WorldWideScience

Sample records for pseudograph alpha-carbon atom

  1. Protein linear indices of the 'macromolecular pseudograph alpha-carbon atom adjacency matrix' in bioinformatics. Part 1: prediction of protein stability effects of a complete set of alanine substitutions in Arc repressor.

    Science.gov (United States)

    Marrero-Ponce, Yovani; Medina-Marrero, Ricardo; Castillo-Garit, Juan A; Romero-Zaldivar, Vicente; Torrens, Francisco; Castro, Eduardo A

    2005-04-15

    A novel approach to bio-macromolecular design from a linear algebra point of view is introduced. A protein's total (whole protein) and local (one or more amino acid) linear indices are a new set of bio-macromolecular descriptors of relevance to protein QSAR/QSPR studies. These amino-acid level biochemical descriptors are based on the calculation of linear maps on Rn[f k(xmi):Rn-->Rn] in canonical basis. These bio-macromolecular indices are calculated from the kth power of the macromolecular pseudograph alpha-carbon atom adjacency matrix. Total linear indices are linear functional on Rn. That is, the kth total linear indices are linear maps from Rn to the scalar R[f k(xm):Rn-->R]. Thus, the kth total linear indices are calculated by summing the amino-acid linear indices of all amino acids in the protein molecule. A study of the protein stability effects for a complete set of alanine substitutions in the Arc repressor illustrates this approach. A quantitative model that discriminates near wild-type stability alanine mutants from the reduced-stability ones in a training series was obtained. This model permitted the correct classification of 97.56% (40/41) and 91.67% (11/12) of proteins in the training and test set, respectively. It shows a high Matthews correlation coefficient (MCC=0.952) for the training set and an MCC=0.837 for the external prediction set. Additionally, canonical regression analysis corroborated the statistical quality of the classification model (Rcanc=0.824). This analysis was also used to compute biological stability canonical scores for each Arc alanine mutant. On the other hand, the linear piecewise regression model compared favorably with respect to the linear regression one on predicting the melting temperature (tm) of the Arc alanine mutants. The linear model explains almost 81% of the variance of the experimental tm (R=0.90 and s=4.29) and the LOO press statistics evidenced its predictive ability (q2=0.72 and scv=4.79). Moreover, the

  2. Structure and Reactivity of the Glutathione Radical Cation: Radical Rearrangement from the Cysteine Sulfur to the Glutamic Acid alpha-Carbon Atom

    NARCIS (Netherlands)

    Osburn, S.; Berden, G.; Oomens, J.; Gulyuz, K.; Polfer, N.C.; O'Hair, R.A.J.; Ryzhov, V.

    2013-01-01

    A gas-phase radical rearrangement through intramolecular hydrogen-atom transfer (HAT) was studied in the glutathione radical cation, [-ECG](+.), which was generated by a homolytic cleavage of the protonated S-nitrosoglutathione. Ion-molecule reactions suggested that the radical migrates from the

  3. Atomic polarizabilities

    Energy Technology Data Exchange (ETDEWEB)

    Safronova, M. S. [Department of Physics and Astronomy, University of Delaware, Newark, DE 19716 (United States); Mitroy, J. [School of Engineering, Charles Darwin University, Darwin NT 0909 (Australia); Clark, Charles W. [Joint Quantum Institute, National Institute of Standards and Technology and the University of Maryland, Gaithersburg, Maryland 20899-8410 (United States); Kozlov, M. G. [Petersburg Nuclear Physics Institute, Gatchina 188300 (Russian Federation)

    2015-01-22

    The atomic dipole polarizability governs the first-order response of an atom to an applied electric field. Atomic polarization phenomena impinge upon a number of areas and processes in physics and have been the subject of considerable interest and heightened importance in recent years. In this paper, we will summarize some of the recent applications of atomic polarizability studies. A summary of results for polarizabilities of noble gases, monovalent, and divalent atoms is given. The development of the CI+all-order method that combines configuration interaction and linearized coupled-cluster approaches is discussed.

  4. Atomic Physics

    CERN Document Server

    Foot, Christopher J

    2007-01-01

    This text will thoroughly update the existing literature on atomic physics. Intended to accompany an advanced undergraduate course in atomic physics, the book will lead the students up to the latest advances and the applications to Bose-Einstein Condensation of atoms, matter-wave inter-ferometry and quantum computing with trapped ions. The elementary atomic physics covered in the early chapters should be accessible to undergraduates when they are first introduced to the subject. To complement. the usual quantum mechanical treatment of atomic structure the book strongly emphasizes the experimen

  5. Ultracold atoms on atom chips

    DEFF Research Database (Denmark)

    Krüger, Peter; Hofferberth, S.; Haller, E.

    2005-01-01

    Miniaturized potentials near the surface of atom chips can be used as flexible and versatile tools for the manipulation of ultracold atoms on a microscale. The full scope of possibilities is only accessible if atom-surface distances can be reduced to microns. We discuss experiments in this regime...

  6. Atomic physics

    CERN Document Server

    Born, Max

    1969-01-01

    The Nobel Laureate's brilliant exposition of the kinetic theory of gases, elementary particles, the nuclear atom, wave-corpuscles, atomic structure and spectral lines, electron spin and Pauli's principle, quantum statistics, molecular structure and nuclear physics. Over 40 appendices, a bibliography, numerous figures and graphs.

  7. Early Atomism

    Indian Academy of Sciences (India)

    http://www.ias.ac.in/article/fulltext/reso/015/10/0905-0925. Keywords. Atomic theory; Avogadro's hypothesis; atomic weights; periodic table; valence; molecular weights; molecular formula; isomerism. Author Affiliations. S Ramasesha1. Solid State and Structural Chemistry Unit, Indian Institute of Science, Bangalore 560 012, ...

  8. The abuse potential of two novel synthetic cathinones with modification on the alpha-carbon position, 2-cyclohexyl-2-(methylamino)-1-phenylethanone (MACHP) and 2-(methylamino)-1-phenyloctan-1-one (MAOP), and their effects on dopaminergic activity.

    Science.gov (United States)

    Botanas, Chrislean Jun; Yoon, Seong Shoon; de la Peña, June Bryan; Dela Peña, Irene Joy; Kim, Mikyung; Woo, Taeseon; Seo, Joung-Wook; Jang, Choon-Gon; Park, Kyung-Tae; Lee, Young Hun; Lee, Yong Sup; Kim, Hee Jin; Cheong, Jae Hoon

    2017-02-01

    The recreational use of synthetic cathinones has dramatically increased in recent years, which is partly due to easy accessibility and ability of synthetic cathinones to exert rewarding effects similar to cocaine and methamphetamine. Many synthetic cathinones have already been scheduled in several countries; however, novel and diverse synthetic cathinones are emerging at an unprecedented rate, often outpacing regulatory processes. Recently, designer modifications of the basic cathinone molecule are usually performed on the alpha-carbon position. In this study, we designed and synthesized two novel synthetic cathinones with substituents on alpha-carbon position, [1] 2-cyclohexyl-2-(methylamino)-1-phenylethanone (MACHP), and [2] 2-(methylamino)-1-phenyloctan-1-one (MAOP). Then, we evaluated their rewarding and reinforcing effects through the conditioned place preference (CPP) in mice and self-administration (SA) test in rats. Locomotor activity was also assessed in mice during daily MACHP or MAOP treatment for 7days and drug challenge. qRT-PCR analyses were conducted to determine their effects on dopamine-related genes in the striatum. MACHP and MAOP produced CPP at 10 and 30mg/kg. In the SA test, MACHP (1mg/kg/infusion), but not MAOP, was self-administered. Both MACHP and MAOP induced locomotor sensitization in mice. qRT-PCR analyses showed that MACHP and MAOP reduced dopamine transporter gene expression in the striatum. These data indicate that MACHP and MAOP may have rewarding properties, which might be attributed to their ability to affect the dopaminergic activity. These findings may be useful in predicting the abuse potential and hasten the regulation of future cathinone entities with similar modifications. Copyright © 2017 Elsevier Inc. All rights reserved.

  9. Atomic theories

    CERN Document Server

    Loring, FH

    2014-01-01

    Summarising the most novel facts and theories which were coming into prominence at the time, particularly those which had not yet been incorporated into standard textbooks, this important work was first published in 1921. The subjects treated cover a wide range of research that was being conducted into the atom, and include Quantum Theory, the Bohr Theory, the Sommerfield extension of Bohr's work, the Octet Theory and Isotopes, as well as Ionisation Potentials and Solar Phenomena. Because much of the material of Atomic Theories lies on the boundary between experimentally verified fact and spec

  10. Atomic Power

    African Journals Online (AJOL)

    Atomic Power. By Denis Taylor: Dr. Taylor was formerly Chief UNESCO Advisor at the University. College, Nairobi, Kenya and is now Professor of Electrical Engineering in the Uni- versity of ... method of producing radioactive isotopes, which are materials .... the sealing and the pressure balancing, all can be carried out ...

  11. Atomic arias

    Science.gov (United States)

    Crease, Robert P.

    2009-01-01

    The American composer John Adams uses opera to dramatize controversial current events. His 1987 work Nixon in China was about the landmark meeting in 1972 between US President Richard Nixon and Chairman Mao Zedong of China; The Death of Klinghoffer (1991) was a musical re-enactment of an incident in 1985 when Palestinian terrorists kidnapped and murdered a wheelchair-bound Jewish tourist on a cruise ship. Adams's latest opera, Doctor Atomic, is also tied to a controversial event: the first atomic-bomb test in Alamogordo, New Mexico, on 16 June 1945. The opera premièred in San Francisco in 2005, had a highly publicized debut at the Metropolitan Opera in New York in 2008, and will have another debut on 25 February - with essentially the same cast - at the English National Opera in London.

  12. Atomic rivals

    Energy Technology Data Exchange (ETDEWEB)

    Goldschmidt, B.

    1990-01-01

    This book is a memoir of rivalries among the Allies over the bomb, by a participant and observer. Nuclear proliferation began in the uneasy wartime collaboration of the United States, England, Canada, and Free France to produce the atom bomb. Through the changes of history, a young French chemist had a role in almost every act of this international drama. This memoir is based on Goldschmidt's own recollections, interviews with other leading figures, and 3,000 pages of newly declassified documents in Allied archives. From his own start as Marie Curie's lab assistant, Goldschmidt's career was closely intertwined with Frances complicated rise to membership in the nuclear club. As a refugee from the Nazis, he became part of the wartime nuclear energy project in Canada and found himself the only French scientist to work (although briefly) on the American atom bomb project.

  13. Atom Skimmers and Atom Lasers Utilizing Them

    Science.gov (United States)

    Hulet, Randall; Tollett, Jeff; Franke, Kurt; Moss, Steve; Sackett, Charles; Gerton, Jordan; Ghaffari, Bita; McAlexander, W.; Strecker, K.; Homan, D.

    2005-01-01

    Atom skimmers are devices that act as low-pass velocity filters for atoms in thermal atomic beams. An atom skimmer operating in conjunction with a suitable thermal atomic-beam source (e.g., an oven in which cesium is heated) can serve as a source of slow atoms for a magneto-optical trap or other apparatus in an atomic-physics experiment. Phenomena that are studied in such apparatuses include Bose-Einstein condensation of atomic gases, spectra of trapped atoms, and collisions of slowly moving atoms. An atom skimmer includes a curved, low-thermal-conduction tube that leads from the outlet of a thermal atomic-beam source to the inlet of a magneto-optical trap or other device in which the selected low-velocity atoms are to be used. Permanent rare-earth magnets are placed around the tube in a yoke of high-magnetic-permeability material to establish a quadrupole or octupole magnetic field leading from the source to the trap. The atoms are attracted to the locus of minimum magnetic-field intensity in the middle of the tube, and the gradient of the magnetic field provides centripetal force that guides the atoms around the curve along the axis of the tube. The threshold velocity for guiding is dictated by the gradient of the magnetic field and the radius of curvature of the tube. Atoms moving at lesser velocities are successfully guided; faster atoms strike the tube wall and are lost from the beam.

  14. High Atom Number in Microsized Atom Traps

    Science.gov (United States)

    2015-12-14

    Final Performance Report on ONR Grant N00014-12-1-0608 High atom number in microsized atom traps for the period 15 May 2012 through 14 September...TYPE Final Technical Report 3. DATES COVERED (From - To) 05/15/2012-09/14/2012 4. TITLE AND SUBTITLE High atom number in microsized atom traps...forces for implementing a small-footprint, large-number atom -chip instrument. Bichromatic forces rely on absorption and stimulated emission to produce

  15. "Bohr's Atomic Model."

    Science.gov (United States)

    Willden, Jeff

    2001-01-01

    "Bohr's Atomic Model" is a small interactive multimedia program that introduces the viewer to a simplified model of the atom. This interactive simulation lets students build an atom using an atomic construction set. The underlying design methodology for "Bohr's Atomic Model" is model-centered instruction, which means the central model of the…

  16. Teach us atom structure

    Energy Technology Data Exchange (ETDEWEB)

    Lim, Suh Yeon

    2006-08-15

    This book is written to teach atom structure in very easy way. It is divided into nine chapters, which indicates what is the components of matter? when we divide matter continuously, it becomes atom, what did atom look like? particles comprised of matter is not only atom, discover of particles comprised of atom, symbol of element, various radiation, form alchemy to nuclear transmutation, shape of atom is evolving. It also has various pictures in each chapters to explain easily.

  17. Playing pinball with atoms.

    Science.gov (United States)

    Saedi, Amirmehdi; van Houselt, Arie; van Gastel, Raoul; Poelsema, Bene; Zandvliet, Harold J W

    2009-05-01

    We demonstrate the feasibility of controlling an atomic scale mechanical device by an external electrical signal. On a germanium substrate, a switching motion of pairs of atoms is induced by electrons that are directly injected into the atoms with a scanning tunneling microscope tip. By precisely controlling the tip current and distance we make two atom pairs behave like the flippers of an atomic-sized pinball machine. This atomic scale mechanical device exhibits six different configurations.

  18. Claisen rearrangement of allyl phenyl ether: heavy-atom kinetic isotope effects and bond orders in the transition structure

    Energy Technology Data Exchange (ETDEWEB)

    Kupczyk-Subotkowska, L.; Saunders, W.H. Jr.; Shine, H.J.

    1988-10-12

    Kinetic isotope effects (KIE) were measured for the rearrangement at 220/degree/C of allyl ether (1) which was labeled successively at its oxygen atom ((/sup 18/O)-1), /alpha/-carbon atom ((/alpha/-/sup 14/C)-1), /gamma/-carbon atom ((/gamma/-/sup 14/C)-1), and ortho-carbon atom ((2-/sup 14/C)-1). The KIE were 1.0297 (/sup 18/O), 1.0306 (/alpha/-/sup 14/C), 1.0362 (/gamma/-/sup 14/C), and 1.0375 (2-/sup 14/C). KIE were determined from isotopic abundances in the product, o-allylphenol (2), which were measured by multiscan mass spectrometry (/sup 18/O) and scintillation counting (/sup 14/C). A model of the transition structure was then developed, whose bond orders gave calculated KIE in reasonably good agreement not only with the experimentally determined heavy-atom KIE but also with the deuterium KIE reported earlier by McMichael and Korver. A loose transition structure was thus found for the rearrangement of 1 into 2. In this transition structure the C/sub /alpha//-O bond is 50-60% broken while the C/sub /gamma//-C/sub ortho/ bond is only 10-20% complete. The results thus define this concerted, nonsynchronous rearrangement more explicitly than hitherto possible. 40 references, 8 tables.

  19. Control the fear atomic

    Energy Technology Data Exchange (ETDEWEB)

    Park, Jong Gwan [I and Book, Seoul (Korea, Republic of)

    2003-04-15

    This book has a lot of explanation of nuclear energy with articles. Their titles are the bad man likes atomic, the secret of atom, nuclear explosion, NPT?, the secret of uranium fuel rod, nuclear power plant vs nuclear bomb, I hate atomic, keep plutonium in control, atomic in peace and find out alternative energy.

  20. Microfabricated Waveguide Atom Traps.

    Energy Technology Data Exchange (ETDEWEB)

    Jau, Yuan-Yu [Sandia National Lab. (SNL-NM), Albuquerque, NM (United States)

    2017-09-01

    A nanoscale , microfabricated waveguide structure can in - principle be used to trap atoms in well - defined locations and enable strong photon-atom interactions . A neutral - atom platform based on this microfabrication technology will be prealigned , which is especially important for quantum - control applications. At present, there is still no reported demonstration of evanescent - field atom trapping using a microfabricated waveguide structure. We described the capabilities established by our team for future development of the waveguide atom - trapping technology at SNL and report our studies to overcome the technical challenges of loading cold atoms into the waveguide atom traps, efficient and broadband optical coupling to a waveguide, and the waveguide material for high - power optical transmission. From the atomic - physics and the waveguide modeling, w e have shown that a square nano-waveguide can be utilized t o achieve better atomic spin squeezing than using a nanofiber for first time.

  1. Atomic and molecular manipulation

    CERN Document Server

    Mayne, Andrew J

    2011-01-01

    Work with individual atoms and molecules aims to demonstrate that miniaturized electronic, optical, magnetic, and mechanical devices can operate ultimately even at the level of a single atom or molecule. As such, atomic and molecular manipulation has played an emblematic role in the development of the field of nanoscience. New methods based on the use of the scanning tunnelling microscope (STM) have been developed to characterize and manipulate all the degrees of freedom of individual atoms and molecules with an unprecedented precision. In the meantime, new concepts have emerged to design molecules and substrates having specific optical, mechanical and electronic functions, thus opening the way to the fabrication of real nano-machines. Manipulation of individual atoms and molecules has also opened up completely new areas of research and knowledge, raising fundamental questions of "Optics at the atomic scale", "Mechanics at the atomic scale", Electronics at the atomic scale", "Quantum physics at the atomic sca...

  2. Advances in atomic spectroscopy

    CERN Document Server

    Sneddon, J

    2000-01-01

    This fifth volume of the successful series Advances in Atomic Spectroscopy continues to discuss and investigate the area of atomic spectroscopy.It begins with a description of the use of various atomic spectroscopic methods and applications of speciation studies in atomic spectroscopy. The emphasis is on combining atomic spectroscopy with gas and liquid chromatography. In chapter two the authors describe new developments in tunable lasers and the impact they will have on atomic spectroscopy. The traditional methods of detection, such as photography and the photomultiplier, and how they are being replaced by new detectors is discussed in chapter three. The very active area of glow discharge atomic spectrometry is presented in chapter four where, after a brief introduction and historical review, the use of glow discharge lamps for atomic spectroscopy and mass spectrometry are discussed. Included in this discussion is geometry and radiofrequency power. The future of this source in atomic spectroscopy is also dis...

  3. Atomic vapor density monitor

    Energy Technology Data Exchange (ETDEWEB)

    Sewall, N.; Harris, W.; Beeler, R.; Wooldridge, J.; Chen, H.L.

    1986-09-01

    This report presents information on the Atomic Vapor Density Monitor (AVDM) system that measures the density of a vapor by measuring the absorption of light from a swept-wavelength laser that passes through an atomic vapor stream.

  4. Atomic Spectra Database (ASD)

    Science.gov (United States)

    SRD 78 NIST Atomic Spectra Database (ASD) (Web, free access)   This database provides access and search capability for NIST critically evaluated data on atomic energy levels, wavelengths, and transition probabilities that are reasonably up-to-date. The NIST Atomic Spectroscopy Data Center has carried out these critical compilations.

  5. Playing Pinball with Atoms

    NARCIS (Netherlands)

    Saedi, A.; van Houselt, Arie; van Gastel, Raoul; Poelsema, Bene; Zandvliet, Henricus J.W.

    2009-01-01

    We demonstrate the feasibility of controlling an atomic scale mechanical device by an external electrical signal. On a germanium substrate, a switching motion of pairs of atoms is induced by electrons that are directly injected into the atoms with a scanning tunneling microscope tip. By precisely

  6. Atomization characteristics of a prefilming airblast atomizer

    Science.gov (United States)

    Hayashi, Shigeru; Koito, Atsushi; Hishiki, Manabu

    1992-01-01

    The size distribution of water test sprays generated by a prefilming airblast atomizer used for aeroengines was measured in swirling and non-swirling flows with the well established laser scattering particle sizing technique. Atomizing air velocity (or pressure difference) was varied in a range wider than the conditions of actual engines. The Sauter Mean Diameter (SMD) decreased at approximately a 1.5 power of the atomizing air velocity, being a higher velocity index than the previously reported values of 1 to 1.2. It was unexpectedly found that the effect of the liquid/air flow ratio was small. Since swirling flow increased the SMD at lower air velocities yet decreased it at higher ones, it is suggested that the reverse flow near the nozzle pintle adversely affects atomization.

  7. Single atom electrochemical and atomic analytics

    Science.gov (United States)

    Vasudevan, Rama

    In the past decade, advances in electron and scanning-probe based microscopies have led to a wealth of imaging and spectroscopic data with atomic resolution, yielding substantial insight into local physics and chemistry in a diverse range of systems such as oxide catalysts, multiferroics, manganites, and 2D materials. However, typical analysis of atomically resolved images is limited, despite the fact that image intensities and distortions of the atoms from their idealized positions contain unique information on the physical and chemical properties inherent to the system. Here, we present approaches to data mine atomically resolved images in oxides, specifically in the hole-doped manganite La5/8Ca3/8MnO3, on epitaxial films studied by in-situ scanning tunnelling microscopy (STM). Through application of bias to the STM tip, atomic-scale electrochemistry is demonstrated on the manganite surface. STM images are then further analyzed through a suite of algorithms including 2D autocorrelations, sliding window Fourier transforms, and others, and can be combined with basic thermodynamic modelling to reveal relevant physical and chemical descriptors including segregation energies, existence and strength of atomic-scale diffusion barriers, surface energies and sub-surface chemical species identification. These approaches promise to provide tremendous insights from atomically resolved functional imaging, can provide relevant thermodynamic parameters, and auger well for use with first-principles calculations to yield quantitative atomic-level chemical identification and structure-property relations. This research was sponsored by the Division of Materials Sciences and Engineering, BES, DOE. Research was conducted at the Center for Nanophase Materials Sciences, which also provided support and is a DOE Office of Science User Facility.

  8. Multilevel Atomic Coherent States and Atomic Holomorphic Representation

    Science.gov (United States)

    Cao, Chang-Qi; Haake, Fritz

    1996-01-01

    The notion of atomic coherent states is extended to the case of multilevel atom collective. Based on atomic coherent states, a holomorphic representation for atom collective states and operators is defined. An example is given to illustrate its application.

  9. Long range intermolecular forces in triatomic systems: connecting the atom-diatom and atom-atom-atom representations

    OpenAIRE

    Cvitas, Marko T.; Soldan, Pavel; Hutson, Jeremy M.

    2005-01-01

    The long-range forces that act between three atoms are analysed in both atom-diatom and atom-atom-atom representations. Expressions for atom-diatom dispersion coefficients are obtained in terms of 3-body nonadditive coefficients. The anisotropy of atom-diatom C_6 dispersion coefficients arises primarily from nonadditive triple-dipole and quadruple-dipole forces, while pairwise-additive forces and nonadditive triple-dipole and dipole-dipole-quadrupole forces contribute significantly to atom-di...

  10. Modern atomic physics

    CERN Document Server

    Natarajan, Vasant

    2015-01-01

    Much of our understanding of physics in the last 30-plus years has come from research on atoms, photons, and their interactions. Collecting information previously scattered throughout the literature, Modern Atomic Physics provides students with one unified guide to contemporary developments in the field. After reviewing metrology and preliminary material, the text explains core areas of atomic physics. Important topics discussed include the spontaneous emission of radiation, stimulated transitions and the properties of gas, the physics and applications of resonance fluorescence, coherence, cooling and trapping of charged and neutral particles, and atomic beam magnetic resonance experiments. Covering standards, a different way of looking at a photon, stimulated radiation, and frequency combs, the appendices avoid jargon and use historical notes and personal anecdotes to make the topics accessible to non-atomic physics students. Written by a leader in atomic and optical physics, this text gives a state-of-the...

  11. Single atom microscopy.

    Science.gov (United States)

    Zhou, Wu; Oxley, Mark P; Lupini, Andrew R; Krivanek, Ondrej L; Pennycook, Stephen J; Idrobo, Juan-Carlos

    2012-12-01

    We show that aberration-corrected scanning transmission electron microscopy operating at low accelerating voltages is able to analyze, simultaneously and with single atom resolution and sensitivity, the local atomic configuration, chemical identities, and optical response at point defect sites in monolayer graphene. Sequential fast-scan annular dark-field (ADF) imaging provides direct visualization of point defect diffusion within the graphene lattice, with all atoms clearly resolved and identified via quantitative image analysis. Summing multiple ADF frames of stationary defects produce images with minimized statistical noise and reduced distortions of atomic positions. Electron energy-loss spectrum imaging of single atoms allows the delocalization of inelastic scattering to be quantified, and full quantum mechanical calculations are able to describe the delocalization effect with good accuracy. These capabilities open new opportunities to probe the defect structure, defect dynamics, and local optical properties in 2D materials with single atom sensitivity.

  12. Solar Spectroscopy: Atomic Processes

    Science.gov (United States)

    Mason, H.; Murdin, P.

    2000-11-01

    A Greek philosopher called DEMOCRITUS (c. 460-370 BC) first introduced the concept of atoms (which means indivisible). His atoms do not precisely correspond to our atoms of today, which are not indivisible, but made up of a nucleus (protons with positive charge and neutrons which have no charge) and orbiting electrons (with negative charge). Indeed, in the solar atmosphere, the temperature is suc...

  13. Advances in atomic spectroscopy

    CERN Document Server

    Sneddon, J

    1997-01-01

    This series describes selected advances in the area of atomic spectroscopy. It is primarily intended for the reader who has a background in atmoic spectroscopy; suitable to the novice and expert. Although a widely used and accepted method for metal and non-metal analysis in a variety of complex samples, Advances in Atomic Spectroscopy covers a wide range of materials. Each Chapter will completely cover an area of atomic spectroscopy where rapid development has occurred.

  14. Atoms, Molecules, and Compounds

    CERN Document Server

    Manning, Phillip

    2007-01-01

    Explores the atoms that govern chemical processes. This book shows how the interactions between simple substances such as salt and water are crucial to life on Earth and how those interactions are predestined by the atoms that make up the molecules.

  15. Atoms, Molecules and Radiation

    Indian Academy of Sciences (India)

    IAS Admin

    A Refresher Course in Applications of Quantum Mechanics to 'Atoms, Molecules and Radiation' will be held at the Indian Academy of Sciences, Bangalore from December 8 to 20. 2014. The Course is primarily aimed at teachers teaching quantum mechanics and/ or atomic and molecular physics at the UG / PG level.

  16. When Atoms Want

    Science.gov (United States)

    Talanquer, Vicente

    2013-01-01

    Chemistry students and teachers often explain the chemical reactivity of atoms, molecules, and chemical substances in terms of purposes or needs (e.g., atoms want or need to gain, lose, or share electrons in order to become more stable). These teleological explanations seem to have pedagogical value as they help students understand and use…

  17. Atomicity in Electronic Commerce,

    Science.gov (United States)

    1996-01-01

    Atomicity in Electronic Commerce J. D. Tygar January 1996 CMU-CS-96-112 School of Computer Science Carnegie Mellon University Pittsburgh, PA 15213...other research sponsor. Keywords: electronic commerce , atomicity, NetBill, IBIP, cryptography, transaction pro- cessing, ACID, franking, electronic ...goods over networks. Electronic commerce has inspired a large variety of work. Unfortunately, much of that work ignores traditional transaction

  18. Theoretical atomic physics

    CERN Document Server

    Friedrich, Harald

    2017-01-01

    This expanded and updated well-established textbook contains an advanced presentation of quantum mechanics adapted to the requirements of modern atomic physics. It includes topics of current interest such as semiclassical theory, chaos, atom optics and Bose-Einstein condensation in atomic gases. In order to facilitate the consolidation of the material covered, various problems are included, together with complete solutions. The emphasis on theory enables the reader to appreciate the fundamental assumptions underlying standard theoretical constructs and to embark on independent research projects. The fourth edition of Theoretical Atomic Physics contains an updated treatment of the sections involving scattering theory and near-threshold phenomena manifest in the behaviour of cold atoms (and molecules). Special attention is given to the quantization of weakly bound states just below the continuum threshold and to low-energy scattering and quantum reflection just above. Particular emphasis is laid on the fundamen...

  19. Atomic diffusion in stars

    CERN Document Server

    Michaud, Georges; Richer, Jacques

    2015-01-01

    This book gives an overview of atomic diffusion, a fundamental physical process, as applied to all types of stars, from the main sequence to neutron stars. The superficial abundances of stars as well as their evolution can be significantly affected. The authors show where atomic diffusion plays an essential role and how it can be implemented in modelling.  In Part I, the authors describe the tools that are required to include atomic diffusion in models of stellar interiors and atmospheres. An important role is played by the gradient of partial radiative pressure, or radiative acceleration, which is usually neglected in stellar evolution. In Part II, the authors systematically review the contribution of atomic diffusion to each evolutionary step. The dominant effects of atomic diffusion are accompanied by more subtle effects on a large number of structural properties throughout evolution. One of the goals of this book is to provide the means for the astrophysicist or graduate student to evaluate the importanc...

  20. Maximally Atomic Languages

    Directory of Open Access Journals (Sweden)

    Janusz Brzozowski

    2014-05-01

    Full Text Available The atoms of a regular language are non-empty intersections of complemented and uncomplemented quotients of the language. Tight upper bounds on the number of atoms of a language and on the quotient complexities of atoms are known. We introduce a new class of regular languages, called the maximally atomic languages, consisting of all languages meeting these bounds. We prove the following result: If L is a regular language of quotient complexity n and G is the subgroup of permutations in the transition semigroup T of the minimal DFA of L, then L is maximally atomic if and only if G is transitive on k-subsets of 1,...,n for 0 <= k <= n and T contains a transformation of rank n-1.

  1. Single-atom nanoelectronics

    CERN Document Server

    Prati, Enrico

    2013-01-01

    Single-Atom Nanoelectronics covers the fabrication of single-atom devices and related technology, as well as the relevant electronic equipment and the intriguing new phenomena related to single-atom and single-electron effects in quantum devices. It also covers the alternative approaches related to both silicon- and carbon-based technologies, also from the point of view of large-scale industrial production. The publication provides a comprehensive picture of the state of the art at the cutting edge and constitutes a milestone in the emerging field of beyond-CMOS technology. Although there are

  2. Physics of the atom

    CERN Document Server

    Wehr, Russell M; Adair, Thomas W

    1984-01-01

    The fourth edition of Physics of the Atom is designed to meet the modern need for a better understanding of the atomic age. It is an introduction suitable for students with a background in university physics and mathematical competence at the level of calculus. This book is designed to be an extension of the introductory university physics course into the realm of atomic physics. It should give students a proficiency in this field comparable to their proficiency in mechanics, heat, sound, light, and electricity.

  3. Atomic & Molecular Interactions

    Energy Technology Data Exchange (ETDEWEB)

    None

    2002-07-12

    The Gordon Research Conference (GRC) on Atomic & Molecular Interactions was held at Roger Williams University, Bristol, RI. Emphasis was placed on current unpublished research and discussion of the future target areas in this field.

  4. The Casimir atomic pendulum

    Energy Technology Data Exchange (ETDEWEB)

    Razmi, H. [Department of Physics, University of Qom, Qom 37185-359 (Iran, Islamic Republic of)], E-mail: razmi@qom.ac.ir; Abdollahi, M. [Department of Physics, University of Qom, Qom 37185-359 (Iran, Islamic Republic of)], E-mail: mah.abdollahi@gmail.com

    2008-11-10

    We want to introduce an atomic pendulum whose driving force (torque) is due to the quantum vacuum fluctuations. Applying the well-known Casimir-Polder effect to a special configuration (a combined structure of an atomic nanostring and a conducting plate), an atomic pendulum (Casimir atomic pendulum) is designed. Using practically acceptable data corresponding to the already known world of nanotechnology and based on reasonable/reliable numerical estimates, the period of oscillation for the pendulum is computed. This pendulum can be considered as both a new micro(nano)-electromechanical system and a new simple vacuum machine. Its design may be considered as a first step towards realizing the visualized vacuum (Casimir) clock{exclamation_point}.

  5. The Casimir atomic pendulum

    Science.gov (United States)

    Razmi, H.; Abdollahi, M.

    2008-11-01

    We want to introduce an atomic pendulum whose driving force (torque) is due to the quantum vacuum fluctuations. Applying the well-known Casimir-Polder effect to a special configuration (a combined structure of an atomic nanostring and a conducting plate), an atomic pendulum (Casimir atomic pendulum) is designed. Using practically acceptable data corresponding to the already known world of nanotechnology and based on reasonable/reliable numerical estimates, the period of oscillation for the pendulum is computed. This pendulum can be considered as both a new micro(nano)-electromechanical system and a new simple vacuum machine. Its design may be considered as a first step towards realizing the visualized vacuum (Casimir) clock!

  6. Advances in atomic spectroscopy

    CERN Document Server

    Sneddon, J

    1998-01-01

    This volume continues the series'' cutting-edge reviews on developments in this field. Since its invention in the 1920s, electrostatic precipitation has been extensively used in industrial hygiene to remove dust and particulate matter from gases before entering the atmosphere. This combination of electrostatic precipitation is reported upon in the first chapter. Following this, chapter two reviews recent advances in the area of chemical modification in electrothermal atomization. Chapter three consists of a review which deal with advances and uses of electrothermal atomization atomic absorption spectrometry. Flow injection atomic spectroscopy has developed rapidly in recent years and after a general introduction, various aspects of this technique are looked at in chapter four. Finally, in chapter five the use of various spectrometric techniques for the determination of mercury are described.

  7. Dalton's Atomic Theory

    National Research Council Canada - National Science Library

    DOBBIN, LEONARD

    1896-01-01

    WITH reference to the communications from the authors and from the reviewer of the "New View of the Origin of Dalton's Atomic Theory," published in NATURE for May 14, I beg leave to offer the following remarks...

  8. Atomic Interferometry Project

    Data.gov (United States)

    National Aeronautics and Space Administration — Vertical cavity surface emitting lasers (VCSELs) is a new technology which can be used for developing high performance laser components for atom-based sensors...

  9. Topics in atomic physics

    CERN Document Server

    Burkhardt, Charles E

    2006-01-01

    The study of atomic physics propelled us into the quantum age in the early twentieth century and carried us into the twenty-first century with a wealth of new and, in some cases, unexplained phenomena. Topics in Atomic Physics provides a foundation for students to begin research in modern atomic physics. It can also serve as a reference because it contains material that is not easily located in other sources. A distinguishing feature is the thorough exposition of the quantum mechanical hydrogen atom using both the traditional formulation and an alternative treatment not usually found in textbooks. The alternative treatment exploits the preeminent nature of the pure Coulomb potential and places the Lenz vector operator on an equal footing with other operators corresponding to classically conserved quantities. A number of difficult to find proofs and derivations are included as is development of operator formalism that permits facile solution of the Stark effect in hydrogen. Discussion of the classical hydrogen...

  10. Zeeman atomic absorption spectrometry

    Energy Technology Data Exchange (ETDEWEB)

    Hadeishi, T.; McLaughlin, R.

    1978-08-01

    The design and development of a Zeeman atomic absorption spectrometer for trace element analysis are described. An instruction manual is included which details the operation, adjustment, and maintenance. Specifications and circuit diagrams are given. (WHK)

  11. Atomic Clocks Research - An Overview.

    Science.gov (United States)

    1987-08-15

    magnet. Since atomic deflection in an inhomogeneous magnetic field is inversely proportional to the square of the atomic speed, the atomic velocity...purifier and controlled leak; an atomic source (i.e., the dissociator under 39 study); a dipole electromagnetic with pole pieces shaped to produce an...34Relaxation Magnetique d’Atomes de Rubidium sur des Parois Paraffines," J. Phys. (Paris) 24, 379 (1963). 21. S. Wexler, "Deposition of Atomic Beams

  12. Wave Atom Based Watermarking

    OpenAIRE

    Bukhari, Ijaz; Nuhman-ul-Haq; Hyat, Khizar

    2013-01-01

    Watermarking helps in ensuring originality, ownership and copyrights of a digital image. This paper aims at embedding a Watermark in an image using Wave Atom Transform. Preference of Wave Atoms on other transformations has been due to its sparser expansion, adaptability to the direction of local pattern, and sharp frequency localization. In this scheme, we had tried to spread the watermark in an image so that the information at one place is very small and undetectable. In order to extract the...

  13. Hirshfeld atom refinement.

    Science.gov (United States)

    Capelli, Silvia C; Bürgi, Hans-Beat; Dittrich, Birger; Grabowsky, Simon; Jayatilaka, Dylan

    2014-09-01

    Hirshfeld atom refinement (HAR) is a method which determines structural parameters from single-crystal X-ray diffraction data by using an aspherical atom partitioning of tailor-made ab initio quantum mechanical molecular electron densities without any further approximation. Here the original HAR method is extended by implementing an iterative procedure of successive cycles of electron density calculations, Hirshfeld atom scattering factor calculations and structural least-squares refinements, repeated until convergence. The importance of this iterative procedure is illustrated via the example of crystalline ammonia. The new HAR method is then applied to X-ray diffraction data of the dipeptide Gly-l-Ala measured at 12, 50, 100, 150, 220 and 295 K, using Hartree-Fock and BLYP density functional theory electron densities and three different basis sets. All positions and anisotropic displacement parameters (ADPs) are freely refined without constraints or restraints - even those for hydrogen atoms. The results are systematically compared with those from neutron diffraction experiments at the temperatures 12, 50, 150 and 295 K. Although non-hydrogen-atom ADPs differ by up to three combined standard uncertainties (csu's), all other structural parameters agree within less than 2 csu's. Using our best calculations (BLYP/cc-pVTZ, recommended for organic molecules), the accuracy of determining bond lengths involving hydrogen atoms from HAR is better than 0.009 Å for temperatures of 150 K or below; for hydrogen-atom ADPs it is better than 0.006 Å(2) as judged from the mean absolute X-ray minus neutron differences. These results are among the best ever obtained. Remarkably, the precision of determining bond lengths and ADPs for the hydrogen atoms from the HAR procedure is comparable with that from the neutron measurements - an outcome which is obtained with a routinely achievable resolution of the X-ray data of 0.65 Å.

  14. Atoms, molecules & elements

    CERN Document Server

    Graybill, George

    2007-01-01

    Young scientists will be thrilled to explore the invisible world of atoms, molecules and elements. Our resource provides ready-to-use information and activities for remedial students using simplified language and vocabulary. Students will label each part of the atom, learn what compounds are, and explore the patterns in the periodic table of elements to find calcium (Ca), chlorine (Cl), and helium (He) through hands-on activities.

  15. Atomic Bomb Health Benefits

    OpenAIRE

    Luckey, T. D.

    2008-01-01

    Media reports of deaths and devastation produced by atomic bombs convinced people around the world that all ionizing radiation is harmful. This concentrated attention on fear of miniscule doses of radiation. Soon the linear no threshold (LNT) paradigm was converted into laws. Scientifically valid information about the health benefits from low dose irradiation was ignored. Here are studies which show increased health in Japanese survivors of atomic bombs. Parameters include decreased mutation,...

  16. Atomic interferometry; Interferometrie atomique

    Energy Technology Data Exchange (ETDEWEB)

    Baudon, J.; Robert, J. [Paris-13 Univ., 93 - Saint-Denis (France)

    2004-07-01

    Since the theoretical works of L. De Broglie (1924) and the famous experiment of Davisson and Germer (1927), we know that a wave is linked with any particle of mass m by the relation {lambda} = h/(mv), where {lambda} is the wavelength, v the particle velocity and h is the Planck constant. The basic principle of the interferometry of any material particle, atom, molecule or aggregate is simple: using a simple incident wave, several mutually consistent waves (with well-defined relative phases) are generated and controllable phase-shifts are introduced between them in order to generate a wave which is the sum of the previous waves. An interference figure is obtained which consists in a succession of dark and bright fringes. The atomic interferometry is based on the same principle but involves different techniques, different wave equations, but also different beams, sources and correlations which are described in this book. Because of the small possible wavelengths and the wide range of possible atomic interactions, atomic interferometers can be used in many domains from the sub-micron lithography to the construction of sensors like: inertial sensors, gravity-meters, accelerometers, gyro-meters etc. The first chapter is a preliminary study of the space and time diffraction of atoms. The next chapters is devoted to the description of slit, light separation and polarization interferometers, and the last chapter treats of the properties of Bose-Einstein condensates which are interesting in atomic interferometry. (J.S.)

  17. Atomic bomb and leukemia

    Energy Technology Data Exchange (ETDEWEB)

    Ichimaru, M.; Tomonaga, M.; Amenomori, T.; Matsuo, T. (Nagasaki Univ. (Japan). School of Medicine)

    1991-12-01

    Characteristic features of the leukemia among atomic bomb survivors were studied. Dose estimates of atomic bomb radiation were based on T65D, but the new dosimetry system DS86 was used for some analyses. The ratio of a single leukemia type to all leukemias was highest for chronic myelogenous leukemia (CML) in Hiroshima, and the occurrence of CML was thought to be most characteristic to atomic bomb radiation induced leukemia. The threshold of CML occurrence in Hiroshima is likely to be between 0.5{approx}0.09 Gy. However, the threshold of acute leukemia appears to be nearly 1 Gy. In the distribution of acute myeloid leukemia (AML) subtypes by French-American-British classification, there was no M3 case in 1 Gy or more group, although several atypical AML cases of survivors were observed. Although aplastic anemia has not increased as a late effect of the atomic bomb radiation exposure, many atypical leukemia or other myeloproliferative diseases who had been diagnosed as aplastic anemia or its related diseases have been experienced among atomic bomb survivors. Chromosome study was conducted using colony forming cells induced by hemopoietic stem cells of peripheral blood of proximal survivors. Same chromosome aberrations were observed in colony forming cells and peripheral T-cells in several atomic bomb survivors. (author).

  18. Universal bosonic tetramers of dimer-atom-atom structure

    OpenAIRE

    Deltuva, A.

    2012-01-01

    Unstable four-boson states having an approximate dimer-atom-atom structure are studied using momentum-space integral equations for the four-particle transition operators. For a given Efimov trimer the universal properties of the lowest associated tetramer are determined. The impact of this tetramer on the atom-trimer and dimer-dimer collisions is analyzed. The reliability of the three-body dimer-atom-atom model is studied.

  19. Sampling the Hydrogen Atom

    Directory of Open Access Journals (Sweden)

    Graves N.

    2013-01-01

    Full Text Available A model is proposed for the hydrogen atom in which the electron is an objectively real particle orbiting at very near to light speed. The model is based on the postulate that certain velocity terms associated with orbiting bodies can be considered as being af- fected by relativity. This leads to a model for the atom in which the stable electron orbits are associated with orbital velocities where Gamma is n /α , leading to the idea that it is Gamma that is quantized and not angular momentum as in the Bohr and other models. The model provides a mechanism which leads to quantization of energy levels within the atom and also provides a simple mechanical explanation for the Fine Struc- ture Constant. The mechanism is closely associated with the Sampling theorem and the related phenomenon of aliasing developed in the mid-20th century by engineers at Bell labs.

  20. Atomic Force Microscope

    Energy Technology Data Exchange (ETDEWEB)

    Day, R.D.; Russell, P.E.

    1988-12-01

    The Atomic Force Microscope (AFM) is a recently developed instrument that has achieved atomic resolution imaging of both conducting and non- conducting surfaces. Because the AFM is in the early stages of development, and because of the difficulty of building the instrument, it is currently in use in fewer than ten laboratories worldwide. It promises to be a valuable tool for obtaining information about engineering surfaces and aiding the .study of precision fabrication processes. This paper gives an overview of AFM technology and presents plans to build an instrument designed to look at engineering surfaces.

  1. Hirshfeld atom refinement

    Directory of Open Access Journals (Sweden)

    Silvia C. Capelli

    2014-09-01

    Full Text Available Hirshfeld atom refinement (HAR is a method which determines structural parameters from single-crystal X-ray diffraction data by using an aspherical atom partitioning of tailor-made ab initio quantum mechanical molecular electron densities without any further approximation. Here the original HAR method is extended by implementing an iterative procedure of successive cycles of electron density calculations, Hirshfeld atom scattering factor calculations and structural least-squares refinements, repeated until convergence. The importance of this iterative procedure is illustrated via the example of crystalline ammonia. The new HAR method is then applied to X-ray diffraction data of the dipeptide Gly–l-Ala measured at 12, 50, 100, 150, 220 and 295 K, using Hartree–Fock and BLYP density functional theory electron densities and three different basis sets. All positions and anisotropic displacement parameters (ADPs are freely refined without constraints or restraints – even those for hydrogen atoms. The results are systematically compared with those from neutron diffraction experiments at the temperatures 12, 50, 150 and 295 K. Although non-hydrogen-atom ADPs differ by up to three combined standard uncertainties (csu's, all other structural parameters agree within less than 2 csu's. Using our best calculations (BLYP/cc-pVTZ, recommended for organic molecules, the accuracy of determining bond lengths involving hydrogen atoms from HAR is better than 0.009 Å for temperatures of 150 K or below; for hydrogen-atom ADPs it is better than 0.006 Å2 as judged from the mean absolute X-ray minus neutron differences. These results are among the best ever obtained. Remarkably, the precision of determining bond lengths and ADPs for the hydrogen atoms from the HAR procedure is comparable with that from the neutron measurements – an outcome which is obtained with a routinely achievable resolution of the X-ray data of 0.65 Å.

  2. Optically pumped atoms

    CERN Document Server

    Happer, William; Walker, Thad

    2010-01-01

    Covering the most important knowledge on optical pumping of atoms, this ready reference is backed by numerous examples of modelling computation for optical pumped systems. The authors show for the first time that modern scientific computing software makes it practical to analyze the full, multilevel system of optically pumped atoms. To make the discussion less abstract, the authors have illustrated key points with sections of MATLAB codes. To make most effective use of contemporary mathematical software, it is especially useful to analyze optical pumping situations in the Liouville spa

  3. Atoms in Agriculture

    Energy Technology Data Exchange (ETDEWEB)

    Osborne, Thomas S. [University of Tennessee

    1965-01-01

    Agriculture benefits from the applications of research. Radioactive techniques have been used to study soils, plants, microbes, insects, farm animals, and new ways to use and preserve foodstuffs. Radioactive atoms are not used directly by farmers but are used in research directed by the U. S. Department of Agriculture and Atomic Energy Commission, by the agricultural experiment stations of the various states, and by numerous public and private research institutions. From such research come improved materials and methods which are used on the farm.

  4. From Atoms to Solids

    Science.gov (United States)

    1999-01-31

    Honea. M.L. Homer, J.L. Persson, R.L. Whetten , Chem. atoms Phys. Lett. 171 (1990) 147. [17] M.R. Hoare, Adv. Chem. Phys. 40 (1979) 49. Two types of...Persson, M.E. LaVilla, R.L. tal conditions, the clusters become rigid. Thereafter, Whetten , J. Phys. Chem. 93 (1989) 2869. each newly added atom condenses...106 (1981) 265. M. Broyer, Phys. Rev. A 39 (1989) 6056. [9] W. Ekardt, Ber. Bunsenges. Phys. Chem. 88 (1984) 289. [38] R.L. Whetten , private

  5. Korean atomic bomb victims.

    Science.gov (United States)

    Sasamoto, Yukuo

    2009-01-01

    After colonizing Korea, Japan invaded China, and subsequently initiated the Pacific War against the United States, Britain, and their allies. Towards the end of the war, U.S. warplanes dropped atomic bombs on Hiroshima and Nagasaki, which resulted in a large number of Koreans who lived in Hiroshima and Nagasaki suffering from the effects of the bombs. The objective of this paper is to examine the history of Korea atomic bomb victims who were caught in between the U.S., Japan, the Republic of Korea (South Korea) and the Democratic People's Republic of Korea (North Korea).

  6. Atomic bomb and leukemia

    Energy Technology Data Exchange (ETDEWEB)

    Ichimaru, Michito; Tomonaga, Masao; Amenomori, Tatsuhiko; Matsuo, Tatsuki (Nagasaki Univ. (Japan). School of Medicine)

    1991-03-01

    Characteristic features of leukemia among atomic bomb survivors were studied. The ratio of a single leukemia type to all leukemias was highest for CML in Hiroshima, and the occurrence of CML was thought to be most characteristic for atomic bomb radiation induced leukemia. In the distribution of AML subtypes of FAB classification, there was no M3 cases in 1 Gy or more group, although several atypical AML cases of survivors were observed. Chromosome study was conducted using colony forming cells induced by hemopoietic stem cells of peripheral blood of proximal survivors. Same chromosome aberrations were observed in colony forming cells and peripheral blood of proximal survivors. (author).

  7. Atomic Particle Detection

    Energy Technology Data Exchange (ETDEWEB)

    Hellman, Hal

    1970-01-01

    This booklet tells how scientists observe the particles and electromagnetic radiation that emerges from an atomic nucleus. The equipment used falls into two general categories: counters which count each particle as it passes by, and track detectors, which make a photographic record of the particle's track.

  8. FAC: Flexible Atomic Code

    Science.gov (United States)

    Gu, Ming Feng

    2018-02-01

    FAC calculates various atomic radiative and collisional processes, including radiative transition rates, collisional excitation and ionization by electron impact, energy levels, photoionization, and autoionization, and their inverse processes radiative recombination and dielectronic capture. The package also includes a collisional radiative model to construct synthetic spectra for plasmas under different physical conditions.

  9. Atomic physics and reality

    CERN Multimedia

    1985-01-01

    An account of the long standing debate between Niels Bohr and Albert Einstein regarding the validity of the quantum mechanical description of atomic phenomena.With physicts, John Wheeler (Texas), John Bell (CERN), David Rohm (London), Abner Shimony (Boston), Alain Aspect (Paris)

  10. Ludwig Boltzmann: Atomic genius

    Energy Technology Data Exchange (ETDEWEB)

    Cercignani, C. [Department of Mathematics, Politecnico di Milano (Italy)]. E-mail: carcer@mate.polimi.it

    2006-09-15

    On the centenary of the death of Ludwig Boltzmann, Carlo Cercignani examines the immense contributions of the man who pioneered our understanding of the atomic nature of matter. The man who first gave a convincing explanation of the irreversibility of the macroscopic world and the symmetry of the laws of physics was the Austrian physicist Ludwig Boltzmann, who tragically committed suicide 100 years ago this month. One of the key figures in the development of the atomic theory of matter, Boltzmann's fame will be forever linked to two fundamental contributions to science. The first was his interpretation of 'entropy' as a mathematically well-defined measure of the disorder of atoms. The second was his derivation of what is now known as the Boltzmann equation, which describes the statistical properties of a gas as made up of molecules. The equation, which described for the first time how a probability can evolve with time, allowed Boltzmann to explain why macroscopic phenomena are irreversible. The key point is that while microscopic objects like atoms can behave reversibly, we never see broken coffee cups reforming because it would involve a long series of highly improbable interactions - and not because it is forbidden by the laws of physics. (U.K.)

  11. Atomic Force Microscopy

    Indian Academy of Sciences (India)

    Home; Journals; Resonance – Journal of Science Education; Volume 15; Issue 7. Atomic Force Microscopy - A Tool to Unveil the Mystery of Biological Systems ... Transcription and Disease Laboratory, Molecular Biology and Genetics Unit, Jawaharlal Nehru Centre for Advanced Scientific Research, Jakkur, Bangalore 560 ...

  12. Observational Evidence for Atoms.

    Science.gov (United States)

    Jones, Edwin R., Jr.; Childers, Richard L.

    1984-01-01

    Discusses the development of the concept of atomicity and some of the many which can be used to establish its validity. Chemical evidence, evidence from crystals, Faraday's law of electrolysis, and Avogadro's number are among the areas which show how the concept originally developed from a purely philosophical idea. (JN)

  13. Modelling the Energetics of Encapsulation of Atoms and Atomic ...

    Indian Academy of Sciences (India)

    user

    2015-07-04

    Jul 4, 2015 ... Modelling the Energetics of Encapsulation of. Atoms and Atomic Clusters into Carbon. Nanotubes: Insights from Analytical Approaches. R. S. Swathi. School of Chemistry. Indian Institute of Science Education and Research. Thiruvananthapuram, Kerala, India ...

  14. Role of atoms in atomic gravitational-wave detectors

    Science.gov (United States)

    Norcia, Matthew A.; Cline, Julia R. K.; Thompson, James K.

    2017-10-01

    Recently, it has been proposed that space-based atomic sensors may be used to detect gravitational waves. These proposals describe the sensors either as clocks or as atom interferometers. Here, we seek to explore the fundamental similarities and differences between the two types of proposals. We present a framework in which the fundamental mechanism for sensitivity is identical for clock and atom interferometer proposals, with the key difference being whether or not the atoms are tightly confined by an external potential. With this interpretation in mind, we propose two major enhancements to detectors using confined atoms, which allow for an enhanced sensitivity analogous to large momentum transfer used in atom interferometry (though with no transfer of momentum to the atoms), and a way to extend the useful coherence time of the sensor beyond the atom's excited-state lifetime.

  15. Absorption imaging of ultracold atoms on atom chips

    DEFF Research Database (Denmark)

    Smith, David A.; Aigner, Simon; Hofferberth, Sebastian

    2011-01-01

    Imaging ultracold atomic gases close to surfaces is an important tool for the detailed analysis of experiments carried out using atom chips. We describe the critical factors that need be considered, especially when the imaging beam is purposely reflected from the surface. In particular we present...... methods to measure the atom-surface distance, which is a prerequisite for magnetic field imaging and studies of atom surface-interactions....

  16. Atomic Absorption, Atomic Fluorescence, and Flame Emission Spectrometry.

    Science.gov (United States)

    Horlick, Gary

    1984-01-01

    This review is presented in six sections. Sections focus on literature related to: (1) developments in instrumentation, measurement techniques, and procedures; (2) performance studies of flames and electrothermal atomizers; (3) applications of atomic absorption spectrometry; (4) analytical comparisons; (5) atomic fluorescence spectrometry; and (6)…

  17. Cavity enhanced atomic magnetometry.

    Science.gov (United States)

    Crepaz, Herbert; Ley, Li Yuan; Dumke, Rainer

    2015-10-20

    Atom sensing based on Faraday rotation is an indispensable method for precision measurements, universally suitable for both hot and cold atomic systems. Here we demonstrate an all-optical magnetometer where the optical cell for Faraday rotation spectroscopy is augmented with a low finesse cavity. Unlike in previous experiments, where specifically designed multipass cells had been employed, our scheme allows to use conventional, spherical vapour cells. Spherical shaped cells have the advantage that they can be effectively coated inside with a spin relaxation suppressing layer providing long spin coherence times without addition of a buffer gas. Cavity enhancement shows in an increase in optical polarization rotation and sensitivity compared to single-pass configurations.

  18. Cavity enhanced atomic magnetometry

    CERN Document Server

    Crepaz, Herbert; Dumke, Rainer

    2015-01-01

    Atom sensing based on Faraday rotation is an indispensable method for precision measurements, universally suitable for both hot and cold atomic systems. Here we demonstrate an all-optical magnetometer where the optical cell for Faraday rotation spectroscopy is augmented with a low finesse cavity. Unlike in previous experiments, where specifically designed multipass cells had been employed, our scheme allows to use conventional, spherical vapour cells. Spherical shaped cells have the advantage that they can be effectively coated inside with a spin relaxation suppressing layer providing long spin coherence times without addition of a buffer gas. Cavity enhancement shows in an increase in optical polarization rotation and sensitivity compared to single-pass configurations.

  19. Atomes et rayonnement

    OpenAIRE

    Dalibard, Jean; Haroche, Serge

    2013-01-01

    Matière et lumière sont intimement liées dans notre modélisation du monde physique. De l’élaboration de la théorie quantique à l’invention du laser, l’interaction entre atomes et rayonnement a joué un rôle central dans le développement de la science et de la technologie d’aujourd’hui. La maîtrise de cette interaction permet désormais d’atteindre les plus basses températures jamais mesurées. Le refroidissement de gaz d’atomes par la lumière d’un laser conduit à une « matière quantique » aux pr...

  20. Atomic emission spectroscopy

    Science.gov (United States)

    Andrew, K. H.

    1975-01-01

    The relationship between the Slater-Condon theory and the conditions within the atom as revealed by experimental data was investigated. The first spectrum of Si, Rb, Cl, Br, I, Ne, Ar, and Xe-136 and the second spectrum of As, Cu, and P were determined. Methods for assessing the phase stability of fringe counting interferometers and the design of an autoranging scanning system for digitizing the output of an infrared spectrometer and recording it on magnetic tape are described.

  1. Navigation with Atom Interferometers

    Science.gov (United States)

    2017-03-20

    stability of the design and will be measured at a future time. Angle random walk can be calculated from first principles from the shot-noise limited...interferometer cannot distinguish between the two sources of phase shifts. We describe a design for a dual atom interferometer to simultaneously...stability. This paper is organized as follows: we first describe the basic building blocks of the interferometer: beam splitters and mirrors. We then

  2. Into the atom and beyond

    CERN Document Server

    1989-01-01

    Magnifying an atom to football pitch size. The dense nucleus, carrying almost all the atomic mass, is much smaller than the ball. The players (the electrons) would see something about the size of a marble!

  3. Nuclear effects in atomic transitions

    CERN Document Server

    Pálffy, Adriana

    2011-01-01

    Atomic electrons are sensitive to the properties of the nucleus they are bound to, such as nuclear mass, charge distribution, spin, magnetization distribution, or even excited level scheme. These nuclear parameters are reflected in the atomic transition energies. A very precise determination of atomic spectra may thus reveal information about the nucleus, otherwise hardly accessible via nuclear physics experiments. This work reviews theoretical and experimental aspects of the nuclear effects that can be identified in atomic structure data. An introduction to the theory of isotope shifts and hyperfine splitting of atomic spectra is given, together with an overview of the typical experimental techniques used in high-precision atomic spectroscopy. More exotic effects at the borderline between atomic and nuclear physics, such as parity violation in atomic transitions due to the weak interaction, or nuclear polarization and nuclear excitation by electron capture, are also addressed.

  4. Atomic and Molecular Physics Program

    Science.gov (United States)

    2013-03-05

    Atomic Quantum Memories in Nano-Scale Optical Circuits: Jeff Kimble, Oskar Painter (CalTech) • Demonstration of a nanofiber atom trap: A. Goban...et al, Phys. Rev. Lett. 109, 033603 (2012) • Cavity QED with atomic mirrors: D. Chang, et al, N. J. Phys. 14, 063003 (2012) • Fiber -coupled chip... PMMA -diamond hybrid cavities, coupling stable NV centers • Cavity Optomechanics with Cold Atoms: Dan Stamper-Kurn (UC Berkeley) • Squeezed light

  5. Lasers, Understanding the Atom Series.

    Science.gov (United States)

    Hellman, Hal

    This booklet is one of the booklets in the "Understanding the Atom Series" published by the U. S. Atomic Energy Commission for high school science teachers and their students. Basic information for understanding the laser is provided including discussion of the electromagnetic spectrum, radio waves, light and the atom, coherent light, controlled…

  6. Breaking the atom with Samson

    NARCIS (Netherlands)

    Väänänen, J.; Coecke, B.; Ong, L.; Panangaden, P.

    2013-01-01

    The dependence atom =(x,y) was introduced in [11]. Here x and y are finite sets of attributes (or variables) and the intuitive meaning of =(x,y) is that the attributes x completely (functionally) determine the attributes y. One may wonder, whether the dependence atom is truly an atom or whether it

  7. Current Trends in Atomic Spectroscopy.

    Science.gov (United States)

    Wynne, James J.

    1983-01-01

    Atomic spectroscopy is the study of atoms/ions through their interaction with electromagnetic radiation, in particular, interactions in which radiation is absorbed or emitted with an internal rearrangement of the atom's electrons. Discusses nature of this field, its status and future, and how it is applied to other areas of physics. (JN)

  8. Bohmian picture of Rydberg atoms

    Indian Academy of Sciences (India)

    lished the nearly elliptical shapes for the centre-of-mass motion in Rydberg atoms using numerical simulations, we show analytically that the Bohmian trajectories in Rydberg atoms are nearly ellipti- cal. Keywords. Rydberg atom; quantum trajectory. PACS No. 03.65.Ge. 1. Introduction. Ever since the advent of quantum ...

  9. Cold atoms close to surfaces

    DEFF Research Database (Denmark)

    Krüger, Peter; Wildermuth, Stephan; Hofferberth, Sebastian

    2005-01-01

    Microscopic atom optical devices integrated on atom chips allow to precisely control and manipulate ultra-cold (T atoms and Bose-Einstein condensates (BECs) close to surfaces. The relevant energy scale of a BEC is extremely small (down to ... be utilized as a sensor for variations of the potential energy of the atoms close to the surface. Here we describe how to use trapped atoms as a measurement device and analyze the performance and flexibility of the field sensor. We demonstrate microscopic magnetic imaging with simultaneous high spatial...

  10. Topics in atomic collision theory

    CERN Document Server

    Geltman, Sydney; Brueckner, Keith A

    1969-01-01

    Topics in Atomic Collision Theory originated in a course of graduate lectures given at the University of Colorado and at University College in London. It is recommended for students in physics and related fields who are interested in the application of quantum scattering theory to low-energy atomic collision phenomena. No attention is given to the electromagnetic, nuclear, or elementary particle domains. The book is organized into three parts: static field scattering, electron-atom collisions, and atom-atom collisions. These are in the order of increasing physical complexity and hence necessar

  11. Cavity QED with atomic mirrors

    Science.gov (United States)

    Chang, D. E.; Jiang, L.; Gorshkov, A. V.; Kimble, H. J.

    2012-06-01

    A promising approach to merge atomic systems with scalable photonics has emerged recently, which consists of trapping cold atoms near tapered nanofibers. Here, we describe a novel technique to achieve strong, coherent coupling between a single atom and photon in such a system. Our approach makes use of collective enhancement effects, which allow a lattice of atoms to form a high-finesse cavity within the fiber. We show that a specially designated ‘impurity’ atom within the cavity can experience strongly enhanced interactions with single photons in the fiber. Under realistic conditions, a ‘strong coupling’ regime can be reached, wherein it becomes feasible to observe vacuum Rabi oscillations between the excited impurity atom and a single cavity quantum. This technique can form the basis for a scalable quantum information network using atom-nanofiber systems.

  12. Chameleon Induced Atomic Afterglow

    CERN Document Server

    Brax, Philippe

    2010-01-01

    The chameleon is a scalar field whose mass depends on the density of its environment. Chameleons are necessarily coupled to matter particles and will excite transitions between atomic energy levels in an analogous manner to photons. When created inside an optical cavity by passing a laser beam through a constant magnetic field, chameleons are trapped between the cavity walls and form a standing wave. This effect will lead to an afterglow phenomenon even when the laser beam and the magnetic field have been turned off, and could be used to probe the interactions of the chameleon field with matter.

  13. Atomic mechanics of solids

    CERN Document Server

    MacPherson, A K

    1990-01-01

    This volume brings together some of the presently available theoretical techniques which will be useful in the design of solid-state materials. At present, it is impossible to specify the atomic composition of a material and its macroscopic physical properties. However, the future possibilities for such a science are being laid today. This is coming about due to the development of fast, cheap computers which will be able to undertake the calculations which are necessary.Since this field of science is fairly new, it is not yet quite clear which direction of analysis will eventually prov

  14. Electroless atomic layer deposition

    Energy Technology Data Exchange (ETDEWEB)

    Robinson, David Bruce; Cappillino, Patrick J.; Sheridan, Leah B.; Stickney, John L.; Benson, David M.

    2017-10-31

    A method of electroless atomic layer deposition is described. The method electrolessly generates a layer of sacrificial material on a surface of a first material. The method adds doses of a solution of a second material to the substrate. The method performs a galvanic exchange reaction to oxidize away the layer of the sacrificial material and deposit a layer of the second material on the surface of the first material. The method can be repeated for a plurality of iterations in order to deposit a desired thickness of the second material on the surface of the first material.

  15. Atomic data for fusion

    Energy Technology Data Exchange (ETDEWEB)

    Hunter, H.T.; Kirkpatrick, M.I.; Alvarez, I.; Cisneros, C.; Phaneuf, R.A. (eds.); Barnett, C.F.

    1990-07-01

    This report provides a handbook of recommended cross-section and rate-coefficient data for inelastic collisions between hydrogen, helium and lithium atoms, molecules and ions, and encompasses more than 400 different reactions of primary interest in fusion research. Published experimental and theoretical data have been collected and evaluated, and the recommended data are presented in tabular, graphical and parametrized form. Processes include excitation and spectral line emission, charge exchange, ionization, stripping, dissociation and particle interchange reactions. The range of collision energies is appropriate to applications in fusion-energy research.

  16. Neuromorphic atomic switch networks.

    Directory of Open Access Journals (Sweden)

    Audrius V Avizienis

    Full Text Available Efforts to emulate the formidable information processing capabilities of the brain through neuromorphic engineering have been bolstered by recent progress in the fabrication of nonlinear, nanoscale circuit elements that exhibit synapse-like operational characteristics. However, conventional fabrication techniques are unable to efficiently generate structures with the highly complex interconnectivity found in biological neuronal networks. Here we demonstrate the physical realization of a self-assembled neuromorphic device which implements basic concepts of systems neuroscience through a hardware-based platform comprised of over a billion interconnected atomic-switch inorganic synapses embedded in a complex network of silver nanowires. Observations of network activation and passive harmonic generation demonstrate a collective response to input stimulus in agreement with recent theoretical predictions. Further, emergent behaviors unique to the complex network of atomic switches and akin to brain function are observed, namely spatially distributed memory, recurrent dynamics and the activation of feedforward subnetworks. These devices display the functional characteristics required for implementing unconventional, biologically and neurally inspired computational methodologies in a synthetic experimental system.

  17. Delay in atomic photoionization

    CERN Document Server

    Kheifets, A S

    2010-01-01

    We analyze the time delay between emission of photoelectrons from the outer valence $ns$ and $np$ sub-shells in noble gas atoms following absorption of an attosecond XUV pulse. By solving the time dependent Schr\\"odinger equation and carefully examining the time evolution of the photoelectron wave packet, we establish the apparent "time zero" when the photoelectron leaves the atom. Various processes such as elastic scattering of the photoelectron on the parent ion and many-electron correlation affect the quantum phase of the dipole transition matrix element, the energy dependence of which defines the emission timing. This qualitatively explains the time delay between photoemission from the $2s$ and $2p$ sub-shells of Ne as determined experimentally by attosecond streaking [{\\em Science} {\\bf 328}, 1658 (2010)]. However, with our extensive numerical modeling, we were only able to account for less than a half of the measured time delay of $21\\pm5$~as. We argue that the XUV pulse alone cannot produce such a larg...

  18. Recognizing nitrogen dopant atoms in graphene using atomic force microscopy

    DEFF Research Database (Denmark)

    van der Heijden, Nadine J.; Smith, Daniel; Calogero, Gaetano

    2016-01-01

    Doping graphene by heteroatoms such as nitrogen presents an attractive route to control the position of the Fermi level in the material. We prepared N-doped graphene on Cu(111) and Ir(111) surfaces via chemical vapor deposition of two different molecules. Using scanning tunneling microscopy images...... as a benchmark, we show that the position of the dopant atoms can be determined using atomic force microscopy. Specifically, the frequency shift-distance curves Delta f(z) acquired above a N atom are significantly different from the curves measured over a C atom. Similar behavior was found for N-doped graphene...

  19. Can atom-surface potential measurements test atomic structure models?

    Science.gov (United States)

    Lonij, Vincent P A; Klauss, Catherine E; Holmgren, William F; Cronin, Alexander D

    2011-06-30

    van der Waals (vdW) atom-surface potentials can be excellent benchmarks for atomic structure calculations. This is especially true if measurements are made with two different types of atoms interacting with the same surface sample. Here we show theoretically how ratios of vdW potential strengths (e.g., C₃(K)/C₃(Na)) depend sensitively on the properties of each atom, yet these ratios are relatively insensitive to properties of the surface. We discuss how C₃ ratios depend on atomic core electrons by using a two-oscillator model to represent the contribution from atomic valence electrons and core electrons separately. We explain why certain pairs of atoms are preferable to study for future experimental tests of atomic structure calculations. A well chosen pair of atoms (e.g., K and Na) will have a C₃ ratio that is insensitive to the permittivity of the surface, whereas a poorly chosen pair (e.g., K and He) will have a ratio of C₃ values that depends more strongly on the permittivity of the surface.

  20. Optical angular momentum and atoms.

    Science.gov (United States)

    Franke-Arnold, Sonja

    2017-02-28

    Any coherent interaction of light and atoms needs to conserve energy, linear momentum and angular momentum. What happens to an atom's angular momentum if it encounters light that carries orbital angular momentum (OAM)? This is a particularly intriguing question as the angular momentum of atoms is quantized, incorporating the intrinsic spin angular momentum of the individual electrons as well as the OAM associated with their spatial distribution. In addition, a mechanical angular momentum can arise from the rotation of the entire atom, which for very cold atoms is also quantized. Atoms therefore allow us to probe and access the quantum properties of light's OAM, aiding our fundamental understanding of light-matter interactions, and moreover, allowing us to construct OAM-based applications, including quantum memories, frequency converters for shaped light and OAM-based sensors.This article is part of the themed issue 'Optical orbital angular momentum'. © 2017 The Author(s).

  1. Optical nanofibres and neutral atoms

    CERN Document Server

    Nieddu, Thomas; Chormaic, Sile Nic

    2015-01-01

    Optical nanofibres are increasingly being used in cold atom experiments due to their versatility and the clear advantages they have when developing all-fibred systems for quantum technologies. They provide researchers with a method of overcoming the Rayleigh range for achieving high intensities in a focussed beam over a relatively long distance, and can act as a noninvasive tool for probing cold atoms. In this review article, we will briefly introduce the theory of mode propagation in an ultrathin optical fibre and highlight some of the more significant theoretical and experimental progresses to date, including the early work on atom probing, manipulation and trapping, the study of atom-dielectric surface interactions, and the more recent observation of nanofibre-mediated nonlinear optics phenomena in atomic media. The functionality of optical nanofibres in relation to the realisation of atom-photon hybrid quantum systems is also becoming more evident as some of the earlier technical challenges are surpassed ...

  2. Atomic iodine laser

    Energy Technology Data Exchange (ETDEWEB)

    Fisk, G.A.; Gusinow, M.A.; Hays, A.K.; Padrick, T.D.; Palmer, R.E.; Rice, J.K.; Truby, F.K.; Riley, M.E.

    1978-05-01

    The atomic iodine photodissociation laser has been under intensive study for a number of years. The physics associated with this system is now well understood and it is possible to produce a 0.1 nsec (or longer) near-diffraction-limited laser pulse which can be amplified with negligible temporal distortion and little spatial deformation. The output of either a saturated or unsaturated amplifier consists of a high-fidelity near-diffraction-limited, energetic laser pulse. The report is divided into three chapters. Chapter 1 is a survey of the important areas affecting efficient laser operation and summarizes the findings of Chap. 2. Chapter 2 presents detailed discussions and evaluations pertinent to pumps, chemical regeneration, and other elements in the overall laser system. Chapter 3 briefly discusses those areas that require further work and the nature of the work required to complete the full-scale evaluation of the applicability of the iodine photodissociation laser to the inertial confinement program.

  3. Quantum information with Rydberg atoms

    DEFF Research Database (Denmark)

    Saffman, Mark; Walker, T.G.; Mølmer, Klaus

    2010-01-01

    Rydberg atoms with principal quantum number n»1 have exaggerated atomic properties including dipole-dipole interactions that scale as n4 and radiative lifetimes that scale as n3. It was proposed a decade ago to take advantage of these properties to implement quantum gates between neutral atom...... of multiqubit registers, implementation of robust light-atom quantum interfaces, and the potential for simulating quantum many-body physics. The advances of the last decade are reviewed, covering both theoretical and experimental aspects of Rydberg-mediated quantum information processing....

  4. HPAM: Hirshfeld partitioned atomic multipoles

    Science.gov (United States)

    Elking, Dennis M.; Perera, Lalith; Pedersen, Lee G.

    2012-02-01

    An implementation of the Hirshfeld (HD) and Hirshfeld-Iterated (HD-I) atomic charge density partitioning schemes is described. Atomic charges and atomic multipoles are calculated from the HD and HD-I atomic charge densities for arbitrary atomic multipole rank l on molecules of arbitrary shape and size. The HD and HD-I atomic charges/multipoles are tested by comparing molecular multipole moments and the electrostatic potential (ESP) surrounding a molecule with their reference ab initio values. In general, the HD-I atomic charges/multipoles are found to better reproduce ab initio electrostatic properties over HD atomic charges/multipoles. A systematic increase in precision for reproducing ab initio electrostatic properties is demonstrated by increasing the atomic multipole rank from l=0 (atomic charges) to l=4 (atomic hexadecapoles). Both HD and HD-I atomic multipoles up to rank l are shown to exactly reproduce ab initio molecular multipole moments of rank L for L⩽l. In addition, molecular dipole moments calculated by HD, HD-I, and ChelpG atomic charges only ( l=0) are compared with reference ab initio values. Significant errors in reproducing ab initio molecular dipole moments are found if only HD or HD-I atomic charges used. Program summaryProgram title: HPAM Catalogue identifier: AEKP_v1_0 Program summary URL:http://cpc.cs.qub.ac.uk/summaries/AEKP_v1_0.html Program obtainable from: CPC Program Library, Queen's University, Belfast, N. Ireland Licensing provisions: GNU General Public License v2 No. of lines in distributed program, including test data, etc.: 500 809 No. of bytes in distributed program, including test data, etc.: 13 424 494 Distribution format: tar.gz Programming language: C Computer: Any Operating system: Linux RAM: Typically, a few hundred megabytes Classification: 16.13 External routines: The program requires 'formatted checkpoint' files obtained from the Gaussian 03 or Gaussian 09 quantum chemistry program. Nature of problem: An ab initio

  5. Linear Atom Guides: Guiding Rydberg Atoms and Progress Toward an Atom Laser

    Science.gov (United States)

    Traxler, Mallory A.

    In this thesis, I explore a variety of experiments within linear, two-wire, magnetic atom guides. Experiments include guiding of Rydberg atoms; transferring between states while keeping the atoms contained within the guide; and designing, constructing, and testing a new experimental apparatus. The ultimate goal of the atom guiding experiments is to develop a continuous atom laser. The guiding of 87Rb 59D5/2 Rydberg atoms is demonstrated. The evolution of the atoms is driven by the combined effects of dipole forces acting on the center-of-mass degree of freedom as well as internal-state transitions. Time delayed microwave and state-selective field ionization, along with ion detection, are used to investigate the evolution of the internal-state distribution as well as the Rydberg atom motion while traversing the guide. The observed decay time of the guided-atom signal is about five times that of the initial state. A population transfer between Rydberg states contributes to this lengthened lifetime, and also broadens the observed field ionization spectrum. The population transfer is attributed to thermal transitions and, to a lesser extent, initial state-mixing due to Rydberg-Rydberg collisions. Characteristic signatures in ion time-of-flight signals and spatially resolved images of ion distributions, which result from the coupled internal-state and center-of-mass dynamics, are discussed. Some groups have used a scheme to make BECs where atoms are optically pumped from one reservoir trap to a final state trap, irreversibly transferring those atoms from one trap to the other. In this context, transfer from one guided ground state to another is studied. In our setup, before the atoms enter the guide, they are pumped into the | F = 1, mF = --1> state. Using two repumpers, one tuned to the F = 1 → F' = 0 transition (R10) and the other tuned to the F = 1 → F' = 2 transition (R12), the atoms are pumped between these guided states. Magnetic reflections within the guide

  6. Introduction to light forces, atom cooling, and atom trapping

    OpenAIRE

    Savage, Craig

    1995-01-01

    This paper introduces and reviews light forces, atom cooling and atom trapping. The emphasis is on the physics of the basic processes. In discussing conservative forces the semi-classical dressed states are used rather than the usual quantized field dressed states.

  7. Atomic Force Microscopy and Real Atomic Resolution. Simple Computer Simulations

    NARCIS (Netherlands)

    Koutsos, V.; Manias, E.; Brinke, G. ten; Hadziioannou, G.

    1994-01-01

    Using a simple computer simulation for AFM imaging in the contact mode, pictures with true and false atomic resolution are demonstrated. The surface probed consists of two f.c.c. (111) planes and an atomic vacancy is introduced in the upper layer. Changing the size of the effective tip and its

  8. Intermolecular atom-atom bonds in crystals - a chemical perspective.

    Science.gov (United States)

    Thakur, Tejender S; Dubey, Ritesh; Desiraju, Gautam R

    2015-03-01

    Short atom-atom distances between molecules are almost always indicative of specific intermolecular bonding. These distances may be used to assess the significance of all hydrogen bonds, including the C-H⋯O and even weaker C-H⋯F varieties.

  9. Atom-surface studies with Rb Rydberg atoms

    Science.gov (United States)

    Chao, Yuanxi; Sheng, Jiteng; Sedlacek, Jonathon; Shaffer, James

    2015-05-01

    We report on experimental and theoretical progress studying atom-surface interactions using rubidium Rydberg atoms. Rydberg atoms can be strongly coupled to surface phonon polariton (SPhP) modes of a dielectric material. The coherent interaction between Rydberg atoms and SPhPs has potential applications for quantum hybrid devices. Calculations of TM-mode SPhPs on engineered surfaces of periodically poled lithium niobate (PPLN) and lithium tantalate (PPLT) for different periodic domains and surface orientations, as well as natural materials such as quartz, are presented. Our SPhP calculations account for the semi-infinite anisotropic nature of the materials. In addition to theoretical calculations, we show experimental results of measurements of adsorbate fields and coupling of Rydberg atoms to SPhPs on quartz.

  10. Coherent Atom Optics with fast metastable rare gas atoms

    Science.gov (United States)

    Grucker, J.; Baudon, J.; Karam, J.-C.; Perales, F.; Bocvarski, V.; Vassilev, G.; Ducloy, M.

    2006-12-01

    Coherent atom optics experiments making use of an ultra-narrow beam of fast metastable atoms generated by metastability exchange are reported. The transverse coherence of the beam (coherence radius of 1.7 μm for He*, 1.2 μm for Ne*, 0.87 μm for Ar*) is demonstrated via the atomic diffraction by a non-magnetic 2μm-period reflection grating. The combination of the non-scalar van der Waals (vdW) interaction with the Zeeman interaction generated by a static magnetic field gives rise to "vdW-Zeeman" transitions among Zeeman sub-levels. Exo-energetic transitions of this type are observed with Ne*(3P2) atoms traversing a copper micro-slit grating. They can be used as a tunable beam splitter in an inelastic Fresnel bi-prism atom interferometer.

  11. Traps for neutral radioactive atoms

    CERN Document Server

    Sprouse, G D; Grossman, J S; Orozco, L A; Pearson, M R

    2002-01-01

    We describe several methods for efficiently injecting a small number of radioactive atoms into a laser trap. The characteristics of laser traps that make them desirable for physics experiments are discussed and several different experimental directions are described. We describe recent experiments with the alkali element Fr and point to future directions of the neutral atom trapping program.

  12. The Stair-Step Atom.

    Science.gov (United States)

    Jordan, Thomas M.; And Others

    1992-01-01

    Presents a model of a generic atom that is used to represent the movement of electrons from lower to higher levels and vice-versa due to excitation and de-excitation of the atom. As the process of de-excitation takes place, photons represented by colored ping-pong balls are emitted, indicating the emission of light. (MDH)

  13. Atomic collisions involving pulsed positrons

    DEFF Research Database (Denmark)

    Merrison, J. P.; Bluhme, H.; Field, D.

    2000-01-01

    instantaneous intensities be achieved with in-beam accumulation, but more importantly many orders of magnitude improvement in energy and spatial resolution can be achieved using positron cooling. Atomic collisions can be studied on a new energy scale with unprecedented precion and control. The use...... of accelerators for producing intense positron pulses will be discussed in the context of atomic physics experiments....

  14. Bohmian picture of Rydberg atoms

    Indian Academy of Sciences (India)

    Abstract. Unlike the previous theoretical results based on standard quantum mechanics that established the nearly elliptical shapes for the centre-of-mass motion in Rydberg atoms using numerical simulations, we show analytically that the Bohmian trajectories in Rydberg atoms are nearly elliptical.

  15. Atoms in astrophysics

    CERN Document Server

    Eissner, W; Hummer, D; Percival, I

    1983-01-01

    It is hard to appreciate but nevertheless true that Michael John Seaton, known internationally for the enthusiasm and skill with which he pursues his research in atomic physics and astrophysics, will be sixty years old on the 16th of January 1983. To mark this occasion some of his colleagues and former students have prepared this volume. It contains articles that de­ scribe some of the topics that have attracted his attention since he first started his research work at University College London so many years ago. Seaton's association with University College London has now stretched over a period of some 37 years, first as an undergraduate student, then as a research student, and then, successively, as Assistant Lecturer, Lecturer, Reader, and Professor. Seaton arrived at University College London in 1946 to become an undergraduate in the Physics Department, having just left the Royal Air Force in which he had served as a navigator in the Pathfinder Force of Bomber Command. There are a number of stories of ho...

  16. Deep atomic force microscopy

    Energy Technology Data Exchange (ETDEWEB)

    Barnard, H.; Drake, B.; Randall, C.; Hansma, P. K. [Department of Physics, University of California, Santa Barbara, California 93106 (United States)

    2013-12-15

    The Atomic Force Microscope (AFM) possesses several desirable imaging features including the ability to produce height profiles as well as two-dimensional images, in fluid or air, at high resolution. AFM has been used to study a vast selection of samples on the scale of angstroms to micrometers. However, current AFMs cannot access samples with vertical topography of the order of 100 μm or greater. Research efforts have produced AFM scanners capable of vertical motion greater than 100 μm, but commercially available probe tip lengths are still typically less than 10 μm high. Even the longest probe tips are below 100 μm and even at this range are problematic. In this paper, we present a method to hand-fabricate “Deep AFM” probes with tips of the order of 100 μm and longer so that AFM can be used to image samples with large scale vertical topography, such as fractured bone samples.

  17. Atom mapping with constraint programming.

    Science.gov (United States)

    Mann, Martin; Nahar, Feras; Schnorr, Norah; Backofen, Rolf; Stadler, Peter F; Flamm, Christoph

    2014-01-01

    Chemical reactions are rearrangements of chemical bonds. Each atom in an educt molecule thus appears again in a specific position of one of the reaction products. This bijection between educt and product atoms is not reported by chemical reaction databases, however, so that the "Atom Mapping Problem" of finding this bijection is left as an important computational task for many practical applications in computational chemistry and systems biology. Elementary chemical reactions feature a cyclic imaginary transition state (ITS) that imposes additional restrictions on the bijection between educt and product atoms that are not taken into account by previous approaches. We demonstrate that Constraint Programming is well-suited to solving the Atom Mapping Problem in this setting. The performance of our approach is evaluated for a manually curated subset of chemical reactions from the KEGG database featuring various ITS cycle layouts and reaction mechanisms.

  18. Exotic objects of atomic physics

    Science.gov (United States)

    Eletskii, A. V.

    2017-11-01

    There has been presented a short survey of physical properties, methods of production and exploration as well as directions of practical usage of the objects of atomic physics which are not yet described in detail in modern textbooks and manuals intended for students of technical universities. The family of these objects includes negative and multicharged ions, Rydberg atoms, excimer molecules, clusters. Besides of that, in recent decades this family was supplemented with new nanocarbon structures such as fullerenes, carbon nanotubes and graphene. The textbook “Exotic objects of atomic physics” [1] edited recently contains some information on the above-listed objects of the atomic physics. This textbook can be considered as a supplement to classic courses of atomic physics teaching in technical universities.

  19. Atomic spectroscopy and radiative processes

    CERN Document Server

    Landi Degl'Innocenti, Egidio

    2014-01-01

    This book describes the basic physical principles of atomic spectroscopy and the absorption and emission of radiation in astrophysical and laboratory plasmas. It summarizes the basics of electromagnetism and thermodynamics and then describes in detail the theory of atomic spectra for complex atoms, with emphasis on astrophysical applications. Both equilibrium and non-equilibrium phenomena in plasmas are considered. The interaction between radiation and matter is described, together with various types of radiation (e.g., cyclotron, synchrotron, bremsstrahlung, Compton). The basic theory of polarization is explained, as is the theory of radiative transfer for astrophysical applications. Atomic Spectroscopy and Radiative Processes bridges the gap between basic books on atomic spectroscopy and the very specialized publications for the advanced researcher: it will provide under- and postgraduates with a clear in-depth description of theoretical aspects, supported by practical examples of applications.

  20. Atomic form factor for twisted vortex photons interacting with atoms

    Science.gov (United States)

    Guthrey, Pierson; Kaplan, Lev; McGuire, J. H.

    2014-04-01

    The relatively new atomic form factor for twisted (vortex) beams, which carry orbital angular momentum (OAM), is considered and compared to the conventional atomic form factor for plane-wave beams that carry only spin angular momentum. Since the vortex symmetry of a twisted photon is more complex that that of a plane wave, evaluation of the atomic form factor is also more complex for twisted photons. On the other hand, the twisted photon has additional parameters, including the OAM quantum number, ℓ, the nodal radial number, p, and the Rayleigh range, zR, which determine the cone angle of the vortex. This Rayleigh range may be used as a variable parameter to control the interaction of twisted photons with matter. Here we address (i) normalization of the vortex atomic form factor, (ii) displacement of target atoms away from the center of the beam vortex, and (iii) formulation of transition probabilities for a variety of photon-atom processes. We attend to features related to experiments that can test the range of validity and accuracy of calculations of these variations of the atomic form factor. Using the absolute square of the form factor for vortex beams, we introduce a vortex factor that can be directly measured.

  1. Atomic Configuration and Conductance of Tantalum Single-Atom Contacts and Single-Atom Wires

    Science.gov (United States)

    Kizuka, Tokushi; Murata, Satoshi

    2017-09-01

    The tensile deformation and successive fracture process of tantalum (Ta) nanocontacts (NCs) while applying various bias voltages was observed in situ by high-resolution transmission electron microscopy using a picometer-precision dual-goniometer nanotip manipulation technique. Simultaneously, the variation in the conductance of the contacts was measured. The NCs were thinned atom by atom during mechanical elongation, resulting in the formation of two types of single-atom cross-sectional contacts: single-atom contacts (SACs) and single-atom wires (SAWs), in which two electrodes, typically nanotips, are connected by a single shared atom or a one-line array of single atoms, respectively. When the bias voltage was 11 mV, Ta SACs were formed during tensile deformation; however, elongation of the single-atom cross-sectional part did not occur. In contrast, when the bias voltage was increased to 200 mV, Ta SACs were first formed during the tensile deformation, followed by elongation of the single-atom cross section up to a length of three atoms, i.e., the formation of SAWs. Thus, the present observation shows that Ta SAWs are stable even at such a high bias voltage. The conductance of the SACs was approximately 0.10G0 (G0 = 2e2/h, where e is the electron charge and h is Planck’s constant), whereas the conductance of the three-atom-long SAWs ranged from 0.01G0 to 0.22G0. Lower conductances were observed for linear SAWs, whereas higher conductances resulted from kinked SAWs.

  2. Optically polarized atoms understanding light-atom interactions

    CERN Document Server

    Auzinsh, Marcis; Rochester, Simon M

    2010-01-01

    This book is addressed at upper-level undergraduate and graduate students involved in research in atomic, molecular, and optical Physics. It will also be useful to researchers practising in this field. It gives an intuitive, yet sufficiently detailed and rigorous introduction to light-atom interactions with a particular emphasis on the symmetry aspects of the interaction, especially those associated with the angular momentum of atoms and light. The book will enable readers to carryout practical calculations on their own, and is richly illustrated with examples drawn from current research topic

  3. Atoms, Light, and Lasers

    Science.gov (United States)

    Bellac, Michel Le

    2014-11-01

    Up to now, the spatial properties of quantum particles played no more than a secondary role: we only needed the de Broglie relation (1.4) which gives the quantum particles wavelength, and our discussion of the quantum properties of photons was based mainly on their polarization, which is an internal degree of freedom of the photon. The probability amplitudes which we used did not involve the positions or velocities of the particles, which are spatial, or external degrees of freedom. In the present chapter, we shall introduce spatial dependence by defining probability amplitudes a(ěc r) that are functions of the position ěc r. In full generality, a(ěc r) is a complex number, but we shall avoid this complication and discuss only cases where the probability amplitudes may be taken real. For simplicity, we also limit ourselves to particles propagating along a straight line, which we take as the Ox axis: x will define the position of the particle and the corresponding probability amplitude will be a function of x, a(x). In our discussion, we shall need to introduce the so-called potential well, where a particle travels back and forth between two points on the straight line. One important particular case is the infinite well, where the particle is confined between two infinitely high walls over which it cannot pass. This example is not at all academic, and we shall meet it again in Chapter 6 when explaining the design of a laser diode! Furthermore, it will allow us to introduce the notion of energy level, to write down the Heisenberg inequalities, to understand the interaction of a light wave with an atom and finally to explain schematically the principles of the laser.

  4. Electronic structure of atoms: atomic spectroscopy information system

    Science.gov (United States)

    Kazakov, V. V.; Kazakov, V. G.; Kovalev, V. S.; Meshkov, O. I.; Yatsenko, A. S.

    2017-10-01

    The article presents a Russian atomic spectroscopy, information system electronic structure of atoms (IS ESA) (http://grotrian.nsu.ru), and describes its main features and options to support research and training. The database contains over 234 000 records, great attention paid to experimental data and uniform filling of the database for all atomic numbers Z, including classified levels and transitions of rare earth and transuranic elements and their ions. Original means of visualization of scientific data in the form of spectrograms and Grotrian diagrams have been proposed. Presentation of spectral data in the form of interactive color charts facilitates understanding and analysis of properties of atomic systems. The use of the spectral data of the IS ESA together with its functionality is effective for solving various scientific problems and training of specialists.

  5. Quantum Electronics for Atomic Physics

    CERN Document Server

    Nagourney, Warren

    2010-01-01

    Quantum Electronics for Atomic Physics provides a course in quantum electronics for researchers in atomic physics. The book covers the usual topics, such as Gaussian beams, cavities, lasers, nonlinear optics and modulation techniques, but also includes a number of areas not usually found in a textbook on quantum electronics. It includes such practical matters as the enhancement of nonlinear processes in a build-up cavity, impedance matching into a cavity, laser frequencystabilization (including servomechanism theory), astigmatism in ring cavities, and atomic/molecular spectroscopic techniques

  6. Fundamentals in hadronic atom theory

    CERN Document Server

    Deloff, A

    2003-01-01

    Hadronic atoms provide a unique laboratory for studying hadronic interactions essentially at threshold. This text is the first book-form exposition of hadronic atom theory with emphasis on recent developments, both theoretical and experimental. Since the underlying Hamiltonian is a non-self-adjoined operator, the theory goes beyond traditional quantum mechanics and this book covers topics that are often glossed over in standard texts on nuclear physics. The material contained here is intended for the advanced student and researcher in nuclear, atomic or elementary-particle physics. A good know

  7. AtomPy: an open atomic-data curation environment

    Science.gov (United States)

    Bautista, Manuel; Mendoza, Claudio; Boswell, Josiah S; Ajoku, Chukwuemeka

    2014-06-01

    We present a cloud-computing environment for atomic data curation, networking among atomic data providers and users, teaching-and-learning, and interfacing with spectral modeling software. The system is based on Google-Drive Sheets, Pandas (Python Data Analysis Library) DataFrames, and IPython Notebooks for open community-driven curation of atomic data for scientific and technological applications. The atomic model for each ionic species is contained in a multi-sheet Google-Drive workbook, where the atomic parameters from all known public sources are progressively stored. Metadata (provenance, community discussion, etc.) accompanying every entry in the database are stored through Notebooks. Education tools on the physics of atomic processes as well as their relevance to plasma and spectral modeling are based on IPython Notebooks that integrate written material, images, videos, and active computer-tool workflows. Data processing workflows and collaborative software developments are encouraged and managed through the GitHub social network. Relevant issues this platform intends to address are: (i) data quality by allowing open access to both data producers and users in order to attain completeness, accuracy, consistency, provenance and currentness; (ii) comparisons of different datasets to facilitate accuracy assessment; (iii) downloading to local data structures (i.e. Pandas DataFrames) for further manipulation and analysis by prospective users; and (iv) data preservation by avoiding the discard of outdated sets.

  8. Dimer-atom-atom recombination in the universal four-boson system

    OpenAIRE

    Deltuva, A.

    2012-01-01

    The dimer-atom-atom recombination process in the system of four identical bosons with resonant interactions is studied. The description uses the exact Alt, Grassberger and Sandhas equations for the four-particle transition operators that are solved in the momentum-space framework. The dimer-dimer and atom-trimer channel contributions to the ultracold dimer-atom-atom recombination rate are calculated. The dimer-atom-atom recombination rate greatly exceeds the three-atom recombination rate.

  9. Neutral atom traps of radioactives

    CERN Document Server

    Behr, J A

    2003-01-01

    Neutral atoms trapped with modern laser cooling techniques offer the promise of improving several broad classes of experiments with radioactive isotopes. In nuclear beta decay, neutrino spectroscopy from beta-recoil coincidences, along with highly polarized samples, enable experiments to search for non-Standard Model interactions, test whether parity symmetry is maximally violated, and search for new sources of time reversal violation. Ongoing efforts at TRIUMF, Los Alamos and Berkeley will be highlighted. The traps also offer bright sources for Doppler-free spectroscopy, particularly in high-Z atoms where precision measurements could measure the strength of weak neutral nucleon-nucleon and electron-nucleon interactions. Physics with francium atoms has been vigorously pursued at Stony Brook. Several facilities plan work with radioactive atom traps; concrete plans and efforts at KVI Groningen and Legnaro will be among those summarized. Contributions to the multidisciplinary field of trace analysis will be left...

  10. PubChem atom environments.

    Science.gov (United States)

    Hähnke, Volker D; Bolton, Evan E; Bryant, Stephen H

    2015-01-01

    Atom environments and fragments find wide-spread use in chemical information and cheminformatics. They are the basis of prediction models, an integral part in similarity searching, and employed in structure search techniques. Most of these methods were developed and evaluated on the relatively small sets of chemical structures available at the time. An analysis of fragment distributions representative of most known chemical structures was published in the 1970s using the Chemical Abstracts Service data system. More recently, advances in automated synthesis of chemicals allow millions of chemicals to be synthesized by a single organization. In addition, open chemical databases are readily available containing tens of millions of chemical structures from a multitude of data sources, including chemical vendors, patents, and the scientific literature, making it possible for scientists to readily access most known chemical structures. With this availability of information, one can now address interesting questions, such as: what chemical fragments are known today? How do these fragments compare to earlier studies? How unique are chemical fragments found in chemical structures? For our analysis, after hydrogen suppression, atoms were characterized by atomic number, formal charge, implicit hydrogen count, explicit degree (number of neighbors), valence (bond order sum), and aromaticity. Bonds were differentiated as single, double, triple or aromatic bonds. Atom environments were created in a circular manner focused on a central atom with radii from 0 (atom types) up to 3 (representative of ECFP_6 fragments). In total, combining atom types and atom environments that include up to three spheres of nearest neighbors, our investigation identified 28,462,319 unique fragments in the 46 million structures found in the PubChem Compound database as of January 2013. We could identify several factors inflating the number of environments involving transition metals, with many

  11. Atomic layer deposition for semiconductors

    CERN Document Server

    Hwang, Cheol Seong

    2014-01-01

    This edited volume discusses atomic layer deposition (ALD) for all modern semiconductor devices, moving from the basic chemistry of ALD and modeling of ALD processes to sections on ALD for memories, logic devices, and machines.

  12. Rydberg atoms: Two to tango

    Science.gov (United States)

    Löw, Robert

    2014-12-01

    The old adage that you can't tango alone is certainly true for humans. But recent experiments show that it may also be applicable to Rydberg atoms, which keep a beat through the coherent exchange of energy.

  13. High-energy atomic physics

    CERN Document Server

    Drukarev, Evgeny G

    2016-01-01

    This self-contained text introduces readers to the field of high-energy atomic physics - a new regime of photon-atom interactions in which the photon energies significantly exceed the atomic or molecular binding energies, and which opened up with the recent advent of new synchrotron sources. From a theoretical point of view, a small-parameter characteristic of the bound system emerged, making it possible to perform analytic perturbative calculations that can in turn serve as benchmarks for more powerful numerical computations. The first part of the book introduces readers to the foundations of this new regime and its theoretical treatment. In particular, the validity of the small-parameter perturbation expansion and of the lowest-order approximation is critically reviewed. The following chapters then apply these insights to various atomic processes, such as photoionization as a many-body problem, dominant mechanisms for the production of ions at higher energies, Compton scattering and ionization accompanied b...

  14. Chain formation of metal atoms

    DEFF Research Database (Denmark)

    Bahn, Sune Rastad; Jacobsen, Karsten Wedel

    2001-01-01

    The possibility of formation of single-atomic chains by manipulation of nanocontacts is studied for a selection of metals (Ni, Pd, Pt, Cu, Ag, Au). Molecular dynamics simulations show that the tendency for chain formation is strongest for Au and Pt. Density functional theory calculations indicate...... that the metals which form chains exhibit pronounced many-atom interactions with strong bonding in low coordinated systems....

  15. Copper atomic-scale transistors

    Directory of Open Access Journals (Sweden)

    Fangqing Xie

    2017-03-01

    Full Text Available We investigated copper as a working material for metallic atomic-scale transistors and confirmed that copper atomic-scale transistors can be fabricated and operated electrochemically in a copper electrolyte (CuSO4 + H2SO4 in bi-distilled water under ambient conditions with three microelectrodes (source, drain and gate. The electrochemical switching-on potential of the atomic-scale transistor is below 350 mV, and the switching-off potential is between 0 and −170 mV. The switching-on current is above 1 μA, which is compatible with semiconductor transistor devices. Both sign and amplitude of the voltage applied across the source and drain electrodes (Ubias influence the switching rate of the transistor and the copper deposition on the electrodes, and correspondingly shift the electrochemical operation potential. The copper atomic-scale transistors can be switched using a function generator without a computer-controlled feedback switching mechanism. The copper atomic-scale transistors, with only one or two atoms at the narrowest constriction, were realized to switch between 0 and 1G0 (G0 = 2e2/h; with e being the electron charge, and h being Planck’s constant or 2G0 by the function generator. The switching rate can reach up to 10 Hz. The copper atomic-scale transistor demonstrates volatile/non-volatile dual functionalities. Such an optimal merging of the logic with memory may open a perspective for processor-in-memory and logic-in-memory architectures, using copper as an alternative working material besides silver for fully metallic atomic-scale transistors.

  16. Rydberg Atom Quantum Hybrid Systems

    Science.gov (United States)

    Chao, Yuanxi; Sheng, Jiteng; Kumar, Santosh; Bigelow, Nicholas P.; Shaffer, James P.

    2017-04-01

    We report on our recent experimental and theoretical work with Rydberg atom-cavity and Rydberg atom-surface hybrid quantum systems. In the atom-cavity system, Rb contained in a dipole trap is transported into a high-finesse optical cavity using a focus-tunable lens. Cavity assisted Rydberg EIT is observed in the cavity transmission and used to characterize the electric fields in the cavity. The electric fields are attributed to surface adsorbates adhering to the cavity mirrors. We also investigate the coupling of a Rydberg atom ensemble to surface phonon polaritons (SPhPs) propagating on piezoelectric superlattices made from thin film ferroelectric materials. Strong coupling between the atomic and surface excitations can be achieved, due to the large Rydberg transition dipole moments and the local field enhancement of the SPhP modes. The system has many advantages for information transport since the atoms need only be placed at distances on the order of mms from the surface and the SPhPs do not couple to free space electro-magnetic fields. Experimental progress will be discussed, including the fabrication of submicron-period periodically poled Lithium Niobate using the direct e-beam writing technique. This work is supported by AFOSR.

  17. Atom-by-Atom Construction of a Quantum Device.

    Science.gov (United States)

    Petta, Jason R

    2017-03-28

    Scanning tunneling microscopes (STMs) are conventionally used to probe surfaces with atomic resolution. Recent advances in STM include tunneling from spin-polarized and superconducting tips, time-domain spectroscopy, and the fabrication of atomically precise Si nanoelectronics. In this issue of ACS Nano, Tettamanzi et al. probe a single-atom transistor in silicon, fabricated using the precision of a STM, at microwave frequencies. While previous studies have probed such devices in the MHz regime, Tettamanzi et al. probe a STM-fabricated device at GHz frequencies, which enables excited-state spectroscopy and measurements of the excited-state lifetime. The success of this experiment will enable future work on quantum control, where the wave function must be controlled on a time scale that is much shorter than the decoherence time. We review two major approaches that are being pursued to develop spin-based quantum computers and highlight some recent progress in the atom-by-atom fabrication of donor-based devices in silicon. Recent advances in STM lithography may enable practical bottom-up construction of large-scale quantum devices.

  18. Atomic-cascade experiment with detection of the recoil atom

    Energy Technology Data Exchange (ETDEWEB)

    Huelga, S.F. (Dept. de Fisica, Univ. de Oviedo (Spain)); Ferrero, M. (Dept. de Fisica, Univ. de Oviedo (Spain)); Santos, E. (Dept. de Fisica Moderna, Univ. de Cantabria (Spain))

    1994-07-20

    Bell's inequalities cannot be violated in atomic-cascade experiments, even with ideal apparatus, due to the three-body character of the atomic decay. Here we propose a new experiment that would block this loophole by means of a suitable selection of an ensemble of photon pairs. A threshold value for the quantum efficiency is found which may allow the discrimination between quantum mechanics and local-hidden-variables theories. Experimental requirements for performing such a test are discussed. (orig.).

  19. Efficient transfer of francium atoms

    Science.gov (United States)

    Aubin, Seth; Behr, John; Gorelov, Alexander; Pearson, Matt; Tandecki, Michael; Collister, Robert; Gwinner, Gerald; Shiells, Kyle; Gomez, Eduardo; Orozco, Luis; Zhang, Jiehang; Zhao, Yanting; FrPNC Collaboration

    2016-05-01

    We report on the progress of the FrPNC collaboration towards Parity Non Conservation Measurements (PNC) using francium atoms at the TRIUMF accelerator. We demonstrate efficient transfer (higher than 40%) to the science vacuum chamber where the PNC measurements will be performed. The transfer uses a downward resonant push beam from the high-efficiency capture magneto optical trap (MOT) towards the science chamber where the atoms are recaptured in a second MOT. The transfer is very robust with respect to variations in the parameters (laser power, detuning, alignment, etc.). We accumulate a growing number of atoms at each transfer pulse (limited by the lifetime of the MOT) since the push beam does not eliminate the atoms already trapped in the science MOT. The number of atoms in the science MOT is on track to meet the requirements for competitive PNC measurements when high francium rates (previously demonstrated) are delivered to our apparatus. The catcher/neutralizer for the ion beam has been tested reliably to 100,000 heating/motion cycles. We present initial tests on the direct microwave excitation of the ground hyperfine transition at 45 GHz. Support from NSERC and NRC from Canada, NSF and Fulbright from USA, and CONACYT from Mexico.

  20. Observation of relativistic antihydrogen atoms

    Energy Technology Data Exchange (ETDEWEB)

    Blanford, Glenn DelFosse

    1998-01-01

    An observation of relativistic antihydrogen atoms is reported in this dissertation. Experiment 862 at Fermi National Accelerator Laboratory observed antihydrogen atoms produced by the interaction of a circulating beam of high momentum (3 < p < 9 GeV/c) antiprotons and a jet of molecular hydrogen gas. Since the neutral antihydrogen does not bend in the antiproton source magnets, the detectors could be located far from the interaction point on a beamline tangent to the storage ring. The detection of the antihydrogen is accomplished by ionizing the atoms far from the interaction point. The positron is deflected by a magnetic spectrometer and detected, as are the back to back photons resulting from its annihilation. The antiproton travels a distance long enough for its momentum and time of flight to be measured accurately. A statistically significant sample of 101 antihydrogen atoms has been observed. A measurement of the cross section for {bar H}{sup 0} production is outlined within. The cross section corresponds to the process where a high momentum antiproton causes e{sup +} e{sup -} pair creation near a nucleus with the e{sup +} being captured by the antiproton. Antihydrogen is the first atom made exclusively of antimatter to be detected. The observation experiment's results are the first step towards an antihydrogen spectroscopy experiment which would measure the n = 2 Lamb shift and fine structure.

  1. Atomic memory access hardware implementations

    Science.gov (United States)

    Ahn, Jung Ho; Erez, Mattan; Dally, William J

    2015-02-17

    Atomic memory access requests are handled using a variety of systems and methods. According to one example method, a data-processing circuit having an address-request generator that issues requests to a common memory implements a method of processing the requests using a memory-access intervention circuit coupled between the generator and the common memory. The method identifies a current atomic-memory access request from a plurality of memory access requests. A data set is stored that corresponds to the current atomic-memory access request in a data storage circuit within the intervention circuit. It is determined whether the current atomic-memory access request corresponds to at least one previously-stored atomic-memory access request. In response to determining correspondence, the current request is implemented by retrieving data from the common memory. The data is modified in response to the current request and at least one other access request in the memory-access intervention circuit.

  2. Laser manipulation of atoms and nanofabrication

    NARCIS (Netherlands)

    Jurdík, Erich

    2001-01-01

    Fundamental interaction processes between atoms and photons are exploited to control external degrees of freedom of the atoms. Laser light, when properly tuned near an atomic resonance, exerts such forces that the atoms are repelled from or attracted to the regions with low light intensities. We use

  3. Trapping fermionic and bosonic helium atoms

    NARCIS (Netherlands)

    Stas, R.J.W.

    2005-01-01

    This thesis presents experimental and theoretical work performed at the Laser Centre of the Vrije Universiteit in Amsterdam to study laser-cooled metastable triplet helium atoms. Samples containing about 3x10^8 helium atoms-either fermionic helium-3 atoms, bosonic helium-4 atoms or mixtures

  4. Cooling Atomic Gases With Disorder

    Science.gov (United States)

    Paiva, Thereza; Khatami, Ehsan; Yang, Shuxiang; Rousseau, Valéry; Jarrell, Mark; Moreno, Juana; Hulet, Randall G.; Scalettar, Richard T.

    2015-12-01

    Cold atomic gases have proven capable of emulating a number of fundamental condensed matter phenomena including Bose-Einstein condensation, the Mott transition, Fulde-Ferrell-Larkin-Ovchinnikov pairing, and the quantum Hall effect. Cooling to a low enough temperature to explore magnetism and exotic superconductivity in lattices of fermionic atoms remains a challenge. We propose a method to produce a low temperature gas by preparing it in a disordered potential and following a constant entropy trajectory to deliver the gas into a nondisordered state which exhibits these incompletely understood phases. We show, using quantum Monte Carlo simulations, that we can approach the Néel temperature of the three-dimensional Hubbard model for experimentally achievable parameters. Recent experimental estimates suggest the randomness required lies in a regime where atom transport and equilibration are still robust.

  5. Quantum tiltmeter with atom interferometry

    Science.gov (United States)

    Xu, Wen-Jie; Zhou, Min-Kang; Zhao, Miao-Miao; Zhang, Ke; Hu, Zhong-Kun

    2017-12-01

    Matter-wave sensors with cold atoms have progressed tremendously over recent decades. We report a sensitive tilt sensor based on quantum technology employing cold atoms. This quantum tiltmeter is constructed with the configuration of a Ramsey-Bordé atom interferometer, achieving an improvement of nearly three orders of magnitude for tilt measurements with a short-term sensitivity of 1.3 μ rad/Hz 1 /2 , with resolution down to 55 nrad at an integration time of 1000 s. The deformation of the Earth's surface has been monitored in a continuous run of 31 h, showing that a quantum tiltmeter can be applied to record tilt tides and can be an valuable sensor in geophysics and various scientific facilities.

  6. Atom-specific surface magnetometry

    Science.gov (United States)

    Sirotti, Fausto; Panaccione, Giancarlo; Rossi, Giorgio

    1995-12-01

    A powerful atom-specific surface magnetometry can be based on efficient measurements of magnetic dichroism in l>~0 core level photoemission. The temperature dependence M(T) of the Fe(100) surface magnetization was obtained from the photoemission magnetic asymmetry of 3p core levels, providing the measure of the surface exchange coupling via the spin-wave stiffness and of the surface critical exponent. Beyond the magnetic order the photoemission dichroism allows us to derive the energy splitting of the magnetic sublevels of the photoexcited core hole. Fe 3p photoemission dichroism probes directly the magnetic moment changes of iron atoms at Fe(100) surfaces as a function of structural disorder or sulfur segregation. The appearance of dichroism in the 2p photoemission of segregated sulfur atoms in the c(2×2)S/Fe(100) superstructure measures the magnetic-moment transfer and shows the possibility of investigating surface magnetochemistry in a very direct way.

  7. Electric field imaging of single atoms

    Science.gov (United States)

    Shibata, Naoya; Seki, Takehito; Sánchez-Santolino, Gabriel; Findlay, Scott D.; Kohno, Yuji; Matsumoto, Takao; Ishikawa, Ryo; Ikuhara, Yuichi

    2017-05-01

    In scanning transmission electron microscopy (STEM), single atoms can be imaged by detecting electrons scattered through high angles using post-specimen, annular-type detectors. Recently, it has been shown that the atomic-scale electric field of both the positive atomic nuclei and the surrounding negative electrons within crystalline materials can be probed by atomic-resolution differential phase contrast STEM. Here we demonstrate the real-space imaging of the (projected) atomic electric field distribution inside single Au atoms, using sub-Å spatial resolution STEM combined with a high-speed segmented detector. We directly visualize that the electric field distribution (blurred by the sub-Å size electron probe) drastically changes within the single Au atom in a shape that relates to the spatial variation of total charge density within the atom. Atomic-resolution electric field mapping with single-atom sensitivity enables us to examine their detailed internal and boundary structures.

  8. Electric field imaging of single atoms

    Science.gov (United States)

    Shibata, Naoya; Seki, Takehito; Sánchez-Santolino, Gabriel; Findlay, Scott D.; Kohno, Yuji; Matsumoto, Takao; Ishikawa, Ryo; Ikuhara, Yuichi

    2017-01-01

    In scanning transmission electron microscopy (STEM), single atoms can be imaged by detecting electrons scattered through high angles using post-specimen, annular-type detectors. Recently, it has been shown that the atomic-scale electric field of both the positive atomic nuclei and the surrounding negative electrons within crystalline materials can be probed by atomic-resolution differential phase contrast STEM. Here we demonstrate the real-space imaging of the (projected) atomic electric field distribution inside single Au atoms, using sub-Å spatial resolution STEM combined with a high-speed segmented detector. We directly visualize that the electric field distribution (blurred by the sub-Å size electron probe) drastically changes within the single Au atom in a shape that relates to the spatial variation of total charge density within the atom. Atomic-resolution electric field mapping with single-atom sensitivity enables us to examine their detailed internal and boundary structures. PMID:28555629

  9. Atomic horror deal; Atom-Deal des Grauens

    Energy Technology Data Exchange (ETDEWEB)

    May, Hanne

    2010-10-15

    The German government is opting out of the decided nuclear phaseout and will ensure good profits for operators of nuclear power plants. Complex contracts and the disregard of safety regulations will result in a continued atomic energy policy, even beyond the next elections and in disrespect of democratic procedures and bodies. (orig.)

  10. Relativistic atomic beam spectroscopy II

    Energy Technology Data Exchange (ETDEWEB)

    NONE

    1989-12-31

    The negative ion of H is one of the simplest 3-body atomic systems. The techniques we have developed for experimental study of atoms moving near speed of light have been productive. This proposal request continuing support for experimental studies of the H{sup -} system, principally at the 800 MeV linear accelerator (LAMPF) at Los Alamos. Four experiments are currently planned: photodetachment of H{sup -} near threshold in electric field, interaction of relativistic H{sup -} ions with matter, high excitations and double charge escape in H{sup -}, and multiphoton detachment of electrons from H{sup -}.

  11. Atoms, Radiation, and Radiation Protection

    CERN Document Server

    Turner, James E

    2007-01-01

    Atoms, Radiation, and Radiation Protection offers professionals and advanced students a comprehensive coverage of the major concepts that underlie the origins and transport of ionizing radiation in matter. Understanding atomic structure and the physical mechanisms of radiation interactions is the foundation on which much of the current practice of radiological health protection is based. The work covers the detection and measurement of radiation and the statistical interpretation of the data. The procedures that are used to protect man and the environment from the potential harmful effects of

  12. Acceleration effects on atomic clocks

    CERN Document Server

    Dahia, F

    2014-01-01

    We consider a free massive particle inside a box which is dragged by Rindler observers. Admitting that the particle obeys the Klein-Gordon equation, we find the frequencies of the stationary states of this system. Transitions between the stationary states are employed to set a standard frequency for a toy atomic clock. Comparing the energy spectrum of the accelerated system with the energy spectrum of an identical system in an inertial frame, we determine the influence of the instantaneous acceleration on the rate of atomic clocks. We argue that our result does not violate the clock hypothesis.

  13. Pathology of atomic bomb casualties.

    Science.gov (United States)

    Iijima, S

    1982-01-01

    Thirty seven years ago, 6 August 1945 marks the date of the first atomic bombing never experienced in human history. It was dropped on Hiroshima and this was followed by a second bombing three days later on Nagasaki. The total deaths following exposure to the bomb by the end of 1945 totalled 140,000 (+/- 10,000) in Hiroshima and 70,000 (+/- 10,000) in Nagasaki. The present article described and outline of the physical effects of the atomic bomb and injury to the human body by exposure to the bomb.

  14. Collective dynamics of accelerated atoms

    Science.gov (United States)

    Richter, Benedikt; Terças, Hugo; Omar, Yasser; de Vega, Inés

    2017-11-01

    We study the collective dynamics of accelerated atoms interacting with a massless field via an Unruh-deWitt-type interaction. We first derive a general Hamiltonian describing such a system and then, employing a Markovian master equation, we study the corresponding collective dynamics. In particular, we observe that the emergence of entanglement between two-level atoms is linked to the building up of coherences between them and to superradiant emission. In addition, we show that the derived Hamiltonian can be experimentally implemented by employing impurities in Bose-Einstein condensates.

  15. Sub-Angstrom Atomic-Resolution Imaging of Heavy Atoms to Light Atoms

    Energy Technology Data Exchange (ETDEWEB)

    O' Keefe, Michael A.; Shao-Horn, Yang

    2003-05-23

    Three decades ago John Cowley and his group at ASU achieved high-resolution electron microscope images showing the crystal unit cell contents at better than 4Angstrom resolution. Over the years, this achievement has inspired improvements in resolution that have enabled researchers to pinpoint the positions of heavy atom columns within the cell. More recently, this ability has been extended to light atoms as resolution has improved. Sub-Angstrom resolution has enabled researchers to image the columns of light atoms (carbon, oxygen and nitrogen) that are present in many complex structures. By using sub-Angstrom focal-series reconstruction of the specimen exit surface wave to image columns of cobalt, oxygen, and lithium atoms in a transition metal oxide structure commonly used as positive electrodes in lithium rechargeable batteries, we show that the range of detectable light atoms extends to lithium. HRTEM at sub-Angstrom resolution will provide the essential role of experimental verification for the emergent nanotech revolution. Our results foreshadow those to be expected from next-generation TEMs with Cs-corrected lenses and monochromated electron beams.

  16. BOOK REVIEW: Computational Atomic Structure

    Science.gov (United States)

    Post, Douglass E.

    1998-02-01

    The primary purpose of `Computational Atomic Structure' is to give a potential user of the Multi-Configuration Hartree-Fock (MCHF) Atomic Structure Package an outline of the physics and computational methods in the package, guidance on how to use the package, and information on how to interpret and use the computational results. The book is successful in all three aspects. In addition, the book provides a good overview and review of the physics of atomic structure that would be useful to the plasma physicist interested in refreshing his knowledge of atomic structure and quantum mechanics. While most of the subjects are covered in greater detail in other sources, the book is reasonably self-contained, and, in most cases, the reader can understand the basic material without recourse to other sources. The MCHF package is the standard package for computing atomic structure and wavefunctions for single or multielectron ions and atoms. It is available from a number of ftp sites. When the code was originally written in FORTRAN 77, it could only be run on large mainframes. With the advances in computer technology, the suite of codes can now be compiled and run on present day workstations and personal computers and is thus available for use by any physicist, even those with extremely modest computing resources. Sample calculations in interactive mode are included in the book to illustrate the input needed for the code, what types of results and information the code can produce, and whether the user has installed the code correctly. The user can also specify the calculational level, from simple Hartree-Fock to multiconfiguration Hartree-Fock. The MCHF method begins by finding approximate wavefunctions for the bound states of an atomic system. This involves minimizing the energy of the bound state using a variational technique. Once the wavefunctions have been determined, other atomic properties, such as the transition rates, can be determined. The book begins with an

  17. Hanbury Brown and Twiss and other atom-atom correlations: advances in quantum atom optics

    CERN Multimedia

    CERN. Geneva

    2008-01-01

    Fifty years ago, two astronomers, R. Hanbury Brown and R. Q. Twiss, invented a new method to measure the angular diameter of stars, in spite of the atmospheric fluctuations. Their proposal prompted a hot debate among physicists : how might two particles (photons), emitted independently (at opposite extremities of a star) , behave in a correlated way when detected ? It was only after the development of R Glauber's full quantum analysis that the effect was understood as a two particle quantum interference effect. From a modern perspective, it can be viewed as an early example of the amazing properties of pairs of entangled particles. The effect has now been observed with bosonic and fermionic atoms, stressing its fully quantum character. After putting these experiments in a historical perspective, I will present recent results, and comment on their significance. I will also show how our single atom detection scheme has allowed us to demonstrate the creation of atom pairs by non linear mixing of matter wa...

  18. Atomic pair-state interferometer

    DEFF Research Database (Denmark)

    Nipper, J.; Balewski, Jonathan B.; Krupp, Alexander T.

    2012-01-01

    We present experiments measuring an interaction-induced phase shift of Rydberg atoms at Stark-tuned Förster resonances. The phase shift features a dispersive shape around the resonance, showing that the interaction strength and sign can be tuned coherently. We use a pair-state interferometer...

  19. Coffee Cup Atomic Force Microscopy

    Science.gov (United States)

    Ashkenaz, David E.; Hall, W. Paige; Haynes, Christy L.; Hicks, Erin M.; McFarland, Adam D.; Sherry, Leif J.; Stuart, Douglas A.; Wheeler, Korin E.; Yonzon, Chanda R.; Zhao, Jing; Godwin, Hilary A.; Van Duyne, Richard P.

    2010-01-01

    In this activity, students use a model created from a coffee cup or cardstock cutout to explore the working principle of an atomic force microscope (AFM). Students manipulate a model of an AFM, using it to examine various objects to retrieve topographic data and then graph and interpret results. The students observe that movement of the AFM…

  20. Atom Wavelike Nature Solved Mathematically

    Science.gov (United States)

    Sven, Charles

    2010-03-01

    Like N/S poles of a magnet the strong force field surrounding, confining the nucleus exerts an equal force [noted by this author] driving electrons away from the attraction of positively charged protons force fields in nucleus -- the mechanics for wavelike nature of electron. Powerful forces corral closely packed protons within atomic nucleus with a force that is at least a million times stronger than proton's electrical attraction that binds electrons. This then accounts for the ease of electron manipulation in that electron is already pushed away by the very strong atomic N/S force field; allowing electrons to drive photons when I strike a match. Ageless atom's electron requirements, used to drive light/photons or atom bomb, without batteries, must be supplied from a huge, external, super high frequency, super-cooled source, undetected by current technology, one that could exist 14+ billion years without degradation -- filling a limitless space prior to Big Bang. Using only replicable physics, I show how our Universe emanated from that event.

  1. Die sonderbare Welt der Atome

    CERN Multimedia

    Greschik, Stefan

    2003-01-01

    Is a Pinhead small? Or a grain of sand? The components of our world are still infinitely much tinier. Come with us in the dimensions, in that of the giant bacteria and even of atoms large like solar systems (3½ pages)

  2. Atomic Configuration of a ½

    NARCIS (Netherlands)

    Hosson, J.Th.M. de; Sleeswyk, A.W.

    1975-01-01

    The atomic arrangement around a ½<111>{110} edge dislocation in an α-Fe crystallite embedded in an elastic continuum is calculated, using the Johnson-I interatomic potential. A narrow dislocation without any stacking fault results, although there is some displacement in the core parallel to the

  3. Spectroscopy, Understanding the Atom Series.

    Science.gov (United States)

    Hellman, Hal

    This booklet is one of the "Understanding the Atom" Series. The science of spectroscopy is presented by a number of topics dealing with (1) the uses of spectroscopy, (2) its origin and background, (3) the basic optical systems of spectroscopes, spectrometers, and spectrophotometers, (4) the characteristics of wave motion, (5) the…

  4. Electrostatics of Atoms and Molecules

    Indian Academy of Sciences (India)

    Home; Journals; Resonance – Journal of Science Education; Volume 7; Issue 2. Electrostatics of Atoms and Molecules. G Narahari Sastry. Book Review Volume 7 Issue 2 February 2002 pp 90-91. Fulltext. Click here to view fulltext PDF. Permanent link: http://www.ias.ac.in/article/fulltext/reso/007/02/0090-0091 ...

  5. Robert Dicke and Atomic Physics

    Indian Academy of Sciences (India)

    Home; Journals; Resonance – Journal of Science Education; Volume 16; Issue 4. Robert Dicke and Atomic Physics. Vasant Natarajan. General Article Volume 16 Issue 4 April 2011 pp 322-332. Fulltext. Click here to view fulltext PDF. Permanent link: http://www.ias.ac.in/article/fulltext/reso/016/04/0322-0332. Keywords.

  6. Magnetism of a single atom

    NARCIS (Netherlands)

    Otte, Alexander Ferdinand

    2008-01-01

    A low-temperature scanning tunneling microscope is used to perform spin-excitations on individual magnetic transition metal atoms when placed onto a crystal surface. By following these excitations while applying external magnetic fields the precise influence of the anisotropic crystal field on the

  7. Atomism from Newton to Dalton.

    Science.gov (United States)

    Schofield, Robert E.

    1981-01-01

    Indicates that although Newton's achievements were rooted in an atomistic theory of matter resembling aspects of modern nuclear physics, Dalton developed his chemical atomism on the basis of the character of the gross behavior of substances rather than their particulate nature. (Author/SK)

  8. Atoms at the Science Fair

    Energy Technology Data Exchange (ETDEWEB)

    LeCompte, Robert G. [AEC Division of Technical Information; Wood, Burrell L. [AEC Division of Special Projects

    1968-01-01

    The United States Atomic Energy Commission has prepared this booklet to help young science fair exhibitors, their science teachers, project counselors, and parents. The booklet suggests some of the numerous nuclear topics on which students can base meaningful science projects. It offers all exhibitors advice on how to plan, design, and construct successful exhibits.

  9. Small amplitude atomic force spectroscopy

    NARCIS (Netherlands)

    de Beer, Sissi; van den Ende, Henricus T.M.; Ebeling, Daniel; Mugele, Friedrich Gunther; Bhushan, Bharat

    2011-01-01

    Over the years atomic force microscopy has developed from a pure imaging technique to a tool that can be employed for measuring quantitative tip–sample interaction forces. In this chapter we provide an overview of various techniques to extract quantitative tip–sample forces focusing on both

  10. LIGAMENT-CONTROLLED EFFERVESCENT ATOMIZATION

    Science.gov (United States)

    The operating principles and performance of a new type of spray nozzle are presented. This nozzle, termed a "ligament-controlled effervescent atomizer," was developed to allow consumer product manufacturers to replace volatile organic compound (VOC) solvents with water and hydroc...

  11. Atomic Power | Taylor | Zede Journal

    African Journals Online (AJOL)

    Zede Journal. Journal Home · ABOUT THIS JOURNAL · Advanced Search · Current Issue · Archives · Journal Home > Vol 3 (1968) >. Log in or Register to get access to full text downloads. Username, Password, Remember me, or Register. Atomic Power. D Taylor. Abstract. No Abstract. Full Text: EMAIL FREE FULL TEXT ...

  12. Chemistry with bigger, better atoms

    Indian Academy of Sciences (India)

    DELL

    Why are QD-QD solids Stoichiometric. • Adjacent QD levels are <0.1 eV apart. • In contrast, atomic oxidation states are separated by. ~1 eV. • Creation of a Stoichiometric defect is 1012 times easier. × Packing Effects. × (Impossible in disordered solids). × Shell Filling. × (Insufficient level separation) ...

  13. Peace and the Atomic Bomb

    Energy Technology Data Exchange (ETDEWEB)

    Bradbury, Norris E. [Los Alamos National Lab. (LANL), Los Alamos, NM (United States); Meade, Roger Allen [Los Alamos National Lab. (LANL), Los Alamos, NM (United States)

    1948-12-02

    A little over three years after assuming the directorship of the Los Alamos Scientific Laboratory, Norris Bradbury returned to his alma mater, Pomona College, and delivered one of his first extended speeches regarding the atomic bomb. Bradbury noted that although the atomic bomb had brought a “peace of kind,” ending World War II, the bomb also had become, without much thought, a “factor in the political, military, and diplomatic thinking of the world.” Bradbury hoped his speech, given to both the faculty and student body of Pomona, would give his audience a foundation on which to assess and understand the new world the bomb had ushered into existence. Bradbury’s talk was quickly printed an distributed by Pomona College and, later, reprinted in The Physical Review (Volume 75, No. 8, 1154-1160, April 15, 1949). It is reprinted here, for a third time, as a reminder of the early days of Los Alamos and its role in international affairs. "Slightly more that three years ago, this country brought to an end the most catastrophic war in history. The conflict had been characterized by an unremitting application of science to the technology of destruction. The final use of the atomic bomb, however, provided a climax so striking that the inevitable nature of future wars was illustrated with the utmost clarity. Peace of a kind followed the first military use of atomic weapons, but international understanding did not, and the atomic bomb became a factor in the political, military, and diplomatic thinking of the world. Where do we now stand in all this? What are the costs and the rewards? Where are we going? These are some of the things that I would like to discuss with you this morning."

  14. Atoms, molecules and optical physics 1. Atoms and spectroscopy

    Energy Technology Data Exchange (ETDEWEB)

    Hertel, Ingolf V.; Schulz, Claus-Peter

    2015-09-01

    This is the first volume of textbooks on atomic, molecular and optical physics, aiming at a comprehensive presentation of this highly productive branch of modern physics as an indispensable basis for many areas in physics and chemistry as well as in state of the art bio- and material-sciences. It primarily addresses advanced students (including PhD students), but in a number of selected subject areas the reader is lead up to the frontiers of present research. Thus even the active scientist is addressed. This volume 1 provides the canonical knowledge in atomic physics together with basics of modern spectroscopy. Starting from the fundamentals of quantum physics, the reader is familiarized in well structured chapters step by step with the most important phenomena, models and measuring techniques. The emphasis is always on the experiment and its interpretation, while the necessary theory is introduced from this perspective in a compact and occasionally somewhat heuristic manner, easy to follow even for beginners.

  15. Atom Probe Tomography of Geomaterials

    Science.gov (United States)

    Parman, S. W.; Diercks, D.; Gorman, B.; Cooper, R. F.

    2013-12-01

    From the electron microprobe to the secondary ion microprobe to laser-ablation ICP-MS, steady improvements in the spatial resolution and detection limits of geochemical micro-analysis have been central to generating new discoveries. Atom probe tomography (APT) is a relatively new technology that promises nm-scale spatial resolution (in three dimensions) with ppm level detection limits. The method is substantially different from traditional beam-based (electron, ion, laser) methods. In APT, the sample is shaped (usually with a dual-beam FIB) into a needle with typical dimensions of 1-2 μm height and 100-200 nm diameter. Within the atom probe, the needle is evaporated one atom (ideally) at a time by a high electric field (ten's of V per square nm at the needle tip). A femtosecond laser (12 ps pulse width) is used to assist in evaporating non-conducting samples. The two-dimensional detector locates where the atom was released from the needle's surface and so can reconstruct the positions of all detected atoms in three dimensions. It also records the time of flight of the ion, which is used to calculate the mass/charge ratio of the ion. We will discuss our results analyzing a range of geologic materials. In one case, naturally occurring platinum group alloys (PGA) from the Josephine Ophiolite have been imaged. Such alloys are of interest as recorders of the Os heterogeneity of the mantle [1,2]. Optimal ablation was achieved with a laser power of 120-240 pJ and laser pulse rates 500 kHz. Runs were stopped after 10 million atoms were imaged. An example analysis is: Pt 61(1), Fe 26.1(9), Rh 1.20(4), Ir 7.0(7), Ni 2.65(8), Ru 0.20(9), Cu 1.22(8), Co 0.00029(5). Values are in atomic %; values in parentheses are one-sigma standard deviations on five separate needles from the same FIB lift-out, which was 30 μm long. Assuming the sample is homogenous over the 30 μm from which the needle was extracted, the analyses suggest relative errors for major elements below 5% and for

  16. Super-Coulombic atom-atom interactions in hyperbolic media

    Science.gov (United States)

    Cortes, Cristian L.; Jacob, Zubin

    2017-01-01

    Dipole-dipole interactions, which govern phenomena such as cooperative Lamb shifts, superradiant decay rates, Van der Waals forces and resonance energy transfer rates, are conventionally limited to the Coulombic near-field. Here we reveal a class of real-photon and virtual-photon long-range quantum electrodynamic interactions that have a singularity in media with hyperbolic dispersion. The singularity in the dipole-dipole coupling, referred to as a super-Coulombic interaction, is a result of an effective interaction distance that goes to zero in the ideal limit irrespective of the physical distance. We investigate the entire landscape of atom-atom interactions in hyperbolic media confirming the giant long-range enhancement. We also propose multiple experimental platforms to verify our predicted effect with phonon-polaritonic hexagonal boron nitride, plasmonic super-lattices and hyperbolic meta-surfaces as well. Our work paves the way for the control of cold atoms above hyperbolic meta-surfaces and the study of many-body physics with hyperbolic media.

  17. Atomic Covalent Functionalization of Graphene

    Science.gov (United States)

    Johns, James E.; Hersam, Mark C.

    2012-01-01

    Conspectus Although graphene’s physical structure is a single atom thick, two-dimensional, hexagonal crystal of sp2 bonded carbon, this simple description belies the myriad interesting and complex physical properties attributed to this fascinating material. Because of its unusual electronic structure and superlative properties, graphene serves as a leading candidate for many next generation technologies including high frequency electronics, broadband photodetectors, biological and gas sensors, and transparent conductive coatings. Despite this promise, researchers could apply graphene more routinely in real-world technologies if they could chemically adjust graphene’s electronic properties. For example, the covalent modification of graphene to create a band gap comparable to silicon (~1 eV) would enable its use in digital electronics, and larger band gaps would provide new opportunities for graphene-based photonics. Towards this end, researchers have focused considerable effort on the chemical functionalization of graphene. Due to its high thermodynamic stability and chemical inertness, new methods and techniques are required to create covalent bonds without promoting undesirable side reactions or irreversible damage to the underlying carbon lattice. In this Account, we review and discuss recent theoretical and experimental work studying covalent modifications to graphene using gas phase atomic radicals. Atomic radicals have sufficient energy to overcome the kinetic and thermodynamic barriers associated with covalent reactions on the basal plane of graphene but lack the energy required to break the C-C sigma bonds that would destroy the carbon lattice. Furthermore, because they are atomic species, radicals substantially reduce the likelihood of unwanted side reactions that confound other covalent chemistries. Overall, these methods based on atomic radicals show promise for the homogeneous functionalization of graphene and the production of new classes of two

  18. Remote atom entanglement in a fiber-connected three-atom system

    OpenAIRE

    Yan-Qing, Guo; Jing, Chen; He-Shan, Song

    2008-01-01

    An Ising-type atom-atom interaction is obtained in a fiber-connected three-atom system. The interaction is effective when $\\Delta\\approx \\gamma _{0}\\gg g$. The preparations of remote two-atom and three-atom entanglement governed by this interaction are discussed in specific parameters region. The overall two-atom entanglement is very small because of the existence of the third atom. However, the three-atom entanglement can reach a maximum very close to 1.

  19. Atomizer

    DEFF Research Database (Denmark)

    Fixed stereo electroacoustic music, included in Robert Voisey’s (Curator) VoxNovus 60×60 Dance, 60×60 2010 International Mix and 60×60 Sanguine Mix projects. Performed internationally, including Stratford Circus, London, UK. Full performance listings and press available online....

  20. Cooper pairs in atomic nuclei

    Energy Technology Data Exchange (ETDEWEB)

    Pittel, S. [Bartol Research Institute and Department of Physics and Astronomy, University of Delaware, Newark, 19716 Delaware (United States); Dussel, G. G. [Departamento de Fisica J.J. Giambiagi, Universidad de Buenos Aires, 1428 Buenos Aires (Argentina); Dukelsky, J.; Sarriguren, P. [Instituto de Estructura de la Materia, CSIC, Serrano 123, 28006 Madrid (Spain)

    2008-12-15

    We describe recent efforts to study Cooper pairs in atomic nuclei. We consider a self-consistent Hartree Fock mean field for the even Sm isotopes and compare results based on three treatments of pairing correlations: a BCS treatment, a number-projected BCS treatment and an exact treatment using the Richardson Ansatz. Significant differences are seen in the pairing correlation energies. Furthermore, because it does not average over the properties of the fermion pairs, the Richardson solution permits a more meaningful definition of the Cooper wave function and of the fraction of pairs that are collective. Our results confirm that only a few pairs near the Fermi surface in realistic atomic nuclei are collective. (Author)

  1. Helium atom scattering from surfaces

    CERN Document Server

    1992-01-01

    High resolution helium atom scattering can be applied to study a number of interesting properties of solid surfaces with great sensitivity and accuracy. This book treats in detail experimental and theoretical aspects ofthis method as well as all current applications in surface science. The individual chapters - all written by experts in the field - are devoted to the investigation of surface structure, defect shapes and concentrations, the interaction potential, collective and localized surface vibrations at low energies, phase transitions and surface diffusion. Over the past decade helium atom scattering has gained widespread recognitionwithin the surface science community. Points in its favour are comprehensiveunderstanding of the scattering theory and the availability of well-tested approximation to the rigorous theory. This book will be invaluable to surface scientists wishing to make an informed judgement on the actual and potential capabilities of this technique and its results.

  2. The Future of Atomic Energy

    Science.gov (United States)

    Fermi, E.

    1946-05-27

    There is definitely a technical possibility that atomic power may gradually develop into one of the principal sources of useful power. If this expectation will prove correct, great advantages can be expected to come from the fact that the weight of the fuel is almost negligible. This feature may be particularly valuable for making power available to regions of difficult access and far from deposits of coal. It also may prove a great asset in mobile power units for example in a power plant for ship propulsion. On the negative side there are some technical limitations to be applicability of atomic power of which perhaps the most serious is the impossibility of constructing light power units; also there will be some peculiar difficulties in operating atomic plants, as for example the necessity of handling highly radioactive substances which will necessitate, at least for some considerable period, the use of specially skilled personnel for the operation. But the chief obstacle in the way of developing atomic power will be the difficulty of organizing a large scale industrial development in an internationally safe way. This presents actually problems much more difficult to solve than any of the technical developments that are necessary, It will require an unusual amount of statesmanship to balance properly the necessity of allaying the international suspicion that arises from withholding technical secrets against the obvious danger of dumping the details of the procedures for an extremely dangerous new method of warfare on a world that may not yet be prepared to renounce war. Furthermore, the proper balance should be found in the relatively short time that will elapse before the 'secrets' will naturally become open knowledge by rediscovery on part of the scientists and engineers of other countries.

  3. Quantum state atomic force microscopy

    OpenAIRE

    Passian, Ali; Siopsis, George

    2017-01-01

    New classical modalities of atomic force microscopy continue to emerge to achieve higher spatial, spectral, and temporal resolution for nanometrology of materials. Here, we introduce the concept of a quantum mechanical modality that capitalizes on squeezed states of probe displacement. We show that such squeezing is enabled nanomechanically when the probe enters the van der Waals regime of interaction with a sample. The effect is studied in the non-contact mode, where we consider the paramete...

  4. Laser Cooling of Neutral Atoms.

    Science.gov (United States)

    1983-12-01

    wave monochromatic field interactint, with the atomic beam, the above assumption is justified. If the external field is a standing wave, and the atomo ...Substitute for the time derivatives using Schrodingers wave equation and perform some algebra to obtain, Integrate over the second term by parts twice...exponents into sin’s and cos’s. Calculating the indicated magnitude is tedious but straightforward. The real and imaginary parts of the equation are squared

  5. Optimization of Neutral Atom Imagers

    Science.gov (United States)

    Shappirio, M.; Coplan, M.; Balsamo, E.; Chornay, D.; Collier, M.; Hughes, P.; Keller, J.; Ogilvie, K.; Williams, E.

    2008-01-01

    The interactions between plasma structures and neutral atom populations in interplanetary space can be effectively studied with energetic neutral atom imagers. For neutral atoms with energies less than 1 keV, the most efficient detection method that preserves direction and energy information is conversion to negative ions on surfaces. We have examined a variety of surface materials and conversion geometries in order to identify the factors that determine conversion efficiency. For chemically and physically stable surfaces smoothness is of primary importance while properties such as work function have no obvious correlation to conversion efficiency. For the noble metals, tungsten, silicon, and graphite with comparable smoothness, conversion efficiency varies by a factor of two to three. We have also examined the way in which surface conversion efficiency varies with the angle of incidence of the neutral atom and have found that the highest efficiencies are obtained at angles of incidence greater then 80deg. The conversion efficiency of silicon, tungsten and graphite were examined most closely and the energy dependent variation of conversion efficiency measured over a range of incident angles. We have also developed methods for micromachining silicon in order to reduce the volume to surface area over that of a single flat surface and have been able to reduce volume to surface area ratios by up to a factor of 60. With smooth micro-machined surfaces of the optimum geometry, conversion efficiencies can be increased by an order of magnitude over instruments like LENA on the IMAGE spacecraft without increase the instruments mass or volume.

  6. Plasmonic atoms and plasmonic molecules

    OpenAIRE

    V. V. Klimov; Guzatov, D. V.

    2007-01-01

    The proposed paradigm of plasmonic atoms and plasmonic molecules allows one to describe and predict the strongly localized plasmonic oscillations in the clusters of nanoparticles and some other nanostructures in uniform way. Strongly localized plasmonic molecules near the contacting surfaces might become the fundamental elements (by analogy with Lego bricks) for a construction of fully integrated opto-electronic nanodevices of any complexity and scale of integration.

  7. Stochastic models for atomic clocks

    Science.gov (United States)

    Barnes, J. A.; Jones, R. H.; Tryon, P. V.; Allan, D. W.

    1983-01-01

    For the atomic clocks used in the National Bureau of Standards Time Scales, an adequate model is the superposition of white FM, random walk FM, and linear frequency drift for times longer than about one minute. The model was tested on several clocks using maximum likelihood techniques for parameter estimation and the residuals were acceptably random. Conventional diagnostics indicate that additional model elements contribute no significant improvement to the model even at the expense of the added model complexity.

  8. Empirical atom model of Vegard's law

    Science.gov (United States)

    Zhang, Lei; Li, Shichun

    2014-02-01

    Vegard's law seldom holds true for most binary continuous solid solutions. When two components form a solid solution, the atom radii of component elements will change to satisfy the continuity requirement of electron density at the interface between component atom A and atom B so that the atom with larger electron density will expand and the atom with the smaller one will contract. If the expansion and contraction of the atomic radii of A and B respectively are equal in magnitude, Vegard's law will hold true. However, the expansion and contraction of two component atoms are not equal in most situations. The magnitude of the variation will depend on the cohesive energy of corresponding element crystals. An empirical atom model of Vegard's law has been proposed to account for signs of deviations according to the electron density at Wigner-Seitz cell from Thomas-Fermi-Dirac-Cheng model.

  9. "Electronium": A Quantum Atomic Teaching Model.

    Science.gov (United States)

    Budde, Marion; Niedderer, Hans; Scott, Philip; Leach, John

    2002-01-01

    Outlines an alternative atomic model to the probability model, the descriptive quantum atomic model Electronium. Discusses the way in which it is intended to support students in learning quantum-mechanical concepts. (Author/MM)

  10. Atomic clock ensemble in space

    Science.gov (United States)

    Cacciapuoti, L.; Salomon, C.

    2011-12-01

    Atomic Clock Ensemble in Space (ACES) is a mission using high-performance clocks and links to test fundamental laws of physics in space. Operated in the microgravity environment of the International Space Station, the ACES clocks, PHARAO and SHM, will generate a frequency reference reaching instability and inaccuracy at the 1 · 10-16 level. A link in the microwave domain (MWL) and an optical link (ELT) will make the ACES clock signal available to ground laboratories equipped with atomic clocks. Space-to-ground and ground-to-ground comparisons of atomic frequency standards will be used to test Einstein's theory of general relativity including a precision measurement of the gravitational red-shift, a search for time variations of fundamental constants, and Lorentz Invariance tests. Applications in geodesy, optical time transfer, and ranging will also be supported. ACES has now reached an advanced technology maturity, with engineering models completed and successfully tested and flight hardware under development. This paper presents the ACES mission concept and the status of its main instruments.

  11. Dynamics in atomic signaling games

    KAUST Repository

    Fox, Michael J.

    2015-04-08

    We study an atomic signaling game under stochastic evolutionary dynamics. There are a finite number of players who repeatedly update from a finite number of available languages/signaling strategies. Players imitate the most fit agents with high probability or mutate with low probability. We analyze the long-run distribution of states and show that, for sufficiently small mutation probability, its support is limited to efficient communication systems. We find that this behavior is insensitive to the particular choice of evolutionary dynamic, a property that is due to the game having a potential structure with a potential function corresponding to average fitness. Consequently, the model supports conclusions similar to those found in the literature on language competition. That is, we show that efficient languages eventually predominate the society while reproducing the empirical phenomenon of linguistic drift. The emergence of efficiency in the atomic case can be contrasted with results for non-atomic signaling games that establish the non-negligible possibility of convergence, under replicator dynamics, to states of unbounded efficiency loss.

  12. Atom-specific surface magnetometry

    Energy Technology Data Exchange (ETDEWEB)

    Sirotti, F.; Panaccione, G. [Laboratoire pour l`Utilisation du Rayonnement Electromagnetique, Centre National de la Recherche Scientifique, Commissariat a l`Energie Atomique, MESR, F-91405 Orsay (France); Rossi, G. [Laboratorium fuer Festkoerperphysik, Eidgenossische Technische Hochschule-Zuerich, Zuerich CH-8093 (Switzerland)

    1995-12-15

    A powerful atom-specific surface magnetometry can be based on efficient measurements of magnetic dichroism in {ital l}{gt}0 core level photoemission. The temperature dependence M({ital T}) of the Fe(100) surface magnetization was obtained from the photoemission magnetic asymmetry of 3{ital p} core levels, providing the measure of the surface exchange coupling via the spin-wave stiffness and of the surface critical exponent. Beyond the magnetic order {l_angle}M{r_angle} the photoemission dichroism allows us to derive the energy splitting of the magnetic sublevels of the photoexcited core hole. Fe 3{ital p} photoemission dichroism probes directly the magnetic moment changes of iron atoms at Fe(100) surfaces as a function of structural disorder or sulfur segregation. The appearance of dichroism in the 2{ital p} photoemission of segregated sulfur atoms in the {ital c}(2{times}2)S/Fe(100) superstructure measures the magnetic-moment transfer and shows the possibility of investigating surface magnetochemistry in a very direct way.

  13. Dynamics in atomic signaling games.

    Science.gov (United States)

    Fox, Michael J; Touri, Behrouz; Shamma, Jeff S

    2015-07-07

    We study an atomic signaling game under stochastic evolutionary dynamics. There are a finite number of players who repeatedly update from a finite number of available languages/signaling strategies. Players imitate the most fit agents with high probability or mutate with low probability. We analyze the long-run distribution of states and show that, for sufficiently small mutation probability, its support is limited to efficient communication systems. We find that this behavior is insensitive to the particular choice of evolutionary dynamic, a property that is due to the game having a potential structure with a potential function corresponding to average fitness. Consequently, the model supports conclusions similar to those found in the literature on language competition. That is, we show that efficient languages eventually predominate the society while reproducing the empirical phenomenon of linguistic drift. The emergence of efficiency in the atomic case can be contrasted with results for non-atomic signaling games that establish the non-negligible possibility of convergence, under replicator dynamics, to states of unbounded efficiency loss. Copyright © 2015 Elsevier Ltd. All rights reserved.

  14. Inner Space: The Structure of the Atom

    Energy Technology Data Exchange (ETDEWEB)

    Glasstone, Samuel

    1972-01-01

    The atom is now regarded as the smallest possible particle of an element that retains the identity of that element. The atoms of an element determine the characteristics of that particular element. One of the purposes of this booklet is to explain how the atoms of various elements differ from one another.

  15. Gain narrowing in few-atom systems

    NARCIS (Netherlands)

    Savels, T.; Savels, Tom; Mosk, Allard; Lagendijk, Aart

    2007-01-01

    Using a density matrix approach, we study the simplest systems that display both gain and feedback: clusters of 2 to 5 atoms, one of which is pumped. The other atoms supply feedback through multiple scattering of light. We show that, if the atoms are in each other's near field, the system exhibits

  16. Laser Control of Atoms and Molecules

    CERN Document Server

    Letkhov, V S

    2007-01-01

    This text treats laser light as a universal tool to control matter at the atomic and molecular level, one of the most exciting applications of lasers. Lasers can heat matter, cool atoms to ultra-low temperatures where they show quantum collective behaviour, and can act selectively on specific atoms and molecules for their detection and separation.

  17. Atoms – How Small, and How Large!

    Indian Academy of Sciences (India)

    IAS Admin

    Introduction. −Richard Feynman. Famous physicist Feynman's quote highlighting the atomic concept as an important achievement of mankind, has come nearly ... philosophy to science. How small are atoms actually? Niels Bohr in his atomic model (1913) answered this question by assigning a radius a0 (= 0.529Å) to the.

  18. Atomic Delegation: Object-Oriented Transactions

    NARCIS (Netherlands)

    Aksit, Mehmet; Dijkstra, J.W.; Dijkstra, Jan Willem; Tripathi, Anand

    Atomic delegation, an object-oriented linguistic mechanism that allows the creation of dynamically defined classes of atomic actions is presented. When a type is modified, atomic delegation updates functionalities of the the types that delegate to the modified type. This mechanism permits dynamic

  19. Clarifying Atomic Weights: A 2016 Four-Figure Table of Standard and Conventional Atomic Weights

    Science.gov (United States)

    Coplen, Tyler B.; Meyers, Fabienne; Holden, Norman E.

    2017-01-01

    To indicate that atomic weights of many elements are not constants of nature, in 2009 and 2011 the Commission on Isotopic Abundances and Atomic Weights (CIAAW) of the International Union of Pure and Applied Chemistry (IUPAC) replaced single-value standard atomic weight values with atomic weight intervals for 12 elements (hydrogen, lithium, boron,…

  20. Optical lattice on an atom chip

    DEFF Research Database (Denmark)

    Gallego, D.; Hofferberth, S.; Schumm, Thorsten

    2009-01-01

    Optical dipole traps and atom chips are two very powerful tools for the quantum manipulation of neutral atoms. We demonstrate that both methods can be combined by creating an optical lattice potential on an atom chip. A red-detuned laser beam is retroreflected using the atom chip surface as a high......-quality mirror, generating a vertical array of purely optical oblate traps. We transfer thermal atoms from the chip into the lattice and observe cooling into the two-dimensional regime. Using a chip-generated Bose-Einstein condensate, we demonstrate coherent Bloch oscillations in the lattice....

  1. Storage of Quantum Variables in Atomic Media

    DEFF Research Database (Denmark)

    Cviklinski, J.; Ortalo, J.; Josse, V.

    2007-01-01

    Storage and read-out of non classical states of light is a critical element for quantum information networks. Simultaneous storage of two non-commuting variables carried by light and subsequent read-out is shown to be possible in atomic ensembles. Interaction of light fields with three......-level systems allows direct mapping the quantum state of light into long lived coherences in the atomic ground state. We show that excess noise linked to atomic transitions can be made negligible. Experimental developments are discussed for atomic vapours and cold atoms....

  2. Fast metastable hydrogen atoms from H2 molecules: twin atoms

    Directory of Open Access Journals (Sweden)

    Trimèche A.

    2015-01-01

    Full Text Available It is a difficult task to obtain “twin atoms”, i.e. pairs of massive particles such that one can perform experiments in the same fashion that is routinely done with “twin photons”. One possible route to obtain such pairs is by dissociating homonuclear diatomic molecules. We address this possibility by investigating the production of metastable H(2s atoms coming from the dissociation of cold H2 molecules produced in a Campargue nozzle beam crossing an electron beam from a high intensity pulsed electron gun. Dissociation by electron impact was chosen to avoid limitations of target molecular excited states due to selection rules. Detectors placed several centimeters away from the collision center, and aligned with respect to possible common molecular dissociation channel, analyze the neutral fragments as a function of their time-of-flight (TOF through Lyman-α detection. Evidence for the first time observed coincidence of pairs of H(2s atoms obtained this way is presented.

  3. Scanning Quantum Cryogenic Atom Microscope

    Science.gov (United States)

    Yang, Fan; Kollár, Alicia J.; Taylor, Stephen F.; Turner, Richard W.; Lev, Benjamin L.

    2017-03-01

    Microscopic imaging of local magnetic fields provides a window into the organizing principles of complex and technologically relevant condensed-matter materials. However, a wide variety of intriguing strongly correlated and topologically nontrivial materials exhibit poorly understood phenomena outside the detection capability of state-of-the-art high-sensitivity high-resolution scanning probe magnetometers. We introduce a quantum-noise-limited scanning probe magnetometer that can operate from room-to-cryogenic temperatures with unprecedented dc-field sensitivity and micron-scale resolution. The Scanning Quantum Cryogenic Atom Microscope (SQCRAMscope) employs a magnetically levitated atomic Bose-Einstein condensate (BEC), thereby providing immunity to conductive and blackbody radiative heating. The SQCRAMscope has a field sensitivity of 1.4 nT per resolution-limited point (approximately 2 μ m ) or 6 nT /√{Hz } per point at its duty cycle. Compared to point-by-point sensors, the long length of the BEC provides a naturally parallel measurement, allowing one to measure nearly 100 points with an effective field sensitivity of 600 pT /√{Hz } for each point during the same time as a point-by-point scanner measures these points sequentially. Moreover, it has a noise floor of 300 pT and provides nearly 2 orders of magnitude improvement in magnetic flux sensitivity (down to 10-6 Φ0/√{Hz } ) over previous atomic probe magnetometers capable of scanning near samples. These capabilities are carefully benchmarked by imaging magnetic fields arising from microfabricated wire patterns in a system where samples may be scanned, cryogenically cooled, and easily exchanged. We anticipate the SQCRAMscope will provide charge-transport images at temperatures from room temperature to 4 K in unconventional superconductors and topologically nontrivial materials.

  4. Resonant interaction modified by the atomic environment

    Energy Technology Data Exchange (ETDEWEB)

    Sainz, I; Klimov, A B; Chumakov, S M [Departamento de Fisica, Universidad de Guadalajara, Revolucion 1500, 44410, Guadalajara, Jal. (Mexico)

    2003-04-01

    The dynamics of a resonant atom interacting with a quantum cavity field in the presence of many off-resonant atoms is studied. In the framework of the effective Hamiltonian approach we show that the results of elimination of non-resonant transitions are (a) a dynamical Stark shift of the field frequency, dependent on the populations of non-resonant atoms, (b) dependence of the coupling constant between the resonant atom and the field on the populations of non-resonant atoms, and (c) an effective dipole-dipole interaction between non-resonant atoms. Two effects (the coherent influence and dephasing) of the off-resonant environment on the dynamics of the resonant atom are discussed.

  5. Periodic systems of N-atom molecules

    Science.gov (United States)

    Hefferlin, R. A.; Zhuvikin, G. V.; Caviness, K. E.; Duerksen, P. J.

    1984-10-01

    The atoms have long been classified into a periodic system, which is now based on quantum mechanics and group theory. A classification of molecules containing any number (N) of atoms is proposed. It is an extension of the periodic system of the atoms. The approach in this paper is that of group theory, although the proposed system has been subjected to exhaustive comparison with experimental and ab initio computational results for diatomic molecules, and conforms to the commonly known behaviors of molecules with larger N. Orthonormal transformations are performed so that the molecules can be arranged according to their numbers of electrons and to the differences of atomic numbers of the constituent atoms. These arrangements parallel the physical reality of atomic bonding and permit partial three-dimensional models of the systems to be constructed for molecules with as many as four atoms.

  6. Ohm's law survives to the atomic scale.

    Science.gov (United States)

    Weber, B; Mahapatra, S; Ryu, H; Lee, S; Fuhrer, A; Reusch, T C G; Thompson, D L; Lee, W C T; Klimeck, G; Hollenberg, L C L; Simmons, M Y

    2012-01-06

    As silicon electronics approaches the atomic scale, interconnects and circuitry become comparable in size to the active device components. Maintaining low electrical resistivity at this scale is challenging because of the presence of confining surfaces and interfaces. We report on the fabrication of wires in silicon--only one atom tall and four atoms wide--with exceptionally low resistivity (~0.3 milliohm-centimeters) and the current-carrying capabilities of copper. By embedding phosphorus atoms within a silicon crystal with an average spacing of less than 1 nanometer, we achieved a diameter-independent resistivity, which demonstrates ohmic scaling to the atomic limit. Atomistic tight-binding calculations confirm the metallicity of these atomic-scale wires, which pave the way for single-atom device architectures for both classical and quantum information processing.

  7. Knowledge Extraction from Atomically Resolved Images.

    Science.gov (United States)

    Vlcek, Lukas; Maksov, Artem; Pan, Minghu; Vasudevan, Rama K; Kalinin, Sergei V

    2017-10-24

    Tremendous strides in experimental capabilities of scanning transmission electron microscopy and scanning tunneling microscopy (STM) over the past 30 years made atomically resolved imaging routine. However, consistent integration and use of atomically resolved data with generative models is unavailable, so information on local thermodynamics and other microscopic driving forces encoded in the observed atomic configurations remains hidden. Here, we present a framework based on statistical distance minimization to consistently utilize the information available from atomic configurations obtained from an atomically resolved image and extract meaningful physical interaction parameters. We illustrate the applicability of the framework on an STM image of a FeSe x Te 1-x superconductor, with the segregation of the chalcogen atoms investigated using a nonideal interacting solid solution model. This universal method makes full use of the microscopic degrees of freedom sampled in an atomically resolved image and can be extended via Bayesian inference toward unbiased model selection with uncertainty quantification.

  8. Precision spectroscopy on atomic hydrogen

    Energy Technology Data Exchange (ETDEWEB)

    Parthey, Christian Godehard

    2011-12-15

    This Thesis reports on three measurements involving the 1S-2S transition in atomic hydrogen and deuterium conducted on a 5.8 K atomic beam. The transition is excited Doppler-free via two counter-propagating photons near 243 nm. The H/D isotope shift has been determined as {delta}{integral}{sub exp}=670 994 334 606(15) Hz. Comparing with the theoretical value for the isotope shift, excluding the leading nuclear size effect, {delta}{integral}{sub th}=670 999 566.90(66)(60) kHz we confirm, twice more accurate, the rms charge radius difference of the deuteron and the proton as left angle r{sup 2} right angle {sub d}- left angle r{sup 2} right angle {sub p}=3.82007(65) fm{sup 2} and the deuteron structure radius r{sub str}=1.97507(78) fm. The frequency ratio of the 1S-2S transition in atomic hydrogen to the cesium ground state hyperfine transition provided by the mobile cesium fountain clock FOM is measured to be {integral}{sub 1S-2S}=2 466 061 413 187 035 (10) Hz which presents a fractional frequency uncertainty of 4.2 x 10{sup -15}. The second absolute frequency measurement of the 1S-2S transition in atomic hydrogen presents the first application of a 900 km fiber link between MPQ and Physikalisch- Technische Bundesanstalt (PTB) in Braunschweig which we have used to calibrate the MPQ hydrogen maser with the stationary cesium fountain clock CSF1 at PTB. With the result of {integral}{sub 1S-2S}=2 466 061 413 187 017 (11) Hz we can put a constraint on the electron Lorentz boost violating coefficients 0.95c{sub (TX)}-0.29c{sub (TY)}-0.08 c{sub (TZ)}=(2.2{+-}1.8) x 10{sup -11} within the framework of minimal standard model extensions. We limit a possible drift of the strong coupling constant through the ratio of magnetic moments at a competitive level ({partial_derivative})/({partial_derivative}t)ln ({mu}{sub Cs})/({mu}{sub B})=-(3.0{+-}1.2) x 10{sup -15} yr{sup -1}.

  9. Atomic valence in molecular systems

    Science.gov (United States)

    Bochicchio, R. C.; Lain, L.; Torre, A.

    2003-06-01

    Atomic valence in molecular systems is described as a partitioning of the hole distribution, the complementary part of the particle distribution. In this scheme, valence splits into three contributions, related to electron spin density, nonuniform occupancy of orbitals (nonpairing terms) and exchange density (pairing terms), respectively, and whose importance depends on the nature of the state of the system. Calculations carried out for correlated CI and Hartree-Fock state functions in both Mulliken and topological AIM type partitionings as well as theoretical results show the suitability of this formulation for describing valence concepts.

  10. Atoms, molecules and optical physics

    CERN Document Server

    Hertel, Ingolf V

    2015-01-01

    This is the first volume of textbooks on atomic, molecular and optical physics, aiming at a comprehensive presentation of this highly productive branch of modern physics as an indispensable basis for many areas in physics and chemistry as well as in state of the art bio- and material-sciences. It primarily addresses advanced students (including PhD students), but in a number of selected subject areas the reader is lead up to the frontiers of present research. Thus even the active scientist is addressed. This volume 1 provides the canonical knowledge in atomic physics together with basics of modern spectroscopy. Starting from the fundamentals of quantum physics, the reader is familiarized in well structured chapters step by step with the most important phenomena, models and measuring techniques. The emphasis is always on the experiment and its interpretation, while the necessary theory is introduced from this perspective in a compact and occasionally somewhat heuristic manner, easy to follow even for beginner...

  11. Atomic inner-shell transitions

    Science.gov (United States)

    Crasemann, B.; Chen, M. H.; Mark, H.

    1984-01-01

    Atomic inner-shell processes have quite different characteristics, in several important aspects, from processes in the optical regime. Energies are large, e.g., the 1s binding energy reaches 100 keV at Z = 87; relativistic and quantum-electrodynamic effects therefore are strong. Radiationless transitions vastly dominate over photon emission in most cases. Isolated inner-shell vacancies have pronounced single-particle character, with correlations generally contributing only approximately 1 eV to the 1s and 2p binding energies; the structure of such systems is thus well tractable by independent-particle self-consistent-field atomic models. For systems containing multiple deep inner-shell vacancies, or for highly stripped ions, the importance of relativistic intermediate coupling and configuration interaction becomes pronounced. Cancellation of the Coulomb interaction can lead to strong manifestations of the Breit interaction in such phenomena as multiplet splitting and hypersatellite X-ray shifts. Unique opportunities arise for the test of theory.

  12. Atomic coordination reflects peptide immunogenicity

    Directory of Open Access Journals (Sweden)

    Georgios S.E. Antipas

    2016-01-01

    Full Text Available We demonstrated that the immunological identity of variant peptides may be accurately predicted on the basis of atomic coordination of both unprotonated and protonated tertiary structures, provided that the structure of the native peptide (index is known. The metric which was discovered to account for this discrimination is the coordination difference between the variant and the index; we also showed that increasing coordination difference in respect to the index was correlated to a correspondingly weakening immunological outcome of the variant. Additionally, we established that this metric quickly seizes to operate beyond the peptide scale, e.g. over a coordination shell inclusive of atoms up to a distance of 7 Å away from the peptide or over the entire pMHC-TCR complex. Analysis of molecular orbital interactions over a range of formal charges further revealed that the N-terminus of the agonists was always able to sustain a stable ammonium (NH3+ group which was consistently absent in antagonists. We deem that the presence of NH3+ constitutes a secondary observable with a biological consequence, signifying a change in T cell activation. While our analysis of protonated structures relied on the quantum chemical relaxation of the H species, the results were consistent over a wide range of peptide charge and spin polarization conditions.

  13. Deterministic Single Atom STM Tip Technology for Atomically Precise Manufacturing

    Science.gov (United States)

    Ballard, Joshua; Alexander, Justin; Radocea, Adrian; Bischof, Maia; Jaeger, David; Randall, John; Gorman, Brian; von Ehr, Jim; Reidy, Rick

    2011-03-01

    Deterministic tip fabrication for Scanning Tunneling Microscopy (STM) has long been an elusive goal, where the primary method of tip preparation usually includes significant ``tip conditioning'' once the tip has been incorporated into the STM. We have developed a process for generating reproducible single atom tips (SATs) with a small radius of curvature (r.o.c.) of less than 10nm. First, W(111) or W(110) tips are sputter sharpened using a self-limiting process to yield with r.o.c. of SAT is formed. Transmission Electron Microscopy is used to verify that after field evaporation the r.o.c. remains small. Correlations between FIM and tip performance in STM are determined, and long term STM stability is discussed.

  14. Hard and soft acids and bases: atoms and atomic ions.

    Science.gov (United States)

    Reed, James L

    2008-07-07

    The structural origin of hard-soft behavior in atomic acids and bases has been explored using a simple orbital model. The Pearson principle of hard and soft acids and bases has been taken to be the defining statement about hard-soft behavior and as a definition of chemical hardness. There are a number of conditions that are imposed on any candidate structure and associated property by the Pearson principle, which have been exploited. The Pearson principle itself has been used to generate a thermodynamically based scale of relative hardness and softness for acids and bases (operational chemical hardness), and a modified Slater model has been used to discern the electronic origin of hard-soft behavior. Whereas chemical hardness is a chemical property of an acid or base and the operational chemical hardness is an experimental measure of it, the absolute hardness is a physical property of an atom or molecule. A critical examination of chemical hardness, which has been based on a more rigorous application of the Pearson principle and the availability of quantitative measures of chemical hardness, suggests that the origin of hard-soft behavior for both acids and bases resides in the relaxation of the electrons not undergoing transfer during the acid-base interaction. Furthermore, the results suggest that the absolute hardness should not be taken as synonymous with chemical hardness but that the relationship is somewhat more complex. Finally, this work provides additional groundwork for a better understanding of chemical hardness that will inform the understanding of hardness in molecules.

  15. Reading and writing single-atom magnets

    Science.gov (United States)

    Natterer, Fabian D.; Yang, Kai; Paul, William; Willke, Philip; Choi, Taeyoung; Greber, Thomas; Heinrich, Andreas J.; Lutz, Christopher P.

    2017-03-01

    The single-atom bit represents the ultimate limit of the classical approach to high-density magnetic storage media. So far, the smallest individually addressable bistable magnetic bits have consisted of 3-12 atoms. Long magnetic relaxation times have been demonstrated for single lanthanide atoms in molecular magnets, for lanthanides diluted in bulk crystals, and recently for ensembles of holmium (Ho) atoms supported on magnesium oxide (MgO). These experiments suggest a path towards data storage at the atomic limit, but the way in which individual magnetic centres are accessed remains unclear. Here we demonstrate the reading and writing of the magnetism of individual Ho atoms on MgO, and show that they independently retain their magnetic information over many hours. We read the Ho states using tunnel magnetoresistance and write the states with current pulses using a scanning tunnelling microscope. The magnetic origin of the long-lived states is confirmed by single-atom electron spin resonance on a nearby iron sensor atom, which also shows that Ho has a large out-of-plane moment of 10.1 ± 0.1 Bohr magnetons on this surface. To demonstrate independent reading and writing, we built an atomic-scale structure with two Ho bits, to which we write the four possible states and which we read out both magnetoresistively and remotely by electron spin resonance. The high magnetic stability combined with electrical reading and writing shows that single-atom magnetic memory is indeed possible.

  16. Atomic Force Microscopy of Coccoliths: Implications for Biomineralisation and Diagenesis

    DEFF Research Database (Denmark)

    Henriksen, Karen; Young, Jette F.; Bown, P.R.

    2002-01-01

    geochemistry, diagenesis, coccoliths, biomineralization, biological calcite, atomic force microscopy......geochemistry, diagenesis, coccoliths, biomineralization, biological calcite, atomic force microscopy...

  17. Precision measurements with atom interferometry

    Science.gov (United States)

    Schubert, Christian; Abend, Sven; Schlippert, Dennis; Ertmer, Wolfgang; Rasel, Ernst M.

    2017-04-01

    Interferometry with matter waves enables precise measurements of rotations, accelerations, and differential accelerations [1-5]. This is exploited for determining fundamental constants [2], in fundamental science as e.g. testing the universality of free fall [3], and is applied for gravimetry [4], and gravity gradiometry [2,5]. At the Institut für Quantenoptik in Hannover, different approaches are pursued. A large scale device is designed and currently being set up to investigate the gain in precision for gravimetry, gradiometry, and fundamental tests on large baselines [6]. For field applications, a compact and transportable device is being developed. Its key feature is an atom chip source providing a collimated high flux of atoms which is expected to mitigate systematic uncertainties [7,8]. The atom chip technology and miniaturization benefits from microgravity experiments in the drop tower in Bremen and sounding rocket experiments [8,9] which act as pathfinders for space borne operation [10]. This contribution will report about our recent results. The presented work is supported by the CRC 1227 DQ-mat, the CRC 1128 geo-Q, the RTG 1729, the QUEST-LFS, and by the German Space Agency (DLR) with funds provided by the Federal Ministry of Economic Affairs and Energy (BMWi) due to an enactment of the German Bundestag under Grant No. DLR 50WM1552-1557. [1] P. Berg et al., Phys. Rev. Lett., 114, 063002, 2015; I. Dutta et al., Phys. Rev. Lett., 116, 183003, 2016. [2] J. B. Fixler et al., Science 315, 74 (2007); G. Rosi et al., Nature 510, 518, 2014. [3] D. Schlippert et al., Phys. Rev. Lett., 112, 203002, 2014. [4] A. Peters et al., Nature 400, 849, 1999; A. Louchet-Chauvet et al., New J. Phys. 13, 065026, 2011; C. Freier et al., J. of Phys.: Conf. Series 723, 012050, 2016. [5] J. M. McGuirk et al., Phys. Rev. A 65, 033608, 2002; P. Asenbaum et al., arXiv:1610.03832. [6] J. Hartwig et al., New J. Phys. 17, 035011, 2015. [7] H. Ahlers et al., Phys. Rev. Lett. 116, 173601

  18. Atom Interferometry for Fundamental Physics and Gravity Measurements in Space

    Science.gov (United States)

    Kohel, James M.

    2012-01-01

    Laser-cooled atoms are used as freefall test masses. The gravitational acceleration on atoms is measured by atom-wave interferometry. The fundamental concept behind atom interferometry is the quantum mechanical particle-wave duality. One can exploit the wave-like nature of atoms to construct an atom interferometer based on matter waves analogous to laser interferometers.

  19. Manipulating Atoms with Light Achievements and Perspectives

    CERN Multimedia

    CERN. Geneva

    2006-01-01

    During the last few decades spectacular progress has been achieved in the control of atomic systems by light. It will be shown how it is possible to use the basic conservation laws in atom-photon interactions for polarizing atoms, for trapping them, for cooling them to extremely low temperatures, in the microkelvin, and even in the nanokelvin range. A review will be given of recent advances in this field and of new applications, including atomic clocks with very high relative stability and accuracy, atomic interferometers allowing precise measurement of rotation speeds and gravitational fields, the realization of new states of matter such as Bose-Einstein condensates, matter waves and atom lasers, ultracold molecules. New perspectives opened by these results will be also briefly discussed.

  20. Magnetic trapping of cold bromine atoms.

    Science.gov (United States)

    Rennick, C J; Lam, J; Doherty, W G; Softley, T P

    2014-01-17

    Magnetic trapping of bromine atoms at temperatures in the millikelvin regime is demonstrated for the first time. The atoms are produced by photodissociation of Br2 molecules in a molecular beam. The lab-frame velocity of Br atoms is controlled by the wavelength and polarization of the photodissociation laser. Careful selection of the wavelength results in one of the pair of atoms having sufficient velocity to exactly cancel that of the parent molecule, and it remains stationary in the lab frame. A trap is formed at the null point between two opposing neodymium permanent magnets. Dissociation of molecules at the field minimum results in the slowest fraction of photofragments remaining trapped. After the ballistic escape of the fastest atoms, the trapped slow atoms are lost only by elastic collisions with the chamber background gas. The measured loss rate is consistent with estimates of the total cross section for only those collisions transferring sufficient kinetic energy to overcome the trapping potential.

  1. Trapping cold ground state argon atoms.

    Science.gov (United States)

    Edmunds, P D; Barker, P F

    2014-10-31

    We trap cold, ground state argon atoms in a deep optical dipole trap produced by a buildup cavity. The atoms, which are a general source for the sympathetic cooling of molecules, are loaded in the trap by quenching them from a cloud of laser-cooled metastable argon atoms. Although the ground state atoms cannot be directly probed, we detect them by observing the collisional loss of cotrapped metastable argon atoms and determine an elastic cross section. Using a type of parametric loss spectroscopy we also determine the polarizability of the metastable 4s[3/2](2) state to be (7.3±1.1)×10(-39)  C m(2)/V. Finally, Penning and associative losses of metastable atoms in the absence of light assisted collisions, are determined to be (3.3±0.8)×10(-10)  cm(3) s(-1).

  2. A nanoscale quantum interface for single atoms

    Science.gov (United States)

    Tiecke, Tobias; Thompson, Jeff; Feist, Johannes; Yu, Chun; Akimov, Alexey; Chang, Darrick; Zibrov, Alexander; Vuletic, Vladan; Park, Hongkun; Lukin, Mikhail

    2012-02-01

    Neutral atoms are ideal quantum systems: they have long ground-state coherence times and strong optical cycling transitions that enable state detection and preparation. Building quantum networks of atoms interacting through photons is challenging, however, as many schemes for atom-photon interaction are inefficient or hard to scale. We propose a scheme to trap neutral atoms near silver nanowires, which are tightly confining waveguides for surface plasmons. The nanowire tip is used to generate a near-field optical trapping potential, and to enhance and efficiently collect spontaneous emission from the atom. We present experimental results on using the atom to sense the optical field at submicron distances from the wire and our current efforts towards loading the nanotrap.

  3. Atomic bonding between metal and graphene

    KAUST Repository

    Wang, Hongtao

    2013-03-07

    To understand structural and chemical properties of metal-graphene composites, it is crucial to unveil the chemical bonding along the interface. We provide direct experimental evidence of atomic bonding between typical metal nano structures and graphene, agreeing well with density functional theory studies. Single Cr atoms are located in the valleys of a zigzag edge, and few-atom ensembles preferentially form atomic chains by self-assembly. Low migration barriers lead to rich dynamics of metal atoms and clusters under electron irradiation. We demonstrate no electron-instigated interaction between Cr clusters and pristine graphene, though Cr has been reported to be highly reactive to graphene. The metal-mediated etching is a dynamic effect between metal clusters and pre-existing defects. The resolved atomic configurations of typical nano metal structures on graphene offer insight into modeling and simulations on properties of metal-decorated graphene for both catalysis and future carbon-based electronics. © 2013 American Chemical Society.

  4. Nanostructured optical nanofibres for atom trapping

    CERN Document Server

    Daly, Mark; Phelan, Ciarán; Deasy, Kieran; Chormaic, Síle Nic

    2013-01-01

    We propose an optical dipole trap for cold neutral atoms based on the electric field produced from the evanescent fields in a hollow rectangular slot cut through an optical nanofibre. In particular, we discuss the trap performance in relation to laser-cooled rubidium atoms and show that a far off-resonance, blue-detuned field combined with the attractive surface-atom interaction potential from the dielectric material forms a stable trapping configuration. With the addition of a red-detuned field, we demonstrate how three dimensional confinement of the atoms at a distance of 140 - 200 nm from the fibre surface within the slot can be accomplished. This scheme facilitates optical coupling between the atoms and the nanofibre that could be exploited for quantum communication schemes using ensembles of laser-cooled atoms.

  5. Imaging the atomic orbitals of carbon atomic chains with field-emission electron microscopy

    Science.gov (United States)

    Mikhailovskij, I. M.; Sadanov, E. V.; Mazilova, T. I.; Ksenofontov, V. A.; Velicodnaja, O. A.

    2009-10-01

    A recently developed high-field technique of atomic chains preparation has made it possible to attain the ultrahigh resolution of field-emission electron microscopy (FEEM), which can be used to direct imaging the intra-atomic electronic structure. By applying cryogenic FEEM, we are able to resolve the spatial configuration of atomic orbitals, which correspond to quantized states of the end atom in free-standing carbon atomic chains. Knowledge of the intra-atomic structure will make it possible to visualize generic aspects of quantum mechanics and also lead to approaches for a wide range of nanotechnological applications.

  6. Scattering of muonic hydrogen atoms

    Energy Technology Data Exchange (ETDEWEB)

    Mulhauser, F. [Universite de Fribourg (Switzerland); Adamczak, A. [Institute of Nuclear Physics (Poland); Beer, G.A. [University of Victoria (Canada); Bystritsky, V.M. [Joint Institute for Nuclear Research (Russian Federation); Filipowicz, M. [Institute of Physics and Nuclear Techniques (Poland); Fujiwara, M.C. [University of British Columbia (Canada); Huber, T.M. [Gustavus Adolphus College (United States); Jacot-Guillarmod, R. [Universite de Fribourg (Switzerland); Kammel, P. [University of California (United States); Kim, S.K. [Jeonbuk National University (Korea, Republic of); Knowles, P. [Universite de Fribourg (Switzerland); Kunselman, A.R. [University of Wyoming (United States); Maier, M. [University of Victoria (Canada); Markushin, V.E. [Paul Scherrer Institute (Switzerland); Marshall, G.M. [TRIUMF (Canada); Olin, A. [University of Victoria (Canada); Petitjean, C. [Paul Scherrer Institute (Switzerland); Porcelli, T.A. [University of Victoria (Canada); Stolupin, V.A. [Joint Institute for Nuclear Research (Russian Federation); Wozniak, J. [Institute of Physics and Nuclear Techniques (Poland)] (and others)

    1999-06-15

    Our measurement compares the energy dependence of the scattering cross-sections of muonic deuterium and tritium on hydrogen molecules for collisions in the energy range 0.1-45 eV. A time-of-flight method was used to measure the scattering cross-section as a function of the muonic atom beam energy and shows clearly the Ramsauer-Townsend effect. The results are compared with theoretical calculations by using Monte Carlo simulations. The molecular pd{mu} and pt{mu} formation creates background processes. We measure the formation rates in solid hydrogen by detecting the 5.5 MeV (pd{mu}) and 19.8 MeV (pt{mu}) {gamma}-rays emitted during the subsequent nuclear fusion processes.

  7. Theoretical Calculations of Atomic Data for Spectroscopy

    Science.gov (United States)

    Bautista, Manuel A.

    2000-01-01

    Several different approximations and techniques have been developed for the calculation of atomic structure, ionization, and excitation of atoms and ions. These techniques have been used to compute large amounts of spectroscopic data of various levels of accuracy. This paper presents a review of these theoretical methods to help non-experts in atomic physics to better understand the qualities and limitations of various data sources and assess how reliable are spectral models based on those data.

  8. Quantum gates between superconducting and atomic qubits

    Science.gov (United States)

    Saffman, Mark; Wilhelm, Frank; McDermott, Robert

    2009-05-01

    We propose methods for performing entangling gate operations between superconducting phase qubits and neutral atom hyperfine qubits. The gate is mediated by mapping the superconducting qubit onto a microwave excitation of a coplanar waveguide resonator (CPW). The large transition dipole moments of atomic Rydberg states at microwave frequencies enable bidirectional entanglement between a single atom and a single CPW photon. Specific gate protocols and fidelity calculations are presented for experimentally realistic geometries.

  9. Atomicity violation detection using access interleaving invariants

    Science.gov (United States)

    Zhou, Yuanyuan; Lu, Shan; Tucek, Joseph Andrew

    2013-09-10

    During execution of a program, the situation where the atomicity of a pair of instructions that are to be executed atomically is violated is identified, and a bug is detected as occurring in the program at the pair of instructions. The pairs of instructions that are to be executed atomically can be identified in different manners, such as by executing a program multiple times and using the results of those executions to automatically identify the pairs of instructions.

  10. Atomic hydrogen storage method and apparatus

    Science.gov (United States)

    Woollam, J. A. (Inventor)

    1980-01-01

    Atomic hydrogen, for use as a fuel or as an explosive, is stored in the presence of a strong magnetic field in exfoliated layered compounds such as molybdenum disulfide or an elemental layer material such as graphite. The compounds maintained at liquid helium temperatures and the atomic hydrogen is collected on the surfaces of the layered compound which are exposed during delamination (exfoliation). The strong magnetic field and the low temperature combine to prevent the atoms of hydrogen from recombining to form molecules.

  11. Constructing many atomic models in $\\aleph_1$

    OpenAIRE

    Baldwin, John T.; Laskowski, Michael C.; Shelah, Saharon

    2015-01-01

    We introduce the notion of pseudo-algebraicity to study atomic models of first order theories (equivalently models of a complete sentence of $L_{\\omega_1,\\omega}$. Theorem: Let $T$ be any complete first-order theory in a countable language with an atomic model. If the pseudo-minimal types are not dense, then there are $2^{\\aleph_1}$ pairwise non-isomorphic atomic models of $T$, each of size $\\aleph_1$.

  12. Collective light forces on atoms in resonators

    Energy Technology Data Exchange (ETDEWEB)

    Black, Adam T; Thompson, James K; Vuletic, Vladan [Department of Physics, MIT-Harvard Center for Ultracold Atoms, and Research Laboratory of Electronics, Massachusetts Institute of Technology, Cambridge, MA 02139 (United States)

    2005-05-14

    We study resonator-induced light forces arising from cooperative atom-light interaction. For such collective processes, the force on the sample can be orders of magnitude larger than the sum of conventional light forces on individual atoms. Since resonator-induced light forces can be dissipative even when the incident light is far detuned from atomic transitions, they may be applicable to target particles with a complex level structure.

  13. Revival of Raman coherence of trapped atoms

    Science.gov (United States)

    Afek, Gadi; Coslovsky, Jonathan; Mil, Alexander; Davidson, Nir

    2017-10-01

    We perform Raman spectroscopy of optically trapped noninteracting 87Rb atoms, and observe revivals of the atomic coherence at integer multiples of the trap period. The effect of coherence control methods such as echo and dynamical decoupling is investigated experimentally, analytically, and numerically, along with the effect of the anharmonicity of the trapping potential. The latter is shown to be responsible for incompleteness of the revivals. Coherent Raman control of trapped atoms can be useful in the context of free-oscillation atom interferometry and spatial multimode quantum memory.

  14. Advances in atomic, molecular, and optical physics

    CERN Document Server

    Berman, Paul R; Arimondo, Ennio

    2006-01-01

    Volume 54 of the Advances Series contains ten contributions, covering a diversity of subject areas in atomic, molecular and optical physics. The article by Regal and Jin reviews the properties of a Fermi degenerate gas of cold potassium atoms in the crossover regime between the Bose-Einstein condensation of molecules and the condensation of fermionic atom pairs. The transition between the two regions can be probed by varying an external magnetic field. Sherson, Julsgaard and Polzik explore the manner in which light and atoms can be entangled, with applications to quantum information processing

  15. Nanophotonic cavity QED with individually trapped atoms

    Science.gov (United States)

    Dordevic, Tamara; Samutpraphoot, Polnop; Bernien, Hannes; Ocola, Paloma; Schwartz, Sylvain; Vuletic, Vladan; Senko, Crystal; Lukin, Mikhail

    2017-04-01

    The realization of strong interactions between single photons and single atoms is a central theme in quantum optics and an essential prerequisite for future quantum applications such as quantum networks. We achieve such interactions by using a hybrid approach in which we couple individually trapped atoms to nanophotonic crystal cavities. Here we present our methods for trapping and cooling two atoms near a nanophotonic cavity and our progress towards preparing an entangled state of two atoms mediated by the cavity photons. Our experiment aims at demonstrating scalable and efficient quantum gates with applications in integrated quantum networks.

  16. Atomic and molecular beams production and collimation

    CERN Document Server

    Lucas, Cyril Bernard

    2013-01-01

    Atomic and molecular beams are employed in physics and chemistry experiments and, to a lesser extent, in the biological sciences. These beams enable atoms to be studied under collision-free conditions and allow the study of their interaction with other atoms, charged particles, radiation, and surfaces. Atomic and Molecular Beams: Production and Collimation explores the latest techniques for producing a beam from any substance as well as from the dissociation of hydrogen, oxygen, nitrogen, and the halogens.The book not only provides the basic expressions essential to beam design but also offers

  17. Big Atoms for Small Children: Building Atomic Models from Common Materials to Better Visualize and Conceptualize Atomic Structure

    Science.gov (United States)

    Cipolla, Laura; Ferrari, Lia A.

    2016-01-01

    A hands-on approach to introduce the chemical elements and the atomic structure to elementary/middle school students is described. The proposed classroom activity presents Bohr models of atoms using common and inexpensive materials, such as nested plastic balls, colored modeling clay, and small-sized pasta (or small plastic beads).

  18. Conduction of molecular electronic devices: qualitative insights through atom-atom polarizabilities.

    Science.gov (United States)

    Stuyver, T; Fias, S; De Proft, F; Fowler, P W; Geerlings, P

    2015-03-07

    The atom-atom polarizability and the transmission probability at the Fermi level, as obtained through the source-and-sink-potential method for every possible configuration of contacts simultaneously, are compared for polycyclic aromatic compounds. This comparison leads to the conjecture that a positive atom-atom polarizability is a necessary condition for transmission to take place in alternant hydrocarbons without non-bonding orbitals and that the relative transmission probability for different configurations of the contacts can be predicted by analyzing the corresponding atom-atom polarizability. A theoretical link between the two considered properties is derived, leading to a mathematical explanation for the observed trends for transmission based on the atom-atom polarizability.

  19. Atom-atom interactions around the band edge of a photonic crystal waveguide.

    Science.gov (United States)

    Hood, Jonathan D; Goban, Akihisa; Asenjo-Garcia, Ana; Lu, Mingwu; Yu, Su-Peng; Chang, Darrick E; Kimble, H J

    2016-09-20

    Tailoring the interactions between quantum emitters and single photons constitutes one of the cornerstones of quantum optics. Coupling a quantum emitter to the band edge of a photonic crystal waveguide (PCW) provides a unique platform for tuning these interactions. In particular, the cross-over from propagating fields [Formula: see text] outside the bandgap to localized fields [Formula: see text] within the bandgap should be accompanied by a transition from largely dissipative atom-atom interactions to a regime where dispersive atom-atom interactions are dominant. Here, we experimentally observe this transition by shifting the band edge frequency of the PCW relative to the [Formula: see text] line of atomic cesium for [Formula: see text] atoms trapped along the PCW. Our results are the initial demonstration of this paradigm for coherent atom-atom interactions with low dissipation into the guided mode.

  20. Sub-atom shot noise Faraday imaging of ultracold atom clouds

    Science.gov (United States)

    Kristensen, M. A.; Gajdacz, M.; Pedersen, P. L.; Klempt, C.; Sherson, J. F.; Arlt, J. J.; Hilliard, A. J.

    2017-02-01

    We demonstrate that a dispersive imaging technique based on the Faraday effect can measure the atom number in a large, ultracold atom cloud with a precision below the atom shot noise level. The minimally destructive character of the technique allows us to take multiple images of the same cloud, which enables sub-atom shot noise measurement precision of the atom number and allows for an in situ determination of the measurement precision. We have developed a noise model that quantitatively describes the noise contributions due to photon shot noise in the detected light and the noise associated with single atom loss. This model contains no free parameters and is calculated through an analysis of the fluctuations in the acquired images. For clouds containing N∼ 5× {10}6 atoms, we achieve a precision more than a factor of two below the atom shot noise level.

  1. Experimental realization of suspended atomic chains composed of different atomic species

    Energy Technology Data Exchange (ETDEWEB)

    Bettini, Jefferson; Ugarte, Daniel [Laboratorio Nacional de Luz Sincrotron (LNLS), Campinas, SP (Brazil); Sato, Fernando; Galvao, Douglas Soares [Universidade Estadual de Campinas (UNICAMP), SP (Brazil). Inst. de Fisica Gleb Wataghin; Coura, Pablo Zimmerman; Dantas, Socrates de Oliveira [Universidade Federal de Juiz de Fora (UFJF), MG (Brazil). Inst. de Ciencias Exatas. Dept. de Fisica

    2006-07-01

    We report high resolution transmission electron microscopy (HRTEM) and molecular dynamics results of the first experimental test of suspended atomic chains composed of different atomic species formed from spontaneous stretching of metallic nanowires. (author)

  2. Three-dimensional atom localization via electromagnetically induced transparency in a three-level atomic system.

    Science.gov (United States)

    Wang, Zhiping; Cao, Dewei; Yu, Benli

    2016-05-01

    We present a new scheme for three-dimensional (3D) atom localization in a three-level atomic system via measuring the absorption of a weak probe field. Owing to the space-dependent atom-field interaction, the position probability distribution of the atom can be directly determined by measuring the probe absorption. It is found that, by properly varying the parameters of the system, the probability of finding the atom in 3D space can be almost 100%. Our scheme opens a promising way to achieve high-precision and high-efficiency 3D atom localization, which provides some potential applications in laser cooling or atom nano-lithography via atom localization.

  3. Complex patterning by vertical interchange atom manipulation using atomic force microscopy.

    Science.gov (United States)

    Sugimoto, Yoshiaki; Pou, Pablo; Custance, Oscar; Jelinek, Pavel; Abe, Masayuki; Perez, Ruben; Morita, Seizo

    2008-10-17

    The ability to incorporate individual atoms in a surface following predetermined arrangements may bring future atom-based technological enterprises closer to reality. Here, we report the assembling of complex atomic patterns at room temperature by the vertical interchange of atoms between the tip apex of an atomic force microscope and a semiconductor surface. At variance with previous methods, these manipulations were produced by exploring the repulsive part of the short-range chemical interaction between the closest tip-surface atoms. By using first-principles calculations, we clarified the basic mechanisms behind the vertical interchange of atoms, characterizing the key atomistic processes involved and estimating the magnitude of the energy barriers between the relevant atomic configurations that leads to these manipulations.

  4. Cumulative atomic multipole moments complement any atomic charge model to obtain more accurate electrostatic properties

    Science.gov (United States)

    Sokalski, W. A.; Shibata, M.; Ornstein, R. L.; Rein, R.

    1992-01-01

    The quality of several atomic charge models based on different definitions has been analyzed using cumulative atomic multipole moments (CAMM). This formalism can generate higher atomic moments starting from any atomic charges, while preserving the corresponding molecular moments. The atomic charge contribution to the higher molecular moments, as well as to the electrostatic potentials, has been examined for CO and HCN molecules at several different levels of theory. The results clearly show that the electrostatic potential obtained from CAMM expansion is convergent up to R-5 term for all atomic charge models used. This illustrates that higher atomic moments can be used to supplement any atomic charge model to obtain more accurate description of electrostatic properties.

  5. PREFACE: Atom-surface scattering Atom-surface scattering

    Science.gov (United States)

    Miret-Artés, Salvador

    2010-08-01

    It has been a privilege and a real pleasure to organize this special issue or festschrift in the general field of atom-surface scattering (and its interaction) in honor of J R Manson. This is a good opportunity and an ideal place to express our deep gratitude to one of the leaders in this field for his fundamental and outstanding scientific contributions. J R Manson, or Dick to his friends and colleagues, is one of the founding fathers, together with N Cabrera and V Celli, of the 'Theory of surface scattering and detection of surface phonons'. This is the title of the very well-known first theoretical paper by Dick published in Physical Review Letters in 1969. My first meeting with Dick was around twenty years ago in Saclay. J Lapujoulade organized a small group seminar about selective adsorption resonances in metal vicinal surfaces. We discussed this important issue in surface physics and many other things as if we had always known each other. This familiarity and warm welcome struck me from the very beginning. During the coming years, I found this to be a very attractive aspect of his personality. During my stays in Göttingen, we had the opportunity to talk widely about science and life at lunch or dinner time, walking or cycling. During these nice meetings, he showed, with humility, an impressive cultural background. It is quite clear that his personal opinions about history, religion, politics, music, etc, come from considering and analyzing them as 'open dynamical systems'. In particular, with good food and better wine in a restaurant or at home, a happy cheerful soirée is guaranteed with him, or even with only a good beer or espresso, and an interesting conversation arises naturally. He likes to listen before speaking. Probably not many people know his interest in tractors. He has an incredible collection of very old tractors at home. In one of my visits to Clemson, he showed me the collection, explaining to me in great detail, their technical properties

  6. Resonant quantum transitions in trapped antihydrogen atoms.

    Science.gov (United States)

    Amole, C; Ashkezari, M D; Baquero-Ruiz, M; Bertsche, W; Bowe, P D; Butler, E; Capra, A; Cesar, C L; Charlton, M; Deller, A; Donnan, P H; Eriksson, S; Fajans, J; Friesen, T; Fujiwara, M C; Gill, D R; Gutierrez, A; Hangst, J S; Hardy, W N; Hayden, M E; Humphries, A J; Isaac, C A; Jonsell, S; Kurchaninov, L; Little, A; Madsen, N; McKenna, J T K; Menary, S; Napoli, S C; Nolan, P; Olchanski, K; Olin, A; Pusa, P; Rasmussen, C Ø; Robicheaux, F; Sarid, E; Shields, C R; Silveira, D M; Stracka, S; So, C; Thompson, R I; van der Werf, D P; Wurtele, J S

    2012-03-07

    The hydrogen atom is one of the most important and influential model systems in modern physics. Attempts to understand its spectrum are inextricably linked to the early history and development of quantum mechanics. The hydrogen atom's stature lies in its simplicity and in the accuracy with which its spectrum can be measured and compared to theory. Today its spectrum remains a valuable tool for determining the values of fundamental constants and for challenging the limits of modern physics, including the validity of quantum electrodynamics and--by comparison with measurements on its antimatter counterpart, antihydrogen--the validity of CPT (charge conjugation, parity and time reversal) symmetry. Here we report spectroscopy of a pure antimatter atom, demonstrating resonant quantum transitions in antihydrogen. We have manipulated the internal spin state of antihydrogen atoms so as to induce magnetic resonance transitions between hyperfine levels of the positronic ground state. We used resonant microwave radiation to flip the spin of the positron in antihydrogen atoms that were magnetically trapped in the ALPHA apparatus. The spin flip causes trapped anti-atoms to be ejected from the trap. We look for evidence of resonant interaction by comparing the survival rate of trapped atoms irradiated with microwaves on-resonance to that of atoms subjected to microwaves that are off-resonance. In one variant of the experiment, we detect 23 atoms that survive in 110 trapping attempts with microwaves off-resonance (0.21 per attempt), and only two atoms that survive in 103 attempts with microwaves on-resonance (0.02 per attempt). We also describe the direct detection of the annihilation of antihydrogen atoms ejected by the microwaves.

  7. Clarifying atomic weights: A 2016 four-figure table of standard and conventional atomic weights

    Science.gov (United States)

    Coplen, Tyler B.; Meyers, Fabienne; Holden, Norman E.

    2017-01-01

    To indicate that atomic weights of many elements are not constants of nature, in 2009 and 2011 the Commission on Isotopic Abundances and Atomic Weights (CIAAW) of the International Union of Pure and Applied Chemistry (IUPAC) replaced single-value standard atomic weight values with atomic weight intervals for 12 elements (hydrogen, lithium, boron, carbon, nitrogen, oxygen, magnesium, silicon, sulfur, chlorine, bromine, and thallium); for example, the standard atomic weight of nitrogen became the interval [14.00643, 14.00728]. CIAAW recognized that some users of atomic weight data only need representative values for these 12 elements, such as for trade and commerce. For this purpose, CIAAW provided conventional atomic weight values, such as 14.007 for nitrogen, and these values can serve in education when a single representative value is needed, such as for molecular weight calculations. Because atomic weight values abridged to four figures are preferred by many educational users and are no longer provided by CIAAW as of 2015, we provide a table containing both standard atomic weight values and conventional atomic weight values abridged to four figures for the chemical elements. A retrospective review of changes in four-digit atomic weights since 1961 indicates that changes in these values are due to more accurate measurements over time or to the recognition of the impact of natural isotopic fractionation in normal terrestrial materials upon atomic weight values of many elements. Use of the unit “u” (unified atomic mass unit on the carbon mass scale) with atomic weight is incorrect because the quantity atomic weight is dimensionless, and the unit “amu” (atomic mass unit on the oxygen scale) is an obsolete term: Both should be avoided.

  8. Atomic Force Microscope Mediated Chromatography

    Science.gov (United States)

    Anderson, Mark S.

    2013-01-01

    The atomic force microscope (AFM) is used to inject a sample, provide shear-driven liquid flow over a functionalized substrate, and detect separated components. This is demonstrated using lipophilic dyes and normal phase chromatography. A significant reduction in both size and separation time scales is achieved with a 25-micron-length column scale, and one-second separation times. The approach has general applications to trace chemical and microfluidic analysis. The AFM is now a common tool for ultra-microscopy and nanotechnology. It has also been demonstrated to provide a number of microfluidic functions necessary for miniaturized chromatography. These include injection of sub-femtoliter samples, fluidic switching, and sheardriven pumping. The AFM probe tip can be used to selectively remove surface layers for subsequent microchemical analysis using infrared and tip-enhanced Raman spectroscopy. With its ability to image individual atoms, the AFM is a remarkably sensitive detector that can be used to detect separated components. These diverse functional components of microfluidic manipulation have been combined in this work to demonstrate AFM mediated chromatography. AFM mediated chromatography uses channel-less, shear-driven pumping. This is demonstrated with a thin, aluminum oxide substrate and a non-polar solvent system to separate a mixture of lipophilic dyes. In conventional chromatographic terms, this is analogous to thin-layer chromatography using normal phase alumina substrate with sheardriven pumping provided by the AFM tip-cantilever mechanism. The AFM detection of separated components is accomplished by exploiting the variation in the localized friction of the separated components. The AFM tip-cantilever provides the mechanism for producing shear-induced flows and rapid pumping. Shear-driven chromatography (SDC) is a relatively new concept that overcomes the speed and miniaturization limitations of conventional liquid chromatography. SDC is based on a

  9. Advances in atomic physics: Four decades of contribution of the Cairo University - Atomic Physics Group.

    Science.gov (United States)

    El-Sherbini, Tharwat M

    2015-09-01

    In this review article, important developments in the field of atomic physics are highlighted and linked to research works the author was involved in himself as a leader of the Cairo University - Atomic Physics Group. Starting from the late 1960s - when the author first engaged in research - an overview is provided of the milestones in the fascinating landscape of atomic physics.

  10. Atomic parity violation and the HERA anomaly

    OpenAIRE

    Giusti, Leonardo; Strumia, Alessandro

    1997-01-01

    We show that the two scenarios able to explain the HERA anomaly --- a new leptoquark coupling or a new contact interaction --- predict new contributions to atomic parity violation. These corrections are sufficiently large and different that a feasible reduction in the dominant atomic theory uncertainty could give some hint in favour of one of the two scenarios.

  11. Photoassociation of cold metastable helium atoms

    NARCIS (Netherlands)

    Woestenenk, G.R.

    2001-01-01

    During the last decades the study of cold atoms has grown in a great measure. Research in this field has been made possible due to the development of laser cooling and trapping techniques. We use laser cooling to cool helium atoms down to a temperature of 1 mK and we are able to

  12. Ionisation of atomic hydrogen by positron impact

    Science.gov (United States)

    Spicher, Gottfried; Olsson, Bjorn; Raith, Wilhelm; Sinapius, Guenther; Sperber, Wolfgang

    1990-01-01

    With the crossed beam apparatus the relative impact-ionization cross section of atomic hydrogen by positron impact was measured. A layout of the scattering region is given. The first measurements on the ionization of atomic hydrogen by positron impact are also given.

  13. Studies in Composing Hydrogen Atom Wavefunctions

    DEFF Research Database (Denmark)

    Putnam, Lance Jonathan; Kuchera-Morin, JoAnn; Peliti, Luca

    2015-01-01

    We present our studies in composing elementary wavefunctions of a hydrogen-like atom and identify several relationships between physical phenomena and musical composition that helped guide the process. The hydrogen-like atom accurately describes some of the fundamental quantum mechanical phenomen...

  14. Relativistic atomic physics at the SSC

    Energy Technology Data Exchange (ETDEWEB)

    NONE

    1990-12-31

    This report discusses the following proposed work for relativistic atomic physics at the Superconducting Super Collider: Beam diagnostics; atomic physics research; staffing; education; budget information; statement concerning matching funds; description and justification of major items of equipment; statement of current and pending support; and assurance of compliance.

  15. Electron-Atom Collisions in Gases

    Science.gov (United States)

    Kraftmakher, Yaakov

    2013-01-01

    Electron-atom collisions in gases are an aspect of atomic physics. Three experiments in this field employing a thyratron are described: (i) the Ramsauer-Townsend effect, (ii) the excitation and ionization potentials of xenon and (iii) the ion-electron recombination after interrupting the electric discharge.

  16. Mechanism of single atom switch on silicon

    DEFF Research Database (Denmark)

    Quaade, Ulrich; Stokbro, Kurt; Thirstrup, C.

    1998-01-01

    We demonstrate single atom switch on silicon which operates by displacement of a hydrogen atom on the silicon (100) surface at room temperature. We find two principal effects by which the switch is controlled: a pronounced maximum of the switching probability as function of sample bias...

  17. Calculated Atomic Volumes of the Actinide Metals

    DEFF Research Database (Denmark)

    Skriver, H.; Andersen, O. K.; Johansson, B.

    1979-01-01

    The equilibrium atomic volume is calculated for the actinide metals. It is possible to account for the localization of the 5f electrons taking place in americium.......The equilibrium atomic volume is calculated for the actinide metals. It is possible to account for the localization of the 5f electrons taking place in americium....

  18. Antihydrogen atoms may have been drifters

    CERN Multimedia

    Reich, Eugenie Samuel

    2003-01-01

    "It is a mystery of cosmic proportions: why is the universe filled with matter and not antimatter? Physicists hoping to find the answer have been left scratching their heads this week by an analysis which claims that some antihydrogen atoms created last year may not be normal antiatoms after all. Instead, they may sit on the blurry line between atoms and plasma" (1 page)

  19. Magnetic field modulation spectroscopy of rubidium atoms

    Indian Academy of Sciences (India)

    phase-sensitive detection of the signal, thereby paving the way for very high sensitive measurement in the parts per billion (PPB) levels [4]. On the other hand, the saturation. FMS (SFMS) can be used as a very precise frequency reference in experiments involving laser-cooled atoms, frequency standards as in atomic clock, ...

  20. Single atom adhesion in optimized gold nanojunctions

    NARCIS (Netherlands)

    Trouwborst, M. L.; Huisman, E. H.; Bakker, F. L.; van der Molen, S. J.; van Wees, B. J.

    2008-01-01

    We study the interaction between single apex atoms in a metallic contact, using the break junction geometry. By carefully training our samples, we create stable junctions in which no further atomic reorganization takes place. This allows us to study the relation between the so-called jump out of

  1. Monte Carlo calculations of atoms and molecules

    Science.gov (United States)

    Schmidt, K. E.; Moskowitz, J. W.

    1986-06-01

    The variational and Green's function Monte Carlo (GFMC) methods can treat many interesting atomic and molecular problems. These methods can give chemical accuracy for up to 10 or so electrons. The various implementations of the GFMC method, including the domain Green's function method and the short-time approximation, are discussed. Results are presented for several representative atoms and molecules.

  2. Atomic displacements in bcc dilute alloys

    Indian Academy of Sciences (India)

    Home; Journals; Pramana – Journal of Physics; Volume 68; Issue 4. Atomic displacements in bcc ... metal (TM) dilute alloys. We have calculated the atomic displacements in bcc (V, Cr, Fe, Nb, Mo, Ta and W) transition metals (TMs) due to 3d, 4d and 5d TMs at the substitutional site using the Kanzaki lattice static method.

  3. Cold-atom Inertial Sensor without Deadtime

    CERN Document Server

    Fang, Bess; Savoie, Denis; Venon, Bertrand; Alzar, Carlos L Garrido; Geiger, Remi; Landragin, Arnaud

    2016-01-01

    We report the operation of a cold-atom inertial sensor in a joint interrogation scheme, where we simultaneously prepare a cold-atom source and operate an atom interferometer in order to eliminate dead times. Noise aliasing and dead times are consequences of the sequential operation which is intrinsic to cold-atom atom interferometers. Both phenomena have deleterious effects on the performance of these sensors. We show that our continuous operation improves the short-term sensitivity of atom interferometers, by demonstrating a record rotation sensitivity of $100$ nrad.s$^{-1}/\\sqrt{\\rm Hz}$ in a cold-atom gyroscope of $11$ cm$^2$ Sagnac area. We also demonstrate a rotation stability of $1$ nrad.s$^{-1}$ after $10^4$ s of integration, improving previous results by an order of magnitude. We expect that the continuous operation will allow cold-atom inertial sensors with long interrogation time to reach their full sensitivity, determined by the quantum noise limit.

  4. Advances in atomic, molecular, and optical physics

    CERN Document Server

    Bederson, Benjamin

    1993-01-01

    Advances in Atomic, Molecular, and Optical Physics, established in 1965, continues its tradition of excellence with Volume 32, published in honor of Founding Editor Sir David Bates upon his retirement as editorof the series. This volume presents reviews of topics related to the applications of atomic and molecular physics to atmospheric physics and astrophysics.

  5. Rotary-atomizer electric power generator

    NARCIS (Netherlands)

    Nguyen, Trieu; Tran, Tuan; de Boer, Hans L.; van den Berg, Albert; Eijkel, Jan C.T.

    2015-01-01

    We report experimental and theoretical results on a ballistic energy-conversion method based on a rotary atomizer working with a droplet acceleration-deceleration cycle. In a rotary atomizer, liquid is fed onto the center of a rotating flat surface, where it spreads out under the action of the

  6. Programmable solid state atom sources for nanofabrication

    Science.gov (United States)

    Han, Han; Imboden, Matthias; Stark, Thomas; Del Corro, Pablo G.; Pardo, Flavio; Bolle, Cristian A.; Lally, Richard W.; Bishop, David J.

    2015-06-01

    In this paper we discuss the development of a MEMS-based solid state atom source that can provide controllable atom deposition ranging over eight orders of magnitude, from ten atoms per square micron up to hundreds of atomic layers, on a target ~1 mm away. Using a micron-scale silicon plate as a thermal evaporation source we demonstrate the deposition of indium, silver, gold, copper, iron, aluminum, lead and tin. Because of their small sizes and rapid thermal response times, pulse width modulation techniques are a powerful way to control the atomic flux. Pulsing the source with precise voltages and timing provides control in terms of when and how many atoms get deposited. By arranging many of these devices into an array, one has a multi-material, programmable solid state evaporation source. These micro atom sources are a complementary technology that can enhance the capability of a variety of nano-fabrication techniques.In this paper we discuss the development of a MEMS-based solid state atom source that can provide controllable atom deposition ranging over eight orders of magnitude, from ten atoms per square micron up to hundreds of atomic layers, on a target ~1 mm away. Using a micron-scale silicon plate as a thermal evaporation source we demonstrate the deposition of indium, silver, gold, copper, iron, aluminum, lead and tin. Because of their small sizes and rapid thermal response times, pulse width modulation techniques are a powerful way to control the atomic flux. Pulsing the source with precise voltages and timing provides control in terms of when and how many atoms get deposited. By arranging many of these devices into an array, one has a multi-material, programmable solid state evaporation source. These micro atom sources are a complementary technology that can enhance the capability of a variety of nano-fabrication techniques. Electronic supplementary information (ESI) available: A document containing further information about device characterization

  7. Atomic clusters with addressable complexity

    Science.gov (United States)

    Wales, David J.

    2017-02-01

    A general formulation for constructing addressable atomic clusters is introduced, based on one or more reference structures. By modifying the well depths in a given interatomic potential in favour of nearest-neighbour interactions that are defined in the reference(s), the potential energy landscape can be biased to make a particular permutational isomer the global minimum. The magnitude of the bias changes the resulting potential energy landscape systematically, providing a framework to produce clusters that should self-organise efficiently into the target structure. These features are illustrated for small systems, where all the relevant local minima and transition states can be identified, and for the low-energy regions of the landscape for larger clusters. For a 55-particle cluster, it is possible to design a target structure from a transition state of the original potential and to retain this structure in a doubly addressable landscape. Disconnectivity graphs based on local minima that have no direct connections to a lower minimum provide a helpful way to visualise the larger databases. These minima correspond to the termini of monotonic sequences, which always proceed downhill in terms of potential energy, and we identify them as a class of biminimum. Multiple copies of the target cluster are treated by adding a repulsive term between particles with the same address to maintain distinguishable targets upon aggregation. By tuning the magnitude of this term, it is possible to create assemblies of the target cluster corresponding to a variety of structures, including rings and chains.

  8. ``Effervescent'' Atomization in two dimensions

    Science.gov (United States)

    Lhuissier, Henri; Villermaux, Emmanuel

    2011-11-01

    A planar Savart water sheet uniformly seeded with small air bubbles in large surface concentration is studied as a model experiment of the so-called ``effervescent'' atomization process. This two-dimensional setup allows for a quantitative observation of all the steps of the sheet disintegration into a collection of disjointed droplets. The bubbles are heterogeneous nucleation sites which puncture the sheet forming growing holes. The dynamics of the holes opening competes with the simultaneous nucleation rate of new holes in a statistically stationary fashion. The liquid constitutive of the sheet is then transitorily concentrated into a web of ligaments of various lengths and diameters, at the junction between adjacent holes. Their break-up produces the final spray. We provide a complete description of the ligaments web statistics in the case where nucleation is synchronous, and show that the drop size dispersion from the breakup of a single ligament is responsible for the shape of the resulting overall spray drop size distribution.

  9. Atomic Data for UV Astronomy

    Science.gov (United States)

    Nave, Gillian

    2017-06-01

    Spectral lines of iron-group elements are observed in a wide variety of astrophysical objects including A- and B- type stars, the interstellar medium, quasi-stellar objects, and absorption spectra from quasi-stellar objects. Although lines of Fe II, Cr II and Ni II often dominate these spectra, even relatively low abundance elements such as Sc II can be important as their abundance can be significantly higher in some objects. In order to understand these spectra it is necessary to obtain and analyze high-resolution, high signal-to-noise ratio laboratory spectra to obtain accurate wavelengths and energy levels for all of the singly-ionized elements from scandium through nickel. For many years, the atomic spectroscopy groups at the National Institute of Standards and Technology (NIST), USA and Imperial College London, UK, have been recording high-resolution spectra of iron-group elements using Fourier transform (FT) and grating spectroscopy in order to complete their analyses. This has resulted comprehensive analyses of Fe II and Cr II from below 100 nm to 5000 nm, covering almost all of the region in which allowed lines of these spectra are typically observed in astronomical objects. Analysis of spectra of V II, Ti II and Co II recorded in less comprehensive regions using FT spectroscopy have also been published. I shall present our current work to extend the observations and analysis of Co II and Ti II to shorter wavelengths, and our comprehensive analyses of Mn II, Ni II, and Sc II.

  10. Atomic magnetometer for human magnetoencephalograpy.

    Energy Technology Data Exchange (ETDEWEB)

    Schwindt, Peter; Johnson, Cort N.

    2010-12-01

    We have developed a high sensitivity (<5 fTesla/{radical}Hz), fiber-optically coupled magnetometer to detect magnetic fields produced by the human brain. This is the first demonstration of a noncryogenic sensor that could replace cryogenic superconducting quantum interference device (SQUID) magnetometers in magnetoencephalography (MEG) and is an important advance in realizing cost-effective MEG. Within the sensor, a rubidium vapor is optically pumped with 795 laser light while field-induced optical rotations are measured with 780 nm laser light. Both beams share a single optical axis to maximize simplicity and compactness. In collaboration with neuroscientists at The Mind Research Network in Albuquerque, NM, the evoked responses resulting from median nerve and auditory stimulation were recorded with the atomic magnetometer and a commercial SQUID-based MEG system with signals comparing favorably. Multi-sensor operation has been demonstrated with two AMs placed on opposite sides of the head. Straightforward miniaturization would enable high-density sensor arrays for whole-head magnetoencephalography.

  11. Engineering quantum hyperentangled states in atomic systems

    Science.gov (United States)

    Nawaz, Mehwish; -Islam, Rameez-ul; Abbas, Tasawar; Ikram, Manzoor

    2017-11-01

    Hyperentangled states have boosted many quantum informatics tasks tremendously due to their high information content per quantum entity. Until now, however, the engineering and manipulation of such states were limited to photonic systems only. In present article, we propose generating atomic hyperentanglement involving atomic internal states as well as atomic external momenta states. Hypersuperposition, hyperentangled cluster, Bell and Greenberger–Horne–Zeilinger states are engineered deterministically through resonant and off-resonant Bragg diffraction of neutral two-level atoms. Based on the characteristic parameters of the atomic Bragg diffraction, such as comparatively large interaction times and spatially well-separated outputs, such decoherence resistant states are expected to exhibit good overall fidelities and offer the evident benefits of full controllability, along with extremely high detection efficiency, over the counterpart photonic states comprised entirely of flying qubits.

  12. Laser controlled atom source for optical clocks

    Science.gov (United States)

    Kock, Ole; He, Wei; Świerad, Dariusz; Smith, Lyndsie; Hughes, Joshua; Bongs, Kai; Singh, Yeshpal

    2016-11-01

    Precision timekeeping has been a driving force in innovation, from defining agricultural seasons to atomic clocks enabling satellite navigation, broadband communication and high-speed trading. We are on the verge of a revolution in atomic timekeeping, where optical clocks promise an over thousand-fold improvement in stability and accuracy. However, complex setups and sensitivity to thermal radiation pose limitations to progress. Here we report on an atom source for a strontium optical lattice clock which circumvents these limitations. We demonstrate fast (sub 100 ms), cold and controlled emission of strontium atomic vapours from bulk strontium oxide irradiated by a simple low power diode laser. Our results demonstrate that millions of strontium atoms from the vapour can be captured in a magneto-optical trap (MOT). Our method enables over an order of magnitude reduction in scale of the apparatus. Future applications range from satellite clocks testing general relativity to portable clocks for inertial navigation systems and relativistic geodesy.

  13. High data rate atom interferometric device

    Science.gov (United States)

    Biedermann, Grant; McGuinness, Hayden James Evans; Rakholia, Akash

    2015-07-21

    A light-pulse atomic interferometry (LPAI) apparatus is provided. The LPAI apparatus comprises a vessel, two sets of magnetic coils configured to magnetically confine an atomic vapor in two respective magneto-optical traps (MOTs) within the vessel when activated, and an optical system configured to irradiate the atomic vapor within the vessel with laser radiation that, when suitably tuned, can launch atoms previously confined in each of the MOTs toward the other MOT. In embodiments, the magnetic coils are configured to produce a magnetic field that is non-zero at the midpoint between the traps. In embodiments, the time-of-flight of the launched atoms from one MOT to the other is 12 ms or less. In embodiments, the MOTs are situated approximately 36 mm apart. In embodiments, the apparatus is configured to activate the magnetic coils according to a particular temporal magnetic field gradient profile.

  14. A new approach to entangling neutral atoms.

    Energy Technology Data Exchange (ETDEWEB)

    Lee, Jongmin [Sandia National Lab. (SNL-NM), Albuquerque, NM (United States); Martin, Michael J. [Sandia National Lab. (SNL-NM), Albuquerque, NM (United States); Jau, Yuan-Yu [Sandia National Lab. (SNL-NM), Albuquerque, NM (United States); Deutsch, Ivan H. [Sandia National Lab. (SNL-NM), Albuquerque, NM (United States); Biedermann, Grant W. [Sandia National Lab. (SNL-NM), Albuquerque, NM (United States)

    2016-11-01

    Our team has developed a new approach to entangling neutral atoms with a Rydberg-dressed interaction. Entangling neutral atoms is an essential key of quantum technologies such as quantum computation, many-body quantum simulation, and high-precision atomic sensors . The demonstrated Rydberg-dressed protocol involves adiabatically imposing a light shift on the ground state by coupling an excited Rydberg state with a tuned laser field. Using this technique, we have demonstrated a strong and tunable dipole - dipole interaction between two individually trapped atoms with energy shifts of order 1 MHz, which has been challenging to achieve in other protocols . During this program, we experimentally demonstrated Bell-state entanglement and the isomorphism to the Jaynes - Cumming model of a Rydberg-dressed two-atom system. Our theoretical calculations of a CPHASE quantum logic gate and arbitrary Dicke state quantum control in this system encourage further work.

  15. Atomic focusing by quantum fields: Entanglement properties

    Energy Technology Data Exchange (ETDEWEB)

    Paz, I.G. da [Departamento de Física, Universidade Federal do Piauí, Campus Ministro Petrônio Portela, CEP 64049-550, Teresina, PI (Brazil); Frazão, H.M. [Universidade Federal do Piauí, Campus Profa. Cinobelina Elvas, CEP 64900-000, Bom Jesus, PI (Brazil); Departamento de Física, Instituto de Ciências Exatas, Universidade Federal de Minas Gerais, Caixa Postal 702, Belo Horizonte, MG 30123-970 (Brazil); Nemes, M.C. [Departamento de Física, Instituto de Ciências Exatas, Universidade Federal de Minas Gerais, Caixa Postal 702, Belo Horizonte, MG 30123-970 (Brazil); Peixoto de Faria, J.G. [Departamento de Física e Matemática, Centro Federal de Educação Tecnológica de Minas Gerais, Av. Amazonas 7675, Belo Horizonte, MG 30510-000 (Brazil)

    2014-04-01

    The coherent manipulation of the atomic matter waves is of great interest both in science and technology. In order to study how an atom optic device alters the coherence of an atomic beam, we consider the quantum lens proposed by Averbukh et al. [1] to show the discrete nature of the electromagnetic field. We extend the analysis of this quantum lens to the study of another essentially quantum property present in the focusing process, i.e., the atom–field entanglement, and show how the initial atomic coherence and purity are affected by the entanglement. The dynamics of this process is obtained in closed form. We calculate the beam quality factor and the trace of the square of the reduced density matrix as a function of the average photon number in order to analyze the coherence and purity of the atomic beam during the focusing process.

  16. A continuous cold atomic beam interferometer

    Energy Technology Data Exchange (ETDEWEB)

    Xue, Hongbo [State Key Laboratory of Precision Measurement Technology and Instruments, Tsinghua University, Beijing 100084 (China); Joint Institute for Measurement Science, Tsinghua University, Beijing 100084 (China); Center for Space Science and Applied Research, Chinese Academy of Sciences, Beijing 100190 (China); Feng, Yanying, E-mail: yyfeng@tsinghua.edu.cn; Yan, Xueshu; Jiang, Zhikun [State Key Laboratory of Precision Measurement Technology and Instruments, Tsinghua University, Beijing 100084 (China); Joint Institute for Measurement Science, Tsinghua University, Beijing 100084 (China); Chen, Shu [Joint Institute for Measurement Science, Tsinghua University, Beijing 100084 (China); Key Laboratory of Instrumentation Science, North University of China, Taiyuan 030051 (China); Wang, Xiaojia [College of Mechanical Engineering, Taiyuan University of Technology, Taiyuan 030024 (China); Zhou, Zhaoying [State Key Laboratory of Precision Measurement Technology and Instruments, Tsinghua University, Beijing 100084 (China)

    2015-03-07

    We demonstrate an atom interferometer that uses a laser-cooled continuous beam of {sup 87}Rb atoms having velocities of 10–20 m/s. With spatially separated Raman beams to coherently manipulate the atomic wave packets, Mach–Zehnder interference fringes are observed at an interference distance of 2L = 19 mm. The apparatus operates within a small enclosed area of 0.07 mm{sup 2} at a bandwidth of 190 Hz with a deduced sensitivity of 7.8×10{sup −5} rad/s/√(Hz) for rotations. Using a low-velocity continuous atomic source in an atom interferometer enables high sampling rates and bandwidths without sacrificing sensitivity and compactness, which are important for applications in real dynamic environments.

  17. Atom trap loss, elastic collisions, and technology

    Science.gov (United States)

    Booth, James

    2012-10-01

    The study of collisions and scattering has been one of the most productive approaches for modern physics, illuminating the fundamental structure of crystals, surfaces, atoms, and sub-atomic particles. In the field of cold atoms, this is no less true: studies of cold atom collisions were essential to the production of quantum degenerate matter, the formation of cold molecules, and so on. Over the past few years it has been my delight to investigate elastic collisions between cold atoms trapped in either a magneto-optical trap (MOT) or a magnetic trap with hot, background gas in the vacuum environment through the measurement of the loss of atoms from the trap. Motivated by the goal of creating cold atom-based technology, we are deciphering what the trapped atoms are communicating about their environment through the observed loss rate. These measurements have the advantages of being straightforward to implement and they provide information about the underlying, fundamental inter-atomic processes. In this talk I will present some of our recent work, including the observation of the trap depth dependence on loss rate for argon-rubidium collisions. The data follow the computed loss rate curve based on the long-range Van der Waals interaction between the two species. The implications of these findings are exciting: trap depths can be determined from the trap loss measurement under controlled background density conditions; observation of trap loss rate in comparison to models for elastic, inelastic, and chemical processes can lead to improved understanding and characterization of these fundamental interactions; finally the marriage of cold atoms with collision modeling offers the promise of creating a novel pressure sensor and pressure standard for the high and ultra-high vacuum regime.

  18. 0.75 atoms improve the clock signal of 10,000 atoms

    DEFF Research Database (Denmark)

    Kruse, I.; Lange, K.; Peise, Jan

    2017-01-01

    Since the pioneering work of Ramsey, atom interferometers are employed for precision metrology, in particular to measure time and to realize the second. In a classical interferometer, an ensemble of atoms is prepared in one of the two input states, whereas the second one is left empty. In this case.......75 atoms to improve the clock sensitivity of 10,000 atoms by 2.05 dB. The SQL poses a significant limitation for today's microwave fountain clocks, which serve as the main time reference. We evaluate the major technical limitations and challenges for devising a next generation of fountain clocks based...... on atomic squeezed vacuum....

  19. Spatial Imaging of Strongly Interacting Rydberg Atoms

    Science.gov (United States)

    Thaicharoen, Nithiwadee

    The strong interactions between Rydberg excitations can result in spatial correlations between the excitations. The ability to control the interaction strength and the correlations between Rydberg atoms is applicable in future technological implementations of quantum computation. In this thesis, I investigates how both the character of the Rydberg-Rydberg interactions and the details of the excitation process affect the nature of the spatial correlations and the evolution of those correlations in time. I first describes the experimental apparatus and methods used to perform high-magnification Rydberg-atom imaging, as well as three experiments in which these methods play an important role. The obtained Rydberg-atom positions reveal the correlations in the many-body Rydberg-atom system and their time dependence with sub-micron spatial resolution. In the first experiment, atoms are excited to a Rydberg state that experiences a repulsive van der Waals interaction. The Rydberg excitations are prepared with a well-defined initial separation, and the effect of van der Waals forces is observed by tracking the interatomic distance between the Rydberg atoms. The atom trajectories and thereby the interaction coefficient C6 are extracted from the pair correlation functions of the Rydberg atom positions. In the second experiment, the Rydberg atoms are prepared in a highly dipolar state by using adiabatic state transformation. The atom-pair kinetics that follow from the strong dipole-dipole interactions are observed. The pair correlation results provide the first direct visualization of the electric-dipole interaction and clearly exhibit its anisotropic nature. In both the first and the second experiment, results of semi-classical simulations of the atom-pair trajectories agree well with the experimental data. In the analysis, I use energy conservation and measurements of the initial positions and the terminal velocities of the atom pairs to extract the C6 and C 3 interaction

  20. Atom and Bond Fukui Functions and Matrices: A Hirshfeld-I Atoms-in-Molecule Approach.

    Science.gov (United States)

    Oña, Ofelia B; De Clercq, Olivier; Alcoba, Diego R; Torre, Alicia; Lain, Luis; Van Neck, Dimitri; Bultinck, Patrick

    2016-09-19

    The Fukui function is often used in its atom-condensed form by isolating it from the molecular Fukui function using a chosen weight function for the atom in the molecule. Recently, Fukui functions and matrices for both atoms and bonds separately were introduced for semiempirical and ab initio levels of theory using Hückel and Mulliken atoms-in-molecule models. In this work, a double partitioning method of the Fukui matrix is proposed within the Hirshfeld-I atoms-in-molecule framework. Diagonalizing the resulting atomic and bond matrices gives eigenvalues and eigenvectors (Fukui orbitals) describing the reactivity of atoms and bonds. The Fukui function is the diagonal element of the Fukui matrix and may be resolved in atom and bond contributions. The extra information contained in the atom and bond resolution of the Fukui matrices and functions is highlighted. The effect of the choice of weight function arising from the Hirshfeld-I approach to obtain atom- and bond-condensed Fukui functions is studied. A comparison of the results with those generated by using the Mulliken atoms-in-molecule approach shows low correlation between the two partitioning schemes. © 2016 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  1. Theoretical Calculation of Absolute Radii of Atoms and Ions. Part 1. The Atomic Radii

    Directory of Open Access Journals (Sweden)

    Raka Biswas

    2002-02-01

    Full Text Available Abstract. A set of theoretical atomic radii corresponding to the principal maximum in the radial distribution function, 4πr2R2 for the outermost orbital has been calculated for the ground state of 103 elements of the periodic table using Slater orbitals. The set of theoretical radii are found to reproduce the periodic law and the Lother Meyer’s atomic volume curve and reproduce the expected vertical and horizontal trend of variation in atomic size in the periodic table. The d-block and f-block contractions are distinct in the calculated sizes. The computed sizes qualitatively correlate with the absolute size dependent properties like ionization potentials and electronegativity of elements. The radii are used to calculate a number of size dependent periodic physical properties of isolated atoms viz., the diamagnetic part of the atomic susceptibility, atomic polarizability and the chemical hardness. The calculated global hardness and atomic polarizability of a number of atoms are found to be close to the available experimental values and the profiles of the physical properties computed in terms of the theoretical atomic radii exhibit their inherent periodicity. A simple method of computing the absolute size of atoms has been explored and a large body of known material has been brought together to reveal how many different properties correlate with atomic size.

  2. Optimization of electrothermal atomization parameters for simultaneous multielement atomic absorption spectrometry

    Science.gov (United States)

    Harnly, J.M.; Kane, J.S.

    1984-01-01

    The effect of the acid matrix, the measurement mode (height or area), the atomizer surface (unpyrolyzed and pyrolyzed graphite), the atomization mode (from the wall or from a platform), and the atomization temperature on the simultaneous electrothermal atomization of Co, Cr, Cu, Fe, Mn, Mo, Ni, V, and Zn was examined. The 5% HNO3 matrix gave rise to severe irreproducibility using a pyrolyzed tube unless the tube was properly "prepared". The 5% HCl matrix did not exhibit this problem, and no problems were observed with either matrix using an unpyrolized tube or a pyrolyzed platform. The 5% HCl matrix gave better sensitivities with a pyrolyzed tube but the two matrices were comparable for atomization from a platform. If Mo and V are to be analyzed with the other seven elements, a high atomization temperature (2700??C or greater) is necessary regardless of the matrix, the measurement mode, the atomization mode, or the atomizer surface. Simultaneous detection limits (peak height with pyrolyzed tube atomization) were comparable to those of conventional atomic absorption spectrometry using electrothermal atomization above 280 nm. Accuracies and precisions of ??10-15% were found in the 10 to 120 ng mL-1 range for the analysis of NBS acidified water standards.

  3. Coexistence of photonic and atomic Bose-Einstein condensates in ideal atomic gases

    Directory of Open Access Journals (Sweden)

    N. Boichenko

    2015-12-01

    Full Text Available We have studied conditions of photon Bose-Einstein condensate formation that is in thermodynamic equilibrium with ideal gas of two-level Bose atoms below the degeneracy temperature. Equations describing thermodynamic equilibrium in the system were formulated; critical temperatures and densities of photonic and atomic gas subsystems were obtained analytically. Coexistence conditions of these photonic and atomic Bose-Einstein condensates were found. There was predicted the possibility of an abrupt type of photon condensation in the presence of Bose condensate of ground-state atoms: it was shown that the slightest decrease of the temperature could cause a significant gathering of photons in the condensate. This case could be treated as a simple model of the situation known as "stopped light" in cold atomic gas. We also showed how population inversion of atomic levels can be created by lowering the temperature. The latter situation looks promising for light accumulation in atomic vapor at very low temperatures.

  4. Atom localization in 2D for five-level atomic schemes in X-configuration

    Science.gov (United States)

    Raheli, Ali; Hamedi, H. R.; Sahrai, M.

    2015-09-01

    A five-level X-type atomic scheme is proposed to elucidate the two-dimensional (2D) atom localization in sub-wavelength domain by using different coupling situations of the atom with standing wave fields. The scheme is a mixture of two upper V- and lower Λ -type usual three level systems which both are connected at a common intermediate level. The combination of the upper and lower systems can lead to different atom localization patterns as lattice-, chain-, crater-, wave-, and spike-like structures. We discuss how these structures may depend on different coupling conditions of the atom with the standing wave fields. Finally, an experimental implementation for such an atomic model is presented using the 87Rb atoms.

  5. High-dimensional atom localization via spontaneously generated coherence in a microwave-driven atomic system.

    Science.gov (United States)

    Wang, Zhiping; Chen, Jinyu; Yu, Benli

    2017-02-20

    We investigate the two-dimensional (2D) and three-dimensional (3D) atom localization behaviors via spontaneously generated coherence in a microwave-driven four-level atomic system. Owing to the space-dependent atom-field interaction, it is found that the detecting probability and precision of 2D and 3D atom localization behaviors can be significantly improved via adjusting the system parameters, the phase, amplitude, and initial population distribution. Interestingly, the atom can be localized in volumes that are substantially smaller than a cubic optical wavelength. Our scheme opens a promising way to achieve high-precision and high-efficiency atom localization, which provides some potential applications in high-dimensional atom nanolithography.

  6. Life with Four Billion Atoms

    Energy Technology Data Exchange (ETDEWEB)

    Knight, Thomas [Ginkgo Bioworks, Inc.

    2013-04-10

    Today it is commonplace to design and construct single silicon chips with billions of transistors. These are complex systems, difficult (but possible) to design, test, and fabricate. Remarkably, simple living systems can be assembled from a similar number of atoms, most of them in water molecules. In this talk I will present the current status of our attempts at full understanding and complexity reduction of one of the simplest living systems, the free-living bacterial species Mesoplasma florum. This 400 nm diameter cell thrives and replicates every 40 minutes with a genome of only 800 kilobases. Our recent experiments using transposon gene knockouts identified 354 of 683 annotated genes as inessential in laboratory culture when inactivated individually. While a functional redesigned genome will certainly not remove all of those genes, this suggests that roughly half the genome can be removed in an intentional redesign. I will discuss our recent knockout results and methodology, and our future plans for Genome re-engineering using targeted knock-in/knock-out double recombination; whole cell metabolic models; comprehensive whole cell metabolite measurement techniques; creation of plug-and-play metabolic modules for the simplified organism; inherent and engineered biosafety control mechanisms. This redesign is part of a comprehensive plan to lay the foundations for a new discipline of engineering biology. Engineering biological systems requires a fundamentally different viewpoint from that taken by the science of biology. Key engineering principles of modularity, simplicity, separation of concerns, abstraction, flexibility, hierarchical design, isolation, and standardization are of critical importance. The essence of engineering is the ability to imagine, design, model, build, and characterize novel systems to achieve specific goals. Current tools and components for these tasks are primitive. Our approach is to create and distribute standard biological parts

  7. On the energy of electric field in hydrogen atom

    OpenAIRE

    Kornyushin, Yuri

    2009-01-01

    It is shown that hydrogen atom is a unique object in physics having negative energy of electric field, which is present in the atom. This refers also to some hydrogen-type atoms: hydrogen anti-atom, atom composed of proton and antiproton, and positronium.

  8. Structure formation in atom lithography using geometric collimation

    NARCIS (Netherlands)

    Meijer, T.; Beardmore, J.P.; Fabrie, C.G.C.H.M.; van Lieshout, J.P.; Notermans, R.P.M.J.W.; Sang, R.T.; Vredenbregt, E.J.D.; Van Leeuwen, K.A.H.

    2011-01-01

    Atom lithography uses standing wave light fields as arrays of lenses to focus neutral atom beams into line patterns on a substrate. Laser cooled atom beams are commonly used, but an atom beam source with a small opening placed at a large distance from a substrate creates atom beams which are locally

  9. Multiplicity of atomic reconfigurations in an electrochemical Pb single-atom transistor

    Science.gov (United States)

    Xie, F.-Q.; Lin, X.-H.; Gross, A.; Evers, F.; Pauly, F.; Schimmel, Th.

    2017-05-01

    One focus of nanoelectronics research is to exploit the physical limits in size and energy efficiency. Here, we demonstrate a device in the form of a fully metallic atomic-scale transistor based on a lead (Pb) single-atom quantum point contact. The atomic configuration of the point contact determines the conductance of the Pb atomic-scale transistor. The conductance multiplicity of the Pb single-atom transistor has been confirmed by performing switching between an electrically nonconducting "off-state" and conducting "on-states" at 1 G0( G0=2 e2/h , where e is the electron charge, and h Planck's constant), 2.0 G0, 3.0 G0, 1.5 G0, 2.4 G0, 2.7 G0, 2.8 G0, and 5.4 G0, respectively. Our density-functional calculations for various ideal Pb single-atom contacts explain the atomic-configuration-related conductance multiplicity of the Pb single-atom transistor. The performance of the Pb single-atom transistors indicates that both the signatures of atomic valence and conductance quantization play roles in electron transport and bistable reconfiguration. The bistable reconfiguration of the electrode tips is an underlying mechanism in the switching of the Pb atomic-scale transistors. The absolute value of the electrochemical potential applied to the gate electrode is less than 30 mV. This merit suggests Pb [besides silver (Ag)] atomic-scale transistors as potential candidates for the development of electronic circuits with low power consumption. The dimension of the switching unit in the Pb single-atom transistor is in the range of 1 nm, which is much smaller than the projected scaling limit of the gate lengths in silicon transistors (5 nm). Therefore, the metallic single-atom transistors may provide perspectives for electronic applications beyond silicon.

  10. Laser Technology in Commercial Atomic Clocks

    Science.gov (United States)

    Lutwak, R.

    2006-05-01

    Commercial atomic frequency standards (AFS) are deployed in diverse civilian, military, and aerospace applications, ranging from high-precision measurement and calibration to navigation, communications and, of course, timekeeping. Currently, commercially available AFS include magnetically-selected cesium beam frequency standards and hydrogen masers and lamp-pumped rubidium oscillators. Despite the revolution in atomic physics and laboratory-scale AFS brought about by the advent of the tunable laser in the early 1970s, commercial AFS invariably rely on more conventional atomic physics technology developed in the 1950s. The reason for this lack of advancement of commercial AFS technology is the relatively poor reliability and environmental sensitivity of narrow-linewidth single-mode laser sources at atomic resonance wavelengths. Over the past 8 years, Symmetricom, in collaboration with laser manufacturers, has developed specialized laser sources for commercial AFS applications. These laser devices, optimized for high spectral purity and long-term reliability, will enable a new generation of commercial AFS. This talk will briefly describe two laser-based atomic frequency standard development programs at Symmetricom. The Chip-Scale Atomic Clock, two orders of magnitude smaller and lower power than any commercial AFS, will enable atomic timing accuracy in portable battery-powered applications. The Optically-Pumped Cesium Beam Frequency Standard, under development for deployment onboard the GPS-III satellite constellation, will provide enhanced short-term stability and longer lifetime compared to magnetically-selected cesium beam AFS.

  11. Quantum Spin Lenses in Atomic Arrays

    Directory of Open Access Journals (Sweden)

    A. W. Glaetzle

    2017-09-01

    Full Text Available We propose and discuss quantum spin lenses, where quantum states of delocalized spin excitations in an atomic medium are focused in space in a coherent quantum process down to (essentially single atoms. These can be employed to create controlled interactions in a quantum light-matter interface, where photonic qubits stored in an atomic ensemble are mapped to a quantum register represented by single atoms. We propose Hamiltonians for quantum spin lenses as inhomogeneous spin models on lattices, which can be realized with Rydberg atoms in 1D, 2D, and 3D, and with strings of trapped ions. We discuss both linear and nonlinear quantum spin lenses: in a nonlinear lens, repulsive spin-spin interactions lead to focusing dynamics conditional to the number of spin excitations. This allows the mapping of quantum superpositions of delocalized spin excitations to superpositions of spatial spin patterns, which can be addressed by light fields and manipulated. Finally, we propose multifocal quantum spin lenses as a way to generate and distribute entanglement between distant atoms in an atomic lattice array.

  12. Vibration spectra of single atomic nanocontacts

    Energy Technology Data Exchange (ETDEWEB)

    Bourahla, B [Laboratoire de Physique et Chimie Quantique, Departement de Physique, Faculte des Sciences, Universite Mouloud Mammeri de Tizi-Ouzou, 15000 Tizi-Ouzou (Algeria); Khater, A [Laboratoire de Physique de l' Etat Condense UMR 6087, Universite du Maine, 72085 Le Mans (France); Rafil, O [Laboratoire de Physique de l' Etat Condense UMR 6087, Universite du Maine, 72085 Le Mans (France); Tigrine, R [Laboratoire de Physique et Chimie Quantique, Departement de Physique, Faculte des Sciences, Universite Mouloud Mammeri de Tizi-Ouzou, 15000 Tizi-Ouzou (Algeria)

    2006-10-04

    This paper introduces a simple model for an atomic nanocontact, where its mechanical properties are analysed by calculating numerically the local spectral properties at the contact atom and the nearby atoms. The standard methodology for calculating phonon spectral densities is extended to enable the calculation of localized contact modes and local density of states (DOS). The model system considered for the nanocontact consists of two sets of triple parallel semi-infinite atomic chains joined by a single atom in between. The matching method is used, in the harmonic approximation, to calculate the local Green's functions for the irreducible set of sites that constitute the inhomogeneous nanocontact domain. The Green's functions yield the vibration spectra and the DOS for the atomic sites. These are numerically calculated for different cases of elastic hardening and softening of the nanocontact domain. The purpose is to investigate how the local dynamics respond to local changes in the elastic environment. The analysis of the spectra and of the DOS identifies characteristic features and demonstrates the central role of a core subset of these sites for the dynamics of the nanocontact. The system models a situation which may be appropriate for contact atomic force microscopy.

  13. Ps-atom scattering at low energies

    CERN Document Server

    Fabrikant, I I

    2015-01-01

    A pseudopotential for positronium-atom interaction, based on electron-atom and positron-atom phase shifts, is constructed, and the phase shifts for Ps-Kr and Ps-Ar scattering are calculated. This approach allows us to extend the Ps-atom cross sections, obtained previously in the impulse approximation [Phys. Rev. Lett. 112, 243201 (2014)], to energies below the Ps ionization threshold. Although experimental data are not available in this low-energy region, our results describe well the tendency of the measured cross sections to drop with decreasing velocity at $v<1$ a.u. Our results show that the effect of the Ps-atom van der Waals interaction is weak compared to the polarization interaction in electron-atom and positron-atom scattering. As a result, the Ps scattering length for both Ar and Kr is positive, and the Ramsauer-Townsend minimum is not observed for Ps scattering from these targets. This makes Ps scattering quite different from electron scattering in the low-energy region, in contrast to the inter...

  14. Could Atomic clocks be affected by neutrinos?

    CERN Document Server

    Hanafi, Hanaa

    2016-01-01

    An atomic clock is a clock device that uses an electronic transition frequency of the electromagnetic spectrum of atoms as a frequency standard in order to derive a time standard since time is the reciprocal of frequency. If the electronic transition frequencies are in an "optical region", we are talking in this case about optical atomic clocks. If they are in an "microwave region" these atomic clocks are made of the metallic element cesium so they are called Cesium atomic clocks. Atomic clocks are the most accurate time and frequency standards known despite the different perturbations that can affect them, a lot of researches were made in this domain to show how the transitions can be different for different type of perturbations..Since atomic clocks are very sensitive devices, based on coherent states (A coherent state tends to loose coherence after interacting). One question can arise (from a lot of questions) which is why cosmic neutrinos are not affecting these clocks? The answer to this question requir...

  15. Storing Information in Single Atom Magnets

    Science.gov (United States)

    Natterer, Fabian; Yang, Kai; Paul, William; Wilke, Philip; Choi, Taeyoung; Greber, Thomas; Heinrich, Andreas J.; Lutz, Chris P.

    In a Gedankenexperiment about shrinking the size of a magnetic bit, the single atom magnet is the natural limit. Previous experimental efforts reached a size of few atoms per individually addressable magnetic bit, but a recent report of magnetic remanence for ensembles of holmium (Ho) atoms on magnesium oxide (MgO) promised a path toward stable magnetic bits at the atomic limit. It remained unclear, however, how to access the individual magnetic centers. Here we demonstrate the reading and writing of individual Ho atoms on MgO, and show that they independently retain their magnetic information over several hours. We read the Ho states by tunnel magnetoresistance and write with current pulses using a scanning tunneling microscope. We prove magnetic origin of the long-lived states by single-atom electron spin resonance (ESR) and measure a large magnetic moment of (10.1 +/-0.1) Bohr magnetons. The high magnetic stability combined with electrical reading and writing shows that single atom magnetic memory has become a physical reality. SNF Ambizione Grant PZ00P2 167965.

  16. The ALADDIN atomic physics database system

    Science.gov (United States)

    Hulse, Russell A.

    1990-05-01

    ALADDIN is an atomic physics database system which has been developed in order to provide a broadly-based standard medium for the exchange and management of atomic data. ALADDIN consists of a data format definition together with supporting software for both interactive searches as well as for access to the data by plasma modeling and other codes. 8AB The ALADDIN system is designed to offer maximum flexibility in the choice of data representations and labeling schemes, so as to support a wide range of atomic physics data types and allow natural evolution and modification of the database as needs change. Associated dictionary files are included in the ALADDIN system for data documentation. The importance of supporting the widest possible user community was also central to be ALADDIN design, leading to the use of straightforward text files with concatentated data entries for the file structure, and the adoption of strict FORTRAN 77 code for the supporting software. This will allow ready access to the ALADDIN system on the widest range of scientific computers, and easy interfacing with FORTRAN modeling codes, user developed atomic physics codes and database, etc. This supporting software consists of the ALADDIN interactive searching and data display code, together with the ALPACK subroutine package which provides ALADDIN datafile searching and data retrieval capabilities to user's codes. ALADDIN has been adopted as the standard international atomic physics data exchange format for magnetic confinement fusion applications by the International Atomic Energy Agency (IAEA). Entry of critically evaluated atomic data sets into ALADDIN format is to be coordinated by the IAEA atomic and Molecular Data Unit, which will also coordinate long-term development and distribution of updated software and documentation. The increasingly widespread adoption of the ALADDIN data format can be expected to greatly facilitate access to atomic data both within and outside of this original

  17. 1984 Bibliography of atomic and molecular processes

    Energy Technology Data Exchange (ETDEWEB)

    Barnett, C.F.; Gilbody, H.B.; Gregory, D.C.; Griffin, P.M.; Havener, C.C.; Howard, A.M.; Kirkpatrick, M.I.; McDaniel, E.W.; Meyer, F.W.; Morgan, T.J. (comps.)

    1985-04-01

    This annotated bibliography includes papers on atomic and molecular processes published during 1984. Sources include scientific journals, conference proceedings, and books. Each entry is designated by one or more of the 114 categories of atomic and molecular processes used by the Controlled Fusion Atomic Data Center, Oak Ridge National Laboratory to classify data. Also indicated is whether the work was experimental or theoretical, what energy range was covered, what reactants were investigated, and the country of origin of the first author. Following the bibliographical listing, the entries are indexed according to the categories and according to reactants within each subcategory.

  18. Cold Light from Hot Atoms and Molecules

    Science.gov (United States)

    Lister, Graeme; Curry, John J.

    2011-05-01

    The introduction of rare earth atoms and molecules into lighting discharges led to great advances in efficacy of these lamps. Atoms such as Dy, Ho and Ce provide excellent radiation sources for lighting applications, with rich visible spectra, such that a suitable combination of these elements can provide high quality white light. Rare earth molecules have also proved important in enhancing the radiation spectrum from phosphors in fluorescent lamps. This paper reviews some of the current aspects of lighting research, particularly rare earth chemistry and radiation, and the associated fundamental atomic and molecular data.

  19. 1985 bibliography of atomic and molecular processes

    Energy Technology Data Exchange (ETDEWEB)

    Barnett, C.F.; Gilbody, H.B.; Gregory, D.C.; Griffin, P.M.; Havener, C.C.; Howald, A.M.; Kirkpatrick, M.I.; McDaniel, E.W.; Meyer, F.W.; Morgan, T.J. (comps.)

    1986-06-01

    This annotated bibliography includes papers on atomic and molecular processes published during 1985. Sources include scientific journals, conference proceedings, and books. Each entry is designated by one or more of the 114 categories of atomic and molecular processes used by the Controlled Fusion Atomic Data Center, Oak Ridge National Laboratory to classify data. Also indicated is whether the work was experimental or theoretical, what energy range was covered, what reactants were investigated, and the country of origin of the first author. Following the bibliographical listing, the entries are indexed according to the categories and according to reactants within each subcategory.

  20. 1982 bibliography of atomic and molecular processes

    Energy Technology Data Exchange (ETDEWEB)

    Barnett, C.F.; Crandall, D.H.; Gilbody, H.B.; Gregory, D.C.; Kirkpatrick, M.I.; McDaniel, E.W.; McKnight, R.H.; Meyer, F.W.; Morgan, T.J.; Phaneuf, R.A. (comps.)

    1984-05-01

    This annotated bibliography includes papers on atomic and molecular processes published during 1982. Sources include scientific journals, conference proceedings, and books. Each entry is designated by one or more of the 114 categories of atomic and molecular processes used by the Controlled Fusion Atomic Data Center, Oak Ridge National Laboratory to classify data. Also indicated is whether the work was experimental or theoretical, what energy range was covered, what reactants were investigated, and the country of origin of the first author. Following the bibliographical listing, the entries are indexed according to the categories and according to reactants within each subcategory.

  1. Vortices and turbulence in trapped atomic condensates

    Science.gov (United States)

    White, Angela C.; Anderson, Brian P.; Bagnato, Vanderlei S.

    2014-01-01

    After more than a decade of experiments generating and studying the physics of quantized vortices in atomic gas Bose–Einstein condensates, research is beginning to focus on the roles of vortices in quantum turbulence, as well as other measures of quantum turbulence in atomic condensates. Such research directions have the potential to uncover new insights into quantum turbulence, vortices, and superfluidity and also explore the similarities and differences between quantum and classical turbulence in entirely new settings. Here we present a critical assessment of theoretical and experimental studies in this emerging field of quantum turbulence in atomic condensates. PMID:24704880

  2. Bibliography of atomic and molecular processes, 1983

    Energy Technology Data Exchange (ETDEWEB)

    Barnett, C.F.; Crandall, D.H.; Gilbody, H.B.; Gregory, D.C.; Kirkpatrick, M.I.; McDaniel, E.W.; McKnight, R.H.; Meyer, F.W.; Morgan, T.J.; Phaneuf, R.A. (comps.)

    1984-10-01

    This annotated bibliography includes papers on atomic and molecular processes published during 1983. Sources include scientific journals, conference proceedings, and books. Each entry is designated by one or more of the 114 categories of atomic and molecular processes used by the Controlled Fusion Atomic Data Center, Oak Ridge National Laboratory to classify data. Also indicated is whether the work was experimental or theoretical, what energy range was covered, what reactants were investigated, and the country of origin of the first author. Following the bibliographical listing, the entries are indexed according to the categories and according to reactants within each subcategory.

  3. The Manhattan Project: Making the atomic bomb

    Energy Technology Data Exchange (ETDEWEB)

    Gosling, F.G.

    1994-09-01

    This article is a short history of the origins and development of the American atomic bomb program during World War II. Beginning with the scientific developments of the pre-war years, the monograph details the role of US government in conducting a secret, nationwide enterprise that took science from the laboratory and into combat with an entirely new type of weapon. The monograph concludes with a discussion of the immediate postwar period, the debate over the Atomic Energy Act of 1946, and the founding of the Atomic Energy Commission.

  4. The Britannica guide to the atom

    CERN Document Server

    Gregersen, Erik

    2011-01-01

    Common to all matter and its smallest and most fundamental unit, the atom determines the properties of a substance and how it responds to other materials and stimuli. Dividing the atom further reveals several smaller particles whose activity forms the heart of nuclear physics. Readers will discover the structure of the atom as well as the ways in which its electrons, protons, and neutrons facilitate both radioactivity and nuclear reactions, both of which have been crucial to technological advancements since the 20th century.

  5. Scattering theory of molecules, atoms and nuclei

    CERN Document Server

    Canto, L Felipe

    2012-01-01

    The aim of the book is to give a coherent and comprehensive account of quantum scattering theory with applications to atomic, molecular and nuclear systems. The motivation for this is to supply the necessary theoretical tools to calculate scattering observables of these many-body systems. Concepts which are seemingly different for atomic/molecular scattering from those of nuclear systems, are shown to be the same once physical units such as energy and length are diligently clarified. Many-body resonances excited in nuclear systems are the same as those in atomic systems and come under the name

  6. Anomalous atomic volume of alpha-Pu

    DEFF Research Database (Denmark)

    Kollar, J.; Vitos, Levente; Skriver, Hans Lomholt

    1997-01-01

    We have performed full charge-density calculations for the equilibrium atomic volumes of the alpha-phase light actinide metals using the local density approximation (LDA) and the generalized gradient approximation (GGA). The average deviation between the experimental and the GGA atomic radii is 1.......3%. The comparison between the LDA and GGA results show that the anomalously large atomic volume of alpha-Pu relative to alpha-Np can be ascribed to exchange-correlation effects connected with the presence of low coordinated sites in the structure where the f electrons are close to the onset of localization...

  7. Plasmas applied atomic collision physics, v.2

    CERN Document Server

    Barnett, C F

    1984-01-01

    Applied Atomic Collision Physics, Volume 2: Plasmas covers topics on magnetically confined plasmas. The book starts by providing the history of fusion research and describing the various approaches in both magnetically and inertially confined plasmas. The text then gives a general discussion of the basic concepts and properties in confinement and heating of a plasma. The theory of atomic collisions that result in excited quantum states, particularly highly ionized impurity atoms; and diverse diagnostic topics such as emission spectra, laser scattering, electron cyclotron emission, particle bea

  8. Atomic White-Out: Enabling Atomic Circuitry through Mechanically Induced Bonding of Single Hydrogen Atoms to a Silicon Surface.

    Science.gov (United States)

    Huff, Taleana R; Labidi, Hatem; Rashidi, Mohammad; Koleini, Mohammad; Achal, Roshan; Salomons, Mark H; Wolkow, Robert A

    2017-09-26

    We report the mechanically induced formation of a silicon-hydrogen covalent bond and its application in engineering nanoelectronic devices. We show that using the tip of a noncontact atomic force microscope (NC-AFM), a single hydrogen atom could be vertically manipulated. When applying a localized electronic excitation, a single hydrogen atom is desorbed from the hydrogen-passivated surface and can be transferred to the tip apex, as evidenced from a unique signature in frequency shift curves. In the absence of tunnel electrons and electric field in the scanning probe microscope junction at 0 V, the hydrogen atom at the tip apex is brought very close to a silicon dangling bond, inducing the mechanical formation of a silicon-hydrogen covalent bond and the passivation of the dangling bond. The functionalized tip was used to characterize silicon dangling bonds on the hydrogen-silicon surface, which was shown to enhance the scanning tunneling microscope contrast, and allowed NC-AFM imaging with atomic and chemical bond contrasts. Through examples, we show the importance of this atomic-scale mechanical manipulation technique in the engineering of the emerging technology of on-surface dangling bond based nanoelectronic devices.

  9. Understanding Atomic Structure: Is There a More Direct and Compelling Connection between Atomic Line Spectra and the Quantization of an Atom's Energy?

    Science.gov (United States)

    Rittenhouse, Robert C.

    2015-01-01

    The "atoms first" philosophy, adopted by a growing number of General Chemistry textbook authors, places greater emphasis on atomic structure as a key to a deeper understanding of the field of chemistry. A pivotal concept needed to understand the behavior of atoms is the restriction of an atom's energy to specific allowed values. However,…

  10. Atom-by-atom structural and chemical analysis by annular dark-field electron microscopy.

    Science.gov (United States)

    Krivanek, Ondrej L; Chisholm, Matthew F; Nicolosi, Valeria; Pennycook, Timothy J; Corbin, George J; Dellby, Niklas; Murfitt, Matthew F; Own, Christopher S; Szilagyi, Zoltan S; Oxley, Mark P; Pantelides, Sokrates T; Pennycook, Stephen J

    2010-03-25

    Direct imaging and chemical identification of all the atoms in a material with unknown three-dimensional structure would constitute a very powerful general analysis tool. Transmission electron microscopy should in principle be able to fulfil this role, as many scientists including Feynman realized early on. It images matter with electrons that scatter strongly from individual atoms and whose wavelengths are about 50 times smaller than an atom. Recently the technique has advanced greatly owing to the introduction of aberration-corrected optics. However, neither electron microscopy nor any other experimental technique has yet been able to resolve and identify all the atoms in a non-periodic material consisting of several atomic species. Here we show that annular dark-field imaging in an aberration-corrected scanning transmission electron microscope optimized for low voltage operation can resolve and identify the chemical type of every atom in monolayer hexagonal boron nitride that contains substitutional defects. Three types of atomic substitutions were found and identified: carbon substituting for boron, carbon substituting for nitrogen, and oxygen substituting for nitrogen. The substitutions caused in-plane distortions in the boron nitride monolayer of about 0.1 A magnitude, which were directly resolved, and verified by density functional theory calculations. The results demonstrate that atom-by-atom structural and chemical analysis of all radiation-damage-resistant atoms present in, and on top of, ultra-thin sheets has now become possible.

  11. First-Order Quantum Phase Transition for Dicke Model Induced by Atom-Atom Interaction

    Science.gov (United States)

    Zhao, Xiu-Qin; Liu, Ni; Liang, Jiu-Qing

    2017-05-01

    In this article, we use the spin coherent state transformation and the ground state variational method to theoretically calculate the ground function. In order to consider the influence of the atom-atom interaction on the extended Dicke model’s ground state properties, the mean photon number, the scaled atomic population and the average ground energy are displayed. Using the self-consistent field theory to solve the atom-atom interaction, we discover the system undergoes a first-order quantum phase transition from the normal phase to the superradiant phase, but a famous Dicke-type second-order quantum phase transition without the atom-atom interaction. Meanwhile, the atom-atom interaction makes the phase transition point shift to the lower atom-photon collective coupling strength. Supported by the National Natural Science Foundation of China under Grant Nos. 11275118, 11404198, 91430109, 61505100, 51502189, and the Scientific and Technological Innovation Programs of Higher Education Institutions in Shanxi Province (STIP) under Grant No. 2014102, and the Launch of the Scientific Research of Shanxi University under Grant No. 011151801004, and the National Fundamental Fund of Personnel Training under Grant No. J1103210. The Natural Science Foundation of Shanxi Province under Grant No. 2015011008

  12. Suprathermal oxygen atoms in the Martian upper atmosphere: Contribution of the proton and hydrogen atom precipitation

    Science.gov (United States)

    Shematovich, V. I.

    2017-07-01

    This is a study of the kinetics and transport of hot oxygen atoms in the transition region (from the thermosphere to the exosphere) of the Martian upper atmosphere. It is assumed that the source of the hot oxygen atoms is the transfer of momentum and energy in elastic collisions between thermal atmospheric oxygen atoms and the high-energy protons and hydrogen atoms precipitating onto the Martian upper atmosphere from the solar-wind plasma. The distribution functions of suprathermal oxygen atoms by the kinetic energy are calculated. It is shown that the exosphere is populated by a large number of suprathermal oxygen atoms with kinetic energies up to the escape energy 2 eV; i.e., a hot oxygen corona is formed around Mars. The transfer of energy from the precipitating solar-wind plasma protons and hydrogen atoms to the thermal oxygen atoms leads to the formation of an additional nonthermal escape flux of atomic oxygen from the Martian atmosphere. The precipitation-induced escape flux of hot oxygen atoms may become dominant under the conditions of extreme solar events, such as solar flares and coronal mass ejections, as shown by recent observations onboard NASA's MAVEN spacecraft (Jakosky et al., 2015).

  13. Giant atom smasher on hunt for "Sparticles"

    CERN Multimedia

    Moskowitz, Clara

    2008-01-01

    "Squarks, photinos, selectrons, neutralinos: these are just a few types of supersymmetrice particles, a special brand of particle that may be created when the world's most powerful atom smasher goes online this spring." (1 page)

  14. Stochastic analysis/synthesis using sinusoidal atoms

    DEFF Research Database (Denmark)

    Jensen, Kristoffer

    2008-01-01

    This work proposes a method for re-synthesizing music for use in perceptual experiments regarding structural changes and in music creation. Atoms are estimated from music audio, modelled in a stochastic model, and re-synthesized from the model pa- rameters. The atoms are found by splitting...... sinusoids into short segments, and modelled into amplitude and envelope shape, frequency, time and duration. A simple model for creating envelopes with percussive, sustained or crescendo shape is presented. Single variable and joint probability density functions are created from the atom parameters and used...... to re-create sounds with the same distribution of the atoms parameters. A novel method for visualization music, the musigram, permits a better understanding of the re- synthesized sounds....

  15. A History of the Atomic Energy Commission

    Science.gov (United States)

    Buck, Alice L.

    1983-07-01

    This pamphlet traces the history of the US Atomic Energy Commission's twenty-eight year stewardship of the Nation's nuclear energy program, from the signing of the Atomic Energy Act on August 1, 1946 to the signing of the Energy Reorganization Act on October 11, 1974. The Commission's early concentration on the military atom produced sophisticated nuclear weapons for the Nation's defense and made possible the creation of a fleet of nuclear submarines and surface ships. Extensive research in the nuclear sciences resulted in the widespread application of nuclear technology for scientific, medical and industrial purposes, while the passage of the Atomic Energy Act of 1954 made possible the development of a nuclear industry, and enabled the United States to share the new technology with other nations.

  16. An Introduction to Atomic Layer Deposition

    Science.gov (United States)

    Dwivedi, Vivek H.

    2017-01-01

    Atomic Layer Deposition has been instrumental in providing a deposition method for multiple space flight applications. It is well known that ALD is a cost effective nanoadditive-manufacturing technique that allows for the conformal coating of substrates with atomic control in a benign temperature and pressure environment. Through the introduction of paired precursor gases, thin films can be deposited on a myriad of substrates from flat surfaces to those with significant topography. By providing atomic layer control, where single layers of atoms can be deposited, the fabrication of metal transparent films, precise nano-laminates, and coatings of nano-channels, pores and particles is achievable. The feasibility of this technology for NASA line of business applications range from thermal systems, optics, sensors, to environmental protection. An overview of this technology will be presented.

  17. Imaging enzyme kinetics at atomic resolution

    OpenAIRE

    Spence, John; Lattman, Eaton

    2016-01-01

    Serial crystallography at a synchrotron has been used to obtain time-resolved atomic resolution density maps of enzyme catalysis in copper nitrite reductase. Similar XFEL studies, intended to out-run radiation damage, will also soon appear.

  18. Frederick National Laboratory's Contribution to ATOM | FNLCR

    Science.gov (United States)

    As a founding member organization of ATOM, the Frederick National Laboratory will contribute scientific expertise in precision oncology, computational chemistry and cancer biology, as well as support for open sharing of data sets and predictive model

  19. Highly Dense Isolated Metal Atom Catalytic Sites

    DEFF Research Database (Denmark)

    Chen, Yaxin; Kasama, Takeshi; Huang, Zhiwei

    2015-01-01

    Atomically dispersed noble-metal catalysts with highly dense active sites are promising materials with which to maximise metal efficiency and to enhance catalytic performance; however, their fabrication remains challenging because metal atoms are prone to sintering, especially at a high metal...... loading. A dynamic process of formation of isolated metal atom catalytic sites on the surface of the support, which was achieved starting from silver nanoparticles by using a thermal surface-mediated diffusion method, was observed directly by using in situ electron microscopy and in situ synchrotron X......-ray diffraction. A combination of electron microscopy images with X-ray absorption spectra demonstrated that the silver atoms were anchored on five-fold oxygen-terminated cavities on the surface of the support to form highly dense isolated metal active sites, leading to excellent reactivity in catalytic oxidation...

  20. Simulations of atomic-scale sliding friction

    DEFF Research Database (Denmark)

    Sørensen, Mads Reinholdt; Jacobsen, Karsten Wedel; Stoltze, Per

    1996-01-01

    Simulation studies of atomic-scale sliding friction have been performed for a number of tip-surface and surface-surface contacts consisting of copper atoms. Both geometrically very simple tip-surface structures and more realistic interface necks formed by simulated annealing have been studied....... Kinetic friction is observed to be caused by atomic-scale Stick and slip which occurs by nucleation and subsequent motion of dislocations preferably between close-packed {111} planes. Stick and slip seems ro occur in different situations. For single crystalline contacts without grain boundaries...... pinning of atoms near the boundary of the interface and is therefore more easily observed for smaller contacts. Depending on crystal orientation and load, frictional wear can also be seen in the simulations. In particular, for the annealed interface-necks which model contacts created by scanning tunneling...

  1. Atom interferometry using a shaken optical lattice

    Science.gov (United States)

    Weidner, C. A.; Yu, Hoon; Kosloff, Ronnie; Anderson, Dana Z.

    2017-04-01

    We introduce shaken lattice interferometry with atoms trapped in a one-dimensional optical lattice. By phase modulating (shaking) the lattice, we control the momentum state of the atoms. Through a sequence of shaking functions, the atoms undergo an interferometer sequence of splitting, propagation, reflection, reverse propagation, and recombination. Each shaking function in the sequence is optimized with a genetic algorithm to achieve the desired momentum state transitions. As with conventional atom interferometers, the sensitivity of the shaken lattice interferometer increases with interrogation time. The shaken lattice interferometer may also be optimized to sense signals of interest while rejecting others, such as the measurement of an ac inertial signal in the presence of an unwanted dc signal.

  2. Gravitational Wave Detection with Atom Interferometry

    Energy Technology Data Exchange (ETDEWEB)

    Dimopoulos, Savas; /Stanford U., Phys. Dept.; Graham, Peter W.; /SLAC /Stanford U., Phys. Dept.; Hogan, Jason M.; Kasevich, Mark A.; /Stanford U., Phys. Dept.; Rajendran, Surjeet; /SLAC /Stanford U., Phys. Dept.

    2008-01-23

    We propose two distinct atom interferometer gravitational wave detectors, one terrestrial and another satellite-based, utilizing the core technology of the Stanford 10m atom interferometer presently under construction. The terrestrial experiment can operate with strain sensitivity {approx} 10{sup -19}/{radical}Hz in the 1 Hz-10 Hz band, inaccessible to LIGO, and can detect gravitational waves from solar mass binaries out to megaparsec distances. The satellite experiment probes the same frequency spectrum as LISA with better strain sensitivity {approx} 10{sup -20}/{radical}Hz. Each configuration compares two widely separated atom interferometers run using common lasers. The effect of the gravitational waves on the propagating laser field produces the main effect in this configuration and enables a large enhancement in the gravitational wave signal while significantly suppressing many backgrounds. The use of ballistic atoms (instead of mirrors) as inertial test masses improves systematics coming from vibrations and acceleration noise, and reduces spacecraft control requirements.

  3. [Atomic force microscopy involved in protein study].

    Science.gov (United States)

    Lu, Zhengjian; Chen, Guoping; Wang, Jianhua

    2010-06-01

    Atomic force microscopy is a rather new type of nano microscopic technology. It has some advantages, such as high resolution (sub-nano scale); avoidance of special sample preparation; real-time detection of samples under nearly physiological environment; in situ study of samples under water environment; feasibility of investigating physical and chemical properties of samples at molecular level, etc. In recent years, the application of atomic force microscopy in protein study has brought about outstanding achievements. In this paper are introduced the principle and operation modes of atomic force microscopy, also presented are its application in protein imaging, adsorption, folding-and-unfolding, assembly, and single molecular recognition. Additionally, the future application of atomic force microscopy in protein study is prospected.

  4. REVIEW ARTICLE: Fast light in atomic media

    Science.gov (United States)

    Akulshin, Alexander M.; McLean, Russell J.

    2010-10-01

    Atomic media have played a major role in studies of fast light. One of their attractive features is the ability to manipulate experimental parameters to control the dispersive properties that determine the group velocity of a propagating light pulse. We give an overview of the experimental methods, based on both linear and nonlinear atom-light interaction, that have produced superluminal propagation in atomic media, and discuss some of the significant theoretical contributions to the issues of pulse preservation and reconciling faster-than-light propagation and the principle of causality. The comparison of storage of light, enhanced Kerr nonlinearity and efficient wave mixing processes in slow and fast light atomic media illustrates their common and distinct features.

  5. Atomic physics: Cold gases venture into Flatland

    Science.gov (United States)

    Burnett, Keith

    2007-09-01

    Vortex structures have revealed a lot about the nature of three-dimensional Bose-Einstein condensates. They play an even bigger part in two-dimensional cold atomic gases and drive a fundamentally different phase transition.

  6. Jobs in the Atomic Energy Field

    Science.gov (United States)

    Occupational Outlook Quarterly, 1974

    1974-01-01

    According to a recent government survey, employment in privately-owned atomic energy facilities now exceeds employment in government facilities. In this field, engineers, scientists, technicians, and craft workers account for the highest proportion of total employment. (MW)

  7. Quantum Chemical Topology: Knowledgeable atoms in peptides

    Science.gov (United States)

    Popelier, Paul L. A.

    2012-06-01

    The need to improve atomistic biomolecular force fields remains acute. Fortunately, the abundance of contemporary computing power enables an overhaul of the architecture of current force fields, which typically base their electrostatics on fixed atomic partial charges. We discuss the principles behind the electrostatics of a more realistic force field under construction, called QCTFF. At the heart of QCTFF lies the so-called topological atom, which is a malleable box, whose shape and electrostatics changes in response to a changing environment. This response is captured by a machine learning method called Kriging. Kriging directly predicts each multipole moment of a given atom (i.e. the output) from the coordinates of the nuclei surrounding this atom (i.e. the input). This procedure yields accurate interatomic electrostatic energies, which form the basis for future-proof progress in force field design.

  8. A History of the Atomic Energy Commission

    Energy Technology Data Exchange (ETDEWEB)

    Buck, A.L.

    1983-07-01

    This pamphlet traces the history of the US Atomic Energy Commission's twenty-eight year stewardship of the Nation's nuclear energy program, from the signing of the Atomic Energy Act on August 1, 1946 to the signing of the Energy Reorganization Act on October 11, 1974. The Commission's early concentration on the military atom produced sophisticated nuclear weapons for the Nation's defense and made possible the creation of a fleet of nuclear submarines and surface ships. Extensive research in the nuclear sciences resulted in the widespread application of nuclear technology for scientific, medical and industrial purposes, while the passage of the Atomic Energy Act of 1954 made possible the development of a nuclear industry, and enabled the United States to share the new technology with other nations.

  9. Reversible Bergman cyclization by atomic manipulation

    Science.gov (United States)

    Schuler, Bruno; Fatayer, Shadi; Mohn, Fabian; Moll, Nikolaj; Pavliček, Niko; Meyer, Gerhard; Peña, Diego; Gross, Leo

    2016-03-01

    The Bergman cyclization is one of the most fascinating rearrangements in chemistry, with important implications in organic synthesis and pharmacology. Here we demonstrate a reversible Bergman cyclization for the first time. We induced the on-surface transformation of an individual aromatic diradical into a highly strained ten-membered diyne using atomic manipulation and verified the products by non-contact atomic force microscopy with atomic resolution. The diyne and diradical were stabilized by using an ultrathin NaCl film as the substrate, and the diyne could be transformed back into the diradical. Importantly, the diradical and the diyne exhibit different reactivity, electronic, magnetic and optical properties associated with the changes in the bond topology, and spin multiplicity. With this reversible, triggered Bergman cyclization we demonstrated switching on demand between the two reactive intermediates by means of selective C-C bond formation or cleavage, which opens up the field of radical chemistry for on-surface reactions by atomic manipulation.

  10. Quantum physics: Atomic envoy enables molecular control

    Science.gov (United States)

    Campbell, Wes

    2017-05-01

    A technique for manipulating molecules uses an intermediary atom to query a nearby molecule's energy state and produces 'quantum superpositions' of these states, a prerequisite for extremely high-precision spectroscopy. See Letter p.203

  11. Production and detection of cold antihydrogen atoms

    CERN Multimedia

    Amoretti, M; Bonomi, G; Bouchta, A; Bowe, P; Carraro, C; Cesar, C L; Charlton, M; Collier, M; Doser, Michael; Filippini, V; Fine, K S; Fontana, A; Fujiwara, M C; Funakoshi, R; Genova, P; Hangst, J S; Hayano, R S; Holzscheiter, M H; Jørgensen, L V; Lagomarsino, V; Landua, Rolf; Landua, Rolf; Lindelöf, D; Lodi-Rizzini, E; Macri, M; Madsen, N; Manuzio, G; Marchesotti, M; Montagna, P; Pruys, H S; Regenfus, C; Riedler, P; Rochet, J; Rotondi, A; Rouleau, G; Testera, G; Van der Werf, D P; Variola, A; Watson, T L; CERN. Geneva

    2002-01-01

    A theoretical underpinning of the standard model of fundamental particles and interactions is CPT invariance, which requires that the laws of physics be invariant under the combined discrete operations of charge conjugation, parity and time reversal. Antimatter, the existence of which was predicted by Dirac, can be used to test the CPT theorem experimental investigations involving comparisons of particles with antiparticles are numerous. Cold atoms and anti-atoms, such as hydrogen and anti-hydrogen, could form the basis of a new precise test, as CPT invariance implies that they must have the same spectrum. Observations of antihydrogen in small quantities and at high energies have been reported at the European Organization for Nuclear Research (CERN) and at Fermilab, but were not suited to precision comparison measurements. Here we demonstrate the production of antihydrogen atoms at very low energy by mixing trapped antiprotons and positrons in a cryogenic environment. The neutral anti-atoms have been detected...

  12. Atomic resolution images of graphite in air

    Energy Technology Data Exchange (ETDEWEB)

    Grigg, D.A.; Shedd, G.M.; Griffis, D.; Russell, P.E.

    1988-12-01

    One sample used for proof of operation for atomic resolution in STM is highly oriented pyrolytic graphite (HOPG). This sample has been imaged with many different STM`s obtaining similar results. Atomic resolution images of HOPG have now been obtained using an STM designed and built at the Precision Engineering Center. This paper discusses the theoretical predictions and experimental results obtained in imaging of HOPG.

  13. Cesium Atomic Fountain Clocks at NMIJ

    Science.gov (United States)

    2010-11-01

    Wynands and S. Weyers, 2005, “Atomic fountain clocks,” Metrologia , 42, S64-S79. [2] M. Takamoto, F. L. Hong, R. Higashi, et al., 2005, “An optical...beam of laser-cooled cesium atoms,” Physical Review, A 60, R4241-R4244. [13] V. Gerginov, N. Nemitz, S. Weyers, et al., 2010, “Uncertainty evaluation of the caesium fountain clock PTB-CSF2,” Metrologia , 47, 65-79.

  14. Index to the Understanding the Atom Series

    Energy Technology Data Exchange (ETDEWEB)

    None

    1978-01-01

    The U. S. Atomic Energy Commission publishes the Understanding the Atom Series of educational booklets for high school science students and their teachers. This series explains many aspects of nuclear science including its history and applications. Because these 51 booklets cover such a variety of scientific fields, this index was prepared to help the reader find quickly those booklets that contain the information he needs.

  15. A Miniature Wide Band Atomic Magnetometer

    Science.gov (United States)

    2011-12-01

    current circuit is easiest to explain if we at first ignore the capacitors . The reference and the DAC output are combined by R401 and R402 to make...atomic magnetometer CSAC – Chip scale atomic clock DAC – Digital to Analog Converter DARPA – Defense Advanced Research Projects Agency DBR...Transform FPGA – Field Programmable Gate Array GHz – Gigahertz MEMS – Micro-Electro Mechanical System MF – z-component Magnetic Quantum Number, MF MFTFM

  16. Atomization of broad specification aircraft fuels

    Science.gov (United States)

    Skifstad, J. G.; Lefebvre, A. H.

    1980-01-01

    The atomization properties of liquid fuels for the potential use in aircraft gas turbine engines are discussed. The significance of these properties are addressed with respect to the ignition and subsequent combustion behavior of the fuel spray/air mixture. It is shown that the fuel properties which affect the atomization behavior (viscosity, surface tension, and density) are less favorable for the broad specification fuels as compared to with those for conventional fuels.

  17. Atomic Force Microscopy of Biological Membranes

    OpenAIRE

    Frederix, Patrick L.T.M.; Bosshart, Patrick D.; Engel, Andreas

    2009-01-01

    Atomic force microscopy (AFM) is an ideal method to study the surface topography of biological membranes. It allows membranes that are adsorbed to flat solid supports to be raster-scanned in physiological solutions with an atomically sharp tip. Therefore, AFM is capable of observing biological molecular machines at work. In addition, the tip can be tethered to the end of a single membrane protein, and forces acting on the tip upon its retraction indicate barriers that occur during the process...

  18. Tutorial on Atomic Oxygen Effects and Contamination

    Science.gov (United States)

    Miller, Sharon K.

    2017-01-01

    Atomic oxygen is the most predominant specie in low Earth orbit (LEO) and is contained in the upper atmosphere of many other planetary bodies. Formed by photo-dissociation of molecular oxygen, it is highly reactive and energetic enough to break chemical bonds on the surface of many materials and react with them to form either stable or volatile oxides. The extent of the damage for spacecraft depends a lot on how much atomic oxygen arrives at the surface, the energy of the atoms, and the reactivity of the material that is exposed to it. Oxide formation can result in shrinkage, cracking, or erosion which can also result in changes in optical, thermal, or mechanical properties of the materials exposed. The extent of the reaction can be affected by mechanical loading, temperature, and other environmental components such as ultraviolet radiation or charged particles. Atomic oxygen generally causes a surface reaction, but it can scatter under coatings and into crevices causing oxidation much farther into a spacecraft surface or structure than would be expected. Contamination can also affect system performance. Contamination is generally caused by arrival of volatile species that condense on spacecraft surfaces. The volatiles are typically a result of outgassing of materials that are on the spacecraft. Once the volatiles are condensed on a surface, they can then be fixed on the surface by ultraviolet radiation andor atomic oxygen reaction to form stable surface contaminants that can change optical and thermal properties of materials in power systems, thermal systems, and sensors. This tutorial discusses atomic oxygen erosion and contaminate formation, and the effect they have on typical spacecraft materials. Scattering of atomic oxygen, some effects of combined environments and examples of effects of atomic oxygen and contamination on spacecraft systems and components will also be presented.

  19. From heavy ions to exotic atoms

    OpenAIRE

    Indelicato, Paul; Trassinelli, Martino

    2005-01-01

    We review a number of experiments and theoretical calculations on heavy ions and exotic atoms, which aim at providing informations on fundamental interactions. Among those are propositions of experiments for parity violation measurements in heavy ions and high-precision mesurements of He-like transition energies in highly charged ions. We also describe recent experiments on pionic atoms, that make use of highly-charged ion transitions to obtain accurate measurements of strong interaction shif...

  20. Atomic energy levels and Grotrian diagrams

    CERN Document Server

    Bashkin, Stanley

    1975-01-01

    Atomic Energy Levels and Grotrian Diagrams, Volume I: Hydrogen I - Phosphorus XV presents diagrams of various elements that show their energy level and electronic transitions. The book covers the first 15 elements according to their atomic number. The text will be of great use to researchers and practitioners of fields such as astrophysics that requires pictorial representation of the energy levels and electronic transitions of elements.

  1. Atomic and molecular processes in fusion plasmas

    Energy Technology Data Exchange (ETDEWEB)

    Janev, R.K. [International Atomic Energy Agency, Vienna (Austria)

    1997-01-01

    The role of atomic and molecular processes in achieving and maintaining the conditions for thermonuclear burn in a magnetically confined fusion plasma is described. Emphasis is given to the energy balance and power and particle exhaust issues. The most important atomic and molecular processes which affect the radiation losses and impurity transport in the core plasma, the neutral particle transport in the plasma edge and the radiative cooling of divertor plasmas are discussed in greater detail. (author)

  2. A slow gravity compensated atom laser

    DEFF Research Database (Denmark)

    Kleine Büning, G.; Will, J.; Ertmer, W.

    2010-01-01

    We report on a slow guided atom laser beam outcoupled from a Bose–Einstein condensate of 87Rb atoms in a hybrid trap. The acceleration of the atom laser beam can be controlled by compensating the gravitational acceleration and we reach residual accelerations as low as 0.0027 g. The outcoupling...... mechanism allows for the production of a constant flux of 4.5×106 atoms per second and due to transverse guiding we obtain an upper limit for the mean beam width of 4.6 μm. The transverse velocity spread is only 0.2 mm/s and thus an upper limit for the beam quality parameter is M 2=2.5. We demonstrate...... the potential of the long interrogation times available with this atom laser beam by measuring the trap frequency in a single measurement. The small beam width together with the long evolution and interrogation time makes this atom laser beam a promising tool for continuous interferometric measurements....

  3. Cavity electromagnetically induced transparency with Rydberg atoms

    Science.gov (United States)

    Bakar Ali, Abu; Ziauddin

    2018-02-01

    Cavity electromagnetically induced transparency (EIT) is revisited via the input probe field intensity. A strongly interacting Rydberg atomic medium ensemble is considered in a cavity, where atoms behave as superatoms (SAs) under the dipole blockade mechanism. Each atom in the strongly interacting Rydberg atomic medium (87 Rb) follows a three-level cascade atomic configuration. A strong control and weak probe field are employed in the cavity with the ensemble of Rydberg atoms. The features of the reflected and transmitted probe light are studied under the influence of the input probe field intensity. A transparency peak (cavity EIT) is revealed at a resonance condition for small values of input probe field intensity. The manipulation of the cavity EIT is reported by tuning the strength of the input probe field intensity. Further, the phase and group delay of the transmitted and reflected probe light are studied. It is found that group delay and phase in the reflected light are negative, while for the transmitted light they are positive. The magnitude control of group delay in the transmitted and reflected light is investigated via the input probe field intensity.

  4. Optical atomic phase reference and timing

    Science.gov (United States)

    Hollberg, L.; Cornell, E. H.; Abdelrahmann, A.

    2017-06-01

    Atomic clocks based on laser-cooled atoms have made tremendous advances in both accuracy and stability. However, advanced clocks have not found their way into widespread use because there has been little need for such high performance in real-world/commercial applications. The drive in the commercial world favours smaller, lower-power, more robust compact atomic clocks that function well in real-world non-laboratory environments. Although the high-performance atomic frequency references are useful to test Einstein's special relativity more precisely, there are not compelling scientific arguments to expect a breakdown in special relativity. On the other hand, the dynamics of gravity, evidenced by the recent spectacular results in experimental detection of gravity waves by the LIGO Scientific Collaboration, shows dramatically that there is new physics to be seen and understood in space-time science. Those systems require strain measurements at less than or equal to 10-20. As we discuss here, cold atom optical frequency references are still many orders of magnitude away from the frequency stability that should be achievable with narrow-linewidth quantum transitions and large numbers of very cold atoms, and they may be able to achieve levels of phase stability, ΔΦ/Φtotal ≤ 10-20, that could make an important impact in gravity wave science. This article is part of the themed issue 'Quantum technology for the 21st century'.

  5. Effect of atomizer scale and fluid properties on atomization mechanisms and spray characteristics

    Science.gov (United States)

    Waind, Travis

    Atomization is chaos. The breakup of liquid structures by a gas encompasses such a wide range of possible configurations that a definitive mechanism describing breakup in any and all situations is an impossibility. However, when focus is applied, trends can be teased out of experimental data that seem to appropriately describe the action undertaken. These studies sought to better understand atomization, specifically coaxial, two-stream, airblast (or air-assist) atomization in which a central liquid jet is broken up by an annular, high-velocity gas stream. The studies enclosed focused on identifying the effect of changing the atomizer's scale on atomization. While most (but not all) atomization studies only focus on the resulting far-field drop diameters, these studies placed the focus largely on the intermediate structures, in the form of the intact liquid jet (ILJ), while also quantifying the resulting drop diameters. The location and shape of the ILJ constantly change, and on its surface, wavelengths were seen to form and grow, which have been correlated to the resulting drop diameters in previous studies. The studies enclosed herein are unique in that they attempt to apply and explain exiting mechanism-based breakup mechanisms to regimes, fluids, and geometry changes not yet evaluated in the literature. Existing correlations were compared to the experimental data for a range of atomizer geometries, and when they were found lacking, Buckingham-(Pi) theorem was used to develop new correlations for predicting behavior. Additionally, the method developed for the calculation of these parameters for other image sets is included, allowing for easy comparison and value verification. A small-scale, coaxial atomization system was used to atomize water and two silicone oils with air. The atomizers used in these studies had the same general geometry type, but had varying sizes, allowing for the effect of both scale and geometry to be evaluated. These studies quantified

  6. Calibration of atomic trajectories in a large-area dual-atom-interferometer gyroscope

    Science.gov (United States)

    Yao, Zhan-Wei; Lu, Si-Bin; Li, Run-Bing; Luo, Jun; Wang, Jin; Zhan, Ming-Sheng

    2018-01-01

    We propose and demonstrate a method for calibrating atomic trajectories in a large-area dual-atom-interferometer gyroscope. The atom trajectories are monitored by modulating and delaying the Raman transition, and they are precisely calibrated by controlling the laser orientation and the bias magnetic field. To improve the immunity to the gravity effect and the common phase noise, the symmetry and the overlap of two large-area atomic interference loops are optimized by calibrating the atomic trajectories and by aligning the Raman-laser orientations. The dual-atom-interferometer gyroscope is applied in the measurement of the Earth's rotation. The sensitivity is 1.2 ×10-6 rad s -1 Hz-1/2, and the long-term stability is 6.2 ×10-8 rad/s at 2000 s.

  7. HAADF-STEM atom counting in atom probe tomography specimens: Towards quantitative correlative microscopy.

    Science.gov (United States)

    Lefebvre, W; Hernandez-Maldonado, D; Moyon, F; Cuvilly, F; Vaudolon, C; Shinde, D; Vurpillot, F

    2015-12-01

    The geometry of atom probe tomography tips strongly differs from standard scanning transmission electron microscopy foils. Whereas the later are rather flat and thin (atom probe tomography specimens. Based on simulations (electron probe propagation and image simulations), the possibility to apply quantitative high angle annular dark field scanning transmission electron microscopy to of atom probe tomography specimens has been tested. The influence of electron probe convergence and the benefice of deconvolution of electron probe point spread function electron have been established. Atom counting in atom probe tomography specimens is for the first time reported in this present work. It is demonstrated that, based on single projections of high angle annular dark field imaging, significant quantitative information can be used as additional input for refining the data obtained by correlative analysis of the specimen in APT, therefore opening new perspectives in the field of atomic scale tomography. Copyright © 2015 Elsevier B.V. All rights reserved.

  8. Atoms and molecules interacting with light atomic physics for the laser era

    CERN Document Server

    Straten, Peter van der

    2016-01-01

    This in-depth textbook with a focus on atom-light interactions prepares students for research in a fast-growing and dynamic field. Intended to accompany the laser-induced revolution in atomic physics, it is a comprehensive text for the emerging era in atomic, molecular and optical science. Utilising an intuitive and physical approach, the text describes two-level atom transitions, including appendices on Ramsey spectroscopy, adiabatic rapid passage and entanglement. With a unique focus on optical interactions, the authors present multi-level atomic transitions with dipole selection rules, and M1/E2 and multiphoton transitions. Conventional structure topics are discussed in some detail, beginning with the hydrogen atom and these are interspersed with material rarely found in textbooks such as intuitive descriptions of quantum defects. The final chapters examine modern applications and include many references to current research literature. The numerous exercises and multiple appendices throughout enable advanc...

  9. Charge transfer for slow H atoms interacting with Al: Atomic levels and linewidths

    Science.gov (United States)

    Merino, J.; Lorente, N.; Pou, P.; Flores, F.

    1996-10-01

    The charge transfer of slow H atoms colliding with an Al(100) surface is studied by means of a linear combination of atomic orbitals method with local-density many-body contributions. The method is developed in order to calculate atomic levels and associated linewidths. Unlike previous theories, the present method is able to study the effect of the corrugation of the surface, together with the self-consistent potentials involved. This leads to a shift of atomic levels nonlinear on the external charge, contrary to the traditionally assumed image shift. The method works best at very short distances, where the strong coupling between atom and surface promotes molecular orbitals. Thus, the theory expounded in this work can describe the charge-transfer processes of systems in which the atomic levels are near the band edges, as protons scattered off aluminum.

  10. Calcite biomineralization in coccoliths: Evidence from atomic force microscopy (AFM)

    DEFF Research Database (Denmark)

    Henriksen, Karen; Stipp, S.L.S.

    2002-01-01

    geochemistry, crystal orientation, coccolith function, biomineralization, biological calcite, atomic force microscopy......geochemistry, crystal orientation, coccolith function, biomineralization, biological calcite, atomic force microscopy...

  11. Single-passage read-out of atomic quantum memory

    DEFF Research Database (Denmark)

    Fiurasek, J; Sherson, J; Opatrny, T

    2005-01-01

    Retrieving quantum information, collective atomic spin systems, quantum memory Udgivelsesdato: 17 Feb.......Retrieving quantum information, collective atomic spin systems, quantum memory Udgivelsesdato: 17 Feb....

  12. Significant improvements in stability and reproducibility of atomic-scale atomic force microscopy in liquid

    OpenAIRE

    Akrami, S.M.R.; Nakayachi, H.; Watanabe-Nakayama, Takahiro; Asakawa, Hitoshi; Fukuma, Takeshi

    2014-01-01

    Recent advancement of dynamic-mode atomic force microscopy (AFM) for liquid-environment applications enabled atomic-scale studies on various interfacial phenomena. However, instabilities and poor reproducibility of the measurements often prevent systematic studies. To solve this problem, we have investigated the effect of various tip treatment methods for atomic-scale imaging and force measurements in liquid. The tested methods include Si coating, Ar plasma, Ar sputtering and UV/O3 cleaning. ...

  13. Observation of dynamic atom-atom correlation in liquid helium in real space

    OpenAIRE

    Dmowski, W.; Diallo, S. O.; Lokshin, K.; Ehlers, G.; Ferr?, G.; Boronat, J.; Egami, T.

    2017-01-01

    Liquid He-4 becomes superfluid and flows without resistance below temperature 2.17 K. Superfluidity has been a subject of intense studies and notable advances were made in elucidating the phenomenon by experiment and theory. Nevertheless, details of the microscopic state, including dynamic atom-atom correlations in the superfluid state, are not fully understood. Here using a technique of neutron dynamic pair-density function (DPDF) analysis we show that He-4 atoms in the Bose-Einstein condens...

  14. Atomic Physics 15: Proceedings of the Fifteenth International Conference on Atomic Physics.

    Science.gov (United States)

    van Linden van den Heuvell, H. B.; Walraven, J. T. M.; Reynolds, M. W.

    1997-07-01

    The Table of Contents for the full book PDF is as follows: * Preface * Generation of a "Schrödinger cat" of radiation and observation of its decoherence * Synthesis of entangled states and quantum computing * Entangled states of atomic ions for quantum metrology and computation * Entanglement and indistinguishability: Coherence experiments with photon pairs and triplets * Atom optics as a testing ground for quantum chaos * Coherent ultra-bright XUV lasers and harmonics * Hollow atoms * Interdisciplinary experiments with polarized noble gases * The creation and study of Bose-Einstein condensation in a cold alkali vapor * oscopic quantum phenomena in trapped Bose-condensed gases * Doppler-free spectroscopy of trapped atomic hydrogen * QED and the ground state of helium * Towards coherent atomic samples using laser cooling * Bose-Einstein condensation of a weakly-interacting gas * Zeeman and his contemporaries: Dutch physics around 1900 * Zeeman's great discovery * The Zeeman effect: A tool for atom manipulation * The Zeeman effect a century later: New insights into classical physics * QED effects in few-electron high-Z systems * Lamb shift experiments on high-Z one- and two-electron systems * Fundamental constants of nature * Response of atoms in photonic lattices * Hydrogen-like systems and quantum electrodynamics * New experiments with atomic lattices bound by light * Bloch oscillations of atoms in an optical potential * Quantum decoherence and inertial sensing with atom interferometers * Quantum effects in He clusters * Atoms in super-intense radiation fields * Wave packet dynamics of excited atomic electrons in intense laser fields * Nonlinear laser-electron scattering * Comparing the antiproton and proton and progress toward cold antihydrogen * Author Index

  15. Report on the atom what you should know about atomic energy

    CERN Document Server

    Dean, Gordon

    1954-01-01

    The American approach to the atom ; Uranium is where you find it ; the production line: ore to bombs ; the expanding programme ; the headaches ; the pay-off: weapons ; the military and the atoms ; power: the peaceful goals, first phase ; power: the peaceful goals, second goals ; radioisotopes: servants of man ; the quest for knowledge ; secrecy, security and spies ; the international atom ; behind the Iron Curtain ; the way ahead.

  16. Atomic switch: atom/ion movement controlled devices for beyond von-neumann computers.

    Science.gov (United States)

    Hasegawa, Tsuyoshi; Terabe, Kazuya; Tsuruoka, Tohru; Aono, Masakazu

    2012-01-10

    An atomic switch is a nanoionic device that controls the diffusion of metal ions/atoms and their reduction/oxidation processes in the switching operation to form/annihilate a conductive path. Since metal atoms can provide a highly conductive channel even if their cluster size is in the nanometer scale, atomic switches may enable downscaling to smaller than the 11 nm technology node, which is a great challenge for semiconductor devices. Atomic switches also possess novel characteristics, such as high on/off ratios, very low power consumption and non-volatility. The unique operating mechanisms of these devices have enabled the development of various types of atomic switch, such as gap-type and gapless-type two-terminal atomic switches and three-terminal atomic switches. Novel functions, such as selective volatile/nonvolatile, synaptic, memristive, and photo-assisted operations have been demonstrated. Such atomic switch characteristics can not only improve the performance of present-day electronic systems, but also enable development of new types of electronic systems, such as beyond von- Neumann computers. Copyright © 2012 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  17. Determination of nanogram amounts of bismuth in rocks by atomic absorption spectrometry with electrothermal atomization

    Science.gov (United States)

    Kane, J.S.

    1979-01-01

    Bismuth concentrations as low as 10 ng g-1 in 100-mg samples of geological materials can be determined by atomic absorption spectrometry with electrothermal atomization. After HF-HClO4 decomposition of the sample, bismuth is extracted as the iodide into methyl isobutyl ketone and is then stripped with ethylenediaminetetraacetic acid into the aqueous phase. Aliquots of this solution are pipetted into the graphite furnace and dried, charred, and atomized in an automated sequence. Atomic absorbance at the Bi 223.1-nm line provides a measure of the amount of bismuth present. Results are presented for 14 U.S. Geological Survey standard rocks. ?? 1979.

  18. Characterization of non-Lorentzian line shapes in atom-atom collisions

    Energy Technology Data Exchange (ETDEWEB)

    Dehesa, J.S. (Granada Univ. (Spain). Dept. de Fisica Nuclear; Kernforschungsanlage Juelich G.m.b.H. (Germany, F.R.). Inst. fuer Kernphysik)

    Two different characterizations of the spectral line shape in the core region of resonance lines of atoms perturbed by other atoms in terms of 1) its moments about the origin and 2) its frequency moments are given. Simple expressions relating the line width and the asymmetry parameter of these collision-broadened lines with two of these moments are obtained. These expressions might lead to a new experimental determination of the average time of duration of atom-atom collisions since the involved moments are measurable.

  19. Numerical Models for Viscoelastic Liquid Atomization Spray

    Directory of Open Access Journals (Sweden)

    Lijuan Qian

    2016-12-01

    Full Text Available Atomization spray of non-Newtonian liquid plays a pivotal role in various engineering applications, especially for the energy utilization. To operate spray systems efficiently and well understand the effects of liquid rheological properties on the whole spray process, a comprehensive model using Euler-Lagrangian approaches was established to simulate the evolution of the atomization spray for viscoelastic liquid. Based on the Oldroyd model, the viscoelastic linear dispersion relation was introduced into the primary atomization; an extended viscoelastic version of Taylor analogy breakup (TAB model was proposed; and the coalescence criteria was modified by rheological parameters, such as the relaxation time, the retardation time and the zero shear viscosity. The predicted results are validated with experimental data varying air-liquid mass flow ratio (ALR. Then, numerical calculations are conducted to investigate the characteristics of viscoelastic liquid atomization process. Results showed that the evolutionary trend of droplet mean diameter, Weber number and Ohnesorge number of viscoelastic liquids along with axial direction were qualitatively similar to that of Newtonian liquid. However, the mean size of polymer solution increased more gently than that of water at the downstream of the spray, which was beneficial to stable control of the desirable size in the applications. As concerned the effects of liquid physical properties, the surface tension played an important role in the primary atomization, which indicated the benefit of selecting the solvents with lower surface tension for finer atomization effects, while, for the evolution of atomization spray, larger relaxation time and zero shear viscosity increased droplet Sauter mean diameter (SMD significantly. The zero shear viscosity was effective throughout the jet region, while the effect of relaxation time became weaken at the downstream of the spray field.

  20. An Atomic Gravitational Wave Interferometric Sensor (AGIS)

    Energy Technology Data Exchange (ETDEWEB)

    Dimopoulos, Savas; /Stanford U., Phys. Dept.; Graham, Peter W.; /SLAC; Hogan, Jason M.; Kasevich, Mark A.; /Stanford U., Phys. Dept.; Rajendran, Surjeet; /SLAC /Stanford U., Phys. Dept.

    2008-08-01

    We propose two distinct atom interferometer gravitational wave detectors, one terrestrial and another satellite-based, utilizing the core technology of the Stanford 10m atom interferometer presently under construction. Each configuration compares two widely separated atom interferometers run using common lasers. The signal scales with the distance between the interferometers, which can be large since only the light travels over this distance, not the atoms. The terrestrial experiment with baseline {approx} 1 km can operate with strain sensitivity {approx} 10{sup -19}/{radical}Hz in the 1 Hz-10 Hz band, inaccessible to LIGO, and can detect gravitational waves from solar mass binaries out to megaparsec distances. The satellite experiment with baseline {approx} 1000 km can probe the same frequency spectrum as LISA with comparable strain sensitivity {approx} 10{sup -20}/{radical}Hz. The use of ballistic atoms (instead of mirrors) as inertial test masses improves systematics coming from vibrations, acceleration noise, and significantly reduces spacecraft control requirements. We analyze the backgrounds in this configuration and discuss methods for controlling them to the required levels.

  1. Implementing quantum electrodynamics with ultracold atomic systems

    Science.gov (United States)

    Kasper, V.; Hebenstreit, F.; Jendrzejewski, F.; Oberthaler, M. K.; Berges, J.

    2017-02-01

    We discuss the experimental engineering of model systems for the description of quantum electrodynamics (QED) in one spatial dimension via a mixture of bosonic 23Na and fermionic 6Li atoms. The local gauge symmetry is realized in an optical superlattice, using heteronuclear boson-fermion spin-changing interactions which preserve the total spin in every local collision. We consider a large number of bosons residing in the coherent state of a Bose-Einstein condensate on each link between the fermion lattice sites, such that the behavior of lattice QED in the continuum limit can be recovered. The discussion about the range of possible experimental parameters builds, in particular, upon experiences with related setups of fermions interacting with coherent samples of bosonic atoms. We determine the atomic system’s parameters required for the description of fundamental QED processes, such as Schwinger pair production and string breaking. This is achieved by benchmark calculations of the atomic system and of QED itself using functional integral techniques. Our results demonstrate that the dynamics of one-dimensional QED may be realized with ultracold atoms using state-of-the-art experimental resources. The experimental setup proposed may provide a unique access to longstanding open questions for which classical computational methods are no longer applicable.

  2. Trapped Circular Rydberg Atoms for Quantum Simulation

    Science.gov (United States)

    Cantat-Moltrecht, Tigrane; Nguyen, Thanh Long; Cortinas, Rodrigo; Sayrin, Clément; Haroche, Serge; Brune, Michel; Raimond, Jean-Michel

    2017-04-01

    Condensed-matter systems are interesting and important to understand but they are difficult to study, even numerically, given the significant sizes of their Hilbert space. Quantum simulation proposes to mimic those out-of-reach quantum systems with more controllable and accessible ones. The high polarizability of Rydberg atoms allows for strong and tunable short-range interactions, making them nice candidates for a quantum simulation platform. However, low angular momentum Rydberg atoms cannot be efficiently laser-trapped and their lifetimes would limit the scope of such a quantum simulator. We propose instead to use circular Rydberg atoms (of maximum angular momentum) which can be laser-trapped and whose lifetimes can be extended to the one minute range by placing them in a spontaneous emission-inhibiting capacitor. We aim at the deterministic preparation of a 1D-chain of 40 atoms, trapped in a Laguerre-Gauss hollow laser beam, with a collective lifetime of 2 seconds. With exchange rates in the 10 - 100 kHz range, this would provide a platform able to simulate quantum many-body physics for more than 104 exchange times. In this talk I will present this novel quantum simulation platform and our latest experimental results in the laser-trapping of circular Rydberg atoms.

  3. Atomic scale chemical tomography of human bone

    Science.gov (United States)

    Langelier, Brian; Wang, Xiaoyue; Grandfield, Kathryn

    2017-01-01

    Human bone is a complex hierarchical material. Understanding bone structure and its corresponding composition at the nanometer scale is critical for elucidating mechanisms of biomineralization under healthy and pathological states. However, the three-dimensional structure and chemical nature of bone remains largely unexplored at the nanometer scale due to the challenges associated with characterizing both the structural and chemical integrity of bone simultaneously. Here, we use correlative transmission electron microscopy and atom probe tomography for the first time, to our knowledge, to reveal structures in human bone at the atomic level. This approach provides an overlaying chemical map of the organic and inorganic constituents of bone on its structure. This first use of atom probe tomography on human bone reveals local gradients, trace element detection of Mg, and the co-localization of Na with the inorganic-organic interface of bone mineral and collagen fibrils, suggesting the important role of Na-rich organics in the structural connection between mineral and collagen. Our findings provide the first insights into the hierarchical organization and chemical heterogeneity in human bone in three-dimensions at its smallest length scale - the atomic level. We demonstrate that atom probe tomography shows potential for new insights in biomineralization research on bone.

  4. Quantum dots with single-atom precision.

    Science.gov (United States)

    Fölsch, Stefan; Martínez-Blanco, Jesús; Yang, Jianshu; Kanisawa, Kiyoshi; Erwin, Steven C

    2014-07-01

    Quantum dots are often called artificial atoms because, like real atoms, they confine electrons to quantized states with discrete energies. However, although real atoms are identical, most quantum dots comprise hundreds or thousands of atoms, with inevitable variations in size and shape and, consequently, unavoidable variability in their wavefunctions and energies. Electrostatic gates can be used to mitigate these variations by adjusting the electron energy levels, but the more ambitious goal of creating quantum dots with intrinsically digital fidelity by eliminating statistical variations in their size, shape and arrangement remains elusive. We used a scanning tunnelling microscope to create quantum dots with identical, deterministic sizes. By using the lattice of a reconstructed semiconductor surface to fix the position of each atom, we controlled the shape and location of the dots with effectively zero error. This allowed us to construct quantum dot molecules whose coupling has no intrinsic variation but could nonetheless be tuned with arbitrary precision over a wide range. Digital fidelity opens the door to quantum dot architectures free of intrinsic broadening-an important goal for technologies from nanophotonics to quantum information processing as well as for fundamental studies of confined electrons.

  5. Layered Atom Arrangements in Complex Materials

    Energy Technology Data Exchange (ETDEWEB)

    K.E. Sikafus; R.W.Grimes; S.M.Corish; A.R. Cleave; M.Tang; C.R.Stanek; B.P. Uberuaga; J.A.Valdez

    2005-04-15

    In this report, we develop an atom layer stacking model to describe systematically the crystal structures of complex materials. To illustrate the concepts, we consider a sequence of oxide compounds in which the metal cations progress in oxidation state from monovalent (M{sup 1+}) to tetravalent (M{sup 4+}). We use concepts relating to geometric subdivisions of a triangular atom net to describe the layered atom patterns in these compounds (concepts originally proposed by Shuichi Iida). We demonstrate that as a function of increasing oxidation state (from M{sup 1+} to M{sup 4+}), the layer stacking motifs used to generate each successive structure (specifically, motifs along a 3 symmetry axis), progress through the following sequence: MMO, MO, M{sub r}O, MO{sub r/s}O{sub u/v}, MOO (where M and O represent fully dense triangular atom nets and r/s and u/v are fractions used to describe partially filled triangular atom nets). We also develop complete crystallographic descriptions for the compounds in our oxidation sequence using trigonal space group R{bar 3}.

  6. Laser Spectroscopy of Antiprotonic Helium Atoms

    CERN Multimedia

    2002-01-01

    %PS205 %title\\\\ \\\\Following the discovery of metastable antiprotonic helium atoms ($\\overline{p}He^{+} $) at KEK in 1991, systematic studies of their properties were made at LEAR from 1991 to 1996. In the first two years the lifetime of $\\overline{p}He^{+}$ in liquid and gaseous helium at various temperatures and pressures was measured and the effect of foreign gases on the lifetime of these atoms was investigated. Effects were also discovered which gave the antiproton a 14\\% longer lifetime in $^4$He than in $^3$He, and resulted in important differences in the shape of the annihilation time spectra in the two isotopes.\\\\ \\\\Since 1993 laser spectroscopy of the metastable $\\overline{p}He^{+}$ atoms became the main focus of PS205. Transitions were stimulated between metastable and non-metastable states of the $\\overline{p}He^{+}$ atom by firing a pulsed dye laser beam into the helium target every time an identified metastable atom was present (Figure 1). If the laser frequency matched the transition energy, the...

  7. Atomic Parity Violation Overview and Perspectives

    CERN Document Server

    CERN. Geneva. Audiovisual Unit

    2002-01-01

    Optical experiments have demonstrated cases in which mirror symmetry in stable atoms is broken during absorption or emission of light. Such results are in conflict with standard electromagnetic (EM) theory, but can be explained within the unified electroweak theory. Their interpretation is based on exchanges of virtual weak neutral Z_0 bosons between the electrons and the atomic nucleus. These effects were predicted to increase in heavy atoms a little faster than the cube of the atomic number. Moreover, in a highly forbidden transition, like the 6S-7S transition in cesium, the EM interaction is suppressed, leaving the Z_0 exchange a chance to show up. For achieving the determination of the Cs nucleus weak charge, Q_W(Cs), the basic experimental parameter playing in Z_0, exchange the same role as the nuclear charge in the Coulomb interaction, both experimental and theoretical hurdles had to be overcome: first, the excitation and detection of an atomic line with a transition rate about 10^{14} times less than a...

  8. Seebeck effect at the atomic scale.

    Science.gov (United States)

    Lee, Eui-Sup; Cho, Sanghee; Lyeo, Ho-Ki; Kim, Yong-Hyun

    2014-04-04

    The atomic variations of electronic wave functions at the surface and electron scattering near a defect have been detected unprecedentedly by tracing thermoelectric voltages given a temperature bias [Cho et al., Nat. Mater. 12, 913 (2013)]. Because thermoelectricity, or the Seebeck effect, is associated with heat-induced electron diffusion, how the thermoelectric signal is related to the atomic-scale wave functions and what the role of the temperature is at such a length scale remain very unclear. Here we show that coherent electron and heat transport through a pointlike contact produces an atomic Seebeck effect, which is described by the mesoscopic Seebeck coefficient multiplied by an effective temperature drop at the interface. The mesoscopic Seebeck coefficient is approximately proportional to the logarithmic energy derivative of local density of states at the Fermi energy. We deduced that the effective temperature drop at the tip-sample junction could vary at a subangstrom scale depending on atom-to-atom interaction at the interface. A computer-based simulation method of thermoelectric images is proposed, and a point defect in graphene was identified by comparing experiment and the simulation of thermoelectric imaging.

  9. Permutation-invariant distance between atomic configurations

    Energy Technology Data Exchange (ETDEWEB)

    Ferré, Grégoire; Maillet, Jean-Bernard [CEA, DAM, DIF, F-91297 Arpajon (France); Stoltz, Gabriel [Université Paris-Est, CERMICS (ENPC), INRIA, F-77455 Marne-la-Vallée (France)

    2015-09-14

    We present a permutation-invariant distance between atomic configurations, defined through a functional representation of atomic positions. This distance enables us to directly compare different atomic environments with an arbitrary number of particles, without going through a space of reduced dimensionality (i.e., fingerprints) as an intermediate step. Moreover, this distance is naturally invariant through permutations of atoms, avoiding the time consuming associated minimization required by other common criteria (like the root mean square distance). Finally, the invariance through global rotations is accounted for by a minimization procedure in the space of rotations solved by Monte Carlo simulated annealing. A formal framework is also introduced, showing that the distance we propose verifies the property of a metric on the space of atomic configurations. Two examples of applications are proposed. The first one consists in evaluating faithfulness of some fingerprints (or descriptors), i.e., their capacity to represent the structural information of a configuration. The second application concerns structural analysis, where our distance proves to be efficient in discriminating different local structures and even classifying their degree of similarity.

  10. Mining information from atom probe data

    Energy Technology Data Exchange (ETDEWEB)

    Cairney, Julie M., E-mail: julie.cairney@sydney.edu.au [School of Aerospace, Mechanical, Mechatronic Engineering, The University of Sydney, NSW 2006 (Australia); Australian Centre for Microscopy and Microanalysis, The University of Sydney, NSW 2006 (Australia); Rajan, Krishna [Department of Materials Science and Engineering, Iowa State University, Ames, IA 50011 (United States); Haley, Daniel [Department of Materials, University of Oxford, Parks Road, Oxford OX1 3PH (United Kingdom); Max Planck Institut für Eisenforschung GmbH, Max-Planck Straße 1, 40237 Düsseldorf (Germany); Gault, Baptiste; Bagot, Paul A.J. [Department of Materials, University of Oxford, Parks Road, Oxford OX1 3PH (United Kingdom); Choi, Pyuck-Pa [Max Planck Institut für Eisenforschung GmbH, Max-Planck Straße 1, 40237 Düsseldorf (Germany); Felfer, Peter J.; Ringer, Simon P. [School of Aerospace, Mechanical, Mechatronic Engineering, The University of Sydney, NSW 2006 (Australia); Australian Centre for Microscopy and Microanalysis, The University of Sydney, NSW 2006 (Australia); Marceau, Ross K.W. [Institute for Frontier Materials, Deakin University, Geelong Technology Precinct, 75 Pigdons Road, Waurn Ponds, Victoria 3216 (Australia); Moody, Michael P. [Department of Materials, University of Oxford, Parks Road, Oxford OX1 3PH (United Kingdom)

    2015-12-15

    Whilst atom probe tomography (APT) is a powerful technique with the capacity to gather information containing hundreds of millions of atoms from a single specimen, the ability to effectively use this information creates significant challenges. The main technological bottleneck lies in handling the extremely large amounts of data on spatial–chemical correlations, as well as developing new quantitative computational foundations for image reconstruction that target critical and transformative problems in materials science. The power to explore materials at the atomic scale with the extraordinary level of sensitivity of detection offered by atom probe tomography has not been not fully harnessed due to the challenges of dealing with missing, sparse and often noisy data. Hence there is a profound need to couple the analytical tools to deal with the data challenges with the experimental issues associated with this instrument. In this paper we provide a summary of some key issues associated with the challenges, and solutions to extract or “mine” fundamental materials science information from that data. - Highlights: • Overview of the newest developments in techniques to extract information from atom probe data. • As well as reviewing existing approaches, improvements and new approaches are presented. • Techniques covered include tests for randomness, short range order and crystallography. • Methods for interfacial excess mapping and spectral decomposition are also covered.

  11. A Many-Atom Cavity QED System with Homogeneous Atom-Cavity Coupling

    CERN Document Server

    Lee, Jongmin; Teper, Igor; Hosten, Onur; Kasevich, Mark A

    2013-01-01

    We demonstrate a many-atom-cavity system with a high-finesse dual-wavelength standing wave cavity in which all participating rubidium atoms are nearly identically coupled to a 780-nm cavity mode. This homogeneous coupling is enforced by a one-dimensional optical lattice formed by the field of a 1560-nm cavity mode.

  12. Non-Elastic Processes in Atom Rydberg-Atom Collisions: Review of ...

    Indian Academy of Sciences (India)

    2016-01-27

    Jan 27, 2016 ... Inour previous research, it has been demonstrated that inelastic processes in atom Rydberg-atom collisions, such as chemi-ionization and ( n − n ′ ) mixing, should be considered together. Here we will review the present state-of-the-art and the actual problems. In this context, we will consider the influence ...

  13. Observation of dynamic atom-atom correlation in liquid helium in real space.

    Science.gov (United States)

    Dmowski, W; Diallo, S O; Lokshin, K; Ehlers, G; Ferré, G; Boronat, J; Egami, T

    2017-05-04

    Liquid 4 He becomes superfluid and flows without resistance below temperature 2.17 K. Superfluidity has been a subject of intense studies and notable advances were made in elucidating the phenomenon by experiment and theory. Nevertheless, details of the microscopic state, including dynamic atom-atom correlations in the superfluid state, are not fully understood. Here using a technique of neutron dynamic pair-density function (DPDF) analysis we show that 4 He atoms in the Bose-Einstein condensate have environment significantly different from uncondensed atoms, with the interatomic distance larger than the average by about 10%, whereas the average structure changes little through the superfluid transition. DPDF peak not seen in the snap-shot pair-density function is found at 2.3 Å, and is interpreted in terms of atomic tunnelling. The real space picture of dynamic atom-atom correlations presented here reveal characteristics of atomic dynamics not recognized so far, compelling yet another look at the phenomenon.

  14. Study of atomic and condensed atomic indices for reactive sites of ...

    Indian Academy of Sciences (India)

    In this paper, we have introduced the atomic descriptors () to determine the local reactive sites of the molecular systems during electrophilic, nucleophilic and radical attacks. The condensed Fukui function and the newly introduced condensed atomic descriptor have been calculated for six different systems, namely ...

  15. Observation of dynamic atom-atom correlation in liquid helium in real space

    Science.gov (United States)

    Dmowski, W.; Diallo, S. O.; Lokshin, K.; Ehlers, G.; Ferré, G.; Boronat, J.; Egami, T.

    2017-05-01

    Liquid 4He becomes superfluid and flows without resistance below temperature 2.17 K. Superfluidity has been a subject of intense studies and notable advances were made in elucidating the phenomenon by experiment and theory. Nevertheless, details of the microscopic state, including dynamic atom-atom correlations in the superfluid state, are not fully understood. Here using a technique of neutron dynamic pair-density function (DPDF) analysis we show that 4He atoms in the Bose-Einstein condensate have environment significantly different from uncondensed atoms, with the interatomic distance larger than the average by about 10%, whereas the average structure changes little through the superfluid transition. DPDF peak not seen in the snap-shot pair-density function is found at 2.3 Å, and is interpreted in terms of atomic tunnelling. The real space picture of dynamic atom-atom correlations presented here reveal characteristics of atomic dynamics not recognized so far, compelling yet another look at the phenomenon.

  16. The Mystery of Matter, World of the Atom Series.

    Science.gov (United States)

    Pollard, William G.

    This booklet is one in the "World of the Atome Series" for junior high school students and their teachers. It describes the fascinating story of the search for the key to the structure of matter. These topics are reviewed: the chemical atom of the 19th century, the planetary atom, the wave atom, inside the elementary particles, and the mystery of…

  17. Semiclassical treatment of laser excitation of the hydrogen atom

    DEFF Research Database (Denmark)

    Billing, Gert D.; Henriksen, Niels Engholm; Leforestier, C.

    1992-01-01

    We present an alternative method for studying excitation of atoms in intense laser fields. In the present paper we focus upon the optical harmonic generation by hydrogen atoms.......We present an alternative method for studying excitation of atoms in intense laser fields. In the present paper we focus upon the optical harmonic generation by hydrogen atoms....

  18. Photon mass attenuation coefficients, effective atomic numbers and ...

    Indian Academy of Sciences (India)

    (3) where fi = (ni/ ∑j nj) and Zi are the fractional abundance and atomic number respectively of the constituent element. Here, ni is the total number of atoms of the constituent element and ∑j nj are the total number of atoms of all types present in the compound as per its chemical formula. The effective atomic number, Zeff,.

  19. Formation of positron-atom bound states in collisions between Rydberg Ps and neutral atoms

    CERN Document Server

    Swann, A R; Deller, A; Gribakin, G F

    2016-01-01

    Predicted twenty years ago, positron binding to neutral atoms has not yet been observed experimentally. A new scheme is proposed to detect positron-atom bound states by colliding Rydberg positronium (Ps) with neutral atoms. Estimates of the charge-transfer-reaction cross section are obtained using the first Born approximation for a selection of neutral atom targets and a wide range of incident Ps energies and principal quantum numbers. We also estimate the corresponding Ps ionization cross section. The accuracy of the calculations is tested by comparison with earlier predictions for Ps charge transfer in collisions with hydrogen and antihydrogen. We describe an existing Rydberg Ps beam suitable for producing positron-atom bound states and estimate signal rates based on the calculated cross sections and realistic experimental parameters. We conclude that the proposed methodology is capable of producing such states and of testing theoretical predictions of their binding energies.

  20. A Compact Microchip-Based Atomic Clock Based on Ultracold Trapped Rb Atoms

    CERN Document Server

    Farkas, Daniel M; Anderson, Dana Z

    2009-01-01

    We propose a compact atomic clock based on ultracold Rb atoms that are magnetically trapped near the surface of an atom microchip. An interrogation scheme that combines electromagnetically-induced transparency (EIT) with Ramsey's method of separated oscillatory fields can achieve atomic shot-noise level performance of 10^{-13}/sqrt(tau) for 10^6 atoms. The EIT signal can be detected with a heterodyne technique that provides noiseless gain; with this technique the optical phase shift of a 100 pW probe beam can be detected at the photon shot-noise level. Numerical calculations of the density matrix equations are used to identify realistic operating parameters at which AC Stark shifts are eliminated. By considering fluctuations in these parameters, we estimate that AC Stark shifts can be canceled to a level better than 2*10^{-14}. An overview of the apparatus is presented with estimates of duty cycle and power consumption.

  1. Non-destructive state measurement of individual neutral atoms

    Science.gov (United States)

    Gibbons, Michael; Shih, Chung-Yu; Hamley, Chris; Chapman, Michael

    2011-05-01

    Non-destructive state detection of individual neutral atoms is essential for scalable neutral atom quantum information processing. We have demonstrated non-destructive fluorescent state detection of individual neutral atom qubits trapped in an optical lattice. The hyperfine state of the atom is measured with 95% accuracy and the atom loss rate of 1%. State detection is performed on individual atoms over 100 times before being lost from the trap, representing a significant increase in the data collection rates. Using this technique, we have observed microwave Rabi oscillations with measurements done on one-and-the-same atom.

  2. Resonant quantum transitions in trapped antihydrogen atoms

    CERN Document Server

    Amole, C; Baquero-Ruiz, M; Bertsche, W; Bowe, P D; Butler, E; Capra, A; Cesar, C L; Charlton, M; Deller, A; Donnan, P H; Eriksson, S; Fajans, J; Friesen, T; Fujiwara, M C; Gill, D R; Gutierrez, A; Hangst, J S; Hardy, W N; Hayden, M E; Humphries, A J; Isaac, C A; Jonsell, S; Kurchaninov, L; Little, A; Madsen, N; McKenna, J T K; Menary, S; Napoli, S C; Nolan, P; Olchanski, K; Olin, A; Pusa, P; Rasmussen, C Ø; Robicheaux, F; Sarid, E; Shields, C R; Silveira, D M; Stracka, S; So, C; Thompson, R I; van der Werf, D P; Wurtele, J S

    2012-01-01

    The hydrogen atom is one of the most important and influential model systems in modern physics. Attempts to understand its spectrum are inextricably linked to the early history and development of quantum mechanics. The hydrogen atom’s stature lies in its simplicity and in the accuracy with which its spectrum can be measured1 and compared to theory. Today its spectrum remains a valuable tool for determining the values of fundamental constants and for challenging the limits of modern physics, including the validity of quantum electrodynamics and—by comparison with measurements on its antimatter counterpart, antihydrogen—the validity of CPT (charge conjugation, parity and time reversal) symmetry. Here we report spectroscopy of a pure antimatter atom, demonstrating resonant quantum transitions in antihydrogen. We have manipulated the internal spin state2, 3 of antihydrogen atoms so as to induce magnetic resonance transitions between hyperfine levels of the positronic ground state. We used resonant microwave...

  3. Atomic physics precise measurements and ultracold matter

    CERN Document Server

    Inguscio, Massimo

    2013-01-01

    Atomic Physics provides an expert guide to two spectacular new landscapes in physics: precision measurements, which have been revolutionized by the advent of the optical frequency comb, and atomic physics, which has been revolutionized by laser cooling. These advances are not incremental but transformative: they have generated a consilience between atomic and many-body physics, precipitated an explosion of scientific and technological applications, opened new areas of research, and attracted a brilliant generation of younger scientists. The research is advancing so rapidly, the barrage of applications is so dazzling, that students can be bewildered. For both students and experienced scientists, this book provides an invaluable description of basic principles, experimental methods, and scientific applications.

  4. Relativistic Scott correction for atoms and molecules

    DEFF Research Database (Denmark)

    Solovej, Jan Philip; Sørensen, Thomas Østergaard; Spitzer, Wolfgang Ludwig

    2010-01-01

    We prove the first correction to the leading Thomas-Fermi energy for the ground state energy of atoms and molecules in a model where the kinetic energy of the electrons is treated relativistically. The leading Thomas-Fermi energy, established in [25], as well as the correction given here, are of ......We prove the first correction to the leading Thomas-Fermi energy for the ground state energy of atoms and molecules in a model where the kinetic energy of the electrons is treated relativistically. The leading Thomas-Fermi energy, established in [25], as well as the correction given here......, are of semiclassical nature. Our result on atoms and molecules is proved from a general semiclassical estimate for relativistic operators with potentials with Coulomb-like singularities. This semiclassical estimate is obtained using the coherent state calculus introduced in [36]. The paper contains a unified treatment...

  5. Inflow of atomic gas fuelling star formation

    DEFF Research Database (Denmark)

    Michałowski, M. J.; Gentile, G.; Hjorth, Jeppe

    2016-01-01

    Gamma-ray burst host galaxies are deficient in molecular gas, and show anomalous metal-poor regions close to GRB positions. Using recent Australia Telescope Compact Array (ATCA) Hi observations we show that they have substantial atomic gas reservoirs. This suggests that star formation in these ga......Gamma-ray burst host galaxies are deficient in molecular gas, and show anomalous metal-poor regions close to GRB positions. Using recent Australia Telescope Compact Array (ATCA) Hi observations we show that they have substantial atomic gas reservoirs. This suggests that star formation...... in these galaxies may be fuelled by recent inflow of metal-poor atomic gas. While this process is debated, it can happen in low-metallicity gas near the onset of star formation because gas cooling (necessary for star formation) is faster than the Hi-to-H2 conversion....

  6. Electron correlation for helium-like atoms

    Energy Technology Data Exchange (ETDEWEB)

    Roy, U. [Visvabharati Univ., Santiniketan (India). Dept. of Comput. Sci.; Talukdar, B. [Visvabharati Univ., Santiniketan (India). Dept. of Physics

    1999-02-01

    A recently proposed analytical approach to the ground-state energy of helium atom is generalised to study the effect of electron-electron correlation on the properties of helium isoelectronic sequence. The expectation values of the Hamiltonian and some important functions of radial distances are expressed in terms of derivatives of Lewis integrals which not only permit the straightforward variational calculation to get numerical results but also help one derive interesting recurrence relations for radial expectation values. The results presented for atoms from H{sup -} to Si{sup 12+} indicate that the present analytical model will have quantitative applicability for the study of electronic correlation in high-Z helium-like atoms within the framework of non-relativistic quantum mechanics. (orig.) 22 refs.

  7. Atomic Precision in Nano-Electronics

    Science.gov (United States)

    Strachan, Douglas; Johnston, Danvers; Guiton, Beth; Lu, Ye; Datta, Sujit; Davies, Peter; Bonnell, Dawn; Johnson, Charlie

    2008-03-01

    One of the greatest challenges in developing molecular-scale devices is to fabricate and monitor their formation with atomic precision. Recently, we have developed an electromigration technique that employs feedback for controllably electromigrating a nano-scale electrode with atomic precision at room temperature [1]. We will discuss our recent progress advancing this technique towards atomically precise nano-electronics. This will include in-situ transmission electron microscopy which shows evidence for highly crystalline electrode formation and the parallel fabrication of nanogaps for scaling-up to very large-scale integrated-circuits. Our results have implications on the development of a wide range of novel molecular-scale devices. Funding provided by: NSF-NSEC/NBIC DMR-0425780, NSF-NIRT Grant No. 0304531, and MRSEC award No. DMR05-20020. [1] D. R. Strachan, et al., Appl. Phys. Lett. 86, 043109 (2005).

  8. Single Atoms in Nearly Concentric Cavity

    Science.gov (United States)

    Utama, Adrian Nugraha; Nguyen, Chi Huan; Lewty, Nick; Kurtsiefer, Christian; Quantum Optics Group Team

    2017-04-01

    Strong interaction between photons and neutral single atoms are usually observed in cavity quantum electrodynamics (CQED) systems with high finesse mirrors and small physical volume. We demonstrate another approach that employs a near concentric cavity with relatively low finesse mirrors ( 100) and large physical separation between mirrors ( 10 mm). The transmission spectrum of our CQED system with trapped single atoms is observed to exhibit two resolved normal mode peaks, in which the single atom cooperativity is estimated to be around 0.4. The cooperativity of the system can be improved further by increasing the finesse of the mirrors or moving the cavity closer to the concentric point. The successful realization of concentric CQED systems will open opportunities for scaling up with applications in quantum computing. This work is supported by the National Research Foundation and Ministry of Education, Singapore.

  9. Structure and properties of atomic nanoclusters

    CERN Document Server

    Alonso, Julio A

    2005-01-01

    Atomic clusters are the bridge between molecules and the bulk matter. Following two key experiments - the observation of electronic shells in metallic clusters and the discovery of the C60 fullerence - the field of atomic clusters has experienced a rapid growth, and is now considered a mature field. The electrons of the cluster are confined to a small volume, hence, quantum effects are manifested on many properties of the clusters. Another interesting feature is that the properties often change in a non-smooth way as the number of atoms in the cluster increases. This book provides an updated overview of the field, and presents a detailed description of the structure and electronic properties of different types of clusters: Van der Waals clusters, metallic clusters, clusters of ionic materials and network clusters. The assembling of clusters is also considered, since specially stable clusters are expected to play a role in the future design and synthesis of new materials.

  10. A Scanning Quantum Cryogenic Atom Microscope

    CERN Document Server

    Yang, Fan; Taylor, Stephen F; Turner, Richard W; Lev, Benjamin L

    2016-01-01

    Microscopic imaging of local magnetic fields provides a window into the organizing principles of complex and technologically relevant condensed matter materials. However, a wide variety of intriguing strongly correlated and topologically nontrivial materials exhibit poorly understood phenomena outside the detection capability of state-of-the-art high-sensitivity, high-resolution scanning probe magnetometers. We introduce a quantum-noise-limited scanning probe magnetometer that can operate from room-to-cryogenic temperatures with unprecedented DC-field sensitivity and micron-scale resolution. The Scanning Quantum Cryogenic Atom Microscope (SQCRAMscope) employs a magnetically levitated atomic Bose-Einstein condensate (BEC), thereby providing immunity to conductive and blackbody radiative heating. The SQCRAMscope has a noise floor of 300 pT and provides a 100x improvement in magnetic flux sensitivity over previous atomic scanning probe magnetometers. These capabilities are carefully benchmarked by imaging magnet...

  11. Atomic frequency standard relativistic Doppler shift experiment

    Science.gov (United States)

    Peters, H. E.; Reinhardt, V. S.

    1974-01-01

    An experiment has been performed to measure possible space anisotropy as it would effect the frequency of a cesium atomic beam standard clock in a laboratory on earth due to motion relative to external coordinate frames. The cesium frequency was measured as a function of orientation with respect to an atomic hydrogen maser standard. Over a period of 34 days 101 measurements were made. The results are consistent with a conclusion that no general orientation dependance attributable to spacial anisotropy was observed. It is shown that both the airplane clock results, and the null results for the atomic beam clock, are consistent with Einstein general or special relativity, or with the Lorentz transformations alone.

  12. Positronium collisions with rare-gas atoms

    CERN Document Server

    Gribakin, G F; Wilde, R S; Fabrikant, I I

    2015-01-01

    We calculate elastic scattering of positronium (Ps) by the Xe atom using the recently developed pseudopotential method [Fabrikant I I and Gribakin G F 2014 Phys. Rev. A 90 052717] and review general features of Ps scattering from heavier rare-gas atoms: Ar, Kr and Xe. The total scattering cross section is dominated by two contributions: elastic scattering and Ps ionization (break-up). To calculate the Ps ionization cross sections we use the binary-encounter method for Ps collisions with an atomic target. Our results for the ionization cross section agree well with previous calculations carried out in the impulse approximation. Our total Ps-Xe cross section, when plotted as a function of the projectile velocity, exhibits similarity with the electron-Xe cross section for the collision velocities higher than 0.8 a.u., and agrees very well with the measurements at Ps velocities above 0.5 a.u.

  13. Ionization of atoms by slow heavy particles

    CERN Document Server

    Roberts, B M; Gribakin, G F

    2016-01-01

    Atoms and molecules can become ionized during the scattering of a slow, heavy particle off a bound electron. Such an interaction involving leptophilic weakly interacting massive particles (WIMPs) is a promising possible explanation for the anomalous 9 sigma annual modulation in the DAMA dark matter direct detection experiment [R. Bernabei et al., Eur. Phys. J. C 73, 2648 (2013)]. We demonstrate the applicability of the Born approximation for such an interaction by showing its equivalence to the semiclassical adiabatic treatment of atomic ionization by slow-moving WIMPs. Conventional wisdom has it that the ionization probability for such a process should be exponentially small. We show, however, that due to nonanalytic, cusp-like behaviour of Coulomb functions close to the nucleus this suppression is removed, leading to an effective atomic structure enhancement. We also show that electron relativistic effects actually give the dominant contribution to such a process, meaning that nonrelativistic calculations m...

  14. Conservation laws and laser cooling of atoms

    CERN Document Server

    Giuliani, Giuseppe

    2015-01-01

    The straightforward application of energy and linear momentum conservation to the absorption/emission of photons by atoms--first outlined by Schr\\"odinger in 1922--allows to establish the essential features of laser cooling of two levels atoms at low laser intensities. The minimum attainable average kinetic energy of the atoms depends on the ratio $\\Gamma/E_R$ between the natural linewidth and the recoil energy and tends to $E_R$ as $\\Gamma/E_R$ tends to zero. This treatment is valid for any value of the ratio $\\Gamma/E_R$ and contains the semiclassical theory of laser cooling as the limiting case in which $E_R\\ll \\Gamma$.

  15. Atomic size effects in continuum modeling

    Science.gov (United States)

    Ratsch, C.; Kang, M.; Caflisch, R. E.

    2001-08-01

    Continuum modeling of many physical systems typically assumes that the spatial extent of an atom is small compared to the quantities of interest and can therefore be neglected. We show that this is valid only asymptotically. For many applications of practical interest, the spatial extent of a discrete atom cannot be neglected. We have developed a model for the description of epitaxial growth based on the levelset method, and find that we can accurately predict quantities such as the island densities, if we implement boundary conditions in a region with atomic width, rather than just on a line without any spatial extent. Only in the limit of very large islands and island spacings can this be neglected.

  16. Inductively guided circuits for ultracold dressed atoms

    CERN Document Server

    Sinuco-Leon, German; Arnold, Aidan S; Garraway, Barry M

    2014-01-01

    We propose a flexible and robust scheme to create closed quasi-one dimensional guides for ultra-cold atoms through the dressing of hyperfine sub-levels of the atomic ground state. The dressing field is spatially modulated by inductive effects over a micro-engineered conducting loop, freeing the trapping region from leading wires in its proximity. We show that arrays of connected ring traps can also be created by carefully designing the shape of the conducting loop. We report on characteristics of the trap and mechanisms that limit the range of parameters available for experimental implementation, including non-adiabatic losses and heat dissipation by induced currents. We outline conditions to select appropriate parameters for operation of the trap with atom-chip technology.

  17. Modeling Atom Probe Tomography: A review

    Energy Technology Data Exchange (ETDEWEB)

    Vurpillot, F., E-mail: francois.vurpillot@univ-rouen.fr [Groupe de Physique des Matériaux, UMR CNRS 6634, Université de Rouen, Saint Etienne du Rouvray 76801 (France); Oberdorfer, C. [Institut für Materialwissenschaft, Lehrstuhl für Materialphysik, Universität Stuttgart, Heisenbergstr. 3, 70569 Stuttgart (Germany)

    2015-12-15

    Improving both the precision and the accuracy of Atom Probe Tomography reconstruction requires a correct understanding of the imaging process. In this aim, numerical modeling approaches have been developed for 15 years. The injected ingredients of these modeling tools are related to the basic physic of the field evaporation mechanism. The interplay between the sample nature and structure of the analyzed sample and the reconstructed image artefacts have pushed to gradually improve and make the model more and more sophisticated. This paper reviews the evolution of the modeling approach in Atom Probe Tomography and presents some future potential directions in order to improve the method. - Highlights: • The basics of field evaporation. • The main aspects of Atom Probe Tomography modeling. • The intrinsic limitations of the current method and future potential directions to improve the understanding of tip to image ion projection.

  18. Isolating and moving single atoms using silicon nanocrystals

    Science.gov (United States)

    Carroll, Malcolm S.

    2010-09-07

    A method is disclosed for isolating single atoms of an atomic species of interest by locating the atoms within silicon nanocrystals. This can be done by implanting, on the average, a single atom of the atomic species of interest into each nanocrystal, and then measuring an electrical charge distribution on the nanocrystals with scanning capacitance microscopy (SCM) or electrostatic force microscopy (EFM) to identify and select those nanocrystals having exactly one atom of the atomic species of interest therein. The nanocrystals with the single atom of the atomic species of interest therein can be sorted and moved using an atomic force microscope (AFM) tip. The method is useful for forming nanoscale electronic and optical devices including quantum computers and single-photon light sources.

  19. Ex Vacuo Atom Chip Bose-Einstein Condensate (BEC)

    CERN Document Server

    Squires, Matthew B; Kasch, Brian; Stickney, James A; Erickson, Christopher J; Crow, Jonathan A R; Carlson, Evan J; Burke, John H

    2016-01-01

    Ex vacuo atom chips, used in conjunction with a custom thin walled vacuum chamber, have enabled the rapid replacement of atom chips for magnetically trapped cold atom experiments. Atoms were trapped in $>2$ kHz magnetic traps created using high power atom chips. The thin walled vacuum chamber allowed the atoms to be trapped $\\lesssim1$ mm from the atom chip conductors which were located outside of the vacuum system. Placing the atom chip outside of the vacuum simplified the electrical connections and improved thermal management. Using a multi-lead Z-wire chip design, a Bose-Einstein condensate was produced with an external atom chip. Vacuum and optical conditions were maintained while replacing the Z-wire chip with a newly designed cross-wire chip. The atom chips were exchanged and an initial magnetic trap was achieved in less than three hours.

  20. Atomic hydrogen as a launch vehicle propellant

    Science.gov (United States)

    Palaszewski, Bryan A.

    1990-01-01

    An analysis of several atomic hydrogen launch vehicles was conducted. A discussion of the facilities and the technologies that would be needed for these vehicles is also presented. The Gross Liftoff Weights (GLOW) for two systems were estimated; their specific impulses (I sub sp) were 750 and 1500 lb(sub f)/s/lb(sub m). The atomic hydrogen launch vehicles were also compared to the currently planned Advanced Launch System design concepts. Very significant GLOW reductions of 52 to 58 percent are possible over the Advanced Launch System designs. Applying atomic hydrogen propellants to upper stages was also considered. Very high I(sub sp) (greater than 750 lb(sub f)/s/lb(sub m)) is needed to enable a mass savings over advanced oxygen/hydrogen propulsion. Associated with the potential benefits of high I(sub sp) atomic hydrogen are several challenging problems. Very high magnetic fields are required to maintain the atomic hydrogen in a solid hydrogen matrix. The magnetic field strength was estimated to be 30 kilogauss (3 Tesla). Also the storage temperature of the propellant is 4 K. This very low temperature will require a large refrigeration facility for the launch vehicle. The design considerations for a very high recombination rate for the propellant are also discussed. A recombination rate of 210 cm/s is predicted for atomic hydrogen. This high recombination rate can produce very high acceleration for the launch vehicle. Unique insulation or segmentation to inhibit the propellant may be needed to reduce its recombination rate.

  1. Long term stability of atomic time scales

    Science.gov (United States)

    Petit, Gérard; Arias, Elisa Felicitas

    2012-08-01

    International Atomic Time TAI gets its stability from some 400 atomic clocks worldwide that generate the free atomic scale EA L and its accuracy from a small number of primary frequency standards (PFS) which frequency measurements are used to steer the EAL frequency. Because TAI is computed in "real - time" (every month) and has operational constraints, it is not optimal and the BIPM computes in deferred time another time scale TT(BIPM), which is based on a weighted average of the evaluations of TAI frequency by the PFS. We show that a point has been reached where the stability of atomic time scales, the accuracy of primary frequency standards, and the capabilities of frequency transfer are approximately at a similar level, in the low 10 - 16 in relative frequency. The goal is now to reach and surpass 1x10 - 16 and the three fields are in various stages of advancement towards this aim. We review the stability and accuracy recently achieved by frequency standards, focusing on primary frequency standards on one hand, and on new secondary realizations e.g. based on optical transitions on the other hand. We study how these performances can translate to the performance of atomic time scales, and the possible implications of the availability of new high - accuracy frequency standards operating on a regular basis. Finally we show how time transfer is trying to keep up with the progresses of frequency standards. Time transfer is presently the limiting factor at short averaging time (e.g. 1 - 2 weeks) but it should not be limiting the long term stability of atomic time scales, which is the main need of many applications in astronomy.

  2. High intensity laser interactions with atomic clusters

    Energy Technology Data Exchange (ETDEWEB)

    Ditmire, T

    2000-08-07

    The development of ultrashort pulse table top lasers with peak pulse powers in excess of 1 TW has permitted an access to studies of matter subject to unprecedented light intensities. Such interactions have accessed exotic regimes of multiphoton atomic and high energy-density plasma physics. Very recently, the nature of the interactions between these very high intensity laser pulses and atomic clusters of a few hundred to a few thousand atoms has come under study. Such studies have found some rather unexpected results, including the striking finding that these interactions appear to be more energetic than interactions with either single atoms or solid density plasmas. Recent experiments have shown that the explosion of such clusters upon intense irradiation can expel ions from the cluster with energies from a few keV to nearly 1 MeV. This phenomenon has recently been exploited to produce DD fusion neutrons in a gas of exploding deuterium clusters. Under this project, we have undertaken a general study of the intense femtosecond laser cluster interaction. Our goal is to understand the macroscopic and microscopic coupling between the laser and the clusters with the aim of optimizing high flux fusion neutron production from the exploding deuterium clusters or the x-ray yield in the hot plasmas that are produced in this interaction. In particular, we are studying the physics governing the cluster explosions. The interplay between a traditional Coulomb explosion description of the cluster disassembly and a plasma-like hydrodynamic explosion is not entirely understood, particularly for small to medium sized clusters (<1000 atoms) and clusters composed of low-Z atoms. We are focusing on experimental studies of the ion and electron energies resulting from such explosions through various experimental techniques. We are also examining how an intense laser pulse propagates through a dense medium containing these clusters.

  3. Atomic nanoscale technology in the nuclear industry

    CERN Document Server

    Woo, Taeho

    2011-01-01

    Developments at the nanoscale are leading to new possibilities and challenges for nuclear applications in areas ranging from medicine to international commerce to atomic power production/waste treatment. Progress in nanotech is helping the nuclear industry slash the cost of energy production. It also continues to improve application reliability and safety measures, which remain a critical concern, especially since the reactor disasters in Japan. Exploring the new wide-ranging landscape of nuclear function, Atomic Nanoscale Technology in the Nuclear Industry details the breakthroughs in nanosca

  4. Applied atomic and collision physics special topics

    CERN Document Server

    Massey, H S W; Bederson, Benjamin

    1982-01-01

    Applied Atomic Collision Physics, Volume 5: Special Topics deals with topics on applications of atomic collisions that were not covered in the first four volumes of the treatise. The book opens with a chapter on ultrasensitive chemical detectors. This is followed by separate chapters on lighting, magnetohydrodynamic electrical power generation, gas breakdown and high voltage insulating gases, thermionic energy converters, and charged particle detectors. Subsequent chapters deal with the operation of multiwire drift and proportional chambers and streamer chambers and their use in high energy p

  5. Actinometry of O, N and F atoms

    Science.gov (United States)

    Lopaev, D. V.; Volynets, A. V.; Zyryanov, S. M.; Zotovich, A. I.; Rakhimov, A. T.

    2017-02-01

    The applicability of actinometry for measuring the absolute concentration of O, N and F atoms in discharge plasma was studied. For this purpose, concentrations of these atoms were measured downstream of an ICP plasma by means of the actinometry method and of appearance potential mass-spectrometry (APMS). Comparison of the results showed good agreement between the two methods. Since the excitation cross sections of electron states O(3p 3P) and O(3p 5P) applied in actinometry are well tested, this allows using the APMS method for absolute calibration of the theoretical excitation cross sections for N and F atoms. As a result, total excitation cross sections σ \\text{e}\\text{total} of the atomic levels N(3p 4Po), F(3p 2Po) and F(3p 4Do) have been obtained for the first time. Since different types of electron energy distribution function (EEDF) were observed (Maxwellian, bi-Maxwellian and Druyvesteyn) the influence of these possible EEDF types on actinometric coefficients C\\text{Ar}X (X  =  O, N, F), that link the ratio of the atom and actinometer intensities {{I}X}/{{I}\\text{Ar}} with that of their concentrations [X]/[Ar], was also analyzed. It was shown that at the same ionization rate (effective electron temperature) the excitation rate constants k\\text{e}X,\\text{Ar} are highly sensitive to the shape of EEDF, whereas actinometric coefficients C\\text{Ar}X depend on it only slightly. Dependence of actinometric coefficients on electron temperature C\\text{Ar}X≤ft({{T}\\text{e}}\\right) is positive if the emitting level of the X-atom is lower than that of the actinometer, and negative if vice versa. The energy difference between the emitting states of O and Ar atoms is maximal (~3 eV), so that C\\text{Ar}\\text{O}≤ft({{T}\\text{e}}\\right) is not constant for a whole range of electron temperatures typical for discharge plasmas (~2-8 eV). For nitrogen atoms C\\text{Ar}\\text{N}≤ft({{T}\\text{e}}\\right) varies considerably with T e only when T e

  6. Semiempirical potentials for positron scattering by atoms

    Energy Technology Data Exchange (ETDEWEB)

    Assafrao, Denise; Walters, H. R. J.; Arretche, Felipe; Dutra, Adriano; Mohallem, J. R. [Departamento de Fisica, Universidade Federal do Espirito Santo, 29075-910, Vitoria, ES (Brazil); Department of Applied Mathematics and Theoretical Physics, Queen' s University, Belfast, BT7 1NN (United Kingdom); Departamento de Fisica, Universidade do Estado de Santa Catarina, 89223-100, Joinville, SC (Brazil); Laboratorio de Atomos e Moleculas Especiais, Departamento de Fisica, ICEx, Universidade Federal de Minas Gerais, PO Box 702, 30123-970, Belo Horizonte, MG (Brazil)

    2011-08-15

    We report calculations of differential and integral cross sections for positron scattering by noble gas and alkaline-earth atoms within the same methodology. The scattering potentials are constructed by scaling adiabatic potentials so that their minima coincide with the covalent radii of the target atoms. Elastic differential and integral cross sections are calculated for Ne, Ar, Be, and Mg, and the results are very close to experimental and best theoretical data. Particularly, elastic differential cross sections for Be and Mg at low energies are reported.

  7. Atom capture by nanotube and scaling anomaly

    CERN Document Server

    Giri, Pulak Ranjan

    2007-01-01

    The existence of bound state of the polarizable neutral atom in the inverse square potential created by the electric field of single walled charged carbon nanotube (SWNT) is shown to be theoretically possible. The consideration of inequivalent boundary conditions due to self-adjoint extensions lead to this nontrivial bound state solution. It is also shown that the scaling anomaly is responsible for the existence of bound state. Binding of the polarizable atoms in the coupling constant interval \\eta^2\\in[0,1) may be responsible for the smearing of the edge of steps in quantized conductance, which has not been considered so far in literature.

  8. Constructing Diodes and Transistors for Ultracold Atoms

    Science.gov (United States)

    Pepino, Ronald; Cooper, John; Anderson, Dana; Holland, Murray

    2008-05-01

    The ultracold atom-optical analogy to electronic systems is presented, along with the master equation formalism that is applied to this novel physical context of system-reservoir interactions. The proposed formalism lends itself quite readily to not only the study of atomtronic systems, but also transport properties of ultracold atoms in optical lattices. We demonstrate how these systems can be configured so that they emulate the behavior of the electronic diode, field effect transistor (FET), and bipolar junction transistor (BJT). The behavior of simple logic gates: namely, the AND and OR gates are follow as direct consequences of the atomtronic BJTs.

  9. Atomic layer deposition of nanostructured materials

    CERN Document Server

    Pinna, Nicola

    2012-01-01

    Atomic layer deposition, formerly called atomic layer epitaxy, was developed in the 1970s to meet the needs of producing high-quality, large-area fl at displays with perfect structure and process controllability. Nowadays, creating nanomaterials and producing nanostructures with structural perfection is an important goal for many applications in nanotechnology. As ALD is one of the important techniques which offers good control over the surface structures created, it is more and more in the focus of scientists. The book is structured in such a way to fi t both the need of the expert reader (du

  10. Two-photon cooling of magnesium atoms

    DEFF Research Database (Denmark)

    Malossi, N.; Damkjær, S.; Hansen, P. L.

    2005-01-01

    A two-photon mechanism for cooling atoms below the Doppler temperature is analyzed. We consider the magnesium ladder system (3s2)S01¿(3s3p)P11 at 285.2nm followed by the (3s3p)P11¿(3s3d)D21 transition at 880.7nm . For the ladder system quantum coherence effects may become important. Combined with...... and experiment is excellent. In addition, by properly choosing the Rabi frequencies of the two optical transitions a velocity independent atomic dark state is observed....

  11. Advances in atomic physics an overview

    CERN Document Server

    Cohen-Tannoudji, Claude

    2011-01-01

    This book presents a comprehensive overview of the spectacular advances seen in atomic physics during the last 50 years. The authors explain how such progress was possible by highlighting connections between developments that occurred at different times. They discuss the new perspectives and the new research fields that look promising. The emphasis is placed, not on detailed calculations, but rather on physical ideas. Combining both theoretical and experimental considerations, the book will be of interest to a wide range of students, teachers and researchers in quantum and atomic physics.

  12. Probing dark energy with atom interferometry

    Energy Technology Data Exchange (ETDEWEB)

    Burrage, Clare; Copeland, Edmund J. [School of Physics and Astronomy, University of Nottingham, Nottingham, NG7 2RD (United Kingdom); Hinds, E.A., E-mail: Clare.Burrage@nottingham.ac.uk, E-mail: Edmund.Copeland@nottingham.ac.uk, E-mail: Ed.Hinds@imperial.ac.uk [Centre for Cold Matter, Blackett Laboratory, Imperial College London, Prince Consort Road, London, SW7 2AZ (United Kingdom)

    2015-03-01

    Theories of dark energy require a screening mechanism to explain why the associated scalar fields do not mediate observable long range fifth forces. The archetype of this is the chameleon field. Here we show that individual atoms are too small to screen the chameleon field inside a large high-vacuum chamber, and therefore can detect the field with high sensitivity. We derive new limits on the chameleon parameters from existing experiments, and show that most of the remaining chameleon parameter space is readily accessible using atom interferometry.

  13. Storage of Quantum Variables in Atomic Media

    DEFF Research Database (Denmark)

    Cviklinski, J.; Ortalo, J.; Josse, V.

    2007-01-01

    Storage and read-out of non classical states of light is a critical element for quantum information networks. Simultaneous storage of two non-commuting variables carried by light and subsequent read-out is shown to be possible in atomic ensembles. Interaction of light fields with three-level syst......Storage and read-out of non classical states of light is a critical element for quantum information networks. Simultaneous storage of two non-commuting variables carried by light and subsequent read-out is shown to be possible in atomic ensembles. Interaction of light fields with three...

  14. Benchmarking Attosecond Physics with Atomic Hydrogen

    Science.gov (United States)

    2015-05-25

    Final 3. DATES COVERED (From - To) 12 Mar 12 – 11 Mar 15 4. TITLE AND SUBTITLE Benchmarking attosecond physics with atomic hydrogen 5a...AND SUBTITLE Benchmarking attosecond physics with atomic hydrogen 5a. CONTRACT NUMBER FA2386-12-1-4025 5b. GRANT NUMBER 5c. PROGRAM ELEMENT NUMBER...THIS PAGE unclassified Standard Form 298 (Rev. 8-98) Prescribed by ANSI Std Z39-18 Final Report for AOARD Grant FA2386-12-1-4025 “ Benchmarking

  15. Light-pulse atom interferometric device

    Science.gov (United States)

    Biedermann, Grant; McGuinness, Hayden James Evans; Rakholia, Akash; Jau, Yuan-Yu; Schwindt, Peter; Wheeler, David R.

    2016-03-22

    An atomic interferometric device useful, e.g., for measuring acceleration or rotation is provided. The device comprises at least one vapor cell containing a Raman-active chemical species, an optical system, and at least one detector. The optical system is conformed to implement a Raman pulse interferometer in which Raman transitions are stimulated in a warm vapor of the Raman-active chemical species. The detector is conformed to detect changes in the populations of different internal states of atoms that have been irradiated by the optical system.

  16. Atomically flat single terminated oxide substrate surfaces

    Science.gov (United States)

    Biswas, Abhijit; Yang, Chan-Ho; Ramesh, Ramamoorthy; Jeong, Yoon H.

    2017-05-01

    Scientific interest in atomically controlled layer-by-layer fabrication of transition metal oxide thin films and heterostructures has increased intensely in recent decades for basic physics reasons as well as for technological applications. This trend has to do, in part, with the coming post-Moore era, and functional oxide electronics could be regarded as a viable alternative for the current semiconductor electronics. Furthermore, the interface of transition metal oxides is exposing many new emergent phenomena and is increasingly becoming a playground for testing new ideas in condensed matter physics. To achieve high quality epitaxial thin films and heterostructures of transition metal oxides with atomically controlled interfaces, one critical requirement is the use of atomically flat single terminated oxide substrates since the atomic arrangements and the reaction chemistry of the topmost surface layer of substrates determine the growth and consequent properties of the overlying films. Achieving the atomically flat and chemically single terminated surface state of commercially available substrates, however, requires judicious efforts because the surface of as-received substrates is of chemically mixed nature and also often polar. In this review, we summarize the surface treatment procedures to accomplish atomically flat surfaces with single terminating layer for various metal oxide substrates. We particularly focus on the substrates with lattice constant ranging from 4.00 Å to 3.70 Å, as the lattice constant of most perovskite materials falls into this range. For materials outside the range, one can utilize the substrates to induce compressive or tensile strain on the films and explore new states not available in bulk. The substrates covered in this review, which have been chosen with commercial availability and, most importantly, experimental practicality as a criterion, are KTaO3, REScO3 (RE = Rare-earth elements), SrTiO3, La0.18Sr0.82Al0.59Ta0.41O3 (LSAT), Nd

  17. Atom slowing via dispersive optical interactions

    Science.gov (United States)

    Hamamda, M.; Boustimi, M.; Correia, F.; Baudon, J.; Taillandier-Loize, T.; Dutier, G.; Perales, F.; Ducloy, M.

    2012-02-01

    A promising technique of atom slowing is proposed. It is based upon the dispersive interaction of atoms with optical potential pulses generated by a far-off-resonance standing wave modulated in time. Each pulse reduces the velocity by a small amount. By repeating the process thousands of times, the velocity can be lowered from several hundreds of meters per second down to almost zero, over a path as short as 20cm. In the absence of any random recoil process, the initial characteristics of the beam are preserved.

  18. Atomic data for controlled fusion research

    Energy Technology Data Exchange (ETDEWEB)

    Barnett, C.F.; Ray, J.A.; Ricci, E.; Wilker, M.I.; McDaniel, E.W.; Thomas, E.W.; Gilbody, H.B.

    1977-02-01

    Presented is an evaluated graphical and tabular compilation of atomic and molecular cross sections of interest to controlled thermonuclear research. The cross sections are tabulated and graphed as a function of energy for collision processes involving heavy particles, electrons, and photons with atoms and ions. Also included are sections on data for particle penetration through macroscopic matter, particle transport properties, particle interactions with surfaces, and pertinent charged particle nuclear cross sections and reaction rates. In most cases estimates have been made of the data accuracy.

  19. Microwave Spectroscopy of Cold Rubidium Atoms

    OpenAIRE

    Entin, V. M.; Ryabtsev, I. I.

    2004-01-01

    The effect of microwave radiation on the resonance fluorescence of a cloud of cold $^{85}Rb$ atoms in a magnetooptical trap is studied. The radiation frequency was tuned near the hyperfine splitting frequency of rubidium atoms in the 5S ground state. The microwave field induced magnetic dipole transitions between the magnetic sublevels of the 5S(F=2) and 5S(F=3) states, resulting in a change in the fluorescence signal. The resonance fluorescence spectra were recorded by tuning the microwave r...

  20. Atomic Reference Data for Electronic Structure Calculations

    CERN Document Server

    Kotochigova, S; Shirley, E L

    We have generated data for atomic electronic structure calculations, to provide a standard reference for results of specified accuracy under commonly used approximations. Results are presented here for total energies and orbital energy eigenvalues for all atoms from H to U, at microHartree accuracy in the total energy, as computed in the local-density approximation (LDA) the local-spin-density approximation (LSD); the relativistic local-density approximation (RLDA); and scalar-relativistic local-density approximation (ScRLDA).

  1. Electron transport through monovalent atomic wires

    DEFF Research Database (Denmark)

    Lee, Y. J.; Brandbyge, Mads; Puska, M. J.

    2004-01-01

    Using a first-principles density-functional method we model electron transport through linear chains of monovalent atoms between two bulk electrodes. For noble-metal chains the transport resembles that for free electrons over a potential barrier whereas for alkali-metal chains resonance states...... at the chain determine the conductance. As a result, the conductance for noble-metal chains is close to one quantum of conductance, and it oscillates moderately so that an even number of chain atoms yields a higher value than an odd number. The conductance oscillations are large for alkali-metal chains...

  2. A momentum filter for atomic gas

    Science.gov (United States)

    Xiong, Wei; Zhou, Xiaoji; Yue, Xuguang; Zhai, Yueyang; Chen, Xuzong

    2013-06-01

    We propose and demonstrate a momentum filter for atomic gas-based on a designed Talbot-Lau interferometer. It consists of two identical optical standing-wave pulses separated by a delay equal to odd multiples of the half Talbot time. The one-dimensional momentum width along the long direction of a cigar-shaped condensate is rapidly and greatly purified to a minimum, which corresponds to the ground state energy of the confining trap in our experiment. We find good agreement between theoretical analysis and experimental results. The filter is also effective for non-condensed cold atoms and could be applied widely.

  3. Optical method of atomic ordering estimation

    Energy Technology Data Exchange (ETDEWEB)

    Prutskij, T. [Instituto de Ciencias, BUAP, Privada 17 Norte, No 3417, col. San Miguel Huyeotlipan, Puebla, Pue. (Mexico); Attolini, G. [IMEM/CNR, Parco Area delle Scienze 37/A - 43010, Parma (Italy); Lantratov, V.; Kalyuzhnyy, N. [Ioffe Physico-Technical Institute, 26 Polytekhnicheskaya, St Petersburg 194021, Russian Federation (Russian Federation)

    2013-12-04

    It is well known that within metal-organic vapor-phase epitaxy (MOVPE) grown semiconductor III-V ternary alloys atomically ordered regions are spontaneously formed during the epitaxial growth. This ordering leads to bandgap reduction and to valence bands splitting, and therefore to anisotropy of the photoluminescence (PL) emission polarization. The same phenomenon occurs within quaternary semiconductor alloys. While the ordering in ternary alloys is widely studied, for quaternaries there have been only a few detailed experimental studies of it, probably because of the absence of appropriate methods of its detection. Here we propose an optical method to reveal atomic ordering within quaternary alloys by measuring the PL emission polarization.

  4. Robust Digital Holography For Ultracold Atom Trapping

    Science.gov (United States)

    Gaunt, Alexander; Hadzibabic, Zoran

    2013-05-01

    We have formulated and experimentally demonstrated an improved algorithm for design of arbitrary two-dimensional holographic traps for ultracold atoms. Our method builds on the best previously available algorithm, MRAF, and improves on it in two ways. First, it allows for creation of holographic atom traps with a well defined background potential. Second, we experimentally show that for creating trapping potentials free of fringing artifacts it is important to go beyond the Fourier approximation in modelling light propagation. To this end, we incorporate full Helmholtz propagation into our calculations.

  5. Gravitational Wave Detection with Single-Laser Atom Interferometers

    Science.gov (United States)

    Yu, Nan; Tinto, Massimo

    2011-01-01

    A new design for a broadband detector of gravitational radiation relies on two atom interferometers separated by a distance L. In this scheme, only one arm and one laser are used for operating the two atom interferometers. The innovation here involves the fact that the atoms in the atom interferometers are not only considered as perfect test masses, but also as highly stable clocks. Atomic coherence is intrinsically stable, and can be many orders of magnitude more stable than a laser.

  6. Nondestructive fluorescent state detection of single neutral atom qubits.

    Science.gov (United States)

    Gibbons, Michael J; Hamley, Christopher D; Shih, Chung-Yu; Chapman, Michael S

    2011-04-01

    We demonstrate nondestructive (lossless) fluorescent state detection of individual neutral atom qubits trapped in an optical lattice. The hyperfine state of the atom is measured with a 95% accuracy and an atom loss rate of 1%. Individual atoms are initialized and detected over 100 times before being lost from the trap, representing a 100-fold improvement in data collection rates over previous experiments. Microwave Rabi oscillations are observed with repeated measurements of one and the same single atom. © 2011 American Physical Society

  7. Minimal Nondeterministic Finite Automata and Atoms of Regular Languages

    OpenAIRE

    Brzozowski, Janusz; Tamm, Hellis

    2013-01-01

    We examine the NFA minimization problem in terms of atomic NFA's, that is, NFA's in which the right language of every state is a union of atoms, where the atoms of a regular language are non-empty intersections of complemented and uncomplemented left quotients of the language. We characterize all reduced atomic NFA's of a given language, that is, those NFA's that have no equivalent states. Using atomic NFA's, we formalize Sengoku's approach to NFA minimization and prove that his method fails ...

  8. Machine Learning Estimation of Atom Condensed Fukui Functions.

    Science.gov (United States)

    Zhang, Qingyou; Zheng, Fangfang; Zhao, Tanfeng; Qu, Xiaohui; Aires-de-Sousa, João

    2016-02-01

    To enable the fast estimation of atom condensed Fukui functions, machine learning algorithms were trained with databases of DFT pre-calculated values for ca. 23,000 atoms in organic molecules. The problem was approached as the ranking of atom types with the Bradley-Terry (BT) model, and as the regression of the Fukui function. Random Forests (RF) were trained to predict the condensed Fukui function, to rank atoms in a molecule, and to classify atoms as high/low Fukui function. Atomic descriptors were based on counts of atom types in spheres around the kernel atom. The BT coefficients assigned to atom types enabled the identification (93-94 % accuracy) of the atom with the highest Fukui function in pairs of atoms in the same molecule with differences ≥0.1. In whole molecules, the atom with the top Fukui function could be recognized in ca. 50 % of the cases and, on the average, about 3 of the top 4 atoms could be recognized in a shortlist of 4. Regression RF yielded predictions for test sets with R(2) =0.68-0.69, improving the ability of BT coefficients to rank atoms in a molecule. Atom classification (as high/low Fukui function) was obtained with RF with sensitivity of 55-61 % and specificity of 94-95 %. © 2016 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  9. Atomic-scale sensing of the magnetic dipolar field from single atoms

    Science.gov (United States)

    Choi, Taeyoung; Paul, William; Rolf-Pissarczyk, Steffen; MacDonald, Andrew J.; Natterer, Fabian D.; Yang, Kai; Willke, Philip; Lutz, Christopher P.; Heinrich, Andreas J.

    2017-05-01

    Spin resonance provides the high-energy resolution needed to determine biological and material structures by sensing weak magnetic interactions. In recent years, there have been notable achievements in detecting and coherently controlling individual atomic-scale spin centres for sensitive local magnetometry. However, positioning the spin sensor and characterizing spin-spin interactions with sub-nanometre precision have remained outstanding challenges. Here, we use individual Fe atoms as an electron spin resonance (ESR) sensor in a scanning tunnelling microscope to measure the magnetic field emanating from nearby spins with atomic-scale precision. On artificially built assemblies of magnetic atoms (Fe and Co) on a magnesium oxide surface, we measure that the interaction energy between the ESR sensor and an adatom shows an inverse-cube distance dependence (r-3.01±0.04). This demonstrates that the atoms are predominantly coupled by the magnetic dipole-dipole interaction, which, according to our observations, dominates for atom separations greater than 1 nm. This dipolar sensor can determine the magnetic moments of individual adatoms with high accuracy. The achieved atomic-scale spatial resolution in remote sensing of spins may ultimately allow the structural imaging of individual magnetic molecules, nanostructures and spin-labelled biomolecules.

  10. Do atoms and anti-atoms obey the same laws of physics?

    CERN Multimedia

    Jeffrey Hangst

    2010-01-01

    ALPHA physicists have recently succeeded in trapping anti-atoms for the first time. Being able to hold on to the simplest atoms of antimatter is an important step towards the collaboration’s ultimate goal: precision spectroscopic comparison of hydrogen and antihydrogen. The question they are seeking to answer: do atoms and anti-atoms obey the same laws of physics? The Standard Model says that they must.   The ALPHA Collaboration celebrates the successful results. The ALPHA collaboration has taken it up a gear and trapped 38 atoms of antihydrogen for the first time. Antihydrogen atoms have been mass-produced at the Antiproton Decelerator (AD) since 2002, when ATHENA (ALPHA’s predecessor) and ATRAP learned how to mix clouds of antiprotons and positrons at cryogenic temperatures. However, these anti-atoms were not confined, and flew off in a few microseconds to meet their fate: annihilation with matter in the walls of the experiment. ALPHA uses antiprotons produced at...

  11. METHODS OF SAMPLE THERMAL MODIFICATION BY MEANS DOUBLE VAPORIZATION IN TWO STEP ATOMIZER FOR ATOMIC ABSORPTION ANALYSIS

    OpenAIRE

    Grinshtein, Ilia; Vilpan, Yuri; Saraev, Alexei; Vasilieva, Lubov

    2000-01-01

    After sample vaporization in two-step atomizer with a purged vaporizer sample vapors can be transferred into preheated or into non-heated atomizer. In the last case the atomizer walls trap the vapors and then the sample is second time vaporized and atomized by heating the atomizer. Thermal pre-treatment of a sample using this double vaporization makes possible the direct analysis of samples with strongly interfering matrices including solids. The technique was used for the direct determinatio...

  12. Klebsiella pneumoniae antibiotic resistance identified by atomic ...

    Indian Academy of Sciences (India)

    Vincenzo Ierardi

    2017-10-03

    Oct 3, 2017 ... Our aims were to use the atomic force microscopy (AFM) to investigate bacteria morphological changes in response to antibiotics treatment and explore the possibility of reducing the time required to obtain information on their resistance. In particular, we studied Klebsiella pneumoniae bacteria provided by ...

  13. Asymptotics for Two-dimensional Atoms

    DEFF Research Database (Denmark)

    Nam, Phan Thanh; Portmann, Fabian; Solovej, Jan Philip

    2012-01-01

    We prove that the ground state energy of an atom confined to two dimensions with an infinitely heavy nucleus of charge $Z>0$ and $N$ quantum electrons of charge -1 is $E(N,Z)=-{1/2}Z^2\\ln Z+(E^{\\TF}(\\lambda)+{1/2}c^{\\rm H})Z^2+o(Z^2)$ when $Z\\to \\infty$ and $N/Z\\to \\lambda$, where $E^{\\TF}(\\lambd......We prove that the ground state energy of an atom confined to two dimensions with an infinitely heavy nucleus of charge $Z>0$ and $N$ quantum electrons of charge -1 is $E(N,Z)=-{1/2}Z^2\\ln Z+(E^{\\TF}(\\lambda)+{1/2}c^{\\rm H})Z^2+o(Z^2)$ when $Z\\to \\infty$ and $N/Z\\to \\lambda$, where $E......^{\\TF}(\\lambda)$ is given by a Thomas-Fermi type variational problem and $c^{\\rm H}\\approx -2.2339$ is an explicit constant. We also show that the radius of a two-dimensional neutral atom is unbounded when $Z\\to \\infty$, which is contrary to the expected behavior of three-dimensional atoms....

  14. Surface Plasmon Polaritons Probed with Cold Atoms

    DEFF Research Database (Denmark)

    Kawalec, Tomasz; Sierant, Aleksandra; Panas, Roman

    2017-01-01

    We report on an optical mirror for cold rubidium atoms based on a repulsive dipole potential created by means of a modified recordable digital versatile disc. Using the mirror, we have determined the absolute value of the surface plasmon polariton (SPP) intensity, reaching 90 times the intensity...

  15. Quantum state engineering with single atom laser

    Science.gov (United States)

    Stefanov, V. P.

    2017-11-01

    On the basis of quantum stochastic trajectories approach it is shown that a single atom laser with coherent pumping can generate not only coherent states, but squeezed and Fock states, when different schemes of detection are followed by coherent feedback pulses or feedforward actions.

  16. Lithiation-induced shuffling of atomic stacks

    KAUST Repository

    Nie, Anmin

    2014-09-10

    In rechargeable lithium-ion batteries, understanding the atomic-scale mechanism of Li-induced structural evolution occurring at the host electrode materials provides essential knowledge for design of new high performance electrodes. Here, we report a new crystalline-crystalline phase transition mechanism in single-crystal Zn-Sb intermetallic nanowires upon lithiation. Using in situ transmission electron microscopy, we observed that stacks of atomic planes in an intermediate hexagonal (h-)LiZnSb phase are "shuffled" to accommodate the geometrical confinement stress arising from lamellar nanodomains intercalated by lithium ions. Such atomic rearrangement arises from the anisotropic lithium diffusion and is accompanied by appearance of partial dislocations. This transient structure mediates further phase transition from h-LiZnSb to cubic (c-)Li2ZnSb, which is associated with a nearly "zero-strain" coherent interface viewed along the [001]h/[111]c directions. This study provides new mechanistic insights into complex electrochemically driven crystalline-crystalline phase transitions in lithium-ion battery electrodes and represents a noble example of atomic-level structural and interfacial rearrangements.

  17. Potential roughness near lithographically fabricated atom chips

    DEFF Research Database (Denmark)

    Krüger, Peter; Andersson, L. M.; Wildermuth, Stefan

    2007-01-01

    Potential roughness has been reported to severely impair experiments in magnetic microtraps. We show that these obstacles can be overcome as we measure disorder potentials that are reduced by two orders of magnitude near lithographically patterned high-quality gold layers on semiconductor atom chip...

  18. Karakterisering af Materialer fra atom til makro

    DEFF Research Database (Denmark)

    Brøndsted, Povl; Somers, Marcel A.J.

    2002-01-01

    Denne årbog er udgivet i forbindelse med Dansk Metallurgisk Selskabs Vintermøde, der fandt sted på Hotel Koldingfjord, Kolding i dagene 2. til 4. januar 2002. Bogen indeholder de foredrag, der blev præsenteret på Vintermødet. Emnet for mødet var " Karakterisering af Materialer - fra atom til makro...

  19. Reconstruction of Undersampled Atomic Force Microscopy Images

    DEFF Research Database (Denmark)

    Jensen, Tobias Lindstrøm; Arildsen, Thomas; Østergaard, Jan

    2013-01-01

    Atomic force microscopy (AFM) is one of the most advanced tools for high-resolution imaging and manipulation of nanoscale matter. Unfortunately, standard AFM imaging requires a timescale on the order of seconds to minutes to acquire an image which makes it complicated to observe dynamic processes...

  20. Niels Bohr and the Atomic Structure

    Indian Academy of Sciences (India)

    IAS Admin

    Christien Bohr, was a professor of physiology in the Copenhagen. University. Niels received his education in Copenhagen, obtain- ing his masters degree in 1909, and the doctoral degree in 1911. M Durga Prasad ... Inelastic scattering of electrons from mercury atoms. 1914. J Franck, G Hertz. Interpretation of fine structure.

  1. Coaxing shy particles into an atomic jar

    CERN Multimedia

    Hellemans, A

    2000-01-01

    A Dutch-American team claim they can produce anti-hydrogen atoms in far greater quantities than any other current method. They use rubidium ions to trap electrons by applying a pulsed electric field in a series of steps (1 page).

  2. A method optimization study for atomic absorption ...

    African Journals Online (AJOL)

    A sensitive, reliable and relative fast method has been developed for the determination of total zinc in insulin by atomic absorption spectrophotometer. This designed study was used to optimize the procedures for the existing methods. Spectrograms of both standard and sample solutions of zinc were recorded by measuring ...

  3. Planar nanocontacts with atomically controlled separation

    NARCIS (Netherlands)

    Kervennic, Y.V.; Vanmaekelbergh, D.; Kouwenhoven, L.P.; Van der Zant, H.S.J.

    2003-01-01

    We have developed a technology to reproducibly make gaps with distance control on the single-atom scale. The gold contacts are flat on the nanometer scale and are fabricated on an oxidized aluminum film that serves as a gate. We show that these contacts are clean and can be stabilized via chemical

  4. Anisotropic Interactions between Cold Rydberg Atoms

    Science.gov (United States)

    2015-09-28

    AFRL-AFOSR-CL-TR-2015-0002 Anisotropic interactions between cold Rydberg atoms Luis Marcassa INSTITUTO DE FISICA DE SAO CARLOS Final Report 09/28...problem with the report +551633739806 Organization / Institution name Instituto de Fisica de Sao Carlos Grant/Contract Title The full title of the

  5. Optical traps for ultracold metastable helium atoms

    Energy Technology Data Exchange (ETDEWEB)

    Simonet, Juliette [LKB ENS, Paris (France)

    2009-07-01

    One of the main characteristics of metastable helium atoms is their high internal energy (20 eV). This energy can be released when a metastable atom hits a surface, ejecting one electron. Therefore, using a Channeltron Electron Multiplier (CEM), one can detect atoms with a time resolution of up to 5 ns. However, this high internal energy raises the problem of inelastic Penning ionizations, following: He{sup *}+He{sup *}{yields}He+He{sup +}+e{sup *}. This process has a rate of the order of 10 x 10 cm{sup 3} cot s{sup -}1 but is reduced by four orders of magnitude if the atoms are spin polarized due to total spin conservation. We report on the progress of the set up of a dipole trap for ultracold metastable helium using a red detuned fiber laser at 1560 nm. One of the aims of this optical trap is to release the constraint on the magnetic field value. We plan to measure the magnetic field dependance of inelastic collision rates for temperatures smaller than 10 {mu}K. In a spin polarized gas of helium, the spin-spin interaction produces spin relaxation and relaxation induced Penning ionization if the polarization condition is no longer maintained. We also present the development of a optical lattices in 1D and later in 3D. We intend to monitor the Penning ionization rate in order to follow the real-time dynamics of the superfluid-Mott insulator quantum phase transition.

  6. New atomization nozzle for spray drying

    NARCIS (Netherlands)

    Deventer, H.C. van; Houben, R.J.; Koldeweij, R.B.J.

    2013-01-01

    A new atomization nozzle based on ink jet technology is introduced for spray drying. Application areas are the food and dairy industry, in the first instance, because in these industries the quality demands on the final powders are high with respect to heat load, powder shape, and size distribution.

  7. Atomic Resolution Microscopy of Nitrides in Steel

    DEFF Research Database (Denmark)

    Danielsen, Hilmar Kjartansson

    2014-01-01

    MN and CrMN type nitride precipitates in 12%Cr steels have been investigated using atomic resolution microscopy. The MN type nitrides were observed to transform into CrMN both by composition and crystallography as Cr diffuses from the matrix into the MN precipitates. Thus a change from one...

  8. Atomic displacements in bcc dilute alloys

    Indian Academy of Sciences (India)

    Keywords. Atomic displacements; crystal defects; crystalline solids. PACS Nos 63.43.j; 63.43.Dq; 61.66.Dk; 61.72.Ji. 1. Introduction. The transition metal dilute alloys are studied for their unique properties such as high strength ...... Even the recent techniques like EXAFS are inadequate for bcc alloys because in the EXAFS ...

  9. Tapping mode atomic force microscopy in liquid

    NARCIS (Netherlands)

    Putman, Constant A.J.; Putman, C.A.J.; van der Werf, Kees; de Grooth, B.G.; van Hulst, N.F.; Greve, Jan

    1994-01-01

    We show that standard silicon nitride cantilevers can be used for tapping mode atomic force microscopy (AFM) in air, provided that the energy of the oscillating cantilever is sufficiently high to overcome the adhesion of the water layer. The same cantilevers are successfully used for tapping mode

  10. Atomic and molecular phases through attosecond streaking

    DEFF Research Database (Denmark)

    Baggesen, Jan Conrad; Madsen, Lars Bojer

    2011-01-01

    phase of the atomic or molecular ionization matrix elements from the two states through the interference from the two channels. The interference may change the phase of the photoelectron streaking signal within the envelope of the infrared field, an effect to be accounted for when reconstructing short...

  11. Quantum kinetic theory of trapped atomic gases

    NARCIS (Netherlands)

    Stoof, H.T.C.

    2000-01-01

    We pesent a general framework in which we can accurately describe the non-equilibrium of trapped atomic gases. This is achieved by deriving a single Fokker-Planck equation for the gas. In this way we are able to discuss not only the dynamics of an interacting gas above and below the critical

  12. Multiscaling behavior of atomic-scale friction

    Science.gov (United States)

    Jannesar, M.; Jamali, T.; Sadeghi, A.; Movahed, S. M. S.; Fesler, G.; Meyer, E.; Khoshnevisan, B.; Jafari, G. R.

    2017-06-01

    The scaling behavior of friction between rough surfaces is a well-known phenomenon. It might be asked whether such a scaling feature also exists for friction at an atomic scale despite the absence of roughness on atomically flat surfaces. Indeed, other types of fluctuations, e.g., thermal and instrumental fluctuations, become appreciable at this length scale and can lead to scaling behavior of the measured atomic-scale friction. We investigate this using the lateral force exerted on the tip of an atomic force microscope (AFM) when the tip is dragged over the clean NaCl (001) surface in ultra-high vacuum at room temperature. Here the focus is on the fluctuations of the lateral force profile rather than its saw-tooth trend; we first eliminate the trend using the singular value decomposition technique and then explore the scaling behavior of the detrended data, which contains only fluctuations, using the multifractal detrended fluctuation analysis. The results demonstrate a scaling behavior for the friction data ranging from 0.2 to 2 nm with the Hurst exponent H =0.61 ±0.02 at a 1 σ confidence interval. Moreover, the dependence of the generalized Hurst exponent, h (q ) , on the index variable q confirms the multifractal or multiscaling behavior of the nanofriction data. These results prove that fluctuation of nanofriction empirical data has a multifractal behavior which deviates from white noise.

  13. From lattice gauge theories to hydrogen atoms

    Directory of Open Access Journals (Sweden)

    Manu Mathur

    2015-10-01

    Full Text Available We construct canonical transformations to obtain a complete and most economical realization of the physical Hilbert space Hp of pure SU(22+1 lattice gauge theory in terms of Wigner coupled Hilbert spaces of hydrogen atoms. One hydrogen atom is assigned to every plaquette of the lattice. A complete orthonormal description of the Wilson loop basis in Hp is obtained by all possible angular momentum Wigner couplings of hydrogen atom energy eigenstates |n l m〉 describing electric fluxes on the loops. The SU(2 gauge invariance implies that the total angular momenta of all hydrogen atoms vanish. The canonical transformations also enable us to rewrite the Kogut–Susskind Hamiltonian in terms of fundamental Wilson loop operators and their conjugate electric fields. The resulting loop Hamiltonian has a global SU(2 invariance and a simple weak coupling (g2→0 continuum limit. The canonical transformations leading to the loop Hamiltonian are valid for any SU(N. The ideas and techniques can also be extended to higher dimension.

  14. K$_{-}$ and K$_{-}$ polarizability from kaonic atoms

    CERN Document Server

    Backenstoss, Gerhard; Bergström, I; Bunaciu, T; Egger, J; Hagelberg, R; Hultberg, S; Koch, H; Lynen, Y; Ritter, H G; Schwitter, A; Tauscher, L

    1973-01-01

    The K/sup -/ mass was determined from kaonic atomic X-rays from Au and Ba to be 493.691+or-0.040 MeV. An upper limit for the polarizability of the K/sup -/ was found to be 0.020 fm/sup 3/ at 90% confidence. (18 refs).

  15. The Harnessed Atom: Nuclear Energy & Electricity.

    Science.gov (United States)

    Department of Energy, Washington, DC. Nuclear Energy Office.

    This document is part of a nuclear energy curriculum designed for grades six through eight. The complete kit includes a written text, review exercises, activities for the students, and a teachers guide. The 19 lessons in the curriculum are divided into four units including: (1) "Energy and Electricity"; (2) "Understanding Atoms and Radiation"; (3)…

  16. Atomic level characterization in corrosion studies

    Science.gov (United States)

    Marcus, Philippe; Maurice, Vincent

    2017-06-01

    Atomic level characterization brings fundamental insight into the mechanisms of self-protection against corrosion of metals and alloys by oxide passive films and into how localized corrosion is initiated on passivated metal surfaces. This is illustrated in this overview with selected data obtained at the subnanometre, i.e. atomic or molecular, scale and also at the nanometre scale on single-crystal copper, nickel, chromium and stainless steel surfaces passivated in well-controlled conditions and analysed in situ and/or ex situ by scanning tunnelling microscopy/spectroscopy and atomic force microscopy. A selected example of corrosion modelling by ab initio density functional theory is also presented. The discussed aspects include the surface reconstruction induced by hydroxide adsorption and formation of two-dimensional (hydr)oxide precursors, the atomic structure, orientation and surface hydroxylation of three-dimensional ultrathin oxide passive films, the effect of grain boundaries in polycrystalline passive films acting as preferential sites of passivity breakdown, the differences in local electronic properties measured at grain boundaries of passive films and the role of step edges at the exposed surface of oxide grains on the dissolution of the passive film. This article is part of the themed issue 'The challenges of hydrogen and metals'.

  17. Annual review of cold atoms and molecules

    CERN Document Server

    Bongs, Kai; Carr, Lincoln D; Rey, Ana Maria; Zhai, Hui

    2014-01-01

    The aim of this book is to present review articles describing the latest theoretical and experimental developments in the field of cold atoms and molecules. Our hope is that this series will promote research by both highlighting recent breakthroughs and by outlining some of the most promising research directions in the field.

  18. Positronium impact ionization of Alkali atoms

    CERN Document Server

    Ghosh, D

    2015-01-01

    Target ionization processes of alkali atoms by Positronium impact are investigated. Calculations are performed in the frame work of model potential formalism using the Coulomb distorted eikonal approximation. Interesting qualitative features are noted both in the scattered Ps and the ejected electron distributions in differential as well as double differential levels of the collision cross sections.

  19. The New Element Curium (Atomic Number 96)

    Science.gov (United States)

    Seaborg, G. T.; James, R. A.; Ghiorso, A.

    1948-01-01

    Two isotopes of the element with atomic number 96 have been produced by the helium-ion bombardment of plutonium. The name curium, symbol Cm, is proposed for element 96. The chemical experiments indicate that the most stable oxidation state of curium is the III state.

  20. Atomic lithium vapor laser isotope separation

    CERN Document Server

    Olivares, I E

    2002-01-01

    An atomic vapor laser isotope separation in lithium was performed using tunable diode lasers. The method permits also the separation of the isotopes between the sup 6 LiD sub 2 and the sup 7 LiD sub 1 lines using a self-made mass separator which includes a magnetic sector and an ion beam designed for lithium. (Author)

  1. Nano-soldering to single atomic layer

    Science.gov (United States)

    Girit, Caglar O [Berkeley, CA; Zettl, Alexander K [Kensington, CA

    2011-10-11

    A simple technique to solder submicron sized, ohmic contacts to nanostructures has been disclosed. The technique has several advantages over standard electron beam lithography methods, which are complex, costly, and can contaminate samples. To demonstrate the soldering technique graphene, a single atomic layer of carbon, has been contacted, and low- and high-field electronic transport properties have been measured.

  2. Hurricane Ike versus an Atomic Bomb

    Science.gov (United States)

    Pearson, Earl F.

    2013-01-01

    The destructive potential of one of nature's most destructive forces, the hurricane, is compared to one of human's most destructive devices, an atomic bomb. Both can create near absolute devastation at "ground zero". However, how do they really compare in terms of destructive energy? This discussion compares the energy, the…

  3. Optimal control of complex atomic quantum systems

    Science.gov (United States)

    van Frank, S.; Bonneau, M.; Schmiedmayer, J.; Hild, S.; Gross, C.; Cheneau, M.; Bloch, I.; Pichler, T.; Negretti, A.; Calarco, T.; Montangero, S.

    2016-10-01

    Quantum technologies will ultimately require manipulating many-body quantum systems with high precision. Cold atom experiments represent a stepping stone in that direction: a high degree of control has been achieved on systems of increasing complexity. However, this control is still sub-optimal. In many scenarios, achieving a fast transformation is crucial to fight against decoherence and imperfection effects. Optimal control theory is believed to be the ideal candidate to bridge the gap between early stage proof-of-principle demonstrations and experimental protocols suitable for practical applications. Indeed, it can engineer protocols at the quantum speed limit - the fastest achievable timescale of the transformation. Here, we demonstrate such potential by computing theoretically and verifying experimentally the optimal transformations in two very different interacting systems: the coherent manipulation of motional states of an atomic Bose-Einstein condensate and the crossing of a quantum phase transition in small systems of cold atoms in optical lattices. We also show that such processes are robust with respect to perturbations, including temperature and atom number fluctuations.

  4. Multiscaling behavior of atomic-scale friction.

    Science.gov (United States)

    Jannesar, M; Jamali, T; Sadeghi, A; Movahed, S M S; Fesler, G; Meyer, E; Khoshnevisan, B; Jafari, G R

    2017-06-01

    The scaling behavior of friction between rough surfaces is a well-known phenomenon. It might be asked whether such a scaling feature also exists for friction at an atomic scale despite the absence of roughness on atomically flat surfaces. Indeed, other types of fluctuations, e.g., thermal and instrumental fluctuations, become appreciable at this length scale and can lead to scaling behavior of the measured atomic-scale friction. We investigate this using the lateral force exerted on the tip of an atomic force microscope (AFM) when the tip is dragged over the clean NaCl (001) surface in ultra-high vacuum at room temperature. Here the focus is on the fluctuations of the lateral force profile rather than its saw-tooth trend; we first eliminate the trend using the singular value decomposition technique and then explore the scaling behavior of the detrended data, which contains only fluctuations, using the multifractal detrended fluctuation analysis. The results demonstrate a scaling behavior for the friction data ranging from 0.2 to 2 nm with the Hurst exponent H=0.61±0.02 at a 1σ confidence interval. Moreover, the dependence of the generalized Hurst exponent, h(q), on the index variable q confirms the multifractal or multiscaling behavior of the nanofriction data. These results prove that fluctuation of nanofriction empirical data has a multifractal behavior which deviates from white noise.

  5. Advances in atomic, molecular, and optical physics

    CERN Document Server

    Walther, Herbert; Walther, Herbert

    1999-01-01

    This series, established in 1965, is concerned with recent developments in the general area of atomic, molecular, and optical physics. The field is in a state of rapid growth, as new experimental and theoretical techniques are used on many old and new problems. Topics covered also include related applied areas, such as atmospheric science, astrophysics, surface physics, and laser physics.

  6. Der Stoff, aus dem Atome sind

    CERN Multimedia

    Butscher, R

    2004-01-01

    Quarks are hidden in protons and neutrinos - in the heart of atoms. 40 years before, they were only a elegant trick to put in order the chaos of particles. Nowadays, researchers came up with different model and also questions to answer like: Why do we never see quarks alone? (6 pages)

  7. Students' Mental Models of Atomic Spectra

    Science.gov (United States)

    Körhasan, Nilüfer Didis; Wang, Lu

    2016-01-01

    Mental modeling, which is a theory about knowledge organization, has been recently studied by science educators to examine students' understanding of scientific concepts. This qualitative study investigates undergraduate students' mental models of atomic spectra. Nine second-year physics students, who have already taken the basic chemistry and…

  8. Nanoscale magnetic atom chips for quantum simulation

    NARCIS (Netherlands)

    La Rooij, A.L.

    2017-01-01

    This thesis consists of five chapters that describe the different things that I have done in the past few years which all concern my effort to create lattices of ultracold gaseous atoms at length-scales of approximately 100 nano-meters (a millionth of a decimeter, or 200 times smaller than the

  9. Radioactive ions and atoms in superfluid helium

    NARCIS (Netherlands)

    Dendooven, P.G.; Purushothaman, S.; Gloos, K.; Aysto, J.; Takahashi, N.; Huang, W.; Harissopulos, S; Demetriou, P; Julin, R

    2006-01-01

    We are investigating the use of superfluid helium as a medium to handle and manipulate radioactive ions and atoms. Preliminary results on the extraction of positive ions from superfluid helium at temperatures close to 1 K are described. Increasing the electric field up to 1.2 kV/cm did not improve

  10. The 1986-87 atomic mass predictions

    Science.gov (United States)

    Haustein, P. E.

    1987-12-01

    A project to perform a comprehensive update of the atomic mass predictions has recently been concluded and will be published shortly in Atomic Data and Nuclear Data Tables. The project evolved from an ongoing comparison between available mass predictions and reports of newly measured masses of isotopes throughout the mass surface. These comparisons have highlighted a variety of features in current mass models which are responsible for predictions that diverge from masses determined experimentally. The need for a comprehensive update of the atomic mass predictions was therefore apparent and the project was organized and began at the last mass conference (AMCO-VII). Project participants included: Pape and Anthony; Dussel, Caurier and Zuker; Möller and Nix; Möller, Myers, Swiatecki and Treiner; Comay, Kelson, and Zidon; Satpathy and Nayak; Tachibana, Uno, Yamada and Yamada; Spanier and Johansson; Jänecke and Masson; and Wapstra, Audi and Hoekstra. An overview of the new atomic mass predictions may be obtained by written request.

  11. Atomic and molecular adsorption on Rh(111)

    DEFF Research Database (Denmark)

    Mavrikakis, Manos; Rempel, J.; Greeley, Jeffrey Philip

    2002-01-01

    A systematic study of the chemisorption of both atomic (H, O, N, S, C), molecular (N-2, CO, NO), and radical (CH3, OH) species on Rh(111) has been performed. Self-consistent, periodic, density functional theory (DFT-GGA) calculations, using both PW91 and RPBE functionals, have been employed to de...

  12. Evaluation of atomic absorption Spectrophotometry (ashing, non ...

    African Journals Online (AJOL)

    Three commonly used techniques, namely atomic absorption spectrophotometry (AAS-Ashing and AAS-Non Ashing) and titrimetry (potassium permanganate titration) have been evaluated in this study to determine the calcium content in six food samples whose calcium levels ranged from 0 to more than 250mg/100g ...

  13. The mean excitation energy of atomic ions

    DEFF Research Database (Denmark)

    Sauer, Stephan P. A.; Oddershede, Jens; Sabin, John R.

    2015-01-01

    A method for calculation of the mean excitation energies of atomic ions is presented, making the calculation of the energy deposition of fast ions to plasmas, warm, dense matter, and complex biological systems possible. Results are reported to all ions of helium, lithium, carbon, neon, aluminum, ...

  14. V L Ginzburg and the Atomic Project

    Science.gov (United States)

    Ritus, V. I.

    2017-04-01

    This paper is an expanded version of the author's talk presented at a session of the Physical Sciences Division of the Russian Academy of Sciences celebrating the 100th anniversary of V L Ginzburg's birth. Tamm's Special group was organized in June 1948 with the task to clarify the feasibility of constructing a hydrogen bomb. Having verified and confirmed the calculated results by Ya B Zel'dovich's group, the Tamm group proposed an original hydrogen bomb design, which, following A D Sakharov's idea, consisted of an atomic bomb surrounded spherically by nested uranium and heavy water layers: the heavy water, on V L Ginzburg's suggestion, was replaced by higher-calorie solid lithium-6 deuteride. The ionization implosion of deuterium by uranium, both heated by the atomic bomb's explosion, greatly accelerates nuclear reactions in deuterium and uranium and increases the total energy release. Upon their approval by the KB-11 top researchers, the Atomic project leadership, and the government, the proposals were implemented in the RDS-6s bomb, which was successfully tested on 12 August 1953. Lithium-6 deuteride turned out to be a convenient multipurpose nuclear fuel. The paper highlights the recognition by the leaders of the country and of the Atomic project that fundamental science plays a crucial role in promoting scientists' ideas and proposals.

  15. Recent Developments in the NIST Atomic Databases

    Science.gov (United States)

    Kramida, Alexander

    2011-05-01

    New versions of the NIST Atomic Spectra Database (ASD, v. 4.0) and three bibliographic databases (Atomic Energy Levels and Spectra, v. 2.0, Atomic Transition Probabilities, v. 9.0, and Atomic Line Broadening and Shapes, v. 3.0) have recently been released. In this contribution I will describe the main changes in the way users get the data through the Web. The contents of ASD have been significantly extended. In particular, the data on highly ionized tungsten (W III-LXXIV) have been added from a recently published NIST compilation. The tables for Fe I and Fe II have been replaced with newer, much more extensive lists (10000 lines for Fe I). The other updated or new spectra include H, D, T, He I-II, Li I-III, Be I-IV, B I-V, C I-II, N I-II, O I-II, Na I-X, K I-XIX, and Hg I. The new version of ASD now incorporates data on isotopes of several elements. I will describe some of the issues the NIST ASD Team faces when updating the data.

  16. Rb atomic magnetometer toward EDM experiment with laser cooled francium atoms

    Science.gov (United States)

    Inoue, Takeshi; Ando, Shun; Aoki, Takahiro; Arikawa, Hiroshi; Harada, Ken-Ichi; Hayamizu, Tomohiro; Ishikawa, Taisuke; Itoh, Masatoshi; Kato, Ko; Kawamura, Hirokazu; Sakamoto, Kosuke; Uchiyama, Aiko; Asahi, Koichiro; Yoshimi, Akihiro; Sakemi, Yasuhiro

    2014-09-01

    A permanent electric dipole moment (EDM) of a particle or an atom is a suited observable to test the physics beyond the standard model. We plan to search for the electron EDM by using the laser cooled francium (Fr) atom, since the Fr atom has a large enhancement factor of the electron EDM and the laser cooling techniques can suppress both statistical and systematic errors. In the EDM experiment, a fluctuation of the magnetic field is a main source of the errors. In order to achieve the high precision magnetometry, a magnetometer based on the nonlinear magneto-optical rotation effect of the Rb atom is under development. A long coherence time of Rb atom is the key issue for the highly sensitive detection of the field fluctuations. The coherence time is limited due both to collisions with an inner surface of a cell contained the Rb atom and to residual field in a magnetic shield. We prepared the cell coated with an anti-relaxation material and measured the relaxation time. A degauss of the shield was performed to eliminate the residual field. We will report the present status of the magnetometer. A permanent electric dipole moment (EDM) of a particle or an atom is a suited observable to test the physics beyond the standard model. We plan to search for the electron EDM by using the laser cooled francium (Fr) atom, since the Fr atom has a large enhancement factor of the electron EDM and the laser cooling techniques can suppress both statistical and systematic errors. In the EDM experiment, a fluctuation of the magnetic field is a main source of the errors. In order to achieve the high precision magnetometry, a magnetometer based on the nonlinear magneto-optical rotation effect of the Rb atom is under development. A long coherence time of Rb atom is the key issue for the highly sensitive detection of the field fluctuations. The coherence time is limited due both to collisions with an inner surface of a cell contained the Rb atom and to residual field in a magnetic shield

  17. Molecular Beam Studies of Hot Atom Chemical Reactions: Reactive Scattering of Energetic Deuterium Atoms

    Science.gov (United States)

    Continetti, R. E.; Balko, B. A.; Lee, Y. T.

    1989-02-01

    A brief review of the application of the crossed molecular beams technique to the study of hot atom chemical reactions in the last twenty years is given. Specific emphasis is placed on recent advances in the use of photolytically produced energetic deuterium atoms in the study of the fundamental elementary reactions D + H{sub 2} -> DH + H and the substitution reaction D + C{sub 2}H{sub 2} -> C{sub 2}HD + H. Recent advances in uv laser and pulsed molecular beam techniques have made the detailed study of hydrogen atom reactions under single collision conditions possible.

  18. Lattice dynamics and correlated atomic motion from the atomic pair distribution function

    OpenAIRE

    Jeong, I. -K.; Heffner, R. H.; Graf, M. J.; Billinge, S. J. L.

    2002-01-01

    The mean-square relative displacements (MSRD) of atomic pair motions in crystals are studied as a function of pair distance and temperature using the atomic pair distribution function (PDF). The effects of the lattice vibrations on the PDF peak widths are modelled using both a multi-parameter Born von-Karman (BvK) force model and a single-parameter Debye model. These results are compared to experimentally determined PDFs. We find that the near-neighbor atomic motions are strongly correlated, ...

  19. Molecular beam studies of hot atom chemical reactions: Reactive scattering of energetic deuterium atoms

    Energy Technology Data Exchange (ETDEWEB)

    Continetti, R.E.; Balko, B.A.; Lee, Y.T.

    1989-02-01

    A brief review of the application of the crossed molecular beams technique to the study of hot atom chemical reactions in the last twenty years is given. Specific emphasis is placed on recent advances in the use of photolytically produced energetic deuterium atoms in the study of the fundamental elementary reactions D + H/sub 2/ /minus/> DH + H and the substitution reaction D + C/sub 2/H/sub 2/ /minus/> C/sub 2/HD + H. Recent advances in uv laser and pulsed molecular beam techniques have made the detailed study of hydrogen atom reactions under single collision conditions possible. 18 refs., 9 figs.

  20. Optical lattice clock with strontium atoms; Horloge a reseau optique a atomes de strontium

    Energy Technology Data Exchange (ETDEWEB)

    Baillard, X.; Le Targat, R.; Fouche, M.; Brusch, A.; Westergaard, Ph.G.; Lecallier, A.; Lodewyck, J.; Lemonde, P. [Observatoire de Paris, LNE-SYRTE, Systemes de Reference Temps Espace, 75 (France)

    2009-07-01

    Optical lattice clocks, which were first imagined in 2000, should allow one to achieve unprecedented performances in the domain of atomic clocks. We present here the Strontium lattice clock, developed at LNE-SYRTE. The principle, in particular trapping atoms in the Lamb-Dicke regime and the notion of magic wavelength, is first explained. We then present the results obtained for the {sup 87}Sr isotope, with a frequency accuracy of 2,6.10{sup -15}, and the {sup 88}Sr isotope, with. which we perform the first frequency measurement of an optical lattice clock with bosonic atoms. (authors)

  1. High data-rate atom interferometers through high recapture efficiency

    Science.gov (United States)

    Biedermann, Grant; Rakholia, Akash Vrijal; McGuinness, Hayden

    2015-01-27

    An inertial sensing system includes a magneto-optical trap (MOT) that traps atoms within a specified trapping region. The system also includes a cooling laser that cools the trapped atoms so that the atoms remain within the specified region for a specified amount of time. The system further includes a light-pulse atom interferometer (LPAI) that performs an interferometric interrogation of the atoms to determine phase changes in the atoms. The system includes a controller that controls the timing of MOT and cooling laser operations, and controls the timing of interferometric operations to substantially recapture the atoms in the specified trapping region. The system includes a processor that determines the amount inertial movement of the inertial sensing system based on the determined phase changes in the atoms. Also, a method of inertial sensing using this inertial sensing system includes recapture of atoms within the MOT following interferometric interrogation by the LPAI.

  2. Thermally stable single-atom platinum-on-ceria catalysts via atom trapping

    Energy Technology Data Exchange (ETDEWEB)

    Jones, John; Xiong, Haifeng; DelaRiva, Andrew; Peterson, Eric J.; Pham, Hien; Challa, Sivakumar R.; Qi, Gongshin; Oh, Se H.; Wiebenga, Michelle H.; Pereira Hernandez, Xavier I.; Wang, Yong; Datye, Abhaya K.

    2016-07-08

    Catalysts based on single atoms of scarce precious metals can lead to more efficient use through enhanced reactivity and selectivity. However, single atoms on catalyst supports can be mobile and aggregate into nanoparticles when heated at elevated temperatures. High temperatures are detrimental to catalyst performance unless these mobile atoms can be trapped. We used ceria powders having similar surface areas but different exposed surface facets. When mixed with a platinum/ aluminum oxide catalyst and aged in air at 800°C, the platinum transferred to the ceria and was trapped. Polyhedral ceria and nanorods were more effective than ceria cubes at anchoring the platinum. Performing synthesis at high temperatures ensures that only the most stable binding sites are occupied, yielding a sinter-resistant, atomically dispersed catalyst.

  3. Observation of Individual Fluorine Atom from Highly Oriented Poly (tetrafluoroethylene) Films by Atomic Force Microscopy

    Science.gov (United States)

    Lee, Jonathan A.,; Paley, Mark S.

    1999-01-01

    Direct observation of the film thickness, molecular structure and individual fluorine atoms from highly oriented poly(tetrafluoroethylene) (PTFE) films were achieved using atomic force microscopy (AFM). A thin PTFE film is mechanically deposited onto a smooth glass substrate at specific temperatures by a friction transfer technique. Atomic resolution images of these films show that the chain-like helical structures of the PTFE macromolecules are aligned parallel to each other with an intermolecular spacing of 5.72 A, and individual fluorine atoms are clearly observed along these twisted molecular chains with an interatomic spacing of 2.75 A. Furthermore, the first direct AFM measurements for the radius of the fluorine-helix, and of the carbon-helix in sub-angstrom scale are reported as 1.70 A and 0.54 A respectively.

  4. Atomic species identification at the (101) anatase surface by simultaneous scanning tunnelling and atomic force microscopy

    Science.gov (United States)

    Stetsovych, Oleksandr; Todorović, Milica; Shimizu, Tomoko K.; Moreno, César; Ryan, James William; León, Carmen Pérez; Sagisaka, Keisuke; Palomares, Emilio; Matolín, Vladimír; Fujita, Daisuke; Perez, Ruben; Custance, Oscar

    2015-01-01

    Anatase is a pivotal material in devices for energy-harvesting applications and catalysis. Methods for the accurate characterization of this reducible oxide at the atomic scale are critical in the exploration of outstanding properties for technological developments. Here we combine atomic force microscopy (AFM) and scanning tunnelling microscopy (STM), supported by first-principles calculations, for the simultaneous imaging and unambiguous identification of atomic species at the (101) anatase surface. We demonstrate that dynamic AFM-STM operation allows atomic resolution imaging within the material's band gap. Based on key distinguishing features extracted from calculations and experiments, we identify candidates for the most common surface defects. Our results pave the way for the understanding of surface processes, like adsorption of metal dopants and photoactive molecules, that are fundamental for the catalytic and photovoltaic applications of anatase, and demonstrate the potential of dynamic AFM-STM for the characterization of wide band gap materials. PMID:26118408

  5. Observation of Individual Fluorine Atoms from Highly Oriented Poly(Tetrafluoroethylene) Films by Atomic Force Microscopy

    Science.gov (United States)

    Lee, J. A.

    2000-01-01

    Direct observation of the film thickness, molecular structure, and individual fluorine atoms from highly oriented poly(tetrafluoroethylene) (PTFE) films were achieved using atomic force microscopy (AFM). A thin PTFE film is mechanically deposited onto a smooth glass substrate at specific temperatures by a friction-transfer technique. Atomic resolution images of these films show that the chain-like helical structures of the PTFE macromolecules are aligned parallel to each other with an intermolecular spacing of 5.72 A, and individual fluorine atoms are clearly observed along these twisted molecular chains with an interatomic spacing of 2.75 A. Furthermore, the first direct AFM measurements for the radius of the fluorine-helix, and of the carbon-helix in sub-angstrom scale are reported as 1.7 and 0.54 A respectively.

  6. Probing atomic structure and Majorana wavefunctions in mono-atomic Fe chains on superconducting Pb surface

    Science.gov (United States)

    Pawlak, Rémy; Kisiel, Marcin; Klinovaja, Jelena; Meier, Tobias; Kawai, Shigeki; Glatzel, Thilo; Loss, Daniel; Meyer, Ernst

    2016-11-01

    Motivated by the striking promise of quantum computation, Majorana bound states (MBSs) in solid-state systems have attracted wide attention in recent years. In particular, the wavefunction localisation of MBSs is a key feature and is crucial for their future implementation as qubits. Here we investigate the spatial and electronic characteristics of topological superconducting chains of iron atoms on the surface of Pb(110) by combining scanning tunnelling microscopy and atomic force microscopy. We demonstrate that the Fe chains are mono-atomic, structured in a linear manner and exhibit zero-bias conductance peaks at their ends, which we interpret as signature for a MBS. Spatially resolved conductance maps of the atomic chains reveal that the MBSs are well localised at the chain ends (≲25 nm), with two localisation lengths as predicted by theory. Our observation lends strong support to use MBSs in Fe chains as qubits for quantum-computing devices.

  7. Niels Bohr and the quantum atom the Bohr model of atomic structure 1913-1925

    CERN Document Server

    Kragh, Helge

    2012-01-01

    Niels Bohr and the Quantum Atom is the first book that focuses in detail on the birth and development of Bohr's atomic theory and gives a comprehensive picture of it. At the same time it offers new insight into Bohr's peculiar way of thinking, what Einstein once called his 'unique instinct and tact'. Contrary to most other accounts of the Bohr atom, the book presents it in a broader perspective which includes the reception among other scientists and the criticism launched against it by scientists of a more conservative inclination. Moreover, it discusses the theory as Bohr originally conceived it, namely, as an ambitious theory covering the structure of atoms as well as molecules. By discussing the theory in its entirety it becomes possible to understand why it developed as it did and thereby to use it as an example of the dynamics of scientific theories.

  8. Toward the Atomic-Level Mass Analysis of Biomolecules by the Scanning Atom Probe.

    Science.gov (United States)

    Nishikawa, Osamu; Taniguchi, Masahiro

    2017-04-01

    In 1994, a new type of atom probe instrument, named the scanning atom probe (SAP), was proposed. The unique feature of the SAP is the introduction of a small extraction electrode, which scans over a specimen surface and confines the high field, required for field evaporation of surface atoms in a small space, between the specimen and the electrode. Thus, the SAP does not require a sharp specimen tip. This indicates that the SAP can mass analyze the specimens which are difficult to form in a sharp tip, such as organic materials and biomolecules. Clean single wall carbon nanotubes (CNT), made by high-pressure carbon monoxide process are found to be the best substrates for biomolecules. Various amino acids and dipeptide biomolecules were successfully mass analyzed, revealing characteristic clusters formed by strongly bound atoms in the specimens. The mass analysis indicates that SAP analysis of biomolecules is not only qualitative, but also quantitative.

  9. Atomic physics and quantum optics using superconducting circuits.

    Science.gov (United States)

    You, J Q; Nori, Franco

    2011-06-29

    Superconducting circuits based on Josephson junctions exhibit macroscopic quantum coherence and can behave like artificial atoms. Recent technological advances have made it possible to implement atomic-physics and quantum-optics experiments on a chip using these artificial atoms. This Review presents a brief overview of the progress achieved so far in this rapidly advancing field. We not only discuss phenomena analogous to those in atomic physics and quantum optics with natural atoms, but also highlight those not occurring in natural atoms. In addition, we summarize several prospective directions in this emerging interdisciplinary field.

  10. Self-excitation of Rydberg atoms at a metal surface

    DEFF Research Database (Denmark)

    Bordo, Vladimir

    2017-01-01

    The novel effect of self-excitation of an atomic beam propagating above a metal surface is predicted and a theory is developed. Its underlying mechanism is positive feedback provided by the reflective surface for the atomic polarization. Under certain conditions the atomic beam flying in the near...... field of the metal surface acts as an active device that supports sustained atomic dipole oscillations, which generate, in their turn, an electromagnetic field. This phenomenon does not exploit stimulated emission and therefore does not require population inversion in atoms. An experiment with Rydberg...... atoms in which this effect should be most pronounced is proposed and the necessary estimates are given....

  11. Multipolar electrostatics for proteins: atom-atom electrostatic energies in crambin.

    Science.gov (United States)

    Yuan, Yongna; Mills, Matthew J L; Popelier, Paul L A

    2014-02-15

    Accurate electrostatics necessitates the use of multipole moments centered on nuclei or extra point charges centered away from the nuclei. Here, we follow the former alternative and investigate the convergence behavior of atom-atom electrostatic interactions in the pilot protein crambin. Amino acids are cut out from a Protein Data Bank structure of crambin, as single amino acids, di, or tripeptides, and are then capped with a peptide bond at each side. The atoms in the amino acids are defined through Quantum Chemical Topology (QCT) as finite volume electron density fragments. Atom-atom electrostatic energies are computed by means of a multipole expansion with regular spherical harmonics, up to a total interaction rank of L = ℓA+ ℓB + 1 = 10. The minimum internuclear distance in the convergent region of all the 15 possible types of atom-atom interactions in crambin that were calculated based on single amino acids are close to the values calculated from di and tripeptides. Values obtained at B3LYP/aug-cc-pVTZ and MP2/aug-cc-pVTZ levels are only slightly larger than those calculated at HF/6-31G(d,p) level. This convergence behavior is transferable to the well-known amyloid beta polypeptide Aβ1-42. Moreover, for a selected central atom, the influence of its neighbors on its multipole moments is investigated, and how far away this influence can be ignored is also determined. Finally, the convergence behavior of AMBER becomes closer to that of QCT with increasing internuclear distance. Copyright © 2013 Wiley Periodicals, Inc.

  12. Gold volatile species atomization and preconcentration in quartz devices for atomic absorption spectrometry

    Czech Academy of Sciences Publication Activity Database

    Arslan, Y.; Musil, Stanislav; Matoušek, Tomáš; Kratzer, Jan; Dědina, Jiří

    103-104, JAN-FEB (2015), s. 155-163 ISSN 0584-8547 R&D Projects: GA ČR GA14-23532S Grant - others:GA AV ČR(CZ) M200311202 Institutional support: RVO:68081715 Keywords : gold * volatile species generation * quartz atomizers * atomic absorption spectrometry Subject RIV: CB - Analytical Chemistry, Separation Impact factor: 3.289, year: 2015

  13. Chemical oxygen-iodine laser with atomic iodine generated via fluorine atoms

    Czech Academy of Sciences Publication Activity Database

    Jirásek, Vít; Čenský, Miroslav; Špalek, Otomar; Kodymová, Jarmila; Picková, Irena; Jakubec, Ivo

    2008-01-01

    Roč. 345, č. 1 (2008), 14-22 ISSN 0301-0104 R&D Projects: GA ČR GA202/05/0359 Institutional research plan: CEZ:AV0Z10100523; CEZ:AV0Z40320502 Keywords : atomic iodine * atomic fluorine * chemical oxygen–iodine laser * COIL Subject RIV: BH - Optics, Masers, Lasers Impact factor: 1.961, year: 2008

  14. Equilibrium vortex lattices of a binary rotating atomic Bose–Einstein condensate with unequal atomic masses

    Energy Technology Data Exchange (ETDEWEB)

    Dong, Biao; Wang, Lin-Xue; Chen, Guang-Ping [Key Laboratory of Time and Frequency Primary Standards, National Time Service Center, Chinese Academy of Sciences, Xi’an 710600 (China); University of Chinese Academy of Sciences, Beijing 100049 (China); Han, Wei; Zhang, Shou-Gang [Key Laboratory of Time and Frequency Primary Standards, National Time Service Center, Chinese Academy of Sciences, Xi’an 710600 (China); Zhang, Xiao-Fei, E-mail: xfzhang@ntsc.ac.cn [Key Laboratory of Time and Frequency Primary Standards, National Time Service Center, Chinese Academy of Sciences, Xi’an 710600 (China)

    2016-10-15

    We perform a detailed numerical study of the equilibrium ground-state structures of a binary rotating Bose–Einstein condensate with unequal atomic masses. Our results show that the ground-state distribution and its related vortex configurations are complex events that differ markedly depending strongly on the strength of rotation frequency, as well as on the ratio of atomic masses. We also discuss the structures and radii of the clouds, the number and the size of the core region of the vortices, as a function of the rotation frequency, and of the ratio of atomic masses, and the analytical results agree well with our numerical simulations. This work may open an alternate way in the quantum control of the binary rotating quantum gases with unequal atomic masses. - Highlights: • A binary quantum gases with unequal atomic masses is considered. • Effects of the ratio of atomic masses and rotation frequency are discussed in full parameter space. • The detailed information about both the cloud and vortices are also discussed.

  15. AtomPy: An Open Atomic Data Curation Environment for Astrophysical Applications

    Directory of Open Access Journals (Sweden)

    Claudio Mendoza

    2014-05-01

    Full Text Available We present a cloud-computing environment, referred to as AtomPy, based on Google-Drive Sheets and Pandas (Python Data Analysis Library DataFrames to promote community-driven curation of atomic data for astrophysical applications, a stage beyond database development. The atomic model for each ionic species is contained in a multi-sheet workbook, tabulating representative sets of energy levels, A-values and electron impact effective collision strengths from different sources. The relevant issues that AtomPy intends to address are: (i data quality by allowing open access to both data producers and users; (ii comparisons of different datasets to facilitate accuracy assessments; (iii downloading to local data structures (i.e., Pandas DataFrames for further manipulation and analysis by prospective users; and (iv data preservation by avoiding the discard of outdated sets. Data processing workflows are implemented by means of IPython Notebooks, and collaborative software developments are encouraged and managed within the GitHub social network. The facilities of AtomPy are illustrated with the critical assessment of the transition probabilities for ions in the hydrogen and helium isoelectronic sequences with atomic number Z ≤ 10.

  16. Ambient atomic resolution atomic force microscopy with qPlus sensors: Part 1.

    Science.gov (United States)

    Wastl, Daniel S

    2017-01-01

    Atomic force microscopy (AFM) is an enormous tool to observe nature in highest resolution and understand fundamental processes like friction and tribology on the nanoscale. Atomic resolution in highest quality was possible only in well-controlled environments like ultrahigh vacuum (UHV) or controlled buffer environments (liquid conditions) and more specified for long-term high-resolution analysis at low temperatures (∼4 K) in UHV where drift is nearly completely absent. Atomic resolution in these environments is possible and is widely used. However, in uncontrolled environments like air, with all its pollutants and aerosols, unspecified thin liquid films as thin as a single molecular water-layer of 200 pm or thicker condensation films with thicknesses up to hundred nanometer, have been a problem for highest resolution since the invention of the AFM. The goal of true atomic resolution on hydrophilic as well as hydrophobic samples was reached recently. In this manuscript we want to review the concept of ambient AFM with atomic resolution. The reader will be introduced to the phenomenology in ambient conditions and the problems will be explained and analyzed while a method for scan parameter optimization will be explained. Recently developed concepts and techniques how to reach atomic resolution in air and ultra-thin liquid films will be shown and explained in detail, using several examples. Microsc. Res. Tech. 80:50-65, 2017. © 2016 Wiley Periodicals, Inc. © 2016 Wiley Periodicals, Inc.

  17. Atomic resolution non-contact atomic force microscopy of clean metal oxide surfaces.

    Science.gov (United States)

    Lauritsen, J V; Reichling, M

    2010-07-07

    In the last two decades the atomic force microscope (AFM) has become the premier tool for topographical analysis of surface structures at the nanometre scale. In its ultimately sensitive implementation, namely dynamic scanning force microscopy (SFM) operated in the so-called non-contact mode (NC-AFM), this technique yields genuine atomic resolution and offers a unique tool for real space atomic-scale studies of surfaces, nanoparticles as well as thin films, single atoms and molecules on surfaces irrespective of the substrate being electrically conducting or non-conducting. Recent advances in NC-AFM have paved the way for groundbreaking atomic level insight into insulator surfaces, specifically in the most important field of metal oxides. NC-AFM imaging now strongly contributes to our understanding of the surface structure, chemical composition, defects, polarity and reactivity of metal oxide surfaces and related physical and chemical surface processes. Here we review the latest advancements in the field of NC-AFM applied to the fundamental atomic resolution studies of clean single crystal metal oxide surfaces with special focus on the representative materials Al(2)O(3)(0001), TiO(2)(110), ZnO(1000) and CeO(2)(111). © 2010 IOP Publishing Ltd

  18. Interplay between Switching Driven by the Tunneling Current and Atomic Force of a Bistable Four-Atom Si Quantum Dot.

    Science.gov (United States)

    Yamazaki, Shiro; Maeda, Keisuke; Sugimoto, Yoshiaki; Abe, Masayuki; Zobač, Vladimír; Pou, Pablo; Rodrigo, Lucia; Mutombo, Pingo; Pérez, Ruben; Jelínek, Pavel; Morita, Seizo

    2015-07-08

    We assemble bistable silicon quantum dots consisting of four buckled atoms (Si4-QD) using atom manipulation. We demonstrate two competing atom switching mechanisms, downward switching induced by tunneling current of scanning tunneling microscopy (STM) and opposite upward switching induced by atomic force of atomic force microscopy (AFM). Simultaneous application of competing current and force allows us to tune switching direction continuously. Assembly of the few-atom Si-QDs and controlling their states using versatile combined AFM/STM will contribute to further miniaturization of nanodevices.

  19. Feedback Control of MEMS to Atoms

    CERN Document Server

    Shapiro, Benjamin

    2012-01-01

    Feedback Control of MEMS to Atoms illustrates the use of control and control systems as an essential part of functioning integrated miniaturized systems. The book is organized according to the dimensional scale of the problem, starting with microscale systems and ending with atomic-scale systems. Similar to macroscale machines and processes, control systems can play a major role in improving the performance of micro- and nanoscale systems and in enabling new capabilities that would otherwise not be possible. The majority of problems at these scales present many new challenges that go beyond the current state-of-the-art in control theory and engineering. This is a result of the multidisciplinary nature of micro/nanotechnology, which requires the merging of control engineering with physics, biology and chemistry. This book: Shows how the utilization of feedback control in nanotechnology instrumentation can yield results far better than passive systems can Discusses the application of control systems to problems...

  20. Einstein, Ethics and the Atomic Bomb

    Science.gov (United States)

    Rife, Patricia

    2005-03-01

    Einstein voiced his ethical views against war as well as fascism via venues and alliances with a variety of organizations still debated today. In 1939, he signed a letter to President Roosevelt (drafted by younger colleagues Szilard, Wigner and others) warning the U.S.government about the danger of Nazi Germany gaining control of uranium in the Belgian-controlled Congo in order to develop atomic weapons, based on the discovery of fission by Otto Hahn and Lise Meitner. In 1945, he became a member of the Princeton-based ``Emergency Committee for Atomic Scientists'' organized by Bethe, Condon, Bacher, Urey, Szilard and Weisskopf. Rare Einstein slides will illustrate Dr.Rife's presentation on Albert Einstein's philosophic and ethical convictions about peace, and public stance against war (1914-1950).