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Sample records for atomic vapour laser

  1. Laser optical pumping in Rb vapour-cell atomic clocks (Invited Paper)

    NASA Astrophysics Data System (ADS)

    Mileti, Gaetano; Affolderbach, C.

    2005-04-01

    We discuss the basic physical principles of laser optical pumping double-resonance spectroscopy, which form the basis of state-of-the-art vapour-cell atomic frequency standards using laser optical pumping of Rb atoms. The main effects limiting the frequency stability of Rb vapour-cell atomic clocks are identified, and their impact on the development of high-performance frequency standars and their transfer from research laboratories to industry and space is discussed. As examples, the impact of the AC stark effect and the realated issue of laser frequency stabilisation are dealt with in more detail. The main features of the present state-of-the-art Rb atomic frequency standards will be illustrated using the example of the development of atomic clocks for satellite navigation and positioning systems (GPS, GLONAS, GALILEO, etc.) as well as some directions for further improvements that could overcome present day limitations. Such compact Rb clocks find their applications in, for example, telecommunications, local timekeeping and synchronisation, and space applications like satellite navigation and science missions. An overview of other, alternative clock schemes is given and critical issues for future developments towards further performance improvement or device miniaturisation in the field of vapour-cell atomic clocks are discussed.

  2. Light-shift suppression in laser optically pumped vapour-cell atomic frequency standards

    NASA Astrophysics Data System (ADS)

    Affolderbach, C.; Andreeva, C.; Cartaleva, S.; Karaulanov, T.; Mileti, G.; Slavov, D.

    2005-06-01

    We present a novel scheme for reducing the AC Stark effect in optical-microwave double-resonance spectroscopy and its application for efficient suppression of the light-shift-related instabilities in laser-pumped gas-cell atomic clocks. The method uses a multi-frequency pump light field that can be easily produced by frequency modulation of the single-frequency pump laser. We show theoretically that variations of the light shift with both laser frequency and light intensity can be strongly suppressed with properly chosen pump light spectra. Suitable modulation parameters can be found for both the case of pure frequency modulation as well as for pump light spectra showing amplitude-modulation contributions, as usually found for current modulation of diode lasers. We experimentally demonstrate the method for a Rb atomic clock using a frequency-modulated distributed Bragg-reflector laser diode as pump light source.

  3. LASER APPLICATIONS AND OTHER TOPICS IN QUANTUM ELECTRONICS: Production of a highly enriched 176Yb isotope in weight amounts by the atomic-vapour laser isotope separation method

    NASA Astrophysics Data System (ADS)

    Andreev, O. I.; Derzhiev, V. I.; Dyakin, V. M.; Egorov, A. G.; Mikhal'tsov, L. A.; Tarasov, V. A.; Tolkachev, A. I.; Toporov, Yu G.; Chaushanskii, S. A.; Yakovlenko, Sergei I.

    2006-01-01

    The production of a highly enriched 176Yb isotope in weight amounts by the atomic-vapour laser isotope separation method is reported. The content of 176Yb achieved in the experimental samples of the enriched material was 99%. For a commercial production of about 20 mg h-1, the concentration of this isotope is about 88% with about 5% of the 'harmful' isotope 174Yb. The experimental results may serve as the basis for the technology of obtaining 177Lu isotope for applications in modern nuclear medicine as a drug with a high specific activity.

  4. Production of a highly enriched {sup 176}Yb isotope in weight amounts by the atomic-vapour laser isotope separation method

    SciTech Connect

    Andreev, O I; Derzhiev, V I; Dyakin, V M; Egorov, A G; Mikhal'tsov, L A; Tarasov, V A; Tolkachev, A I; Toporov, Yu G; Chaushanskii, S A; Yakovlenko, Sergei I

    2006-01-31

    The production of a highly enriched {sup 176}Yb isotope in weight amounts by the atomic-vapour laser isotope separation method is reported. The content of {sup 176}Yb achieved in the experimental samples of the enriched material was 99%. For a commercial production of about 20 mg h{sup -1}, the concentration of this isotope is about 88% with about 5% of the 'harmful' isotope {sup 174}Yb. The experimental results may serve as the basis for the technology of obtaining {sup 177}Lu isotope for applications in modern nuclear medicine as a drug with a high specific activity. (laser applications and other topics in quantum electronics)

  5. Collisional thulium vapour gas-discharge laser

    SciTech Connect

    Gerasimov, V A; Pavlinskii, A V

    2004-01-31

    A collisional laser on a system of atomic levels based on the principle proposed by Gould is built for the first time. The population of the upper laser level and relaxation of the lower level occur upon inelastic collisions of excited thulium atoms with helium atoms. The lower-level relaxation occurs in a reaction with an energy defect of > 13000 cm{sup -1}. (active media. lasers)

  6. Ultrafast vapourization dynamics of laser-activated polymeric microcapsules

    NASA Astrophysics Data System (ADS)

    Lajoinie, Guillaume; Gelderblom, Erik; Chlon, Ceciel; Böhmer, Marcel; Steenbergen, Wiendelt; de Jong, Nico; Manohar, Srirang; Versluis, Michel

    2014-04-01

    Precision control of vapourization, both in space and time, has many potential applications; however, the physical mechanisms underlying controlled boiling are not well understood. The reason is the combined microscopic length scales and ultrashort timescales associated with the initiation and subsequent dynamical behaviour of the vapour bubbles formed. Here we study the nanoseconds vapour bubble dynamics of laser-heated single oil-filled microcapsules using coupled optical and acoustic detection. Pulsed laser excitation leads to vapour formation and collapse, and a simple physical model captures the observed radial dynamics and resulting acoustic pressures. Continuous wave laser excitation leads to a sequence of vapourization/condensation cycles, the result of absorbing microcapsule fragments moving in and out of the laser beam. A model incorporating thermal diffusion from the capsule shell into the oil core and surrounding water reveals the mechanisms behind the onset of vapourization. Excellent agreement is observed between the modelled dynamics and experiment.

  7. Mechanisms of vapour plume formation in laser deep penetration welding

    NASA Astrophysics Data System (ADS)

    Brock, C.; Hohenstein, R.; Schmidt, M.

    2014-07-01

    We analysed the dynamic shape of the metal vapour plume during deep penetration laser welding by means of high speed imaging. Our studies show that besides the inclination also the elongation of the vapour plume is determined by the evaporation processes inside the keyhole. When welding stainless steel sheets, the shape of the vapour plume as well as the shape of its origin, the keyhole, significantly vary with laser power and feed rate settings in a consistent way. This rather deterministic relationship allows for estimating how evaporation is distributed along the keyhole surface in different welding regimes. Based on the evaluation of the high speed sequences and corresponding microsections we propose a model of the vapour plume formation. The model indicates that, depending on the keyhole shape, the generation of the vapour plume is either governed by the vapour formed at the bottom of the keyhole or by the vapour formed at the inclined front keyhole surface, resulting in a very different shape of the plume in each case.

  8. Transversely diode-pumped alkali metal vapour laser

    NASA Astrophysics Data System (ADS)

    Parkhomenko, A. I.; Shalagin, A. M.

    2015-09-01

    We have studied theoretically the operation of a transversely diode-pumped alkali metal vapour laser. For the case of high-intensity laser radiation, we have obtained an analytical solution to a complex system of differential equations describing the laser. This solution allows one to exhaustively determine all the energy characteristics of the laser and to find optimal parameters of the working medium and pump radiation (temperature, buffer gas pressure, and intensity and width of the pump spectrum).

  9. Copper bromide vapour laser with a pulse repetition rate up to 700 kHz

    SciTech Connect

    Nekhoroshev, V O; Fedorov, V F; Evtushenko, Gennadii S; Torgaev, S N

    2012-10-31

    The results of the experimental study of a copper bromide vapour laser at high repetition rates of regular pump pulses are presented. A record-high pulse repetition rate of 700 kHz is attained for lasing at self-terminating transitions in copper atoms. To analyse the obtained results, use is made of the data of numerical modelling of the plasma kinetics in the phase of pumping and discharge afterglow. (lasers)

  10. Resonance laser-induced ionisation of sodium vapour taking radiative transfer into account

    SciTech Connect

    Kosarev, N I; Shaparev, N Ya

    2006-04-30

    The problem of ionisation of atomic sodium in the field of resonance laser radiation is numerically solved taking radiative transfer into account. Seed electrons are produced due to the mechanism of associative ionisation, then they gain energy in superelastic processes (collisions of the second kind) and initiate the avalanche ionisation of the medium by electron impact. We studied the effect of secondary radiation on the laser pulse propagation upon competition between the ionising and quenching electron collisions with excited atoms, on the kinetics of ionisation-induced vapour bleaching, and the plasma channel expansion in the form of a halo. (interaction of laser radiation with matter)

  11. Spectroscopy of micro-fabricated Cs vapours cells for miniature atomic clocks

    NASA Astrophysics Data System (ADS)

    Miletic, D.; Affolderbach, C.; Mileti, G.; Hasegawa, M.; Gorecki, C.

    2010-10-01

    In this paper we present our spectroscopic studies on Coherent Population Trapping (CPT) in micro-fabricated Caesium cells and our evaluation of its application in miniature atomic frequency standards (atomic clocks). We observe the CPT signal on the Cs D1-line by coupling two hyperfine ground-state Zeeman sub-levels to a common excited state using two coherent electromagnetic fields created with a modulated DFB laser. Contrarily to double resonance, CPT does not require any microwave cavity, which should facilitate the miniaturization of a future atomic clock device. We study and report here on the light shift phenomena at different cell temperatures and laser wavelength. We also present resonance shifts due to cell temperature variations and clock frequency stability measurements. To the best of our knowledge, this article is the first report on light shift with Cs D1 line in a CPT vapour-cell atomic clock.

  12. Infrared Laser Optoacoustic Detection Of Gases And Vapours

    NASA Astrophysics Data System (ADS)

    Johnson, S. A.; Cummins, P. G.; Bone, S. A.; Davies, P. B.

    1988-10-01

    Mid-infrared laser optoacoustic spectroscopy has been used to detect a variety of gases and vapours. Performance was calibrated using the signal from a known concentration of ethene, and then the method applied to the perfume alcohol geraniol. Detection limits were found to be 1 ppb for ethene and 70 ppb for geraniol on their strongest absorption lines for a few seconds measurement time.

  13. The Development Of Gold And Copper Vapour Lasers For Medical Applications In Australia

    NASA Astrophysics Data System (ADS)

    Stanco, Alex

    1987-04-01

    The first fully automated mobile copper and gold vapour lasers for medical applications were developed in Australia. The history of this development program is presented in this paper. These lasers have been tested in several clinical programs and success with the gold vapour laser in cancer phototherapy using HpD has been achieved in various types of tumours. Trials have commenced on the use of the 578 nm yellow line of the copper vapour laser for dermatology and plastic surgery.

  14. Experimental study of multipass copper vapour laser amplifiers

    SciTech Connect

    Karpukhin, Vyacheslav T; Malikov, Mikhail M

    2008-12-31

    Repetitively pulsed multipass copper vapour amplifiers are studied experimentally. A considerable increase in the peak power of laser pulses was achieved by using a special scheme of the amplifier. It is found that the main reasons preventing an increase in the peak power during many passages of the beam are the competitive development of lasing from spontaneous seeds in a parasitic resonator formed by the fold mirrors of a multipass amplifier, a decrease in the amplification during the last passages, and an increase in the pulse width at the amplifier output. (lasers. amplifiers)

  15. Manufacturing diamond films using copper vapour lasers

    SciTech Connect

    McLean, M., LLNL

    1996-01-08

    Fifty nanosecond pulses of visible light have been used to produce hard, hydrogen-free diamond-like-carbon (DLC) films at irradiances between 5 x 10{sup 8} and 5 x 10{sup 10} W/cm{sup 2} The films were characterized by a number of techniques including: Raman spectroscopy, Electron Energy Loss Spectroscopy (EELS), atomic force microscopy, and spectroscopic ellipsometry. The cost for manufacturing DLC with high average power, high-pulse repetition frequency, visible light is low enough to compete with other diamond thin film production methods.

  16. Diode-pumped caesium vapour laser with closed-cycle laser-active medium circulation

    SciTech Connect

    Bogachev, A V; Garanin, Sergey G; Dudov, A M; Eroshenko, V A; Kulikov, S M; Mikaelian, G T; Panarin, V A; Pautov, V O; Rus, A V; Sukharev, Stanislav A

    2012-02-28

    The creation of a caesium vapour laser with closed-cycle circulation of the laser-active medium is first reported. The power of the laser radiation amounted to {approx}1 kW with the 'light-to-light' conversion efficiency of {approx}48 %. Quasi-two-dimensional computational model of the laser operation that provides adequate description of experimental results is considered. Calculated and experimental dependences of the laser radiation power on the temperature of the cuvette walls, laser medium pressure and pump power are presented.

  17. Application of copper vapour lasers for controlling activity of uranium isotopes

    SciTech Connect

    Barmina, E V; Sukhov, I A; Lepekhin, N M; Priseko, Yu S; Filippov, V G; Simakin, Aleksandr V; Shafeev, Georgii A

    2013-06-30

    Beryllium nanoparticles are generated upon ablation of a beryllium target in water by a copper vapour laser. The average size of single crystalline nanoparticles is 12 nm. Ablation of a beryllium target in aqueous solutions of uranyl chloride leads to a significant (up to 50 %) decrease in the gamma activity of radionuclides of the uranium-238 and uranium-235 series. Data on the recovery of the gamma activity of these nuclides to new steady-state values after laser irradiation are obtained. The possibility of application of copper vapour lasers for radioactive waste deactivation is discussed. (laser applications and other topics in quantum electronics)

  18. CONTROL OF LASER RADIATION PARAMETERS: Efficient 510 ? 578-nm conversion of emission of copper vapour lasers

    NASA Astrophysics Data System (ADS)

    D'yachkov, Aleksei B.; Labozin, Valerii P.

    2002-09-01

    The results of experiments on the 510 ? 578-nm conversion of high-power radiation from a copper vapour laser (CVL) in a dye cell are presented. The use of the efficient laser dye Pyrromethane 597 (PM-597) made it possible to convert the 120-W CVL radiation (72 W at 510 nm + 48 W at 578 nm) into 102-W radiation at 578 nm, which is equivalent to a conversion efficiency of 85%. Photostability of the dye in various solvents is studied. The photostability (more than 45 GJ mole-1) of PM-597 in n-heptane is found to be higher than that of Rh 6G in ethanol.

  19. Lasers, Understanding the Atom Series.

    ERIC Educational Resources Information Center

    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…

  20. Quantitative vapour-liquid visualization using laser-induced exciplex fluorescence

    NASA Astrophysics Data System (ADS)

    Kim, Jong-Uk; Hong, Byungyou

    2001-09-01

    We describe an optical technique for quantitative evaluation of the concentrations of coexisting vapour and liquid phases in a spray. A laser-induced exciplex fluorescence visualization system allows time-resolved two-dimensional fluorescence images of vapour and liquid distributions to be acquired simultaneously using two-colour emission. The method is based on the exciplex formers DMA (N,N-dimethylaniline) and 1,4,6-TMN (trimethylnaphthalene) in a non-polar solvent. We report here methods for quantitatively calibrating the liquid and vapour phases of a solution containing 90% isooctane, 5% DMA and 5% 1,4,6-TMN. The evaluation of fluorescence intensities yields quantitative two-dimensional concentration maps of liquid and vapour phases. This technique is expected to find applications in studying mixture formation in diesel or spark ignition engines with spectrally well-separated fluorescence images obtained from the monomer and exciplex constituents dissolved in a fuel.

  1. Diode laser frequency stabilisation for water-vapour differential absorption sensing

    NASA Astrophysics Data System (ADS)

    Matthey, R.; Schilt, S.; Werner, D.; Affolderbach, C.; Thvenaz, L.; Mileti, G.

    2006-11-01

    We describe a low-power continuous-wave laser system for water-vapour sensing applications in the 935-nm region. The system is based on extended-cavity diode lasers and distributed-feedback lasers and delivers four single-mode frequency-stabilised optical signals. Three lasers are locked to three water-vapour absorption lines of different strengths, whereas the fourth lies outside any absorption line. On-line stabilisation is performed by wavelength-modulation spectroscopy using compact water-vapour reference cells. An offset-locking technique implemented around an electrical filter is applied for the stabilisation of the off-line slave laser to an on-line master laser at a frequency detuning of 18.8 GHz. Stabilities in the order of 15 MHz over one day were observed for the strongest lines, at the detection limit of the measurement instrumentation. The developed techniques and schemes can be applied to other wavelength ranges and molecular species. Differential absorption lidar instrumentation can in particular benefit from such a system when the stabilised lasers serve as injection seeders to pulsed power oscillators.

  2. Model of the radial gas-temperature distribution in a copper bromide vapour laser

    SciTech Connect

    Iliev, I P; Gocheva-Ilieva, S G

    2010-08-27

    An analytic model is proposed to calculate the buffer-gas temperature in the discharge-tube cross section of the copper bromide vapour laser. The model is the generalisation of the previous models developed by the authors. Assuming that the volume electric power is arbitrary distributed over the tube radius, the general solution of the quasi-stationary heat conduction equation with the boundary conditions of the first and second kinds is presented. Application of the model is considered by the example of a copper bromide vapour laser emitting at 510.6 and 578.2 nm at different specific radial distributions of the volume power. The obtained results are compared with the temperature profiles known to date. Application of this model to molecular lasers is also discussed. (lasers)

  3. High-power copper vapour lasers and applications

    SciTech Connect

    Chang, J.J.; Warner, B.E.; Boley, C.D.; Dragon, E.P.

    1995-08-01

    Expanded applications of copper vapor lasers has prompted increased demand for higher power and better beam quality. This paper reports recent progress in laser power scaling, MOPA operation, beam quality improvement, and applications in precision laser machining. Issues such as gas heating, radial delay, discharge instability, and window heating will also be discussed.

  4. Atomic vapor laser isotope separation process

    DOEpatents

    Wyeth, R.W.; Paisner, J.A.; Story, T.

    1990-08-21

    A laser spectroscopy system is utilized in an atomic vapor laser isotope separation process. The system determines spectral components of an atomic vapor utilizing a laser heterodyne technique. 23 figs.

  5. Vapour phase growth and grain boundary structure of molybdenum disulphide atomic layers.

    PubMed

    Najmaei, Sina; Liu, Zheng; Zhou, Wu; Zou, Xiaolong; Shi, Gang; Lei, Sidong; Yakobson, Boris I; Idrobo, Juan-Carlos; Ajayan, Pulickel M; Lou, Jun

    2013-08-01

    Single-layered molybdenum disulphide with a direct bandgap is a promising two-dimensional material that goes beyond graphene for the next generation of nanoelectronics. Here, we report the controlled vapour phase synthesis of molybdenum disulphide atomic layers and elucidate a fundamental mechanism for the nucleation, growth, and grain boundary formation in its crystalline monolayers. Furthermore, a nucleation-controlled strategy is established to systematically promote the formation of large-area, single- and few-layered films. Using high-resolution electron microscopy imaging, the atomic structure and morphology of the grains and their boundaries in the polycrystalline molybdenum disulphide atomic layers are examined, and the primary mechanisms for grain boundary formation are evaluated. Grain boundaries consisting of 5- and 7- member rings are directly observed with atomic resolution, and their energy landscape is investigated via first-principles calculations. The uniformity in thickness, large grain sizes, and excellent electrical performance signify the high quality and scalable synthesis of the molybdenum disulphide atomic layers. PMID:23749265

  6. Vapour phase growth and grain boundary structure of molybdenum disulphide atomic layers

    NASA Astrophysics Data System (ADS)

    Najmaei, Sina; Liu, Zheng; Zhou, Wu; Zou, Xiaolong; Shi, Gang; Lei, Sidong; Yakobson, Boris I.; Idrobo, Juan-Carlos; Ajayan, Pulickel M.; Lou, Jun

    2013-08-01

    Single-layered molybdenum disulphide with a direct bandgap is a promising two-dimensional material that goes beyond graphene for the next generation of nanoelectronics. Here, we report the controlled vapour phase synthesis of molybdenum disulphide atomic layers and elucidate a fundamental mechanism for the nucleation, growth, and grain boundary formation in its crystalline monolayers. Furthermore, a nucleation-controlled strategy is established to systematically promote the formation of large-area, single- and few-layered films. Using high-resolution electron microscopy imaging, the atomic structure and morphology of the grains and their boundaries in the polycrystalline molybdenum disulphide atomic layers are examined, and the primary mechanisms for grain boundary formation are evaluated. Grain boundaries consisting of 5- and 7- member rings are directly observed with atomic resolution, and their energy landscape is investigated via first-principles calculations. The uniformity in thickness, large grain sizes, and excellent electrical performance signify the high quality and scalable synthesis of the molybdenum disulphide atomic layers.

  7. Atomic vapor laser isotope separation

    SciTech Connect

    Stern, R.C.; Paisner, J.A.

    1985-11-08

    Atomic vapor laser isotope separation (AVLIS) is a general and powerful technique. A major present application to the enrichment of uranium for light-water power reactor fuel has been under development for over 10 years. In June 1985 the Department of Energy announced the selection of AVLIS as the technology to meet the nation's future need for the internationally competitive production of uranium separative work. The economic basis for this decision is considered, with an indicated of the constraints placed on the process figures of merit and the process laser system. We then trace an atom through a generic AVLIS separator and give examples of the physical steps encountered, the models used to describe the process physics, the fundamental parameters involved, and the role of diagnostic laser measurements.

  8. Investigation of the vapour-plasma plume in the welding of titanium by high-power ytterbium fibre laser radiation

    NASA Astrophysics Data System (ADS)

    Bykovskiy, D. P.; Petrovskii, V. N.; Uspenskiy, S. A.

    2015-03-01

    The vapour-plasma plume produced in the welding of 6-mm thick VT-23 titanium alloy plates by ytterbium fibre laser radiation of up to 10 kW power is studied in the protective Ar gas medium. High-speed video filming of the vapour-plasma plume is used to visualise the processes occurring during laser welding. The coefficient of inverse bremsstrahlung by the welding plasma plume is calculated from the data of the spectrometric study.

  9. Microfabricated rubidium vapour cell with a thick glass core for small-scale atomic clock applications

    NASA Astrophysics Data System (ADS)

    Ptremand, Y.; Affolderbach, C.; Straessle, R.; Pellaton, M.; Briand, D.; Mileti, G.; de Rooij, N. F.

    2012-02-01

    This paper presents a new fabrication method to manufacture alkali reference cells having dimensions larger than standard micromachined cells and smaller than glass-blown ones, for use in compact atomic devices such as vapour-cell atomic clocks or magnetometers. The technology is based on anodic bonding of silicon and relatively thick glass wafers and fills a gap in cell sizes and technologies available up to now: on one side, microfabrication technologies with typical dimensions ? 2 mm and on the other side, classical glass-blowing technologies for typical dimensions of about 6-10 mm or larger. The fabrication process is described for cells containing atomic Rb and spectroscopic measurements (optical absorption spectrum and double resonance) are reported. The analysis of the bonding strength of our cells was performed and shows that the first anodic bonding steps exhibit higher bonding strengths than the later ones. The spectroscopic results show a good quality of the cells. From the double-resonance signals, we predict a clock stability of ?3 10-11 at 1 s of integration time, which compares well to the performance of compact commercial Rb atomic clocks.

  10. Legal requirements and guidelines for the control of harmful laser generated particles, vapours and gases

    NASA Astrophysics Data System (ADS)

    Horsey, John

    2015-07-01

    This paper is a review of the Health and Safety laws and guidelines relating to laser generated emissions into the workplace and outside environment with emphasis on the differences between legal requirements and guideline advice. The types and nature of contaminants released by various laser processes (i.e. cutting, coding, engraving, marking etc) are discussed, together with the best methods for controlling them to within legal exposure limits. A brief description of the main extract air filtration techniques, including the principles of particulate removal and the action of activated carbon for gas/vapour/odour filtration, is given.

  11. Copper bromide vapour laser with an output pulse duration of up to 320 ns

    NASA Astrophysics Data System (ADS)

    Gubarev, F. A.; Fedorov, V. F.; Fedorov, K. V.; Shiyanov, D. V.; Evtushenko, G. S.

    2016-01-01

    We report the development of a copper bromide vapour laser with an output pulse duration of up to 320 ns. To lengthen the pulse, the discharge current was limited using a compound switch comprising a pulsed hydrogen thyratron and a tacitron. This technique permits limiting the excitation of the working levels at the initial stage of the discharge development to lengthen the inversion lifetime. The longest duration of a laser pulse was reached in tubes 25 and 50 mm in diameter for a pulse repetition rate of 2 – 4 kHz.

  12. Hydride vapour phase epitaxy assisted buried heterostructure quantum cascade lasers for sensing applications

    NASA Astrophysics Data System (ADS)

    Lourdudoss, S.; Metaferia, W.; Junesand, C.; Manavaimaran, B.; Ferré, S.; Simozrag, B.; Carras, M.; Peretti, R.; Liverini, V.; Beck, M.; Faist, J.

    2015-01-01

    Buried heterostructure (BH) lasers are routinely fabricated for telecom applications. Development of quantum cascade lasers (QCL) for sensing applications has largely benefited from the technological achievements established for telecom lasers. However, new demands are to be met with when fabricating BH-QCLs. For example, hetero-cascade and multistack QCLs, with several different active regions stacked on top of each other, are used to obtain a broad composite gain or increased peak output power. Such structures have thick etch ridges which puts severe demand in carrying out regrowth of semi-insulating layer around very deeply etched (< 10 μm) ridges in short time to realize BH-QCL. For comparison, telecom laser ridges are normally only <5 μm deep. We demonstrate here that hydride vapour phase epitaxy (HVPE) is capable of meeting this new demand adequately through the fabrication of BH-QCLs in less than 45 minutes for burying ridges etched down to 10-15 μm deep. This has to be compared with the normally used regrowth time of several hours, e.g., in a metal organic vapour phase epitaxy (MOVPE) reactor. This includes also micro-stripe lasers resembling grating-like ridges for enhanced thermal dissipation in the lateral direction. In addition, we also demonstrate HVPE capability to realize buried heterostructure photonic crystal QCLs for the first time. These buried lasers offer flexibility in collecting light from the surface and relatively facile device characterization feasibility of QCLs in general; but the more important benefits of such lasers are enhanced light matter interaction leading to ultra-high cavity Q-factors, tight optical confinement, possibility to control the emitted mode pattern and beam shape and substantial reduction in laser threshold.

  13. Atomic-based stabilization for laser-pumped atomic clocks.

    PubMed

    Gerginov, V; Shah, V; Knappe, S; Hollberg, L; Kitching, J

    2006-06-15

    We describe a novel technique for stabilizing frequency shifts in laser-interrogated vapor-cell atomic clocks. The method suppresses frequency shifts due to changes in the laser frequency, intensity, and modulation index as well as atomic vapor density. The clock operating parameters are monitored by using the atoms themselves, rather than by using conventional schemes for laser frequency and cell temperature control. The experiment is realized using a chip-scale atomic clock. The novel atomic-based stabilization approach results in a simpler setup and improved long-term performance. PMID:16729092

  14. Atom Skimmers and Atom Lasers Utilizing Them

    NASA Technical Reports Server (NTRS)

    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.

  15. Wavelength-tunable sources of entangled photons interfaced with atomic vapours

    PubMed Central

    Trotta, Rinaldo; Martín-Sánchez, Javier; Wildmann, Johannes S.; Piredda, Giovanni; Reindl, Marcus; Schimpf, Christian; Zallo, Eugenio; Stroj, Sandra; Edlinger, Johannes; Rastelli, Armando

    2016-01-01

    The prospect of using the quantum nature of light for secure communication keeps spurring the search and investigation of suitable sources of entangled photons. A single semiconductor quantum dot is one of the most attractive, as it can generate indistinguishable entangled photons deterministically and is compatible with current photonic-integration technologies. However, the lack of control over the energy of the entangled photons is hampering the exploitation of dissimilar quantum dots in protocols requiring the teleportation of quantum entanglement over remote locations. Here we introduce quantum dot-based sources of polarization-entangled photons whose energy can be tuned via three-directional strain engineering without degrading the degree of entanglement of the photon pairs. As a test-bench for quantum communication, we interface quantum dots with clouds of atomic vapours, and we demonstrate slow-entangled photons from a single quantum emitter. These results pave the way towards the implementation of hybrid quantum networks where entanglement is distributed among distant parties using optoelectronic devices. PMID:26815609

  16. Wavelength-tunable sources of entangled photons interfaced with atomic vapours

    NASA Astrophysics Data System (ADS)

    Trotta, Rinaldo; Martín-Sánchez, Javier; Wildmann, Johannes S.; Piredda, Giovanni; Reindl, Marcus; Schimpf, Christian; Zallo, Eugenio; Stroj, Sandra; Edlinger, Johannes; Rastelli, Armando

    2016-01-01

    The prospect of using the quantum nature of light for secure communication keeps spurring the search and investigation of suitable sources of entangled photons. A single semiconductor quantum dot is one of the most attractive, as it can generate indistinguishable entangled photons deterministically and is compatible with current photonic-integration technologies. However, the lack of control over the energy of the entangled photons is hampering the exploitation of dissimilar quantum dots in protocols requiring the teleportation of quantum entanglement over remote locations. Here we introduce quantum dot-based sources of polarization-entangled photons whose energy can be tuned via three-directional strain engineering without degrading the degree of entanglement of the photon pairs. As a test-bench for quantum communication, we interface quantum dots with clouds of atomic vapours, and we demonstrate slow-entangled photons from a single quantum emitter. These results pave the way towards the implementation of hybrid quantum networks where entanglement is distributed among distant parties using optoelectronic devices.

  17. Wavelength-tunable sources of entangled photons interfaced with atomic vapours.

    PubMed

    Trotta, Rinaldo; Martn-Snchez, Javier; Wildmann, Johannes S; Piredda, Giovanni; Reindl, Marcus; Schimpf, Christian; Zallo, Eugenio; Stroj, Sandra; Edlinger, Johannes; Rastelli, Armando

    2016-01-01

    The prospect of using the quantum nature of light for secure communication keeps spurring the search and investigation of suitable sources of entangled photons. A single semiconductor quantum dot is one of the most attractive, as it can generate indistinguishable entangled photons deterministically and is compatible with current photonic-integration technologies. However, the lack of control over the energy of the entangled photons is hampering the exploitation of dissimilar quantum dots in protocols requiring the teleportation of quantum entanglement over remote locations. Here we introduce quantum dot-based sources of polarization-entangled photons whose energy can be tuned via three-directional strain engineering without degrading the degree of entanglement of the photon pairs. As a test-bench for quantum communication, we interface quantum dots with clouds of atomic vapours, and we demonstrate slow-entangled photons from a single quantum emitter. These results pave the way towards the implementation of hybrid quantum networks where entanglement is distributed among distant parties using optoelectronic devices. PMID:26815609

  18. Mercury determination by cold vapour atomic absorption spectrometry in several biological indicators from Lake Maracaibo, Venezuela.

    PubMed

    Colina de Vargas, M; Romero, R A

    1992-03-01

    Two sampling sessions were carried out in Lake Maracaibo and eight sites selected in four pairs one in front of the other (El Mojn-Ancn de iturre, Santa Cruz de Mara-Punta de Palmas, Maracaibo-Punta de Leiva and San Francisco-La Rita). Specimens of Cynoscin acoupa Maracaiboencis (curvina, n = 5), Oligoplites palometa (palometa, n = 5), Penaeus schmitti (shrimp, n = 20), and Polymesoda arctata (mussels, n = 20) were collected. For the curvina and palometa, muscle, brain, kidney, gill, liver and heart were analysed. Shrimp and mussels were analysed whole, without the shells. Samples were lyophilized and cold digested in a mixture of sulfuric, nitric and perchloric acids, potassium permanganate and hydrogen peroxide. Spectrometric determination was carried out using cold vapour atomic absorption spectrometry and sodium borohydride as reducing agent. Accuracy was tested with a National Institute of Standards and Technology (NIST) Standard Reference Material (SRM) RM50 Albacore Tuna, and against another method. The detection limit for Hg was 53 ng l-1. Good agreement was found between results for the analysis of SRM RM50 (Hg = 0.95 +/- 0.14 mg kg-1) and the assigned value furnished by NIST (Hg = 0.95 +/- 0.10 mg kg-1). Precision and the interference were also evaluated. Mercury concentrations in brain, kidney and heart tissues of the curvina and palometa were found to be higher than those in the muscle tissue. PMID:1580413

  19. Comparison of laser-ablation and hot-wall chemical vapour deposition techniques for nanowire fabrication

    NASA Astrophysics Data System (ADS)

    Stern, E.; Cheng, G.; Guthrie, S.; Turner-Evans, D.; Broomfield, E.; Lei, B.; Li, C.; Zhang, D.; Zhou, C.; Reed, M. A.

    2006-06-01

    A comparison of the transport properties of populations of single-crystal, In2O3 nanowires (NWs) grown by unassisted hot-wall chemical vapour deposition (CVD) versus NWs grown by laser-ablation-assisted chemical vapour deposition (LA-CVD) is presented. For nominally identical growth conditions across the two systems, NWs fabricated at 850 °C with laser-ablation had significantly higher average mobilities at the 99.9% confidence level, 53.3 ± 5.8 cm2 V-1 s-1 versus 10.2 ± 1.9 cm2 V-1 s-1. It is also observed that increasing growth temperature decreases mobility for LA-CVD NWs. Transmission electron microscopy studies of CVD-fabricated samples indicate the presence of an amorphous In2O3 region surrounding the single-crystal core. Further, low-temperature measurements verify the presence of ionized impurity scattering in low-mobility CVD-grown NWs.

  20. Tuneable, stabilised diode lasers for compact atomic frequency standards and precision wavelength references

    NASA Astrophysics Data System (ADS)

    Affolderbach, C.; Mileti, G.

    2005-03-01

    We describe the ongoing activities in Observatoire Cantonal de Neuchtel in the fields of precision laser spectroscopy and metrology of Rb atomic vapours. The work is motivated by the potentials of highly stable and narrowband laser light sources for a variety of technical and scientific applications. We describe the use of extended-cavity diode lasers for the realisation of such narrowband light sources and the basic schemes under study for their stabilisation, with focus on Doppler and sub-Doppler laser spectroscopy. The resulting laser systems offer good frequency stabilities and can be effectively miniaturised. This makes them interesting for direct applications of these techniques, as well as the presently developed precision instruments: compact atomic frequency standards for ground and space applications (GALILEO satellite positioning system), secondary optical frequency standards, transportable extended cavity diode lasers as seeding lasers, and others.

  1. A simple laser system for atom interferometry

    NASA Astrophysics Data System (ADS)

    Merlet, S.; Volodimer, L.; Lours, M.; Pereira Dos Santos, F.

    2014-07-01

    We present here a simple laser system for a laser-cooled atom interferometer, where all functions (laser cooling, interferometry and detection) are realized using only two extended cavity laser diodes, amplified by a common tapered amplifier. One laser is locked by frequency modulation transfer spectroscopy, the other being phase locked with an offset frequency determined by an field-programmable gate array-controlled direct digital synthesizer, which allows for efficient and versatile tuning of the laser frequency. Raman lasers are obtained with a double pass acoustooptic modulator. We demonstrate a gravimeter using this laser system, with performances close to the state of the art.

  2. Push-Pull Laser-Atomic Oscillator

    SciTech Connect

    Jau, Y.-Y.; Happer, W.

    2007-11-30

    A vapor of alkali-metal atoms in the external cavity of a semiconductor laser, pumped with a time-independent injection current, can cause the laser to self-modulate at the 'field-independent 0-0 frequency' of the atoms. Push-pull optical pumping by the modulated light drives most of the atoms into a coherent superposition of the two atomic sublevels with an azimuthal quantum number m=0. The atoms modulate the optical loss of the cavity at the sharply defined 0-0 hyperfine frequency. As in a maser, the system is not driven by an external source of microwaves, but a very stable microwave signal can be recovered from the modulated light or from the modulated voltage drop across the laser diode. Potential applications for this new phenomenon include atomic clocks, the production of long-lived coherent atomic states, and the generation of coherent optical combs.

  3. Push-pull laser-atomic oscillator.

    PubMed

    Jau, Y-Y; Happer, W

    2007-11-30

    A vapor of alkali-metal atoms in the external cavity of a semiconductor laser, pumped with a time-independent injection current, can cause the laser to self-modulate at the "field-independent 0-0 frequency" of the atoms. Push-pull optical pumping by the modulated light drives most of the atoms into a coherent superposition of the two atomic sublevels with an azimuthal quantum number m=0. The atoms modulate the optical loss of the cavity at the sharply defined 0-0 hyperfine frequency. As in a maser, the system is not driven by an external source of microwaves, but a very stable microwave signal can be recovered from the modulated light or from the modulated voltage drop across the laser diode. Potential applications for this new phenomenon include atomic clocks, the production of long-lived coherent atomic states, and the generation of coherent optical combs. PMID:18233280

  4. Atom laser based on Raman transitions

    NASA Astrophysics Data System (ADS)

    Moy, G. M.; Hope, J. J.; Savage, C. M.

    1997-05-01

    In this paper we present an atom laser scheme using a Raman transition for the output coupling of atoms. A beam of thermal atoms (bosons) in a metastable atomic state is pumped into a multimode atomic cavity. This cavity is coupled through spontaneous emission to another cavity for the atomic ground state. Above a certain threshold pumping rate a large number of atoms build up in the lowest energy state of the second cavity, while the higher energy states remain unpopulated. Atoms are then coupled to the outside of the cavity with a Raman transition. This changes the internal level of the atom and imparts a momentum kick, allowing the atoms to leave the system. We propose an implementation of our scheme using hollow optical-fiber atom waveguides.

  5. Q-switching of neodymium-doped solid-state lasers by molecular caesium vapour

    NASA Astrophysics Data System (ADS)

    Ezekian, S. T.; Mikhaelian, S. A.; Petrosian, K. B.; Pokhsrarian, K. M.

    1989-04-01

    Molecular caesium vapor was employed for passive Q switching in YAG:Nd, glass:Nd, YAL:Nd, GSGG Cr,Nd, and YLF:Nd lasers. The results demonstrate that the laser output pulse duration can be simply controlled by means of Cs2 vapor temperature variation. It is noted that the negative sign of the nonlinear refractive index n2 of atomic Cs at the 1.06-micron wavelength implies that such nonlinear effects as self-focusing and phase modulation (occurring in the powerful amplifying stages of lasers) can be compensated for.

  6. Conservation laws and laser cooling of atoms

    NASA Astrophysics Data System (ADS)

    Giuliani, Giuseppe

    2015-11-01

    The straightforward application of energy and linear momentum conservation to the absorption/emission of photons by atoms allows us to establish the essential features of laser cooling of two level atoms at low laser intensities. The lowest attainable average kinetic energy of the atoms depends on the ratio {{? }}/{E}{{R}} between the natural linewidth and the recoil energy and tends to ER as {{? }}/{E}{{R}} tends to zero (in one dimension). This treatment, like the quantum mechanical ones, is valid for any value of the ratio {{? }}/{E}{{R}} and contains the semiclassical theory of laser cooling as the limiting case in which {E}{{R}}\\ll {{? }}.

  7. Laser Spectroscopy of Atoms and Molecules.

    ERIC Educational Resources Information Center

    Schawlow, Arthur L.

    1978-01-01

    Surveys new laser techniques and a variety of spectroscopic experiments that can be used to detect, measure and study very small numbers of atoms on molecules. The range of applicability of these techniques is also included. (HM)

  8. Atomic-vapor-laser isotope separation

    SciTech Connect

    Davis, J.I.

    1982-10-01

    This paper gives a brief history of the scientific considerations leading to the development of laser isotope separation (LIS) processes. The close relationship of LIS to the broader field of laser-induced chemical processes is evaluated in terms of physical criteria to achieve an efficient production process. Atomic-vapor LIS processes under development at Livermore are reviwed. 8 figures.

  9. Design for an optical cw atom laser

    PubMed Central

    Ashkin, Arthur

    2004-01-01

    A new type of optical cw atom laser design is proposed that should operate at high intensity and high coherence and possibly record low temperatures. It is based on an optical-shepherd technique, in which far-off-resonance blue-detuned swept sheet laser beams are used to make new types of high-density traps, atom waveguides, and other components for achieving very efficient BoseEinstein condensation and cw atom laser operation. A shepherd-enhanced trap is proposed that should be superior to conventional magneto-optic traps for the initial collection of molasses-cooled atoms. A type of dark-spot optical trap is devised that can cool large numbers of atoms to polarization-gradient temperatures at densities limited only by three-body collisional loss. A scheme is designed to use shepherd beams to capture and recycle essentially all of the escaped atoms in evaporative cooling, thereby increasing the condensate output by several orders of magnitude. Condensate atoms are stored in a shepherd trap, protected from absorbing light, under effectively zero-gravity conditions, and coupled out directly into an optical waveguide. Many experiments and devices may be possible with this cw atom laser. PMID:15302937

  10. Laser Cooled Atomic Clocks in Space

    NASA Technical Reports Server (NTRS)

    Thompson, R. J.; Kohel, J.; Klipstein, W. M.; Seidel, D. J.; Maleki, L.

    2000-01-01

    The goals of the Glovebox Laser-cooled Atomic Clock Experiment (GLACE) are: (1) first utilization of tunable, frequency-stabilized lasers in space, (2) demonstrate laser cooling and trapping in microgravity, (3) demonstrate longest 'perturbation-free' interaction time for a precision measurement on neutral atoms, (4) Resolve Ramsey fringes 2-10 times narrower than achievable on Earth. The approach taken is: the use of COTS components, and the utilization of prototype hardware from LCAP flight definition experiments. The launch date is scheduled for Oct. 2002. The Microgravity Science Glovebox (MSG) specifications are reviewed, and a picture of the MSG is shown.

  11. Vapour-liquid coexistence curves of the united-atomand anisotropic united-atom force fields for alkane mixtures

    NASA Astrophysics Data System (ADS)

    Delhommelle, Jerome; Boutin, Anne; Tavitian, Bernard; Mackie, Allan D.; Fuchs, Alain H.

    The performances of two categories of force field for mixtures of alkanes are compared. Configurational-bias Monte Carlo simulations in the Gibbs ensemble were carried out to compute the vapour-liquid coexistence curves (VLCC) for pure n-pentane and n-dodecane and for binary mixtures of these components with methane. The united-atom (UA) force field (Siepmann and coworkers) and the anisotropic united-atom (AUA) force field (Toxvaerd) were used in this study. It is shown that the use of the recently readjusted versions of these potential forms together with the Lorentz-Berthelot mixing rules yields a description of the VLCC of methane-n alkane binary mixtures that is as accurate as the description of the pure component obtained with the same UA/AUA force field.

  12. Transverse flow CW atomic iodine laser system

    SciTech Connect

    Schlie, L. A.; Rathge, R. D.

    1985-08-13

    A transverse flow CW atomic iodine laser system uses a closed cycle fuel system to operate in a continuous mode. An elliptical pump cell having a Hg arc lamp cooled by deionized water irradiates with UV energy C/sub 3/F/sub 7/I gas to produce excited atomic iodine. A transverse flow section attached to the pump cell channels C/sub 3/F/sub 7/I gas into a laser cell where lasing occurs. The flow section has upstream and downstream flow cavities, triangular shaped, that channel the laser gas. A diffuser and flow straighteners are placed in these cavities to make the flow velocity across the transverse laser axis as uniform as possible so as to produce very stable laser gain output.

  13. Photonic metamaterials by direct laser writing and silver chemical vapour deposition.

    PubMed

    Rill, Michael S; Plet, Christine; Thiel, Michael; Staude, Isabelle; von Freymann, Georg; Linden, Stefan; Wegener, Martin

    2008-07-01

    Metamaterials are artificial materials that--unlike natural substances--enable magnetism to be achieved at optical frequencies. The vast majority of photonic metamaterials has been fabricated by electron-beam lithography and evaporation of metal films, both of which are well-established two-dimensional (2D) technologies. Although stacking of three or four functional layers made using these methods has been reported, a truly 3D fabrication approach would be preferable for 3D photonic metamaterials. Here, we report first steps in this direction by using a combination of direct laser writing and silver chemical vapour deposition--the 3D analogues of electron-beam lithography and evaporation, respectively. The optical characterization of a planar test structure composed of elongated split-ring resonators is in good agreement with theory. Retrieval of the effective optical parameters reveals the importance of bi-anisotropy. Once suitable theoretical blueprints are available, our fabrication approach will enable rapid prototyping of truly 3D photonic metamaterials. PMID:18469820

  14. Strain and structure heterogeneity in MoS2 atomic layers grown by chemical vapour deposition.

    PubMed

    Liu, Zheng; Amani, Matin; Najmaei, Sina; Xu, Quan; Zou, Xiaolong; Zhou, Wu; Yu, Ting; Qiu, Caiyu; Birdwell, A Glen; Crowne, Frank J; Vajtai, Robert; Yakobson, Boris I; Xia, Zhenhai; Dubey, Madan; Ajayan, Pulickel M; Lou, Jun

    2014-01-01

    Monolayer molybdenum disulfide (MoS2) has attracted tremendous attention due to its promising applications in high-performance field-effect transistors, phototransistors, spintronic devices and nonlinear optics. The enhanced photoluminescence effect in monolayer MoS2 was discovered and, as a strong tool, was employed for strain and defect analysis in MoS2. Recently, large-size monolayer MoS2 has been produced by chemical vapour deposition, but has not yet been fully explored. Here we systematically characterize chemical vapour deposition-grown MoS2 by photoluminescence spectroscopy and mapping and demonstrate non-uniform strain in single-crystalline monolayer MoS2 and strain-induced bandgap engineering. We also evaluate the effective strain transferred from polymer substrates to MoS2 by three-dimensional finite element analysis. Furthermore, our work demonstrates that photoluminescence mapping can be used as a non-contact approach for quick identification of grain boundaries in MoS2. PMID:25404060

  15. Prospects of laser cooling in atomic thallium

    SciTech Connect

    Fan, Isaac; Chen, Tzu-Ling; Liu, Yu-Sheng; Lien, Yu-Hung; Liu, Yi-Wei; Shy, Jow-Tsong

    2011-10-15

    One of the most precisely determined upper limits for the electron electric dipole moment (EDM) is set by the thallium (Tl) atomic beam experiment. One way to enhance the sensitivity of the atomic beam setup is to laser cool the Tl atoms to reduce the EDM-like phase caused by the Exv effect. In this report, a cooling scheme based on the 6P{sub 3/2}(F=2){r_reversible}6D{sub 5/2}(F{sup '}=3) transition in Tl is proposed. The absolute frequency measurement of this nearly closed-cycle transition was performed in an atomic beam apparatus. Two Ti:sapphire lasers were frequency-doubled using enhancement cavities in X-type configurations to provide the needed 377- and 352-nm light sources for the optical pumping and cooling transitions, respectively. The absolute frequency of this cooling transition is determined to be 851 634 646(56) MHz.

  16. Laser trapping of {sup 21}Na atoms

    SciTech Connect

    Lu, Zheng-Tian

    1994-09-01

    This thesis describes an experiment in which about four thousand radioactive {sup 21}Na (t{sub l/2} = 22 sec) atoms were trapped in a magneto-optical trap with laser beams. Trapped {sup 21}Na atoms can be used as a beta source in a precision measurement of the beta-asymmetry parameter of the decay of {sup 21}Na {yields} {sup 21}Ne + {Beta}{sup +} + v{sub e}, which is a promising way to search for an anomalous right-handed current coupling in charged weak interactions. Although the number o trapped atoms that we have achieved is still about two orders of magnitude lower than what is needed to conduct a measurement of the beta-asymmetry parameter at 1% of precision level, the result of this experiment proved the feasibility of trapping short-lived radioactive atoms. In this experiment, {sup 21}Na atoms were produced by bombarding {sup 24}Mg with protons of 25 MeV at the 88 in. Cyclotron of Lawrence Berkeley Laboratory. A few recently developed techniques of laser manipulation of neutral atoms were applied in this experiment. The {sup 21}Na atoms emerging from a heated oven were first transversely cooled. As a result, the on-axis atomic beam intensity was increased by a factor of 16. The atoms in the beam were then slowed down from thermal speed by applying Zeeman-tuned slowing technique, and subsequently loaded into a magneto-optical trap at the end of the slowing path. The last two chapters of this thesis present two studies on the magneto-optical trap of sodium atoms. In particular, the mechanisms of magneto-optical traps at various laser frequencies and the collisional loss mechanisms of these traps were examined.

  17. One-atom correlated-emission laser

    SciTech Connect

    Kim, Ho-Joon; Lee, Hai-Woong; Khosa, Ashfaq H.; Zubairy, M. Suhail

    2008-02-15

    We study a four-level double-{lambda} atomic configuration working as a two photon linear amplifier where two atomic transitions independently interact with cavity mode, while the other transitions are driven by a strong pump field. It is found that our system always works as a phase sensitive linear amplifier with no window for a phase insensitive linear amplifier. We also investigate that the system behaves as a two-photon correlated-emission laser under certain conditions.

  18. Determination of total mercury in environmental and biological samples by flow injection cold vapour atomic absorption spectrometry

    NASA Astrophysics Data System (ADS)

    Murphy, James; Jones, Phil; Hill, Steve J.

    1996-12-01

    A simple and accurate method has been developed for the determination of total mercury in environmental and biological samples. The method utilises an off-line microwave digestion stage followed by analysis using a flow injection system with detection by cold vapour atomic absorption spectrometry. The method has been validated using two certified reference materials (DORM-1 dogfish and MESS-2 estuarine sediment) and the results agreed well with the certified values. A detection limit of 0.2 ng g -1 Hg was obtained and no significant interference was observed. The method was finally applied to the determination of mercury in river sediments and canned tuna fish, and gave results in the range 0.1-3.0 mg kg -1.

  19. Active narrowband filtering, line narrowing and gain using ladder electromagnetically induced transparency in an optically thick atomic vapour

    NASA Astrophysics Data System (ADS)

    Keaveney, James; Sargsyan, Armen; Sarkisyan, David; Papoyan, Aram; Adams, Charles S.

    2014-04-01

    Electromagnetically induced transparency (EIT) resonances using the 5S1/2 ? 5P3/2 ? 5D5/2 ladder-system in optically thick Rb atomic vapour are studied. We observe a strong line narrowing effect and gain at the 5S1/2 ? 5P3/2 transition wavelength due to an energy-pooling assisted frequency conversion with characteristics similar to 4-wave mixing. As a result it is possible to observe tunable and switchable transparency resonances with amplitude close to 100% and a linewidth of 15 MHz. In addition, the large line narrowing effect allows resolution of 85Rb 5D5/2 hyperfine structure even in the presence of strong power broadening.

  20. Optimal laser positioning for laser-assisted atom probe tomography.

    PubMed

    Koelling, S; Innocenti, N; Bogdanowicz, J; Vandervorst, W

    2013-09-01

    Laser-assisted atom probe tomography is a material analysis method based on field evaporating ions from a tip-shaped sample by a combination of a standing electric field and a short (pico- or femtosecond) laser pulse. The laser-pulse thereby acts as a starting signal for a time-of-flight mass analysis of the ions whereby the thermal energy deposited in the tip by the laser pulse temporarily enables the evaporation of ions from the surface of the tip. Here we will use simulations of the laser absorption on a silicon tip to find the optimal position of the laser spot in order to maximize the mass resolution achieved during the experiments. We will confirm our simulations by showing that the experimentally observed mass resolution indeed changes as predicted by the simulations. PMID:23578966

  1. Influence of the voltage pulse front shortening on the pulse repetition rate in a copper vapour laser

    SciTech Connect

    Bokhan, P A; Gugin, P P; Zakrevskii, D E; Lavrukhin, M A; Kazaryan, M A; Lyabin, N A

    2013-08-31

    The lasing characteristics of a copper vapour laser are investigated in the regime of a pulse train excited in the internalheating tube with the diameter of 2 cm and length of 48 cm. Two power supply schemes are compared: a conventional scheme with a storage capacitor discharged through a thyratron connected to a peaking capacitor and the scheme in which the peaking capacitor is connected to the laser active element through a kivotron – a fast switch based on the 'open discharge' with a turn-on time of less than 1 ns. It is shown that in the considered range of the pulse repetition rates f = 2 – 16 kHz in the first case we deal with a typical energy dependence on frequency having a maximum near 4 – 5 kHz. In the second case, the lasing energy is frequency-independent; hence, the average power in this range is proportional to f. The results obtained are explained by the neutralised influence of the initial electron concentration on energy characteristics of the copper vapour laser. (control of laser radiation parameters)

  2. Measuring variations of ?18O and ?2H in atmospheric water vapour using laser spectroscopy: an instrument characterisation study

    NASA Astrophysics Data System (ADS)

    Aemisegger, F.; Sturm, P.; Graf, P.; Sodemann, H.; Pfahl, S.; Knohl, A.; Wernli, H.

    2012-02-01

    Variations of stable water isotopes in water vapour have become measurable at a measurement frequency of about 1 Hz in recent years using novel laser spectroscopic techniques. This enables us to perform continuous measurements for process-based investigations of the atmospheric water cycle at the time scales relevant for synoptic meteorology. An important prerequisite for the interpretation of data from automated field measurements lasting for several weeks or months is a detailed knowledge about instrument properties and the sources of measurement uncertainty. We present here a comprehensive characterisation and comparison study of two commercial laser spectroscopic systems based on cavity ring-down spectroscopy (Picarro) and off-axis integrated cavity output spectroscopy (Los Gatos Research). The uncertainty components of the measurements were first assessed in laboratory experiments, focussing on the effects of (i) water vapour mixing ratio, (ii) measurement stability, (iii) uncertainties due to calibration and (iv) response times of the isotope measurements due to adsorption-desorption processes on the tubing and measurement cavity walls. Based on the experience from our laboratory experiments we set up a one-week field campaign for comparing measurements of the ambient isotope signals of the two laser spectroscopic systems. The optimal calibration strategy determined for both instruments was applied as well as the correction functions for water vapour mixing ratio effects. The root mean square difference between the isotope signals from the two instruments during the field deployment was 2.3 for ?2H, 0.5 for ?18O and 3.1 for deuterium excess. These uncertainty estimates from field measurements compare well to those found in the laboratory experiments. The present quality of measurements from laser spectroscopic instruments combined with a calibration system opens new possibilities for investigating the atmospheric water cycle and the land-atmosphere moisture fluxes.

  3. Multiple absorption of laser photons by atoms.

    NASA Technical Reports Server (NTRS)

    Faisal, F. H. M.

    1973-01-01

    Using a space translation operation, it is shown that the Schroedinger equation for an atom in an external electromagnetic field can be solved with sufficient accuracy to obtain the transition probabilities for multiphoton absorption from a monochromatic laser beam of arbitrary intensity or frequency. The specific applicability conditions of the method are discussed.

  4. Laser manipulation of atomic and molecular flows

    NASA Astrophysics Data System (ADS)

    Lilly, Taylor C.

    The continuing advance of laser technology enables a range of broadly applicable, laser-based flow manipulation techniques. The characteristics of these laser-based flow manipulations suggest that they may augment, or be superior to, such traditional electro-mechanical methods as ionic flow control, shock tubes, and small scale wind tunnels. In this study, methodology was developed for investigating laser flow manipulation techniques, and testing their feasibility for a number of aerospace, basic physics, and micro technology applications. Theories for laser-atom and laser-molecule interactions have been under development since the advent of laser technology. The theories have yet to be adequately integrated into kinetic flow solvers. Realizing this integration would greatly enhance the scaling of laser-species interactions beyond the realm of ultra-cold atomic physics. This goal was realized in the present study. A representative numerical investigation, of laser-based neutral atomic and molecular flow manipulations, was conducted using near-resonant and non-resonant laser fields. To simulate the laser interactions over a range of laser and flow conditions, the following tools were employed: a custom collisionless gas particle trajectory code and a specifically modified version of the Direct Simulation Monte Carlo statistical kinetic solver known as SMILE. In addition to the numerical investigations, a validating experiment was conducted. The experimental results showed good agreement with the numerical simulations when experimental parameters, such as finite laser line width, were taken into account. Several areas of interest were addressed: laser induced neutral flow steering, collimation, direct flow acceleration, and neutral gas heating. Near-resonant continuous wave laser, and non-resonant pulsed laser, interactions with cesium and nitrogen were simulated. These simulations showed trends and some limitations associated with these interactions, used for flow steering and collimation. The use of one of these interactions, the induced dipole force, was extended beyond a single Gaussian laser field. The interference patterns associated with counter-propagating laser fields, or "optical lattices," were shown to be capable of both direct species acceleration and gas heating. This study resulted in predictions for a continuous, resonant laser-cesium flow with accelerations of 106 m/s2. For this circumstance, a future straightforward proof of principle experiment has been identified. To demonstrate non-resonant gas heating, a series of pulsed optical lattices were simulated interacting with neutral non-polar species. An optimum time between pulses was identified as a function of the collisional relaxation time. Using the optimum time between pulses, molecular nitrogen simulations showed an increase in gas temperature from 300 K to 2470 K at 1 atm, for 50 successive optical lattice pulses. A second proof of principle experiment was identified for future investigation.

  5. Secondary laser cooling of strontium-88 atoms

    NASA Astrophysics Data System (ADS)

    Strelkin, S. A.; Khabarova, K. Yu.; Galyshev, A. A.; Berdasov, O. I.; Gribov, A. Yu.; Kolachevsky, N. N.; Slyusarev, S. N.

    2015-07-01

    The secondary laser cooling of a cloud of strontium-88 atoms on the 1 S 0-3 P 1 (689 nm) intercombination transition captured into a magneto-optical trap has been demonstrated. We describe in detail the recapture of atoms from the primary trap operating on the strong 1 S 0-1 P 1 (461 nm) transition and determine the recapture coefficient ?, the number of atoms, and their temperature in the secondary trap as a function of experimental parameters. A temperature of 2 K has been reached in the secondary trap at the recapture coefficient ? = 6%, which confirms the secondary cooling efficiency and is sufficient to perform metrological measurements of the 1 S 0-3 P 1 (698 nm) clock transition in an optical lattice.

  6. Evidence for laser cooling in a magnesium atomic beam

    SciTech Connect

    Beverini, N.; De Pascalis, S.; Maccioni, E.; Pereira, D.; Strumia, F.; Vissani, G.; Wang, Y.Z.; Novero, C.

    1989-04-01

    Laser cooling in a Mg atomic beam is reported for the first time to our knowledge. Previous cooling experiments were performed by using visible or infrared lasers. The Mg atoms were cooled by using an intracavity frequency-doubled dye laser at 285 nm to reach the resonant /sup 1/S/sub 0/--/sup 1/P/sub 1/ transition. Evidence of laser cooling was obtained even with the limited available laser power (approx. =1--2 mW).

  7. Navigating more precisely with laser clocks

    NASA Astrophysics Data System (ADS)

    Mileti, Gaetano; Affolderbach, Christoph; Droz, Fabien; Murphy, Eamonn

    2005-05-01

    The development of the key technologies, particularly in terms of reliable diode lasers and atomic vapour cells, will pave the way towards low-power and miniature - ultimately chip-scale - atomic clocks for industrial and domestic use.

  8. Gravitational Wave Detection with Single-Laser Atom Interferometers

    NASA Technical Reports Server (NTRS)

    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.

  9. Bose condensates and the atom laser

    NASA Astrophysics Data System (ADS)

    Andrews, Michael R.

    In this thesis, I describe four classes of studies of cold, dilute vapors of atomic sodium. The in-situ nondestructive observation of a Bose condensate is presented in the broader context of imaging a cold polarized cloud. Two condensates were made to interfere, and a rudimentary ``atom laser'' was demonstrated. Excitations of a condensate were imaged in- situ and nondestructively, opening up the field of real- time dynamical studies. A related study attempting (unsuccessfully) to create and detect superfluid currents and vortices is discussed. Lastly, Feshbach resonances were used to modify the interactions in a Bose condensate, and the scattering length was observed to vary by over a factor of ten. (Copies available exclusively from MIT Libraries, Rm. 14-0551, Cambridge, MA 02139-4307. Ph. 617-253-5668; Fax 617-253-1690.)

  10. Atomic spectroscopy with laser and synchrotron radiation

    SciTech Connect

    van de Meulen, P. . Lab. voor Fysische Chemie Oak Ridge National Lab., TN ); de Beer, E.; de Lange, C.A. . Lab. voor Fysische Chemie); Westwood, N.P.C. . Lab. voor Fysische Chemie Guelph Univ., ON . Guelph-Waterloo Centre for Graduate Work in Chemistry); Krause, M.O. (Oak Ridge National

    1991-01-01

    Oxygen and nitrogen atoms which play a crucial role in many chemical processes are studied with photoelectron spectroscopy. In the case of oxygen synchrotron radiation is employed to study the inner-valence excitation region between 20 and 30 eV and detailed information about bound-continuum interactions between discrete Rydberg levels and various ionization continua is obtained. In the case of nitrogen laser multiphoton ionization is employed to study extensive novel Rydberg series below the lowest ionization energy which show appreciable local perturbations arising from bound-bound interactions. 26 refs., 3 figs., 1 tab.

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

    NASA Astrophysics Data System (ADS)

    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 are also studied. Design and construction of a new linear magnetic atom guide is detailed. This guide beta has many improvements over the original guide alpha: a Zeeman slower, magnetic injection, a physical shutter, and surface adsorption evaporative cooling are some of the main changes. Testing of this new system is underway. It is hoped that the improvements to guide beta will yield an atom density sufficient to reach degeneracy, thereby forming a continuous BEC at the end of the guide. The BEC, which will be continuously replenished by the atoms within the guide, will be outcoupled to form a continuous atom laser.

  12. Laser theory with finite atom-field interacting time

    NASA Astrophysics Data System (ADS)

    Yu, Deshui; Chen, Jingbiao

    2008-07-01

    We investigate the influence of atomic transit time τ on the laser linewidth by the quantum Langevin approach. With comparing the bandwidths of cavity mode κ , atomic polarization γab , and atomic transit broadening τ-1 , we study the laser linewidth in different limits. We also discuss the spectrum of fluctuations of output field and the influence of pumping statistics on the output field.The influence of atomic transit time τ on laser field has not been carefully discussed before, to our knowledge. In particular, a laser operating in the region of γab≪τ-1≪κ/2 appears not to have been analyzed in previous laser theories. Our work could be a useful complementarity to laser theory. It is also an important theoretical foundation for the recently proposed active optical atomic clock based on bad-cavity laser mechanism.

  13. Increasing the output power of single 808-nm laser diodes using diamond submounts produced by microwave plasma chemical vapour deposition

    SciTech Connect

    Ashkinazi, E E; Bezotosnyi, V V; Bondarev, Vadim Yu; Kovalenko, V I; Konov, Vitalii I; Krokhin, Oleg N; Oleshchenko, V A; Pevtsov, Valerii F; Popov, Yurii M; Popovich, A F; Ral'chenko, Viktor G; Cheshev, E A

    2012-11-30

    We have designed and fabricated submounts from synthetic diamond grown by microwave plasma chemical vapour deposition and developed an economical process for metallising such submounts. Laser diode chips having an 808-nm emission wavelength, 3-mm-long cavity and 130-mm-wide stripe contact were mounted on copper heat sinks with the use of diamond submounts differing in quality. The devices were tested for more than 150 h in continuous mode at an output power of 8 W on diamond with a thermal conductivity of 700 W m{sup -1} K{sup -1}, and no changes in their output power were detected. On diamond with a thermal conductivity of 1600 W m{sup -1} K{sup -1}, stable cw operation for 24 h at an output power of 12 W was demonstrated. (letters)

  14. Method validation for the determination of total mercury in fish muscle by cold vapour atomic absorption spectrometry.

    PubMed

    Nascimento Neto, A P; Costa, L C S Magalhães; Kikuchi, A N S; Furtado, D M S; Araujo, M Q; Melo, M C C

    2012-01-01

    A method was validated for the determination of total Hg in fish muscle using continuous flow cold vapour atomic absorption (CVAAS) after microwave digestion in closed vessels. The method was validated according to European Union Regulations 333/2007 and 657/2002, considering the maximum level for the metal in fish, established by European Union regulation 1881/2006. The procedure for determining linear range, selectivity, recovery, precision, trueness, decision limit (CCα), detection capability (CCβ), measurement uncertainty and robustness of the method is reported. The results of the validation process demonstrate the method fulfils the provisions of the Commission Regulation. The selectivity study indicated that there was no matrix effect on the calibration curve between the concentration range of 1.0 and 30.0 µg Hg l(-1). The mean recovery calculated at six levels of fortification was in the range of 94-104%. The limit of detection (LOD) and limit of quantification (LOQ) values were 4.90 and 15.7 µg kg(-1), while the CCα and CCβ values were 0.517 and 0.533 mg kg(-1), respectively, for the maximum contaminant level of 0.500 mg kg(-1). The relative expanded measurement uncertainty of the method was 0.055 mg kg(-1). The method was not affected by slight variations of some critical factors (ruggedness minor changes) as sample mass and volume of the HNO(3) and H(2)O(2) used in the digestion step. The method allowed accurate confirmation analyses of the CRM DORM 3. In fact, the Z-scores attained in a proficiency test round were well below the reference value of 2.0, proving the excellent performance of the laboratory. PMID:22250927

  15. Measuring fast variations of ?^{18}O and ?^2H in atmospheric water vapour using laser spectroscopy: an instrument inter-comparison and characterisation study

    NASA Astrophysics Data System (ADS)

    Aemisegger, F.; Sturm, P.; Graf, P.; Sodemann, H.; Pfahl, S.; Knohl, A.; Wernli, H.

    2012-04-01

    Fast variations of stable water isotopes in water vapour have become measurable lately using novel laser spectroscopic techniques. This allows us to perform process-based investigations of the atmospheric water cycle at the time scales of significant weather events. An important prerequisite for such studies implying automatic field measurements lasting for several weeks or even months is a detailed knowledge about sources of uncertainty and instrument properties. We present a comprehensive characterisation and comparison study of two commercial laser spectroscopic systems based on cavity ring-down spectroscopy (Picarro) and off-axis integrated cavity output spectroscopy (Los Gatos Resarch). The old versions (L1115-i, WVIA) and the new versions (L2130-i, WVIA-EP) of both systems were tested. The uncertainty components of the measurements were assessed in laboratory experiments, focussing on effects of (i) water vapour mixing ratio, (ii) measurement stability, (iii) uncertainties due to calibration and (iv) response times of the isotope measurements due to adsorption-desorption processes on the tubing and measurement cavity walls. Knowledge from our laboratory experiments was used to setup a one-week field campaign for comparing measurements of the ambient isotope signals from the L1115-i and WVIA systems. The optimal calibration strategy determined for both instruments was applied as well as the correction functions for water vapour mixing ratio effects. Using this field measurement data we address the question of how well the deuterium excess (d=?2H-8?18O) of atmospheric water vapour can be determined with laser spectroscopy. The deuterium excess is an interesting parameter for process-based atmospheric water cycle studies, which depends on humidity and temperature conditions at source location of water vapour. Up to now only very few high-time-resolution measurements of deuterium excess exist. Our concurrent measurements of atmospheric isotopes in water vapour using the two analysers allow us to evaluate the precision and accuracy of atmospheric deuterium-excess measurements.

  16. Dual-Beam Atom Laser Driven by Spinor Dynamics

    NASA Technical Reports Server (NTRS)

    Thompson, Robert; Lundblad, Nathan; Maleki, Lute; Aveline, David

    2007-01-01

    An atom laser now undergoing development simultaneously generates two pulsed beams of correlated Rb-87 atoms. (An atom laser is a source of atoms in beams characterized by coherent matter waves, analogous to a conventional laser, which is a source of coherent light waves.) The pumping mechanism of this atom laser is based on spinor dynamics in a Bose-Einstein condensate. By virtue of the angular-momentum conserving collisions that generate the two beams, the number of atoms in one beam is correlated with the number of atoms in the other beam. Such correlations are intimately linked to entanglement and squeezing in atomic ensembles, and atom lasers like this one could be used in exploring related aspects of Bose-Einstein condensates, and as components of future sensors relying on atom interferometry. In this atom-laser apparatus, a Bose-Einstein condensate of about 2 x 10(exp 6) Rb-87 atoms at a temperature of about 120 micro-K is first formed through all-optical means in a relatively weak singlebeam running-wave dipole trap that has been formed by focusing of a CO2-laser beam. By a technique that is established in the art, the trap is loaded from an ultrahigh-vacuum magnetooptical trap that is, itself, loaded via a cold atomic beam from an upstream two-dimensional magneto-optical trap that resides in a rubidium-vapor cell that is differentially pumped from an adjoining vacuum chamber, wherein are performed scientific observations of the beams ultimately generated by the atom laser.

  17. A compact laser system for the cold atom gravimeter

    NASA Astrophysics Data System (ADS)

    Wang, Qiyu; Wang, Zhaoying; Fu, Zhijie; Liu, Weiyong; Lin, Qiang

    2016-01-01

    With the rapid development of the technologies in the field of laser cooling atoms, a portable and stable laser system is urgently required for the wide applications based on the cold atoms. In this paper, we report a modular laser system for a gravimeter based on atom interferometry, which enable us to realize high-precision gravity measurements outside of laboratory. The system is based on two distributed feedback (DFB) laser diodes of 1560 nm, which are used as the master laser and the reference laser respectively. The frequency of the reference laser is locked on a rubidium transition, the master laser is frequency locked on the reference one by the method of beat locking. The master laser is power amplified firstly by the erbium-doped fiber amplifier (EDFA), and then frequency doubled by using a periodically poled lithium niobate (PPLN) crystal to obtain 1 W laser output at 780 nm. The repumping and Raman lasers are generated by adding an electro-optic modulation on the master laser, featuring extremely low phase noise. With this laser system, we obtain a cloud of 87Rb atoms with a temperature of 5 μKin a magneto-optical trapping. And a gravity resolution of 1.0 ×10-8 g within 200 s integration time is reached.

  18. Nonlinear spectroscopy of cold atoms in diffuse laser light.

    PubMed

    Zhang, Wen-Zhuo; Cheng, Hua-Dong; Xiao, Ling; Liu, Liang; Wang, Yu-Zhu

    2009-02-16

    The nonlinear spectroscopy of cold atoms in the diffuse laser cooling system is studied in this paper. We present the theoretical models of the recoil-induced resonances (RIR) and the electromagnetically-induced absorption (EIA) of cold atoms in diffuse laser light, and show their signals in an experiment of cooling (87)Rb atomic vapor in an integrating sphere. The theoretical results are in good agreement with the experimental ones when the light intensity distribution in the integrating sphere is considered. The differences between nonlinear spectra of cold atoms in the diffuse laser light and in the optical molasses are also discussed. PMID:19219193

  19. An investigation on the effects of side assisting gas flow and metallic vapour jet on the stability of keyhole and molten pool during laser full-penetration welding

    NASA Astrophysics Data System (ADS)

    Zhang, Linjie; Zhang, Jianxun; Zhang, Guifeng; Bo, Wu; Gong, Shuili

    2011-04-01

    This paper reports on a study aiming at separating the effects of side assisting gas flow from a metallic vapour jet on the transient behaviour of a molten pool and a keyhole during laser full-penetration welding. To achieve the research purpose, laser welding process was simulated under three different conditions: in the presence of both side gas flow and metallic vapour jet, in the presence of side gas flow alone and in the presence of metallic vapour jet alone. It was found that the side gas flow not only pushed the molten melt to flow towards the rear part of the molten pool but also formed, on the molten pool surface, a proper pressure distribution which helped maintain both the humping in the rear part of the molten pool and the concave around the upper exit of the keyhole. Under the condition with side gas flow, the swelling formed around the keyhole blocked the side gas flow and on the other hand the side gas flow pushed them to flow backwards to the rear part of the molten pool more effectively, thereby enlarging and stabilizing the keyhole exit. Furthermore, the peak value of the average pressure in the region composed of the molten pool and keyhole decreased step by step with the growth of the concave. Finally, the interaction between the metallic vapour and molten melt was well controlled using the side gas flow, which led to an improvement in the stability of the molten pool and a reduction in spatters and pores.

  20. Development of laser excited atomic fluorescence and ionization methods

    SciTech Connect

    Winefordner, J.D.

    1991-01-01

    Progress report: May 1, 1988 to December 31, 1991. The research supported by DE-FG05-88ER13881 during the past (nearly) 3 years can be divided into the following four categories: (1) theoretical considerations of the ultimate detection powers of laser fluorescence and laser ionization methods; (2) experimental evaluation of laser excited atomic fluorescence; (3) fundamental studies of atomic and molecular parameters in flames and plasmas; (4) other studies.

  1. Laser techniques for spectroscopy of core-excited atomic levels

    NASA Technical Reports Server (NTRS)

    Harris, S. E.; Young, J. F.; Falcone, R. W.; Rothenberg, J. E.; Willison, J. R.

    1982-01-01

    We discuss three techniques which allow the use of tunable lasers for high resolution and picosecond time scale spectroscopy of core-excited atomic levels. These are: anti-Stokes absorption spectroscopy, laser induced emission from metastable levels, and laser designation of selected core-excited levels.

  2. Laser Methods in the Study of Nuclei, Atoms and Molecules

    NASA Astrophysics Data System (ADS)

    Inamura, Takashi T.

    2005-01-01

    The VIth International Workshop on Application of Lasers in Atomic Nuclei Research was held at Adam Mickiewicz University, Poznan in Poland from May 24 to 27, 2004. Its title this year was "Laser methods in the study of nuclei, atoms and molecules". Some topics are reviewed from a viewpoint of the atomic physics contribution to nuclear physics and its applications. It is suggested how this meeting should be organized in the future by taking the new geopolitics into account.

  3. Compact Laser System for Field Deployable Ultracold Atom Sensors

    NASA Astrophysics Data System (ADS)

    Pino, Juan; Luey, Ben; Anderson, Mike

    2013-05-01

    As ultracold atom sensors begin to see their way to the field, there is a growing need for small, accurate, and robust laser systems to cool and manipulate atoms for sensing applications such as magnetometers, gravimeters, atomic clocks and inertial sensing. In this poster we present a laser system for Rb, roughly the size of a paperback novel, capable of generating and controlling light sufficient for the most complicated of cold atom sensors. The system includes >100dB of non-mechanical, optical shuttering, the ability to create short, microsecond pulses, a Demux stage to port light onto different optical paths, and an atomically referenced, frequency agile laser source. We will present data to support the system, its Size Weight and Power (SWaP) requirements, as well as laser stability and performance. funded under DARPA

  4. Miniature, atomically referenced offset phase-locked laser for cold-atom sensors

    NASA Astrophysics Data System (ADS)

    Pino, Juan; Luey, Ben; Bickman, Sarah; Anderson, Mike

    2012-06-01

    As ultracold atom sensors begin to see their way to the field, there is a growing need for small, accurate, and robust laser systems to cool and manipulate atoms for sensing applications such as magnetometers, gravimeters, atomic clocks and inertial sensing. In this poster we present an ultracompact, frequency agile laser source, referenced to a hyperfine transition of ^87Rb. The laser system is housed in a package roughly the size of a stack of business cards, is hermetically sealed, and contains no moving parts -- ideal for field deployment. The laser system includes two lasers with independent temperature control, a Rb-filled vapor cell, a high-speed photodetector for monitoring the offset frequency between the lasers, as well the necessary optical isolation. We will present designs of the ultracompact laser system, as well as quantitative results including size, weight, expected power consumption, frequency agility, and frequency stability.

  5. Investigations of laser pumped gas cell atomic frequency standard

    NASA Technical Reports Server (NTRS)

    Volk, C. H.; Camparo, J. C.; Fueholz, R. P.

    1982-01-01

    The performance characteristics of a rubidium gas cell atomic frequency standard might be improved by replacing the standard rubidium discharge lamp with a single mode laser diode. Aspects of the laser pumped gas cell atomic clock studied include effects due to laser intensity, laser detuning, and the choice of the particular atomic absorption line. Results indicate that the performance of the gas cell clock may be improved by judicious choice of the operating parameters of the laser diode. The laser diode also proved to be a valuable tool in investigating the operation of the conventional gas cell clock. Results concerning linewidths, the light shift effect and the effect of isotopic spin exchange in the conventional gas cell clock are reported.

  6. Recent progress of laser cooling for neutral mercury atom

    NASA Astrophysics Data System (ADS)

    Liu, Kang-Kang; Zhao, Ru-Chen; Fu, Xiao-Hu; Hu, Jin-Meng; Feng, Yan; Xu, Zhen; Wang, Yu-Zhu

    2014-11-01

    Mercury is the heaviest stable atom that could be laser cooled, and have a large nuclear charge number. So it has a distinct advantage in quantum precision measurement such as fine-structure constant ? and permanent electric dipole moment. Due to its insensitivity of black body radiation, atomic mercury is a good candidate of optical clock. Here we report our recent development of laser cooling of neutral mercury atom. By cooling the mercury source to about -70C, an ultra-high vacuum system was realized to produce ultracold mercury atoms. The commercial frequency quadrupled semiconductor laser is locked on the cooling transition (1S0-3P1 transition, wavelength of 253.7 nm) by sub-Doppler frequency modulation spectroscopy. By the modification with feed-forward method, the UV laser becomes faster tunable and more stable. A folded beam configuration was used to realize the magneto-optical trap (MOT) because of the shortage of cooling laser power, and the ultracold mercury atoms were observed by fluorescence detection. All of six rich abundant isotopes have been observed, and the atom number is about 1.5106 with density of 3.5109 /cm3 for 202Hg. With optical shutter and the programmable system to control the time sequence, the temperature of ultracold atoms can be measured by time of flight method. To enhance the laser power, a 1014.8 nm fiber laser amplifier was developed, which can work at room temperature. After two stages of frequency doubling, about 75 mW of 253.7 nm UV laser were generated, and the saturated absorption spectroscopy of mercury atom was also observed. More power of UV laser could help to trap more atoms in the future. These works laid a good foundation to realize the mercury lattice clock.

  7. Collisions and photoionization of laser-cooled atoms: When atoms go bump in the light

    SciTech Connect

    Ratliff, L.

    1996-05-01

    Advances in laser cooling of neutral atoms have made possible a new form of high resolution spectoscopy: photoassociation of ultracold atoms. Colliding neutral atoms, confined in a laser trap, are photoassociated to bound excited states of the dimer molecule by absorbing a photon from a tunable laser. The technique can probe long range and {open_quote}purely long range{close_quote} molecular states that are difficult or impossible to detect by traditional means and, because of the extremely low energy of the colliding atoms (1 mK), is capable of high resolution (0.001 cm{minus}1). Recent results include, the first direct (and most precise) measurement of a molecular dissociation limit, the first observation of retardation effects in atom-atom interactions, high precision measurements of atomic lifetimes, and the study of exotic states of alkali dimers.

  8. Development of a sequential injection system for trace mercury determination by cold vapour atomic absorption spectrometry utilizing an integrated gas-liquid separator/reactor.

    PubMed

    Anthemidis, Aristidis N; Zachariadis, George A; Stratis, John A

    2004-11-15

    A simple and robust time-based on-line sequential injection system for trace mercury determination via cold vapour atomic absorption spectrometry (CVAAS), employing a new integrated gas-liquid separator (GLS), which in parallel operates as reactor, was developed. Sample and reductant are sequentially loaded into the GLS while an argon flow delivers the released mercury vapour through the atomic absorption cell. The proposed method is characterized by the ability of successfully managing variable sample volume up to 30ml in order to achieve high sensitivity. For 20ml sample volume, the sampling frequency is 25h(-1). The calibration curve is linear over the concentration range 0.05-5.0mugl(-1) of Hg(II), the detection limit is c(L) = 0.02mugl(-1), and the relative standard deviation is s(r) = 2.6% at 1.0mugl(-1) Hg(II) level. The performance of the proposed method was evaluated by analyzing certified reference material and applied to the analysis of natural waters and biological samples. PMID:18969711

  9. Optically pumped semiconductor lasers for atomic and molecular physics

    NASA Astrophysics Data System (ADS)

    Burd, S.; Leibfried, D.; Wilson, A. C.; Wineland, D. J.

    2015-03-01

    Experiments in atomic, molecular and optical (AMO) physics rely on lasers at many different wavelengths and with varying requirements on spectral linewidth, power and intensity stability. Optically pumped semiconductor lasers (OPSLs), when combined with nonlinear frequency conversion, can potentially replace many of the laser systems currently in use. We are developing a source for laser cooling and spectroscopy of Mg+ ions at 280 nm, based on a frequency quadrupled OPSL with the gain chip fabricated at the ORC at Tampere Univ. of Technology, Finland. This OPSL system could serve as a prototype for many other sources used in atomic and molecular physics.

  10. Adiabatic Theory of Ionization of Atoms by Intense Laser Pulses

    NASA Astrophysics Data System (ADS)

    Morishita, Toru; Tolstikhin, Oleg I.

    We present the adiabatic theory of ionization of atoms by intense ultrashort laser pulses. We discuss a trilobite-like structure in a photoelectron spectrum generated by a pulse of overbarrier intensity.

  11. Laser Produced Plasma Takle Atomic and Nuclear Processes

    NASA Astrophysics Data System (ADS)

    Belyaev, Vadim

    2000-03-01

    It is demonstrated that the transformation of superstrong fields in a laser-produced plasma by atomic structures leads to the generation of magnetic fields in an atom, which destroy the internal structure of low-lying electronic shells and give rise to the wave collapse, or nucleation, of the fields with subsequent strong action on nuclei. The mechanism behind the direct transfer (inner conversion) of energy of excited nuclei due to electrons is analyzed. Electromagnetic stimulation of artificial radioactivity in a laser-produced plasma is considered. The developed theory makes it possible to account for the mechanism of nuclear fusion of elements with light-weight nuclei in a laser-produced plasma. The first results of experiments on electromagnetic stimulation of atomic and nuclear processes in a laser-produced plasma excited under the action of terawatt laser radiation on a target are presented. The present work was supported by International Science and Technology Center under Project number 856.

  12. Probing Molecules with Laser-Cooled Atomic Ions

    NASA Astrophysics Data System (ADS)

    Brown, Kenneth R.

    2012-06-01

    Trapped, laser-cooled atomic ions can be controlled with unprecedented precision and accuracy as demonstrated by both atomic ion clocks and prototype quantum computing devices. By trapping a mixture of laser-cooled atomic and molecular ions, the molecular ions will be sympathetically cooled to millikelvin temperatures. The reaction dynamics and spectroscopy of the molecular ion can then be observed without the thermal distribution of ion motion. Furthermore, the bright fluorescence of the atomic ion can be used as a signal for obtaining information about the molecular ion via the Coulombic interaction. In this talk, I will present our work towards performing single molecular ion spectroscopy on an atomic ion - molecular ion pair. I will discuss fundamental limits and applications of the technique for astrochemistry and the direct laser-cooling of molecular ions.

  13. Quantum kinetic theory model of a continuous atom laser

    NASA Astrophysics Data System (ADS)

    Dennis, G. R.; Davis, Matthew J.; Hope, J. J.

    2012-07-01

    We investigate the feasible limits for realizing a continuously evaporated atom laser with high-temperature sources. A plausible scheme for realizing a truly continuous atom laser is to outcouple atoms from a partially condensed Bose gas while continuously reloading the system with noncondensed thermal atoms and performing evaporative cooling. Here we use quantum kinetic theory to model this system and estimate feasible limits for the operation of such a scheme. For sufficiently high temperatures, the figure of merit for the source is shown to be the phase-space flux. The dominant process limiting the usage of sources with low phase-space flux is the three-body loss of the condensed gas. We conclude that certain double-magneto-optical trap sources may produce substantial mean condensate numbers through continuous evaporation and provide an atom laser source with a narrow linewidth and reasonable flux.

  14. EFFECTS OF LASER RADIATION ON MATTER. LASER PLASMA: Dynamics of a plasma formed by a surface optical-discharge in a metal vapour interacting with a cw CO2 laser beam

    NASA Astrophysics Data System (ADS)

    Zaikin, A. E.; Levin, A. V.; Petrov, A. L.

    1995-02-01

    A surface optical-discharge plasma was formed in a metal vapour under normal conditions by steady-state irradiation with a cw CO2 laser delivering radiation of moderate (2-4.5 MW cm-2) intensity. This plasma strongly screened the irradiated surface. Under the selected experimental conditions the optical discharge was not a continuous (steady-state) process. The plasma cloud was displaced along the beam out of the waist to a region where the laser radiation intensity was almost an order of magnitude less than the threshold for excitation of the optical-discharge plasma in the vapour. A strong screening of the metal surface, which could even completely stop evaporation of the metal, was observed. Self-oscillations of the optical-discharge plasma were observed for the first time in a vapour interacting with cw CO2 radiation: this was attributed to screening of the target surface. Within one period of the self-oscillations there were additional hf plasma pulsations which led to stratification of the plasma cloud. The results obtained were interpreted.

  15. Coupling of non-selective adsorption with selective elution for novel in-line separation and detection of cadmium by vapour generation atomic absorption spectrometry.

    PubMed

    Zhang, Yanlin; Adeloju, Samuel B

    2015-05-01

    Non-selective adsorption of Cd(2+) ions on a cation exchange fiber and subsequent selective elution with a KI solution has been strategically utilized to develop a highly selective in-line separation of Cd(2+) ions from other metal ions for its rapid and reliable quantification by cold vapour-atomic absorption spectrometry. After retention of Cd(2+) with a high efficiency on cation exchange fiber, selective elution of the retained Cd(2+) was subsequently accomplished with 0.3M KI. Vapour generation of Cd for in-line CV-AAS determination was then achieved by merging the eluate with HCl and NaBH4. Interferences from most base metals with the vapour generation of Cd were eliminated by this approach, with the exception of Pb(2+)ions which was removed by co-precipitation with BaSO4 prior to the in-line separation. Substantial improvement in sensitivity of the in-line CV-AAS determination of Cd was achieved by increasing the sample loading time. A detection limit of 0.6 ng L(-1) (3σ) was obtained with sample loading time of 120 s, corresponding to a consumption of 24 mL of sample solution. Application of the method to the determination of Cd in certified sediment and fish samples gave a good agreement with the certified values. Further validation by recovery study in real fish sample digests and water gave average Cd recoveries of 98.7±1.0% for fish and 92±3% for water with RSD of 1.5% for fish and 4% for water, respectively. PMID:25770618

  16. Infiltrating a thin or single-layer opal with an atomic vapour: Sub-Doppler signals and crystal optics

    NASA Astrophysics Data System (ADS)

    Moufarej, Elias; Maurin, Isabelle; Zabkov, Ilya; Laliotis, Athanasios; Ballin, Philippe; Klimov, Vasily; Bloch, Daniel

    2014-10-01

    Artificial thin glass opals can be infiltrated with a resonant alkali-metal vapour, providing novel types of hybrid systems. The reflection at the interface between the substrate and the opal yields a resonant signal, which exhibits sub-Doppler structures in linear spectroscopy for a range of oblique incidences. This result is suspected to originate in an effect of the three-dimensional confinement of the vapour in the opal interstices. It is here extended to a situation where the opal is limited to a few- or even a single-layer opal film, which is a kind of bidimensional grating. We have developed a flexible one-dimensional layered optical model, well suited for a Langmuir-Blodgett opal. Once extended to the case of a resonant infiltration, the model reproduces quick variations of the lineshape with incidence angle or polarization. Alternately, for an opal limited to a single layer of identical spheres, a three-dimensional numerical calculation was developed. It predicts crystalline anisotropy, which is demonstrated through diffraction on an empty opal made of a single layer of polystyrene spheres.

  17. Strongly driven one-atom laser and decoherence monitoring

    SciTech Connect

    Lougovski, P.; Casagrande, F.; Lulli, A.; Solano, E.

    2007-09-15

    We propose the implementation of a strongly driven one-atom laser, based on the off-resonant interaction of a three-level atom in {lambda} configuration with a single cavity mode and three laser fields. We show that the system can be described equivalently by a two-level atom resonantly coupled to the cavity and driven by a strong effective coherent field. The effective dynamics can be solved exactly, including a thermal field bath, allowing an analytical description of field statistics and entanglement properties. We also show the possible generation of quantum superposition (Schroedinger cat) states for the whole atom-field system and for the field alone after atomic measurement. We propose a way to monitor the system decoherence by measuring atomic populations. Finally, we confirm the validity of our model through numerical solutions.

  18. Ferric ion induced enhancement of ultraviolet vapour generation coupled with atomic fluorescence spectrometry for the determination of ultratrace inorganic arsenic in surface water.

    PubMed

    Wang, Yuelong; Lin, Lingling; Liu, Jixin; Mao, Xuefei; Wang, Jianhua; Qin, Deyuan

    2016-02-01

    A novel method of ultraviolet vapour generation (UVG) coupled with atomic fluorescence spectrometry (AFS) was developed for the determination of ultratrace inorganic arsenic (iAs) in surface water. In this work, different ferric species were utilised for the first time as an enhancement reagent for the ultraviolet vapour generation of As(iii), and their UVG efficiencies for volatile species of arsenic were investigated. 15 mg L(-1) of ferric chloride provided the greatest enhancement of approximately 10-fold, using 20% acetic acid combined with 4% formic acid with 30 s ultraviolet irradiation at 200 mL min(-1) Ar/H2 flow rate. Under the optimised conditions, the linear range was 1.0 ?g L(-1)-100.0 ?g L(-1), and the spiked recoveries were 92%-98%. The limit of detection was 0.05 ?g L(-1) for iAs, and the relative standard deviation (RSD) value of the repeated measurements was 2.0% (n = 11). This method was successfully applied to the determination of ultratrace iAs in tap water, river water, and lake water samples using 0.2% H2SO4 (v?:?v) as the sample preserver. The obtained values for the water samples of certified reference materials (CRMs) including GSB-Z50004-200431, GBW08605 and GBW(E)080390 were all within the certified ranges. PMID:26765360

  19. Time-based on-line preconcentration cold vapour generation procedure for ultra-trace mercury determination with inductively coupled plasma atomic emission spectrometry.

    PubMed

    Anthemidis, Aristidis N; Zachariadis, George A; Michos, Christos E; Stratis, John A

    2004-07-01

    A time-based sequential dispensing on-line column preconcentration procedure for mercury determination at trace levels by cold vapour generation inductively coupled plasma atomic emission spectrometry (CV-ICP-AES), by means of a unified module of a preconcentration column and a gas-liquid separator (PCGLS) is described. The complex of mercury formed on-line with ammonium pyrrolidine dithiocarbamate (APDC) is retained on the surface of the hydrophobic poly(tetrafluoroethylene) (PTFE) turnings, which are packed into the lower compartment of the PCGLS. Subsequently, mercury vapour is generated directly on the PTFE turnings by reductant SnCl(2) and separated from the liquid mixture via the PCGLS by argon purge gas. The outlet of the PCGLS is connected directly to the torch adapter of the plasma without the normal spray chamber and nebulizer. With 60-s preconcentration time and 12.0 mL min(-1) sample flow rate, the sampling frequency is 30 h(-1). The calibration curve is linear over the concentration range 0.02-5.0 microg L(-1), the detection limit ( c(L)) is 0.01 microg L(-1) and the relative standard deviation ( s(r)) is 3.1% at the 1.0 microg L(-1) level. The proposed method was evaluated by analysis of BCR CRM 278 (Mytilus Edulis) reference material and applied to the determination of total mercury in digested urine, blood and hair samples. PMID:15067491

  20. Laser stripping of hydrogen atoms by direct ionization

    SciTech Connect

    Brunetti, E.; Becker, W.; Bryant, H. C.; Jaroszynski, D. A.; Chou, W.

    2015-05-08

    Direct ionization of hydrogen atoms by laser irradiation is investigated as a potential new scheme to generate proton beams without stripping foils. The time-dependent Schrdinger equation describing the atom-radiation interaction is numerically solved obtaining accurate ionization cross-sections for a broad range of laser wavelengths, durations and energies. Parameters are identified where the Doppler frequency up-shift of radiation colliding with relativistic particles can lead to efficient ionization over large volumes and broad bandwidths using currently available lasers.

  1. Laser stripping of hydrogen atoms by direct ionization

    DOE PAGESBeta

    Brunetti, E.; Becker, W.; Bryant, H. C.; Jaroszynski, D. A.; Chou, W.

    2015-05-08

    Direct ionization of hydrogen atoms by laser irradiation is investigated as a potential new scheme to generate proton beams without stripping foils. The time-dependent Schrödinger equation describing the atom-radiation interaction is numerically solved obtaining accurate ionization cross-sections for a broad range of laser wavelengths, durations and energies. Parameters are identified where the Doppler frequency up-shift of radiation colliding with relativistic particles can lead to efficient ionization over large volumes and broad bandwidths using currently available lasers.

  2. Measuring variations of ?18O and ?2H in atmospheric water vapour using two commercial laser-based spectrometers: an instrument characterisation study

    NASA Astrophysics Data System (ADS)

    Aemisegger, F.; Sturm, P.; Graf, P.; Sodemann, H.; Pfahl, S.; Knohl, A.; Wernli, H.

    2012-07-01

    Variations of stable water isotopes in water vapour have become measurable at a measurement frequency of about 1 Hz in recent years using novel laser spectroscopic techniques. This enables us to perform continuous measurements for process-based investigations of the atmospheric water cycle at the time scales relevant for synoptic and mesoscale meteorology. An important prerequisite for the interpretation of data from automated field measurements lasting for several weeks or months is a detailed knowledge about instrument properties and the sources of measurement uncertainty. We present here a comprehensive characterisation and comparison study of two commercial laser spectroscopic systems based on cavity ring-down spectroscopy (Picarro) and off-axis integrated cavity output spectroscopy (Los Gatos Research). The uncertainty components of the measurements were first assessed in laboratory experiments, focussing on the effects of (i) water vapour mixing ratio, (ii) measurement stability, (iii) uncertainties due to calibration and (iv) response times of the isotope measurements due to adsorption-desorption processes on the tubing and measurement cavity walls. Based on the experience from our laboratory experiments, we set up a one-week field campaign for comparing measurements of the ambient isotope signals from the two laser spectroscopic systems. The optimal calibration strategy determined for both instruments was applied as well as the correction functions for water vapour mixing ratio effects. The root mean square difference between the isotope signals from the two instruments during the field deployment was 2.3 for ?2H, 0.5 for ?18O and 3.1 for deuterium excess. These uncertainty estimates from field measurements compare well to those found in the laboratory experiments. The present quality of measurements from laser spectroscopic instruments combined with a calibration system opens new possibilities for investigating the atmospheric water cycle and the land-atmosphere moisture fluxes.

  3. Solar-simulator-pumped atomic iodine laser kinetics

    NASA Technical Reports Server (NTRS)

    Wilson, H. W.; Raju, S.; Shiu, Y. J.

    1983-01-01

    The literature contains broad ranges of disagreement in kinetic data for the atomic iodine laser. A kinetic model of a solar-simulator-pumped iodine laser is used to select those kinetic data consistent with recent laser experiments at the Langley Research Center. Analysis of the solar-simulator-pumped laser experiments resulted in the following estimates of rate coefficients: for alkyl radical (n-C3F7) and atomic iodine (I) recombination, 4.3 x 10 to the 11th power (1.9) + or - cu cm/s; for n-C3F7I stabilized atomic iodine recombination (I + I) 3.7 x 10 to the -32nd power (2.3) + or -1 cm to the 6th power/s; and for molecular iodine (I2) quenching, 3.1 x 10 to the -11th power (1.6) + or - 1 cu cm/s. These rates are consistent with the recent measurements.

  4. Quantum optical master equations: The one-atom laser

    NASA Astrophysics Data System (ADS)

    Ginzel, Christian; Briegel, Hans-Jrgen; Martini, Ullrich; Englert, Berthold-Georg; Schenzle, Axel

    1993-07-01

    We present a detailed numerical study of the one-atom laser, that is, a single two-level atom interacting with one lasing mode, whereby both the atom and the photon field are coupled to reservoirs. The stationary as well as the dynamical properties of the model are calculated directly from the quantum master equation with the help of two numerical methods. These numerical methods do not need any quasi-probability representation and they do not require approximations. We find that the one-atom laser exhibits most of the typical features of a normal laser. In the region far below threshold some aspects, among them the linewidth, are changed due to eigenvalues of the master equation with imaginary parts. In this regime the complexity of the eigenvalues prominently enters the dynamical behavior.

  5. Two-Photon Coherent Atomic Absorption of Multiple Laser Beams

    NASA Astrophysics Data System (ADS)

    Li, Ming-Chiang

    2006-05-01

    Physical processes on two-photon coherent atomic absorption of multiple laser beams were discussed about thirty years ago [M. C. Li, Bull. Am. Phys. Soc. 20, 654 (1975)]. These processes can be divided into two distinct groups. In the first group, laser beams are from a single source, and in the second group laser beams are from two different sources [M. C. Li, Phys. Rev. A 22 (1980) 1323]. Several experiments in the first group were carried out and have led to the 2005 Nobel Prize in physics. The second group is more interesting. Beside atoms are in random motion, two photons are from different sources. Classically, it is impossible for atoms to transit coherently in the absorption process, but quantum mechanically, such a transition is possible and that is one of the spooky phenomena in quantum mechanic. To assure the coherent transition, each photon as absorbed by the atom must have two possible paths of choices. If one photon has the choice and other one is not, then the atomic transitions cannot be coherent. Around1990, there were very active experimental pursuits on such a spooky phenomenon of two photons emitted from crystal parametric down conversion. The present talk will review various spooky phenomena associated with two-photon coherent atomic absorption. Hope that the talk will stimulate the interest on the long neglected experimental front on two-photon coherent atomic absorption from two different laser sources.

  6. Laser Assisted Free-Free Transition in Electron - Atom Collision

    NASA Technical Reports Server (NTRS)

    Sinha, C.; Bhatia, A. K.

    2011-01-01

    Free-free transition is studied for electron-Hydrogen atom system in ground state at very low incident energies in presence of an external homogeneous, monochromatic and linearly polarized laser field. The incident electron is considered to be dressed by the laser in a non perturbative manner by choosing the Volkov solutions in both the channels. The space part of the scattering wave function for the electron is solved numerically by taking into account the effect of electron exchange, short range as well as of the long range interactions. Laser assisted differential as well as elastic total cross sections are calculated for single photon absorption/emission in the soft photon limit, the laser intensity being much less than the atomic field intensity. A strong suppression is noted in the laser assisted cross sections as compared to the field free situations. Significant difference is noted in the singlet and the triplet cross sections.

  7. Recirculation of Laser Power in an Atomic Fountain

    NASA Technical Reports Server (NTRS)

    Enzer, Daphna G.; Klipstein, WIlliam M.; Moore, James D.

    2007-01-01

    A new technique for laser-cooling atoms in a cesium atomic fountain frequency standard relies on recirculation of laser light through the atom-collection region of the fountain. The recirculation, accomplished by means of reflections from multiple fixed beam-splitter cubes, is such that each of two laser beams makes three passes. As described below, this recirculation scheme offers several advantages over prior designs, including simplification of the laser system, greater optical power throughput, fewer optical and electrical connections, and simplification of beam power balancing. A typical laser-cooled cesium fountain requires the use of six laser beams arranged as three orthogonal pairs of counter-propagating beams to decelerate the atoms and hold them in a three-dimensional optical trap in vacuum. Typically, these trapping/cooling beams are linearly polarized and are positioned and oriented so that (1) counter-propagating beams in each pair have opposite linear polarizations and (2) three of the six orthogonal beams have the sum of their propagation directions pointing up, while the other three have the sum of their propagation directions pointing down. In a typical prior design, two lasers are used - one to generate the three "up" beams, the other to generate the three "down" beams. For this purpose, the output of each laser is split three ways, then the resulting six beams are delivered to the vacuum system, independently of each other, via optical fibers. The present recirculating design also requires two lasers, but the beams are not split before delivery. Instead, only one "up" beam and one oppositely polarized "down" beam are delivered to the vacuum system, and each of these beams is sent through the collection region three times. The polarization of each beam on each pass through the collection region is set up to yield the same combination of polarization and propagation directions as described above. In comparison with the prior design, the present recirculating design utilizes the available laser light more efficiently, making it possible to trap more atoms at a given laser power or the same number of atoms at a lower laser power. The present design is also simpler in that it requires fewer optical fibers, fiber couplings, and collimators, and fewer photodiodes for monitoring beam powers. Additionally, the present design alleviates the difficulty of maintaining constant ratios among power levels of the beams within each "up" or "down" triplet.

  8. Simplified atom trap using a single microwave modulated diode laser

    SciTech Connect

    Newbury, N.R.; Myatt, C.J.; Wieman, C.E.

    1993-05-01

    We have demonstrated microwave modulation of a diode laser which is operated with optical feedback from a diffraction grating. By directly modulating the diode laser current at frequencies up to 6.8 GHz, we observed 2-30% of the laser power in a single sideband for 20mW of microwave power. Using such a diode laser modulated at 6.6GHz, we have trapped {sup 87}Rb in a vapor cell. With 10mW of microwave power, the number of trapped atoms was only 15% smaller than the number obtained using two lasers in the conventional manner. A microwave modulated diode laser should also be useful for driving stimulated Raman transitions between the hyperfine levels of Rb or Cs.

  9. A Theory of Laser Induced Nuclear Reaction in Single Atoms

    SciTech Connect

    Faisal, F. H. M.; Donner, C.

    2010-02-02

    An 'electron-bridge' mechanism of nuclear reaction in an atom or ion by ultra-intense laser fields is presented. A preliminary estimate of the intensity dependence of the rate of disintegration reaction of deuteron nucleus in deuterium atom is made for 800 nm laser fields. For intensities below 5x10{sup 21} W/cm{sup 2}, the rate of disintegration by the 'electron-bridge' mechanism is found to be small, but it rises sharply and becomes large already for {approx_equal}10{sup 22} W/cm{sup 2}.

  10. Cold-atom dynamics in crossed-laser-beam waveguides

    SciTech Connect

    Torrontegui, E.; Muga, J. G.; Echanobe, J.; Ruschhaupt, A.; Guery-Odelin, D.

    2010-10-15

    We study the dynamics of neutral cold atoms in an L-shaped crossed-beam optical waveguide formed by two perpendicular red-detuned lasers of different intensities and a blue-detuned laser at the corner. The motion in one sense is optimized, and the motion in the other sense may be suppressed even if it is energetically allowed. Quantum and classical simulations are performed and give similar results. Complemented with a vibrational cooling process we find a range of parameters for which this setting works as a one-way device or 'atom diode'.

  11. Interferometric Laser Cooling of Atomic Rubidium.

    PubMed

    Dunning, Alexander; Gregory, Rachel; Bateman, James; Himsworth, Matthew; Freegarde, Tim

    2015-08-14

    We report the 1D cooling of ^{85}Rb atoms using a velocity-dependent optical force based upon Ramsey matter-wave interferometry. Using stimulated Raman transitions between ground hyperfine states, 12 cycles of the interferometer sequence cool a freely moving atom cloud from 21 to 3 ?K. This pulsed analog of continuous-wave Doppler cooling is effective at temperatures down to the recoil limit; with augmentation pulses to increase the interferometer area, it should cool more quickly than conventional methods and be more suitable for species that lack a closed radiative transition. PMID:26317719

  12. Long Range Interactions With Laser Cooled Neutral Atoms

    SciTech Connect

    Gattobigio, Giovanni Luca; Michaud, Franck; Labeyrie, Guillaume; Kaiser, Robin; Loureiro, Jorge; Mendonca, Jose Tito; Tercas, Hugo; Pohl, Thomas

    2008-09-07

    Multiple scattering of light in a trap of laser cooled neutral atoms leads to repulsion forces between the atoms. The corresponding interactions have long range behavior in 1/r{sup 2} and are thus similar to Coulomb interaction in an one component confined plasma. Consequences of these interactions will be described in this paper, including the limitation of the spatial density one can obtain in such systems and self-sustained oscillations of the cloud.

  13. Simultaneous detection of methane, oxygen and water vapour utilising near-infrared diode lasers in conjunction with difference-frequency generation

    NASA Astrophysics Data System (ADS)

    Gustafsson, U.; Sandsten, J.; Svanberg, S.

    An all-diode-laser-based spectrometer is used for the simultaneous detection of methane, oxygen and water vapour. This is accomplished using a 760-nm diode laser and a 980-nm diode laser in conjunction with difference-frequency generation to 3.4 μm in a periodically poled lithium niobate crystal. Each of the output wavelengths is resonant with one of the molecular species. Simultaneous recordings over a 15-m open path of laboratory air are demonstrated. The recording scheme shows the wide applicability of a diode-laser-based difference-frequency spectrometer for the detection of molecular species in different wavelength ranges. By increasing the frequency of the 760-nm diode laser and decreasing the frequency of the 980-nm diode laser, a maximum continuous tuning range in the mid infrared of 3.6 cm-1 is achieved. This enables the recording of several methane lines at atmospheric pressure. Pressure-dependence studies of methane lineshapes are also performed in an absorption cell. An indoor-air methane background level of 3 ppm is measured. The signal-to-noise ratio in the recorded methane spectra indicates that sub-ppm detection of methane at atmospheric pressure is feasible.

  14. Sub-Doppler laser cooling of potassium atoms

    SciTech Connect

    Landini, M.; Roy, S.; Carcagni, L.; Trypogeorgos, D.; Fattori, M.; Inguscio, M.; Modugno, G.

    2011-10-15

    We investigate the sub-Doppler laser cooling of bosonic potassium isotopes, whose small hyperfine splitting has so far prevented cooling below the Doppler temperature. We find instead that the combination of a dark optical molasses scheme that naturally arises in this kind of system and an adiabatic ramping of the laser parameters allows us to reach sub-Doppler temperatures for small laser detunings. We demonstrate temperatures as low as 25{+-}3 {mu}K and 47{+-}5 {mu}K in high-density samples of the two isotopes {sup 39}K and {sup 41}K, respectively. Our findings should find application to other atomic systems.

  15. Equilibrium temperature of laser cooled atoms in squeezed vacuum

    NASA Technical Reports Server (NTRS)

    Shevy, Y.

    1992-01-01

    It is shown that by squeezing the vacuum fluctuations of the electromagnetic field the quantum fluctuations of the optical forces exerted on laser cooled two-level atoms, can be dramatically modified. Under certain conditions, this modification in concert with the enhanced average forces can lead to equilibrium temperatures below those attained under normal vacuum fluctuations.

  16. Rate-equation approach to atomic-laser light statistics

    SciTech Connect

    Chusseau, Laurent; Arnaud, Jacques; Philippe, Fabrice

    2002-11-01

    We consider three- and four-level atomic lasers that are either incoherently (unidirectionally) or coherently (bidirectionally) pumped, the single-mode cavity being resonant with the laser transition. The intracavity Fano factor and the photocurrent spectral density are evaluated on the basis of rate equations. According to that approach, fluctuations are caused by jumps in active and detecting atoms. The algebra is simple. Whenever a comparison is made, the expressions obtained coincide with the previous results. The conditions under which the output light exhibits sub-Poissonian statistics are considered in detail. Analytical results, based on linearization, are verified by comparison with Monte Carlo simulations. An essentially exhaustive investigation of sub-Poissonian light generation by three- and four-level lasers has been performed. Only special forms were reported earlier.

  17. 5p photoemission from laser-excited cesium atoms

    SciTech Connect

    Schulz, J.; Maeaettae, M.; Heinaesmaeki, S.; Huttula, M.; Aksela, S.; Aksela, H.; Sankari, R.; Kukk, E.; Rander, T.; Svensson, S.

    2006-06-15

    Fine-structure resolved 5p photoemission spectra of Cs in the ground state and after laser excitation into the [Xe]6p {sup 2}P{sub 1/2} and 6p{sup 2}P{sub 3/2} states have been studied. The 5p{sup 5}6p final states have been reached by the 5p{sup 6}6s{yields}5p{sup 5}6p conjugate shakeup process from ground-state atoms as well as by direct photoemission from laser-excited atoms. The laser-excited spectra can be well described with calculations based on the jK-coupling model. Calculations based on a multiconfiguration Dirac-Fock approach have been performed to investigate the deviations created by intermediate coupling from the pure jK-coupling scheme.

  18. Control for atom response in multicomponent laser fields

    NASA Astrophysics Data System (ADS)

    Andreev, A. V.; Stremoukhov, S. Yu.; Shutova, O. A.

    2012-03-01

    A theory of the nonlinear optical response of an atom interacting with a superposition of arbitrarily polarized fields is developed. The theory is based on the analytical solution of the boundary-value problem for an electron moving in a spherically symmetric intraatomic field and in the field of an external electromagnetic field. By means of the example of an argon atom interacting with a bichromatic field formed by the first and second harmonics of a Ti:sapphire laser, it is shown that, when an atom interacts with the field of two polarized pulses the polarization directions of which are not collinear, the response spectrum significantly depends on the laser radiation parametersthe duration and intensity of pulses, the time of delay between them, and the angle between the directions of polarization vectors. Generation of THz radiation is shown to be possible in the ionization-free regime due to intraatomic nonlinearity.

  19. Extreme ultraviolet laser excites atomic giant resonance.

    PubMed

    Richter, M; Amusia, M Ya; Bobashev, S V; Feigl, T; Jurani?, P N; Martins, M; Sorokin, A A; Tiedtke, K

    2009-04-24

    Exceptional behavior of light-matter interaction in the extreme ultraviolet is demonstrated. The photoionization of different rare gases was compared at the free-electron laser in Hamburg, FLASH, by applying ion spectroscopy at the wavelength of 13.7 nm and irradiance levels of thousands of terawatts per square centimeter. In the case of xenon, the degree of nonlinear photoionization was found to be significantly higher than for neon, argon, and krypton. This target specific behavior cannot be explained by the standard theories developed for optical strong-field phenomena. We suspect that the collective giant 4d resonance of xenon is the driving force behind the effect that arises in this spectral range. PMID:19518707

  20. Atomic electron correlations in intense laser fields

    SciTech Connect

    DiMauro, L.F.; Sheehy, B.; Walker, B.; Agostini, P.A.; Kulander, K.C.

    1998-11-01

    This talk examines two distinct cases in strong optical fields where electron correlation plays an important role in the dynamics. In the first example, strong coupling in a two-electron-like system is manifested as an intensity-dependent splitting in the ionized electron energy distribution. This two-electron phenomenon (dubbed continuum-continuum Autler-Townes effect) is analogous to a strongly coupled two-level, one-electron atom but raises some intriguing questions regarding the exact nature of electron-electron correlation. The second case examines the evidence for two-electron ionization in the strong-field tunneling limit. Although their ability to describe the one-electron dynamics has obtained a quantitative level of understanding, a description of the two (multiple) electron ionization remains unclear.

  1. Atomic electron correlations in intense laser fields

    SciTech Connect

    DiMauro, L.F.; Sheehy, B.; Walker, B. Agostini, P.A. Kulander, K.C.

    1999-06-01

    This talk examines two distinct cases in strong optical fields where electron correlation plays an important role in the dynamics. In the first example, strong coupling in a two-electron-like system is manifested as an intensity-dependent splitting in the ionized electron energy distribution. This two-electron phenomenon (dubbed continuum-continuum Autler-Townes effect) is analogous to a strongly coupled two-level, one-electron atom but raises some intriguing questions regarding the exact nature of electron-electron correlation. The second case examines the evidence for two-electron ionization in the strong-field tunneling limit. Although our ability to describe the one-electron dynamics has obtained a quantitative level of understanding, a description of the two (multiple) electron ionization remains unclear. {copyright} {ital 1999 American Institute of Physics.}

  2. Atomic electron correlations in intense laser fields

    SciTech Connect

    DiMauro, L. F.; Sheehy, B.; Walker, B.; Agostini, P. A.; Kulander, K. C.

    1999-06-11

    This talk examines two distinct cases in strong optical fields where electron correlation plays an important role in the dynamics. In the first example, strong coupling in a two-electron-like system is manifested as an intensity-dependent splitting in the ionized electron energy distribution. This two-electron phenomenon (dubbed continuum-continuum Autler-Townes effect) is analogous to a strongly coupled two-level, one-electron atom but raises some intriguing questions regarding the exact nature of electron-electron correlation. The second case examines the evidence for two-electron ionization in the strong-field tunneling limit. Although our ability to describe the one-electron dynamics has obtained a quantitative level of understanding, a description of the two (multiple) electron ionization remains unclear.

  3. Injection locking of a high power ultraviolet laser diode for laser cooling of ytterbium atoms

    NASA Astrophysics Data System (ADS)

    Hosoya, Toshiyuki; Miranda, Martin; Inoue, Ryotaro; Kozuma, Mikio

    2015-07-01

    We developed a high-power laser system at a wavelength of 399 nm for laser cooling of ytterbium atoms with ultraviolet laser diodes. The system is composed of an external cavity laser diode providing frequency stabilized output at a power of 40 mW and another laser diode for amplifying the laser power up to 220 mW by injection locking. The systematic method for optimization of our injection locking can also be applied to high power light sources at any other wavelengths. Our system does not depend on complex nonlinear frequency-doubling and can be made compact, which will be useful for providing light sources for laser cooling experiments including transportable optical lattice clocks.

  4. Cs 728 nm Laser Spectroscopy and Faraday Atomic Filter

    NASA Astrophysics Data System (ADS)

    Liu, Zhong-Zheng; Tao, Zhi-Ming; Jiang, Zhao-Jie; Chen, Jing-Biao

    2014-12-01

    We mainly present the 728 nm laser spectroscopy and Faraday atomic filter of Cs atoms with 650 MHz linewidth and 2.6% transmission based on an electrodeless discharge vapor lamp, compared with Rb 728 nm laser spectroscopy. Accidentally, this remarkably strong Cs 728 nm transition from the 6F7/2 state to the 5D5/2 state is only about 2.5 GHz away from the Rb 728 nm transition of the future potential four-level active optical clock, once laser cooled and trapped from the 7S1/2 state to the 5P1/2 state, as we proposed previously. A Faraday atomic filter stabilized 728 nm laser using a Cs electrodeless discharge vapor lamp with a power of 10mW will provide a frequency reference to evaluate the performance of the potential Rb four-level active optical clock at 728 nm with power less than 1 nW by 2.5 GHz heterodyne measurements.

  5. Laser information encoded in atomic asymmetrical ionization in few-cycle laser fields

    SciTech Connect

    Tabe, T.; Ono, N.; Toshima, N.; Tong, X. M.

    2011-08-15

    The pulse duration and carry-envelope phase (CEP) are two important parameters to characterize a few-cycle intense laser. We systematically study asymmetrical ionization of Ar in few-cycle laser fields with different pulse durations (3-7 fs) and laser intensities (10{sup 13}-10{sup 14} W/cm{sup 2}) by solving the time-dependent Schroedinger equation. Analyzing the CEP-dependent asymmetry of above-threshold ionization as a function of the photoelectron energy, we find that the qualitative global features of CEP-dependent asymmetry are insensitive to the pulse duration. But the fine structures of the asymmetry are sensitive to the laser pulse duration. Changing Ar to H atoms, we find that the information encoded in asymmetry is insensitive to target atoms at a moderate laser intensity.

  6. Development of a chemical oxygen - iodine laser with production of atomic iodine in a chemical reaction

    SciTech Connect

    Censky, M; Spalek, O; Jirasek, V; Kodymova, J; Jakubec, I

    2009-11-30

    The alternative method of atomic iodine generation for a chemical oxygen - iodine laser (COIL) in chemical reactions with gaseous reactants is investigated experimentally. The influence of the configuration of iodine atom injection into the laser cavity on the efficiency of the atomic iodine generation and small-signal gain is studied. (lasers)

  7. Velocity measurements by laser resonance fluorescence. [single atom diffusional motion

    NASA Technical Reports Server (NTRS)

    She, C. Y.; Fairbank, W. M., Jr.

    1980-01-01

    The photonburst correlation method was used to detect single atoms in a buffer gas. Real time flow velocity measurements with laser induced resonance fluorescence from single or multiple atoms was demonstrated and this method was investigated as a tool for wind tunnel flow measurement. Investigations show that single atoms and their real time diffusional motion on a buffer gas can be measured by resonance fluorescence. By averaging over many atoms, flow velocities up to 88 m/s were measured in a time of 0.5 sec. It is expected that higher flow speeds can be measured and that the measurement time can be reduced by a factor of 10 or more by careful experimental design. The method is clearly not ready for incorporation in high speed wind tunnels because it is not yet known whether the stray light level will be higher or lower, and it is not known what detection efficiency can be obtained in a wind tunnel situation.

  8. Pulsed laser gates for trapped atomic qubits

    NASA Astrophysics Data System (ADS)

    Senko, Crystal; Campbell, Wesley C.; Mizrahi, Jonathan; Monroe, Chris

    2011-05-01

    Current experimental techniques for entangling multiple trapped ion qubits via the quantized modes of motion are inherently limited in speed and thus sensitive to many sources of noise. We use high power mode-locked lasers to perform ultrafast qubit operations via stimulated Raman transitions. We show that complete control over the spin state of a single qubit can be accomplished in tens of picoseconds by splitting a single pulse and varying the delay. We also investigate improvements to the fidelity of current protocols using a weak pulse train at a large (33 THz) detuning. Future work will focus on generating entangling gates on timescales faster than a motional period, by tailoring the ions' motional evolution with pulse sequences of varying Rabi frequency or using spin-dependent momentum kicks fashioned from a few strong pulses,. This work is supported by grants from the U.S. Army Research Office with funding from the DARPA OLE program, IARPA, and the MURI program; the NSF PIF Program; the NSF Physics Frontier Center at JQI; and the European Commission AQUTE program.

  9. EFFECTS OF LASER RADIATION ON MATTER: Spectrum of the barium atom in a laser radiation field

    NASA Astrophysics Data System (ADS)

    Bondar', I. I.; Suran, V. V.

    1990-08-01

    An experimental investigation was made of the influence of a laser radiation field on the spectrum of barium atoms. The investigation was carried out by the method of three-photon ionization spectroscopy using dye laser radiation (? = 14 800-18 700 cm - 1). The electric field intensity of the laser radiation was 103-106 V/cm. This laser radiation field had a strong influence on a number of bound and autoionizing states. The nature of this influence depended on the ratio of the excitation frequencies of bound and autoionizing states.

  10. Atomic mass dependent electrostatic diagnostics of colliding laser plasma plumes

    NASA Astrophysics Data System (ADS)

    Yeates, P.; Fallon, C.; Kennedy, E. T.; Costello, J. T.

    2013-09-01

    The behaviours of colliding laser plasma plumes (Cp) compared with single plasma plumes (Sp) are investigated for 14 different atomic mass targets. A Faraday cup, situated at the end of a drift tube (L = 0.99 m), is employed to record the time-of-flight (TOF) current traces for all elements and both plume configurations, for a fixed laser intensity of Ip = 4.2 1010 W cm-2 (F = 0.25 kJ cm-2). The ratio of the peak current from the Cp relative to twice that from the Sp is designated as the peak current ratio while the ratio of the integrated charge yield from the Cp relative to twice that from the Sp is designated as the charge yield ratio. Variation of the position of the Faraday cup within the drift tube (L = 0.33, 0.55, and 0.99 m) in conjunction with a lower laser fluence (F = 0.14 kJ cm-2) facilitated direct comparison of the changing TOF traces from both plasma configurations for the five lightest elements studied (C, Al, Si, Ti, and Mn). The results are discussed in the frame of laser plasma hydrodynamic modelling to approximate the critical recombination distance LCR. The dynamics of colliding laser plasma plumes and the atomic mass dependence trends observed are presented and discussed.

  11. Decay of metastable H atoms in intense excimer lasers

    SciTech Connect

    Dimou, L.; Faisal, F.H.M. )

    1992-10-01

    Decay widths of metastable hydrogen atoms subjected to the intense field of the currently available KrF{sup *} laser ({lambda}=248 nm) and ArF{sup *} laser ({lambda}=193 nm) are calculated by solving the full (3+1)-dimensional Schroedinger equation in the space-translated frame of reference. The critical intensities, above which the suppression of ionization decay sets in, are found to be {ital I}{sub {ital c}}{congruent}2.5{times}10{sup 14} and 7{times}10{sup 14} W/cm{sup 2} for {lambda}=248 and 193 nm, respectively.

  12. Ionization of atomic hydrogen in strong infrared laser fields

    NASA Astrophysics Data System (ADS)

    Grum-Grzhimailo, Alexei N.; Abeln, Brant; Bartschat, Klaus; Weflen, Daniel; Urness, Timothy

    2010-04-01

    We have used the matrix iteration method of Nurhuda and Faisal [Phys. Rev. A 60, 3125 (1999)] to treat ionization of atomic hydrogen by a strong laser pulse. After testing our predictions against a variety of previous calculations, we present ejected-electron spectra as well as angular distributions for few-cycle infrared laser pulses with peak intensities of up to 1015 W/cm2. It is shown that the convergence of the results with the number of partial waves is a serious issue, which can be managed in a satisfactory way by using the velocity form of the electric dipole operator in connection with an efficient time-propagation scheme.

  13. Atomic vapor laser isotope separation using resonance ionization

    SciTech Connect

    Comaskey, B.; Crane, J.; Erbert, G.; Haynam, C.; Johnson, M.; Morris, J.; Paisner, J.; Solarz, R.; Worden, E.

    1986-09-01

    Atomic vapor laser isotope separation (AVLIS) is a general and powerful technique. A major present application to the enrichment of uranium for light-water power-reactor fuel has been under development for over 10 years. In June 1985, the Department of Energy announced the selection of AVLIS as the technology to meet the nation's future need for enriched uranium. Resonance photoionization is the heart of the AVLIS process. We discuss those fundamental atomic parameters that are necessary for describing isotope-selective resonant multistep photoionization along with the measurement techniques that we use. We illustrate the methodology adopted with examples of other elements that are under study in our program.

  14. Effects of injected atomic coherence in broad-area lasers

    SciTech Connect

    Calderon, Oscar G.; Cabrera, Eduardo; Carreno, F.; Anton, M.A.; Melle, Sonia; Guerra, J.M.

    2005-09-15

    We analyze the effect of injected atomic coherence on transverse patterns of a broad area laser by means of the semiclassical two-level Maxwell-Bloch equations. A single longitudinal mode is considered. The injected atomic coherence forces a spatially homogeneous profile to appear and locks the field phase to a single value. Above a pump threshold value a very rich scenario of patterns is developed. Near threshold we find stationary patterns such as rhombic and hexagonal lattices. Well above threshold nonstationary patterns such as complex highly ordered vortex lattices traveling along the cross section, and nearly traveling waves appear.

  15. Design of laser system for absolute gravimeter based on 87Rb atom interferometer

    NASA Astrophysics Data System (ADS)

    Zhao, Yang; Wang, Shaokai; Zhuang, Wei; Fang, Fang; Li, Tianchu

    2015-08-01

    We present a laser system design for an absolute gravimeter based on 87Rb atom interferometer. By skillful design, lasers with 9 different frequencies are based on two diode lasers including tapered amplifier. Two electrical feedback systems are used for laser frequency stabilization and the Raman lasers generation respectively. All other lasers are based on two Raman lasers and realized with frequency shift by acoustic optical modulators. This laser system not only has the compact and simple construction, but meets all requirements for laser power and frequency controlling for the atom interferometer. It has the characteristic of reliability and integrity.

  16. Direct observation of electron emission from the grain boundaries of chemical vapour deposition diamond films by tunneling atomic force microscopy

    SciTech Connect

    Chatterjee, Vijay; Harniman, Robert; May, Paul W.; Barhai, P. K.

    2014-04-28

    The emission of electrons from diamond in vacuum occurs readily as a result of the negative electron affinity of the hydrogenated surface due to features with nanoscale dimensions, which can concentrate electric fields high enough to induce electron emission from them. Electrons can be emitted as a result of an applied electric field (field emission) with possible uses in displays or cold-cathode devices. Alternatively, electrons can be emitted simply by heating the diamond in vacuum to temperatures as low as 350?C (thermionic emission), and this may find applications in solar energy generation or energy harvesting devices. Electron emission studies usually use doped polycrystalline diamond films deposited onto Si or metallic substrates by chemical vapor deposition, and these films have a rough, faceted morphology on the micron or nanometer scale. Electron emission is often improved by patterning the diamond surface into sharp points or needles, the idea being that the field lines concentrate at the points lowering the barrier for electron emission. However, there is little direct evidence that electrons are emitted from these sharp tips. The few reports in the literature that have studied the emission sites suggested that emission came from the grain boundaries and not the protruding regions. We now present direct observation of the emission sites over a large area of polycrystalline diamond using tunneling atomic force microscopy. We confirm that the emission current comes mostly from the grain boundaries, which is consistent with a model for emission in which the non-diamond phase is the source of electrons with a threshold that is determined by the surrounding hydrogenated diamond surface.

  17. Laser-induced electron diffraction for probing rare gas atoms.

    PubMed

    Xu, Junliang; Blaga, Cosmin I; DiChiara, Anthony D; Sistrunk, Emily; Zhang, Kaikai; Chen, Zhangjin; Le, Anh-Thu; Morishita, Toru; Lin, C D; Agostini, Pierre; DiMauro, Louis F

    2012-12-01

    Recently, using midinfrared laser-induced electron diffraction (LIED), snapshots of a vibrating diatomic molecule on a femtosecond time scale have been captured [C.I. Blaga et al., Nature (London) 483, 194 (2012)]. In this Letter, a comprehensive treatment for the atomic LIED response is reported, a critical step in generalizing this imaging method. Electron-ion differential cross sections (DCSs) of rare gas atoms are extracted from measured angular-resolved, high-energy electron momentum distributions generated by intense midinfrared lasers. Following strong-field ionization, the high-energy electrons result from elastic rescattering of a field-driven wave packet with the parent ion. For recollision energies ?100 eV, the measured DCSs are indistinguishable for the neutral atoms and ions, illustrating the close collision nature of this interaction. The extracted DCSs are found to be independent of laser parameters, in agreement with theory. This study establishes the key ingredients for applying LIED to femtosecond molecular imaging. PMID:23368191

  18. Energy level offset analysis of lead atom in laser plasma

    NASA Astrophysics Data System (ADS)

    Zhou, X. M.; Chen, C. S.; Man, B. Y.; Guo, J.; Wang, J.

    2009-08-01

    The optical emission spectra of the plasma generated by a 1064 nm laser irradiation of lead target in air were recorded and analyzed. Temporal evolvement trait of spectral lines was investigated. The Stark width and line shift were measured at different delay time and laser energies. The electron densities were determined using Stark-broadening parameters of spectral lines. The atomic energy level offset in plasma surroundings was explored by analyzing the line shift. The experimental data of Stark widths and line shifts were analyzed using the regularity of the Stark parameters dependence on effective ionization potential. However an inverse experimental result was found compared with the theoretical calculation. In addition, the change of the Stark widths and line shifts with the delay time and laser energies was discussed.

  19. High resolution molecular spectroscopy using laser cooled sodium atoms

    SciTech Connect

    Ratliff, L.; Helmerson, K.; Lett, P.; Rolston, S.

    1993-05-01

    We present a new spectroscopic technique which allows the observation of long-range molecular states of ultracold sodium via the associative ionization (AI) reaction. Due to the ultracold conditions, we are able to achieve very high resolution spectra of free-bound molecular transitions which were previously observable only via bound-bound spectroscopy. Previous experiments using laser cooled sodium have revealed evidence of molecular spectra but were limited to a narrow tuning range and power broadened because the intense trapping laser was also used to excite the molecular transitions. By alternating the beams of a magneto-optical trap with a separate laser, we confine the atoms while leaving them unperturbed by the trapping light during the excitation period. The second laser excites free ground state atoms into the bound molecular states. With this scheme, we have been able to detect the vibrational series of molecular states in the intermediate AI excitation step, from just below threshold to 3 cm{sup {minus}1} deep. By resolving narrow structure within the spectra associated with molecular hyperfine splittings and comparing with theoretical calculations, we can unambiguously identify the molecular states involved.

  20. Numerical method for calculating atomic spectra in strong laser Helds

    NASA Astrophysics Data System (ADS)

    Koryukina, E. V.

    2016-02-01

    In this paper, a new theoretical method is suggested for calculating atomic emission spectra in strong laser fields. This numerical method based on diagonalization of the energy matrix of an atom in the electric field is free from limitations of perturbation theory and valid for a wide range of changes in the electric field strength and frequency. Within the framework of the suggested method, the ground-state shifts of He, Ne, Ar, and Kr atoms in a circularly polarized electric field are computed. Calculations are carried out for electric fields with strengths of 0.06 and 0.15 a.u. and frequencies from 10-4 to 0.057 a.u. In addition, the effect of ordering of the transition probabilities with respect to the magnetic quantum number M in the electric field is also investigated. The results obtained can be useful for correct interpretation of the experimental data and prediction of the behaviour of atomic emission spectra in strong laser fields.

  1. Homonuclear ionizing collisions of laser-cooled metastable helium atoms

    SciTech Connect

    Stas, R. J. W.; McNamara, J. M.; Hogervorst, W.; Vassen, W.

    2006-03-15

    We present a theoretical and experimental investigation of homonuclear ionizing collisions of laser-cooled metastable (2 {sup 3}S{sub 1}) helium atoms, considering both the fermionic {sup 3}He and bosonic {sup 4}He isotopes. The theoretical description combines quantum threshold behavior, Wigner's spin-conservation rule, and quantum-statistical symmetry requirements in a single-channel model, complementing a more complete close-coupling theory that has been reported for collisions of metastable {sup 4}He atoms. The model is supported with measurements (in the absence of light fields) of ionization rates in magneto-optically trapped samples that contain about 3x10{sup 8} atoms of a single isotope. The ionization rates are determined from measurements of trap loss due to light-assisted collisions combined with comparative measurements of the ion production rate in the absence and presence of trapping light. Theory and experiment show good agreement.

  2. Laser-cooled atomic ions as probes of molecular ions

    SciTech Connect

    Brown, Kenneth R.; Viteri, C. Ricardo; Clark, Craig R.; Goeders, James E.; Khanyile, Ncamiso B.; Vittorini, Grahame D.

    2015-01-22

    Trapped laser-cooled atomic ions are a new tool for understanding cold molecular ions. The atomic ions not only sympathetically cool the molecular ions to millikelvin temperatures, but the bright atomic ion fluorescence can also serve as a detector of both molecular reactions and molecular spectra. We are working towards the detection of single molecular ion spectra by sympathetic heating spectroscopy. Sympathetic heating spectroscopy uses the coupled motion of two trapped ions to measure the spectra of one ion by observing changes in the fluorescence of the other ion. Sympathetic heating spectroscopy is a generalization of quantum logic spectroscopy, but does not require ions in the motional ground state or coherent control of the ion internal states. We have recently demonstrated this technique using two isotopes of Ca{sup +} [Phys. Rev. A, 81, 043428 (2010)]. Limits of the method and potential applications for molecular spectroscopy are discussed.

  3. A heated vapor cell unit for dichroic atomic vapor laser lock in atomic rubidium.

    PubMed

    McCarron, Daniel J; Hughes, Ifan G; Tierney, Patrick; Cornish, Simon L

    2007-09-01

    The design and performance of a compact heated vapor cell unit for realizing a dichroic atomic vapor laser lock (DAVLL) for the D(2) transitions in atomic rubidium is described. A 5 cm long vapor cell is placed in a double-solenoid arrangement to produce the required magnetic field; the heat from the solenoid is used to increase the vapor pressure and correspondingly the DAVLL signal. We have characterized experimentally the dependence of important features of the DAVLL signal on magnetic field and cell temperature. For the weaker transitions both the amplitude and gradient of the signal are increased by an order of magnitude. PMID:17902946

  4. A heated vapor cell unit for dichroic atomic vapor laser lock in atomic rubidium

    SciTech Connect

    McCarron, Daniel J.; Hughes, Ifan G.; Tierney, Patrick; Cornish, Simon L.

    2007-09-15

    The design and performance of a compact heated vapor cell unit for realizing a dichroic atomic vapor laser lock (DAVLL) for the D{sub 2} transitions in atomic rubidium is described. A 5 cm long vapor cell is placed in a double-solenoid arrangement to produce the required magnetic field; the heat from the solenoid is used to increase the vapor pressure and correspondingly the DAVLL signal. We have characterized experimentally the dependence of important features of the DAVLL signal on magnetic field and cell temperature. For the weaker transitions both the amplitude and gradient of the signal are increased by an order of magnitude.

  5. Nuclear-driven flashlamp pumping of the atomic iodine laser

    NASA Astrophysics Data System (ADS)

    Miley, G. H.

    1992-03-01

    This report is a study of the atomic iodine laser pumped with nuclear-excited XeBr fluorescence. Preliminary experiments, conducted in the TRIGA reactor, investigated the fluorescence of the excimer XeBr under nuclear pumping with B-10 and He-3, for use as a flashlamp gas to stimulate the laser. These measurements included a determination of the fluorescence efficiency (light emitted in the wavelength region of interest, divided by energy deposited in the gas) of XeBr under nuclear pumping, with varying excimer mixtures. Maximum fluorescence efficiencies were approximately 1 percent. In order to better understand XeBr under nuclear excitation, a kinetics model of the system was prepared. The model generated the time-dependant concentrations of 20 reaction species for three pulse sizes: a TRIGA pulse; a fast burst reactor pulse; and an e-beam pulse. The modeling results predicted fluorescence efficiencies significantly higher (peak efficiencies of approximately 10 percent) than recorded in the fluorescence experiments. The cause of this discrepancy was not fully determined. A ray tracing computer model was also prepared to evaluate the efficiency with which nuclear-induced fluorescence generated in one cavity of a laser could be coupled into another cavity containing an iodine lasant. Finally, an experimental laser cell was constructed to verify that nuclear-induced XeBr fluorescence could be used to stimulate a laser. Lasing was achieved at 1.31 micron in the TRIGA using C3F7I, a common iodine lasant. Peak laser powers were approximately 20 mW. Measured flashlamp pump powers at threshold agreed well with literature values, as did lasant pressure dependency on laser operation.

  6. Nuclear-driven flashlamp pumping of the atomic iodine laser

    SciTech Connect

    Miley, G.H.

    1992-03-01

    This report is a study of the atomic iodine laser pumped with nuclear- excited XeBr fluorescence. Preliminary experiments, conducted in the TRIGA reactor investigated the fluorescence of the excimer XeBr under nuclear pumping with {sup 10}B and {sup 3}He, for use as a flashlamp gas to stimulate the laser. These measurements included a determination of the fluorescence efficiency (light emitted in the wavelength region of interest, divided by energy deposited in the gas) of XeBr under nuclear pumping, with varying excimer mixtures. Maximum fluorescence efficiencies were approximately 1%. In order to better understand XeBr under nuclear excitation, a kinetics model of the system was prepared. The model generated the time-dependant concentrations of 20 reaction species for three pulse sizes, a TRIGA pulse, a fast burst reactor pulse, and an e-beam pulse. The modeling results predicted fluorescence efficiencies significantly higher (peak efficiencies of approximately 10%) than recorded in the fluorescence experiments. The cause of this discrepancy was not fully determined. A ray tracing computer model was also prepared to evaluate the efficiency with which nuclear-induced fluorescence generated in one cavity of a laser could be coupled into another cavity containing an iodine lasant. Finally, an experimental laser cell was constructed to verify that nuclear-induced XeBr fluorescence could be used to stimulate a laser. Lasing was achieved at 1.31 micron in the TRIGA using C{sub 3}F{sub 7}I, a common iodine lasant. Peak laser powers were approximately 20 mW. Measured flashlamp pump powers at threshold agreed well with literature values, as did lasant pressure dependency on laser operation.

  7. Atomic mass dependent electrostatic diagnostics of colliding laser plasma plumes

    SciTech Connect

    Yeates, P.; Fallon, C.; Kennedy, E. T.; Costello, J. T.; School of Physical Sciences, Dublin City University , Dublin 7

    2013-09-15

    The behaviours of colliding laser plasma plumes (C{sub p}) compared with single plasma plumes (S{sub p}) are investigated for 14 different atomic mass targets. A Faraday cup, situated at the end of a drift tube (L = 0.99 m), is employed to record the time-of-flight (TOF) current traces for all elements and both plume configurations, for a fixed laser intensity of I{sub p} = 4.2 10{sup 10} W cm{sup ?2} (F = 0.25 kJ cm{sup ?2}). The ratio of the peak current from the C{sub p} relative to twice that from the S{sub p} is designated as the peak current ratio while the ratio of the integrated charge yield from the C{sub p} relative to twice that from the S{sub p} is designated as the charge yield ratio. Variation of the position of the Faraday cup within the drift tube (L = 0.33, 0.55, and 0.99 m) in conjunction with a lower laser fluence (F = 0.14 kJ cm{sup ?2}) facilitated direct comparison of the changing TOF traces from both plasma configurations for the five lightest elements studied (C, Al, Si, Ti, and Mn). The results are discussed in the frame of laser plasma hydrodynamic modelling to approximate the critical recombination distance L{sub CR}. The dynamics of colliding laser plasma plumes and the atomic mass dependence trends observed are presented and discussed.

  8. Secondary laser cooling and capturing of thulium atoms in traps

    SciTech Connect

    Sukachev, D D; Kalganova, E S; Sokolov, A V; Fedorov, S A; Vishnyakova, G A; Akimov, A V; Kolachevsky, N N; Sorokin, V N

    2014-06-30

    Secondary laser cooling has been realised on the weak dipole transition 4f{sup 13}({sup 2}F{sup o})6s{sup 2}, J = 7/2, F=4 ? 4f{sup 12}({sup 3}H{sub 6}) 5d{sub 5/2}6s{sup 2}, J' = 9/2, F' = 5 with the wavelength of 530.7 nm and natural width of 350 kHz. The temperature of the atomic cloud in a magnetooptical trap (MOT) was 30 ?K at the lifetime of 2 s and the number of atoms 10{sup 5}. Approximately 1% of atoms from the MOT have been reloaded to an optical dipole trap and to one-dimensional optical lattice at the wavelength of 532 nm. The atom lifetime in the optical lattice was 320 ms. We propose to employ thulium atoms captured in an optical lattice as an optical frequency reference. (extreme light fields and their applications)

  9. Modeling a semiconductor laser with an intracavity atomic absorber

    SciTech Connect

    Masoller, C.; Vilaseca, R.; Oria, M.

    2009-07-15

    The dynamics of a semiconductor laser with an intracavity atomic absorber is studied numerically. The study is motivated by the experiments of Barbosa et al. [Opt. Lett. 32, 1869 (2007)], using a semiconductor junction as an active medium, with its output face being antireflection coated, and a cell containing cesium vapor placed in a cavity that was closed by a diffraction grating (DG). The DG allowed scanning the lasing frequency across the D{sub 2} line in the Cs spectrum, and different regimes such as frequency bistability or dynamic instability were observed depending on the operating conditions. Here we propose a rate-equation model that takes into account the dispersive losses and the dispersive refractive index change in the laser cavity caused by the presence of the Cs vapor cell. These effects are described through a modification of the complex susceptibility. The numerical results are found to be in qualitative good agreement with some of the observations; however, some discrepancies are also noticed, which can be attributed to multi-longitudinal-mode emission in the experiments. The simulations clearly show the relevant role of the Lamb dips and crossover resonances, which arise on top of the Doppler-broadened D{sub 2} line in the Cs spectrum, and are due to the forward and backward intracavity fields interacting resonantly with the Cs atoms. When the laser frequency is locked in a dip, a reduction in the frequency noise and of the intensity noise is demonstrated.

  10. Laser cooling and trapping of atomic particles. (Latest citations from the NTIS bibliographic database). Published Search

    SciTech Connect

    1994-02-01

    The bibliography contains citations concerning theory and experiments on laser cooling and laser trapping of neutral atoms and atomic ions. Atoms and ions are cooled by laser radiation pressure to very low Kelvin temperatures and confined in electromagnetic traps of very high density. Atomic particles cover sodium atoms, mercury ions, beryllium ions, magnesium ions, and hydrogen. Citations discuss applications in high performance spectroscopy, atomic clocks, microwave and optical frequency standards, relativistic neutral particle beam weapons, exotic fuels, cooling of electron beams, and space propulsion. (Contains a minimum of 185 citations and includes a subject term index and title list.)

  11. Laser cooling and trapping of atomic particles. (Latest citations from the NTIS data base). Published Search

    SciTech Connect

    Not Available

    1992-04-01

    The bibliography contains citations concerning theory and experiments on laser cooling and laser trapping of neutral atoms and atomic ions. Atoms and ions are cooled by laser radiation pressure to very low Kelvin temperatures and confined in electromagnetic traps of very high density. Atomic particles discussed include sodium atoms, mercury ions, beryllium ions, magnesium ions, and hydrogen. Applications for high performance spectroscopy, atomic clocks, microwave and optical frequency standards, relativistic neutral particle beam weapons, exotic fuels, cooling of electron beams, and space propulsion are examined. (Contains a minimum of 151 citations and includes a subject term index and title list.)

  12. Laser cooling and trapping of atomic particles. (Latest citations from the NTIS bibliographic database). Published Search

    SciTech Connect

    Not Available

    1994-12-01

    The bibliography contains citations concerning theory and experiments on laser cooling and laser trapping of neutral atoms and atomic ions. Atoms and ions are cooled by laser radiation pressure to very low Kelvin temperatures and confined in electromagnetic traps of very high density. Atomic particles cover sodium atoms, mercury ions, beryllium ions, magnesium ions, and hydrogen. Citations discuss applications in high performance spectroscopy, atomic clocks, microwave and optical frequency standards, relativistic neutral particle beam weapons, exotic fuels, cooling of electron beams, and space propulsion. (Contains a minimum of 204 citations and includes a subject term index and title list.)

  13. Ionization of atomic hydrogen in strong infrared laser fields

    SciTech Connect

    Grum-Grzhimailo, Alexei N.; Abeln, Brant; Bartschat, Klaus; Weflen, Daniel; Urness, Timothy

    2010-04-15

    We have used the matrix iteration method of Nurhuda and Faisal [Phys. Rev. A 60, 3125 (1999)] to treat ionization of atomic hydrogen by a strong laser pulse. After testing our predictions against a variety of previous calculations, we present ejected-electron spectra as well as angular distributions for few-cycle infrared laser pulses with peak intensities of up to 10{sup 15} W/cm{sup 2}. It is shown that the convergence of the results with the number of partial waves is a serious issue, which can be managed in a satisfactory way by using the velocity form of the electric dipole operator in connection with an efficient time-propagation scheme.

  14. Small-sized dichroic atomic vapor laser lock.

    PubMed

    Lee, Changmin; Iwata, G Z; Corsini, E; Higbie, J M; Knappe, S; Ledbetter, M P; Budker, D

    2011-04-01

    Two, lightweight diode laser frequency stabilization systems designed for experiments in the field are described. A significant reduction in size and weight in both models supports the further miniaturization of measurement devices in the field. Similar to a previous design, magnetic field lines are contained within a magnetic shield enclosing permanent magnets and a Rb cell, so that these dichroic atomic vapor laser lock (DAVLL) systems may be used for magnetically sensitive instruments. The mini-DAVLL system (49 mm long) uses a vapor cell (20 mm long) and does not require cell heaters. An even smaller micro-DAVLL system (9 mm long) uses a microfabricated cell (3 mm square) and requires heaters. These new systems show no degradation in performance with regard to previous designs while considerably reducing dimensions. PMID:21528995

  15. Production of pulsed atomic oxygen beams via laser vaporization methods

    NASA Technical Reports Server (NTRS)

    Brinza, David E.; Coulter, Daniel R.; Liang, Ranty H.; Gupta, Amitava

    1986-01-01

    The generation of energetic pulsed atomic oxygen beams by laser-driven evaporation of cryogenically frozen ozone/oxygen films and thin indium-tin oxide (ITO) films is reported. Mass spectroscopy is used in the mass and energy characterization of beams from the ozone/oxygen films, and a peak flux of 3 x 10 to the 20th/sq m per sec at 10 eV is found. Analysis of the time-of-flight data suggests that several processes contribute to the formation of the oxygen beam. Results show the absence of metastable states such as the 2p(3)3s(1)(5S) level of atomic oxygen blown-off from the ITO films. The present process has application to the study of the oxygen degradation problem of LEO materials.

  16. Designing Frustrated Quantum Magnets with Laser-Dressed Rydberg Atoms

    NASA Astrophysics Data System (ADS)

    Glaetzle, Alexander W.; Dalmonte, Marcello; Nath, Rejish; Gross, Christian; Bloch, Immanuel; Zoller, Peter

    2015-05-01

    We show how a broad class of lattice spin-1 /2 models with angular- and distance-dependent couplings can be realized with cold alkali atoms stored in optical or magnetic trap arrays. The effective spin-1 /2 is represented by a pair of atomic ground states, and spin-spin interactions are obtained by admixing van der Waals interactions between fine-structure split Rydberg states with laser light. The strengths of the diagonal spin interactions as well as the "flip-flop," and "flip-flip" and "flop-flop" interactions can be tuned by exploiting quantum interference, thus realizing different spin symmetries. The resulting energy scales of interactions compare well with typical temperatures and decoherence time scales, making the exploration of exotic forms of quantum magnetism, including emergent gauge theories and compass models, accessible within state-of-the-art experiments.

  17. Designing frustrated quantum magnets with laser-dressed Rydberg atoms.

    PubMed

    Glaetzle, Alexander W; Dalmonte, Marcello; Nath, Rejish; Gross, Christian; Bloch, Immanuel; Zoller, Peter

    2015-05-01

    We show how a broad class of lattice spin-1/2 models with angular- and distance-dependent couplings can be realized with cold alkali atoms stored in optical or magnetic trap arrays. The effective spin-1/2 is represented by a pair of atomic ground states, and spin-spin interactions are obtained by admixing van der Waals interactions between fine-structure split Rydberg states with laser light. The strengths of the diagonal spin interactions as well as the "flip-flop," and "flip-flip" and "flop-flop" interactions can be tuned by exploiting quantum interference, thus realizing different spin symmetries. The resulting energy scales of interactions compare well with typical temperatures and decoherence time scales, making the exploration of exotic forms of quantum magnetism, including emergent gauge theories and compass models, accessible within state-of-the-art experiments. PMID:25978228

  18. Electron scattering by laser-excited barium atoms

    NASA Technical Reports Server (NTRS)

    Register, D. F.; Trajmar, S.; Jensen, S. W.; Poe, R. T.

    1978-01-01

    Inelastic and superelastic scattering of 30- and 100-eV electrons by laser-excited 6s 6p 1P and subsequent cascade-populated 6s 6p 3P, 6s 5d 1D, and 6s 5d 3D Ba atoms have been observed. Absolute differential cross sections for the singlet and relative scattering intensities for the triplet species have been determined in the 5 to 20 deg angular region. Under the present conditions excitations dominate over deexcitations.

  19. Observing the profile of an atom laser beam

    SciTech Connect

    Koehl, M.; Esslinger, T.; Busch, Th.; Moelmer, K.; Haensch, T. W.

    2005-12-15

    We report on an investigation of the beam profile of an atom laser extracted from a magnetically trapped {sup 87}Rb Bose-Einstein condensate. The transverse momentum distribution is magnified by a curved mirror for matter waves and a momentum resolution of 1/60 of a photon recoil is obtained. We find the transverse momentum distribution to be determined by the mean-field potential of the residing condensate, which leads to a nonsmooth transverse density distribution. Our experimental data are compared with a full three-dimensional simulation of the output coupling process and we find good agreement.

  20. Production of pulsed atomic oxygen beams via laser vaporization methods

    NASA Technical Reports Server (NTRS)

    Brinza, David E.; Coulter, Daniel R.; Liang, Ranty H.; Gupta, Amitava

    1987-01-01

    Energetic pulsed atomic oxygen beams were generated by laser-driven evaporation of cryogenically frozen ozone/oxygen films and thin films of indium-tin oxide (ITO). Mass and energy characterization of beams from the ozone/oxygen films were carried out by mass spectrometry. The peak flux, found to occur at 10 eV, is estimated from this data to be 3 x 10(20) m(-2) s(-1). Analysis of the time-of-flight data indicates a number of processes contribute to the formation of the atomic oxygen beam. The absence of metastable states such as the 2p(3) 3s(1) (5S) level of atomic oxygen blown off from ITO films is supported by the failure to observe emission at 777.3 nm from the 2p(3) 3p(1) (5P sub J) levels. Reactive scattering experiments with polymer film targets for atomic oxygen bombardment are planned using a universal crossed molecular beam apparatus.

  1. Influence of laser irradiation condition on a femtosecond laser-assisted tomographic atom probe.

    PubMed

    Nishimura, A; Nogiwa, K; Otobe, T; Ohkubo, T; Hono, K; Kondo, K; Yokoyama, A

    2009-04-01

    Influence of femtosecond laser pulse condition on the performance of an energy-compensated optical tomographic atom probe has been investigated. The unstable oscillator makes the mass peaks significantly broadened. Double 80fs pulse train with 10ns interval makes the mass peaks slightly shifted to the higher mass side. The mass peak shift corresponds to the fight time of ions triggered by laser pulsing. Chirping ratio for the laser pulses ranging from 80fs to 10ps is controlled by the pulse compressor for the fragile specimens such as oxide dispersion strengthen steel or insulator materials. A first-principle calculation for optical dielectric breakdown in diamond has been successfully demonstrated. It is shown that effective conductive increase has appeared at the laser intensity around 10(13)W/cm(2). PMID:19232830

  2. Selective Two-Step (STS) Photoionization of Atoms and Photodissociation of Molecules by Laser Radiation.

    PubMed

    Ambartzumian, R V; Letokhov, V S

    1972-02-01

    The general considerations for two-step photoionization of atoms and photodissociation of molecules using tunable laser sources are discussed. Experimental results are given for the (1) photoionization of rubidium vapor using a ruby-laser-pumped dye laser and a doubled ruby laser radiation, and (2) photodissociation of HCl using the Raman-shifted output and the fourth harmonic output of a tunable Nd-glass laser. The possibilities for other laser systems are also discussed. PMID:20111507

  3. Low-threshold short-cavity diode laser for a miniature atomic clock

    SciTech Connect

    Kargapol'tsev, Sergei V; Velichansky, Vladimir L; Vasil'ev, V V; Kobyakova, M Sh; Morozyuk, A V; Shiryaeva, N V; Konyaev, V P

    2009-06-30

    Short-cavity diode lasers (SCDLs) emitting at the 894-nm D{sub 1} line of caesium are developed. Low threshold currents and power consumption will make it possible to use these lasers in chip-size atomic clocks (CSACs) and magnetometers. The SCDL parameters are comparable with the parameters of surface-emitting lasers. (lasers)

  4. Sympathetic cooling of molecules with laser-cooled atoms

    NASA Astrophysics Data System (ADS)

    Hudson, Eric

    2014-05-01

    Cooling molecules through collisions with laser-cooled atoms is an attractive route to ultracold, ground state molecules. The technique is simple, applicable to a wide class of molecules, and does not require molecule specific laser systems. Particularly suited to this technique are charged molecules, which can be trapped indefinitely, even at room temperature, and undergo strong, short-ranged collisions with ultracold atoms. In this talk, I will focus on recent efforts to use the combination of a magneto-optical trap (MOT) and an ion trap, dubbed the MOTion trap, to produce cold, ground state diatomic charged molecules. The low-energy internal structure of these diatomic molecules, e.g. the electric dipole moment and vibrational, rotational, and ?-doublet levels, presents a host of opportunities for advances in quantum simulation, precision measurement, cold chemistry, and quantum information. Excitingly, recent proof-of-principle experiments have demonstrated that the MOTion trap is extremely efficient at cooling the vibrational motion of molecular ions. Supported by the ARO and NSF.

  5. Effects of strong laser fields on hadronic helium atoms

    NASA Astrophysics Data System (ADS)

    Lee, Han-Chieh; Jiang, Tsin-Fu

    2015-12-01

    The metastable hadronic helium atoms in microseconds lifetime are available in laboratory, and two-photon spectroscopy was reported recently. This exotic helium atom has an electron in the ground state and a negative hadron rotating around the helium nucleus. We theoretically study the excitation on hadronic helium by femtosecond pulse and elucidate the influence of moleculelike structure and rotation behavior on the photoelectron spectra and high-order harmonic generation. Because of the moleculelike structure, the electronic ground state consists of several angular orbitals. These angular orbitals can enhance photoelectron spectra at high energies, and also influence the harmonic generation spectra considerably. In particular, the harmonic spectra can occur at even harmonic orders because of the transition between these angular orbitals and continuum states. On the other side, the rotation behavior of hadron can induce a frequency shift in the harmonic spectra. The magnitude of the frequency shift depends on the orbiting speed of the hadron, which is considerable because the rotation period is in a few femtoseconds, a time scale that is comparable to that of infrared laser and is feasible in current laser experiments.

  6. Theory and computation of atoms in intense laser fields

    NASA Astrophysics Data System (ADS)

    Smyth, Edward Stuart

    This thesis has involved performing various modifications to the HELIUM program and using the HELIUM program to study the dynamics of laser-atom interactions. The HELIUM program is a portable code for the numerical solution of the full 5-dimensional time-dependent Schrdinger Equation for 2 electron atoms in a very intense, linearly polarized, laser pulse. A finite-difference grid is used to model the two radial co-ordinates and a basis set of coupled spherical harmonics handles the three angular variables of the system. The HELIUM program was modified to incorporate a new propagator based on Krylov-subspace techniques, thus allowing a substantial increase in performance. A modular structure was implemented within the HELIUM program, separating the source code into 5 layers. This allows the program to be optimized for particular computer architectures while remaining portable across a wide variety of massively-parallel and vector supercomputers. It also greatly aids the task of program testing and verification. The breadth of output from the code was greatly extended. Numerous runs were performed for a wide variety of laser pulse parameters, enabling various observables such as ionization rates and harmonic generation to be studied. Comparisons with the results of other models have been performed and a new single active electron model has been developed. The full five-dimensional wavefunction can now be output to disk using an efficient parallel I/O strategy for subsequent analysis using the latest graphical visualization techniques. The study of magnesium, a quasi two electron system, was started using a time-independent screening potential to model the effect of the inner closed electron shells.

  7. Ionization of atomic hydrogen in strong infrared laser fields

    NASA Astrophysics Data System (ADS)

    Abeln, Brant; Weflen, Daniel; Bartschat, Klaus; Urness, Timothy; Grum-Grzhimailo, Alexei N.

    2010-03-01

    We used the matrix iteration method of Nurhuda and FaisalootnotetextM. Nurhuda and F.H.M. Faisal, Phys. Rev. A 60 (1999) 3125. to treat ionization of atomic hydrogen by a strong laser pulse. After testing our predictions against a variety of previous calculations, we obtained ejected-electron spectra as well as angular distributions for few-cycle infrared laser pulses with peak intensities of up to 10^15,W/cm^2 by using the velocity form of the electric dipole operator in connection with an efficient time-propagation scheme. We demonstrate that our results are converged with the number of partial waves used in the expansion of the total wavefunction and that they are essentially free of numerical artifacts. The results are analyzed with particular emphasis on the effect of the carrier envelope for short pulses, and we produced movies to visualize the time-dependent electron density. Choosing parameters of currently available lasers, our predictions are expected to guide and be tested by ongoing experimental investigations.

  8. Laser spectroscopy of atoms in superfluid helium for the measurement of nuclear spins and electromagnetic moments of radioactive atoms

    NASA Astrophysics Data System (ADS)

    Fujita, T.; Furukawa, T.; Imamura, K.; Yang, X. F.; Hatakeyama, A.; Kobayashi, T.; Ueno, H.; Asahi, K.; Shimoda, T.; Matsuo, Y.

    2015-11-01

    A new laser spectroscopic method named "OROCHI (Optical RI-atom Observation in Condensed Helium as Ion catcher)" has been developed for deriving the nuclear spins and electromagnetic moments of low-yield exotic nuclei. In this method, we observe atomic Zeeman and hyperfine structures using laser-radio-frequency/microwave double-resonance spectroscopy. In our previous works, double-resonance spectroscopy was performed successfully with laser-sputtered stable atoms including non-alkali Au atoms as well as alkali Rb and Cs atoms. Following these works, measurements with 84-87Rb energetic ion beams were carried out in the RIKEN projectile fragment separator (RIPS). In this paper, we report the present status of OROCHI and discuss its feasibility, especially for low-yield nuclei such as unstable Au isotopes.

  9. Laser cooling and trapping of neutral atoms. Final report, 1 Oct 89-30 Sep 92

    SciTech Connect

    Phillips, W.D.

    1992-07-01

    In 1988, before the beginning of the current contract period, our group discovered that sodium atoms could be laser cooled well below the lower limit (the 'Doppler limit') predicted by the then generally accepted theory. Two main consequences of that discovery were a revamping of the theory of laser cooling and a renewed interest in the applications of laser cooling because of the far lower temperatures. Both of these effects are continuing in full force today, and this report is in large part a record of our group's continuing involvement in the new developments in laser cooling during the past three years. The work of the NIST laser cooling group falls functionally into the categories of: investigating laser cooling mechanisms; studies of collisions between laser cooled atoms; development of new trapping techniques for neutral atoms; study of the fluorescent spectrum of laser cooled atoms; manipulation of atoms and atom optics; development of coherent sources of vacuum ultraviolet light for laser cooling and high resolution spectroscopy; application of laser cooling and trapping technology to atomic frequency standards.

  10. A spectrometer on chemical vapour deposition-diamond basis for the measurement of the charge-state distribution of heavy ions in a laser-generated plasma

    SciTech Connect

    Cayzac, Witold; Frank, Alexander; Schumacher, Dennis; Roth, Markus; Blazevic, Abel; Wamers, Felix; Traeger, Michael; Berdermann, Eleni; Voss, Bernd; Hessling, Thomas

    2013-04-15

    This article reports on the development and the first applications of a new spectrometer which enables the precise and time-resolved measurement of both the energy loss and the charge-state distribution of ion beams with 10 < Z < 30 at energies of 4-8 MeV/u after their interaction with a laser-generated plasma. The spectrometer is based on five 20 Multiplication-Sign 7 mm{sup 2} large and 20 {mu}m thick polycrystalline diamond samples produced via the Chemical Vapour Deposition (CVD) process and was designed with the help of ion-optical simulations. First experiments with the spectrometer were successfully carried out at GSI using {sup 48}Ca ions at an energy of 4.8 MeV/u interacting with a carbon plasma generated by the laser irradiation of a thin foil target. Owing to the high rate capability and the short response time of the spectrometer, pulsed ion beams with 10{sup 3}-10{sup 4} ions per bunch at a bunch frequency of 108 MHz could be detected. The temporal evolution of the five main charge states of the calcium ion beams as well as the corresponding energy loss values could be measured simultaneously. Due to the outstanding properties of diamond as a particle detector, a beam energy resolution ({Delta}E/E) Almost-Equal-To 0.1% could be reached using the presented experimental method, while a precision of 10% in the energy loss and charge-state distribution data was obtained.

  11. Low temperature corneal laser welding investigated by atomic force microscopy

    NASA Astrophysics Data System (ADS)

    Matteini, Paolo; Sbrana, Francesca; Tiribilli, Bruno; Pini, Roberto

    2009-02-01

    The structural modifications in the stromal matrix induced by low-temperature corneal laser welding were investigated by atomic force microscopy (AFM). This procedure consists of staining the wound with Indocyanine Green (ICG), followed by irradiation with a near-infrared laser operated at low-power densities. This induces a local heating in the 55-65 °C range. In welded tissue, extracellular components undergo heat-induced structural modifications, resulting in a joining effect between the cut edges. However, the exact mechanism generating the welding, to date, is not completely understood. Full-thickness cuts, 3.5 mm in length, were made in fresh porcine cornea samples, and these were then subjected to laser welding operated at 16.7 W/cm2 power density. AFM imaging was performed on resin-embedded semi-thin slices once they had been cleared by chemical etching, in order to expose the stromal bulk of the tissue within the section. We then carried out a morphological analysis of characteristic fibrillar features in the laser-treated and control samples. AFM images of control stromal regions highlighted well-organized collagen fibrils (36.2 +/- 8.7 nm in size) running parallel to each other as in a typical lamellar domain. The fibrils exhibited a beaded pattern with a 22-39 nm axial periodicity. Laser-treated corneal regions were characterized by a significant disorganization of the intralamellar architecture. At the weld site, groups of interwoven fibrils joined the cut edges, showing structural properties that were fully comparable with those of control regions. This suggested that fibrillar collagen is not denatured by low-temperature laser welding, confirming previous transmission electron microscopy (TEM) observations, and thus it is probably not involved in the closure mechanism of corneal cuts. The loss of fibrillar organization may be related to some structural modifications in some interfibrillar substance as proteoglycans or collagen VI. Furthermore, AFM imaging was demonstrated to be a suitable tool for attaining three-dimensional information on the fibrillar assembly of corneal stroma. The results suggested that AFM analyses of resin-embedded histological sections subjected to chemical etching provide a rapid and cost-effective response, with an imaging resolution that is quite similar to that of TEM.

  12. Design and realization of beam collimation system for semiconductor laser in atomic magnetometer

    NASA Astrophysics Data System (ADS)

    Chen, Xi; Quan, Wei; Duan, Lihong; Liu, Baiqi; Xu, Fan

    2015-10-01

    Atomic magnetometer which uses alkali atoms as the sensors can realize ultrahigh sensitivity magnetic field measurement and has extensive applications scientific researches. Semiconductor lasers are used as the pump and probe laser in atomic magnetometer. Due to structural characteristics of semiconductor laser, beam divergence angles in vertical and horizontal direction have large deviation and laser beam diverges extremely fast. However, poor laser beam affects the implementation of atomic magnetometer sensitivity adversely. Only the circular laser beam with Gaussian distribution guarantees the homogeneous polarization of alkali atom vapor and high efficiency of atomic magnetometer. Consequently, a beam collimation system must be designed. In this paper, a collimation method using a thin lens and a pair of anamorphic prisms is proposed to guarantee the laser spot size approximately constant. The thin lens is used to decrease fast-axis divergence angle and ensure transmitted light is parallel. The anamorphic prisms pairs expand the laser beam in slow-axis and make the beam spot nearly round. Initially, the effect of thin lenses and anamorphic prisms on the relationship of input and output beam profiles is theoretically analyzed based on principle of geometrical optics. Then the software Zemax is used to simulate the collimation system. Finally, a beam collimation system is designed and tested. The experiment result shows that the laser beam size is approximately 2×2cm2 and the beam approximate a Gaussian profile, which can meet the requirement of the atomic magnetometer.

  13. Request for Support for the Conference on Super Intense Laser Atom Physics

    SciTech Connect

    Todd Ditmire

    2004-10-21

    The Conference on Super Intense Laser Atom Physics (SILAP) was held in November 2003 in Dallas, Texas. The venue for the meeting was South Fork Ranch in the outskirts of Dallas. The topics of the meeting included high harmonic generation and attosecond pulse generation, strong field interactions with molecules and clusters, particle acceleration, and relativistic laser atom interactions.

  14. QED Energy Approach to Atoms and Nuclei in a Strong Laser Field: Radiation Lines

    SciTech Connect

    Glushkov, A. V.

    2010-10-29

    The consistent approach to the 'atom, nucleus - realistic laser field' interaction is presented and based on the QED and Gell-Mann and Low S-matrix formalism. The method is applied to studying the multi-photon resonance width and shift in the atom of H in a laser pulse.

  15. Neutral atomic jet generation by laser ablation of copper targets

    SciTech Connect

    Matos, J. B. de; Rodrigues, N. A. S.

    2014-08-15

    This work aimed the obtainment of a neutral atomic jet departing from a plume generated by laser ablation of copper targets. A pair of electrodes together with a transducer pressure sensor was used to study the ablated plume charge composition and also to measure the ion extraction from the plasma plume. The neutral beam was produced with this setup and the relative abundance of neutrals in the plasma was measured, it decreases from 30% to 8% when the laser fluence is varied from 20 J/cm{sup 2} to 32 J/cm{sup 2}. The necessary voltage to completely remove the ions from the plume varied from 10 V to 230 V in the same fluence range. TOF analysis resulted in center of mass velocities between 3.4 and 4.6 km/s, longitudinal temperature in the range from 1 10{sup 4} K to 2.4 10{sup 4} K and a Mach number of M = 2.36, calculated using purely hydrodynamic expansion approximation.

  16. Quantum Control of Atomic Hydrogen Using Laser Fields

    NASA Astrophysics Data System (ADS)

    Zhang, Xingjun; Red, Eddie; Wynn, Albert, III; Weatherford, Charles

    2007-06-01

    A method for the ab initio simulation of STIRAP (stimulated Raman adiabatic passage) [1,2] laser quantum control of the energy level poulations of atomic ions will be described. The method employs a new algorithm for the solution of the time- dependent Schr"odinger equation which avoids the time-propagator and uses spectral elements in time with a spectral spatial basis.[3] This results in a set of coupled simultaneous equations and is thus an implicit stable procedure. In order to treat the continuum problem (ionization), a complex absorbing potential is used. The spectral spatial basis used is the Coulomb Sturmians.[4] As an initial application, the control of the levels of atomic hydrogen will be presented. [1] S.A. Rice and M. Zhao, Optical Control of Molecular Dynamics, Wiley, New York, 2000. [2] M. Shapiro and P. Brumer, Principles of the Quantum Control of Molecular Processes, Wiley, New York, 2003. [3] C.A. Weatherford, E. Red, and A. Wynn III, J. Mol. Structure (Theochem) 592, 47 (2002). [4] J. Avery, Hyperspherical Harmonics and Generalized Sturmians, Kluwer, Dordrecht, 2000.

  17. Spectral characterisation of tuneable narrow-band diode lasers for Rb atomic spectroscopy and precision instruments

    NASA Astrophysics Data System (ADS)

    Slavov, Dimitar; Affolderbach, C.; Mileti, Gaetano

    2005-04-01

    We have characterized teh spectral properties and wavelength tuning behaviour of different types of diode lasers in order to evaluate their potential for applications in atomic spectroscopy and precision instruments. Here we report on studies of recently developed distributed feedback (DFB) and Fabry-Perot laser diodes, emitting around 780 and 795 nm, in solitary operation as well as in an extended-cavity configuration. In solitary operation both types of laser studied show continuous tuning ranges beyond 40 GHz and single-mode emission linewidths around 6 MHz, which makes them interesting candidates for use in high-precision instruments based on atomic spectroscopy such as atomic frequency standards and atomic magnetometers.

  18. Laser-excited atomic fluorescence spectrometry and atomic absorption spectrometry in flames and graphite tube furnaces

    SciTech Connect

    Dougherty, J.P.

    1987-01-01

    Laser Excited Atomic Fluorescence Spectrometry (LEAFS) and Atomic Absorption Spectrometry (AAS) were investigated to improve techniques for analyzing trace and ultratrace levels of metals in complicated matrices. The atom cells used for LEAFS were two differently designed graphite tube furnaces and an air/acetylene flame. For AAS, a graphite tube furnace was used as the atom cell. The AAS limit of detection for manganese was investigated when the commercial light source, a hollow cathode lamp, was replaced with a microwave excited electrodeless discharge lamp (EDL). The lack of long term stability and the broadening of the emission profile of the EDL, with temperature, did not make it a suitable light source for AAS. The LEAFS instrument was mostly constructed from components that were available commercially. Data collection and automation of the instrument was achieved through the use of a micro-computer and an interface that was controlled with a software algorithm written in assembly and FORTRAN languages. An air/acetylene flame was used in the LEAFS instrument mainly for diagnostic studies, although analytical data were obtained for silver, copper, lead and indium. The graphite tube furnaces were used in the LEAFS instrument to obtain analytical figures of merit for cobalt, lead, indium, manganese, copper, silver and thallium. The limits of detection for these elements ranged from 6 to 500 femtograms, which represent some of the best limits of detection ever reported for any analytical technique. Manganese and thallium were determined in biological material by LEAFS and AAS in a graphite tube furnace. The biological materials investigated were whole mouse brains and bovine liver.

  19. Ordered many-electron motions in atoms and x-ray lasers. [Subpicosecond ultraviolet laser radiation

    SciTech Connect

    Rhodes, C.K.

    1986-01-01

    Subpicosecond ultraviolet laser technology is enabling the exploration of nonlinear atomic interactions with electric field strengths considerably in excess of an atomic unit. As this regime is approached, experiments studying multiple ionization, photoelectron energy spectra, and harmonically produced radiation all exhibit strong nonlinear coupling. Peak total energy transfer rates on the order of approx.2 x 10/sup -4/ W/atom have been observed at an intensity of approx.10/sup 16/ W/cm/sup 2/, and it is expected that energy transfer rates approaching approx.0.1 to 1 W/atom will occur under more extreme conditions for which the ultraviolet electric field E is significantly greater than e/a/sub 0//sup 2/. In this high intensity regime, a wide range of new nonlinear phenomena will be open to study. These will include the possibility of ordered driven motions in atoms, molecules, and plasmas, mechanisms involving collisions, and relativistic processes such as electron-positron pair production. An understanding of these physical interactions may provide a basis for the generation of stimulated emission in the x-ray range. 100 refs., 8 figs.

  20. Clock Technology Development for the Laser Cooling and Atomic Physics (LCAP) Program

    NASA Technical Reports Server (NTRS)

    Klipstein, W. M.; Thompson, R. J.; Seidel, D. J.; Kohel, J.; Maleki, L.

    1998-01-01

    The Time and Frequency Sciences and Technology Group at Jet Propulsion Laboratory (JPL) has developed a laser cooling capability for flight and has been selected by NASA to support the Laser-Cooling and Atomic Physics (LCAP) program. Current work in the group includes design and development for tee two laser-cooled atomic clock experiments which have been selected for flight on the International Space Station.

  1. Two-mode single-atom laser as a source of entangled light

    SciTech Connect

    Kiffner, M.; Evers, J.; Keitel, C. H.; Zubairy, M. S.

    2007-03-15

    A two-mode single-atom laser is considered, with the aim of generating entanglement in macroscopic light. Two transitions in the four-level gain medium atom independently interact with the two cavity modes, while two other transitions are driven by control laser fields. Atomic relaxation as well as cavity losses are taken into account. We show that this system is a source of macroscopic entangled light over a wide range of control parameters and initial states of the cavity field.

  2. Spatial and temporal behaviors of laser beam propagating in atomic vapor

    SciTech Connect

    Nomaru, K.; Chen, Y.; Izawa, Y.; Nakai, S.; Yamanaka, C.

    1996-05-01

    Spatial and temporal behaviors of laser beam propagating in a atomic vapor have been investigated experimentally. The pulse reshapings of frequency-chirped laser pulses in the near-resonant atomic vapor have been demonstrated by making use of atomic samarium vapor. Self-induced transparency and self-focusing have also been observed by streak camera. Theses results will be compared with numerical or analytical results in this paper. {copyright} {ital 1996 American Institute of Physics.}

  3. Collisional redistribution laser cooling of a high-pressure atomic gas

    NASA Astrophysics Data System (ADS)

    Vogl, Ulrich; Sa?, Anne; Ha?elmann, Simon; Weitz, Martin

    2011-09-01

    We describe measurements demonstrating laser cooling of an atomic gas by means of collisional redistribution of radiation. The experiment uses rubidium atoms in the presence of several hundred bar of argon buffer gas pressure. Frequent collisions in the dense gas transiently shift a far red detuned optical field into resonance, while spontaneous emission occurs close to the unperturbed atomic transition frequency. Evidence for the cooling is obtained both via thermographic imaging and via thermographic deflection spectroscopy. The cooled gas has a density above 10$^{21}$ atoms/cm$^3$, yielding evidence for the laser cooling of a macroscopic ensemble of gas atoms.

  4. EFFECTS OF LASER RADIATION ON MATTER. LASER PLASMA: Investigation of the populations of excited states of barium atoms in a laser plasma

    NASA Astrophysics Data System (ADS)

    Burimov, V. N.; Zherikhin, A. N.; Popkov, V. L.

    1995-02-01

    Laser-induced fluorescence was used in an investigation of the populations of the ground and excited (6s5d 3D1 and 3D2) states of Ba atoms in a plasma formed by laser ablation of YBaCuO target. A nonequilibrium velocity distribution of the atoms was detected. At large distances from the target about 4% of the atoms were in an excited state.

  5. Continuous-wave, single-frequency 229??nm laser source for laser cooling of cadmium atoms.

    PubMed

    Kaneda, Yushi; Yarborough, J M; Merzlyak, Yevgeny; Yamaguchi, Atsushi; Hayashida, Keitaro; Ohmae, Noriaki; Katori, Hidetoshi

    2016-02-15

    Continuous-wave output at 229nm for the application of laser cooling of Cd atoms was generated by the fourth harmonic using two successive second-harmonic generation stages. Employing a single-frequency optically pumped semiconductor laser as a fundamental source, 0.56W of output at 229nm was observed with a 10-mm long, Brewster-cut BBO crystal in an external cavity with 1.62W of 458nm input. Conversion efficiency from 458nm to 229nm was more than 34%. By applying a tapered amplifier (TA) as a fundamental source, we demonstrated magneto-optical trapping of all stable Cd isotopes including isotopes Cd111 and Cd113, which are applicable to optical lattice clocks. PMID:26872168

  6. Fast switching of alkali atom dispensers using laser-induced heating

    SciTech Connect

    Griffin, P.F.; Weatherill, K.J.; Adams, C.S.

    2005-09-15

    We show that by using an intense laser source to locally heat an alkali atom dispenser, one can generate a high flux of atoms followed by fast recovery (<100 ms) of the background pressure when the laser is extinguished. For repeated heating pulses a switch-on time for the atomic flux of 200 ms is readily attainable. This technique is suited to ultracold atom experiments using simple ultrahigh vacuum (UHV) chambers. Laser-induced heating provides a fast repetition of the experimental cycle, which, combined with low atom loss due to background gas collisions, is particularly useful for experiments involving far-off resonance optical traps, where sufficient laser power (0.5-4 W) is readily available.

  7. Laser-induced fluorescence detection strategies for sodium atoms and compounds in high-pressure combustors

    NASA Technical Reports Server (NTRS)

    Weiland, Karen J. R.; Wise, Michael L.; Smith, Gregory P.

    1993-01-01

    A variety of laser-induced fluorescence schemes were examined experimentally in atmospheric pressure flames to determine their use for sodium atom and salt detection in high-pressure, optically thick environments. Collisional energy transfer plays a large role in fluorescence detection. Optimum sensitivity, at the parts in 10 exp 9 level for a single laser pulse, was obtained with the excitation of the 4p-3s transition at 330 nm and the detection of the 3d-3p fluorescence at 818 nm. Fluorescence loss processes, such as ionization and amplified spontaneous emission, were examined. A new laser-induced atomization/laser-induced fluorescence detection technique was demonstrated for NaOH and NaCl. A 248-nm excimer laser photodissociates the salt molecules present in the seeded flames prior to atom detection by laser-induced fluorescence.

  8. Simple interface of high-performance liquid chromatography-atomic fluorescence spectrometry hyphenated system for speciation of mercury based on photo-induced chemical vapour generation with formic acid in mobile phase as reaction reagent.

    PubMed

    Yin, Yongguang; Liu, Jingfu; He, Bin; Shi, Jianbo; Jiang, Guibin

    2008-02-15

    Photo-induced chemical vapour generation (CVG) with formic acid in mobile phase as reaction reagent was developed as interface to on-line couple HPLC with atomic fluorescence spectrometry for the separation and determination of inorganic mercury, methylmercury (MeHg), ethylmercury (EtHg) and phenylmercury (PhHg). In the developed procedure, formic acid in mobile phase was used to decompose organomercuries and reduce Hg(2+) to mercury cold vapour under UV irradiation. Therefore, no post-column reagent was used and the flow injection system in traditional procedure is omitted. A number of operating parameters including pH of mobile phase, concentration of formate, flow rate of mobile phase, length of PTFE reaction coil, flow rate of carrier gas and Na(2)S(2)O(3) in sample matrix were optimized. The limits of detection at the optimized conditions were 0.085, 0.033, 0.029 and 0.038 microg L(-1) for inorganic mercury, MeHg, EtHg and PhHg, respectively. The developed method was validated by determination of certified reference material DORM-2 and was further applied in analyses of seafood samples from Yantai port, China. The UV-CVG with formic acid simplifies the instrumentation and reduces the analytical cost significantly. PMID:18184614

  9. Spin physics with laser-pumped helium atoms

    SciTech Connect

    Schearer, L.D.

    1993-05-01

    With the development of new, tunable lasers at 1083 nm, direct optical pumping of the triplet metastable atoms of helium yields an almost perfectly aligned ensemble. In {sup 3}He the hyperflne interaction and collisions transfer the orientation to the groundstate nuclear spins. The optical pumping process in {sup 3}He is extraordinarily efficient- nearly 2.5 nuclei are oriented per absorbed photon at turn-on. Applications to magnetometry, the production of spin-polarized electron and ion beams, and the development of polarized neutron beams and dense targets will be discussed. The progress of the UNI-Mainz experiment to measure the electric and magnetic form factors of the neutron will be described. In this experiment the polarized {sup 3}He target is mechanically compressed to several atmospheres with minimal loss of nuclear polarization. Extension of this dense nuclear target for use as a neutron spin filter is also in progress. We will also describe the status of our experiment to observe scattering asymmetries of polarized electrons by chiral molecules. Progress on the development of a compact, moderate current, polarized e-beam will be discussed.

  10. A self-injected, diode-pumped, solid-state ring laser for laser cooling of Li atoms

    SciTech Connect

    Miake, Yudai; Mukaiyama, Takashi; O’Hara, Kenneth M.; Gensemer, Stephen

    2015-04-15

    We have constructed a solid-state light source for experiments with laser cooled lithium atoms based on a Nd:Y V O{sub 4} ring laser with second-harmonic generation. Unidirectional lasing, an improved mode selection, and a high output power of the ring laser were achieved by weak coupling to an external cavity which contained the lossy elements required for single frequency operation. Continuous frequency tuning is accomplished by controlling two piezoelectric transducers (PZTs) in the internal and the external cavities simultaneously. The light source has been utilized to trap and cool fermionic lithium atoms into the quantum degenerate regime.

  11. A self-injected, diode-pumped, solid-state ring laser for laser cooling of Li atoms.

    PubMed

    Miake, Yudai; Mukaiyama, Takashi; O'Hara, Kenneth M; Gensemer, Stephen

    2015-04-01

    We have constructed a solid-state light source for experiments with laser cooled lithium atoms based on a Nd:YVO4 ring laser with second-harmonic generation. Unidirectional lasing, an improved mode selection, and a high output power of the ring laser were achieved by weak coupling to an external cavity which contained the lossy elements required for single frequency operation. Continuous frequency tuning is accomplished by controlling two piezoelectric transducers (PZTs) in the internal and the external cavities simultaneously. The light source has been utilized to trap and cool fermionic lithium atoms into the quantum degenerate regime. PMID:25933847

  12. A self-injected, diode-pumped, solid-state ring laser for laser cooling of Li atoms

    NASA Astrophysics Data System (ADS)

    Miake, Yudai; Mukaiyama, Takashi; O'Hara, Kenneth M.; Gensemer, Stephen

    2015-04-01

    We have constructed a solid-state light source for experiments with laser cooled lithium atoms based on a Nd:Y V O4 ring laser with second-harmonic generation. Unidirectional lasing, an improved mode selection, and a high output power of the ring laser were achieved by weak coupling to an external cavity which contained the lossy elements required for single frequency operation. Continuous frequency tuning is accomplished by controlling two piezoelectric transducers (PZTs) in the internal and the external cavities simultaneously. The light source has been utilized to trap and cool fermionic lithium atoms into the quantum degenerate regime.

  13. Methods and evaluation of frequency aging in distributed-feedback laser diodes for rubidium atomic clocks

    NASA Astrophysics Data System (ADS)

    Matthey, Renaud; Affolderbach, Christoph; Mileti, Gaetano

    2011-09-01

    Distributed-feedback laser diodes emitting at 780nm have been evaluated, with respect to the aging of the injection current required for reaching the rubidium D2 resonance line. Results obtained for lasers operating in air and in vacuum for 9 months are reported. When operated at constant temperature, the laser current required for emission at the wavelength of the desired atomic resonance is found to decrease by 50 to 80?A per month. The impact of this result on the lifetime and long-term performances of laser-pumped rubidium atomic clocks is discussed.

  14. Methods and evaluation of frequency aging in distributed-feedback laser diodes for rubidium atomic clocks.

    PubMed

    Matthey, Renaud; Affolderbach, Christoph; Mileti, Gaetano

    2011-09-01

    Distributed-feedback laser diodes emitting at 780?nm have been evaluated, with respect to the aging of the injection current required for reaching the rubidium D2 resonance line. Results obtained for lasers operating in air and in vacuum for 9 months are reported. When operated at constant temperature, the laser current required for emission at the wavelength of the desired atomic resonance is found to decrease by 50 to 80??A per month. The impact of this result on the lifetime and long-term performances of laser-pumped rubidium atomic clocks is discussed. PMID:21886194

  15. Electron-impact excitation of holmium atoms

    SciTech Connect

    Smirnov, Yu M

    2000-06-30

    The electron-impact excitation of holmium atoms was studied by the method of extended crossing beams. The cross sections and the optical excitation functions were obtained for odd levels of Ho I, including the 22014 cm{sup -1} laser level. Over 99% of the atoms were shown to reside in the ground level prior to collisions with electrons. Also measured were the excitation cross sections for six even levels, which presumably participate in the formation of inversion population in a gas-discharge holmium vapour laser. (laser applications and other topics in quantum electronics)

  16. Construction and characterization of external cavity diode lasers for atomic physics.

    PubMed

    Hardman, Kyle S; Bennetts, Shayne; Debs, John E; Kuhn, Carlos C N; McDonald, Gordon D; Robins, Nick

    2014-01-01

    Since their development in the late 1980s, cheap, reliable external cavity diode lasers (ECDLs) have replaced complex and expensive traditional dye and Titanium Sapphire lasers as the workhorse laser of atomic physics labs. Their versatility and prolific use throughout atomic physics in applications such as absorption spectroscopy and laser cooling makes it imperative for incoming students to gain a firm practical understanding of these lasers. This publication builds upon the seminal work by Wieman, updating components, and providing a video tutorial. The setup, frequency locking and performance characterization of an ECDL will be described. Discussion of component selection and proper mounting of both diodes and gratings, the factors affecting mode selection within the cavity, proper alignment for optimal external feedback, optics setup for coarse and fine frequency sensitive measurements, a brief overview of laser locking techniques, and laser linewidth measurements are included. PMID:24796259

  17. Construction and Characterization of External Cavity Diode Lasers for Atomic Physics

    PubMed Central

    Hardman, Kyle S.; Bennetts, Shayne; Debs, John E.; Kuhn, Carlos C. N.; McDonald, Gordon D.; Robins, Nick

    2014-01-01

    Since their development in the late 1980s, cheap, reliable external cavity diode lasers (ECDLs) have replaced complex and expensive traditional dye and Titanium Sapphire lasers as the workhorse laser of atomic physics labs1,2. Their versatility and prolific use throughout atomic physics in applications such as absorption spectroscopy and laser cooling1,2 makes it imperative for incoming students to gain a firm practical understanding of these lasers. This publication builds upon the seminal work by Wieman3, updating components, and providing a video tutorial. The setup, frequency locking and performance characterization of an ECDL will be described. Discussion of component selection and proper mounting of both diodes and gratings, the factors affecting mode selection within the cavity, proper alignment for optimal external feedback, optics setup for coarse and fine frequency sensitive measurements, a brief overview of laser locking techniques, and laser linewidth measurements are included. PMID:24796259

  18. First-order correlation functions in a binary-collisions atom laser scheme

    NASA Astrophysics Data System (ADS)

    Zobay, O.; Meystre, P.

    1998-05-01

    First-order correlation functions for a recently proposed atom laser scheme [1,2] are investigated. In this model the atomic dynamics is described in terms of a system of three atomic resonator modes, i.e. pump, loss, and laser mode. The laser operation relies on binary collisions between ground state atoms fed into the pump mode. After adiabatically eliminating the loss mode analytical approximations for the first-order correlation function of the laser mode can be derived using a linearized fluctuation ansatz. With the help of these approximations which have been checked against numerical simulations the influence of the various system parameters, i.e. pumping and collision strengths, on the laser linewidth can be discussed. Applying these results to the atom laser scheme of Ref. [2] it is shown that a laser linewidth of the order of the natural linewidth of the laser mode might be achievable. [1] M. Holland et al, Phys. Rev. A 54, R1757 (1996). [2] M. G. Moore and P. Meystre, Phys. Rev. A 56, 2989 (1997).

  19. Annealing study of H2O and O3 grown Al2O3 deposited by atomic layer chemical vapour deposition on n-type 4H-SiC

    NASA Astrophysics Data System (ADS)

    Avice, Marc; Grossner, Ulrike; Nilsen, Ola; Christensen, Jens S.; Fjellvg, Helmer; Svensson, Bengt G.

    2006-09-01

    Al2O3 has been grown by atomic layer chemical vapour deposition on HF cleaned n-type 4H-SiC using either H2O or O3 as an oxidant. After post-deposition annealing at high temperature (1000C) in argon atmosphere for different durations (1, 2 and 3 h), bulk and interface properties of the films were studied by capacitance-voltage (CV), current-voltage (IV) and secondary ion mass spectrometry (SIMS) measurements. Electrical measurements show a decreasing shift of the flatband voltage indicating a diminution of the negative oxide charges with increasing annealing time. The SIMS measurements reveal accumulation of boron, sodium and potassium at the Al2O3/SiC interface but the accumulation decreases with annealing at 1000C where also out diffusion of silicon into the Al2O3 film takes place.

  20. Determining the stable isotope composition of pore water from saturated and unsaturated zone core: improvements to the direct vapour equilibration laser spectrometry method

    NASA Astrophysics Data System (ADS)

    Hendry, M. J.; Schmeling, E.; Wassenaar, L. I.; Barbour, S. L.; Pratt, D.

    2015-11-01

    A method to measure the δ2H and δ18O composition of pore waters in saturated and unsaturated geologic core samples using direct vapour equilibration and laser spectrometry (DVE-LS) was first described in 2008, and has since been rapidly adopted. Here, we describe a number of important methodological improvements and limitations encountered in routine application of DVE-LS over several years. Generally, good comparative agreement, as well as accuracy, is obtained between core pore water isotopic data obtained using DVE-LS and that measured on water squeezed from the same core. In complex hydrogeologic settings, high-resolution DVE-LS depth profiles provide greater spatial resolution of isotopic profiles compared to long-screened or nested piezometers. When fluid is used during drilling and coring (e.g. water rotary or wet sonic drill methods), spiking the drill fluid with 2H can be conducted to identify core contamination. DVE-LS analyses yield accurate formational isotopic data for fine-textured core (e.g. clay, shale) samples, but are less effective for cores obtained from saturated permeable (e.g. sand, gravels) geologic media or on chip samples that are easily contaminated by wet rotary drilling fluid. Data obtained from DVE-LS analyses of core samples collected using wet (contamination by drill water) and dry sonic (water loss by heating) methods were also problematic. Accurate DVE-LS results can be obtained on core samples with gravimetric water contents > 5 % by increasing the sample size tested. Inexpensive Ziploc™ gas-sampling bags were determined to be as good as, if not better than, other, more expensive specialty bags. Sample storage in sample bags provides acceptable results for up to 10 days of storage; however, measurable water loss, as well as evaporitic isotopic enrichment, occurs for samples stored for up to 6 months. With appropriate care taken during sample collection and storage, the DVE-LS approach for obtaining high-resolution pore water isotopic data is a promising alternative to study the hydrogeology of saturated and unsaturated sediments. Eliminating analytical interferences from volatile organics remains a challenge.

  1. Broadening the applications of the atom probe technique by ultraviolet femtosecond laser.

    PubMed

    Hono, K; Ohkubo, T; Chen, Y M; Kodzuka, M; Oh-ishi, K; Sepehri-Amin, H; Li, F; Kinno, T; Tomiya, S; Kanitani, Y

    2011-05-01

    Laser assisted field evaporation using ultraviolet (UV) wavelength gives rise to better mass resolution and signal-to-noise ratio in atom probe mass spectra of metals, semiconductors and insulators compared to infrared and green lasers. Combined with the site specific specimen preparation techniques using the lift-out and annular Ga ion milling in a focused ion beam machine, a wide variety of materials including insulating oxides can be quantitatively analyzed by the three-dimensional atom probe using UV laser assisted field evaporation. After discussing laser irradiation conditions for optimized atom probe analyses, recent atom probe tomography results on oxides, semiconductor devices and grain boundaries of sintered magnets are presented. PMID:21177036

  2. An all-gas-phase amine based iodine laser using molecular iodine as atomic iodine donor

    NASA Astrophysics Data System (ADS)

    Masuda, Taizo; Nakamura, Tomonari; Endo, Masamori

    2010-01-01

    The laser action of an all-gas-phase iodine laser that uses molecular iodine as a source of iodine atoms has been demonstrated. The laser is based on the energy transfer reaction between metastable NCl(a 1?) and ground-state I( 2P 3/2) atoms. The replacement of iodine source from HI to I 2 had been desired, but it was considered to be difficult due to the high deactivation reaction rate of excited iodine atoms by residual I 2. In this system, iodine atoms are produced by microwave discharge. Continuous-wave laser output of 35 mW with a duty factor of 40% was observed. This is 70% of the output from the same system with HI iodine source.

  3. Testing Lorentz Invariance with Laser-Cooled Cesium Atomic Frequency Standards

    NASA Technical Reports Server (NTRS)

    Klipstein, William M.

    2004-01-01

    This slide presentation reviews the Lorentz invariance testing during the proposed PARCS experiment. It includes information on the primary atomic reference clock in space (PARCS), cesium, laser cooling, and the vision for the future.

  4. Laser-Induced Particle Adsorption on Atomically Thin MoS2.

    PubMed

    Tran Khac, Bien Cuong; Jeon, Ki-Joon; Choi, Seung Tae; Kim, Yong Soo; DelRio, Frank W; Chung, Koo-Hyun

    2016-02-10

    Atomically thin molybdenum disulfide (MoS2) shows great potential for use in nanodevices because of its remarkable electronic, optoelectronic, and mechanical properties. These material properties are often dependent on the thickness or the number of layers, and hence Raman spectroscopy is widely used to characterize the thickness of atomically thin MoS2 due to the sensitivity of the vibrational spectrum to thickness. However, the lasers used in Raman spectroscopy can increase the local surface temperature and eventually damage the upper layers of the MoS2, thereby changing the aforementioned material properties. In this work, the effects of lasers on the topography and material properties of atomically thin MoS2 were systematically investigated using Raman spectroscopy and atomic force microscopy. In detail, friction force microscopy was used to study the friction characteristics of atomically thin MoS2 as a function of laser powers from 0.5 to 20 mW and number of layers from 1 to 3. It was found that particles formed on the top surface of the atomically thin MoS2 due to laser-induced thermal effects. The degree of particle formation increased as the laser power increased, prior to the thinning of the atomically thin MoS2. In addition, the degree of particle formation increased as the number of MoS2 layers increased, which suggests that the thermal behavior of the supported MoS2 may differ depending on the number of layers. The particles likely originated from the atmosphere due to laser-induced heating, but could be eliminated via appropriate laser powers and exposure times, which were determined experimentally. The outcomes of this work indicate that thermal management is crucial in the design of reliable nanoscale devices based on atomically thin MoS2. PMID:26795729

  5. Polarization response of interacting atomic systems in an intense resonance laser field

    SciTech Connect

    Gulyaev, A. V. Tikhonova, O. V.

    2012-05-15

    The dynamics and quantum correlations are studied in a system of two interacting atoms in a resonance femtosecond laser field. The polarization response of a medium consisting of such pairs of interacting atoms is analyzed. Regimes are found in which the polarization response of the medium under study contains the intense component at a tunable low frequency. It is shown that the dipole response of the medium can be suppressed using the entanglement effect and symmetry properties of collective atomic states.

  6. Two Step Deceleration of Cesium Atomic Beam by Frequency Modulated Diode Lasers

    NASA Astrophysics Data System (ADS)

    Yoneyama, Toshio; Sato, Shunichi

    2005-11-01

    Two step white light slowing of a cesium atomic beam was demonstrated by using two kinds of frequency modulated diode lasers. In addition to a frequency modulated free-running diode laser used for the first step of wide range deceleration, a frequency modulated external cavity diode laser (ECDL) with narrower and sharper spectrum was used for the second step deceleration. It was shown that the number of slowed atoms was increased more than twofold by the two step deceleration which kept narrow velocity width of 27 m/s, which is smaller than that by only the single step deceleration.

  7. Magnetic-field-induced enhancement of atomic stabilization in intense high-frequency laser fields

    NASA Astrophysics Data System (ADS)

    Simonsen, Aleksander Skjerlie; Frre, Morten

    2015-07-01

    The role of the magnetic-field component of the laser pulse on the phenomenon of atomic stabilization is investigated in an ab initio study. This is achieved by solving the time-dependent Schrdinger equation for the laser-atom interaction beyond the dipole approximation. The system under study is atomic hydrogen and the atom is assumed to be irradiated by an intense xuv laser light pulse of varying intensity and duration. We consider two different photon energies, ? ? =54 and 95 eV. The main finding is that there exists a range of laser pulse durations lasting for a few tens of field cycles where the atomic stabilization effect is enhanced due to the magnetic-field component. This is a rather surprising result that contradicts earlier statements made in the few-cycle pulse regime, where it has been shown that the magnetic field has a destructive effect in that the degree of stabilization is suppressed. It is further found that in the long-pulse limit the ionization probabilities obtained when illuminating the target with dipole and nondipole fields eventually coincide, meaning that the magnetic-field component of the laser field finally loses its significance in the context of atomic stabilization. It is also found that within the window of enhanced stabilization, the surplus population is distributed among excited bound states rather than in the initial ground state.

  8. Mechanisms of infrared-laser-assisted atomic ionization by attosecond pulses

    SciTech Connect

    Tong, X. M.; Ranitovic, P.; Cocke, C. L.; Toshima, N.

    2010-02-15

    We propose a mechanism to understand the infrared (IR) laser assisted atomic ionization by attosecond pulses (AP). Atomic structures in an IR laser field are described by Floquet states and atoms can be ionized to a Floquet state by a single AP through different Floquet components. The interference of ionization through different Floquet components results in the oscillation of the ionization yield as a function of the arriving time of the AP. The proposed mechanism explains the recent experimental observations [Johnsson et al., Phys. Rev. Lett. 99, 233001 (2007)]. Furthermore, we find that, for a specified photoelectron energy, the ionization yield always oscillates as a function of the relative phase between the AP and the IR laser for both He and Ar atoms.

  9. Improved production of Br atoms near zero speed by photodissociating laser aligned Br2 molecules.

    PubMed

    Deng, L Z; Yin, J P

    2014-10-28

    We theoretically investigated the improvement on the production rate of the decelerated bromine (Br) atoms near zero speed by photodissociating laser aligned Br2 precursors. Adiabatic alignment of Br2 precursors exposed to long laser pulses with duration on the order of nanoseconds was investigated by solving the time-dependent Schrdinger equation. The dynamical fragmentation of adiabatically aligned Br2 precursors was simulated and velocity distribution of the Br atoms produced was analyzed. Our study shows that the larger the degree of the precursor alignment, ?cos(2)???, the higher the production rate of the decelerated Br atoms near zero speed. For Br2 molecules with an initial rotational temperature of ~1 K, a ?cos(2)??? value of ~0.88 can result in an improvement factor of over ~20 on the production rate of the decelerated Br atoms near zero speed, requiring a laser intensity of only ~1 10(12) W/cm(2) for alignment. PMID:25362306

  10. Determining traces of indium in especial-purity tin by laser atomic absorption

    SciTech Connect

    Bykov, I.V.; Chekalin, N.V.; Tikhomirova, E.I.

    1985-04-20

    This paper examines various schemes for the selective laser excitation of tin atoms in an acetylene-air flame. The exciting source was provided by two laser systems: dye lasers, which include master lasers and a prism telescope along with an amplifier having transverse pumping by a nitrogen laser, and dye lasers employing glancing incidence and longitudinal pumping by the second harmonic of an Nd-YAG laser. A limit of detection for indium in aqueous solution of about 1 pg/ml has been attained and there is virtually no effect from tin in a two-stage ioinization scheme up to a concentration of 50 g/liter. It is possible to determine indium in tin at the level of 10/sup -8/%.

  11. Determination of total urinary mercury by on-line sample microwave digestion followed by flow injection cold vapour inductively coupled plasma mass spectrometry or atomic absorption spectrometry.

    PubMed

    Bettinelli, M; Spezia, S; Ronchi, A; Minoia, C

    2002-01-01

    The total mercury content in urine was determined by inductively coupled plasma mass spectrometry with the so-called cold vapour method after on-line oxidative treatment of the sample in a microwave oven (FI-MW-CV-ICPMS). Use of a KBr/KBrO(3) mixture, microwave digestion, and the final oxidation with KMnO(4), assure the complete recovery of the organic forms of Hg which would be difficult to determine otherwise if using only the CV-ICPMS apparatus. Quantitative recoveries were obtained for phenyl Hg chloride (PMC), dimethyl Hg (DMM), Hg acetate (MA) and methyl Hg chloride (MMC). Use of automatic flow injection microwave systems (FI-MW) for sample treatment reduces environmental contamination and allows detection limits suitable for the determination of reference values. Since no certified reference materials were commercially available in the concentration ranges of interest, the accuracy of the proposed procedure has been assessed by analysing a series of urine samples with two independent techniques, ICP-MS and AAS. When using the FI-MW-CV-ICP-MS technique, the detection limit was assessed at 0.03microg/L Hg, while with FI-MW-CV-AAS it was 0.2microg/L Hg. The precision of the method was less than 2-3% for FI-MW-CV-ICP-MS and about 3-5% for FI-MV-CV-AAS at concentrations below 1microg/L Hg. These results show that ICP-MS can be considered as a "reference technique" for the determination of total urinary Hg at very low concentrations, such as are present in non-exposed subjects. PMID:12125019

  12. Pulsed-laser atom probe studies of a precipitation hardened maraging TRIP steel.

    PubMed

    Dmitrieva, O; Choi, P; Gerstl, S S A; Ponge, D; Raabe, D

    2011-05-01

    A precipitation hardened maraging TRIP steel was analyzed using a pulsed laser atom probe. The laser pulse energy was varied from 0.3 to 1.9 nJ to study its effect on the measured chemical compositions and spatial resolution. Compositional analyses using proximity histograms did not show any significant variations in the average matrix and precipitate compositions. The only remarkable change in the atom probe data was a decrease in the ++/+ charge state ratios of the elements. The values of the evaporation field used for the reconstructions exhibit a linear dependence on the laser pulse energy. The adjustment of the evaporation fields used in the reconstructions for different laser pulse energies was based on the correlation of the obtained cluster shapes to the TEM observations. No influence of laser pulse energy on chemical composition of the precipitates and on the chemical sharpness of their interfaces was detected. PMID:21215524

  13. Phase-locked laser system for use in atomic coherence experiments.

    PubMed

    Marino, Alberto M; Stroud, C R

    2008-01-01

    We describe a phase-coherent laser system designed for use in experiments involving coherently prepared atomic media. We implement a simple technique based on a sample-and-hold circuit together with a reset of the integrating electronics that makes it possible to scan continuously the relative frequency between the lasers of over tens of gigahertz while keeping them phase locked. The system consists of three external-cavity diode lasers operating around 795 nm. A low-power laser serves as a frequency reference for two high-power lasers which are phased locked with an optical phase-locked loop. We measured the residual phase noise of the system to be less than 0.04 rad(2). In order to show the application of the system towards atomic coherence experiments, we used it to implement electromagnetically induced transparency in a rubidium vapor cell and obtained a reduction in the absorption coefficient of 92%. PMID:18248019

  14. A phase-modulated laser system of ultra-low phase noise for compact atom interferometers

    NASA Astrophysics Data System (ADS)

    Lee, Ki-Se; Kim, Jaewan; Lee, Sang-Bum; Park, Sang Eon; Kwon, Taek Yong

    2015-07-01

    A compact and robust laser system is essential for mobile atom interferometers. Phase modulation can provide the two necessary phase-coherent frequencies without sophisticated phase-locking between two different lasers. However, the additional laser frequencies generated can perturb the atom interferometer. In this article, we report on a novel method to produce a single high-power laser beam composed of two phase-coherent sidebands without the perturbing carrier mode. Light from a diode laser is phase-modulated by using a fiber-coupled electro-optic modulator driven at 3.4 GHz and passes through a Fabry-Perot cavity with a 6.8 GHz free spectral range. The cavity filters the carrier mode to leave the two first-order sidebands for the two-photon Raman transition between the two hyperfine ground states of 87Rb. The laser beam is then fed to a single tapered amplifier, and the two sidebands are both amplified without mode competition. The phase noise is lower than that of a state-of-the-art optically phase-locked external-cavity diode laser (-135 dBrad2/Hz at 10 kHz) at frequencies above 10 Hz. This technique can be used in all-fiber-based laser systems for future mobile atom interferometers.

  15. Neutral Rydberg-state excitation of atoms and diatomic molecules in strong laser fields

    NASA Astrophysics Data System (ADS)

    Lv, Hang; Zhang, Junfeng; Zuo, Wanlong; Jin, Mingxing; Xu, Haifeng; Ding, Dajun

    2014-04-01

    Using pulsed-field ionization technique combining with time-of-flight mass spectrometer, we have observed neutral Rydberg-state excitation of Ar atom and NO molecule when irradiated by a 90-fs 800-nm laser with intensity range of 1.5×1014 ~ 3.0×1015 Wcm-2. The dependence of the Rydberg-state excitation on the polarization and intensity of the laser field has been investigated. The results show that Rydberg-state excitation is suppressed by the circular polarized laser and the yield of Rydberg-state exhibits a plateau structure as the laser intensity is increased.

  16. Diode-Pumped Alkali Atom Lasers 03-LW-024 Final Report

    SciTech Connect

    Page, R H; Beach, R J

    2005-02-16

    The recent work at LLNL on alkali-atom lasers has been remarkably successful and productive. Three main phases (so far) can be identified. First, the concept and demonstration of red lasers using (Ti:sapphire pumping) took place; during this time, Rubidium and Cesium resonance-line lasers were tested, and theoretical models were developed and shown to describe experimental results very reliably. Work done during this first phase has been well documented, and the models from that period are still in use for their predictions and for designing power-scaled lasers. [1 - 3] Second, attempts were made to produce a blue alkali-vapor laser using sequentially-resonant two-step pumping (again, using Ti:sapphire lasers.) Although a blue laser did not result, the physical limitations of our approach are now better-defined. Third, diode-pumped operation of a red laser (Rubidium) was attempted, and we eventually succeeded in demonstrating the world's first diode-pumped gas laser. [4] Because we have a defensible concept for producing an efficient, compact, lightweight, power-scaled laser (tens of kW,) we are in a position to secure outside funding, and would like to find a sponsor. For descriptions of work done during the ''first phase,'' see References [1 - 3] ''Phase two'' work is briefly described in the section ''Blue laser,'' and ''phase three'' work is presented in the section entitled ''Diode-pumped red laser.''

  17. High-order-harmonic generation from Rydberg atoms driven by plasmon-enhanced laser fields

    NASA Astrophysics Data System (ADS)

    Tikman, Y.; Yavuz, I.; Ciappina, M. F.; Chacón, A.; Altun, Z.; Lewenstein, M.

    2016-02-01

    We theoretically investigate high-order-harmonic generation (HHG) in Rydberg atoms driven by spatially inhomogeneous laser fields, induced, for instance, by plasmonic enhancement. It is well known that the laser intensity should exceed a certain threshold in order to stimulate HHG when noble gas atoms in their ground state are used as an active medium. One way to enhance the coherent light coming from a conventional laser oscillator is to take advantage of the amplification obtained by the so-called surface plasmon polaritons, created when a low-intensity laser field is focused onto a metallic nanostructure. The main limitation of this scheme is the low damage threshold of the materials employed in the nanostructure engineering. In this work we propose the use of Rydberg atoms, driven by spatially inhomogeneous, plasmon-enhanced laser fields, for HHG. We exhaustively discuss the behavior and efficiency of these systems in the generation of coherent harmonic emission. Toward this aim we numerically solve the time-dependent Schrödinger equation for an atom, with an electron initially in a highly excited n th Rydberg state, located in the vicinity of a metallic nanostructure. In this zone the electric field changes spatially on scales relevant for the dynamics of the laser-ionized electron. We first use a one-dimensional model to investigate systematically the phenomena. We then employ a more realistic situation, in which the interaction of a plasmon-enhanced laser field with a three-dimensional hydrogen atom is modeled. We discuss the scaling of the relevant input parameters with the principal quantum number n of the Rydberg state in question and demonstrate that harmonic emission can be achieved from Rydberg atoms well below the damage threshold, thus without deterioration of the geometry and properties of the metallic nanostructure.

  18. Laser-Assisted Field Evaporation and Three-Dimensional Atom-by-Atom Mapping of Diamond Isotopic Homojunctions.

    PubMed

    Mukherjee, Samik; Watanabe, Hideyuki; Isheim, Dieter; Seidman, David N; Moutanabbir, Oussama

    2016-02-10

    It addition to its high evaporation field, diamond is also known for its limited photoabsorption, strong covalent bonding, and wide bandgap. These characteristics have been thought for long to also complicate the field evaporation of diamond and make its control hardly achievable on the atomistic-level. Herein, we demonstrate that the unique behavior of nanoscale diamond and its interaction with pulsed laser lead to a controlled field evaporation thus enabling three-dimensional atom-by-atom mapping of diamond (12)C/(13)C homojunctions. We also show that one key element in this process is to operate the pulsed laser at high energy without letting the dc bias increase out of bounds for diamond nanotip to withstand. Herein, the role of the dc bias in evaporation of diamond is essentially to generate free charge carriers within the nanotip via impact ionization. The mobile free charges screen the internal electric field, eventually creating a hole rich surface where the pulsed laser is effectively absorbed leading to an increase in the nanotip surface temperature. The effect of this temperature on the uncertainty in the time-of-flight of an ion, the diffusion of atoms on the surface of the nanotip, is also discussed. In addition to paving the way toward a precise manipulation of isotopes in diamond-based nanoscale and quantum structures, this result also elucidates some of the basic properties of dielectric nanostructures under high electric field. PMID:26741402

  19. Fluctuation properties of laser light after interaction with an atomic system: Comparison between two-level and multilevel atomic transitions

    NASA Astrophysics Data System (ADS)

    Lezama, A.; Rebhi, R.; Kastberg, A.; Tanzilli, S.; Kaiser, R.

    2015-09-01

    The complex internal atomic structure involved in radiative transitions has an effect on the spectrum of fluctuations (noise) of the transmitted light. A degenerate transition has different properties in this respect than a pure two-level transition. We investigate these variations by studying a certain transition between two degenerate atomic levels for different choices of the polarization state of the driving laser. For circular polarization, corresponding to the textbook two-level-atom case, the optical spectrum shows the characteristic Mollow triplet for strong laser drive, while the corresponding noise spectrum exhibits squeezing in some frequency ranges. For a linearly polarized drive, corresponding to the case of a multilevel system, additional features appear in both optical and noise spectra. These differences are more pronounced in the regime of a weakly driven transition: whereas the two-level case essentially exhibits elastic scattering, the multilevel case has extra noise terms related to spontaneous Raman transitions. We also discuss the possibility to experimentally observe these predicted differences for the commonly encountered case where the laser drive has excess noise in its phase quadrature.

  20. Site-Specific Laser Modification of MgO nanoclusters: Towards Atomic-Scale Surface Structuring

    SciTech Connect

    Beck, Kenneth M.; Henyk, Matthias; Wang, Chong M.; Trevisanutto, P. E.; Sushko, Petr; Hess, Wayne P.; Shluger, Alexander L.

    2006-07-06

    Atomic emission from MgO nanostructures is induced using laser light tuned to excite specific surface sites at energies well below the excitation threshold of the bulk material. We find that near UV excitation of MgO nancrystalline films and nanocube samples desorbs neutral Mg-atoms with hyper-thermal kinetic energies in the range of 0.1-0.4 eV. Our ab initio calculations suggest that metal atom emission is induced predominantly by electron trapping at surface 3-coordinated Mg sites followed by electronic excitation at these sites. The proposed general mechanism can be used to control atomic scale modification of insulating surfaces.

  1. Laser-cooled atoms inside a hollow-core photonic-crystal fiber

    SciTech Connect

    Bajcsy, M.; Hofferberth, S.; Balic, V.; Zibrov, A. S.; Lukin, M. D.; Peyronel, T.; Liang, Q.; Vuletic, V.

    2011-06-15

    We describe the loading of laser-cooled rubidium atoms into a single-mode hollow-core photonic-crystal fiber. Inside the fiber, the atoms are confined by a far-detuned optical trap and probed by a weak resonant beam. We describe different loading methods and compare their trade-offs in terms of implementation complexity and atom-loading efficiency. The most efficient procedure results in loading of {approx}30,000 rubidium atoms, which creates a medium with an optical depth of {approx}180 inside the fiber. Compared to our earlier study this represents a sixfold increase in the maximum achieved optical depth in this system.

  2. Transverse laser cooling of a thermal atomic beam of dysprosium

    SciTech Connect

    Leefer, N.; Cingoez, A.; Gerber-Siff, B.; Sharma, Arijit; Torgerson, J. R.; Budker, D.

    2010-04-15

    A thermal atomic beam of dysprosium atoms is cooled using the 4f{sup 10}6s{sup 2}(J=8){yields}4f{sup 10}6s6p(J=9) transition at 421 nm. The cooling is done via a standing light wave orthogonal to the atomic beam. Efficient transverse cooling to the Doppler limit is demonstrated for all observable isotopes of dysprosium. Branching ratios to metastable states are demonstrated to be <5x10{sup -4}. A scheme for enhancement of the nonzero-nuclear-spin-isotope cooling and a method for direct identification of possible trap states are proposed.

  3. Helium in chirped laser fields as a time-asymmetric atomic switch

    SciTech Connect

    Kaprlov-?nsk, Petra Ruth; Moiseyev, Nimrod

    2014-07-07

    Tuning the laser parameters exceptional points in the spectrum of the dressed laser helium atom are obtained. The weak linearly polarized laser couples the ground state and the doubly excited P-states of helium. We show here that for specific chirped laser pulses that encircle an exceptional point one can get the time-asymmetric phenomenon, where for a negative chirped laser pulse the ground state is transformed into the doubly excited auto-ionization state, while for a positive chirped laser pulse the resonance state is not populated and the neutral helium atoms remains in the ground state as the laser pulse is turned off. Moreover, we show that the results are very sensitive to the closed contour we choose. This time-asymmetric state exchange phenomenon can be considered as a time-asymmetric atomic switch. The optimal time-asymmetric switch is obtained when the closed loop that encircles the exceptional point is large, while for the smallest loops, the time-asymmetric phenomenon does not take place. A systematic way for studying the effect of the chosen closed contour that encircles the exceptional point on the time-asymmetric phenomenon is proposed.

  4. Helium in chirped laser fields as a time-asymmetric atomic switch.

    PubMed

    Kaprálová-Žďánská, Petra Ruth; Moiseyev, Nimrod

    2014-07-01

    Tuning the laser parameters exceptional points in the spectrum of the dressed laser helium atom are obtained. The weak linearly polarized laser couples the ground state and the doubly excited P-states of helium. We show here that for specific chirped laser pulses that encircle an exceptional point one can get the time-asymmetric phenomenon, where for a negative chirped laser pulse the ground state is transformed into the doubly excited auto-ionization state, while for a positive chirped laser pulse the resonance state is not populated and the neutral helium atoms remains in the ground state as the laser pulse is turned off. Moreover, we show that the results are very sensitive to the closed contour we choose. This time-asymmetric state exchange phenomenon can be considered as a time-asymmetric atomic switch. The optimal time-asymmetric switch is obtained when the closed loop that encircles the exceptional point is large, while for the smallest loops, the time-asymmetric phenomenon does not take place. A systematic way for studying the effect of the chosen closed contour that encircles the exceptional point on the time-asymmetric phenomenon is proposed. PMID:25005289

  5. Combined quantum-state preparation and laser cooling of a continuous beam of cold atoms

    SciTech Connect

    Di Domenico, Gianni; Devenoges, Laurent; Dumas, Claire; Thomann, Pierre

    2010-11-15

    We use two-laser optical pumping on a continuous atomic fountain in order to prepare cold cesium atoms in the same quantum ground state. A first laser excites the F=4 ground state to pump the atoms toward F=3 while a second {pi}-polarized laser excites the F=3{yields}F{sup '}=3 transition of the D{sub 2} line to produce Zeeman pumping toward m=0. To avoid trap states, we implement the first laser in a two-dimensional optical lattice geometry, thereby creating polarization gradients. This configuration has the advantage of simultaneously producing Sisyphus cooling when the optical lattice laser is tuned between the F=4{yields}F{sup '}=4 and F=4{yields}F{sup '}=5 transitions of the D{sub 2} line, which is important to remove the heat produced by optical pumping. Detuning the frequency of the second {pi}-polarized laser reveals the action of a mechanism improving both laser cooling and state-preparation efficiency. A physical interpretation of this mechanism is discussed.

  6. Quantum treatment of two-stage sub-Doppler laser cooling of magnesium atoms

    NASA Astrophysics Data System (ADS)

    Prudnikov, O. N.; Brazhnikov, D. V.; Taichenachev, A. V.; Yudin, V. I.; Bonert, A. E.; Il'enkov, R. Ya.; Goncharov, A. N.

    2015-12-01

    Deep laser cooling of 24Mg atoms has been theoretically studied. We propose a two-stage sub-Doppler cooling strategy using electrodipole transition 3 3P2→3 3D3 (λ =383.8 nm). The first stage implies exploiting magneto-optical trap with σ+ and σ- light beams, while at the second stage lin ⊥ lin molasses is used. We focus on achieving a large number of ultracold atoms (Teff<10 μ K ) in a cold-atomic cloud. The calculations have been based on quantum treatment, taking into full account the recoil effect and beyond many widely used approximations. Steady-state values of average kinetic energy and linear momentum distributions of cold atoms have been analyzed for various light-field intensities and frequency detunings. The results of conducted quantum analysis have been significantly different from the results achieved under a semiclassical approximation based on the Fokker-Planck equation. The second cooling stage allows achieving sufficiently lower kinetic energies of the atomic cloud as well as increased fraction of ultracold atoms at certain conditions compared to the first one. We hope that the obtained results can help in overcoming current experimental problems in deep cooling of 24Mg atoms by means of laser field. Cold magnesium atoms cooled in a large amount to several μ K are of huge interest to, for example, quantum metrology and to other many-body cold-atoms physics.

  7. Born-Floquet theory of laser-assisted electron-atom collisions

    SciTech Connect

    Doerr, M.; Joachain, C.J. Institut de Physique Corpusculaire, Universite de Louvain, B-1348 Louvain-la-Neuve ); Potvliege, R.M. ); Vucic, S. Institute of Physics, P.O. Box 57, 11001 Beograd )

    1994-06-01

    We present a non-Hermitian Born-Floquet theory of scattering of fast electrons by atoms in the presence of a strong monochromatic laser field. The interaction of the laser field with both the incident electron and the target atom is treated nonperturbatively, while the interaction of the incident electron with the target atom is treated in first Born approximation. Fluorescence is neglected. Detailed calculations are performed for the elastic'' scattering of 500 eV electrons by atomic hydrogen accompanied by the transfer of photons. The contribution of the entire spectrum of unperturbed atomic states to the dressing of the target is exactly taken into account by performing the calculations on a complex Sturmian basis set. In the nonresonant case, and for electric field strengths that are small with respect to the atomic unit, our Born-Floquet results are in agreement with those obtained using the semi-perturbative approach of Byron and Joachain (in which target dressing is treated in first-order perturbation theory) even at intensities where multiphoton ionization is nonperturbative. The Born-Floquet approach is particularly useful to study resonant cases, where the laser frequency matches a transition frequency in the atom. Two such situations are analyzed.

  8. Effects of laser energy and wavelength on the analysis of LiFePO₄ using laser assisted atom probe tomography

    SciTech Connect

    Santhanagopalan, Dhamodaran; Schreiber, Daniel K.; Perea, Daniel E.; Martens, Richard L.; Janssen, Yuri; Khalifah, Peter; Meng, Ying Shirley

    2014-09-21

    The effects of laser wavelength (355 nm and 532 nm) and laser pulse energy on the quantitative analysis of LiFePO₄ by atom probe tomography are considered. A systematic investigation of ultraviolet (UV, 355 nm) and green (532 nm) laser assisted field evaporation has revealed distinctly different behaviors. With the use of a UV laser, the major issue was identified as the preferential loss of oxygen (up to 10 at%) while other elements (Li, Fe and P) were observed to be close to nominal ratios. Lowering the laser energy per pulse to 1 pJ/pulse from 50 pJ/pulse increased the observed oxygen concentration to nearer its correct stoichiometry, which was also well correlated with systematically higher concentrations of ¹⁶O₂⁺ ions. Green laser assisted field evaporation led to the selective loss of Li (33% deficiency) and a relatively minor O deficiency. The loss of Li is likely a result of selective dc evaporation of Li between or after laser pulses. Comparison of the UV and green laser data suggests that the green wavelength energy was absorbed less efficiently than the UV wavelength because of differences in absorption at 355 and 532 nm for LiFePO₄. Plotting of multihit events on Saxey plots also revealed a strong neutral O₂ loss from molecular dissociation, but quantification of this loss was insufficient to account for the observed oxygen deficiency.

  9. Effects of laser energy and wavelength on the analysis of LiFePO₄ using laser assisted atom probe tomography

    DOE PAGESBeta

    Santhanagopalan, Dhamodaran; Schreiber, Daniel K.; Perea, Daniel E.; Martens, Richard L.; Janssen, Yuri; Khalifah, Peter; Meng, Ying Shirley

    2014-09-21

    The effects of laser wavelength (355 nm and 532 nm) and laser pulse energy on the quantitative analysis of LiFePO₄ by atom probe tomography are considered. A systematic investigation of ultraviolet (UV, 355 nm) and green (532 nm) laser assisted field evaporation has revealed distinctly different behaviors. With the use of a UV laser, the major issue was identified as the preferential loss of oxygen (up to 10 at%) while other elements (Li, Fe and P) were observed to be close to nominal ratios. Lowering the laser energy per pulse to 1 pJ/pulse from 50 pJ/pulse increased the observed oxygenmore » concentration to nearer its correct stoichiometry, which was also well correlated with systematically higher concentrations of ¹⁶O₂⁺ ions. Green laser assisted field evaporation led to the selective loss of Li (33% deficiency) and a relatively minor O deficiency. The loss of Li is likely a result of selective dc evaporation of Li between or after laser pulses. Comparison of the UV and green laser data suggests that the green wavelength energy was absorbed less efficiently than the UV wavelength because of differences in absorption at 355 and 532 nm for LiFePO₄. Plotting of multihit events on Saxey plots also revealed a strong neutral O₂ loss from molecular dissociation, but quantification of this loss was insufficient to account for the observed oxygen deficiency.« less

  10. Bistable Photon Emission from a Solid-State Single-Atom Laser

    NASA Astrophysics Data System (ADS)

    Lambert, Neill; Nori, Franco; Flindt, Christian

    2015-11-01

    We predict a bistability in the photon emission from a solid-state single-atom laser comprising a microwave cavity coupled to a voltage-biased double quantum dot. To demonstrate that the single-atom laser is bistable, we evaluate the photon emission statistics and show that the distribution takes the shape of a tilted ellipse. The switching rates of the bistability can be extracted from the electrical current and the shot noise in the quantum dots. This provides a means to control the photon emission statistics by modulating the electronic transport in the quantum dots. Our prediction is robust against moderate electronic decoherence and dephasing and is important for current efforts to realize single-atom lasers with gate-defined quantum dots as the gain medium.

  11. Laser supported detonation wave source of atomic oxygen for aerospace material testing

    NASA Technical Reports Server (NTRS)

    Krech, Robert H.; Caledonia, George E.

    1990-01-01

    A pulsed high-flux source of nearly monoenergetic atomic oxygen was developed to perform accelerated erosion testing of spacecraft materials in a simulated low-earth orbit (LEO) environment. Molecular oxygen is introduced into an evacuated conical expansion nozzle at several atmospheres pressure through a pulsed molecular beam valve. A laser-induced breakdown is generated in the nozzle throat by a pulsed CO2 TEA laser. The resulting plasma is heated by the ensuing laser-supported detonation wave, and then it rapidly expands and cools. An atomic oxygen beam is generated with fluxes above 10 to the 18th atoms per pulse at 8 + or - 1.6 km/s with an ion content below 1 percent for LEO testing. Materials testing yielded the same surface oxygen enrichment in polyethylene samples as observed on the STS mission, and scanning electron micrographs of the irradiated polymer surfaces showed an erosion morphology similar to that obtained on low earth orbit.

  12. Light emission induced by an XUV laser pulse interacting resonantly with atomic hydrogen

    NASA Astrophysics Data System (ADS)

    Li, Qingyi; Zhang, Zhiyuan; Zhang, Yunfeng; Li, Suyu; Guo, Fuming; Yang, Yujun

    2016-01-01

    The resonant interaction between XUV ultra-short laser pulses and atomic hydrogen is systematically studied by numerically solving the time-dependent Schrdinger equation in this paper. Triple-peak structures are found to appear in the harmonics emitted provided that the incident laser is resonant with the 1 s-2p transition of the hydrogen atom. Moreover, the energy difference between neighboring peaks is the same and turns out to be proportional to the peak field strength E 0. Based on the theory of strong field approximation, and taking the interactions of the 1 s-2p bound energy levels into consideration, theoretical interpretations of the phenomena mentioned are successfully presented. This work provides a possible approach for generating XUV radiation with a tunable frequency via the interaction between atoms and XUV laser pulses.

  13. A compact laser head with high-frequency stability for Rb atomic clocks and optical instrumentation

    NASA Astrophysics Data System (ADS)

    Affolderbach, Christoph; Mileti, Gaetano

    2005-07-01

    We present a compact and frequency-stabilized laser head based on an extended-cavity diode laser. The laser head occupies a volume of 200cm3 and includes frequency stabilization to Doppler-free saturated absorption resonances on the hyperfine components of the Rb87D2 lines at 780 nm, obtained from a simple and compact spectroscopic setup using a 2cm3 vapor cell. The measured frequency stability is ?210-12 over integration times from 1 s to 1 day and shows the potential to reach 210-13 over 102-105 s. Compact laser sources with these performances are of great interest for applications in gas-cell atomic frequency standards, atomic magnetometers, interferometers and other instruments requiring stable and narrow-band optical sources.

  14. Atomic oxygen fluorescence excitation using a Raman-shifted, tunable ArF-excimer laser

    NASA Technical Reports Server (NTRS)

    Fletcher, D. G.

    1994-01-01

    A novel method for exciting the two-photon, 2p3 3p 3P left arrow 2p4 3P atomic oxygen transition is reported. The transition to the upper state is achieved through the combined absorption of photons from the second and third Stokes order pulses of an ArF-excimer laser that is wavelength-shifted by the use of deuterium Raman cell. All three transitions from the ground electronic state of the oxygen atom lie within the tuning range of the Raman-shifted ArF laser. The available pulse energy from this laser configuration is comparable to that of commercially available Nd:YAG-pumped dye laser systems operated at 226 nm.

  15. Dynamics simulation on the interaction of intense laser pulses with atomic clusters

    NASA Astrophysics Data System (ADS)

    Du, Hong-Chuan; Zhu, Peng-Jia; Sun, Shao-Hua; Liu, Zuo-Ye; Li, Lu; Ma, Ling-Ling; Hu, Bi-Tao

    2009-06-01

    Under classical particle dynamics, the interaction process between intense femtosecond laser pulses and icosahedral noble-gas atomic clusters was studied. Our calculated results show that ionization proceeds mainly through tunnel ionization in the combined field from ions, electrons and laser, rather than the electron-impact ionization. With increasing cluster size, the average and maximum kinetic energy of the product ion increases. According to our calculation, the expansion process of the clusters after laser irradiation is dominated by Coulomb explosion and the expansion scale increases with increasing cluster size. The dependence of average kinetic energy and average charge state of the product ions on laser wavelength is also presented and discussed. The dependence of average kinetic energy on the number of atoms inside the cluster was studied and compared with the experimental data. Our results agree with the experimental results reasonably well.

  16. Efficiency of generation of highly ionised atoms under resonance absorption of CO2-laser radiation

    NASA Astrophysics Data System (ADS)

    Gus'kov, Sergei Yu; Demchenko, N. N.; Makarov, K. N.; Rozanov, Vladislav B.; Satov, Yu A.; Sharkov, Boris Yu

    2011-10-01

    We consider the generation of beams of highly ionised atoms in solid targets irradiated with CO2-laser pulses. We present experimental results on generation of Mg and Pb ions from laser plasma at a radiation flux density q ? 1014 W cm-2. We have developed a theoretical model describing the plasma heating by CO2-laser radiation at a high pulse intensity on the target, taking into account the ponderomotive forces affecting the behaviour of the interaction of light with the plasma. It is shown that in the case of resonance absorption of laser radiation by the plasma, the efficiency of generation of highly ionised atoms of the target substance is higher than the efficiency of generation in the case of classical absorption. The results of the numerical calculation by the developed model are in good agreement with the experiment.

  17. Inelastic scattering of electrons by metastable hydrogen atoms in a laser field

    NASA Astrophysics Data System (ADS)

    Buica, Gabriela

    2015-09-01

    The inelastic scattering of fast electrons by metastable hydrogen atoms in the presence of a linearly polarized laser field is theoretically studied in the domain of field intensities below 1010 W/cm2. The interaction of the hydrogen atom with the laser field is described by first-order time-dependent perturbation theory, while the projectile electrons interacting with the laser field are described by the Gordon-Volkov wave functions. An analytic expression is obtained for the differential scattering cross section in the first-order Born approximation for laser-assisted inelastic e--H (2 s ) scattering for the 2 s →n l excitation. Detailed analytical and numerical results are presented for inelastic scattering accompanied by one-photon absorption, and the angular dependence and resonance structure of the differential cross sections are discussed for the 2 s →4 l excitation of metastable hydrogen.

  18. A compact laser head with high-frequency stability for Rb atomic clocks and optical instrumentation

    SciTech Connect

    Affolderbach, Christoph; Mileti, Gaetano

    2005-07-15

    We present a compact and frequency-stabilized laser head based on an extended-cavity diode laser. The laser head occupies a volume of 200 cm{sup 3} and includes frequency stabilization to Doppler-free saturated absorption resonances on the hyperfine components of the {sup 87}Rb D{sub 2} lines at 780 nm, obtained from a simple and compact spectroscopic setup using a 2 cm{sup 3} vapor cell. The measured frequency stability is {<=}2x10{sup -12} over integration times from 1 s to 1 day and shows the potential to reach 2x10{sup -13} over 10{sup 2}-10{sup 5} s. Compact laser sources with these performances are of great interest for applications in gas-cell atomic frequency standards, atomic magnetometers, interferometers and other instruments requiring stable and narrow-band optical sources.

  19. Laser based analysis using a passively Q-switched laser employing analysis electronics and a means for detecting atomic optical emission of the laser media

    DOEpatents

    Woodruff, Steven D.; Mcintyre, Dustin L.

    2016-03-29

    A device for Laser based Analysis using a Passively Q-Switched Laser comprising an optical pumping source optically connected to a laser media. The laser media and a Q-switch are positioned between and optically connected to a high reflectivity mirror (HR) and an output coupler (OC) along an optical axis. The output coupler (OC) is optically connected to the output lens along the optical axis. A means for detecting atomic optical emission comprises a filter and a light detector. The optical filter is optically connected to the laser media and the optical detector. A control system is connected to the optical detector and the analysis electronics. The analysis electronics are optically connected to the output lens. The detection of the large scale laser output production triggers the control system to initiate the precise timing and data collection from the detector and analysis.

  20. Momentum partition between constituents of exotic atoms during laser-induced tunneling ionization

    NASA Astrophysics Data System (ADS)

    Cricchio, Dario; Fiordilino, Emilio; Hatsagortsyan, Karen Z.

    2015-08-01

    The tunneling ionization of exotic atoms such as muonic hydrogen, muonium, and positronium in a strong laser field of circular polarization is investigated, taking into account the impact of the motion of the center of mass on the the tunneling ionization dynamics. The momentum partition between the ionization products is deduced. The effect of the center-of-mass motion for the momentum distribution of the ionization components is determined. The effect scales with the ratio of the electron (muon) to the atomic core masses and is nonnegligible for exotic atoms, while being insignificant for common atoms. It is shown that the electron (muon) momentum shift during the under-the-barrier motion due to the magnetically induced Lorentz force has a significant impact on the momentum distribution of the atomic core and depends on the ratio of the electron to the atomic core masses.

  1. Clock Technology Development in the Laser Cooling and Atomic Physics (LCAP) Program

    NASA Technical Reports Server (NTRS)

    Seidel, Dave; Thompson, R. J.; Klipstein, W. M.; Kohel, J.; Maleki, L.

    2000-01-01

    This paper presents the Laser Cooling and Atomic Physics (LCAP) program. It focuses on clock technology development. The topics include: 1) Overview of LCAP Flight Projects; 2) Space Clock 101; 3) Physics with Clocks in microgravity; 4) Space Clock Challenges; 5) LCAP Timeline; 6) International Space Station (ISS) Science Platforms; 7) ISS Express Rack; 8) Space Qualification of Components; 9) Laser Configuration; 10) Clock Rate Comparisons: GPS Carrier Phase Frequency Transfer; and 11) ISS Model Views. This paper is presented in viewgraph form.

  2. Locking of dye-laser radiation spectrum onto atomic absorption lines of an impulsive discharge plasma

    SciTech Connect

    Burakov, V.S.; Zhukovskii, V.V.; Isaevich, A.V.

    1987-08-01

    The authors study the characteristics of the formation of the radiation spectrum of a dye laser with the help of resonance phase-polarization methods with the use of an impulsive discharge plasma, enriched with atoms of the material to whose spectral absorption lines the laser radiation frequency is locked, in the absorbing cell of the resonator. Copper monoiodide is used as a test plasma.

  3. Experimental search for the electron electric dipole moment with laser cooled francium atoms

    NASA Astrophysics Data System (ADS)

    Inoue, T.; Ando, S.; Aoki, T.; Arikawa, H.; Ezure, S.; Harada, K.; Hayamizu, T.; Ishikawa, T.; Itoh, M.; Kato, K.; Kawamura, H.; Uchiyama, A.; Aoki, T.; Asahi, K.; Furukawa, T.; Hatakeyama, A.; Hatanaka, K.; Imai, K.; Murakami, T.; Nataraj, H. S.; Sato, T.; Shimizu, Y.; Wakasa, T.; Yoshida, H. P.; Yoshimi, A.; Sakemi, Y.

    2015-04-01

    A laser cooled heavy atom is one of the candidates to search for the permanent electric dipole moment (EDM) of the electron due to the enhancement mechanism and its long coherence time. The laser cooled francium (Fr) factory has been constructed to perform the electron EDM search at the Cyclotron and Radioisotope Center, Tohoku University. The present status of Fr production and the EDM measurement system is presented.

  4. Evolution of dark state of an open atomic system in constant intensity laser field

    SciTech Connect

    Krmpot, A. J.; Radonjic, M.; Cuk, S. M.; Nikolic, S. N.; Grujic, Z. D.; Jelenkovic, B. M.

    2011-10-15

    We studied experimentally and theoretically the evolution of open atomic systems in the constant intensity laser field. The study is performed by analyzing the line shapes of Hanle electromagnetically induced transparency (EIT) obtained in different segments of a laser beam cross section of constant intensity, i.e., a {Pi}-shaped laser beam. Such Hanle EIT resonances were measured using a small movable aperture placed just in front of the photodetector, i.e., after the entire laser beam had passed through the vacuum Rb cell. The laser was locked to the open transition F{sub g}=2{yields}F{sub e}=1 at the D{sub 1} line of {sup 87}Rb with laser intensities between 0.5 and 4 mW/cm{sup 2}. This study shows that the profile of the laser beam determines the processes governing the development of atomic states during the interaction. The resonances obtained near the beam center are narrower than those obtained near the beam edge, but the significant changes of the linewidths occur only near the beam edge, i.e., right after the atom enters the beam. The Hanle EIT resonances obtained near the beam center exhibit two pronounced minima next to the central maximum. The theoretical model reveals that the occurrence of these transmission minima is a joint effect of the preparation of atoms into the dark state and the optical pumping into the uncoupled ground level F{sub g}=1. The appearance of the transmission minima, although similar to that observed in the wings of a Gaussian beam [A. J. Krmpot et al., Opt. Express 17, 22491 (2009)], is of an entirely different nature for the {Pi}-shaped laser beam.

  5. New energy levels of atomic niobium by laser induced fluorescence spectroscopy in the near infrared

    NASA Astrophysics Data System (ADS)

    ztrk, I. K.; Ba?ar, G; Er, A.; Gzelimen, F.; Ba?ar, G; Krger, S.

    2015-01-01

    Laser-induced fluorescence spectroscopy was applied in order to find new energy levels of the niobium atom. A continuous wave tuneable titanium-sapphire laser in the wavelength range from 750 to 865 nm and a hollow-cathode lamp were used. We discovered four energy levels of even parity, three lying levels below 19 000 cm-1 and one at much higher energy. Additionally hyperfine structure data of six levels of odd parity were determined.

  6. Experimental demonstration of a diode laser-excited optical filter in atomic Rb vapor

    SciTech Connect

    Chung, Y.C.; Shay, T.M.

    1988-05-01

    The authors report the first demonstration of a narrow bandwidth optical filter using diode laser-pumped atomic Rb vapor. Excellent rejection of off-resonant laser photons has been achieved. The measured detection bandwidth was 1.18 GHz at the Rb cell temperature of 150/sup 0/C, which shows a good agreement with the calculated detection bandwidth of 1.02 GHz.

  7. Quasistatic limit of the strong-field approximation describing atoms in intense laser fields: Circular polarization

    SciTech Connect

    Bauer, Jaroslaw H.

    2011-03-15

    In the recent work of Vanne and Saenz [Phys. Rev. A 75, 063403 (2007)] the quasistatic limit of the velocity gauge strong-field approximation describing the ionization rate of atomic or molecular systems exposed to linearly polarized laser fields was derived. It was shown that in the low-frequency limit the ionization rate is proportional to the laser frequency {omega} (for a constant intensity of the laser field). In the present work I show that for circularly polarized laser fields the ionization rate is proportional to {omega}{sup 4} for H(1s) and H(2s) atoms, to {omega}{sup 6} for H(2p{sub x}) and H(2p{sub y}) atoms, and to {omega}{sup 8} for H(2p{sub z}) atoms. The analytical expressions for asymptotic ionization rates (which become nearly accurate in the limit {omega}{yields}0) contain no summations over multiphoton contributions. For very low laser frequencies (optical or infrared) these expressions usually remain with an order-of-magnitude agreement with the velocity gauge strong-field approximation.

  8. Lithium atomic beam spectroscopy and phase sensitive detection using a diode laser

    NASA Astrophysics Data System (ADS)

    Houlton, Jack; Peplinski, Brandon; Otto, Lauren; Klemme, Daniel; Greenlee, Tom; Hoyt, Chad

    2011-04-01

    We describe spectroscopy of a collimated lithium atomic beam using a home-built external cavity diode laser (ECDL) at 671 nm. The atomic beam is formed from an effusive oven containing Li at T ~ 450C and a series of apertures. The ECDL light is split into two beams that counter-propagate at right angles to the atomic beam. Fluorescence spectra from the unresolved 2S1/2 F = 2 --> 2P3/2 D2 line of 7Li were recorded over a large range of saturation parameters (0.1s0 - 50s0, where s0 is the ratio of laser intensity to the saturation intensity). We modeled the effects of transverse atomic velocities (residual Doppler broadening), power broadening, and the saturation feature at high s0. We calibrated the spectra by modulating the laser current at ~ 110 MHz and observing the sideband spectra. We locked the frequency of the ECDL to the transition at low and high values of s0 by phase sensitive detection in the fluorescence. The laser beam was electro-optically modulated at 100 kHz and the fluorescence signal was demodulated with a lock-in amplifier. The locked ECDL will be used for laser cooling and trapping experiments. Funding from MN NASA Space Grant Consortium and CID, Inc.

  9. Exotic hollow atom states pumped by relativistic laser plasma in a radiation dominant regime

    NASA Astrophysics Data System (ADS)

    Woolsey, Nigel; Pikuz, S. A.; Faenov, A. Ya; Dance, R. J.; Wagenaars, E.; Booth, N.; Culfa, O.; Evans, R. G.; Gray, R. J.; Kaempfer, T.; Lancaster, K. L.; McKenna, P.; Rossall, A. L.; Skobelev, I. Yu; Schulze, K. S.; Uschmann, I.; Zhidkov, A. G.; Abdallah, J., Jr.; Colgan, J.

    2013-10-01

    In high-spectral resolution experiments with the petawatt Vulcan laser, strong x-ray radiation of KK hollow atoms (atoms without n = 1 electrons) from aluminium targets was observed at high laser contrast, for intensities of 3 1020 Wcm-2 and micron thick targets. These spectral observations are interpreted using detailed atomic kinetics calculations suggesting these exotic hollow atom states occur at near solid density and are driven by an intense polychromatic x-ray field. We estimate that this x-ray radiation field has energy in the kilovolt range and has an intensity exceeding 1018 Wcm-2. The field may arise through relativistic electron Thomson scattering and bremsstrahlung in the electrostatic fields at the target surface.

  10. Dynamics of coherent accumulation in cold atoms probed by a femtosecond laser

    NASA Astrophysics Data System (ADS)

    Marian, Adela; Stowe, Matthew C.; Felinto, Daniel; Ye, Jun

    2004-05-01

    We are using a phase-stabilized femtosecond laser comb to investigate two-photon transitions in laser cooled Rb atoms. The bandwidth associated with the femtosecond pulse is sufficiently wide to allow exploration of a large number of atomic states in a single pulse. The time delay between successive pulses is tuned so as to create an optical frequency comb structure with appropriate components in resonance with single-photon enhanced two-photon transitions. This enables one to conduct high-resolution spectroscopy over a broad bandwidth, with the prospect of studying coherent accumulation of population in this multilevel system. We are currently investigating the population transfer among the relevant atomic states. The experimental observations are in good agreement with a theory using the Bloch equations to describe the time evolution of all the relevant levels. Measurement of atomic structure in a global and precise manner will also be reported.

  11. Influence of atomic modeling on integrated simulations of laser-produced Au plasmas

    NASA Astrophysics Data System (ADS)

    Frank, Yechiel; Raicher, Erez; Ehrlich, Yosi; Hurvitz, Gilad; Shpilman, Zeev; Fraenkel, Moshe; Zigler, Arie; Henis, Zohar

    2015-11-01

    Time-integrated x-ray emission spectra of laser-irradiated Au disks were recorded using transmission grating spectrometry, at laser intensities of 1013 to 1014W/cm2 . Radiation-hydrodynamics and atomic physics calculations were used to simulate the emitted spectra. Three major plasma regions can be recognized: the heat wave, the corona, and an intermediate region connecting them. An analysis of the spectral contribution of these three plasma regions to the integrated recorded spectrum is presented. The importance of accurate atomic modeling of the intermediate plasma region, between the corona and the heat wave, is highlighted. The influence of several aspects of the atomic modeling is demonstrated, in particular multiply-excited atomic configurations and departure from local thermal equilibrium.

  12. Differential cross sections for ionization of laser-aligned atoms by electron impact.

    PubMed

    Nixon, Kate L; Murray, Andrew James

    2011-03-25

    The first experimental data are given for (e,2e) ionization from laser-aligned atoms. A linearly polarized laser excited Mg atoms to the 3¹P₁ state prior to ionization by low energy electrons. The scattered and ejected electrons were detected in coincidence and the differential cross section determined for a range of alignment angles. An asymmetric coplanar geometry was used, with one electron fixed and the other detected at different angles. The data are compared to that from the spherically symmetric 3¹S₀ state. Significant differences are found, in both magnitude and angular distribution. PMID:21517314

  13. q-deformed model of nonclassical quantum-statistical behaviour for an atom laser

    NASA Astrophysics Data System (ADS)

    Haghshenasfard, Zahra; Cottam, Michael G.

    2013-09-01

    Theoretical studies are reported for the quantum dynamical and statistical properties of an atom laser. The model is based on the generalized deformed oscillator algebra in which the field radiation operators are deformed by an operator-valued function f( N) of the photon number N. The Hamiltonian of the system is solved analytically under the rotating wave approximation. In particular, it is shown that the nonlinearity introduced by q-deformation leads to quadrature squeezing effects and a sub-Poisson distribution for the atom laser beam.

  14. Influence of the wavelength on the spatial resolution of pulsed-laser atom probe

    SciTech Connect

    Gault, B.; Chen, Y. M.; Hono, K.; Moody, M. P.; Ringer, S. P.; Ohkubo, T.

    2011-11-01

    Modern atom probes typically incorporate an ultrafast pulsed-laser source with wavelength ranging from infrared (IR) to ultraviolet (UV) depending on the specific instrument. In order to estimate the influence of the wavelength on the accuracy of the technique, the achievable in-depth spatial resolution has been measured for atom probe analyses of the same pure W specimen using three different wavelengths and across a range of laser pulse energies. UV illumination is shown to yield superior spatial resolution to both IR and visible (green) wavelengths. We propose that this improvement relates to a faster decay of temperature enabled by light absorption confined to the near apex region.

  15. A laser frequency and power control system in an atomic Talbot-Lau interferometer

    NASA Astrophysics Data System (ADS)

    Yang, Ting; Hu, Zhaohui; Qi, Lu

    2013-12-01

    The importance of atom interferometers that have high sensitivity and super precision is well recognized in the fields of rotation sensing, inertial and gravitational forces sensing, relativity tests, and other precision measures. So many researchers are absorbed in atom interferometers. An atom interferometer consists of many parts, among of which optical part plays a significant role because of the need of laser beams in every parts. Based on this situation and some specific quantitive requirements to laser beams, this article presents a laser frequency and power control system for atom interferometer which can realize the functions of frequency shift and scan, power stabilization and modulation, and highspeed switch. The system lies on acousto-optical modulators (AOM) and a phase-locked loop frequency synthesizer is designed in the system as a very important part which has wide capture range of frequency and well stability. The experimental results show that the designed system is available and the performances of laser through AOM are as good as expected and the phase noise of the output is restrained. In addition, the system also could be used in other instruments and devices, such as atomic clock, gravimeter, gradiometer, and gyroscope.

  16. Theory of x-ray absorption by laser-dressed atoms.

    SciTech Connect

    Buth, C.; Santra, R.; Chemistry

    2007-03-23

    An ab initio theory is devised for the x-ray photoabsorption cross section of atoms in the field of a moderately intense optical laser (800 nm, 10{sup 13} W/cm{sup 2}). The laser dresses the core-excited atomic states, which introduces a dependence of the cross section on the angle between the polarization vectors of the two linearly polarized radiation sources. We use the Hartree-Fock-Slater approximation to describe the atomic many-particle problem in conjunction with a nonrelativistic quantum-electrodynamic approach to treat the photon-electron interaction. The continuum wave functions of ejected electrons are treated with a complex absorbing potential that is derived from smooth exterior complex scaling. The solution to the two-color (x-ray plus laser) problem is discussed in terms of a direct diagonalization of the complex symmetric matrix representation of the Hamiltonian. Alternative treatments with time-independent and time-dependent non-Hermitian perturbation theories are presented that exploit the weak interaction strength between x rays and atoms. We apply the theory to study the photoabsorption cross section of krypton atoms near the K edge. A pronounced modification of the cross section is found in the presence of the optical laser.

  17. Atom laser based on four-wave mixing with Bose-Einstein condensates in nonlinear lattices

    NASA Astrophysics Data System (ADS)

    Wasak, T.; Konotop, V. V.; Trippenbach, M.

    2013-12-01

    Optical lattices are typically used to modify the dispersion relation of the matter wave, in particular, to ensure resonant conditions for multiwave interactions. Here we propose an alternative mechanism of wave interactions. It can be implemented using a nonlinear lattice and modifies the momentum conservation law of the interacting atoms, leaving the energy conservation unchanged. We propose to apply this phenomenon to construct an atom laser via a resonant four-wave mixing process.

  18. Stability diagram of the collective atomic recoil laser with thermal atoms

    NASA Astrophysics Data System (ADS)

    Tomczyk, H.; Schmidt, D.; Georges, C.; Slama, S.; Zimmermann, C.

    2015-06-01

    We experimentally investigate cold thermal atoms in a single sidedly pumped optical ring resonator for temperatures between 0.4 and 9 μ K . The threshold for collective atomic recoil lasing (CARL) is recorded for various pump-cavity detunings. The resulting stability diagram is interpreted by simulating the classical CARL equations. We find that the stability diagram for thermal atoms shows the same asymmetry as observed for Bose-Einstein condensates in previous experiments. Whereas for condensates the asymmetry is well explained by a Dicke-type quantum model we here discuss a simplified classical model. It complements the quantum model and provides an intuitive explanation based on the change in the long-range atomic interaction with pump-cavity detuning.

  19. Control of atomic transition rates via laser-light shaping

    NASA Astrophysics Data System (ADS)

    Jáuregui, R.

    2015-04-01

    A modular systematic analysis of the feasibility of modifying atomic transition rates by tailoring the electromagnetic field of an external coherent light source is presented. The formalism considers both the center of mass and internal degrees of freedom of the atom, and all properties of the field: frequency, angular spectrum, and polarization. General features of recoil effects for internal forbidden transitions are discussed. A comparative analysis of different structured light sources is explicitly worked out. It includes spherical waves, Gaussian beams, Laguerre-Gaussian beams, and propagation invariant beams with closed analytical expressions. It is shown that increments in the order of magnitude of the transition rates for Gaussian and Laguerre-Gaussian beams, with respect to those obtained in the paraxial limit, require waists of the order of the wavelength, while propagation invariant modes may considerably enhance transition rates under more favorable conditions. For transitions that can be naturally described as modifications of the atomic angular momentum, this enhancement is maximal (within propagation invariant beams) for Bessel modes, Mathieu modes can be used to entangle the internal and center-of-mass involved states, and Weber beams suppress this kind of transition unless they have a significant component of odd modes. However, if a recoil effect of the transition with an adequate symmetry is allowed, the global transition rate (center of mass and internal motion) can also be enhanced using Weber modes. The global analysis presented reinforces the idea that a better control of the transitions between internal atomic states requires both a proper control of the available states of the atomic center of mass, and shaping of the background electromagnetic field.

  20. Electron ionization and spin polarization control of Fe atom adsorbed graphene irradiated by a femtosecond laser

    NASA Astrophysics Data System (ADS)

    Yu, Dong; Jiang, Lan; Wang, Feng; Li, Xin; Qu, Liangti; Lu, Yongfeng

    2015-10-01

    We investigate the structural properties and ionized spin electrons of an Fe-graphene system, in which the time-dependent density functional theory (TDDFT) within the generalized gradient approximation is used. The electron dynamics, including electron ionization and ionized electron spin polarization, is described for Fe atom adsorbed graphene under femtosecond laser irradiation. The theoretical results show that the electron ionization and ionized electron spin polarization are sensitive to the laser parameters, such as the incident angle and the peak intensity. The spin polarization presents the maximum value under certain laser parameters, which may be used as a source of spin-polarized electrons.

  1. Calibrating laser beam deflection systems for use in atomic force microscopes and cantilever sensors

    SciTech Connect

    Beaulieu, L.Y.; Godin, Michel; Laroche, Olivier; Tabard-Cossa, Vincent; Gruetter, Peter

    2006-02-20

    Most atomic force microscopes and cantilever-based sensors use an optical laser beam detection system to monitor cantilever deflections. We have developed a working model that accurately describes the way in which a position sensitive photodetector interprets the deflection of a cantilever in these instruments. This model exactly predicts the numerical relationship between the measured photodetector signal and the actual cantilever deflection. In addition, the model is used to optimize the geometry of such laser deflection systems, which greatly simplifies the use of any cantilever-based instrument that uses a laser beam detection system.

  2. Compact extended-cavity diode laser for atomic spectroscopy and metrology

    NASA Astrophysics Data System (ADS)

    Vassiliev, V. V.; Zibrov, S. A.; Velichansky, V. L.

    2006-01-01

    We report on a compact, inexpensive, and durable extended-cavity diode laser (ECDL) of an original mechanical concept. The independent temperature control of a laser diode and an extended cavity provides a low-frequency drift. The linewidth of a few hundred kilohertz was measured by taking a beating of two identical ECDLs. The continuous tuning range of about 1 is achieved by the synchronous scan of two piezotransducers translating and rotating an external diffraction grating. The laser has been used in high-resolution spectroscopy, atom cooling, metrology, and precise interferometry.

  3. Study of transitions in thulium atoms in the 410-420-nm range for laser cooling

    SciTech Connect

    Akimov, A V; Chebakov, K Yu; Tolstikhina, I Yu; Sokolov, A V; Rodionov, P B; Kanorsky, S I; Sorokin, V N; Kolachevsky, N N

    2008-10-31

    The possibility of laser cooling of thulium atoms is considered. The hyperfine structure of almost cyclic 4f{sup 13}6s{sup 2} (J{sub g} = 7/2) {r_reversible} 4f{sup 12}5d{sub 3/2}6s{sup 2} (J{sub e} = 9/2) and 4f{sup 13}6s{sup 2} (J{sub g} = 7/2) {r_reversible} 4f{sup 12}5d{sub 5/2}6s{sup 2} (J{sub e} = 9/2) transitions at 410.6 and 420.4 nm, respectively, is studied by the method of sub-Doppler saturation spectroscopy in counterpropagating laser beams. The hyperfine splitting of excited levels involved in these transitions is measured and the natural linewidths of these transitions are determined. The structure of the neighbouring 4f{sup 13}6s6p (J{sub e} = 5/2) and 4f{sup 12}5d{sub 5/2}6s{sup 2} (J{sub e} = 7/2) levels is studied for the first time by this method. The decay probabilities of the J{sub e} = 9/2 levels via channels removing atoms from the cooling cycle are calculated. It is found that the branching ratio for the strong transition at 410.6 nm (A = 6x10{sup 7} s{sup -1}) is smaller than 2x10{sup -5}, which makes this transition most promising for laser cooling. The laser cooling of atoms in a Zeeman cooler at this transition is simulated. The possibility of using a laser-cooled cloud of thulium atoms to study the metrological transition at 1.14 {mu}m is discussed. (laser cooling of atoms)

  4. Atomic vapor laser isotope separation of lead-210 isotope

    DOEpatents

    Scheibner, Karl F.; Haynam, Christopher A.; Johnson, Michael A.; Worden, Earl F.

    1999-01-01

    An isotopically selective laser process and apparatus for removal of Pb-210 from natural lead that involves a one-photon near-resonant, two-photon resonant excitation of one or more Rydberg levels, followed by field ionization and then electrostatic extraction. The wavelength to the near-resonant intermediate state is counter propagated with respect to the second wavelength required to populate the final Rydberg state. This scheme takes advantage of the large first excited state cross section, and only modest laser fluences are required. The non-resonant process helps to avoid two problems: first, stimulated Raman Gain due to the nearby F=3/2 hyperfine component of Pb-207 and, second, direct absorption of the first transition process light by Pb-207.

  5. Atomic vapor laser isotope separation of lead-210 isotope

    DOEpatents

    Scheibner, K.F.; Haynam, C.A.; Johnson, M.A.; Worden, E.F.

    1999-08-31

    An isotopically selective laser process and apparatus for removal of Pb-210 from natural lead that involves a one-photon near-resonant, two-photon resonant excitation of one or more Rydberg levels, followed by field ionization and then electrostatic extraction. The wavelength to the near-resonant intermediate state is counter propagated with respect to the second wavelength required to populate the final Rydberg state. This scheme takes advantage of the large first excited state cross section, and only modest laser fluences are required. The non-resonant process helps to avoid two problems: first, stimulated Raman Gain due to the nearby F=3/2 hyperfine component of Pb-207 and, second, direct absorption of the first transition process light by Pb-207. 5 figs.

  6. Rescattering and frustrated tunneling ionization of atoms in circularly polarized laser fields

    NASA Astrophysics Data System (ADS)

    Li, Min; Qin, Liang; Wu, Chengyin; Peng, Liangyou; Gong, Qihuang; Liu, Yunquan

    2014-01-01

    We investigate strong-field ionization dynamics of atoms in circularly polarized laser fields by a three-dimensional electron ensemble method which is validated by comparison with ab initio results of solving the time-dependent Schrödinger equation. We show that the Coulomb potential and the electron recollision play very crucial roles for single ionization of atoms with a lower ionization potential in circularly polarized laser fields. We find that the critical laser field strength for recollision scales as F0˜2ln10ω2/√2Ip (Ip, ionization potential; ω , laser frequency), below which the rescattering is very crucial. As a consequence of recollision, a large amount of tunneled electrons will be ejected into the elliptical orbits of Rydberg states or strongly rescattered off the nucleus and eventually achieve large energy from laser fields. The characteristic feature is that both the relative frustrated tunneling rate and the hard rescattering rate decrease with increasing the laser intensity and the wavelength. This study sheds a light on those processes that are closely related with electron rescattering in circularly polarized laser fields, e.g., high-order harmonic generation and nonsequential double ionization.

  7. Velocity and electronic state distributions of sputtered Fe atoms by laser-induced fluorescence spectroscopy

    SciTech Connect

    Young, C.E.; Calaway, W.F.; Pellin, M.J.; Gruen, D.M.

    1983-01-01

    Velocity distributions and relative populations in the fine-structure levels of the a/sup 5/D/sub J/ ground state of Fe atoms, produced by sputtering with 3 keV argon ions, have been investigated by Doppler shifted laser induced fluorescence. The laser system employs a single-mode, scanning ring dye laser, amplified by a sequence of three excimer-pumped flowing-dye cells. Frequency doubling in a KD*P crystal was used to produce high energy (> .5 mJ) pulses of narrowband tunable UV output near 300 nm. Laser power influence on effective velocity bandwidth was investigated. Favorable light-collection geometry minimized distortion of the velocity spectra from apparatus-averaging effects. In impurity flux diagnostic applications in fusion devices, substantial spatial averaging may occur. In the latter case, the narrow velocity bandwidth (70 m/s, transform limit) of the present laser system is particularly useful.

  8. Velocity and electronic state distributions of sputtered Fe atoms by laser-induced fluorescence spectroscopy

    SciTech Connect

    Young, C.E.; Calaway, W.F.; Pellin, M.J.; Gruen, D.M.

    1984-04-01

    Velocity distributions and relative populations in the fine-structure levels of the a /sup 5/D/sub J/ ground state of Fe atoms, produced by sputtering with 3 keV argon ions, have been investigated by Doppler-shifted laser-induced fluorescence. The laser system employs a single-mode, scanning ring dye laser, amplified by a sequence of three excimer-pumped flowing dye cells. Frequency doubling in a KD*P crystal was used to produce high energy (>0.5 mJ) pulses of narrowband tunable UV output near 300 nm. Laser power influence on effective velocity bandwidth was investigated. Favorable light-collection geometry minimized distortion of the velocity spectra from apparatus-averaging effects. In impurity flux diagnostic applications in fusion devices, substantial spatial averaging may occur. In the latter case, the narrow velocity bandwidth (70 m/s, transform limit) of the present laser system is particularly useful.

  9. Narrow bandwidth interference filter-stabilized diode laser systems for the manipulation of neutral atoms

    NASA Astrophysics Data System (ADS)

    Gilowski, M.; Schubert, Ch.; Zaiser, M.; Herr, W.; Wbbena, T.; Wendrich, T.; Mller, T.; Rasel, E. M.; Ertmer, W.

    2007-12-01

    We present and investigate different external cavity diode laser (ECDL) configurations for the manipulation of neutral atoms, wavelength-stabilized by a narrow-band high transmission interference filter. A novel diode laser, providing high output power of more than 1 W, with a linewidth of less than 85 kHz, based on a self-seeded tapered amplifier chip has been developed. Additionally, we compare the optical and spectral properties of two laser systems based on common laser diodes, differing in their coating, as well as one, based on a distributed-feedback (DFB) diode. The linear cavity setup in all these systems combines a robust and compact design with a high wavelength tunability and an improved stability of the optical feedback compared to diode laser setups using diffraction gratings for wavelength discrimination.

  10. Heteronuclear ionizing collisions between laser-cooled metastable helium atoms

    SciTech Connect

    McNamara, J. M.; Stas, R. J. W.; Hogervorst, W.; Vassen, W.

    2007-06-15

    We have investigated cold ionizing heteronuclear collisions in dilute mixtures of metastable (2 {sup 3}S{sub 1}) {sup 3}He and {sup 4}He atoms, extending our previous work on the analogous homonuclear collisions [R. J. W. Stas et al., Phys. Rev. A 73, 032713 (2006)]. A simple theoretical model of such collisions enables us to calculate the heteronuclear ionization rate coefficient, for our quasiunpolarized gas, in the absence of resonant light (T=1.2 mK): K{sub 34}{sup (th)}=2.4x10{sup -10} cm{sup 3}/s. This calculation is supported by a measurement of K{sub 34} using magneto-optically trapped mixtures containing about 1x10{sup 8} atoms of each species, K{sub 34}{sup (exp)}=2.5(8)x10{sup -10} cm{sup 3}/s. Theory and experiment show good agreement.

  11. Surface diffusion limitation in laser focused atomic deposition

    NASA Astrophysics Data System (ADS)

    Behringer, R. E.; Natarajan, Vasant; Timp, G.

    1996-09-01

    We have previously demonstrated that an optical standing wave can be used to focus a neutral atomic beam into a structure which is deposited on a substrate, under conditions that are compatible with molecular beam epitaxy. We have made structures in sodium with linewidths of ? ? 45 nm and contrast better than 10:1. Here, we observe that the condition of the surface prior to deposition is critical in producing these features. With certain surface conditions, apparently the mobility of the atoms on the surface reduces the contrast of the grating to approximately 1:1. We discuss the condition necessary during deposition to insure that the resolution of the deposited features is retained.

  12. The interaction of 193-nm excimer laser irradiation with single-crystal zinc oxide: Neutral atomic zinc and oxygen emission

    SciTech Connect

    Kahn, E. H.; Langford, S. C.; Dickinson, J. T.; Boatner, Lynn A

    2013-01-01

    We report mass-resolved time-of-flight measurements of neutral particles from the surface of single-crystal ZnO during pulsed 193-nm irradiation at laser fluences below the threshold for avalanche breakdown. The major species emitted are atomic Zn and O. We examine the emissions of atomic Zn as a function of laser fluence and laser exposure. Defects at the ZnO surface appear necessary for the detection of these emissions. Our results suggest that the production of defects is necessary to explain intense sustained emissions at higher fluence. Rapid, clean surface etching and high atomic zinc kinetic energies seen at higher laser fluences are also discussed.

  13. Laser-induced fluorescence of metal-atom impurities in a neutral beam

    SciTech Connect

    Burrell, C.F.; Pyle, R.V.; Sabetimani, Z.; Schlachter, A.S.

    1984-10-01

    The need to limit impurities in fusion devices to low levels is well known. We have investigated, by the technique of laser-induced fluorescence, the concentration of heavy-metal atoms in a neutral beam caused by their evaporation from the hot filaments in a conventional high-current multifilament hydrogen-ion source.

  14. Photoelectron momentum spectra for multiphoton ionization of Hydrogen atoms by intense laser pulses

    NASA Astrophysics Data System (ADS)

    Ovchinnikov, Serge; Macek, Joseph

    2007-06-01

    Full three-dimensional electron momentum distribution for multiphoton ionization of Hydrogen atoms by intense laser pulses are calculated by solving the time-dependent solutions of Schr"odinger equation on a three-dimensional lattice in a scaled coordinate representation (CSLTDSE). This approach allows one to circumvent many difficulties related to the propagation of wave function to macroscopic distances.

  15. Theory of multiphoton ionization of atoms by strong, short pulsed lasers

    SciTech Connect

    Kulander, K.C.

    1987-07-10

    A numerical technique for investigating the behavior of many electron atoms in intense laser fields is presented. A description of the method is followed by results of an illustrative, application to helium for a number of wavelengths and intensities. A discussion of high order ionization dynamics for this system based on these calculations is provided. 10 refs.

  16. Mechanical effect of retroreflected frequency-chirped laser pulses on two-level atoms

    SciTech Connect

    Demeter, G.; Djotyan, G. P.; Soerlei, Zs.; Bakos, J. S.

    2006-07-15

    We discuss the mechanical momentum transfer to two-level atoms by a pair of short, counterpropagating, frequency-chirped laser pulses, which partially overlap each other in the atomic medium. We show that such a pulse pair can induce a much greater change of momentum than pulses that do not overlap (interact separately with the atoms). The dispersive effect on the atomic velocity distribution is shown to be much smaller for the case of overlapping pulses. Furthermore, there are regimes where the method is not sensitive to the exact values of the pulse parameters or the initial velocity distribution. The interaction can be repeated for a cumulative effect, so a sequence of such pulse pairs can be used very effectively to manipulate the mechanical motion of atoms.

  17. Atomic oxygen effects on thin film space coatings studied by spectroscopic ellipsometry, atomic force microscopy, and laser light scattering

    NASA Technical Reports Server (NTRS)

    Synowicki, R. A.; Hale, Jeffrey S.; Woollam, John A.

    1992-01-01

    The University of Nebraska is currently evaluating Low Earth Orbit (LEO) simulation techniques as well as a variety of thin film protective coatings to withstand atomic oxygen (AO) degradation. Both oxygen plasma ashers and an electron cyclotron resonance (ECR) source are being used for LEO simulation. Thin film coatings are characterized by optical techniques including Variable Angle Spectroscopic Ellipsometry, Optical spectrophotometry, and laser light scatterometry. Atomic Force Microscopy (AFM) is also used to characterize surface morphology. Results on diamondlike carbon (DLC) films show that DLC degrades with simulated AO exposure at a rate comparable to Kapton polyimide. Since DLC is not as susceptible to environmental factors such as moisture absorption, it could potentially provide more accurate measurements of AO fluence on short space flights.

  18. Quantum-mechanical theory including angular momenta analysis of atom-atom collisions in a laser field

    NASA Technical Reports Server (NTRS)

    Devries, P. L.; George, T. F.

    1978-01-01

    The problem of two atoms colliding in the presence of an intense radiation field, such as that of a laser, is investigated. The radiation field, which couples states of different electronic symmetry, is described by the number state representation while the electronic degrees of freedom (plus spin-orbit interaction) are discussed in terms of a diabatic representation. The total angular momentum of the field-free system and the angular momentum transferred by absorption (or emission) of a photon are explicitly considered in the derivation of the coupled scattering equations. A model calculation is discussed for the Xe + F collision system.

  19. Accurate measurement of tunneling ionization rates of atoms in a high-intensity laser field

    NASA Astrophysics Data System (ADS)

    Buerke, Brian Joseph

    2000-08-01

    Tunneling ionization of noble gas atoms is important for understanding the physics of strongly driven atoms and for developing new technologies such as ultrafast coherent x-ray sources and laser-based electron accelerators. Measurements of tunneling rates for atoms ionized by a high-intensity laser pulse have achieved a factor-of-ten improvement in accuracy over previous experiments, providing unprecedented detail about high- intensity laser-atom interactions. The measurements employ a circularly polarized, 2-ps, 1053-nm laser pulse with a peak intensity of 1.5 1017 W/cm2 to ionize low charge states of helium and neon. Under these conditions, electrons produced during ionization are ponderomotively scattered out of the laser focus and gain an amount of energy proportional to the intensity at the moment of ionization. The measured electron energy (0-4 keV) is insensitive to variations in the peak laser intensity, allowing the ionizing electric fields to be determined with an accuracy better than 2%. Detailed Monte Carlo simulations of electron motion in the focus, which calibrate the ionizing fields to the electron energies, confirm the accuracy of the measurements. The inferred ionization rates provide rigorous tests of available tunneling theories. The helium data show excellent agreement with the semiclassical theory of Ammosov, Delone, and Krainov (ADK). The results for hydrogenic helium (He1+), in particular, agree well with analytic and numerical solutions of the Schrdinger equation. The measurements verify both the importance of the long-range nature of the Coulomb potential and the effect of multielectron interactions in determining the ionization rate. The neon data show a small but significant breakdown of the ADK theory, which is attributed to polarization of the atom by the laser field prior to ionization. Atom polarization may imply that tunneling ionization intensities are described by a universal scaling relation. The neon data also provide tentative evidence for the DC Stark shift of the atomic ground state and its effect on tunneling ionization rates.

  20. Acceleration of neutral atoms in strong short-pulse laser fields.

    PubMed

    Eichmann, U; Nubbemeyer, T; Rottke, H; Sandner, W

    2009-10-29

    A charged particle exposed to an oscillating electric field experiences a force proportional to the cycle-averaged intensity gradient. This so-called ponderomotive force plays a major part in a variety of physical situations such as Paul traps for charged particles, electron diffraction in strong (standing) laser fields (the Kapitza-Dirac effect) and laser-based particle acceleration. Comparably weak forces on neutral atoms in inhomogeneous light fields may arise from the dynamical polarization of an atom; these are physically similar to the cycle-averaged forces. Here we observe previously unconsidered extremely strong kinematic forces on neutral atoms in short-pulse laser fields. We identify the ponderomotive force on electrons as the driving mechanism, leading to ultrastrong acceleration of neutral atoms with a magnitude as high as approximately 10(14) times the Earth's gravitational acceleration, g. To our knowledge, this is by far the highest observed acceleration on neutral atoms in external fields and may lead to new applications in both fundamental and applied physics. PMID:19865167

  1. Application of sub-Doppler DAVLL to laser frequency stabilization in atomic cesium.

    PubMed

    Su, Dian-Qiang; Meng, Teng-Fei; Ji, Zhong-Hua; Yuan, Jin-Peng; Zhao, Yan-Ting; Xiao, Lian-Tuan; Jia, Suo-Tang

    2014-10-20

    We achieve laser frequency stabilization by a simple technique based on sub-Doppler dichroic atomic vapor laser lock (DAVLL) in atomic cesium. The technique that combines saturated-absorption spectroscopy and Zeeman splitting of hyperfine structures allows us to obtain a modulation-free dispersion-like error signal for frequency stabilization. For the error signal, the dependence of peak-to-peak amplitude and the slope at the zero-crossing point on the magnetic field is studied by simulation and experiment. Based on the result, we obtain an available sub-Doppler DAVLL error signal with high sensitivity to the frequency drift by selecting an appropriate strength of the magnetic field. Ultimately, the fluctuation of the locked laser frequency is confined to below 0.5MHz in a long term, exhibiting efficient suppression of frequency noise. PMID:25402788

  2. Comparing Laser Interferometry and Atom Interferometry Approaches to Space-Based Gravitational-Wave Measurement

    NASA Technical Reports Server (NTRS)

    Baker, John; Thorpe, Ira

    2012-01-01

    Thoroughly studied classic space-based gravitational-wave missions concepts such as the Laser Interferometer Space Antenna (LISA) are based on laser-interferometry techniques. Ongoing developments in atom-interferometry techniques have spurred recently proposed alternative mission concepts. These different approaches can be understood on a common footing. We present an comparative analysis of how each type of instrument responds to some of the noise sources which may limiting gravitational-wave mission concepts. Sensitivity to laser frequency instability is essentially the same for either approach. Spacecraft acceleration reference stability sensitivities are different, allowing smaller spacecraft separations in the atom interferometry approach, but acceleration noise requirements are nonetheless similar. Each approach has distinct additional measurement noise issues.

  3. Optical control of an atomic inner-shell x-ray laser

    NASA Astrophysics Data System (ADS)

    Darvasi, Gábor; Keitel, Christoph H.; Buth, Christian

    2014-01-01

    X-ray free-electron lasers have had an enormous impact on x-ray science by achieving femtosecond pulses with unprecedented intensities. However, present-day facilities operating by the self-amplified spontaneous emission principle have a number of shortcomings; namely, their radiation has a chaotic pulse profile and short coherence times. We put forward a scheme for a neon-based atomic inner-shell x-ray laser (XRL) which produces temporally and spatially coherent subfemtosecond pulses that are controlled by and synchronized to an optical laser with femtosecond precision. We envision that such an XRL will allow for numerous applications such as nuclear quantum optics and the study of ultrafast quantum dynamics of atoms, molecules, and condensed matter.

  4. Magnetic coupling of laser-cooled atoms to a micro-resonator

    NASA Astrophysics Data System (ADS)

    Geraci, Andrew; Wang, Ying-Ju; Eardley, Matthew; Moreland, John; Kitching, John

    2009-05-01

    The direct coupling of the spin-degrees of freedom of an atomic vapor to the vibrational motion of a magnetic cantilever tip has recently been demonstrated [1], and prospects for coupling a BEC on an atom-chip to a nano- mechanical resonator have been recently discussed [2]. Possible applications include chip-scale atomic devices, in which localized interactions with magnetic cantilever tips selectively influence or probe atomic spins. As a next step towards the realization of a strongly coupled ultra-cold atom- resonator system, we have constructed an apparatus to study the direct coupling between the spins of trapped laser-cooled Rb atoms and a magnetic tip on a micro-cantilever. The atoms will be loaded into a magnetic trap formed by the cantilever tip and external magnetic fields. The cantilever will be driven capacitively at its resonance frequency, resulting in a coherent precession of the trapped atomic spins with a matching Larmor frequency. Prospects for measuring the back-action of the ensemble of atomic spins on a cantilever beam will also be discussed. [1] Y.-J. Wang,M. Eardley, S. Knappe, J. Moreland, L. Hollberg, and J. Kitching, PRL 97, 227602 (2006). [2] P. Treutlein,D. Hunger, S. Camerer, T. W. Hansch, and J. Reichel, PRL 99, 140403 (2007).

  5. Development of laser excited atomic fluorescence and ionization methods. Final technical progress report, May 1, 1988--December 31, 1991

    SciTech Connect

    Winefordner, J.D.

    1991-12-31

    Progress report: May 1, 1988 to December 31, 1991. The research supported by DE-FG05-88ER13881 during the past (nearly) 3 years can be divided into the following four categories: (1) theoretical considerations of the ultimate detection powers of laser fluorescence and laser ionization methods; (2) experimental evaluation of laser excited atomic fluorescence; (3) fundamental studies of atomic and molecular parameters in flames and plasmas; (4) other studies.

  6. High-Coherence Electron and Ion Bunches from Laser-Cooled Atoms

    NASA Astrophysics Data System (ADS)

    McCulloch, A. J.; Sheludko, D. V.; Putkunz, C. T.; Saliba, S. D.; Thompson, D. J.; Speirs, R. W.; Murphy, D.; Torrance, J.; Sparkes, B. M.; Scholten, R. E.

    2014-04-01

    Cold atom electron and ion sources produce electron bunches and ion beams by photoionisation of laser cooled atoms. They offer high coherence and the potential for high brightness, with applications including ultrafast electron diffractive imaging of dynamic processes at the nanoscale. Here we present our cold atom electron/ion source, with an electron temperature of less than 10 K and a transverse coherence length of 10 nm. We also discuss experiments investigating space-charge effects with ions and the production of ultra-fast electron bunches using a femto-second laser. In the latter experiment we show that it is possible to produce both cold and fast electron bunches with our source.

  7. Comparison of atom interferometry with laser interferometry for gravitational wave observations in space

    NASA Astrophysics Data System (ADS)

    Bender, Peter L.

    2014-03-01

    Proposals were made earlier in 2008 to use atom interferometry based on Raman transitions for gravitational wave observations in space. Recently, Graham et al. have suggested a new atom interferometry method for such observations based on laser-induced single-photon transitions on highly forbidden optical transitions such as those used in recently developed optical clocks. However, a number of additional requirements that are not discussed by Graham et al. have to be considered if the sensitivity level they suggest is to be reached. When all of the requirements are considered, it appears that such an atom interferometry mission would be much more complex than a laser interferometry mission with better overall sensitivity.

  8. Four-level atomic interferometer driven by shaped ultrafast laser pulses

    SciTech Connect

    Clow, Stephen; Weinacht, Thomas

    2010-08-15

    We analyze the behavior of a four-state, two-path atomic interferometer driven by shaped ultrafast laser pulses. The laser pulses interact with atomic rubidium, exciting the atoms to the 5D state via two intermediate resonances (the 5P{sub 1/2} and 5P{sub 3/2}). The relative phase of the two paths can be modified by applying a varying spectral phase at the wavelength corresponding to one of the resonant transitions for each pathway. We trace out the behavior of the system from the simplest case of weak-field excitation with resonant fields to strong-field excitation with a broadband source. Our measurements and analysis reveal that while interference is observed for all field strengths and spectral widths, the character of the interference changes substantially.

  9. Ultrafast laser-driven Rabi oscillations of a trapped atomic vapor.

    PubMed

    Lee, Han-gyeol; Kim, Hyosub; Ahn, Jaewook

    2015-02-15

    We consider the Rabi oscillation of an atom ensemble of Gaussian spatial distribution interacting with ultrafast laser pulses. Based on an analytical model calculation, we show that its dephasing dynamics is solely governed by the size ratio between the atom ensemble and the laser beam, and that every oscillation peak of the inhomogeneously broadened Rabi flopping falls on the homogeneous Rabi oscillation curve. The results are verified experimentally with a cold rubidium vapor in a magneto-optical trap. As a robust means to achieve higher-fidelity population inversion of the atom ensemble, we demonstrate a spin-echo type R(x)(π/2)R(y)(π)R(x)(π/2) composite interaction as well. PMID:25680137

  10. SUPERSTRONG LASER FIELDS: Relativistic effects of the interaction of an intense femtosecond laser pulse with atomic clusters

    NASA Astrophysics Data System (ADS)

    Rastunkov, V. S.; Krainov, Vladimir P.

    2005-06-01

    The effects of the interaction of an intense femtosecond laser pulse with large atomic clusters are considered. The pulse intensity is of the order of 1018 W cm-2. New effects appear when the magnetic component of the Lorentz force is taken into account. The second harmonic of laser radiation is generated. The second harmonic generation (SHG) efficiency is proportional to the square of the number of atoms in a cluster and the square of the laser radiation intensity. The resonance increase in the SHG efficiency at the Mie frequencies (both at the second-harmonic frequency and fundamental frequency) proved to be insignificant because of a fast passage through the resonance during the cluster expansion. The mechanisms of the expansion and accumulation of energy by electrons and ions in the cluster are discussed in detail. The energy accumulation by electrons mainly occurs due to stimulated inverse bremsstrahlung upon elastic reflection of the electrons from the cluster surface. The equations describing the cluster expansion take into account both the hydrodynamic pressure of heated electrons and the Coulomb explosion of the ionised cluster caused by outer shell ionisation. It is assumed that both inner shell and outer shell ionisation is described by the over-barrier mechanism. It is shown that atomic clusters are more attractive for generation of even harmonics than compared to solid and gas targets.

  11. Characteristics of an all gas-phase iodine laser using molecular iodine as atomic iodine donor

    NASA Astrophysics Data System (ADS)

    Masuda, Taizo; Nakamura, Tomonari; Endo, Masamori

    2010-10-01

    The laser action of an all gas-phase iodine laser (AGIL), which uses molecular iodine as a source of iodine atoms, has been demonstrated. The laser is based on the energy transfer reaction between metastable NCl(a 1?) and ground state I(2P3/2) atoms, which are produced by the electric discharge of a mixture of I2 and He. At fixed flow rates of the chemical species, the laser output powers are measured at three different positions in a flow reactor. The output power is characterized by a function of the optical axis position and is in reasonable agreement with the numerical simulation. A repetitive pulse of laser output at 50 Hz with a duty factor of 40% is observed. The highest output power is 40 mW at 210 mm downstream from the mixing point of I/H/He and NCl3. This is 80% of the output power generated from the conventional system using HI as an iodine donor. The measured results of the time-resolved laser output power suggest that the output power of the I2-AGIL is more sensitive to the electric discharge plasma intensity as compared with that of the HI-AGIL. An AGIL operated using I2 could potentially have the same output power as that of an AGIL operated using HI if a continuous-wave electric discharge generator is used.

  12. Effects of neutron fluence on the operating characteristics of diode lasers used in atomic frequency standards. Technical report

    SciTech Connect

    Frueholz, R.P.; Camparo, J.C.; Delcamp, S.B.; Barnes, C.E.

    1990-08-15

    One of the next major advances in rubidium and cesium atomic clock technology will center on the use of diode lasers for optical pumping. The atomic clocks used on board satellites have the potential to interact with various forms of radiation that are not present in the laboratory environment, and the effects of this radiation on the laser's operating characteristics relevant to clock applications are not well known. The present report describes an ongoing experiment to study the effects of neutron fluence on the operating characteristics of Mitsubishi Transverse Junction Stripe (TJS) AlGaAs diode lasers. Different models of the TJS diode laser produce optical radiation in both the 780 and 850 nm range, appropriate for optical pumping in rubidium and cesium atomic clocks, respectively. In this phase, a set of TJS diode lasers has been exposed to a neutron fluence of 2 x 1012 n/cm2, and four laser characteristics were examined after each exposure. The laser's light output versus injection current and single-mode linewidth versus output power both influence the efficiency of optical pumping and hence the atomic clock's signal-to-noise ratio. We have also measured the laser's single-mode wavelength versus injection current (laser tuning). Since the diode laser must remain tuned to the appropriate atomic transition, any degradation in the ability to tune the laser will impact atomic clock reliability. Finally, the diode laser's gain curve has been studied at several injection currents below threshold. This diode laser characteristic is taken as an indicator of the neutron damage mechanisms in the laser's semiconductor material. Changes in these characteristics due to the neutron exposure are reported.

  13. Propagation of frequency-chirped laser pulses in a medium of atoms with a {lambda}-level scheme

    SciTech Connect

    Demeter, G.; Dzsotjan, D.; Djotyan, G. P.

    2007-08-15

    We study the propagation of frequency-chirped laser pulses in optically thick media. We consider a medium of atoms with a {lambda} level-scheme (Lambda atoms) and also, for comparison, a medium of two-level atoms. Frequency-chirped laser pulses that induce adiabatic population transfer between the atomic levels are considered. They induce transitions between the two lower (metastable) levels of the {lambda}-atoms and between the ground and excited states of the two-level atoms. We show that associated with this adiabatic population transfer in {lambda}-atoms, there is a regime of enhanced transparency of the medium--the pulses are distorted much less than in the medium of two-level atoms and retain their ability to transfer the atomic population much longer during propagation.

  14. Single attosecond burst generation during ionization of excited atoms by intense ultrashort laser pulses

    SciTech Connect

    Emelin, M. Yu.; Ryabikin, M. Yu. Sergeev, A. M.

    2008-02-15

    We develop an analytical approach to describing the generation of a single attosecond burst during barrier-suppression ionization of a hydrogen atom by an intense laser pulse. We derive analytical expressions that describe the evolution of the electron wave packet in the time interval between the detachment from the atom and the collision with the parent ion for an arbitrary initial atomic state by assuming the atom to be fully ionized in one laser-field half-period. For various s-states, we derive expressions for the profile of the attosecond burst generated when the electron packet collides with the ion and analyze the dependence of its generation efficiency on the principal quantum number n of the initial atomic state. The results obtained are compared with the results of three-dimensional numerical calculations. We show that the attosecond pulse generation efficiency can be several orders of magnitude higher than that in the case of ionization from the ground state when pre-excited atomic states are used.

  15. SLIMP: Strong laser interaction model package for atoms and molecules

    NASA Astrophysics Data System (ADS)

    Zhang, Bin; Zhao, Zengxiu

    2015-07-01

    We present the SLIMP package, which provides an efficient way for the calculation of strong-field ionization rate and high-order harmonic spectra based on the single active electron approximation. The initial states are taken as single-particle orbitals directly from output files of the general purpose quantum chemistry programs GAMESS, Firefly and Gaussian. For ionization, the molecular Ammosov-Delone-Krainov theory, and both the length gauge and velocity gauge Keldysh-Faisal-Reiss theories are implemented, while the Lewenstein model is used for harmonic spectra. Furthermore, it is also efficient for the evaluation of orbital coordinates wavefunction, momentum wavefunction, orbital dipole moment and calculation of orbital integrations. This package can be applied to quite large basis sets and complex molecules with many atoms, and is implemented to allow easy extensions for additional capabilities.

  16. THERMAL EFFECTS ON MASS AND SPATIAL RESOLUTION DURING LASER PULSE ATOM PROBE TOMOGRAPHY OF CERIUM OXIDE

    SciTech Connect

    Rita Kirchhofer; Melissa C. Teague; Brian P. Gorman

    2013-05-01

    Cerium oxide (CeO2) is an ideal surrogate material for trans-uranic elements and fission products found in nuclear fuels due to similarities in their thermal properties; therefore, cerium oxide was used to determine the best run condition for atom probe tomography (APT). Laser pulse APT is a technique that allows for spatial resolution in the nm scale and isotopic/elemental chemical identification. A systematic study of the impact of laser pulse energy and specimen base temperature on the mass resolution, measurement of stoichiometry, multiples, and evaporation mechanisms are reported in this paper. It was demonstrated that using laser pulse APT stoichiometric field evaporation of cerium oxide was achieved at 1 pJ laser pulse energy and 20 K specimen base temperature.

  17. Diode laser operating on an atomic transition limited by an isotope ??Rb Faraday filter at 780 nm.

    PubMed

    Tao, Zhiming; Hong, Yelong; Luo, Bin; Chen, Jingbiao; Guo, Hong

    2015-09-15

    We demonstrate an extended cavity Faraday laser system using an antireflection-coated laser diode as the gain medium and the isotope (87)Rb Faraday anomalous dispersion optical filter (FADOF) as the frequency selective device. Using this method, the laser wavelength works stably at the highest transmission peak of the isotope (87)Rb FADOF over the laser diode current from 55 to 140 mA and the temperature from 15C to 35C. Neither the current nor the temperature of the laser diode has significant influence on the output frequency. Compared with previous extended cavity laser systems operating at frequencies irrelevant to spectacular atomic transition lines, the laser system realized here provides a stable laser source with the frequency operating on atomic transitions for many practical applications. PMID:26371933

  18. Atomic force microscopy and Raman scattering studies of femtosecond laser-induced nanohillocks on CR-39

    NASA Astrophysics Data System (ADS)

    Bashir, Shazia; Rafique, M. Shahid; Husinsky, Wolfgang; Hobro, Alison; Lendl, Bernhard

    2009-12-01

    The phenomenon of nanohillock-like defect formation on the surfaces of CR-39 by ultra-short laser irradiation is investigated using an Atomic Force Microscope (AFM) and Raman Scattering. A polymer CR-39 target was exposed to Ti:sapphire 25-fs laser pulses with a central wavelength at 800 nm. Samples were irradiated for different laser fluences both in air and vacuum. Detailed surface topographical features of the bombarded samples were characterized by atomic force microscopy in contact mode in air at room temperature. AFM reveals that the growth of nanohillocks and their features are strongly dependent on the ambient condition, target position from focus, and irradiation fluence. The appearance of these nanohillocks in the range 1-20 nm in height and 10-90 nm in diameter are regarded as typical features for fast electronic processes (correlated with existence of hot electrons) and are explained on the basis of Coulomb explosion. These nanostructures due to localization of laser energy deposition in small areas provide a possible pathway from dense electronic excitation to atomic motion causing permanent structural modification which are well correlated to structural alterations, like crosslinking and chain scissions, inferred from Raman spectroscopy.

  19. Photoelectron and photoion spectroscopy of atoms, nanoparticles, and nanoplasmas irradiated with strong femtosecond laser fields

    NASA Astrophysics Data System (ADS)

    Hickstein, Daniel D.

    Modern femtosecond lasers can produce pulses of light that are shorter than the vibrational periods in molecules and have electric fields stronger than the Coulomb field that binds electrons in atoms. These short pulse lasers enable the observation of chemical reactions, the production of attosecond bursts of high-energy photons, and the precision-machining of solid materials with minimal heat transport to the material. In this thesis, I describe three experiments that provide new insight into strong-field (1014 Watts/cm2) femtosecond laser-matter interactions in three important regimes. First, I discuss the strong-field ionization of gas-phase atoms, identify a new structure in the photoelectron angular distribution of xenon gas, and explain this structure as a result of field-driven electrons colliding with the Coulomb potential of the ion. Second, I describe a new method to perform photoelectron and photoion spectroscopy on single, isolated nanoparticles and demonstrate this technique by observing the directional ion ejection that takes place in the laser ablation of nanostructures. Finally, I present the first experimental observations of shock wave propagation in nanoscale plasmas. These findings will guide future efforts to probe the structure of atoms and molecules on the femtosecond timescale, design nanomaterials that enhance light on the subwavelength scale, and produce high-energy ions from plasmas.

  20. Above-threshold ionization and photoelectron spectra in atomic systems driven by strong laser fields

    NASA Astrophysics Data System (ADS)

    Surez, Noslen; Chacn, Alexis; Ciappina, Marcelo F.; Biegert, Jens; Lewenstein, Maciej

    2015-12-01

    Above-threshold ionization (ATI) results from strong-field laser-matter interaction and it is one of the fundamental processes that may be used to extract electron structural and dynamical information about the atomic or molecular target. Moreover, it can also be used to characterize the laser field itself. Here we develop an analytical description of ATI, which extends the theoretical strong-field approximation (SFA), for both the direct and rescattering transition amplitudes in atoms. From a nonlocal, but separable potential, the bound-free dipole and the rescattering transition matrix elements are analytically computed. In comparison with the standard approaches to the ATI process, our analytical derivation of the rescattering matrix elements allows us to study directly how the rescattering process depends on the atomic target and laser-pulse features; we can turn on and off contributions having different physical origins or corresponding to different physical mechanisms. We compare SFA results with the full numerical solutions of the time-dependent Schrdinger equation (TDSE) within the few-cycle pulse regime. Good agreement between our SFA and TDSE model is found for the ATI spectrum. Our model captures also the strong dependence of the photoelectron spectra on the carrier envelope phase of the laser field.

  1. Manipulation of Ultracold Rubidium Atoms Using a Single Linearly Chirped Laser Pulse

    NASA Astrophysics Data System (ADS)

    Collins, Thomas; Malinovskaya, Svetlana

    2011-05-01

    The ability to manipulate ultracold atomic and molecular systems allows us to utilize their potential for use in the emerging field of quantum computing, which holds the promise of developing computing systems which operate at speeds far greater than those of conventional computers. Also, ultracold atomic and molecular systems have possible chemical applications that make it desirable to find an efficient way to control which quantum states available to the system are occupied. In this work we studied the behavior of Rubidium atoms dressed by a linearly-chirped laser pulse, modeling the quantum states of the atoms as a three level lambda system. We set as our control knobs the pulse duration, chirp parameter, field strength, and the one-photon detuning. We discovered certain sets of values for the control knobs which yielded near total transfer to the desired state and thus may be used in experimental setup.

  2. High-stability compact atomic clock based on isotropic laser cooling

    SciTech Connect

    Esnault, Francois-Xavier; Holleville, David; Rossetto, Nicolas; Guerandel, Stephane; Dimarcq, Noel

    2010-09-15

    We present a compact cold-atom clock configuration where isotropic laser cooling, microwave interrogation, and clock signal detection are successively performed inside a spherical microwave cavity. For ground operation, a typical Ramsey fringe width of 20 Hz has been demonstrated, limited by the atom cloud's free fall in the cavity. The isotropic cooling light's disordered properties provide a large and stable number of cold atoms, leading to a high signal-to-noise ratio limited by atomic shot noise. A relative frequency stability of 2.2x10{sup -13{tau}-1/2} has been achieved, averaged down to 4x10{sup -15} after 5x10{sup 3} s of integration. Development of such a high-performance compact clock is of major relevance for on-board applications, such as satellite-positioning systems. As a cesium clock, it opens the door to a new generation of compact primary standards and timekeeping devices.

  3. Search for Electric dipole moment (EDM) in laser cooled and trapped 225Ra atoms

    NASA Astrophysics Data System (ADS)

    Kalita, Mukut; Bailey, Kevin; Dietrich, Matthew; Green, John; Holt, Roy; Korsch, Wolfgang; Lu, Zheng-Tian; Lemke, Nathan; Mueller, Peter; O'Connor, Tom; Parker, Richard; Singh, Jaideep; Trimble, Will; Argonne National Laboratory Collaboration; University Of Chicago Collabration; University Of Kentucky Collaboration

    2014-05-01

    We are searching for an EDM of the diamagnetic 225Ra atom. 225Ra has nuclear spin I =1/2. Experimental sensitivity to its EDM is enhanced due to its heavy mass and the increased Schiff moment of its octupole deformed nucleus. Our experiment involves collecting laser cooled Ra atoms in a magneto-optical trap (MOT), transporting them 1 meter with a far off-resonant optical dipole trap (ODT) and then transferring the atoms to a second standing-wave ODT in our experimental chamber. We will report our recent experiences in polarizing and observing Larmor precession of 225Ra atoms in parallel electric and magnetic fields in a magnetically shielded region and progress towards a first measurement of the EDM of 225Ra. This work is supported by DOE, Office of Nuclear Physics, under contract No. DE-AC02-06CH11357 and contract No. DE-FG02-99ER41101.

  4. An all gas-phase iodine laser using molecular iodine as atomic iodine donor

    NASA Astrophysics Data System (ADS)

    Masuda, Taizo; Nakamura, Tomonari; Endo, Masamori

    2010-09-01

    The characteristics of an all gas-phase iodine laser (AGIL) that uses molecular iodine as a source of iodine atoms is studied. The laser is based on the energy transfer reaction between metastable NCl(a1?) and ground state I(2P3/2) atoms, which are produced by the electric discharge of a mixture of I2 and He. At fixed flow rates of the chemical species, the laser output powers are measured at three different positions in a flow reactor. The output power is characterized by a function of the optical axis position and is reasonably reproduced by the numerical calculation. A repetitive pulse of laser output at 50 Hz with a duty factor of 40% is observed. The highest output power is 40 mW at 210 mm downstream from the mixing point of I/H/He and NCl3. This is 80% of the output power generated from the conventional system using HI as an iodine donor. The measured results of the time resolved laser output power suggest that the output power of the I2- AGIL is more sensitive to the electric discharge plasma intensity as compared to that of the HI-AGIL. An AGIL operated using I2 could potentially have the same output power as that of an AGIL operated using HI if a continuous-wave electric discharge generator is used.

  5. A Technology Demonstration Experiment for Laser Cooled Atomic Clocks in Space

    NASA Technical Reports Server (NTRS)

    Klipstein, W. M.; Kohel, J.; Seidel, D. J.; Thompson, R. J.; Maleki, L.; Gibble, K.

    2000-01-01

    We have been developing a laser-cooling apparatus for flight on the International Space Station (ISS), with the intention of demonstrating linewidths on the cesium clock transition narrower than can be realized on the ground. GLACE (the Glovebox Laser- cooled Atomic Clock Experiment) is scheduled for launch on Utilization Flight 3 (UF3) in 2002, and will be mounted in one of the ISS Glovebox platforms for an anticipated 2-3 week run. Separate flight definition projects funded at NIST and Yale by the Micro- gravity Research Division of NASA as a part of its Laser Cooling and Atomic Physics (LCAP) program will follow GLACE. Core technologies for these and other LCAP missions are being developed at JPL, with the current emphasis on developing components such as the laser and optics subsystem, and non-magnetic vacuum-compatible mechanical shutters. Significant technical challenges in developing a space qualifiable laser cooling apparatus include reducing the volume, mass, and power requirements, while increasing the ruggedness and reliability in order to both withstand typical launch conditions and achieve several months of unattended operation. This work was performed at the Jet Propulsion Laboratory under a contract with the National Aeronautics and Space Administration.

  6. Atomic inner-shell laser at 1.5-ngstrm wavelength pumped by an X-ray free-electron laser

    NASA Astrophysics Data System (ADS)

    Yoneda, Hitoki; Inubushi, Yuichi; Nagamine, Kazunori; Michine, Yurina; Ohashi, Haruhiko; Yumoto, Hirokatsu; Yamauchi, Kazuto; Mimura, Hidekazu; Kitamura, Hikaru; Katayama, Tetsuo; Ishikawa, Tetsuya; Yabashi, Makina

    2015-08-01

    Since the invention of the first lasers in the visible-light region, research has aimed to produce short-wavelength lasers that generate coherent X-rays; the shorter the wavelength, the better the imaging resolution of the laser and the shorter the pulse duration, leading to better temporal resolution in probe measurements. Recently, free-electron lasers based on self-amplified spontaneous emission have made it possible to generate a hard-X-ray laser (that is, the photon energy is of the order of ten kiloelectronvolts) in an ngstrm-wavelength regime, enabling advances in fields from ultrafast X-ray spectrosopy to X-ray quantum optics. An atomic laser based on neon atoms and pumped by a soft-X-ray (that is, a photon energy of less than one kiloelectronvolt) free-electron laser has been achieved at a wavelength of 14 nanometres. Here, we use a copper target and report a hard-X-ray inner-shell atomic laser operating at a wavelength of 1.5 ngstrms. X-ray free-electron laser pulses with an intensity of about 1019 watts per square centimetre tuned to the copper K-absorption edge produced sufficient population inversion to generate strong amplified spontaneous emission on the copper K? lines. Furthermore, we operated the X-ray free-electron laser source in a two-colour mode, with one colour tuned for pumping and the other for the seed (starting) light for the laser.

  7. Stabilization of circular Rydberg atoms by circularly polarized infrared laser fields

    SciTech Connect

    Askeland, S.; Soerngaard, S. A.; Nepstad, R.; Foerre, M.; Pilskog, I.

    2011-09-15

    The ionization dynamics of circular Rydberg states in strong circularly polarized infrared (800 nm) laser fields is studied by means of numerical simulations with the time-dependent Schroedinger equation. We find that at certain intensities, related to the radius of the Rydberg states, atomic stabilization sets in, and the ionization probability decreases as the intensity is further increased. Moreover, there is a strong dependence of the ionization probability on the rotational direction of the applied laser field, which can be understood from a simple classical analogy.

  8. Stabilization of circular Rydberg atoms by circularly polarized infrared laser fields

    NASA Astrophysics Data System (ADS)

    Askeland, S.; Sørngård, S. A.; Pilskog, I.; Nepstad, R.; Førre, M.

    2011-09-01

    The ionization dynamics of circular Rydberg states in strong circularly polarized infrared (800 nm) laser fields is studied by means of numerical simulations with the time-dependent Schrödinger equation. We find that at certain intensities, related to the radius of the Rydberg states, atomic stabilization sets in, and the ionization probability decreases as the intensity is further increased. Moreover, there is a strong dependence of the ionization probability on the rotational direction of the applied laser field, which can be understood from a simple classical analogy.

  9. Laser-diode frequency control by resonant phase-conjugate reflection from an atomic vapor.

    PubMed

    Cyr, N; Breton, M; Têtu, M; Thériault, S

    1991-09-01

    We report our first results on the frequency control of an AlGaAs laser diode by resonant phase-conjugate reflection from an atomic rubidium vapor. When the electrical feedback technique is used, the Allan variance reaches a flicker floor such that sigma(y)(2)(tau) = 1.6 x 10(-19) tau(0) for tau > 1s. We also demonstrate that laser frequency locking can be achieved by using the phase-conjugate reflection directly as a resonant optical feedback. This approach leads to a self-controlled optical frequency standard at 780 nm. PMID:19776950

  10. Observation of picosecond superfluorescent pulses in rubidium atomic vapor pumped by 100-fs laser pulses

    SciTech Connect

    Ariunbold, Gombojav O.; Kash, Michael M.; Sautenkov, Vladimir A.; Li, Hebin; Welch, George R.; Rostovtsev, Yuri V.; Scully, Marlan O.

    2010-10-15

    We study the superfluorescence (SF) from a gas of rubidium atoms. The atoms of a dense vapor are excited to the 5D state from the 5S state by a two-photon process driven by 100-fs laser pulses. The atoms decay to the 6P state and then to the 5S state. The SF emission at 420 nm on the 6P-5S transition is recorded by a streak camera with picosecond time resolution. The time duration of the generated SF is tens of picoseconds, which is much shorter than the time scale of the usual relaxation processes, including spontaneous emission and atomic coherence dephasing. The dependence of the time delay between the reference input pulse and SF is measured as a function of laser power. The experimental data are described quantitatively by a simulation based on the semiclassical atom-field interaction theory. The observed change in scaling laws for the peak intensity and delay time can be elucidated by an SF theory in which the sample length is larger than the cooperation length.

  11. A modification of the laser detonation-type hyperthermal oxygen atom beam source for a long-term operation

    SciTech Connect

    Kinoshita, Hiroshi; Yamamoto, Shunsuke; Yatani, Hideaki; Ohmae, Nobuo

    2008-07-15

    It has been an impedimental problem, for the laser detonation-type atom beam generator, that a poppet in the pulsed supersonic valve is rapidly eroded by the irradiation of powerful laser light and high temperature plasma. In order to operate the atom beam source for a long duration, a modification was made to hide the poppet from direct irradiation of laser and plasma. The alteration of device configuration resulted in great improvement in endurance of poppet more than 300 000 repetitions. Morphology of a polyimide film exposed to approximately 200 000 pulses of hyperthermal oxygen atom beam showed a shaglike carpet structure, which is a characteristic to that exposed to energetic oxygen atoms. A flux of the oxygen atom beam was estimated to be 5x10{sup 14} atoms/cm{sup 2}/pulse at a location of 30 cm away from the nozzle throat.

  12. Photoelectron momentum distributions of the hydrogen atom driven by multicycle elliptically polarized laser pulses

    NASA Astrophysics Data System (ADS)

    Murakami, Mitsuko; Chu, Shih-I.

    2016-02-01

    Photoelectron momentum distributions (PMDs) of the hydrogen atom driven by multicycle elliptically polarized strong laser fields are studied in detail, based on the numerical solution of the time-dependent Schrödinger equation and the Volkov wave propagation. Both short and long driving pulses of the 800-nm field are considered, as well as the ellipticity dependence, to describe the mechanism of symmetry breaking in the hydrogen-atom PMD. Moreover, we demonstrate that the value of a retardation angle in the longitudinal PMD can depend on the order of above-threshold ionization spectra.

  13. Survival of Rydberg atoms in intense laser fields and the role of nondipole effects

    NASA Astrophysics Data System (ADS)

    Klaiber, Michael; Dimitrovski, Darko

    2015-02-01

    We consider the interaction of Rydberg atoms with strong infrared laser pulses using an approach based on the Magnus expansion of the time evolution operator. First-order corrections beyond the electric dipole approximation are also included in the theory. We illustrate the dynamics of the interaction at the parameters of the experiment [Eichmann et al., Phys. Rev. Lett. 110, 203002 (2013), 10.1103/PhysRevLett.110.203002]. It emerges that the depletion of Rydberg atoms in this regime comes predominantly from the nondipole effects.

  14. New metal atom laser transitions in As, Bi, Ga, Ge, Hg, In, Pb, Sb, and Tl

    NASA Technical Reports Server (NTRS)

    Chou, M. S.; Cool, T. A.

    1976-01-01

    A double discharge technique was used in the investigation. An initial discharge established between parallel arrays of tungsten pin electrodes was followed, after a variable time delay, by a high voltage (180 kV), short duration (50 nsec) secondary discharge between two aluminum main electrodes. Metal compounds, including metal alkyls, hydrides, and halides, were used to obtain the required metal atom concentrations. Twenty-four new laser transitions involving 9 different metal atoms were observed. The observed relations are shown in a number of partial energy-level diagrams.

  15. Tunable Diode Laser Absorption Spectroscopy of Metastable Atoms in Dusty Plasmas

    SciTech Connect

    Hoang Tung Do; Hippler, Rainer

    2008-09-07

    Spatial density profile of neon metastable produced in dusty plasma was investigated by means of tunable diode laser absorption spectroscopy. The line averaged measured density drops about 30% with the presence of dust particles. The observations provide evidence for a significant interaction between atoms and powder particles which are important for energy transfer from plasma to particles. The power per unit area absorbed by dust particles due to the collision of metastable atoms with dust particle surface is about some tens of mW/m{sup 2}.

  16. Magnetic Dichroism in K-Shell Photoemission from Laser Excited Li Atoms

    NASA Astrophysics Data System (ADS)

    Meyer, M.; Grum-Grzhimailo, A. N.; Cubaynes, D.; Felfli, Z.; Heinecke, E.; Manson, S. T.; Zimmermann, P.

    2011-11-01

    Magnetic dichroism in the angular distribution has been demonstrated for single-electron photoemission from inner ns2 subshells of gaseous atomic targets using the example of K-shell photoionization of polarized Li atoms laser prepared in the 1s22p P3/22 excited state. The effect is pronounced for the conjugate shakeup and conjugate shakedown photoelectron lines, and less important, though observable, for the main and direct shakeup lines. The phenomenon is caused by configuration interaction in the final continuum state and is quantitatively described by the close-coupling R-matrix calculations.

  17. Production of iodine atoms for an oxygen-iodine laser from iodine-containing molecules with the help of atomic oxygen

    SciTech Connect

    Shepelenko, A A; Mikheev, P A

    2003-03-31

    A new technique is proposed for the production of atomic iodine for a cw oxygen-iodine laser with the use of reactions between iodine donor molecules and oxygen atoms. The CH{sub 3}I, CF{sub 3}I, or I{sub 2} molecules can be used as donors. Oxygen atoms are injected into the reaction region by admixing the flow of partially dissociated oxygen produced in an electric discharge. The use of atomic iodine instead of molecular iodine excludes the consumption of singlet oxygen O{sub 2}({sup 1{Delta}}) for the dissociation of I{sub 2} and quenching of I* by the I{sub 2} molecules. The latter will supposedly allow raising the optimal density of I and accordingly the gain coefficient. Estimates were made of the required degree of dissociation of oxygen employed to obtain iodine atoms at which the above advantages can be realised. (lasers)

  18. Two-photon dichroic atomic vapor laser lock using electromagnetically induced transparency and absorption

    SciTech Connect

    Becerra, F. E.; Willis, R. T.; Rolston, S. L.; Orozco, L. A.

    2009-07-15

    We demonstrate a technique to lock the frequency of a laser to a transition between two excited states in Rb vapor using a two-photon process in the presence of a weak magnetic field. We use a ladder configuration from specific hyperfine sublevels of the 5S{sub 1/2}, 5P{sub 3/2}, and 5D{sub 5/2} levels. This atomic configuration can show electromagnetically induced transparency and absorption processes. The error signal comes from the difference in the transparency or absorption felt by the two orthogonal polarizations of the probe beam. A simplified model is in good quantitative agreement with the observed signals for the experimental parameters. We have used this technique to lock the frequency of the laser up to 1.5 GHz off atomic resonance.

  19. Wave packet dynamics of excited atomic electrons in intense laser fields

    SciTech Connect

    Kulander, K.C.; Schafer, K.J.

    1996-08-01

    Dynamics of muliphoton ionization in the tunneling (long wavelength, high intensity) regime is described. Photoemission by tunnel ionized atoms is dominated by the odd harmonics of the driving laser field. Excitation by ultra short ({similar_to} 10-20 fs) pulses produces hiogh harmonics with characteristics which will alow them to be compressed to given coherent sources of VUV and possibly XUV radiation with pulse lengths near or below 1 fs.

  20. High-resolution laser spectroscopy of ultracold ytterbium atoms using spin-forbidden electric quadrupole transition

    NASA Astrophysics Data System (ADS)

    Uetake, S.; Yamaguchi, A.; Hashimoto, D.; Takahashi, Y.

    2008-11-01

    We have successfully observed high-resolution spectra of spin-forbidden electric quadrupole transition (1 S 0?3 D 2) in ytterbium (174Yb) atoms. The differential light shifts between the 1 S 0 and the 3 D 2 states in a far-off resonant trap at 532 nm are also measured. For the spectroscopy, we developed simple, narrow-linewidth, and long-term frequency stabilized violet diode laser systems. Long-term drifts of the excitation laser (404 nm) is suppressed by locking the laser to a length stabilized optical cavity. The optical path length of the cavity is stabilized to another diode laser whose frequency is locked to a strong 1 S 0?1 P 1 transition (399 nm) of Yb. Both lasers are standard extended-cavity diode lasers (ECDLs) in the Littrow configuration. Since the linewidth of a violet ECDL (10 MHz) is broader than a typical value of a red or near infra-red ECDL (<1 MHz), we employ optical feedback from a narrow-band Fabry-Perot cavity to reduce the linewidth. The linewidth is expected to be <20 kHz for 1 ms averaging time, and the long-term frequency stability is estimated to be 200 kHz/h.

  1. Comparison of Laser Interferometry and Atom Interferometry for Gravitational Wave Observations in Space

    NASA Astrophysics Data System (ADS)

    Bender, Peter L.

    2015-08-01

    1. In 2013 a suggestion was made by Graham et al. [1] [Phys. Rev. Lett. 110, 171102 (2013)] of possible GW observations over 10^3 km baselines using strongly forbidden single photon transitions in atoms such as Sr-87. A comparison of the requirements for such a mission with those for laser interferometer missions such as LISA or eLISA with roughly 10^6 km baselines was published in 2014 [Bender, Phys. Rev. D 89, 062004 (2014)]. The comparison will be somewhat updated in this talk.2. Recently, a possible method for gravitational wave observations with atom interferometry over million km scale baselines has been suggested by Hogan and Kasevich [arXiv:1501.06797v1 (2015)]. As an example, they consider observations similar to those discussed in [1], but over a 2*10^6 km baseline. The atomic transitions in the two spacecraft would be driven by separate lasers that are phase locked using 1 W laser power and 30 cm diam. telescopes. Total observation times for individual clouds of 80 to 320 s are assumed, along with 50 concurrent interferometers and a 60 Hz Rabi frequency for the laser pulses.3. After the flight of the LISA Pathfinder mission later this year, it is expected that more intensive work will start on a laser interferometer gravitational wave mission. Probably the most important objective will be the observation of GW signals from the mergers at high redshifts of massive black holes with masses in the range from perhaps 10^4 to 10^7 M_sun. Such signals would give new constraints on the mechanisms for the formation of intermediate mass and larger black holes at early times, and probably contribute to understanding the observed close correlation between the growth of galaxies and of the massive black holes at their centers.

  2. Non-thermal laser-induced desorption of metal atoms with bimodal kinetic energy distribution

    NASA Astrophysics Data System (ADS)

    Gtz, T.; Bergt, M.; Hoheisel, W.; Trger, F.; Stuke, M.

    1996-09-01

    Laser-induced desorption of metal atoms at low rate has been studied for pulsed excitation with wavelengths of ?=266, 355, 532 and 1064 nm. For this purpose sodium adsorbed on quartz served as a model system. The detached Na atoms were photo-ionized with the light of a second laser operating at ?=193 nm and their kinetic energy distribution was determined by time-of-flight measurements. For ?=1064 nm a distribution typical of thermal bond breaking is observed. If desorption, however, is stimulated with light of ?=266 or 532 nm, the kinetic energy distribution is non-thermal with a single maximum at E kin=0.160.02 eV. For ?=355 nm the non-thermal distribution is even bimodal with maxima appearing at E kin=0.160.02 and 0.330.02 eV. These values of the kinetic energies actually remain constant under variation of all experimental parameters. They appear to reflect the electronic and geometric properties of different binding sites from which the atoms are detached and thus constitute fingerprints of the metal surface. The non-thermal desorption mechanism is discussed in the framework of the Menzel-Gomer-Redhead scenario. The transition from non-thermal to thermal desorption at large fluences of the laser light could also be identified.

  3. Discharge formation systems for generating atomic iodine in a pulse-periodic oxygen-iodine laser

    NASA Astrophysics Data System (ADS)

    Aksinin, V. I.; Antsiferov, S. A.; Velikanov, S. D.; Gerasimov, A. Yu; Gostev, I. V.; Kazantsev, S. Yu; Kalinovskii, V. V.; Konovalov, V. V.; Kononov, I. G.; Mikhalkin, V. N.; Podlesnykh, S. V.; Sevryugin, I. V.; Firsov, K. N.

    2014-01-01

    Generation characteristics of a pulse-periodic oxygen-iodine laser with the electro-discharge production of atomic iodine were compared with inductively stabilised edged or anisotropic- resistive cathodes used for ignition of the volume discharge. The discharge was initiated by the radiation of a barrier discharge from the side of a grid anode. It was found that at equal specific electrical energy depositions to the gas-discharge plasma, the system with the anisotropic-resistive cathode provides a more stable and uniform volume discharge with the possibility of varying the composition and pressure of working mixtures over a wide range and a greater specific extraction of laser energy is observed (up to 2.4 J L-1). At a high pulse repetition rate of laser pulses (50 - 100 Hz) and long duration of the pulse trains (longer than a minute) the surface of anisotropic-resistive cathode became eroded.

  4. Laser generation of ultra-short neutron bursts from high atomic number converters

    NASA Astrophysics Data System (ADS)

    Pomerantz, I.; McCary, E.; Meadows, A. R.; Arefiev, A.; Bernstein, A. C.; Chester, C.; Cortez, J.; Donovan, M. E.; Dyer, G.; Gaul, E. W.; Hamilton, D.; Kuk, D.; Lestrade, A. C.; Wang, C.; Ditmire, T.; Hegelich, B. M.

    2015-05-01

    At the Texas Petawatt laser facility we developed a novel ultra-short pulsed laser-driven neutron source generating an unprecedented output peak flux. Our results show a dramatic onset of high-energy electron generation from petawatt laser-irradiated plastic targets for targets thinner than a few microns. In this regime, the copious amounts of multi-MeV electrons emitted from the target are utilized to generate photo-neutrons from a metal converter. The neutrons are generated with a <50 ps pulse duration and a flux of 1018 n/cm2/s, exceeding any other pulsed or CW neutron source. In this paper, we will report on our measurement of the neutron yields produced from high atomic number converters.

  5. Laser-Aided Diagnostics of Atoms and Particulates in Magnetron Sputtering Plasmas

    SciTech Connect

    Nafarizal, N.; Takada, N.; Sasaki, K.

    2009-07-07

    Laser-aided diagnostic technique is introduced as an advanced and valuable technique to evaluate the properties of plasma. This technique is an expensive and sophisticated technique which requires researchers to have a basic knowledge in optical spectroscopy. In the present paper, we will generally introduce the experimental work using laser-induced fluorescence (LIF) and laser light scattering (LLS) techniques. The LIF was used to evaluate the spatial distribution of Cu atoms in magnetron sputtering plasma. The change in the spatial distribution was studied as a function of discharge power. On the other hand, the LLS was used to evaluate the generation of Cu particulates in high-pressure magnetron sputtering plasma. The temporal evolution of Cu particulates in the gas phase of sputtering plasma was visualized successfully.

  6. A Hertz-Linewidth Ultrastable Diode Laser System for Clock Transition Detection of Strontium Atoms

    NASA Astrophysics Data System (ADS)

    Li, Ye; Lin, Yi-Ge; Wang, Qiang; Wang, Shao-Kai; Zhao, Yang; Meng, Fei; Lin, Bai-Ke; Cao, Jian-Ping; Li, Tian-Chu; Fang, Zhan-Jun; Zang, Er-Jun

    2014-02-01

    The frequencies of two 698 nm external cavity diode lasers (ECDLs) are locked separately to two independently located ultrahigh finesse optical resonant cavities with the PoundDreverHall technique. The linewidth of each ECDL is measured to be ~4.6 Hz by their beating and the fractional frequency stability below 5 10-15 between 1 s to 10 s averaging time. Another 698 nm laser diode is injection locked to one of the cavity-stabilized ECDLs with a fixed frequency offset for power amplification while maintaining its linewidth and frequency characteristics. The frequency drift is ~1 Hz/s measured by a femtosecond optical frequency comb based on erbium fiber. The output of the injection slave laser is delivered to the magneto-optical trap of a Sr optical clock through a 10-m-long single mode polarization maintaining fiber with an active fiber noise cancelation technique to detect the clock transition of Sr atoms.

  7. Laser-excitation technique for the measurement of absolute transition probabilities of weak atomic lines

    NASA Technical Reports Server (NTRS)

    Kwong, H. S.; Smith, P. L.; Parkinson, W. H.

    1982-01-01

    A new technique is presented for the measurement of transition probabilities for weak allowed, intersystem, and forbidden lines. The method exploits the fact that oscillator strength is proportional to the number of stimulated absorptions and emissions produced by a narrow-band laser pulse of known energy which is in resonance with an atomic transition. The method is tested for a particular transition of Mg I with a known oscillator strength value and of appropriate magnitude. The number densities are measured using a Mach-Zehnder interferometer and the hook method for the lower level population and by measuring an absorption-equivalent width for the other. The apparatus consisted of a high-power tunable laser and a magnesium oven to produce excited Mg vapor, and a laser-plasma background continuum. The results are in good agreement with theoretical and other experimental data.

  8. Nondipole ionization dynamics in atoms induced by intense xuv laser fields

    NASA Astrophysics Data System (ADS)

    Frre, Morten; Simonsen, Aleksander Skjerlie

    2014-11-01

    Solving the time-dependent Schrdinger equation from first principles, the laser-induced breakup dynamics of hydrogen is studied beyond the electric dipole approximation, at very high laser intensities. It is assumed that the atom is being irradiated by an extreme ultraviolet laser light pulse at a wavelength of 13 nm, corresponding to a photon energy of 95 eV. It has already been experimentally demonstrated that the free-electron laser (FEL) FLASH in Hamburg can deliver irradiance levels up to about 1016W/cm2 in this wavelength range. Although we will go to even higher intensities in the present work, in order to spot nondipole effects, this merely demonstrates that ultrahigh light intensities can be achieved with present FEL technologies. Furthermore, with new seeding techniques the laser power is expected to go even higher in the future. In our study the atom is exposed to a short attosecond laser pulse, and the role of higher-order corrections to the electric dipole approximation is studied systematically. The main findings are that higher-order corrections beyond the leading first-order term, to a good approximation, can be neglected for all intensities within the nonrelativistic regime, provided the pulse duration is not too long. This means that the effect of second- and higher-order corrections only needs to be accounted for when entering the relativistic regime, within the scope of the Dirac equation. It is further found that the leading first-order correction to the dipole approximation has a great impact on the angular emission pattern of the low-energy photoelectrons.

  9. Preparation of nanowire specimens for laser-assisted atom probe tomography

    NASA Astrophysics Data System (ADS)

    Blumtritt, H.; Isheim, D.; Senz, S.; Seidman, D. N.; Moutanabbir, O.

    2014-10-01

    The availability of reliable and well-engineered commercial instruments and data analysis software has led to development in recent years of robust and ergonomic atom-probe tomographs. Indeed, atom-probe tomography (APT) is now being applied to a broader range of materials classes that involve highly important scientific and technological problems in materials science and engineering. Dual-beam focused-ion beam microscopy and its application to the fabrication of APT microtip specimens have dramatically improved the ability to probe a variety of systems. However, the sample preparation is still challenging especially for emerging nanomaterials such as epitaxial nanowires which typically grow vertically on a substrate through metal-catalyzed vapor phase epitaxy. The size, morphology, density, and sensitivity to radiation damage are the most influential parameters in the preparation of nanowire specimens for APT. In this paper, we describe a step-by-step process methodology to allow a precisely controlled, damage-free transfer of individual, short silicon nanowires onto atom probe microposts. Starting with a dense array of tiny nanowires and using focused ion beam, we employed a sequence of protective layers and markers to identify the nanowire to be transferred and probed while protecting it against Ga ions during lift-off processing and tip sharpening. Based on this approach, high-quality three-dimensional atom-by-atom maps of single aluminum-catalyzed silicon nanowires are obtained using a highly focused ultraviolet laser-assisted local electrode atom probe tomograph.

  10. Exploring Ramsey-coherent population trapping atomic clock realized with pulsed microwave modulated laser

    SciTech Connect

    Yang, Jing; Yun, Peter; Tian, Yuan; Tan, Bozhong; Gu, Sihong

    2014-03-07

    A scheme for a Ramsey-coherent population trapping (CPT) atomic clock that eliminates the acousto-optic modulator (AOM) is proposed and experimentally studied. Driven by a periodically microwave modulated current, the vertical-cavity surface-emitting laser emits a continuous beam that switches between monochromatic and multichromatic modes. Ramsey-CPT interference has been studied with this mode-switching beam. In eliminating the AOM, which is used to generate pulsed laser in conventional Ramsey-CPT atomic clock, the physics package of the proposed scheme is virtually the same as that of a conventional compact CPT atomic clock, although the resource budget for the electronics will slightly increase as a microwave switch should be added. By evaluating and comparing experimentally recorded signals from the two Ramsey-CPT schemes, the short-term frequency stability of the proposed scheme was found to be 46% better than the scheme with AOM. The experimental results suggest that the implementation of a compact Ramsey-CPT atomic clock promises better frequency stability.

  11. Millikelvin Reactive Collisions between Sympathetically Cooled Molecular Ions and Laser-Cooled Atoms in an Ion-Atom Hybrid Trap

    NASA Astrophysics Data System (ADS)

    Hall, Felix H. J.; Willitsch, Stefan

    2012-12-01

    We report on a study of cold reactive collisions between sympathetically cooled molecular ions and laser-cooled atoms in an ion-atom hybrid trap. Chemical reactions were studied at average collision energies ?Ecoll?/kB?20mK, about 2 orders of magnitude lower than has been achieved in previous experiments with molecular ions. Choosing N2++Rb as a prototypical system, we find that the reaction rate is independent of the collision energy within the range studied, but strongly dependent on the internal state of Rb. Highly efficient charge exchange four times faster than the Langevin rate was observed with Rb in the excited (5p) P3/22 state. This observation is rationalized by a capture process dominated by the charge-quadrupole interaction and a near resonance between the entrance and exit channels of the system. Our results provide a test of classical models for reactions of molecular ions at the lowest energies reached thus far.

  12. Photoinduced Electron and H-atom Transfer Reactions of Xanthone by Laser Flash Photolysis

    NASA Astrophysics Data System (ADS)

    Wang, Jin-ting; Pan, Yang; Zhang, Li-min; Yu, Shu-qin

    2007-08-01

    The property of the lowest excited triplet states of xanthone in acetonitrile was investigated using time-resolved laser flash photolysis at 355 nm. The transient absorption spectra and the quenching rate constants (kq) of the excited xanthone with several amines were determined. Good correlation between lgkq and the driving force of the reactions suggests the electron transfer mechanism, except aniline and 3-nitroaniline (3-NO2-A) which showed energy transfer mechanism. With the appearance of ketyl radical, hydrogen atom transfer also happened between xanthone and dimethyl-p-toluidine, 3,5,N,N-tetramethylaniline, N,N-dimethylaniline, and triethylamine. Therefore, both electron transfer and H-atom transfer occured in these systems. Great discrepancies of kq values were discovered in H-atom abstraction reactions for alcohols and phenols, which can be explained by different abstraction mechanisms. The quenching rate constants between xanthone and alcohols correlate well with the ?-C-H bonding energy of alcohols.

  13. Evidence for unnatural-parity contributions to electron-impact ionization of laser-aligned atoms

    NASA Astrophysics Data System (ADS)

    Armstrong, G. S. J.; Colgan, J.; Pindzola, M. S.; Amami, S.; Madison, D. H.; Pursehouse, J.; Nixon, K. L.; Murray, A. J.

    2015-09-01

    Recent measurements have examined the electron-impact ionization of excited-state laser-aligned Mg atoms. In this work we show that the ionization cross section arising from the geometry where the aligned atom is perpendicular to the scattering plane directly probes the unnatural parity contributions to the ionization amplitude. The contributions from natural parity partial waves cancel exactly in this geometry. Our calculations resolve the discrepancy between the nonzero measured cross sections in this plane and the zero cross section predicted by distorted-wave approaches. We demonstrate that this is a general feature of ionization from p -state targets by additional studies of ionization from excited Ca and Na atoms.

  14. RETRACTED Studies on the effect of instability of divergence, pointing and amplitude of green and yellow radiation pulses of copper vapour laser in second harmonic and sum frequency conversion

    NASA Astrophysics Data System (ADS)

    Prakash, Om; Mahakud, Ramakanta; Nakhe, Shankar V.; Dixit, Sudhir K.

    2013-02-01

    This paper presents the effect of single pulse stability of divergence angle, beam pointing angle and amplitude of green and yellow radiation pulses of an unstable resonator copper vapour laser (CVL) oscillator in the sum frequency mixing and second harmonic. The conversion efficiency of sum frequency generation was lower compared to second harmonic processes despite larger fundamental power being used in sum frequency experiments. However the net UV power obtained at the sum frequency was higher than both of the second harmonic UV frequencies. Lower SFG conversion efficiency (12.4%271 nm) compared to SHG (16.7%255 nm, 14.5%289 nm) of individual CVL radiations is attributed to difference in single pulse stability of beam pointing, divergence and amplitude fluctuation of both CVL radiations in addition to commonly known fact of spatio-temporal mis-match. At the same fundamental input power (2.7 W), higher SH conversion efficiency of yellow (12.7%) compared to green (11.0%) is attributed to its better single pulse stability of beam pointing and divergence.

  15. Laser microdissection of metaphase chromosomes and characterization by atomic force microscopy

    NASA Astrophysics Data System (ADS)

    Thalhammer, Stefan; Stark, Robert W.; Schuetze, Karin; Wienberg, Johannes; Heckl, Wolfgang M.

    1997-01-01

    A new experimental setup has been constructed in which a UV laser microbeam and atomic force microscopy (AFM) have been combined on an inverted microscope in order to manipulate and visualize chromosomes with high resolution. The laser beam has been used to dissect Muntjak metaphase chromosomes and was aimed to optimize the physical size of the cuts. The capability of the AFM to visualize biological materials with relative ease has been used to characterize the microdissected chromosomes. This work demonstrates that chromosome fiber material can be removed completely at the cut site using appropriate laser power. The minimum cut size achieved with a 337-nm nitrogen UV laser was between 600 and 800 nm. The smallest distance between the cuts was around 500 nm, corresponding to the finest probe for further biochemical use after physical translocation such as the polymerase chain reaction. Limitations on minimizing the cut size due to diffraction-limited focusing and the effects of laser ablation of biomaterial are discussed.

  16. In situ laser ablation sampling for inductively coupled plasma atomic emission spectrometry

    NASA Astrophysics Data System (ADS)

    Liu, X. R.; Horlick, Gary

    1995-06-01

    In this report an in situ laser ablation system for inductively coupled plasma-atomic emission spectrometry (ICP-AES) is described that eliminates the aerosol transport step associated with conventional laser ablation sample introduction systems. The concept of this system is to place the sample inside the ICP torch immediately below the plasma discharge. This can be accomplished using a direct sample insertion system. The laser is then focused on the sample by a lens placed above the plasma and ablated material is directly injected into the plasma. For ablation with a Q-switched Nd-YAG laser (single pulse) this results in an emission signal that has a duration of about 0.7 ms, in contrast to a conventional ablation system where signal durations are measured in seconds. This translates to a dramatic improvement in sensitivity for the in situ system over a conventional system. Measurement considerations are discussed, results are presented for the analysis of Al and steel samples, and the in situ system is briefly compared with a conventional laser ablation system.

  17. Live atomic force microscopy imaging of laser microbeam assisted cellular microsurgery

    NASA Astrophysics Data System (ADS)

    Ingle, Ninad; Mohanty, Samarendra K.

    2011-02-01

    Ultrafast laser microbeam is finding growing usage in causing highly localized damage to cellular structures. This has specifically enhanced efficiency of optoporation-injection of exogenous impermeable substances into the cell by transient pore formation. However, kinetics of laser microbeam induced pore formation and sealing of membrane has not been visualized at nanoscale resolution. Here, we report realization of live atomic force microscopy (AFM) imaging of ultrafast tunable Ti: Sapphire laser microbeam assisted cellular microsurgery. AFM imaging was carried out using Nanonics Multiview system in parallel to exposure of the laser beam. Red blood cells (RBCs) were chosen as cellular model for micro-surgery due to their smooth surface topography. The transparent nature of the Nanonics fiber-optic AFM cantilever allowed simultaneous bright field/phase contrast imaging of the RBC. Measurement of pore size by AFM revealed true pore size as a function of laser exposure duration in contrast to phase contrast imaging. Further, AFM imaging of live cells showed fine topography of sealed pores that could not be comprehended from conventional microscopy.

  18. Arc Jet Flow Properties Determined from Laser- Induced Fluorescence of Atomic Species

    NASA Technical Reports Server (NTRS)

    Fletcher, Douglas G.

    1997-01-01

    Flow property measurements that were recently acquired in the Ames Research Center Aerodynamic Heating Facility (AHF) arc jet using two-photon Laser-Induced Fluorescence (LIF) of atomic nitrogen and oxygen are reported. The measured properties, which include velocity, translational temperature, and species concentration, cover a wide range of facility operation for the 30 cm nozzle. During the tests, the arc jet pressure and input stream composition were maintained at fixed values and the arc current was varied to vary the flow enthalpy. As part of this ongoing effort, a measurement of the two-photon absorption coefficient for the 3p4D(left arrow)2p4S transition of atomic nitrogen was performed, and the measured value is used to convert the relative concentration measurements to absolute values. A flow reactor is used to provide a known temperature line shape profile to deconvolve the laser line width contribution to the translational temperature measurements. Results from the current experiments are compared with previous results obtained using NO-beta line profiles at room temperature and the problem of multimode laser oscillation and its impact on the two-photon excitation line shape are discussed. One figure is attached, and this figure show relative N atom concentration measurements as a function of the arc power. Other measurements have already been acquired and analyzed. The arc jet flow facilities are heavily used in thermal protection material development and evaluation. All hypersonic flight and planetary atmospheric entry vehicles will use materials tested in these arc jet facilities. This poster represents an application of laser-spectroscopic measurements in an important test facility.

  19. Arcjet Flow Properties Determined from Laser-Induced Fluorescence of Atomic Species

    NASA Technical Reports Server (NTRS)

    Fletcher, Douglas G.

    1997-01-01

    Flow property measurements that were recently acquired in the Ames Research Center Aerodynamic Heating Facility (AHF) arc jet using two-photon Laser-Induced Fluorescence (LIF) of atomic nitrogen and oxygen are reported. The measured properties, which include velocity, translational temperature, and species concentration, cover a wide range of facility operation for the 30 cm nozzle. During the tests, the arc jet pressure and input stream composition were maintained at fixed values and the arc current was varied to vary the flow enthalpy. As part of this ongoing effort, a measurement of the two-photon absorption coefficient for the 3p4D<-2p4S transition of atomic nitrogen was performed, and the measured value is used to convert the relative concentration measurements to absolute values. A flow reactor is used to provide a known temperature line shape profile to deconvolve the laser line width contribution to the translational temperature measurements. Results from the current experiments are compared with previous results obtained using NO-Beta line profiles at room temperature and the problem of multimode laser oscillation and its impact on the two-photon excitation line shape are discussed. One figure is attached, and this figure shows relative N atom concentration measurements as a function of the arc power. Other measurements have already been acquired and analyzed. This poster represents an application of laser-spectroscopic measurements in an important test facility. The arc jet flow facilities are heavily used in thermal protection material development and evaluation. All hypersonic flight and planetary atmospheric entry vehicles will use materials tested in these arc jet facilities.

  20. EFFECTS OF LASER RADIATION ON MATTER. LASER PLASMA: Characteristics of the scattering of neutral atoms by two counterpropagating pulsed optical fields

    NASA Astrophysics Data System (ADS)

    Grinchuk, V. A.; Grishina, I. A.; Kuzin, E. F.; Nagaeva, M. L.; Ryabenko, G. A.; Yakovlev, V. P.

    1994-04-01

    The scattering of neutral sodium atoms by a strong field of two counterpropagating (incident on and reflected from a mirror) short laser pulses was used in an experimental investigation of a stimulated radiation pressure. The reasons for the anomalous frequency structure in the scattering of atoms were identified. The oscillatory nature of the dependence of the scattering on the detuning from resonance was found to be significant in strong laser radiation fields. The oscillation period depended on the distance between the reflecting mirror and the atomic beam.

  1. A Simple LIBS (Laser-Induced Breakdown Spectroscopy) Laboratory Experiment to Introduce Undergraduates to Calibration Functions and Atomic Spectroscopy

    ERIC Educational Resources Information Center

    Chinni, Rosemarie C.

    2012-01-01

    This laboratory experiment introduces students to a different type of atomic spectroscopy: laser-induced breakdown spectroscopy (LIBS). LIBS uses a laser-generated spark to excite the sample; once excited, the elemental emission is spectrally resolved and detected. The students use LIBS to analyze a series of standard synthetic silicate samples…

  2. A semiclassical study of laser-induced atomic fluorescence from Na2, K2 and NaK

    NASA Technical Reports Server (NTRS)

    Yuan, J.-M.; Bhattacharyya, D. K.; George, T. F.

    1982-01-01

    A semiclassical treatment of laser-induced atomic fluorescence for the alkali-dimer systems Na2, K2 and NaK is presented. The variation of the fluorescence intensity with the frequency of the exciting laser photon is studied and a comparison of theoretical results with a set of experimental data is presented.

  3. A Simple LIBS (Laser-Induced Breakdown Spectroscopy) Laboratory Experiment to Introduce Undergraduates to Calibration Functions and Atomic Spectroscopy

    ERIC Educational Resources Information Center

    Chinni, Rosemarie C.

    2012-01-01

    This laboratory experiment introduces students to a different type of atomic spectroscopy: laser-induced breakdown spectroscopy (LIBS). LIBS uses a laser-generated spark to excite the sample; once excited, the elemental emission is spectrally resolved and detected. The students use LIBS to analyze a series of standard synthetic silicate samples

  4. Nuclear-driven flashlamp pumping of the atomic iodine laser. Final report

    SciTech Connect

    Miley, G.H.

    1992-03-01

    This report is a study of the atomic iodine laser pumped with nuclear- excited XeBr fluorescence. Preliminary experiments, conducted in the TRIGA reactor investigated the fluorescence of the excimer XeBr under nuclear pumping with {sup 10}B and {sup 3}He, for use as a flashlamp gas to stimulate the laser. These measurements included a determination of the fluorescence efficiency (light emitted in the wavelength region of interest, divided by energy deposited in the gas) of XeBr under nuclear pumping, with varying excimer mixtures. Maximum fluorescence efficiencies were approximately 1%. In order to better understand XeBr under nuclear excitation, a kinetics model of the system was prepared. The model generated the time-dependant concentrations of 20 reaction species for three pulse sizes, a TRIGA pulse, a fast burst reactor pulse, and an e-beam pulse. The modeling results predicted fluorescence efficiencies significantly higher (peak efficiencies of approximately 10%) than recorded in the fluorescence experiments. The cause of this discrepancy was not fully determined. A ray tracing computer model was also prepared to evaluate the efficiency with which nuclear-induced fluorescence generated in one cavity of a laser could be coupled into another cavity containing an iodine lasant. Finally, an experimental laser cell was constructed to verify that nuclear-induced XeBr fluorescence could be used to stimulate a laser. Lasing was achieved at 1.31 micron in the TRIGA using C{sub 3}F{sub 7}I, a common iodine lasant. Peak laser powers were approximately 20 mW. Measured flashlamp pump powers at threshold agreed well with literature values, as did lasant pressure dependency on laser operation.

  5. GaAlAs laser diode frequency locked at the D/sub 2/ line of Cs atoms in an atomic beam

    SciTech Connect

    Wang, D.; Xie, L.; Wang, Y.

    1988-10-01

    A GaAlAs laser diode has been locked to the D/sub 2/ transition of Cs atoms in an atomic beam. Measured frequency stabilities are 1 x 10/sup -10/ (0.1 sec), 8.4 x 10/sup -12/ (1 sec), 2.2 x 10/sup -12/ (10 sec), and 7.8 x 10/sup -13/ (100 sec). This system has been successfully applied to an optically pumped Cs-beam frequency standard.

  6. Absorption spectroscopy characterization measurements of a laser-produced Na atomic beam

    SciTech Connect

    Ching, C.H.; Bailey, J.E.; Lake, P.W.; Filuk, A.B.; Adams, R.G.; McKenney, J.

    1996-06-01

    This work describes a pulsed Na atomic beam source developed for spectroscopic diagnosis of a high-power ion diode on the Particle Beam Fusion Accelerator II. The goal is to produce a {approximately} 10{sup 12}-cm{sup {minus}3}-density Na atomic beam that can be injected into the diode acceleration gap to measure electric and magnetic fields from the Stark and Zeeman effects through laser-induced-fluorescence or absorption spectroscopy. A {approximately} 10 ns fwhm, 1.06 {micro}m, 0.6 J/cm{sup 2} laser incident through a glass slide heats a Na-bearing thin film, creating a plasma that generates a sodium vapor plume. A {approximately} 1 {micro}sec fwhm dye laser beam tuned to 5,890 {angstrom} is used for absorption measurement of the Na I resonant doublet by viewing parallel to the film surface. The dye laser light is coupled through a fiber to a spectrograph with a time-integrated CCD camera. A two-dimensional mapping of the Na vapor density is obtained through absorption measurements at different spatial locations. Time-of-flight and Doppler broadening of the absorption with {approximately} 0.1 {angstrom} spectral resolution indicate that the Na neutral vapor temperature is about 0.5 to 2 eV. Laser-induced-fluorescence from {approximately} 1 {times} 10{sup 12}-cm{sup {minus}3} Na I 3s-3p lines observed with a streaked spectrograph provides a signal level sufficient for {approximately} 0.06 {angstrom} wavelength shift measurements in a mock-up of an ion diode experiment.

  7. Near resonant absorption by atoms in intense fluctuating laser fields. Final report

    SciTech Connect

    Smith, S.J.

    1994-01-01

    The objective of this program was to make quantitative measurements of the effects of higher-order phase/frequency correlations in a laser beam on nonlinear optical absorption processes in atoms. The success of this program was due in large part to a unique experimental capability for modulating the extracavity beam of a stabilized ({approx_lt}200 kHz) continuous-wave laser with statistically-well-characterized stochastic phase (or frequency) fluctuations, in order to synthesize laser bandwidths to {approximately}20 MHz (depending on noise amplitude), with profiles variable between Gaussian and Lorentzian (depending on noise bandwidth). Laser driven processes investigated included the following: (1) the optical Autler-Towns effect in the 3S{sub 1/2} (F = 2, M{sub F} = 2) {yields} 3P{sub 3/2} (F = 3, M{sub F} = 3) two- level Na resonance, using a weak probe to the 4D{sub 5/2} level; (2) the variance and spectra of fluorescence intensity fluctuations in the two-level Na resonance; (3) the Hanle effect in the {sup 1}S{sub 0} {minus} {sup 3}P{sub 1}, transition at {lambda} = 555.6 nm in {sup 174} Yb; (4) absorption (and gain) of a weak probe, when the probe is a time-delayed replica of the resonant (with the two-level Na transition) pump laser; and (5) four-wave-mixing in a phase-conjugate geometry, in a sodium cell, and, finally, in a diffuse atomic sodium beam. The experimental results from these several studies have provided important confirmation of advanced theoretical methods.

  8. QED Theory of Radiation Emission and Absorption Lines for Atoms and Ions in a Strong Laser Field

    SciTech Connect

    Glushkov, A. V.

    2008-10-22

    The results of numerical calculating the multi-photon resonance shift and width for transition 6S-6F in the atom of Cs (wavelength 1059nm) in a laser pulse of the Gaussian and soliton-like shapes are presented. QED theory of radiation atomic lines is used.

  9. Strong Gaussian standing wave: an efficient tool for laser cooling of atomic beams

    NASA Astrophysics Data System (ADS)

    Zemanek, Pavel; Foot, Christopher J.

    1998-01-01

    We propose an efficient method of cooling atoms in a strong Gaussian standing wave. The steep gradients of the atomic potential energy give rise to large dipole forces, which can be much stronger than the maximum radiation pressure force and can therefore stop atoms in a much shorter distance. We have simulated the cooling process using a semi-classical Monte- Carlo method, which includes the radial motion, in addition to the motion along the beams. Both motions are calculated directly without separation the dynamics into force and diffusion terms. To cool a large range of atomic velocities the frame in which the standing wave is at rest was swept by changing the frequencies of the counter-propagating beams, in a similar way to the well-known chirp cooling technique using the radiation pressure force. If the curvature of Gaussian beams far from beam waist is employed the radial motion and velocities can be reduced even for the blue detuning comparing to the near waist case. The simulations show that it is possible to stop caesium atoms in a distance of several centimeters (the exact value depends on the laser power, beam waist radius and acceptable chirping force) starting from the most probable velocity at room temperature. Narrower radial and wider axial velocity distribution was obtained for red detuning comparing with the blue one.

  10. Hook spectroscopy as an atomic number density diagnostic applied to laser-ablated copper plasmas

    SciTech Connect

    Zerkle, D.K.; Sappey, A.D.; Gamble, T.K.

    1993-11-01

    Hook spectroscopy has been used to determine the absolute number density of ground state copper atoms in laser-ablated plasma plumes. An ablation laser power flux of {approximately} 1.5 GW/cm{sup 2} is applied to a solid copper target in a background gas, producing a plasma plume suitable for studying homogeneous copper vapor condensation. Density is measured at post-ablation time delays ranging from 10 {mu}s to 3 ms with 25 torr of argon as the background gas. Planar laser-induced fluorescence (PLEF) images containing relative density information are used in conjunction with the hook spectra to resolve spatially the absolute density within the plume. Copper atom densities thus measured ranged from 1.9 {times} 10{sup 15} cm{sup {minus}3} at a delay of 10 {mu}s to 2.7 {times} 10{sup 13} cm{sup {minus}3} at 3 ms delay in 25 torr of argon The decrease in density is due to the condensation of copper vapor to form fine particulate. As a combustion diagnostic, the hook method may prove extremely useful for the determination of metal impurity density in coal fired flames as well as a single -- shot OH density and temperature diagnostic.

  11. Qualitative tissue differentiation by analysing the intensity ratios of atomic emission lines using laser induced breakdown spectroscopy (LIBS): prospects for a feedback mechanism for surgical laser systems.

    PubMed

    Kanawade, Rajesh; Mahari, Fanuel; Klämpfl, Florian; Rohde, Maximilian; Knipfer, Christian; Tangermann-Gerk, Katja; Adler, Werner; Schmidt, Michael; Stelzle, Florian

    2015-01-01

    The research work presented in this paper focuses on qualitative tissue differentiation by monitoring the intensity ratios of atomic emissions using 'Laser Induced Breakdown Spectroscopy' (LIBS) on the plasma plume created during laser tissue ablation. The background of this study is to establish a real time feedback control mechanism for clinical laser surgery systems during the laser ablation process. Ex-vivo domestic pig tissue samples (muscle, fat, nerve and skin) were used in this experiment. Atomic emission intensity ratios were analyzed to find a characteristic spectral line for each tissue. The results showed characteristic elemental emission intensity ratios for the respective tissues. The spectral lines and intensity ratios of these specific elements varied among the different tissue types. The main goal of this study is to qualitatively and precisely identify different tissue types for tissue specific laser surgery. PMID:24376030

  12. Effects of laser linewidth on an effective method for excitation in three-level atomic systems by two optimally detuned counterpropagating pulsed lasers

    SciTech Connect

    Gupta, G. P.; Suri, B. M.

    2008-02-15

    Population transfer in three-level atomic systems with high efficiency and selectivity is desirable for practical applications in laser spectroscopy, trace analysis, and isotope separation. The effective excitation method for achieving this population transfer in three-level atomic systems using coherent two-photon excitation with two optimally detuned counterpropagating pulsed lasers, initially investigated analytically assuming monochromatic lasers and Doppler-free systems, is studied numerically by solving the density matrix equations incorporating finite laser linewidth and effective Doppler width. A three-level Yb system is chosen for illustration of numerical results. The effects of laser linewidth and effective Doppler width on the values of optimal detunings and maximum third-level population are discussed.

  13. Nonlinear spectroscopy of Sr atoms in an optical cavity for laser stabilization

    NASA Astrophysics Data System (ADS)

    Christensen, Bjarke T. R.; Henriksen, Martin R.; Schffer, Stefan A.; Westergaard, Philip G.; Tieri, David; Ye, Jun; Holland, Murray J.; Thomsen, Jan W.

    2015-11-01

    We study the nonlinear interaction of a cold sample of 88Sr atoms coupled to a single mode of a low finesse optical cavity in the so-called bad cavity limit, and we investigate the implications for applications to laser stabilization. The atoms are probed on the weak intercombination line |5 s21S0>-|5 s 5 p 3P1> at 689 nm in a strongly saturated regime. Our measured observables include the atomic induced phase shift and absorption of the light field transmitted through the cavity represented by the complex cavity transmission coefficient. We demonstrate high signal-to-noise-ratio measurements of both quadraturesthe cavity transmitted phase and absorptionby employing frequency modulation (FM) spectroscopy (noise-immune cavity-enhanced optical-heterodyne molecular spectroscopy). We also show that when FM spectroscopy is employed in connection with a cavity locked to the probe light, observables are substantially modified compared to the free-space situation in which no cavity is present. Furthermore, the nonlinear dynamics of the phase dispersion slope is experimentally investigated, and the optimal conditions for laser stabilization are established. Our experimental results are compared to state-of-the-art cavity QED theoretical calculations.

  14. Application of Coulomb wave function discrete variable representation to atomic systems in strong laser fields

    NASA Astrophysics Data System (ADS)

    Peng, Liang-You; Starace, Anthony F.

    2006-10-01

    We present an efficient and accurate grid method for solving the time-dependent Schrdinger equation for an atomic system interacting with an intense laser pulse. Instead of the usual finite difference (FD) method, the radial coordinate is discretized using the discrete variable representation (DVR) constructed from Coulomb wave functions. For an accurate description of the ionization dynamics of atomic systems, the Coulomb wave function discrete variable representation (CWDVR) method needs three to ten times fewer grid points than the FD method. The resultant grid points of the CWDVR are distributed unevenly so that one has a finer grid near the origin and a coarser one at larger distances. The other important advantage of the CWDVR method is that it treats the Coulomb singularity accurately and gives a good representation of continuum wave functions. The time propagation of the wave function is implemented using the well-known Arnoldi method. As examples, the present method is applied to multiphoton ionization of both the H atom and the H- ion in intense laser fields. The short-time excitation and ionization dynamics of H by an abruptly introduced static electric field is also investigated. For a wide range of field parameters, ionization rates calculated using the present method are in excellent agreement with those from other accurate theoretical calculations.

  15. Optical field ionization of atoms and ions using ultrashort laser pulses

    SciTech Connect

    Fittinghoff, D.N.

    1993-12-01

    This dissertation research is an investigation of the strong optical field ionization of atoms and ions by 120-fs, 614-run laser pulses and 130-fs, 800-nm laser pulses. The experiments have shown ionization that is enhanced above the predictions of sequential tunneling models for He{sup +2}, Ne{sup +2} and Ar{sup +2}. The ion yields for He{sup +l}, Ne{sup +l} and Ar{sup +l} agree well with the theoretical predictions of optical tunneling models. Investigation of the polarization dependence of the ionization indicates that the enhancements are consistent with a nonsequential ionization mechanism in which the linearly polarized field drives the electron wavefunction back toward the ion core and causes double ionization through inelastic e-2e scattering. These investigations have initiated a number of other studies by other groups and are of current scientific interest in the fields of high-irradiance laser-matter interactions and production of high-density plasmas. This work involved: (1) Understanding the characteristic nature of the ion yields produced by tunneling ionization through investigation of analytic solutions for tunneling at optical frequencies. (2) Extensive characterization of the pulses produced by 614-nm and 800-ran ultrashort pulse lasers. Absolute calibration of the irradiance scale produced shows the practicality of the inverse problem--measuring peak laser irradiance using ion yields. (3) Measuring the ion yields for three noble gases using linear, circular and elliptical polarizations of laser pulses at 614-nm and 800-nm. The measurements are some of the first measurements for pulse widths as low as 120-fs.

  16. Laser cooling and trapping of atomic particles. January 1970-September 1989 (Citations from the NTIS data base). Report for Jan 70-Sep 89

    SciTech Connect

    Not Available

    1989-11-01

    This bibliography contains citations concerning theory and experiments on laser cooling and laser trapping of neutral atoms and atomic ions. Atoms and ions are cooled by laser radiation pressure to very low Kelvin temperatures and confined in electromagnetic traps with very high density. Atomic particles discussed include sodium atoms, mercury ions, beryllium ions, magnesium ions, and hydrogen. Applications include high performance spectroscopy, atomic clocks, microwave and optical frequency standards, relativistic neutral particle beam weapons, exotic fuels, cooling of electron beams, and space propulsion. (Contains 97 citations fully indexed and including a title list.)

  17. Influence of instrument conditions on the evaporation behavior of uranium dioxide with UV laser-assisted atom probe tomography

    NASA Astrophysics Data System (ADS)

    Valderrama, B.; Henderson, H. B.; Gan, J.; Manuel, M. V.

    2015-04-01

    Atom probe tomography (APT) provides the ability to detect subnanometer chemical variations spatially, with high accuracy. However, it is known that compositional accuracy can be affected by experimental conditions. A study of the effect of laser energy, specimen base temperature, and detection rate is performed on the evaporation behavior of uranium dioxide (UO2). In laser-assisted mode, tip geometry and standing voltage also contribute to the evaporation behavior. In this investigation, it was determined that modifying the detection rate and temperature did not affect the evaporation behavior as significantly as laser energy. It was also determined that three laser evaporation regimes are present in UO2. Very low laser energy produces a behavior similar to DC-field evaporation, moderate laser energy produces the desired laser-assisted field evaporation characteristic and high laser energy induces thermal effects, negatively altering the evaporation behavior. The need for UO2 to be analyzed under moderate laser energies to produce accurate stoichiometry distinguishes it from other oxides. The following experimental conditions providing the best combination of mass resolving power, accurate stoichiometry, and uniform evaporation behavior: 50 K, 10 pJ laser energy, a detection rate of 0.003 atoms per pulse, and a 100 kHz repetition rate.

  18. Influence of instrument conditions on the evaporation behavior of uranium dioxide with UV laser-assisted atom probe tomography

    SciTech Connect

    Valderrama, B.; Henderson, H.B.; Gan, J.; Manuel, M.V.

    2015-04-01

    Atom probe tomography (APT) provides the ability to detect subnanometer chemical variations spatially, with high accuracy. However, it is known that compositional accuracy can be affected by experimental conditions. A study of the effect of laser energy, specimen base temperature, and detection rate is performed on the evaporation behavior of uranium dioxide (UO2). In laser-assisted mode, tip geometry and standing voltage also contribute to the evaporation behavior. In this investigation, it was determined that modifying the detection rate and temperature did not affect the evaporation behavior as significantly as laser energy. It was also determined that three laser evaporation regimes are present in UO2. Very low laser energy produces a behavior similar to DC-field evaporation, moderate laser energy produces the desired laser-assisted field evaporation characteristic and high laser energy induces thermal effects, negatively altering the evaporation behavior. The need for UO2 to be analyzed under moderate laser energies to produce accurate stoichiometry distinguishes it from other oxides. The following experimental conditions providing the best combination of mass resolving power, accurate stoichiometry, and uniform evaporation behavior: 50 K, 10 pJ laser energy, a detection rate of 0.003 atoms per pulse, and a 100 kHz repetition rate.

  19. Atom Specific Ultrafast Surface Chemistry using a Soft X-ray Laser

    NASA Astrophysics Data System (ADS)

    Nilsson, Anders

    2014-03-01

    Catalysis is central for many chemical energy transformations that occur at interfaces. One of the dreams is to follow catalytic reactions in real time from reactants over various intermediates to products. The prospective for the study of chemical reactions on surfaces using X-ray free-electron lasers (Linac Coherent Light Source, or LCLS, at SLAC National Accelerator Laboratory) will be presented. We induced the hot electron and phonon mediated excitation of adsorbates on Ru(0001) with synchronized excitation by a femtosecond optical laser pulse. We have followed the ultrafast evolution of the bond distortions, weakening and breaking, using x-ray absorption spectroscopy and x ray emission spectroscopy resonantly tuned to the oxygen core level with ultrashort x-ray pulses delivered from LCLS. We can directly follow the time evolution of the molecular orbitals in an atom-specific way on a subpicosecond timescale. Three examples will be shown CO desorption, Oxygen activation and CO oxidation on Ru(0001).

  20. Relativistic electronic dressing in laser-assisted ionization of atomic hydrogen by electron impact

    SciTech Connect

    Attaourti, Y.; Taj, S.

    2004-06-01

    Within the framework of the coplanar binary geometry where it is justified to use plane wave solutions for the study of the (e,2e) reaction and in the presence of a circularly polarized laser field, we introduce as a first step the Dirac-Volkov plane wave Born approximation 1 where we take into account only the relativistic dressing of the incident and scattered electrons. Then, we introduce the Dirac-Volkov plane wave Born approximation 2 where we take totally into account the relativistic dressing of the incident, scattered, and ejected electrons. We then compare the corresponding triple differential cross sections for laser-assisted ionization of atomic hydrogen by electron impact both for the nonrelativistic and the relativistic regime.

  1. Generation of neutral atomic beams utilizing photodetachment by high power diode laser stacks

    NASA Astrophysics Data System (ADS)

    O'Connor, A. P.; Grussie, F.; Bruhns, H.; de Ruette, N.; Koenning, T. P.; Miller, K. A.; Savin, D. W.; Stützel, J.; Urbain, X.; Kreckel, H.

    2015-11-01

    We demonstrate the use of high power diode laser stacks to photodetach fast hydrogen and carbon anions and produce ground term neutral atomic beams. We achieve photodetachment efficiencies of ˜7.4% for H- at a beam energy of 10 keV and ˜3.7% for C- at 28 keV. The diode laser systems used here operate at 975 nm and 808 nm, respectively, and provide high continuous power levels of up to 2 kW, without the need of additional enhancements like optical cavities. The alignment of the beams is straightforward and operation at constant power levels is very stable, while maintenance is minimal. We present a dedicated photodetachment setup that is suitable to efficiently neutralize the majority of stable negative ions in the periodic table.

  2. Generation of neutral atomic beams utilizing photodetachment by high power diode laser stacks.

    PubMed

    O'Connor, A P; Grussie, F; Bruhns, H; de Ruette, N; Koenning, T P; Miller, K A; Savin, D W; Stützel, J; Urbain, X; Kreckel, H

    2015-11-01

    We demonstrate the use of high power diode laser stacks to photodetach fast hydrogen and carbon anions and produce ground term neutral atomic beams. We achieve photodetachment efficiencies of ∼7.4% for H(-) at a beam energy of 10 keV and ∼3.7% for C(-) at 28 keV. The diode laser systems used here operate at 975 nm and 808 nm, respectively, and provide high continuous power levels of up to 2 kW, without the need of additional enhancements like optical cavities. The alignment of the beams is straightforward and operation at constant power levels is very stable, while maintenance is minimal. We present a dedicated photodetachment setup that is suitable to efficiently neutralize the majority of stable negative ions in the periodic table. PMID:26628128

  3. a Study of Collisional Deactivation of Two-Photon Laser Excited Xenon Atoms

    NASA Astrophysics Data System (ADS)

    Bowering, Norbert Rudolf

    Xenon atoms and collision pairs of the 6p manifold are excited selectively by two-photon excitation using a computer-controlled frequency doubled narrow-band dye laser. The laser-induced fluorescence of the excited states is analyzed with spectral and temporal resolution. The deactivation characteristics of directly excited states and of states populated by cascade is studied by measuring the lifetimes and total quench rates. State-to-state reaction rates are obtained by combining these results with time -integrated data. The line shapes are analyzed in detail to study the half-collision dynamics. Selective quenching due to potential crossings is observed as xenon pairs are excited during a collision.

  4. Laser-ranging long-baseline differential atom interferometers for space

    NASA Astrophysics Data System (ADS)

    Chiow, Sheng-wey; Williams, Jason; Yu, Nan

    2015-12-01

    High-sensitivity differential atom interferometers (AIs) are promising for precision measurements in science frontiers in space, including gravity-field mapping for Earth science studies and gravitational wave detection. Difficulties associated with implementing long-baseline differential AIs have previously included the need for a high optical power, large differential Doppler shifts, and narrow dynamic range. We propose a configuration of twin AIs connected by a laser-ranging interferometer (LRI-AI) to provide precise information of the displacements between the two AI reference mirrors and also to phase-lock the two independent interferometer lasers over long distances, thereby drastically improving the practical feasibility of long-baseline differential AI measurements. We show that a properly implemented LRI-AI can achieve equivalent functionality to the conventional differential AI measurement configuration.

  5. Application of Coulomb Wave Function DVR to Atomic Systems in Strong Laser Fields

    NASA Astrophysics Data System (ADS)

    Peng, Liang-You; Starace, Anthony F.

    2006-05-01

    We present an efficient and accurate grid method for solving the time-dependent Schr"odinger equation (TDSE) for atomic systems interacting with short laser pulses. The radial part of the wave function is expanded in a DVR (Discrete Variable Representation) basis constructed from the positive energy Coulomb wave function. The time propagation of the wave function is implemented using the well-known Arnoldi method. Compared with the usual finite difference (FD) discretization scheme for the radial coordinate, this method requires fewer grid points and handles naturally the Coulomb singularity at the origin. As examples, the method is shown to give accurate ionization rates for both H and H^- over a wide range of laser parameters.

  6. Two-color stabilization of atomic hydrogen in circularly polarized laser fields

    NASA Astrophysics Data System (ADS)

    Bauer, D.; Ceccherini, F.

    2002-11-01

    The dynamic stabilization of atomic hydrogen against ionization in high-frequency single- and two-color, circularly polarized laser pulses is observed by numerically solving the three-dimensional, time-dependent Schrdinger equation. The single-color case is revisited and numerically determined ionization rates are compared with both, the exact and the approximate high-frequency Floquet rates. The positions of the peaks in the photoelectron spectra can be explained with the help of dressed initial states. In two-color laser fields of opposite circular polarization, the stabilized probability density may be shaped in various ways. For laser frequencies ?1 and ?2=n?1, n=2,3,..., and sufficiently large excursion amplitudes, (n+1) distinct probability density peaks are observed. This may be viewed as the generalization of the well-known ``dichotomy'' in linearly polarized laser fields, i.e, as ``trichotomy,'' ``quatrochotomy,'' ``pentachotomy'' etc. All those observed structures and their ``hula-hoop''-like dynamics can be understood with the help of high-frequency Floquet theory and the two-color Kramers-Henneberger transformation. The shaping of the probability density in the stabilization regime can be realized without additional loss in the survival probability, as compared to the corresponding single-color results.

  7. Two-color stabilization of atomic hydrogen in circularly polarized laser fields

    SciTech Connect

    Bauer, D.; Ceccherini, F.

    2002-11-01

    The dynamic stabilization of atomic hydrogen against ionization in high-frequency single- and two-color, circularly polarized laser pulses is observed by numerically solving the three-dimensional, time-dependent Schroedinger equation. The single-color case is revisited and numerically determined ionization rates are compared with both, the exact and the approximate high-frequency Floquet rates. The positions of the peaks in the photoelectron spectra can be explained with the help of dressed initial states. In two-color laser fields of opposite circular polarization, the stabilized probability density may be shaped in various ways. For laser frequencies {omega}{sub 1} and {omega}{sub 2}=n{omega}{sub 1}, n=2,3,..., and sufficiently large excursion amplitudes (n+1) distinct probability density peaks are observed. This may be viewed as the generalization of the well-known 'dichotomy' in linearly polarized laser fields, i.e, as 'trichotomy', 'quatrochotomy', 'pentachotomy' etc. All those observed structures and their 'hula-hoop'-like dynamics can be understood with the help of high-frequency Floquet theory and the two-color Kramers-Henneberger transformation. The shaping of the probability density in the stabilization regime can be realized without additional loss in the survival probability, as compared to the corresponding single-color results.

  8. Discharge formation systems for generating atomic iodine in a pulse-periodic oxygen–iodine laser

    SciTech Connect

    Aksinin, V I; Kazantsev, S Yu; Kononov, I G; Podlesnykh, S V; Firsov, K N; Antsiferov, S A; Velikanov, S D; Gerasimov, A Yu; Gostev, I V; Kalinovskii, V V; Konovalov, V V; Mikhalkin, V N; Sevryugin, I V

    2014-01-31

    Generation characteristics of a pulse-periodic oxygen–iodine laser with the electro-discharge production of atomic iodine were compared with inductively stabilised edged or anisotropic- resistive cathodes used for ignition of the volume discharge. The discharge was initiated by the radiation of a barrier discharge from the side of a grid anode. It was found that at equal specific electrical energy depositions to the gas-discharge plasma, the system with the anisotropic-resistive cathode provides a more stable and uniform volume discharge with the possibility of varying the composition and pressure of working mixtures over a wide range and a greater specific extraction of laser energy is observed (up to 2.4 J L{sup -1}). At a high pulse repetition rate of laser pulses (50 – 100 Hz) and long duration of the pulse trains (longer than a minute) the surface of anisotropic-resistive cathode became eroded. (laser applications and other topics in quantum electronics)

  9. Low-energy electron-impact laser-assisted ionization of atomic hydrogen

    NASA Astrophysics Data System (ADS)

    Makhoute, A.; Ajana, I.; Khalil, D.

    2014-11-01

    We have studied the influence of a linearly polarized laser field on the dynamics of low (e ,2 e ) collisions in atomic hydrogen. The influence of the laser on the target states is treated using a first-order perturbation approach. The continuum states of the scattered and ejected electrons are described respectively by Volkov and Coulomb-Volkov wave functions. The second Born approximation is used to calculate triple differential cross sections for laser-assisted ionization by low-energy electron impact. The required scattering amplitudes are evaluated by using the Sturmian basis expansion. The influence of the laser parameters (photon energy, intensity, and direction of polarization) on the triple differential cross sections is analyzed, and several illustrative examples are discussed. Our second Born approximation results agree very well with those obtained in the first-order Born approximation at larger incident energies. The margins between the second and first Born approximation results are large at low incident energies in the vicinity of the recoil peaks.

  10. Multiphoton effects in laser-assisted ionization of a helium atom by electron impact

    NASA Astrophysics Data System (ADS)

    Ghosh Deb, S.; Sinha, C.

    2010-11-01

    The dynamics of the electron impact multiphoton ionization of a He atom in the presence of an intense laser field ( n γ _e, 2 e) is studied theoretically for laser polarization (\\vert\\vert^l) and perpendicular (bot^r) to the incident momentum. The triple differential (TDCS) as well as the double differential (DDCS) cross sections are studied for the coplanar asymmetric geometry. The results are compared with the only available kinematically complete experiment at high incident energy (1000 eV). Significant laser modification (enhancement) is noted due to multiphoton effects in the present binary and recoil peak intensities of the TDCS for both the geometries, in qualitative agreement with the experiment. In the single photon case, the net effect of the laser field is to suppress the field free (FF) TDCS as well as the DDCS in the zeroth order approximation of the ejected electron wave function (CV), while in the first order (MCV), the cross sections are found to be enhanced. The CV multiphoton cross sections obey the famous Kroll Watson (KW) sum rule while the latter does not hold good in the corresponding MCV approximation.

  11. Al-free active region laser diodes at 894 nm for compact Cesium atomic clocks

    NASA Astrophysics Data System (ADS)

    Von Bandel, N.; Bb Manga Lob, J.; Garcia, M.; Larrue, A.; Robert, Y.; Vinet, E.; Lecomte, M.; Drisse, O.; Parillaud, O.; Krakowski, M.

    2015-03-01

    Time-frequency applications are in need of high accuracy and high stability clocks. Compact industrial Cesium atomic clocks optically pumped is a promising area that could satisfy these demands. However, the stability of these clocks relies, among others, on the performances of laser diodes that are used for atomic pumping. This issue has led the III-V Lab to commit to the European Euripides-LAMA project that aims to provide competitive compact optical Cesium clocks for earth applications. This work will provide key experience for further space technology qualification. We are in charge of the design, fabrication and reliability of Distributed-Feedback diodes (DFB) at 894nm (D1 line of Cesium) and 852nm (D2 line). The use of D1 line for pumping will provide simplified clock architecture compared to D2 line pumping thanks to simpler atomic transitions and larger spectral separation between lines in the 894nm case. Also, D1 line pumping overcomes the issue of unpumped "dark states" that occur with D2 line. The modules should provide narrow linewidth (<1MHz), very good reliability in time and, crucially, be insensitive to optical feedback. The development of the 894nm wavelength is grounded on our previous results for 852nm DFB. Thus, we show our first results from Al-free active region with InGaAsP quantum well broad-area lasers (100?m width, with lengths ranging from 2mm to 4mm), for further DFB operation at 894nm. We obtained low internal losses below 2cm-1, the external differential efficiency is 0.49W/A with uncoated facets and a low threshold current density of 190A/cm, for 2mm lasers at 20C.

  12. Atomic inner-shell laser at 1.5-ngstrm wavelength pumped by an X-ray free-electron laser.

    PubMed

    Yoneda, Hitoki; Inubushi, Yuichi; Nagamine, Kazunori; Michine, Yurina; Ohashi, Haruhiko; Yumoto, Hirokatsu; Yamauchi, Kazuto; Mimura, Hidekazu; Kitamura, Hikaru; Katayama, Tetsuo; Ishikawa, Tetsuya; Yabashi, Makina

    2015-08-27

    Since the invention of the first lasers in the visible-light region, research has aimed to produce short-wavelength lasers that generate coherent X-rays; the shorter the wavelength, the better the imaging resolution of the laser and the shorter the pulse duration, leading to better temporal resolution in probe measurements. Recently, free-electron lasers based on self-amplified spontaneous emission have made it possible to generate a hard-X-ray laser (that is, the photon energy is of the order of ten kiloelectronvolts) in an ngstrm-wavelength regime, enabling advances in fields from ultrafast X-ray spectrosopy to X-ray quantum optics. An atomic laser based on neon atoms and pumped by a soft-X-ray (that is, a photon energy of less than one kiloelectronvolt) free-electron laser has been achieved at a wavelength of 14 nanometres. Here, we use a copper target and report a hard-X-ray inner-shell atomic laser operating at a wavelength of 1.5 ngstrms. X-ray free-electron laser pulses with an intensity of about 10(19) watts per square centimetre tuned to the copper K-absorption edge produced sufficient population inversion to generate strong amplified spontaneous emission on the copper K? lines. Furthermore, we operated the X-ray free-electron laser source in a two-colour mode, with one colour tuned for pumping and the other for the seed (starting) light for the laser. PMID:26310765

  13. Laser frequency stabilization using Zeeman effect

    NASA Astrophysics Data System (ADS)

    Chron, B.; Gilles, H.; Hamel, J.; Moreau, O.; Sorel, H.

    1994-02-01

    We describe a new and easy to handle method to stabilize the laser frequency on an atomic transition. This method, based on Zeeman effect, involves the circular dichroism of an atomic vapour submitted to a magnetic field. It is applied to the frequency stabilization of a single frequency LNA laser on (2 (2 ^3S1-2 ^3P0) helium transition. Nous dcrivons une nouvelle mthode, facile mettre en oeuvre pour asservir la longueur d'onde d'un laser sur une raie atomique. Cette mthode base sur l'effet Zeeman, met en jeu le dichrosme circulaire prsent par une vapeur d'atomes soumise un champ magntique. Elle est applique la stabilisation de la frquence d'un laser LNA monomode sur la transition (2 ^3S1-2 ^3P0) de l'hlium.

  14. Atomic ionization by intense laser pulses of short duration: Photoelectron energy and angular distributions

    SciTech Connect

    Dondera, M.

    2010-11-15

    We introduce an adequate integral representation of the wave function in the asymptotic region, valid for the stage postinteraction between a one-electron atom and a laser pulse of short duration, as a superposition of divergent radial spherical waves. Starting with this representation, we derive analytic expressions for the energy and angular distributions of the photoelectrons and we show their connection with expressions used before in the literature. Using our results, we propose a method to extract the photoelectron distributions from the time dependence of the wave function at large distances. Numerical results illustrating the method are presented for the photoionization of hydrogenlike atoms from the ground state and several excited states by extreme ultraviolet pulses with a central wavelength of 13.3 nm and several intensities around the value I{sub 0}{approx_equal}3.51x10{sup 16} W/cm{sup 2}.

  15. Laser sampling system for an inductively-coupled atomic emission spectrometer. Final report

    SciTech Connect

    1998-02-15

    A laser sampling system was attached to a Perkin Elmer Optima 3000 inductively-coupled plasma, atomic emission spectrometer that was already installed and operating in the Chemistry and Geochemistry Department at the Colorado School of Mines. The use of the spectrometer has been highly successful. Graduate students and faculty from at least four different departments across the CSM campus have used the instrument. The final report to NSF is appended to this final report. Appendices are included which summarize several projects utilizing this instrument: acquisition of an inductively-coupled plasma atomic emission spectrometer for the geochemistry program; hydrogen damage susceptibility assessment for high strength steel weldments through advanced hydrogen content analysis, 1996 and 1997 annual reports; and methods for determination of hydrogen distribution in high strength steel welds.

  16. Total ionization rates and ion yields of atoms at nonperturbative laser intensities

    NASA Astrophysics Data System (ADS)

    Becker, A.; Plaja, L.; Moreno, P.; Nurhuda, M.; Faisal, F. H.

    2001-08-01

    We investigate a simply corrected Keldysh-Faisal-Reiss (KFR) rate formula for laser-induced ionization of atoms in the nonperturbative intensity domain. Predictions of the formula are compared, first, with ab initio Floquet calculations, which show good agreement in the nonperturbative intensity domain for not too short wavelengths. Second, they are found to agree with the results of numerical simulations for the H atom, provided the pulse lengths are not shorter than three field cycles, so that the adiabatic rate becomes a valid parameter. Finally, total single-ionization yields predicted by the present model are compared with 36 different experimental data sets for He, Ne, Ar, Kr, and Xe, covering both linear and circular polarizations, and different wavelengths, pulse durations, and intensities; the results show a remarkable overall agreement with the data.

  17. Atomic Oxygen Sensors Based on Nanograin ZnO Films Prepared by Pulse Laser Deposition

    SciTech Connect

    Wang Yunfei; Chen Xuekang; Li Zhonghua; Zheng Kuohai; Wang Lanxi; Feng Zhanzu; Yang Shengsheng

    2009-01-05

    High-quality nanograin ZnO thin films were deposited on c-plane sapphire (Al{sub 2}O{sub 3}) substrates by pulse laser deposition (PLD). Scanning electron microscopy (SEM) and x-ray diffraction (XRD) were used to characterize the samples. The structural and morphological properties of ZnO films under different deposition temperature have been investigated before and after atomic oxygen (AO) treatment. XRD has shown that the intensity of the (0 0 2) peak increases and its FWHM value decreases after AO treatment. The AO sensing characteristics of nano ZnO film also has been investigated in a ground-based atomic oxygen simulation facility. The results show that the electrical conductivity of nanograin ZnO films decreases with increasing AO fluence and that the conductivity of the films can be recovered by heating.

  18. General approach to few-cycle intense laser interactions with complex atoms

    SciTech Connect

    Guan Xiaoxu; Zatsarinny, O.; Bartschat, K.; Schneider, B. I.; Feist, J.; Noble, C. J.

    2007-11-15

    A general ab initio and nonperturbative method to solve the time-dependent Schroedinger equation (TDSE) for the interaction of a strong attosecond laser pulse with a general atom, i.e., beyond the models of quasi-one-electron or quasi-two-electron targets, is described. The field-free Hamiltonian and the dipole matrices are generated using a flexible B-spline R-matrix method. This numerical implementation enables us to construct term-dependent, nonorthogonal sets of one-electron orbitals for the bound and continuum electrons. The solution of the TDSE is propagated in time using the Arnoldi-Lanczos method, which does not require the diagonalization of any large matrices. The method is illustrated by an application to the multiphoton excitation and ionization of Ne atoms. Good agreement with R-matrix Floquet calculations for the generalized cross sections for two-photon ionization is achieved.

  19. Laser-induced mono-atomic-layer etching on Cl-adsorbed Si(111) surfaces

    NASA Astrophysics Data System (ADS)

    Iimori, T.; Hattori, K.; Shudo, K.; Iwaki, T.; Ueta, M.; Komori, F.

    1998-06-01

    We have studied ultraviolet laser-induced monolayer etching process on Cl-adsorbed Si(111)-77 surfaces with X-ray photoemission spectroscopy. We keep the fluence as low as 1 mJ/cm 2 to discuss electronic excitation and relaxation at the surface during this process. After irradiation, silicon di- and tri-chloride species on the surface disappear and monochlorides remain at the surfaces. We conclude that surface adatom polychlorides and rest-atom polychlorides are desorbed primarily as SiCl 2 species, and that adatom monochlorides and rest-atom monochlorides are stable against irradiation. Photo-excited electrons and/or holes in bulk induces the SiCl 2 desorption at the surfaces.

  20. Self-Amplified Gamma-Ray Laser on Positronium Atoms from a Bose-Einstein Condensate

    NASA Astrophysics Data System (ADS)

    Avetissian, H. K.; Avetissian, A. K.; Mkrtchian, G. F.

    2014-07-01

    A scheme of an intense coherent gamma-ray source based on the spontaneous radiation of positronium atoms in a Bose-Einstein condensate (BEC) due to two-photon collective annihilation decay is investigated analytically arising from the second quantized formalism. It is shown that because of the intrinsic instability of annihilation decay of BEC, the spontaneously emitted entangled photon pairs are amplified, leading to an exponential buildup of a macroscopic population into end-fire modes at a certain shape of the elongated condensate. The considered scheme may also be applied to a BEC of atoms or quasiparticles as a laser mechanism with double coherence to create entangled photonic beams with a macroscopic number of photons.

  1. Self-amplified gamma-ray laser on positronium atoms from a Bose-Einstein condensate.

    PubMed

    Avetissian, H K; Avetissian, A K; Mkrtchian, G F

    2014-07-11

    A scheme of an intense coherent gamma-ray source based on the spontaneous radiation of positronium atoms in a Bose-Einstein condensate (BEC) due to two-photon collective annihilation decay is investigated analytically arising from the second quantized formalism. It is shown that because of the intrinsic instability of annihilation decay of BEC, the spontaneously emitted entangled photon pairs are amplified, leading to an exponential buildup of a macroscopic population into end-fire modes at a certain shape of the elongated condensate. The considered scheme may also be applied to a BEC of atoms or quasiparticles as a laser mechanism with double coherence to create entangled photonic beams with a macroscopic number of photons. PMID:25062185

  2. Arcjet flow properties determined from laser-induced fluorescence of atomic nitrogen.

    PubMed

    Fletcher, D G

    1999-03-20

    Flow property measurements that were recently acquired in the Ames Research Center Aerodynamic Heating Facility arcjet using two-photon laser-induced fluorescence (LIF) of atomic nitrogen (N) are reported. The flow properties, which include velocity, translational temperature, and N concentration, were measured simultaneously over a range of facility operating conditions for N(2)-argon test gas flows in the 30-cm-diameter nozzle. A recent measurement of the two-photon excitation cross section for the 3p(4)D degrees <-- 2p(4)S degrees transition of atomic nitrogen is used to convert the relative nitrogen concentration measurements to absolute values, and a nitrogen flow reactor is used to provide a room-temperature, reference-wavelength calibration of the translational temperature and velocity measurements. When combined with information from facility measurements, an analysis of the flow properties obtained using two-photon LIF of N yields the total free-stream flow enthalpy. PMID:18305816

  3. Spectroscopy of Hydrogen atom collisions: from laser-plasmas to stars

    NASA Astrophysics Data System (ADS)

    Allard, Nicole; Kielkopf, J.; Gerbaldi, M.; Koester, D.

    The low energy interactions of neutral and ionized hydrogen atoms are fundamental processes which also have important aplications to the diagnostics of laboratory and astrophysical plasmas. satellites in the far wings of the Lyman alpha and Lyman beta have been identified as ultraviolet absorption features in the spectra of white dwarf and Lambda Bootis stars, and they are seen in emission spectra of plasma produced when a pulsed laser excites a target as H_2 gas. Comparison of laboratory observations and astronomical spectra with theoretical profiles are discussed.

  4. Electron release of fare-gas atomic clusters under an intense laser pulse.

    PubMed

    Siedschlag, Christian; Rost, Jan M

    2002-10-21

    Calculating the energy absorption of atomic clusters as a function of the laser pulse length T we find a maximum for a critical T(*). We show that T(*) can be linked to an optimal cluster radius R(*). The existence of this radius can be attributed to the enhanced ionization mechanism originally discovered for diatomic molecules. Our findings indicate that enhanced ionization should be operative for a wide class of rare-gas clusters. From a simple Coulomb-explosion ansatz, we derive an analytical expression relating the maximum energy release to a suitably scaled expansion time which can be expressed with the pulse length T(*). PMID:12398668

  5. Refraction and absorption of x rays by laser-dressed atoms.

    SciTech Connect

    Buth, C.; Santra, R.; Young, L.

    2010-06-01

    X-ray refraction and absorption by neon atoms under the influence of an 800 nm laser with an intensity of 10{sup 13} W/cm{sup 2} is investigated. For this purpose, we use an ab initio theory suitable for optical strong-field problems. Its results are interpreted in terms of a three-level model. On the Ne 1s {yields} 3p resonance, we find electromagnetically induced transparency (EIT) for x rays. Our work opens novel perspectives for ultrafast x-ray pulse shaping.

  6. The RMT method for describing many-electron atoms in intense short laser pulses

    NASA Astrophysics Data System (ADS)

    Lysaght, M. A.; Moore, L. R.; Nikolopoulos, L. A. A.; Parker, J. S.; van der Hart, H. W.; Taylor, K. T.

    2012-11-01

    We describe how we have developed an ab initio R-Matrix incorporating Time (RMT) method to provide an accurate description of the single ionization of a general many-electron atom exposed to short intense laser pulses. The new method implements the "division-of-space" concept central to R-matrix theory and takes over the sophisticated time-propagation algorithms of the HELIUM code. We have tested the accuracy of the new method by calculating multiphoton ionization rates of He and Ne and have found excellent agreement with other highly accurate and well-established methods.

  7. Increase in the power of lasing on atomic and ion transitions in chemical elements

    SciTech Connect

    Klimkin, V M; Sokovikov, V G

    2007-02-28

    A method for increasing the power of pulsed lasing on atomic and ion transitions in chemical elements obtained by the conversion of the UV radiation of excimer lasers in cells with metal vapours is studied. A part of UV radiation transmitted through a cell with metal vapour is used for pumping a dye solution in such a way that the cell converter with metal vapour represents a master oscillator, while the dye cell represents an amplifier. The study is performed by the example of amplification of weak spectral components of radiation from a XeCl* laser converted in mercury and barium vapours. In the amplifying stage the longitudinal pumping of the dye is used and a scheme for suppressing self-excitation is employed. It is found by selecting dyes that the alcohol solution of uranin is nearly optimal for amplification of the 546.1-nm laser line of mercury, while the best results in amplification of the 533-nm and 648.2-nm laser lines of barium were obtained by using alcohol solutions of rhodamine 6G and oxazine 17, respectively. The power of the 546.1-nm mercury line was increased by an order of magnitude, while the power of the 533-nm and 648.2-nm lines of barium - almost by a factor of twenty-five. (lasers)

  8. Selective production of atomic oxygen by laser photolysis as a tool for studying the effect of atomic oxygen in plasma medicine

    NASA Astrophysics Data System (ADS)

    Ono, Ryo; Tokumitsu, Yusuke

    2015-06-01

    We propose a method for selectively producing O atoms by the laser photolysis of O3 as a tool for studying the therapeutic effect of O atoms in plasma medicine. A KrF excimer laser (248?nm) irradiates an O3 /He mixture flowing in a quartz tube to photodissociate O3 , which leads to the production of O atoms. The effluent from the quartz tube nozzle can be applied to a target (cells, bacteria, or an affected part). Simulations show that 500 ppm O atoms can be continuously supplied to a target surface at a distance of 3?mm from the quartz tube nozzle if an O3 (2000 ppm)/He mixture is used. The effluent contains only O, O3 , and O_2({{a}1}{?g}) , and does not contain other types of reactive species in contrast to a plasma. Therefore, it can be used to examine the therapeutic effects of O atoms in isolation. Part of the simulation results are experimentally verified by irradiating an O3 /He mixture with a KrF excimer laser.

  9. Sensitized and heavy atom induced production of acenaphthylene triplet: A laser flash photolysis study

    SciTech Connect

    Samanta, A.; Fessenden, R.W. )

    1989-07-27

    The triplet state of acenaphthylene has been examined by nanosecond laser flash photolysis using sensitization and heavy atom perturbation techniques. Although acenaphthylene does not form any observable triplet upon direct flash excitation, a transient with microsecond lifetime ({lambda}{sub max} = 315 nm) is observable when a solution of the sample is excited by sensitizers (benzophenone, thioxanthone, benzil). This transient is ascribed to the triplet of acenaphthylene on the basis of its quenching behavior toward oxygen, ferrocene, azulene, and {beta}-carotene. Quantitative data concerning the triplet-triplet absorption and quenching constants are presented. The triplet energy is estimated to lie between 46 and 47 kcal/mol. The triplet can also be produced by direct excitation in solvents containing heavy atoms (ethyl bromide, ethyl iodide). The triplet yield is found to increase with an increase of the amount of the heavy atom containing solvent. No saturation limit is obtained. These facts together with the effect of heavy atoms on the T{sub 1} {yields} S{sub 0} process allow the differing behavior of ethyl bromide and ethyl iodide on the photodimerization process of acenaphthylene to be explained. Triplet-state parameters (extinction coefficient and triplet yield) have been estimated in these solvents by the energy-transfer technique and actinometry.

  10. Stability of the far-off-resonance dipole-atom trap with superimposed laser cooling

    NASA Astrophysics Data System (ADS)

    Jun, Jin Woo; Minogin, V. G.

    2001-08-01

    The stability region of a far-off-resonance dipole-atom trap (FORT) composed of a single trapping laser beam and a ?+-?- cooling field configuration is discussed for the simplest (3+5)-level atomic scheme. The ultimate parameters of the stable FORT are evaluated by extending the theory of the FORT to the fourth-order rate-equation approximation. It is shown that when the detuning of the trapping field is much larger than the detuning of the cooling field, and with a proper choice of a low optical saturation due to the trapping and cooling field, the mixing of the one-photon processes responsible for the trapping potential with the two-photon processes responsible for the sub-Doppler cooling of atoms in the trap remains weak. It is concluded that the FORT with superimposed cooling fields possesses a stability region where the diffusive heating is suppressed by the cooling processes. Numerical evaluations of the stability region for a model of a (3+5)-level atom are given.

  11. Atomic layer-by-layer growth of oxide thin films by laser MBE

    NASA Astrophysics Data System (ADS)

    Lei, Qingyu; Liu, Guozhen; Golalikhani, Maryam; Chen, Ke; Shi, Suilin; Huang, Fuqiang; Farrar, Andrew; Tenne, Dmitri; Singh, Rakesh; Xi, Xiaoxing

    2014-03-01

    We have studied an atomic layer-by-layer thin film growth technique for complex oxide thin films and heterostructures. By using a laser-MBE system and monitoring the reflection high-energy electron diffraction (RHEED) intensity to control the flux for each atomic layer in-situ, we actively control the structure and stoichiometry down to the atomic layer level. In the growth of SrTiO3 from the separate SrO and TiO2 targets, or from metal Sr and oxide TiO2 target, we studied the phases of the specular and diffraction spot intensities as well as that of the Kikuchi lines. UV Raman spectroscopy was used to probe the symmetry breaking due to the cation off-stoichiometry. Similar stoichiometry control as shown by reactive MBE has been demonstrated. We also studied the target preparation of various oxides, including the highly reactive La2O3 and BaO. We have successfully applied this atomic layer-by-layer growth method to the deposition of LaAlO3 and LaNiO3 thin films and superlattices.

  12. Quantum control of multilevel atoms with rotational degeneracy using short laser pulses

    SciTech Connect

    Demeter, G.

    2010-10-15

    We study the quantum control of multilevel atoms with rotationally degenerate levels using short laser pulses. Various control schemes are considered, ones using {pi} pulses, frequency-chirped pulses, two consecutive pulses, or two pulses that overlap each other partially. We study the possibilities of controlling the quantum state of an ensemble of atoms distributed randomly over one or more rotationally degenerate levels initially. For the sake of concreteness we use the hyperfine level scheme of the {sup 85}Rb D line, but the results can easily be generalized for any of the alkali-metal atoms used in cooling and trapping experiments. We find that even though a number of difficulties arise, such as unequal coupling constants between rotational sublevels or dephasing between different hyperfine levels during the interaction, control schemes using simple or multiphoton adiabatic passage can be used to control the internal states of the atoms effectively as well as the center-of-mass motion. Furthermore, it is shown that in some cases it is possible to exploit the inequality of the coupling constants to entangle the rotational substates with specific distinct translational quantum states and hence separate these substates in momentum space.

  13. Effects of Laser Energy and Wavelength on the Analysis of LiFePO4 Using Laser Assisted Atom Probe Tomography

    SciTech Connect

    Santhanagopalan, Dhamodaran; Schreiber, Daniel K.; Perea, Daniel E.; Martens, Rich; Janssen, Yuri; Kalifah, Peter; Meng, Ying S.

    2015-01-21

    The effects of laser wavelength (355 nm and 532 nm) and laser pulse energy on the quantitative accuracy of atom probe tomography (APT) examinations of LiFePO4 (LFP) are considered. A systematic investigation of ultraviolet (UV, 355 nm) and green (532 nm) laser assisted APT of LFP has revealed distinctly different behaviors. With the use of UV laser the major issue was identified as the preferential loss of oxygen (up to 10 at. %) while other elements (Li, Fe and P) were observed to be close to nominal ratios. Lowering the laser energy per pulse to 1 pJ increased the observed oxygen concentration to near its correct stoichiometry and was well correlated with systematically higher concentrations of 16O2+ ions. This observation supports the premise that lower laser energies lead to a higher probability of oxygen molecule ionization. Conversely, at higher laser energies the resultant lower effective electric field reduces the probability of oxygen molecule ionization. Green laser assisted field evaporation led to the selective loss of Li (~50% deficiency) and correct ratios of the remaining elements, including the oxygen concentration. The loss of Li is explained by selective dc evaporation of lithium between laser pulses and relatively negligible oxygen loss as neutrals during green-laser pulsing. Lastly, plotting of multihit events on a Saxey plot for the straight-flight path data (green laser only) revealed a surprising dynamic recombination process for some molecular ions mid-flight.

  14. Laser sustained discharge nozzle apparatus for the production of an intense beam of high kinetic energy atomic species

    DOEpatents

    Cross, Jon B.; Cremers, David A.

    1988-01-01

    Laser sustained discharge apparatus for the production of intense beams of high kinetic energy atomic species. A portion of the plasma resulting from a laser sustained continuous optical discharge which generates energetic atomic species from a gaseous source thereof is expanded through a nozzle into a region of low pressure. The expanded plasma contains a significant concentration of the high kinetic energy atomic species which may be used to investigate the interaction of surfaces therewith. In particular, O-atoms having velocities in excess of 3.5 km/s can be generated for the purpose of studying their interaction with materials in order to develop protective materials for spacecraft which are exposed to such energetic O-atoms during operation in low earth orbit.

  15. Laser sustained discharge nozzle apparatus for the production of an intense beam of high kinetic energy atomic species

    DOEpatents

    Cross, J.B.; Cremers, D.A.

    1986-01-10

    Laser sustained discharge apparatus for the production of intense beams of high kinetic energy atomic species is described. A portion of the plasma resulting from a laser sustained continuous optical discharge which generates energetic atomic species from a gaseous source thereof is expanded through a nozzle into a region of low pressure. The expanded plasma contains a significant concentration of the high kinetic energy atomic species which may be used to investigate the interaction of surfaces therewith. In particular, O-atoms having velocities in excess of 3.5 km/s can be generated for the purpose of studying their interaction with materials in order to develop protective materials for spacecraft which are exposed to such energetic O-atoms during operation in low earth orbit.

  16. Hydrogen atom temperature measured with wavelength-modulated laser absorption spectroscopy in large scale filament arc negative hydrogen ion source

    SciTech Connect

    Nakano, H. Goto, M.; Tsumori, K.; Kisaki, M.; Ikeda, K.; Nagaoka, K.; Osakabe, M.; Takeiri, Y.; Kaneko, O.; Nishiyama, S.; Sasaki, K.

    2015-04-08

    The velocity distribution function of hydrogen atoms is one of the useful parameters to understand particle dynamics from negative hydrogen production to extraction in a negative hydrogen ion source. Hydrogen atom temperature is one of the indicators of the velocity distribution function. To find a feasibility of hydrogen atom temperature measurement in large scale filament arc negative hydrogen ion source for fusion, a model calculation of wavelength-modulated laser absorption spectroscopy of the hydrogen Balmer alpha line was performed. By utilizing a wide range tunable diode laser, we successfully obtained the hydrogen atom temperature of ∼3000 K in the vicinity of the plasma grid electrode. The hydrogen atom temperature increases as well as the arc power, and becomes constant after decreasing with the filling of hydrogen gas pressure.

  17. Optically pumped rare-gas lasers

    NASA Astrophysics Data System (ADS)

    Mikheyev, P. A.

    2015-08-01

    The modern state of the research of a new promising optically pumped laser system with an active medium formed by metastable rare-gas atoms is briefly reviewed. The kinetics of these media is similar to that of laser media based on alkali metal vapour; however, the gas medium is inert. Metastable atoms can be produced in an electric discharge. As in alkali lasers, the specific laser power output under atmospheric pressure can be several hundreds of watts per 1 cm3. The lasing wavelengths lie in the near-IR range and fall in the transparency window of the terrestrial atmosphere. This new concept makes it possible to develop a closed-cycle cw laser with megawatt power levels and high beam quality.

  18. Development of laser-plasma diagnostics using ultrafast atomic-scale dynamics. 96-ERD-046 final report

    SciTech Connect

    Bolton, P.R.; Kulander, K.C.; Boreham, B.W.

    1997-03-01

    Ultrashort laser pulse systems allow examination of intense, ultrafast laser-plasma interactions. More specifically, intense laser irradiation can induce short xuv/x-ray bursts from the surface of condensed phase targets. Ultrafast xuv/x-ray detection is needed to understand laser-plasma interactions in this dynamic regime. Support of the Stockpile Stewardship and Management Program requires this critical understanding. Our effort here has been to extend understanding of atomic-scale dynamics in such environments with the goal of developing next generation ultrafast xuv/x-ray diagnostics where the sensors will be the atoms and ions themselves and the time resolution will approach that of the induced atomic transitions ({approx} a few femtoseconds). Pivotal contributions to the rapidly developing field of highly nonperturbative interactions of ultrashort pulse lasers with atoms/ions have been made at this laboratory. In the visible/infrared wavelength regions the temporal and spectral content of ultrashort laser pulses are now reliably monitored within a single pulse using frequency resolved optical gating (FROG) which is based on rapid nonlinear optical processes such as the Kerr effect. New applications of this basic concept are still being developed. Corresponding detection for the xuv/x-ray wavelengths does not exist and is urgently needed in many laboratory programs. The FROG technique cannot be applied in the xuv/x-ray region. Current x-ray streak camera technology is limited to {approx}0.5 picosecond resolution.

  19. Non-neutral ion plasmas and crystals, laser cooling, and atomic clocks

    SciTech Connect

    Bollinger, J.J.; Wineland, D.J. ); Dubin, D.H.E. )

    1994-05-01

    Experimental work which uses Penning and Paul traps to confine non-neutral ion plasmas is discussed. Penning traps use a static uniform magnetic field and a static electric field to confine ions. The Paul trap uses the ponderomotive force from inhomogeneous radio-frequency fields to confine ions to a region of minimum field strength. In many atomic physics experiments, these traps are designed to produce a harmonic restoring force for small numbers of stored ions ([lt]10[sup 4]). Under these conditions and at low temperatures, both traps produce plasmas with simple shapes whose mode properties can be calculated exactly. Laser cooling has been used to reduce the temperature of trapped ions to less than 10 mK with ion spacings less than 20 [mu]m. At such temperatures and interion spacings, the Coulomb potential energy between nearest neighbor ions is greater than the ion thermal energy and the ions exhibit spatial correlations characteristic of a liquid or crystal. Laser beams also apply a torque which, by changing the plasma angular momentum, changes the plasma density. Atomic clocks are an important application of ion trap plasmas. Better control of the plasma dynamics will reduce fluctuations in the relativistic time dilation, yielding better clocks.

  20. Controllable optical bistability in photonic-crystal one-atom laser

    SciTech Connect

    Guo Xiaoyong; Lue Shuchen

    2009-10-15

    We investigate the property of optical bistability in a photonic-crystal one-atom laser when nonlinear microcavity is present. The physical system consists of a coherently driven two-level light emitter strongly coupled to a high-quality microcavity which is embedded within a photonic crystal and another coherent probing field which has incident into the microcavity. In our case, the microcavity is fabricated by nonlinear material and placed as an impurity in photonic crystal. This study reveals that such a system can exhibit optical bistability. The dependence of threshold value and hysteresis loop on the photonic band gap of the photonic crystal, driving field Rabi frequency and dephasing processes, are studied. Our results clearly illustrate the ability to control optical bistability through suitable photonic-crystal architectures and external coherent driving field, and this study suggests that in a photonic-crystal nonlinear microcavity, the one-atom laser acts as an effective controllable bistable device in the design of all-light digital computing systems in the near future.

  1. New advances in the interaction of a femtosecond Ti:sapphire laser with atoms and molecules

    NASA Astrophysics Data System (ADS)

    Talebpour, Abdossamad

    Dans ce travail exprimental, nous avons tud le comportement des atomes de gaz rare et des molecules soumis des champs laser intense (1013-1016 W/cm 2) g = 800 nm. Les recherches realises ont montr que l'ionization simple tait correctement dcrite par un modle considerant le phnomne d'effet tunnel au travers d'une barriere de potentiel oscillant dans le temps. Aussi, nous avons tudi le phnomene de pigeage de population dans les tats excits des atomes et des molcules qui sont en rsonance dynamique avec leur tat fondamental. Pour l'ionisation non squentielle, il a t observ que le phnomne dpendait de la longueur d'onde du laser et que le taux d'ionisation non-squentielle tait proportionnelle au taux prdit par la limit quasi- statique des modles d'ionisation squentielle. Finalement, tudiant la fragmentation de la molcule NO, nous avons propos un modle pour le mcanisme de fragmentation des molcules diatomiques. D'aprs ce modle, l'tirement de la molcule par la rediffusion de l'lectron et la recombinaison dissociative suivie par l'``enhanced ionization'' est le mcanisme responsable pour la fragmentation des ions molculaires.

  2. The interaction of 193-nm excimer laser radiation with single-crystal zinc oxide: The generation of atomic Zn line emission at laser fluences below breakdown

    SciTech Connect

    Kahn, E. H.; Langford, S. C.; Dickinson, J. T.; Boatner, Lynn A

    2013-01-01

    The production of gas phase atomic and ionic line spectra accompanying the high laser fluence irradiation of solid surfaces is well known and is most often due to the production and interaction of high densities of atoms, ions, and electrons generated from laser-induced breakdown. The resulting plasma expands and moves rapidly away from the irradiated spot and is accompanied by intense emission of light. This type of plume is well studied and is frequently exploited in the technique of chemical analysis known as laser induced breakdown spectroscopy. Here, we describe a similar but weaker emission of light generated in vacuum by the laser irradiation of single crystal ZnO at fluences well below breakdown; this emission consists entirely of optical line emission from excited atomic Zn. We compare the properties of the resulting laser-generated gas-phase light emission (above and below breakdown) and describe a mechanism for the production of the low-fluence optical emission resulting from a fortuitous choice of material and laser wavelength.

  3. The interaction of 193-nm excimer laser radiation with single-crystal zinc oxide: The generation of atomic Zn line emission at laser fluences below breakdown

    SciTech Connect

    Khan, Enamul H.; Langford, S. C.; Dickinson, J. T.; Boatner, L. A.

    2013-08-28

    The production of gas phase atomic and ionic line spectra accompanying the high laser fluence irradiation of solid surfaces is well known and is most often due to the production and interaction of high densities of atoms, ions, and electrons generated from laser-induced breakdown. The resulting plasma expands and moves rapidly away from the irradiated spot and is accompanied by intense emission of light. This type of plume is well studied and is frequently exploited in the technique of chemical analysis known as laser induced breakdown spectroscopy. Here, we describe a similar but weaker emission of light generated in vacuum by the laser irradiation of single crystal ZnO at fluences well below breakdown; this emission consists entirely of optical line emission from excited atomic Zn. We compare the properties of the resulting laser-generated gas-phase light emission (above and below breakdown) and describe a mechanism for the production of the low-fluence optical emission resulting from a fortuitous choice of material and laser wavelength.

  4. Study of laser uncaging induced morphological alteration of rat cortical neurites using atomic force microscopy.

    PubMed

    Tian, Jian; Tu, Chunlong; Liang, Yitao; Zhou, Jian; Ye, Xuesong

    2015-09-30

    Activity-dependent structural remodeling is an important aspect of neuronal plasticity. In the previous researches, neuronal structure variations resulting from external interventions were detected by the imaging instruments such as the fluorescence microscopy, the scanning/transmission electron microscopy (SEM/TEM) and the laser confocal microscopy. In this article, a new platform which combined the photochemical stimulation with atomic force microscopy (AFM) was set up to detect the activity-dependent structural remodeling. In the experiments, the cortical neurites on the glass coverslips were stimulated by locally uncaged glutamate under the ultraviolet (UV) laser pulses, and a calcium-related structural collapse of neurites (about 250 nm height decrease) was observed by an AFM. This was the first attempt to combine the laser uncaging with AFM in living cell researches. With the advantages of highly localized stimulation (<5 μm), super resolution imaging (<3.8 nm), and convenient platform building, this system was suitable for the quantitative observation of the neuron mechanical property variations and morphological alterations modified by neural activities under different photochemical stimulations, which would be helpful for studying physiological and pathological mechanisms of structural and functional changes induced by the biomolecule acting. PMID:26149288

  5. Selective laser pumping of magnetic sublevels in the hyperfine structure of the cesium atom

    NASA Astrophysics Data System (ADS)

    Magunov, A. I.; Palchikov, V. G.

    2014-05-01

    The evolution of the populations of the magnetic sublevels of the cesium atom (133Cs isotope) in resonant laser fields with linear polarization is analyzed using the equations for the density matrix. Analytic expressions are derived for stationary populations resulting from laser-induced optical transitions on the hyperfine structure components F g = 3 ? F e = 2, 3 and F f = 4 ? F e = 3, 4 of lines D 1 (62 S 1/2 ? 62 P 1/2) and D 2 (62 S 1/2 ? 62 P 3/2) depending on the initial values of the populations. The numerical solution of the evolution equations gives the characteristic times of stabilization of the steady regime as functions of laser field intensities and detuning from optical resonance. We determine the sequences of optical transitions increasing (by more than an order of magnitude) the population of the lower sublevel 62 S 1/2 F g = 3 M = 0 of the "clock" microwave transition F g = 3 M = 0 ? F f = 4 M = 0 in the cesium frequency standard, which increases the signal intensity in the recording system by the same proportion.

  6. Polarization-based isotope-selective two-color photoionization of atomic samarium using broadband lasers

    NASA Astrophysics Data System (ADS)

    Seema, A. U.; Rath, Asawari D.; Mandal, P. K.; Dev, Vas

    2015-03-01

    An isotope separation method based on polarization selection rules is applied to atomic samarium by using two-color resonance ionization spectroscopy with broadband lasers. In this method, odd isotopes with nonzero nuclear spin are selectively excited, while even isotopes with zero nuclear spin are prohibited from excitation using two parallel linearly polarized lasers. We have identified a two-color excitation scheme 0 cm-1 ( J = 0) ? 15650.5 cm-1 ( J = 1) ? 33116.8 cm-1 ( J = 1) ? Sm+ for selective excitation of the odd isotopes of Sm I. Using this scheme, selective excitation of odd isotopes of Sm I (147Sm and 149Sm) with an isotopic selectivity better than 40 has been demonstrated. In addition, the effect of different polarization states of the excitation lasers and relative polarization angle between them on the selectivity of odd isotopes has also been studied. The dependence of the even mass isotope signal on the relative polarization angle followed sin2 ?, which is in excellent agreement with theoretical predictions.

  7. Sub-part-per-billion analysis of aqueous lead colloids by ArF laser induced atomic fluorescence.

    PubMed

    Ho, S K; Cheung, N H

    2005-01-01

    Highly sensitive analysis of aqueous lead carbonate colloids was demonstrated by two-pulse laser-induced atomic fluorescence. The first laser pulse at 1064 nm ablated the sample solution to create an expanding plume. The colloids, being heavier, trailed behind and became concentrated. They were then intercepted by an ArF laser pulse that induced prompt atomic fluorescence at 405.8 nm from the lead atoms. The detection limit for lead was 0.24 ppb. Tap water was analyzed, and lead emissions were clearly observed. Time-resolved spectroscopy revealed that the efficient 193-nm excitation of the analytes was more universal than expected. That was confirmed by the successful application of the technique to colloids and alloys other than lead. PMID:15623296

  8. Generalized space-translated Dirac and Pauli equations for superintense laser-atom interactions

    NASA Astrophysics Data System (ADS)

    Boca, Madalina; Florescu, Viorica; Gavrila, Mihai

    2012-02-01

    We obtain a generalization of the nonrelativistic space-translation transformation to the Dirac equation in the case of a unidirectional laser pulse. This is achieved in a quantum-mechanical representation connected to the standard Dirac representation by a unitary operator T transforming the Foldy-Wouthuysen free-particle basis into the Volkov spinor basis. We show that a solution of the transformed Dirac equation containing initially low momenta p (p/mc?1) will maintain this property at all times, no matter how intense the field or how rapidly it varies (within present experimental capabilities). As a consequence, the transformed four-component equation propagates independently electron and positron wave packets, and in fact the latter are propagated via two two-component Pauli equations, one for the electron, the other for the positron. These we shall denote as the Pauli low-momentum regime (LMR) equations, equivalent to the Dirac equation for the laser field. Successive levels of dynamical accuracy appear depending on how accurately the operator T is approximated. At the level of accuracy considered in this paper, the Pauli LMR equations contain no spin matrices and are in fact two-component Schrdinger equations containing generalized time-dependent potentials. The effects of spin are nevertheless included in the theory because, in the calculation of observables which are formulated in the laboratory frame, use is made of the spin-dependent transformation operator T. In addition, the nonrelativistic limit of our results reproduces known results for the laboratory frame with spin included. We show that in intense laser pulses the generalized potentials can undergo extreme distortion from their unperturbed form. The Pauli LMR equation for the electron is applicable to one-electron atoms of small nuclear charge(?Z?1) interacting with lasers of all intensities and frequencies ??mc2.

  9. Single-mode vertical-cavity surface emitting lasers for {sup 87}Rb-based chip-scale atomic clock

    SciTech Connect

    Derebezov, I. A. Haisler, V. A.; Bakarov, A. K.; Kalagin, A. K.; Toropov, A. I.; Kachanova, M. M.; Gavrilova, T. A.; Semenova, O. I.; Tretyakov, D. B.; Beterov, I. I.; Entin, V. M.; Ryabtsev, I. I.

    2010-11-15

    The results of numerical simulation and study of lasing characteristics of semiconductor verticalcavity surface-emitting lasers based on Al{sub x}Ga{sub 1-x}As alloys are presented. Lasers exhibit stable single-mode lasing at a wavelength of 795 nm at low operating currents {approx}1.5 mA and an output power of 350 {mu}W, which offers prospects of their applications in next-generation chip-scale atomic clocks

  10. Calculation of the harmonic spectrum for one and two-electron atoms in two-colour laser fields

    NASA Astrophysics Data System (ADS)

    Robinson, D. J.; Parker, J. S.; Moore, L. R.; Taylor, K. T.

    2012-11-01

    We study the behaviour of hydrogen and helium atoms in intense two-colour linearly-polarised laser fields. Two cases are considered - the case where both fields act with parallel axes of polarisation and the case where the polarisation axes are perpendicular. We report extensions of the HELIUM code and a related hydrogen code to study these two cases of the two-colour problem. The impact of the second laser pulse on the harmonic spectrum is explored.

  11. The effects of atomic rubidium vapor on the performance of optical windows in Diode Pumped Alkali Lasers (DPALs)

    NASA Astrophysics Data System (ADS)

    Quarrie, Lindsay O.'Brien

    2013-03-01

    Diode Pumped Alkali Lasers (DPALs) suffers from damage to its optical windows due to atomic alkali exposure. DPALs are of great interest since they can combine multiple lasers to achieve higher laser output power, scalable to megawatts, with very high quantum efficiency. However before scaling to higher laser output beam power, damage to the optical windows from atomic alkali exposure in the gain medium has to be addressed. A DPAL emulator chamber was constructed for the purpose of evaluating different optical windows in a representative hot alkali rich environment typical of a DPAL gain cell. Sample optical windows of fused silica, alumina, magnesium fluoride and calcium fluoride were exposed in the DPAL emulator in order to qualitatively and quantitatively demonstrate and assess the damaging effects of the atomic rubidium vapor on the optical windows. Methodologies to examine the damage were developed for comparing exposed and unexposed optical windows. We found that damage to the optical windows due to the atomic rubidium can be quantified by means of changes in laser energy transmission through the optical window after rubidium exposure.

  12. Scheme for a compact cold-atom clock based on diffuse laser cooling in a cylindrical cavity

    NASA Astrophysics Data System (ADS)

    Liu, Peng; Meng, Yanling; Wan, Jinyin; Wang, Xiumei; Wang, Yaning; Xiao, Ling; Cheng, Huadong; Liu, Liang

    2015-12-01

    We present a scheme for a compact rubidium cold-atom clock which performs diffuse light cooling, microwave interrogation, and detection of the clock signal in a cylindrical microwave cavity. The diffuse light is produced by laser light reflection at the inner surface of the microwave cavity. The pattern of the injected laser beams is specially designed to accumulate the majority of the cold atoms in the center of the microwave cavity. Microwave interrogation of the cold atoms in the cavity leads to Ramsey fringes, which have a linewidth of 24.5 Hz with a contrast of 95.6 % when the free evolution time is 20 ms. Recently, a frequency stability of 7.3 ×10-13τ-1 /2 has been achieved. The scheme of this physical package can largely reduce the cold-atom clock complexity and increase clock performance.

  13. Laser flash photolysis studies on the induced-quenching process competing with hydrogen atom abstraction of triplet benzophenone. Heavy atom effect

    NASA Astrophysics Data System (ADS)

    Okada, Katsuji; Yamaji, Minoru; Shizuka, Haruo

    1996-05-01

    The rate constants ( kHA and kIQ) for the hydrogen atom abstraction (HA) and induced-quenching (IQ) processes between triplet benzophenone ( 3BP ?) and halogenated toluenes (XTL) were determined by means of nanosecond laser flash photolysis techniques. It was found that the kIQ value increased proportionally with increasing the squared summation of the spin-orbit coupling constant (?) of atoms involved in XTL while the kHA's were almost indifferent. It was demonstrated that the IQ process was the intersystem crossing process which was induced mainly by the spin-orbit interaction between 3BP ? and XTL.

  14. Conditions for the applicability of the Kramers-Henneberger approximation for atoms in high-frequency strong laser fields

    NASA Astrophysics Data System (ADS)

    Pawlak, Mariusz; Moiseyev, Nimrod

    2014-08-01

    Using well-known scaling techniques we present that for a given laser intensity the photoionization decay rate ? of the core electron in the 1s orbital of an atom is varied with the laser frequency ? such that ?Z4 vs ? /Z2 has a universal behavior that does not depend on the nuclear charge Z. One can conclude that the laser frequency required to stabilize the 1s core electron is larger by the factor Z2 than the laser frequency required to stabilize the electron in the most diffused orbital. This condition ensures the applicability of the Kramers-Henneberger approximation (KHA) for all electrons including the core electrons. However, simple analytical arguments, which are confirmed by our numerical results, show that when the photoionization of the core electron is due to the absorption of one photon only, then the KHA is applicable for a lower frequency that is linearly proportional to Z and not to the square of atomic number as expected. This condition is a lower bound for the laser frequency which is needed to stabilize a many-electron atom in the presence of high-frequency strong laser fields.

  15. The Toxicity of Epichlorhydrin Vapour

    PubMed Central

    Gage, J. C.

    1959-01-01

    A versatile apparatus is described for exposing experimental animals to predetermined concentrations of toxic substances in air, and it has been used to study the vapour toxicity of epichlorhydrin to rats and rabbits. At concentrations above 100 p.p.m. the vapour produces lung oedema and damage to the renal cortical tubules in rats, while above 50 p.p.m. it produces marked nasal irritation. Nasal irritation is still present in rats and rabbits below 50 p.p.m. and is only absent below 10 p.p.m. It is recommended that the concentration in industrial atmospheres should not exceed 5 p.p.m. PMID:13618515

  16. Solution to a 3D atom-laser interaction problem by sine-DVR and split-operator propagator

    NASA Astrophysics Data System (ADS)

    Yuan, Minghu; Chu, Tianshu

    2014-05-01

    We present a three-dimensional quantum approach for exploring atom-laser interaction based on solution of time-dependent Schrdinger equation. And the numerical results are achieved with sine-DVR (discrete variable representation) and split-operator propagator in the length gauge. Applications of the present theoretical approach have been illustrated in the calculations of the photoelectron features for argon in either linearly or circularly polarized laser field. Our calculated photoelectron spectra have good agreement with experimental results in both of the two polarization laser fields, and the features of above threshold ionization spectra are investigated.

  17. Calculations of the double differential cross section for attosecond laser-assisted photoionization of atoms

    NASA Astrophysics Data System (ADS)

    Kazansky, A. K.; Kabachnik, N. M.

    2006-12-01

    The energy and angular distributions of photoelectrons (the double differential cross sections, DDCS) for attosecond-pulse induced photoemission from atoms in the presence of a strong laser field are theoretically considered. We suggest a comparatively simple computational method based on the strong field approximation for calculation of the DDCS of short pulse photoionization which explicitly includes competing processes of interference and dephasing of the electronic wave packets. The method can be useful for analysis of attosecond streaking experiments. It is tested by comparison with the exact quantum-mechanical computation based on a numerical solving of the time-dependent Schrdinger equation. An excellent agreement between the two computational methods is demonstrated in a wide range of the pulse durations.

  18. Spinor dynamics-driven formation of a dual-beam atom laser.

    PubMed

    Lundblad, N; Thompson, R J; Aveline, D C; Maleki, L

    2006-10-30

    We demonstrate a novel dual-beam atom laser formed by outcoupling oppositely polarized components of an all-optical F = 1 spinor Bose-Einstein condensate whose Zeeman sublevel populations have been coherently evolved through spin dynamics. The condensate is formed through all-optical means using a single-beam running-wave dipole trap. We create a condensate in the magnetic field-insensitive m(F) = 0 state, and drive coherent spin-mixing evolution through adiabatic compression of the initially weak trap. Such dual beams, number-correlated through the angular momentum-conserving reaction 2m(0) ?m(+1) +m(-1), have been proposed as tools to explore entanglement and squeezing in Bose-Einstein condensates, and have potential use in precision phase measurements. PMID:19529412

  19. Parametrization of electron-impact ionization cross sections from laser-excited and aligned atoms.

    PubMed

    Nixon, Kate L; Murray, Andrew James

    2014-01-17

    A set of parameters describing electron-impact ionization from laser-aligned atoms are reported, which define the "length", "width", and "direction" of the quadruple differential cross section (QDCS) as a function of target alignment kB for fixed ingoing electron momentum k0 and outgoing momenta k1, k2. 24Mg was used, with k0, k1, k2, and kB in the same plane. The parameters are derived for a range of k2 angles, with k1 set at 30° to k0. The QDCS is then determined for all kB. The parameters are very angle sensitive, the QDCS direction varying more than 90° as the length to width ratio varied more than an order of magnitude. PMID:24484007

  20. Development of laser optogalvanic spectroscopy as a probe of alkali atoms in an MHD environment

    SciTech Connect

    Monts, D.L.; Qian, S.; Cook, R.L.; Shepard, W.S.

    1995-02-01

    Application of Laser Optogalvanic Spectroscopy (LOGS) to MHD combustion systems requires selection of an appropriate alkali atom electronic transition to monitor. These studies suggest that in MHD combustion systems, it is desirable to use cesium, which occurs as an impurity in potassium compounds, as a surrogate for potassium rather than to directly monitor potassium in order to obtain reliable determinations of seed concentration. Studies were also performed to investigate the effect of electrode corrosion on the normalized LOGS signal intensity at a fixed wavelength (578.238 nm). During six-hour experiments in a near-stoichiometric flame, the normalized LOGS signal intensity decreased by 40-50% for a -960 V rod electrode and by 10-20% for a -500 V rod electrode. These changes are attributed to buildup of an oxide coating on the electrode, reducing the collection efficiency of the electrode.

  1. Triple Differential Cross Sections for Ionization of Laser-Aligned Mg Atoms by electron impact

    NASA Astrophysics Data System (ADS)

    Amami, Sadek; Madison, Don; Nixon, Kate; Murray, Andrew

    2013-09-01

    3DW (3-body distorted wave) triple differential cross sections have been calculated for electron impact ionization of magnesium atoms aligned by lasers. Calculations have been performed for the kinematics of the experiment performed by Kate Nixon and Andrew Murray at Manchester, England [K. L. Nixon and A. J. Murray 2011 Phys. Rev. Lett. 106, 123201]. An incident projectile was produced with energy of 41.91eV, scattered and ejected electrons were detected with equal energies (E1 =E2 =20eV), the scattered projectile was detected at a fixed angle of 30deg, and the ejected electrons were detected at angles ranging between 0circ; - 180circ; . The theoretical 3DW results will be compared with the experimental data. This work is supported by the US National Science Foundation under Grant.No.PHY-1068237.

  2. Analysis of atomic and ion debris features of laser-produced Sn and Li plasmas

    SciTech Connect

    Coons, R. W.; Harilal, S. S.; Campos, D.; Hassanein, A.

    2010-09-15

    Tin and lithium plasmas emit efficiently in the in-band region (13.5 nm with 2% bandwidth) necessary for extreme ultraviolet (EUV) lithography. We have made a detailed comparison of the atomic and ionic debris, as well as the emission features of Sn and Li plasmas under identical experimental conditions. Planar slabs of pure Sn and Li were irradiated with 1064 nm, 9 ns neodymium-doped yttrium aluminum garnet laser pulses for producing plasmas. A suite of diagnostics were used to analyze the emission and debris features, including optical emission spectroscopy (OES), a Faraday cup, an EUV pinhole camera, the absolute measurement of EUV conversion efficiency (CE), etc. Our results show that Sn plasmas provide a CE nearly twice that of Li. However, the kinetic energies of Sn ions are considerably higher, though with a lower flux. OES studies have showed that the kinetic energies of neutral species are substantially lower compared to that of the charged particle species.

  3. Atomic kinetics for isochoric heating of solid aluminum under short intense XUV free electron laser irradiation

    NASA Astrophysics Data System (ADS)

    Deschaud, Basil; Peyrusse, Olivier; Rosmej, Frank B.

    2015-06-01

    An atomic configuration kinetics model that links the cold solid state, the heated solid state and the dilute plasma state is presented. It is based on a coherent implementation of the Fermi-Dirac statistics for the free electrons and a link between the cold solid elementary processes and the plasma elementary processes. This model allows us to follow the bound electron kinetics continuously from the cold solid state to the plasma state. The good agreement of the obtained spectra for the isochoric heating of solid aluminum under XUV free electron laser (XUVFEL) irradiation show the validity of this approach. The kinetics model has also been included in a 1D Lagrangian hydrodynamics code. This code is an essential tool for the design and the interpretation of warm/hot dense matter experiments.

  4. Laser absorption spectroscopy diagnostics of helium metastable atoms generated in dielectric barrier discharge cryoplasmas

    NASA Astrophysics Data System (ADS)

    Urabe, Keiichiro; Muneoka, Hitoshi; Stauss, Sven; Sakai, Osamu; Terashima, Kazuo

    2015-10-01

    Cryoplasmas, which are plasmas whose gas temperatures are below room temperature (RT), have shown dynamic changes in their physical and chemical characteristics when the gas temperature in the plasmas (Tgp) was decreased from RT. In this study, we measured the temporal behavior of helium metastable (Hem) atoms generated in a parallel-plate dielectric barrier discharge at ambient gas temperatures (Tga) of 300, 100, and 14 K and with a gas density similar to atmospheric conditions by laser absorption spectroscopy. The increments of Tgp to Tga were less than 20 K. We found from the results that the Hem lifetime and maximum density become longer and larger over one order of magnitude for lower Tga. The reasons for the long Hem lifetime at low Tga are decreases in the rate coefficients of three-body Hem quenching reactions and in the amounts of molecular impurities with boiling points higher than that of He.

  5. Breakthrough: X-ray Laser Captures Atoms and Molecules in Action

    ScienceCinema

    Bergmann, Uwe

    2014-05-21

    The Linac Coherent Light Source at SLAC is the world's most powerful X-ray laser. Just two years after turning on in 2009, breakthrough science is emerging from the LCLS at a rapid pace. A recent experiment used the X-rays to create and probe a 2-million-degree piece of matter in a controlled way for the first time-a significant leap toward understanding the extreme conditions found in the hearts of stars and giant planets, and a finding which could further guide research into nuclear fusion, the mechanism that powers the sun. Upcoming experiments will investigate the fundamental, atomic-scale processes behind such phenomena as superconductivity and magnetism, as well as peering into the molecular workings of photosynthesis in plants.

  6. Site evaluations for the uranium-atomic vapor laser isotope separation (U-AVLIS) production plant

    SciTech Connect

    Wolsko, T.; Absil, M.; Cirillo, R.; Folga, S.; Gillette, J.; Habegger, L.; Whitfield, R.

    1991-07-01

    This report describes a uranium-atomic vapor laser isotope separation (U-AVLIS) production plant siting study conducted during 1990 to identify alternative plant sites for examination in later environmental impact studies. A siting study methodology was developed in early 1990 and was implemented between June and December. This methodology had two parts. The first part -- a series of screening analyses that included exclusionary and other criteria -- was conducted to identify a reasonable number of candidates sites. This slate of candidate sites was then subjected to more rigorous and detailed comparative analysis for the purpose of developing a short list of reasonable alternative sites for later environmental examination. To fully appreciate the siting study methodology, it is important to understand the U-AVLIS program and site requirements. 16 refs., 29 figs., 54 tabs.

  7. Spectroscopic measurement of the vapour pressure of ice.

    PubMed

    Bielska, K; Havey, D K; Scace, G E; Lisak, D; Hodges, J T

    2012-06-13

    We present a laser absorption technique to measure the saturation vapour pressure of hexagonal ice. This method is referenced to the triple-point state of water and uses frequency-stabilized cavity ring-down spectroscopy to probe four rotation-vibration transitions of at wavenumbers near 7180?cm(-1). Laser measurements are made at the output of a temperature-regulated standard humidity generator, which contains ice. The dynamic range of the technique is extended by measuring the relative intensities of three weak/strong transition pairs at fixed ice temperature and humidity concentration. Our results agree with a widely used thermodynamically derived ice vapour pressure correlation over the temperature range 0C to -70C to within 0.35 per cent. PMID:22547230

  8. Investigations of ion-irradiated uranium dioxide nuclear fuel with laser-assisted atom probe tomography

    NASA Astrophysics Data System (ADS)

    Valderrama, Billy

    Performance in commercial light water reactors is dictated by the ability of its fuel material, uranium dioxide (UO2), to transport heat generated during the fission process. It is widely known that the service lifetime is limited by irradiation-induced microstructural changes that degrade the thermal performance of UO2. Studying the role of complex, often interacting mechanisms that occur during the early stages of microstructural evolution presents a challenge. Phenomena of particular interest are the segregation of fission products to form bubbles and their resultant effect on grain boundary (GB) mobility, and the effect of irradiation on fuel stoichiometry. Each mechanism has a profound consequence on fuel thermal conductivity. Several advanced analytical techniques, such as transmission electron microscopy, x-ray diffraction, x-ray photoelectron spectroscopy, etc. have been used to study these mechanisms. However, they each have limitations and cannot individually provide the necessary information for deeper understanding. One technique that has been under utilized is atom probe tomography (APT), which has a unique ability to spatially resolve small-scale chemical variations. APT uses the principle of field ionization to evaporate surface ions for chemical analysis. For low electrical conductivity systems, a pulsed laser is used to thermally assist in the evaporation process. One factor complicating the analysis is that laser-material interactions are poorly understood for oxide materials and literature using this technique with UO2 is lacking. Therefore, an initial systematic study to identify the optimal conditions for the analysis of UO2 using laser-assisted APT was conducted. A comparative study on the evaporation behavior between CeO2 and UO2 was followed. CeO2 was chosen due to its technological relevancy and availability of comparative studies with laser-assisted APT. Dissimilar evaporation behavior between these materials was identified and attributed to differences in laser absorption, oxide stability, and thermal conductivity between the two materials. After the conditions were identified, APT was utilized to study the role of temperature and GB structure on the segregation of Kr. Results indicate that high angle GBs contain more Kr relative to low angle GBs. The methodology presented can be applied to investigate small-scale chemical changes in other oxide materials.

  9. Sub-Doppler absorption narrowing in atomic vapor at two intense laser fields.

    PubMed

    Krmpot, Aleksandar; Mijailovi?, Marina; Pani?, Bratimir; Luki?, Dragan; Kovacevi?, Aleksander; Panteli?, Dejan; Jelenkovi?, Branislav

    2005-03-01

    We have experimentally studied electromagnetically induced transparency (EIT) and absorption (EIA) in hot 85Rb atomic vapor using probe and coupling light with comparable power levels. We have shown that strong-probe EIT has different linewidth and appears in fewer configurations than does usual, weak probe EIT. In V-scheme, where optical pumping and saturation are dominant mechanisms, narrow EIT is possible only when a probe is tuned to a closed transition. The width of the EIT resonance increases with laser intensity with non-linear dependence, similar to the weak-probe EIT in Lambda- scheme. The EIT in Lambda- scheme was observed when two transitions had balanced population losses. The EIA was modified for the case of a strong probe as well: in four-level N-scheme with Zeeman sublevels the EIA was observed only for a cycling transition when F'=F+1, where F and F' are the angular momenta of the 5 2S1/2 (ground) and 5 2P3/2 (excited) state hyper-fine levels, respectively. The combination of strong probe and strong coupling laser beam intensities allows observation of an absorption dip due to three-photon resonance in a four-level scheme that involves the Raman transitions via virtual level. PMID:19495020

  10. An atomic force microscopy statistical analysis of laser-induced azo-polyimide periodic tridimensional nanogrooves.

    PubMed

    Stoica, Iuliana; Epure, Luiza; Sava, Ion; Damian, Victor; Hurduc, Nicolae

    2013-09-01

    The surface morphology of azo-polyimide films was investigated after 355 nm Nd: YAG laser irradiation with two different incident fluencies. Atomic force microscopy (AFM) was employed to correlate the laser-induced tridimensional nanogrooved surface relief with the incident fluence and the number of irradiation pulses. The height images revealed that the grooves depth increased even tens of times by increasing the incident fluence, using the same numbers of irradiation pulses. For low incident fluence, the films were uniformly patterned till 100 pulses of irradiation. Instead, when using higher fluence, after 15 pulses of irradiation the accuracy of the surface relief definition was reduced. This behavior could be explained by means of two different mechanisms, one that suppose the film photo-fluidization due to the cis-trans isomerization processes of the azo-groups and the second one responsible for the directional mass displacement. The dominant surface direction and parameters like isotropy, periodicity, and period were evaluated from the polar representation for texture analysis, revealing the appearance of ordered and directionated nanostructures for most of the experimental conditions. Also, the graphical studies of the functional volume parameters have evidenced the improvement of the relief structuration during surface nanostructuration. The correlation of these statistical texture parameters with the irradiation characteristics is important in controlling the alignment of either the liquid crystals or the cells/tissues on patterned azo-polyimide surfaces for optoelectronic devices and implantable biomaterials, respectively. PMID:23801415

  11. Analysis of the production and clusterization of iron atoms under pulsed laser photolysis of Fe(CO)5

    NASA Astrophysics Data System (ADS)

    Gurentsov, E. V.; Eremin, A. V.; Priemchenko, K. Yu.

    2013-09-01

    Atomic-resonance absorption spectroscopy is used to study the production and loss of iron atoms under dissociation of the Fe(CO)5 vapor in a quartz reactor that is induced by the pulses of the KrF excimer laser. Iron atoms populate the ground state owing to the quenching of the excited states generated in the course of the laser photolysis and are detected using the resonance absorption at a wavelength of 385.99 nm. The effective quenching rates are in good agreement with the known rates of the quenching of metastable iron atoms by the Fe(CO)5 molecules. It is demonstrated that a loss of iron atoms is related to the recombination with dimer and trimer formation and the secondary atomic reactions with the Fe(CO)5, CO, and FeCO molecules. The rates of the main elementary reactions responsible for the loss of iron atoms are determined using the comparison of the experimental results and kinetic simulation data.

  12. Analysis of atomic distribution in as-fabricated Zircaloy-2 claddings by atom probe tomography under high-energy pulsed laser

    NASA Astrophysics Data System (ADS)

    Sawabe, T.; Sonoda, T.; Kitajima, S.; Kameyama, T.

    2013-11-01

    The properties of second-phase particles (SPPs) in Zircaloy-2 claddings are key factors influencing the corrosion resistance of the alloy. The chemical compositions of Zr (Fe, Cr)2 and Zr2(Fe, Ni) SPPs were investigated by means of pulsed laser atom probe tomography. In order to prevent specimen fracture and to analyse wide regions of the specimen, the pulsed laser energy was increased to 2.0 nJ. This gave a high yield of average of 3 107 ions per specimen. The Zr (Fe, Cr)2 SPPs contained small amounts of Ni and Si atoms, while in Zr2(Fe, Ni) SPPs almost all the Si was concentrated and the ratio of Zr: (Fe + Ni + Si) was 2:1. Atomic concentrations of the Zr-matrix and the SPPs were identified by two approaches: the first by using all the visible peaks of the mass spectrum and the second using the representative peaks with the natural abundance of the corresponding atoms. It was found that the change in the concentration between the Zr-matrix and the SPPs can be estimated more accurately by the second method, although Sn concentration in the Zr2(Fe, Ni) SPPs is slightly overestimated.

  13. Enhancement of visible He2 emission by infrared laser excitation of He metastable atoms in atmospheric-pressure plasma jet

    NASA Astrophysics Data System (ADS)

    Urabe, Keiichiro; Motomura, Hideki; Sakai, Osamu; Tachibana, Kunihide

    2011-02-01

    We observed bright red emission at an intersection of an infrared (IR) laser beam and an atmospheric-pressure plasma jet (APPJ). The APPJ had a coaxial dielectric barrier discharge configuration and generated a plasma plume in a He gas flow ejected into air from a glass capillary. Although the laser-beam wavelength was 1083 nm corresponding to He I (23P-23S) atomic transition, the enhanced red emission peaked in the visible region at 640 nm and had broad bandwidth corresponding to He2 (d\\,^{3}\\!\\Sigma_u^{+}{{--}}b\\,^{3}\\Pi _g) molecular transition. This result indicates that the IR laser excitation of He metastable (23S) atoms leads to selective formation of excited He2 (d\\,^{3}\\!\\Sigma_u^{+}) molecules from excited He (23P) atoms. The 640 nm emission intensity decreased as the laser beam moved downstream in the plasma plume, because of the quenching effects on the excited He atoms and the excited He2 molecules by air entrainment. We believe that the He2 (d\\,^{3}\\!\\Sigma_u^{+}) molecular formation follows two potential curves of He2 (f 3Σu or f 3Πu) and (d\\,^{3}\\!\\Sigma_u^{+}) states, overcoming a potential hump by three-body collision processes.

  14. Rotationally resolved hot atom collisional excitation of CO2(0001) by time-resolved diode laser spectroscopy

    NASA Astrophysics Data System (ADS)

    O'Neill, James A.; Wang, Chen Xi; Ye Cai, Ji; Flynn, George W.; Weston, Ralph E., Jr.

    1986-10-01

    A tunable infrared diode laser was used to study the nascent rotationa distribution of CO2 molecules produced directly in the 0001 excited state as a result of collisions with hot hydrogen atoms formed in the UV photolysis of H2S.(AIP)

  15. Performance predictions of a focused ion beam from a laser cooled and compressed atomic beam

    SciTech Connect

    Haaf, G. ten; Wouters, S. H. W.; Vredenbregt, E. J. D.; Mutsaers, P. H. A.; Geer, S. B. van der

    2014-12-28

    Focused ion beams are indispensable tools in the semiconductor industry because of their ability to image and modify structures at the nanometer length scale. Here, we report on performance predictions of a new type of focused ion beam based on photo-ionization of a laser cooled and compressed atomic beam. Particle tracing simulations are performed to investigate the effects of disorder-induced heating after ionization in a large electric field. They lead to a constraint on this electric field strength which is used as input for an analytical model which predicts the minimum attainable spot size as a function of, amongst others, the flux density of the atomic beam, the temperature of this beam, and the total current. At low currents (I < 10 pA), the spot size will be limited by a combination of spherical aberration and brightness, while at higher currents, this is a combination of chromatic aberration and brightness. It is expected that a nanometer size spot is possible at a current of 1 pA. The analytical model was verified with particle tracing simulations of a complete focused ion beam setup. A genetic algorithm was used to find the optimum acceleration electric field as a function of the current. At low currents, the result agrees well with the analytical model, while at higher currents, the spot sizes found are even lower due to effects that are not taken into account in the analytical model.

  16. Vapour Intrusion into Buildings - A Literature Review

    EPA Science Inventory

    This chapter provides a review of recent research on vapour intrusion of volatile organic compounds (VOCs) into buildings. The chapter builds on a report from Tillman and Weaver (2005) which reviewed the literature on vapour intrusion through 2005. Firstly, the term vapour intru...

  17. Vapour Intrusion into Buildings - A Literature Review

    EPA Science Inventory

    This chapter provides a review of recent research on vapour intrusion of volatile organic compounds (VOCs) into buildings. The chapter builds on a report from Tillman and Weaver (2005) which reviewed the literature on vapour intrusion through 2005. Firstly, the term ‘vapour intru...

  18. Diagnostics of Carbon Nanotube Formation in a Laser Produced Plume: An Investigation of the Metal Catalyst by Laser Ablation Atomic Fluorescence Spectroscopy

    NASA Technical Reports Server (NTRS)

    deBoer, Gary; Scott, Carl

    2003-01-01

    Carbon nanotubes, elongated molecular tubes with diameters of nanometers and lengths in microns, hold great promise for material science. Hopes for super strong light-weight material to be used in spacecraft design is the driving force behind nanotube work at JSC. The molecular nature of these materials requires the appropriate tools for investigation of their structure, properties, and formation. The mechanism of nanotube formation is of particular interest because it may hold keys to controlling the formation of different types of nanotubes and allow them to be produced in much greater quantities at less cost than is currently available. This summer's work involved the interpretation of data taken last summer and analyzed over the academic year. The work involved diagnostic studies of carbon nanotube formation processes occurring in a laser-produced plume. Laser ablation of metal doped graphite to produce a plasma plume in which carbon nanotubes self assemble is one method of making carbon nanotube. The laser ablation method is amenable to applying the techniques of laser spectroscopy, a powerful tool for probing the energies and dynamics of atomic and molecular species. The experimental work performed last summer involved probing one of the metal catalysts, nickel, by laser induced fluorescence. The nickel atom was studied as a function of oven temperature, probe laser wavelength, time after ablation, and position in the laser produced plume. This data along with previously obtained data on carbon was analyzed over the academic year. Interpretations of the data were developed this summer along with discussions of future work. The temperature of the oven in which the target is ablated greatly influences the amount of material ablated and the propagation of the plume. The ablation conditions and the time scale of atomic and molecular lifetimes suggest that initial ablation of the metal doped carbon target results in atomic and small molecular species. The metal atoms survive for several milliseconds while the gaseous carbon atoms and small molecules nucleate more rapidly. Additional experiments and the development of in situ methods for carbon nanotube detection would allow these results to be interpreted from the perspective of carbon nanotube formation.

  19. Analysis of geological samples by atomic emission spectroscopy of plasmas induced by laser ablation at low pressures

    NASA Astrophysics Data System (ADS)

    Pavlov, S.; Schrder, S.; Jessberger, E.; Hbers, H.

    2011-12-01

    Elemental analysis of geologic samples based on atomic emission spectroscopy is currently considered for several future space lander missions to planets, moons and asteroids in solar system. The spectroscopic techniques, called laser-induced plasma (breakdown) spectroscopy (LIBS), provides quantitatively the microscopic in-situ abundances of all major and many trace elements of surfaces of solar system bodies. Excitation and evolution of the plasmas induced by lasers depend on the properties of the investigated material and on environmental conditions. This study focuses on the feasibility of spectroscopy of plasmas induced by low-energy laser (below 1 mJ per pulse) for the exploration of solar system bodies with thin atmospheres (pressures below 1 mPa). At such low pressures the excited plasmas have small plumes and expand very rapidly, which limits both the LIBS signal intensity and the available acquisition time. This, in turn, requires usually relatively powerful laser sources to create a detectable LIBS plasma. The low pressure conditions are simulated in a dedicated chamber at the DLR-Berlin Institute of Planetary Research, that can hold the Martian-like atmosphere or high vacuum conditions. Two infrared Q-switched lasers are used for comparative investigation of atomic emission spectra: Firstly, a Nd:YAG laser (Inlite, Continuum) operating at 1064 nm and at 10 Hz, pulse energy up to 230 mJ at 8-10 ns pulse duration and, secondly, developed for future planetary missions Nd:YLF laser (NeoLASE) operating at 1053 nm and at 10-50 Hz, pulse energy up to 3 mJ at 3-5 ns pulse duration. The emitted light of the laser-induced plasma is analysed by an echelle spectrometer (LTB Aryelle Butterfly) covering the wavelength range of 280-900 nm with a spectral resolution of around 104. Identification of atomic transitions is performed using the LTB built-in spectrometer software by comparison with the NIST spectral database. Several basaltic rock and sediment standards were crushed to powder and pressed into pellets. Reduction of both pressure and laser excitation energy results in a significant decrease of the signal-to-noise ratio for most atomic lines (an exception are the widely broadened lines of H). However, the detection of atomic emission lines of elements with relative abundances above 10-3 (0.1 wt%) - Al, Ca, Cr, H, K, Mg, Mn, Na, Ni, O, Si, Ti, - is possible down to a laser excitation energy of 0.9 mJ (laser irradiance on the sample surface 46 MW/mm2). Additionally, the detection of carbon and sulphur, having strong atomic transitions in ultraviolet range, can be expected by extension of the spectral range of the LIBS spectrometer to 190 nm. Atomic doublet and triplet transitions, broadened by atomic collisions at ambient pressures (100 kPa), become spectrally resolved and are identified below 1 mPa. This demonstrates the feasibility of miniaturized laser-induced breakdown spectrometry for space missions to solar bodies with absent or thin atmospheres.

  20. Parameters of an electric-discharge generator of iodine atoms for a chemical oxygen-iodine laser

    SciTech Connect

    Azyazov, V N; Vorob'ev, M V; Voronov, A I; Kupryaev, Nikolai V; Mikheev, P A; Ufimtsev, N I

    2009-01-31

    Laser-induced fluorescence is used for measuring the concentration of iodine molecules at the output of an electric-discharge generator of atomic iodine. Methyl iodide CH{sub 3}I is used as the donor of atomic iodine. The fraction of iodine extracted from CH{sub 3}I in the generator is {approx}50%. The optimal operation regimes are found in which 80%-90% of iodine contained in the output flow of the generator was in the atomic state. This fraction decreased during the iodine transport due to recombination and was 20%-30% at the place where iodine was injected into the oxygen flow. The fraction of the discharge power spent for dissociation was {approx}3%. (elements of laser setups)

  1. Electron-ion dynamics in laser-assisted desorption of hydrogen atoms from H-Si(111) surface

    SciTech Connect

    Bubin, Sergiy; Varga, Kalman

    2011-09-15

    In the framework of real time real space time-dependent density functional theory we have studied the electron-ion dynamics of a hydrogen-terminated silicon surface H-Si(111) subjected to intense laser irradiation. Two surface fragments of different sizes have been used in the simulations. When the intensity and duration of the laser exceed certain levels (which depend on the wavelength) we observe the desorption of the hydrogen atoms, while the underlying silicon layer remains essentially undamaged. Upon further increase of the laser intensity, the chemical bonds between silicon atoms break as well. The results of the simulations suggest that with an appropriate choice of laser parameters it should be possible to remove the hydrogen layer from the H-Si(111) surface in a matter of a few tens of femtoseconds. We have also observed that at high laser field intensities (2-4 V/A in this work) the desorption occurs even when the laser frequency is smaller than the optical gap of the silicon surface fragments. Therefore, nonlinear phenomena must play an essential role in such desorption processes.

  2. Pump-probe study of atoms and small molecules with laser driven high order harmonics

    NASA Astrophysics Data System (ADS)

    Cao, Wei

    A commercially available modern laser can emit over 1015 photons within a time window of a few tens of femtoseconds (10-15second), which can be focused into a spot size of about 10 mum, resulting in a peak intensity above 1014W/cm2. This paves the way for table-top strong field physics studies such as above threshold ionization (ATI), non-sequential double ionization (NSDI), high order harmonic generation (HHG), etc.. Among these strong laser-matter interactions, high order harmonic generation, which combines many photons of the fundamental laser field into a single photon, offers a unique way to generate light sources in the vacuum ultraviolet (VUV) or extreme ultraviolet (EUV) region. High order harmonic photons are emitted within a short time window from a few tens of femtoseconds down to a few hundreds of attoseconds (10 -18second). This highly coherent nature of HHG allows it to be synchronized with an infrared (IR) laser pulse, and the pump-probe technique can be adopted to study ultrafast dynamic processes in a quantum system. The major work of this thesis is to develop a table-top VUV(EUV) light source based on HHG, and use it to study dynamic processes in atoms and small molecules with the VUV(EUV)-pump IR-probe method. A Cold Target Recoil Ion Momentum Spectroscopy (COLTRIMS) apparatus is used for momentum imaging of the interaction products. Two types of high harmonic pump pulses are generated and applied for pump-probe studies. The first one consists of several harmonics forming a short attosecond pulse train (APT) in the EUV regime (around 40 eV). We demonstrate that, (1) the auto-ionization process triggered by the EUV in cation carbon-monoxide and oxygen molecules can be modified by scanning the EUV-IR delay, (2) the phase information of quantum trajectories in bifurcated high harmonics can be extracted by performing an EUV-IR cross-correlation experiment, thus disclosing the macroscopic quantum control in HHG. The second type of high harmonic source implemented in this work is a single harmonic in the VUV regime (around 15 eV) filtered out from a monochromator. Experiments on D2 molecules have been conducted using the 9th or the 11th harmonic as the pump pulse. Novel dissociative ionization pathways via highly excited states of D 2 have been revealed, thus suggesting potential applications for time-resolved studies and control of photochemistry processes.

  3. Radiative properties of Z-pinch and laser produced plasmas from mid-atomic-number materials

    NASA Astrophysics Data System (ADS)

    Ouart, Nicholas D.

    The investigation of Z-pinches on university-scale pulsed power generators allows for the study of plasmas with a broad range of temperatures, densities, and sizes in cost effective experiments. In particular, X-pinches produce the hottest and densest plasma and are very suitable for x-ray radiation studies. The planar wire array has shown to be a powerful radiation source on the 1 MA Zebra generator at UNR. The radiative and implosion dynamics from such loads with mid-atomic-number materials were not studied previously in detail and are a topic of this dissertation. Specifically, the radiative and implosion characteristics of Z-pinch and X-pinch plasmas with mid-atomic-number materials (iron, nickel, copper, and zinc) will be discussed. The theoretical tool used to accomplish this is non-LTE kinetic modeling. This tool is not limited to Z-pinches, but can be applied to any plasma radiation source like laser produced plasmas which will be demonstrated. In addition, since the radiative characteristics of wire arrays are connected with the implosion characteristics, another theoretical tool, the Wire Ablation Dynamics Model was used in this dissertation to understand the ablation and implosion dynamics of wire arrays. The experiments were analyzed from two university-scale pulsed power machines: the 1 MA Zebra and COBRA generators. The research completed in this dissertation emphasizes the unique capabilities and usefulness of spectroscopy, particularly time-gated x-ray spectroscopy. For example, modeling of time-gated L-shell spectra captured from the precursor column of low-wire-number copper cylindrical wire arrays reveals electron temperatures 400 eV, which is significantly higher than any previous precursor measurements. From the analysis of experiments on COBRA, total energy was higher for the implosion of a compact cylindrical wire array made with alternating brass and aluminum wires than a uniform wire array made with just brass or aluminum. Comparison of L-shell radiation from mid-atomic-number wires placed in the inner or outer array from nested wire array implosions on COBRA shows that the material radiates more when placed on the outer array. Using different materials on the outer and inner arrays provides a unique opportunity to study the implosion dynamics of nested wire arrays, especially when using time-gated spectroscopy. Brass planar wire arrays represent a unique opportunity to study the performance of two L-shell radiators from mid-atomic-number materials (copper and zinc) at the same time in experiments on Zebra. The ablation and implosion dynamics of the single- and double-planar wire arrays was investigated and completed. Non-LTE kinetic modeling was used to describe the radiation from simultaneous measurements of K- and L-shell radiation from the interaction of a femtosecond laser system with an iron target. The K- and L-shell radiation originates from two distinct plasma regions. The L-shell radiation was emitted from a region of plasma created by the prepulse and modeling showed moderate electron temperatures and electron densities. The cold iron Kalpha line manifested from a region of plasma that was heated by hot electrons interacting with the solid dense iron target. K-shell modeling showed electron temperatures of tens of eV and less than 1% hot electrons. To study the time history of cold Kalpha lines for mid-atomic-number materials, experiments with planar wire arrays were performed on Zebra. Continuation of this study was accomplished using X-pinches to allow for the simultaneous measurements in time of hotter ionic and cold K-shell lines.

  4. Compositional and morphological imaging of CO2 laser irradiated human teeth by low vacuum SEM, confocal laser scanning microscopy and atomic force microscopy.

    PubMed

    Watari, F

    2001-03-01

    Enamel and dentin of human teeth irradiated by CO2 laser were investigated by confocal laser scanning microscopy (CLSM), low vacuum scanning electron microscopy (WET-SEM) and atomic force microscopy (AFM). Optical tomographic imaging by CLSM, compositional imaging based on atomic number effect of reflected electrons by WET-SEM, high resolution observation of surface morphology by AFM were done for both the irradiated and non-irradiated area of the same specimen throughout. The crystals of about 50 microm length and the bright spots were observed by CLSM at the bottom of the cavity induced by laser irradiation. They turned out from the observation by WET-SEM as the acicular crystals with the cross section of an irregularly hexagonal shape situated parallel and perpendicular, respectively, to the inner surface of the cavity. The thickness of the thermally deteriorated zone of the cavity was about 25 microm. The crystals unidirectionally grown up to the size of several hundreds nm were also observed by AFM, while the apatite crystallites of 50-150 nm were recognized all over in non-irradiated area. All the results suggest that after instantaneous melting at the surface of teeth by CO2 laser shot the crystals of calcium phosphate were recrystalized and grown to a large size. The compositional imaging in addition to morphological observation was useful to obtain the information of the change in materials induced by laser irradiation. PMID:15348301

  5. Self-injection and acceleration of electrons during ionization of gas atoms by a short laser pulse

    SciTech Connect

    Singh, K.P.

    2006-04-15

    Using a relativistic three-dimensional single-particle code, acceleration of electrons created during the ionization of nitrogen and oxygen gas atoms by a laser pulse has been studied. Barrier suppression ionization model has been used to calculate ionization time of the bound electrons. The energy gained by the electrons peaks for an optimum value of laser spot size. The electrons created near the tail do not gain sufficient energy for a long duration laser pulse. The electrons created at the tail of pulse escape before fully interacting with the trailing part of the pulse for a short duration laser pulse, which causes electrons to retain sufficient energy. If a suitable frequency chirp is introduced then energy of the electrons created at the tail of the pulse further increases.

  6. Non-contact quantification of laser micro-impulse in water by atomic force microscopy and its application for biomechanics

    NASA Astrophysics Data System (ADS)

    Hosokawa, Yoichiroh

    2011-12-01

    We developed a local force measurement system of a femtosecond laser-induced impulsive force, which is due to shock and stress waves generated by focusing an intense femtosecond laser into water with a highly numerical aperture objective lens. In this system, the force localized in micron-sized region was detected by bending movement of a cantilever of atomic force microscope (AFM). Here we calculated the bending movement of the AFM cantilever when the femtosecond laser is focused in water at the vicinity of the cantilever and the impulsive force is loaded on the cantilever. From the result, a method to estimate the total of the impulsive force at the laser focal point was suggested and applied to estimate intercellular adhesion strength.

  7. OROCHI experiment: Laser spectroscopy of RI atoms in superfluid helium for measurements of nuclear spins and electromagnetic moments

    NASA Astrophysics Data System (ADS)

    Furukawa, Takeshi

    2014-09-01

    We have been developing a new laser spectroscopy technique named as OROCHI (Optical RI-atom Observation in Condensed Helium as Ion-catcher) for measurements of nuclear spins and electromagnetic moments of low yield exotic radioisotopes (RIs). In this technique, we use superfluid helium (He II) liquid as a stopping material of RI beam in which in-situ laser spectroscopy of the RI atoms stopped in He II is carried out. The characteristic features of He II, i.e. high trapping efficiency of He II liquid for accelerated ion beams and the characteristics of atomic spectra in He II, enables us to measure the nuclear spins and moments of the extremely low yield RIs. So far, we have demonstrated the feasibility of our method to deduce the nuclear spins and moments with stable Rb, Cs, Ag and Au isotopes supplied into He II by laser sputtering technique. In addition, we have also succeeded in observing laser-radiowave/microwave double resonance signals of 84-87Rb atoms injected into He II as energetic ion beam. In these on-line experiment, the 84-87Rb isotope beams (intensity: up to 105 particles/s) were provided with RIPS beamline in RIKEN, and introduced into He II filled in a cryostat. Special care was taken in controlling the stopping position of injected Rb isotopes. Aluminum energy degraders of varied thickness from 0 to 0.8 mm were placed upstream of the beam injection window of the He II cryostat for optimizing the stopping position The 84-87Rb atoms stopped and then neutralized in He II were optically pumped and polarized with circularly polarized pumping laser light whose wavelength were tuned to 780 nm, D1 absorption line of Rb atoms in He II. The polarized atoms were subjected to irradiation of radiowave or microwave, and then we demonstrated the double resonance spectroscopy for observing the Zeeman transition of 84-87Rb atoms and the hyperfine transition of 87Rb, respectively In this presentation we will show the details of OROCHI technique and the present status of our development, in particular the result of the recent on-line experiment.

  8. Breakdown and dc discharge in low-pressure water vapour

    NASA Astrophysics Data System (ADS)

    Sivo, J.; koro, N.; Mari?, D.; Malovi?, G.; Petrovi?, Z. Lj

    2015-10-01

    In this paper we report studies of basic properties of breakdown, low-current Townsend discharge and high-current discharge regimes in water vapour. Paschen curves and the corresponding distributions of emission intensities at low current were recorded in the range of pd (pressure x electrode gap) from 0.1 to 10 Torrcm covering the region of Paschen minimum. From the experimental profiles we obtained effective ionization coefficient of water vapour for the E/N range 650?Td-7?kTd and fitted the results by using the extended Townsend analytical formula. Using the obtained ionization coefficient, we calculated the effective yield of secondary electrons from the copper cathode. Results of the measurements of Volt-Ampere characteristics in water vapour were presented together with the images of the axial structure of the discharge in a wide range of discharge currents for two pd values. Recorded profiles showed development of the spatial structure of the discharge in different operating regimes. We were able to identify conditions where processes induced by heavy particles, probably fast hydrogen atoms, are dominant in inducing emission from the discharge. Finally, standard scaling laws were tested for low current and glow discharges in water vapour.

  9. No sodium in the vapour plumes of Enceladus.

    PubMed

    Schneider, Nicholas M; Burger, Matthew H; Schaller, Emily L; Brown, Michael E; Johnson, Robert E; Kargel, Jeffrey S; Dougherty, Michele K; Achilleos, Nicholas A

    2009-06-25

    The discovery of water vapour and ice particles erupting from Saturn's moon Enceladus fuelled speculation that an internal ocean was the source. Alternatively, the source might be ice warmed, melted or crushed by tectonic motions. Sodium chloride (that is, salt) is expected to be present in a long-lived ocean in contact with a rocky core. Here we report a ground-based spectroscopic search for atomic sodium near Enceladus that places an upper limit on the mixing ratio in the vapour plumes orders of magnitude below the expected ocean salinity. The low sodium content of escaping vapour, together with the small fraction of salt-bearing particles, argues against a situation in which a near-surface geyser is fuelled by a salty ocean through cracks in the crust. The lack of observable sodium in the vapour is consistent with a wide variety of alternative eruption sources, including a deep ocean, a freshwater reservoir, or ice. The existing data may be insufficient to distinguish between these hypotheses. PMID:19553993

  10. Characterization of energetic and thermalized sputtered tungsten atoms using tuneable diode-laser induced fluorescence in direct current magnetron discharge

    NASA Astrophysics Data System (ADS)

    Desecures, M.; de Poucques, L.; Bougdira, J.

    2015-02-01

    In this study a tuneable diode-laser induced fluorescence (TD-LIF) technique (?0 = 407.4358 nm) is used to determine the atoms' velocity distribution function (AVDF) of energetic and thermalized sputtered tungsten (W) atoms in direct current magnetron discharge. The AVDF is characterized by probing the plasma above the centre of the target racetrack along the magnetron cathode axis in an argon-helium (Ar-He) mixture. Quantitative absorption measurements corroborated by deposition on silicon substrates are used to calibrate the TD-LIF relative measurements. Density, flux, temperature, AVDF and the flux velocity distribution function are derived from fitting the TD-LIF signals with four Gaussians (thermalized atoms) and four (energetic atom) functions (Stepanova and Dew 2004 Nucl. Instrum. Methods Phys. Res. B 215 357) taking into account the natural abundance and resonance wavelength shifts of the four main isotopes. Measurements show transport improvement for W atoms and an increase of the ratio of Ar ions to Ar neutrals with the increase of the percentage of He. All measurements are performed at 0.4 Pa and 100 W. The mean velocity of energetic W atoms typically ranges from 1900 to 2200 m s-1. The densities of thermalized and energetic atoms are in the same order of magnitude (109 cm-3) and their corresponding fluxes are several tens of times higher for energetic atoms (1015 cm-2 s-1).

  11. Numerical solutions of the time-dependent Schroedinger equation for atoms and molecules in intense laser fields

    NASA Astrophysics Data System (ADS)

    Guan, Xiaoxu

    2015-03-01

    Recent progress in ab initio computational methods allows us to treat the laser-atom, laser-molecule interaction, and other collision processes with improved accuracy. Full-dimensional quantum calculations for even a few particles are extremely demanding because of the unfavorable scaling of the full quantum wave function, but they are of significant importance for understanding the entangled response of electrons and nuclei in a system strongly influenced by intense lasers and particle beams. In this talk I will concentrate on the applications of grid-based approaches to the time-dependent problems of atoms and molecules driven by intense ultrafast laser pulses. The spatial coordinates are discretized via the finite-element discrete-variable representation. Examples include ionization dynamics in complete breakup processes through few-photon absorption in helium atoms and hydrogen molecules, and also time-delayed attosecond transient absorption spectra in helium. This work was supported by DOE DE-FG02-13ER16403, NSF PHY-0757755, NSF PHY-1068140, and XSEDE PHY-090031.

  12. Improved production of Br atoms near zero speed by photodissociating laser aligned Br{sub 2} molecules

    SciTech Connect

    Deng, L. Z. Yin, J. P.

    2014-10-28

    We theoretically investigated the improvement on the production rate of the decelerated bromine (Br) atoms near zero speed by photodissociating laser aligned Br{sub 2} precursors. Adiabatic alignment of Br{sub 2} precursors exposed to long laser pulses with duration on the order of nanoseconds was investigated by solving the time-dependent Schrödinger equation. The dynamical fragmentation of adiabatically aligned Br{sub 2} precursors was simulated and velocity distribution of the Br atoms produced was analyzed. Our study shows that the larger the degree of the precursor alignment, 〈cos{sup 2} θ〉, the higher the production rate of the decelerated Br atoms near zero speed. For Br{sub 2} molecules with an initial rotational temperature of ∼1 K, a 〈cos{sup 2} θ〉 value of ∼0.88 can result in an improvement factor of over ∼20 on the production rate of the decelerated Br atoms near zero speed, requiring a laser intensity of only ∼1 × 10{sup 12} W/cm{sup 2} for alignment.

  13. Reactive quenching of two-photon excited xenon atoms by Cl/sub 2/. [Xenon chloride laser

    SciTech Connect

    Bruce, M.R.; Layne, W.B.; Meyer, E.; Keto, J.W.

    1987-01-01

    Total binary and tertiary quench rates have been measured for the reaction Xe (5p/sup 5/6p) + Cl/sub 2/ at thermal temperatures. Xenon atoms are excited by state-selective, two-photon absorption with a uv laser. The time dependent fluorescence from the excited atom in the IR and from XeCl* (B) product near 308 nm have been measured with subnanosecond time resolution. The decay rates are measured as a function of Cl/sub 2/ pressure to 20 Torr and Xe pressure to 400 Torr. The measured reaction rates (k/sub 2/ approx. 10/sup -9/ cm/sup 3/sec/sup -1/) are consistent with a harpoon model described in a separate paper. We also measure large termolecular reaction rates for collisions with xenon atoms (k/sub 3/ approx. 10/sup -28/ cm/sup 6/sec/sup -1/). Total product fluorescence has been examined using a gated optical multichannel analyzer. We measure unit branching fractions for high vibrational levels of XeCl* (B) with very little C state fluorescence observed. The measured termolecular rates suggest similar processes will dominate at the high buffer-gas pressures used in XeCl lasers. The effect of these large reactive cross sections for neutral xenon atoms on models of the XeCl laser will be discussed.

  14. Multiphoton ionization of the calcium atom by linearly and circularly polarized laser fields

    SciTech Connect

    Buica, Gabriela; Nakajima, Takashi

    2010-04-15

    We theoretically study multiphoton ionization of the Ca atom irradiated by the second (photon energy 3.1 eV) and third (photon energy 4.65 eV) harmonics of Ti:sapphire laser pulses (photon energy 1.55 eV). Because of the dense energy level structure the second and third harmonics of a Ti:sapphire laser are nearly single-photon resonant with the 4s4p {sup 1}P{sup o} and 4s5p {sup 1}P{sup o} states, respectively. Although two-photon ionization takes place through the near-resonant intermediate states with the same symmetry in both cases, it turns out that there are significant differences between them. The photoelectron energy spectra exhibit the absence or presence of substructures. More interestingly, the photoelectron angular distributions clearly show that the main contribution to the ionization processes by the third harmonic arises from the far-off-resonant 4s4p {sup 1}P{sup o} state rather than the near-resonant 4s5p {sup 1}P{sup o} state. These findings can be attributed to the fact that the dipole moment for the 4s{sup 2} {sup 1}S{sup e}-4s5p {sup 1}P{sup o} transition is much smaller than that for the 4s{sup 2} {sup 1}S{sup e}-4s4p {sup 1}P{sup o} transition.

  15. Frequency control of tunable lasers using a frequency-calibrated ?-meter in an experiment on preparation of Rydberg atoms in a magneto-optical trap

    NASA Astrophysics Data System (ADS)

    Saakyan, S. A.; Sautenkov, V. A.; Vilshanskaya, E. V.; Vasiliev, V. V.; Zelener, B. B.; Zelener, B. V.

    2015-09-01

    A new technique is proposed and applied to study the frequency drift of an external-cavity semiconductor laser, locked to the transmission resonances of a thermally stabilised Fabry-Perot interferometer. The interferometer frequency drift is measured to be less than 2 MHz h-1. The laser frequency is measured using an Angstrom wavemeter, calibrated using an additional stabilised laser. It is shown that this system of laser frequency control can be used to identify Rydberg transitions in ultracold 7Li atoms.

  16. Manipulating state-selective charge exchange in laser-assisted collisions of He2+ with atomic H

    NASA Astrophysics Data System (ADS)

    Domnguez-Gutirrez, F. Javier; Cabrera-Trujillo, R.

    2013-09-01

    We solve the time-dependent Schrdinger equation within a finite-differences approach and the propagation Crank-Nicolson method to calculate the n = 2, 3, and total electron capture cross section of He2+ colliding with atomic H in the energy collision range 0.25-35 keV/amu. We use a laser pulse of 3, 2, and 1 fs at FHWM, wavelength of 800 nm and intensity 3.15 1012 W/cm2. We demonstrate that the laser assistance in the collision increases an order of magnitude the electron charge capture in the 0.25-2 keV/amu energy collision range. We compare our numerical results with those obtained experimentally for the laser-free case to asses the validity of our method. Also, we study the effect of the laser pulse in the excitation cross-section for n =2 states of the hydrogen atom and the dependence of the charge exchange as function of the FWHM of the laser pulse. We acknowledge support from CONACyT and PAPIIT IN-101-611.

  17. Spatial dynamics of laser-induced fluorescence in an intense laser beam: An experimental and theoretical study with alkali-metal atoms

    NASA Astrophysics Data System (ADS)

    Auzinsh, M.; Berzins, A.; Ferber, R.; Gahbauer, F.; Kalnins, U.

    2016-03-01

    We show that it is possible to model accurately optical phenomena in intense laser fields by taking into account the intensity distribution over the laser beam. We present an extension of an earlier theoretical model that divides an intense laser beam into concentric regions, each with a Rabi frequency that corresponds to the intensity in that region, and solve a set of coupled optical Bloch equations for the density matrix in each region. Experimentally obtained magneto-optical resonance curves for the Fg=2 ⟶Fe=1 transition of the D1 line of 87Rb agree very well with the theoretical model up to a laser intensity of around 200 mW/cm2 for a transition whose saturation intensity is around 4.5 mW/cm2. We examine the spatial dependence of the fluorescence intensity in an intense laser beam experimentally and theoretically. We present and discuss the results of an experiment in which a broad, intense pump laser excites the Fg=4 ⟶Fe=4 transition of the D2 line of cesium while a narrow probe beam scans the atoms within the pump beam and excites the D1 line of cesium, whose fluorescence is recorded as a function of probe beam position. Experimentally obtained spatial profiles of the fluorescence intensity agree qualitatively with the predictions of the model.

  18. Topotactic changes on ?-Mo4O11 caused by biased atomic force microscope tip and cw-laser

    NASA Astrophysics Data System (ADS)

    Borovak, Milo; utar, Petra; Goreshnik, Evgeny; Mihailovic, Dragan

    2015-11-01

    We present topotactic changes on Mo4O11 crystals induced by a biased atomic force microscope tip and continuous laser. The transformation does not change the topography of the samples, while the surface potential shows remarkable changes on areas where the biased AFM tip was applied. No structural changes were observed by Raman spectroscopy, but AFM scans revealed changes to surface potential due to laser illumination. The observed phenomenon could be potentially useful for memristive memory devices considering the fact that properties of other molybdenum oxides vary from metallic to insulators.

  19. Role of Photoexcitation and Field Ionization in the Measurement of Accurate Oxide Stoichiometry by Laser-Assisted Atom Probe Tomography

    SciTech Connect

    Devaraj, Arun; Colby, Robert J.; Hess, Wayne P.; Perea, Daniel E.; Thevuthasan, Suntharampillai

    2013-03-06

    Pulsed lasers extend the high spatial and mass resolution of atom probe tomography (APT) to non-conducting materials, such as oxides. For prototypical metal oxide MgO, measured stoichiometry depends strongly upon pulse energy and applied voltage. Very low laser energies (0.02 pJ) and high electric fields yield optimal stoichiometric accuracy, attributed to the field-dependent ionization of photo-desorbed O or O2 neutrals. This emphasizes the importance of considering electronic excitations in APT analysis of oxides ionic materials.

  20. Angular distribution of atoms emitted from a SrZrO{sub 3} target by laser ablation under different laser fluences and oxygen pressures

    SciTech Connect

    Konomi, I.; Motohiro, T.; Azuma, H.; Asaoka, T.; Nakazato, T.; Sato, E.; Shimizu, T.; Fujioka, S.; Sarukura, N.; Nishimura, H.

    2010-05-15

    Angular distributions of atoms emitted by laser ablation of perovskite-type oxide SrZrO{sub 3} have been investigated using electron probe microanalysis with wavelength-dispersive spectroscopy and charge-coupled device photography with an interference filter. Each constituent element has been analyzed as a two-modal distribution composed of a broad cos{sup m} {theta} distribution and a narrow cos{sup n} {theta} distribution. The exponent n characterizes the component of laser ablation while the exponent m characterizes that of thermal evaporation, where a larger n or m means a narrower angular distribution. In vacuum, O (n=6) showed a broader distribution than those of Sr (n=16) and Zr (n=17), and Sr{sup +} exhibited a spatial distribution similar to that of Sr. As the laser fluence was increased from 1.1 to 4.4 J/cm{sup 2}, the angular distribution of Sr became narrower. In the laser fluence range of 1.1-4.4 J/cm{sup 2}, broadening of the angular distribution of Sr was observed only at the fluence of 1.1 J/cm{sup 2} under the oxygen pressure of 10 Pa. Monte Carlo simulations were performed to estimate approximately the energy of emitted atoms, focusing on the broadening of the angular distribution under the oxygen pressure of 10 Pa. The energies of emitted atoms were estimated to be 1-20 eV for the laser fluence of 1.1 J/cm{sup 2}, and more than 100 eV for 2.2 and 4.4 J/cm{sup 2}.

  1. Broad-band laser optical pumping of Rb for the creation of nuclear polarisation in {sup 3}He

    SciTech Connect

    Kolachevsky, Nikolai N; Papchenko, A A; Sobel'man, Igor I; Sorokin, Vadim N; Prokof'ichev, Yu V; Skoi, V R

    2000-01-31

    A large volume (30 cm{sup 3}) of dense (up to 10{sup 15} cm{sup -3}) Rb vapour was pumped optically by a high-power laser diode array. The conditions for the propagation of high-power broad-band optical pump radiation through an optically dense medium were examined. A spectroscopic method was developed for determination of the polarisation of Rb. The dependence of the polarisation of Rb on its vapour pressure was investigated at buffer gas pressures of 1, 8, and 13 bar. Under optimal conditions a 15-W diode laser made it possible to polarise at least 10{sup 18} of {sup 3}He atoms per second during collisions between Rb and {sup 3}He atoms, sufficient for the creation of an efficient neutron polariser. (laser applications and other topics in quantum electronics)

  2. Calculation of the characteristics of radiative multiphoton absorption and emission lines when an atom interacts with pulsed laser radiation

    NASA Astrophysics Data System (ADS)

    Glushkov, A. V.; Loboda, A. V.

    2007-03-01

    We have used the quantum electrodynamic theory of moments and the S-matrix formalism of Gell-Mann and Low to carry out numerical modeling of the characteristics (shift, width) of radiative multiphoton absorption lines for an atom in the field of a multimodal laser pulse with gaussian and soliton-like shapes. We have studied the effect of multimode character on the characteristics of multiphoton resonances, using as an example the 6S-6F transition in the cesium atom at the wavelength 1059 nm.

  3. Single and double multiphoton ionization of Li and Be atoms by strong laser fields

    NASA Astrophysics Data System (ADS)

    Telnov, Dmitry; Heslar, John; Chu, Shih-I.

    2011-05-01

    The time-dependent density functional theory with self-interaction correction and proper asymptotic long-range potential is extended for nonperturbative treatment of multiphoton single and double ionization of Li and Be atoms by strong 800 nm laser fields. We make use of the time-dependent Krieger-Li-Iafrate (TDKLI) exchange-correlation potential with the integer discontinuity which improves the description of the double ionization process. However, we have found that the discontinuity of the TDKLI potential is not sufficient to reproduce the characteristic feature of double ionization. This may happen because the discontinuity of the TDKLI potential is related to the spin particle numbers only and not to the total particle number. Introducing a discontinuity with respect to the total particle number to the exchange-correlation potential, we were able to obtain the knee structure in the intensity dependence of the double ionization probability of Be. This work was partially supported by DOE and NSF and by NSC-Taiwan.

  4. On the Strong-Field Approximation Describing Atoms and Molecules in Intense Laser Fields

    NASA Astrophysics Data System (ADS)

    Saenz, Alejandro; Vanne, Yulian

    2008-05-01

    A very popular theory to describe atomic (and recently also molecular) behavior in intense laser fields is the strong-field approximation (SFA), also known as Keldysh-Faisal-Reiss theory. It can be seen as the first-order term of an in principle exact time-dependent S-matrix theory. We have recently investigated some aspects of this theory in more detail. This includes the correctness of a recently proposed ``exact'' Keldysh theory based on the residue theorem instead of the saddle-point method. Furthermore, we have derived an analytical expression of the velocity-gauge SFA in the long-wavelength limit including the full Coulomb interaction. This revealed a break-down of the theory, but also allowed for a derivation of a new Coulomb correction factor and of a simplified quasi-static SFA (QSFA) that is of special interest for experimental studies in which the wavelength is scanned over large ranges. Finally, we will comment on a recently proposed SFA formulation in a ``gauge-invariant gauge.''

  5. [Atomic Vapor Laser Isotope Separation (AVLIS) program]. Final report, [January--July 1992

    SciTech Connect

    Not Available

    1992-12-04

    This report summarizes work performed for the Atomic Vapor Laser Isotope Separation (AVLIS) program from January through July, 1992. Each of the tasks assigned during this period is described, and results are presented. Section I details work on sensitivity matrices for the UDS relay telescope. These matrices show which combination of mirror motions may be performed in order to effect certain changes in beam parameters. In Section II, an analysis is given of transmission through a clipping aperture on the launch telescope deformable mirror. Observed large transmission losses could not be simulated in the analysis. An EXCEL spreadsheet program designed for in situ analysis of UDS optical systems is described in Section III. This spreadsheet permits analysis of changes in beam first-order characteristics due to changes in any optical system parameter, simple optimization to predict mirror motions needed to effect a combination of changes in beam parameters, and plotting of a variety of first-order data. Optical systems may be assembled directly from OSSD data. A CODE V nonsequential model of the UDS optical system is described in Section IV. This uses OSSD data to build the UDS model; mirror coordinates may thus be verified. Section V summarizes observations of relay telescope performance. Possible procedures which allow more accurate assessment of relay telescope performance are given.

  6. Large numbers of cold positronium atoms created in laser-selected Rydberg states using resonant charge exchange

    NASA Astrophysics Data System (ADS)

    McConnell, R.; Gabrielse, G.; Kolthammer, W. S.; Richerme, P.; Müllers, A.; Walz, J.; Grzonka, D.; Zielinski, M.; Fitzakerley, D.; George, M. C.; Hessels, E. A.; Storry, C. H.; Weel, M.; ATRAP Collaboration

    2016-03-01

    Lasers are used to control the production of highly excited positronium atoms (Ps*). The laser light excites Cs atoms to Rydberg states that have a large cross section for resonant charge-exchange collisions with cold trapped positrons. For each trial with 30 million trapped positrons, more than 700 000 of the created Ps* have trajectories near the axis of the apparatus, and are detected using Stark ionization. This number of Ps* is 500 times higher than realized in an earlier proof-of-principle demonstration (2004 Phys. Lett. B 597 257). A second charge exchange of these near-axis Ps* with trapped antiprotons could be used to produce cold antihydrogen, and this antihydrogen production is expected to be increased by a similar factor.

  7. REVIEWS OF TOPICAL PROBLEMS: Tunnel and multiphoton ionization of atoms and ions in a strong laser field (Keldysh theory)

    NASA Astrophysics Data System (ADS)

    Popov, Vladimir S.

    2004-09-01

    The theoretical description of the nonlinear photoionization of atoms and ions exposed to high-intensity laser radiation is underlain by the Keldysh theory proposed in 1964. The paper reviews this theory and its further development. The discussion is concerned with the energy and angular photoelectron distributions for the cases of linearly, circularly, and elliptically polarized laser radiation, with the ionization rate of atomic states exposed to a monochromatic electromagnetic wave and to ultrashort laser pulses of various shape, and with momentum and angular photoelectron spectra in these cases. The limiting cases of tunnel (? ll 1) and multiphoton (? gg 1) ionization are discussed, where c is the adiabaticity parameter, or the Keldysh parameter. The probability of above-barrier ionization is calculated for hydrogen atoms in a low-frequency laser field. The effect of a strong magnetic field on the ionization probability is discussed. The process of Lorentz ionization occurring in the motion of atoms and ions in a constant magnetic field is considered. The properties of an exactly solvable modelthe ionization of an s-level bound by zero-range forces in the field of a circularly polarized electromagnetic waveare described. In connection with this example, the Zel'dovich regularization method in the theory of quasistationary states is discussed. Results of the Keldysh theory are compared with experiment. A brief discussion is made of the relativistic ionization theory applicable when the binding energy of the atomic level is comparable with the electron rest mass (multiply charged ions) and the sub-barrier electron motion can no longer be considered to be nonrelativistic. A similar process of electron-positron pair production from a vacuum by the field of high-power optical or X-ray lasers (the Schwinger effect) is considered. The calculations invoke the method of imaginary time, which provides a convenient and physically clear way of calculating the probability of particle tunneling through time-varying barriers. Discussed in the Appendices are the properties of the asymptotic coefficients of the atomic wave function, the expansions for the Keldysh function, and the so-called 'ADK theory'.

  8. Isothermal vapour flow in extremely dry soils

    NASA Astrophysics Data System (ADS)

    Todman, L. C.; Ireson, A. M.; Butler, A. P.; Templeton, M. R.

    2012-04-01

    In dry soils hydraulic connectivity within the liquid water phase decreases and vapour flow becomes a significant transport mechanism for water. The temperature or solute concentration of the liquid phase affects the vapour pressure of the surrounding air, thus temperature or solute gradients can drive vapour flows. However, in extremely dry soils where water is retained by adsorptive forces rather than capillarity, vapour flows can also occur. In such soils tiny changes in water content significantly affect the equilibrium vapour pressure in the soil, and hence small differences in water content can initiate vapour pressure gradients. In many field conditions this effect may be negligible compared to vapour flows driven by other factors. However, flows of this type are particularly significant in a new type of subsurface irrigation system which uses pervaporation, via a polymer tubing, as the mechanism for water supply. In this system, water enters the soil in vapour phase. Experiments were performed in laboratory conditions using marine sand that had previously been oven dried and cooled. This dry sand was used to represent the desert conditions in which this irrigation system is intended for use. Experimental results show that isothermal vapour flows can significantly affect the performance of such irrigation systems due to the rapid transport of water through the soil via the vapour phase. When the irrigation pipe was buried at a depth of 10cm a vapour flow from the soil surface was observed in less than 2 hours. These flows therefore affect the loss of mass into the atmosphere and thus must be considered when evaluating the availability of water for the irrigated crop. The experiments also provide a rare opportunity to observe isothermal vapour flows initiating from a subsurface source. Such experiments allow the significance of these flows to be quantified and potentially applied to other areas of arid zone hydrology.

  9. Ab Initio Methods for Few- and Many-Electron Atomic Systems in Intense Short-Pulse Laser Light

    NASA Astrophysics Data System (ADS)

    Lysaght, M. A.; Moore, L. R.; Nikolopoulos, L. A. A.; Parker, J. S.; van der Hart, H. W.; Taylor, K. T.

    We describe how we have developed an ab initio method for solving the time-dependent Schrdinger equation for multielectron atomic systems exposed to intense short-pulse laser light. Our starting point for this development is to take over the algorithms and numerical methods employed in the HELIUM code we formerly developed and which has proved highly successful at describing few-electron atoms and atomic ions in strong laser fields. We describe how we have extended the underlying methods of HELIUM to describe multielectron systems exposed to intense short-pulse laser light. We achieve this extension through exploiting the powerful R-matrix division-of-space concept to bring together a numerical method (basis set) most appropriate to the multielectron finite inner region and a different numerical method (finite difference) most appropriate to the one-electron outer region. In order for the method to exploit massively parallel supercomputers efficiently, we time-propagate the wave function in both regions by employing schemes based on the Arnoldi method, long employed in HELIUM.

  10. High efficiency coherent optical memory with warm rubidium vapour.

    PubMed

    Hosseini, M; Sparkes, B M; Campbell, G; Lam, P K; Buchler, B C

    2011-01-01

    By harnessing aspects of quantum mechanics, communication and information processing could be radically transformed. Promising forms of quantum information technology include optical quantum cryptographic systems and computing using photons for quantum logic operations. As with current information processing systems, some form of memory will be required. Quantum repeaters, which are required for long distance quantum key distribution, require quantum optical memory as do deterministic logic gates for optical quantum computing. Here, we present results from a coherent optical memory based on warm rubidium vapour and show 87% efficient recall of light pulses, the highest efficiency measured to date for any coherent optical memory suitable for quantum information applications. We also show storage and recall of up to 20 pulses from our system. These results show that simple warm atomic vapour systems have clear potential as a platform for quantum memory. PMID:21285952

  11. High efficiency coherent optical memory with warm rubidium vapour

    PubMed Central

    Hosseini, M.; Sparkes, B.M.; Campbell, G.; Lam, P.K.; Buchler, B.C.

    2011-01-01

    By harnessing aspects of quantum mechanics, communication and information processing could be radically transformed. Promising forms of quantum information technology include optical quantum cryptographic systems and computing using photons for quantum logic operations. As with current information processing systems, some form of memory will be required. Quantum repeaters, which are required for long distance quantum key distribution, require quantum optical memory as do deterministic logic gates for optical quantum computing. Here, we present results from a coherent optical memory based on warm rubidium vapour and show 87% efficient recall of light pulses, the highest efficiency measured to date for any coherent optical memory suitable for quantum information applications. We also show storage and recall of up to 20 pulses from our system. These results show that simple warm atomic vapour systems have clear potential as a platform for quantum memory. PMID:21285952

  12. Quantum theory of two-photon correlated-spontaneous-emission lasers: Exact atom-field interaction Hamiltonian approach

    SciTech Connect

    Lu, N.; Zhu, S. )

    1989-11-15

    A quantum theory of two-photon correlated-spontaneous-emission lasers (CEL's) is developed, starting from the exact atom-field interaction Hamiltonian for cascade three-level atoms interacting with a single-mode radiation field. We consider the situation where the active atoms are prepared initially in a coherent superposition of three atomic levels and derive a master equation for the field-density operator by using a quantum theory for coherently pumped lasers. The master equation is transformed into a Fokker-Planck equation for the antinormal-ordering {ital Q} function. The drift coefficients of the Fokker-Planck equation enable us to study the steady-state operation of the two-photon CEL's analytically. We have studied both resonant two-photon CEL for which there is no threshold, and off-resonant two-photon CEL for which there exists a threshold. In both cases the initial atomic coherences provide phase locking, and squeezing in the phase quadrature of the field is found. The off-resonant two-photon CEL can build up from a vacuum when its linear gain is larger than the cavity loss (even without population inversion). Maximum squeezing is found in the no-population-inversion region with the laser intensities far below saturation in both cases, which are more than 90% for the resonant two-photon CEL and nearly 50% for the off-resonant one. Approximate steady-state {ital Q} functions are obtained for the resonant two-photon CEL and, in certain circumstances, for the off-resonant one.

  13. Measurement and simulations of hollow atom X-ray spectra of solid-density relativistic plasma created by high-contrast PW optical laser pulses

    NASA Astrophysics Data System (ADS)

    Pikuz, S. A.; Faenov, A. Ya.; Colgan, J.; Dance, R. J.; Abdallah, J.; Wagenaars, E.; Booth, N.; Culfa, O.; Evans, R. G.; Gray, R. J.; Kaempfer, T.; Lancaster, K. L.; McKenna, P.; Rossall, A. L.; Skobelev, I. Yu.; Schulze, K. S.; Uschmann, I.; Zhidkov, A. G.; Woolsey, N. C.

    2013-09-01

    K-shell spectra of solid Al excited by petawatt picosecond laser pulses have been investigated at the Vulcan PW facility. Laser pulses of ultrahigh contrast with an energy of 160 J on the target allow studies of interactions between the laser field and solid state matter at 1020 W/cm2. Intense X-ray emission of KK hollow atoms (atoms without n = 1 electrons) from thin aluminum foils is observed from optical laser plasma for the first time. Specifically for 1.5 ?m thin foil targets the hollow atom yield dominates the resonance line emission. It is suggested that the hollow atoms are predominantly excited by the impact of X-ray photons generated by radiation friction to fast electron currents in solid-density plasma due to Thomson scattering and bremsstrahlung in the transverse plasma fields. Numerical simulations of Al hollow atom spectra using the ATOMIC code confirm that the impact of keV photons dominates the atom ionization. Our estimates demonstrate that solid-density plasma generated by relativistic optical laser pulses provide the source of a polychromatic keV range X-ray field of 1018 W/cm2 intensity, and allows the study of excited matter in the radiation-dominated regime. High-resolution X-ray spectroscopy of hollow atom radiation is found to be a powerful tool to study the properties of high-energy density plasma created by intense X-ray radiation.

  14. Two-dimensional imaging of atomic and nanoparticle components in copper plasma plume produced by ultrafast laser ablation

    NASA Astrophysics Data System (ADS)

    Anoop, K. K.; Ni, Xiaochang; Bianco, M.; Paparo, D.; Wang, X.; Bruzzese, R.; Amoruso, S.

    2014-10-01

    We report on the spatial and temporal evolution of the plume generated during ultrafast laser ablation of a pure copper target with 800 nm, ≈50 fs, Ti: Sapphire laser pulses. Time-gated imaging was used to record 2-dimensional images of plume populations. The temporal evolution of neutral (Cu*), and ionic (Cu+) components of the plume are separately imaged by exploiting bandpass interference filters, while nanoparticles are investigated by collecting their characteristic broadband emission. The ionic component of the plume moves two to three times faster than the neutral component, with a velocity which is almost independent of laser fluence. Plume emission intensity variations at different fluences and delay times are studied for both atomic and nanoparticle components.

  15. Sub-20 isolated ultrashort attosecond pulse generation from He atoms by two-color mid-infrared laser fields

    NASA Astrophysics Data System (ADS)

    Li, Peng-Cheng; Chu, Shih-I.

    2014-05-01

    We propose an efficient method for the generation of ultra-broadband supercontinuum spectra and isolated ultrashort attosecond laser pulse from He atoms with two-color mid-infrared laser fields. High-order harmonic generation (HHG) is obtained by solving the time-dependent Schrdinger equation accurately by means of the time-dependent generalized pseudospectral method. We found that the optimizing two-color mid-infrared laser pulse allows the HHG cutoff to be significantly extended, leading to the production of ultra-broadband supercontinuum. As a result, an isolated 18 attosecond pulse can be generated directly by the superposition of the supercontinuum harmonics. To facilitate the exploration of the ultrashort attosecond generation mechanisms, we perform both the semiclassical simulation and the wavelet time-frequency transform. This work was partially supported by DOE and by MOE-NSC-NTU-Taiwan.

  16. Laser-induced atomic assembling of periodic layered nanostructures of silver nanoparticles in fluoro-polymer film matrix

    NASA Astrophysics Data System (ADS)

    Bagratashvili, V. N.; Rybaltovsky, A. O.; Minaev, N. V.; Timashev, P. S.; Firsov, V. V.; Yusupov, V. I.

    2010-05-01

    Fluorinated acrylic polymer (FAP) films have been impregnated with silver precursor (Ag(hfac)COD) by supercritical fluid technique and next irradiated with laser (? = 532 nm). Laser-chemically reduced Ag atoms have been assembled into massifs of Ag nanoparticles (3 - 8 nm) in FAP/Ag(hfac)COD films matrix in the form of periodic layered nanostructures (horizontal to film surface) with unexpectedly short period (90 - 180 nm). The wavelet analysis of TEM images reveals the existence of even shorter-period structures in such films. Photolysis with non-coherent light or pyrolysis of FAP/Ag(hfac)COD film results in formation of Ag nanoparticles massifs but free of any periodic nanoparticle assemblies. Our interpretation of the observed effect of laser formation of short-period nano-sized Ag nanoparticle assemblies is based on self-enhanced interference process in the course of modification of optical properties of film.

  17. Spectroscopy of the three-photon laser excitation of cold Rubidium Rydberg atoms in a magneto-optical trap

    SciTech Connect

    Entin, V. M.; Yakshina, E. A.; Tretyakov, D. B.; Beterov, I. I.; Ryabtsev, I. I.

    2013-05-15

    The spectra of the three-photon laser excitation 5S{sub 1/2} {yields} 5P{sub 3/2} {yields} 6S{sub 1/2}nP of cold Rb Rydberg atoms in an operating magneto-optical trap based on continuous single-frequency lasers at each stage are studied. These spectra contain two partly overlapping peaks of different amplitudes, which correspond to coherent three-photon excitation and incoherent three-step excitation due to the presence of two different ways of excitation through the dressed states of intermediate levels. A four-level theoretical model based on optical Bloch equations is developed to analyze these spectra. Good agreement between the experimental and calculated data is achieved by introducing additional decay of optical coherence induced by a finite laser line width and other broadening sources (stray electromagnetic fields, residual Doppler broadening, interatomic interactions) into the model.

  18. Sensitivity function analysis of gravitational wave detection with single-laser and large-momentum-transfer atomic sensors

    NASA Astrophysics Data System (ADS)

    Tang, Biao; Zhang, Bao-Cheng; Zhou, Lin; Wang, Jin; Zhan, Ming-Sheng

    2015-03-01

    Recently, a configuration using atomic interferometers (AIs) had been suggested for the detection of gravitational waves. A new AI with some additional laser pulses for implementing large momentum transfer was also put forward, in order to reduce the effect of shot noise and laser frequency noise. We use a sensitivity function to analyze all possible configurations of the new AI and to distinguish how many momenta are transferred in a specific configuration. By analyzing the new configuration, we further explore a detection scheme for gravitational waves, in particular, that ameliorates laser frequency noise. We find that the amelioration occurs in such a scheme, but novelly, in some cases, the frequency noise can be canceled completely by using a proper data processing method. Supported by the National Natural Science Foundation of China.

  19. Laser-assisted atom probe tomography of 18O-enriched oxide thin film for quantitative analysis of oxygen

    NASA Astrophysics Data System (ADS)

    Kinno, T.; Tomita, M.; Ohkubo, T.; Takeno, S.; Hono, K.

    2014-01-01

    18O-enriched SiO2 thin film with the 16O:18O ratio of around 1:1 has been analyzed by laser-assisted atom probe tomography (LA-APT) using 343 nm-wavelength ultraviolet laser or 532 nm-wavelength green laser in order to investigate the quantitativeness of the oxygen concentration determined by LA-APT. No clear evidence for detecting 16O18O++ signals was found in mass spectra, implying that the peaks at mass/charge of 16 and 18 are dominated by O+, not by O2++. The calculated elemental composition indicated significant loss of oxygen in LA-APT analysis of SiO2.

  20. High-resolution optical spectroscopy of Os-with a view to laser cooling of atomic anions

    NASA Astrophysics Data System (ADS)

    Kellerbauer, Alban; Fritzsche, Stephan

    2012-11-01

    Atomic anions are generally not amenable to optical spectroscopy because they are loosely bound systems and rarely have bound excited states. Until recently, there was only one known negative ion with a strong bound-bound electronic transition, the osmium anion Os-. The electric-dipole transition between the 4Fe9/2 ground and 6DoJ excited state of this ion provides unique insight into the structure of atomic anions. In addition, it may enable the preparation of ultracold ensembles of negative ions. Laser excitation of the electric-dipole transition in Os- ions could be used to laser-cool them to microkelvin temperatures. If demonstrated to be successful, the technique would allow the cooling of any species of negatively charged ions - from subatomic particles to molecular anions - to ultracold temperatures by sympathetic cooling. We have been investigating the bound-bound electric-dipole transition in Os- by high-resolution laser spectroscopy with a view to using it for the first laser cooling of negative ions. The principle of the method, its potential applications, as well as experimental results are presented.

  1. Generation of Attosecond X-ray Pulses Beyond the Atomic Unit of Time Using Laser Induced Microbunching in Electron Beams

    SciTech Connect

    Xiang, D.; Huang, Z.; Stupakov, G.; /SLAC

    2009-12-11

    Ever since the discovery of mode-locking, efforts have been devoted to reducing the duration of laser pulses since the ultrashort pulses are critical to explore the dynamics occurred on a ever-shorter timescale. In this paper we describe a scheme that's capable of generating intense attosecond x-ray pulses with duration beyond the atomic unit of time ({approx}24 attoseconds). The scheme combines the echo-enabled harmonic generation technique with the bunch compression which allows one to generate harmonic numbers of a few hundred in a microbunched beam through up-conversion of the frequency of a UV seed laser. A few-cycle intense IR laser is used to generate the required energy chirp in the beam for bunch compression and for selection of an attosecond x-ray pulse. Using a representative realistic set of parameters, we show that 1 nm x-ray pulse with peak power of a few hundred MW and duration as short as 20 attoseconds (FWHM) can be generated from a 200 nm UV seed laser. The proposed scheme may enable the study of electronic dynamics with a resolution beyond the atomic unit of time and may open a new regime of ultrafast sciences.

  2. Infrared (1-12 ?m) atomic and molecular emission signatures from energetic materials using laser-induced breakdown spectroscopy

    NASA Astrophysics Data System (ADS)

    Kumi Barimah, E.; Hmmerich, U.; Brown, E.; Yang, C. S.-C.; Trivedi, S. B.; Jin, F.; Wijewarnasuriya, P. S.; Samuels, A. C.; Snyder, A. P.

    2013-05-01

    Laser-induced breakdown spectroscopy (LIBS) is a powerful analytical technique to detect the elemental composition of solids, liquids, and gases in real time. For example, recent advances in UV-VIS LIBS have shown great promise for applications in chemical, biological, and explosive sensing. The extension of conventional UVVIS LIBS to the near-IR (NIR), mid-IR (MIR) and long wave infrared (LWIR) regions (~1-12 ?m) offers the potential to provide additional information due to IR atomic and molecular signatures. In this work, a Q-switched Nd: YAG laser operating at 1064 nm was employed as the excitation source and focused onto several chlorate and nitrate compounds including KClO3, NaClO3, KNO3, and NaNO3 to produce intense plasma at the target surface. IR LIBS studies on background air, KCl , and NaCl were also included for comparison. All potassium and sodium containing samples revealed narrow-band, atomic-like emissions assigned to transitions of neutral alkali-metal atoms in accordance with the NIST atomic spectra database. In addition, first evidence of broad-band molecular LIBS signatures from chlorate and nitrate compounds were observed at ~10 ?m and ~7.3 ?m, respectively. The observed molecular emissions showed strong correlation with FTIR absorption spectra of the investigated materials.

  3. Photothermal excitation and laser Doppler velocimetry of higher cantilever vibration modes for dynamic atomic force microscopy in liquid

    SciTech Connect

    Nishida, Shuhei; Kobayashi, Dai; Sakurada, Takeo; Nakazawa, Tomonori; Hoshi, Yasuo; Kawakatsu, Hideki

    2008-12-15

    The authors present an optically based method combining photothermal excitation and laser Doppler velocimetry of higher cantilever vibration modes for dynamic atomic force microscopy in liquid. The frequency spectrum of a silicon cantilever measured in water over frequencies ranging up to 10 MHz shows that the method allows us to excite and detect higher modes, from fundamental to fifth flexural, without enhancing spurious resonances. By reducing the tip oscillation amplitude using higher modes, the average tip-sample force gradient due to chemical bonds is effectively increased to achieve high-spatial-resolution imaging in liquid. The method's performance is demonstrated by atomic resolution imaging of a mica surface in water obtained using the second flexural mode with a small tip amplitude of 99 pm; individual atoms on the surface with small height differences of up to 60 pm are clearly resolved.

  4. Zeeman effects in the hyperfine structure of atomic iodine photodissociation laser emission.

    NASA Technical Reports Server (NTRS)

    Hwang, W. C.; Kasper, J. V. V.

    1972-01-01

    Observation of hyperfine structure in laser emission from CF3I and C2F5I photodissociation lasers. Constant magnetic fields affect the time behavior of the emission by changing the relative gains of the hyperfine transitions. Time-varying fields usually present in photodissociation lasers further complicate the emission.

  5. Atom probe tomography characterisation of a laser diode structure grown by molecular beam epitaxy

    SciTech Connect

    Bennett, Samantha E.; Humphreys, Colin J.; Oliver, Rachel A.; Smeeton, Tim M.; Hooper, Stewart E.; Heffernan, Jonathan; Saxey, David W.; Smith, George D. W.

    2012-03-01

    Atom probe tomography (APT) has been used to achieve three-dimensional characterization of a III-nitride laser diode (LD) structure grown by molecular beam epitaxy (MBE). Four APT data sets have been obtained, with fields of view up to 400 nm in depth and 120 nm in diameter. These data sets contain material from the InGaN quantum well (QW) active region, as well as the surrounding p- and n-doped waveguide and cladding layers, enabling comprehensive study of the structure and composition of the LD structure. Two regions of the same sample, with different average indium contents (18% and 16%) in the QW region, were studied. The APT data are shown to provide easy access to the p-type dopant levels, and the composition of a thin AlGaN barrier layer. Next, the distribution of indium within the InGaN QW was analyzed, to assess any possible inhomogeneity of the distribution of indium (''indium clustering''). No evidence for a statistically significant deviation from a random distribution was found, indicating that these MBE-grown InGaN QWs do not require indium clusters for carrier localization. However, the APT data show steps in the QW interfaces, leading to well-width fluctuations, which may act to localize carriers. Additionally, the unexpected presence of a small amount (x = 0.005) of indium in a layer grown intentionally as GaN was revealed. Finally, the same statistical method applied to the QW was used to show that the indium distribution within a thick InGaN waveguide layer in the n-doped region did not show any deviation from randomness.

  6. ac Stark shift in double resonance and coherent population trapping in a wall-coated cell for compact Rb atomic clocks

    NASA Astrophysics Data System (ADS)

    Miletic, Danijela; Bandi, Thejesh; Affolderbach, Christoph; Mileti, Gaetano

    2012-05-01

    We present a comparative study of the light-shifts (ac Stark shift) in a Rb vapour cell using two possible schemes for Rb atomic clocks: double resonance (DR) and coherent population trapping (CPT). For both schemes, the same wall-coated cell in a compact atomic resonator was used. The light-shift resulting from a monochromatic (DR) or a non-monochromatic (CPT) optical excitation was measured as a function of the laser intensity and the laser frequency and compared with existing theoretical results.

  7. Atomic physics of relativistic high contrast laser-produced plasmas in experiments on Leopard laser facility at UNR

    NASA Astrophysics Data System (ADS)

    Safronova, A. S.; Kantsyrev, V. L.; Faenov, A. Y.; Safronova, U. I.; Wiewior, P.; Renard-Le Galloudec, N.; Esaulov, A. A.; Weller, M. E.; Stafford, A.; Wilcox, P.; Shrestha, I.; Ouart, N. D.; Shlyaptseva, V.; Osborne, G. C.; Chalyy, O.; Paudel, Y.

    2012-06-01

    The results of the recent experiments focused on study of x-ray radiation from multicharged plasmas irradiated by relativistic (I > 1019 W/cm2) sub-ps laser pulses on Leopard laser facility at NTF/UNR are presented. These shots were done under different experimental conditions related to laser pulse and contrast. In particular, the duration of the laser pulse was 350 fs or 0.8 ns and the contrast was varied from high (10-7) to moderate (10-5). The thin laser targets (from 4 to 750 μm) made of a broad range of materials (from Teflon to iron and molybden to tungsten and gold) were utilized. Using the x-ray diagnostics including the high-precision spectrometer with resolution R ˜ 3000 and a survey spectrometer, we have observed unique spectral features that are illustrated in this paper. Specifically, the observed L-shell spectra for Fe targets subject to high intensity lasers (˜1019 W/cm2) indicate electron beams, while at lower intensities (˜1016 W/cm2) or for Cu targets there is much less evidence for an electron beam. In addition, K-shell Mg features with dielectronic satellites from high-Rydberg states, and the new K-shell F features with dielectronic satellites including exotic transitions from hollow ions are highlighted.

  8. High-order optical harmonic generation as a process of single atom interaction with sub-relativistic single- and multicolor laser fields

    SciTech Connect

    Andreev, A. V.; Stremoukhov, S. Yu.; Shoutova, O. A.

    2012-07-30

    We present a non-perturbative theory of a single atom interaction with the multicolor laser field. The theory is based on the use of exact mathematical solutions of the boundary value problem for 'an atom in the external field', as a result the case of arbitrary orientation of atomic angular momentum and electromagnetic wave polarization vector can be described in the consistent mathematical form. We also present the results of numerical simulations on silver and argon atoms interaction with single-and two-color laser fields formed by fundamental frequency and second harmonic of Ti:Sapphire laser. The results of numerical calculations show that the efficiency of high-order harmonic generation (HHG) depends strongly on the laser field parameters (especially on the orientation of polarization vectors and chirp of the two-color laser field components). We have demonstrated the saturation of the cut-off frequency in the laser fields of near-atomic strength and investigated the impact of the field phase in the case of ultrashort laser pulses.

  9. The Saga of Light-Matter Interaction and Magneto-optical Effects Applications to Atomic Magnetometry, Laser-cooled Atoms, Atomic Clocks, Geomagnetism, and Plant Bio-magnetism

    NASA Astrophysics Data System (ADS)

    Corsini, Eric P.

    The quest to expand the limited sensorial domain, in particular to bridge the inability to gauge magnetic fields near and far, has driven the fabrication of remedial tools. The interaction of ferromagnetic material with a magnetic field had been the only available technique to gauge that field for several millennium. The advent of electricity and associated classical phenomena captured in the four Maxwell equations, were a step forward. In the early 1900s, the model of quantum mechanics provided a two-way leap forward. One came from the newly understood interaction of light and matter, and more specifically the three-way coupling of photons, atoms' angular momenta, and magnetic field, which are the foundations of atomic magnetometry. The other came from magnetically sensitive quantum effects in a fabricated energy-ladder form of matter cooled to a temperature below that of the energy steps; these quantum effects gave rise to the superconducting quantum interference device (SQUID). Research using atomic magnetometers and SQUIDs has resulted in thousands of publications, text books, and conferences. The current status in each field is well described in Refs. [48,49,38,42] and all references therein. In this work we develop and investigate techniques and applications pertaining to atomic magnetometry. [Full text: eric.corsini gmail.com].

  10. Large increase in the electron capture and excitation cross sections for Li+ colliding with atomic H under UV laser assistance

    NASA Astrophysics Data System (ADS)

    Domínguez-Gutiérrez, F. J.; Cabrera-Trujillo, R.

    2015-07-01

    Neutralization and ash products due to electron capture processes in plasmas reduce the efficiency of energy generation in fusion Tokamak reactors. Therefore, lithium ions have been used to improve the efficiency of energy generation where good control of the electron capture process is required. Here, we show that an intense (1.4× {{10}13} W cm-2), ultra-short (1 fs at full width half-maximum) Gaussian laser pulse in the UV region can enhance the electron capture process on L{{i}+}+H(1s) in the low collision keV energy region. We find a factor of 10 enhancement in electron capture cross-section at impact energies lower than 10 keV amu-1 for an 80 nm wavelength laser and a factor of 2 for the excitation process in the hydrogen atom as compared to the laser-free case. In contrast, for a 200 nm wavelength laser the increase of the electron capture cross-sections takes place around 1 keV amu-1 by a factor of 3 and no enhancement for the excitation process. Our results show that the UV assisted production of Li can be controlled, particularly for short UV wave-length for a specific collision energy range. We anticipate that our findings will facilitate UV laser control of the Li production in Tokamak reactors and encourage further experimental work in this system.

  11. A method of local measurement of the microwave field in a plasma based on resonant laser fluorescence of hydrogen atoms

    NASA Astrophysics Data System (ADS)

    Polushkin, I. N.; Riabikin, M. Iu.; Shagiev, Iu. M.; Iazenkov, V. V.

    1985-11-01

    The interaction of hydrogen atoms with a powerful microwave field and a resonant laser beam are investigated theoretically and experimentally. The frequency of the microwave radiation was 38.5 GHz and the spectral transition of H-alpha was used as the source of resonant laser radiation. The microwave field was produced by a 100 kW gyrotron and directed through a quasi-optical duct to a gas discharge tube filled with hydrogen. Laser pulses of 20 ns duration and 20 kW power were obtained under coherent pumping. The generation line width of the radiation was 0.008 nm. Measurements of the correlation between the fluorescence signal and the intensities of the laser beam and the microwaves confirmed the theoretical calculations. On the basis of the measurements of the laser beam intensity vs the fluorescence signal, it is shown that the strength of the oscillating plasma electric field can be determined with a high time-resolution (10 to the -8th s) and high-spatial resolution (0.01 cm).

  12. A sensitive and accurate atomic magnetometer based on free spin precession

    NASA Astrophysics Data System (ADS)

    Gruji?, Zoran D.; Koss, Peter A.; Bison, Georg; Weis, Antoine

    2015-05-01

    We present a laser-based atomic magnetometer that allows inferring the modulus of a magnetic field from the free Larmor precession of spin-oriented Cs vapour atoms. The detection of free spin precession (FSP) is not subject to systematic readout errors that occur in phase feedback-controlled magnetometers in which the spin precession is actively driven by an oscillating field or a modulation of light parameters, such as frequency, amplitude, or polarization. We demonstrate that an FSP-magnetometer can achieve a 200 fT/?Hz sensitivity (<100 fT/?Hz in the shotnoise limit) and an absolute accuracy at the same level.

  13. Lasers.

    ERIC Educational Resources Information Center

    Schewe, Phillip F.

    1981-01-01

    Examines the nature of laser light. Topics include: (1) production and characteristics of laser light; (2) nine types of lasers; (3) five laser techniques including holography; (4) laser spectroscopy; and (5) laser fusion and other applications. (SK)

  14. Elastic Electron Scattering by Laser-Excited (sup 138)Ba (...6s6p (sup 1)P(sub 1)) Atoms

    NASA Technical Reports Server (NTRS)

    Csanak, G.

    1997-01-01

    The result of a joint experimental and theoretical study concerning elastic electron scattering by laser-excited (sup 138)Ba (...6s6p (sup 1)P(sub 1)) atoms are presented. From these studies, we extracted differential scattering cross sections (DCS's) and collision parameters for elastic scattering by the coherently prepared (sup 1)P(sub 1) atoms.

  15. Acquired acid resistance of human enamel treated with laser (Er:YAG laser and Co2 laser) and acidulated phosphate fluoride treatment: An in vitro atomic emission spectrometry analysis

    PubMed Central

    Mathew, Anju; Reddy, N. Venugopal; Sugumaran, D. K.; Peter, Joby; Shameer, M.; Dauravu, Liju Marcely

    2013-01-01

    Background: Dental caries is essentially a process of diffusion and dissolution. If the aspect of dissolution can be curtailed some degree of prevention can be achieved. Aims: The present study was carried out to evaluate and compare the effect of Er:YAG laser and Co2 laser irradiation combined with acidulated phosphate fluoride treatment on in vitro acid resistance of human enamel. Design: An in vitro study was carried out on 30 human premolars to evaluate the enamel's acid resistance using an atomic emission spectrometry analysis. Materials and Methods: A total of 60 enamel specimens were prepared from 30 human premolars and were randomly assigned to 6 groups: (1) Untreated (control); (2) 1.23% acidulated phosphate fluoride (APF) gel application alone for 4 min; (3) Er:YAG laser treatment alone; (4) Co2 laser treatment alone; (5) Er:YAG laser + APF gel application; (6) Co2 laser + APF gel application. The specimens were then individually immersed in 5 ml of acetate buffer solution (0.1 mol/L, pH 4.5) and incubated at 37C for 24 h, and the acid resistance was evaluated by determining the calcium ion concentration using the atomic emission spectrometry. Statistical Analysis: An ANOVA model was constructed (P value of 0.05), followed by Tukey's test for multiple pair wise comparisons of mean values. Results: Significant differences were found between the control group and the test groups (P < 0.001). Conclusions: Combining acidulated phosphate fluoride with either Er:YAG or Co2 laser had a synergistic effect in decreasing the enamel demineralization more than either fluoride treatment or laser treatment alone. PMID:24015004

  16. Comparison of theory and experiment for a one-atom laser in a regime of strong coupling

    SciTech Connect

    Boozer, A.D.; Boca, A.; Buck, J.R.; McKeever, J.; Kimble, H.J.

    2004-08-01

    Our recent paper reports the experimental realization of a one-atom laser in a regime of strong coupling [J. McKeever, A. Boca, A. D. Boozer, J. R. Buck, and H. J. Kimble, Nature (London) 425, 268 (2003)]. Here we provide the supporting theoretical analysis relevant to the operating regime of our experiment. By way of a simplified four-state model, we investigate the passage from the domain of conventional laser theory into the regime of strong coupling for a single intracavity atom pumped by coherent external fields. The four-state model is also employed to exhibit the vacuum-Rabi splitting and to calculate the optical spectrum. We next extend this model to incorporate the relevant Zeeman hyperfine states as well as a simple description of the pumping processes in the presence of polarization gradients and atomic motion. This extended model is employed to make quantitative comparisons with our earlier measurements for the intracavity photon number versus pump strength and for the photon statistics as expressed by the intensity correlation function g{sup (2)}({tau})

  17. Photonic tunneling effect between two coupled single-atom laser cavities imbedded within a photonic-crystal platform

    SciTech Connect

    Guo Xiaoyong; Ren Zhongzhou

    2011-01-15

    In this paper we investigate the photonic tunneling effect between two coupled one-atom laser cavities. The physical system consists of two coupled photonic crystal microcavities and each cavity contains a coherently pumped two-level atom. The dynamics of the system can be described by the master equation in terms of the reduced density operator. It is shown that the photonic tunneling behavior depends on certain physical conditions of the system. In the absence of the pumping field and without dissipations, the coherent photon number imbalance between two cavities exhibits the alternating-current Josephson effect. However, when the pumping effect and losses of the system are taken into account, the mean photon number imbalance displays a damped oscillation. In addition, the influence of tunneling amplitude and photonic band-gap structure on the oscillations is also studied. The research gives a further insight into the correlated dynamics of two coupled one-atom laser systems and provides an idea for constructing novel photon tunnel devises.

  18. Physical properties of vapour grown indium monotelluride platelets

    NASA Astrophysics Data System (ADS)

    Kunjomana, A. G.; Chandrasekharan, K. A.; Teena, M.

    2015-02-01

    Indium monotelluride (InTe) crystals were grown from vapour phase under different temperature gradients by employing physical vapour deposition (PVD) method. The morphology of these crystals such as whiskers, needles, platelets etc., strongly depends on the temperature distribution in the horizontal dual zone furnace. InTe platelets were deposited by setting the temperature of the charge (TC) and growth (TS) zones at 1073 K and 773 K (ΔT=300 K), respectively, for different growth periods (24 h, 48 h, 72 h and 96 h). The surface growth features have been analyzed by scanning electron microscopes, which indicate layer growth mechanism for all the crystals. Various crystals grown under ΔT=200 K and 300 K (retaining TS invariant) were examined by X-ray diffraction and elemental analysis. InTe samples exhibited consistent lattice parameters, density and atomic percentage, establishing stoichiometry and chemical homogeneity. The results obtained for Seebeck coefficient, electrical conductivity, power factor, dislocation density and microhardness are found to be reproducible as well. The vapour deposited InTe platelets are mechanically stable and possess high value of TEP, which ensure their practical application in thermoelectric power generation.

  19. Chemical reactions of excited nitrogen atoms for short wavelength chemical lasers. Final technical report

    SciTech Connect

    Not Available

    1989-12-15

    Accomplishments of this program include the following: (1) Scalable, chemical generation of oxygen atoms by reaction of fluorine atoms and water vapor. (2) Production of nitrogen atom densities of 1 {times} 10{sup 1}5 cm{sup {minus}3} with 5% electrical efficiency by injecting trace amounts of fluorine into microwave discharged nitrogen. (3) Production of cyanide radicals by reaction of high densities of N atoms with cyanogen. (4) Production of carbon atoms by reaction of nitrogen atoms with cyanogen or with fluorine atoms and hydrogen cyanide. (5) Confirmation that the reaction of carbon atoms and carbonyl sulfide produces CS(a{sup 3} {Pi}{sub r}), as predicted by conservation of electron spin and orbital angular momenta and as proposed by others under another SWCL program. (6) Production of cyanide radicals by injection of cyanogen halides into active nitrogen and use as spectroscopic calibration source. (7) Demonstration that sodium atoms react with cyanogen chloride, bromide and iodide and with cyanuric trifluoride to produce cyanide radicals. (8) Demonstration of the potential utility of the fluorine atom plus ammonia reaction system in the production of NF(b{sup l}{Sigma}{sup +}) via N({sup 2}D) + F{sub 2}.

  20. Two-Photon Laser-Induced Fluorescence O and N Atoms for the Study of Heterogeneous Catalysis in a Diffusion Reactor

    NASA Technical Reports Server (NTRS)

    Pallix, Joan B.; Copeland, Richard A.; Arnold, James O. (Technical Monitor)

    1995-01-01

    Advanced laser-based diagnostics have been developed to examine catalytic effects and atom/surface interactions on thermal protection materials. This study establishes the feasibility of using laser-induced fluorescence for detection of O and N atom loss in a diffusion tube to measure surface catalytic activity. The experimental apparatus is versatile in that it allows fluorescence detection to be used for measuring species selective recombination coefficients as well as diffusion tube and microwave discharge diagnostics. Many of the potential sources of error in measuring atom recombination coefficients by this method have been identified and taken into account. These include scattered light, detector saturation, sample surface cleanliness, reactor design, gas pressure and composition, and selectivity of the laser probe. Recombination coefficients and their associated errors are reported for N and O atoms on a quartz surface at room temperature.