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(2,2-Bipyridyl)bis(eta5-1,2,3,4,5-pentamethylcyclopentadienyl)Strontium(II)

Description: In the title compound, the Sr-N distances are 2.624 (3) and 2.676 (3) Angstroms. The Sr-centroid distances are 2.571 and 2.561 Angstroms. The N-C-C-N torsion angle in the bipyridine ligand is 2.2 (4){sup o}. Interestingly, the bipyridine ligand is tilted. The angle between the plane defined by Sr1, N1 and N2 and the plane defined by the 12 atoms of the bipyridine ligand is 10.7{sup o}.
Date: July 3, 2008
Creator: Kazhdan, Daniel; Kazhdan, Daniel; Hu, Yung-Jin; Kokai, Akos; Levi, Zerubba & Rozenel, Sergio
Partner: UNT Libraries Government Documents Department

Photofragment Coincidence Imaging of Small I- (H2O)n Clusters Excited to the Charge-transfer-to-solvent State

Description: The photodissociation dynamics of small I{sup -}(H{sub 2}O){sub n} (n = 2-5) clusters excited to their charge-transfer-to-solvent (CTTS) states have been studied using photofragment coincidence imaging. Upon excitation to the CTTS state, two photodissociation channels were observed. The major channel ({approx}90%) is a 2-body process forming neutral I + (H{sub 2}O){sub n} photofragments, and the minor channel is a 3-body process forming I + (H{sub 2}O){sub n-1} + H{sub 2}O fragments. Both process display translational energy (P(E{sub T})) distributions peaking at E{sub T} = 0 with little available energy partitioned into translation. Clusters excited to the detachment continuum rather than to the CTTS state display the same two channels with similar P(E{sub T}) distributions. The observation of similar P(E{sub T}) distributions from the two sets of experiments suggests that in the CTTS experiments, I atom loss occurs after autodetachment of the excited (I(H{sub 2}O){sub n}{sup -})* cluster, or, less probably, that the presence of the excess electron has little effect on the departing I atom.
Date: November 9, 2005
Creator: Neumark, D. E. Szpunar, K. E. Kautzman, A. E. Faulhaber, and D. M.; Kautzman, K.E.; Faulhaber, A.E. & Faulhaber, A.E.
Partner: UNT Libraries Government Documents Department

Biocompatible Graphene-based Growth of Cancer Cells: A Work in Progress

Description: Poster presentation for the 2012 University Scholars Day at the University of North Texas. This poster discusses research on the biocompatible graphene-based growth of cancer cells. Graphene is made of a single layer of carbon atoms. Recently is has been used to successfully differentiate stem cells in neural cells.
Date: April 19, 2012
Creator: Parks, Melissa & Verrill, Diane
Partner: UNT Honors College

Nuclear parameters from muonic and pionic x rays

Description: In view of the higher precision of the experimental data in measurements of the energies and relative intensities of the muonic and pionic x-ray transitions, the validity of the approximations made in extracting nuclear spectroscopic values from the raw data must be scrutinized more carefully if the reliability of the extracted parameters are to approach the accuracy of the experimental data. (GHT)
Date: January 1, 1980
Creator: Steffen, R M
Partner: UNT Libraries Government Documents Department

Atomic Scale coexistence of Periodic and quasiperiodic order in a2-fold A1-Ni-Co decagonal quasicrystal surface

Description: Decagonal quasicrystals are made of pairs of atomic planes with pentagonal symmetry periodically stacked along a 10-fold axis. We have investigated the atomic structure of the 2-fold surface of a decagonal Al-Ni-Co quasicrystal using scanning tunneling microscopy (STM). The surface consists of terraces separated by steps of heights 1.9, 4.7, 7.8, and 12.6{angstrom} containing rows of atoms parallel to the 10-fold direction with an internal periodicity of 4{angstrom}. The rows are arranged aperiodically, with separations that follow a Fibonacci sequence and inflation symmetry. The results indicate that the surfaces are preferentially Al-terminated and in general agreement with bulk models.
Date: November 14, 2005
Creator: Park, Jeong Young; Ogletree, D. Frank; Salmeron, Miquel; Ribeiro,R.A.; Canfield, P.C.; Jenks, C.J. et al.
Partner: UNT Libraries Government Documents Department

A divide-and-conquer linear scaling three dimensional fragment method for large scale electronic structure calculations

Description: We present a new linear scaling ab initio total energy electronic structure calculation method based on the divide-and-conquer strategy. This method is simple to implement, easily to parallelize, and produces very accurate results when compared with the direct ab initio method. The method has been tested using up to 8,000 processors, and has been used to calculate nanosystems up to 15,000 atoms.
Date: July 11, 2008
Creator: Wang, Lin-Wang; Zhao, Zhengji; Meza, Juan & Wang, Lin-Wang
Partner: UNT Libraries Government Documents Department

Molecular Dimensions

Description: This study attempts to calculate the areas of the cross section and diameter of the CH3 group, COOH group, the length of the carbon chain, and the longtiudinal distance between carbon atoms for each of the three acids. It also attempts to develop a method of measuring the effective diameter of molecules of gases. Equations for these terms as given by MacDougall and experiments were performed and the data applied to the equation.
Date: August 1938
Creator: Moss, H. H.
Partner: UNT Libraries

First principle thousand atom quantum dot calculations

Description: A charge patching method and an idealized surface passivation are used to calculate the single electronic states of IV-IV, III-V, II-VI semiconductor quantum dots up to a thousand atoms. This approach scales linearly and has a 1000 fold speed-up compared to direct first principle methods with a cost of eigen energy error of about 20 meV. The calculated quantum dot band gaps are parametrized for future references.
Date: March 30, 2004
Creator: Wang, Lin-Wang & Li, Jingbo
Partner: UNT Libraries Government Documents Department

Exotic atoms and leptonic conservations

Description: The major 1989 efforts have been on two aspects of experiments at TRIUMF. One effort was production of muonic hydrogen and muonic deuterium into a vacuum. We study rates relevant to muonic catalyzed fusion, and if there are found an adequate number of muons in the 2s state then we plan to measure precision energies. The second effort was to develop plans for kaonic atoms at the kaon factory. We also completed analyses from the experiments with pionic atoms at LAMPF.
Date: January 1, 1990
Creator: Kunselman, R.
Partner: UNT Libraries Government Documents Department

Exploiting Universality in Atoms with Large Scattering Lengths

Description: The focus of this research project was atoms with scattering lengths that are large compared to the range of their interactions and which therefore exhibit universal behavior at sufficiently low energies. Recent dramatic advances in cooling atoms and in manipulating their scattering lengths have made this phenomenon of practical importance for controlling ultracold atoms and molecules. This research project was aimed at developing a systematically improvable method for calculating few-body observables for atoms with large scattering lengths starting from the universal results as a first approximation. Significant progress towards this goal was made during the five years of the project.
Date: May 31, 2012
Creator: Braaten, Eric
Partner: UNT Libraries Government Documents Department

Dynamic Stark effect and forbidden-transition spectrallineshapes

Description: We report on an experimental and theoretical study of thedynamic (ac) Stark effect on a for bidden transition. A general frameworkfor parameterizing and describing off-resonant ac-Stark shifts ispresented. A model is developed to calculate spectral line shapesresulting from resonant excitation of atoms in an intense standinglight-wave in the presence of off-resonant ac-Stark shifts. The model isused in the analysis and interpretation of a measurement of the ac-Starkshifts of the static-electric-field-induced 6s2 1S0 -->5d6s 3D1transition at 408 nm in atomic Yb. The results are in agreement withestimates of the ac-Stark shift of the transition under the assumptionthat the shift is dominated by that of the 6s2 1S0 ground state. Adetailed description of the experiment and analysis is presented. Abi-product of this work is an ind ependent determination (from thesaturation behavior of the 408-nm transition) of the Stark transitionpolarizability, which is found to be in agreement with our earliermeasurement. This work is part of the ongoing effort aimed at a precisionmeasurement of atomic parity-violation effects in Yb.
Date: December 15, 2005
Creator: Stalnaker, Jason E.; Budker, D.; Freedman, S.J.; Guzman, J.S.; Rochester, S.M. & Yashchuk, V.V.
Partner: UNT Libraries Government Documents Department

Nuclear physics with stopping kaon beams

Description: The present status of thc study of hadronic atoms using stopping kaon beams is reviewed. The kaonic atom system is chiefly discussed. Kaon - nucleus interactions from x rays, nuclear gamma rays, and electromagnetic interactions are covered. (JFP)
Date: July 1, 1973
Creator: Barnes, P. D.
Partner: UNT Libraries Government Documents Department

A POSSIBLE PHASE TRANSITION IN LIQUID He3

Description: A possible phase transition in liquid He{sup 3} has been investigated theoretically by generalizing the Bardeen, Cooper, and Schrieffer equations for the transition temperature in the manner suggested by Cooper, Mills, and Sessler. The equations are transformed into a form suitable for numerical solution and an expression is given for the transition temperature at which liquid He{sup 3} will change to highly correlated phase. Following a suggestion of Hottelson, it is shown that the phase transition is a consequence of the interaction of particles in relative D-states. The predicted value of the transition temperature depends on the assumed form of the effective single-particle potential and the interaction between He{sup 3} atoms. The most important aspects of the single-particle potential are related to the thermodynamic properties of the liquid just above the transition temperature. Two choices of the two-particle interaction, oonstituent with experiments, yield a second-order transition at a temperature between approximately 0.01 K and 0.1 K. The highly correlated phase should exhibit enhanced fluidity.
Date: January 29, 1960
Creator: Emery, V.J. & Sessler, A.M.
Partner: UNT Libraries Government Documents Department

CORRELATION EFFECTS IN MANY FERMION SYSTEMS: MULTIPLE PARTICLE EXCITATION EXPANSION

Description: The ground-state wave function and energy of a finite system of interacting fermions are expanded in terms of multiple-particle excitations on an uncorrelated zero-order state. The resulting set of coupled equations constitutes a systematic variational generalization of Hartree-Fock theory. Comparison is made with many-body perturbation theory and it is shown that to any order the theory incorporates an infinite number of perturbation theory terms. Solutions of the equations for ground-state atomic systems are discussed and related to previous work using many-body perturbation theory. It is shown that the sums of perturbation terms necessary for convergence are automatically included in the equations for two-particle excitations. Application of the equations to open-shell atoms is described.
Date: July 1, 1963
Creator: Kelly, Hugh P. & Sessler, Andrew M.
Partner: UNT Libraries Government Documents Department