombination in the tensile wells yields values for the barrier height that are in agreement with the calculated values.

Time-Resolved and Post-Irradiation Studies of the Interaction of High-Power Pulsed Microwave Radiation with Silicon

1986 ◽  
Vol 74 ◽  
Author(s):  
R. B. James ◽  
P. R. Bolton ◽  
R. A. Alvarez ◽  
R. E. Valiga ◽  
W. H. Christie
Keyword(s):  
Mass Spectrometry ◽  
Secondary Ion Mass Spectrometry ◽  
Surface Region ◽  
Surface Damage ◽  
Threshold Value ◽  
Optical Measurements ◽  
Time Resolved ◽  
Near Surface ◽  
Reflected Power ◽  
Secondary Ion

AbstractWe have measured the microwave-induced damage to the near-surface region of silicon for 1.9-μs pulses at a frequency of 2.856 GHz and a pulse power of up to 7.2 MW. Rectangular samples were irradiated in a test section of WR-284 waveguide that was filled with freon to a pressure of 30 psig. Incident, transmitted and reflected powers were monitored with directional couplers and fast diodes. The results of the time-resolved optical measurements show that the onset of surface damage is accompanied by a large increase in the reflected power. Examination of the irradiated surfaces shows that the degree of damage is greatest near the edges of the samples. Using secondary ion mass spectrometry to profile the implanted As, we find that the microwave pulses can melt the near-surface region of the material for pulse powers exceeding a threshold value.

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