scholarly journals The Role of Crystalline Orientation in the Formation of Surface Patterns on Solids Irradiated with Femtosecond Laser Double Pulses

2020 ◽  
Vol 10 (24) ◽  
pp. 8811
Author(s):  
George D. Tsibidis ◽  
Luc Museur ◽  
Andrei Kanaev
Keyword(s):  
Carrier Density ◽  
Fluid Transport ◽  
Temperature Drop ◽  
Thermal Response ◽  
Surface Pattern ◽  
Temporal Separation ◽  
Pulse Separation ◽  
Theoretical Predictions ◽  
Surface Patterns

A theoretical investigation of the underlying ultrafast processes upon irradiation of rutile TiO2 of (001) and (100) surface orientation with femtosecond (fs) double pulsed lasers was performed in ablation conditions, for which, apart from mass removal, phase transformation and surface modification of the heated solid were induced. A parametric study was followed to correlate the transient carrier density and the produced lattice temperature with the laser fluence, pulse separation and the induced damage. The simulations showed that both temporal separation and crystal orientation influence the surface pattern, while both the carrier density and temperature drop gradually to a minimum value at temporal separation equal to twice the pulse separation that remain constant at long delays. Carrier dynamics, interference of the laser beam with the excited surface waves, thermal response and fluid transport at various pulse delays explained the formation of either subwavelength or suprawavelength structures. The significant role of the crystalline anisotropy is illustrated through the presentation of representative experimental results correlated with the theoretical predictions.

Role of Si(100) Surface Patterns in the Phase Separation of Cu/Sn Thin Films

2001 ◽  
Vol 672 ◽  
Author(s):  
Qin Hu ◽  
Martin Zinke–Allmang ◽  
Ian V. Mitchell
Keyword(s):  
Thin Film ◽  
Thermal Decomposition ◽  
Phase Separation ◽  
Ex Situ ◽  
Surface Pattern ◽  
Length Scale ◽  
Thermal Decomposition Process ◽  
Surface Patterns ◽  
Initial Pattern

ABSTRACTWe report on the competitive phase separation of copper and tin thin film deposits on a pre–patterned Si(100) surface. The initial pattern on Si(100) was achieved through a thermal decomposition process of an ex–situ grown oxide film. Copper and tin phase separation on silicon is a competitive process with Cu forming preferrably silicide. Sn is observed to cover the silicide clusters when present in a sufficient amount. The pre–patterning of the surface introduces a new length scale in the problem. Our data suggest that this length scale plays a role while the clustering (ripening) length scale is of the same order, i.e., during nucleation and the early phase separation, but that both length scales become independent once the length scale of ripening significantly exceeds the length scale of the surface pattern.

Electric charge of nanopatterned silica surfaces

2019 ◽  
Vol 21 (14) ◽  
pp. 7576-7587 ◽  
Author(s):  
H. Gokberk Ozcelik ◽  
Murat Barisik
Keyword(s):  
Surface Charge ◽  
Flat Surface ◽  
Ionic Concentration ◽  
Surface Pattern ◽  
Surface Charges ◽  
Local Surface ◽  
Silica Surfaces ◽  
Pattern Size ◽  
Theoretical Predictions ◽  
Surface Patterns

The surface charge density of a nanopatterned silica decreased at the pits but increased at the tips of surface patterns. For a case of self-repeating surface structures, the average of local surface charges becomes lower than the theoretical predictions. Our phenomenological model developed as an extension to the existing flat surface theory predicts the average surface charge on a nanopatterned surface as a function of surface pattern size, ionic concentration and pH.

Microcalorimeters for X-Ray Spectroscopy

1988 ◽  
Vol 102 ◽  
pp. 41
Author(s):  
E. Silver ◽  
C. Hailey ◽  
S. Labov ◽  
N. Madden ◽  
D. Landis ◽  
...  
Keyword(s):  
High Resolution ◽  
High Efficiency ◽  
Thermal Response ◽  
Low Noise ◽  
High Resolution Spectroscopy ◽  
Superconducting Transition ◽  
Sapphire Substrates ◽  
Laboratory Plasmas ◽  
Adiabatic Demagnetization ◽  
Theoretical Predictions

The merits of microcalorimetry below 1°K for high resolution spectroscopy has become widely recognized on theoretical grounds. By combining the high efficiency, broadband spectral sensitivity of traditional photoelectric detectors with the high resolution capabilities characteristic of dispersive spectrometers, the microcalorimeter could potentially revolutionize spectroscopic measurements of astrophysical and laboratory plasmas. In actuality, however, the performance of prototype instruments has fallen short of theoretical predictions and practical detectors are still unavailable for use as laboratory and space-based instruments. These issues are currently being addressed by the new collaborative initiative between LLNL, LBL, U.C.I., U.C.B., and U.C.D.. Microcalorimeters of various types are being developed and tested at temperatures of 1.4, 0.3, and 0.1°K. These include monolithic devices made from NTD Germanium and composite configurations using sapphire substrates with temperature sensors fabricated from NTD Germanium, evaporative films of Germanium-Gold alloy, or material with superconducting transition edges. A new approache to low noise pulse counting electronics has been developed that allows the ultimate speed of the device to be determined solely by the detector thermal response and geometry. Our laboratory studies of the thermal and resistive properties of these and other candidate materials should enable us to characterize the pulse shape and subsequently predict the ultimate performance. We are building a compact adiabatic demagnetization refrigerator for conveniently reaching 0.1°K in the laboratory and for use in future satellite-borne missions. A description of this instrument together with results from our most recent experiments will be presented.

Transport and fluctuations in nonlinear-dissipative systems: role of interparticle collisions

1999 ◽  
Vol 4 ◽  
pp. 31-86 ◽  
Author(s):  
R. Katilius ◽  
A. Matulionis ◽  
R. Raguotis ◽  
I. Matulionienė
Keyword(s):  
Electric Fields ◽  
Carrier Density ◽  
Experimental Results ◽  
Dissipative Systems ◽  
Doped Semiconductors ◽  
Electron Diffusion ◽  
Electron Collisions ◽  
Electric Noise ◽  
Diffusion Phenomena

The goal of the paper is to overview contemporary theoretical and experimental research of the microwave electric noise and fluctuations of hot carriers in semiconductors, revealing sensitivity of the noise spectra to non-linearity in the applied electric field strength and, especially, in the carrier density. During the last years, investigation of electronic noise and electron diffusion phenomena in doped semiconductors was in a rapid progress. By combining analytic and Monte Carlo methods as well as the available experimental results on noise, it became possible to obtain the electron diffusion coefficients in the range of electric fields where inter-electron collisions are important and Price’s relation is not necessarily valid. Correspondingly, a special attention to the role of inter-electron collisions and of the non-linearity in the carrier density while shaping electric noise and diffusion phenomena in the non-equilibrium states will be paid. The basic and up-to-date information will be presented on methods and advances in this contemporary field - the field in which methods of non-linear analytic and computational analysis are indispensable while seeking coherent understanding and interpretation of experimental results.

An Experimental Investigation of Auditors' Liability: Implications for Social Welfare and Exploration of Deviations from Theoretical Predictions

2000 ◽  
Vol 75 (4) ◽  
pp. 429-451 ◽  
Author(s):  
Ronald R. King ◽  
Rachel Schwartz
Keyword(s):  
Experimental Investigation ◽  
Social Welfare ◽  
Strict Liability ◽  
Liability Rule ◽  
Optimal Response ◽  
Legal Regimes ◽  
Theoretical Predictions ◽  
Best Responses

This paper reports the results of an experiment designed to investigate how legal regimes affect social welfare. We investigate four legal regimes, each consisting of a liability rule (strict or negligence) and a damage measure (out-of-pocket or independent-of-investment). The results of the experiment are for the most part consistent with the qualitative predictions of Schwartz's (1997) model; however, subjects' actual choices deviate from the point predictions of the model. We explore whether these deviations arise because: (1) subjects form faulty anticipations of their counterparts' actions and/or (2) subjects do not choose the optimal responses given their anticipations. We find that subjects behave differently under the four regimes in terms of anticipation errors and departures from best responses. For example, subjects playing the role of auditors anticipate investments most accurately under the regime with strict liability combined with out-of-pocket damages, but are least likely to choose the optimal response given their anticipations. This finding implies that noneconomic factors likely play a role in determining subjects' choices.

Sticky ends in a self-assembling ABA triblock copolymer: the role of ureas in stimuli-responsive hydrogels

2019 ◽  
Vol 4 (1) ◽  
pp. 91-102 ◽  
Author(s):  
Ryan T. Shafranek ◽  
Joel D. Leger ◽  
Song Zhang ◽  
Munira Khalil ◽  
Xiaodan Gu ◽  
...  
Keyword(s):  
Self Assembly ◽  
Viscoelastic Properties ◽  
Triblock Copolymer ◽  
Thermal Response ◽  
Stimuli Responsive ◽  
Self Assembling ◽  
Polymeric Hydrogels ◽  
Aba Triblock Copolymer ◽  
Responsive Hydrogels

Directed self-assembly in polymeric hydrogels allows tunability of thermal response and viscoelastic properties.

scholarly journals A Stochastic Kinetic Type Reactions Model for COVID-19

Mathematics ◽  
2021 ◽  
Vol 9 (11) ◽  
pp. 1221
Author(s):  
Giorgio Sonnino ◽  
Fernando Mora ◽  
Pasquale Nardone
Keyword(s):  
Real Data ◽  
Stochastic Noise ◽  
Mathematical Basis ◽  
Sis Model ◽  
Theoretical Predictions ◽  
Coronavirus Infection ◽  
Massive Distribution ◽  
Second Wave ◽  
Stochastic Sis Model

We propose two stochastic models for the Coronavirus pandemic. The statistical properties of the models, in particular the correlation functions and the probability density functions, were duly computed. Our models take into account the adoption of lockdown measures as well as the crucial role of hospitals and health care institutes. To accomplish this work we adopt a kinetic-type reaction approach where the modelling of the lockdown measures is obtained by introducing a new mathematical basis and the intensity of the stochastic noise is derived by statistical mechanics. We analysed two scenarios: the stochastic SIS-model (Susceptible ⇒ Infectious ⇒ Susceptible) and the stochastic SIS-model integrated with the action of the hospitals; both models take into account the lockdown measures. We show that, for the case of the stochastic SIS-model, once the lockdown measures are removed, the Coronavirus infection will start growing again. However, the combined contributions of lockdown measures with the action of hospitals and health institutes is able to contain and even to dampen the spread of the SARS-CoV-2 epidemic. This result may be used during a period of time when the massive distribution of vaccines in a given population is not yet feasible. We analysed data for USA and France. In the case of USA, we analysed the following situations: USA is subjected to the first wave of infection by Coronavirus and USA is in the second wave of SARS-CoV-2 infection. The agreement between theoretical predictions and real data confirms the validity of our approach.

Prediction of Ball Motion in High-Speed Thrust-Loaded Ball Bearings

1976 ◽  
Vol 98 (3) ◽  
pp. 463-469 ◽  
Author(s):  
C. R. Gentle ◽  
R. J. Boness
Keyword(s):  
Computer Program ◽  
High Speed ◽  
Ball Bearing ◽  
Viscoelastic Behavior ◽  
Specific Situation ◽  
Fluid Models ◽  
Ball Bearings ◽  
Theoretical Predictions ◽  
Ball Motion

This paper describes the development of a computer program used to analyze completely the motion of a ball in a high-speed, thrust-loaded ball bearing. Particular emphasis is paid to the role of the lubricant in governing the forces and moments acting on each ball. Expressions for these forces due to the rolling and sliding of the ball are derived in the light of the latest fluid models, and estimates are also made of the cage forces applicable in this specific situation. It is found that only when lubricant viscoelastic behavior is considered do the theoretical predictions agree with existing experimental evidence.

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