A5082594793- Spectroscopy and Quantum Chemical Studies
- 2D Materials and Applications
- Photonic Crystals and Applications
- Chalcogenide Semiconductor Thin Films
- Advanced Measurement and Metrology Techniques
- Photonic and Optical Devices
- Photochemistry and Electron Transfer Studies
- Quantum and electron transport phenomena
- Photorefractive and Nonlinear Optics
- Advanced Chemical Physics Studies
- Ultrasonics and Acoustic Wave Propagation
- Graphene research and applications
- Advanced Fiber Optic Sensors
- Chemical Safety and Risk Management
- Occupational Health and Safety Research
- Catalysis and Oxidation Reactions
- Thermography and Photoacoustic Techniques
- Strong Light-Matter Interactions
- Glass properties and applications
- Plasmonic and Surface Plasmon Research
- Health Services Management and Policy
- Phase-change materials and chalcogenides
- Atherosclerosis and Cardiovascular Diseases
- Quantum Dots Synthesis And Properties
- Adipokines, Inflammation, and Metabolic Diseases
Wake Forest University
2021-2024
University of California, San Diego
2023-2024
Centro de Investigaciones en Optica
2009-2022
University of Alabama in Huntsville
2006
Steacie Institute for Molecular Sciences
2000
We formulate a theoretical approach of surface second-harmonic generation from semiconductor surfaces based on the length gauge and electron density operator. Within independent particle approximation, nonlinear second-order susceptibility tensor ${\ensuremath{\chi}}^{\mathrm{a}\mathrm{b}\mathrm{c}}(\ensuremath{-}2\ensuremath{\omega};\ensuremath{\omega},\ensuremath{\omega})$ is calculated, including in one unique formulation (i) scissors correction, needed to have correct value energy band...
Si(111) surfaces with covalently attached monolayers have been investigated by optical second harmonic generation (SHG). The are modified wet chemical procedures and studied SHG in air or a liquid immersion cell, using fundamental wavelengths λ = 775 830 nm. Results reported for including −H, −C10H21 (decyl), −O−C10H21 (decyloxy) −Cl, surface native oxide film. rotational anisotropy of the efficiency has estimates made relative values nonlinear susceptibilities bulk response. mechanisms that...
We present the three-layer model to calculate surface second-harmonic generation (SSHG) yield. This considers that is represented by three regions or layers. The first layer vacuum region with a dielectric function ${\ensuremath{\epsilon}}_{v}(\ensuremath{\omega})=1$ from where fundamental electric field impinges on material. second thin $(\ensuremath{\ell})$ of thickness $d$ characterized ${\ensuremath{\epsilon}}_{\ensuremath{\ell}}(\ensuremath{\omega})$, and it in this SSHG takes place....
We develop explicit expressions for the surface second-harmonic radiation yield using three layer model. derive that can be applied to systems without and symmetry considerations, then reduce them (111), (110), (100) symmetries.
In this work, we report linear and non-linear spectroscopic measurements of chemically-grown layered (from one to 37 quintuple layers) bulk alpha-In2Se3 samples over a photon energy range 1.0--4 eV, compare with ab initio density functional theory calculations, including bandstructures G0W0 calculations.
We perform a systematic study of the macroscopic dielectric function and electron energy loss (EEL) spectra for graphite. obtain dispersion behavior $\ensuremath{\pi}$ plasmon, as momentum transfer $q$ two nonequivalent paths that traverse first four Brillouin zones. carry out these calculations within both time-dependent density functional theory (with exchange-correlation functionals) Bethe-Salpeter equation. Additionally, we explore effects using complete excitonic Hamiltonian all...
Despite the exponential growth in demand for advanced computational skills driven by big data, machine learning, and artificial intelligence, higher education institutions still face a significant shortage of dedicated course offerings pertaining to High Performance Computing (HPC). This educational deficiency not only hampers preparedness undergraduate students cutting-edge postgraduate programs but also impairs their readiness enter dynamic workforce increasingly reliant on sophisticated...
We present a generalization of the three-layer model to calculate surface second harmonic generation (SSGH) yield, that includes depth dependence nonlinear order susceptibility tensor $\boldsymbol{\chi}(-2\omega;\omega,\omega)$. This considers is represented by three regions or layers. The first layer semi-infinite vacuum region with dielectric function $\epsilon_{v}(\omega)=1$, from where fundamental electric field impinges on material. thin ($\ell$) thickness $d$ characterized...
Abstract Abstractauthoren We present a theoretical study of the optical spin injection, current and second harmonic generation two 50% hydrogenated graphene structures: C H ‐alt ‐up. Optical under incidence circularly polarized light onto nonmagnetic semiconductors, creates spin‐polarized electrons in conduction bands. injection second‐harmonic are nonlinear second‐order effects that allowed materials without inversion symmetry. The results calculated full electronic band structure scheme...
We present a simple model to study the effects of displacing single atomic monolayer on linear optical properties material. As an example, we calculate change in reflectance Si(111)(1 × 1):H slab after disordering successively deeper layers. find that varies significantly at photon energies above 2.0 eV, and disordered produces larger than relaxed slab. The results also show quantitative difference contribution from odd even layers calculated reflectance. This simplified is first approach;...
A slip ring is a rotary electrical interface, collector, swivel or joint. It component architecture that can perform continuous data transfer between and stationary structure. few of the numerous approaches for transferring include contact non-contact methods which use wires, radio waves, optical fibers even liquid as media. However, they all suffer inherent drawbacks in durability, reliability, stability, electromagnetic interference speed. The system introduced this paper alleviates many...
We characterise from first principles the structure and bonding in 2D heterosystems made of bilayers or trilayers graphene graphene-like-materials (GLMs), stacked on top each other, functionalized using hydrogen. The effects electron band gap opening tuning, as well formation strongly bonded multilayers have been predicted. linear nonlinear optical vibrational spectra were modelled for hydrogenated alternating monolayers with insulating hexagonal boron nitride (h-BN) films. Here we focus...
The upper left (u.l.) panel represents the 50% hydrogenated graphene structure C16H8-up, which upon incidence of a circularly polarized light beam (in red) creates spin-polarized electrons in conduction bands. degree spin polarization along three Cartesian directions i = x,y,z (see right diagram) can reach more than for , as represented by solid black arrows pointing down u.l. image. same induce an electronic injection current, shown thick arrow sketch. According to calculations Zapata-Peña...
We present a straight forward and practical method for joining pneumatically floated optical tables with no previous preparation. In order to demonstrate this we joined two in an uncentered "T-shape" using twenty four stainless steel plates (SSP), used Michelson interferometer compare the stability of entire "T"-structure versus one its parts alone, finding that they both show similar rigidity. also evaluated performance different master-salve leg configurations by calculating stress on...
We present a simple and practical method for joining pneumatically floated optical tables. In order to demonstrate this we joined two tables in an uncentered "T-shape", used Michelson interferometer compare the stability of entire "T-structure" versus one its parts alone finding that they both show similar rigidity. also found optimal master-slave leg configuration by calculating stress on joint confirmed calculations interferometry. The vibration damping against unjoined was measured...
Although the general properties of rare earths' electronic states and transitions are well understood, much less is known regarding relationships between them band a crystal lattice. These interactions can enhance or inhibit performance provide mechanisms for manipulating material's optical properties. Up-conversion ZrO<sub>2</sub>:Tm<sup>3+</sup>, Yb<sup>3+</sup>, Er<sup>3+</sup>, Ho<sup>3+</sup> nano-crystalline samples were synthesized by sol-gel method emission analyzed as function...