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Sample records for atomic vapour laser

  1. 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)

  2. 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)

  3. 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.

  4. 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)

  5. 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.

  6. 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)

  7. 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.

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

    NASA Astrophysics Data System (ADS)

    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.

    2012-02-01

    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 ~1 kW with the 'light-to-light' conversion efficiency of ~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.

  9. 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.

  10. 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)

  11. 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.

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

    NASA Astrophysics Data System (ADS)

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

    2013-06-01

    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.

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

    E-print Network

    Bristol, University of

    observation of the emission sites over a large area of polycrystalline diamond using tunneling atomic forceDirect observation of electron emission from the grain boundaries of chemical vapour deposition for polycrystalline low pressure chemical vapour deposition ZnO:B films J. Appl. Phys. 113, 123104 (2013); 10

  14. 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)

  15. 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.

  16. 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…

  17. Diode laser atomic absorption spectrometry

    NASA Astrophysics Data System (ADS)

    Zybin, A.; Koch, J.; Wizemann, H. D.; Franzke, J.; Niemax, K.

    2005-01-01

    The paper reviews the past 11 years of literature on the application of diode lasers in atomic absorption spectrometry with graphite furnaces (GF), plasmas and flames as atomizers. Experimental arrangements and techniques for powerful absorption measurements as well as the theoretical background are covered. The analytical possibilities of high-resolution spectroscopy, including Doppler-free techniques for isotope selective measurements and isotope dilution analysis are discussed and various applications of element-selective detection by diode laser atomic absorption in combination with separation techniques, such as liquid (LC) and gas chromatography (GC), and with laser ablation of solid samples, are presented.

  18. The Collective Atomic Recoil Laser

    SciTech Connect

    Courteille, Ph.W.; Cube, C. avon; Deh, B.; Kruse, D.; Ludewig, A.; Slama, S.; Zimmermann, C.

    2005-05-05

    An ensemble of periodically ordered atoms coherently scatters the light of an incident laser beam. The scattered and the incident light may interfere and give rise to a light intensity modulation and thus to optical dipole forces which, in turn, emphasize the atomic ordering. This positive feedback is at the origin of the collective atomic recoil laser (CARL). We demonstrate this dynamics using ultracold atoms confined by dipole forces in a unidirectionally pumped far red-detuned high-finesse optical ring cavity. Under the influence of an additional dissipative force exerted by an optical molasses the atoms, starting from an unordered distribution, spontaneously form a density grating moving at constant velocity. Additionally, steady state lasing is observed in the reverse direction if the pump laser power exceeds a certain threshold. We compare the dynamics of the atomic trajectories to the behavior of globally coupled oscillators, which exhibit phase transitions from incoherent to coherent states if the coupling strength exceeds a critical value.

  19. Nonlinear absorption of femtosecond laser pulses (800 nm) by atmospheric air and water vapour

    SciTech Connect

    Kiselev, A M; Ponomarev, Yu N; Stepanov, A N; Tikhomirov, A B; Tikhomirov, B A

    2011-11-30

    Quantitative data on the nonlinear absorption cross sections of femtosecond Ti : Sapphire laser pulses in air and water vapour have been obtained. A photoacoustic spectrometer calibrated based on the calculated value of linear absorption of laser pulses with a wavelength of 800 nm and a spectral width of 17.7 nm is used to find the nonlinear absorption cross sections of water vapour and air: {sigma}{sub 2}{sup w} = (2.6{+-}0.4) Multiplication-Sign 10{sup -55} cm{sup 4} s and {sigma}{sub 2}{sup a} = (8.7{+-}1.0) Multiplication-Sign 10{sup -56} cm{sup 4} s, respectively. Based on measuring the absorption of femtosecond Ti : Sapphire laser pulses with a photoacoustic detector calibrated with the known linear absorption of ruby laser radiation by water vapour in air, the air nonlinear absorption cross section is found to be (8.2{+-}0.9) Multiplication-Sign 10{sup -56} cm{sup 4} s.

  20. 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.

  1. 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.

  2. 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.

  3. 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.

  4. 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 ?m) ridges in short time to realize BH-QCL. For comparison, telecom laser ridges are normally only <5 ?m 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 ?m 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.

  5. DYNAMICS OF KICKED LASER COOLED RUBIDIUM ATOMS

    E-print Network

    Summy, Gil

    DYNAMICS OF KICKED LASER COOLED RUBIDIUM ATOMS By BRIAN P. TIMMONS Bachelor of Science Northeastern July, 2006 #12;DYNAMICS OF KICKED LASER COOLED RUBIDIUM ATOMS Thesis Approved: Thesis Advisor Dean(AOM) . . . . . . . . 37 3.3.5. Shutters . . . . . . . . . . . . . . . . . . . . . . 38 3.4. Laser Cooled Rubidium-87 Atoms

  6. Resonance enhanced multiphoton ionization probing of H atoms and CH3 radicals in a hot lament chemical vapour deposition reactor

    E-print Network

    Bristol, University of

    reactor used for diamond chemical vapour deposition (CVD). Parameters varied include the hydrocarbon (CH4 to reinforce the consensus view that H atom production during diamond CVD in a hot ®lament reactor arises as a result of dissociative adsorption on the hot ®lament surface, whereas CH3 radical formation is dominated

  7. EFFECT OF LASER LIGHT ON MATTER. LASER PLASMAS: Evaporation-capillary instability in a deep vapour-gas cavity

    NASA Astrophysics Data System (ADS)

    Mirzoev, F. Kh

    1994-02-01

    A theoretical investigation is made of an instability of a molten metal surface on the walls of a deep vapour—gas cavity or crater when this surface absorbs a uniform flux of the energy of laser radiation. The instability is due to the growth of perturbations on the free surface of the melt. This growth is maintained by an associated space—time modulation of the evaporation pressure. The dispersion equation for weak hydrodynamic perturbations is derived and investigated. This equation allows for the dependence of the instability increment on the laser radiation and phase transition parameters, and also on the material constants of the medium. Quantitative estimates are obtained of the conditions for the realisation of the investigated instability mechanism.

  8. Atomic physics: An almost lightless laser

    E-print Network

    Vuletic, Vladan

    Lasers are often described in terms of a light field circulating in an optical resonator system. Now a laser has been demonstrated in which the field resides primarily in the atomic medium that is used to generate the light.

  9. 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.

  10. 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 Moján-Ancón de iturre, Santa Cruz de Mara-Punta de Palmas, Maracaibo-Punta de Leiva and San Francisco-La Rita). Specimens of Cynosción 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

  11. 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.

  12. 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 {{? }}.

  13. 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.

  14. 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)

  15. 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.

  16. Interferometric laser cooling of atomic rubidium

    E-print Network

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

    2014-01-01

    We report the 1-D cooling of atoms using a velocity-dependent optical force based upon Ramsey matter-wave interferometry. The interferometer is realised with stimulated Raman transitions between ground hyperfine states, and after 12 cycles of the cooling sequence, we observe a reduction in the temperature of a freely moving cloud of magneto-optically cooled $^{85}$Rb atoms from 20 $\\mu$K to 4 $\\mu$K, accompanied in this first demonstration by an acceleration of the centre of mass of the atom cloud. This pulse-based laser cooling technique could in principle be extended to molecules and atoms that lack a closed radiative transition.

  17. 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

  18. Quantum motion of laser trapped atoms

    SciTech Connect

    Jessen, P.S.

    1993-05-01

    In two recent experiments Verkerk et al. and our group have observed quantization of the center-of-mass motion of laser cooled atoms in sub-wavelength sized potential wells formed by the light field of a 1-dimensional optical molasses. Our 1-dimensional optical molasses consists of a pair of counterpropagating laser beams of orthogonal, linear polarization, creating a series of potential wells separated by {lambda}/4. Polarization gradient laser cooling reduces the thermal energy of the atoms until they are trapped in well resolved vibrational levels near the bottom of the wells. Transitions between these vibrational levels are seen in a high resolution spectrum of fluorescence, where they give rise to a Rayleigh peak centered at the laser frequency, and well resolved Raman sidebands shifted by a frequency {plus_minus}{omega}, typically on the order of 100 kHz. We find quantitative agreement between the measured level separation h{omega} and the results of a calculation of the bandstructure in the periodic optical potential. Based on the observed ratio of the strength of the blue to the red sideband we determine the temperature of the atoms, and find agreement with theoretical predictions. Based on the level spacing and temperature we find the atoms to be localized to {approx}/15, with up to 50-60% of the population of the trapped atoms in the vibrational ground state. We observe intriguing differences between fluorescence radiated by localized atoms, and the fluorescence radiated by non-localized atoms in a 1-dimensional optical molasses composed of a pair of counterpropagating laser beams of opposite circular polarization. The prospect of observing quantum motion and spatial order in 2 and 3 dimensions, and the consequences for the spectrum of fluorescence, will be discussed.

  19. 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.

  20. 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.

  1. 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.

  2. Entangling many atomic ensembles through laser manipulation

    E-print Network

    L. -M. Duan

    2002-04-24

    We propose an experimentally feasible scheme to generate Greenberger-Horne-Zeilinger (GHZ) type of maximal entanglement between many atomic ensembles based on laser manipulation and single-photon detection. The scheme, with inherent fault tolerance to the dominant noise and efficient scaling of the efficiency with the number of ensembles, allows to maximally entangle many atomic ensemble within the reach of current technology. Such a maximum entanglement of many ensembles has wide applications in demonstration of quantum nonlocality, high-precision spectroscopy, and quantum information processing.

  3. Resonance enhanced multiphoton ionisation probing of H atoms in a hot lament chemical vapour deposition reactor

    E-print Network

    Bristol, University of

    (CVD) of diamond. Macroscopic study and intuition have already gone far to make the growth of diamond-PACVD) or in the arc jet of a plasma torch. The resulting H atoms begin a series of abstraction reactions in the gas

  4. 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)

  5. 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.

  6. Stimulated IR emission in an optically pumped cesium vapour

    SciTech Connect

    Sitnikov, M G; Znamenskiy, Nikolay V; Manykin, Eduard A; Petrenko, Evgenii A; Grigoryan, Grigorii G

    2000-03-31

    It is demonstrated that the optical pumping of a Cs vapour with light pulses of a dye laser tunable within the range of 15390-17920 cm{sup -1} gives rise to high-power stimulated IR emission on several atomic transitions. Analysis of threshold, energy, and spectral characteristics of this emission allowed the mechanism underlying this effect to be explained. (active media. lasers)

  7. 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 µK 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.

  8. A new method for preconcentration and determination of mercury in fish, shellfish and saliva by cold vapour atomic absorption spectrometry.

    PubMed

    Lemos, Valfredo Azevedo; dos Santos, Liz Oliveira

    2014-04-15

    The development of a method using solid phase extraction for preconcentration and determination of mercury by cold vapour atomic absorption spectrometry is described. Hg (II) ions are sorbed on a minicolumn packed with Amberlite XAD-4 sorbent functionalised with 2-(2'-benzothiazolylazo)-p-cresol (BTAC). Then, a reducing solution was used for desorption and the transport of the analyte for subsequent detection. The assay presented a limit of detection of 0.011 ?g L?¹ (0.011 ?g g?¹, for solid samples), a limit of quantification of 0.038 ?g L?¹ (0.038 ?g g?¹, for solid samples), a precision of 0.50% (1.000 ?g L?¹ Hg solution) and an enrichment factor of 46. The proposed method was applied to the determination of mercury in human saliva (0.055-0.200 ?g L?¹). The following seafood collected in Todos os Santos Bay, Brazil was also analysed: bass (0.169-0.195 ?g g?¹), mullet (0.043-0.361 ?g g?¹), shrimp (0.075-0.374 ?g g?¹) and mussel (0.206-0.397 ?g g?¹). PMID:24295696

  9. Simultaneously determination of methyl and inorganic mercury in fish species by cold vapour generation atomic absorption spectrometry.

    PubMed

    Shah, A Q; Kazi, T G; Baig, J A; Afridi, H I; Arain, M B

    2012-10-15

    A simple and rapid non-chromatographic method was developed to determine methylmercury (MeHg) and inorganic mercury (iHg) levels in muscles tissues of 10 freshwater fish species. The MeHg and iHg were determined by cold vapour atomic absorption spectrometry after alkaline wet digestion of samples. The digested samples were reduced sequentially with stannous chloride and sodium tetrahydroborate for iHg and MeHg, respectively. Parameters such as carrier gas flow rate (argon), volume of oxidizing and potassium persulphate solutions were investigated in detail. The accuracy of the technique was evaluated by using certified reference material (DORM-2) and spiking the both Hg species in muscles tissue of a fish. The limits of detection were 0.117 and 0.133 ?g kg(-1) for MeHg and iHg, respectively. The concentrations of MeHg and iHg in muscles tissues of ten fish species were found in the range of (28.4-56.3) and (3.01-8.11) ?g kg(-1), respectively. PMID:23442694

  10. Laser collimation of Cr atoms with 3-D simulation analysis.

    PubMed

    Xiong, Xianming; Li, Yanqun; Zhang, Wentao

    2012-09-01

    Based on two-level atomic theory and Doppler Effect, the laser collimation of Cr atoms with 3-D simulation analysis has been studied in this paper. By analyzing the 3-D force on chromium atom, a theoretical 3-D model is built and the accurate 3-D trajectory of chromium atoms in laser cooling field has been achieved. The final 3-D distribution of atoms with different parameters has also been described. PMID:23035430

  11. 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.

  12. A model for an atom laser XII INTERNATIONAL CONFERENCE

    E-print Network

    Dalibard, Jean

    A model for an atom laser XII INTERNATIONAL CONFERENCE Island of Capri, Italy June 11-16,1995 *-:A, 24 rue Lhomond, 75005 Paris, France ABSTRACT We present a model for an "atom laser", and we show that fractionofthe atoms in a given mode of the surroundingatomic cavity. We point out the similarities between

  13. Coherent laser spectroscopy of rubidium atoms , M.M. Hossaina

    E-print Network

    Coherent laser spectroscopy of rubidium atoms S. Mitraa , M.M. Hossaina , B. Raya , P.N. Ghosh of Electronics, BAS, 1784 Sofia, Bulgaria ABSTRACT Laser spectroscopy experiments are reported on rubidium atoms pumping, rubidium, - and V-type systems. 1. INTRODUCTION Atomic rubidium has played a pivotal role

  14. 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.)

  15. 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 (CC?), detection capability (CC?), 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 CC? and CC? 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

  16. Collinear laser spectroscopy of atomic cadmium

    E-print Network

    Frömmgen, Nadja; Bissell, Mark L; Biero?, Jacek; Blaum, Klaus; Cheal, Bradley; Flanagan, Kieran; Fritzsche, Stephan; Geppert, Christopher; Hammen, Michael; Kowalska, Magdalena; Kreim, Kim; Krieger, Andreas; Neugart, Rainer; Neyens, Gerda; Rajabali, Mustafa M; Nörtershäuser, Wilfried; Papuga, Jasna; Yordanov, Deyan T

    2015-01-01

    Hyperfine structure $A$ and $B$ factors of the atomic $5s\\,5p\\,\\; ^3\\rm{P}_2 \\rightarrow 5s\\,6s\\,\\; ^3\\rm{S}_1$ transition are determined from collinear laser spectroscopy data of $^{107-123}$Cd and $^{111m-123m}$Cd. Nuclear magnetic moments and electric quadrupole moments are extracted using reference dipole moments and calculated electric field gradients, respectively. The hyperfine structure anomaly for isotopes with $s_{1/2}$ and $d_{5/2}$ nuclear ground states and isomeric $h_{11/2}$ states is evaluated and a linear relationship is observed for all nuclear states except $s_{1/2}$. This corresponds to the Moskowitz-Lombardi rule that was established in the mercury region of the nuclear chart but in the case of cadmium the slope is distinctively smaller than for mercury. In total four atomic and ionic levels were analyzed and all of them exhibit a similar behaviour. The electric field gradient for the atomic $5s\\,5p\\,\\; ^3\\mathrm{P}_2$ level is derived from multi-configuration Dirac-Hartree-Fock calculatio...

  17. Collinear laser spectroscopy of atomic cadmium

    E-print Network

    Nadja Frömmgen; Dimiter L. Balabanski; Mark L. Bissell; Jacek Biero?; Klaus Blaum; Bradley Cheal; Kieran Flanagan; Stephan Fritzsche; Christopher Geppert; Michael Hammen; Magdalena Kowalska; Kim Kreim; Andreas Krieger; Rainer Neugart; Gerda Neyens; Mustafa M. Rajabali; Wilfried Nörtershäuser; Jasna Papuga; Deyan T. Yordanov

    2015-07-14

    Hyperfine structure $A$ and $B$ factors of the atomic $5s\\,5p\\,\\; ^3\\rm{P}_2 \\rightarrow 5s\\,6s\\,\\; ^3\\rm{S}_1$ transition are determined from collinear laser spectroscopy data of $^{107-123}$Cd and $^{111m-123m}$Cd. Nuclear magnetic moments and electric quadrupole moments are extracted using reference dipole moments and calculated electric field gradients, respectively. The hyperfine structure anomaly for isotopes with $s_{1/2}$ and $d_{5/2}$ nuclear ground states and isomeric $h_{11/2}$ states is evaluated and a linear relationship is observed for all nuclear states except $s_{1/2}$. This corresponds to the Moskowitz-Lombardi rule that was established in the mercury region of the nuclear chart but in the case of cadmium the slope is distinctively smaller than for mercury. In total four atomic and ionic levels were analyzed and all of them exhibit a similar behaviour. The electric field gradient for the atomic $5s\\,5p\\,\\; ^3\\mathrm{P}_2$ level is derived from multi-configuration Dirac-Hartree-Fock calculations in order to evaluate the spectroscopic nuclear quadrupole moments. The results are consistent with those obtained in an ionic transition and based on a similar calculation.

  18. 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.

  19. Preparation, characterisation and optimisation of lithium battery anodes consisting of silicon synthesised using Laser assisted Chemical Vapour Pyrolysis

    NASA Astrophysics Data System (ADS)

    Veliscek, Ziga; Perse, Lidija Slemenik; Dominko, Robert; Kelder, Erik; Gaberscek, Miran

    2015-01-01

    Suitability of silicon prepared using Laser assisted Chemical Vapour Pyrolysis (LaCVP) as a potential anode material in lithium batteries is systematically investigated. Its compositional, morphological, physical-chemical and electrochemical properties are compared to a current benchmark commercial silicon. Important differences in particle size and particle composition are found which, as shown, affect critically the rheological properties of the corresponding electrode slurries. In order to overcome the rheological problems of prepared nanosilicon, we introduce and optimise a spraying method instead of using the usual casting technique for slurry application. Interestingly, the optimised electrodes show similar electrochemical performance, regardless of the particle size or composition of nanosilicon. This unexpected result is explained by the unusually high resistance of electrochemical wiring in silicon-based electrodes (about 60 Ohm per 1 mg cm-2 of active material loading). Despite that, the optimised material still shows a capacity up to 1200 mA h g-1 at a relatively high loading of 1.6 mg cm-2 and after 20 cycles. On the other hand, by decreasing the loading to below ca. 0.9 mg cm-2 the wiring problems are effectively overcome and capacities close to theoretical values can be obtained.

  20. 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 ?Kin a magneto-optical trapping. And a gravity resolution of 1.0 ×10-8 g within 200 s integration time is reached.

  1. Sympathetic Cooling of Molecules Using Laser-Cooled Atoms

    E-print Network

    California at Los Angles, University of

    Sympathetic Cooling of Molecules Using Laser-Cooled Atoms Maya Lewin-Berlin January 18, 2013 Abstract Sympathetic cooling of molecules using laser-cooled neutral atoms is a new technique being allows researchers to quickly determine the state of the cooling system. Measurements of the temperature

  2. Lamb Shift of Laser-Dressed Atomic States

    E-print Network

    U. D. Jentschura; J. Evers; M. Haas; C. H. Keitel

    2003-07-07

    We discuss radiative corrections to an atomic two-level system subject to an intense driving laser field. It is shown that the Lamb shift of the laser-dressed states, which are the natural state basis of the combined atom-laser system, cannot be explained in terms of the Lamb shift received by the atomic bare states which is usually observed in spectroscopic experiments. In the final part, we propose an experimental scheme to measure these corrections based on the incoherent resonance fluorescence spectrum of the driven atom.

  3. Generating Controllable Atom-Light Entanglement with a Raman Atom Laser System S. A. Haine,1

    E-print Network

    Queensland, University of

    Generating Controllable Atom-Light Entanglement with a Raman Atom Laser System S. A. Haine,1 M. K. Olsen,2 and J. J. Hope1 1 Australian Centre for Quantum-Atom Optics, The Australian National University, Canberra, 0200, Australia 2 Australian Centre for Quantum-Atom Optics, University of Queensland, Brisbane

  4. Double scattering of intense laser light by two atoms

    E-print Network

    Vyacheslav Shatokhin; Tobias Geiger; Thomas Wellens; Andreas Buchleitner

    2010-03-31

    This paper analyzes coherent backscattering of intense laser light by two randomly placed distant atoms. Starting from the general two-atom master equation, we analytically derive the elastic and inelastic background and interference components of the double scattering spectrum. By expressing the final results in terms of single-atom observables, the two-atom problem is shown to be equivalent to a description in terms of single atoms under bichromatic driving.

  5. Application of wavelength scanning for measuring water vapour concentration by distributed laser diode

    NASA Astrophysics Data System (ADS)

    Chang, Jun; Guangping, Lv; Zhou, Guoqing; Chen, Kun; Zhang, Yan; Wang, Zhongliang; Zhang, Shicong; Wang, Qiang; Song, Fujun

    2011-10-01

    A technique which takes advantage of distributed feedback laser diode (DFB-LD) wavelength scanning to measure water vapor concentration is presented. Concentration is gotten by peak absorption rate according to Beer-Lambert law and absorption coefficient of water vapor in HITRAN database. Theoretical work on the pressure affection to light intensity absorption rate has been done, a scheme is presented to cope with the affection of overlap of two adjacent lines, it takes advantage of the peak absorption difference between 1368.597nm and 1367.862 nm, and the difference value is used to calculate the water-vapor concentration.

  6. 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.

  7. 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.

  8. 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.

  9. Search for a permanent EDM using laser cooled radioactive atom

    NASA Astrophysics Data System (ADS)

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

    2014-03-01

    The search for the electric-dipole moment (EDM) of laser-cooled francium (Fr) atoms could lead to a measurement for the electron EDM. It is predicted that the electron EDM would be enhanced by approximately three orders of magnitude in heavy atoms such as Fr. Laser-cooling and trapping techniques are expected to suppress statistical and systematic errors in precision measurements. The magneto-optical trap was achieved using stable rubidium in a developing factory of laser-cooled radioactive atoms. In light of the results from the rubidium experiments, we found that an upgrade of each apparatus is preferred for Fr trapping.

  10. Laser-Enabled Auger Decay in Rare-Gas Atoms

    SciTech Connect

    Ranitovic, P.; Hogle, C. W.; Zhou, X.; Murnane, M. M.; Kapteyn, H. C.; Tong, X. M.; Liu, Y.; Toshima, N.

    2011-02-04

    In rare-gas atoms, Auger decay in which an inner-valence shell ns hole is filled is not energetically allowed. However, in the presence of a strong laser field, a new laser-enabled Auger decay channel can open up to increase the double-ionization yield. This process is efficient at high laser intensities, where an ns hole can be filled within a few femtoseconds of its creation. This novel laser-enabled Auger decay process is of fundamental importance for controlling electron dynamics in atoms, molecules, and materials.

  11. 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.

  12. Coherent inelastic backscattering of intense laser light by cold atoms

    E-print Network

    V. Shatokhin; C. A. Mueller; A. Buchleitner

    2005-02-04

    We present a nonperturbative treatment of coherent backscattering of intense laser light from cold atoms, and predict a nonvanishing backscattering signal even at very large intensities, due to the constructive (self-)interference of inelastically scattered photons.

  13. 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.

  14. 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) (3?) 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

  15. 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.

  16. 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.

  17. Method for laser spectroscopy of metastable pionic helium atoms

    NASA Astrophysics Data System (ADS)

    Hori, M.; Sótér, A.; Aghai-Khozani, H.; Barna, D.; Dax, A.; Hayano, R. S.; Murakami, Y.; Yamada, H.

    2015-08-01

    The PiHe collaboration is currently attempting to carry out laser spectroscopy of metastable pionic helium atoms using the high-intensity ? - beam of the ring cyclotron facility of the Paul Scherrer Institute. These atoms are heretofore hypothetical three-body Coulomb systems each composed of a helium nucleus, a ? - occupying a Rydberg state, and an electron occupying the 1s ground state. We briefly review the proposed method by which we intend to detect the laser spectroscopic signal. This complements our experiments on metastable antiprotonic helium atoms at CERN.

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

    NASA Astrophysics Data System (ADS)

    Ginzel, Christian; Briegel, Hans-Jürgen; 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.

  19. Laser Probing of Neutron-Rich Nuclei in Light Atoms

    E-print Network

    Z. -T. Lu; P. Mueller; G. W. F. Drake; W. Noertershaeuser; Steven C. Pieper; Z. -C. Yan

    2013-07-10

    The neutron-rich 6He and 8He isotopes exhibit an exotic nuclear structure that consists of a tightly bound 4He-like core with additional neutrons orbiting at a relatively large distance, forming a halo. Recent experimental efforts have succeeded in laser trapping and cooling these short-lived, rare helium atoms, and have measured the atomic isotope shifts along the 4He-6He-8He chain by performing laser spectroscopy on individual trapped atoms. Meanwhile, the few-electron atomic structure theory, including relativistic and QED corrections, has reached a comparable degree of accuracy in the calculation of the isotope shifts. In parallel efforts, also by measuring atomic isotope shifts, the nuclear charge radii of lithium and beryllium isotopes have been studied. The techniques employed were resonance ionization spectroscopy on neutral, thermal lithium atoms and collinear laser spectroscopy on beryllium ions. Combining advances in both atomic theory and laser spectroscopy, the charge radii of these light halo nuclei have now been determined for the first time independent of nuclear structure models. The results are compared with the values predicted by a number of nuclear structure calculations, and are used to guide our understanding of the nuclear forces in the extremely neutron-rich environment.

  20. 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.

  1. Cold Atoms and Stable Lasers: The Clocks of the Future Today

    E-print Network

    Van Stryland, Eric

    Cold Atoms and Stable Lasers: The Clocks of the Future Today Leo Hollberg National Institute laser and length metrology Richard Fox #12;Types of Clocks Ruler Clock Decay Stable Oscillator Atomic 158 Counter Generic Atomic Clock Atoms #12;Atomic Beam Clock Ramsey Method Cs Signal # of Atoms d

  2. Theory of laser-induced excitation transfer and atomic association

    NASA Astrophysics Data System (ADS)

    Saha, H. P.; Dahler, John S.; Jones, Dumont M.

    1984-09-01

    Formulas are derived for the differential and integral cross sections associated with laser-induced excitation transfer. The theory is patterned closely after our recent treatment of laser-induced chemi-ionization. It is found that cross sections specific to single-photon absorption are proportional to the square of the cosine of the angle between the laser polarization and the initial relative velocity of the two colliding atoms. The distortion by a laser of the cross section for an elastic scattering event also is treated. Finally, a cross-section formula is derived for a collision-induced two-photon absorption, mediated by a single intermediate electronic state.

  3. Stationary quantum statistics of a non-Markovian atom laser

    E-print Network

    A. S. Bradley; J. J. Hope; M. J. Collett

    2002-10-31

    We present a steady state analysis of a quantum-mechanical model of an atom laser. A single-mode atomic trap coupled to a continuum of external modes is driven by a saturable pumping mechanism. In the dilute flux regime, where atom-atom interactions are negligible in the output, we have been able to solve this model without making the Born-Markov approximation. The more exact treatment has a different effective damping rate and occupation of the lasing mode, as well as a shifted frequency and linewidth of the output. We examine gravitational damping numerically, finding linewidths and frequency shifts for a range of pumping rates. We treat mean field damping analytically, finding a memory function for the Thomas-Fermi regime. The occupation and linewidth are found to have a nonlinear scaling behavior which has implications for the stability of atom lasers.

  4. 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.

  5. WHEN ATOMS BEHAVE AS WAVES: BOSE-EINSTEIN CONDENSATION AND THE ATOM LASER

    E-print Network

    of Bose-Einstein condensation was predicted long ago, in a 1925 paper by Albert Einstein [1] usingWHEN ATOMS BEHAVE AS WAVES: BOSE-EINSTEIN CONDENSATION AND THE ATOM LASER Nobel Lecture, December 8, such as Bose-Einstein condensates first realized in 1995. Each of these achievements in cooling has been

  6. Nobel lecture: When atoms behave as waves: Bose-Einstein condensation and the atom laser*

    E-print Network

    by Albert Einstein (Einstein, 1925b) using a method introduced by Satyen- dra Nath Bose to derive the blackNobel lecture: When atoms behave as waves: Bose-Einstein condensation and the atom laser* Wolfgang, such as Bose-Einstein con- densates first realized in 1995. Each of these achieve- ments in cooling has been

  7. Laser cooling and trapping of atoms

    SciTech Connect

    Bjorkholm, J.E.; Chu, S.; Ashkin, A.; Cable, A.

    1987-09-25

    We recently demonstrated the first optical trapping of atoms. An important prelude to that work was our earlier demonstration of ''optical molasses,'' a technique for creating a long-lived collection of ultra-cold atoms. This paper presents a pedagogical discussion of those experiments and of the background material needed to understand them.

  8. Theory of a single-atom laser including light forces

    E-print Network

    Thomas Salzburger; Peter Domokos; Helmut Ritsch

    2005-04-12

    We study a single incoherently pumped atom moving within an optical high-Q resonator in the strong coupling regime. Using a semiclassical description for the atom and field dynamics, we derive a closed system of differential equations to describe this coupled atom-field dynamics. For sufficiently strong pumping the system starts lasing when the atom gets close to a field antinode, and the associated light forces provide for self-trapping of the atom. For a cavity mode blue detuned with respect to the atomic transition frequency this is combined with cavity induced motional cooling allowing for long term steady-state operation of such a laser. The analytical results for temperature and field statistics agree well with our earlier predictions based on Quantum Monte Carlo simulations. We find sub-Doppler temperatures that decrease with gain and coupling strength and can even go beyond the limit of passive cavity cooling. Besides demonstrating the importance of light forces in single-atom lasers, this result also gives strong evidence to enhance laser cooling through stimulated emission in resonators.

  9. Laser-assisted inelastic scattering of electrons by helium atoms

    NASA Astrophysics Data System (ADS)

    Agueny, H.; Makhoute, A.; Dubois, A.; Ajana, I.; Rahali, G.

    2015-07-01

    The differential cross section for electron-impact excitation of helium atoms in the presence of a linearly polarized laser field is calculated. The interaction of the laser field with both the projectile electron and the target atom is treated in a fully nonperturbative way, while the electron-atom interaction is treated within the first Born approximation. We are interested in studying two cases where the photon energy of the laser field is chosen to be far from resonance and when it matches with 2 1S ?2 1P and 3 1S ?3 1P transition frequencies. The agreement between perturbative and nonperturbative results is good, except close to the resonance where the perturbative cross sections diverge while the nonperturbative ones predict no maximum of the cross sections. Another interesting effect is the presence of an avoided crossing of the Floquet pseudoenergies at resonance.

  10. 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}.

  11. Search for electron EDM with laser cooled radioactive atom

    NASA Astrophysics Data System (ADS)

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

    2013-05-01

    The permanent electric dipole moment (EDM) of the elementary particle has the sensitivity to the CP violation in the theories beyond the standard model (SM). The search for the EDM constitutes the stringent test to discriminate between the SM and beyond it. We plan to perform the electron EDM search by using the laser cooled francium (Fr) atom which has the largest enhancement factor of the electron EDM in the alkali atoms. In this paper, the present status of the laser cooled Fr factory that is being constructed at Cyclotron and Radioisotope Center (CYRIC), Tohoku University are reported.

  12. Continuous beam of laser-cooled Yb atoms

    NASA Astrophysics Data System (ADS)

    Rathod, K. D.; Singh, Alok K.; Natarajan, Vasant

    2013-05-01

    We demonstrate the launching of laser-cooled Yb atoms in a continuous atomic beam. The continuous cold beam has significant advantages over the more-common pulsed fountain, which was also demonstrated by us recently. The cold beam is formed in the following steps: i) atoms from a thermal beam are first Zeeman-slowed to a small final velocity; ii) the slowed atoms are captured in a two-dimensional magneto-optic trap (2D-MOT); and iii) atoms are launched continuously in the vertical direction using two sets of moving-molasses beams, inclined at ±15° to the vertical. The cooling transition used is the strongly allowed {^1S}_0 \\rightarrow {^1P}_1 transition at 399 nm. We capture about 7 × 106 atoms in the 2D-MOT, and then launch them with a vertical velocity of 13 m/s at a longitudinal temperature of 125(6) mK.

  13. Laser-induced nonresonant nuclear excitation in muonic atoms

    E-print Network

    A. Shahbaz; C. Müller; T. J. Buervenich; C. H. Keitel

    2008-12-13

    Coherent nuclear excitation in strongly laser-driven muonic atoms is calculated. The nuclear transition is caused by the time-dependent Coulomb field of the oscillating charge density of the bound muon. A closed-form analytical expression for electric multipole transitions is derived and applied to various isotopes; the excitation probabilities are in general very small. We compare the process with other nuclear excitation mechanisms through coupling with atomic shells and discuss the prospects to observe it in experiment.

  14. 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.

  15. Sub-Doppler laser cooling of potassium atoms

    NASA Astrophysics Data System (ADS)

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

    2011-10-01

    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 ?K and 47±5 ?K in high-density samples of the two isotopes 39K and 41K, respectively. Our findings should find application to other atomic systems.

  16. 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.

  17. 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

  18. Interferometric Laser Cooling of Atomic Rubidium

    NASA Astrophysics Data System (ADS)

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

    2015-08-01

    We report the 1D cooling of 85Rb 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.

  19. Search for a permanent EDM with laser cooled radioactive atom

    NASA Astrophysics Data System (ADS)

    Sakemi, Yasuhiro

    2014-09-01

    To explore the mechanism for the generation of the matter-antimatter asymmetry in the universe, the study on fundamental symmetry violation using the trapped radioactive atoms with laser cooling techniques is being promoted. An Electric Dipole Moment (EDM) of the elementary particle is a good prove to observe the phenomena beyond the Standard Model. A finite value of EDM means the violation of the time reversal symmetry, and the CP violation under the CPT invariance. In paramagnetic atoms, an electron EDM results in an atomic EDM enhanced by the factor of the 3rd power of the charge of the nucleus due the relativistic effects. A heaviest alkali element francium (Fr), which is the radioactive atom, has the largest enhancement factor K ~ 895 in atomic system. Then, we are developing a high intensity laser cooled Fr factory at Cyclotron and Radioisotope Center (CYRIC), Tohoku University to search for the EDM of Fr with the accuracy of 10-29 e cm. To overcome the current accuracy limit of the EDM, it is necessary to realize the high intensity Fr source and to reduce the systematic error due to the motional magnetic field and inhomogeneous applied field. To reduce the dominant component of the systematic errors mentioned above, we will confine the Fr atoms in the small region with the Magneto-Optical Trap (MOT) and optical lattice using the laser cooling and trapping techniques. The construction of the experimental apparatus is making progress, and the new thermal ionizer already produces the Fr of ~ 10 6 ions/s with the primary beam intensity 200 nA. The extracted Fr ion beam is transported to the neutralizer, which is located 10 m downstream, and the produced neutral Fr atoms are introduced into the MOT to load the next trapping system such as the optical dipole force trap and optical lattice. The coherence time will be increased in the laser trapping system, and the present status of the experiment will be reported.

  20. 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.

  1. A new laser cooling method for lithium atom interferometry

    NASA Astrophysics Data System (ADS)

    Kim, Geena

    An atom interferometer offers means to measure physical constants and physical quantities with a high precision, with relatively low cost and convenience as a table-top experiment. A precision measurement of a gravitational acceleration can test fundamental physics concepts such as Einstein equivalence principle (EEP). We identified that the two lithium isotopes (7Li and 6Li) have an advantage for the test of EEP, according to the standard model extension (SME). We aim to build the world's first lithium atom interferometer and test the Einstein equivalence principle. We demonstrate a new laser cooling method suitable for a lithium atom interferometer. Although lithium is often used in ultra-cold atom experiments for its interesting physical properties and measurement feasibility, it is more difficult to laser cool lithium than other alkali atoms due to its unresolved hyperfine states, light mass (large recoil velocity) and high temperature from the oven. Typically, standard laser cooling techniques such as Zeeman slowers and magneto-optical traps are used to cool lithium atoms to about 1 mK, and the evaporative cooling method is used to cool lithium atoms to a few muK for Bose-Einstein condensate (BEC) experiments. However, for the atom interferometry purpose, the evaporative cooling method is not ideal for several reasons: First, its cooling efficiency is so low (0.01 % or less) that typically only 104-105 atoms are left after cooling when one begins with 10. 9 atoms. More atoms in anatom interferometer are needed to have a better signal to noise ratio. Second, an evaporative cooling is used to make a BEC, but we do not need a BEC to make an atom interferometer. In an atom interferometer, a high density of atoms as in a BEC should be avoided since it causes a phase shift due to atom interactions. Third, a setup for an evaporative cooling requires intricate RF generating coils or a high power laser. With a simple optical lattice and a moderate laser power (100 mW), we achieved a sub-Doppler cooling of lithium by a new laser cooling method despite the fact that lithium has un-resolved hyperfine structure. We identified that the Sisyphus cooling and the adiabatic cooling mechanisms cooperate and give both lower temperature and higher cooling efficiency than the result that can be achieved by each alone. We cooled 7Li atoms to ˜ 50 muK (about 8 times the recoil temperature) in a one dimensional lattice with cooling efficiency of 50%. In three dimensions the cooling temperature was limited to 90,muK due to instability of our 3D lattice, however the same principle applies and potentially a lower temperature can be achieved in 3D as well.

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

    PubMed

    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. PMID:26233359

  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. Heteronuclear collisions between laser-cooled metastable neon atoms

    E-print Network

    Jan Schütz; Thomas Feldker; Holger John; Gerhard Birkl

    2012-08-28

    We investigate heteronuclear collisions in isotope mixtures of laser-cooled metastable 3P2 neon. Experiments are performed with spin-polarized atoms in a magnetic trap for all two-isotope combinations of the stable neon isotopes 20Ne, 21Ne, and 22Ne. We determine the rate coefficients for heteronuclear ionizing collisions to beta_{21,20}=(3.9+/-2.7) x 10^{-11} cm^3/s, beta_{22,20}=(2.6+/-0.7) x 10^{-11} cm^3/s, and beta_{21,22}=(3.9+/-1.9) x 10^{-11} cm^3/s. We also study heteronuclear elastic collision processes and give upper bounds for heteronuclear thermal relaxation cross sections. This work significantly extends the limited available experimental data on heteronuclear ionizing collisions for laser-cooled atoms involving one or more rare gas atoms in a metastable state.

  5. Ion microscopy based on laser-cooled cesium atoms

    E-print Network

    Viteau, M; Kime, L; Rasser, B; Sudraud, P; Bruneau, Y; Khalili, G; Pillet, P; Comparat, D; Guerri, I; Fioretti, A; Ciampini, D; Allegrini, M; Fuso, F

    2016-01-01

    We demonstrate a prototype of a Focused Ion Beam machine based on the ionization of a laser-cooled cesium beam adapted for imaging and modifying different surfaces in the few-tens nanometer range. Efficient atomic ionization is obtained by laser promoting ground-state atoms into a target excited Rydberg state, then field-ionizing them in an electric field gradient. The method allows obtaining ion currents up to 130 pA. Comparison with the standard direct photo-ionization of the atomic beam shows, in our conditions, a 40-times larger ion yield. Preliminary imaging results at ion energies in the 1-5 keV range are obtained with a resolution around 40 nm, in the present version of the prototype. Our ion beam is expected to be extremely monochromatic, with an energy spread of the order of 1 eV, offering great prospects for lithography, imaging and surface analysis.

  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. Atomic-signal-based zero field finding technique for unshielded laser-pumped atomic magnetometer

    E-print Network

    Haifeng Dong; Hongbo Lin; Xinbin Tang

    2012-03-05

    We described a novel technique that can find the zero-field for unshielded laser-pumped atomic magnetometer using atomic signal itself. By comparing light density of pump beam after atomic vapor cell, it is decided which direction to move the compensation magnetic field and whether to increase or decrease the converging step length. The zero-field is found in less than 18s and the step length after converging is smaller than 10nT, 10nT and 40nT for x, y and z axes, respectively, limited by 50Hz noise in the lab environment.

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

    NASA Astrophysics Data System (ADS)

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

    2014-09-01

    A permanent electric dipole moment (EDM) of a particle or an atom is a suited observable to test the physics beyond the standard model. We plan to search for the electron EDM by using the laser cooled francium (Fr) atom, since the Fr atom has a large enhancement factor of the electron EDM and the laser cooling techniques can suppress both statistical and systematic errors. In the EDM experiment, a fluctuation of the magnetic field is a main source of the errors. In order to achieve the high precision magnetometry, a magnetometer based on the nonlinear magneto-optical rotation effect of the Rb atom is under development. A long coherence time of Rb atom is the key issue for the highly sensitive detection of the field fluctuations. The coherence time is limited due both to collisions with an inner surface of a cell contained the Rb atom and to residual field in a magnetic shield. We prepared the cell coated with an anti-relaxation material and measured the relaxation time. A degauss of the shield was performed to eliminate the residual field. We will report the present status of the magnetometer. A permanent electric dipole moment (EDM) of a particle or an atom is a suited observable to test the physics beyond the standard model. We plan to search for the electron EDM by using the laser cooled francium (Fr) atom, since the Fr atom has a large enhancement factor of the electron EDM and the laser cooling techniques can suppress both statistical and systematic errors. In the EDM experiment, a fluctuation of the magnetic field is a main source of the errors. In order to achieve the high precision magnetometry, a magnetometer based on the nonlinear magneto-optical rotation effect of the Rb atom is under development. A long coherence time of Rb atom is the key issue for the highly sensitive detection of the field fluctuations. The coherence time is limited due both to collisions with an inner surface of a cell contained the Rb atom and to residual field in a magnetic shield. We prepared the cell coated with an anti-relaxation material and measured the relaxation time. A degauss of the shield was performed to eliminate the residual field. We will report the present status of the magnetometer. Supported by Grants-in-Aid for Scientic Research (Nos. 21104005 and 26220705).

  9. 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.

  10. Laser cooling of a magnetically guided ultracold atom beam

    NASA Astrophysics Data System (ADS)

    Aghajani-Talesh, A.; Falkenau, M.; Volchkov, V. V.; Trafford, L. E.; Pfau, T.; Griesmaier, A.

    2010-06-01

    We report on the transverse laser cooling of a magnetically guided beam of ultracold chromium atoms. Radial compression by a tapering of the guide is employed to adiabatically heat the beam. Inside the tapered section, heat is extracted from the atom beam by a two-dimensional (2D) optical molasses perpendicular to it, resulting in a significant increase in atomic phase space density. A magnetic offset field is applied to prevent optical pumping to untrapped states. Our results demonstrate that, by a suitable choice of the magnetic offset field, the cooling beam intensity and detuning, atom losses and longitudinal heating can be avoided. Final temperatures below 65 ?K have been achieved, corresponding to an increase in phase space density in the guided beam by more than a factor of 30.

  11. Laser cooling of cesium atoms below 3 microkelvins

    SciTech Connect

    Salomon, C.; Dalibard, J.; Phillips, W.D. , Departement de Physique de l ENS, 24 rue Lhomond, F-75231 Paris Cedex 05 ); Clairon, A. ); Guellati, S. )

    1991-08-05

    We have measured the temperature of cesium atoms released from optical molasses. For a wide range of laser intensity and detuning from resonance, the temperature depends only on the intensity to detuning ratio. The lowest temperature achieved is 2.5{plus minus}0.6 {mu}K, which corresponds to an rms velocity of 12.5 mm/s or 3.6 times the single-photon recoil velocity. This is, to our knowledge, the coldest kinetic temperature ever measured for three dimensional (3D) cooling. We then discuss the possibility of using such a cold sample of atoms for realizing a high performance atomic clock in a fountain geometry. In particular, a method for launching the atoms upwards, while maintaining the very cold temperature, is demonstrated.

  12. 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.

  13. 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.

  14. 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.

  15. Scattering of two-level atoms by delta lasers: Exactly solvable models in atom optics

    E-print Network

    D. Seidel; J. G. Muga; G. C. Hegerfeldt

    2006-07-18

    We study the scattering of two-level atoms at narrow laser fields, modeled by a $\\delta$-shape intensity profile. The unique properties of these potentials allow us to give simple analytic solutions for one or two field zones. Several applications are studied: a single $\\delta$-laser may serve as a detector model for atom detection and arrival-time measurements, either by means of fluorescence or variations in occupation probabilities. We show that, in principle, this ideal detector can measure the particle density, the quantum mechanical flux, arrival time distributions or local kinetic energy densities. Moreover, two spatially separated $\\delta$-lasers are used to investigate quantized-motion effects on Ramsey interferometry.

  16. Differential atomic magnetometry based on a diverging laser beam

    SciTech Connect

    Hodby, E.; Donley, E. A.; Kitching, J.

    2007-07-02

    The authors demonstrate a novel atomic magnetometer that uses differential detection of the spatially diverging components of a light field to monitor the Larmor precession frequency of atoms in a thermal vapor. The design is implemented in compact form with a micromachined alkali vapor cell and a naturally divergent light field emitted by a vertical-cavity surface-emitting laser. Operating the magnetometer in differential mode cancels common-mode noise and improves the sensitivity by a factor of 26 over single-channel operation. They also suggest ways in which the current sensitivity of 28 pT/{radical}Hz may be improved further without sacrificing size or simplicity.

  17. 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.

  18. 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.

  19. 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.

  20. Comparison of the Er,Cr:YSGG laser with a chemical vapour deposition bur and conventional techniques for cavity preparation: a microleakage study.

    PubMed

    Yazici, A Rüya; Y?ld?r?m, Zeren; Antonson, Sibel A; Kilinc, Evren; Koch, Daniele; Antonson, Donald E; Dayangaç, Berrin; Ozgünaltay, Gül

    2012-01-01

    The aim of this study was to compare the effects of the Er,Cr:YSGG laser using chemical vapour deposition (CVD) bur cavity preparation with conventional preparation methods including a diamond bur and a carbide bur on the microleakage with two different adhesive systems. A total of 40 extracted human premolars were randomly assigned to four experimental groups according to the cavity preparation technique: group I diamond bur (Diatech); group II carbide bur (Diatech); group III Er,Cr:YSGG laser (Biolase Millennium II); and group IV CVD bur (CVDentUS). Using the different preparation techniques, Class V standardized preparations were performed on the buccal and lingual surfaces with gingival margins on the dentin and occlusal margins on the enamel. Each preparation group was randomly assigned to two subgroups (five teeth, ten preparations) according to the type of adhesive: an etch-and-rinse adhesive (Adper Single Bond), and a single-step self-etch adhesive (AdheSE One). All preparations were restored with a nanohybrid composite resin in a single increment. Following thermocycling (×500; 5-55°C), the teeth were immersed in basic fuchsin and sectioned in the orovestibular direction. Dye penetration was evaluated under a light microscope by two blinded examiners. Data were statistically analysed with the Kruskal-Wallis and Wilcoxon tests (p<0.05). There were no statistically significant differences between the preparation techniques with either of the two adhesive systems (p>0.05). Comparing the enamel and dentin leakage scores within each group, no statistically significant differences were found (p>0.05). The Er,Cr:YSGG laser cavity preparation did not differ from preparation with CVD, diamond or carbide bur in terms of microleakage with the different adhesive systems. PMID:20842517

  1. On hot atom non-equilibrium processes in laser chemistry and chemical lasers

    NASA Astrophysics Data System (ADS)

    Temkin, A. Ya.

    1986-09-01

    Hot atom reactions in laser chemistry and in the pumping of some kinds of chemical lasers are treated by the method of the non-equilibrium chemical kinetics proposed in previous works of the author. This method is based on the use of the multigroup approximation for the description of hot atom slowing down. The three-group approximation is applied to the kinetics of two hot H atom reactions with N 2O having different activation energies. The hot atoms are supposed to be produced by 248 nm excimer laser photolysis of HI and to have initial kinetic energies of 1.8907 and 0.95400 eV. The kinetics of these reactions and the dependence of the product yields on the rare gas concentration in the system are obtained. It was shown how the same formulae (with a change of symbols) can be applied to the description of the vibrotational level populations of product molecules. Some kinetic experiments are suggested to obtain the data necessary for the determination of the group constants. The hot atom kinetics of the chemical laser pumping made by the light of a flash-lamp (or of a laser) or by the particle beam is studied by use of the two-group approximation. A two-level model of the lasing molecule is employed. Lasing molecules are supposed to be produced by a hot atom reaction with the bulk molecules. The inverse population and its dependence on the rare gas concentration in the system are obtained. The possibility and usefulness of more complicated models (more energy groups and more molecular levels) are discussed.

  2. Electrothermal atomization laser-excited atomic fluorescence spectroscopy for the determination of indium

    SciTech Connect

    Aucelio, R.Q.; Smith, B.W.; Winefordner, J.D.

    1998-11-01

    A dye laser pumped by a high-repetition-rate copper vapor laser was used as the excitation source to determine indium at parts-per-trillion level by electrothermal atomization laser-excited atomic fluorescence spectrometry (ETA-LEAFS). A comparison was made between wall atomization, in pyrolytic and nonpyrolytic graphite tubes, and platform atomization. The influence of several chemical modifiers either in solution or precoated in the graphite tube was evaluated. The influence of several acids and NaOH in the analyte solution was also studied. Optimization of the analytical conditions was carried out to achieve the best signal-to-background ratio and consequently an absolute limit of detection of 1 fg. Some possible interferents of the method were evaluated. The method was evaluated by determining indium in blood, urine, soil, and urban dust samples. Recoveries between 99.17 and 109.17{percent} are reported. A precision of 4.1{percent} at the 10 ng&hthinsp;g{sup {minus}1} level in water standards was achieved. {copyright} {ital 1998} {ital Society for Applied Spectroscopy}

  3. Colloidal mercury (Hg) distribution in soil samples by sedimentation field-flow fractionation coupled to mercury cold vapour generation atomic absorption spectroscopy.

    PubMed

    Santoro, A; Terzano, R; Medici, L; Beciani, M; Pagnoni, A; Blo, G

    2012-01-01

    Diverse analytical techniques are available to determine the particle size distribution of potentially toxic elements in matrices of environmental interest such as soil, sediments, freshwater and groundwater. However, a single technique is often not exhaustive enough to determine both particle size distribution and element concentration. In the present work, the investigation of mercury in soil samples collected from a polluted industrial site was performed by using a new analytical approach which makes use of sedimentation field-flow fractionation (SdFFF) coupled to cold vapour generation electrothermal atomic absorption spectroscopy (CV-ETAAS). The Hg concentration in the SdFFF fractions revealed a broad distribution from about 0.1 to 1 ?m, roughly following the particle size distributions, presenting a maximum at about 400-700 nm in diameter. A correlation between the concentration of Hg in the colloidal fraction and organic matter (O.M.) content in the soil samples was also found. However, this correlation is less likely to be related to Hg sorption to soil O.M. but rather to the presence of colloidal mercuric sulfide particles whose size is probably controlled by the occurrence of dissolved O.M. The presence of O.M. could have prevented the aggregation of smaller particles, leading to an accumulation of mercuric sulfides in the colloidal fraction. In this respect, particle size distribution of soil samples can help to understand the role played by colloidal particles in mobilising mercury (also as insoluble compounds) and provide a significant contribution in determining the environmental impact of this toxic element. PMID:22089540

  4. A difference in using atomic layer deposition or physical vapour deposition TiN as electrode material in metal-insulator-metal and metal-insulator-silicon capacitors.

    PubMed

    Groenland, A W; Wolters, R A M; Kovalgin, A Y; Schmitz, J

    2011-09-01

    In this work, metal-insulator-metal (MIM) and metal-insulator-silicon (MIS) capacitors are studied using titanium nitride (TiN) as the electrode material. The effect of structural defects on the electrical properties on MIS and MIM capacitors is studied for various electrode configurations. In the MIM capacitors the bottom electrode is a patterned 100 nm TiN layer (called BE type 1), deposited via sputtering, while MIS capacitors have a flat bottom electrode (called BE type 2-silicon substrate). A high quality 50-100 nm thick SiO2 layer, made by inductively-coupled plasma CVD at 150 degrees C, is deposited as a dielectric on top of both types of bottom electrodes. BE type 1 (MIM) capacitors have a varying from low to high concentration of structural defects in the SiO2 layer. BE type 2 (MIS) capacitors have a low concentration of structural defects and are used as a reference. Two sets of each capacitor design are fabricated with the TiN top electrode deposited either via physical vapour deposition (PVD, i.e., sputtering) or atomic layer deposition (ALD). The MIM and MIS capacitors are electrically characterized in terms of the leakage current at an electric field of 0.1 MV/cm (I leak) and for different structural defect concentrations. It is shown that the structural defects only show up in the electrical characteristics of BE type 1 capacitors with an ALD TiN-based top electrode. This is due to the excellent step coverage of the ALD process. This work clearly demonstrates the sensitivity to process-induced structural defects, when ALD is used as a step in process integration of conductors on insulation materials. PMID:22097586

  5. Threshold of a random laser based on Raman gain in cold atoms

    E-print Network

    Kaiser, Robin

    . Husson, D. Sauteret, F. Auzel, and A. Migus, "Generation of spatially incoherent short pulses in laserThreshold of a random laser based on Raman gain in cold atoms William Guerin, Nicolas Mercadier address the problem of achieving a random laser with a cloud of cold atoms, in which gain and scattering

  6. 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.

  7. Search for a permanent EDM using laser cooled radioactive atom

    NASA Astrophysics Data System (ADS)

    Sakemi, Y.; Harada, K.; Hayamizu, T.; Itoh, M.; Kawamura, H.; Liu, S.; Nataraj, H. S.; Oikawa, A.; Saito, M.; Sato, T.; Yoshida, H. P.; Aoki, T.; Hatakeyama, A.; Murakami, T.; Imai, K.; Hatanaka, K.; Wakasa, T.; Shimizu, Y.; Uchida, M.

    2011-07-01

    An Electric Dipole Moment (EDM) of the elementary particle is a good prove to observe the phenomena beyond the Standard Model. A non-zero EDM shows the violation of the time reversal symmetry, and under the CPT invariance it means the CP violation. In paramagnetic atoms, an electron EDM results in an atomic EDM enhanced by the factor of the 3rd power of the charge of the nucleus due the relativistic effects. A heaviest alkali element francium (Fr), which is the radioactive atom, has the largest enhancement factor K ~ 895. Then, we are developing a high intensity laser cooled Fr factory at Cyclotron and Radioisotope Center (CYRIC), Tohoku University to perform the search for the EDM of Fr with the accuracy of 10-29 e · cm. The important points to overcome the current accuracy limit of the EDM are to realize the high intensity Fr source and to reduce the systematic error due to the motional magnetic field and inhomogeneous applied field. To reduce the dominant component of the systematic errors mentioned above, we will confine the Fr atoms in the small region with the Magneto-Optical Trap and optical lattice using the laser cooling and trapping techniques. The construction of the experimental apparatus is making progress, and the new thermal ionizer already produces the Fr of ~106 ions/s with the primary beam intensity 200 nA. The developments of the laser system and optical equipments are in progress, and the present status and future plan of the experimental project is reported.

  8. 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.

  9. 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.

  10. Direct determination of aluminum content in seawater by electrothermal atomization-laser excited atomic fluorescence

    NASA Astrophysics Data System (ADS)

    Le Bihan, A.; Lijour, Y.; Giamarchi, P.; Burel-Deschamps, L.; Stephan, L.

    2003-01-01

    The development of an analytical method for the direct determination of ultra trace content of aluminum in seawater by electrothermal atomization-laser excited atomic fluorescence (ETA-LEAF) using a pulsed Nd:Yag laser associated with an optical parametric oscillator (OPO) and an intensified CCD (ICCD) camera is described. The good temporal reproducibility of the device and the fairly long lifetime of the selected Al radiation allowed optimization of the temporal parameters in the nanosecond range. After optimizing thermal and optical parameters, this potentiality allowed to reach a 100 fg detection limit (5 ng l -1). The method was developed within a multidisciplinary program involving chemical and physical applications, thereby demonstrating the versatility of the apparatus.

  11. 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)

  12. Modeling a semiconductor laser with an intracavity atomic absorber

    NASA Astrophysics Data System (ADS)

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

    2009-07-01

    The dynamics of a semiconductor laser with an intracavity atomic absorber is studied numerically. The study is motivated by the experiments of Barbosa [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 D2 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 D2 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.

  13. Pump-Probe Spectroscopy of Laser-Cooled Atoms

    NASA Astrophysics Data System (ADS)

    Yu, I. A.

    2000-06-01

    We have studied pump-probe spectroscopy of cold ^87Rb atoms. The cold atoms are produced with a magneto-optical trap (MOT). Pump-probe spectra are measured without the presence of the MOT or any kind of optical molasses. In the measurement, the pump laser is fixed to a frequency around the resonance of the 5S_1/2,F=2 to 5P_3/2,F=3 transition and the probe laser frequency is scanned across the pump laser frequency. We have adjusted the pump frequency to red detunings, blue detunings, and the resonance for the study. Different polarization configurations of the probe and pump fields result in very different spectra of the probe absorption. The observed spectra exhibit a dispersion-like profile, a Lorentzian profile, a dispersion-like and a Lorentzian profiles, or two concentric dispersion-like profiles. The widths of all the spectral profiles are narrower than the natural linewidth of the excited states. Our work identifies the mechanisms behind these different spectral profiles. The mechanisms can be recoil-induced resonances, stimulated Raman transitions, Zeeman-coherence-induced resonances, and/or two-wave mixing. This work is supported by the National Science Council under the grant of NSC 89-2112-M-007-048.

  14. 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.

  15. 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

  16. Phase shift in an atom interferometer induced by the additional laser lines of a Raman laser generated by modulation

    E-print Network

    Olivier Carraz; Renée Charrière; Malo Cadoret; Nassim Zahzam; Yannick Bidel; Alexandre Bresson

    2012-05-03

    The use of Raman laser generated by modulation for light-pulse atom interferometer allows to have a laser system more compact and robust. However, the additional laser frequencies generated can perturb the atom interferometer. In this article, we present a precise calculation of the phase shift induced by the additional laser frequencies. The model is validated by comparison with experimental measurements on an atom gravimeter. The uncertainty of the phase shift determination limits the accuracy of our compact gravimeter at 8.10^-8 m/s^2. We show that it is possible to reduce considerably this inaccuracy with a better control of experimental parameters or with particular interferometer configurations.

  17. 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)

  18. Coherent Control of Laser Field and Spectroscopy in Dense Atomic Vapor 

    E-print Network

    Li, Hebin

    2011-08-08

    Coherent effects are studied in a dense atomic vapor driven by laser fields. With optical properties dramatically modified by these effects, the medium can be used to manipulate some of the properties of laser field. Our ...

  19. 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.

  20. Search for permanent EDM using laser cooled Fr atoms

    NASA Astrophysics Data System (ADS)

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

    2013-03-01

    The existence of a non-zero electric dipole moment (EDM) implies the violation of time reversal symmetry. As the time-reversal symmetry violation predicted by the Standard Model (SM) for the electron EDM is too small to be observed with current experimental techniques and any a non-zero EDM would indicate new physics beyond the SM. The tiny signal from the electron EDM is enhanced in the heavy atoms such as francium (Fr). We are constructing the laser-cooled Fr factory to search for the electron EDM.

  1. Mobility edge for cold atoms in laser speckle potentials

    E-print Network

    Dominique Delande; Giuliano Orso

    2015-02-17

    Using the transfer matrix method, we numerically compute the precise position of the mobility edge of atoms exposed to a laser speckle potential, and study its dependence vs. the disorder strength and correlation function. Our results deviate significantly from previous theoretical estimates using an approximate self-consistent approach of localization. In particular we find that the position of the mobility edge in blue-detuned speckles is much lower than in the red-detuned counterpart, pointing out the crucial role played by the asymmetric on-site distribution of speckle patterns.

  2. Enabling Nanotechnology with Focused Ion Beams from Laser Cooled Atoms

    NASA Astrophysics Data System (ADS)

    Steele, A. V.; Knuffman, B.; Orloff, J.; Maazouz, M.; McClelland, J. J.

    2011-05-01

    The Magneto-Optical Trap Ion Source (MOTIS) being developed at NIST has the potential to enable numerous advances in nanoscale science. In a MOTIS, atoms are captured into a MOT, photoionized, and accelerated to an energy of a few hundred eV to a few tens of kV. A beam formed in this way can be brought to a tight focus, competitive with the commercial focused ion beam machines deployed widely today. Additionally, the unique characteristics of this source, coupled with the user's choice of ion from the long and growing list of laser-coolable atomic species suggest that the MOTIS has the potential to advance the state of the art in applications such as imaging, nanofabrication, secondary ion mass spectrometry, and others. I will present high-resolution images from our lithium and chromium MOTIS-based focused ion beams and discuss applications which we will pursue with these new tools.

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

    E-print Network

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

    2015-04-30

    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.

  4. 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

  5. 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.

  6. 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.

  7. Ultra-narrow-linewidth combined CW Ti:Sapphire/Dye laser for atom cooling and high-precision spectroscopy

    E-print Network

    Kobtsev, Sergei M.

    Ultra-narrow-linewidth combined CW Ti:Sapphire/Dye laser for atom cooling and high.5 nm Ar laser 457.9 nm 514.5 nm Ar laser 457.9 nm CW Ti:Sapphire Laser Combined CW Ti:Sapphire/Dye Laser Introduction Dye laser and Ti:Sapphire laser are characterized by ability to tune over a wide

  8. 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.

  9. Linear Stark effect for a sulfur atom in strong high-frequency laser fields.

    PubMed

    Balanarayan, P; Moiseyev, Nimrod

    2013-06-21

    Current trends in laser technology have reached the regime of studying atoms stabilized against ionization, going beyond the perturbation theory. In this work, properties of a laser-dressed sulfur atom are examined in this stabilization regime. The electronic structure of a sulfur atom changes dramatically as it interacts with strong high-frequency laser fields. Degenerate molecularlike states are obtained for the ground state triplet of the laser-dressed sulfur atom for high-frequency and moderate intensity laser parameters. The degenerate ground state is obtained for a laser intensity which is smaller by more than one order of magnitude than the intensity required for hydrogen atoms due to many electron screening effects. An infinitesimally weak static field mixes these degenerate states to give rise to asymmetric states with large permanent dipole moments. Hence, a strong linear Stark effect rather than the usual quadratic one is obtained. PMID:23829733

  10. 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 Schrödinger 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.

  11. Autler-Townes effect for an atom in a 100% amplitude-modulated laser field. I. A dressed-atom approach

    E-print Network

    Stroud Jr., Carlos R.

    Autler-Townes effect for an atom in a 100% amplitude-modulated laser field. I. A dressed-atom probe field couples this strongly driven transition to a third atomic state. We obtain analytic When a sufficiently intense monochromatic laser field drives a two-level atomic resonance the resonant

  12. Excitation of an Atomic Transition with a Vortex Laser Beam

    E-print Network

    Christian T. Schmiegelow; Jonas Schulz; Henning Kaufmann; Thomas Ruster; Ulrich G. Poschinger; Ferdinand Schmidt-Kaler

    2015-11-23

    Photons carry one unit of angular momentum associated with their spin~\\cite{Beth1936}. Structured vortex beams carry additional orbital angular momentum which can also be transferred to matter~\\cite{Allen1992}. This extra twist has been used for example to drive motion of microscopic particles in optical tweezers as well as to create vortices in degenerate quantum gases~\\cite{He1995,Andersen2006}. Here we demonstrate the transfer of optical orbital angular momentum from the transverse spatial structure of the beam to the internal (electronic) degrees of freedom of an atom. Probing a quadrupole transition of a single trapped $^{40}$Ca$^+$ ion localized at the center of the vortex, we observe strongly modified selection rules, accounting for both the photon spin and the vorticity of the field. In particular, we show that an atom can absorb two quanta of angular momentum from a single photon even when rotational symmetry is conserved. In contrast to previous findings~\\cite{Araoka2005,Loeffler2011a,Mathevet2013}, our experiment allows for conditions where the vorticity of the laser beam determines the optical excitation, contributing to the long-standing discussion on whether the orbital angular momentum of photons can be transferred to atomic internal degrees of freedom~\\cite{VanEnk1994,Babiker2002,Jauregui2004, Schmiegelow2012, Mondal2014, Scholz-Marggraf2014} and paves the way for its use to tailor light-matter interactions.

  13. 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.

  14. Oxygen atom density and thermal energy control in an electric-oxygen iodine laser

    E-print Network

    Carroll, David L.

    Oxygen atom density and thermal energy control in an electric-oxygen iodine laser Benavides G. F-Champaign, Urbana, IL 61801, USA E-mail: benavides@cuaerospace.com ABSTRACT Experiments[1] with Electric Oxygen-Iodine Laser (ElectricOIL) heat exchanger technology have demonstrated improved control of oxygen atom density

  15. 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.

  16. Some Non-Perturbative and Non-Linear Effects in Laser-Atom Interaction

    E-print Network

    Qi-Ren Zhang

    2006-08-06

    We show that if the laser is intense enough, it may always ionize an atom or induce transitions between discrete energy levels of the atom, no matter what is its frequency. It means in the quantum transition of an atom interacting with an intense laser of circular frequency $\\omega$, the energy difference between the initial and the final states of the atom is not necessarily being an integer multiple of the quantum energy $\\hbar\\omega$. The absorption spectra become continuous. The Bohr condition is violated. The energy of photoelectrons becomes light intensity dependent in the intense laser photoelectric effect. The transition probabilities and cross sections of photo-excitations and photo-ionizations are laser intensity dependent, showing that these processes cannot be reduced to the results of interactions between the atom and separate individual photons, they are rather the processes of the atom interacting with the laser as a whole. The interaction of photons on atoms are not simply additive. The effects are non-perturbative and non-linear. Some numerical results for processes between hydrogen atom and intense circularly polarized laser, illustrating the non-perturbative and non-linear character of the atom-laser interaction, are given.

  17. Controlling double ionization of atoms in intense bichromatic laser pulses

    E-print Network

    Adam Kamor; Francois Mauger; Cristel Chandre; Turgay Uzer

    2010-11-11

    We consider the classical dynamics of a two-electron system subjected to an intense bichromatic linearly polarized laser pulse. By varying the parameters of the field, such as the phase lag and the relative amplitude between the two colors of the field, we observe several trends from the statistical analysis of a large ensemble of trajectories initially in the ground state energy of the helium atom: High sensitivity of the sequential double ionization component, low sensitivity of the intensities where nonsequential double ionization occurs while the corresponding yields can vary drastically. All these trends hold irrespective of which parameter is varied: the phase lag or the relative amplitude. We rationalize these observations by an analysis of the phase space structures which drive the dynamics of this system and determine the extent of double ionization. These trends turn out to be mainly regulated by the dynamics of the inner electron.

  18. 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.

  19. Laser-excited atomic fluorescence spectrometry in a graphite furnace with an

    E-print Network

    Michel, Robert G.

    Laser-excited atomic fluorescence spectrometry in a graphite furnace with an optical parametric oscillator laser for sequential multi-element determination of cadmium, cobalt, lead, manganese and thallium, for the ® rst time, that solid-state lasers required for analysis (ml or mg) and the technique has direct based

  20. 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.

  1. Laser sculpting of atomic sp, sp(2) , and sp(3) hybrid orbitals.

    PubMed

    Liu, Chunmei; Manz, Jörn; Yang, Yonggang

    2015-01-12

    Atomic sp, sp(2) , and sp(3) hybrid orbitals were introduced by Linus Pauling to explain the nature of the chemical bond. Quantum dynamics simulations show that they can be sculpted by means of a selective series of coherent laser pulses, starting from the 1s orbital of the hydrogen atom. Laser hybridization generates atoms with state-selective electric dipoles, opening up new possibilities for the study of chemical reaction dynamics and heterogeneous catalysis. PMID:25257703

  2. 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.

  3. Transient absorption spectra of the laser-dressed hydrogen atom

    NASA Astrophysics Data System (ADS)

    Murakami, Mitsuko; Chu, Shih-I.

    2013-10-01

    We present a theoretical study of transient absorption spectra of laser-dressed hydrogen atoms, based on numerical solutions of the time-dependent Schrödinger equation. The timing of absorption is controlled by the delay between an extreme ultra violet (XUV) pulse and an infrared (IR) laser field. The XUV pulse is isolated and several hundred attoseconds in duration, which acts as a pump to drive the ground-state electron to excited p states. The subsequent interaction with the IR field produces dressed states, which manifest as sidebands between the 1s-np absorption spectra separated by one IR-photon energy. We demonstrate that the population of dressed states is maximized when the timing of the XUV pulse coincides with the zero crossing of the IR field, and that their energies can be manipulated in a subcycle time scale by adding a chirp to the IR field. An alternative perspective to the problem is to think of the XUV pulse as a probe to detect the dynamical ac Stark shifts. Our results indicate that the accidental degeneracy of the hydrogen excited states is removed while they are dressed by the IR field, leading to large ac Stark shifts. Furthermore, we observe the Autler-Townes doublets for the n=2 and 3 levels using the 656 nm dressing field, but their separation does not agree with the prediction by the conventional three-level model that neglects the dynamical ac Stark shifts.

  4. 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.

  5. VCSEL Laser System for Atomic Clocks Nathan Belcher REU program, College of William and Mary

    E-print Network

    Novikova, Irina

    VCSEL Laser System for Atomic Clocks Nathan Belcher REU program, College of William and Mary I of my project is to create a prototype atomic clock, and this summer's research has been all about modulation with rf signals, and use in miniature atomic clocks. This paper will describe the theory behind

  6. 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 ?2H and ?18O 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.

  7. Bessel beams of two-level atoms driven by a linearly polarized laser field

    E-print Network

    Armen G. Hayrapetyan; Oliver Matula; Andrey Surzhykov; Stephan Fritzsche

    2013-08-04

    We study Bessel beams of two-level atoms that are driven by a linearly polarized laser field. Starting from the Schroedinger equation, we determine the states of two-level atoms in a plane-wave field respecting propagation directions both of the atom and the field. For such laser-driven two-level atoms, we construct Bessel beams beyond the typical paraxial approximation. We show that the probability density of these atomic beams obtains a non-trivial, Bessel-squared-type behavior and can be tuned under the special choice of the atom and laser parameters, such as the nuclear charge, atom velocity, laser frequency, and propagation geometry of the atom and laser beams. Moreover, we spatially and temporally characterize the beam of hydrogen and selected (neutral) alkali-metal atoms that carry non-zero orbital angular momentum (OAM). The proposed spatiotemporal Bessel states (i) are able to describe, in principle, twisted states of any two-level system which is driven by the radiation field and (ii) have potential applications in atomic, nuclear processes and quantum communication.

  8. 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.

  9. 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.

  10. 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

  11. Laser-excited atomic fluorescence of atoms produced in a graphite furnace

    SciTech Connect

    Goforth, D.; Winefordner, J.D.

    1986-11-01

    Laser-excited atomic fluorescence in a graphite furnace gives detection limits for Pb, Cu, Mn, Sn, Al, In, Li, and Pt, in the picogram to sub-picogram range. The linear dynamic range for these elements varies from 3 to 7 orders of magnitude. A graphite rod, a plain graphite cup, and a slotted graphite cup are compared as the cuvette in the fluorescence system. Detection limits for a pyrolytic coating, a tantalum foil liner, and a tantalum carbide coating of the graphite cuvette are compared. A hydrogen-argon atmosphere, a low-pressure atmosphere, and an argon atmosphere are compared as the atmosphere surrounding the graphite cuvette. Lastly, Cu and Mn are determined in several standard reference materials.

  12. Coherence and linewidth of a continuously pumped atom laser at finite temperature

    NASA Astrophysics Data System (ADS)

    Lee, Geoffrey M.; Haine, Simon A.; Bradley, Ashton S.; Davis, Matthew J.

    2015-07-01

    A continuous-wave atom laser formed by the outcoupling of atoms from a trapped Bose-Einstein condensate (BEC) potentially has a range of metrological applications. However, in order for the device to be truly continuous, a mechanism to replenish the atoms in the BEC is required. Here we calculate the temporal coherence properties of a continuously pumped atom laser beam outcoupled from a trapped Bose-Einstein condensate that is replenished from a reservoir at finite temperature. We find that the thermal fluctuations of the condensate can significantly decrease the temporal coherence of the output beam due to atomic interactions between the trapped BEC and the beam, and this can impact the metrological usefulness of the device. We demonstrate that a Raman outcoupling scheme imparting a sufficient momentum kick to the atom laser beam can lead to a significantly reduced linewidth.

  13. Development of Laser Light Sources for Trapping Radioactive Francium Atoms Toward Tests of Fundamental Symmetries

    NASA Astrophysics Data System (ADS)

    Harada, Ken-ichi; Ezure, Saki; Hayamizu, Tomohiro; Kato, Ko; Kawamura, Hirokazu; Inoue, Takeshi; Arikawa, Hiroshi; Ishikawa, Taisuke; Aoki, Takahiro; Uchiyama, Aiko; Itoh, Masatoshi; Ando, Shun; Aoki, Takatoshi; Hatakeyama, Atsushi; Hatanaka, Kichiji; Imai, Kenichi; Murakami, Tetsuya; Shimizu, Yasuhiro; Sato, Tomoya; Wakasa, Tomotsugu; Yoshida, Hidetomo P.; Sakemi, Yasuhiro

    We have developed laser light sources and a magneto-optical trap system for cooling and trapping radioactive francium (Fr) atoms. Because Fr is the heaviest alkali element, a Fr atom exhibits high sensitivity to symmetry violation effects such as atomic parity nonconservation (APNC) and the electron electric dipole moment (eEDM). A laser cooling and trapping technique reduces the systematic errors due to the Doppler effect and the motion-induced magnetic field effect caused by the velocity of atoms. Thus, optically cooled and trapped Fr atoms are among a few promising candidates considered for APNC and eEDM measurements. Frequency stabilization of laser light is required for any stable measurement involving trapped radioactive atoms, including Fr. Since the hyperfine splitting in iodine molecules (127I2) is close to the resonance frequency of the Fr D2 line, we performed frequency modulation spectroscopy of hyperfine structures of I2.

  14. Molybdenum atoms yield in pulse ultraviolet laser photolysis of Mo(CO)6

    NASA Astrophysics Data System (ADS)

    Eremin, A. V.; Gurentsov, E. V.; Musikhin, S. A.

    2015-11-01

    Atomic resonance absorption spectroscopy has been used to study the yield of molybdenum atoms in the process of ultraviolet laser pulse photo-dissociation of Mo(CO)6 vapor. Molybdenum atoms in a ground state were formed by the quenching of the electronically excited Mo atoms generated during photolysis and were detected using the resonance absorption at a wavelength of 386.41 nm. The effective quenching rates were measured in the presence of various bath gases.

  15. 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

  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. Spectra of Electromagnetically Induced Absorption in Laser-Cooled Atoms

    NASA Astrophysics Data System (ADS)

    Chen, Ying-Cheng; Liao, Yen-An; Chen, Yun-Wen; Su, Jung-Jung; Yu, Ite A.

    2001-05-01

    Electromagnetically induced absorption (EIA) is the phenomenon that absorption of the probe field is enhanced by the presence of the coupling field in a two-level system. It is due to constructive interference between the coherence among degenerate Zeeman sublevels and the optical coherence driven by the probe field. The spectral profile of the EIA phenomenon is a sharp peak on top of the broader profile that is due to the direct probe transition between the ground and the excited states. Linewidth of the EIA peak can be very narrow and is determined by the relaxation rate of the coherence between degenerate Zeeman sublevels. We have systematically studied the EIA spectra in cold ^87Rb atoms produced by a magneto-optical trap (MOT). The frequency of the coupling field is fixed at the resonance of the 5S_1/2,F=2 to 5P_3/2,F=3 transition and the probe frequency is swept across the coupling frequency. Both fields are linearly polarized and their polarization directions are orthogonal. During the measurement of the spectrum, the laser and magnetic fields of the MOT are momentarily turned off. The experimental spectra are consistent with the theoretical predictions from the density-matrix calculation. The measured EIA linewidth can be as narrow as 90 kHz or 0.015?, where ? is the natural linewidth of the excited state. Our work demonstrates the EIA spectrum can be applied to temperature measurements of cold atoms and precision detection of magnetic fields. This work is supported by the National Science Council under the grant of NSC 89-2112-M-007-061.

  19. 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.

  20. Inversion symmetry breaking of atomic bound states in strong and short laser fields

    E-print Network

    Stooß, Veit; Ott, Christian; Blättermann, Alexander; Ding, Thomas; Pfeifer, Thomas

    2015-01-01

    In any atomic species, the spherically symmetric potential originating from the charged nucleus results in fundamental symmetry properties governing the structure of atomic states and transition rules between them. If atoms are exposed to external electric fields, these properties are modified giving rise to energy shifts such as the AC Stark-effect in varying fields and, contrary to this in a constant (DC) electric field for high enough field strengths, the breaking of the atomic symmetry which causes fundamental changes in the atom's properties. This has already been observed for atomic Rydberg states with high principal quantum numbers. Here, we report on the observation of symmetry breaking effects in Helium atoms for states with principal quantum number n=2 utilizing strong visible laser fields. These findings were enabled by temporally resolving the dynamics better than the sub-optical cycle of the applied laser field, utilizing the method of attosecond transient absorption spectroscopy (ATAS). We ident...

  1. Non-additivity in laser-illuminated many-atom systems.

    PubMed

    Shahmoon, Ephraim; Mazets, Igor; Kurizki, Gershon

    2014-06-15

    We show that atoms subject to laser radiation may form a non-additive many-body system on account of their long-range forces, when the atoms are trapped in the vicinity of a fiber with a Bragg grating. When the laser frequency is inside the grating's bandgap but very close to its edge, we find that the range and strength of the laser-induced interaction becomes substantially enhanced, due to the large density of states near the edge, while the competing process of scattering to the fiber is inhibited. The dynamics of the atomic positions in this system conforms to a prominent model of statistical physics which exhibits slow relaxation. This suggests the possibility of using laser-illuminated atoms to study the characteristics of non-additive systems. PMID:24978565

  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. Intensity-resolved Above Threshold Ionization Yields of Atoms with Ultrashort Laser Pulses 

    E-print Network

    Hart, Nathan Andrew

    2012-10-19

    of the laser. ____________ This thesis follows the style of Advances in Atomic, Molecular and Optical Physics. 2 Several methods have been employed to work around this difficulty. Hansch and Van Woerkom (1996) used a two dimensional z...

  4. Quantum control of qubits and atomic motion using ultrafast laser pulses

    NASA Astrophysics Data System (ADS)

    Mizrahi, J.; Neyenhuis, B.; Johnson, K. G.; Campbell, W. C.; Senko, C.; Hayes, D.; Monroe, C.

    2014-01-01

    Pulsed lasers offer significant advantages over continuous wave (CW) lasers in the coherent control of qubits. Here we review the theoretical and experimental aspects of controlling the internal and external states of individual trapped atoms with pulse trains. Two distinct regimes of laser intensity are identified. When the pulses are sufficiently weak that the Rabi frequency ? is much smaller than the trap frequency ? trap, sideband transitions can be addressed and atom-atom entanglement can be accomplished in much the same way as with CW lasers. By contrast, if the pulses are very strong ? ? ? trap, impulsive spin-dependent kicks can be combined to create entangling gates which are much faster than a trap period. These fast entangling gates should work outside of the Lamb-Dicke regime and be insensitive to thermal atomic motion.

  5. 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.

  6. Direct atomic flux measurement of electron-beam evaporated yttrium with a diode-laser-based atomic absorption monitor at 668 nm

    E-print Network

    Fejer, Martin M.

    Direct atomic flux measurement of electron-beam evaporated yttrium with a diode-laser-based atomic May 1997 A direct measurement of atomic flux in e-beam evaporated yttrium has been demonstrated den- sity and velocity, and thus the atomic flux in an e-beam evaporated yttrium system with a diode

  7. Reactions of pulsed laser produced boron and nitrogen atoms in a condensing argon stream

    E-print Network

    Martin, Jan M.L.

    Reactions of pulsed laser produced boron and nitrogen atoms in a condensing argon stream Lester dilution in argon favored diboron species. At low laser power with minimum radiation, the dominant reaction for argon matrix reactions; instead intense new infrared ab- sorptions, with boron isotopic multiplets, were

  8. Mapping of laser diode radiation intensity by atomic-force microscopy

    NASA Astrophysics Data System (ADS)

    Alekseev, P. A.; Dunaevskii, M. S.; Slipchenko, S. O.; Podoskin, A. A.; Tarasov, I. S.

    2015-09-01

    The distribution of the intensity of laser diode radiation has been studied using an original method based on atomic-force microscopy (AFM). It is shown that the laser radiation intensity in both the near field and transition zone of a high-power semiconductor laser under room-temperature conditions can be mapped by AFM at a subwavelength resolution. The obtained patterns of radiation intensity distribution agree with the data of modeling and the results of near-field optical microscopy measurements.

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

    E-print Network

    Bajcsy, Michal

    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 ...

  10. Linear Stark Effect for a Sulfur Atom in Strong High-Frequency Laser Fields P. Balanarayan and Nimrod Moiseyev*

    E-print Network

    Moiseyev, Nimrod

    Linear Stark Effect for a Sulfur Atom in Strong High-Frequency Laser Fields P. Balanarayan the perturbation theory. In this work, properties of a laser-dressed sulfur atom are examined in this stabilization regime. The electronic structure of a sulfur atom changes dramatically as it interacts with strong high

  11. Autler-Townes effect for an atom in a 100% amplitude-modulated laser field. II. Experimental results

    E-print Network

    Stroud Jr., Carlos R.

    Autler-Townes effect for an atom in a 100% amplitude-modulated laser field. II. Experimental We report the observation of the Autler-Townes absorption spectrum of a two-level atom in a 100% amplitude-modulated optical field. Two frequency-stabilized dye lasers interact with a three-level atomic

  12. A pumped atom laser NICHOLAS P. ROBINS*, CRISTINA FIGL, MATTHEW JEPPESEN, GRAHAM R. DENNIS AND JOHN D. CLOSE

    E-print Network

    Loss, Daniel

    ARTICLES A pumped atom laser NICHOLAS P. ROBINS*, CRISTINA FIGL, MATTHEW JEPPESEN, GRAHAM R. DENNIS AND JOHN D. CLOSE ARC Centre for Quantum-Atom Optics, Physics Department, Australian National University.1038/nphys1027 The atom laser, a bright, coherent matter wave derived from a Bose­Einstein condensate, holds

  13. 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.

  14. Improving Raman velocimetry of laser-cooled cesium atoms by spin-polarization

    E-print Network

    Julien Chabé; Hans Lignier; Pascal Szriftgiser; Jean Claude Garreau

    2007-02-04

    We study the peformances of Raman velocimetry applied to laser-cooled, spin-polarized, cesium atoms. Atoms are optically pumped into the F=4, m=0 ground-state Zeeman sublevel, which is insensitive to magnetic perturbations. High resolution Raman stimulated spectroscopy is shown to produce Fourier-limited lines, allowing, in realistic experimental conditions, atomic velocity selection to one-fiftieth of a recoil velocity.

  15. Effects of laser radiation field on energies of hydrogen atom in plasmas

    NASA Astrophysics Data System (ADS)

    Bahar, M. K.

    2015-09-01

    In this study, for the first time, the Schrödinger equation with more general exponential cosine screened Coulomb (MGECSC) potential is solved numerically in the presence of laser radiation field within the Ehlotzky approximation using the asymptotic iteration method. The MGECSC potential includes four different potential forms in consideration of different sets of the parameters in the potential. By applying laser field, the total interaction potential of hydrogen atom embedded in plasmas converts to double well-type potential. The plasma screening effects under the influence of laser field as well as confinement effects of laser field on hydrogen atom in Debye and quantum plasmas are investigated by solving the Schrödinger equation with the laser-dressed MGECSC potential. It is resulted that since applying a monochromatic laser field on hydrogen atom embedded in a Debye and quantum plasma causes to shift in the profile of the total interaction potential, the confinement effects of laser field on hydrogen atom in plasmas modeled by the MGECSC potential change localizations of energy states.

  16. 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.

  17. 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 Schrödinger 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

  18. Laser Cooling and Trapping of Neutral Mercury Atoms Using an Optically-Pumped External-Cavity Semiconductor Laser

    NASA Astrophysics Data System (ADS)

    Paul, Justin; Lytle, Christian; Jones, R. Jason

    2011-05-01

    The level structure of the Hg atom is similar to other alkaline earth-like atoms, offering the possibility to realize an extremely high quality resonance factor (Q) on the ``clock'' transition (1S0- 3P0) when confined in an optical lattice at the Stark-shift free wavelength. A key feature of the Hg system is the reduced uncertainty due to black-body induced Stark shifts, making it an interesting candidate as an optical frequency standard. One challenge to laser-cooling neutral Hg atoms is finding a reliable source for cooling on the 1S0-3 P1 transition at 253.7 nm. We employ an optically pumped semiconductor laser (OPSEL) operating at 1015 nm, whose frequency is quadrupled in two external-cavity doubling stages to generate over 120 mW at 253.7 nm. With this new laser source we have trapped Hg199 from a background vapor in a standard MOT. We trap up to 2 × 106 atoms with a 1/e2 radius of our MOT of ~310 microns, corresponding to a density of 1.28 × 1010 atoms/cm3. We report on the progress of our Hg system and plans for precision lattice-based spectroscopy of the clock transition. Support for this work is supported through the U.S. Air Force Office of Scientific Research (AFOSR) through grant no. FA9550-09-1-0563.

  19. Differential cross sections for ionization and excitation of laser-aligned atoms by electron impact

    NASA Astrophysics Data System (ADS)

    Murray, Andrew

    2012-06-01

    Differential cross section measurements will be presented for electron impact ionization and excitation of atoms prepared using high resolution continuous wave laser radiation. In the case of ionization, low energy coplanar asymmetric (e,2e) experiments were performed from laser excited Mg atoms that were aligned using radiation around 285nm. The atoms were subjected to linearly polarized radiation whose polarization vector was varied from in the plane to perpendicular to the scattering plane. Ionization measurements were then conducted from the laser-excited 3P state, and the differential cross section determined. By careful analysis of the laser pumping, these measurements were directly compared to those from the ground state. Such experiments provide valuable information on the ionization of aligned targets. In the second experiment to be described here, a resonant enhancement cavity has been placed around the interaction region and super-elastic scattering measurements have been carried out from laser-excited atoms inside the cavity. This new technique opens up many new targets for study, since the cavity increases the effective intensity of the laser radiation that is exciting the atoms by a factor of up to 50. As such, new ionization and excitation measurements are possible using deep UV radiation where the laser power is only a few mW. Results from calcium will be presented, and progress towards studies from silver, copper and gold will be discussed. We are also advancing this new technique to allow simultaneous excitation from the hyperfine levels of different targets (such as Rb), which will allow the method to be adopted in different fields, such as laser cooling and trapping.

  20. Effects of laser energy and wavelength on the analysis of LiFePO? 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 LiFePO? 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 ¹?O?? 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 LiFePO?. Plotting of multihit events on Saxey plots also revealed a strong neutral O? loss from molecular dissociation, but quantification of this loss was insufficient to account for the observed oxygen deficiency.« less

  1. Effects of laser energy and wavelength on the analysis of LiFePO? 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 LiFePO? 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 ¹?O?? 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 LiFePO?. Plotting of multihit events on Saxey plots also revealed a strong neutral O? loss from molecular dissociation, but quantification of this loss was insufficient to account for the observed oxygen deficiency.

  2. 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.

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

    SciTech Connect

    Kaprálová-Ž?ánská, 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. Laser-Excited Atomic Fluorescence Spectrometry in a Pressure-Controlled Electrothermal Atomizer

    E-print Network

    Michel, Robert G.

    - mized. Experiments to test the model included the direct determination of phosphorus and tellurium. For the atomization of tellurium directly from a solid nickel alloy, and the atomization of cobalt from an aqueous

  5. 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.

  6. 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.

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

    E-print Network

    Neill Lambert; Franco Nori; Christian Flindt

    2015-11-23

    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.

  8. 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.

  9. 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.

  10. 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.

  11. 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.

  12. Control of terahertz photoelectron currents generated by intense two-color laser radiation interacting with atoms

    NASA Astrophysics Data System (ADS)

    Popruzhenko, S. V.; Tulsky, V. A.

    2015-09-01

    Using the strong-field approximation, a net photoelectron current, generated due to the interaction of an intense two-color laser field consisting of the fundamental and the second harmonic of infrared laser radiation with an atom, is found. The focus is on the case in which neither of the two field components can be treated perturbatively. The dependence of the current on the ratio of the harmonic amplitudes and their relative phase is studied and parameters maximizing the current are specified.

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

    NASA Astrophysics Data System (ADS)

    Öztürk, I. K.; Ba?ar, Gö; Er, A.; Güzelçimen, F.; Ba?ar, Gü; Kröger, 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.

  14. 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.

  15. 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.

  16. Theoretical study on isotope separation of an ytterbium atomic beam by laser deflection

    NASA Astrophysics Data System (ADS)

    Zhou, Min; Xu, Xin-Ye

    2014-01-01

    Isotope separation by laser deflecting an atomic beam is analyzed theoretically. Interacting with a tilted one-dimensional optical molasses, an ytterbium atomic beam is split into multi-beams with different isotopes like 172Yb,173Yb, and 174Yb. By using the numerical calculation, the dependences of the splitting angle on the molasses laser intensity and detuning are studied, and the optimal parameters for the isotope separation are also investigated. Furthermore, the isotope separation efficiency and purity are estimated. Finally a new scheme for the efficient isotope separation is proposed. These findings will give a guideline for simply obtaining pure isotopes of various elements.

  17. Multimode-to-monomode guided-atom lasers: An entropic analysis

    SciTech Connect

    Gattobigio, G. L.; Guery-Odelin, D.; Couvert, A.; Jeppesen, M.; Mathevet, R.

    2009-10-15

    We have experimentally demonstrated a high level of control of the mode populations of guided-atom lasers (GALs) by showing that the entropies per particle of an optically GAL and the one of the trapped Bose-Einstein condensate (BEC) from which it has been produced are the same. The BEC is prepared in a crossed beam optical dipole trap. We have achieved isentropic outcoupling for both magnetic and optical schemes. We can prepare GAL in a nearly pure monomode regime (85% in the ground state). Furthermore, optical outcoupling enables the production of spinor guided-atom lasers and opens the possibility to tailor their polarization.

  18. 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.

  19. Laser safety information for the Atomic, Molecular and Optical (AMO) Physics Labs at Lehigh University modified from the laser safety program developed by the office of Environmental

    E-print Network

    Huennekens, John

    1 Laser safety information for the Atomic, Molecular and Optical (AMO) Physics Labs at Lehigh University modified from the laser safety program developed by the office of Environmental Health and Safety using the following reference materials: I. American National Standards for Safe Use of Lasers - ANSI Z

  20. Magnetic induced dichroism and frequency stabilization of violet-blue diode lasers on gallium atomic transitions

    SciTech Connect

    Fazio, Barbara; Marago, Onofrio M.; Musso, Maurizio

    2005-06-01

    We study the magnetic-field-induced dichroism on a sample of gallium neutral atoms created in a hollow cathode lamp and describe a method for robust stabilization of violet-blue diode lasers tuned on gallium atomic transitions for an atom nanofabrication experiment. We compare the experimental dichroic signals with theoretical simulations obtained by the solving of the exact atom-field interaction Hamiltonian. We find excellent agreement when considering the magnetic field shielding from the hollow cathode. This method allows for a wide range of frequency tuning, modulation-free locking, and long-term stability of external-cavity diode lasers. From analysis of a square root Allan variance we have achieved a stability of 1 MHz at 1-s average time.

  1. 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.

  2. 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.

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

    E-print Network

    Cricchio, Dario; Hatsagortsyan, Karen Z

    2015-01-01

    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.

  4. 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.

  5. 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.

  6. Production of a cold atomic vapor using diode-laser cooling

    SciTech Connect

    Sesko, D.; Fan, C.G.; Wieman, C.E.

    1988-06-01

    We have used the light from diode lasers (lambda = 852 nm) to damp the motion of atoms in a cesium vapor. We have been able to contain more than 10/sup 7/ atoms for 0.2 sec and cool them to a temperature of 100/sup +100/..sqrt../sub 30/ ..mu..K in this viscous photon medium (the so-called optical molasses).

  7. Search for Laser-Induced Formation of Antihydrogen Atoms

    SciTech Connect

    Amoretti, M.; Macri, M.; Testera, G.; Variola, A.; Amsler, C.; Pruys, H.; Regenfus, C.; Bonomi, G.; Bowe, P. D.; Ejsing, A. M.; Hangst, J. S.; Madsen, N.; Canali, C.; Carraro, C.; Lagomarsino, V.; Manuzio, G.; Cesar, C. L.; Charlton, M.; Joergensen, L. V.; Mitchard, D.

    2006-11-24

    Antihydrogen can be synthesized by mixing antiprotons and positrons in a Penning trap environment. Here an experiment to stimulate the formation of antihydrogen in the n=11 quantum state by the introduction of light from a CO{sub 2} continuous wave laser is described. An overall upper limit of 0.8% with 90% C.L. on the laser-induced enhancement of the recombination has been found. This result strongly suggests that radiative recombination contributes negligibly to the antihydrogen formed in the experimental conditions used by the ATHENA Collaboration.

  8. 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.

  9. 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˜2ln10?2/?2Ip (Ip, ionization potential; ? , 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.

  10. 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.

  11. 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)

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

    E-print Network

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

    2015-08-15

    The problem of deep laser cooling of $^{24}$Mg atoms is theoretically studied. We propose two-stage sub-Doppler cooling strategy using electro-dipole transition $3^3P_2$$\\to$$3^3D_3$ ($\\lambda$=383.9 nm). The first stage implies exploiting magneto-optical trap with $\\sigma^+$ and $\\sigma^-$ light beams, while the second one uses a lin$\\perp$lin molasses. We focus on achieving large number of ultracold atoms (T$_{eff}$ magnesium atoms, being cooled in large number down to several microkelvins, have certain interest, for example, in quantum metrology.

  13. Ultra-narrow-linewidth combined CW Ti:Sapphire/Dye laser for atom cooling and high-precision spectroscopy

    E-print Network

    Kobtsev, Sergei M.

    Ultra-narrow-linewidth combined CW Ti:Sapphire/Dye laser for atom cooling and high 37, k. 141, Novosibirsk, 630058, Russia ABSTRACT Presented is a new combined CW Ti:Sapphire/Dye laser-term output line width does not exceed 10 kHz for the Ti:Sapphire laser and amounts to 50 kHz for the Dye

  14. 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.

  15. Tunable frequency-stabilization of UV laser using a Hallow-Cathode Lamp of atomic thallium

    E-print Network

    Chen, Tzu-Ling; Shy, Jow-Tsong; Liu, Yi-Wei

    2013-01-01

    A frequency-stabilized ultraviolet laser system, locked to the thallium resonant transition of 377.5 nm, was demonstrated using a novel bichromatic spectroscopy technique for tuning the zero-crossing laser-lock point. The atomic thallium system is a promising candidate in atomic parity violation and permanent electric dipole moment experiments, and its 377.5 nm 6P1/2->7S1/2 transition is important for thallium laser cooling and trapping experiment. The pressure shift, owing to the high pressure bu?er gas of the hollow-cathode lamp, was observed using an atomic beam resonance as reference. Such a shift was corrected by adjusting the peak ratio of the two Doppler-free saturation pro?les resulted from two pumping beams with a 130 MHz frequency di?erence. The resulted frequency stability of the ultraviolet laser is ?0.5 MHz at 0.1 sec integration time. This scheme is compact and versatile for stabilizing UV laser systems, which acquire a sub-MHz stability and frequency tunability.

  16. Characterization of laser cooling in a high-magnetic-field atom trap

    NASA Astrophysics Data System (ADS)

    Paradis, E.; Zigo, S.; Hu, K. Z.; Raithel, G.

    2012-08-01

    We describe cooling and trapping of both 85Rb and 87Rb in a range of magnetic fields up to 2.6 T. Atoms are injected from a low-field pyramidal magneto-optical trap and recaptured in a high-magnetic-field atom trap. The atoms are cooled and trapped by a six-beam optical molasses via the 5S1/2|mI,mJ= 1/2>? 5P3/2|mI,mJ= 3/2> transition (mI= 5/2 for 85Rb and mI= 3/2 for 87Rb). We study the trap fluorescence spectra, atom temperatures, density distributions, and lifetimes as a function of magnetic field and detuning parameters. The trap fluorescence spectra are both narrow and asymmetric, as is characteristic for laser cooling of atoms in an external trapping potential. The trap is modeled using a Monte Carlo trajectory simulation technique.

  17. 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.

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

    DOEpatents

    Scheibner, Karl F. (Tracy, CA); Haynam, Christopher A. (Pleasanton, CA); Johnson, Michael A. (Pleasanton, CA); Worden, Earl F. (Diablo, CA)

    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.

  19. 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.

  20. Laser-assisted ion-atom collisions: Plateau, cutoff, and multiphoton peaks

    SciTech Connect

    Ciappina, Marcelo F.; Madsen, Lars Bojer

    2008-02-15

    We study ionization in laser-assisted high-energy nonrelativistic ion-atom collisions and show that the low-energy angular differential electron spectrum may be enhanced by five orders of magnitude by an external field of strength less than 1/100 of the atomic field. With increasing strength of the assisting field, the energy spectrum develops a plateau with a characteristic cutoff. In the plateau region we predict distinct multiphoton peaks separated by the photon energy of the assisting field. In the present laser-assisted continuum-distorted-wave eikonal-initial-state theory, this effect may be related to the dynamics in the two-body electron-projectile subsystem. The laser-assisted distorted wave Born and first Born approximation do not account for the phase-distortion of the target electron by the incoming projectile and consequently the associated plateau, cutoff, and multiphoton features are not predicted by these latter theories.

  1. Synchronization of internal and external degrees of freedom of atoms in a standing laser wave

    SciTech Connect

    Argonov, V.Yu.; Prants, S.V.

    2005-05-15

    We consider dissipative dynamics of atoms in a strong standing laser wave and find a nonlinear dynamical effect of synchronization between center-of-mass motion and internal Rabi oscillations. The synchronization manifests itself in the phase space as limit cycles, which may have different periods and riddled basins of attraction. The effect can be detected in fluorescence spectra of atoms as equidistant sideband frequencies with the space between adjacent peaks to be inversely proportional to the value of the period of the respective limit cycle. With increasing intensity of the laser field, we numerically observe cascades of bifurcations that eventually end up in settling a strange chaotic attractor. A broadband noise is shown to destroy a fine structure of the bifurcation scenario, but prominent features of period-1 and period-3 limit cycles survive under a weak noise. The character of the atomic motion is analyzed with the help of the friction force whose zeroes are attractor or repellor points in the velocity space. We find ranges of the laser parameters where the atomic motion resembles a random but deterministic walking of atoms erratically jumping between different wells of the optical potential. Such a random walking is shown to be fractal.

  2. Spontaneous and parametric processes in warm rubidium vapours

    E-print Network

    D?browski, Micha?; P?cak, Daniel; Chrapkiewicz, Rados?aw; Wasilewski, Wojciech

    2014-01-01

    Warm rubidium vapours are known to be a versatile medium for a variety of experiments in atomic physics and quantum optics. Here we present experimental results on producing the frequency converted light for quantum applications based on spontaneous and stimulated processes in rubidium vapours. In particular, we study the efficiency of spontaneously initiated stimulated Raman scattering in the {\\Lambda}-level configuration and conditions of generating the coherent blue light assisted by multi-photon transitions in the diamond-level configuration. Our results will be helpful in search for new types of interfaces between light and atomic quantum memories.

  3. 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)(?/2)R(y)(?)R(x)(?/2) composite interaction as well. PMID:25680137

  4. 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.

  5. Laser Ablation Solid Sampling processes investigated usinginductively coupled plasma - atomic emission spectroscopy (ICP-AES)

    SciTech Connect

    Mao, X.L.; Ciocan, A.C.; Borisov, O.V.; Russo, R.E.

    1997-07-01

    The symbiotic relationship between laser ablation mechanismsand analytical performance using inductively coupled plasma-atomicemission spectroscopy are addressed in this work. For both cases, it isimportant to ensure that the ICP conditions (temperature and electronnumber density) are not effected by the ablated mass. By ensuring thatthe ICP conditions are constant, changes in spectral emission intensitywill be directly related to changes in laser ablation behavior. Mg ionicline to atomic line ratios and excitation temperature were measured tomonitor the ICP conditions during laser-ablation sample introduction. Thequantity of ablated mass depends on the laser pulse duration andwavelength. The quantity of mass removed per unit energy is larger whenablating with shorter laser wavelengths and pulses. Preferential ablationof constituents from a multicomponent sample was found to depend on thelaser beam properties (wavelength and pulse duration). Fornanosecond-pulsed lasers, thermal vaporization dominates the ablationprocess. For picosecond-pulsed lasers, a non-thermal mechanism appears todominate the ablation process. This work will describe the mass ablationbehavior during nanosecond and picosecond laser sampling into the ICP.The behavior of the ICP under mass loading conditions is firstestablished, followed by studies of the ablation behavior at variouspower densities. A thermal vaporization model is used to explainnanosecond ablation, and a possible non-thermal mechanism is proposed toexplain preferential ablation of Zn and Cu from brass samples duringpicosecond ablation.

  6. Extreme Light Laser: Analyzing the texture of matter from the atom to vacuum

    NASA Astrophysics Data System (ADS)

    Mourou, Gérard A.

    2010-03-01

    On the eve of the laser's fiftieth anniversary, we cannot but marvel at the astounding progress accomplished since the first laser shot rang in the Hughes Research Laboratory May 1960. The range of the laser applications is stupefying. At one extreme, It can be used to slow down the atoms to almost a complete stop in order to investigate its structure with meticulousness or make, ultra accurate clocks. At the other extreme, laser light can provide enormous electric fields capable of accelerating electrons from rest to close to the speed of light over only a fraction of a micrometer in a femtosecond, leading to extremely compact laser accelerator for material science, medical and environment applications. In the near future, the laser will produce pulses with peak power in the exawatt regime or hundred thousand times the world grid power during few femtoseconds. This laser called ELI for Extreme Light Infrastructure, is being designed and constructed in Europe. It will produce bursts of High energy particles and radiations in the attosecond and zeptosecond range and will be the gateway of a new laser-matter interaction r'egime : the ultra relativistic regime where not only electrons but ions are thrust to relativistic velocity. Finally, its intensity will be so large that it will be able to break down the vacuum into its fundamental elements and hence offering a new paradigm to analyze the texture of vacuum.

  7. 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.

  8. 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.

  9. The effects of He addition on the performance of the fission-fragment excited Ar/Xe atomic xenon laser

    E-print Network

    Kushner, Mark

    The effects of He addition on the performance of the fission-fragment excited Ar/Xe atomic xenon September 1990; accepted for publication 8 November 1990) The intrinsic power efficiency of the atomic xenon of a fission-fragment excited atomic xenon laser. Adding He increases the heat capacity without appreciably

  10. Continuous-wave laser oscillation on the 1315 nm transition of atomic iodine pumped by O2,,a1

    E-print Network

    Kushner, Mark

    Continuous-wave laser oscillation on the 1315 nm transition of atomic iodine pumped by O2,,a11/2 I 2 P3/2 transition of atomic iodine is conventionally obtained by a near-resonant energy nm transition of atomic iodine where the O2 a1 used to pump the iodine was produced by a radio

  11. Time-resolved diffraction profiles and atomic dynamics in short-pulse laser-induced structural transformations: Molecular dynamics study

    E-print Network

    Zhigilei, Leonid V.

    Time-resolved diffraction profiles and atomic dynamics in short-pulse laser-induced structural on the atomic-level structural rearrangements available from the simulations to the diffraction spectra measured of the irradiated surface and provides limited direct information on atomic structural rearrangements. Recent

  12. Non-neutral ion plasmas and crystals, laser cooling, and atomic clocks* J. J. Bollinger+ and D. J. Wineland

    E-print Network

    California at San Diego, University of

    Non-neutral ion plasmas and crystals, laser cooling, and atomic clocks* J. J. Bollinger+ and D. J the plasma angular momentum, changes the plasma density. Atomic clocks are an important application of ion could potentially lead to a new generation of atomic clocks.3" are no free electrons to recombine

  13. Collective Atomic Recoil Laser as a synchronization transition

    E-print Network

    J. Javaloyes; M. Perrin; A. Politi

    2007-12-11

    We consider here a model previously introduced to describe the collective behavior of an ensemble of cold atoms interacting with a coherent electromagnetic field. The atomic motion along the self-generated spatially-periodic force field can be interpreted as the rotation of a phase oscillator. This suggests a relationship with synchronization transitions occurring in globally coupled rotators. In fact, we show that whenever the field dynamics can be adiabatically eliminated, the model reduces to a self-consistent equation for the probability distribution of the atomic "phases". In this limit, there exists a formal equivalence with the Kuramoto model, though with important differences in the self-consistency conditions. Depending on the field-cavity detuning, we show that the onset of synchronized behavior may occur through either a first- or second-order phase transition. Furthermore, we find a secondary threshold, above which a periodic self-pulsing regime sets in, that is immediately followed by the unlocking of the forward-field frequency. At yet higher, but still experimentally meaningful, input intensities, irregular, chaotic oscillations may eventually appear. Finally, we derive a simpler model, involving only five scalar variables, which is able to reproduce the entire phenomenology exhibited by the original model.

  14. 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 15°C to 35°C. 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

  15. 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.

  16. 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.

  17. Laser Desorption/Ionization of Transition Metal Atoms and Oxides from Solid Argon Lester Andrews,*, Andreas Rohrbacher, Christopher M. Laperle, and Robert E. Continetti

    E-print Network

    Continetti, Robert E.

    Laser Desorption/Ionization of Transition Metal Atoms and Oxides from Solid Argon Lester Andrews of the laser-ablated metal atoms and O2 in excess argon during condensation at 10 K, have been laser desorbed of organic acid typically used as a matrix in matrix- assisted laser desorption/ionization (MALDI) mass

  18. Atomic inner-shell laser at 1.5-ångström 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 ångström-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 ångströms. 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.

  19. 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.

  20. 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.

  1. 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)

  2. Theory and experiment on laser-enabled inner-valence Auger decay of rare-gas atoms

    SciTech Connect

    Tong, X. M.; Ranitovic, P.; Hogle, C. W.; Murnane, M. M.; Kapteyn, H. C.; Toshima, N.

    2011-07-15

    In rare-gas atoms, an inner-valence shell ns hole cannot be filled by Auger decay because of an energy deficiency. We show theoretically and experimentally that by adding a moderately intense infrared laser, Auger decay is possible with decay rates increasing dramatically for laser intensities {>=}10{sup 13} W/cm{sup 2}. For Xe atoms, the simulated laser-enabled Auger decay yields are comparable with the experimental one, while for Ar atoms, the simulated ones are much smaller. We attribute the discrepancies to screening effects of the photoelectron. Laser-enabled Auger decay is of fundamental importance for understanding attosecond science, and is also important for experimental applications in ultrafast atomic, molecular, and materials dynamics using x rays. More importantly it may provide a way to control the Auger decay time and selectively break chemical bonds of molecules using a control infrared laser field.

  3. No sodium in the vapour plumes of Enceladus Nicholas M. Schneider1

    E-print Network

    Brown, Michael E.

    LETTERS No sodium in the vapour plumes of Enceladus Nicholas M. Schneider1 , Matthew H. Burger2 be ice warmed, melted or crushed by tectonic motions4 . Sodium chloride (that is, salt) is expected search for atomic sodium near Enceladus that places an upper limit on the mixing ratio in the vapour

  4. Non-exponential tunneling ionization of atoms by an intense laser field

    NASA Astrophysics Data System (ADS)

    Ishkhanyan, A. M.; Krainov, V. P.

    2015-04-01

    We discuss the possibility of non-exponential tunneling ionization of atoms irradiated by intense laser field. This effect can occur at times which are greater than the lifetime of a system under consideration. The mechanism for non-exponential depletion of an initial quasi-stationary state is the cutting of the energy spectrum of final continuous states at long times. We first consider the known examples of cold emission of electrons from metal, tunneling alpha-decay of atomic nuclei, spontaneous decay in two-level systems, and the single-photon atomic ionization by a weak electromagnetic field. The new physical situation discussed is tunneling ionization of atoms by a strong low-frequency electromagnetic field. In this case the decay obeys ?1/t power-law dependence on the (long) interaction times.

  5. 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.

  6. 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.

  7. 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.

  8. 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.

  9. Laser Irradiated Enhancement of the Atomic Electron Capture Rate in search of New Physics

    E-print Network

    Takaaki Nomura; Joe Sato; Takashi Shimomura

    2007-06-16

    Electron capture processes are important in the search for new physics. In this context, a high capture rate is desired. We investigate the possibility of enhancing the electron capture rate by irradiating laser beam to ''atom''. The possibility of such enhancement can be understood as a consequence of an enhancement of the electron wave function at the origin, $\\Psi (0)$, through an increased effective mass of the electron. We find that an order of magnitude enhancement can be realized by using a laser with intensity on the order of $10^{10}$ W/mm$^2$ and a photon energy on the order of $10^{-3}$ eV.

  10. Pulsed Sisyphus scheme for laser cooling of atomic (anti)hydrogen.

    PubMed

    Wu, Saijun; Brown, Roger C; Phillips, William D; Porto, J V

    2011-05-27

    We propose a laser cooling technique in which atoms are selectively excited to a dressed metastable state whose light shift and decay rate are spatially correlated for Sisyphus cooling. The case of cooling magnetically trapped (anti)hydrogen with the 1S-2S-3P transitions by using pulsed ultraviolet and continuous-wave visible lasers is numerically simulated. We find a number of appealing features including rapid three-dimensional cooling from ?1 K to recoil-limited, millikelvin temperatures, as well as suppressed spin-flip loss and manageable photoionization loss. PMID:21699293

  11. High-power Ti:sapphire lasers for spectroscopy of antiprotonic atoms and radioactive ions

    NASA Astrophysics Data System (ADS)

    Hori, M.; Dax, A.; Soter, A.

    2012-12-01

    The ASACUSA collaboration has developed injection-seeded Ti:sapphire lasers of linewidth ?pl ˜ 6 MHz, pulse energy 50-100 mJ, and output wavelength ? = 726-941 nm. They are being used in two-photon spectroscopy experiments of antiprotonic helium atoms at the Antiproton Decelerator (AD) of CERN. Ti:sapphire lasers of larger linewidth ?pl ˜ 100 MHz but more robust design will also be used in collinear resonance ionization spectroscopy (CRIS) experiments of neutron-deficient francium ions at the ISOLDE facility.

  12. High-power Ti:sapphire lasers for spectroscopy of antiprotonic atoms and radioactive ions

    NASA Astrophysics Data System (ADS)

    Hori, M.; Dax, A.; Soter, A.

    The ASACUSA collaboration has developed injection-seeded Ti:sapphire lasers of linewidth ?pl ˜ 6 MHz, pulse energy 50-100 mJ, and output wavelength ? = 726-941 nm. They are being used in two-photon spectroscopy experiments of antiprotonic helium atoms at the Antiproton Decelerator (AD) of CERN. Ti:sapphire lasers of larger linewidth ?pl ˜ 100 MHz but more robust design will also be used in collinear resonance ionization spectroscopy (CRIS) experiments of neutron-deficient francium ions at the ISOLDE facility.

  13. 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.

  14. Laser frequency stabilization using Zeeman effect

    NASA Astrophysics Data System (ADS)

    Chéron, 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 décrivons une nouvelle méthode, facile à mettre en oeuvre pour asservir la longueur d'onde d'un laser sur une raie atomique. Cette méthode basée sur l'effet Zeeman, met en jeu le dichroïsme circulaire présenté par une vapeur d'atomes soumise à un champ magnétique. Elle est appliquée à la stabilisation de la fréquence d'un laser LNA monomode sur la transition (2 ^3S1-2 ^3P0) de l'hélium.

  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. Multi-element analysis by ArF laser excited atomic fluorescence of laser ablated plumes: Mechanism and applications

    NASA Astrophysics Data System (ADS)

    Cai, Yue; Chu, Po-Chun; Ho, Sut Kam; Cheung, Nai-Ho

    2012-12-01

    A new multi-element analysis technique based on laser-excited atomic fluorescence was reviewed. However, the one-wavelength-one-transition constraint was overcome. Numerous elements were induced to fluoresce at a single excitation wavelength of 193 nm. This was possible provided that the analytes were imbedded in dense plumes, such as those produced by pulsed laser ablation. The underlying mechanism of the technique was explained and corroborated. Analytical applications to metals, plastics, ceramics and their composites were discribed. Detection limits in the ng/g range and mass limits of atto moles were demonstrated. Several real-world problems, including the analysis of paint coating for trace lead, the non-destructive analysis of potteries and ink, the chemical profiling of electrode-plastic interfaces, and the analysis of ingestible lead colloids were discussed.

  17. 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.

  18. Laser excited atomic and ionic fluorescence of metal vapors in the inductively coupled plasma

    NASA Astrophysics Data System (ADS)

    Ng, Kin C.; Simeonsson, Josef B.; Winefordner, James D.

    The analytical performance of laser excited fluorescence of atoms (Au, Ag, Pd, Pt, Cu, In, Pb, Ru) and ions (Sc, Ce, Dy, Eu, Gd, Sm, Er, W, Cr) in the inductively coupled plasma (ICP) is presented. The detection limits ranged from 0.2 ng/mL for Sc to 364 ng/mL for W. It is concluded that laser excited atomic fluorescence in the ICP is a highly element-selective technique, which provides comparable detection limits to the ICP-AES. This element specific technique is based on the double resonance approach. The linear dynamic range of LEAF-ICP is at least equal to that of ICP-AES, that is between 10 exp 4 and 10 exp 7.

  19. Analysis of an atom laser based on the spatial control of the scattering length

    SciTech Connect

    Carpentier, Alicia V.; Michinel, Humberto; Rodas-Verde, Maria I.; Perez-Garcia, Victor M.

    2006-07-15

    In this paper we analyze atom lasers based on the spatial modulation of the scattering length of a Bose-Einstein condensate. We demonstrate, through numerical simulations and approximate analytical methods, the controllable emission of matter-wave bursts and study the dependence of the process on the spatial shape of the scattering length along the axis of emission. We also study the role of an additional modulation of the scattering length in time.

  20. Vectorial atomic magnetometer based on coherent transients of laser absorption in Rb vapor

    E-print Network

    Lenci, L; Barreiro, S; Valente, P; Lezama, A; Failache, H

    2014-01-01

    We have designed and tested an atomic vectorial magnetometer based on the analysis of the coherent oscillatory transients in the transmission of resonant laser light through a Rb vapor cell. We show that the oscillation amplitudes at the Larmor frequency and its first harmonic are related through a simple formula to the angles determining the orientation of the magnetic field vector. The magnetometer was successfully applied to the measurement of the ambient magnetic field.

  1. Towards the measurement of the electron EDM with laser cooled francium atoms

    NASA Astrophysics Data System (ADS)

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

    2014-09-01

    The electric dipole moment (EDM) of a particle is a probe into new physics beyond the standard model. The electron EDM might be observed with an enhancement in heavier paramagnetic atoms. Francium (Fr), whose electron structure is useful for laser-cooling and trapping, has a large enhancement factor. Fr produced at high temperature via a fusion reaction will be laser-cooled and trapped in an optical lattice where the EDM is measured. The magneto-optical trapping of Fr is required in advance of the lattice trapping. The technique observing a small number of atoms makes it easy to search for the resonant frequency of Fr. The improvement of the beam purity should lead to a more efficient trap. The techniques towards Fr trapping and EDM measurement have been developed. The electric dipole moment (EDM) of a particle is a probe into new physics beyond the standard model. The electron EDM might be observed with an enhancement in heavier paramagnetic atoms. Francium (Fr), whose electron structure is useful for laser-cooling and trapping, has a large enhancement factor. Fr produced at high temperature via a fusion reaction will be laser-cooled and trapped in an optical lattice where the EDM is measured. The magneto-optical trapping of Fr is required in advance of the lattice trapping. The technique observing a small number of atoms makes it easy to search for the resonant frequency of Fr. The improvement of the beam purity should lead to a more efficient trap. The techniques towards Fr trapping and EDM measurement have been developed. Supported by MEXT/JSPS KAKENHI Grants (21104005, 25610112 and 26220705) and Tohoku University's Focused Research Project.

  2. Atomic collisions in the presence of laser radiation - Time dependence and the asymptotic wave function

    NASA Technical Reports Server (NTRS)

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

    1982-01-01

    A time-dependent, wave-packet description of atomic collisions in the presence of laser radiation is extracted from the more conventional time-independent, stationary-state description. This approach resolves certain difficulties of interpretation in the time-independent approach which arise in the case of asymptotic near resonance. In the two-state model investigated, the approach predicts the existence of three spherically scattered waves in this asymptotically near-resonant case.

  3. 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.

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

    NASA Astrophysics Data System (ADS)

    Götz, T.; Bergt, M.; Hoheisel, W.; Träger, 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=0.16±0.02 eV. For ?=355 nm the non-thermal distribution is even bimodal with maxima appearing at E kin=0.16±0.02 and 0.33±0.02 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.

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

    E-print Network

    Suárez, Noslen; Ciappina, Marcelo; Biegert, Jens; Lewenstein, Maciej

    2015-01-01

    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 re-scattering transition amplitudes in atoms. From a non-local, but separable potential, the bound-free dipole and the re-scattering transition matrix elements are analytically computed. In comparison with the standard approaches to the ATI process, our analytical derivation of the re-scattering matrix elements allows us to study directly how the re-scattering 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 ...

  6. 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.

  7. Velocity selective bi-polarization spectroscopy for laser cooling of metastable Krypton atoms

    E-print Network

    Kale, Y B; Singh, S; Mishra, S R; Rawat, H S

    2014-01-01

    We report a velocity selective bi-polarization spectroscopy (VS-BPS) technique to generate a background-free, dispersion-like reference signal which is tunable over a wide range of frequency. In this technique, a pair of linearly polarized weak probe beams passing through a gas cell of metastable Krypton (Kr*) atoms, overlaps with a pair of counter-propagating circularly polarized strong pump beams derived from an independently tunable control laser. The polarization spectroscopy signals from the two probe beams, after subtraction, result in VS-BPS signal. The spectral shifting in VS-BPS signal can be achieved by tuning the frequency of the control laser. The dependence of the amplitude and slope of the VS-BPS signal on the RF power used for excitation of Kr atoms in the gas cell and on the power of pump beams has been studied. The frequency stability of a diode laser locked with VS-BPS signal has been found to be better than the frequency stability of the laser locked with a saturated absorption spectroscopy...

  8. Laser cooling of neutral atoms. Final report, 22 July 1983-30 September 1988

    SciTech Connect

    Metcalf, H.

    1989-10-01

    A new cooling process was discovered that uses an applied magnetic field to mix differentially light-shifted atomic-ground-state sublevels. It seems to be another form of the polarization scrambling molasses that was appropriate for the ultra-cold measurements on the three-dimensional Na molasses at the NBS last year, except that this is a one-dimensional (or perhaps two-dimensional) version. Optical collimation experiments were performed in two dimensions to make a very intense beam of atoms. Measuring a beam profile in two dimensions would require two hot wires scanning in perpendicular directions, and any asymmetry in the line shape could produce ambiguity. It is therefore very desirable to have a neutral atom imaging device. Diode Laser Experiments; High Vacuum System for trap and Molasses; magnetic Trapping of Neutral Atoms; Trapping Metastable Helium; the earliest experiments on optical pumping of helium there has been interest in generating light to excite the first resonance transition from the metastable 2 3S1 state to the 2/3P(O,1,2) states (lifetime tau approx 95 nsec). For 25 years these experiments were done with light from resonance lamps, but the advent of LNA in 1985 provided the opportunity for laser excitation of this important transition.

  9. 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.

  10. 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.

  11. Theoretical modeling of laser-induced plasmas using the ATOMIC code

    NASA Astrophysics Data System (ADS)

    Colgan, James; Johns, Heather; Kilcrease, David; Judge, Elizabeth; Barefield, James, II; Clegg, Samuel; Hartig, Kyle

    2014-10-01

    We report on efforts to model the emission spectra generated from laser-induced breakdown spectroscopy (LIBS). LIBS is a popular and powerful method of quickly and accurately characterizing unknown samples in a remote manner. In particular, LIBS is utilized by the ChemCam instrument on the Mars Science Laboratory. We model the LIBS plasma using the Los Alamos suite of atomic physics codes. Since LIBS plasmas generally have temperatures of somewhere between 3000 K and 12000 K, the emission spectra typically result from the neutral and singly ionized stages of the target atoms. We use the Los Alamos atomic structure and collision codes to generate sets of atomic data and use the plasma kinetics code ATOMIC to perform LTE or non-LTE calculations that generate level populations and an emission spectrum for the element of interest. In this presentation we compare the emission spectrum from ATOMIC with an Fe LIBS laboratory-generated plasma as well as spectra from the ChemCam instrument. We also discuss various physics aspects of the modeling of LIBS plasmas that are necessary for accurate characterization of the plasma, such as multi-element target composition effects, radiation transport effects, and accurate line shape treatments. The Los Alamos National Laboratory is operated by Los Alamos National Security, LLC for the National Nuclear Security Administration of the U.S. Department of Energy under Contract No. DE-AC5206NA25396.

  12. Laser excited atomic and ionic fluorescence in an inductively coupled plasma

    NASA Astrophysics Data System (ADS)

    Uchida, H.; Kosinski, M. A.; Winefordner, J. D.

    The characteristics of atomic and ionic fluorescence excited by a pulsed dye laser in an inductively coupled plasma (ICP) and their application to plasma diagnostics have been investigated. The vertical distributions of atomic and ionic fluorescence for calcium and yttrium are directly obtained in the central region without the need of an Abel inversion procedure. Thermally assisted fluorescence intensities are found not to be in a Boltz mann distribution, despite the good linearity shown for the emission plot at the same wavelengths. The usefulness of the ICP as an atomization or ionization cell in fluorescence spectrometry is also discussed. However. fluorescence detection limits in the analytical region of the plasma are about two orders poorer than those for emission

  13. Diffraction electron-atom scattering in an intense low-frequency laser field

    SciTech Connect

    Jaron, A.; Kaminski, J.Z.

    1997-12-01

    An explanation of discrepancies between predictions of the Kroll-Watson theory and cross sections measured in the Wallbank-Holmes experiments on electron-atom scattering in the presence of a powerful low-frequency laser field is presented. Our model calculations for helium and argon as target atoms come out to be in good agreement with experimental results; i.e., obtained cross sections are by many orders of magnitude larger than those predicted by the Kroll-Watson theory. A mechanism responsible for such a substantial increase of the calculated cross sections is found to be due to the diffraction scattering of electrons by atomic obstacles. {copyright} {ital 1997} {ital The American Physical Society}

  14. 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…

  15. Single-Atom Laser From McGraw-Hill Yearbook of Science & Technology (McGraw-Hill, New York, 2001).

    E-print Network

    Fang-Yen, Christopher

    1 Single-Atom Laser From McGraw-Hill Yearbook of Science & Technology (McGraw-Hill, New York-Field Lasers, Korea Advanced Institute of Science and Technology, Taejon. Korea Aljalal, Abdulaziz G. R of Technology, Cambridge. Yu, Chung-Chieh G.R. Harrison Spectroscopy Laboratory, Massachusetts Institute

  16. Diode-laser-based atomic absorption monitor using frequency-modulation spectroscopy for physical vapor deposition process control

    E-print Network

    Fejer, Martin M.

    have limited utility in these applications be- cause they are spatially incoherent and have lowDiode-laser-based atomic absorption monitor using frequency-modulation spectroscopy for physical cavity diode laser. FM detection made it possible to measure absorption as low as 10 6 . For electron

  17. 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.

  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. Atomic force microscopy visualization of injuries in Enterococcus faecalis surface caused by Er,Cr:YSGG and diode lasers

    PubMed Central

    López-Jiménez, Lidia; Viñas, Miguel; Vinuesa, Teresa

    2015-01-01

    Aim: To visualize by Atomic Force Microscopy the alterations induced on Enterococcus. faecalis surface after treatment with 2 types of laser: Erbium chromium:yttrium-scandium-gallium-garnet (Er,Cr:YSGG) laser and Diode laser. Material and Methods: Bacterial suspensions from overnight cultures of E. faecalis were irradiated during 30 seconds with the laser-lights at 1 W and 2 W of power, leaving one untreated sample as control. Surface alterations on treated E. faecalis were visualized by Atomic Force Microscopy (AFM) and its surface roughness determined. Results: AFM imaging showed that at high potency of laser both cell morphology and surface roughness resulted altered, and that several cell lysis signs were easily visualized. Surface roughness clearly increase after the treatment with Er,Cr:YSGG at 2W of power, while the other treatments gave similar values of surface roughness. The effect of lasers on bacterial surfaces visualized by AFM revealed drastic alterations. Conclusions: AFM is a good tool to evaluate surface injuries after laser treatment; and could constitute a measure of antimicrobial effect that can complete data obtained by determination of microbial viability. Key words:Atomic force microscopy, Er,Cr:YSGG laser, diode laser, Enterococcus faecalis, surface roughness. PMID:25475770

  1. 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.

  2. 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.

  3. Tunable frequency-stabilised laser for studying the cooling dynamics of Rb atoms in a magnetooptical trap

    SciTech Connect

    Yarovitsky, Alexander V; Vasil'ev, V V; Velichansky, Vladimir L; Razin, Oleg A; Sherstov, Ivan V; Prudnikov, O N; Taichenachev, Aleksei V; Yudin, Valerii I

    2004-04-30

    A system is developed which allows one to stabilise the diode laser frequency at any point in the vicinity of the cyclic D{sub 2}-line transition in Rb in the interval from +40 to -150 MHz and to switch the laser frequency within this interval for {approx}1 ms. A method is proposed and realised for increasing the contrast of the reference sub-Doppler resonance observed in circularly polarised fields. The ultimate contrast of the resonance is estimated. This system can be used to study the anomalous light pressure force acting on atoms in an optical molasses. A magnetooptical trap for Rb atoms is described. (control of laser radiation parameters)

  4. High-Precision Measurement of the Laser-Trapping Frequencies for $^{209,210,211}$Fr Atoms

    E-print Network

    Sanguinetti, S; Corradi, L; Dainelli, A; Khanbekyan, A; Mariotti, E; de Mauro, C; Minguzzi, P; Moi, L; Stancari, G; Tomassetti, L; Veronesi, S

    2008-01-01

    We present the accurate measurement of the frequency of the $7S-7P$ laser-trapping transition for three francium isotopes. Our approach is based on an interferometric comparison to deduce the unknown laser frequency from a secondary laser frequency-standard. After careful investigation of systematics, with samples of about 100 atoms the final accuracy reaches 8 MHz, an order of magnitude better than the best previous measurement for $^{210}$Fr, and opens the way to improved tests of the theoretical computation of Fr atomic structure.

  5. Atomic inner-shell laser at 1.5-ångström 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 ångström-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 ångströms. 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

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

    E-print Network

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

    2015-01-01

    The problem of deep laser cooling of $^{24}$Mg atoms is theoretically studied. We propose two-stage sub-Doppler cooling strategy using electro-dipole transition $3^3P_2$$\\to$$3^3D_3$ ($\\lambda$=383.9 nm). The first stage implies exploiting magneto-optical trap with $\\sigma^+$ and $\\sigma^-$ light beams, while the second one uses a lin$\\perp$lin molasses. We focus on achieving large number of ultracold atoms (T$_{eff}$ < 10 $\\mu$K) in a cold atomic cloud. The calculations have been done out of many widely used approximations and based on quantum treatment with taking full account of recoil effect. Steady-state average kinetic energies and linear momentum distributions of cold atoms are analysed for various light-field intensities and frequency detunings. The results of conducted quantum analysis have revealed noticeable differences from results of semiclassical approach based on the Fokker-Planck equation. At certain conditions the second cooling stage can provide sufficiently lower kinetic energies of atom...

  7. Nonlinear spectroscopy of Sr atoms in an optical cavity for laser stabilization

    NASA Astrophysics Data System (ADS)

    Christensen, Bjarke T. R.; Henriksen, Martin R.; Schäffer, 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 quadratures—the cavity transmitted phase and absorption—by 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.

  8. 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 Schrödinger 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.

  9. Application of Coulomb wave function discrete variable representation to atomic systems in strong laser fields.

    PubMed

    Peng, Liang-You; Starace, Anthony F

    2006-10-21

    We present an efficient and accurate grid method for solving the time-dependent Schrodinger 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. PMID:17059259

  10. 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.

  11. 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.

  12. Laser-induced reversion of $\\delta^{'}$ precipitates in an Al-Li alloy: Study on temperature rise in pulsed laser atom probe

    E-print Network

    Khushaim, Muna; Al-Kassab, Talaat

    2015-01-01

    The influence of tuning the laser energy during the analyses on the resulting microstructure in a specimen utilizing an ultra-fast laser assisted atom probe was demonstrated by a case study of a binary Al-Li alloy. The decomposition parameters, such as the size, number density, volume fraction and composition of $\\delta^{'}$ precipitates, were carefully monitored after each analysis. A simple model was employed to estimate the corresponding specimen temperature for each value of the laser energy. The results indicated that the corresponding temperatures for the laser energy in the range of 10 to 80 pJ are located inside the miscibility gap of the binary Al-Li phase diagram and fall into the metastable equilibrium field. In addition, the corresponding temperature for a laser energy of 100 pJ was in fairly good agreement with reported range of $\\delta^{'}$ solvus temperature, suggesting a result of reversion upon heating due to laser pulsing.

  13. Atom-probe tomography of nickel-based superalloys with green or ultraviolet lasers: a comparative study.

    PubMed

    Amouyal, Yaron; Seidman, David N

    2012-10-01

    Recent developments in the technology of laser-pulsed local-electrode atom-probe (LEAP) tomography include a picosecond ultraviolet (UV) laser system having a 355 nm wavelength and both external and in-vacuum optics. This approach ensures focusing of the laser beam to a smaller spot diameter than has heretofore been obtained using a green (532 nm wavelength) picosecond laser. We compare the mass spectra acquired, using either green or UV laser pulsing, from nickel-based superalloy specimens prepared either electrochemically or by lifting-out from bulk material using ion-beam milling in a dual-beam focused ion beam microscope. The utilization of picosecond UV laser pulsing yields improved mass spectra, which manifests itself in higher signal-to-noise ratios and mass-resolving power (m/?m) in comparison to green laser pulsing. We employ LEAP tomography to investigate the formation of misoriented defects in nickel-based superalloys and demonstrate that UV laser pulsing yields better accuracy in compositional quantification than does green laser pulsing. Furthermore, we show that using a green laser the quality of mass spectra collected from specimens that were lifted-out by ion milling is usually poorer than for electrochemically-sharpened specimens. Employing UV laser pulsing yields, however, improved mass spectra in comparison to green laser pulsing even for ion-milled microtips. PMID:23046701

  14. 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 Schrödinger 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.

  15. 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.

  16. Arc Jet Flow Properties Determined from Laser-Induced Fluorescence of Atomic Nitrogen

    NASA Technical Reports Server (NTRS)

    Fletcher, Douglas; Wercinski, Paul F. (Technical Monitor)

    1998-01-01

    An laser-spectroscopic investigation of the thermocheMical state of arcjet flows is currently being conducted in the Aerodynamic Heating Facility (AHF) Circlet at NASA Ames Research Center. Downstream of the nozzle exit, but upstream of the test article, Laser-Induced Fluorescence (LIF) of atomic nitrogen is used to assess the nonequilibriuM distribution of flow enthalpy in the free stream. The two-photon LIF technique provides simultaneous measurements of free stream velocity, translational temperature, and nitrogen number density on the flow centerline. Along with information from facility instrumentation, these measurements allow a determination of the free stream total enthalpy, and its apportionment in to thermal, kinetic, and chemical mode contributions. Experimental results are presented and discussed for two different niti-ogen/argon test gas flow runs during which the current is varied while the pressure remains constant .

  17. 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

  18. 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.

  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. 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.

  1. Al-free active region laser diodes at 894 nm for compact Cesium atomic clocks

    NASA Astrophysics Data System (ADS)

    Von Bandel, N.; Bébé Manga Lobé, 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/cm², for 2mm lasers at 20°C.

  2. MOTIS: A Focused Ion Beam Source Based On Laser-Cooled Atoms

    NASA Astrophysics Data System (ADS)

    Knuffman, B.; Steele, A. V.; Orloff, J.; Maazouz, M.; McClelland, J. J.

    2011-11-01

    We have demonstrated high resolution focused ion beams based on a magneto-optical trap ion source (MOTIS), which takes advantage of the ultra cold temperatures of laser cooled atoms to produce high brightness, low emittance ion beams. We have created focused beams of both Cr+ and Li+ and present secondary electron micrographs obtained with these beams, demonstrating a focal spot size as low as 27 nm at a beam energy of 2 keV. This work shows that the MOTIS can be a useful source for focused ion beams that will open new opportunities for applications in materials characterization and metrology.

  3. Isotope effects in the harmonic response from hydrogenlike muonic atoms in strong laser fields

    SciTech Connect

    Shahbaz, Atif; Mueller, Carsten; Buervenich, Thomas J.

    2010-07-15

    High-order harmonic generation from hydrogenlike muonic atoms exposed to ultraintense high-frequency laser fields is studied. Systems of low nuclear-charge number Z are considered where a nonrelativistic description applies. By comparing the radiative response for different isotopes, we demonstrate characteristic signatures of the finite nuclear mass and size in the harmonic spectra. In particular, for Z>1, an effective muon charge appears in the Schroedinger equation for the relative particle motion, which influences the position of the harmonic cutoff. Cutoff energies in the million-electron-volt domain can be achieved, offering prospects for the generation of ultrashort coherent {gamma}-ray pulses.

  4. 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.

  5. 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.

  6. Sub-doppler laser cooling of thulium atoms in a magneto-optical trap

    NASA Astrophysics Data System (ADS)

    Sukachev, D.; Sokolov, A.; Chebakov, K.; Akimov, A.; Kolachevsky, N.; Sorokin, V.

    2010-11-01

    Sub-Doppler laser cooling in a magneto-optical trap for thulium atoms at a wavelength of 410.6 nm has been experimentally studied. Without any dedicated molasses period of sub-Doppler cooling, the cloud of 3 × 106 atoms at a temperature of 25(5) ?K was observed. The measured temperature is significantly lower than the Doppler limit of 240 ?K for the cooling transition at 410.6 nm. The high efficiency of the sub-Doppler cooling process is due to a near-degeneracy of the Landé g-factors of the lower 4 f 136 s 2 ( J = 7/2) and the upper 4 f 125 d 3/26 s 2 ( J = 9/2) cooling levels.

  7. 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.

  8. 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.

  9. Quantum interference in attosecond transient absorption of laser-dressed helium atoms

    E-print Network

    Shaohao Chen; Mengxi Wu; Mette B. Gaarde; Kenneth J. Schafer

    2013-01-04

    We calculate the transient absorption of an isolated attosecond pulse by helium atoms subject to a delayed infrared (\\ir) laser pulse. With the central frequency of the broad attosecond spectrum near the ionization threshold, the absorption spectrum is strongly modulated at the sub-\\ir-cycle level. Given that the absorption spectrum results from a time-integrated measurement, we investigate the extent to which the delay-dependence of the absorption yields information about the attosecond dynamics of the atom-field energy exchange. We find two configurations in which this is possible. The first involves multi photon transitions between bound states that result in interference between different excitation pathways. The other involves the modification of the bound state absorption lines by the IR field, which we find can result in a sub-cycle time dependence only when ionization limits the duration of the strong field interaction.

  10. 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.

  11. Sub-Doppler Laser Cooling of Thulium Atoms in a Magneto-optical Trap

    E-print Network

    Sukachev, D; Chebakov, K; Akimov, A; Kanorsky, S; Kolachevsky, N; Sorokin, V

    2010-01-01

    We have experimentally studied sub-Doppler laser cooling in a magneto-optical trap for thulium atoms working at the wavelength of 410.6\\,nm. Without any dedicated molasses period of sub-Doppler cooling, the cloud of $3\\times 10^6$ atoms at the temperature of 25(5)\\,$\\mu$K was observed. The measured temperature is significantly lower than the Doppler limit of 240$\\mu$K for the cooling transition at 410.6\\,nm. High efficiency of the sub-Doppler cooling process is due to a near-degeneracy of the Land\\'e-$g$ factors of the lower $4f^{13}6s^{2}\\, (J\\,=\\,{7}/{2})$ and the upper $4f^{12}5d_{3/2}6s^{2}\\, (J\\,=\\,{9}/{2})$ cooling levels.}

  12. Sub-Doppler Laser Cooling of Thulium Atoms in a Magneto-optical Trap

    E-print Network

    D. Sukachev; A. Sokolov; K. Chebakov; A. Akimov; S. Kanorsky; N. Kolachevsky; V. Sorokin

    2010-12-24

    We have experimentally studied sub-Doppler laser cooling in a magneto-optical trap for thulium atoms working at the wavelength of 410.6\\,nm. Without any dedicated molasses period of sub-Doppler cooling, the cloud of $3\\times 10^6$ atoms at the temperature of 25(5)\\,$\\mu$K was observed. The measured temperature is significantly lower than the Doppler limit of 240$\\mu$K for the cooling transition at 410.6\\,nm. High efficiency of the sub-Doppler cooling process is due to a near-degeneracy of the Land\\'e-$g$ factors of the lower $4f^{13}6s^{2}\\, (J\\,=\\,{7}/{2})$ and the upper $4f^{12}5d_{3/2}6s^{2}\\, (J\\,=\\,{9}/{2})$ cooling levels.}

  13. Comparison of Gaussian and super Gaussian laser beams for addressing atomic qubits

    E-print Network

    Gillen-Christandl, Katharina; Piotrowicz, M J; Saffman, M

    2015-01-01

    We study the fidelity of single qubit quantum gates performed with two-frequency laser fields that have a Gaussian or super Gaussian spatial mode. Numerical simulations are used to account for imperfections arising from atomic motion in an optical trap, spatially varying Stark shifts of the trapping and control beams, and transverse and axial misalignment of the control beams. Numerical results that account for the three dimensional distribution of control light show that a super Gaussian mode with intensity $I\\sim e^{-2(r/w_0)^n}$ provides reduced sensitivity to atomic motion and beam misalignment. Choosing a super Gaussian with $n=6$ the decay time of finite temperature Rabi oscillations can be increased by a factor of 60 compared to an $n=2$ Gaussian beam, while reducing crosstalk to neighboring qubit sites.

  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. 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

  16. 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.

  17. 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.

  18. Laser sustained discharge nozzle apparatus for the production of an intense beam of high kinetic energy atomic species

    DOEpatents

    Cross, Jon B. (Santa Fe, NM); Cremers, David A. (Los Alamos, NM)

    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.

  19. 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.

  20. EFFECTS OF MULTI-ELECTRON CORRELATION ON MULTIPHOTON IONIZATION AND HIGH-ORDER HARMONIC GENERATION OF ATOMIC AND MOLECULAR SYSTEMS IN INTENSE ULTRASHORT LASER FIELDS

    E-print Network

    Heslar, John

    2009-05-07

    . To advance this strong-field atomic and molecular physics, this dissertation aims at the developing new theoretical formalisms and accurate computational methods for ab initio non-perturbative studies of atomic and molecular processes in intense laser fields...

  1. 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.

  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. 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

  5. arXiv:0802.2601v1[cond-mat.other]19Feb2008 A quasi-monomode guided atom-laser from an all-optical Bose-Einstein condensate

    E-print Network

    Guéry-Odelin, David

    , a coherent matter wave in which many atoms occupy a single quan- tum mode. Atom lasers are orders to inertial fields [7]. Many prospects for atom lasers depend upon a high degree of control over the internalarXiv:0802.2601v1[cond-mat.other]19Feb2008 A quasi-monomode guided atom-laser from an all

  6. 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.

  7. 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 ?m), 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

  8. 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.

  9. A new approach to driving and controlling precision lasers for cold-atom science

    NASA Astrophysics Data System (ADS)

    Luey, Ben; Shugrue, Jeremy; Anderson, Mike

    2014-05-01

    Vescent's Integrated Control Electronics (ICE) Platform is a new approach to controlling and driving lasers and other electoral devices in complex atomic and optical experiments. By employing low-noise, high-bandwidth analog electronics with digital control, ICE combines the performance of analog design with the convenience of the digital world. Utilizing a simple USB COM port interface, ICE can easily be controlled via LabView, Python, or an FPGA. High-speed TTL inputs enable precise external timing or triggering. ICE is capable of generating complex timing internally, enabling ICE to drive an entire experiment or it can be directed by an external control program. The system is capable of controlling up to 8 unique ICE slave boards providing flexibility to tailor an assortment of electronics hardware to the needs of a specific experiment. Examples of ICE slave boards are: a current controller and peak-lock laser servo, a four channel temperature controller, a current controller and offset phase lock servo. A single ensemble can drive, stabilize, and frequency lock 3 lasers in addition to powering an optical amplifier, while still leaving 2 remaining slots for further control needs. Staff Scientist

  10. 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...

  11. 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.

  12. 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

  13. A new scheme of compact cold atom clock based on diffuse laser cooling in a cylindrical cavity

    E-print Network

    Liu, Peng; Wan, Jinyin; Wang, Xiumei; Wang, Yaning; Xiao, Ling; Cheng, Huadong; Liu, Liang

    2015-01-01

    We present a new scheme of compact Rubidium cold-atom clock which performs the diffuse light cooling, the microwave interrogation and the detection of the clock signal in a cylindrical microwave cavity. The diffuse light is produced by the reflection of the laser light at the inner surface of the microwave cavity. The pattern of injected laser beams is specially designed to make most of the cold atoms accumulate in the center of the microwave cavity. The microwave interrogation of cold atoms in the cavity leads to Ramsey fringes whose line-width is 24.5 Hz and the contrast of 95.6% when the free evolution time is 20 ms. The frequency stability of $7.3\\times10^{-13}\\tau^{-1/2}$ has been achieved recently. The scheme of this physical package can largely reduce the complexity of the cold atom clock, and increase the performance of the clock.

  14. Very high-order harmonic generation from Ar atoms and Ar^+ ions in super intense pulsed laser fields

    NASA Astrophysics Data System (ADS)

    Carrera, Juan J.; Tong, Xiao-Min

    2005-05-01

    We present an ab initio nonpertubative investigation of the mechanisms responsible for the production of very high-order harmonic generation (HHG) from Ar atoms and Ar^+ ions by means of the self-interaction-free time dependent density functional theory recently developed [1]. Further, by introducing an effective charge concept, we can study at which laser intensity the contribution to the high-energy HHG from Ar^+ ions precede over the Ar atoms. Comparing the HHG behavior from Ar atoms and Ar^+ ions in super intense laser field, we conclude that the high energy HHG observed in the recent experiment [2] originated from the ionized Ar atoms. [1] J.J. Carrera, S.I.Chu and X.M.Tong, Phys. Rev. A (submitted) [2] Gibson, et. al., PRL 92, 033001 (2004)

  15. Towards an Atomic Parity Violation Measurement with Laser Trapped Francium at ISAC

    NASA Astrophysics Data System (ADS)

    Collister, R.; Tandecki, M.; Gwinner, G.; Zhang, J.; Orozco, L.; Behr, J. A.; Pearson, M. R.; Gomez-Garcia, E.; Aubin, S.

    2012-10-01

    The neutral atom trap for parity violation measurements at TRIUMF has recently accepted its first radioactive beam. The longest lived francium isotopes have half-lives of minutes, requiring us to produce them with the online mass separator of the ISAC facility. The ion beam is embedded into a catcher made of yttrium foil where it is neutralized. Subsequently, the foil is rotated and heated to release a pulse of atomic francium into the laser trap cell. Francium isotopes 207, 209 and 221 have successfully been cooled and confined in a magneto-optical trap, a crucial first step for later experiments. The next online measurements are planned for November 2012 where two physics goals will be pursued. Firstly, the hyperfine anomaly will be probed via high precision spectroscopy on the atomic D1 transition in order to investigate the nuclear magnetization distribution. This will be followed by ionization cross-section measurements from the 7p3/2 state to evaluate this as a potential problematic trap loss mechanism for future parity violation measurements.

  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 Schrödinger 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. Direct measurement of laser-induced frequency shift rate of ultracold cesium molecules by analyzing losses of trapped atoms

    SciTech Connect

    Zhang Yichi; Ma Jie; Li Yuqing; Wu Jizhou; Zhang Linjie; Chen Gang; Wang Lirong; Zhao Yanting; Xiao Liantuan; Jia Suotang

    2012-09-24

    We report on a quantitative experimental determination of the laser-induced frequency shift rate of the ultracold cesium molecules formed via photoassociation (PA) by means of the trap loss measurement of the losses of trapped atoms in a standard magneto-optical trap. The experiment was directly performed by varying the photoassociation laser intensity without any additional frequency monitor technologies. Our experimental method utilized dependences of the losses on the laser-induced frequency shift rate based on the conditions of the identified photoassociation spectral shape. We demonstrated that the method is sensitive enough to determine small frequency shifts of rovibrational levels of ultracold cesium molecules.

  18. Breakdown and dc discharge in low-pressure water vapour

    NASA Astrophysics Data System (ADS)

    Sivoš, J.; Škoro, 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.

  19. 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

  20. No sodium in the vapour plumes of Enceladus

    NASA Astrophysics Data System (ADS)

    Schneider, Nicholas M.; Burger, Matthew H.; Schaller, Emily L.; Brown, Michael E.; Johnson, Robert E.; Kargel, Jeffrey S.; Dougherty, Michele K.; Achilleos, Nicholas A.

    2009-06-01

    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.

  1. 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.

  2. 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.

  3. 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 Schrödinger equation. An excellent agreement between the two computational methods is demonstrated in a wide range of the pulse durations.

  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. 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.

  6. 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.

  7. 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.

  8. 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.

  9. Coherence properties of Bose-Einstein condensates and atom lasers Wolfgang Ketterle and Hans-Joachim Miesner

    E-print Network

    Coherence properties of Bose-Einstein condensates and atom lasers Wolfgang Ketterle and Hans to the second-order spatial correlation function at zero relative position , which is a measure of the local provided clear evidence of quantum occupancies phase-space densities much larger than one which is one

  10. MOLECULARPHYSICS, 1984, VOL. 52, No. 3, 541-566 An investigation of the laser optogalvanic effect for atoms

    E-print Network

    Cohen, Ronald C.

    in recombina- tion-limited hollow cathode plasmas, with the use of dye lasers. Compara- tive studies. flames [1], positive column DC discharges [2-4], hollow cathode DC discharges [4] and radiofrequency, argon, lithium, and barium atoms, generated in commercial hollow cathode lamps, and of hydrogen

  11. A 461 nm Laser System and Hollow-Cathode Lamp Spectroscopy for Magneto-Optical Trapping of Sr Atoms

    E-print Network

    Torii, Yoshio

    A 461 nm Laser System and Hollow-Cathode Lamp Spectroscopy for Magneto-Optical Trapping of Sr Atoms absorption line, we measured the saturated absorption spectrum of a Sr hollow-cathode lamp. The dependences­Einstein condensation, quantum degenerate of mixture, strontium, frequency modulation spectroscopy, hollow-cathode lamp

  12. Continuous wave near-infrared atomic Xe laser excited by a radio frequency discharge in a slab geometry

    E-print Network

    Vellekoop, Michel

    Continuous wave near-infrared atomic Xe laser excited by a radio frequency discharge in a slab excited by a radio frequency rf discharge in a slab geometry. A maximum continuous wave cw output power­7 Until now the research in this wave- length region was concentrated mainly on the improvement of solid

  13. Spectral analysis of irregular roughness artifacts measured by atomic force microscopy and laser scanning microscopy.

    PubMed

    Chen, Yuhang; Luo, Tingting; Ma, Chengfu; Huang, Wenhao; Gao, Sitian

    2014-12-01

    Atomic force microscopy (AFM) and laser scanning microscopy (LSM) measurements on a series of specially designed roughness artifacts were performed and the results characterized by spectral analysis. As demonstrated by comparisons, both AFM and LSM can image the complex structures with high resolution and fidelity. When the surface autocorrelation length increases from 200 to 500 nm, the cumulative power spectral density spectra of the design, AFM and LSM data reach a better agreement with each other. The critical wavelength of AFM characterization is smaller than that of LSM, and the gap between the measured and designed critical wavelengths is reduced with an increase in the surface autocorrelation length. Topography measurements of surfaces with a near zero or negatively skewed height distribution were determined to be accurate. However, obvious discrepancies were found for surfaces with a positive skewness owing to more severe dilations of either the solid tip of the AFM or the laser tip of the LSM. Further surface parameter evaluation and template matching analysis verified that the main distortions in AFM measurements are tip dilations while those in LSM are generally larger and more complex. PMID:25339140

  14. 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

  15. Experimental and theoretical Auger and autoionization spectra for electron impact on laser-excited Na atoms

    NASA Astrophysics Data System (ADS)

    Dorn, A.; Zatsarinny, O.; Mehlhorn, W.

    1997-07-01

    An experimental method is described to obtain electron spectra with good resolution 0953-4075/30/13/007/img6 and high intensity following L-shell excitation or ionization of laser-excited Na atoms. We report on experimental and theoretical electron spectra in the energy range of 25 - 33 eV for laser excitation to 0953-4075/30/13/007/img7, 0953-4075/30/13/007/img8, 0953-4075/30/13/007/img9 and 0953-4075/30/13/007/img10 and for 1.5 keV electron impact. Due to the good agreement in line positions and intensities essentially all lines can be assigned. Furthermore, experimental relative cross sections for 0953-4075/30/13/007/img11 states excited from 0953-4075/30/13/007/img8, 0953-4075/30/13/007/img7 and 0953-4075/30/13/007/img14 are determined and compared with theoretical values.

  16. 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?

  17. 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)

  18. Polarization switching detection method using a ferroelectric liquid crystal for dichroic atomic vapor laser lock frequency stabilization techniques.

    PubMed

    Dudzik, Grzegorz; Rzepka, Janusz; Abramski, Krzysztof M

    2015-04-01

    We present a concept of the polarization switching detection method implemented for frequency-stabilized lasers, called the polarization switching dichroic atomic vapor laser lock (PSDAVLL) technique. It is a combination of the well-known dichroic atomic vapor laser lock method for laser frequency stabilization with a synchronous detection system based on the surface-stabilized ferroelectric liquid crystal (SSFLC).The SSFLC is a polarization switch and quarter wave-plate component. This technique provides a 9.6 dB better dynamic range ratio (DNR) than the well-known two-photodiode detection configuration known as the balanced polarimeter. This paper describes the proposed method used practically in the VCSEL laser frequency stabilization system. The applied PSDAVLL method has allowed us to obtain a frequency stability of 2.7×10?? and a reproducibility of 1.2×10??, with a DNR of detected signals of around 81 dB. It has been shown that PSDAVLL might be successfully used as a method for spectra-stable laser sources. PMID:25967193

  19. 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.

  20. 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)

  1. 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.

  2. Laser excited analytical atomic and ionic fluorescence in flames, furnaces and inductively coupled plasmas—I. General considerations

    NASA Astrophysics Data System (ADS)

    Omenetto, N.; Human, H. G. C.

    Several important parameters for the analytical use of laser excited fluorescence spectrometry in flames, graphite furnaces and inductively coupled plasmas are discussed in some detail. These parameters include the laser characteristics such as peak power, pulse duration, spectral bandwidth and repetition rate, the choice of the excitation line, the optical arrangement and the detection system, this last one centred on the widespread use of the boxcar averager. It is shown that, if the ultimate sensitivity is the goal to be achieved, then the choice must be the electrothermal atomization. However, even for flames and inductively coupled plasmas, excellent results are possible provided that: (i) the laser system allows complete spectral coverage in the ultraviolet: (ii) saturation of the fluorescence signal can be approached over a large sample volume; and (iii) the gated detection parameters and the laser repetition frequency are optimized with respect to each other so as to reach the maximum signal-to-noise ratio.

  3. 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.

  4. Theoretical study of terahertz generation from atoms and aligned molecules driven by two-color laser fields

    E-print Network

    Chen, Wenbo; Meng, Chao; Liu, Jinlei; Zhou, Zhaoyan; Zhang, Dongwen; Yuan, Jianmin; Zhao, Zengxiu

    2015-01-01

    We study the generation of terahertz radiation from atoms and molecules driven by an ultrashort fundamental laser and its second harmonic field by solving time-dependent Schr\\"odinger equation (TDSE). The comparisons between one-, two-, and three- dimensional TDSE numerical simulations show that initial ionized wave-packet and its subsequent acceleration in the laser field and rescattering with long-range Coulomb potential play key roles. We also present the dependence of the optimum phase delay and yield of terahertz radiation on the laser intensity, wavelength, duration, and the ratio of two-color laser components. Terahertz wave generation from model hydrogen molecules are further investigated by comparing with high harmonic emission. It is found that the terahertz yield is following the alignment dependence of ionization rate, while the optimal two-color phase delays varies by a small amount when the alignment angle changes from 0 to 90 degrees, which reflects alignment dependence of attosecond electron d...

  5. 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.

  6. High efficiency coherent optical memory with warm rubidium vapour

    E-print Network

    Hosseini, M; Lam, P K; Buchler, B C

    2010-01-01

    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 optical memory as do deterministic logic gates for optical quantum computing. In this paper 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. We also show storage 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.

  7. 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

  8. 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).

  9. 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}.

  10. 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}???, 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}??? 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.

  11. Development of an electric field application system with transparent electrodes towards the electron EDM measurement with laser-cooled Fr atoms

    NASA Astrophysics Data System (ADS)

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

    2014-09-01

    The permanent electric dipole moment (EDM) of elementary particles is a good probe for new physics beyond the standard model. Since the francium (Fr) atom has a large enhancement factor of the electron EDM and laser-cooled atoms can have long coherence times, we plan to utilize laser-cooled Fr atoms for the electron EDM search experiment. Besides, a strong electric field is one of key issues for the EDM experiment. Recently, we have embarked on a development of the electric field application system with transparent electrodes coated by tin-doped indium oxide (ITO). The ITO electrodes break the difficulty in the coexistence of electrodes with several cooling laser lights. The actual electric field applied to the atom is evaluated by measuring the dc Stark shift for the laser-cooled rubidium atoms. In this presentation, the present status of the electric field application system will be reported. The permanent electric dipole moment (EDM) of elementary particles is a good probe for new physics beyond the standard model. Since the francium (Fr) atom has a large enhancement factor of the electron EDM and laser-cooled atoms can have long coherence times, we plan to utilize laser-cooled Fr atoms for the electron EDM search experiment. Besides, a strong electric field is one of key issues for the EDM experiment. Recently, we have embarked on a development of the electric field application system with transparent electrodes coated by tin-doped indium oxide (ITO). The ITO electrodes break the difficulty in the coexistence of electrodes with several cooling laser lights. The actual electric field applied to the atom is evaluated by measuring the dc Stark shift for the laser-cooled rubidium atoms. In this presentation, the present status of the electric field application system will be reported. This work is supported by Grants-in-Aid for Scientific Research (No. 26220705) and Tohoku University's Focused Research Project.

  12. Manipulating state-selective charge exchange in laser-assisted collisions of He2+ with atomic H

    NASA Astrophysics Data System (ADS)

    Domínguez-Gutiérrez, F. Javier; Cabrera-Trujillo, R.

    2013-09-01

    We solve the time-dependent Schrödinger 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.

  13. Noncontact estimation of intercellular breaking force using a femtosecond laser impulse quantified by atomic force microscopy

    PubMed Central

    Hosokawa, Yoichiroh; Hagiyama, Man; Iino, Takanori; Murakami, Yoshinori; Ito, Akihiko

    2011-01-01

    When a femtosecond laser pulse (fsLP) is focused through an objective lens into a culture medium, an impulsive force (fsLP-IF) is generated that propagates from the laser focal point (Of) in a micron-sized space. This force can detach individual adherent cells without causing considerable cell damage. In this study, an fsLP-IF was reflected in the vibratory movement of an atomic force microscopy (AFM) cantilever. Based on the magnitude of the vibration and the geometrical relationship between Of and the cantilever, the fsLP-IF generated at Of was calculated as a unit of impulse [N-s]. This impulsive force broke adhesion molecule-mediated intercellular interactions in a manner that depended on the adhesion strength that was estimated by the cell aggregation assay. The force also broke the interactions between streptavidin-coated microspheres and a biotin-coated substrate with a measurement error of approximately 7%. These results suggest that fsLP-IF can be used to break intermolecular and intercellular interactions and estimate the adhesion strength. The fsLP-IF was used to break intercellular contacts in two biologically relevant cultures: a coculture of leukocytes seeded over on an endothelial cell monolayer, and a polarized monolayer culture of epithelial cells. The impulses needed to break leukocyte–endothelial and interepithelial interactions, which were calculated based on the geometrical relationship between Of and the adhesive interface, were on the order of 10-13 and 10-12 N-s, respectively. When the total impulse at Of is well-defined, fsLP-IF can be used to estimate the force required to break intercellular adhesions in a noncontact manner under biologically relevant conditions. PMID:21245358

  14. Topotactic changes on ?-Mo4O11 caused by biased atomic force microscope tip and cw-laser

    NASA Astrophysics Data System (ADS)

    Borovšak, Miloš; Šutar, 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.

  15. 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.

  16. Deuterium excess in the atmospheric water vapour of a Mediterranean coastal wetland: regional vs. local signatures

    NASA Astrophysics Data System (ADS)

    Delattre, H.; Vallet-Coulomb, C.; Sonzogni, C.

    2015-09-01

    Stable isotopes of water vapour represent a powerful tool for tracing atmospheric vapour origin and mixing processes. Laser spectrometry recently allowed high time-resolution measurements, but despite an increasing number of experimental studies, there is still a need for a better understanding of the isotopic signal variability at different time scales. We present results of in situ measurements of ?18O and ?D during 36 consecutive days in summer 2011 in atmospheric vapour of a Mediterranean coastal wetland exposed to high evaporation (Camargue, Rhône River delta, France). The mean composition of atmospheric vapour (?v) is ?18O = -14.66 ‰ and ?D = - 95.4 ‰, with data plotting clearly above the local meteoric water line on a ?18O-?D plot, and an average deuterium excess (d) of 21.9 ‰. Important diurnal d variations are observed, and an hourly time scale analysis is necessary to interpret the main processes involved in its variability. After having classified the data according to air mass back trajectories, we analyse the average daily cycles relating to the two main meteorological situations, i.e. air masses originating from North Atlantic Ocean and Mediterranean Sea. In both situations, we show that diurnal fluctuations are driven by (1) the influence of local evaporation, culminating during daytime, and leading to an increase in absolute water vapour concentration associated to a ?v enrichment and d increase; (2) vertical air mass redistribution when the Planetary Boundary Layer collapses in the evening, leading to a d decrease, and (3) dew formation during the night, producing a ?v depletion with d remaining stable. Using a two-component mixing model, we calculate the average composition of the locally evaporated vapour (?E). We find higher d(E) under North Atlantic air mass conditions, which is consistent with lower humidity conditions. We also suggest that ?v measured when the PBL collapses is the most representative of a regional signal. Strong, cold and dry winds coming from the north bring an isotopically depleted vapour, while light, warm and wet winds coming from the south bring an isotopically enriched vapour. Under northern conditions, a strong advection rate dilutes the contribution of the locally evaporated vapour (?E) to the ambient moisture (?v). The higher d values measured under northern conditions, compared to the Mediterranean situation, thus results from the combination of a higher d in both local and regional vapour. This depiction of typical daily cycles of water vapour isotopic composition can be used as a framework for further quantitative analyses of vapour sources during specific days.

  17. 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.

  18. Analysis of tungsten carbide coatings by infrared laser-induced argon spark with inductively coupled plasma atomic emission spectrometry

    NASA Astrophysics Data System (ADS)

    Kanický, V.; Otruba, V.; Mermet, J.-M.

    2000-10-01

    Infrared laser ablation was studied for application to the analysis of plasma-sprayed tungsten carbide/cobalt coatings. The potential of the laser induced argon-spark (LINA-Spark™), as a sample introduction device in inductively coupled plasma atomic emission spectrometry was studied. The use of an IR laser along with defocusing led to laser-induced microplasma-based ablation. The mass ablation rate, represented by the ICP emission intensity per laser beam unit area, exhibited a flat increase in the irradiance range 2-250 GW/cm 2. A low slope (0.5) of this dependence in log-log scale gave evidence of plasma shielding. The steep increase in the measured acoustic signal when focused in front of the sample, i.e. in argon, indicated a breakdown of argon. Consequently, considerably lower ICP emissions were observed within the same range of irradiance. The cobalt/tungsten line intensity ratio in the ICP was practically constant from 1.5 up to at least 250 GW/cm 2. Acceptable precision (R.S.D.<5%) was obtained without internal standardization for irradiance between 2 and 8 GW/cm 2. Optimization of the laser pulse energy, repetition rate, beam focusing and sample displacement during interaction led to the linearization of dependences of signal vs. cobalt percentage, at least up to the highest studied value of 23% Co.

  19. 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 model—the ionization of an s-level bound by zero-range forces in the field of a circularly polarized electromagnetic wave—are 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'.

  20. Earle K. Plyler Prize for Molecular Spectroscopy Talk: Laser Ablated Metal Atom Reactions to Form Novel Molecules

    NASA Astrophysics Data System (ADS)

    Andrews, Lester

    2010-03-01

    A wide variety of laser-ablated metal atom reactions in solid rare gas matrices at cryogenic temperatures to form novel product molecules will be presented. These will include the ion-pair molecule Li^+O2^-, the dialane molecule Al2H6, the thorium methylidene CH2=ThH2, the thorium borylene FB=ThF2, the uranium methylidyne HC?UF3, the nitride N?UF3, and other recently prepared uranium bearing molecules.

  1. Doubly resonant three-photon double ionization of Ar atoms induced by an EUV free-electron laser

    SciTech Connect

    Gryzlova, E. V.; Ma, Ri; Fukuzawa, H.; Motomura, K.; Yamada, A.; Ueda, K.; Grum-Grzhimailo, A. N.; Strakhova, S. I.; Kabachnik, N. M.; Rouzee, A.; Hundermark, A.; Vrakking, M. J. J.; Johnsson, P.; Nagaya, K.; Yase, S.; Mizoguchi, Y.; Yao, M.; Nagasono, M.; Tono, K.; Yabashi, M.; and others

    2011-12-15

    A mechanism for three-photon double ionization of atoms by extreme-ultraviolet free-electron laser pulses is revealed, where in a sequential process the second ionization step, proceeding via resonant two-photon ionization of ions, is strongly enhanced by the excitation of ionic autoionizing states. In contrast to the conventional model, the mechanism explains the observed relative intensities of photoelectron peaks and their angular dependence in three-photon double ionization of argon.

  2. Strong amplification of sidebands in a strongly driven three-level atomic system. II. Classical description of the laser field

    NASA Astrophysics Data System (ADS)

    Mavroyannis, Constantine

    1986-04-01

    The fluorescent spectra arising from the interaction of a three-level atom with a strong pump field and a weak signal field have been studied simultaneously. The atom consists of an upper excited state ||2> and two lower ground states ||3> and ||1>, which arise by removing the degeneracy of the ground state by applying internal or external fields. The laser field depletes the metastable state ||3> by bringing the electrons into the excited state ||2> from where the electrons emit photons and decay into the lower states through the transitions ||2> ? ||3> and ||2> ? ||1>, which are described by the signal field. Using a classical description of the laser field, where in the model Hamiltonian the laser-atom interaction is treated classically while the free and interacting electron and signal fields are quantized, the decay process ||2> ? ||1> of the signal field is considered by evaluating the appropriate Green's function of the system. The spectral function for the ||2> ? ||1> transition of the signal field describes one-photon, three-photon, and two-photon Raman processes, respectively. The one-photon spectra consist of the main peak at the signal frequency and a pair of sidebands, which are symmetrically located from the position of the main peak. The intensity of the main peak is positive while that of the sidebands is negative indicating that the signal is attenuated and is amplified at the corresponding frequencies, respectively. The three-photon and two-photon Raman spectra are described by a doublet, respectively, whose intensities are always negative, implying amplification of the signal field. The computed spectra are presented graphically and compared with those derived in a recent study, where the laser field is quantized and photon-photon correlations are taken into consideration in the limit of high photon densities of the laser field. A detailed discussion of both treatments is given for the processes under investigation.

  3. Characterization of a tunable optical parametric oscillator laser system for multielement flame laser excited atomic fluorescence spectrometry of cobalt, copper, lead, manganese, and thallium in buffalo river sediment.

    PubMed

    Zhou, J X; Hou, X; Tsai, S J; Yang, K X; Michel, R G

    1997-02-01

    A pulsed (10 Hz) optical parametric oscillator (OPO) laser system based on beta-barium borate (BBO) crystals and equipped with a frequency-doubling option (FDO) was characterized for use in laser excited atomic fluorescence spectrometry (LEAFS). This all-solid-state laser has a narrow spectral line width, a wide spectral tuning range (220-2200 nm), and a rapid, computer-controlled slew scan of wavelength (0.250 nm s-1 in the visible and infrared, and 0.125 nm s-1 in the ultraviolet). The output power characteristics (15-90 mJ/pulse in the visible, 1-40 mJ in the infrared, and 1-11 mJ in the ultraviolet), laser pulse-to-pulse variability (3-13% relative standard deviation, RSD, of the laser pulses), conversion efficiency of the FDO (2-17%), and spectral bandwidth in the visible spectrum (0.1-0.3 cm-1) were measured. The laser was used as the excitation source for a flame LEAFS instrument for which rapid, sequential, multielement analysis was demonstrated by slew scan of the laser. The instrument allowed about 640 measurements to be made in about 6 h, with triplicate measurements of all solutions and aqueous calibration curves, which yielded accurate analyses of a river sediment (National Institute of Standards and Technology, Buffalo River Sediment, 2704) for five elements with precisions < 5% RSD. Comparable or improved flame LEAFS detection limits over literature values were obtained for cobalt (2 ng mL-1), copper (2 ng mL-1), lead (0.4 ng mL-1), manganese (0.2 ng mL-1), and thallium (0.9 ng mL-1) by flame LEAFS. PMID:9030057

  4. 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 Schrödinger 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.

  5. 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.

  6. 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.

  7. 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.

  8. 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.

  9. 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 (?T=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 ?T=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.

  10. Mesoscale modelling of water vapour in the tropical UTLS: two case studies from the HIBISCUS campaign

    NASA Astrophysics Data System (ADS)

    Marécal, V.; Durry, G.; Longo, K.; Freitas, S.; Rivière, E. D.; Pirre, M.

    2006-08-01

    In this study, we evaluate the ability of the BRAMS mesoscale model compared to ECMWF global analysis to simulate the observed vertical variations of water vapour in the tropical upper troposphere and lower stratosphere (UTLS). The observations are balloon-borne measurements of water vapour mixing ratio and temperature from micro-SDLA (Tunable Diode Laser Spectrometer) instrument. Data from two balloon flights performed during the 2004 HIBISCUS field campaign are used to compare with the mesoscale simulations and to ECMWF analysis. The mesoscale model performs significantly better than ECMWF analysis for water vapour in the upper troposphere and similarly or slightly worse for temperature. The improvement provided by the mesoscale model for water vapour comes mainly from (i) the enhanced vertical resolution in the UTLS (250 m for BRAMS and ~1 km for ECMWF model) and (ii) the more detailed microphysical parameterization providing ice supersaturations as in the observations. The ECMWF vertical resolution (~1 km) is too coarse to capture the observed fine scale vertical variations of water vapour in the UTLS. In near saturated or supersaturated layers, the mesoscale model relative humidity with respect to ice saturation is close to observations provided that the temperature profile is realistic. For temperature, ECMWF analysis gives good results partly thanks to data assimilation. The analysis of the mesoscale model results showed that in undersaturated layers, the water vapour profile depends mainly on the dynamics. In saturated/supersaturated layers, microphysical processes play an important role and have to be taken into account on top of the dynamical processes to understand the water vapour profiles. In the lower stratosphere, the ECMWF model and the BRAMS model give very similar water vapour profiles that are significantly dryer than micro-SDLA measurements. This similarity comes from the fact that BRAMS is initialised using ECMWF analysis and that no mesoscale process acts in the stratosphere leading to no modification of the BRAMS results with respect to ECMWF analysis.

  11. 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.; Hömmerich, 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.

  12. 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.

  13. Non-perturbative generation of above-threshold harmonics from pre-excited argon atoms in intense mid-infrared laser fields

    E-print Network

    Li, Guihua; Li, Ziting; Yao, Jingpin; Zeng, Bin; Chu, Wei; Cheng, Ya

    2015-01-01

    We experimentally investigate the generation of above-threshold harmonics completely from argon atoms on an excited state using mid-infrared femtosecond laser pulses. The highly nonlinear dependences of the observed signal on the pulse energy and polarization of the driver laser pulses indicate its non-perturbative characteristic.

  14. Laser wavelength effects on ionic and atomic emission from tin plasmas D. Campos,a

    E-print Network

    Harilal, S. S.

    , Purdue University, 400 Central Drive, West Lafayette, Indiana 47907, USA Received 26 January 2010- minum garnet Nd:YAG laser generated a high conversion efficiency CE thus suggesting that laser produced conversion of the incident laser pulse energy to EUV radiation as well as nearly complete control of debris

  15. 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.

  16. 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.

  17. Atomic force microscopy analysis of human cornea surface after UV (?=266 nm) laser irradiation

    NASA Astrophysics Data System (ADS)

    Spyratou, E.; Makropoulou, M.; Moutsouris, K.; Bacharis, C.; Serafetinides, A. A.

    2009-07-01

    Efficient cornea reshaping by laser irradiation for correcting refractive errors is still a major issue of interest and study. Although the excimer laser wavelength of 193 nm is generally recognized as successful in ablating corneal tissue for myopia correction, complications in excimer refractive surgery leads to alternative laser sources and methods for efficient cornea treatment. In this work, ablation experiments of human donor cornea flaps were conducted with the 4th harmonic of an Nd:YAG laser, with different laser pulses. AFM analysis was performed for examination of the ablated cornea flap morphology and surface roughness.

  18. 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.

  19. Frequency stabilization of an external-cavity diode laser to metastable argon atoms in a discharge.

    PubMed

    Douglas, P; Maher-McWilliams, C; Barker, P F

    2012-06-01

    A laser stabilization scheme using magnetic dichroism in a RF plasma discharge is presented. This method has been used to provide a frequency stable external-cavity diode laser that is locked to the 4s[3/2](2) ? 4p[5/2](3) argon laser cooling transition at 811.53 nm. Using saturated absorption spectroscopy, we lock the laser to a Doppler free peak which gave a locking range of 20 MHz when the slope of the error signal was maximized. The stability of the laser was characterized by determining the square root Allan variance of laser frequency fluctuations when the laser was locked. A stability of 129 kHz was measured at 1 s averaging time for data acquired over 6000 s. PMID:22755615

  20. High-resolution Rydberg tagging time-of-flight measurements of atomic photofragments by single-photon vacuum ultraviolet laser excitation

    SciTech Connect

    Jones, Brant; Zhou Jingang; Yang Lei; Ng, C. Y.

    2008-12-15

    By coupling a comprehensive tunable vacuum ultraviolet (VUV) laser system to a velocity-mapped ion imaging apparatus, we show that high-resolution high-n Rydberg tagging time-of-flight (TOF) measurements of nascent atomic photofragments formed by laser photodissociation can be made using single-photon VUV laser photoexcitation. To illustrate this single-photon Rydberg tagging TOF method, we present here the results of the VUV laser high-n Rydberg tagging TOF measurements of O({sup 3}P{sub 2}) and S({sup 3}P{sub 2}) formed in the photodissociation of SO{sub 2} and CS{sub 2} at 193.3 and 202.3 nm, respectively. These results are compared to those obtained by employing the VUV laser photoionization time-sliced velocity-mapped ion imaging technique. The fact that the kinetic energy resolutions achieved in the VUV laser high-n Rydberg tagging TOF measurements of O and S atoms are found to be higher than those observed in the VUV laser photoionization, time-sliced velocity-mapped ion imaging studies show that the single-photon VUV laser high-n Rydberg tagging TOF method is useful and complementary to state-of-the-art time-sliced velocity-mapped ion imaging measurements of heavier atomic photofragments, such as O and S atoms. Furthermore, the general agreement observed between the VUV laser high-n Rydberg tagging TOF and velocity-mapped ion imaging experiments supports the conclusion that the lifetimes of the tagged Rydberg states of O and S atoms are sufficiently long to allow the reliable determination of state-resolved UV photodissociation cross sections of SO{sub 2} and CS{sub 2} by using the VUV laser high-n Rydberg tagging TOF method.

  1. Continuous high-flux monovelocity atomic beam based on a broadband laser-cooling technique

    SciTech Connect

    Zhu, M.; Oates, C.W.; Hall, J.L. )

    1991-07-01

    We report application of Hoffnagle's broadband cooling concept to cool Na atoms in an atomic beam. The rms velocity spread of the cooled atoms is 0.75{plus minus}0.05 m/s (1.5{plus minus}0.2 mK) with a flux of (9.5{plus minus}1.0) {times} 10{sup 8} atoms/s. 1D broadband optical molasses is also demonstrated. Potential applications of the cooling scheme are discussed.

  2. Multibeam emitters as joint optical laser complex and ion-optical system for laser selection of atoms, molecules, isotopes, isomers, long-lived and short-lived radionuclides in different spheres from ?-laser and atomic energetics to medicine and gene engineering

    NASA Astrophysics Data System (ADS)

    Karyagin, Stanislav V.

    2001-03-01

    The SPTEN-(gamma) -laser's development leads to the essentially new principles for the effective converting of the nuclear radiation (neutrons, gamma, etc.) into the well controlling and focusing broad formatted atomic (ionic, molecular, etc.) beams which are fit for the creation of the active medium of the (gamma) -laser and for the other aims, e.g., for the acceleration by many orders of the selection of atoms, molecules, isotopes, isomers, radionuclides, for high precision methods in the spectroscopy-chromatography of the macromolecules, etc. The appropriate Multi Beam Emitter systems, MBE, are based on the dividing of the broad formatted beam of nuclei into a big amount approximately 105 - 109 of the collinear microbeams with use of the especial deeply engraved gratings together with ad hoc ion and laser optics. MBE will be realized in a non-(gamma) - laser sphere before the first direct (gamma) -lasing demonstration experiments.

  3. 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.

  4. In situ atomic force microscopy of laser-conditioned and laser- damaged HfO sub 2 /saw sub 2 dielectric mirror coatings

    SciTech Connect

    Staggs, M.C.; Balooch, M.; Kozlowski, M.R.; Siekhaus, W.J.

    1991-01-07

    Atomic force microscopy was used to determine in situ the nm-scale morphological changes that occur on dielectric optical coatings as a result of laser illumination. Of particular interest is a process called laser conditioning in which the damage threshold of the films is increased by a factor of 2 to 3 when the film is first illuminated at fluences below the damage threshold. The optical coating studied was a highly reflective dielectric multilayer mirror (HR) consisting of many alternating quarter-wave layers of HfO{sub 2} and SiO{sub 2} at 1.06 {mu}m. The top layer was a {lambda}/2 SiO{sub 2} overcoat. Laser beam specifications were: 1.06-{mu}m wavelength, 8- to 10-ns pulsewidth. Laser beam spot sizes ranging from 85 {mu}m to 1.4 mm in diameter. The maximum scan range of the AFM was 80 {mu}m. A survey of the as-deposited surface shows mostly hillocks approximately 200 nm in diameter and 10 nm in height. The predominant surface irregularity is {mu}m-scale domes associated with well known nodule defects. Laser illumination causes nodule defects to be easily ejected from the coating surface. Further damage may propagate from the resulting craters. These nodule defects therefore determine the damage threshold of the film. Using the AFM we have shown that for illumination at fluences below the nodule ejection threshold we observe a decrease in the surface roughness of the nodule defects and hillock structure of the as-deposited film. The subtle changes in these surface features may be an indication that the film is being mechanically stabilized, thus providing the observed conditioning effect.

  5. In situ atomic force microscopy of laser-conditioned and laser- damaged HfO{sub 2}/saw{sub 2} dielectric mirror coatings

    SciTech Connect

    Staggs, M.C.; Balooch, M.; Kozlowski, M.R.; Siekhaus, W.J.

    1991-01-07

    Atomic force microscopy was used to determine in situ the nm-scale morphological changes that occur on dielectric optical coatings as a result of laser illumination. Of particular interest is a process called laser conditioning in which the damage threshold of the films is increased by a factor of 2 to 3 when the film is first illuminated at fluences below the damage threshold. The optical coating studied was a highly reflective dielectric multilayer mirror (HR) consisting of many alternating quarter-wave layers of HfO{sub 2} and SiO{sub 2} at 1.06 {mu}m. The top layer was a {lambda}/2 SiO{sub 2} overcoat. Laser beam specifications were: 1.06-{mu}m wavelength, 8- to 10-ns pulsewidth. Laser beam spot sizes ranging from 85 {mu}m to 1.4 mm in diameter. The maximum scan range of the AFM was 80 {mu}m. A survey of the as-deposited surface shows mostly hillocks approximately 200 nm in diameter and 10 nm in height. The predominant surface irregularity is {mu}m-scale domes associated with well known nodule defects. Laser illumination causes nodule defects to be easily ejected from the coating surface. Further damage may propagate from the resulting craters. These nodule defects therefore determine the damage threshold of the film. Using the AFM we have shown that for illumination at fluences below the nodule ejection threshold we observe a decrease in the surface roughness of the nodule defects and hillock structure of the as-deposited film. The subtle changes in these surface features may be an indication that the film is being mechanically stabilized, thus providing the observed conditioning effect.

  6. Predicting the absorption of chemical vapours.

    PubMed

    Rauma, Matias; Boman, Anders; Johanson, Gunnar

    2013-02-01

    The focus of this review is on the systemic absorption of vapours via skin, including experimental data as well as regression and pharmacokinetic models. Dermal contribution ratios (DCR), i.e. amount absorbed through skin relative to total intake (skin and inhalation) at specified conditions, could be identified or calculated from published data for 33 chemical vapours. The ratios vary from ~0.0002 (vinyl chloride) to ~0.8 (2-butoxyethanol), with hydrophilic chemicals having a higher ratio than lipophilic ones. Multiple regression analysis of these data suggests that the DCR is largely explained by the octanol:water partition coefficient, vapour pressure and molecular weight (R(2)=0.69). Several physiologically-based pharmacokinetic models were identified; however, all describe the absorption of single substances. Regarding predictive models, only two models were found. In conclusion, dermal uptake of chemical vapours needs more attention, as such exposures are common, data are scarce and few predictive models exist. PMID:22465561

  7. Measurement of temperature rises in the femtosecond laser pulsed three-dimensional atom probe

    SciTech Connect

    Cerezo, A.; Smith, G.D.W.; Clifton, P.H.

    2006-04-10

    A previous Letter [B. Gault et al., Appl. Phys. Lett. 86, 094101 (2005)] interpreted measurements of the field evaporation enhancement under femtosecond pulsed laser irradiation of a field emitter in terms of a direct electric field enhancement by the intrinsic field of the laser light. We show that, on the contrary, the field evaporation enhancement is predominantly a thermal heating effect. Indirect measurements of the peak specimen temperature under irradiation by femtosecond laser pulses are consistent with temperature rises obtained using longer laser pulses in a range of earlier work.

  8. In-source laser spectroscopy of polonium isotopes: From atomic physics to nuclear structure

    E-print Network

    Rothe, S

    2014-01-01

    The Resonance Ionization Laser Ion Source RILIS [1] at the CERN-ISOLDE on-line radioactive ion beam facility is essential for ion beam production for the majority of experiments, but it is also powerful tool for laser spectroscopy of rare isotopes. A series of experiments on in-source laser spectroscopy of polonium isotopes [2, 3] revealed the nuclear ground state properties of 191;211;216;218Po. However, limitations caused by the isobaric background of surface-ionized francium isotopes hindered the study of several neutron rich polonium isotopes. The development of the Laser Ion Source and Trap (LIST) [4] and finally its integration at ISOLDE has led to a dramatic suppression of surface ions. Meanwhile, the RILIS laser spectroscopy capabilities have advanced tremendously. Widely tunable titanium:sapphire (Ti:Sa) lasers were installed to complement the established dye laser system. Along with a new data acquisition system [5], this more versatile laser setup enabled rst ever laser spectroscopy of the radioact...

  9. An assessment of vapour pressure estimation methods.

    PubMed

    O'Meara, Simon; Booth, Alastair Murray; Barley, Mark Howard; Topping, David; McFiggans, Gordon

    2014-09-28

    Laboratory measurements of vapour pressures for atmospherically relevant compounds were collated and used to assess the accuracy of vapour pressure estimates generated by seven estimation methods and impacts on predicted secondary organic aerosol. Of the vapour pressure estimation methods that were applicable to all the test set compounds, the Lee-Kesler [Reid et al., The Properties of Gases and Liquids, 1987] method showed the lowest mean absolute error and the Nannoolal et al. [Nannoonal et al., Fluid Phase Equilib., 2008, 269, 117-133] method showed the lowest mean bias error (when both used normal boiling points estimated using the Nannoolal et al. [Nannoolal et al., Fluid Phase Equilib., 2004, 226, 45-63] method). The effect of varying vapour pressure estimation methods on secondary organic aerosol (SOA) mass loading and composition was investigated using an absorptive partitioning equilibrium model. The Myrdal and Yalkowsky [Myrdal and Yalkowsky, Ind. Eng. Chem. Res., 1997, 36, 2494-2499] vapour pressure estimation method using the Nannoolal et al. [Nannoolal et al., Fluid Phase Equilib., 2004, 226, 45-63] normal boiling point gave the most accurate estimation of SOA loading despite not being the most accurate for vapour pressures alone. PMID:25105180

  10. Spectroscopic detection and analysis of atomic emissions during industrial pulsed laser-drilling of structural aerospace alloys

    NASA Astrophysics Data System (ADS)

    Bright, Robin Michael

    The ability to adequately cool internal gas-turbine engine components in next-generation commercial and military aircraft is of extreme importance to the aerospace industry as the demand for high-efficiency engines continues to push operating temperatures higher. Pulsed laser-drilling is rapidly becoming the preferred method of creating cooling holes in high temperature components due a variety of manufacturing advantages of laser-drilling over conventional hole-drilling techniques. As cooling requirements become more demanding, the impact of drilling conditions on material removal behavior and subsequent effects on hole quality becomes critical. In this work, the development of emission spectroscopy as a method to probe the laser-drilling process is presented and subsequently applied to the study of material behavior of various structural aerospace materials during drilling. Specifically, emitted photons associated with energy level transitions within excited neutral atoms in material ejected during drilling were detected and analyzed. Systematic spectroscopic studies indicated that electron energy level populations and calculated electron temperatures within ejected material are dependent on both laser pulse energy and duration. Local thermal conditions detected by the developed method were related to the characteristics of ejected material during drilling and to final hole quality. Finally, methods of utilizing the observed relationships for spectroscopic process monitoring and control were demonstrated.

  11. Theoretical study of terahertz generation from atoms and aligned molecules driven by two-color laser fields

    NASA Astrophysics Data System (ADS)

    Chen, Wenbo; Huang, Yindong; Meng, Chao; Liu, Jinlei; Zhou, Zhaoyan; Zhang, Dongwen; Yuan, Jianmin; Zhao, Zengxiu

    2015-09-01

    We study the generation of terahertz radiation from atoms and molecules driven by an ultrashort fundamental laser and its second-harmonic field by solving the time-dependent Schrödinger equation (TDSE). The comparisons between one-, two-, and three-dimensional TDSE numerical simulations show that the initial ionized wave packet and its subsequent acceleration in the laser field and rescattering with long-range Coulomb potential play key roles. We also present the dependence of the optimum phase delay and yield of terahertz radiation on the laser intensity, wavelength, duration, and ratio of two-color laser components. Terahertz wave generation from model hydrogen molecules is further investigated by comparing with high harmonic emission. It is found that the terahertz yield follows the alignment dependence of the ionization rate, while the optimal two-color phase delays vary by a small amount when the alignment angle changes from 0 to 90 degrees, which reflects the alignment dependence of attosecond electron dynamics. Finally, we show that terahertz emission might be used to clarify the origin of interference in high harmonic generation from aligned molecules by coincidentally measuring the alignment-dependent THz yields.

  12. 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].

  13. VOLUME 87, NUMBER 17 P H Y S I C A L R E V I E W L E T T E R S 22 OCTOBER 2001 Atom Laser Divergence

    E-print Network

    Thywissen, Joseph

    VOLUME 87, NUMBER 17 P H Y S I C A L R E V I E W L E T T E R S 22 OCTOBER 2001 Atom Laser-outcoupled, free-falling atom laser as a function of the outcoupling frequency. The data are compared to a Gaussian includes diffraction, magnetic lensing, and interaction between the atom laser and the condensate. We find

  14. Title of Document: INTERACTION OF LASERS WITH ATOMIC CLUSTERS AND STRUCTURED PLASMAS

    E-print Network

    Anlage, Steven

    response of an individual cluster when irradiated by a laser. Our analysis of the laser pulse interaction and integrate the response of individual electrons to the self consistent field following unperturbed orbits. The dipole spectrum depicts strong absorption at frequencies much smaller than wp/v2. This enhanced

  15. Nanoscale bending movement of biological micro-object induced by femtosecond laser impulse and its detection by atomic force microscopy

    NASA Astrophysics Data System (ADS)

    Takenaka, Masanobu; Iino, Takanori; Nagatani, Akira; Hosokawa, Yoichiroh

    2014-08-01

    A horizontal vibrational motion of biological tissue generated by a femtosecond laser-induced impulsive force was directly detected for the first time as angular shift of the cantilever of an atomic force microscope (AFM), which was directly in contact with the tissue. The motion of a small plant stem (diameter: 160 µm) on the force loading was detected by the torsional motion of the AFM cantilever. The sensitivity of the method was evaluated by a numerical simulation with the finite element method (FEM). The results conclusively demonstrated the efficacy of this method for nano-scale detection of the horizontal motion of biological micro-objects.

  16. Using Lasers and X-rays to Reveal the Motion of Atoms and Electrons (LBNL Summer Lecture Series)

    SciTech Connect

    Schoenlein, Robert

    2009-07-14

    Summer Lecture Series 2009: The ultrafast motion of atoms and electrons lies at the heart of chemical reactions, advanced materials with exotic properties, and biological processes such as the first event in vision. Bob Schoenlein, Deputy Director for Science at the Advanced Light Source, will discuss how such processes are revealed by using laser pulses spanning a millionth of a billionth of a second, and how a new generation of light sources will bring the penetrating power of x-rays to the world of ultrafast science.

  17. Using Lasers and X-rays to Reveal the Motion of Atoms and Electrons (LBNL Summer Lecture Series)

    ScienceCinema

    Schoenlein, Robert [Deputy Director, Advanced Light Source

    2011-04-28

    Summer Lecture Series 2009: The ultrafast motion of atoms and electrons lies at the heart of chemical reactions, advanced materials with exotic properties, and biological processes such as the first event in vision. Bob Schoenlein, Deputy Director for Science at the Advanced Light Source, will discuss how such processes are revealed by using laser pulses spanning a millionth of a billionth of a second, and how a new generation of light sources will bring the penetrating power of x-rays to the world of ultrafast science.

  18. Using Lasers and X-rays to Reveal the Motion of Atoms and Electrons (LBNL Summer Lecture Series)

    SciTech Connect

    Schoenlein, Robert

    2009-07-07

    Summer Lecture Series 2009: The ultrafast motion of atoms and electrons lies at the heart of chemical reactions, advanced materials with exotic properties, and biological processes such as the first event in vision. Bob Schoenlein, Deputy Director for Science at the Advanced Light Source, will discuss how such processes are revealed by using laser pulses spanning a millionth of a billionth of a second, and how a new generation of light sources will bring the penetrating power of x-rays to the world of ultrafast science.

  19. Using Lasers and X-rays to Reveal the Motion of Atoms and Electrons (LBNL Summer Lecture Series)

    ScienceCinema

    Schoenlein, Robert [Deputy Director, Advanced Light Source

    2010-01-08

    Summer Lecture Series 2009: The ultrafast motion of atoms and electrons lies at the heart of chemical reactions, advanced materials with exotic properties, and biological processes such as the first event in vision. Bob Schoenlein, Deputy Director for Science at the Advanced Light Source, will discuss how such processes are revealed by using laser pulses spanning a millionth of a billionth of a second, and how a new generation of light sources will bring the penetrating power of x-rays to the world of ultrafast science.

  20. Investigation of material property influenced stoichiometric deviations as evidenced during UV laser-assisted atom probe tomography in fluorite oxides

    NASA Astrophysics Data System (ADS)

    Valderrama, Billy; Henderson, Hunter B.; Yablinsky, Clarissa A.; Gan, Jian; Allen, Todd R.; Manuel, Michele V.

    2015-09-01

    Oxide materials are used in numerous applications such as thermal barrier coatings, nuclear fuels, and electrical conductors and sensors, all applications where nanometer-scale stoichiometric changes can affect functional properties. Atom probe tomography can be used to characterize the precise chemical distribution of individual species and spatially quantify the oxygen to metal ratio at the nanometer scale. However, atom probe analysis of oxides can be accompanied by measurement artifacts caused by laser-material interactions. In this investigation, two technologically relevant oxide materials with the same crystal structure and an anion to cation ratio of 2.00, pure cerium oxide (CeO2) and uranium oxide (UO2) are studied. It was determined that electronic structure, optical properties, heat transfer properties, and oxide stability strongly affect their evaporation behavior, thus altering their measured stoichiometry, with thermal conductance and thermodynamic stability being strong factors.

  1. Interferences of real trajectories and the emergence of quantum features in electron-atom scattering in a strong laser field

    SciTech Connect

    Cerkic, A.; Milosevic, D. B.

    2006-03-15

    Using the example of electron-atom scattering in a strong laser field, it is shown that the oscillatory structure of the scattered electron spectrum can be explained as a consequence of the interference of the real electron trajectories in terms of Feynman's path integral. While in previous work on quantum-orbit theory the complex solutions of the saddle-point equations were considered, we show here that for the electron-atom scattering with much simpler real solutions a satisfactory agreement with the strong-field-approximation results can be achieved. Real solutions are applicable both for the direct (low-energy) and the rescattering (high-energy) plateau in the scattered electron spectrum. In between the plateaus and beyond the rescattering cutoff good results can be obtained using the complex (quantum) solutions and the uniform approximation. The interference of real solutions is related to the recent attosecond double-slit experiment in time.

  2. Modeling of atomic processes for x-ray-laser plasmas. Final report, 15 June 1986-14 February 1988

    SciTech Connect

    Gupta, U.

    1988-07-01

    This work dealt with the theoretical modeling and computation of photoionization, photoexcitation, radiative decay, and radiative recombination processes for multielectron atoms and ions in plasmas. Such atomic processes lead to and influence lasing in x-ray lasers operating both in the soft- and hard-x-ray regions. This research utilized a two-component, finite temperature, self consistent density functional method and demonstrated that this method is applicable for arbitrary plasma density and temperature and is capable of accurately treating multielectron ions of arbitrary Z. Electron-collisional ionization and excitation processes were investigated. These processes are an important mechanism through which population inversion of ionic energy levels lead to lasing in the soft x-ray region. Previously, theoretical calculations utilizing a semi-classical impact approximation were performed. In many cases such a method is inadequate. Computations were carried out by electron-impact ionization and excitation cross sections and rate coefficients utilizing the distorted wave with exchange method.

  3. Three-dimensional atom localization by laser fields in a four-level tripod system

    NASA Astrophysics Data System (ADS)

    Ivanov, Vladimir S.; Rozhdestvensky, Yuri V.; Suominen, Kalle-Antti

    2014-12-01

    We present a scheme for high-precision three-dimensional (3D) localization by the measurement of the atomic-level population. The scheme is applied to a four-level tripod-type atom coupled by three strong standing waves and a probe running wave. As a result, the atom can be localized in volumes that are substantially smaller than a cubic optical wavelength, which is achieved by the increase of standing-wave intensities. The upper-level distribution depends crucially on the atom-field coupling and it forms 3D periodic structures composed of spheres, hourglasses, bowls, donuts, or deformed barrels.

  4. Femtosecond, two-photon laser-induced-fluorescence imaging of atomic oxygen in an atmospheric-pressure plasma jet

    NASA Astrophysics Data System (ADS)

    Schmidt, Jacob B.; Sands, Brian L.; Kulatilaka, Waruna D.; Roy, Sukesh; Scofield, James; Gord, James R.

    2015-06-01

    Femtosecond, two-photon-absorption laser-induced-fluorescence (fs-TALIF) spectroscopy is employed to measure space- and time-resolved atomic-oxygen distributions in a nanosecond, repetitively pulsed, externally grounded, atmospheric-pressure plasma jet flowing helium with a variable oxygen admixture. The high-peak-intensity, low-average-energy femtosecond pulses result in increased TALIF signal with reduced photolytic inferences. This allows 2D imaging of absolute atomic-oxygen number densities ranging from 5.8???×???1015 to 2.0???×???1012cm-3 using a cooled CCD with an external intensifier. Xenon is used for signal and imaging-system calibrations to quantify the atomic-oxygen fluorescence signal. Initial results highlight a transition in discharge morphology from annular to filamentary, corresponding with a change in plasma chemistry from ozone to atomic oxygen production, as the concentration of oxygen in the feed gas is changed at a fixed voltage-pulse-repetition rate. In this configuration, significant concentrations of reactive oxygen species may be remotely generated by sustaining an active discharge beyond the confines of the dielectric capillary, which may benefit applications that require large concentrations of reactive oxygen species such as material processing or biomedical devices.

  5. Quantum dynamics and cooling of atoms in one-dimensional standing-wave laser fields: Anomalous effects in Doppler cooling

    NASA Astrophysics Data System (ADS)

    Doery, M. R.; Vredenbregt, E. J. D.; Bergeman, T.

    1995-06-01

    We report computational results for the time evolution of the velocity distribution P(V,t) for two-level and multilevel ``Doppler'' laser cooling. We compare results obtained from the semiclassical (SC) Fokker-Planck equation and from generalized optical Bloch equations applied to density matrices over a basis of products of internal and quantized translational states (QDM). Computer memory requirements are optimized to make large-scale QDM calculations feasible. QDM and SC agree well except for two cases: (a) atoms in the wells of the light-shift potential (with kinetic energy less than the well depth, U0), and (b) atoms with recoil energy ER comparable to or greater than the natural linewidth ??. Transient dips occur in P(V,t) at V=0 in QDM results due to slow cooling of atoms in the light-shift potential wells. Dips in P(V,t) occur at velocity-tuned-resonance (Doppleron) velocities but disappear over long interaction times as atoms accumulate near points where the force is zero. When ER~=??, sharp peaks occur in P(V,T) at V=+/-VR from velocity-selective population quasitrapping not previously found in a two-level transition. Sharp features in P(V,t) occur also for J-->J+1 transitions with J>0, small U0/ER, and sufficiently large detuning, from transitions between individual quantum states in the periodic potential.

  6. Spatially and Temporally Resolved Atomic Oxygen Measurements in Short Pulse Discharges by Two Photon Laser Induced Fluorescence

    NASA Astrophysics Data System (ADS)

    Lempert, Walter; Uddi, Mruthunjaya; Mintusov, Eugene; Jiang, Naibo; Adamovich, Igor

    2007-10-01

    Two Photon Laser Induced Fluorescence (TALIF) is used to measure time-dependent absolute oxygen atom concentrations in O2/He, O2/N2, and CH4/air plasmas produced with a 20 nanosecond duration, 20 kV pulsed discharge at 10 Hz repetition rate. Xenon calibrated spectra show that a single discharge pulse creates initial oxygen dissociation fraction of ˜0.0005 for air like mixtures at 40-60 torr total pressure. Peak O atom concentration is a factor of approximately two lower in fuel lean (?=0.5) methane/air mixtures. In helium buffer, the initially formed atomic oxygen decays monotonically, with decay time consistent with formation of ozone. In all nitrogen containing mixtures, atomic oxygen concentrations are found to initially increase, for time scales on the order of 10-100 microseconds, due presumably to additional O2 dissociation caused by collisions with electronically excited nitrogen. Further evidence of the role of metastable N2 is demonstrated from time-dependent N2 2^nd Positive and NO Gamma band emission spectroscopy. Comparisons with modeling predictions show qualitative, but not quantitative, agreement with the experimental data.

  7. Synergistic effect of EUV from the laser-sustained detonation plasma in a ground-based atomic oxygen simulation on fluorinated polymers

    SciTech Connect

    Tagawa, Masahito; Abe, Shingo; Kishida, Kazuhiro; Yokota, Kumiko; Okamoto, Akio

    2009-01-05

    The contribution of extreme ultraviolet (EUV) from a laser-sustained plasma on the mass loss phenomenon of fluorinated polymer in a ground-based laser-detonation atomic oxygen beam source was evaluated. The atomic oxygen beam and EUV from the oxygen plasma were separated by the high-speed chopper wheel installed in the beam source. The mass changes of the fluorinated polymer and polyimide were measured from the frequency shift of the quartz crystal microbalance during the beam exposures. It has been made clear that the fluorinated polymer erodes by EUV exposure alone. In contrast, no erosion was detected for polyimide by EUV alone. The atomic oxygen-induced erosion was measured for both materials even without EUV exposure. However, no strong synergistic effect was observed for a fluorinated polymer even under the simultaneous exposure condition of atomic oxygen and EUV. Similar results were observed even in simultaneous exposure of atomic oxygen (without EUV) and 172 nm vacuum ultraviolet (VUV) from an excimer lamp. These experiments suggest that the primary origin of the accelerated erosion of fluorinated polymer observed in a laser detonation atomic oxygen source is not the EUV from the laser-sustained plasma.

  8. Synergistic effect of EUV from the laser-sustained detonation plasma in a ground-based atomic oxygen simulation on fluorinated polymers

    NASA Astrophysics Data System (ADS)

    Tagawa, Masahito; Abe, Shingo; Kishida, Kazuhiro; Yokota, Kumiko; Okamoto, Akio

    2009-01-01

    The contribution of extreme ultraviolet (EUV) from a laser-sustained plasma on the mass loss phenomenon of fluorinated polymer in a ground-based laser-detonation atomic oxygen beam source was evaluated. The atomic oxygen beam and EUV from the oxygen plasma were separated by the high-speed chopper wheel installed in the beam source. The mass changes of the fluorinated polymer and polyimide were measured from the frequency shift of the quartz crystal microbalance during the beam exposures. It has been made clear that the fluorinated polymer erodes by EUV exposure alone. In contrast, no erosion was detected for polyimide by EUV alone. The atomic oxygen-induced erosion was measured for both materials even without EUV exposure. However, no strong synergistic effect was observed for a fluorinated polymer even under the simultaneous exposure condition of atomic oxygen and EUV. Similar results were observed even in simultaneous exposure of atomic oxygen (without EUV) and 172 nm vacuum ultraviolet (VUV) from an excimer lamp. These experiments suggest that the primary origin of the accelerated erosion of fluorinated polymer observed in a laser detonation atomic oxygen source is not the EUV from the laser-sustained plasma.

  9. One-atom correlated-emission laser RID C-6638-2008 

    E-print Network

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

    2008-01-01

    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...

  10. High power room temperature 1014.8 nm Yb fiber amplifier and frequency quadrupling to 253.7 nm for laser cooling of mercury atoms.

    PubMed

    Hu, Jinmeng; Zhang, Lei; Liu, Hongli; Liu, Kangkang; Xu, Zhen; Feng, Yan

    2013-12-16

    An 8 W continuous wave linearly-polarized single-frequency 1014.8 nm fiber amplifier working at room temperature is developed with commercial double-clad single-mode Yb-doped silica fiber. Re-absorption at the laser wavelength and amplified spontaneous emission at longer wavelength are managed by optimizing the amplifier design. The laser has a linewidth of ~24 kHz without noticeable broadening after amplification. Using two resonant cavity frequency doublers, 1.03 W laser at 507.4 nm and 75 mW laser at 253.7 nm are generated with 4 W 1014.8 nm laser. Both absorption and saturated absorption spectra of the (1)S(0) - (3)P(1) transition of atomic mercury are measured with the 253.7 nm laser. PMID:24514668

  11. A Laser System for the Spectroscopy of Highly-Charged Bismuth Ions

    E-print Network

    S. Albrecht; S. Altenburg; C. Siegel; N. Herschbach; G. Birkl

    2011-08-25

    We present and characterize a laser system for the spectroscopy on highly-charged ^209Bi^82+ ions at a wavelength of 243.87 nm. For absolute frequency stabilization, the laser system is locked to a near-infra-red laser stabilized to a rubidium transition line using a transfer cavity based locking scheme. Tuning of the output frequency with high precision is achieved via a tunable rf offset lock. A sample-and-hold technique gives an extended tuning range of several THz in the UV. This scheme is universally applicable to the stabilization of laser systems at wavelengths not directly accessible to atomic or molecular resonances. We determine the frequency accuracy of the laser system using Doppler-free absorption spectroscopy of Te_2 vapour at 488 nm. Scaled to the target wavelength of 244 nm, we achieve a frequency uncertainty of \\sigma_{244nm} = 6.14 MHz (one standard deviation) over six days of operation.

  12. Photoionization and Velocity Map Imaging spectroscopy of atoms, molecules and clusters with Synchrotron and Free Electron Laser radiation at Elettra

    NASA Astrophysics Data System (ADS)

    Di Fraia, M.; Sergo, R.; Stebel, L.; Giuressi, D.; Cautero, G.; Tudor, M.; Callegari, C.; O'Keeffe, P.; Ovcharenko, Y.; Lyamayev, V.; Feyer, V.; Moise, A.; Devetta, M.; Piseri, P.; Grazioli, C.; Coreno, M.

    2015-12-01

    Advances in laser and Synchrotron Radiation instrumentation are continuously boosting fundamental research on the electronic structure of matter. At Elettra the collaboration between several groups active in the field of atomic, molecular and cluster physics and the Instrumentation and Detector Laboratory has resulted in an experimental set-up that successfully tackles the challenges posed by the investigation of the electronic structure of isolated species in the gas phase. The use of Synchrotron Radiation (SR) and Free Electron Laser (FEL) light, allows to cover a wide spectrum of targets from energetic to dynamics. We developed a Velocity Map Imaging (VMI) spectrometer that allows to perform as well SR as FEL experiments, just by changing part of the detection system. In SR experiments, at the Gasphase beamline of Elettra, a cross delay line detector is used, coupled to a 4-channel time-to-digital converter that reconstructs the position of the electrons. Simultaneously, a Time-of-Flight (TOF) mass spectrometer is used to acquire photoion spectra. Such a system allows PhotoElectron-PhotoIon-Coincidence (PEPICO) spectroscopy of atoms, molecules and clusters. In FEL experiments (notably differing from SR experiments in the much higher rate of events produced and detected, which forces one to forfeit coincidence detection), at the Low Density Matter (LDM) beamline of FERMI, a Micro Channel Plate (MCP) a phosphor screen and a CCD camera are used instead, capable of shot-by-shot collection of practically all events, albeit without time resolution.

  13. 2D laser diagnostics of liquid methanol for investigation of atomization and vaporization dynamics in a burning spray jet

    SciTech Connect

    Bazile, R.; Stepowski, D.

    1994-12-31

    Single-shot planar imaging of Raman scattering of liquid methanol, as well as laser-induced fluorescence of dissolved dye, has been used to investigate atomization and vaporization dynamics in the early stages of a burning spray jet. Within the limited dynamic range of the camera, these linear techniques provide signal levels that are locally proportional to the mass of liquid intercepted by the laser sheet, whereas the techniques based on elastic interactions with the spray could not provide quantifiable data in this region of large size dispersion. High-speed 2D maps of the condensed mass held of the initial jet display the dynamic behavior of the structures induced by different regimes of air-blast atomization. The technique has enabled them to obtain planar instantaneous pictures of the liquid phase velocity field in the early development of the burning spray. When a droplet vaporizes, the signal level on its (blue) Raman image scales as its actual volume d{sup 3}, whereas the signal level on its (red) dye fluorescence image scales as its initial volume d{sub 0}{sup 3}, since the mass of dissolved dye does not vaporize. The comparison of the simultaneous images provides useful information on the vaporization dynamics in the burning spray. The data have been obtained in terms of evaporation constant from size reduction of single droplets or in terms of vaporized mass fraction of injected fuel from integrated measurements.

  14. Determination of the tip temperature in laser assisted atom-probe tomography using charge state distributions

    SciTech Connect

    Marquis, Emmanuelle A.; Gault, Baptiste

    2008-10-15

    The method suggested by Kellogg [J. Appl. Phys. 52, 5320 (1981)] to estimate the temperature of a field emitter under laser pulsing irradiation is reconsidered in the case of a W-Re alloy. It is shown that the temperature obtained using this method is not the absolute temperature, but, if properly calibrated, a value that could be considered as a good approximation of the average temperature reached by the tip when illuminated by picosecond laser pulses.

  15. Enhancement in the number of trapped atoms in a cesium magneto-optical trap by a near-resonant control laser

    SciTech Connect

    Pradhan, S.; Gaur, S. J.; Manohar, K. G.; Jagatap, B. N.

    2005-11-15

    We demonstrate enhancement in the number of trapped cesium atoms in a magneto-optical trap (MOT) using a control laser that illuminates only a small faction of the capture region of the trap without interacting with the cold cloud of atoms. The enhancement is maximized when the laser is slightly blue detuned with respect to the cooling transition. Trap loading curves point to approximately a twofold increase in the capture rate, which as a consequence results in the increase in the steady state number of trapped atoms. Enhanced loading is confirmed by MOT loading and decay curves taken under the modulation of the control laser beam. Optical pumping of the inaccessible Zeeman states into the stretched states is suggested as a possible mechanism.

  16. Beyond the Floquet theorem: generalized Floquet formalisms and quasienergy methods for atomic and molecular multiphoton processes in intense laser fields

    NASA Astrophysics Data System (ADS)

    Chu, Shih-I.; Telnov, Dmitry A.

    2004-02-01

    The advancement of high-power and short-pulse laser technology in the past two decades has generated considerable interest in the study of multiphoton and very high-order nonlinear optical processes of atomic and molecular systems in intense and superintense laser fields, leading to the discovery of a host of novel strong-field phenomena which cannot be understood by the conventional perturbation theory. The Floquet theorem and the time-independent Floquet Hamiltonian method are powerful theoretical framework for the study of bound-bound multiphoton transitions driven by periodically time-dependent fields. However, there are a number of significant strong-field processes cannot be directly treated by the conventional Floquet methods. In this review article, we discuss several recent developments of generalized Floquet theorems, formalisms, and quasienergy methods, beyond the conventional Floquet theorem, for accurate nonperturbative treatment of a broad range of strong-field atomic and molecular processes and phenomena of current interests. Topics covered include (a) artificial intelligence (AI)-most-probable-path approach (MPPA) for effective treatment of ultralarge Floquet matrix problem; (b) non-Hermitian Floquet formalisms and complex quasienergy methods for nonperturbative treatment of bound-free and free-free processes such as multiphoton ionization (MPI) and above-threshold ionization (ATI) of atoms and molecules, multiphoton dissociation (MPD) and above-threshold dissociation (ATD) of molecules, chemical bond softening and hardening, charge-resonance enhanced ionization (CREI) of molecular ions, and multiple high-order harmonic generation (HHG), etc.; (c) many-mode Floquet theorem (MMFT) for exact treatment of multiphoton processes in multi-color laser fields with nonperiodic time-dependent Hamiltonian; (d) Floquet-Liouville supermatrix (FLSM) formalism for exact nonperturbative treatment of time-dependent Liouville equation (allowing for relaxations and dephasing mechanisms) and high-order nonlinear optical processes (such as intensity-dependent nonlinear optical susceptibilities and multiphoton resonance fluorescence, etc.); (e) generalized Floquet approaches for the treatment of nonadiabatic and complex geometric phases involving multiphoton transitions; (f) generalized Floquet techniques for the treatment of multiphoton processes in intense laser pulse fields with nonperiodic time-dependent Hamiltonians; (g) Floquet formulations of time-dependent density functional theory (DFT) and time-dependent current DFT for nonperturbative treatment of multiphoton processes of many-electron quantum systems in periodic or polychromatic ( quasiperiodic) laser fields. For each generalized Floquet approach, we present also the corresponding development of new computational techniques for facilitating the study of strong-field processes and phenomena. The advancement of these generalized Floquet formalisms and quasienergy methods provides powerful new theoretical frameworks and accurate computational methods for nonperturbative and ab initio treatment of a wide range of interesting and challenging laser-induced chemical and physical processes and insightful exploration of strong-field atomic and molecular physics.

  17. Passive atomic frequency standard based on coherent population trapping in {sup 87}Rb using injection-locked lasers

    SciTech Connect

    Moon, Han Seb; Park, Sang Eon; Park, Young-Ho; Lee, Lim; Kim, Jung Bog

    2006-11-15

    We present a microwave frequency standard based on coherent population trapping (CPT) in the {sup 87}Rb D{sub 1} line. The CPT spectrum is obtained using two Raman lasers with a 6.8 GHz frequency offset by injection locking of a master laser to a slave laser. We have constructed an atomic clock employing a 5 cm long Rb vapor cell confined with 6.67 kPa neon buffer gas at 70 degree sign C. Using this system, we improve the CPT contrast through the elimination of undesired off-resonant fields created by the direct modulation method. We measured the frequency shift of the CPT signal as a function of the temperature of the Rb cell and estimated it to be approximately 1.3x10{sup -9}/K. The frequency of a 10 MHz crystal oscillator has been stabilized to the CPT spectrum between the two ground states in {sup 87}Rb. The relative frequency stability is approximately 2.3x10{sup -12} for an average time of 68 s.

  18. Electron collisions with cesium atoms—benchmark calculations and application to modeling an excimer-pumped alkali laser

    NASA Astrophysics Data System (ADS)

    Zatsarinny, Oleg; Bartschat, Klaus; Babaeva, Natalia Yu; Kushner, Mark J.

    2014-06-01

    The B-spline R-matrix (BSR) with pseudostates method is employed to describe electron collisions with cesium atoms. Over 300 states are kept in the close-coupling expansion, including a large number of pseudostates to model the effect of the Rydberg spectrum and, most importantly, the ionization continuum on the results for transitions between the discrete physical states of interest. Predictions for elastic scattering, momentum transfer, excitation and ionization are presented for incident energies up to 200 eV and compared with results from previous calculations and available experimental data. In a second step, the results are used to model plasma formation in an excimer-pumped alkali laser operating on the Cs (62P3/2,1/2 ? 62S1/2) (852 nm and 894 nm) transitions. At sufficiently high operating temperature of a Cs-Ar containing quartz cell, pump power, and repetition rate, plasma formation in excess of 1014-1015 cm-3 occurs. This may reduce laser output power by electron collisional mixing of the upper and lower laser levels.

  19. Evaluation of a Raman Lidar for Atmospheric Water Vapour Profiling

    NASA Astrophysics Data System (ADS)

    Kunz, G. J.; deLeeuw, G.

    2002-04-01

    Knowledge of the vertical profile of atmospheric water vapour is important for predicting atmospheric refraction effects for radar and infrared applications. A model is developed to calculate the performance of a vibrational Raman lidar for measuring vertical profiles of atmospheric water vapour, based on the current transmitter and receiver properties of the TNO-FEL backscatter lidar. Calculations are carried out for the four harmonics of the Nd:YAG laser. These calculations show that maximum ranges of approximately 50 m can be obtained for single shot operation during day time with each of the 532, 355 and 266 nm wavelengths (respectively the second, third and fourth harmonics). The maximum range at the fundamental wavelength is only a few meters due to the limited Raman cross section at this wavelength and the limited sensitivity of the detector at the Raman wavelength. By operating the system under night-time conditions, the maximum range increases to about 160 m. The maximum range could further be improved if noise free amplifiers would be available. It is estimated that the maximum range will increase to 360 m if a pre-amplifier is available with an equivalent noise current of 9. 10-13 W/Hz1/2 and a bandwidth of at least 30 MHz. Larger ranges can be obtained by averaging multiple signals. For increasing the maximum range by a factor of 10, the required number of shots is approximately 10,000, which takes about 10 minutes for a 20 Hz lidar system.

  20. Forbidden atomic transitions driven by an intensity-modulated laser trap.

    PubMed

    Moore, Kaitlin R; Anderson, Sarah E; Raithel, Georg

    2015-01-01

    Spectroscopy is an essential tool in understanding and manipulating quantum systems, such as atoms and molecules. The model describing spectroscopy includes the multipole-field interaction, which leads to established spectroscopic selection rules, and an interaction that is quadratic in the field, which is not often employed. However, spectroscopy using the quadratic (ponderomotive) interaction promises two significant advantages over spectroscopy using the multipole-field interaction: flexible transition rules and vastly improved spatial addressability of the quantum system. Here we demonstrate ponderomotive spectroscopy by using optical-lattice-trapped Rydberg atoms, pulsating the lattice light and driving a microwave atomic transition that would otherwise be forbidden by established spectroscopic selection rules. This ability to measure frequencies of previously inaccessible transitions makes possible improved determinations of atomic characteristics and constants underlying physics. The spatial resolution of ponderomotive spectroscopy is orders of magnitude better than the transition frequency would suggest, promising single-site addressability in dense particle arrays for quantum computing applications. PMID:25600089

  1. A liquid crystalline chirality balance for vapours

    PubMed Central

    Ohzono, Takuya; Yamamoto, Takahiro; Fukuda, Jun-ichi

    2014-01-01

    Chiral discrimination of vapours plays an important role in olfactory perception of biological systems and its realization by artificial sensors has been an intriguing challenge. Here, we report a simple method that tangibly visualizes the chirality of a diverse variety of molecules dissolved from vapours with high sensitivity, by making use of a structural change in a periodic microstructure of a nematic liquid crystal confined in open microchannels. This microstructure is accompanied by a topological line defect of a zigzag form with equal lengths of ‘zig’ and ‘zag.’ We find that a tiny amount of vapour of chiral molecules injected onto the liquid crystal induces the imbalance of ‘zig’ and ‘zag’ depending on its enantiomeric excess within a few seconds. Our liquid-crystal-based ‘chirality balance’ offers a simple, quick and versatile chirality-sensing/-screening method for gas-phase analysis (for example, for odours, environmental chemicals or drugs). PMID:24781531

  2. Computer simulations on resonant fluorescence spectra in atomic gases in two monochromatic laser fields of arbitrary intensity and magnetic field

    NASA Astrophysics Data System (ADS)

    Karagodova, Tamara Y.

    1996-03-01

    In the intense radiation fields with power density from 104W/cm2 to 109W/cm2 the essential modification of electronic states of atoms occurs displaying, in particular, in modifications of resonant fluorescence (rf) spectra. We use 'Fermi golden rule' for calculations of relative intensities and frequencies for rf multiplet for real multilevel initially unexcited atoms in two monochromatic laser fields of arbitrary intensity resonant to adjacent transitions of (Xi) or (Lambda) types and magnetic field, giving the level splittings of different values from Zeeman to Paschen-Back effect. The dependence of quasienergies on parameters obtained with the help of a sorting program permits us to define the values of parameters for which the states of the system are mixed and so to receive the correct probability amplitudes for instantaneous or adiabatic regimes of switching the perturbation. The analysis of the quasienergies and form of rf spectra permits us to get relations between the form of the spectra and modifications of electronic structure of the atom due to radiation fields and external magnetic field.

  3. Characterization of energetic and thermalized sputtered atoms in pulsed plasma using time-resolved tunable diode-laser induced fluorescence

    SciTech Connect

    Desecures, M.; Poucques, L. de; Easwarakhanthan, T.; Bougdira, J.

    2014-11-03

    In this work, a time-resolved tunable diode-laser (DL) induced fluorescence (TR-TDLIF) method calibrated by absorption spectroscopy has been developed in order to determine atom and flux velocity distribution functions (AVDF and FVDF) of the energetic and the thermalized atoms in pulsed plasmas. The experimental set-up includes a low-frequency (?3?Hz) and high spectral-resolution DL (?0.005?pm), a fast rise-time pulse generator, and a high power impulse magnetron sputtering (HiPIMS) system. The induced TR-TDLIF signal is recorded every 0.5??s with a digital oscilloscope of a second-long trace. The technique is illustrated with determining the AVDF and the FVDF of a metastable state of the sputtered neutral tungsten atoms in the HiPIMS post-discharge. Gaussian functions describing the population of the four W isotopes were used to fit the measured TR-TDLIF signal. These distribution functions provide insight into transition from the energetic to thermalized regimes from the discharge onset. This technique may be extended with appropriate DLs to probe any species with rapidly changing AVDF and FVDF in pulsed and strongly oscillating plasmas.

  4. Development of a high-Q superconducting microwave resonator for coupling to trapped laser-cooled atoms

    NASA Astrophysics Data System (ADS)

    Hertzberg, Jared; Voigt, Kristen; Kim, Zaeill; Hoffman, Jonathan; Grover, Jeff; Lee, Jongmin; Solano, Pablo; Budoyo, Rangga; Ballard, Cody; Anderson, James; Lobb, Chris; Orozco, Luis; Rolston, Steven; Wellstood, Frederick

    2014-03-01

    We present progress towards a hybrid quantum system in which microwave quanta may be exchanged between a superconducting qubit and laser-trapped atoms via a magnetic dipole interaction. In initial experiments, we seek to couple a thin-film superconducting LC resonator cooled to 20 mK to the 6.835 GHz hyperfine splitting in an ensemble of optically trapped 87Rb atoms. The atoms will be trapped in the evanescent optical field on the waist of a tapered 500-nm-diameter optical fiber which is moved to within a few microns of the inductor in the LC resonator. Rayleigh scattered light from defects in the optical fiber will impinge on the superconducting device. We describe the resulting effects of absorbed photons and how to minimize optical effects as well as results on positioning the resonator relative to the optical fiber within a dilution refrigerator. Work supported by NSF through the Physics Frontier Center at the Joint Quantum Institute, Dept. of Physics, Univ. of Maryland.

  5. Pulsed hollow-cathode ion lasers: pumping and lasing parameters

    SciTech Connect

    Zinchenko, S P; Ivanov, I G

    2012-06-30

    Optimal discharge conditions have been experimentally found for ion lasers excited in the hollow-cathode discharge plasma by microsecond current pulses by pumping working atoms in secondkind collisions with ions and metastable buffer-gas atoms. Measurements of the output power of krypton ion and zinc-, cadmium-, mercury-, thallium-, copper-, and gallium-vapour lasers in tubes with cathodes of different diameters showed that the pulse power reaches several tens of watts, and the average power obtained with cathodes 2 cm in diameter and a length of 40 cm or more approaches 1 W. Lasing in most media is observed simultaneously at several lines (the multi-wavelength regime). Lasing on a three-component (He - Kr - Hg) mixture is realised in the multi-wavelength regime at blue, red, and IR lines.

  6. Production mechanism of atomic nitrogen in atmospheric pressure pulsed corona discharge measured using two-photon absorption laser-induced fluorescence

    SciTech Connect

    Teramoto, Yoshiyuki; Ono, Ryo; Oda, Tetsuji

    2012-06-01

    To study the production mechanism of atomic nitrogen, the temporal profile and spatial distribution of atomic nitrogen are measured in atmospheric pressure pulsed positive corona discharge using two-photon absorption laser-induced fluorescence. The absolute atomic nitrogen density in the streamer filaments is estimated from decay rate of atomic nitrogen in N{sub 2} discharge. The results indicate that the absolute atomic nitrogen density is approximately constant against discharge energy. When the discharge voltage is 21.5 kV, production yield of atomic nitrogen produced by an N{sub 2} discharge pulse is estimated to be 2.9 - 9.8 Multiplication-Sign 10{sup 13} atoms and the energy efficiency of atomic nitrogen production is estimated to be about 1.8 - 6.1 Multiplication-Sign 10{sup 16} atoms/J. The energy efficiency of atomic nitrogen production in N{sub 2} discharge is constant against the discharge energy, while that in N{sub 2}/O{sub 2} discharge increases with discharge energy. In the N{sub 2}/O{sub 2} discharge, two-step process of N{sub 2} dissociation plays significant role for atomic nitrogen production.

  7. Method using laser irradiation for the production of atomically clean crystalline silicon and germanium surfaces

    DOEpatents

    Ownby, Gary W. (Knoxville, TN); White, Clark W. (Oak Ridge, TN); Zehner, David M. (Lenoir City, TN)

    1981-01-01

    This invention relates to a new method for removing surface impurities from crystalline silicon or germanium articles, such as off-the-shelf p- or n-type wafers to be doped for use as junction devices. The principal contaminants on such wafers are oxygen and carbon. The new method comprises laser-irradiating the contaminated surface in a non-reactive atmosphere, using one or more of Q-switched laser pulses whose parameters are selected to effect melting of the surface without substantial vaporization thereof. In a typical application, a plurality of pulses is used to convert a surface region of an off-the-shelf silicon wafer to an automatically clean region. This can be accomplished in a system at a pressure below 10.sup.-8 Torr, using Q-switched ruby-laser pulses having an energy density in the range of from about 60 to 190 MW/cm.sup.2.

  8. Experimental and theoretical investigation of a coaxial pumped photolytic atomic bromine laser

    SciTech Connect

    Rafferty, B.D.; Anderson, B.T.; Glassman, J.; Miller, H.C.; Hager, G.D.; Lampson, A.I.

    1997-05-01

    This paper describes the results from a combined experimental/theoretical investigation of a coaxial pumped photolytic bromine laser. A 532-nm pump was used to photodissociate IBr and produce Br*({sup 2}P{sub 1/2}) with subsequent lasing on the ({sup 2}P{sub 1/2}) {yields} ({sup 2}P{sub 3/2}) transition. Experimental results are presented for output energy, mode buildup time and small-signal gain as a function of pump energy and mirror outcoupling fraction. A simplified rate equation model was developed to predict the laser performance parameters and shows goods agreement with the laser output energy and small-signal gain.

  9. Chemical vapour deposition synthetic diamond: materials, technology and applications

    NASA Astrophysics Data System (ADS)

    Balmer, R. S.; Brandon, J. R.; Clewes, S. L.; Dhillon, H. K.; Dodson, J. M.; Friel, I.; Inglis, P. N.; Madgwick, T. D.; Markham, M. L.; Mollart, T. P.; Perkins, N.; Scarsbrook, G. A.; Twitchen, D. J.; Whitehead, A. J.; Wilman, J. J.; Woollard, S. M.

    2009-09-01

    Substantial developments have been achieved in the synthesis of chemical vapour deposition (CVD) diamond in recent years, providing engineers and designers with access to a large range of new diamond materials. CVD diamond has a number of outstanding material properties that can enable exceptional performance in applications as diverse as medical diagnostics, water treatment, radiation detection, high power electronics, consumer audio, magnetometry and novel lasers. Often the material is synthesized in planar form; however, non-planar geometries are also possible and enable a number of key applications. This paper reviews the material properties and characteristics of single crystal and polycrystalline CVD diamond, and how these can be utilized, focusing particularly on optics, electronics and electrochemistry. It also summarizes how CVD diamond can be tailored for specific applications, on the basis of the ability to synthesize a consistent and engineered high performance product.

  10. Atom Interferometers

    E-print Network

    Alexander D. Cronin; Joerg Schmiedmayer; David E. Pritchard

    2007-12-21

    Interference with atomic and molecular matter waves is a rich branch of atomic physics and quantum optics. It started with atom diffraction from crystal surfaces and the separated oscillatory fields technique used in atomic clocks. Atom interferometry is now reaching maturity as a powerful art with many applications in modern science. In this review we first describe the basic tools for coherent atom optics including diffraction by nanostructures and laser light, three-grating interferometers, and double wells on AtomChips. Then we review scientific advances in a broad range of fields that have resulted from the application of atom interferometers. These are grouped in three categories: (1) fundamental quantum science, (2) precision metrology and (3) atomic and molecular physics. Although some experiments with Bose Einstein condensates are included, the focus of the review is on linear matter wave optics, i.e. phenomena where each single atom interferes with itself.

  11. Spinor atom-molecule conversion via laser-induced three-body recombination

    SciTech Connect

    Jing, H.; Deng, Y.; Meystre, P.

    2011-04-15

    We study the theory of several aspects of the dynamics of coherent atom-molecule conversion in spin-one Bose-Einstein condensates. Specifically, we discuss how, for a suitable dark-state condition, the interplay of spin-exchange collisions and photo association leads to the stable creation of an atom-molecule pair from three initial spin-zero atoms. This process involves two two-body interactions and can be intuitively viewed as an effective three-body recombination. We investigate the relative roles of photo association and of the initial magnetization in the 'resonant' case, where the dark-state condition is perfectly satisfied. We also consider the 'nonresonant' case, where that condition is satisfied either only approximately - the so-called adiabatic case - or not at all. In the adiabatic case, we derive an effective nonrigid pendulum model that allows one to conveniently discuss the onset of an antiferromagnetic instability in an 'atom-molecule pendulum', as well as large-amplitude pair oscillations and atom-molecule entanglement.

  12. Selection and amplification of a single optical frequency comb mode for laser cooling of the strontium atoms in an optical clock

    NASA Astrophysics Data System (ADS)

    Liu, Hui; Yin, Mojuan; Kong, Dehuan; Xu, Qinfang; Zhang, Shougang; Chang, Hong

    2015-10-01

    In this paper, we report on the active filtering and amplification of a single mode from an optical femtosecond laser comb with mode spacing of 250 MHz by optical injection of two external-cavity diode lasers operating in cascade to build a narrow linewidth laser for laser cooling of the strontium atoms in an optical lattice clock. Despite the low injection of individual comb mode of approximately 50 nW, a single comb line at 689 nm could be filtered and amplified to reach as high as 10 mW with 37 dB side mode suppression and a linewidth of 240 Hz. This method could be applied over a broad spectral band to build narrow linewidth lasers for various applications.

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

    E-print Network

    Grütter, Peter

    sensors L. Y. Beaulieua Department of Physics and Physical Oceanography, Memorial University, St. John and cantilever-based sensors use an optical laser beam detection system to monitor cantilever deflections. We-based sensors both rely on converting a cantilever deflection into a physical quantity. For example, force

  14. Analysis of atomic and ion debris features of laser-produced Sn and Li plasmas

    E-print Network

    Harilal, S. S.

    Environment, Purdue University, West Lafayette, Indiana 47907, USA Received 3 May 2010; accepted 5 August 2010-doped yttrium aluminum garnet laser pulses for producing plasmas. A suite of diagnostics were used to analyze width,13 spot size,14 power density,15,16 etc. and target mass density,15 target geometry,16 etc

  15. Measurement method for the nuclear anapole moment of laser trapped alkali atoms

    E-print Network

    Gómez, E; Sprouse, G D; Orozco, L A; De Mille, D P

    2004-01-01

    Weak interactions within a nucleus generate a nuclear spin dependent parity violating electromagnetic moment; the anapole moment. In heavy nuclei, the anapole moment is the dominant contribution to spin-dependent atomic parity violation. We analyze a method to measure the nuclear anapole moment through the electric dipole transition it induces between hyperfine states of the ground level. The method requires tight confinement of the atoms to position them at the anti-node of a standing wave driving the anapole-induced E1 transiton. We explore the necessary limits in the number of atoms, excitation fields, trap type, interrogation method, and systematic tests necessary for such measurements in francium, the heaviest alkali.

  16. Investigation of broadening and shift of vapour absorption lines of H{sub 2}{sup 16}O in the frequency range 7184 – 7186 cm{sup -1}

    SciTech Connect

    Nadezhdinskii, A I; Pereslavtseva, A A; Ponurovskii, Ya Ya

    2014-10-31

    We present the results of investigation of water vapour absorption spectra in the 7184 – 7186 cm{sup -1} range that is of particular interest from the viewpoint of possible application of the data obtained for monitoring water vapour in the Earth's stratosphere. The doublet of H{sub 2}{sup 16}O near ? = 7185.596 cm{sup -1} is analysed. The coefficients of broadening and shift of water vapour lines are found in the selected range in mixtures with buffer gases and compared to those obtained by other authors. (laser spectroscopy)

  17. Laser spectroscopy of thulium atoms implanted in liquid and solid {sup 4}He

    SciTech Connect

    Ishikawa, K.; Hatakeyama, A.; Gosyono-o, K.; Wada, S.; Takahashi, Y.; Yabuzaki, T.

    1997-07-01

    The excitation, emission spectra, and decay curves of the emission intensity of thulium atoms implanted in liquid and solid helium were observed in the presence and absence of an external magnetic field. The observed narrow line (width {approximately}0.1 nm) of the excitation spectrum at 590.60 nm is assigned as a zero-phonon transition from the electronic ground state 4f{sup 13}({sup 2}F{sub 7/2}{sup o})6s{sup 2}, which indicates that the transition between the inner shells is weakly perturbed by surrounding helium atoms. The pressure dependence of the emission wavelength suggests that the symmetry of helium atoms distributed around a thulium atom in the solid phase is similar to that in the liquid phase. The emission intensity was stable and large in the solid phase since thulium atoms were trapped at a density of 10{sup 10}{endash}10{sup 11} atoms/cm{sup 3}. The lifetime of the excited state was measured to be 7.09{plus_minus}0.04 {mu}s, which was longer than that of the 4f{sup 12}({sup 3}H{sub 6})5d{sub 5/2}6s{sup 2} (6,5/2){sub 7/2} state of free thulium atoms. The excited state is expected to be a mixed state of the 4f{sup 12}5d6s{sup 2} and 4f{sup 13}6s6p configurations. The metastable state 4f{sup 13}({sup 2}F{sub 5/2}{sup o})6s{sup 2} is populated by a radiative transition from this excited state and relaxes to the ground state through a magnetic dipole transition. The lifetime of the metastable state of a neutral thulium atom was measured to be 75{plus_minus}3 ms. {copyright} {ital 1997} {ital The American Physical Society}

  18. Measurement method for the nuclear anapole moment of laser-trapped alkali-metal atoms

    SciTech Connect

    Gomez, E.; Aubin, S.; Sprouse, G. D.; Orozco, L. A.; DeMille, D. P.

    2007-03-15

    Weak interactions within a nucleus generate a nuclear spin dependent, parity-violating electromagnetic moment, the anapole moment. We analyze a method to measure the nuclear anapole moment through the electric dipole transition it induces between hyperfine states of the ground level. The method requires tight confinement of the atoms to position them at the antinode of a standing wave Fabry-Perot cavity driving the anapole-induced microwave E1 transition. We explore the necessary limits in the number of atoms, excitation fields, trap type, interrogation method, and systematic tests necessary for such measurements in francium, the heaviest alkali.

  19. Saturated Vapour Pressure and Refrigeration - Part I

    ERIC Educational Resources Information Center

    Bunker, C. A.

    1973-01-01

    The first part of a two-part article describes an experimental approach that can be used in teaching the concept of saturated vapour pressure. This leads to a discussion of refrigeration cycles in the second part of the article. (JR)

  20. Reaction of Laser-Ablated Uranium and Thorium Atoms with H2Se: A Rare Example of Selenium Multiple Bonding.

    PubMed

    Vent-Schmidt, Thomas; Andrews, Lester; Thanthiriwatte, K Sahan; Dixon, David A; Riedel, Sebastian

    2015-10-19

    The compounds H2ThSe and H2USe were synthesized by the reaction of laser-ablated actinide metal atoms with H2Se under cryogenic conditions following the procedures used to synthesize H2AnX (An = Th, U; X = O, S). The molecules were characterized by infrared spectra in an argon matrix with the aid of deuterium substitution and electronic structure calculations at the density functional theory level. The main products, H2ThSe and H2USe, are shown to have a highly polarized actinide-selenium triple bond, as found for H2AnS on the basis of electronic structure calculations. There is an even larger back-bonding of the Se with the An than found for the corresponding sulfur compounds. These molecules are of special interest as rare examples of multiple bonding of selenium to a metal, particularly an actinide metal. PMID:26418218

  1. Coupling laser ablation and atomic fluorescence spectrophotometry: an example using mercury analysis of small sections of fish scales.

    PubMed

    Beaudin, Luc; Johannessen, Sophia C; Macdonald, Robie W

    2010-11-01

    Mercury is a toxic element that exchanges among air, water, and sediments and biomagnifies into high trophic level organisms. Here, we present a novel combination of laser ablation with relatively low-cost cold vapor atomic fluorescence spectrophotometry to analyze Hg vaporized from targeted patches of fish scale 300-500 ?m square. This method permits the analysis of multiple samples from the same scale, which is useful, because fish scale growth rings may provide an archive from which spatial and temporal trends in environmental Hg can be inferred at fine resolution. The detection limit of the method is 1.5 pg Hg, with a precision of 0.1 pg/?L. Developed using fish scales, the method could be adapted to other media, such as baleen, shells, nails, hair, teeth, wood and, possibly, varved sediments. PMID:20942426

  2. Bose-Einstein condensate. To photograph the pulse, we selectively image 12) atoms in the cloud with the 'imaging' laser beam shown

    E-print Network

    Hau, Lene Vestergaard

    . The transverse width ofthe probe laser beam (in the x-y plane) is larg- er than the size ofthe condensate density in the middle ofthe clQud. Stopped light Because ofthe aforementioned spatial compression emission. If instead, 12)hadbeen reachedvia spontaneous,incoherent emission from 13),the two ejected atom

  3. Bose-Einstein condensation of a system of two-level atoms in resonant interaction with a single-running-wave-mode laser field 

    E-print Network

    Wang, Xinfeng

    2001-01-01

    In this thesis, we study the influence of a single-running-wave-mode laser field to the critical temperature T[] of Bose-Einstein condensation(BEC) of a system of two-level bosonic atoms. Using a simple model, we obtain the dispersion relation...

  4. 10. Jones, B., Ghose, S., Clemens, J. P., Rice, P. R. & Pedrotti, L. M. Photon statistics of a single atom laser. Phys. Rev. A 60, 32673275 (1999).

    E-print Network

    Zaanen, Jan

    1999-01-01

    3737 (1996). 30. Corwin, K. L., Kuppens, S. J. M., Cho, D. & Wieman, C. E. Spin-polarized atoms cavity. Phys. Rev. Lett. 90, 133602 (2003). 13. Sargent, M. III, Scully, M. O. & Lamb, W. E. Jr Laser. Mandel, L. & Wolf, E. Optical Coherence and Quantum Optics (Cambridge Univ. Press, Cambridge, 1995). 16

  5. Candidates for laser cooling of atomic anions: La{sup -} versus Os{sup -}

    SciTech Connect

    Pan, Lin; Beck, Donald R.

    2010-07-15

    This brief report is a follow-up to the recent proposal to use La{sup -} as another candidate, in addition to Os{sup -}, in laser cooling of anions, which can then be used to cool antiprotons sympathetically. Using the relativistic configuration interaction formalism, we calculate the photodetachment cross sections of the upper laser cooling state La{sup -} 5d6s{sup 2}6p {sup 3}D{sub 1} and Os{sup -} 5d{sup 6}6s{sup 2}6p {sup 6}D{sub 9/2}. Our results show that La{sup -} has a very similar two-photon detachment loss as Os{sup -}, retaining it as another promising candidate for cooling antiprotons sympathetically.

  6. Laser crystallization of amorphous silicon films investigated by Raman spectroscopy and atomic force microscopy

    NASA Astrophysics Data System (ADS)

    Jin, Jing; Yuan, Zhijun; Huang, Lu; Chen, Sheng; Shi, Weimin; Cao, Zechun; Lou, Qihong

    2010-03-01

    The intrinsic and phosphorous (P)-doped hydrogenated amorphous silicon thin films were crystallized by laser annealing. The structural properties during crystallization process can be investigated. Observed redshifts of the Si Raman transverse optical phonon peak indicate tensile stress present in the films and become intense with the effect of doping, which can be relieved in P-doped films by introducing buffer layer structures. Based on experimental results, the established correlation between the stress and crystalline fraction ( XC) suggests that the relatively high stress can limit the increase in XC and the highest crystalline fraction is obtained by a considerable stress release. At high laser energy density of 1250 mJ/cm 2, the poorer crystalline quality and disordered structure of the film originating from the irradiation damage and defects lead to the low electron mobility.

  7. Application of atomic vapor laser isotope separation to the enrichment of mercury

    SciTech Connect

    Crane, J.K.; Erbert, G.V.; Paisner, J.A.; Chen, H.L.; Chiba, Z.; Beeler, R.G.; Combs, R.; Mostek, S.D.

    1986-09-01

    Workers at GTE/Sylvania have shown that the efficiency of fluorescent lighting may be markedly improved using mercury that has been enriched in the /sup 196/Hg isotope. A 5% improvement in the efficiency of fluorescent lighting in the United States could provide a savings of approx. 1 billion dollars in the corresponding reduction of electrical power consumption. We will discuss the results of recent work done at our laboratory to develop a process for enriching mercury. The discussion will center around the results of spectroscopic measurements of excited state lifetimes, photoionization cross sections and isotope shifts. In addition, we will discuss the mercury separator and supporting laser mesurements of the flow properties of mercury vapor. We will describe the laser system which will provide the photoionization and finally discuss the economic details of producing enriched mercury at a cost that would be attractive to the lighting industry.

  8. Electronic and atomic kinetics in solids irradiated with free-electron lasers or swift-heavy ions

    NASA Astrophysics Data System (ADS)

    Medvedev, N.; Volkov, A. E.; Ziaja, B.

    2015-12-01

    In this brief review we discuss the transient processes in solids under irradiation with femtosecond X-ray free-electron-laser (FEL) pulses and swift-heavy ions (SHI). Both kinds of irradiation produce highly excited electrons in a target on extremely short timescales. Transfer of the excess electronic energy into the lattice may lead to observable target modifications such as phase transitions and damage formation. Transient kinetics of material excitation and relaxation under FEL or SHI irradiation are comparatively discussed. The same origin for the electronic and atomic relaxation in both cases is demonstrated. Differences in these kinetics introduced by the geometrical effects (?m-size of a laser spot vs nm-size of an ion track) and initial irradiation (photoabsorption vs an ion impact) are analyzed. The basic mechanisms of electron transport and electron-lattice coupling are addressed. Appropriate models and their limitations are presented. Possibilities of thermal and nonthermal melting of materials under FEL and SHI irradiation are discussed.

  9. Unified understanding of tunneling ionization and stabilization of atomic hydrogen in circularly and linearly polarized intense laser fields

    SciTech Connect

    Miyagi, Haruhide; Someda, Kiyohiko

    2010-07-15

    On the basis of the Floquet formalism, the ionization mechanisms of atomic hydrogen in circularly and linearly polarized intense laser fields are discussed. By using the complex scaling method in the velocity gauge, the pole positions of the scattering-matrix on the complex quasienergy Riemann surface are calculated, and pole trajectories with respect to the variation of the laser intensity are obtained. In the low-frequency regime, the pole trajectory exhibits a smooth ponderomotive energy shift in the case of circular polarization. In contrast, the smoothness is lost in the case of linear polarization. In the high-frequency regime, the pole trajectories exhibit the stabilization phenomenon for both the types of polarization. These observations are elucidated by a unified picture based on the analysis of the adiabatic potentials for the radial motion of the electron in the acceleration gauge. The ionization in the case of circular polarization of the low-frequency regime is governed by the electron tunneling through a barrier of a single adiabatic potential. The stabilization in the high-frequency regime can be explained by the change in the avoided crossings among the adiabatic potential curves. The transition between the different frequency regimes is explicable by the change in the structure of the adiabatic potentials. The difference caused by the type of polarization is ascribable to the difference in the space-time symmetry.

  10. Nonsequential Double Ionization of Atoms in Strong Laser Field: Identifying the Mechanisms behind the Correlated-Electron Momentum Spectra

    NASA Astrophysics Data System (ADS)

    Ye, Difa; Fu, Libin; Liu, Jie

    Within the strong-field physics community, there has been increasing interest on nonsequential double ionization (NSDI) induced by electron-electron (e-e) correlation. A large variety of novel phenomena has been revealed in experiments during the past decades. However, the theoretical understanding and interpretation of this process is still far from being complete. The most accurate simulation, i.e. the exact solution of the time-dependent Schrödinger equation (TDSE) for two electrons in a laser field is computationally expensive. In order to overcome the difficulty, we proposed a feasible semiclassical model, in which we treat the tunneling ionization of the outmost electron quantum mechanically according to the ADK theory, sample the inner electron from microcanonical distribution and then evolve the two electrons with Newton's equations. With this model, we have successfully explained various NSDI phenomena, including the excessive DI yield, the energy spectra and angular distribution of photoelectrons. Very recently, it is adopted to reveal the physical mechanisms behind the fingerlike structure in the correlated electron momentum spectra, the unexpected correlation-anticorrelation transition close to the recollision threshold, and the anomalous NSDI of alkaline-earth-metal atoms in circularly polarized field. The obvious advantage of our model is that it gives time-resolved insights into the complex dynamics of NSDI, from the turn-on of the laser field to the final escape of the electrons, thus allowing us to disentangle and thoroughly analyze the underlying physical mechanisms.

  11. Double resonance laser-induced fluorescence of Cadmium and Zinc in the inductively coupled plasma and electrothermal atomizer

    NASA Astrophysics Data System (ADS)

    Ezer, M.; Pacquette, H. L.; Simeonsson, J. B.

    1999-11-01

    Double resonance laser-induced fluorescence (LIF) spectrometry studies of Zn and Cd have been performed in the inductively coupled plasma (ICP) and electrothermal atomizer (ETA). Stepwise excitation of Zn is accomplished at 213.856 nm and 636.235 nm with fluorescence emissions observed near 334.5 nm. Excitation of Cd is accomplished at 228.802 nm and 643.847 nm with fluorescence emissions observed near 361.1 nm and 347.6 nm. Calibration studies demonstrate that the double resonance LIF approaches provide high sensitivity and linearity over several orders of magnitude in both atomizers. Limits of detection for Zn and Cd in the ICP are 1.7 ng/ml and 5 ng/ml, respectively. Excellent sensitivity is observed in the ETA resulting in limits of detection of 70 pg/ml (700 fg absolute mass) and 4 pg/ml (40 fg absolute mass) for Zn and Cd, respectively. The Zn content of a bovine serum standard reference material (NIST SRM #1598) has been determined by ETA-LIF and found to be 940±60 ng/g, which is in very good agreement with the certified value of 890±60 ng/g. Low-level ETA-LIF measurements of Zn in these studies are strongly limited by the high background level observed for this element.

  12. Repumping and spectroscopy of laser-cooled Sr atoms using the (5s5p)3P2-(5s4d)3D2 transition

    NASA Astrophysics Data System (ADS)

    Mickelson, P. G.; Martinez de Escobar, Y. N.; Anzel, P.; De Salvo, B. J.; Nagel, S. B.; Traverso, A. J.; Yan, M.; Killian, T. C.

    2009-12-01

    We describe repumping and spectroscopy of laser-cooled strontium (Sr) atoms using the (5s5p)3P2-(5s4d)3D2 transition. Atom number in a magneto-optical trap is enhanced by driving this transition because Sr atoms that have decayed into the (5s5p)3P2 dark state are repumped back into the (5s2)1S0 ground state. Spectroscopy of 84Sr, 86Sr, 87Sr and 88Sr improves the value of the (5s5p)3P2-(5s4d)3D2 transition frequency and determines the isotope shifts for the transition accurately enough to guide laser-cooling experiments with less abundant isotopes.

  13. Outer-shell excitation mechanisms and static-mode laser-fluorescence spectroscopy of sputtered atoms

    SciTech Connect

    Gruen, D.M.; Pellin, M.J.; Young, C.E.; Mendelsohn, M.H.; DeWald, A.B.

    1982-01-01

    A review of the literature on atoms sputtered in electronically excited states is given together with a discussion of various mechanisms that have been proposed to account for the observations. The major observational features that have emerged from the older studies may be summarized as follows: (1) the kinetic energies of neutral atoms in highly excited electronic states are 1-2 orders of magnitude greater than E/sub b/, the surface binding energy; (2) relative yields show approximately exponential dependence on excitation energy with characteristic temperatures measured in thousands of degrees; (43) absolute yields are lower by 2-3 orders of magnitude than secondary ion yields which themselves are usually very small compared to total sputtering yields. In many cases, excited-state yields increase 1-2 orders of magnitude as a result of surface oxidation. 83 references.

  14. Radioactive ion beam transportation for the fundamental symmetry study with laser-trapped atoms

    NASA Astrophysics Data System (ADS)

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

    2014-02-01

    The search for the violation of the fundamental symmetry in a radioactive atom is the promising candidate for precision tests of the standard model and its possible extensions. The subtle signal arising from the symmetry violation is enhanced in heavy atoms, such as a francium (Fr). To realize high precision measurements, a large amount of radioactive isotopes is required. The Fr is produced via a nuclear fusion reaction using a melted gold target with a 18O primary beam at Cyclotron and Radioisotope Center, Tohoku University. The maximum extraction efficiency of the Fr ion was achieved at approximately 35%. The beam line consists of an electrostatic deflector, three electrostatic quadrupole triplets to the measurement area at 10 m away from the reaction point, and several beam diagnosis systems. We optimized parameters of the beam line.

  15. Radioactive ion beam transportation for the fundamental symmetry study with laser-trapped atoms.

    PubMed

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

    2014-02-01

    The search for the violation of the fundamental symmetry in a radioactive atom is the promising candidate for precision tests of the standard model and its possible extensions. The subtle signal arising from the symmetry violation is enhanced in heavy atoms, such as a francium (Fr). To realize high precision measurements, a large amount of radioactive isotopes is required. The Fr is produced via a nuclear fusion reaction using a melted gold target with a (18)O primary beam at Cyclotron and Radioisotope Center, Tohoku University. The maximum extraction efficiency of the Fr ion was achieved at approximately 35%. The beam line consists of an electrostatic deflector, three electrostatic quadrupole triplets to the measurement area at 10 m away from the reaction point, and several beam diagnosis systems. We optimized parameters of the beam line. PMID:24593466

  16. Radioactive ion beam transportation for the fundamental symmetry study with laser-trapped atoms

    SciTech Connect

    Arikawa, Hiroshi Ando, S.; Aoki, T.; Ezure, S.; Harada, K.; Hayamizu, T.; Inoue, T.; Ishikawa, T.; Itoh, M.; Kawamura, H.; Kato, K.; Kato, T.; Uchiyama, A.; Sakemi, Y.; Aoki, T.; Furukawa, T.; Hatakeyama, A.; Hatanaka, K.; Yoshida, H. P.; Imai, K.; and others

    2014-02-15

    The search for the violation of the fundamental symmetry in a radioactive atom is the promising candidate for precision tests of the standard model and its possible extensions. The subtle signal arising from the symmetry violation is enhanced in heavy atoms, such as a francium (Fr). To realize high precision measurements, a large amount of radioactive isotopes is required. The Fr is produced via a nuclear fusion reaction using a melted gold target with a {sup 18}O primary beam at Cyclotron and Radioisotope Center, Tohoku University. The maximum extraction efficiency of the Fr ion was achieved at approximately 35%. The beam line consists of an electrostatic deflector, three electrostatic quadrupole triplets to the measurement area at 10 m away from the reaction point, and several beam diagnosis systems. We optimized parameters of the beam line.

  17. An 8-{mu}m quantum cascade laserproduced by the metalorganic vapour phase epitaxy method

    SciTech Connect

    Zasavitskii, I I; Pashkeev, D A; Marmalyuk, Aleksandr A; Ryaboshtan, Yu L; Mikaelyan, G T

    2010-02-28

    An 8-{mu}m quantum cascade laser is fabricated by the metalorganic vapour phase epitaxy method. A scheme of vertical transitions in a structure consisting of three quantum wells is used. The laser operates in a pulsed regime at temperatures up to 250 K. The threshold current density was about 3 kA cm{sup -2} and increased up to 6 kA cm{sup -2} at 250 K. The 1-{mu}s pulse power in the multimode regime was 45 mW at 77 K.

  18. Narrow linewidth, high-power Al-free active region (? = 852nm) DFB laser diodes for atomic clocks and interferometry applications

    NASA Astrophysics Data System (ADS)

    Ligeret, V.; Vermersch, F. J.; Bansropun, S.; Lecomte, M.; Calligaro, M.; Parillaud, O.; Krakowski, M.

    2007-02-01

    Single frequency and single spatial mode diode lasers emitting at 852nm are strategic components for systems such as atomic clocks (positioning systems for navigation, in space atomic clock like Galileo or Pharao (cold atom), measurement of fundamental constants), or interferometry applications. We have developed the technological foundations of lasers at 852nm to address these different applications. These include an Al free active region, a single spatial mode ridge waveguide and a DFB (distributed feedback) structure. The device is a separate confinement heterostructure with a GaInP large optical cavity and a single compressive strained GaInAsP quantum well. For an AR-HR coated ridge Fabry Perot laser, we obtain a power of 230mW with M2=1.3. An optical power of 150mW was obtained at 854nm, 20°C for AR-HR coated devices. We obtain a single spatial mode emission and a SMSR over 50dB, both at 150mW. DFB Lasers at 852.12nm, corresponding to the D2 caesium transition, were then realised with a power of 40mW per facet, 37°C for uncoated devices. At 40mW, we determine a M2 value of 1.3. We measure a SMSR value around 50dB between 10°C and 80°C. On this last laser run, we obtain very homogeneous spectral linewidth values for five different lasers, measured with a Fabry Perot interferometer. We obtain at 20°C a low average linewidth value of 1.40MHz and 1.10MHz at respectively 40mW and 20mW, together with a low standard deviation of 0.1MHz. At 852.12nm (37°C, 40mW), a low linewidth value of 1MHz was measured, for one laser preliminary tested.

  19. Three-photon resonance ionization of atomic Mn in a hot-cavity laser ion source using Ti:sapphire lasers

    NASA Astrophysics Data System (ADS)

    Liu, Y.; Gottwald, T.; Mattolat, C.; Wendt, K.

    2015-06-01

    Three-photon resonance ionization of atomic manganese (Mn) in a hot-cavity ion source using Ti:sapphire lasers has been demonstrated. Three-step ionization schemes employing different intermediate levels and Rydberg or autoionizing (AI) states in the final ionization step are established. Strong AI resonances were observed via the 3d54s5s f 6S5/2 level at 49 415.35 cm-1, while Rydberg transitions were reached from the 3d54s4d e 6D9/2,7/2,5/2 levels at around 47 210 cm-1. Analyses of the strong Rydberg transitions associated with the 3d54s4d e 6D7/2 lower level indicate that they belong to the dipole-allowed 4d ? nf 6F°9/2,7/2,5/2 series converging to the 3d54s 7S3 ground state of Mn II. From this series, an ionization potential of 59 959.56 ± 0.01 cm-1 is obtained for Mn. At high ion source temperatures the semi-forbidden 4d ? nf 8F°9/2,7/2,5/2 series was also observed. The overall ionization efficiency for Mn has been measured to be about 0.9% when using the strong AI transition in the third excitation step and 0.3% when employing an intense Rydberg transition. Experimental data indicate that the ionization efficiency was limited by the interaction of Mn atoms with ion source materials at high temperatures.

  20. Determination of transient atomic structure of laser-excited materials from time-resolved diffraction data

    SciTech Connect

    Giret, Yvelin; Department of Physics and Astronomy, University College London, Gower Street, WC1E 6BT London ; Naruse, Nobuyasu; Murooka, Yoshie; Yang, Jinfeng; Tanimura, Katsumi; Daraszewicz, Szymon L.; Duffy, Dorothy M.; Shluger, Alexander L.

    2013-12-16

    The time evolution of the Bragg peaks of photo-excited gold nanofilms is measured using transmission ultrafast electron diffraction (UED) with 3.0 MeV electron pulses and the corresponding structure evolution is calculated using two-temperature molecular dynamics (2T-MD). The good agreement obtained between the measured and calculated Bragg peaks, over the full experimental timescale, enables the lattice temperature effects and the structural changes to be disentangled for the first time. The agreement demonstrates that 2T-MD is a reliable method for solving the inverse problem of structure determination of laser irradiated metals in UED measurements.