Gaussian Oscillator Research Articles

Study of P+10,11Be elastic scattering using different potentials at low energies

A microscopic approach was used to analyze the elastic scattering of protons on [Formula: see text]Be at incident energies of 9.1, 15.1, 39.1, and 59.3[Formula: see text]MeV/nucleon for [Formula: see text]Be and [Formula: see text]Be (38.4[Formula: see text]MeV/nucleon and 49.3[Formula: see text]MeV/nucleon) within the framework of single folding (SF) and São-Paulo (SP) potentials. Also, the energy dependence of the reaction cross-sections of the considered reactions is investigated. The study was performed using FRESCO code on the free parameters ([Formula: see text] and [Formula: see text]). The DFPOT code was used to compute the SF and SP potentials microscopically for the real and imaginary parts of the optical potential (OP), respectively. The OP was derived using two different nuclear density distributions since [Formula: see text]Be as Gaussian–Gaussian (GG) [Formula: see text] and Gaussian–Oscillator (GO) [Formula: see text], and the effective N–N interactions were represented in the Gaussian form. The resulting differential cross-sections agreed well with the given experimental data.

Synthesis and characterization of Zinc Oxide thin films deposited by Spray Pyrolysis technique for possible applications in solar cells

In the present study, the synthesis and characterization of ZnO thin films deposited at 300, 350 and 400°C using the Ultrasonic Spray Pyrolysis technique, as a possible candidate for electron transport layer (ETL) in solar cells is reported. X-ray diffraction (XRD) analysis revealed that the films have a hexagonal wurtzite phase with a preferential orientation (101) with good polycrystallinity. The mean crystallites size based on the Debye-Scherrer model was calculated, indicating that the size of the crystals decreases as the deposition temperature increases. The optical characterization of the material showed a high transmittance in the visible region (85-99%) with which the optical band gap (3.06-3.29 eV) was determined. The thickness, surface roughness and optical constants (n and k) were determined by Spectroscopic Ellipsometry using the Gaussian oscillator model. Hall Effect revealed a low resistivity of 1-4 Ω cm and a high mobility of charge carriers (304 cm2/Vs) in the films. Due to all these properties, ZnO is considered an ideal material for optoelectronic applications, as well as a material with potential to be used as ETL in solar cells.

Optical characterisation of dyed liquid crystal cells

ABSTRACT The guest-host liquid crystal display, first proposed in 1968, relies on controlling the orientation of dichroic dyes dissolved in a nematic liquid crystal host. Controlling the orientation of the liquid crystal and of the dissolved dye with an electric field allows control of the transmittance of the cell. Knowing the dielectric properties at optical frequencies of the dye and liquid crystal mixtures is crucial for the optimal design of guest-host liquid crystal devices. In this work, the dielectric functions of various layers in liquid crystal cells are described by models obeying the Kramers-Kronig relations: the Sellmeier equation for transparent layers and the causal Gaussian oscillator model for absorbing layers. We propose a systematic way to accurately model the dielectric response of each layer by minimising the sum of squared differences between the measured transmittance spectrum of a guest-host cell in the near-UV/vis range and the prediction of the transmittance of the modelled multilayer structure. By measuring the transmittance for incident light polarised parallel and perpendicular to the nematic director allows us to separately characterise the two principal dielectric functions of the uniaxial sample. Our results show that the causal Gaussian oscillator model can accurately characterise the dielectric functions of dyes in liquid crystals.

Gaussian dispersion analysis in the time domain: Efficient conversion with Padé approximants

We present an approach for adapting the Gaussian dispersion analysis (GDA) of optical materials to time-domain simulations. Within a GDA model, the imaginary part of a measured dielectric function is presented as a sum of Gaussian absorption terms. Such a simple model is valid for materials where inhomogeneous broadening is substantially larger than the homogeneous linewidth. The GDA model is the essential broadband approximation for the dielectric function of many glasses, polymers, and other natural and artificial materials with disorder. However, efficient implementation of this model in time-domain full-wave electromagnetic solvers has never been fully achieved. We start with a causal form of an isolated oscillator with Gaussian-type absorption — Causal Dawson-Gauss oscillator. Then, we derive explicit analytical formulas to implement the Gaussian oscillator in a finite-difference time-domain (FDTD) solver with minimal use of memory and floating point operations. The derivation and FDTD implementation employ our generalized dispersive material (GDM) model — a universal, modular approach to describing optical dispersion with Padé approximants. We share the FDTD prototype codes that include automated generation of the approximants and a universal FDTD dispersion implementation that employs various second-order accurate numerical schemes. The codes can be used with non-commercial solvers and commercial software for time-domain simulations of light propagation in dispersive media, which are experimentally characterized with GDA models. Program summaryProgram Title:MADISCPC Library link to program files:https://doi.org/10.17632/x69b4krsy8.1Licensing provisions: GPLv3Programming language: MATLABNature of problem: The problem of efficient time-domain simulation of the Gaussian absorption is essential for wideband modeling of the optical response from materials with inhomogeneous spectral broadening, such as glasses, polymers, and other natural and artificial composite materials with structural or phase disorder.Solution method: A Coupled Oscillator (CO) approximation to the Gaussian absorption in both the frequency and time domains is derived to solve this problem. The time-domain CO approximation is coupled to the finite-difference time-domain (FDTD) solver for the Maxwell equations in the MADIS (MAterial DIspersion Simulator) package. Verification of the Maxwell solvers' accuracy and stability is performed with the FDTD solver coupled to a compact universal implementation of the CO model, employing second-order schemes (either ADE or RC). Code prototypes of these efficient CO schemes can be ported to other methods and platforms for implementing the Gaussian absorption in open-source codes or commercial software.Additional comments including restrictions and unusual features: Patent pending. Restrict any commercial use, including for profit reproduction.

Two-body problems in the orthogonal condition model

In this work we investigate the 0+, 2+, 4+, 6+, 8+ and 10+resonant states of the + system and each advantage of Gaussian and Harmonic Oscillator basis wave functions in the complex scaled orthogonal condition model (CSOCM).

Optical properties of plasma‐treated PEEK: Monitoring colour and crystallinity for applications in medicine and dentistry using ellipsometry

AbstractPoly‐ether‐ether‐ketone (PEEK) is a widely used and versatile polymer. Here, we use ellipsometry to determine the wavelength‐dependent optical properties of PEEK before and after the surface is modified by plasma immersion ion implantation (PIII), a technique that renders the surface hydrophilic and bio‐active. Lorentz and Gaussian oscillator models are used to fit the data for extraction of the optical constants and the dielectric function. The effect of PIII, even for short treatment times, changes the optical properties of PEEK, indicative of an amorphisation of the initial semicrystalline structure that broadens the electronic density of states distribution. The progressive changes in the optical properties with treatment time allow assessment of colour changes and estimation of ion dose in the PIII process.

Turbulence-resilient pilot-assisted self-coherent free-space optical communications using automatic optoelectronic mixing of many modes

In free-space optical communications that use both amplitude and phase data modulation (for example, in quadrature amplitude modulation (QAM)), the data are typically recovered by mixing a Gaussian local oscillator with a received Gaussian data beam. However, atmospheric turbulence can induce power coupling from the transmitted Gaussian mode to higher-order modes, resulting in a significantly degraded mixing efficiency and system performance. Here, we use a pilot-assisted self-coherent detection approach to overcome this problem. Specifically, we transmit both a Gaussian data beam and a frequency-offset Gaussian pilot tone beam such that both beams experience similar turbulence and modal coupling. Subsequently, a photodetector mixes all corresponding pairs of the beams’ modes. During mixing, a conjugate of the turbulence-induced modal coupling is generated and compensates the modal coupling experienced by the data, and thus the corresponding modes of the pilot and data mix efficiently. We demonstrate a 12 Gbit s−1 16-QAM polarization-multiplexed free-space optical link that is resistant to turbulence.

Systematic analysis of 17,19F and 16,17O elastic scattering on 208Pb just below the coulomb barrier

The 17F, 17O + 208Pb elastic scattering at 90.4 and 78 MeV (just below coulomb barrier), respectively, are analyzed within the framework of the double folding approach. The folded potentials are constructed by folding the density independent M3Y effective nucleon-nucleon interaction over the nucleon density distribution of 17F and its mirror 17O nuclei. Gaussian oscillator (GO) density distribution is considered to represent the (core16O+nucleon) structure for 17F and 17O. The knock-on exchange potentials are introduced to construct the real semi-microscopic potentials. The imaginary potentials are supplemented to derive potentials in two forms: either phenomenological Woods-Saxon (WS) or the same form as real folded potentials and different strengths. Moreover, the analysis of 19F, 16O + 208Pb elastic scattering at 91, 78 MeV energies, in that order, is applied in comparison to the 17F, 17O + 208Pb systems in an endeavor to investigate the behavior and properties of 17F and 17O projectiles.

Study of the proton halo structure of nuclei 23Al and 27P using the binary cluster model

The neutron, proton, and matter densities of the ground state of the proton-rich 23Al and 27P exotic nuclei were analyzed using the binary cluster model (BCM). Two density parameterizations were used in BCM calculations namely; Gaussian (GS) and harmonic oscillator (HO) parameterizations. According to the calculated results, it found that the BCM gives a good description of the nuclear structure for above proton-rich exotic nuclei. The elastic form factors of the unstable 23Al and 27P exotic nuclei and those of their stable isotopes 27Al and 31P are studied by the plane-wave Born approximation. The main difference between the elastic form factors of unstable nuclei and their stable isotopes is caused by the variation in the proton density distributions, especially the details of the outer part. Moreover, the Glauber model is used to calculate the matter rms radii and reaction cross-section of these exotic nuclei. The calculated results of the mentioned nuclei give a good accordance with the experimental data.

Study of the Exotic Structure of Neutron-Rich 14B and 17C Nuclei Using the Binary Cluster Model

The neutron, proton, and matter densities of the ground state of the 14B and 17C exotic nuclei are analyzed using the binary cluster model (BCM). Two density parameterizations are used in BCM calculations namely; Gaussian (GS) and harmonic oscillator (HO) parameterizations. According to the calculated results it found that, the BCM gives a good description of the nuclear structure for above neutron-rich exotic nuclei. The elastic form factors of theunstable 14B and 17C exotic nuclei and those of their stable isotopes 10B and 13C are determined using the plane-wave Born approximation. The main difference between the elastic form factors of unstable nuclei and their stable isotopes is due to the difference in the center of mass correction. Moreover, the Glauber model is used to calculate the matter rms radii and reaction cross section of these exotic nuclei. The calculate results of the mentioned nuclei give a good accordance with the experimental data.

On twin peak quasi-periodic oscillations resulting from the interaction between discoseismic modes and turbulence in accretion discs around black holes

ABSTRACT Given the peculiar and (in spite of many efforts) unexplained quasi-periodic oscillation twin peak phenomena in accretion disc power spectral density observations, the present exploratory analytical article tries to inquire deeper into the relationship between discoseismic modes and the underlying driving turbulence in order to assess its importance. We employ a toy model in the form of a Gaussian white noise-driven damped harmonic oscillator with stochastic frequency. This oscillator represents the discoseismic mode. (Stochastic damping was also considered, but interestingly it was found to be less relevant for the case at hand.) In the context of this model, we find that turbulence interacts with disc oscillations in interesting ways. In particular, the stochastic part in the oscillator frequency behaves as a separate driving agent. This gives rise to 3:2 twin peaks for some values of the physical parameters, which we find. We conclude with the suggestion that the study of turbulence be brought to the forefront of disc oscillation dynamics, as opposed to being a mere background feature. This change of perspective carries immediate observable consequences, such as considerably shifting the values of the (discoseismic) oscillator frequencies.

Study on broadband optical constants of yttrium fluoride thin films deposited by electron beam evaporation

In this paper, the broadband optical constants of YF3 thin films prepared by electron beam evaporation were studied (0.2 μm–14 μm), which are consistent with the data reported in other literature. The composite dispersion physical model of the optical constants of YF3 thin films was established by using Cody-Lorentz model and Gaussian oscillator model, which is employed in this study and is universal for YF3 thin films with water defects. The water absorption of the YF3 thin films occurs at 3251.9 cm−1 and 3454.3 cm-1 representing the symmetrical stretching vibration and asymmetric stretching vibration frequency of the HOH bond, and 1640.8 cm−1 representing the shear vibration frequency of the HOH bond. In addition, the Raman spectra of amorphous YF3 thin film shows that the intrinsic vibrational frequencies are 383 cm−1 and 462 cm−1. Based on the electron interband transition and the micro-structural vibration characteristics mentioned above, the broadband optical constants of the YF3 thin film are obtained, which makes up the deficiency of extinction coefficient data of YF3 thin film.

The Neutron Halo Structure of 11Be and 14Be Nuclei Studied by the Binary Cluster Model

We have calculated some of the basic structural properties such as the ground state proton, neutron and matter densities and elastic form factors of halo nuclei namely, 11Be and 14Be using the binary cluster model (BCM) within the Gaussian and harmonic oscillator wave functions. The halo nuclei have been considered as a compact core with loosely bound valence neutron(s) forming the halo. The comparison between the calculated and experimental matter density distributions supports the halo structure for 11Be [14Be] where the valence one neutron [two neutrons] occupy the 1p1/2 [(2s1/2)2] orbital. We have also calculated the reaction cross sections for these nuclei using the Glauber model with an optical limit approximation at low and high energies. The calculated of these nuclei give a good description of experimental data at both low and high energies.

Thermal hysteresis measurement of the VO2 dielectric function for its metal-insulator transition by visible-IR ellipsometry

The real and imaginary parts of the dielectric function of VO2 thin films, deposited on r-plane sapphire via pulsed laser deposition, are measured by means of visible-infrared ellipsometry for wavelengths ranging from 0.4 to 15 μm and temperatures within its phase transition. For both the insulator-to-metal (heating) and metal-to-insulator (cooling) transitions, it is shown that the two ellipsometric signals exhibit three temperature-driven behaviors, which are well described by appropriate combinations of the Tauc-Lorentz, Gaussian, and Drude oscillator models. By fitting Bruggeman's effective medium model for the dielectric function to the corresponding measured experimental values, using the volumetric fraction of the VO2 metallic domains as a fitting parameter for different temperatures within the VO2 phase transition, we have found that this model is suitable for describing the dielectric function in visible and near-infrared wavelengths (∼0.4 to ∼3.0 μm), but it generally fails for longer infrared ones. Furthermore, the hysteresis loop of the VO2 emissivity averaged over a relevant interval of wavelengths is determined and shown to vary from ∼0.49, in the insulator phase, to ∼0.16, in the metallic one. These values, based on the VO2 dielectric function, are consistent with previous measurements reported in the literature, and therefore, our measured data are expected to be useful for describing the behavior of VO2 films involved in optical and radiative applications.

Spectroscopic ellipsometry investigations of Cd-Se thin film electrochemically prepared

Binary Cadmium selenium (Cd-Se) thin film deposited onto glass substrate coated by indium tin oxide (ITO) using electrodeposition method at room temperature. Structural, morphological and optical properties has been investigated by X-ray diffraction (XRD), scanning electron microscope (SEM) and variable angle spectroscopic ellipsometry (VESA). XRD pattern shows that the nature film is polycrystalline where both (hexagonal) Se and (hexagonal) CdSe crystalline phases coexist. Based on the (SEM) images, it was found that micro-structures consist of dense layers or agglomerates suggesting an acceptable adhesion between ITO layers and Cd-Se films. VESA measurements on the Cd-Se are presented in the energy range of 1.–5 eV with different incident angles and at room temperature. The experimental data of SE were fit using a linear summation from Gaussian and Tauc-Lorentz oscillator functions. Each function was employed to fit a range of absorption spectrum from ultraviolet, visible and infrared regions. Optical constants such as pseudo refractive index, pseudo extinction coefficient, real and imaginary parts of the pseudo dielectric function were determined. The optical energy band gap (Eg) of prepared film is 2.16 and 1.14 eV for the direct allowed and indirect allowed transitions, respectively.

Heat-coupled Gaussian continuous-wave double-pass optical parametric oscillator: thermally induced phase mismatching for periodically poled MgO:LiNbO3 crystal.

In this paper, a model describing the thermal effects on the optical parametric oscillator (OPO) of Gaussian continuous waves in double-pass cavities is presented. Eight equations, including forward and backward nonlinear waves, heat, and thermally induced phase mismatching equations, were coupled and solved simultaneously to investigate the effect of heat generation on the OPO's efficiency. The model was applied for a periodically poled MgO:LiNbO3 crystal with an excellent agreement with experimental data. The numerical calculations have been carried out by a homemade code written in Intel FORTRAN, which used a finite difference method.

Sensitivity of the halo nuclei-12C elastic scattering at incident nucleon energy 800 MeV to the halo density distribution

In the framework of Glauber optical limit approximation where Coulomb effect is taken into account, the elastic scattering differential cross section for halo nuclei with \({}^{12}{\text{C}}\) at 800 MeV/N has been calculated. Its sensitivity to the halo densities and the root mean square of the core and halo is the main goal of the current study. The projectile nuclei are taken to be one-neutron and two-neutron halo. The calculations are carried out for Gaussian–Gaussian, Gaussian–Oscillator and Gaussian-2 s phenomenological densities for each considered projectile in the mass number range 6–29. Also included a comparison between the obtained results of phenomenological densities and the results within the microscopic densities LSSM of \({}^{6}{\text{He}}\) and \({}^{11}{\text{Li}}\) and microscopic densities GCM of \({}^{11}{\text{Be}}\) where the density of the target nucleus \({}^{12}{\text{C}}\) obtained from electron-\({}^{12}{\text{C}}\) scattering is used. The zero range approximation is considered in the calculations. We found that the sensitivity of elastic scattering differential cross section to the halo density is clear if the nucleus appears as two clear different clusters, core and halo.

Gaussian oscillator model of the dielectric constant of SiO2 thin film in infrared range

SiO2 thin film is one of the most important low refractive index materials in the area of optical thin films. It is always used in the design and preparation of many kinds of multilayer films. The dielectric constant of the SiO2 thin film is a key characteristic for design of the multilayer thin film. The composite Gaussian oscillator model is one of the most important dispersion models for the dielectric constant of the amorphous SiO2 in the anomalous dispersion regime in the infrared range. More and more researchers have focused on the number and the physical meaning of the oscillators in the composite oscillator. A method to determine the SiO2 thin film oscillator quantity was proposed. In this method, the quantity of oscillator peaks was equivalent to the oscillator number of chemical composition, based on the factor analysis technology of chemometrics. Concretely, the composite oscillators of the dielectric constant were equivalent to the mixture, and the independent oscillators were equivalent to the compositions of the mixture. The absorbance of the mixture changed with the physical thickness of the thin film. Eight SiO2 film samples with different thickness were prepared on the Si substrate by the ion beam sputtering deposition. The infrared transmittances of the eight samples were used as elements in the spectral matrix. There were nine Gaussian oscillators in the range of 400-4000 cm-1, which was determined by the factor analysis technology. The dielectric constant of the SiO2 thin film in this range was obtained by the inverse calculation from the spectral transmittance. It provides the inverse calculation result for the dielectric constant of the SiO2 thin film with a specific physical meaning. By analyzing the dielectric constant in the range of 400-900 cm-1, the symmetric stretching vibrational frequency and the in-plane rocking frequency of the Si-O-Si bond of the SiO2 thin film can be obtained. Compared with fused silica, the symmetric stretching vibrational frequency increased while the rocking frequency was reduced. In fact, the frequency shifts are caused by the strain of the thin film. By analyzing the dielectric constant in the range of 900-1500 cm-1, four anti-symmetric stretching vibrational frequencies of the Si-O-Si bond in the SiO2 thin film were obtained. They have a certain corresponding relation with the anti-symmetric stretching vibrational frequency of the Si-O-Si bond in the fused silica. What's more, by analyzing the dielectric constant in the range of 3000-4000 cm-1, the water-cut (or hydroxyl) chemical defects in the films were confirmed. The chemical defects can influence the dielectric constant in the whole infrared range.

Eagle XG® glass, optical constants from 230 to 1690 nm (0.73 - 5.39 eV) by spectroscopic ellipsometry

Eagle XG® glass is widely used in the manufacture of electronic displays. Spectroscopic ellipsometry and transmission data for this material were obtained from 193 to 1690 nm. The optical constants of the material were then modeled from 230 to 1690 nm. The data were initially fit with a basis spline (B-spline), and these results were used as the starting point for either a two-Gaussian oscillator model or a Tauc-Lorentz (T-L) + Gaussian oscillator model. Both models gave good fits, with unweighted mean squared error values of ca. 1.1. Samples were provided by Corning Incorporated directly from their production facility.

Approximate Solution of Schrödinger Equation with Pseudo-Gaussian Potential Viewed as a Perturbation

Abstract We consider the Schrödinger equation with pseudo-Gaussian potential and point out that it is basically made up by a term representing the harmonic oscillator potential and an additional term, which is actually a power series that converges rapidly. Based on this observation the system can be considered as a perturbation of harmonic oscillator. The perturbation method is used to approximate the energy levels of pseudo- Gaussian oscillator. The results are compared with those obtained in the analytic and numeric case.