Physics Commons^™

Computer Simulation Of Adsorption Of C60 Fullerene Molecule On Reconstructed Defective Si(100) Surfacee Content Of The Body Element Is Displayed In Your Browser, I. Urolov, Ishmumin Yadgarov, Ganiboy Raxmanov

Bulletin of National University of Uzbekistan: Mathematics and Natural Sciences

In this work, based on the molecular dynamics (MD) method, the adsorption processes of C₆₀ fullerene molecules on the reconstructed defective silicon Si(100) surface with different configurations were simulated in the LAMMPS open package program. Second-order Brenner interatomic potential was used to determine interactions between Si-Si, C-C and Si-C atoms. The interaction of various shaped defect areas with the C₆₀ molecule on the surface of reconstructed silicon Si(100) was studied. As a result of calculations, stable adsorption states were determined by comparing the energy of C₆₀ molecule adsorption to the defective silicon Si(100) surface and the Si-C …

Triply Differential Positron And Electron Impact Ionization Of Argon: Systematic Features And Scaling, Robert D. Dubois, O. G. De Lucio

Physics Faculty Research & Creative Works

Triply differential data are presented for the 200 eV positron and electron impact ionization of argon. Six electron emission energies between 2.6 and 19 eV, and for scattering angles of 2, 3, and 4 degrees cover a momentum transfer range of 0.16 to 0.31 a.u. The binary and recoil intensities are fitted using a double peak structure in both regions, which, for the present kinematic conditions, are unresolved. The fitted peak intensities and angular positions are shown to have systematic dependences as a function of the momentum transfer and kinematic emission angle, respectively, and illustrate projectile charge effects. A comparison …

A New Type Of Current Instability In Silicon With Nanoclusters Of Manganese Atoms, M. K. Bakhadirkhanov, S. B. Isamov, K. A. Ismayilov, X. U. Kamalov

Karakalpak Scientific Journal

The current instabilities in silicon with nanoclusters of manganese atoms in accordance with the excitation conditions and the control possibilities for the oscillation parameters discovered by us differ substantially from the current instability found in many other semiconductor materials [1-3]. This is due to the onset of generation of current instability only under illumination by certain wavelengths under the condition of a sufficiently low IR light intensity, as well as a pronounced dependence of the current frequency frequency on the energy of the incident photons. It should be noted that such instabilities of current are observed only in silicon samples …

Computational Techniques For Scattering Amplitudes, Juliano A. Everett

Publications and Research

Scattering amplitudes in quantum field theory can be described as the probability of a scattering process to happen within a high energy particle interaction, as well as a bridge between experimental measurements and the prediction of the theory.

In this research project, we explore the Standard Model of Particle Theory, it’s representation in terms of Feynman diagrams and the algebraic formulas associated with each combination.

Using the FeynArts program as a tool for generating Feynman diagrams, we evaluate the expressions of a set of physical processes, and explain why these techniques become necessary to achieve this goal.

Laser Spectroscopy Of Ultra-Small Concentration Of Atoms And Aerosols In Various Phase States Of Substance, А.Т. Xalmanov

Scientific Journal of Samarkand University

In this work it is given studying of dynamics and types of physical processes with excited atoms and molecules in atomizer of "graphite furnace". Physical mechanism of increasing atomic-ionization signal for two stepwise excitation schemes was shown. It is shown that the maximum signal is observed for In atoms at the transition 5p 2 Р3/2→6s 2 S3/2→8p 2 P1/2 and for Li, Na, Ag, Au, Pt atoms at the transition (n)s→(m)p→(k)d respectively (where n, k, m and f principal quantum numbers of states). In the result in the experiment photoionization collisional ionization and mechanisms were developed. The results are show …

Problem Set #7, David Peak

Problems

Atom stuff

Resonant Collisions Of Potassium Atoms, Philip Michael Adamson

Honors Theses

This thesis discusses an approach to excite potassium atoms to very highly excited states (Rydberg states), and then tune their energy levels to induce resonant collisions between atoms. Potassium gas is super-cooled to 1 mK and confined to a small volume in a magneto-optical trap. A 405 nm laser diode, electronically locked to a potassium vapor cell via Doppler free spectroscopy, excites these atoms from the 4s_1/2 state (ground state) to the 5p_3/2 state. A 978 nm laser then excites the 5p_3/2 to nd_3/2 or nd_5/2 transition, creating Rydberg atoms. Since there is no ground …

Unmasking The Mysteries Of High-Mass X-Ray Binaries (Hmxbs): The Role Of The Electron Beam Ion Trap (Ebit), Carey L. Baxter, Greg Brown, Natalie Hell

Carey L Baxter

The Electron Beam Ion Trap (EBIT) uses a very narrow electron beam (~60μm) to excite and trap ions. X-ray emissions of the excited ions are then diffracted and analyzed. I studied specific spectral emission lines of ionized silicon. This data can be used as a point of reference for similar spectra measured by the satellite Chandra so that the Doppler shift due to wind around the accretion disks of High Mass X-ray Binaries (HMXBs) can be calculated. HMXBs are pairs of stars that are luminous in X-rays. They are composed of a donor star that gives up mass to an …

Techniques To Characterize Vapor Cell Performance For A Nuclear-Magnetic-Resonance Gyroscope, James Julian Mirijanian

Master's Theses

Research was performed to improve the procedures for testing performance parameters of vapor cells for a nuclear-magnetic-resonance gyroscope. In addition to summarizing the theoretical infrastructure of the technology, this research resulted in the development and successful implementation of new techniques to characterize gyro cell performance.

One of the most important parameters to measure for gyro performance is the longitudinal spin lifetime of polarized xenon atoms in the vapor cell. The newly implemented technique for measuring these lifetimes matches results from the industry standard method to within 3.5% error while reducing the average testing time by 76% and increasing data resolution …

Quantum Engineering Of Laser-Cooled Atoms: Experiments And Theory, Kieran Deasy

Theses

In this thesis, laser cooling and trapping techniques are implemented to forrn a cold atom cloud of 85Rb atoms in a magneto-optical trap (Mon configuration. The system produces an atom cloud of~ 1.5 mm in diameter, containing ~ 108 atoms and an average temperature in the sub-Doppler range. Tapered optical fibres (TOFs) are also detailed here, including their guiding properties and the process used for their fabrication. Many possible applications for TOFs have been proposed and one such application is investigated, i.e. the use of TOFs as highly sensitive atom probes. The research results contained within this thesis describe two …

Constructing A Magneto-Optical Trap For Cold Atom Trapping, Eric S. Muckley

Physics

A magneto-optical trap, or MOT, is a device that traps atoms between three pairs of opposing perpendicular laser beams for cooling the atoms to temperatures near absolute zero. The MOT uses Doppler cooling and a magnetic quadrupole field to trap the atoms; in our case, Rb87 atoms. In the future, the MOT will be used in experiments pertaining to the advancement of quantum computing. In this paper, I explain some of the processes required for construction and operation of the MOT.

Bound States In The Continuum In Quantum-Dot Pairs, Gonzalo Ordonez, Kyungsun Na, Sungyun Kim

Scholarship and Professional Work - LAS

It is shown that for two open quantum dots connected by a wire, “bound states in the continuum” of a single electron are formed at nearly periodic distances between the dots. This is due to Fabry-Pérot interference between quasibound states in each dot. The bound states are nonlocal, describing the electron trapped in both dots at the same time. Theoretical and numerical results show that trapped states exist even if the wire connecting the dots is relatively long.

Surface Core-Level Shifts Of Ta(110) And W(110) Vs. Alkali-Atom Coverage: Implications For Thealkali-Substrate Interaction, A. B. Andrews, D. Mark Riffe, G. K. Wertheim

All Physics Faculty Publications

The change in the average surface-atom core-level shift (SCS) produced by submonolayer coverages of alkali adsorbates is quite small for both Ta(110) and W(110), less than 45 meV in magnitude. The small change of the measured SCS’s as a function of coverage decisively supports the covalent-bonding picture of alkali adsorption proposed by Ishida and Terakura.