Physics Commons^™

Effects Of Post-Deposition Annealing On Room Temperature Deposited Zinc Oxide, Ishan Rayen

Macalester Journal of Physics and Astronomy

This study focuses on thin film deposition of ZnO onto a glass slide using magnetron sputtering. The focus of the study is to understand the effects of post-deposition annealing temperatures. The goal is to optimize crystal quality, conductivity, and transparency. The results attempt to answer the effects of room temperature deposition and changes in film properties once annealed. Annealing temperatures ranged from 100°C to 400°C with an annealing time of 30 minutes. This found an ideal temperature of 250°C for post-deposition annealing, resulting in approximately 3.86 times more conductivity with little to no decrease in transparency. However crystal quality did …

Float Like A Butterfly, Sting Like A Bee!, Kobe D. Rome

SACAD: John Heinrichs Scholarly and Creative Activity Days

By injecting an electron into the empty pie* molecular orbital (LUMO) of Amino Acids in gas phase, we measure the Vertical Attachment Energies (VAEs) for the formation of short-lived anion states of these species using electron transmission spectroscopy (ETS). Our ETS study, a first of its kind to measure the VAE for the simplest of proteins, Glycine-Glycine (Gly-Gly), is currently in progress. Based on our previous measurements for several Amino Acids including Glycine, we expect a common range of attachment energy (1.50 – 2.00 eV) for Gly-Gly.

Advancements In Characterization Of Ancient Potteries From Southeast Asia: A Review Of Analytical Techniques, Chitnarong Sirisathitkul

Makara Journal of Science

Ancient potteries offer valuable information regarding technological advancements, life dynamics, cultural diversity, and trade routes in the past. Earthenware, stoneware, and porcelain from Southeast Asia have been characterized using several analytical techniques, as reviewed in this article. Fluorescent and diffracted X-rays give rise to elemental and phase compositions, respectively. Examination of molecular bonds requires vibrational spectroscopy, which is useful for the identification of organic materials in ancient potteries. With the advent of portable X-ray fluorescence and Raman spectrometry, on-site analysis of archeological ceramics is now possible. For in-depth analysis, synchrotron light sources can provide new insights into artifacts through X-ray …

Electro-Optical Effect Of 4-N-Alkyl-Sulfanyl-4' Isothiocyanate-Biphenyl Liquid Crystal Homologous Series Under Terahertz Frequency: A Theoretical Approach, Yogesh Kumar, Narinder Kumar

Makara Journal of Science

This work presented the electro-optical effect of the homologous series 4-n-alkyl-sulfanyl-4'-isothiocyanate-biphenyl (N1SC13H8-SH_2n+1C_n) under an electric field with terahertz (THz) frequency. The increase in alkyl sulfanyl chain length reduces the birefringence but increases the order parameter in THz frequency. An inverse relationship exists between the birefringence and order parameter. Meanwhile, the increase in alkyl sulfanyl chain length increases the refractive index with an even–odd effect. Birefringence, refractive index, order parameter, and director angle show an even–odd effect in the THz frequency range. The calculation is performed between 1 and 1,200 THz frequency. The isothiocyanate stretching corresponding to …

Application Of A Diatomic Molecule Model Potential To A Series Of Homo- And Heterodiatomic Molecules, Dorien E. Carpenter, Javier E. Hasbun

Georgia Journal of Science

We apply a one-dimensional classical model of a diatomic molecule model potential with modifications to H₂, HF, LiF, N₂, and CO. We obtain the unknown parameters of this model by digitizing plots of the potential curves for the molecules from a published, Hartree-Fock based theoretical electron correlation calculation (Piris 2017). We then apply the method of successive approximations to the model in order to calculate the wavenumber for each molecule in the series. The wavenumber depends on a parameter which in turn depends on the initial conditions. The value of this parameter for each individual molecule …

Size Effect On The Optical Response Of Cylindrical Palladium Nanoparticles, Salem Marhaba, Mohammed Khalaf

BAU Journal - Science and Technology

In this work, a computational study is carried out to investigate the optical response of palladium nano-cylinders. The Finite Element Method (FEM) is employed using the COMSOL MULTIPHYSICS simulation program to calculate the scattering, absorption, and extinction cross-sections. The influence of the size of the cylindrical nanoparticles on their optical properties is discussed. The results are plotted for a broad spectral range of wavelengths from ultra-violet to infra-red of the incident electromagnetic wave on the cylindrical nanoparticles.

Density Functional Theory (Dft) Study Of A Binary Mixture Of Mbba And Paa Liquid Crystal For Thz Application, Mirtunjai Mishra, Narinder Kumar, Pawan Singh, B. S. Rawat, Reena Dhyani, Devendra Singh, Devesh Kumar

Makara Journal of Science

The present scenario expresses the electro-optical effect of abinary mixture of MBBA and PAA liquid crystal studied under the impact of the electric field in THz frequency. The binary mixture has a negative order parameter, negative birefringence, and a nematic phase stability under such an electric field. The refractive index remains constant at high THz frequency. The director angle is sensitive to THz frequency, contributing to the maximum fluctuation. The atomic contribution of a binary mixture is approximately equal to the molecular contribution. The binary mixture has a remarkably high bandgap. The C-H, O-C, C-N atom stretching, and wagging of …

Localized Surface Plasmon Resonance Of Copper Nanoparticles Using Finite Element Method, Samaya El Samad, Salem Marhaba

BAU Journal - Science and Technology

The aim of this paper is to study the interaction of the electromagnetic wave with plasmonic nanoparticles. Localized Surface Plasmon resonance (LSPR) characteristics are governed by the intrinsic properties of the nanoparticle (size, shape and dielectric environment). The extinction cross-section spectra of Cu nanoparticles are calculated using finite element method (FEM). By increasing both the size of the nanoparticle and the dielectric environment, the simulations show a red-shifting and broadening on the LSPR spectrum with enhancement of the spectral amplitude. The extinction cross section spectra are calculated using polarized light for non-spherical or assembled nanoparticles. We investigated the LSPR of …

Structural And Spectroscopic Analysis For Silver Bulk And Nanoparticles, Hajir M. Fadhil, Khaleel I. Hassoon, Hyder A. Salih

Karbala International Journal of Modern Science

In this research work, a pulsed Nd-YْAG laser having a wavelength of 1064 nm and energy (400-700 mJ (has been utilized as a source in an induced breakdown spectroscopy (LIBS) experiment to determine the density of electron and the tem-perature of Ag-plasma. Two forms of silver (as a bulk and as a compressed nano powder) have been used as targets in the LIBSs setup. The aim of the present work is to study the impact of target properties and laser energy on the plasma fea-tures formed by the interaction between a pulsed laser and these two forms of silver. The …

Study Of The Geometric Structure Of Low-Atomic Copper Clusters Using Computer Simulation, Nodirbek Ikromjonovich Ibrokhimov

Scientific-technical journal

In this work, we investigated the geometric structure of small neutral copper clusters with low energy using the MD (Molecular Dynamics) method. When calculating the processes of interatomic interaction, we used a potential EAM (Embedded-atom method). A computer model of Cu_n (n = 2-13) clusters has been created. The geometric shapes of the Cu₂, Cu₃, Cu₄, Cu₅, Cu₆, Cu₇, Cu₈, Cu₉, Cu₁₀, Cu₁₁, Cu₁₂, and Cu₁₃ clusters have been studied and the structural parameters (Cu-Cu bond …

Laser-Excitation Spectroscopy Of Niobium Hydride And Tantalum Hydride, Siddhant Singh

Macalester Journal of Physics and Astronomy

The experimental results presented in this paper shed light on some of the fundamental bonding characteristics of NbH and TaH. Six bands of niobium hydride and five weak bands of tantalum hydride were observed for the first time using laser excitation spectroscopy. The rotational assignments of observed bands were confirmed using dispersed fluorescence experiments for NbH and by checking the internal consistency of a global least squares fit for the weaker bands of TaH. For TaH, we were able to determine the term energies and molecular constants of each of its observed states to a high degree of accuracy …

Determination Of The Rydberg Constant From The Emission Spectra Of H And He+, Kyle D. Shaffer

Ramifications

Abstract

In this experiment, the Rydberg constants for the hydrogen atom and He⁺ were determined by analysis of the emission spectra of Hand He, respectively, in comparison to the principal quantum numbers of each transition. Using both a hydrogen and then a helium atomic lamp attached to a 0.5 m grating spectrometer and a photomultiplier detector (PMT), a change in voltage detected by the PMT can be paired with a corresponding wavelength passing through the spectrometer from each emission peak in the visible to ultraviolet range. The peaks acquired from this change in voltage were analyzed to find their …

Dft-Based Study Of Electric Field Effect On The Polarizability Of Three Ringed Nematic Liquid Crystal Molecules, Pranav Upadhyay, Mirtunjai Mishra, Ankur Trivedi, Jitendra Kumar, Asheesh Kumar, Devesh Kumar

Makara Journal of Science

Owing to its successful application to complex molecular systems, computational density functional theory (DFT) has been used to study the effect of an electric field on the molecular polarizability and HOMO–LUMO gap of 1-phenyl-4-{2-[(1s,4r)-4-pentylcyclohexyl]ethyl}benzene (1) and its fluoro-, chloro-, and cyano- derivatives, namely, 1-fluoro-4-(4-{2-[(1s,4r)-4-pentylcyclohexyl]ethyl}phenyl)benzene (2), 1-chloro-4-(4-{2-[(1s,4r)-4-pentylcyclohexyl]ethyl}phenyl)benzene (3), and 4-(4-{2-[(1s,4r)-4-pentylcyclohexyl]ethyl}phenyl)benzonitrile (4). These molecules belong to the family of nematic liquid crystals with three rings: two benzene and one cyclohexane. Furthermore, two DFT approaches, namely, B3LYP and M062X, have been used to examine the results obtained. This study reveals a remarkable feature: the polarizability of these molecules follows nearly a step function …

Studying The Linear Complex Pt Symmetric Potential, Roland Lombard

Journal of the Arab American University مجلة الجامعة العربية الامريكية للبحوث

We investigate the spectrum of the linear complex PT symmetric potential V(x) = λ|x| + icx. Semi analytical solutions are given by using properties of the Airy functions. The numerical integration of the differential equation system is discussed. We show that the number of eigenstates with a real eigenvalue is limited, depending on the ratio c/λ and on the quantum number n, reflecting a spontaneous breaking of the PT symmetry. For the ground state ( n = 0), we conjecture the eigenvalue to be real whatever the value of c.

Self-Aggregation Of C60 Particles In A Volume Of Evaporating Droplets On A Flat Surface, Urol Makhmanov, Abdulmutallib Kokhkharov, Sagdilla Bakhramov, Donats Erts

Bulletin of National University of Uzbekistan: Mathematics and Natural Sciences

The experimental results on the self-aggregation of fullerene C₆₀ particles in a microvolume of drying droplets of a colloidal solution of fullerene on a solid substrate are presented. Using methods of scanning electron microscopy and atomic force microscopy, it was shown that in the volume of an evaporating droplet of a solution of fullerene C₆₀ in xylene, deposited on the surface of a flat silicon substrate at room temperature, nanostructured and porous mC₆₀ aggregates of quasispherical and elongated spherical shapes with geometrical sizes in average diameter up to D≈4000 nm are synthesized. It is established that an …

Intermolecular Dynamics Of Condensed State: Study Of Temperature Effect On Anisotropy Relaxation By Vibration Spectroscopy, Bakhodir Eshchanov, Shavkat Otajonov, Jurat Gayipov, Dilafruz Xudoyberdiyeva, Sarvarbek Qurbanbayev

Bulletin of National University of Uzbekistan: Mathematics and Natural Sciences

As a result of the experimental study of the spectra of anisotropic scattering of light, a character of orientation movement of molecules in aromatic hydrocarbons has been analyzed. The obtained results have been interpreted from the viewpoint of a model of inhibited rotation and the contributions of the rotational and vibrational degrees of freedom to a molecule spectrum have been estimated. With increasing temperature of liquids under study and approaching a critical state, the rotational degrees of freedom "freeze", and the vibrational degrees have become more significant.

Quantum Interference In Monocyclic Molecules: A Novel And Straightforward Phase Wave Model, Zainelabideen Yousif Mijbil

Karbala International Journal of Modern Science

We have proposed by far the simplest model, so-called phase wave model (PWM), to predict quantum interference states in monocyclic molecules. Meanwhile, transmission coefficient calculations were also performed using Green’s function method incorporated with Hückel (Tight Binding) approximation. An impressive agreement has been obtained between the results of the phase wave model and the ones from transmission coefficient calculations for the chosen model systems, namely benzene, cycloheptatriene, cyclooctatetraene, and [10]annulene. PWM represents the phase of wave functions of the incoming electrons by a wave and associates a single wavelength of the phase with five atoms/sites. Hence, the electrical conductance would …

Guidelines For Studying The Dynamics Of Nanostructural Phenomena In Liquids By Dynamic Light Scattering., Shavkat Esirgapovich Qarshiboyev, Lionard Sabirov, Leonid Chaikov, Marina Kirichenko

Scientific Journal of Samarkand University

The paper describes the principles of correlation spectroscopy of scattered light and a method for determining the size of particles suspended in a liquid using such spectroscopy - the method of dynamic light scattering (DLS). Some features of the application of the DLS method are considered.

Structuring Light For Investigating Optical Vortices, Andrew Voitiv, Mark Siemens

DU Undergraduate Research Journal Archive

Vortices are well known in our world: tornadoes, hurricanes, and quickly stirred iced tea all demonstrate the vortex phenomenon. In addition to these classical fluids, vortices exist in laser light. While classical fluid vortex dynamics is one of the oldest studied physics problems, the study of optical vortices is only a few decades old. Paralleling the community’s curiosity of quantized vortices in quantum fluids, such as super fluid helium and Bose-Einstein condensate, there is immense interest in the study of optical vortices. In this article, we cover the basic theory of structuring light to generate optical vortices and then discuss …

Structure, Stability And Vibrational Properties Of Cdse Wurtzite Molecules And Nanocrystals: A Dft Study, Mudar A. Abdulsattar, Hayder M. Abduljalil, Hussein Hakim Abed

Karbala International Journal of Modern Science

Bare and hydrogen passivated CdSe wurtzite molecules and nanostructures are investigated. The investigation is performed using wurtzoid structures that represent the wurtzite structure at the molecular and nanoscale region. The results show that the energy gap of bare and hydrogen passivated CdSe molecules is higher than and converges to the experimental bulk energy gap. Vibrational analysis of wurtzoid molecules shows that the experimental longitudinal optical mode is in between bare and hydrogen passivated CdSe molecules and very near to bare molecules. The stability of wurtzoid molecules against transition to CdSe diamondoids and cuboids that represent the molecular scale of diamond …

A Brief Review Of Modern Uses Of Scattering Techniques, Daniel M. Wade, Dereth J. Drake

Georgia Journal of Science

Thomson, Rayleigh, Mie, and Raman scattering are commonly used in several disciplines in science and engineering. The techniques involve the scattering of electromagnetic radiation or particles in a sample. This paper provides a brief history for each scattering method, describes the traditional laboratory approach for implementation, and discusses current uses and variations of these four techniques.

Measurement Of Solar Spectral Irradiance And Surface Ozone At Carrollton, Georgia, Usa, During The Great American Eclipse On 21 August 2017, Kirthi Tennakone, L Ajith Desilva, Charles A. Zander*, Shea Rose, Austin B. Kerlin

Georgia Journal of Science

Measurements conducted at the University of West Georgia, Carrollton, Georgia, during the time of the solar eclipse of 21^st August 2017 demonstrated that the integrated spectral irradiance in defined wavelength ranges in the ultraviolet and visible calculated as a fraction of the total irradiance reached a minimum at maximum obscuration of the Sun, whereas in an infrared range it was maximum. The method of analysis adopted supports the view that the changes in spectral irradiance during highly obscured partial phases is a consequence of limb darkening. In a surface ozone measurement, a minimum in ozone concentration occurred 30 +_ …

Comparison Of Various Mean Field Formulations For Retrieving Refractive Indices Of Aerosol Particles Containing Inclusions, Kristin S. Dooley, Jessica Deyoung

Journal of the Arkansas Academy of Science

Application of effective medium approximation (EMA) methods to two-component systems are presented. Systems studied are composed of water, sulfate, soot, and dust as these are commonly encountered atmospheric aerosol components. Atmospheric models often employ EMAs to include internally mixed aerosols without the computational burden of exact theory. In the current work, several types of mixing rules (Maxwell-Garnet, Bruggeman, and coherent potential approximation) have been applied to various two-component internally mixed particles at 550 nm using volume fractions of the minor component below 0.1. As expected, results show that the formulations tested produce very similar effective refractive indices indicating that electric …

Time-Resolved Thz Conductivity Of An Intermediate Band Semiconductor, Elliot Weiss

Macalester Journal of Physics and Astronomy

Intermediate band materials have promising applications as affordable, highly efficient solar materials. However, intermediate band solar cells exhibit low efficiency to date. Carrier recombination is a critical process that limits efficiency. If electrons relax to the valence band before they can be collected, their energy is lost. To help understand the recombination dynamics and physical properties of intermediate band semiconductors, we obtain time-resolved THz conductivity measurements of the intermediate band semiconductor, GaPAsN, at various temperatures. From our results, we build a model that provides insight to the recombination dynamics of GaPAsN.

Intervalley Scattering Rates In Tellurium Observed Via Time-Resolved Terahertz Spectroscopy, Joshua R. Rollag

Macalester Journal of Physics and Astronomy

We conducted time-resolved terahertz spectroscopy measurements on the elemental semiconductor tellurium. Pump-probe measurements were used to find the conductivity as a function of time in single crystalline tellurium samples. It was found that the excitation dynamics in tellurium changes for photon energies of 1.03 eV and 1.55 eV. The change in these excitation dynamics was attributed to intervalley scattering effects. A model using intervalley scattering and Auger recombination was fit to the data, giving a value of 2.28 ps for the intervalley scattering time constant in tellurium.

Conductivity Measurements Of A Thermoelectric Nanomaterial Through Thz Spectroscopy, Michaela S. Koller, James Heyman, Gunnar Footh

Macalester Journal of Physics and Astronomy

In today’s society there is a great demand on energy output—in the United States alone we rely heavily on non-renewable energy sources. Thermoelectric materials may be able to be used to create more efficient energy systems or recover wasted heat from inefficient technologies. This paper focuses on the conductivity of a new thermoelectric material that incorporates copper into a tellurium nanowire PEDOT:PSS material. The addition of copper seems to increase the conductivity of the material, although the exact relationship between the percentage of copper to tellurium and its affect on the conductivity is uncertain from the results.

Model For The Electrolysis Of Water And Its Use For Optimization, Roger Lascorz, Javier E. Hasbun Dr

Georgia Journal of Science

The goal of this research was to study the optimization of the electrolysis of water both theoretically and experimentally. For accuracy, 3 hr experiments were made with measurements recorded every 15 min. The results show that a better model than the classical one is needed for water electrolysis. A new model that fits experimental data better is proposed. The results of this new model not only predict hydrogen production in electrolysis of water better, but show a way to predict gas production of any liquid as well as what voltage to use to optimize it.

Dissociative Excitation Of H2 In An Rf Plasma, John Carlson

Macalester Journal of Physics and Astronomy

Plasma-enhanced chemical vapor deposition is a widely used method for depositing thin films. In order to optimize the properties of the films, it is important to understand the plasma processes that occur during film growth. In this research we use optical emission spectroscopy in order to measure the spectral emission lines of a plasma produced with hydrogen gas. In conjunction with other measurements and modeling, these measurements can provide insight to the electron energy distribution of the plasma.

Characterizing Nanoparticle Size By Dynamic Light Scattering, M. Zaman, S. Ang, S. Singh

Journal of the Arkansas Academy of Science

The Dynamic Light Scattering (DLS) Technique was used to determine the size, shape and diffusion coefficient of rod-like nanoparticles. The intensity auto-correlation functions of light scattered by particles in a solution were measured and analyzed to obtain the relaxation rates for decay of intensity correlations. These decay rates are related to the diffusion coefficients pertaining to the motion of the particle. In the case of nanorods, there are two types of motion - translational and rotational. By disentangling the relaxation rates, corresponding to these two types of motion, the shape and size of nanoparticles were characterized. These experiments, though limited …

Modelling Transient Terahertz Magneto-Spectroscopy Measurements Of P-Type Cvd Graphene Leading To A Negative Photoconductivity., Rhyan Foo Kune

Macalester Journal of Physics and Astronomy

Ultrafast Terahertz (THz) Magneto-Spectroscopy (UTMS) measurements were performed on p-type CVD graphene sample to investigate the intrinsic carrier dynamics of the material. We investigated static and time-resolved THz transmission measurements, in which the sample was photo-excited by a near infrared (NIR) pump pulse, in order to study its behavior in a magnetic field. In these measurements the free carriers were probed to independently measure the carrier density and scattering rate in this film. We observed, in our graphene sample, an increase in transmission related to a negative photoconductivity (decrease in conductivity after photoexcitation) consistent with previous research. This decrease is …