A5067353011- Laser Design and Applications
- Carbon Nanotubes in Composites
- Semiconductor materials and devices
- Graphene research and applications
- Oceanographic and Atmospheric Processes
- Nanowire Synthesis and Applications
- Laser Material Processing Techniques
- Laser-induced spectroscopy and plasma
- Laser-Matter Interactions and Applications
- 2D Materials and Applications
- Building materials and conservation
- Organometallic Complex Synthesis and Catalysis
- Metal and Thin Film Mechanics
- Ionic liquids properties and applications
- Electrochemical Analysis and Applications
- Molecular Junctions and Nanostructures
- Diamond and Carbon-based Materials Research
- Structural Analysis of Composite Materials
- Spectroscopy and Laser Applications
- Ocular and Laser Science Research
- Solid State Laser Technologies
- Quantum Dots Synthesis And Properties
- Chalcogenide Semiconductor Thin Films
- Photonic and Optical Devices
- Arctic and Antarctic ice dynamics
University of the West Indies
2024
University of Manchester
1956-2024
Wellcome Centre for Cell-Matrix Research
2024
University of Southampton
2012-2022
University of the West
1990-2021
Australian Antarctic Division
2021
University College Cork
2019
Arup Group (United Kingdom)
2012-2019
Lam Research (United States)
2018-2019
Colorado School of Mines
2019
This paper presents a tutorial review of the self-induced thermal distortion laser radiation propagating in absorbing media. The beam is result heating path by absorption small fraction power medium which changes index refraction and therefore distorts beam. Thermal-blooming effects can limit powers be effectively propagated through atmosphere, or media absorb such as industrial laboratory environments, liquid gas cells, even active themselves. In this paper, we steady-state blooming CW...
The fabrication of next-generation semiconductor devices has created a need for low-temperature (≤400 °C) deposition highly-conformal (>95%) SiO2, SiNx, and SiC films on high-aspect-ratio nanostructures. To enable the growth these Si-based dielectric films, manufacturers are transitioning from chemical vapor to atomic layer (ALD). Currently, SiO2 deposited using ALD already being integrated into device manufacturing. However, substantial processing challenges remain complete...
A theoretical model is developed that predicts the steady-state self-induced thermal distortion of a laser beam in an absorbing medium flowing transverse to direction propagation. general perturbation solution obtained appropriate when effects are small. computer iteration this performed obtain results applicable over increased range conditions. The diffraction neglected, and therefore limited near-field or where caustic infinite intensity predicted as result self-focusing associated with...
The gas-breakdown threshold or the minimum power density required to ionize a gas with 10.6-μ-wave-length radiation has been examined using of Q-switched CO2 laser. studies show that focused beam cannot initiate breakdown process for intensities as high 109 W/cm2. If an initial low degree ionization is provided by external source, subsequent growth in agreement cascade model evidenced experimentally determined pressure and laser-radiation frequency dependence.
Abstract Hybridisation of electronic bands two-dimensional materials, assembled into twistronic heterostructures, enables one to tune their optoelectronic properties by selecting conditions for resonant interlayer hybridisation. Resonant hybridisation qualitatively modifies the excitons in such transforming these optically active modes superposition states and intralayer excitons. For MoSe 2 /WSe strong hybridization both single particle excitonic can occur via tunnelling. Here we use...
Anticyclones originating from the Loop Current are known to propagate into western Gulf of Mexico. Their frequency generation, their long lifetimes, and satellite data suggest that at any one time or more eddies may occupy Gulf. Given eddy sizes (100–200 km) geometric confinement Gulf, it would appear there be significant interactions individual and/or with bottom topography. These possibilities explored through use a two-layer primitive equation model. Variable parameters in this model...
The propagation of an isolated mesoscale eddy onto a western bounding topographic slope is examined through the use two-layer, primitive equation, numerical model. Variable parameters in study are sense rotation (cyclonic/anticyclonic), vertical structure (baroclinic, barotropic), and layer thickness ratio (H1/H2). Eddy size strength (rotational velocity) frictional parameterization fixed. Dispersion induced by planetary beta-effects, giving asymmetric distribution. This distribution allows...
The threshold for generation of high-density plasma caused by the interaction laser radiation with solids is examined theoretically. developed semiquantitative model applicable predicting generating laser-supported absorption waves, absorbing produced on surfaces high-intensity radiation, and also aerosol-induced gas breakdown, commonly referred to as dirty air breakdown. In developing model, vapor density generated solid calculated then intensity required cascade ionize full ionization...
Gas-breakdown threshold measurements with 10.6-μ wavelength radiation have been made in air, argon, and helium. The was determined 50- 200-nsec-duration pulses found to depend on the peak intensity of pulse, showing that breakdown process is a balance between rate energy absorption some loss. also decreased as focal spot size increased from 10−2 10−1 cm, loss reduced for larger beam sizes. varied inversely gas pressure 0.1 4 atm, which evidence mechanism not electron diffusion but must be...
Electrodeposition is a widely used materials-deposition technology with number of unique features, in particular, the efficient use starting materials, conformal, and directed coating. The properties solvent medium for electrodeposition are critical to technique's applicability. Supercritical fluids solvents which give wide range advantages chemistry general, materials processing particular. However, applicable approach from supercritical has not yet been developed. We present here method...
Laser supported combustion (LSC) waves, subsonically propagating plasma, are ignited from solid targets and maintained in atmospheric pressure air using focused high−power, as high 15 kW, cw CO2 laser radiation. The intensity necessary to ignite LSC Ii, is measured for steel aluminum a function of beam focal spot diameter wind velocity transverse the axis needed maintain such waves air, Im. In absence wind, quantities Ii Im essentially identical diameters smaller than 0.1 cm, but...
The steady-state thermal defocusing of CO <inf xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</inf> laser radiation (10.6-μ wavelength) in gases has been investigated experimentally and theoretically. increase the beam diameter change intensity caused by self-induced index refraction variations absorbing studied as a function power, absorption coefficient gas, pathlength. A Mach-Zehnder interferometer was used to examine directly changes which...
The effect of kinetic cooling due to the absorption 10.6-μ CO2 laser radiation in atmosphere has recently been predicted. In this letter, experimental evidence for is presented. Transient-density increases have observed CO2–N2 mixtures following propagation an ∼ 1-μsec 0.5-J pulse through gas. experiments were performed with varying concentrations and subsequent heating effects are explained using usual three-level approximation vibrational-energy transfer CO2–N2, together known relaxation rates.
Delamination processes absorb significant amounts of energy in laminated glass windows when they are subjected to blast loads. Blast tests were performed previously and their results had been used calculate the loads imposed on support systems. In this research, delamination process at realistic deformation rates was studied understand reaction force response obtained. Laboratory tensile pre-cracked specimens investigate behaviour. The experiments confirmed presence a plateau...
The breakdown threshold with 10.6−μ wavelength CO2 laser radiation induced by particles is reported. Single solid of different materials and sizes were suspended electrodynamically at the focus a pulsed TEA thresholds for vaporization also particle−induced measured. Th intensity order 108 W/cm2, independent particle size material represents limiting that can be propagated through an aerosol−laden atmosphere.
Abstract The spatial structure and temporal characteristics of sea breeze the associated coastal ocean response in northwest Gulf Mexico are investigated using moored instruments, hydrographic stations, wind measurements. Near study area 30°N, motions diurnal–inertial band (DIB) may be significantly enhanced by a near-resonant condition between local inertial diurnal forcing frequencies. Wavelet analysis is used to quantify results. Results indicate that sea-breeze variability peaks summer...
Experiments have been carried out to study the ionization buildup and gas breakdown processes in focal volume of an intense 10. 6-μ laser pulse atmospheric-pressure helium preionized various levels electron density. With no preionization flux required for was agreement with results obtained by previous authors, showed same dependence on size. However, a high initial density, threshold much lower dependence. The indicate that is controlled cascade processes, while it dominated other effects...