Sample records for atomic vapour laser

  1. Subpicotesla atomic magnetometry with a microfabricated vapour cell

    E-print Network

    Bentz, Dale P.

    magnetometers7,8 , based on the precession of the spins of alkali atoms in the vapour phase, could achieve-scale microfabricated alkali vapour cell with sensitivity below 70 fT Hz21/2 . Additionally, we use a simplified optical configuration that requires only a single low-power laser. This result suggests that millimetre-scale, low

  2. Metal Vapour Lasers: Physics, Engineering and Applications

    NASA Astrophysics Data System (ADS)

    Little, Christopher E.

    1999-03-01

    Metal Vapour Lasers Christopher E. Little University of St Andrews, St Andrews, Scotland Since the first successful demonstration of a metal vapour laser (MVL) in 1962, this class of laser has become widely used in a broad range of fields including precision materials processing, isotope separation and medicine. The MVLs that are used today have a range of impressive characteristics that are not readily available using other technologies. In particular, the combination of high average output powers, pulse recurrence frequencies and beam quality available from green/yellow Cu vapour lasers (CVLs) and Cu bromide lasers, coupled with the high-quality, multiwatt ultraviolet (265-289 nm) radiation that can be produced using simple nonlinear optical techniques, means that Cu lasers will continue to be important for many years. Metal Vapour Lasers covers all the most commercially important and scientifically interesting pulsed and continuous wave (CW) gas-discharge MVLs, and includes device histories, operating characteristics, engineering, kinetics, commercial exploitation and applications. Short descriptions of gas discharges and excitation techniques make this volume self-consistent. A comprehensive bibliography is also provided. The greater part of this book is devoted to CVLs and their variants, including new sealed-off, high-power 'kinetically enhanced' CVLs and Cu bromide lasers. However, many other self-terminating MVLs are also discussed, including the red AuVL, green/infrared MnVL and infrared BaVL. Pulsed, high-gain, high average power lasers in the UV/violet (373.7, 430.5 nm) spectral regions are represented by Sr¯+ and Ca¯+ discharge-afterglow recombination lasers. The most commercially successful of the MVLs - the CW, UV/blue cataphoretic He-Cd¯+ ion laser - is described. Hollow cathode lasers are represented in two guises: 'white light' (blue/green/red) He-Cd¯+ ion lasers and UV/infrared Ne/He-Cu¯+ ion lasers. This unique volume is an essential reference source for all those working on metal vapour lasers, and all those who use them, from postgraduate students through to experienced scientists and engineers. It will also be extremely useful to all those working in other gas laser technologies, and in gas discharge physics.

  3. Collisional thulium vapour gas-discharge laser

    SciTech Connect

    Gerasimov, V A; Pavlinskii, A V [Institute of Atmospheric Optics, Siberian Branch, Russian Academy of Sciences, Tomsk (Russian Federation)

    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)

  4. Ultrafast vapourization dynamics of laser-activated polymeric microcapsules.

    PubMed

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

    2014-01-01

    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. PMID:24752357

  5. 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)

  6. Diode laser-induced infrared fluorescence of water vapour

    NASA Astrophysics Data System (ADS)

    Li, Hejie; Hanson, Ronald K.; Jeffries, Jay B.

    2004-07-01

    Infrared laser-induced fluorescence (LIF) of water vapour was investigated for its potential as a spatially resolved gasdynamic diagnostic. A cw diode laser operating near 1392 nm was scanned across a single absorption transition in the ngr1 + ngr3 band of H2O in a static cell, and the resulting fluorescence signal was collected near 2.7 m (both ngr1 and ngr3 bands). Experiments were conducted at low pressure in pure water vapour and mixtures of water vapour and N2 using a 20 mW laser in a double-pass arrangement. A simple analytical model was developed to relate LIF intensity to gas properties as a function of laser power. The spectrally resolved, single-line excitation spectrum was fitted with a Voigt profile, allowing inference of the water vapour temperature from the Doppler-broadened component of the measured fluorescence lineshape. A two-line excitation scheme was also investigated as a means of measuring temperature with reduced measurement time. From these initial measurements, we estimate that a practical sensor for atmospheric pressure applications would require a minimum of 1-2 W of laser power for two-line, fixed-wavelength temperature measurements and a minimum of about 70 W of power for scanned-wavelength measurements.

  7. Photonic metamaterials by direct laser writing and silver chemical vapour

    E-print Network

    LETTERS Photonic metamaterials by direct laser writing and silver chemical vapour deposition online: 11 May 2008; doi:10.1038/nmat2197 Metamaterials are artificial materials that--unlike natural metamaterials4,5 has been fabricated by electron-beam lithography and evaporation of metal films, both of which

  8. Diode laser-induced infrared fluorescence of water vapour

    Microsoft Academic Search

    Hejie Li; Ronald K. Hanson; Jay B. Jeffries

    2004-01-01

    Infrared laser-induced fluorescence (LIF) of water vapour was investigated for its potential as a spatially resolved gasdynamic diagnostic. A cw diode laser operating near 1392 nm was scanned across a single absorption transition in the ngr1 + ngr3 band of H2O in a static cell, and the resulting fluorescence signal was collected near 2.7 m (both ngr1 and ngr3 bands).

  9. Laser spectroscopy of sub-micrometre- and micrometre-thick caesium-vapour layers

    SciTech Connect

    Cartaleva, S; Krasteva, A; Slavov, D; Todorov, P; Vaseva, K [Institute of Electronics, Bulgarian Academy of Sciences, boul. Tzarigradsko shosse 72, 1784 Sofia (Bulgaria); Moi, L [CNISM and Physics Department, University of Siena, via Roma 56, 53100 Siena - Italy (Italy); Sargsyan, A; Sarkisyan, D [Institute for Physical Research, National Academy of Sciences of Armenia, Ashtarak-0203 (Armenia)

    2013-09-30

    We present high resolution laser spectroscopy of Cs vapours confined in a unique optical cell of sub-micrometric and micrometric thickness, where a strong spatial anisotropy is present for the time of interaction between the atoms and laser radiation. Similarly to the spectra of selective specular reflection, the Doppler-free spectra of absorption and fluorescence are observed, not revealing cross-over resonances that will be useful for frequency stabilisation, provided the cell is cheap and compact. A new resonance in the fluorescence of closed transition is studied, demonstrating its high sensitivity to elastic atom atom and atom dielectric surface collisions. The theoretical modelling performed is in agreement with the experimental observations. (laser spectroscopy)

  10. 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.

  11. Spatial homogeneity criteria for active media of cataphoresis repetitively pulsed metal vapour lasers

    SciTech Connect

    Chebotarev, Gennady D; Prutsakov, Oleg O; Latush, Evgeny L [Department of Physics, Rostov State University, Rostov-on-Don (Russian Federation)

    2005-07-31

    The formation of the transverse distribution of the metal vapour concentration in repetitively pulsed lasers is analysed. The criterion for the homogeneity of this distribution is found. The optimal conditions for excitation of the active media of cataphoresis repetitively pulsed metal vapour lasers are determined under which a high degree of both longitudinal and transverse homogeneity is achieved. (active media)

  12. Co-laser photoacoustic spectroscopy of gases and vapours for trace gas analysis

    Microsoft Academic Search

    S. Bernegger; M. W. Sigrist

    1990-01-01

    This comprehensive study reviews the sensitive and selective detection of trace gases by laser photoacoustic spectroscopy. A computer controlled CO-laser photoacoustic system is presented. The wavelength range between 5.0 and 6.5 mum is of great interest because it coincides with specific absorption bands of various gases and vapours of environmental concern. However, since water-vapour, which is present in most samples,

  13. LASER APPLICATIONS AND OTHER TOPICS IN QUANTUM ELECTRONICS: Development of a discharge in pulsed metal-vapour lasers

    NASA Astrophysics Data System (ADS)

    Zemskov, K. I.; Isaev, A. A.; Petrash, G. G.

    1999-05-01

    An analysis is made of the electric characteristics of the exciting discharge in pulsed metal vapour lasers. The initial stages of the current and voltage pulses are given most attention. Our estimates are based on a series of recent experimental results and of calculations, obtained for typical operating conditions of present-day metal vapour lasers. The initial development of the discharge is shown to depend only slightly on the conductivity of the hot part of the discharge tube, where a metal vapour coexists with a buffer gas. The effects of the electrode properties and of the processes in cold near-electrode regions on laser operation are discussed.

  14. Spectroscopic detection of atom-surface interactions in an atomic vapour layer with nanoscale thickness

    E-print Network

    Whittaker, K A; Hughes, I G; Sargsyan, A; Sarkisyan, D; Adams, C S

    2015-01-01

    We measure the resonance line shape of atomic vapor layers with nanoscale thickness confined between two sapphire windows. The measurement is performed by scanning a probe laser through resonance and collecting the scattered light. The line shape is dominated by the effects of Dicke narrowing, self-broadening, and atom-surface interactions. By fitting the measured line shape to a simple model we discuss the possibility to extract information about the atom-surface interaction.

  15. Copper vapour laser ID labelling on metal dentures and restorations.

    PubMed

    Ling, B C; Nambiar, P; Low, K S; Lee, C K

    2003-06-01

    Denture marking is accepted as a means of identifying dentures and persons in geriatric institutions, or post-mortem during war, crimes, civil unrest, natural and mass disasters. Labelling on the acrylic resin component of the denture can easily be damaged or destroyed by fire but on cobalt-chromium components it would be more resistant. A copper vapour laser (CVL) can be used to label the cobalt-chromium components of dentures and metal restorations easily, and legibly, and miniaturised for the incorporation of more personal particulars necessary for the identification of the deceased person. The CVL beam is focussed by its optics and delivered to the material surface by the two-axis scanner mounted with mirrors. A personal computer controls the movement of the scanner and the firing of the CVL. The high peak power of the pulsed CVL is focussed to very high energy density producing plasma ablation of the alloy surface. Very fine markings of a few microns width can be produced enabling the storage of detailed information of the deceased person on a metal surface for the purpose of rapid identification. PMID:12793127

  16. Atoms in Intense Laser Fields

    NASA Astrophysics Data System (ADS)

    Joachain, C. J.; Kylstra, N. J.; Potvliege, R. M.

    2014-07-01

    Part I. Basic Concepts: 1. High-intensity laser-atom physics; 2. Theory of laser-atom interactions; Part II. Theoretical Methods: 3. Perturbation theory; 4. Floquet theory; 5. Numerical integration of the wave equations; 6. The low-frequency regime; 7. The high-frequency regime; Part III. Multiphoton Atomic Physics: 8. Multiphoton ionization; 9. Harmonic generation and attosecond pulses; 10. Laser-assisted electron-atom collisions; Appendix; Index.

  17. 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

    hot lament (HF) reactor, or plasma (e.g. microwave) enhanced. The formation of H atoms chemical vapour deposition reactor James A. Smith, Moray A. Cook, Stephen R. Langford, Stephen A. Redman reactor used for diamond chemical vapour deposition (CVD). Parameters varied include the hydrocarbon (CH4

  18. Speciation of mercury in fish samples by flow injection catalytic cold vapour atomic absorption spectrometry.

    PubMed

    Zhang, Yanlin; Adeloju, Samuel B

    2012-04-01

    A rapid flow injection catalytic cold vapour atomic absorption spectrometric (FI-CCV-AAS) method is described for speciation and determination of mercury in biological samples. Varying concentrations of NaBH(4) were employed for mercury vapour generation from inorganic and mixture of inorganic and organic (total) Hg. The presence of Fe(3+), Cu(2+) and thiourea had catalytic effect on mercury vapour generation from methylmercury (MeHg) and, when together, Cu(2+) and thiourea had synergistic catalytic effect on the vapour generation. Of the two metal ions, Fe(3+) gave the best sensitivity enhancement, achieving the same sensitivity for MeHg and inorganic Hg(2+). Due to similarity of resulting sensitivity, Hg(2+) was used successfully as a primary standard for quantification of inorganic and total Hg. The catalysis was homogeneous in nature, and it was assumed that the breaking of the C-Hg bond was facilitated by the delocalization of the 5d electron pairs in Hg atom. The extraction of MeHg and inorganic mercury (In-Hg) in fish samples were achieved quantitatively with hydrochloric acid in the presence of thiourea and determined by FI-CCV-AAS. The application of the method to the quantification of mercury species in a fish liver reference material DOLT-4 gave 91.5% and 102.3% recoveries for total and methyl mercury, respectively. The use of flow injection enabled rapid analysis with a sample throughput of 180 h(-1). PMID:22405296

  19. Influence of the switch parameters on the performance characteristics of a copper vapour laser

    SciTech Connect

    Yudin, Nikolai A [Institute of Semiconductor Physics, Siberian Branch of the Russian Academy of Sciences, Novosibirsk (Russian Federation)

    2002-09-30

    Analysis of the circuits for exciting the active medium of a copper vapour laser (CVL) has shown that the main factors limiting the mean output power of the CVL are the cathode emissive power of an electron tube and the permissible current rise rate in a thyratron switch. The laser operation reliability and the thyratron service life are determined by the reverse voltage across the thyratron anode. The service life of a TGI1-1000/25 thyratron in a CVL corresponds to its certified value, if the reverse voltage at the thyratron anode is within 3 kV. (lasers)

  20. Comparative laser performances of pyrromethene 567 and rhodamine 6G dyes in copper vapour laser pumped dye lasers

    NASA Astrophysics Data System (ADS)

    Ray, A. K.; Kundu, S.; Sasikumar, S.; Rao, C. S.; Mula, S.; Sinha, S.; Dasgupta, K.

    2007-05-01

    Narrowband laser performances and photochemical stability of alcoholic solutions of pyrromethene 567 and rhodamine 6G dyes, under high-repetition rate copper vapour laser (at 510 nm), as well as, high-peak intensity Nd:YAG laser (at 532 nm) excitation have been investigated. We have observed that pyrromethene 567 dye solutions offer higher efficiency, wider tuning range, but lower photochemical stability and higher lasing threshold than that of rhodamine 6G dye solutions. An addition of about 100 mM DABCO, as a singlet oxygen quencher, in pyrromethene 567 dye solutions improved its photochemical stability close to that of rhodamine 6G. The observation of higher slope efficiency, in spite of higher threshold pump energy for pyrromethene 567 dye than that of rhodamine 6G dye solutions, was explained by a predictive model on gain characteristics of both dye solutions as a function of pump energy.

  1. 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.

  2. Influence of off-axis unstable resonator alignment on copper vapour laser output divergence

    Microsoft Academic Search

    David W. Coutts

    1994-01-01

    The influence of the off-axis unstable resonator alignment on the temporally evolving far-field intensity profile from a copper vapour laser is investigated. For optimum output power, the moderate divergence (four-pass) component produces an annular far-field intensity profile corresponding to an image of the spontaneous emission seed source. By adjusting the resonator alignment, one side of the annular image may be

  3. Detection of metal vapour in the high-current phase of a pseudospark switch by resonance absorption of laser light

    NASA Astrophysics Data System (ADS)

    Lins, Gnter; Verleger, Jobst

    1996-03-01

    The electron emission mechanism which is active at the cathode of a pseudospark switch leads to thermal overloading of emission sites followed by the evaporation of cathode material. As a consequence, metal vapour should be present very shortly after the beginning of current flow. However, it has never been possible to observe metal vapour by laser-induced fluorescence (LIF) prior to the cessation of current. In the present work resonance absorption of laser light was used to detect molybdenum vapour from the cathode during the high-current phase of a pseudospark switch. To observe the narrow-band absorption the laser light which had passed the switch was introduced into a molybdenum hollow cathode lamp where it caused fluorescence from molybdenum vapour. The intensity of the fluorescence light from the hollow cathode lamp was proportional to the intensity of the laser light left after the absorption process in the pseudospark. For a current amplitude of 12 kA and a pulse duration of 0022-3727/29/3/040/img1, it is shown that molybdenum vapour is definitely present shortly after the current maximum, well before the current stops flowing. The neutral vapour density in the high-current phase is estimated to amount to at least 0022-3727/29/3/040/img2. It is concluded that LIF fails to detect metal vapour prior to the cessation of current, mainly because the fluorescence process is severely disturbed by electronic collisions which deplete the upper fluorescence level.

  4. Feedback control of an atom laser.

    PubMed

    Dall, R G; Dedman, C J; Truscott, A G

    2008-09-15

    We report the first real-time feedback control of an atom laser. The unique feature of metastable helium atoms, the production of ions in the atom laser outcoupling process, is exploited to actively control the spatial location inside the Bose-Einstein condensate where outcoupling occurs. Unlike alkali atom lasers, this provides almost instantaneous feedback which reduces frequency, amplitude and spatial mode fluctuations in the atom laser beam. PMID:18795009

  5. LASERS: Role of negative ions in the plasma of pulsed metal and metal-compound vapour lasers

    NASA Astrophysics Data System (ADS)

    Zemskov, K. I.; Isaev, A. A.; Petrash, G. G.

    1997-07-01

    An analysis is made of the published data on the discharge and lasing characteristics, and on the level population kinetics of pulsed lasers based on vapours of metals and their halides mixed with hydrogen and HBr additives. The influence of dissociative attachment, particularly to the HBr molecule, on the population inversion kinetics of these lasers is considered. Such attachment makes it possible to explain all the observed features of the investigated lasers, including an increase in the efficiency and power of a CuBr laser with added hydrogen and of a 'HyBrID' laser. The addition of molecules with a large dissociative-attachment cross section and with a suitable position of the maximum of this cross section provides new opportunities for improving the characteristics of pulsed lasers based on r m transitions between resonance (r) and metastable (m) levels.

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

    Microsoft Academic Search

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

    2006-01-01

    We describe a novel technique for stabilizing frequency shifts in laser-interrogated vapor-cell atomic clocks. The method suppresses frequency shifts due to changes in the laser frequency, intensity, and modulation index as well as atomic vapor density. The clock operating parameters are monitored by using the atoms themselves, rather than by using conventional schemes for laser frequency and cell temperature control.

  7. 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.; Ferr, 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.

  8. On the simulation of a copper vapour laser with hydrogen admixtures

    SciTech Connect

    Petrash, G G [P.N. Lebedev Physics Institute, Russian Academy of Sciences, Moscow (Russian Federation)

    2005-06-30

    The results of computer simulation of a pulsed copper vapour laser with hydrogen admixtures presented in [1-4] are discussed. It is pointed out that the simulation technique used in these papers has a number of serious drawbacks. In particular, it is shown that the prepulse electron temperature obtained with its help is much lower than the temperature of the wall of the gas-discharge tube, which is in direct contradiction with the thermodynamics. Possible reasons for the erroneous results obtained in these works are discussed. (discussion)

  9. DISCUSSION: On the simulation of a copper vapour laser with hydrogen admixtures

    NASA Astrophysics Data System (ADS)

    Petrash, G. G.

    2005-06-01

    The results of computer simulation of a pulsed copper vapour laser with hydrogen admixtures presented in [1-4] are discussed. It is pointed out that the simulation technique used in these papers has a number of serious drawbacks. In particular, it is shown that the prepulse electron temperature obtained with its help is much lower than the temperature of the wall of the gas-discharge tube, which is in direct contradiction with the thermodynamics. Possible reasons for the erroneous results obtained in these works are discussed.

  10. Optimisation of cold vapour atomic absorption spectrometry for determination of high levels of total mercury in activated carbon

    Microsoft Academic Search

    D ARIJA G IBIAR; V ESNA J EREB; R ADOJKO J AIMOVI; T ATJANA D IZDAREVI; E LISABETH; C. P AIVA; R ICARDO M ELAMED; L UIS G ONZAGA; S. S OBRAL; M ILENA H ORVAT

    The relative efficiency of digestion\\/leaching procedures for the determination of high mercury concen trations in activated carbon obtained from natural gas treatment facilities was investigated. The method is based on acid digestion\\/leaching, reduction by SnCl 2 , gold amalgamation and detection by cold vapour atomic spectrometry. Sample decomposition was c arried out in sealed Pyrex ampoules and closed Teflon vials,

  11. 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.

  12. Atomic Processes for XUV Lasers: Alkali Atoms and Ions

    Microsoft Academic Search

    David Paul Dimiduk

    1987-01-01

    The development of extreme ultraviolet (XUV) lasers is dependent upon knowledge of processes in highly excited atoms. Described here are spectroscopy experiments which have identified and characterized certain autoionizing energy levels in core-excited alkali atoms and ions. Such levels, termed quasi-metastable, have desirable characteristics as upper levels for efficient, powerful XUV lasers. Quasi -metastable levels are among the most intense

  13. Theoretical model and novel numerical approach of a broadband optically pumped three-level alkali vapour laser

    Microsoft Academic Search

    Zining Yang; Hongyan Wang; Qisheng Lu; Liang Liu; Yuandong Li; Weihong Hua; Xiaojun Xu; Jinbao Chen

    2011-01-01

    A model for an end-pumped double-pass alkali vapour laser is set up which has considered all the main physical features, including the fine-structure mixing rate that represents the three-level nature of this kind of laser, the spectral dependence of pump light absorption for broadband pumping, the longitudinal population variation and the distributed intra-cavity losses. To solve this model, we have

  14. A simple laser system for atom interferometry

    NASA Astrophysics Data System (ADS)

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

    2014-07-01

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

  15. REVIEW: Collision lasers on atomic transitions

    NASA Astrophysics Data System (ADS)

    Petrash, G. G.

    2009-02-01

    This paper reviews the research of cw collision lasers on transitions of atoms and atomic ions and presents characteristics of systems that are considered to be collision lasers. Literature data on 'relaxation' and 'mixing' of levels by collisions with heavy particles are discussed, with particular attention to the relaxation of metastable levels. The major problems in the development of efficient cw collision lasers are analysed, including difficulties in realising discharges suitable for pumping collision lasers. The possibility of further advances in collision laser development is discussed.

  16. Line-shape study of water vapour by tunable diode laser spectrometer in the 822832nm wavelength region

    Microsoft Academic Search

    A. Ray; A. Bandyopadhyay; B. Ray; D. Biswas; P. N. Ghosh

    2004-01-01

    A near-infrared tunable diode laser absorption spectrometer is set up to measure the air-induced broadening coefficients and the line-strength parameters of water-vapour overtone transitions within the (2,1,1)?(0,0,0) band in the 822832nm wavelength region. A Hitachi HL8311 E double hetero-junction structure diode laser is used as a probe. The diode laser controller is home-built and stable within 10?A and 10mK, respectively.

  17. Using diode lasers for atomic physics

    Microsoft Academic Search

    Carl E. Wieman; Leo Hollberg

    1991-01-01

    A review of the use of diode lasers in atomic physics with an extensive list of references is presented. The relevant characteristics of diode lasers is discussed and the manner in which to purchase and use them is explained. The various techniques that have been used to control and narrow the spectral outputs of diode lasers are also reviewed. Finally,

  18. Push-Pull Laser-Atomic Oscillator

    SciTech Connect

    Jau, Y.-Y.; Happer, W. [Department of Physics, Princeton University, Princeton, New Jersey 08544 (United States)

    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.

  19. High-Intensity Laser-Atom Physics

    Microsoft Academic Search

    N. Kylstra; M Dorr

    2000-01-01

    The development of lasers capable of delivering short pulses of very intense radiation, over a widefrequency range, has led to the discovery of new, non-perturbative multiphoton processes in laserinteractions with atomic systems. In this article, we first give a survey of the main properties ofmultiphoton processes such as the multiphoton ionization of atoms, the emission by atoms of highorder harmonics

  20. Atom Laser with a cw Output Coupler

    Microsoft Academic Search

    Immanuel Bloch; Theodor W. Hnsch; Tilman Esslinger

    1999-01-01

    We demonstrate a continuous output coupler for magnetically trapped atoms. Over a period of up to 100 ms, a collimated and monoenergetic beam of atoms is continuously extracted from a Bose-Einstein condensate. The intensity and kinetic energy of the output beam of this atom laser are controlled by a weak rf field that induces spin flips between trapped and untrapped

  1. Kinetics of photoplasma of dense barium vapour

    NASA Astrophysics Data System (ADS)

    Kosarev, N. I.

    2015-03-01

    Barium vapour ionisation under laser photoexcitation of the resonance line at a wavelength of ? = 553.5 nm is studied numerically. Seed electrons, arising due to the associative ionisation of atoms, gain energy in superelastic collisions and lead to electron avalanche ionisation of the medium. The influence of radiative transfer in a cylindrical gas volume on the excitation kinetics of barium atoms, absorption dynamics of laser radiation and oscillation of ionisation-brightening wave under competition between ionising and quenching collisions of electrons with excited atoms is studied.

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

    PubMed

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

    2008-07-01

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

  3. A study of the repumping laser and external magnetic field effect on coherent absorption resonance in alkali vapour

    NASA Astrophysics Data System (ADS)

    Dey, S.; Aich, N.; Mitra, S.; Chaudhuri, C.; Ghosh, P. N.; Ray, B.

    2015-05-01

    Investigation of coherent absorption resonance via electromagnetically induced absorption (EIA) spectra in rubidium vapour has been done in presence of a repumping laser and an external magnetic field. The EIA line shape gets enhanced and symmetric with the application of the repumping laser. In presence of an external magnetic field the amplitude of the EIA resonance gradually diminishes and at higher magnetic field, two absorption dip-like structures along with a transmission peak in between is obtained. Theoretically calculated spectra based on density matrix approach show a good agreement with the observations.

  4. Laser Spectroscopy of Atoms and Molecules.

    ERIC Educational Resources Information Center

    Schawlow, Arthur L.

    1978-01-01

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

  5. Atomic gallium laser spectroscopy with violet/blue diode lasers

    E-print Network

    Marago, O M; Gucciardi, P G; Arimondo, E

    2003-01-01

    We describe the operation of two GaN-based diode lasers for the laser spectroscopy of gallium at 403 nm and 417 nm. Their use in an external cavity configuration enabled the investigation of absorption spectroscopy in a gallium hollow cathode. We have analyzed the Doppler broadened profiles accounting for hyperfine and isotope structure and extracting both the temperature and densities of the neutral atomic sample produced in the glow discharge. We have also built a setup to produce a thermal atomic beam of gallium. Using the GaN-based diode lasers we have studied the laser induced fluorescence and hyperfine resolved spectra of gallium.

  6. Atomic stabilization in ultrastrong laser fields

    Microsoft Academic Search

    Bernard Piraux; Etienne Huens; Peter Knight

    1991-01-01

    One- and two-photon ionization of atomic hydrogen by an ultrashort hyperbolic secant laser pulse is analyzed in detail by means of the essential-states method. We consider two frequency regimes. For photon energies close to the ionization potential, we show that the excitation of atomic hydrogen, initially in its ground state, leads, at low and moderate laser intensities, to an np-state

  7. Design for an optical cw atom laser.

    PubMed

    Ashkin, Arthur

    2004-08-17

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

  8. 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.

  9. 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 [A.V. Rzhanov Institute of Semiconductor Physics, Siberian Branch of the Russian Academy of Sciences, Novosibirsk (Russian Federation); Kazaryan, M A [P N Lebedev Physics Institute, Russian Academy of Sciences, Moscow (Russian Federation); Lyabin, N A [Research and production corporation 'Istok', Fryazino, Moscow region (Russian Federation)

    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)

  10. Generic model of an atom laser

    E-print Network

    B. Kneer; T. Wong; K. Vogel; W. P. Schleich; D. F. Walls

    1998-08-20

    We present a generic model of an atom laser by including a pump and loss term in the Gross-Pitaevskii equation. We show that there exists a threshold for the pump above which the mean matter field assumes a non-vanishing value in steady-state. We study the transient regime of this atom laser and find oscillations around the stationary solution even in the presence of a loss term. These oscillations are damped away when we introduce a position dependent loss term. For this case we present a modified Thomas-Fermi solution that takes into account the pump and loss. Our generic model of an atom laser is analogous to the semi-classical theory of the laser.

  11. Atomic Spectroscopy for Soft-X Lasers

    NASA Astrophysics Data System (ADS)

    Pedrotti, Kenneth Donald

    The realization of lasers in the extreme ultraviolet (XUV) is hampered by a lack of knowledge concerning the location and properties of useful atomic levels. This dissertation presents the results of experimental investigations of core-excited levels in alkali-metal atoms and alkaline -earth ions. A novel hollow-cathode discharge device has been developed for production of excited atoms of interest for laser construction. This device has been used to find new levels in Na I and Mg II using emission spectroscopy. A novel high-resolution laser technique called extinction spectroscopy has been demonstrated in Li by the measurement of the lifetime of an autoionizing level. A tunable coherent radiation source at 110 nm was also developed and used to make high-resolution absorption measurements on Cs transitions considered for use in the creation of a VUV Laser.

  12. Transverse flow CW atomic iodine laser system

    NASA Astrophysics Data System (ADS)

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

    1985-08-01

    A transverse flow continuous wave atomic iodine laser system uses a closed cycle fuel system to operate in a continuous mode. An elliptical pump cell having a Hg arc lamp cooled by deionized water irradiates with UV energy C3F7I gas to produce excited atomic iodine. A transverse flow section attached to the pump cell channels C3F7I gas into a laser cell where lasing occurs. The flow section has upstream and downstream flow cavities, triangular shaped, that channel the laser gas. A diffuser and flow straighteners are placed in these cavities to make velocity across the transverse laser axis as uniform as possible so as to produce very stable laser gain output.

  13. 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.

  14. Electroionization laser using metastable xenon atoms

    SciTech Connect

    Baranov, V.V.; Basov, N.G.; Danilychev, V.A.; Dudin, A.Y.; Zayarnyi, D.A.; Ustinovskii, N.N.; Kholin, I.V.; Chugunov, A.Y.

    1984-05-10

    A new approach is proposed for developing high-power gas lasers which work on atomic transitions. The idea is to pump the working levels by an externally sustained electroionization discharge from highly excited metastable states excited in the active medium by an external source. An output energy of more than 50 J at the wavelength 1.73 ..mu..m has been achieved from an Ar:Xe laser with an active-medium volume of 10 liters.

  15. Apparatus For Laser Excitation of Lithium Atoms.

    NASA Astrophysics Data System (ADS)

    Daly, James; Flaherty, Suzy; Oxley, Paul

    2006-10-01

    We have constructed and tested a vacuum system and a simple lithium oven. Lithium atoms from this oven will be excited to high principal quantum number by a combination of three lasers. We have also built and tested the hardware needed to operate the first of these lasers. In the future we will study charge transfer collisions between excited lithium atoms and ions to gain a better understanding of the physical properties of fusion, astrophysical, and other types of plasmas. Our vacuum system is assembled from standard conflat vacuum parts and from parts designed and built at Holy Cross. The vacuum environment is maintained by a diffusion pump in conjunction with a cold water trap to prevent pump oil migrating into our vacuum system. Our lithium oven consists of a small steel tube filled with lithium and mounted inside our vacuum system. The oven is heated by high temperature heater tapes. We have reached oven temperatures of over 600C which provides a sufficiently intense Li beam for our needs. The laser used in the first excitation step of lithium is a diode laser operating at 671nm. We have assembled the mechanical structure used to mount the diode laser and collimate its light output. Commercial electronics control the laser diode current and its temperature. Initial tests of the properties of the laser have been made.

  16. Laser manipulation of atomic and molecular flows

    NASA Astrophysics Data System (ADS)

    Lilly, Taylor C.

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

  17. Phase stabilization of laser beams in a cold atom accelerometer

    E-print Network

    Byrne, Nicole (Nicole Malenie)

    2014-01-01

    A cold atom accelerometer measures the displacement of a proof mass of laser cooled atoms with respect to an instrument reference frame. The cold atom interferometer's reference frame is defined by a pair of specially ...

  18. Laser-stimulated atomic migration

    Microsoft Academic Search

    WILBUR M. FRANKLIN; PAPIYA SENGUPTA

    1972-01-01

    The effects of stimulated Raman scattering (SRS) and of infrared (IR) absorption on the scattering at defects leading to atomic migration in solids is evaluated in detail for certain systems.DeltaE\\/kT approx sum u_{ic}^{2}\\/langleu_{i}u_{i}rangle, whereDeltaEis the activation energy, uicis the many-body critical displacement in a migration event, andlangleu_{i}u_{i}rangleis the equal-time correlation function including anharmonic terms. Using the equal-time correlation for the

  19. Comments to the note by G.G. Petrash on the paper 'On the simulation of a copper vapour laser with hydrogen admixtures'

    SciTech Connect

    Boichenko, Aleksandr M; Evtushenko, Gennadii S; Zhdaneev, O V; Yakovlenko, Sergei I [A.M. Prokhorov General Physics Institute, Russian Academy of Sciences, Moscow (Russian Federation)

    2005-06-30

    The remarks on the results published in [1-4] on the simulation of a copper vapour laser with hydrogen admixtures are analysed. It is shown that these remarks do not affect the conclusions made in our papers, and many of them are simply erroneous. (discussion)

  20. DISCUSSION: Effect of the prepulse electron density and population of the lower laser level on the pulse repetition rate achievable in a copper vapour laser

    NASA Astrophysics Data System (ADS)

    Petrash, G. G.

    2002-02-01

    Factors are considered which restrict the limiting pulse repetition rate in a copper vapour laser. The existence of a critical prepulse electron density discussed in a paper of S.I.Yakovlenko [Quantum Electronics, 30, 501 (2000)] and new arguments in favour of the existence of the critical electron density reported in a paper of A.M. Boichenko and S.I.Yakovlenko [Quantum Electronics, 32, 172 (2002)] are analysed. The conclusion is made that the new arguments do not prove the existence of the critical electron density as well.

  1. Stable 85Rb micro vapour cells: fabrication based on anodic bonding and application in chip-scale atomic clocks

    NASA Astrophysics Data System (ADS)

    Su, Juan; Deng, Ke; Guo, Deng-Zhu; Wang, Zhong; Chen, Jing; Zhang, Geng-Min; Chen, Xu-Zong

    2010-11-01

    We describe the microfabrication of 85Rb vapour cells using a glass-silicon anodic bonding technique and in situ chemical reaction between rubidium chloride and barium azide to produce Rb. Under controlled conditions, the pure metallic Rb drops and buffer gases were obtained in the cells with a few mm3 internal volumes during the cell sealing process. At an ambient temperature of 90 C the optical absorption resonance of 85Rb D1 transition with proper broadening and the corresponding coherent population trapping (CPT) resonance, with a signal contrast of 1.5% and linewidth of about 1.7 kHz, have been detected. The sealing quality and the stability of the cells have also been demonstrated experimentally by using the helium leaking detection and the after-9-month optoelectronics measurement which shows a similar CPT signal as its original status. In addition, the physics package of chip-scale atomic clock (CSAC) based on the cell was realized. The measured frequency stability of the physics package can reach to 2.1 10-10 at one second when the cell was heated to 100 C which proved that the cell has the quality to be used in portable and battery-operated devices.

  2. 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

  3. 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? (0.011 ?g g?, for solid samples), a limit of quantification of 0.038 ?g L? (0.038 ?g g?, for solid samples), a precision of 0.50% (1.000 ?g L? 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?). The following seafood collected in Todos os Santos Bay, Brazil was also analysed: bass (0.169-0.195 ?g g?), mullet (0.043-0.361 ?g g?), shrimp (0.075-0.374 ?g g?) and mussel (0.206-0.397 ?g g?). PMID:24295696

  4. Electroionization laser using metastable xenon atoms

    Microsoft Academic Search

    V. V. Baranov; N. G. Basov; V. A. Danilychev; A. Yu. Dudin; D. A. Zayarnyi; N. N. Ustinovskii; I. V. Kholin; A. Yu. Chugunov

    1984-01-01

    A new approach is proposed for developing high-power gas lasers which work on atomic transitions. The idea is to pump the working levels by an externally sustained electroionization discharge from highly excited metastable states excited in the active medium by an external source. An output energy of more than 50 J at the wavelength 1.73 ..mu..m has been achieved from

  5. Laser cooling of atoms and molecules with ultrafast pulses

    SciTech Connect

    Kielpinski, D. [Research Laboratory of Electronics and Center for Ultracold Atoms, Massachusetts Institute of Technology, Cambridge, Massachusetts 02139 (United States); Centre for Quantum Dynamics, School of Science, Griffith University, Brisbane 4111, Queensland (Australia)

    2006-06-15

    We propose a laser cooling method for atomic species whose level structure makes traditional laser cooling difficult. For instance, laser cooling of hydrogen requires single-frequency vacuum-ultraviolet light, while multielectron atoms need single-frequency light at many widely separated frequencies. These restrictions can be eased by laser cooling on two-photon transitions with ultrafast pulse trains. Laser cooling of hydrogen, antihydrogen, and many other species appears feasible, and extension of the technique to molecules may be possible.

  6. Design for a compact CW atom laser

    NASA Astrophysics Data System (ADS)

    Power, Erik; Raithel, Georg

    2011-05-01

    We present a design for a compact continuous-wave atom laser on a chip. A 2D spiral-shaped quadrupole guide is formed by two 0.5 mm 0.5 mm wires carrying 5 A each embedded in a Si wafer; a 1.5 mm 0.5 mm wire on the bottom layer carries -10 A, producing a horizontal B-field that pushes the guiding channel center above the chip surface. The center-to-center separation between the top wires is varied from 1.6 mm at the start of the guide to 1 mm at the end, decreasing the guide height from ~ 500 ?m to ~ 25 ?m above the surface as the atoms travel the 70 cm-long guide. The magnetic gradient of the guiding channel gradually increases from ~ 100 G /cm to ~ 930 G /cm . These features result in continuous surface adsorption evaporative cooling and progressive magnetic compression. Spin flip losses are mitigated by a solenoid sewn around the guide to produce a longitudinal B-field. 87Rb atoms are gravitationally loaded into the guide. A far off-resonant light shift barrier at the end of the guide traps the atoms and allows formation of a BEC. Tuning the barrier height to create a non-zero tunneling rate equal to the loading rate completes the implementation of a CW atom laser. Two options for atom interferometry are implemented on the first-generation chip (matter-wave Fabry-Perot interferometer and guide-based Mach-Zehnder interferometer). Current construction status and challenges will be discussed, along with preliminary results.

  7. Blast waves in atomic cluster media using intense laser pulses

    Microsoft Academic Search

    Roland Smith

    2008-01-01

    We report on the progress of experimental and numerical investigations of the dynamics of strong (>Mach 50) blast waves driven by focusing sub-ps laser pulses into an extended medium of atomic clusters. A gas of atomic clusters is an extraordinarily efficient absorber of intense laser light and can be used to create high energy density plasmas with tabletop laser systems.

  8. Laser Phase and Frequency Stabilization using Atomic Coherence

    E-print Network

    Torii, Yoshio; Ohtsubo, Nozomi; Aoki, Takatoshi

    2012-01-01

    We present a novel and simple method of stabilizing the laser phase and frequency by polarization spectroscopy of an atomic vapor. In analogy to the Pound-Drever-Hall method, which uses a cavity as a memory of the laser phase, this method uses atomic coherence (dipole oscillation) as a phase memory of the transmitting laser field. A preliminary experiment using a distributed feedback laser diode and a rubidium vapor cell demonstrated a shot-noise-limited laser linewidth reduction (from 2 MHz to 20 kHz). This method would improve the performance of gas-cell-based optical atomic clocks and magnetometers and facilitate laser cooling experiments using narrow transitions.

  9. High-power atomic xenon laser

    NASA Astrophysics Data System (ADS)

    Witteman, Wilhelmus J.; Peters, Peter J. M.; Botma, Hako; Tskhai, S. N.; Udalov, Yuri B.; Mei, Qi-Chu; Ochkin, V. N.

    1995-03-01

    The high pressure atomic xenon laser is becoming the most promising light source in the wavelength region of a few microns. The merits are high efficiency (so far up to 8 percent), high output energies (15 J/liter at 9 bar), high continuous output power (more than 200 W/liter), no gas dissociation and thermal heating of the lower laser level. Compared with the well-known low pressure xenon laser the power performance is now roughly a factor thousand higher. The operation of the system, based on three-body-collisions, uses the metastable state of the xenon atom as the ground state so that in the recirculation of energy a high quantum efficiency is obtained. Furthermore the homogeneous line broadening caused by the high collision frequency has also a strong beneficial effect on the efficiency. However, the required intense homogeneous excitation of the gas medium at high density is from a technical point of view a great challenge. From our experimental and theoretical work we found that at optimum performance the input power must be 1 to 2.5 [KW cm-3 atm-2]. We describe our results obtained with e-beam sustained and x-ray preionized systems delivering pulsed energies in the range of joules per liter. Furthermore we describe our recent results on continuous RF excited wave guide systems of about 37 cm length with output powers in the range of watts.

  10. Amplitude noise reduction in atomic and semiconductor lasers

    SciTech Connect

    Kennedy, T.A.B.; Walls, D.F. (Department of Physics, University of Auckland, Auckland, New Zealand (NZ))

    1989-12-01

    The quantum noise properties of atomic and semiconductor lasers are compared. The intensity fluctuation spectrum of the output field is calculated for the case of regularly, i.e., sub-Poissonian, pumped lasers. The effects of spontaneous emission on the output amplitude fluctuations may be suppressed in regularly pumped atomic lasers by requiring the lifetime of the lower lasing level to be short in comparison with that of the upper laser level. The output amplitude fluctuations then tend to zero at the laser frequency. In regularly pumped semiconductor lasers, net stimulated emission of photons dominates over spontaneous emission because of the combination of pumping and rapid intraband thermalization due to Coulomb scattering.

  11. Collinear laser spectroscopy of atomic cadmium

    E-print Network

    Frmmgen, 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; Nrtershuser, 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...

  12. Collinear laser spectroscopy of atomic cadmium

    E-print Network

    Nadja Frmmgen; 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 Nrtershuser; 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.

  13. High-intensity lasers: interactions with atoms, molecules and clusters

    E-print Network

    Ditmire, Todd

    of the ionization and dissociation of clusters of noble gas atoms is reviewed with special emphasisHigh-intensity lasers: interactions with atoms, molecules and clusters B y M. H. R. Hutchinson2 , T 2BZ, UK 2 Central Laser Facility, Rutherford Appleton Laboratory, Chilton, Didcot OX11 0QX, UK

  14. Measuring the Temporal Coherence of an Atom Laser Beam

    Microsoft Academic Search

    Michael Khl; Theodor W. Hnsch; Tilman Esslinger

    2001-01-01

    We report on the measurement of the temporal coherence of an atom laser beam extracted from a 87Rb Bose-Einstein condensate. Reflecting the beam from a potential barrier creates a standing matter wave structure. From the contrast of this interference pattern, observed by magnetic resonance imaging, we have deduced an energy width of the atom laser beam which is Fourier limited

  15. 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.

  16. 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

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

    PubMed

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

    2009-02-16

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

  18. Gravitational wave detection with single-laser atom interferometers

    E-print Network

    Nan Yu; Massimo Tinto

    2010-03-22

    We present a new general design approach of a broad-band detector of gravitational radiation that relies on two atom interferometers separated by a distance L. In this scheme, only one arm and one laser will be used for operating the two atom interferometers. We consider atoms in the atom interferometers not only as perfect inertial reference sensors, but also as highly stable clocks. Atomic coherence is intrinsically stable and can be many orders of magnitude more stable than a laser. The unique one-laser configuration allows us to then apply time-delay interferometry to the responses of the two atom interferometers, thereby canceling the laser phase fluctuations while preserving the gravitational wave signal in the resulting data set. Our approach appears very promising. We plan to investigate further its practicality and detailed sensitivity analysis.

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

    NASA Astrophysics Data System (ADS)

    Inamura, Takashi T.

    2005-01-01

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

  20. 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.

  1. 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.

  2. The diode laser in atomic physics

    Microsoft Academic Search

    J. C. Camparo

    1985-01-01

    Over the past fiie years the use of diode lasers in physics research has expanded rapidly. In part, this has occurred because the diode laser is a highly monochromatic and tunable light source that, when compared to other laser systems, is quite inexpensive and easy to operate. These characteristics make the diode laser ideal for multi-laser experiments, or small scale\\/high

  3. Laser-Ranging Long Baseline Differential Atom Interferometers for Space

    E-print Network

    Chiow, Sheng-wey; Yu, Nan

    2015-01-01

    High sensitivity differential atom interferometers are promising for precision measurements in science frontiers in space, including gravity field mapping for Earth science studies and gravitational wave detection. We propose a new configuration of twin atom interferometers connected by a laser ranging interferometer (LRI-AI) to provide precise information of the displacements between the two AI reference mirrors and a means to phase-lock the two independent interferometer lasers over long distances, thereby further enhancing the feasibility of long baseline differential atom interferometers. We show that a properly implemented LRI-AI can achieve equivalent functionality to the conventional differential atom interferometer measurement system. LRI-AI isolates the laser requirements for atom interferometers and for optical phase readout between distant locations, thus enabling optimized allocation of available laser power within a limited physical size and resource budget. A unique aspect of LRI-AI also enables...

  4. Narrow linewidth single laser source system for onboard atom interferometry

    NASA Astrophysics Data System (ADS)

    Theron, Fabien; Carraz, Olivier; Renon, Geoffrey; Zahzam, Nassim; Bidel, Yannick; Cadoret, Malo; Bresson, Alexandre

    2015-01-01

    A compact and robust laser system for atom interferometry based on a frequency-doubled telecom laser is presented. Thanks to the original stabilization architecture on a saturated absorption setup, we obtain a frequency agile laser system allowing fast tuning of the laser frequency over 1 GHz in few ms using a single laser source. The different laser frequencies used for atom interferometry are generated by changing dynamically the frequency of the laser and by creating sidebands using a phase modulator. A laser system for Rubidium 87 atom interferometry using only one laser source based on a frequency-doubled telecom fiber bench is then built. We take advantage of the maturity of fiber telecom technology to reduce the number of free-space optical components (which are intrinsically less stable) and to make the setup compact and much less sensitive to vibrations and thermal fluctuations. This source provides spectral linewidth below 2.5 kHz, which is required for precision atom interferometry and particularly for a high performance atomic inertial sensor.

  5. Investigations of laser pumped gas cell atomic frequency standard

    NASA Technical Reports Server (NTRS)

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

    1982-01-01

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

  6. Recent progress of laser cooling for neutral mercury atom

    NASA Astrophysics Data System (ADS)

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

    2014-11-01

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

  7. ATOMIC AND MOLECULAR PHYSICS: Simulation of Chromium Atom Deposition Pattern in a Gaussain Laser Standing Wave with Different Laser Power

    NASA Astrophysics Data System (ADS)

    Zhang, Wen-Tao; Zhu, Bao-Hua

    2009-07-01

    One-dimensional deposition of a neutral chromium atomic beam focused by a near-resonant Gaussian standing-laser field is discussed by using a fourth-order Runge-Kutta type algorithm. The deposition pattern of neutral chromium atoms in a laser standing wave with different laser power is discussed and the simulation result shows that the full width at half maximum (FWHM) of a nanometer stripe is 115 nm and the contrast is 2.5:1 with laser power 3.93 mW; the FWHM is 0.8 nm and the contrast is 27:1 with laser power 16 mW, the optimal laser power; but with laser power increasing to 50 mW, the nanometer structure forms multi-crests and the quality worsens quickly with increasing laser power.

  8. ATOMIC AND MOLECULAR PHYSICS: Kinetic theory of (2 + 4)-level atom in ?+ - ?- laser fields

    NASA Astrophysics Data System (ADS)

    Yu, Chuang; Yu, De-Shui; Chen, Jing-Biao

    2009-08-01

    The kinetic theory of (2 + 4)-level atoms in ? + - ?- laser fields is presented. We systemically discuss friction coefficient, momentum diffusion tensor and atomic temperature based on the Fokker-Planck equation. This cooling system is much like that of a (1 + 3)-level atom, and the temperature is still limited to the Doppler temperature. Since this cooling system has not been investigated before, this work may be regarded as a necessary complement to the laser cooling theory.

  9. 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 98.71.0% for fish and 923% for water with RSD of 1.5% for fish and 4% for water, respectively. PMID:25770618

  10. Measurement of the absorption line profiles of water vapour isotopomers at 1.39 {mu}m using the methods of diode laser spectroscopy

    SciTech Connect

    Kuz'michev, A S; Nadezhdinskii, Aleksandr I; Ponurovskii, Ya Ya

    2011-07-31

    The issues related to high-precision measurement of the absorption line profiles of water vapour and its isotopomers using the methods of diode laser spectroscopy in the near IR range aimed at the analysis and detection of greenhouse gases are considered. The absorption line shape of H{sub 2}{sup 16}O is investigated as a function of pressure of different buffer gases. The influence of the instrument function of the diode laser (DL) on the precision of measuring the line profile is studied. From fitting the profile of Doppler-broadened H{sub 2}{sup 16}O absorption line to a model profile the lasing line width of the DL with a fibre pigtail is determined. The frequencies and intensities of absorption lines of water isotopomers H{sub 2}{sup 16}O, H{sub 2}{sup 17}O, H{sub 2}{sup 18}O, and HDO are measured in the range of DL oscillation. Analytical spectral regions are chosen for distant probing of water vapour using an airborne lab. (laser spectroscopy)

  11. LaserGuided Atoms in Hollow-Core Optical Fibers

    Microsoft Academic Search

    M. J. Renn; D. Montgomery; O. Vdovin; D. Z. Anderson; C. E. Wieman; E. A. Cornell

    1995-01-01

    We have used optical forces to guide atoms through hollow-core optical fibers. Laser light is launched into the hollow region of a glass capillary fiber and guided by grazing-incidence reflection from the walls. When the laser is detuned 1-30 GHz red of the Rb D2 resonance lines, dipole forces attract atoms to the high-intensity region along the axis and guide

  12. Progress towards laser spectroscopy of atomic and molecular positronium

    NASA Astrophysics Data System (ADS)

    Cassidy, D. B.; Hisakado, T. H.; Meligne, V. E.; Tom, H. W. K.; Mills, A. P., Jr.

    2009-11-01

    The production of molecular positronium and the existence of excited states of this molecule make it natural to consider performing laser spectroscopy on this four-particle matter-antimatter system. We report here progress towards this goal, including the production of a more intense positron beam and the development and testing of laser systems suitable for spectroscopy of atomic and molecular positronium.

  13. Interactions of cold atoms and ultrafast laser pulses

    Microsoft Academic Search

    Michelle Stephens; Kyle Taylor; Jacob Berg; Joseph Hottenstein; Hai Nguyen; Christopher Verzani

    2009-01-01

    We report experimental progress of the interaction between cold trapped atoms and ultrafast laser pulses. At the University of Wisconsin Stevens Point, we use a Spectra-Physics Millennia laser to pump a KM Labs Ti:Sappire laser which produces pulses with duration of about 30 fs at a wavelength of 800 nm at a repetition rate of 1 kHz. Investigations of the

  14. Atomic nanofabrication by laser manipulation of a neutral cesium beam

    Microsoft Academic Search

    A. Camposeo; F. Cervelli; F. Tantussi; M. Lindholdt; F. Fuso; M. Allegrini; E. Arimondo

    2003-01-01

    In this work, we report on the results of a nanolithography experiment with a cold cesium beam. We have realized a brilliant and collimated cesium beam with a low longitudinal velocity (10 m\\/s) exploiting laser cooling techniques, in particular a pyramidal atomic funnel. The cesium atomic beam has been utilized to pattern gold substrates, using Self Assembled Monolayers (SAM) of

  15. Strongly driven one-atom laser and decoherence monitoring

    SciTech Connect

    Lougovski, P. [Hearne Institute for Theoretical Physics, Department of Physics and Astronomy, Louisiana State University, 202 Nicholson Hall, Baton Rouge, Louisiana 70803 (United States); Casagrande, F.; Lulli, A. [Dipartimento di Fisica, Universita di Milano, Via Celoria 16, 20133 Milan (Italy); Solano, E. [Physics Department, ASC, and CeNS, Ludwig-Maximilians-Universitaet, Theresienstrasse 37, 80333 Munich (Germany); Seccion Fisica, Departamento de Ciencias, Pontificia Universidad Catolica del Peru, Apartado 1761, Lima (Peru)

    2007-09-15

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

  16. Stark Effect of Alkali Atoms by Laser Spectroscopy

    Microsoft Academic Search

    Masayuki Kawamura; Wei-Guo Jin; Tatsuya Minowa; Nobuyuki Takahashi

    2009-01-01

    Stark effect of alkali atoms has been studied by means of high-resolution atomic-beam laser spectroscopy. A compact electrode apparatus has been developed in order to produce a stable and strong electric field. The Stark shifts and splittings of the D lines have been measured for K, Rb and Cs atoms. The scalar polarizabilities of the K and Rb D1 lines

  17. Electron drift in alkali-metal vapours

    Microsoft Academic Search

    I. I. Fabrikant

    1992-01-01

    Electron drift velocities in sodium, potassium, rubidium and caesium vapours are calculated using theoretical momentum-transfer cross sections for electron-atom scattering. The results strongly disagree with experimental data for saturated vapours at low values of E\\/N (ratio of electric field to vapour number density). The author shows using the case of sodium as an example, that the disagreement could be explained

  18. Laser stripping of hydrogen atoms by direct ionization

    NASA Astrophysics Data System (ADS)

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

    2015-05-01

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

  19. An output coupler for Bose condensed atoms The observations of BEC have stimulated interest in atom lasers, coherent sources of

    E-print Network

    An output coupler for Bose condensed atoms The observations of BEC have stimulated interest in atom lasers, coherent sources of atomic matter waves. The build-up of atoms in the ground state of a magnetic. We demonstrated a scheme for doing this with Bose condensed atoms [1]. A variable fraction of atoms

  20. hal-00195321,version2-9Jan2008 Guided atom laser : a new tool for guided atom optics

    E-print Network

    Paris-Sud XI, Universit de

    hal-00195321,version2-9Jan2008 Guided atom laser : a new tool for guided atom optics J. Billy, V: January 9, 2008) Abstract We present a guided atom laser. A Bose-Einstein condensate (BEC) is created in a crossed hybrid magnetic and an elongated optical trap, which acts as a matterwave guide. Atoms

  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. Retrieval of electron-atom scattering cross sections from laser-induced electron rescattering of atomic negative ions in intense laser fields

    E-print Network

    Lin, Chii-Dong

    of atomic negative ions in intense laser fields XiaoXin Zhou,1,2 Zhangjin Chen,1 Toru Morishita,1,3 Anh-dimensional electron momentum distributions of atomic negative ions in an intense laser field by solving the time of atomic negative ions in the laser field. This opens up the possibility of measuring electron

  3. 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.

  4. ATOMIC AND MOLECULAR PHYSICS: Multiphoton ionization of the hydrogen atom exposed to circularly or linearly polarized laser pulses

    NASA Astrophysics Data System (ADS)

    Wang, Pei-Jie; He, Feng

    2009-12-01

    This paper studies the multiphoton ionization of the hydrogen atom exposed to the linearly or circularly polarized laser pulses by solving the time-dependent Schrdinger equation. It finds that the ratio of the ionization probabilities by linearly and circularly polarized laser pulses varies with the numbers of absorbing photons. With the same laser intensity, the circularly polarized laser pulse favors to ionize the atom with more ease than the linearly polarized laser pulse if only two or three photons are necessary to be absorbed. For the higher order multiphoton ionization, the linearly polarized laser pulse has the advantage over circularly polarized laser pulse to ionize the atom.

  5. A continuous flow cold vapour procedure for mercury determination by atomic emission using the reverse flow injection approach

    NASA Astrophysics Data System (ADS)

    De Andrade, Joo Carlos; Bueno, Maria Izabel M. S.

    1994-07-01

    An experimental set-up for on-line Hg 2+ reduction and determination was devised using the reverse flow injection analysis (r-FIA) concept and the cold vapour (CV) technique, injecting an acidic Sn 2+ solution into the mercury sample line. The elemental mercury generated is separated from the reacting mixture by a 100 ml min -1 helium stream, which passes through a gas-liquid separator connected to a permeation cell. This gas stream is used as the plasma medium. The permeated Hg is then concentrated on a 0.3 g gold foil placed inside a quartz tube connected to an 11 W He de discharge plasma chamber. The mercury retained on the gold surface is released by resistive heating and the emission intensity is observed at the 253.7 nm mercury line. For an injection cycle of 30 s, the calibration graphs are linear up to 50 ng ml -1(itr 2 = 0.999). An injection frequency of 120 h -1 is achieved, with negligible carry-over. The calculated relative standard deviation of the transient peaks is 1.6%. Higher sensitivities can be achieved using longer injection cycles. Samples of Human Hair Certified Reference Material were used to determine the accuracy of the method.

  6. Interactions of cold atoms and ultrafast laser pulses

    NASA Astrophysics Data System (ADS)

    Stephens, Michelle; Taylor, Kyle; Berg, Jacob; Hottenstein, Joseph; Nguyen, Hai; Verzani, Christopher

    2009-05-01

    We report experimental progress of the interaction between cold trapped atoms and ultrafast laser pulses. At the University of Wisconsin Stevens Point, we use a Spectra-Physics Millennia laser to pump a KM Labs Ti:Sappire laser which produces pulses with duration of about 30 fs at a wavelength of 800 nm at a repetition rate of 1 kHz. Investigations of the interactions of these ultrafast laser pulses with 300 micro K Rb atoms produced in a magneto optical trap are underway. We look for various processes of molecular photo-association which include formation, distribution of populations, and alignment. The diagnostic system and the specific photo-association process will be described in detail.

  7. Miniature laser-pumped cesium cell atomic clock oscillator

    Microsoft Academic Search

    P. J. Chantry; I. Liberman; W. R. Verbanets; C. F. Petronio; R. L. Cather; W. D. Partlow

    1996-01-01

    Our approach to a low-power compact atomic oscillator is based on the use of a diode laser to excite a small cell (~0.1 cm3) containing cesium vapor and buffer gases. Laser wavelength and power are controlled solely with current and temperature, providing a compact, low-power, rugged, spectrally-pure, collimated optical source. A succession of physics packages, when operated with analog laboratory

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

    SciTech Connect

    Torrontegui, E.; Muga, J. G. [Departamento de Quimica-Fisica, Universidad del Pais Vasco - Euskal Herriko Unibertsitatea, Apartado 644, E-48080 Bilbao (Spain); Echanobe, J. [Departamento de Ingenieria Electronica, Universidad del Pais Vasco - Euskal Herriko Unibertsitatea, Apartado 644, E-48080 Bilbao (Spain); Ruschhaupt, A. [Institut fuer Theoretische Physik, Leibniz Universitaet Hannover, Appelstrasse 2, D-30167 Hannover (Germany); Guery-Odelin, D. [Laboratoire Collisions Agregats Reactivite, CNRS UMR 5589, IRSAMC, Universite Paul Sabatier, 118 Route de Narbonne, F-31062 Toulouse CEDEX 4 (France)

    2010-10-15

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

  9. Design, fabrication and characterization of tunable external cavity diode laser and atom trapping chips for atomic physics

    Microsoft Academic Search

    Ho-Chiao Chuang

    2008-01-01

    External cavity diode laser systems (ECDLs) have been well documented for their suitability in the fields of laser cooling and atom trapping, and are now widely used in optical and atomic physics. A particularly simple implementation of this idea uses feedback from a diffraction grating mounted in the Littrow configuration and the typical size of this laser is quite large

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

    E-print Network

    Toshiyuki Hosoya; Martin Miranda; Ryotaro Inoue; Mikio Kozuma

    2014-12-02

    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, which does not depend on complex nonlinear frequency-doubling, has great importance for implementing transportable optical lattice clocks, and is also useful for investigations on condensed matter physics or quantum information processing using cold atoms.

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

    E-print Network

    Hart, Nathan Andrew

    2012-10-19

    The above threshold ionization (ATI) spectra provide a diversity of information about a laser-atom ionization process such as laser intensity, pulse duration, carrier envelope phase, and atomic energy level spacing. However, the spatial distribution...

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

    NASA Astrophysics Data System (ADS)

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

    2014-06-01

    Secondary laser cooling has been realised on the weak dipole transition 4f13(2Fo)6s2, J = 7/2, F=4 ? 4f12(3H6) 5d5/26s2, 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 105. 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.

  13. Experiments on a semiconductor laser pumped rubidium atomic clock

    Microsoft Academic Search

    Minoru Hashimoto; Motoichi Ohtsu

    1987-01-01

    Experiments designed to improve the performance of a commercial Rb-87 atomic clock by using a semiconductor laser are described. Two resonance gas cells were compared: gas cell A (natural Rb and buffer gases) and gas cell B (Rb-87 and buffer gases). Although the values of the highest microwave frequency stability obtained by using these cells were very similar, the magnitudes

  14. Laser experiments with single atoms in cavities and traps

    Microsoft Academic Search

    Herbert Walther

    1996-01-01

    In this paper recent experiments with the one-atom maser or micromaser are described. They deal with the dynamical behavior of the field at parameter values where the field undergoes phase transitions. In the second part of the paper experiments with a single laser-cooled In+ ion in a modified Paul trap are discussed. The aim of this experiment is precision spectroscopy

  15. Equilibrium temperature of laser cooled atoms in squeezed vacuum

    NASA Technical Reports Server (NTRS)

    Shevy, Y.

    1992-01-01

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

  16. A laser-cooled atom beam for nanolithography applications

    Microsoft Academic Search

    A. Camposeo; F. Cervelli; A. Piombini; F. Tantussi; F. Fuso; M. Allegrini; E. Arimondo

    2003-01-01

    We are developing an apparatus for atom lithography with the main objective of to push the space resolution of the technique towards its ultimate limit, expected in the 10 nm range. We exploit an original implementation of laser-cooling techniques to produce a brilliant and collimated cesium beam with low longitudinal velocity. Beam characterization, carried out with a variety of spectroscopic

  17. Mercury(II) and methyl mercury determinations in water and fish samples by using solid phase extraction and cold vapour atomic absorption spectrometry combination.

    PubMed

    Tuzen, Mustafa; Karaman, Isa; Citak, Demirhan; Soylak, Mustafa

    2009-07-01

    A method has been developed for mercury(II) and methyl mercury speciation on Staphylococcus aureus loaded Dowex Optipore V-493 micro-column in the presented work, by using cold vapour atomic absorption spectrometry. Selective and sequential elution with 0.1 molL(-1) HCl for methyl mercury and 2 molL(-1) HCl for mercury(II) were performed at the pH range of 2-6. Optimal analytical conditions including pH, amounts of biosorbent, sample volumes were investigated. The detection limits of the analytes were 2.5 ngL(-1) for Hg(II) and 1.7 ngL(-1) for methyl mercury. The capacity of biosorbent for mercury(II) and methyl mercury was 6.5 and 5.4 mgg(-1), respectively. The validation of the presented procedure is performed by the analysis of standard reference material. The speciation procedure established was successfully applied to the speciation of mercury(II) and methyl mercury in natural water and microwave digested fish samples. PMID:19394391

  18. 5p photoemission from laser-excited cesium atoms

    SciTech Connect

    Schulz, J. [Department of Physical Sciences, University of Oulu, Box 3000, FIN-90014 (Finland); Department of Physics, Uppsala University, Box 530, SE-75121 Uppsala (Sweden); Maeaettae, M.; Heinaesmaeki, S.; Huttula, M.; Aksela, S.; Aksela, H. [Department of Physical Sciences, University of Oulu, Box 3000, FIN-90014 (Finland); Sankari, R. [Department of Physical Sciences, University of Oulu, Box 3000, FIN-90014 (Finland); Department of Physics, University of Turku, FIN-20014 Turku (Finland); Kukk, E. [Department of Physics, University of Turku, FIN-20014 Turku (Finland); Rander, T.; Svensson, S. [Department of Physics, Uppsala University, Box 530, SE-75121 Uppsala (Sweden)

    2006-06-15

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

  19. A Scheme of Generating and Spatially Separating Two-Component Entangled Atom Lasers

    E-print Network

    Xiong-Jun Liu; Hui Jing; Xin Liu; Ming-Sheng Zhan; Mo-Lin Ge

    2005-11-14

    Entanglement of remote atom lasers is obtained via quantum state transfer technique from lights to matter waves in a five-level $M$-type system. The considered atom-atom collisions can yield an effective Kerr susceptibility for this system and lead to the self- and cross- phase modulation between the two output atom lasers. This effect results in generation of entangled states of output fields. Particularly, under different conditions of space-dependent control fields, the entanglement of atom lasers and of atom-light fields can be obtained, respectively. Furthermore, based on the Bell-state measurement, an useful scheme is proposed to spatially separate the generated entangled atom lasers.

  20. 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 [Institute of Physics, Czech Academy of Sciences, Prague (Czech Republic); Jakubec, I [Institute of Inorganic Chemistry, Czech Academy of Sciences, Rez (Czech Republic)

    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)

  1. Ionization of Atoms by the Spatial Gradient of the Pondermotive Potential in a Focused Laser Beam

    E-print Network

    . Rydberg ions, formed during the interaction of noble gas atoms with an intense laser pulse, are usedIonization of Atoms by the Spatial Gradient of the Pondermotive Potential in a Focused Laser Beam E of atoms by the spatial gradient of the pondermotive potential in a focused laser beam is investigated

  2. New stable multiply charged negative atomic ions in linearly polarized superintense laser fields

    E-print Network

    Kais, Sabre

    New stable multiply charged negative atomic ions in linearly polarized superintense laser fields Qi doubly-negatively-charged atomic ion in the gas phase, only one electron can be added to a free atom superintense laser field one can stabilize multiply charged negative atomic ions in the gas phase. We present

  3. Cs 728 nm Laser Spectroscopy and Faraday Atomic Filter

    NASA Astrophysics Data System (ADS)

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

    2014-12-01

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

  4. 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.

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

    PubMed

    Cayzac, Witold; Frank, Alexander; Schumacher, Dennis; Roth, Markus; Blazevi?, Abel; Wamers, Felix; Trger, Michael; Berdermann, Elni; Voss, Bernd; Hessling, Thomas

    2013-04-01

    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 7 mm(2) large and 20??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 (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(3)-10(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 ?EE ? 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. PMID:23635189

  6. Differential atomic magnetometry based on a diverging laser beam

    SciTech Connect

    Hodby, E.; Donley, E. A.; Kitching, J. [Time and Frequency Division, National Institute of Standards and Technology, 325 Broadway, Boulder, Colorado 80305 (United States)

    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.

  7. 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.

  8. Blast waves in atomic cluster media using intense laser pulses.

    NASA Astrophysics Data System (ADS)

    Smith, Roland

    2008-04-01

    We report on the progress of experimental and numerical investigations of the dynamics of strong (>Mach 50) blast waves driven by focusing sub-ps laser pulses into an extended medium of atomic clusters. A gas of atomic clusters is an extraordinarily efficient absorber of intense laser light and can be used to create high energy density plasmas with tabletop laser systems. These HED plasmas can launch shocks and strongly radiative blast waves with dimensionless parameters scalable to astrophysical objects such as supernova remnants, and have been used by us in a number of shock evolution and collision studies. To date such experiments have been conducted with modest laser energies of <1J. In order to study processes such as the Vishniac overstability and cooling instability in these systems significantly more input energy may be required due to the weak variation of blast wave velocity with deposited energy Vb E^1/4. We report on the scaling of cluster blast wave experiments to laser energies up 0.5kJ using the Vulcan laser at RAL. An extensive suite of diagnostics including multi-frame optical probe systems, streaked Schlieren imaging and keV imaging and spectroscopy was fielded in order to study the growth of spatial and temporal instabilities. To better match astrophysical scenarios with strong radiative pre-heat of material upstream of the shock an additional radiation field was also introduced using a secondary laser heated gold foil target and grazing incidence XUV guiding structure. This allowed us to compare blast wave propagation into cold versus hot ionized upstream gases. These experimental systems provide a useful test bed against which to benchmark numerical simulations, and have been compared to the 3D magnetoresistive hydrocode GORGON and radiation-hydrodynamics code NYM.

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

    NASA Astrophysics Data System (ADS)

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

    2014-04-01

    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.

  10. 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

  11. Experimental study on initial atomization of plain jet air blast atomizer by multi-pulse laser photography

    Microsoft Academic Search

    J. S. Chin; M. Y. Hou; Z. Liu

    1987-01-01

    An experimental study on the initial atomization of a plain jet air blast atomizer by multi-pulse laser photography has been conducted. The photos obtained are processed by computerized image processor. Initial drop size distribution and droplet velocity are obtained. By using multi-pulse laser the direction of flying droplets and their trajectories can be shown. The results also show that for

  12. Narrow-line diode laser system for laser cooling of strontium atoms on the intercombination transition

    Microsoft Academic Search

    Y. Li; T. Ido; T. Eichler; H. Katori

    2004-01-01

    We report a diode laser system developed for narrow-line cooling and trapping on the 1 S 0 3 P 1 intercombination transition of neutral strontium atoms. Doppler cooling on this spin-forbidden transition with a line width of G\\/2p=7.1kHz enables us to achieve sub-K temperatures in a two-step cooling process. The required reduction of the laser line width to the kHz

  13. Atomic physics modeling of x-ray laser plasmas

    SciTech Connect

    Osterheld, A.L.; Young, B.K.F.; Walling, R.S.; Goldstein, W.H.; Scofield, J.H.; Chen, M.; Shimkaveg, G.; Carter, M.; Shepherd, R.; MacGowan, B.J.; Da Silva, L.; Matthews, D.; Maxon, S.; London, R.; Stewart, R.E.

    1992-05-01

    We have developed collisional-radiative models to describe the kinetics of x-ray laser plasmas. Careful attention has been paid to indirect processes such as dielectronic recombination and excitation-autoionization. These models can be used for calculations of the ionization dynamics, gain coefficients, and detailed emission spectra. We will present results from ionization balance and gain calculations for neonlike and nickellike collisional lasing schemes, emphasizing the effects of different atomic physics processes and model approximations.

  14. Laser Cooling and Magnetic Trapping of Neutral Atoms

    NASA Astrophysics Data System (ADS)

    So, Sung-Leung Ivan

    Predictions based on a one dimensional deterministic model concerning the National Bureau of Standards (Gaithersburg) laser-cooling experiment is described. The predictions are found to agree with the experimental data. Some ideas of how to cool in a harmonic magnetic trap are explored using computer simulation techniques. The ideas may be tested in an experimentally realizable donut-trap. A possible way to deal with general nonequilibrium situation is demonstrated by a simple model of the atomic cloud in the magnetic trap.

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

    PubMed

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

    2012-12-01

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

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

    PubMed

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

    2007-09-01

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

  17. Theory of a mode-locked atom laser with toroidal geometry Peter D. Drummond,1

    E-print Network

    Queensland, University of

    laser, based on the generation of a dark soliton in a ring-shaped Bose-Einstein condensate way to make a mode-locked atom laser is to cre- ate a periodic field circulating around a ringTheory of a mode-locked atom laser with toroidal geometry Peter D. Drummond,1 Antonios Eleftheriou

  18. HIGH RESOLUTION OPTICAL SPECTROSCOPY IN NEON USING A TUNABLE LASER AND AN EXCITED ATOMIC BEAM

    E-print Network

    Boyer, Edmond

    L-161 HIGH RESOLUTION OPTICAL SPECTROSCOPY IN NEON USING A TUNABLE LASER AND AN EXCITED ATOMIC BEAM Rsum. 2014 La structure hyperfine de trois raies d'absorption du non a t tudie l'aide d'un laser absorption lines of neon have been investigated using a single mode tunable dye laser illuminating an atomic

  19. APS/123-QED Guided atom laser: transverse mode quality and longitudinal momentum distribution

    E-print Network

    APS/123-QED Guided atom laser: transverse mode quality and longitudinal momentum distribution F the outcoupling of a matter wave into a guide by a time-dependent spilling of the atoms from an initially trapped to interactions in the mode quality of a guided atom laser. This study is consistent with recent experimental

  20. Correlation Effects in Intense Laser-Atom Processes

    NASA Astrophysics Data System (ADS)

    Starace, Anthony

    2013-05-01

    Results for three processes involving interaction of the He atom with an intense, short laser pulse are presented, each of which demonstrates dramatic effects of electron correlations: high-order harmonic generation, few-cycle attosecond pulse ionization, and few-cycle attosecond pulse ionization plus excitation. Results are obtained by solving the two-active-electron, time-dependent Schrdinger equation (TDSE) in its full dimensionality over the laser pulse duration. In cases of ionization, projections of the two-electron wave packet solutions of the TDSE onto correlated eigenstates of the field-free Hamiltonian are carried out. All numerical results are thus essentially exact. For high-order harmonic generation, as the laser pulse frequency varies from 4.6 eV to 6.6 eV, the 13th, 11th, and 9th harmonics sequentially become resonant with the isolated 2s2p(1P) autoionizing state of He, which dramatically enhances these harmonics. For ionization of He to the He+(n =1) state by an intense few-cycle attosecond pulse, asymmetries are found in the differential probability for ionization of electrons parallel and antiparallel to the linear polarization axis of the laser pulse. These asymmetries are greatly enhanced in the vicinity of two-electron doubly-excited (autoionizing) states. For ionization plus excitation of He to He+(n =2) states by a few-cycle attosecond pulse, for most carrier-envelope phases (CEPs) asymmetries in the photoelectron angular distributions have opposite signs for He+(2s) and He+(2p) and are orders of magnitude larger than for ionization without excitation. All these results demonstrate a crucial role for many-body effects in intense laser-atom interactions. Results for three processes involving interaction of the He atom with an intense, short laser pulse are presented, each of which demonstrates dramatic effects of electron correlations: high-order harmonic generation, few-cycle attosecond pulse ionization, and few-cycle attosecond pulse ionization plus excitation. Results are obtained by solving the two-active-electron, time-dependent Schrdinger equation (TDSE) in its full dimensionality over the laser pulse duration. In cases of ionization, projections of the two-electron wave packet solutions of the TDSE onto correlated eigenstates of the field-free Hamiltonian are carried out. All numerical results are thus essentially exact. For high-order harmonic generation, as the laser pulse frequency varies from 4.6 eV to 6.6 eV, the 13th, 11th, and 9th harmonics sequentially become resonant with the isolated 2s2p(1P) autoionizing state of He, which dramatically enhances these harmonics. For ionization of He to the He+(n =1) state by an intense few-cycle attosecond pulse, asymmetries are found in the differential probability for ionization of electrons parallel and antiparallel to the linear polarization axis of the laser pulse. These asymmetries are greatly enhanced in the vicinity of two-electron doubly-excited (autoionizing) states. For ionization plus excitation of He to He+(n =2) states by a few-cycle attosecond pulse, for most carrier-envelope phases (CEPs) asymmetries in the photoelectron angular distributions have opposite signs for He+(2s) and He+(2p) and are orders of magnitude larger than for ionization without excitation. All these results demonstrate a crucial role for many-body effects in intense laser-atom interactions. Work supported in part by DOE, Office of Science, Div. of Chemical Sciences, Geosciences, and Biosciences, under Grant No. DE-FG03-96ER14646.

  1. JOURNAL DE PHYSIQUE ColZoque C7, supplgment au n07, Tome 40, JuiZZet 1979, page C7-373 KINETIC PROCESSESIN NON-HEATEDCOPPER VAPOUR LASER

    E-print Network

    Paris-Sud XI, Universit de

    both the ground and 2~5,2 metastable states o f cdpper atoms were deri- ved from measurements o f the o a t the instant o f vapour production. A triggered xenon f l a s h tube was used as the sour- ce f o r absorptlon was displayed on an oscilloscope and recorded on Polaroid f l lm. Ground s t a t e and metastable copper

  2. 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.

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

    NASA Astrophysics Data System (ADS)

    Miley, G. H.

    1992-03-01

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

  4. Imaging Atoms and Molecules with Strong Laser Fields

    NASA Astrophysics Data System (ADS)

    Smeenk, Christopher

    We study multi-photon ionization of rare gas atoms and small molecules by infrared femtosecond laser pulses. We demonstrate that ionization is accurately described by a tunnelling model when many infrared photons are absorbed. By measuring photo-electron and photo-ion spectra, we show how the sub-Angstrom spatial resolution of tunnelling gives information about electron densities in the valence shell of atoms and molecules. The photo-electron and photo-ion momentum distributions are recorded with a velocity map imaging (VMI) spectrometer. We describe a tomographic method for imaging a 3-D momentum distribution of arbitrary symmetry using a 2-D VMI detector. We apply the method to measure the 3-D photo-electron distribution in elliptically polarized light. Using circularly polarized light, we show how the photo-electron momentum distribution can be used to measure the focused laser intensity with high precision. We demonstrate that the gradient of intensities present in a focused femtosecond pulse can be replaced by a single average intensity for a highly nonlinear process like multi-photon ionization. By studying photo-electron angular distributions over a range of laser parameters, we determine experimentally how the photon linear momentum is shared between the photo-electron, photo-ion and light field. We find the photo-electron carries only a portion of the total linear momentum absorbed. In addition we consider how angular momentum is shared in multi-photon ionization, and find the photo-electron receives all of the angular momentum absorbed. Our results demonstrate how optical and material properties influence the photo-electron spectrum in multi-photon ionization. These will have implications for molecular imaging using femtosecond laser pulses, and controlling the initial conditions of laser generated plasmas.

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

    SciTech Connect

    Yeates, P. [National Centre for Plasma Science and Technology (NCPST), Dublin City University (DCU), Dublin 7 (Ireland)] [National Centre for Plasma Science and Technology (NCPST), Dublin City University (DCU), Dublin 7 (Ireland); Fallon, C. [School of Physical Sciences, Dublin City University (DCU), Dublin 7 (Ireland)] [School of Physical Sciences, Dublin City University (DCU), Dublin 7 (Ireland); Kennedy, E. T.; Costello, J. T. [National Centre for Plasma Science and Technology (NCPST), Dublin City University (DCU), Dublin 7 (Ireland) [National Centre for Plasma Science and Technology (NCPST), Dublin City University (DCU), Dublin 7 (Ireland); School of Physical Sciences, Dublin City University (DCU), Dublin 7 (Ireland)

    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.

  6. 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 [Institut fuer Kernphysik, Technische Universitaet Darmstadt, Schlossgartenstr. 9, 64289 Darmstadt (Germany); Blazevic, Abel; Wamers, Felix; Traeger, Michael; Berdermann, Eleni; Voss, Bernd; Hessling, Thomas [GSI Helmholtzzentrum fuer Schwerionenforschung, Planckstr. 1, 64291 Darmstadt (Germany)

    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.

  7. Concentration effects on laser-based ?18 O and ?2 H measurements and implications for the calibration of vapour measurements with liquid standards.

    PubMed

    Schmidt, Markus; Maseyk, Kadmiel; Lett, Cline; Biron, Philippe; Richard, Patricia; Bariac, Thierry; Seibt, Ulli

    2010-12-30

    Recently available isotope ratio infrared spectroscopy can directly measure the isotopic composition of atmospheric water vapour (?(18) O, ?(2) H), overcoming one of the main limitations of isotope ratio mass spectrometry (IRMS) methods. Calibrating these gas-phase instruments requires the vapourisation of liquid standards since primary standards in principle are liquids. Here we test the viability of calibrating a wavelength-scanned cavity ring-down spectroscopy (CRDS) instrument with vapourised liquid standards. We also quantify the dependency of the measured isotope values on the water concentration for a range of isotopic compositions. In both liquid and vapour samples, we found an increase in ?(18) O and ?(2) H with water vapour concentration. For ?(18) O, the slope of this increase was similar for liquid and vapour, with a slight positive relationship with sample ?-value. For ?(2) H, we found diverging patterns for liquid and vapour samples, with no dependence on ?-value for vapour, but a decreasing slope for liquid samples. We also quantified tubing memory effects to step changes in isotopic composition, avoiding concurrent changes in the water vapour concentration. Dekabon tubing exhibited much stronger, concentration-dependent, memory effects for ?(2) H than stainless steel or perfluoroalkoxy (PFA) tubing. Direct vapour measurements with CRDS in a controlled experimental chamber agreed well with results obtained from vapour simultaneously collected in cold traps analysed by CRDS and IRMS. We conclude that vapour measurements can be calibrated reliably with liquid standards. We demonstrate how to take the concentration dependencies of the ?-values into account. Copyright 2010 John Wiley & Sons, Ltd. PMID:21080508

  8. A comparative study of three microwave induced plasma sources for atomic emission spectrometryI. Excitation of mercury and its determination after on-line continuous cold vapour generation

    NASA Astrophysics Data System (ADS)

    Camua-Aguilar, J. F.; Pereiro-Garcia, R.; Snchez-Ura, J. E.; Sanz-Medel, A.

    1994-05-01

    Argon and helium microwave induced plasmas (MIPs), sustained in a Beenakker cavity (with "capillary tube" and "tangential flow" torches), a surfatron and a microwave plasma torch (MPT) have been compared in terms of their discharge properties (plasma configuration, stability and gas consumption) and ability to excite Hg atoms. An on-line continuous mercury cold vapour generation system, using SnCl 2/ HC1 as the chemical reducing agent, was employed as the sample introduction system. Analytical figures of merit for the determination of mercury by atomic emission spectrometry (AES) showed the superiority of He discharges over the argon plasmas as excitation sources of atomic mercury. The He surfatron, with a 1 mm i.d. fused silica tube as the plasma torch, turned out to be the cavity that offered the best Hg(II) detection limit (10 pg ml -1), a linear dynamic range of more than three orders of magnitude, and a precision of 4%. However, the plasma generated in the surfatron device used was shown to be susceptible to the entrance of molecular gases, e.g. produced during the sample reduction step, and to water vapour. Application of these systems to the sensitive determination of mercury in sea-water has been explored.

  9. 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 experiments demonstrate...

  10. A Miniature Glow Discharge for Laser Excited Atomic Fluorescence Detection of Lead

    Microsoft Academic Search

    C. L. Davis; B. W. Smith; J. D. Winefordner

    1995-01-01

    A miniature glow discharge atom reservoir has been designed for laser excited atomic fluorescence spectrometric measurements of nanoliter-sized solution residues. A copper vapor laser pumped dye laser was used to measure the fluorescence of Ph atoms sputtered from the Ni cathode of the discharge. Excitation of Pb occurred at 283.3 nm, and fluorescence was monitored at 405.8 nm. The optimal

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

    SciTech Connect

    Kargapol'tsev, Sergei V; Velichansky, Vladimir L; Vasil'ev, V V [P.N. Lebedev Physics Institute, Russian Academy of Sciences, Moscow (Russian Federation); Kobyakova, M Sh; Morozyuk, A V; Shiryaeva, N V; Konyaev, V P [M.F. Stel'makh Polyus Research and Development Institute, Moscow (Russian Federation)

    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)

  12. 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

  13. 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.

  14. Frequency tuning of a CW atomic iodine laser via the Zeeman effect

    Microsoft Academic Search

    M. A. Kelly; J. K. McIver; R. F. Shea; G. D. Hager

    1991-01-01

    A continuously operating, C3F7I photolytic 1.315-?m atomic iodine laser has been used to make the first precise observations of frequency tuning of an atomic iodine laser by means of the Zeeman effect. Application of a uniform magnetic field to the gain region of the photolytic iodine laser causes the laser to operate at different frequencies as a function of the

  15. Experimental comparison of Raman and RF outcouplers for high flux atom lasers

    E-print Network

    J. E. Debs; D. Dring; P. A. Altin; C. Figl; J. Dugu; M. Jeppesen; J. T. Schultz; N. P. Robins; J. D. Close

    2009-08-28

    We study the properties of an atom laser beam derived from a Bose-Einstein condensate using three different outcouplers, one based on multi-state radio frequency transitions and two others based on Raman transitions capable of imparting momentum to the beam. We first summarize the differences that arise in such systems, and how they may impact on the use of an atom laser in interferometry. Experimentally, we examine the formation of a bound state in all three outcouplers, a phenomenon which limits the atom laser flux, and find that a two-state Raman outcoupler is the preferred option for high flux, low divergence atom laser beams.

  16. Experimental Effects of Atomic Oxygen on the Development of an Electric Discharge Oxygen Iodine Laser

    E-print Network

    Carroll, David L.

    Experimental Effects of Atomic Oxygen on the Development of an Electric Discharge Oxygen Iodine of the electric discharge iodine laser continues, the role of oxygen atoms downstream of the discharge region of atomic iodine where the O2(a1 ) was produced in a flowing electric discharge. Excess atomic oxygen

  17. Laser frequency stabilization using Zeeman effect

    Microsoft Academic Search

    B. Chron; H. Gilles; J. Hamel; O. Moreau; H. Sorel

    1994-01-01

    We describe a new and easy to handle method to stabilize the laser frequency on an atomic transition. This method, based on Zeeman effect, involves the circular dichroism of an atomic vapour submitted to a magnetic field. It is applied to the frequency stabilization of a single frequency LNA laser on (2 (2 ^3S1-2 ^3P0) helium transition. Nous dcrivons une

  18. Ultra-violet and resonant laser ablation coupled with microwave induced plasma atomic emission spectrometry and determination of tin in nickel based alloys by electrothermal atomizer atomic absorption and laser excited atomic fluorescence spectrometry

    NASA Astrophysics Data System (ADS)

    Yang, Xiaodong

    Chapter 1 reviews laser ablation in analytical atomic spectrometry. Laser ablation is categorized into two functions: one is used as a sample introduction method, the other function is used as a microprobe analysis method. Both fundamental and applicational aspects are reviewed with the citations of related papers. This chapter also serves as an introduction to the work which is described in chapter 2 and chapter 3 as laser ablation is a relatively new research area for the research group. In chapter 2, instrumentation for excimer (308nm) laser ablation of samples was coupled with a microwave induced plasma (MLP), and evaluated for its potential as an approach to solid sampling for atomic emission spectrometry. Operating parameters were optimized, and the effects of laser repetition rate and number of laser shots on the emission signal were investigated. The UV excimer laser removed more material than would be expected of an infrared laser of similar energy. The chromium detection limit in the solid steel sample was estimated to be about 500 mug/g. In chapter 3, a wavelength tunable optical parametric oscillator (OPO) laser was used to ablate a steel sample into the same apparatus described in chapter 2. The emission signal for the elements was selectively enhanced when the ablation wavelength was tuned to be in resonance with any atomic transition of that element. This was the first report of the observation of resonant ablation by use of optical detection, as prior reports of resonant ablation have used mass spectrometric detectors. Chapter 4 reviews the publications in laser excited atomic fluorescence spectrometry in recent eight years. The focus of the review is on recent development on new instruments and applications of this technique. Chapter 5 studies the determination of tin in nickel-based alloys with laser excited atomic fluorescence in a graphite furnace. Zeeman electrothermal atomizer atomic absorption spectrometry and inductively coupled plasma mass spectrometry methods were also used. The laser excited atomic fluorescence method turned out to be as accurate as the other techniques. The atomic fluorescence method was simple to develop and did not need a sophisticated background correction technique to do the analyses.

  19. Ultra-violet and resonant laser ablation coupled with microwave induced plasma atomic emission spectrometry and determination of tin in nickel based alloys by electrothermal atomizer atomic absorption and laser excited atomic fluorescence spectrometry

    Microsoft Academic Search

    Xiaodong Yang

    1998-01-01

    Chapter 1 reviews laser ablation in analytical atomic spectrometry. Laser ablation is categorized into two functions: one is used as a sample introduction method, the other function is used as a microprobe analysis method. Both fundamental and applicational aspects are reviewed with the citations of related papers. This chapter also serves as an introduction to the work which is described

  20. A simple laser system for atom interferometry S. Merlet, L. Volodimer, M. Lours, F. Pereira Dos Santos

    E-print Network

    Boyer, Edmond

    A simple laser system for atom interferometry S. Merlet, L. Volodimer, M. Lours, F. Pereira Dos We present here a simple laser system for a laser cooled atom interferometer, where all functions (laser cooling, interferometry and detection) are realized using only two extended cavity laser diodes

  1. 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

  2. Atomic emission and laser excited atomic fluorescence studies of the glow discharge for the analysis of microsamples

    SciTech Connect

    Becerra Marmolejo, E.

    1992-01-01

    The glow discharge as an atomizer for atomic spectroscopy offers excellent advantages that have not been fully exploited. In this work fundamental studies about the sputtering process of liquid microsamples was investigated. This work was done by two different approaches: Atomic Emission Spectroscopy using a wavelength modulation technique for simultaneous background correction, and Laser Excited Atomic Fluorescence Spectroscopy. In the first approach, the sample holder was a cooled cooper hollow electrode. The hollow depth as well as the atomizer operating parameters -- current, voltage, and pressure -- were optimized in order to follow the temporal behavior of the analyte. In the second approach, the sample holder was a hot planar copper electrode. Here, the atomic excitation process was produced by a copper vapor pumped dye laser at a repetition rate of 6,000 Hz, and the fluorescence signal was collected at 90 degrees from the laser path. In the atomic fluorescence studies a comparison of the pulsed and non-pulsed operating modes of the glow discharge was carried out. Also, information about the vertical atomic distribution in the chamber area was obtained. Calibration curves and figures of merit for lead and gallium using the atomic emission system and lead using the atomic fluorescence system were determined. The effect of sodium chloride as a matrix interferant was investigated using both techniques. The results of these studies using the two approaches along with brief discussions about their theoretical aspects are presented in this dissertation.

  3. Alumina vapour condensation on Mo( 1 1 0 ) surface and adsorption of copper and gold atoms on the formed oxide layer

    Microsoft Academic Search

    T. T Magkoev; K Christmann; A. M. C Moutinho; Y Murata

    2002-01-01

    Aluminium oxide vapour condensation on Mo(110) surface and subsequent adsorption of Cu and Au submonolayer films on the formed ultrathin oxide layer has been studied by X-ray photoelectron spectroscopy (XPS), Auger electron spectroscopy (AES) and reflectionabsorption infrared spectroscopy. AES and XPS data suggest that the oxide films formed in this way exhibit the properties characteristic for the bulk alumina, although

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

    SciTech Connect

    Glushkov, A. V. [Odessa University, P.O.Box 24a, Odessa-9, SE, 65009 (Ukraine); Institute for Spectroscopy of Russian Academy of Sciences, Troitsk, Moscow reg., 142090 (Russian Federation)

    2010-10-29

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

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

    NASA Astrophysics Data System (ADS)

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

    2009-02-01

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

  6. 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.

  7. IOP PUBLISHING JOURNAL OF PHYSICS B: ATOMIC, MOLECULAR AND OPTICAL PHYSICS J. Phys. B: At. Mol. Opt. Phys. 46 (2013) 025402 (10pp) doi:10.1088/0953-4075/46/2/025402

    E-print Network

    Carroll, David L.

    2013-01-01

    and predictions for a continuous wave exciplex pumped alkali laser David L Carroll and Joseph T Verdeyen CU The exciplex pumped alkali laser (XPAL) system has been demonstrated in mixtures of Cs vapour, Ar provide an advantageous pathway for optically pumping atomic alkali lasers on the principal series

  8. 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

  9. Generation of Two-Flavor Vortex Atom Laser from a Five-State Medium

    E-print Network

    Xiong-Jun Liu; Hui Jing; Xin Liu; Mo-Lin Ge

    2007-02-14

    Two-flavor atom laser in a vortex state is obtained and analyzed via electromagnetically induced transparency (EIT) technique in a five-level $M$ type system by using two probe lights with $\\pm z$-directional orbital angular momentum $\\pm l\\hbar$, respectively. Together with the original transfer technique of quantum states from light to matter waves, the present result can be extended to generate continuous two-flavor vortex atom laser with non-classical atoms.

  10. Temperature dependent gain of the atomic xenon laser Gregory A. Hebne?)

    E-print Network

    Kushner, Mark

    the gain and efficiency of the atomic xenon laser at gas tem- peratures less than 325 K,1-3,6the functionalTemperature dependent gain of the atomic xenon laser Gregory A. Hebne?) Sandia National(3/2),-6p(5/2),] and 2.03 pm [5d(3/2)t- 6p( 3/2) t] atomic xenon transitions for gas temperatures

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

    PubMed

    Liu, Chunmei; Manz, Jrn; 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

  12. 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.

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

    SciTech Connect

    Matos, J. B. de; Rodrigues, N. A. S. [Department of Physics, Technological Institute for Aeronautics ITA/DCTA, So Jos dos Campos, P.O. Box 6050, 12.228-900 Sao Paulo (Brazil); Destro, M. G.; Silveira, C. A. B. da [Photonics Division, Institute for Advanced Studies IEAv/DCTA, So Jos dos Campos, P.O. Box 6044, 12.231-970 Sao Paulo (Brazil)

    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.

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

    PubMed

    de Matos, J B; Destro, M G; da Silveira, C A B; Rodrigues, N A S

    2014-08-01

    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(2) to 32 J/cm(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(4) K to 2.4 10(4) K and a Mach number of M = 2.36, calculated using purely hydrodynamic expansion approximation. PMID:25173267

  15. Analysis of Nanometer Structure for Chromium Atoms in Gauss Standing Laser Wave

    NASA Astrophysics Data System (ADS)

    Zhang, Wen-Tao; Zhu, Bao-Hua; Xiong, Xian-Ming

    2010-12-01

    The equation of motion of two-level chromium atoms in Gauss standing laser wave is discussed and the distribution of chromium atoms is given under different transverse velocity conditions. The results show that the focusing position of atoms will be affected by the transverse velocity of atoms. Based on the four-order Runge-Kutta method, the locus of chromium atoms in Gauss standing laser wave is simulated. The three-dimensional characteristics of nanometer structures are stimulated under perfect and emanative conditions.

  16. Quantum Control of Atomic Hydrogen Using Laser Fields

    NASA Astrophysics Data System (ADS)

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

    2007-06-01

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

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

    E-print Network

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

    2010-01-01

    We study the superfluorescence (SF) from a gas of rubidium atoms. The atoms of a dense vapor are excited to the 5D state from the 5S state by a two-photon process driven by 100-fs laser pulses. The atoms decay to the 6P state and then to the 5S...

  18. Parametric excitation of laser-guided Cs atoms in a hollow-core optical fiber

    Microsoft Academic Search

    Shin'ichiro Hayashi; Akio Ishimizu; Takehisa Tohei; Maki Tachikawa

    2003-01-01

    Laser radiation propagating through a hollow-core fiber exerts a central force on atoms toward the beam axis. Motion of Cs atoms guided through a glass capillary by the optical gradient force is experimentally investigated by the parametric excitation method, in which periodic modulation of the potential depth resonantly enhances atomic oscillations around the fiber axis. Broadband structure of the observed

  19. PHYSICAL REVIEW A 83, 063830 (2011) Laser-cooled atoms inside a hollow-core photonic-crystal fiber

    E-print Network

    Vuletic, Vladan

    2011-01-01

    PHYSICAL REVIEW A 83, 063830 (2011) Laser-cooled atoms inside a hollow-core photonic-crystal fiber of laser-cooled rubidium atoms into a single-mode hollow-core photonic-crystal fiber. Inside the fiber]. Here, we present an approach making use of laser-cooled atoms trapped inside such a hollow-core fiber

  20. Zeeman effect spectroscopically locked Cs diode laser system for atomic physics

    Microsoft Academic Search

    K. R. Overstreet; J. Franklin; J. P. Shaffer

    2004-01-01

    We present a diode laser system for Cs that uses a dichroic atomic vapor laser lock (DAVLL) to obtain stable single frequency operation around 852 nm from a high power quantum well index guided laser diode, >170 mW (JDS Uniphase SDL-5401-G1 and SDL-5421-G1). The laser diode is locked to an external cavity formed by a diffraction grating in the Littrow

  1. Laser microprobe and resonant laser ablation for depth profile measurements of hydrogen isotope atoms contained in graphite

    Microsoft Academic Search

    Masafumi Yorozu; Tatsuya Yanagida; Terunobu Nakajyo; Yasuhiro Okada; Akira Endo

    2001-01-01

    We measured the depth profile of hydrogen atoms in graphite by laser microprobing combined with resonant laser ablation. Deuterium-implanted graphite was employed for the measurements. The sample was ablated by a tunable laser with a wavelength corresponding to the resonant wavelength of1S-2S of deuterium with two-photon excitation. The ablated deuterium was ionized by a 2 + 1 resonant ionization process.

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

    E-print Network

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

    2015-01-01

    We have constructed a solid-state light source for experiments with laser cooled lithium atoms based on a Nd:YVO$_4$ ring laser with second-harmonic generation. Unidirectional lasing, an improved mode selection, and a high output power of the ring laser was 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 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.

  3. 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.

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

    E-print Network

    Hayrapetyan, Armen G; Surzhykov, Andrey; Fritzsche, Stephan

    2013-01-01

    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...

  5. 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

  6. 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

  7. Charge states of high Z atoms in a strong laser field

    SciTech Connect

    Susskind, S.M.; Valeo, E.J.; Oberman, C.R.; Bernstein, I.B. (Princeton Univ., NJ (USA). Plasma Physics Lab.; Yale Univ., New Haven, CT (USA))

    1989-11-01

    We present a numerical solution of the Thomas-Fermi atom in the presence of a static electric field as a model of the adiabatic response of a heavy atom in the presence of a strong laser field. In this semiclassical approach, we calculate the resulting charge state of the atom and its induced dipole moment after the field is turned on. Due to the scaling properties of the Thomas-Fermi approach, the resulting total atomic charge and dipole moment can be expressed as a universal function of the field. We compare our results with recent ionization experiments performed on noble gases using laser fields. 7 refs., 5 figs.

  8. Applied atomic collision physics. Volume 3 - Gas lasers

    Microsoft Academic Search

    E. W. McDaniel; W. L. Nighan

    1982-01-01

    The theoretical basis, development, functional principles, and applications of gas lasers are detailed. Energy transfer, direct excitation, photodissociation, chemical, and excimer lasers are described. Attention is given to the theory of lasers, the production of excited states, and the kinetics and spectroscopy of excited states, as well as techniques for the extraction of laser energy. Various aspects of charged particle

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

    E-print Network

    Stoo, Veit; Ott, Christian; Blttermann, 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...

  10. Characterisation Of Excited Atom Reaction Dynamics By Laser Induced Fluorescence

    NASA Astrophysics Data System (ADS)

    Wissenfeld, John R.; Harmon, Troy M.; Jursich, Gregory M.; Kagan, Mark R.

    1986-06-01

    Recent advances in laser technology have made available to chemists reliable sources of tunable, narrow bandwidth radiation in the ultraviolet and vacuum ultraviolet regions. It has thus become possible to detect with unprecedented sensitivity the diatomic products of bimolecular chemical reactions with resolution of electronic, vibrational, rotational, and even fine structure states. In our laboratory, special attention has been given to studies of the reactivity of optically metastable, electronically excited carbon an0 oxygen atoms, C( D) and 0('D). Examined in detail has been the reaction of C('D) with H2 in which the population of the product CH(v"=O) A doublet states is found to Be inverted. The reaction was further shcown to proceed via a long-lived 'CH collision complex. Extensive studies of 0(D) + H2 ? OH + H using hydrogen isotopes have demonstrated the importance of angular momentum constraints on the dynamics of HOH collision complex dissociation. Most recently, we have been successful in detecting the CN product of C('D) + NO ? CN + 0('D), evidence for excited oxygen formation having been inferred from the observed CN product energetics. Also to be discussed will be the detection of highly vibrationally excited OH radicals by off-diagonal LIF in the Av = -1i -2 progressions. These experiments provide the first direct evidence that 0('D) + H2 proceeds exclusively by insertion/dissociation with no significant contribution from direct hydrogen abstraction.

  11. 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.

  12. Laser-pumped atomic clock exploiting pressure-broadened optical transitions

    Microsoft Academic Search

    James Camparo; John Coffer; Jeremy Townsend

    2005-01-01

    The alkali-vapor-cell atomic clock, of either the conventional or the coherent population trapping type, offers one of the most viable approaches to making ultraminiature and chip-scale devices. Unfortunately, this atomic clock suffers from two laser-induced noise processes: conversion of laser phase noise (PM) to amplitude noise (AM) and ac-Stark-shift fluctuations. Here we demonstrate a method for circumventing these problems in

  13. Determination of low concentration of atoms by the intracavity laser spectroscopy method

    NASA Astrophysics Data System (ADS)

    Sinitsa, Leonid N.; Serdyukov, V. I.

    1995-08-01

    Intracavity laser spectroscopy method is very effective for investigation of weak absorption spectra for detection of atoms in water and soil. Intracavity laser spectroscopy can provide both low detection limit (105at/cm3) and the high speed operation of measurements that allows one to have results of measurements practically in a real time scale. In this paper the results of detection of low concentration of U-atoms are presented.

  14. Investigations on laser ablationmicrowave induced plasmaatomic emission spectrometry using polymer samples

    Microsoft Academic Search

    F. Leis; H. E. Bauer; L. Prodan; K. Niemax

    2001-01-01

    The potential of laser ablationmicrowave induced plasmaatomic emission spectrometry (LAMIPAES) for the analysis of plastic materials has been investigated. A Nd\\/YAG laser, operated in its fundamental mode at 1064 nm, was used to ablate small amounts of various plastics. The sample atoms were transported and excited in a closely neighbored continuously running microwave induced plasma (MIP) operated in argon or

  15. High-order harmonic generation on atoms and ions with laser fields of relativistic intensities

    SciTech Connect

    Avetissian, H. K.; Markossian, A. G.; Mkrtchian, G. F. [Centre of Strong Fields Physics, Yerevan State University, 1 A. Manukian, Yerevan 0025 (Armenia)

    2011-07-15

    High-order harmonic generation (HHG) by hydrogenlike atoms or ions in the field of counterpropagating laser beams of standing-wave configuration, with linear polarizations and relativistic intensities, is studied. The relativistic quantum theory of HHG in such field configurations (homogeneous), at which the impeding factor of relativistic magnetic drift of superstrong laser fields can be eliminated, is presented.

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

    Microsoft Academic Search

    Dimitar Slavov; C. Affolderbach; Gaetano Mileti

    2005-01-01

    We have characterized teh spectral properties and wavelength tuning behaviour of different types of diode lasers in order to evaluate their potential for applications in atomic spectroscopy and precision instruments. Here we report on studies of recently developed distributed feedback (DFB) and Fabry-Perot laser diodes, emitting around 780 and 795 nm, in solitary operation as well as in an extended-cavity

  17. Complete electromagnetically induced transparency in sodium atoms excited by a multimode dye laser

    E-print Network

    Complete electromagnetically induced transparency in sodium atoms excited by a multimode dye laser experimentally by means of excitation with a broadband multimode dye laser tuned on the D1 line. One hundred orders of magnitude narrower than the natural width of the corresponding optical transitions. CPT

  18. Measurement of depth profile of hydrogen isotope atom contained in solid material using resonant laser ablation

    Microsoft Academic Search

    Masafumi Yorozu; Yasuhiro Okada; Terunobu Nakajyo; Akira Endo

    1999-01-01

    The depth profile of hydrogen isotope atoms was measured by using mass spectrometry combined with resonant laser ablation. A graphite sample was implanted with deuterium by a cyclotron and was employed for the measurements. The graphite sample was ablated by a tunable laser which wavelength was corresponding to the resonant wavelength of 1S - 2S for deuterium with two- photon

  19. Excitation mechanism of IR transitions in the xenon atom in a nuclear-pumped laser

    Microsoft Academic Search

    Karelin

    1998-01-01

    A numerical simulation is used to show that new experimental data on the rate constants of xenon atoms in metastable and resonant states lead to a revision of the existing views on the mechanism of excitation of the upper active levels of a laser operating on IR transitions in xenon. (lasers, active media)

  20. Excitation mechanism of IR transitions in the xenon atom in a nuclear-pumped laser

    SciTech Connect

    Karelin, A V [A.M. Prokhorov General Physics Institute, Russian Academy of Sciences, Moscow (Russian Federation)

    1998-07-31

    A numerical simulation is used to show that new experimental data on the rate constants of xenon atoms in metastable and resonant states lead to a revision of the existing views on the mechanism of excitation of the upper active levels of a laser operating on IR transitions in xenon. (lasers, active media)

  1. The Production of Strong Blast Waves through Intense Laser Irradiation of Atomic Clusters

    Microsoft Academic Search

    T. Ditmire; K. Shigemori; B. A. Remington; K. Estabrook; R. A. Smith

    2000-01-01

    An understanding of radiation effects on the evolution of shock waves is of great importance to many problems in astrophysics. Shock waves driven by a laser-heated plasma are attractive for laboratory investigation of these phenomena. Recent studies of intense short-pulse laser interactions with gases of atomic clusters indicate a potential avenue to access this regime of radiative hydrodynamics. We have

  2. Diode-Pumped Alkali Atom Lasers 03LW024 Final Report

    Microsoft Academic Search

    R H Page; R J Beach

    2005-01-01

    The recent work at LLNL on alkali-atom lasers has been remarkably successful and productive. Three main phases (so far) can be identified. First, the concept and demonstration of red lasers using (Ti:sapphire pumping) took place; during this time, Rubidium and Cesium resonance-line lasers were tested, and theoretical models were developed and shown to describe experimental results very reliably. Work done

  3. Shakedown in core photoelectron spectra from aligned laser-excited Na atoms

    SciTech Connect

    Schulz, J.; Tchaplyguine, M.; Rander, T.; Bjoerneholm, O.; Svensson, S.; Sankari, R.; Heinaesmaeki, S.; Aksela, H.; Aksela, S.; Kukk, E. [Department of Physics, Uppsala University, Box 530, SE-75121 Uppsala (Sweden); Department of Physical Sciences, P.O.Box 3000, FIN-90014 University of Oulu (Finland); Department of Physics, University of Turku, FIN-20014 Turku (Finland)

    2005-07-15

    In an experiment combining a state-of-the-art visible laser system with the vacuum ultraviolet beamline I411 at the storage ring MAX II, shakedown satellite lines in the 2p photoelectron emission of excited Na atoms have been observed. A close investigation of these lines shows a strong dependency of the line intensities from the linear polarization angle of the laser light. The shakedown electrons are preferably emitted into the direction of the laser electric field vector.

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

    Microsoft Academic Search

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

    1988-01-01

    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 10⁷ atoms for 0.2 sec and cool them to a temperature of 100\\/sup +100\\/..sqrt.. ..mu..K in this viscous photon medium (the so-called optical molasses).

  5. A Review of Applications and Experimental Improvements Related to Diode Laser Atomic Spectroscopy

    Microsoft Academic Search

    Gbor Galbcs

    2006-01-01

    This article attempts to review the major advancements made in the past 12 years, since 1993, in the field of diode laser atomic spectroscopy. The discussion covers experimental improvements (e.g., wavelength stabilization, frequency upconversion, enhancement of tuning characteristics, spectral bandwidth using external cavities, etc.), diagnostic applications in various atomizers, as well as analytical applications (e.g., absorption, fluorescence, and ionization spectroscopy;

  6. Atom cooling using the dipole force of a single retroflected laser beam

    SciTech Connect

    Xuereb, Andre; Freegarde, Tim [School of Physics and Astronomy, University of Southampton, Southampton SO17 1BJ (United Kingdom); Horak, Peter [Optoelectronics Research Centre, University of Southampton, Southampton SO17 1BJ (United Kingdom)

    2009-07-15

    We present a mechanism for cooling atoms by a laser beam reflected from a single mirror. The cooling relies on the dipole force and thus in principle applies to arbitrary refractive particles including atoms, molecules, or dielectric spheres. Friction and equilibrium temperatures are derived by an analytic perturbative approach. Finally, semiclassical Monte Carlo simulations are performed to validate the analytic results.

  7. Measurement of the Hyperfine Splitting of Alkali Atoms in Superfluid Helium for Laser Spectroscopy of Atoms with Unstable Nuclei

    NASA Astrophysics Data System (ADS)

    Imamura, Kei; Furukawa, Takeshi; Wakui, Takashi; Yang, Xiaofei; Mitsuya, Yousuke; Fujita, Tomomi; Ebara, Yuta; Hayasaka, Miki; Ichikawa, Yuichi; Shirai, Hazuki; Suzuki, Takahiro; Sato, Tomoya; Ohtomo, Yuichi; Kojima, Shuichiro; Asahi, Koichiro; Hatakeyama, Atsushi; Odashima, Hitoshi; Kobayashi, Tohru; Ueno, Hideki; Matsuo, Yukari

    We have developed a new nuclear laser spectroscopy method that is named "OROCHI" (Optical RI-atom Observation in Condensed Helium as Ion-catcher). OROCHI utilizes superfluid helium both as an effective stopper of highly energetic ion beams and as a host matrix for in-situ laser spectroscopy of radioactive isotopes (RIs). Zeeman splitting energy and hyperfine splitting energy (HFS) of the atoms introduced into He II are measured to deduce nuclear spins and moments, respectively. So far, we have confirmed the feasibility of OROCHI to RIs by observing the Zeeman resonance successfully using 84-87Rb beam delivered from RIPS (RIKEN Projectile fragmentation Separator) beamline in RIBF. Recently, we have also successfully observed the HFS resonance of the injected 87Rb atoms. We report the details of the experiment.

  8. Enhancement of Efficiency of XUV Generation in Atomic Gases Irradiated by Intense Laser Fields

    NASA Astrophysics Data System (ADS)

    Andreev, A. V.; Stremoukhov, S. Y.; Shoutova, O. A.

    We present the results of the theoretical study of the high-order harmonic generation (HHG) in atomic gases. It is shown that the photoemission spectra exhibit unusual behavior when the laser field strength approaches near-atomic values. In subatomic field strength the cut-off frequency increases linearly with laser pulse intensity. However, when the field strength approaches near-atomic region firstly cut-off frequency slows down and then saturates. To interpret such kind of photoemission spectrum behavior we have proposed the light-atom interaction theory based on the use of eigenfunctions of boundary value problem for "an atom in the external field" instead of the traditional basis of the "free atom" eigenfunctions.

  9. 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

  10. 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

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

    Microsoft Academic Search

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

    2011-01-01

    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 30,000 rubidium

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

    Microsoft Academic Search

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

    2011-01-01

    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 ~30,000 rubidium

  13. Thermogravimetric analysis for boiling points and vapour pressure

    Microsoft Academic Search

    J. W. Goodrum; E. M. Siesel

    1996-01-01

    A TGA instrument has been adapted for rapid measurement of boiling points and vapour pressure at temperatures from ambient up to 400C and pressures from ambient down to 20 mm Hg. Samples were contained in sealed holders having a laser-drilled aperture. Several organic liquids in the 100 to 300 gMW range showed good agreement with reference vapour pressure data. Sample

  14. Multiphoton ionization of iodine atoms and CF 3I molecules by XeCl laser radiation

    NASA Astrophysics Data System (ADS)

    Lokhman, V. N.; Ogurok, D. D.; Ryabov, E. A.

    2008-01-01

    We report about effective ionization of iodine atoms and CF3I molecules under the action of intense XeCl laser radiation (308 nm). The only ion fragment resulting from the irradiation of the CF3I molecules is the I+ ion. We have studied the influence of the intensity, spectral composition, and polarization of the laser radiation used on the intensity of the ion signal and the shape of its time-of-flight peak. Based on the analysis of the results obtained, we have suggested the mechanism of this effect. The conclusion drawn is that the ionization of the iodine atoms by the ordinary XeCl laser with a nonselective cavity results from a three- (2 + 1)-photon REMPI process. This process is in turn due to the presence of accidental two-photon resonances between various spectral components of the laser radiation and the corresponding intermediate excited states of the iodine atom. The probability of ionization of the atoms from their ground state I(2P3/2) by the radiation of the ordinary XeCl laser is more than two orders of magnitude higher than the probability of their ionization from the metastable state I*(2P1/2). The ionization of the CF3I molecules by the XeCl laser radiation occurs as a result of a four-photon process involving the preliminary one-photon dissociation of these molecules and the subsequent (2 + 1)-photon REMPI of the resultant neutral iodine atoms.

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

    SciTech Connect

    Tong, X. M. [Institute of Materials Science, University of Tsukuba, 1-1-1 Tennodai, Tsukuba, Ibaraki 305-8573 (Japan); Center for Computational Sciences, University of Tsukuba, 1-1-1 Tennodai, Tsukuba, Ibaraki 305-8577 (Japan); Ranitovic, P. [James R. Macdonald Laboratory, Physics Department, Kansas State University, Manhattan, Kansas 66506 (United States); JILA, University of Colorado and NIST, Boulder, Colorado 80309-0441 (United States); Cocke, C. L. [James R. Macdonald Laboratory, Physics Department, Kansas State University, Manhattan, Kansas 66506 (United States); Toshima, N. [Institute of Materials Science, University of Tsukuba, 1-1-1 Tennodai, Tsukuba, Ibaraki 305-8573 (Japan)

    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.

  16. Accuracy of pulsed laser atom probe tomography for compound semiconductor analysis

    NASA Astrophysics Data System (ADS)

    Mller, M.; Gault, B.; Smith, G. D. W.; Grovenor, C. R. M.

    2011-11-01

    Atom probe tomography has recently experienced a renaissance, strongly promoted by the revival of pulsed laser atom probe. The technique is now widely employed to study semiconductor materials at the nanometre level. This paper summarises some aspects of the accuracy of pulsed laser atom probe relevant to semiconductor applications. It is shown that laser pulsing can reduce the lateral resolution due to thermally stimulated surface migration. Moreover, the commonly observed cluster ions can undergo field dissociation which results in an increased probability of ion loss due to pile-up effects at the detector. Field dissociation can also induce a new type of local magnification that increases spatial inaccuracy in the data reconstruction. These effects can be reduced by an appropriate choice of experimental parameters. Despite these difficulties, the atom probe technique can provide unparalleled insight into the nanoscale structure and chemistry of a wide range of semiconductor devices.

  17. Lasers as a Bridge between Atomic and Nuclear Physics

    E-print Network

    Sergei G. Matinyan

    1997-06-02

    This paper reviews the application of optical and UV laser radiation to several topics in low-energy nuclear physics. We consider the laser-induced nuclear anti-Stokes transitions, the laser-assisted and the laser-induced internal conversion, and the Electron Bridge and Inverse Electron Bridge mechanisms as tools for deexciting and exciting of low-lying nuclear isomeric states. A study of the anomalous, by low-lying, nuclear isomeric states (on an example of the $^{229}$Th nucleus) is presented in detail.

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

    SciTech Connect

    Page, R H; Beach, R J

    2005-02-16

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

  19. Explosion of atomic clusters irradiated by high-intensity laser pulses: Scaling of ion energies with cluster and laser parameters

    E-print Network

    Ditmire, Todd

    , with a view to experimental optimization of the cluster explosion temperature. The noble-gas clusters were as noble-gas clusters explode. The ions are stripped to very high charge states 1,3,4 and the x-ray yieldExplosion of atomic clusters irradiated by high-intensity laser pulses: Scaling of ion energies

  20. LASERS, ACTIVE MEDIA: Excitation mechanism of IR transitions in the xenon atom in a nuclear-pumped laser

    Microsoft Academic Search

    A. V. Karelin

    1998-01-01

    A numerical simulation is used to show that new experimental data on the rate constants of xenon atoms in metastable and resonant states lead to a revision of the existing views on the mechanism of excitation of the upper active levels of a laser operating on IR transitions in xenon. Bibtex entry for this abstract Preferred format for this abstract

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

    SciTech Connect

    Kaprlov-?nsk, Petra Ruth, E-mail: kapralova@jh-inst.cas.cz [Department of Radiation and Chemical Physics, Institute of Physics, Academy of Sciences of the Czech Republic, Na Slovance 2, 182 21 Prague 8 (Czech Republic); J. Heyrovsky Institute of Physical Chemistry, Academy of Sciences of the Czech Republic, Dolejkova 3, 182 23 Prague 8 (Czech Republic); Moiseyev, Nimrod, E-mail: nimrod@tx.technion.ac.il [Schulich Faculty of Chemistry and Faculty of Physics, Technion Israel Institute of Technology, Haifa 32000 (Israel)

    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.

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

    SciTech Connect

    Di Domenico, Gianni; Devenoges, Laurent; Dumas, Claire; Thomann, Pierre [Laboratoire Temps-Frequence, Universite de Neuchatel, Avenue de Bellevaux 51, CH-2009 Neuchatel (Switzerland)

    2010-11-15

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

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

    Microsoft Academic Search

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

    2011-01-01

    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

  4. Effects of laser energy and wavelength on the analysis of LiFePO? using laser assisted atom probe tomography

    DOE PAGESBeta

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

    2015-01-01

    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 oxygenmoreconcentration to nearer its correct stoichiometry, which was also well correlated with systematically higher concentrations of ?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

  5. Effects of laser energy and wavelength on the analysis of LiFePO? using laser assisted atom probe tomography

    SciTech Connect

    Santhanagopalan, Dhamodaran [Univ. of California, San Diego, CA (United States); Khalifah, Peter [Stony Brook Univ., NY (United States); Brookhaven National Lab., Upton, NY (United States); Schreiber, Daniel K. [Pacific Northwest National Lab. (PNNL), Richland, WA (United States); Perea, Daniel E. [Pacific Northwest National Lab. (PNNL), Richland, WA (United States); Martens, Richard L. [Univ. of Alabama, Tuscaloosa, AL (United States); Janssen, Yuri [Stony Brook Univ., NY (United States); Meng, Ying Shirley [Univ. of California, San Diego, CA (United States)

    2015-01-01

    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 ?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.

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

    SciTech Connect

    Affolderbach, Christoph; Mileti, Gaetano [Observatoire de Neuchatel, Rue de l'Observatoire 58, 2000 Neuchatel (Switzerland)

    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.

  7. Photoelectron momentum distributions of atomic and molecular systems in strong circularly or elliptically polarized laser fields

    NASA Astrophysics Data System (ADS)

    He, Pei-Lun; Takemoto, Norio; He, Feng

    2015-06-01

    Photoelectron momentum distributions of a hydrogen atom in an elliptically polarized laser field and a hydrogen molecular ion in a circularly polarized laser field are studied by simulating the time-dependent Schrdinger equation. We demonstrate that, in both systems, the Coulomb interaction between a liberated electron and its parent ion is essential for the photoelectron momentum angular drift in a laser polarization plane. By decomposing the wave packet into the rescattered and directly ionized components in the case of a hydrogen molecular ion, we reveal that the rescattered component drifts by a larger angle. The drift angle of the photoelectron of the hydrogen atom decreases monotonically with longer wavelength, while a nonmonotonic dependence is shown for H2+. We attribute such nonmonotonicity to the fluctuation of the instant of ionization for H2 + as the laser wavelength is changed.

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

    E-print Network

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

    2009-01-01

    A thermal atomic beam of dysprosium (Dy) atoms is cooled using the $4f^{10}6s^2(J=8) \\to 4f^{10}6s6p (J=9)$ transition at 421 nm. The cooling is done via a standing light wave orthogonal to the atomic beam. Efficient transverse cooling to a temperature of $\\sim$ 22 mK is demonstrated for all stable isotopes of dysprosium. Branching ratios to metastable states are demonstrated to be $<2\\times10^{-4}$. A scheme for enhancement of the odd-isotope cooling is proposed as well as a method for direct identification of possible trap states.

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

    SciTech Connect

    Leefer, N.; Cingoez, A. [Department of Physics, University of California at Berkeley, Berkeley, California 94720-7300 (United States); Gerber-Siff, B. [Swarthmore College, Swarthmore, Pennsylvania 19081 (United States); Sharma, Arijit [Raman Research Institute, Sadashivanagar, Bangalore 560080 (India); Torgerson, J. R. [Physics Division, Los Alamos National Laboratory, Los Alamos, New Mexico 87545 (United States); Budker, D. [Department of Physics, University of California at Berkeley, Berkeley, California 94720-7300 (United States); Nuclear Science Division, Lawrence Berkeley National Laboratory, Berkeley, California 94720 (United States)

    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.

  10. Laser-excited atomic fluorescence in a pulsed hollow-cathode glow discharge.

    PubMed

    Glick, M; Smith, B W; Winefordner, J D

    1990-01-15

    A pulsed glow discharge with low background noise is evaluated as an atom reservoir for laser-induced atomic fluorescence spectroscopy. Aqueous solutions are dried in graphite electrodes that are used as disposable hollow cathodes. Atomic vapor is produced in a flowing-gas glow discharge with a water-cooled cathode holder. A dye laser triggers a switching circuit that pulses that glow discharge, and fluorescence measurements are made 100 microseconds after the discharge is extinguished. The atomic population is large during this dark period, while the background emission is negligible. Linear calibration curves are obtained by nonresonance fluorescence for two elements, Pb and Ir. The detection limits for Pb are 100 pg/mL and 500 fg, and for Ir are 6 ng/mL and 20 pg. The experimental detection limit for Pb is compared to the intrinsic detection limit. PMID:2310012

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

    Microsoft Academic Search

    N. Cyr; M. Breton; M. Tetu; S. Theriault

    1991-01-01

    First results are reported on the frequency control of an AlGaAs laser diode by resonant phase-conjugate reflection from an atomic rubidium vapor. When the electrical feedback technique is used, the Allan variance reaches a flicker floor. It is also demonstrated that laser frequency locking can be achieved by using the phase-conjugate reflection directly as a resonant optical feedback. This approach

  12. Shaping coherent excitation of atoms and molecules by a train of ultrashort laser pulses

    SciTech Connect

    Gogyan, A. [Institute for Physical Research, Armenian National Academy of Sciences, Ashtarak-2, 0203 (Armenia); Laboratoire Interdisciplinaire Carnot de Bourgogne, UMR CNRS 5209, BP 47870, F-21078 Dijon (France); Guerin, S. [Laboratoire Interdisciplinaire Carnot de Bourgogne, UMR CNRS 5209, BP 47870, F-21078 Dijon (France); Malakyan, Yu. [Institute for Physical Research, Armenian National Academy of Sciences, Ashtarak-2, 0203 (Armenia); Centre of Strong Field Physics, Yerevan State University, 1 A. Manukian St., Yerevan 0025 (Armenia)

    2010-03-15

    We propose a mechanism to produce a superposition of atomic and molecular states by a train of ultrashort laser pulses combined with weak control fields. By adjusting the repetition rate of the pump pulses and the intensity of the coupling laser, one can suppress a transition while simultaneously enhancing the desired transitions. As an example, various superpositions of vibrational states of the K{sub 2} molecule are shown.

  13. Spin polarisation of electrons scattered superelastically by laser-excited Na atoms

    Microsoft Academic Search

    G F Hanne; C Szmytkowski; M van der Wiel

    1982-01-01

    The authors have measured the spin polarisation of electrons scattered superelastically from laser-excited Na atoms at a collision energy of 20 eV and a scattering angle of 30 degrees . The measured spin polarisation is 0.095+or-0.048 for scattering from the 3p2P1\\/2 excited state of Na. The polarisation changes sign if the laser is tuned to the 3p 2P3\\/2 state, as

  14. Scattering of polarized laser light by an atomic gas in free space: a QSDE approach

    E-print Network

    Luc Bouten; John K. Stockton; Gopal Sarma; Hideo Mabuchi

    2007-01-30

    We propose a model, based on a quantum stochastic differential equation (QSDE), to describe the scattering of polarized laser light by an atomic gas. The gauge terms in the QSDE account for the direct scattering of the laser light into different field channels. Once the model has been set, we can rigorously derive quantum filtering equations for balanced polarimetry and homodyne detection experiments, study the statistics of output processes and investigate a strong driving, weak coupling limit.

  15. Long-Range Interactions between cw Self-Focused Laser Beams in an Atomic Vapor

    Microsoft Academic Search

    A. C. Tam; W. Happer

    1977-01-01

    We have observed that circularly polarized laser beams of opposite (equal) polarizations in an alkali vapor repel (attract) each other for laser frequencies on the high-frequency wing of the D1 line. Our experiments indicate that these long-range noncontact interactions are mediated by the exchange of polarized atoms between the beams. The repulsion between sigma+ and sigma- beams leads to the

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

    Microsoft Academic Search

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

    2007-01-01

    We present and investigate different external cavity diode laser (ECDL) configurations for the manipulation of neutral atoms, wavelength-stabilized by a narrow-band high transmission interference filter. A novel diode laser, providing high output power of more than 1W, with a linewidth of less than 85kHz, based on a self-seeded tapered amplifier chip has been developed. Additionally, we compare the optical and

  17. 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.

  18. Atomic levels population and depopulation kinetics in Cu-vapor laser

    NASA Astrophysics Data System (ADS)

    Isaev, A. A.; Mikhelsoo, V. T.; Petrash, G. G.; Peet, V. E.; Ponomarev, I. V.

    1989-06-01

    Kinetics of population and depopulation of atomic copper ground state, resonance and metastable levels and also some higher laying levels were measured in active medium of copper vapor laser. A typical commercial sealed-off self-heated discharge tube was studied. Simultaneously at the same conditions of operation characteristics of excitation pulse and gain in active medium were measured. The measurements were made for the whole temperature interval of laser action.

  19. Z-pinch photo-pumped pulsed atomic iodine laser. Final report Oct 81-Sep 82

    SciTech Connect

    Stone, D.H.; Saunders, D.P.; Clark, M.C.

    1984-03-01

    A pulsed atomic iodine laser (CF3I) was designed and constructed using a coaxial xenon flash lamp as a pump source. The flash lamp was operated at low pressure to obtain pulse compression via xenon self-pinch. Electrical and optical diagnostics were performed for various xenon and CF3I pressures. Calorimeter data and burn patterns were obtained for the laser. Time-resolved spectroscopic data were taken throughout the CF3I pump band.

  20. Determination of additives in PVC material by UV laser ablation inductively coupled plasma atomic emission spectrometry

    Microsoft Academic Search

    M. Hemmerlin; J. M. Mermet; M. Bertucci; P. Zydowicz

    1997-01-01

    UV laser ablation inductively coupled plasma atomic emission spectrometry (LA-ICP-AES) has been applied to the direct determination of additives in solid poly(vinyl chloride) materials. A Nd:YAG laser, operating at its fourth harmonic (266 nm), was used with a beam masking device, in the most reproducible conditions, to introduce solid particles into the plasma torch of a simultaneous ICP-AES system. Emphasis

  1. Laser-assisted ionization of atomic hydrogen by electrons in the second Born approximation

    SciTech Connect

    Zheng Mingyang [Department of Modern Physics, University of Science and Technology of China, P. O. Box 4, Hefei, Anhui 230026 (China); Li Shumin [Department of Modern Physics, University of Science and Technology of China, P. O. Box 4, Hefei, Anhui 230026 (China); Institut fuer Theoretische Physik, Universitaet Heidelberg, Philosophenweg 16, D-69120 Heidelberg (Germany)

    2010-08-15

    Electron-impact ionization of atomic hydrogen in the presence of a linearly polarized laser field is studied in the second Born approximation. The state of fast electron in the laser field is described by the Volkov state, while the dressed state of the ejected slow electron and atomic hydrogen is treated perturbatively to the first order. We calculate the triple differential cross section in the Ehrhardt asymmetric coplanar geometry. Numerical results show that the triple differential cross sections of the first Born approximation are significantly improved when the second-order corrections are taken into account.

  2. Two-stage laser cooling and optical trapping of thulium atoms

    NASA Astrophysics Data System (ADS)

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

    2014-07-01

    We propose to use the magnetic-dipole transition at ? = 1.14 ?m coupling two ground state fine-structure components of thulium (Tm), as a clock transition in optical clocks. We have demonstrated first stage laser cooling of Tm atoms down to a temperature of 25??K using a strong transition at ? = 410.6 nm and we have also shown preliminary results for second stage cooling using a weaker transition at ? = 530.7 nm (natural linewidth ?G = 350?kHz). Laser cooled atoms have been trapped in an optical dipole trap and in a 1D optical lattice operating near 532?nm.

  3. Ionization of atoms by the spatial gradient of the pondermotive potential in a focused laser beam.

    PubMed

    Wells, E; Ben-Itzhak, I; Jones, R R

    2004-07-01

    Ionization of atoms by the spatial gradient of the pondermotive potential in a focused laser beam is investigated. Rydberg ions, formed during the interaction of noble gas atoms with an intense laser pulse, are used to probe the gradient field. Rydberg ion species with higher ionization potentials are produced at locations where the gradient field is largest. The measured Rydberg ion yields differ dramatically from estimates that ignore gradient-field ionization, but are in good agreement with predictions that include the effect. PMID:15323908

  4. 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.

  5. Making optical atomic clocks more stable with $10^{-16}$ level laser stabilization

    Microsoft Academic Search

    Y. Y. Jiang; A. D. Ludlow; N. D. Lemke; R. W. Fox; J. A. Sherman; L.-S. Ma; C. W. Oates

    2011-01-01

    The superb precision of an atomic clock is derived from its stability. Atomic\\u000aclocks based on optical (rather than microwave) frequencies are attractive\\u000abecause of their potential for high stability, which scales with operational\\u000afrequency. Nevertheless, optical clocks have not yet realized this vast\\u000apotential, due in large part to limitations of the laser used to excite the\\u000aatomic resonance.

  6. Laser-induced fluorescence measurement of oxygen atoms above a catalytic combustor surface

    SciTech Connect

    Pfefferle, L.D. (Yale University, Department of Chemical Engineering, New Haven, Connecticut 06520 (US)); Dyer, M.J.; Crosley, D.R. (SRI International, Molecular Physics Laboratory, 333 Ravenswood Avenue, Menlo Park, California 94025 (US))

    1990-01-01

    Two-photon laser-induced fluorescence has been used to detect oxygen atoms in the gas phase above a heated, catalytically stabilized combustor. Excitation was at 226 nm and detection at 777 nm. Special care using the collection optics was necessary to avoid detector saturation from intense thermal emission background from the heated plate. The experimental configuration together with considerations of quenching collisions and photochemical production of oxygen atoms are described.

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

    NASA Astrophysics Data System (ADS)

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

    2013-12-01

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

  8. 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

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

    E-print Network

    V. Yu. Argonov; S. V. Prants

    2004-09-17

    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 the 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 the intensity of the laser field, we observe numerically 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 in the sense that the measured characteristic of the motion, time of exit of atoms from a given space of the standing wave, is a complicated function that has a self-similar structure with singularities on a Cantor set of values of one of the control parameters.

  10. Thermal calcium atom interferometer with a phase resolution of a few milliradians based on a narrow-linewidth diode laser

    Microsoft Academic Search

    Tomoya Akatsuka; Yoshihiro Mori; Nobuhiko Sone; Yurie Ohtake; Mamoru Machiya; Atsuo Morinaga

    2011-01-01

    A symmetrical atom interferometer with a thermal calcium atom beam has been developed using a narrow linewidth diode laser stabilized to the resonance of a high-finesse cavity. The linewidth of the diode laser was estimated to be less than 1 Hz relative to the cavity resonance in noise measurement over the range of 100 Hz to 1 MHz, and the

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

    SciTech Connect

    Beaulieu, L.Y.; Godin, Michel; Laroche, Olivier; Tabard-Cossa, Vincent; Gruetter, Peter [Department of Physics and Physical Oceanography, Memorial University, St. John's, Newfoundland, A1B 37X (Canada); Division of Biological Engineering, Media Laboratory, Massachusetts Institute of Technology, 20 Ames Street, Cambridge, Massachusetts 02139 (United States); Physics Department, McGill University, Montreal, Quebec, H3A 2T8 (Canada)

    2006-02-20

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

  12. Laser wavelength effects on ionic and atomic emission from tin plasmas

    SciTech Connect

    Campos, D.; Harilal, S. S.; Hassanein, A. [School of Nuclear Engineering and Center for Materials Under Extreme Environment, Purdue University, 400 Central Drive, West Lafayette, Indiana 47907 (United States)

    2010-04-12

    We investigated the effects of laser wavelength on atomic and ionic emission from Sn plasmas. Plasmas were produced using planar Sn targets excited with 10.6 mum carbon dioxide (CO{sub 2}) and 1.06 mum neodymium-doped yttrium aluminum garnet (Nd:YAG) lasers. Two-dimensional spectral imaging of visible emission showed that continuum emission was significantly more intense in the CO{sub 2} laser produced plasma (LPP) whereas line emission was considerably more extensive in the Nd:YAG LPP. Faraday cup analysis showed that ion profiles were narrower with CO{sub 2} LPPs although they possessed higher kinetic energies.

  13. Search for laser-induced formation of antihydrogen atoms.

    PubMed

    Amoretti, M; Amsler, C; Bonomi, G; Bowe, P D; Canali, C; Carraro, C; Cesar, C L; Charlton, M; Ejsing, A M; Fontana, A; Fujiwara, M C; Funakoshi, R; Genova, P; Hangst, J S; Hayano, R S; Jrgensen, L V; Kellerbauer, A; Lagomarsino, V; Lodi Rizzini, E; Macr, M; Madsen, N; Manuzio, G; Mitchard, D; Montagna, P; Posada, L G C; Pruys, H; Regenfus, C; Rotondi, A; Telle, H H; Testera, G; Van der Werf, D P; Variola, A; Venturelli, L; Yamazaki, Y; Zurlo, N

    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 CO2 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. PMID:17155742

  14. 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 [P. N. Lebedev Physics Institute, Russian Academy of Sciences, Moscow (Russian Federation)

    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)

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

    SciTech Connect

    Kahn, E. H. [Washington State University; Langford, S. C. [Washington State University; Dickinson, J. T. [Washington State University; Boatner, Lynn A [ORNL

    2013-01-01

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

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

    E-print Network

    Gilowski, M; Zaiser, M; Herr, Werner; Wbbena, T; Wendrich, T; Mller, T; Rasel, E M; Ertmer, W

    2007-01-01

    We present and investigate different external cavity diode laser (ECDL) configurations for the manipulation of neutrals atoms, wavelength-stabilized by a narrow-band high transmission interference filter. A novel diode laser, providing high output power of more than 1 W, with a linewidth of less than 200 kHz, based on a self-seeded tapered amplifier chip has been developed. Additionally, we compare the optical and spectral properties of two laser systems based on common laser diodes, differing in their coating, as well as one, based on a distributed-feedback (DFB) diode. The linear cavity setup in all these systems combines a robust and compact design with a high wavelength tunability and an improved stability of the optical feedback compared to diode laser setups using diffraction gratings for wavelength discrimination.

  17. 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.

  18. Influence of external magnetic and laser radiation fields on Feshbach resonances in collision of atoms

    E-print Network

    E. A. Gazazyan; A. D. Gazazyan; V. O. Chaltykyan

    2012-09-21

    We study collision of two atoms with formation of Feshbach resonance at combined interaction with the external magnetic field and laser radiation. In cases of one- and two-photon resonances of laser radiation with two discrete vibrational molecular levels, we show that Feshbach resonances appear at interaction of external magnetic field with dressed states formed via Autler-Townes effect. In addition, in case of one-photon resonance the lower vibrational molecular state is coupled by laser radiation with the continuum of the elastic channel and forms laser-induced Feshbach resonance via both Autler-Townes effect and LICS mechanism. We study the combined process of formation of Feshbach resonances; this enables the control of Feshbach resonance by varying the magnetic field and intensity and frequency of laser radiation. We obtain the cross-sections of elastic and inelastic scattering and show that quenching of resonance occurs at the energy equal to that of the systems ground state. Dependence of the cross-sections on the magnetic field and laser intensity is examined in detail. In all considered cases, the scattering length is obtained depending on the magnetic and laser fields are studied. In the absence of magnetic interaction if the hyperfine substates of the quasibound state in the closed channel and those of individual colliding atoms in the open channel are the same, Feshbach resonances may arise via weak interaction between nuclear and electronic motions, which leads to transitions between electronic states. The obtained results can be employed in new studies of collisions of cold atoms, e.g., of alkali metal atoms and for interpretation of new experiments in BECs.

  19. Cavity-mediated collective laser-cooling of an atomic gas inside an asymmetric trap

    E-print Network

    Oleg Kim; Almut Beige

    2015-06-09

    This paper proposes a two-stage process for the collective cooling of a non-interacting atomic gas in a slightly anharmonic, asymmetric trap inside a relatively leaky optical cavity. During the first stage, the displacement stage, the atoms accumulate a small distance away from the trap centre. During the second stage, the cooling stage, a short laser pulse is applied which translates the initial displacement of the particles into a reduction of their vibrational energy with a collectively enhanced cooling rate. If this is followed by another displacement stage and both stages of the proposed cooling process are continuously repeated, the atomic gas is expected to reach a very low temperature.

  20. Atomic diffraction in counterpropagating Gaussian pulses of laser light

    SciTech Connect

    Simula, Tapio P.; Moelmer, Klaus [Lundbeck Foundation Theoretical Center for Quantum System Research, Department of Physics and Astronomy, University of Aarhus, DK-8000 Aarhus C (Denmark); Muradyan, Atom [Department of Physics, Yerevan State University, 1 Alex Manukian, Yerevan 375049 (Armenia)

    2007-12-15

    We present an analysis of atomic diffraction due to the interaction of an atomic beam with a pair of Gaussian light pulses. We derive a simple analytical expression for the populations in different diffraction orders. The validity of the obtained solution extends beyond the Raman-Nath regime, where the kinetic energy associated with different diffraction peaks is neglected, into the so-called channeling regime where accurate analytical expressions have not previously been available for the diffraction. Comparison with experimental results and exact numerical solutions demonstrate the validity of our analytical formula.

  1. The interaction of atomic clusters with intense laser fields

    SciTech Connect

    Hutchinson, M. H. R. [Central Laser Facility, Rutherford Appleton Laboratory, Chilton, Didcot, OX11 0QX (United Kingdom); Ditmire, T.; Tisch, J. W. G.; Springate, E.; Marangos, J. P.; Mason, M. B.; Smith, R. A. [Blackett Laboratory, Prince Consort Road, Imperial College of Science, Technology, and Medicine, London, SW7 2BZ (United Kingdom)

    1998-02-20

    The dynamics of the heating and dissociation of noble gas clusters when irradiated by intense, femtosecond laser pulses is described. The clusters explode with the generation of highly energetic electrons and ions. A plasma model of the ionised cluster is discussed.

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

    SciTech Connect

    Winefordner, J.D.

    1991-12-31

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

  3. Modulation transfer and optical Stark effect in a rubidium atomic clock pumped by a semiconductor laser

    Microsoft Academic Search

    Minoru Hashimoto; Motoichi Ohtsu

    1989-01-01

    Novel spectral line shapes of optical-microwave double resonance with an extremely narrow linewidth were observed in a rubidium atomic clock pumped by a semiconductor laser. It was confirmed that these novel spectral line shapes of double resonance were due to the modulation-transfer effect. These spectral line shapes were calculated by solving the equation of motion of the density matrix that

  4. Direct and resonance ionization of atomic sodium in crossed laser and synchrotron radiation beams: theory

    SciTech Connect

    Balashov, V. V.; Grum-Grzhimailo, A. N.; Zhadamba, V.

    1988-09-01

    The dependence of the photoabsorption, angular distribution, and polarization of photoelectrons on the orientation of an intermediate state of an atom under the conditions characteristic for experiments for direct and resonance photoionization in crossed beams of laser and synchrotron radiation is studied theoretically. Concrete computations are performed for the ionization of sodium through intermediate 3/ital P//sub /ital J// states.

  5. 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.

  6. Saturation of nonlinear susceptibility of noble gas atom in intense laser field

    Microsoft Academic Search

    M. Hatayama; M. Nurhuda; A. Suda; K. Nagasaka; K. Midorikawa

    2001-01-01

    We investigate the nonlinear susceptibility of noble gas atom interacting with intense laser field. The solution is obtained by solving the time dependent Schrodinger equation. It is shown that the behavior of nonlinear susceptibility strongly depends on the intensity; it increases almost linearly in low intensity regime, then becomes saturated at higher intensity. Furthermore, at intensity beyond the saturation value,

  7. Laser ablation processes investigated using inductively coupled plasmaatomic emission spectroscopy (ICPAES)

    Microsoft Academic Search

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

    1998-01-01

    The symbiotic relationship between laser ablation mechanisms and analytical performance using inductively coupled plasmaatomic emission spectroscopy are addressed in this work. For both cases, it is important to ensure that the ICP conditions (temperature and electron number density) are not effected by the ablated mass. By ensuring that the ICP conditions are constant, changes in spectral emission intensity will be

  8. Electron-ion collision rates in atomic clusters irradiated by femtosecond laser pulses

    Microsoft Academic Search

    M. Moll; P. Hilse; M. Schlanges; Th Bornath; V. P. Krainov

    2010-01-01

    In atomic clusters irradiated by femtosecond laser pulses, plasmas with high density and high temperature are created. The heating is mainly caused by inverse bremsstrahlung, i.e. determined by electron-ion collisions. In the description of the scattering of electrons on noble gas ions in such plasmas, it is important to account for the inner structure of the ions and the screening

  9. Atomic/Molecular-Level Simulations of LaserMaterials Interactions

    E-print Network

    Zhigilei, Leonid V.

    of experimental parameters in current applications, the emergence of new techniques, and interpretation equilibration, nonthermal atomic dynamics), active structural and phase transformations occurring in the high-temperature/high-pressure, fracture/spallation, explosive boiling, and surface vaporization), as well as long-term evolution

  10. Two-photon stimulated emission in laser-driven alkali-metal atoms using an orthogonal pump-probe geometry

    E-print Network

    Gauthier, Daniel

    Two-photon stimulated emission in laser-driven alkali-metal atoms using an orthogonal pump for building a two-photon laser. The two-photon stimulated emission is spectrally isolated and resonantly involving orthogonal beams and polarizations. The observed two-photon laser beam amplification increases

  11. IPredictions for gain in the fission-fragment-excited atomic xenon laser Jong W. Shon and Mark J. Kushnera)

    E-print Network

    Kushner, Mark

    IPredictions for gain in the fission-fragment-excited atomic xenon laser Jong W. Shon and Mark J xenon laser (5d-6p) is an attractive candidate for fission fragment excitation, which provides low gain at 1.73 and 2.03 pm has recently been measured in a reactor-excited xenon laser yielding values

  12. Excitation mechanisms and gain modeling of the high-pressure atomic Ar laser in He/M mixtures

    E-print Network

    Kushner, Mark

    of AI-; is believed to predominantly produce Ar( 4s) states. Electroionization from Ar metastables- ergy recirculation or electroionization process similar to the xenon laserJY8Electroionization in rare gas lasers refers to recirculation of atomic states from the laser levels to the rare gas metastables

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

    NASA Astrophysics Data System (ADS)

    Juregui, R.

    2015-04-01

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

  14. Spectroscopic studies of rubidium vapour zone produced by thermal evaporation in noble gas

    Microsoft Academic Search

    Shosuke Mochizuki; Ken-ichi Inozume; Raphael Ruppin

    1999-01-01

    The time evolution of the extinction spectra of the rubidium vapour zone has been measured during the process of gas evaporation. The structure of the spectra and their time dependence show the occurrence of atoms, dimers, clusters and microcrystals. Also, they show a size trend in the surface plasma resonance frequency of rubidium clusters. Also, vapour species in each zone

  15. Developing Density of Laser-Cooled Neutral Atoms and Molecules in a Linear Magnetic Trap

    NASA Astrophysics Data System (ADS)

    Velasquez, Joe, III; Walstrom, Peter; di Rosa, Michael

    2013-05-01

    In this poster we show that neutral particle injection and accumulation using laser-induced spin flips may be used to form dense ensembles of ultracold magnetic particles, i.e., laser-cooled paramagnetic atoms and molecules. Particles are injected in a field-seeking state, are switched by optical pumping to a field-repelled state, and are stored in the minimum-B trap. The analogous process in high-energy charged-particle accumulator rings is charge-exchange injection using stripper foils. The trap is a linear array of sextupoles capped by solenoids. Particle-tracking calculations and design of our linear accumulator along with related experiments involving 7Li will be presented. We test these concepts first with atoms in preparation for later work with selected molecules. Finally, we present our preliminary results with CaH, our candidate molecule for laser cooling. This project is funded by the LDRD program of Los Alamos National Laboratory.

  16. 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.

  17. Radiative collisional heating at the Doppler limit for laser-cooled magnesium atoms

    SciTech Connect

    Piilo, J. [Department of Physics, University of Turku, FIN-20014 Turun yliopisto (Finland); Institute of Solid State Physics, Bulgarian Academy of Sciences, Tsarigradsko chaussee 72, 1784 Sofia (Bulgaria); School of Pure and Applied Physics, University of KwaZulu-Natal, Durban 4041 (South Africa); Lundh, E. [Helsinki Institute of Physics, PL 64, FIN-00014 Helsingin yliopisto (Finland); Department of Physics, KTH, SE-10691 Stockholm (Sweden); Suominen, K.-A. [Department of Physics, University of Turku, FIN-20014 Turun yliopisto (Finland); Helsinki Institute of Physics, PL 64, FIN-00014 Helsingin yliopisto (Finland)

    2004-07-01

    We report Monte Carlo wave function simulation results on cold collisions between magnesium atoms in a strong red-detuned laser field. This is the normal situation, e.g., in magneto-optical traps (MOT). The Doppler limit heating rate due to radiative collisions is calculated for {sup 24}Mg atoms in an MOT based on the {sup 1}S{sub 0}-{sup 1}P{sub 1} atomic laser cooling transition. We find that radiative heating does not seem to affect the Doppler limit in this case. We also describe a channeling mechanism due to the missing Q branch in the excitation scheme, which could lead to a suppression of inelastic collisions, and find that this mechanism is not present in our simulation results due to the multistate character of the excitation process.

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

    E-print Network

    Carroll, David L.

    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

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

    E-print Network

    Fejer, Martin M.

    Diode-laser-based atomic absorption monitor using frequency-modulation spectroscopy for physical; accepted for publication 28 July 1995 We have developed an atomic monitoring system for physical vapor due to the velocity distribution of the atomic vapor within the deposition chamber have been measured

  20. WALES: WAter vapour Lidar Experiment in Space

    NASA Astrophysics Data System (ADS)

    Guerin, F.; Pain, Th.; Palmade, J. L.; Pailharey, E.; Giraud, D.; Jubineau, F.

    2004-06-01

    The WAter vapour Lidar Experiment in Space (WALES) mission aims at providing water vapour profiles with high accuracy and vertical resolution through the troposphere and the lower stratosphere on a global scale using an instrument based on Differential Absorption Lidar (DIAL) observation technique, and mounted on an Earth orbiting satellite. This active DIAL technique will also provide data on the cloud coverage by means of the signal reflection on the cloud layers. In DIAL operation, backscatter lidar signals at two wavelengths - at least - are detected. One wavelength (? ON) is highly absorbed by the species of interest, while the other (? OFF) is backscattered with minimal absorption. This difference in absorption at the two transmitted wavelengths leads to the determination of the concentration of the species of interest. The DIAL is therefore a dual-wavelength lidar in which the signals detected at the two wavelengths are processed to extract the absolute density of water vapour. The Phase A study performed by ALCATEL Space and their partners under contract of the European Space Agency has led to a credible and innovative concept of instrument, based on a mission performance modelling. The challenge is to foster the scientific return while minimising the development risks and costs of instrument development, in particular the laser transmitter. The paper describes the payload design and the implementation on a low Earth orbiting (LEO) satellite.

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

    E-print Network

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

    2007-01-01

    We have investigated cold ionizing heteronuclear collisions in dilute mixtures of metastable (2 3S1) 3He and 4He atoms, extending our previous work on the analogous homonuclear collisions [R. J. W. Stas et al., PRA 73, 032713 (2006)]. A simple theoretical model of such collisions enables us to calculate the heteronuclear ionization rate coefficient, for our quasi-unpolarized gas, in the absence of resonant light (T = 1.2 mK): K34(th) = 2.4*10^-10 cm^3/s. This calculation is supported by a measurement of K34 using magneto-optically trapped mixtures containing about 1*10^8 atoms of each species, K34(exp) = 2.5(8)*10^-10 cm^3/s. Theory and experiment show good agreement.

  2. Control of atomic transition rates via laser light shaping

    E-print Network

    Jauregui, R

    2015-01-01

    A modular systematic analysis of the feasibility of modifying atomic transition rates by tailoring the electromagnetic field of an external coherent light source is presented. The formalism considers both the center of mass and internal degrees of freedom of the atom, and all properties of the field: frequency, angular spectrum, and polarization. General features of recoil effects for internal forbidden transitions are discussed. A comparative analysis of different structured light sources is explicitly worked out. It includes spherical waves, Gaussian beams, Laguerre-Gaussian beams, and propagation invariant beams with closed analytical expressions. It is shown that increments in the order of magnitude of the transition rates for Gaussian and Laguerre-Gaussian beams, with respect to those obtained in the paraxial limit, requires waists of the order of the wavelength, while propagation invariant modes may considerably enhance transition rates under more favorable conditions. For transitions that can be natura...

  3. 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.

  4. 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.

  5. Counting radioactive noble gas atoms: Lasers, accelerators or decay counters?

    Microsoft Academic Search

    Bernhard E. Lehmann

    2001-01-01

    Radon-220 and Radon-222 in environmental air samples can be measured on-line with high temporal resolution by state-of-the-art alpha counting. Argon-37, Krypton-85 and Argon-39 are measured routinely by low level decay counting using high-pressure gas proportional counters in an underground laboratory. For Krypton-81 decay counting is not possible in environmental samples. Therefore, various attempts have been made to use atom counting

  6. Analytic description of elastic electron-atom scattering in an elliptically polarized laser field

    NASA Astrophysics Data System (ADS)

    Flegel, A. V.; Frolov, M. V.; Manakov, N. L.; Starace, Anthony F.; Zheltukhin, A. N.

    2013-01-01

    An analytic description of laser-assisted electron-atom scattering (LAES) in an elliptically polarized field is presented using time-dependent effective range (TDER) theory to treat both electron-laser and electron-atom interactions nonperturbatively. Closed-form formulas describing plateau features in LAES spectra are derived quantum mechanically in the low-frequency limit. These formulas provide an analytic explanation for key features of the LAES differential cross section. For the low-energy region of the LAES spectrum, our result generalizes the Kroll-Watson formula to the case of elliptic polarization. For the high-energy (rescattering) plateau in the LAES spectrum, our result generalizes prior results for a linearly polarized field valid for the high-energy end of the rescattering plateau [Flegel , J. Phys. BJPAPEH0953-407510.1088/0953-4075/42/24/241002 42, 241002 (2009)] and confirms the factorization of the LAES cross section into three factors: two field-free elastic electron-atom scattering cross sections (with laser-modified momenta) and a laser field-dependent factor (insensitive to the scattering potential) describing the laser-driven motion of the electron in the elliptically polarized field. We present also approximate analytic expressions for the exact TDER LAES amplitude that are valid over the entire rescattering plateau and reduce to the three-factor form in the plateau cutoff region. The theory is illustrated for the cases of e-H scattering in a CO2-laser field and e-F scattering in a midinfrared laser field of wavelength ?=3.5?m, for which the analytic results are shown to be in good agreement with exact numerical TDER results.

  7. CO/sub 2/ laser sustained CW discharge atomic beam source

    SciTech Connect

    Cross, J.B.; Cremers, D.A.; Spangler, L.H.; Hoffbauer, M.A.; Archuleta, F.A.

    1986-01-01

    A high pressure, supersonic, laser sustained plasma nozzle beam source has been developed for the production of intense (>10/sup 19/ particles s/sup 1/-sr/sup -1/) beams of atomic and/or radical species having kinetic energies in the range of 1 to 10 eV. A high plasma temperature (10 to 30,000 K) is produced in the throat of a hydrodynamic expansion nozzle by sustaining a cw optical discharge in a gas using a high power cw CO/sub 2/ laser. Gas mixtures are expanded through the nozzle/discharge region creating energetic atoms and molecules. An oxygen atom beam has been produced with a kinetic energy of 2 to 3 eV and an intensity of approx. 10/sup 18/ O-atoms s/sup -1/sr/sup -1/. O-atom collisions (1 eV) from an uncharacterized nickel surface shows strong specular scattering with approximately 50% energy loss to the surface. Argon beams having kinetic energies between 5 to 10 eV with intensities of >10/sup 19/ atoms s/sup -1/sr/sup -1/ have also been produced. 13 refs., 8 figs.

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

    SciTech Connect

    Tong, X. M. [Institute of Materials Science, Graduate School of Pure and Applied Sciences, University of Tsukuba, 1-1-1 Tennodai, Tsukuba, Ibaraki 305-8573 (Japan); Center for Computational Sciences, University of Tsukuba, 1-1-1 Tennodai, Tsukuba, Ibaraki 305-8577 (Japan); Ranitovic, P.; Hogle, C. W.; Murnane, M. M.; Kapteyn, H. C. [JILA and Department of Physics, University of Colorado and NIST, Boulder, Colorado 80309-0440 (United States); Toshima, N. [Institute of Materials Science, Graduate School of Pure and Applied Sciences, University of Tsukuba, 1-1-1 Tennodai, Tsukuba, Ibaraki 305-8573 (Japan)

    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.

  9. LETTER doi:10.1038/nature10721 Atomic inner-shell X-ray laser at 1.46 nanometres

    E-print Network

    Rocca, Jorge J.

    -ray free-electron laser Nina Rohringer1 {, Duncan Ryan2 , Richard A. London1 , Michael Purvis2 , Felicie7 . The introduction of X-ray free-electron lasers810 makes it possible to pump new atomic X-ray lasers11 and driven by rapid K-shell photo-ionization using pulses from an X-ray free-electron laser. We established

  10. 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.

  11. Wideband laser locking to an atomic reference with modulation transfer spectroscopy.

    PubMed

    Negnevitsky, V; Turner, L D

    2013-02-11

    We demonstrate that conventional modulated spectroscopy apparatus, used for laser frequency stabilization in many atomic physics laboratories, can be enhanced to provide a wideband lock delivering deep suppression of frequency noise across the acoustic range. Using an acousto-optic modulator driven with an agile oscillator, we show that wideband frequency modulation of the pump laser in modulation transfer spectroscopy produces the unique single lock-point spectrum previously demonstrated with electro-optic phase modulation. We achieve a laser lock with 100 kHz feedback bandwidth, limited by our laser control electronics. This bandwidth is sufficient to reduce frequency noise by 30 dB across the acoustic range and narrows the imputed linewidth by a factor of five. PMID:23481768

  12. Atomic inner-shell X-ray laser at 1.46 nanometres pumped by an X-ray free-electron laser.

    PubMed

    Rohringer, Nina; Ryan, Duncan; London, Richard A; Purvis, Michael; Albert, Felicie; Dunn, James; Bozek, John D; Bostedt, Christoph; Graf, Alexander; Hill, Randal; Hau-Riege, Stefan P; Rocca, Jorge J

    2012-01-26

    Since the invention of the laser more than 50 years ago, scientists have striven to achieve amplification on atomic transitions of increasingly shorter wavelength. The introduction of X-ray free-electron lasers makes it possible to pump new atomic X-ray lasers with ultrashort pulse duration, extreme spectral brightness and full temporal coherence. Here we describe the implementation of an X-ray laser in the kiloelectronvolt energy regime, based on atomic population inversion and driven by rapid K-shell photo-ionization using pulses from an X-ray free-electron laser. We established a population inversion of the K? transition in singly ionized neon at 1.46 nanometres (corresponding to a photon energy of 849 electronvolts) in an elongated plasma column created by irradiation of a gas medium. We observed strong amplified spontaneous emission from the end of the excited plasma. This resulted in femtosecond-duration, high-intensity X-ray pulses of much shorter wavelength and greater brilliance than achieved with previous atomic X-ray lasers. Moreover, this scheme provides greatly increased wavelength stability, monochromaticity and improved temporal coherence by comparison with present-day X-ray free-electron lasers. The atomic X-ray lasers realized here may be useful for high-resolution spectroscopy and nonlinear X-ray studies. PMID:22281598

  13. On-line characterisation of copper vapour evolution from linear vapour source generated using strip electron beam

    NASA Astrophysics Data System (ADS)

    Sahu, G. K.; Majumder, A.; Patankar, R. A.; Mago, V. K.; Thakur, K. B.

    2008-05-01

    In electron beam assisted physical vapour deposition (EB-PVD) technique, the online characterization of the evaporator is essential for process optimisation and control. In applications such as decorative and corrosion resistance coating, the knowledge of time average distribution of vapour is essential, whereas in some real time applications such as isotope purification, surface hardening and alloying etc., real time knowledge of vapour distribution and vapour propagation is important. The online characterization of various parameters related to the evaporator and associated processes using least expensive techniques is necessary to know the process throughput. Measurement of atom flux using quartz crystal thickness monitor can be one such techniques. The experimental studies were carried out to characterize the evaporator using thickness monitor by measuring copper vapour propagation and distribution over the two dimensional source. The experimental data measured at two heights corresponding to aspect ratio 2 and 3 are presented and the behaviour of expanding vapour is discussed. This technique can also be used to estimate the source temperature from the deposition rate data, which is discussed in the paper with its validation using measured temperature using two-colour pyrometer.

  14. Advances in the RF atomic iodine generator for oxygen-iodine laser

    NASA Astrophysics Data System (ADS)

    Jirsek, Vt; Schmiedberger, Josef; ?ensk, Miroslav; Kodymov, Jarmila

    2010-09-01

    Recent advances in the RF atomic iodine generator for oxygen-iodine lasers are presented. The generator is based on the RF discharge dissociation of a suitable iodine donor immediately before its injection to the flow of singlet oxygen. The discharge is ignited directly in the iodine injector, and the configuration is ready for the laser operation. The dissociation fraction was derived from the atomic iodine number density measured at a presupposed position of laser resonator. The dissociation fraction and the fraction of RF power spent on the dissociation (discharge dissociation efficiency) were measured for the following donors: CH3I, CF3I and HI. A significant improvement of the discharge stability was achieved by increasing the cross-sectional area of the exit injection holes and employing a tangential inlet of working gas into the discharge chamber. The flow rates 0.15 mmol/s and 0.19 mmol/s of produced atomic iodine were achieved using the HI and CF3I, respectively. The atomic iodine number density in the supersonic flow attained 4.22 1014 cm-3. The dissociation efficiency was substantially better for HI than for studied organic iodides.

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

    SciTech Connect

    Esnault, Francois-Xavier; Holleville, David; Rossetto, Nicolas; Guerandel, Stephane; Dimarcq, Noel [LNE-SYRTE, Observatoire de Paris, CNRS UPMC, 61 Avenue de l'Observatoire, 75014 Paris (France)

    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.

  16. 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.

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

    NASA Astrophysics Data System (ADS)

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

    2014-05-01

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

  18. Laser-Excited Atomic Fluorescence Spectrometry in a Pressure-Controlled Electrothermal Atomizer

    E-print Network

    Michel, Robert G.

    the removal of the analyte by diffusion. Varia- tion in working pressure was shown to affect the competi- tion pressure to 70 kPa. If a reduction in working pressure affected only the diffusion of the analyte, poorer of the conditions required for complete atomization are chemical modi- fication of the matrix, high heating rate

  19. Imaging of the expansion of femtosecond-laser-produced silicon plasma atoms by off-resonant planar laser-induced fluorescence.

    PubMed

    Samek, Ota; Leis, Franz; Margetic, Vanja; Malina, Radomir; Niemax, Kay; Hergenrder, Roland

    2003-10-20

    Planar laser-induced fluorescence measurements were used to investigate the expansion dynamics of a femtosecond laser-induced plasma. Temporally and spatially resolved measurements were performed to monitor the atoms that were ablated from a silicon target. A dye laser (lambda = 288.16 nm) was used to excite fluorescence signals. The radiation of an off-resonant transition (Si 390.55 nm) was observed at different distances from the target surface. This allowed easy detection of the ablated Si atoms without problems caused by scattered laser light. Abel inversion was applied to obtain the radial distribution of the Si atoms. The atom distribution in the plasma shows some peculiarities, depending on the crater depth. PMID:14594057

  20. 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.

  1. The Magnus expansion for interaction of atoms with attosecond laser pulses

    NASA Astrophysics Data System (ADS)

    Klaiber, Michael; Dimitrovski, Darko; Briggs, John S.

    2008-09-01

    The Magnus expansion of the time propagator for an atom in the classical field of a short, strong laser pulse is employed increasingly as attosecond pulses are developed. Here the lowest order terms are given explicitly and shown to be gauge invariant up to a given power of the laser-pulse length. The Kramers-Henneberger frame transformation is shown to lead to the same result and to be particularly suited for use with the Magnus expansion. A recently proposed modification of the first-order Magnus term is shown to be equivalent to the second order for a full-cycle pulse.

  2. Toward atomic resolution diffractive imaging of isolated molecules with x-ray free-electron lasers

    E-print Network

    Stern, Stephan; Filsinger, Frank; Rouze, Arnaud; Rudenko, Artem; Johnsson, Per; Martin, Andrew V; Barty, Anton; Bostedt, Christoph; Bozek, John D; Coffee, Ryan N; Epp, Sascha; Erk, Benjamin; Foucar, Lutz; Hartmann, Robert; Kimmel, Nils; Khnel, Kai-Uwe; Maurer, Jochen; Messerschmidt, Marc; Rudek, Benedikt; Starodub, Dmitri G; Thgersen, Jan; Weidenspointner, Georg; White, Thomas A; Stapelfeldt, Henrik; Rolles, Daniel; Chapman, Henry N; Kpper, Jochen

    2014-01-01

    We give a detailed account of the theoretical analysis and the experimental results of an x-ray-diffraction experiment on quantum-state selected and strongly laser-aligned gas-phase ensembles of the prototypical large asymmetric rotor molecule 2,5-diiodobenzonitrile, performed at the Linac Coherent Light Source [Phys. Rev. Lett. 112, 083002 (2014)]. This experiment is the first step toward coherent diffractive imaging of structures and structural dynamics of isolated molecules at atomic resolution, i. e., picometers and femtoseconds, using x-ray free-electron lasers.

  3. Toward atomic resolution diffractive imaging of isolated molecules with X-ray free-electron lasers.

    PubMed

    Stern, S; Holmegaard, L; Filsinger, F; Rouze, A; Rudenko, A; Johnsson, P; Martin, A V; Barty, A; Bostedt, C; Bozek, J; Coffee, R; Epp, S; Erk, B; Foucar, L; Hartmann, R; Kimmel, N; Khnel, K-U; Maurer, J; Messerschmidt, M; Rudek, B; Starodub, D; Thgersen, J; Weidenspointner, G; White, T A; Stapelfeldt, H; Rolles, D; Chapman, H N; Kpper, J

    2014-01-01

    We give a detailed account of the theoretical analysis and the experimental results of an X-ray-diffraction experiment on quantum-state selected and strongly laser-aligned gas-phase ensembles of the prototypical large asymmetric rotor molecule 2,5-diiodobenzonitrile, performed at the Linac Coherent Light Source [Phys. Rev. Lett.112, 083002 (2014)]. This experiment is the first step toward coherent diffractive imaging of structures and structural dynamics of isolated molecules at atomic resolution, i.e., picometers and femtoseconds, using X-ray free-electron lasers. PMID:25415561

  4. ATOMIC AND MOLECULAR PHYSICS: Intensity-dependent asymmetric photoionization in few-cycle laser pulses

    NASA Astrophysics Data System (ADS)

    Zhang, Xiao-Ming; Zhang, Jing-Tao; Gong, Qi-Huang; Xu, Zhi-Zhan

    2009-03-01

    The asymmetric photoionization of atoms irradiated by intense, few-cycle laser pulses is studied numerically. The results show that the pulse intensity affects the asymmetric photoionization in three aspects. First, at higher intensities, the asymmetry becomes distinctive for few-cycle pulses of longer durations. Second, as the laser intensity increases, the maximal asymmetry first decreases then increases after it has reached a minimal value. Last, the value of the carrier-envelope phase corresponding to the maximal asymmetry varies with the pulse intensity. This study reveals that the increasing of pulse intensity is helpful for observing the asymmetric photoionization.

  5. 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.

  6. 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.

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

    SciTech Connect

    Ariunbold, Gombojav O. [Institute for Quantum Studies and Department of Physics, Texas A and M University, College Station, Texas 77843 (United States); Department of Physics, National University of Mongolia, 210646 Ulaanbaatar (Mongolia); Kash, Michael M. [Institute for Quantum Studies and Department of Physics, Texas A and M University, College Station, Texas 77843 (United States); Department of Physics, Lake Forest College, Lake Forest, Illinois 60045 (United States); Sautenkov, Vladimir A. [Institute for Quantum Studies and Department of Physics, Texas A and M University, College Station, Texas 77843 (United States); Lebedev Institute of Physics, Moscow 119991 (Russian Federation); Li, Hebin; Welch, George R. [Institute for Quantum Studies and Department of Physics, Texas A and M University, College Station, Texas 77843 (United States); Rostovtsev, Yuri V. [Institute for Quantum Studies and Department of Physics, Texas A and M University, College Station, Texas 77843 (United States); Department of Physics, University of North Texas, 1155 Union Circle 311427, Denton, Texas 76203 (United States); Scully, Marlan O. [Institute for Quantum Studies and Department of Physics, Texas A and M University, College Station, Texas 77843 (United States); Applied Physics and Materials Science Group, Princeton University, Princeton, New Jersey 08544 (United States); Max-Planck-Institute fuer Quantenoptik, D-85748 Garching (Germany)

    2010-10-15

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

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

    NASA Astrophysics Data System (ADS)

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

    2011-11-01

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

  9. Exterior complex scaling method in TDDFT: HHG of Ar atoms in intense laser fields

    NASA Astrophysics Data System (ADS)

    Sosnova, Ksenia E.; Telnov, Dmitry A.; Rozenbaum, Efim; Chu, Shih-I.

    2014-04-01

    Exterior complex scaling (ECS) method is applied in the framework of the time-dependent density functional theory to study high-order harmonic generation (HHG) of multielectron atoms in intense laser fields. ECS allows to impose correct (outgoing-wave) boundary conditions on the wave functions at large distances. In the present work, ECS is combined with the time-dependent generalized pseudospectral method for accurate and efficient solution of the time-dependent Kohn-Sham equations. Results for HHG of Ar atoms are presented.

  10. Measurements of sulfur compounds in CO 2 by diode laser atomic absorption spectrometry

    NASA Astrophysics Data System (ADS)

    Franzke, J.; Stancu, D. G.; Niemax, K.

    2003-07-01

    Two simple methods for the analysis of the total concentration of sulfur in CO 2 by diode laser atomic absorption spectrometry of excited, metastable sulfur atoms in a direct current discharge are presented. In the first method, the CO 2 sample gas is mixed with the plasma gas (Ar or He) while the second is based on reproducible measurements of the sulfur released from the walls in a helium discharge after being deposited as a result of operating the discharge in pure CO 2 sample gas. The detection limits obtained satisfy the requirements for the control of sulfur compounds in CO 2 used in the food and beverage industry.

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

    NASA Astrophysics Data System (ADS)

    Klaiber, Michael; Dimitrovski, Darko

    2015-02-01

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

  12. Nuclear Signatures in High-Order Harmonic Generation from Laser-Driven Muonic Atoms

    SciTech Connect

    Shahbaz, A.; Mueller, C.; Staudt, A.; Keitel, C. H. [Max-Planck-Institut fuer Kernphysik, Saupfercheckweg 1, 69117 Heidelberg (Germany); Buervenich, T. J. [Frankfurt Institute for Advanced Studies, Johann Wolfgang Goethe University, Max-von-Laue-Strasse 1, 60438 Frankfurt (Germany)

    2007-06-29

    High-order harmonic generation from muonic atoms exposed to intense laser fields is considered. Our particular interest lies in effects arising from the finite nuclear mass and size. We numerically perform a fully quantum mechanical treatment of the muon-nucleus dynamics by employing modified soft-core and hard-core potentials. It is shown that the position of the high-energy cutoff of the harmonic spectrum depends on the nuclear mass, while the height of the spectral plateau is sensitive to the nuclear radius. We also demonstrate that {gamma}-ray harmonics can be generated from muonic atoms in ultrastrong VUV fields, which have potential to induce photonuclear reactions.

  13. Time-resolved ionization process of hydrogen atoms in strong laser fields

    NASA Astrophysics Data System (ADS)

    Cui, Sen; He, Feng

    2013-12-01

    Within the strong-field approximation, we study the time-resolved ionization process of a hydrogen atom in strong laser fields. At any time during the interaction between an atom and a laser field, the electron may instantaneously absorb all possible energies and build a wide momentum spectrum. As the interaction evolves in time, the coherent superposition of all previous instantaneous ionization events gradually filters out all other energy components except the part with an energy n? -Ip, where Ip is the ionization potential, ? is the photon energy, and n is a positive integer. The establishment of the electron energy spectra in above-threshold ionization, rescattering, and streaking can all be directly viewed by tracking the time-dependent momentum spectra.

  14. Isolated attosecond pulse generation from atom radiated by a three-color laser pulse

    NASA Astrophysics Data System (ADS)

    Qin, Yue-Fei; Guo, Fu-Ming; Li, Su-Yu; Yang, Yu-Jun; Chen, Gao

    2014-09-01

    We theoretically investigate high-order harmonic and attosecond pulse generation from helium atom in a three-color laser field, which is synthesized by 10 fs/800 nm Ti-sapphire laser and a two-color field consisting of 30 fs/532 nm and 30 fs/1330 nm pulses. Compared with harmonic spectrum generated by a monochromatic field, the harmonics generated from the synthesized three-color field show a supercontinuum spectrum with a bandwidth of 235 eV, ranging from the 154th to the 306th order harmonic. This phenomenon can be attributed to the fact that the ionization of atoms as well as motion of ionized electron can be effectively controlled in the three-color field. Therefore, an isolated 46-as pulse can be generated by superposing supercontinuum from the 160th to the 210th order harmonics.

  15. Influence of the atomic mass of the background gas on laser ablation plume propagation

    NASA Astrophysics Data System (ADS)

    Amoruso, Salvatore; Schou, Jrgen; Lunney, James G.

    2008-09-01

    A combination of time-of-flight ion probe measurements and gas dynamical modeling has been used to investigate the propagation of a laser ablation plume in gases of different atomic/molecular weight. The pressure variation of the ion time-of-flight was found to be well described by the gas dynamical model of Predtechensky and Mayorov (Appl. Supercond. 1:2011, 1993). In particular, the model describes how the pressure required to stop the plume in a given distance depends on the atomic/molecular weight of the gas, which is a feature that cannot be explained by standard point-blast-wave descriptions of laser ablation plume expansion in gas.

  16. Measurement of yields for electron emission from surfaces upon impact of laser-excited Ar*(4p) and Kr*(5p) atoms

    Microsoft Academic Search

    S. Schohl; H. A. J. Meijer; M.-W. Ruf; H. Hotop

    1992-01-01

    A laser method for the determination of the electron emission coefficient gamma for the impact of slow laser-excited rare gas atoms Rg*(mp5(m+1)p 3D3) on surfaces is described. It is based on controlled partial depletion of metastable Rg*(mp5(m+1)s 3P2) atoms in a collimated beam by two-step laser photoionization in combination with saturated laser excitation of the metastable (3P2) atoms to the

  17. 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.

  18. Two-photon ionization measurements on atomic caesium by means of an argon ion laser

    Microsoft Academic Search

    E H A Granneman; M J Van der Wiel

    1975-01-01

    Measurements are reported of two-photon ionization probabilities in atomic Cs at the nine wavelengths of the Ar ion laser (5145-4545 AA), the first step of the two-photon process occurring to intermediate levels in the vicinity of the 7 2P1\\/2,3\\/2 levels. Additional ionization due to molecular Cs was monitored by ion time-of-flight analysis and found to be negligible when choosing proper

  19. Precise laser spectroscopy of the antiprotonic helium atom and CPT test on antiproton mass and charge

    E-print Network

    H. Yamaguchi; J. Eades; R. S. Hayano; M. Hori; D. Horvath; T. Ishikawa; B. Juhasz; J. Sakaguchi; H. A. Torii; E. Widmann; T. Yamazaki

    2003-03-19

    We have measured twelve transition frequencies of the antiprotonic helium atom (pbar-He+) with precisions of 0.1--0.2 ppm using a laser spectroscopic method. The agreement between the experiment and theories was so good that we can put a limit on the proton-antiproton mass (or charge) difference. The new limit is expected to be much smaller than the already published value, 60 ppb.

  20. Intense terahertz emission from atomic cluster plasma produced by intense femtosecond laser pulses

    SciTech Connect

    Jahangiri, Fazel; Hashida, Masaki; Tokita, Shigeki; Sakabe, Shuji [Advanced Research Center for Beam Science, ICR, Kyoto University, Gokasho, Uji, Kyoto 611-0011, Japan and Department of Physics, GSS, Kyoto University, Kitashirakawa, Sakyo, Kyoto 606-7501 (Japan); Nagashima, Takeshi; Hangyo, Masanori [Institute of Laser Engineering, Osaka University, 2-6 Yamadaoka, Suita, Osaka 565-0871 (Japan)

    2011-12-26

    Terahertz (THz) emission from argon cluster plasma, generated by intense femtosecond laser pulses in the energy range of 10-70 mJ, has been investigated. THz polarization, energy dependence, and angular distribution were measured to provide an initial discussion on the mechanisms of THz emission. THz pulses of much higher energy were generated from argon clusters than from argon gas, which indicates that plasma produced from atomic clusters holds considerable promise as an intense THz source.

  1. Influence of low atomic number plasma component on the formation of laser-produced plasma jets

    SciTech Connect

    Kasperczuk, A.; Pisarczyk, T.; Badziak, J.; Borodziuk, S.; Chodukowski, T. [Institute of Plasma Physics and Laser Microfusion, 23 Hery St., 00-908 Warsaw (Poland); Gus'kov, S. Yu.; Demchenko, N. N. [Institute of Plasma Physics AS CR, v.v.i., Za Slovankou 3, 182 00 Prague 8 (Czech Republic); Ullschmied, J.; Krousky, E.; Masek, K.; Pfeifer, M.; Rohlena, K.; Skala, J. [Institute of Physics AS CR, v.v.i., Na Slovance 2, 182 21 Prague 8 (Czech Republic); Pisarczyk, P. [Warsaw University of Technology, ICS, 15/19 Nowowiejska St., 00-665 Warsaw (Poland)

    2010-11-15

    The results of investigations are presented that are connected with a very simple method of plasma jet formation, which consists in irradiating a massive planar target made of material with relatively high atomic number by a partly defocused laser beam. This brief communication is aimed at investigations of interaction of axially symmetrical light (plastic-CH) plasma with heavy (copper) plasma. It demonstrates that a relatively thin plastic plasma envelope can compress the Cu plasma and control the Cu-jet formation.

  2. 320 IEEE JOURNAL OF QUANTUMELECTRONICS, VOL. QE-18, No. 3, MARCH 1982 Optically Pumped Atomic Thulium Lasers

    E-print Network

    Bokor, Jeffrey

    Thulium Lasers J. C. WHITE, J. BOKOR, AND D. HENDERSON Abstract-A thulium vapor column isirradiated action in optically pumped atomic thulium vapor. A Tm vapor column was irradiated with intense radia

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

    NASA Astrophysics Data System (ADS)

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

    1996-09-01

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

  4. Bulk analysis by IR laser ablation inductively coupled plasma atomic emission spectrometry.

    PubMed

    Hemmerlin, M; Somas, D; Dubuisson, C; Loisy, F; Poussel, E; Mermet, J M

    2000-09-01

    Two laser ablation systems dedicated to bulk analysis were evaluated for steel and PVC samples, using inductively coupled plasma atomic emission spectrometry detection. These systems were characterized by the use of a Nd:YAG laser operating at 1064 nm, the absence of observation device and a large laser spot size. The 1064 nm wavelength was selected to avoid the use of frequency-multiplying optics, and to be less critical to the sampling position. Calibration graphs and limits of detection are given for both types of materials. LODs were in the range 3-120 microg/g for steel, and in the range 0.07-15 microg/g for PVC. In the case of steel samples, similar calibration graph slopes were obtained between polished and unpolished samples. PMID:11220827

  5. An all-solid-state laser source at 671 nm for cold atom experiments with lithium

    E-print Network

    Eismann, Ulrich; Canalias, Carlota; Zukauskas, Andrius; Trnec, Grard; Vigu, Jacques; Chevy, Frdric; Salomon, Christophe

    2011-01-01

    We present an all solid-state narrow line-width laser source emitting $670\\,\\mathrm{mW}$ output power at $671\\,\\mathrm{nm}$ delivered in a diffraction-limited beam. The source is based on a frequency-doubled diode-end-pumped ring laser operating on the ${^4F}_{3/2} \\rightarrow {^4I}_{13/2}$ transition in Nd:YVO$_4$. By using periodically-poled potassium titanyl phosphate (ppKTP) in an external build-up cavity, doubling efficiencies of up to 86% are obtained. Tunability of the source over $100\\,\\rm GHz$ is accomplished. We demonstrate the suitability of this robust frequency-stabilized light source for laser cooling of lithium atoms. Finally a simplified design based on intra-cavity doubling is described and first results are presented.

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

    NASA Astrophysics Data System (ADS)

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

    2014-01-01

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

  7. Application of x-ray lasers to current and future experiments in atomic and molecular physics

    SciTech Connect

    Caldwell, C. Denise [Department of Physics, University of Central Florida, Orlando, FL 32816-2385 (United States)

    1995-05-01

    The use of intrinsically narrow-banded, intense x-ray lasers has the potential for a significant impact in atomic and molecular physics. As with any new technology, it is impossible to predict all the new information which may emerge as the technology develops. At least at the beginning it will be important for these lasers to have applicability to existing experimental methods, which can then exploit the new tool for experiments which are currently barely feasible with existing and planned sources of radiation in the high-energy regime. Examples of these are: resonant Auger decay, particularly of dilute species, studied with electron spectrometry; multi-photon processes involving the simultaneous utilization of two laser photons; and fragmentation experiments in which the high-energy photon is one of a pump-probe pair. Results from these experiments will go a long way to suggesting directions for future study.

  8. Low phase noise diode laser oscillator for 1S-2S spectroscopy in atomic hydrogen

    E-print Network

    N. Kolachevsky; J. Alnis; C. G. Parthey; A. Matveev; R. Landig; T. W. Haensch

    2011-07-08

    We report on a low-noise diode laser oscillator at 972 nm actively stabilized to an ultra-stable vibrationally- and thermally compensated reference cavity. To increase the fraction of laser power in the carrier we designed a 20 cm long external cavity diode laser with an intra-cavity electro-optical modulator. The fractional power in the carrier reaches 99.9% which corresponds to a rms phase noise of $\\phi^2_\\textrm{rms}=1\\,\\textrm{mrad}^2$ in 10\\,MHz bandwidth. Using this oscillator we recorded 1S-2S spectra in atomic hydrogen and have not observed any significant loss of the excitation efficiency due to phase noise multiplication in the three consecutive 2-photon processes.

  9. Measurement of the Zeeman effect in an atomic anion: Prospects for laser cooling of Os-

    NASA Astrophysics Data System (ADS)

    Kellerbauer, A.; Fischer, A.; Warring, U.

    2014-04-01

    The negative osmium ion Os- is one of very few atomic anions potentially suitable for laser cooling. We have made a measurement of the Zeeman splitting of a bound-bound transition in 192Os- by studying the laser excitation from the 5d76s2 4F9/2e ground to the 5d66s26p 6D9/2o excited state in a homogeneous external magnetic field. The experimental Land factors gJ=1.31(7) and gJ=1.50(8), respectively, agree well with calculated values. Both levels are found to split into 10 Zeeman sublevels, resulting in 28 allowed transitions of different relative intensities, in agreement with calculations based on pure and composite LS states. In view of the experimental results, the prospects for laser cooling of Os- are discussed.

  10. High-fidelity modelling of an exciplex pumped alkali laser with radiative transport

    Microsoft Academic Search

    Andrew D. Palla; David L. Carroll; Joseph T. Verdeyen; Michael C. Heaven

    2011-01-01

    The exciplex-pumped alkali laser (XPAL) system has been demonstrated in mixtures of Cs vapour, Ar, and ethane by pumping Cs-Ar atomic collision pairs and subsequent dissociation of diatomic, electronically excited CsAr molecules (exciplexes or excimers). Because of the addition of atomic collision pairs and exciplex states, modelling of the XPAL system is far more complicated than the modelling of the

  11. Resonant-holographic-interferometry for absolute measurements of excimer laser-ablated neutral-atom plume line-density profiles

    Microsoft Academic Search

    R. M. Gilgenbach; R. A. Lindley; C. H. Ching; J. S. Lash

    1993-01-01

    Experiments have been performed to measure Al neutral atom absolute line-density profiles using resonant-holographic-interferometry. The ablation source is a KrF excimer laser with a per-pulse energy of about 0.8 J. Targets are either pure aluminum or Al2O3. Aluminum ground-state neutral atom line-densities are probed by a dye laser tuned near the 394.401 nm line. A double-pulse interferometry technique is employed

  12. Time-of-flight diode-laser velocimeter using a locally seeded atomic absorber: Application in a pulse detonation engine

    Microsoft Academic Search

    S. T. Sanders; D. W. Mattison; J. B. Jeffries; R. K. Hanson

    2003-01-01

    A diode-laser velocimeter based on atomic absorption spectroscopy has been developed and applied to a pulse detonation engine (PDE). The velocimeter uses a salt-coated sting to seed an atomic absorber at any desired location and a single, fixed-wavelength diode laser to monitor the absorber's presence downstream of the sting. Salt particles stripped from the sting tend to form distinct \\

  13. Pumping of atomic alkali lasers by photoexcitation of a resonance line blue satellite and alkali-rare gas excimer dissociation

    Microsoft Academic Search

    J. D. Readle; C. J. Wagner; J. T. Verdeyen; T. M. Spinka; D. L. Carroll; J. G. Eden

    2009-01-01

    Photoassociation of alkali-rare gas atomic collision pairs provides an alternative approach to optically pumping atomic alkali lasers. Lasing on the 6 2P1\\/2-->6 2S1\\/2 (D1) transition of Cs has been observed when the blue satellite of the 6 2P3\\/2<--6 2S1\\/2 (D2) transition, peaking at ~837 nm for mixtures of Cs vapor, Ar, and ethane, is pumped by a pulsed dye laser.

  14. Application of vortex-flow dc glow discharge for atomic iodine production for oxygen-iodine laser

    Microsoft Academic Search

    Pavel A. Mikheyev; Alexander A. Shepelenko

    2004-01-01

    The possibility to produce atomic iodine decomposing methyl iodide with the help of the vortex-flow DC glow discharge for use in oxygen-iodine laser has been investigated experimentally. Number density of iodine atoms had been measured via absorption of single frequency tunable semiconductor laser radiation at 1.315 mum. Two cases were studied: (1) the products of discharge in oxygen decomposed methyl

  15. Nondipole ionization dynamics in atoms induced by intense xuv laser fields

    NASA Astrophysics Data System (ADS)

    Frre, Morten; Simonsen, Aleksander Skjerlie

    2014-11-01

    Solving the time-dependent Schrdinger equation from first principles, the laser-induced breakup dynamics of hydrogen is studied beyond the electric dipole approximation, at very high laser intensities. It is assumed that the atom is being irradiated by an extreme ultraviolet laser light pulse at a wavelength of 13 nm, corresponding to a photon energy of 95 eV. It has already been experimentally demonstrated that the free-electron laser (FEL) FLASH in Hamburg can deliver irradiance levels up to about 1016W/cm2 in this wavelength range. Although we will go to even higher intensities in the present work, in order to spot nondipole effects, this merely demonstrates that ultrahigh light intensities can be achieved with present FEL technologies. Furthermore, with new seeding techniques the laser power is expected to go even higher in the future. In our study the atom is exposed to a short attosecond laser pulse, and the role of higher-order corrections to the electric dipole approximation is studied systematically. The main findings are that higher-order corrections beyond the leading first-order term, to a good approximation, can be neglected for all intensities within the nonrelativistic regime, provided the pulse duration is not too long. This means that the effect of second- and higher-order corrections only needs to be accounted for when entering the relativistic regime, within the scope of the Dirac equation. It is further found that the leading first-order correction to the dipole approximation has a great impact on the angular emission pattern of the low-energy photoelectrons.

  16. Photoinduced Electron and H-atom Transfer Reactions of Xanthone by Laser Flash Photolysis

    NASA Astrophysics Data System (ADS)

    Wang, Jin-ting; Pan, Yang; Zhang, Li-min; Yu, Shu-qin

    2007-08-01

    The property of the lowest excited triplet states of xanthone in acetonitrile was investigated using time-resolved laser flash photolysis at 355 nm. The transient absorption spectra and the quenching rate constants (kq) of the excited xanthone with several amines were determined. Good correlation between lgkq and the driving force of the reactions suggests the electron transfer mechanism, except aniline and 3-nitroaniline (3-NO2-A) which showed energy transfer mechanism. With the appearance of ketyl radical, hydrogen atom transfer also happened between xanthone and dimethyl-p-toluidine, 3,5,N,N-tetramethylaniline, N,N-dimethylaniline, and triethylamine. Therefore, both electron transfer and H-atom transfer occured in these systems. Great discrepancies of kq values were discovered in H-atom abstraction reactions for alcohols and phenols, which can be explained by different abstraction mechanisms. The quenching rate constants between xanthone and alcohols correlate well with the ?-C-H bonding energy of alcohols.

  17. A semiclassical study of laser-induced atomic fluorescence from Na2, K2 and NaK

    NASA Technical Reports Server (NTRS)

    Yuan, J.-M.; Bhattacharyya, D. K.; George, T. F.

    1982-01-01

    A semiclassical treatment of laser-induced atomic fluorescence for the alkali-dimer systems Na2, K2 and NaK is presented. The variation of the fluorescence intensity with the frequency of the exciting laser photon is studied and a comparison of theoretical results with a set of experimental data is presented.

  18. Asymmetry of the photoionization rate of H atoms by a sequence of one-cycle laser pulses

    Microsoft Academic Search

    Li-Hua Bai; Jing-Tao Zhang; Zhi-Zhan Xu

    2005-01-01

    Using an unperturbed scattering theory, the characteristics of H atom photoionization are studied respectively by a linearly- and by a circularly- polarized one-cycle laser pulse sequence. The asymmetry for photoelectrons in two directions opposite to each other is investigated. It is found that the asymmetry degree varies with the carrier-envelope (CE) phase, laser intensity, as well as the kinetic energy

  19. 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

  20. 852-nm distributed-feedback diode lasers for atomic clocks and laser cooling

    Microsoft Academic Search

    A. Klehr; H. Wenzel; G. Erbert; G. Trankle; T. Laurent; K. Haack

    2005-01-01

    We report on narrow linewidth DFB RW lasers emitting at the caesium D2 resonance wavelength. The devices operate in a single lateral and longitudinal mode up to 250 mW optical power with a spectral linewidth below 1 MHz.

  1. Laser-induced excitation and ionization of a confined hydrogen atom in an exponential-cosine-screened Coulomb potential

    NASA Astrophysics Data System (ADS)

    Lumb, Shalini; Lumb, Sonia; Prasad, Vinod

    2014-09-01

    The energy spectra of spherically confined hydrogen atom embedded in an exponential-cosine-screened Coulomb potential is worked out by using the Bernstein-polynomial method. The interaction of short laser pulses in the femtosecond range with the system is studied in detail. The effect of shape of laser pulse, confinement radius, Debye screening length as well as different laser parameters on the dynamics of the system has been explored and analyzed.

  2. Laser ablation inductively coupled plasma atomic emission spectrometry of a uranium-zirconium alloy: ablation properties and analytical behavior

    Microsoft Academic Search

    Phillip Goodall; Stephen G. Johnson; Elon Wood

    1995-01-01

    The ablation properties and analytical behavior of a uranium-zirconium alloy have been examined using tandem laser ablation\\/pneumatic nebulization sample introduction in conjunction with inductively coupled atomic emission spectrometry (LA-ICP-AES). An apparent change in composition of the laser ablation aerosol (115 GW cm?2 Zr deficient, 40250 GW cm?2 Zr rich) is observed. This phenomenon is independent of laser wavelength. After collection

  3. Measurement method for the nuclear anapole moment of laser-trapped alkali-metal atoms E. Gomez,1,

    E-print Network

    Orozco, Luis A.

    Measurement method for the nuclear anapole moment of laser-trapped alkali-metal atoms E. Gomez,1 for such measurements in francium, the heaviest alkali. DOI: 10.1103/PhysRevA.75.033418 PACS number s : 32.80.Pj, 32 transition between the ground hy- perfine levels in a chain of isotopes of an alkali-metal atom. Alkali

  4. Interaction of intense short laser pulses with gases of nanoscale atomic and molecular clusters

    NASA Astrophysics Data System (ADS)

    Gupta, Ayush

    We study the interaction of intense laser pulses with gases of van der Waals bound atomic aggregates called clusters in the range of laser-cluster parameters such that kinetic as well as hydrodynamic effects are active. The clustered gas absorbs the laser pulse energy efficiently, producing x-rays, extreme ultraviolet radiation, energetic particles and fusion neutrons. First, we investigate the effect of pulse duration on the heating of a single cluster in a strong laser field using a 2-D electrostatic particle-in-cell (PIC) code. Heating is dominated by a collision-less resonant absorption process that involves energetic electrons transiting through the cluster. A size-dependent intensity threshold defines the onset of this resonance [Taguchi et al., Phys. Rev. Lett., v90(20), (2004)]. It is seen that increasing the laser pulse width lowers this intensity threshold and the energetic electrons take multiple laser periods to transit the cluster instead of one laser period as previously recorded [Taguchi et al., Phys. Rev. Lett., v90(20), (2004)]. Results of our numerical simulations showing the effect of pulse duration on the heating rate and the evolution of the electron phase space are presented in this dissertation. Our simulations show that strong electron heating is accompanied by the generation of a quasi-monoenergetic high-energy peak in the ion kinetic energy distribution function. The energy at which the peak occurs is pulse duration dependent. Calculations of fusion neutron yield from exploding deuterium clusters using the PIC model with periodic boundary conditions are also presented. We also investigate the propagation of the laser pulse through a gas of clusters that is described by an effective dielectric constant determined by the single cluster polarizability. For computational advantage, we adopt a uniform density description of the exploding clusters, modified to yield experimentally consistent single cluster polarizability, and couple it to a Gaussian description of the laser pulse. This model is then used to study self-focusing, absorption, and spectral broadening of the laser pulse. The model is further extended to allow for a fraction of the gas to be present as unclustered monomers and to include the effect of unbound electrons produced in the laser-cluster interaction.

  5. Laser ablation mass removal versus incident power density during solid sampling for inductively coupled plasma atomic emission spectroscopy

    SciTech Connect

    Shannon, M.A.; Mao, X.L.; Fernandez, A.; Chan, W.T.; Russo, R.E. [Lawrence Berkeley National Lab., CA (United States)

    1995-12-15

    For laser ablation solid sampling, the quantity of material ablated (removed) influences the sensitivity of chemical analysis. The mass removal rate depends strongly on the laser power density, which is the main controllable parameter for a given material and wavelength parameter using laser solid sampling for inductively coupled plasma atomic emission spectroscopy (ICP-AES). For a wide variety of materials, a decrease in the rate of change, or roll-off, in mass removed is observed with increasing incident laser power density. The roll-off results from a change in the efficiency of material removed by the laser beam, primarily due to shielding of the target from the incident laser energy by a laser-vapor plume interaction. Several analytical technologies were employed to study the quantity of mass removed versus laser power density. Data for mass ablation behavior versus laser power density are reported using ICP-AES, atomic emission from a laser-induced plasma near the sample surface, acoustic stress power in the target, and measurements of crater volumes. This research demonstrates that the change in ICP-AES intensity with laser power density is due to changes in the mass removal. The roll-off in mass ablation is not due to a change in particle size distribution of the ablated species, fractionation of the sample, or a change in transport efficiency to the ICP torch. 29 refs., 10 figs.

  6. 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.

  7. 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.

  8. Laser microdissection of metaphase chromosomes and characterization by atomic force microscopy

    NASA Astrophysics Data System (ADS)

    Thalhammer, Stefan; Stark, Robert W.; Schuetze, Karin; Wienberg, Johannes; Heckl, Wolfgang M.

    1997-01-01

    A new experimental setup has been constructed in which a UV laser microbeam and atomic force microscopy (AFM) have been combined on an inverted microscope in order to manipulate and visualize chromosomes with high resolution. The laser beam has been used to dissect Muntjak metaphase chromosomes and was aimed to optimize the physical size of the cuts. The capability of the AFM to visualize biological materials with relative ease has been used to characterize the microdissected chromosomes. This work demonstrates that chromosome fiber material can be removed completely at the cut site using appropriate laser power. The minimum cut size achieved with a 337-nm nitrogen UV laser was between 600 and 800 nm. The smallest distance between the cuts was around 500 nm, corresponding to the finest probe for further biochemical use after physical translocation such as the polymerase chain reaction. Limitations on minimizing the cut size due to diffraction-limited focusing and the effects of laser ablation of biomaterial are discussed.

  9. Influence of external magnetic and laser radiation fields on Feshbach resonances in collision of atoms

    E-print Network

    Gazazyan, E A; Chaltykyan, V O

    2012-01-01

    We study collision of two atoms with formation of Feshbach resonance at combined interaction with the external magnetic field and laser radiation. In cases of one- and two-photon resonances of laser radiation with two discrete vibrational molecular levels, we show that Feshbach resonances appear at interaction of external magnetic field with dressed states formed via Autler-Townes effect. In addition, in case of one-photon resonance the lower vibrational molecular state is coupled by laser radiation with the continuum of the elastic channel and forms laser-induced Feshbach resonance via both Autler-Townes effect and LICS mechanism. We study the combined process of formation of Feshbach resonances; this enables the control of Feshbach resonance by varying the magnetic field and intensity and frequency of laser radiation. We obtain the cross-sections of elastic and inelastic scattering and show that quenching of resonance occurs at the energy equal to that of the systems ground state. Dependence of the cross-se...

  10. Simultaneous Elemental Composition and Size Distributions of Submicron Particles in Real Time Using Laser Atomization Ionization Mass Spectrometry

    Microsoft Academic Search

    William D. Reents; Zhaozhu Ge

    2000-01-01

    Composition and size of individual submicron particles have been measured using a laser atomization ionization mass spectrometry technique, the Particle Blaster. Individual particles are quantitatively converted to atomic cations, providing information on both their complete elemental composition and particle size. Measured average atomic ratios for 100 nm particles of sodium chloride is 1.12 +- 0.36 (Cl:Na), for 50 nm particles

  11. 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.

  12. Quantum synchronization of many coupled atoms for an ultranarrow linewidth laser

    NASA Astrophysics Data System (ADS)

    He, Peiru; Xu, Minghui; Tieri, David; Zhu, Bihui; Rey, Ana Maria; Hazzard, Kaden; Holland, Murray

    2014-05-01

    We theoretically investigate the effect of quantum synchronization on many coupled two-level atoms acting as high quality oscillators. We show that quantum synchronization - the spontaneous alignment of the phase (of the two-level superposition) between different atoms - provides a potential approach to produce robust atomic coherences and coherent light with ultranarrow linewidth and extreme phase stability. The atoms may be coupled either through their direct dipole-dipole interactions or, as in a superradiant laser, through an optical cavity. We develop a variety of analytic and computational approaches for this problem, including exact open quantum system methods for small systems, semiclassical theories, and approaches that make use of the permutation symmetry of identically coupled ensembles. We investigate the first and second order coherence properties of both the optical and atomic degrees of freedom. We study synchronization in both the steady-state, as well as during the dynamically applied pulse sequences of Rabi and Ramsey interferometry. This work was supported by the DARPA QuASAR program, the NSF, and NIST.

  13. Generation of pulsed, energy-selected metal atom-beam by laser vaporization of metal compounds. Interim report

    SciTech Connect

    Thiem, T.L.; Salter, R.H.; Watson, L.R.; Murad, E.; Dressler, R.A.

    1991-11-12

    A fast pulsed beam of neutral metal atoms is produced by laser vaporization of a solid metal compound sample in a modified high-temperature mass spectrometer. Atomic beams of several eV kinetic energy are generated at substantially lower laser power densities than necessary when irradiating a pure metal sample. The energy of the atomic beam can be controlled with the laser power, similar to studies conducted on thin metal films. The source, however, overcomes the problem of short sample lifetime associated with irradiating thin films. Samples have been irradiated for several hours without observing a change in beam intensity or energy, thus offering an interesting source for kinetic studies. The energy distribution is typically narrower than a Maxwell-Boltzman distribution. The dependence of the beam intensity and energy distribution on laser power and metal compound counter anion are presented.

  14. Thresholdless dressed-atom laser in a photonic band-gap material

    E-print Network

    Gao-xiang Li; Min Luo; Zbigniew Ficek

    2009-06-23

    We demonstrate the capability of complete thresholdless lasing operation between dressed states of a two-level atom located inside a microscopic cavity engineered in a photonic band-gap material. We distinguish between threshold and thresholdless behaves by analyzing the Mandel's Q parameter for the cavity field. We find that the threshold behave depends on whether the spontaneous emission is or is not present on the lasing transition. In the presence of the spontaneous emission, the mean photon number of the cavity field exhibits threshold behavior indicating that the system may operate as an ordinary laser. When the spontaneous emission is eliminated on the lasing transition, no threshold is observed for all values of the pumping rate indicating the system becomes a thresholdless laser. Moreover, we find that under a thresholdless operation, the mean photon number can increase nonlinearly with the pumping rate, and this process is accompanied by a sub-Poisson statistics of the field. This suggests that the nonclassical statistics can be used to distinguish a nonlinear operation of the dressed-atom laser.

  15. Effects of Chirped Laser Pulses on Nonclassical Correlation and Entanglement of Photon Pairs from Single Atom

    E-print Network

    C. H. Raymond Ooi

    2008-03-15

    We study the effects of arbitrary laser pulse excitations on quantum correlation, entanglement and the role of quantum noise. The transient quantities are computed exactly using a method that provides exact solutions of the Langevin field operators for photon pairs produced by a double Raman atom driven by laser pulses. Short pulses with appropriate chirping, delay and/or detuning can generate broadband photon pairs and yield results that provide insights on how to generate very large nonclassical correlation. We find that short pulses are not favorable for entanglement. The quantity was previously found to be phase-sensitive and this is used with the pulse area concept to explain the rapid variations of entanglement with pulse width and strength. Photon correlation and entanglement are favored by exclusively two different initial conditions. Analysis reinforces our understanding of the two nonclassical concepts.

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

    NASA Astrophysics Data System (ADS)

    Von Bandel, N.; Bb Manga Lob, J.; Garcia, M.; Larrue, A.; Robert, Y.; Vinet, E.; Lecomte, M.; Drisse, O.; Parillaud, O.; Krakowski, M.

    2015-03-01

    Time-frequency applications are in need of high accuracy and high stability clocks. Compact industrial Cesium atomic clocks optically pumped is a promising area that could satisfy these demands. However, the stability of these clocks relies, among others, on the performances of laser diodes that are used for atomic pumping. This issue has led the III-V Lab to commit to the European Euripides-LAMA project that aims to provide competitive compact optical Cesium clocks for earth applications. This work will provide key experience for further space technology qualification. We are in charge of the design, fabrication and reliability of Distributed-Feedback diodes (DFB) at 894nm (D1 line of Cesium) and 852nm (D2 line). The use of D1 line for pumping will provide simplified clock architecture compared to D2 line pumping thanks to simpler atomic transitions and larger spectral separation between lines in the 894nm case. Also, D1 line pumping overcomes the issue of unpumped "dark states" that occur with D2 line. The modules should provide narrow linewidth (<1MHz), very good reliability in time and, crucially, be insensitive to optical feedback. The development of the 894nm wavelength is grounded on our previous results for 852nm DFB. Thus, we show our first results from Al-free active region with InGaAsP quantum well broad-area lasers (100?m width, with lengths ranging from 2mm to 4mm), for further DFB operation at 894nm. We obtained low internal losses below 2cm-1, the external differential efficiency is 0.49W/A with uncoated facets and a low threshold current density of 190A/cm, for 2mm lasers at 20C.

  17. Multiphoton effects in laser-assisted ionization of a helium atom by electron impact

    NASA Astrophysics Data System (ADS)

    Ghosh Deb, S.; Sinha, C.

    2010-11-01

    The dynamics of the electron impact multiphoton ionization of a He atom in the presence of an intense laser field ( n ? _e, 2 e) is studied theoretically for laser polarization (\\vert\\vert^l) and perpendicular (bot^r) to the incident momentum. The triple differential (TDCS) as well as the double differential (DDCS) cross sections are studied for the coplanar asymmetric geometry. The results are compared with the only available kinematically complete experiment at high incident energy (1000 eV). Significant laser modification (enhancement) is noted due to multiphoton effects in the present binary and recoil peak intensities of the TDCS for both the geometries, in qualitative agreement with the experiment. In the single photon case, the net effect of the laser field is to suppress the field free (FF) TDCS as well as the DDCS in the zeroth order approximation of the ejected electron wave function (CV), while in the first order (MCV), the cross sections are found to be enhanced. The CV multiphoton cross sections obey the famous Kroll Watson (KW) sum rule while the latter does not hold good in the corresponding MCV approximation.

  18. 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.

  19. 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

  20. PHYSICAL PROCESSES IN LASERS: Spatial-temporal kinetics of the ground state population of the copper atom in a copper vapor laser

    NASA Astrophysics Data System (ADS)

    Isaev, A. A.; Mikhkel'soo, V. T.; Petrash, G. G.; Pet, V. .; Ponomarev, I. V.; Treshchalov, A. B.; Yurchenko, N. I.

    1989-06-01

    An analysis was made of a method of measuring the ground-state population of copper atoms in the medium of a self-heated copper vapor laser. The active medium was probed using radiation from a pulsed dye laser (temporal resolution 5 ns, spatial resolution 2 mm). An investigation was made of the ground-state kinetics during an excitation pulse and in an interpulse interval over the whole lasing temperature range of 1350-1650 C in a commercial UL-101 laser. A deficit of copper atoms additional to the thermal one was revealed and studied using the radial distributions of the ground state population. The physical processes governing the radial distributions of copper atoms in the ground state are discussed.

  1. An alternative electric-field spectrum for laser-driven atomic systems

    NASA Astrophysics Data System (ADS)

    Stokes, Adam; Beige, Almut

    2015-05-01

    We adopt an open systems perspective to calculate a novel frequency spectrum associated with the electric field generated by an atomic dipole moment undergoing resonant laser-driving. This spectrum has a similar triplet shape to the Mollow spectrum indicating that it contains a similar amount of information. However, while the Mollow triplet derives from the Glauber two-time correlation function, which represents the average energy-intensity of a superposition of waves taken at different times, our spectrum derives from a correlation function defined in terms of single-time expectation values of the electric source-field. Although the two spectra are derived from different physical signals and utilise different measures of correlation, they both appear to reflect the quantum-mechanical level-structure of the atomic source.

  2. Variation of the Fine-Structure Constant and Laser Cooling of Atomic Dysprosium

    E-print Network

    Leefer, N A; Budker, D; Ferrell, S J; Yashchuk, V V; Lapierre, A; Nguyen, A -T; Lamoreaux, S K; Torgerson, J R

    2008-01-01

    Radio-frequency electric-dipole transitions between nearly degenerate, opposite parity levels of atomic dysprosium (Dy) were monitored over an eight-month period to search for a variation in the fine-structure constant, $\\alpha$. The data provide a rate of fractional temporal variation of $\\alpha$ of $(-2.7\\pm2.6)\\times 10^{-15}$ yr$^{-1}$ or a value of $(-8.7 \\pm 6.6) \\times 10^{-6}$ for $k_\\alpha$, the variation coefficient for $\\alpha$ in a changing gravitational potential. All results indicate the absence of significant variation at the present level of sensitivity. We also present initial results on laser cooling of an atomic beam of dysprosium.

  3. 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.}

  4. Arcjet flow properties determined from laser-induced fluorescence of atomic nitrogen.

    PubMed

    Fletcher, D G

    1999-03-20

    Flow property measurements that were recently acquired in the Ames Research Center Aerodynamic Heating Facility arcjet using two-photon laser-induced fluorescence (LIF) of atomic nitrogen (N) are reported. The flow properties, which include velocity, translational temperature, and N concentration, were measured simultaneously over a range of facility operating conditions for N(2)-argon test gas flows in the 30-cm-diameter nozzle. A recent measurement of the two-photon excitation cross section for the 3p(4)D degrees <-- 2p(4)S degrees transition of atomic nitrogen is used to convert the relative nitrogen concentration measurements to absolute values, and a nitrogen flow reactor is used to provide a room-temperature, reference-wavelength calibration of the translational temperature and velocity measurements. When combined with information from facility measurements, an analysis of the flow properties obtained using two-photon LIF of N yields the total free-stream flow enthalpy. PMID:18305816

  5. 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 [National Key Laboratory of Vacuum and Cryogenics Technology and Physics, Lanzhou Institute of Physics, Lanzhou 730000 (China)

    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.

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

    SciTech Connect

    Shahbaz, Atif; Mueller, Carsten [Max-Planck-Institut fuer Kernphysik, Saupfercheckweg 1, D-69117 Heidelberg (Germany); Buervenich, Thomas J. [Frankfurt Institute for Advanced Studies, Johann Wolfgang Goethe University, Ruth-Moufang-Strasse 1, D-60438 Frankfurt am Main (Germany)

    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.

  7. Using Lasers and X-rays to Reveal the Motion of Atoms and Electrons

    SciTech Connect

    Bob Schoenlein

    2009-07-14

    July 7, 2009 Berkeley Lab summer lecture: 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

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

    E-print Network

    Neill Lambert; Franco Nori; Christian Flindt

    2015-05-29

    We predict a dynamical bistability in the photon emission from a solid-state single-atom laser comprised of a microwave cavity coupled to a voltage-biased double quantum dot. The switching rates of the bistability can be extracted from the average electrical current and the shot noise in the quantum dots. Using large-deviation techniques we demonstrate that the full counting statistics of emitted photons is captured by the universal shape of a tilted ellipse whose form can be controlled by modulating the electronic transport in the quantum dots. Our prediction is robust against moderate electronic decoherence and dephasing due to phonons and may be tested using current technology.

  9. Spectroscopic measurement of the vapour pressure of ice.

    PubMed

    Bielska, K; Havey, D K; Scace, G E; Lisak, D; Hodges, J T

    2012-06-13

    We present a laser absorption technique to measure the saturation vapour pressure of hexagonal ice. This method is referenced to the triple-point state of water and uses frequency-stabilized cavity ring-down spectroscopy to probe four rotation-vibration transitions of at wavenumbers near 7180?cm(-1). Laser measurements are made at the output of a temperature-regulated standard humidity generator, which contains ice. The dynamic range of the technique is extended by measuring the relative intensities of three weak/strong transition pairs at fixed ice temperature and humidity concentration. Our results agree with a widely used thermodynamically derived ice vapour pressure correlation over the temperature range 0C to -70C to within 0.35 per cent. PMID:22547230

  10. 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.

  11. Atomic layer-by-layer growth of oxide thin films by laser MBE

    NASA Astrophysics Data System (ADS)

    Lei, Qingyu; Liu, Guozhen; Golalikhani, Maryam; Chen, Ke; Shi, Suilin; Huang, Fuqiang; Farrar, Andrew; Tenne, Dmitri; Singh, Rakesh; Xi, Xiaoxing

    2014-03-01

    We have studied an atomic layer-by-layer thin film growth technique for complex oxide thin films and heterostructures. By using a laser-MBE system and monitoring the reflection high-energy electron diffraction (RHEED) intensity to control the flux for each atomic layer in-situ, we actively control the structure and stoichiometry down to the atomic layer level. In the growth of SrTiO3 from the separate SrO and TiO2 targets, or from metal Sr and oxide TiO2 target, we studied the phases of the specular and diffraction spot intensities as well as that of the Kikuchi lines. UV Raman spectroscopy was used to probe the symmetry breaking due to the cation off-stoichiometry. Similar stoichiometry control as shown by reactive MBE has been demonstrated. We also studied the target preparation of various oxides, including the highly reactive La2O3 and BaO. We have successfully applied this atomic layer-by-layer growth method to the deposition of LaAlO3 and LaNiO3 thin films and superlattices.

  12. CONTROL OF LASER RADIATION PARAMETERS: Tunable frequency-stabilised laser for studying the cooling dynamics of Rb atoms in a magnetooptical trap

    NASA Astrophysics Data System (ADS)

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

    2004-04-01

    A system is developed which allows one to stabilise the diode laser frequency at any point in the vicinity of the cyclic D2-line transition in Rb in the interval from +40 to -150 MHz and to switch the laser frequency within this interval for ~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.

  13. 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. [Department of Physics and Astronomy, Washington State University, Pullman, Washington 991642814 (United States)] [Department of Physics and Astronomy, Washington State University, Pullman, Washington 991642814 (United States); Boatner, L. A. [Metals and Ceramics Division, Oak Ridge National Laboratory, Oak Ridge, Tennessee 37831 (United States)] [Metals and Ceramics Division, Oak Ridge National Laboratory, Oak Ridge, Tennessee 37831 (United States)

    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.

  14. 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...

  15. Vapour Phase Activity of Imazalil

    Microsoft Academic Search

    Jef Van Gestel; Jan Van Cutsem; Denis Thienpont

    1981-01-01

    A series of in vitro experiments with imazalil is described. It is demonstrated that the compound has fungistatic, fungicidal and even sporocidal activity in the vapour phase against a wide variety of fungal species, e.g., dermatophytes, Candida albicans, and plant-pathogenic fungi. Possible practical applications are discussed.Copyright 1981 S. Karger AG, Basel

  16. Homogeneous nucleation and growthin iron-platinum vapour investigated by molecular dynamics simulation

    Microsoft Academic Search

    N. Lmmen; T. Kraska

    2007-01-01

    .Homogeneous nucleation and growth\\u000a from binary metal vapour is investigated by molecular dynamics simulation. It is focused here mainly on the iron-platinum\\u000a system with a mole fraction of 0.5. The simulations are started in the highly supersaturated vapour phase. Argon is added\\u000a as carrier gas removing the heat of condensation from the forming clusters. The embedded atom method is employed

  17. Angular distribution of atoms ejected by laser ablation of different metals

    SciTech Connect

    Konomi, I.; Motohiro, T. [Toyota Technological Institute, 2-12-1 Hisakata, Tempaku-ku, Nagoya 468-8511 (Japan); Toyota Central Research and Development Laboratories, Inc., 41-1 Yokomichi, Nagakute, Aichi 480-1192 (Japan); Asaoka, T. [Toyota Central Research and Development Laboratories, Inc., 41-1 Yokomichi, Nagakute, Aichi 480-1192 (Japan)

    2009-07-01

    Angular distributions of 13 different metals ejected by laser ablation using fourth harmonics (wavelength=266 nm) of neodymium doped yttrium aluminum garnet laser and a fluence close to near-threshold value (2.3 J/cm{sup 2}) have been investigated with a high angular resolution. The angular distribution which is characterized by the exponent n of cos{sup n} theta distribution showed very broad range of values between 3 and 24 for different metals. A simple relation that the exponent n is proportional to the square root of particle atomic weight as reported previously has not been observed. Instead, a general trend has been found that the metals with higher sublimation energy such as Ta and Zr show narrower angular distribution than those with lower sublimation energy such as Sn and In. While the sublimation energy of metals has a great influence on the angular distribution of ejected atoms, a simple consideration suggests that their thermal conductivity and specific heat have little effect on it.

  18. Controllable optical bistability in photonic-crystal one-atom laser

    SciTech Connect

    Guo Xiaoyong; Lue Shuchen [Heilongjiang Key Laboratory for Advanced Functional Material and Excited State Process, School of Physics and Electronic Engineering, Harbin Normal University, Harbin 150025 (China)

    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.

  19. Investigations on laser ablation microwave induced plasma atomic emission spectrometry using polymer samples

    NASA Astrophysics Data System (ADS)

    Leis, F.; Bauer, H. E.; Prodan, L.; Niemax, K.

    2001-01-01

    The potential of laser ablation-microwave induced plasma-atomic emission spectrometry (LA-MIP-AES) for the analysis of plastic materials has been investigated. A Nd/YAG laser, operated in its fundamental mode at 1064 nm, was used to ablate small amounts of various plastics. The sample atoms were transported and excited in a closely neighbored continuously running microwave induced plasma (MIP) operated in argon or helium at reduced pressure. A 0.5-m chelle spectrometer, equipped with an intensified charge coupled device (ICCD) as a detector was used for recording the spectra. The amount of ablated material was found to be strongly dependent on the matrix (10-190 ng/shot). Signals for some metals often used as additives in polymers (Al, Ca, Cu, Sb, Ti) and for the elements F, Cl, Br, J, and P in various polymers were recorded in the spectral range 250-840 nm. The estimated detection limits were found to be in the range 0.001-0.08% for metals and 0.05-0.7% for non-metals. Spectral lines of fluorine and iodine could only be measured in the helium MIP. For high concentrations of chlorine and carbon in the samples (polyvinylchloride), a memory effect was observed.

  20. 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

  1. CCMR: Atomic Scale Theory of Real-Time X-ray Signatures in Pulsed Laser Deposition

    NSDL National Science Digital Library

    Handford, Christina G.

    2005-08-17

    Pulsed laser deposition (PLD) uses timed laser pulses to blast a target surface causing a plume of material to be discharged from the target. The plume of material then collides with the substrate surface on which the material is being grown. One thing pulsed laser deposition is used for is growing thin films of complex oxide crystals. In an experiment by Aaron Fleet, et al., a smoothing mechanism is found to be present during PLD of SrTiO3. Via real time x-ray diffraction data from the G3 facility at CHESS, the smoothing mechanism is found to vary with the step density of the thin film. These findings are the inspiration for this theoretical research project designed to study these step phenomena on the atomic level. The project focuses on two possibilities for the experimentally observed trend. One is the possibility of a difference in behavior of the collisions when hitting near a step, as opposed to a flat surface, and two is the possibility that there is a difference in the x-ray signatures only due to the presence of steps on a relaxed surface. These two possibilities are studied and compared to determine if they are relevant to the smoothing mechanism.

  2. 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.

  3. Single-mode vertical-cavity surface emitting lasers for {sup 87}Rb-based chip-scale atomic clock

    SciTech Connect

    Derebezov, I. A., E-mail: derebezov@thermo.isp.nsc.ru; 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. [Russian Academy of Sciences, A.V. Rzhanov Institute of Semiconductor Physics, Siberian Branch (Russian Federation)

    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

  4. Photoelectron spectroscopy of laser-excited aligned Ca atoms in the region of the 3p excitation

    Microsoft Academic Search

    S. Baier; W. Fiedler; B. R. Muller; M. Schulze; P. Zimmermann; M. Meyer; M. Pahler; T. Prescher; E. von Raven; M. Richter; J. Ruder; B. Sonntag

    1992-01-01

    Pumping the resonance transition Ca 4s21S0 to 4s4p 1P1 at lambda =422.7 nm with the linear polarized light of a ring dye laser the subsequent excitation by the linear polarized VUV light of the synchrotron radiation source BESSY was used to investigate the photoionization process from laser-excited aligned Ca atoms. Using the dependence of the photoelectron signals on the polarization

  5. Pumping of atomic alkali lasers by photoexcitation of a resonance line blue satellite and alkali-rare gas excimer dissociation

    Microsoft Academic Search

    J. D. Readle; C. J. Wagner; J. T. Verdeyen; T. M. Spinka; D. L. Carroll; J. G. Eden

    2009-01-01

    Photoassociation of alkali-rare gas atomic collision pairs provides an alternative approach to optically pumping atomic alkali lasers. Lasing on the 6 2P1\\/2?6 2S1\\/2(D1) transition of Cs has been observed when the blue satellite of the 6 2P3\\/2?6 2S1\\/2(D2) transition, peaking at ?837 nm for mixtures of Cs vapor, Ar, and ethane, is pumped by a pulsed dye laser. For 50%

  6. High-coherence electron and ion bunches from laser-cooled atoms.

    PubMed

    Sparkes, Ben M; Thompson, Daniel J; McCulloch, Andrew J; Murphy, Dene; Speirs, Rory W; Torrance, Joshua S J; Scholten, Robert E

    2014-08-01

    Cold atom electron and ion sources produce electron bunches and ion beams by photoionization of laser-cooled atoms. They offer high coherence and the potential for high brightness, with applications including ultra-fast electron-diffractive imaging of dynamic processes at the nanoscale. The effective brightness of electron sources has been limited by nonlinear divergence caused by repulsive interactions between the electrons, known as the Coulomb explosion. It has been shown that electron bunches with ellipsoidal shape and uniform density distribution have linear internal Coulomb fields, such that the Coulomb explosion can be reversed using conventional optics. Our source can create bunches shaped in three dimensions and hence in principle achieve the transverse spatial coherence and brightness needed for picosecond-diffractive imaging with nanometer resolution. Here we present results showing how the shaping capability can be used to measure the spatial coherence properties of the cold electron source. We also investigate space-charge effects with ions and generate electron bunches with durations of a few hundred picoseconds. Future development of the cold atom electron and ion source will increase the bunch charge and charge density, demonstrate reversal of Coulomb explosion, and ultimately, ultra-fast coherent electron-diffractive imaging. PMID:24758916

  7. Molecular dynamics investigation of homogeneous nucleation and cluster growth of platinum clusters from supersaturated vapour

    Microsoft Academic Search

    N. Lmmen; T. Kraska

    2005-01-01

    The formation of platinum nanoparticles from a supersaturated vapour phase is investigated by molecular dynamics simulations. Argon is added as carrier gas, removing the condensation heat from the nucleating system. The interactions between the platinum atoms are modelled by the multi-body embedded atom method. The nucleation rates in highly supersaturated systems are estimated as well as properties of the critical

  8. 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 spectrometry. Adding the C6H5Br chromophore to the Ar/O2 gas mixture also enhanced the metal and oxide ion, laser ablation has been used to provide transition metal atoms for reactions with small molecules

  9. The space-time kinetics of the population of the copper atom ground state in a copper-vapor laser

    NASA Astrophysics Data System (ADS)

    Isaev, A. A.; Mikhkel'Soo, V. T.; Petrash, G. G.; Peet, V. E.; Ponomarev, I. V.

    1989-06-01

    A technique for measuring the population of the copper atom ground state in the medium of a self-heated copper-vapor laser is developed. The pulsed dye laser was used to sound the active medium (the temporal resolution was 5 ns and the spatial resolution was 2 mm). The kinetics of the ground state was studied in the excitation pulse and in the interpulse time interval over the whole temperature range of the stimulated emission (1360-1650 C) from a commercially produced laser.

  10. 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 [State Key Laboratory of Quantum Optics and Quantum Optics Devices, Laser Spectroscopy Laboratory, Shanxi University, Taiyuan 030006 (China)

    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.

  11. Breakthrough: X-ray Laser Captures Atoms and Molecules in Action

    SciTech Connect

    Bergmann, Uwe

    2012-04-26

    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.

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

    SciTech Connect

    Coons, R. W.; Harilal, S. S.; Campos, D.; Hassanein, A. [School of Nuclear Engineering and Center for Materials Under Extreme Environment, Purdue University, West Lafayette, Indiana 47907 (United States)

    2010-09-15

    Tin and lithium plasmas emit efficiently in the in-band region (13.5 nm with 2% bandwidth) necessary for extreme ultraviolet (EUV) lithography. We have made a detailed comparison of the atomic and ionic debris, as well as the emission features of Sn and Li plasmas under identical experimental conditions. Planar slabs of pure Sn and Li were irradiated with 1064 nm, 9 ns neodymium-doped yttrium aluminum garnet laser pulses for producing plasmas. A suite of diagnostics were used to analyze the emission and debris features, including optical emission spectroscopy (OES), a Faraday cup, an EUV pinhole camera, the absolute measurement of EUV conversion efficiency (CE), etc. Our results show that Sn plasmas provide a CE nearly twice that of Li. However, the kinetic energies of Sn ions are considerably higher, though with a lower flux. OES studies have showed that the kinetic energies of neutral species are substantially lower compared to that of the charged particle species.

  13. 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.

  14. Strong influence of configuration interactions on the orientation and alignment dichroism in the 3p photoelectron spectra of free laser-polarized Fe atoms

    Microsoft Academic Search

    R. Mller; J. Schulz; Ph. Wernet; K. Godehusen; M. Martins; B. Sonntag; P. Zimmermann

    2007-01-01

    The 3p photoelectron spectra of oriented and aligned free Fe atoms are presented. The atomic polarization was achieved by optical pumping. For this purpose single-mode ultraviolet continuous wave laser radiation was produced by second harmonic generation in an external ring resonator. The ground state Fe 3d64s2 D45 was oriented by circularly polarized laser radiation and aligned by linearly polarized laser

  15. Absolute Optical Frequency Measurements of the Cesium D1 Transitions in a Thermal Atomic Beam using a Femtosecond Laser Frequency Comb

    Microsoft Academic Search

    Carol E. Tanner; Scott Diddams

    2005-01-01

    High resolution spectroscopy of the cesium D1 line is performed in a thermal atomic beam using a narrow linewidth CW diode laser offset locked to a single tooth of a femtosecond laser frequency comb. A computer controlled RF synthesizer changes the offset frequency, thus scanning the optical frequency of the probe laser. A photodiode collects the fluorescence and the signal

  16. Investigations of ion-irradiated uranium dioxide nuclear fuel with laser-assisted atom probe tomography

    NASA Astrophysics Data System (ADS)

    Valderrama, Billy

    Performance in commercial light water reactors is dictated by the ability of its fuel material, uranium dioxide (UO2), to transport heat generated during the fission process. It is widely known that the service lifetime is limited by irradiation-induced microstructural changes that degrade the thermal performance of UO2. Studying the role of complex, often interacting mechanisms that occur during the early stages of microstructural evolution presents a challenge. Phenomena of particular interest are the segregation of fission products to form bubbles and their resultant effect on grain boundary (GB) mobility, and the effect of irradiation on fuel stoichiometry. Each mechanism has a profound consequence on fuel thermal conductivity. Several advanced analytical techniques, such as transmission electron microscopy, x-ray diffraction, x-ray photoelectron spectroscopy, etc. have been used to study these mechanisms. However, they each have limitations and cannot individually provide the necessary information for deeper understanding. One technique that has been under utilized is atom probe tomography (APT), which has a unique ability to spatially resolve small-scale chemical variations. APT uses the principle of field ionization to evaporate surface ions for chemical analysis. For low electrical conductivity systems, a pulsed laser is used to thermally assist in the evaporation process. One factor complicating the analysis is that laser-material interactions are poorly understood for oxide materials and literature using this technique with UO2 is lacking. Therefore, an initial systematic study to identify the optimal conditions for the analysis of UO2 using laser-assisted APT was conducted. A comparative study on the evaporation behavior between CeO2 and UO2 was followed. CeO2 was chosen due to its technological relevancy and availability of comparative studies with laser-assisted APT. Dissimilar evaporation behavior between these materials was identified and attributed to differences in laser absorption, oxide stability, and thermal conductivity between the two materials. After the conditions were identified, APT was utilized to study the role of temperature and GB structure on the segregation of Kr. Results indicate that high angle GBs contain more Kr relative to low angle GBs. The methodology presented can be applied to investigate small-scale chemical changes in other oxide materials.

  17. Exterior complex scaling method in TDDFT: HHG of Ar atoms in intense laser fields

    NASA Astrophysics Data System (ADS)

    Sosnova, K. E.; Telnov, D. A.; Rozenbaum, E. B.; Chu, S. I.

    2014-04-01

    The exterior complex scaling (ECS) method is applied in the framework of time-dependent density-functional theory (TDDFT) to study high-order harmonic generation (HHG) of multielectron atoms in intense laser fields. With the help of ECS, correct outgoing-wave boundary conditions can be imposed on the wave functions at large distances. In our implementation, ECS is combined with the time-dependent generalized pseudospectral method for accurate and efficient solution of the time-dependent Kohn-Sham equations. We make use of LB94 exchange-correlation potential which appears quite accurate in calculations of unperturbed electronic structure of Ar. Calculations of HHG are performed for the laser fields with the wavelength of 800 nm and several peak intensities. The HHG spectrum exhibits an intensity-independent minimum corresponding to the photon energy of about 51 eV which is closely related to the Cooper minimum in the photoionization cross section of Ar. We found that HHG spectra calculated with the frozen-core potential (not including dynamic response of the electron density) differ significantly from those obtained by TDDFT.

  18. Self-Compression of High Power Laser Pulses in an Atomic Gas

    NASA Astrophysics Data System (ADS)

    Wagner, Nicholas; Christov, Ivan; Murnane, Margaret; Kapteyn, Henry; Gibson, Emily

    2004-05-01

    We observe a new form of pulse compression that operates at ionizing laser intensities when an ultrashort pulse propagates through an atomic gas. Normally, when a laser pulse propagates through a gas-filled waveguide at intensities below the ionizing threshold, nonlinear effects such a self-phase modulation (SPM) broaden the spectrum of the pulse. However, these nonlinear effects do not change the pulse envelope - the pulse emerges from the fiber with the same pulse duration but with a broader spectrum. The pulse can then be compressed externally. In this work, we observe pulse compression of 28fs pulses down to 14fs, without the need for post-compression. The waveguide is filled with low pressure argon gas (2-9 torr). We use amplified 800nm pulses at an intensity of 10^15 W/cm^2, which doubly ionize Ar. The input and output pulses were measured using SHG FROG. This new compression scheme cannot be explained by 1-dimensional nonlinear propagation, but may be due to a spatial-temporal coupling. This compression technique can be used to advantage in experiments performed in waveguides, such as HHG or exciting molecular vibrations.

  19. 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 [Samara Branch of the P.N. Lebedev Physics Institute, Russian Academy of Sciences, Samara (Russian Federation)

    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)

  20. Pulsed erbium laser ablation of hard dental tissue: the effects of atomized water spray versus water surface film

    NASA Astrophysics Data System (ADS)

    Freiberg, Robert J.; Cozean, Colette D.

    2002-06-01

    It has been established that the ability of erbium lasers to ablate hard dental tissue is due primarily to the laser- initiated subsurface expansion of the interstitial water trapped within the enamel and that by maintaining a thin film of water on the surface of the tooth, the efficiency of the laser ablation is enhanced. It has recently been suggested that a more aggressive ablative mechanism, designated as a hydrokinetic effect, occurs when atomized water droplets, introduced between the erbium laser and the surface of the tooth, are accelerated in the laser's field and impact the tooth's surface. It is the objective of this study to determine if the proposed hydrokinetic effect exists and to establish its contribution to the dental hard tissue ablation process. Two commercially available dental laser systems were employed in the hard tissue ablation studies. One system employed a water irrigation system in which the water was applied directly to the tooth, forming a thin film of water on the tooth's surface. The other system employed pressurized air and water to create an atomized mist of water droplets between the laser hand piece and the tooth. The ablative properties of the two lasers were studied upon hard inorganic materials, which were void of any water content, as well as dental enamel, which contained interstitial water within its crystalline structure. In each case the erbium laser beam was moved across the surface of the target material at a constant velocity. When exposing material void of any water content, no ablation of the surfaces was observed with either laser system. In contrast, when the irrigated dental enamel was exposed to the laser radiation, a linear groove was formed in the enamel surface. The volume of ablated dental tissue associated with each irrigation method was measured and plotted as a function of the energy within the laser pulse. Both dental laser systems exhibited similar enamel ablation rates and comparable ablated surface characteristics. The results of the study suggest that, although the manner in which the water irrigation was introduced differed, the mechanism by which the enamel was removed appeared basically the same for both dental laser systems, namely rapid subsurface expansion of the interstitially trapped water. It is the conclusion of this study that if the proposed hydrokinetic effect exists, it is not effective on hard materials, which are void of water, and it does not contribute in any significant degree in the ablation of dental enamel.

  1. Proposed method for laser spectroscopy of pionic helium atoms to determine the charged-pion mass

    E-print Network

    Hori, Masaki; Korobov, Vladimir I

    2014-01-01

    Metastable pionic helium ($\\pi{\\rm He}^+$) is a three-body atom composed of a helium nucleus, an electron occupying the $1s$ ground state, and a negatively charged pion $\\pi^-$ in a Rydberg state with principal- and orbital angular momentum quantum numbers of $n\\sim \\ell+1\\sim 16$. We calculate the spin-independent energies of the $\\pi{\\rm ^3He}^+$ and $\\pi{\\rm ^4He}^+$ isotopes in the region $n=15$--19. These include relativistic and quantum electrodynamics corrections of orders $R_{\\infty}\\alpha^2$ and $R_{\\infty}\\alpha^3$ in atomic units, where $R_{\\infty}$ and $\\alpha$ denote the Rydberg and fine structure constants. The fine-structure splitting due to the coupling between the electron spin and the orbital angular momentum of the $\\pi^-$, and the radiative and Auger decay rates of the states are also calculated. Some states $(n,\\ell)=(16,15)$ and $(17,16)$ retain nanosecond-scale lifetimes against $\\pi^-$ absorption into the helium nucleus. We propose to use laser pulses to induce $\\pi^-$ transitions from...

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

    NASA Astrophysics Data System (ADS)

    Domnguez-Gutirrez, F. Javier; Cabrera-Trujillo, R.

    2013-09-01

    We solve the time-dependent Schrdinger equation within a finite-differences approach and the propagation Crank-Nicolson method to calculate the n = 2, 3, and total electron capture cross section of He2+ colliding with atomic H in the energy collision range 0.25-35 keV/amu. We use a laser pulse of 3, 2, and 1 fs at FHWM, wavelength of 800 nm and intensity 3.15 1012 W/cm2. We demonstrate that the laser assistance in the collision increases an order of magnitude the electron charge capture in the 0.25-2 keV/amu energy collision range. We compare our numerical results with those obtained experimentally for the laser-free case to asses the validity of our method. Also, we study the effect of the laser pulse in the excitation cross-section for n =2 states of the hydrogen atom and the dependence of the charge exchange as function of the FWHM of the laser pulse. We solve the time-dependent Schrdinger equation within a finite-differences approach and the propagation Crank-Nicolson method to calculate the n = 2, 3, and total electron capture cross section of He2+ colliding with atomic H in the energy collision range 0.25-35 keV/amu. We use a laser pulse of 3, 2, and 1 fs at FHWM, wavelength of 800 nm and intensity 3.15 1012 W/cm2. We demonstrate that the laser assistance in the collision increases an order of magnitude the electron charge capture in the 0.25-2 keV/amu energy collision range. We compare our numerical results with those obtained experimentally for the laser-free case to asses the validity of our method. Also, we study the effect of the laser pulse in the excitation cross-section for n =2 states of the hydrogen atom and the dependence of the charge exchange as function of the FWHM of the laser pulse. We acknowledge support from CONACyT and PAPIIT IN-101-611.

  3. An all-optical locking of a semiconductor laser to the atomic resonance line with 1 MHz accuracy.

    PubMed

    Zhang, Xiaogang; Tao, Zhiming; Zhu, Chuanwen; Hong, Yelong; Zhuang, Wei; Chen, Jingbiao

    2013-11-18

    An all-optical locking technique without extra electrical feedback control system for a semiconductor laser has been used in stabilizing the laser frequency to a hyperfine crossover transition of 87Rb 5(2)S(1/2), F = 2 ? 5(2)P(3/2), F' = 2, 3 with 1 MHz level accuracy. The optical feedback signal is generated from the narrow-band Faraday anomalous dispersion optical filter (FADOF) with nonlinear saturation effect. The peak transmission of the narrow-band FADOF corresponding to 5(2)S(1/2), F = 2 ? 5(2)P(3/2), F' = 2, 3 crossover transition is 18.6 %. The bandwidth is as wide as 38.9 MHz as the laser frequency changes. After locking, the laser frequency fluctuation is reduced to 1.7 MHz. The all-optical laser locking technique can be improved to much higher accuracy with increased external cavity length. The laser we have realized can provide light exactly resonant with atomic transitions used for other atom-light interaction experiments. PMID:24514314

  4. 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 9.6dB 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 2.710-9 and a reproducibility of 1.210-8, with a DNR of detected signals of around 81dB. It has been shown that PSDAVLL might be successfully used as a method for spectra-stable laser sources. PMID:25967193

  5. Time-resolved spectroscopic study of high-pressure self-sustained discharge-pumped atomic xenon lasers

    SciTech Connect

    Komatsu, K.; Matsui, E,; Kannari, F.; Obara, M. (Dept. of Electrical Engineering, Faculty of Science and Technology, Keio Univ., Kohoku-ku, Yokohama 223 (JP))

    1991-01-01

    To explore the lasting kinetics of UV-preionized, self-sustained discharge-pumped atomic xenon (5{ital d} {r arrow} 6{ital p}) lasers, the time-resolved spectroscopy of the laser output from the multiline laser resonator is reported. The diluents used are Ar and He. With the Ar diluent, the 1.73 {mu}m line occupied more than 90% of the total laser output energy, which can therefore characterize the total output performance. Increasing Xe concentration shortened the 1.73 {mu}m laser pulse duration and decreased the total (multiline) laser output energy, because increased Xe metastable state population contributes to the increase of the 6{ital p} state population (lower laser level) by electron-impact excitation and radiation trapping during discharge pumping. High-excitation-rate pumping resulted in the decrease of the laser output power of 1.73 and 2.63 {mu}m lines. Increasing the total gas-pressure leads to the high-efficiency operation due to the modest-excitation-rate pumping at high pressures. When the Ar diluent is partially replaced by the He diluent, the spectral line distribution is also discussed in terms of the relevant kinetic process.

  6. Scanning Tunneling Microscopy and Atomic Force Microscopy Studies of Laser Irradiation of Amorphous WO3 Thin Films

    NASA Astrophysics Data System (ADS)

    Qiu, Hong; Lu, Yong-Feng

    2000-10-01

    The effect of irradiating amorphous WO3-x thin films by an excimer laser and a Nd-YAG (yttrium-aluminum-garnet) laser on the evolution of electronic states was investigated by scanning tunneling spectroscopy (STS) and X-ray photoelectron spectroscopy (XPS). The original films prepared by pulsed-laser deposition (PLD) were first irradiated by a KrF excimer laser at 248 nm in air. The surface was reduced to a quasi-metallic one with oxygen deficiency and the number of W 5d occupied states was increased. A number of surface states appeared on the films. When the films were subsequently irradiated by the Nd-YAG laser at 1.06 ?m in air, the number of W 5d occupied states was reduced due to oxygen restoration. The number of surface states was also greatly reduced. A water layer on the surface, which played a key role in photolysis, was monitored by STS by trapping charges in the Schottky barrier. Atomic force microscopy (AFM) and scanning tunneling microscopy (STM) images of the films at three states: original, surface reduced, and surface restored, were compared in terms of average profile roughness and height. Thermal effects (thermochromism) dominated in the Nd-YAG laser irradiation, resulting in a maximum average roughness in the AFM images, whereas photon effects (photochromism) dominated in excimer laser irradiation, which led to the highest conductance. Slight nanocrystallization occurred in the laser-irradiated films.

  7. Applying velocity constraints to the laser spectroscopy of deuterium-atom and chlorine-atom photodissociation products

    NASA Astrophysics Data System (ADS)

    Johnson, Michael W.

    2005-07-01

    The nuclear hyperfine population distributions of the deuterium atom produced in the 266 nm photolysis of DI were measured with a technique that applies spatial filtering of the nascent recoiling photoproducts to yield a reduced Doppler profile. A novel method of resonance detection for Cl atom photoproducts is also presented along with time-of-flight measurements of chlorine atoms as photoproducts from the dissociation of Cl2, thiophosgene, and phosgene. The resonance detection method permits high-resolution frequency scanning of the hyperfine structure of the chlorine atom. The results of these measurements are also presented.

  8. Thermocamera studies of gases and vapours.

    PubMed Central

    Carlsson, P; Ljungqvist, B; Neikter, K

    1982-01-01

    Most gases and vapours with a bipolar molecular structure absorb infrared energy. If such a gas is interposed between an object emitting infrared radiation and a thermocamera the gas will absorb some of the infrared radiation and thus cast a shadow on the thermocamera picture. In this assay it is possible to visualise the gas. This method had been used to study pollution with anaesthetic gases and vapours in operating theatres. The vapours of other chemicals used in hospitals and other places of work also have been studied. The method permits the study of dispersion and flow patterns of polluting gases and vapours during work. Images PMID:7093159

  9. Self-injection and acceleration of electrons during ionization of gas atoms by a short laser pulse

    SciTech Connect

    Singh, K.P. [Computational Plasma Dynamics Laboratory, Kettering University, Flint, Michigan 48504 (United States)

    2006-04-15

    Using a relativistic three-dimensional single-particle code, acceleration of electrons created during the ionization of nitrogen and oxygen gas atoms by a laser pulse has been studied. Barrier suppression ionization model has been used to calculate ionization time of the bound electrons. The energy gained by the electrons peaks for an optimum value of laser spot size. The electrons created near the tail do not gain sufficient energy for a long duration laser pulse. The electrons created at the tail of pulse escape before fully interacting with the trailing part of the pulse for a short duration laser pulse, which causes electrons to retain sufficient energy. If a suitable frequency chirp is introduced then energy of the electrons created at the tail of the pulse further increases.

  10. 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...

  11. 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.

  12. Atomic force microscopy and transmission electron microscopy analyses of low-temperature laser welding of the cornea.

    PubMed

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

    2009-07-01

    Low-temperature laser welding of the cornea is a technique used to facilitate the closure of corneal cuts. The procedure consists of staining the wound with a chromophore (indocyanine green), followed by continuous wave irradiation with an 810 nm diode laser operated at low power densities (12-16 W/cm(2)), which induces local heating in the 55-65 degrees C range. In this study, we aimed to investigate the ultrastructural modifications in the extracellular matrix following laser welding of corneal wounds by means of atomic force microscopy and transmission electron microscopy. The results evidenced marked disorganization of the normal fibrillar assembly, although collagen appeared not to be denatured under the operating conditions we employed. The mechanism of low-temperature laser welding may be related to some structural modifications of the nonfibrillar extracellular components of the corneal stroma. PMID:18982404

  13. 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.

  14. Growth of centimeter-scale atomically thin MoS2 films by pulsed laser deposition

    NASA Astrophysics Data System (ADS)

    Siegel, Gene; Venkata Subbaiah, Y. P.; Prestgard, Megan C.; Tiwari, Ashutosh

    2015-05-01

    We are reporting the growth of single layer and few-layer MoS2 films on single crystal sapphire substrates using a pulsed-laser deposition technique. A pulsed KrF excimer laser (wavelength: 248 nm; pulse width: 25 ns) was used to ablate a polycrystalline MoS2 target. The material thus ablated was deposited on a single crystal sapphire (0001) substrate kept at 700 C in an ambient vacuum of 10-6 Torr. Detailed characterization of the films was performed using atomic force microscopy (AFM), Raman spectroscopy, UV-Vis spectroscopy, and photoluminescence (PL) measurements. The ablation of the MoS2 target by 50 laser pulses (energy density: 1.5 J/cm2) was found to result in the formation of a monolayer of MoS2 as shown by AFM results. In the Raman spectrum, A1g and E12g peaks were observed at 404.6 cm-1 and 384.5 cm-1 with a spacing of 20.1 cm-1, confirming the monolayer thickness of the film. The UV-Vis absorption spectrum exhibited two exciton absorption bands at 672 nm (1.85 eV) and 615 nm (2.02 eV), with an energy split of 0.17 eV, which is in excellent agreement with the theoretically predicted value of 0.15 eV. The monolayer MoS2 exhibited a PL peak at 1.85 eV confirming the direct nature of the band-gap. By varying the number of laser pulses, bi-layer, tri-layer, and few-layer MoS2 films were prepared. It was found that as the number of monolayers (n) in the MoS2 films increases, the spacing between the A1g and E12g Raman peaks (?f) increases following an empirical relation, ? f = 26 . 45 - /15 . 42 1 + 1 . 44 n 0 . 9 cm - 1 .

  15. 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 argonhelium (ArHe) 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).

  16. Lasers '81

    SciTech Connect

    Collins, C.B.

    1982-01-01

    Progress in lasers is discussed. The subjects addressed include: excimer lasers, surface spectroscopy, modern laser spectroscopy, free electron lasers, cavities and propagation, lasers in medicine, X-ray and gamma ray lasers, laser spectroscopy of small molecules and clusters, optical bistability, excitons, nonlinear optics in the X-ray and gamma ray regions, collective atomic phenomena, tunable IR lasers, far IR/submillimeter lasers, and laser-assisted collisions. Also treated are: special applications, multiphoton processes in atoms and small molecules, nuclear pumped lasers, material processing and applications, polarization, high energy lasers, laser chemistry, IR molecular lasers, laser applications of collision and dissociation phenomena, solid state laser materials, phase conjugation, advances in laser technology for fusion, metal vapor lasers, picosecond phenomena, laser ranging and geodesy, and laser photochemistry of complex molecules.

  17. Thermal calcium atom interferometer with a phase resolution of a few milliradians based on a narrow-linewidth diode laser

    SciTech Connect

    Akatsuka, Tomoya; Mori, Yoshihiro; Sone, Nobuhiko; Ohtake, Yurie; Machiya, Mamoru; Morinaga, Atsuo [Faculty of Science and Technology, Tokyo University of Science, Noda-shi, Chiba 278-8510 (Japan)

    2011-08-15

    A symmetrical atom interferometer with a thermal calcium atom beam has been developed using a narrow linewidth diode laser stabilized to the resonance of a high-finesse cavity. The linewidth of the diode laser was estimated to be less than 1 Hz relative to the cavity resonance in noise measurement over the range of 100 Hz to 1 MHz, and the phase instability of the interference fringes obtained from the Allan deviation was improved to 2 mrad at an integration time of 300 s. Using this atom interferometer, the ac Stark phase shift between the {sup 1}S{sub 0} and {sup 3}P{sub 1} states of a Ca atom was measured as a function of a laser power near the resonance of the {sup 1}S{sub 0}-{sup 1} P{sub 1} transition at a wavelength of 423 nm. The decay rate of the {sup 1}P{sub 1} state was determined to be {gamma}=1.91(33)x10{sup 8} s{sup -1}.

  18. Reactive quenching of two-photon excited xenon atoms by Cl/sub 2/. [Xenon chloride laser

    SciTech Connect

    Bruce, M.R.; Layne, W.B.; Meyer, E.; Keto, J.W.

    1987-01-01

    Total binary and tertiary quench rates have been measured for the reaction Xe (5p/sup 5/6p) + Cl/sub 2/ at thermal temperatures. Xenon atoms are excited by state-selective, two-photon absorption with a uv laser. The time dependent fluorescence from the excited atom in the IR and from XeCl* (B) product near 308 nm have been measured with subnanosecond time resolution. The decay rates are measured as a function of Cl/sub 2/ pressure to 20 Torr and Xe pressure to 400 Torr. The measured reaction rates (k/sub 2/ approx. 10/sup -9/ cm/sup 3/sec/sup -1/) are consistent with a harpoon model described in a separate paper. We also measure large termolecular reaction rates for collisions with xenon atoms (k/sub 3/ approx. 10/sup -28/ cm/sup 6/sec/sup -1/). Total product fluorescence has been examined using a gated optical multichannel analyzer. We measure unit branching fractions for high vibrational levels of XeCl* (B) with very little C state fluorescence observed. The measured termolecular rates suggest similar processes will dominate at the high buffer-gas pressures used in XeCl lasers. The effect of these large reactive cross sections for neutral xenon atoms on models of the XeCl laser will be discussed.

  19. Two-step laser excitation and field-ionization of krypton and xenon atoms in collinear fast-beam laser spectroscopy

    Microsoft Academic Search

    Jens Lassen

    2000-01-01

    In the context of ultra-trace detection and spectroscopy of trace amounts of the noble gases krypton and xenon, a collinear fast-beam laser-spectroscopy method was developed. In both fundamental research of short-lived isotopes, as well as in practical applications the task lies in devising a method that efficiently uses the minute sample sizes (in general less than 1013 atoms) with a

  20. High-resolution multiphoton laser-induced fluorescence spectroscopy of zinc atoms ejected from laser-irradiated ZnS crystals

    Microsoft Academic Search

    H. F. Arlinghaus; W. F. Calaway; C. E. Young; M. J. Pellin; D. M. Gruen; L. L. Chase

    1989-01-01

    Time-of-flight (TOF) measurements employing high-resolution multiphoton laser-induced fluorescence spectroscopy (LFS) have been used as a probe to determine the yield and velocity distributions of Zn atoms ejected from a ZnS single crystal under irradiation by 308-nm photons. For fluences between 20 and 80 mJ\\/cm² (irradiated area 2 mm²), the velocity distributions could be fitted by Maxwell--Boltzmann distributions where the characteristic

  1. High-resolution multiphoton laser-induced fluorescence spectroscopy of zinc atoms ejected from laser-irradiated ZnS crystals

    Microsoft Academic Search

    H. F. Arlinghaus; W. F. Calaway; C. E. Young; M. J. Pellin; D. M. Gruen; L. L. Chase

    1989-01-01

    Time-of-flight (TOF) measurements employing high-resolution multiphoton laser-induced fluorescence spectroscopy (LFS) have been used as a probe to determine the yield and velocity distributions of Zn atoms ejected from a ZnS single crystal under irradiation by 308-nm photons. For fluences between 20 and 80 mJ\\/cm2 (irradiated area 2 mm2), the velocity distributions could be fitted by MaxwellBoltzmann distributions where the characteristic

  2. 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. [Toyota Technological Institute, 2-12-1 Hisakata, Tempaku-ku, Nagoya 468-8511, Japan and Toyota Central Research and Development Laboratories, Inc., 41-1 Yokomichi, Nagakute, Aichi 480-1192 (Japan); Toyota Central Research and Development Laboratories, Inc., 41-1 Yokomichi, Nagakute, Aichi 480-1192 (Japan); Institute of Laser Engineering, Osaka University, 2-6 Yamada-oka, Suita, Osaka 565-0871 (Japan)

    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}.

  3. A sensitive and accurate atomic magnetometer based on free spin precession

    NASA Astrophysics Data System (ADS)

    Gruji?, Zoran D.; Koss, Peter A.; Bison, Georg; Weis, Antoine

    2015-05-01

    We present a laser-based atomic magnetometer that allows inferring the modulus of a magnetic field from the free Larmor precession of spin-oriented Cs vapour atoms. The detection of free spin precession (FSP) is not subject to systematic readout errors that occur in phase feedback-controlled magnetometers in which the spin precession is actively driven by an oscillating field or a modulation of light parameters, such as frequency, amplitude, or polarization. We demonstrate that an FSP-magnetometer can achieve a ~200 fT/ ?Hz sensitivity ( <100 fT/ ?Hz in the shotnoise limit) and an absolute accuracy at the same level.

  4. 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)

  5. 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.

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

    NASA Astrophysics Data System (ADS)

    Marcal, V.; Durry, G.; Longo, K.; Freitas, S.; Rivire, 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.

  7. films deposited by chemical vapour deposition

    NASA Astrophysics Data System (ADS)

    Asafa, T. B.; Witvrouw, A.; Morcos, B. S.; Vanstreels, K.; Said, S. A. M.

    2014-08-01

    A few properties of polycrystalline silicon germanium (poly-Si1- x Ge x ) films can be tailored by modulating the germanium incorporation. In this paper, the structural, mechanical and electrical properties of heavily doped ultrathin (~100 nm) poly-Si1- x Ge x films (0.84 ? x ? 0.88) fabricated by low-pressure chemical vapour deposition were investigated. For a boron concentration of ~2.2 1021 atoms/cm3, a slight increase of germanium fraction significantly enhances the deposition rate, crystallinity and Hall mobility while having negligible influence on the Young's modulus and hardness. The grain size increases from ~6 to ~12 nm while the grain structure becomes more columnar. In addition, the resistivity decreases from 7.4 to 1.1 m ? cm with a corresponding increase in the Hall mobility from ~0.9 to ~4.2 cm2 V-1 s-1. However, the Young's modulus (~101 GPa) and hardness (~8.8 GPa) are virtually unaffected within the range of germanium fraction explored. In practice, poly-SiGe layer having low resistivity, high modulus, high mobility and low surface roughness can be successfully applied for resonators, biosensors and nanoswitches among others.

  8. Strong influence of configuration interactions on the orientation and alignment dichroism in the 3p photoelectron spectra of free laser-polarized Fe atoms

    NASA Astrophysics Data System (ADS)

    Mller, R.; Schulz, J.; Wernet, Ph.; Godehusen, K.; Martins, M.; Sonntag, B.; Zimmermann, P.

    2007-01-01

    The 3p photoelectron spectra of oriented and aligned free Fe atoms are presented. The atomic polarization was achieved by optical pumping. For this purpose single-mode ultraviolet continuous wave laser radiation was produced by second harmonic generation in an external ring resonator. The ground state Fe 3d64s2 D45 was oriented by circularly polarized laser radiation and aligned by linearly polarized laser radiation. Switching from right handed to left handed circularly polarized laser radiation or by changing the polarization angle of the linearly polarized laser radiation by 90 allowed for the measurement of the orientation or the alignment dichroism in the Fe 3p photoelectron spectra excited by linearly polarized synchrotron radiation. The spectra are compared to the predictions of the single configuration LS -coupling model and the results of single and multiconfiguration calculations. Strong configuration interactions in the final core-hole states manifest themselves in marked deviations from the characteristic patterns. The comparison of the spectra of the free Fe atoms with spectra of thin magnetized Fe films reveals similarities but also marked differences between the dichroism curves of free and bound Fe atoms. The common atomic origin of the dichroism of free and bound Fe atoms is discussed; changes in the intra-atomic electron interactions as well as changes in valence electronic configuration when going from free to bound Fe atoms are addressed.

  9. Assessment of bacterial resistance to organic solvents using a combined confocal laser scanning and atomic force microscopy (CLSM/AFM).

    PubMed

    Kuyukina, Maria S; Ivshina, Irena B; Korshunova, Irina O; Rubtsova, Ekaterina V

    2014-12-01

    Using combined confocal laser scanning and atomic force microscopy (CLSM/AFM), bacterial viability under organic solvent stress was assessed at single cell level. Solvent-exposed bacteria stained with the LIVE/DEAD BacLight fluoresced green or red, allowing viable and dead cell discrimination. However, with toluene, butanol and acetonitrile, dually fluorescent cells appeared having compromised cell membranes. Changes in size, surface/volume ratio and roughness were revealed as possible resistance mechanisms. PMID:25193441

  10. Atom-Probe Field Ion Microscopy Investigation of CMSX-4 Ni-Base Superalloy Laser Beam Welds

    Microsoft Academic Search

    Babu

    1997-01-01

    CMSX-4 superalloy laser beam welds were investigated by transmission electron microscopy and atom probe field-ion microscopy (APFIM). The weld microstructure consisted of fine (10- to 50-nm) irregularly shaped γ' precipitates (0.65 to 0.75 volume fraction) within the γ matrix. APFIM compositions of the γ and γ' phases were found to be different from those in the base metal. Concentration profiles

  11. Laser-induced fluorescence measurements and kinetic analysis of Si atom formation in a rotating disk chemical vapor deposition reactor

    Microsoft Academic Search

    Pauline Ho; Michael E. Coltrin; William G. Breiland

    1994-01-01

    An extensive set of laser-induced fluorescence (LIF) measurements of Si atoms during the chemical vapor deposition (CVD) of silicon from silane and disilane in a research rotating disk reactor are presented. The experimental results are compared in detail with predictions from a numerical model of CVD from silane and disilane that treats the fluid flow coupled to gas-phase and gas-surface

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

    NASA Astrophysics Data System (ADS)

    Kanick, 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.

  13. Attosecond XUV absorption spectroscopy of doubly excited states in helium atoms dressed by a time-delayed femtosecond infrared laser

    NASA Astrophysics Data System (ADS)

    Yang, Z. Q.; Ye, D. F.; Ding, Thomas; Pfeifer, Thomas; Fu, L. B.

    2015-01-01

    In the present paper, we investigate the time-resolved transient absorption spectroscopy of doubly excited states of helium atoms by solving the time-dependent two-electron Schrdinger equation numerically based on a one-dimensional model. The helium atoms are subjected to an extreme ultraviolet (XUV) attosecond pulse and a time-delayed infrared (IR) few-cycle laser pulse. A superposition of doubly excited states populated by the XUV pulse is identified, which interferes with the direct ionization pathway leading to Fano resonance profiles in the photoabsorption spectrum. In the presence of an IR laser, however, the Fano line profiles are strongly modified: A shifting, splitting, and broadening of the original absorption lines is observed when the XUV attosecond pulse and infrared few-cycle laser pulse overlap in time, which is in good agreement with recent experimental results. At certain time delays, we observe symmetric Lorentz, inverted Fano profiles, and even negative absorption cross sections indicating that the XUV light can be amplified during the interaction with atoms. We further prove that the above pictures are general for different doubly excited states by suitably varying the frequency of the IR field to coherently couple the corresponding states.

  14. Sub-20 isolated ultrashort attosecond pulse generation from He atoms by two-color mid-infrared laser fields

    NASA Astrophysics Data System (ADS)

    Li, Peng-Cheng; Chu, Shih-I.

    2014-05-01

    We propose an efficient method for the generation of ultra-broadband supercontinuum spectra and isolated ultrashort attosecond laser pulse from He atoms with two-color mid-infrared laser fields. High-order harmonic generation (HHG) is obtained by solving the time-dependent Schrdinger equation accurately by means of the time-dependent generalized pseudospectral method. We found that the optimizing two-color mid-infrared laser pulse allows the HHG cutoff to be significantly extended, leading to the production of ultra-broadband supercontinuum. As a result, an isolated 18 attosecond pulse can be generated directly by the superposition of the supercontinuum harmonics. To facilitate the exploration of the ultrashort attosecond generation mechanisms, we perform both the semiclassical simulation and the wavelet time-frequency transform. This work was partially supported by DOE and by MOE-NSC-NTU-Taiwan.

  15. Generation of isolated sub-20-attosecond pulses from He atoms by two-color midinfrared laser fields

    NASA Astrophysics Data System (ADS)

    Li, Peng-Cheng; Laughlin, Cecil; Chu, Shih-I.

    2014-02-01

    We propose an efficient method for the generation of ultrabroadband supercontinuum spectra and isolated ultrashort attosecond laser pulses from He atoms with two-color midinfrared laser fields. High-order harmonic generation (HHG) is obtained by solving the time-dependent Schrdinger equation accurately by means of the time-dependent generalized pseudospectral method. We found that the optimizing two-color midinfrared laser pulse allows the HHG cutoff to be significantly extended, leading to the production of an ultrabroadband supercontinuum. As a result, an isolated 18-attosecond pulse can be generated directly by the superposition of the supercontinuum harmonics. To facilitate the exploration of the ultrashort attosecond generation mechanisms, we perform both a semiclassical simulation and a wavelet time-frequency transform.

  16. Two-dimensional imaging of atomic and nanoparticle components in copper plasma plume produced by ultrafast laser ablation

    NASA Astrophysics Data System (ADS)

    Anoop, K. K.; Ni, Xiaochang; Bianco, M.; Paparo, D.; Wang, X.; Bruzzese, R.; Amoruso, S.

    2014-10-01

    We report on the spatial and temporal evolution of the plume generated during ultrafast laser ablation of a pure copper target with 800 nm, ?50 fs, Ti: Sapphire laser pulses. Time-gated imaging was used to record 2-dimensional images of plume populations. The temporal evolution of neutral (Cu*), and ionic (Cu+) components of the plume are separately imaged by exploiting bandpass interference filters, while nanoparticles are investigated by collecting their characteristic broadband emission. The ionic component of the plume moves two to three times faster than the neutral component, with a velocity which is almost independent of laser fluence. Plume emission intensity variations at different fluences and delay times are studied for both atomic and nanoparticle components.

  17. 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.

  18. Morphology study of femtosecond laser nano-structured borosilicate glass using atomic force microscopy and scanning electron microscopy

    NASA Astrophysics Data System (ADS)

    Delobelle, Benot; Courvoisier, Franois; Delobelle, Patrick

    2010-05-01

    The morphology of nano-craters drilled in borosilicate glass by single-shot femtosecond laser ablation has been studied by atomic force microscopy and scanning electron microscopy. The influence of polarization, numerical aperture (NA=0.4 and 0.8) and fluence (3< F<18 J cm -2) was systematically investigated in the case of a strong geometrical confinement, leading to nanometric scale in all spatial dimensions. Indeed, the structure size is not restricted by the diffraction limit but determined by the laser pulse stability and the material properties. The dimensions of the principal and of the secondary (self-focusing) craters, and of the rim have been studied in detail. Different relationships have been proposed for the evolutions of the depths and of the different diameters of the craters as functions of the position of the specimen surface through the beam-material interaction region, and of the characteristics of the laser.

  19. 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.

  20. Infrared (1-12 ?m) atomic and molecular emission signatures from energetic materials using laser-induced breakdown spectroscopy

    NASA Astrophysics Data System (ADS)

    Kumi Barimah, E.; Hmmerich, U.; Brown, E.; Yang, C. S.-C.; Trivedi, S. B.; Jin, F.; Wijewarnasuriya, P. S.; Samuels, A. C.; Snyder, A. P.

    2013-05-01

    Laser-induced breakdown spectroscopy (LIBS) is a powerful analytical technique to detect the elemental composition of solids, liquids, and gases in real time. For example, recent advances in UV-VIS LIBS have shown great promise for applications in chemical, biological, and explosive sensing. The extension of conventional UVVIS LIBS to the near-IR (NIR), mid-IR (MIR) and long wave infrared (LWIR) regions (~1-12 ?m) offers the potential to provide additional information due to IR atomic and molecular signatures. In this work, a Q-switched Nd: YAG laser operating at 1064 nm was employed as the excitation source and focused onto several chlorate and nitrate compounds including KClO3, NaClO3, KNO3, and NaNO3 to produce intense plasma at the target surface. IR LIBS studies on background air, KCl , and NaCl were also included for comparison. All potassium and sodium containing samples revealed narrow-band, atomic-like emissions assigned to transitions of neutral alkali-metal atoms in accordance with the NIST atomic spectra database. In addition, first evidence of broad-band molecular LIBS signatures from chlorate and nitrate compounds were observed at ~10 ?m and ~7.3 ?m, respectively. The observed molecular emissions showed strong correlation with FTIR absorption spectra of the investigated materials.

  1. 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 [Institute of Industrial Science, The University of Tokyo, 4-6-1 Komaba, Meguro-ku, Tokyo 153-8505 (Japan)

    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.

  2. A novel method to compensate for the effect of light shift in a rubidium atomic clock pumped by a semiconductor laser

    Microsoft Academic Search

    M. Hashimoto; MOTOICHI OHTSU

    1990-01-01

    Precise measurement of the shift (i.e. microwave frequency shift induced by the electric field of the pumping light) in a rubidium atomic clock pumped by a semiconductor laser is discussed. The spectral lineshape of the microwave resonance, which is used as a frequency discriminator for the atomic clock in the optical microwave double resonance experiment, depends strongly on the spatial

  3. Elastic Electron Scattering by Laser-Excited (sup 138)Ba (...6s6p (sup 1)P(sub 1)) Atoms

    NASA Technical Reports Server (NTRS)

    Csanak, G.

    1997-01-01

    The result of a joint experimental and theoretical study concerning elastic electron scattering by laser-excited (sup 138)Ba (...6s6p (sup 1)P(sub 1)) atoms are presented. From these studies, we extracted differential scattering cross sections (DCS's) and collision parameters for elastic scattering by the coherently prepared (sup 1)P(sub 1) atoms.

  4. A note on mean energy transfer cross sections due to forced dipole excitations in noble gas atoms by intense CO2 laser pulses

    Microsoft Academic Search

    F. H. M. Faisal

    1987-01-01

    The author presents a quantitative estimate of photon absorption cross sections due to forced dipole excitation in noble gas atoms by intense CO2 laser pulses. The cross sections for Xe, Kr, Ar and Ne are calculated using a dynamic model in which the electron cloud of a complex atom is treated as an inhomogeneous gas. The cross sections are used

  5. Cross sections for ionization of rare gas excimers by electron impact and atomic and molecular processes in excimer lasers. Final report 1 Apr 78-30 Sep 79

    SciTech Connect

    Flannery, M.R.; McCann, K.J.

    1980-03-01

    Theoretical cross sections for ionization of metastable excimers - helium, neon, argon, krypton and xenon - and of metastable mercury are presented. Systematic trends in inelastic form factors and Born cross sections for collisional transitions between excited neighboring levels of atoms are discovered and discussed. Key cycles of atomic and molecular collision processes in excimer lasers are delineated and discussed.

  6. Cross sections for ionization of rare gas excimers by electron impact and atomic and molecular processes in excimer lasers. Final report 1 Apr 78-30 Sep 79

    Microsoft Academic Search

    M. R. Flannery; K. J. McCann

    1980-01-01

    Theoretical cross sections for ionization of metastable excimers - helium, neon, argon, krypton and xenon - and of metastable mercury are presented. Systematic trends in inelastic form factors and Born cross sections for collisional transitions between excited neighboring levels of atoms are discovered and discussed. Key cycles of atomic and molecular collision processes in excimer lasers are delineated and discussed.

  7. Z .Spectrochimica Acta Part B 56 2001 1565 1592 Laser excited atomic fluorescence spectrometry

    E-print Network

    Michel, Robert G.

    , but laser diodes could provide this due to their potential to provide an output with very narrow spectral samples. The advent of diode lasers with their now somewhat improved range of wavelengths and power output of second and third harmonic crystals to pulsed diode lasers shows promise for compact and robust

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

    Microsoft Academic Search

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

    2009-01-01

    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

  9. 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.

  10. Large increase in the electron capture and excitation cross sections for Li+ colliding with atomic H under UV laser assistance

    NASA Astrophysics Data System (ADS)

    Domnguez-Gutirrez, F. J.; Cabrera-Trujillo, R.

    2015-07-01

    Neutralization and ash products due to electron capture processes in plasmas reduce the efficiency of energy generation in fusion Tokamak reactors. Therefore, lithium ions have been used to improve the efficiency of energy generation where good control of the electron capture process is required. Here, we show that an intense (1.4 {{10}13} W cm?2), ultra-short (1 fs at full width half-maximum) Gaussian laser pulse in the UV region can enhance the electron capture process on L{{i}+}+H(1s) in the low collision keV energy region. We find a factor of 10 enhancement in electron capture cross-section at impact energies lower than 10 keV amu?1 for an 80 nm wavelength laser and a factor of 2 for the excitation process in the hydrogen atom as compared to the laser-free case. In contrast, for a 200 nm wavelength laser the increase of the electron capture cross-sections takes place around 1 keV amu?1 by a factor of 3 and no enhancement for the excitation process. Our results show that the UV assisted production of Li can be controlled, particularly for short UV wave-length for a specific collision energy range. We anticipate that our findings will facilitate UV laser control of the Li production in Tokamak reactors and encourage further experimental work in this system.

  11. 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. [Department of Materials Science and Metallurgy, University of Cambridge, Pembroke Street, Cambridge, CB2 3QZ (United Kingdom); Smeeton, Tim M.; Hooper, Stewart E.; Heffernan, Jonathan [Sharp Laboratories of Europe Limited, Edmund Halley Road, Oxford Science Park, Oxford, OX4 4GB (United Kingdom); Saxey, David W.; Smith, George D. W. [Department of Materials, University of Oxford, Parks Road, Oxford, OX1 3PH (United Kingdom)

    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.

  12. Acquired acid resistance of human enamel treated with laser (Er:YAG laser and Co2 laser) and acidulated phosphate fluoride treatment: An in vitro atomic emission spectrometry analysis

    PubMed Central

    Mathew, Anju; Reddy, N. Venugopal; Sugumaran, D. K.; Peter, Joby; Shameer, M.; Dauravu, Liju Marcely

    2013-01-01

    Background: Dental caries is essentially a process of diffusion and dissolution. If the aspect of dissolution can be curtailed some degree of prevention can be achieved. Aims: The present study was carried out to evaluate and compare the effect of Er:YAG laser and Co2 laser irradiation combined with acidulated phosphate fluoride treatment on in vitro acid resistance of human enamel. Design: An in vitro study was carried out on 30 human premolars to evaluate the enamel's acid resistance using an atomic emission spectrometry analysis. Materials and Methods: A total of 60 enamel specimens were prepared from 30 human premolars and were randomly assigned to 6 groups: (1) Untreated (control); (2) 1.23% acidulated phosphate fluoride (APF) gel application alone for 4 min; (3) Er:YAG laser treatment alone; (4) Co2 laser treatment alone; (5) Er:YAG laser + APF gel application; (6) Co2 laser + APF gel application. The specimens were then individually immersed in 5 ml of acetate buffer solution (0.1 mol/L, pH 4.5) and incubated at 37C for 24 h, and the acid resistance was evaluated by determining the calcium ion concentration using the atomic emission spectrometry. Statistical Analysis: An ANOVA model was constructed (P value of 0.05), followed by Tukey's test for multiple pair wise comparisons of mean values. Results: Significant differences were found between the control group and the test groups (P < 0.001). Conclusions: Combining acidulated phosphate fluoride with either Er:YAG or Co2 laser had a synergistic effect in decreasing the enamel demineralization more than either fluoride treatment or laser treatment alone. PMID:24015004

  13. Nano structured carbon nitrides prepared by chemical vapour deposition

    NASA Astrophysics Data System (ADS)

    Karuppannan, Ramesh; Prashantha, M.

    2010-08-01

    Nanostructured carbon nitride films were prepared by pyrolysis assisted chemical vapour deposition(CVD). A two zone furnace with a temperature profile having a uniform temperature over a length of 20 cm length has been designed and developed. The precursor Azabenzimidazole was taken in a quartz tube and evaporated at 400 0C. The dense vapours enter the pyrolysis zone kept at a desired temperature and deposit on the quartz substrates. The FTIR spectrum of the prepared samples shows peaks at 1272 cm-1 (C.N stretching) and 1600 cm-1 (C=N) confirms the bonding of nitrogen with carbon. Raman D and G peaks, are observed at 1360 cm-1 and 1576 cm-1 respectively. XPS core level spectra of C 1s and N 1s show the formation of ? bonding between carbon and nitrogen atoms. The size of the nano crystals estimated from the SEM images and XRD is ~100 nm. In some regions of the sample a maximum of 57 atom % of nitrogen has been observed.

  14. Mechanism of pulse discharge production of iodine atoms from CF3I molecules for a chemical oxygen-iodine laser

    NASA Astrophysics Data System (ADS)

    Kochetov, I. V.; Napartovich, A. P.; Vagin, N. P.; Yuryshev, N. N.

    2009-03-01

    The pulsed chemical oxygen-iodine laser (COIL) development is aimed at many new applications. Pulsed electric discharge is most effective in turning COIL operation into the pulse mode by instant production of iodine atoms. A numerical model is developed for simulations of the pulsed COIL initiated by an electric discharge. The model comprises a system of kinetic equations for neutral and charged species, electric circuit equation, gas thermal balance equation and the photon balance equation. Reaction rate coefficients for processes involving electrons are found by solving the electron Boltzmann equation, which is re-calculated in a course of computations when plasma parameters changed. The processes accounted for in the Boltzmann equation include excitation and ionization of atoms and molecules, dissociation of molecules, electron attachment processes, electron-ion recombination, electron-electron collisions, second-kind collisions and stepwise excitation of molecules. The last processes are particularly important because of a high singlet oxygen concentration in gas flow from the singlet oxygen chemical generator. Results of numerical simulations are compared with experimental laser pulse waveforms. It is concluded that there is satisfactory agreement between theory and the experiment. The prevailing mechanism of iodine atom formation from the CF3I donor in a very complex kinetic system of the COIL medium under pulse discharge conditions, based on their detailed numerical modelling and by comparing these results both with experimental results of other authors and their own experiments, is established. The dominant iodine atom production mechanism for conditions under study is the electron-impact dissociation of CF3I molecules. It was proved that in the conditions of the experiment the secondary chemical reactions with O atoms play an insignificant role.

  15. Two-Photon Laser-Induced Fluorescence O and N Atoms for the Study of Heterogeneous Catalysis in a Diffusion Reactor

    NASA Technical Reports Server (NTRS)

    Pallix, Joan B.; Copeland, Richard A.; Arnold, James O. (Technical Monitor)

    1995-01-01

    Advanced laser-based diagnostics have been developed to examine catalytic effects and atom/surface interactions on thermal protection materials. This study establishes the feasibility of using laser-induced fluorescence for detection of O and N atom loss in a diffusion tube to measure surface catalytic activity. The experimental apparatus is versatile in that it allows fluorescence detection to be used for measuring species selective recombination coefficients as well as diffusion tube and microwave discharge diagnostics. Many of the potential sources of error in measuring atom recombination coefficients by this method have been identified and taken into account. These include scattered light, detector saturation, sample surface cleanliness, reactor design, gas pressure and composition, and selectivity of the laser probe. Recombination coefficients and their associated errors are reported for N and O atoms on a quartz surface at room temperature.

  16. Photonic tunneling effect between two coupled single-atom laser cavities imbedded within a photonic-crystal platform

    SciTech Connect

    Guo Xiaoyong [Department of Physics, Nanjing University, Nanjing 210093 (China); Ren Zhongzhou [Department of Physics, Nanjing University, Nanjing 210093 (China); Center of Theoretical Nuclear Physics, National Laboratory of Heavy-Ion Accelerator, Lanzhou 730000 (China)

    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.

  17. 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

  18. Breakdown voltage of zinc and magnesium vapours

    NASA Astrophysics Data System (ADS)

    Zoestbergen, E.; Commandeur, C.; Maalman, T.

    2014-06-01

    In this paper the findings of a study into the electrical breakdown of zinc and magnesium metal vapours are reported. The interest in the breakdown of these vapours lies in the fact that there is a growing interest in producing zinc-magnesium coated articles using physical vapour deposition. For commercial scale operations which require a high power input, a disturbance by electrical breakdown of the metal vapour is unacceptable. Hence, knowledge of the breakdown voltage and pressure relation of these elements is essential in the engineering of a set-up. To determine the breakdown of these metal vapours, a Knudsen effusion cell is built. It is proven that the flow through the Knudsen cell does not change the minimum breakdown voltage or location of this minimum, and is a reliable apparatus for determining the zinc and magnesium vapour data. The outcome of the experiments show that the minimum breakdown for zinc is in agreement with the reported data in the literature, around 350 V. Magnesium has a much lower minimum breakdown voltage than that found for zinc, around 110 V. Furthermore, the locations of the minimum breakdown voltages of both zinc and magnesium are found at around 4-7 Pa m and 1.5 Pa m respectively.

  19. ATOMIC AND MOLECULAR PHYSICS: Single atoms transferring between a magneto-optical trap and a far-off-resonance optical dipole trap

    NASA Astrophysics Data System (ADS)

    He, Jun; Wang, Jing; Yang, Bao-Dong; Zhang, Tian-Cai; Wang, Jun-Min

    2009-08-01

    Based on our work on single cesium atoms trapped in a large-magnetic-gradient vapour-cell magneto-optical trap (MOT), the signal-to-noise ratio (SNR) is remarkably improved. Also a far-off-resonance optical dipole trap (FORT) formed by a strongly-focused 1064 nm single frequency Nd:YVO4 laser beam is introduced. One cesium atom is prepared in the MOT, and then it can transfer successfully between the MOT and the FORT which is overlapped with the MOT. Utilizing the effective transfer, the lifetime of single atoms trapped in the FORT is measured to be 6.9 0.3 s. Thus we provide a system where the atomic qubit can be coherently manipulated.

  20. 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].

  1. Strong amplification of sidebands in self-focused laser beams in an atomic vapor

    Microsoft Academic Search

    A. C. Tam

    1979-01-01

    A cw dye-laser beam tuned to the high-frequency wing of the Na D2 line (at 2-6 GHz from the center of the D2 line) is focused into a Na vapor, forming a self-focused laser filament. The incident laser beam, which is mainly single frequency, contains very weak sidebands at about +\\/- 1 GHz from the main frequency and of intensity

  2. Two-Hole Localization Mechanism for Electron Bond Rupture of Surface Atoms by Laser-Induced Valence Excitation of Semiconductors

    SciTech Connect

    Tanimura, Katsumi; Inami, E.; Kanasaki, J.; Hess, Wayne P.

    2006-07-16

    We examine the mechanism of electronic bond rupture on semiconductor surfaces induced by laser-generated three-dimensional non-equilibrium valence excitation associated with strong carrier diffusion. For such excited systems, the density of sub-surface valence holes that contribute to two-hole localization on the surface is characterized by quasi Fermi level and effective temperature. The rate of two-hole localization, formulated for equilibrated two-dimensional electronic systems by Sumi [Surf. Sci, 248, 382 (1991)], is re-formulated, and a simple analytical expression is yielded for moderate excitation densities. The resulting theoretical model has been successfully applied in the analysis of recent laser-induced atomic desorption experiments on InP and Si surfaces

  3. Two-hole localization mechanism for electronic bond rupture of surface atoms by laser-induced valence excitation of semiconductors

    SciTech Connect

    Tanimura, K.; Inami, E.; Kanasaki, J. [Institute of Scientific and Industrial Research, Osaka University, 8-1 Mihogaoka, Ibaraki, Osaka 567-0047 (Japan); Hess, Wayne P. [Pacific Northwest National Laboratory, Richland, Washington 99352 (United States)

    2006-07-15

    We examine the mechanism of electronic bond rupture on semiconductor surfaces induced by laser-generated nonequilibrium three-dimensional valence excitation associated with strong carrier diffusion. For such excited systems, the density of subsurface valence holes that contribute to two-hole localization on the surface is characterized by quasi-Fermi-levels and effective temperature. The rate of two-hole localization, formulated for equilibrated two-dimensional electronic systems by Sumi [Surf. Sci. 248, 382 (1991)], is reformulated, and a simple analytical expression is yielded for moderate excitation densities. The resulting theoretical model has been successfully applied in the analysis of recent laser-induced atomic desorption experiments on InP and Si surfaces.

  4. BRIEF COMMUNICATIONS: Relaxation of metastable copper atoms in a copper bromide vapor laser under regular pulse conditions

    NASA Astrophysics Data System (ADS)

    Astadzhov, D. N.; Vuchkov, N. K.; Isaev, A. A.; Petrash, G. G.; Ponomarev, I. V.; Sabotinov, N. V.

    1987-02-01

    An experimental investigation was made of the relaxation of the populations of 2D5/2 and 2D3/2 metastable states of the copper atom in the interpulse period in the active medium of a copper bromide vapor laser under near-optimal lasing conditions. Measurements were resolved over the cross section of the discharge zone. The processes responsible for the observed decay of the metastable state populations were considered. An investigation was made of the influence of hydrogen on the lasing characteristics, the excitation power, and the decay of the metastable-state populations. The reasons for an increase in the output power of a copper bromide vapor laser with added hydrogen are discussed.

  5. Stable isotope evidence of dual (Arabian Sea and Bay of Bengal) vapour sources in monsoonal precipitation over north India

    NASA Astrophysics Data System (ADS)

    Sengupta, Saikat; Sarkar, A.

    2006-10-01

    High resolution time series data of hydrogen ( ?D) and oxygen ( ?18O) isotope values of precipitation have been generated for the first time at Kolkata, eastern India where the summer monsoon clouds from Bay of Bengal (BOB) commence their journey over India. Use of a Rayleigh cum two component mixing model and comparison of Kolkata data with the International Atomic Energy Agency (IAEA)-Global Network of Isotopes in Precipitation (GNIP) data base of New Delhi suggest that the precipitation at New Delhi cannot be explained by simple continental effect of a BOB vapour source alone, traveling and raining successively along Kolkata-New Delhi route. It is necessary to invoke an admixture of 20% vapour originating from the Arabian sea with the vapour coming from BOB and finally causing summer monsoon rains at New Delhi. The findings have major implications to the regional water vapour budget over India.

  6. Optical force on two-level atoms by few-cycle-pulse Gaussian laser fields beyond the rotating-wave approximation

    SciTech Connect

    Kumar, Parvendra; Sarma, Amarendra K. [Department of Physics, Indian Institute of Technology Guwahati, Guwahati-781039, Assam (India)

    2011-10-15

    We report a study on light force on a beam of neutral two-level atoms superimposed upon a few-cycle-pulse Gaussian laser field under both resonant and off-resonant conditions. The phenomena of focusing, defocusing, and steering of the neutral atoms in the laser field are analyzed by solving the optical Bloch equation beyond the rotating-wave approximation and the force equation self-consistently. We find that two-level atoms in an atomic beam can be focused and defocused for large, positively and negatively detuned interactions even in the regime of extreme nonlinear optics. The so-called optical potential may be used for stable trapping of the neutral two-level atoms for large positively detuned interaction. This work successfully reproduces some of the features reported in recent experimental and theoretical works.

  7. 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.

  8. Start broadened profiles with self-consistent radiation transfer and atomic kinetics in plasmas produced by high intensity lasers

    SciTech Connect

    Olson, G.L.; Comly, J.C.; La Gattuta, J.K.; Kilcrease, D.P.

    1993-03-01

    Spectral line shapes and line strengths have long been used to diagnose plasma temperatures and densities. In dense plasmas, the additional broadening due to Stark effects give additional information about the plasma density. We present calculations that are self-consistent in that the radiation fields of the line transitions and the atomic kinetics are iterated to convergence. Examples are given for simple plasmas with temperature gradients, density gradients, and velocity fields. Then a more complex example of a laser produced plasma is presented.

  9. Start broadened profiles with self-consistent radiation transfer and atomic kinetics in plasmas produced by high intensity lasers

    SciTech Connect

    Olson, G.L.; Comly, J.C.; La Gattuta, J.K.; Kilcrease, D.P.

    1993-01-01

    Spectral line shapes and line strengths have long been used to diagnose plasma temperatures and densities. In dense plasmas, the additional broadening due to Stark effects give additional information about the plasma density. We present calculations that are self-consistent in that the radiation fields of the line transitions and the atomic kinetics are iterated to convergence. Examples are given for simple plasmas with temperature gradients, density gradients, and velocity fields. Then a more complex example of a laser produced plasma is presented.

  10. 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.

  11. Atomic line emission and high-order harmonic generation in argon driven by 4-MHz sub-?J laser pulses

    NASA Astrophysics Data System (ADS)

    Blttermann, Alexander; Chiang, Cheng-Tien; Widdra, Wolf

    2014-04-01

    We report on the coexistence of atomic line emission (ALE) and high-order harmonic generation (HHG) from argon with experimental conditions bridging the multiphoton and tunnel ionization regimes. Driven by sub-?J femtosecond laser pulses in tight-focusing geometry, characteristic spectra of ALE from highly excited neutral argon as well as from singly ionized argon are detected in the presence of the harmonics. The results are discussed with respect to the electronic structure of argon and the phase-matching condition of the HHG process.

  12. A new time-frequency method to reveal quatum dynamics of atomic hydrogen in intense laser pulses: Synchrosqueezing transform

    E-print Network

    Sheu, Yae-lin; Hsu, Liang-Yan; Wu, Hau-tieng; Li, Peng-Cheng; Chu, Shih-I

    2014-11-26

    ? d?, (5) where ?,? > 0, h(t) = 1? ? e?t 2 and A?, f (t) ? #8; ? ? R+ : #14; Vf (t, ?) #14; > ? . Note that the threshold ? is to avoid numerical instability when computing Eq. (4). ? also serves as a threshold when noise exists.26 The main idea...AIP ADVANCES 4, 117138 (2014) A new time-frequency method to reveal quantum dynamics of atomic hydrogen in intense laser pulses: Synchrosqueezing transform Yae-lin Sheu,1 Liang-Yan Hsu,2,a Hau-tieng Wu,3,b Peng-Cheng Li,1,4 and Shih-I Chu1,5,c 1...

  13. Epitaxial Growth of Atomically Flat Yttrium Iron Garnet Thin Films on Gadolinium Gallium Garnet by Pulse Laser Deposition

    NASA Astrophysics Data System (ADS)

    Lin, Tao; Tang, Chi; Shi, Jing

    2013-03-01

    Yttrium iron garnet (YIG) is a ferrimagnetic insulator which is useful for magneto-optical, microwave, and more recently spintronic devices. Pulsed laser deposition (PLD) has emerged as a preferred technique to deposit complex oxide thin films, heterostructures, and superlattices with high quality. Deposition of YIG films using PLD has been reported by several groups. The layer-by-layer growth mode has been achieved with a high laser repetition rate. No details about surface morphology were discussed. Here we report our approach to grow YIG films with thickness ranging from 10 to 100 nm on (110)- and (111)-oriented gadolinium gallium garnet (GGG) substrates. In both orientations, we have successfully grown epitaxial YIG thin films confirmed by the patterns of the reflection high-energy electron diffraction. The magnetic properties are measured by a vibrating sample magnetometer. The in-plane easy-axis coercivity is less than 1 Oe, while the perpendicular saturation field is ~ 2000 Oe. For both orientations, the atomic force microscopy images show that the YIG surface is extremely flat with roughness ~ 0.6. Flat terraces are found with the atomic step height in films with both orientations. This work paves the way to engineering anisotropy of the thin films for YIG-based magnetic devices. Yttrium iron garnet (YIG) is a ferrimagnetic insulator which is useful for magneto-optical, microwave, and more recently spintronic devices. Pulsed laser deposition (PLD) has emerged as a preferred technique to deposit complex oxide thin films, heterostructures, and superlattices with high quality. Deposition of YIG films using PLD has been reported by several groups. The layer-by-layer growth mode has been achieved with a high laser repetition rate. No details about surface morphology were discussed. Here we report our approach to grow YIG films with thickness ranging from 10 to 100 nm on (110)- and (111)-oriented gadolinium gallium garnet (GGG) substrates. In both orientations, we have successfully grown epitaxial YIG thin films confirmed by the patterns of the reflection high-energy electron diffraction. The magnetic properties are measured by a vibrating sample magnetometer. The in-plane easy-axis coercivity is less than 1 Oe, while the perpendicular saturation field is ~ 2000 Oe. For both orientations, the atomic force microscopy images show that the YIG surface is extremely flat with roughness ~ 0.6. Flat terraces are found with the atomic step height in films with both orientations. This work paves the way to engineering anisotropy of the thin films for YIG-based magnetic devices. This work was supported in part by DMEA and DOE.

  14. 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 m) 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.

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

    SciTech Connect

    Schoenlein, Robert (Deputy Director, Advanced Light Source) [Deputy Director, Advanced Light Source

    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.

  16. Precise Atomic Structure Measurements in Thallium at 378 nm using a Frequency-doubled Diode Laser

    Microsoft Academic Search

    Protik Majumder; Robert Lyman; Paul Friedberg; David Richardson

    2001-01-01

    Using both a heated thallium vapor cell and a recently constructed atomic beam apparatus, we have undertaken a series of precise atomic structure measurements within the 378 nm 6P_1\\/2 - 7S_1\\/2 E1 transition in atomic thallium. These measurements provide important, independent cross-checks on the accuracy of ongoing calculations of parity nonconservation in thallium. For these experiments, we use an external

  17. 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.

  18. 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.

  19. Atomic force microscopic characterization of films grown by inverse pulsed laser deposition

    Microsoft Academic Search

    L. gerhzi; Zs. Geretovszky; T. Csk; T. Szrnyi

    2006-01-01

    Carbon nitride films have been deposited by KrF excimer laser ablation of a rotating graphite target in 5Pa nitrogen ambient in an inverse pulsed laser deposition configuration, where the backward motion of the ablated species is utilised for film growth on substrates lying in the target plane. Topometric AFM scans of the films, exhibiting elliptical thickness distribution, have been recorded

  20. Laser spectroscopy of simple atoms and precision tests of bound state QED

    E-print Network

    Savely G. Karshenboim

    2000-08-23

    We present a brief overview of precision tests of bound state QED and mainly pay our attention to laser spectroscopy as an appropriate tool for these tests. We particularly consider different precision tests of bound state QED theory based on the laser spectroscopy of optical transitions in hydrogen, muonium and positronium and related experiments.

  1. 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.

  2. 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 [Graduate School of Engineering, Kobe University, Rokko-dai 1-1, Nada, Kobe 657-8501 (Japan); Technology Research Institute of Osaka Prefecture, Ayumino 2-7-1, Izumi, Osaka 594-1157 (Japan)

    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.

  3. Pulse duration effects on laser-assisted electron transfer cross section for He2+ ions colliding with atomic hydrogen

    NASA Astrophysics Data System (ADS)

    Domnguez-Gutirrez, Francisco Javier; Cabrera-Trujillo, Remigio

    2014-08-01

    We study the effect of the pulse duration for an ultra-fast and intense laser on the fundamental process of electron capture by analyzing the excitation probability into the n = 2 and n = 3 states when He2+ collides with atomic hydrogen in the 0.05-10 keV/amu energy range, a region of interest for diagnostic processes on plasma and fusion power reactors. We solve the time-dependent Schrdinger equation to calculate the electron capture probability by means of a finite-differences, as well as by an electron-nuclear dynamics approach. In particular, we study the effects of 1, 3, 6, and 10 fs laser pulses at FWHM, wavelength of 780 nm and intensity of 3.5 1012 W/cm2. We report good agreement for the laser-free state and total electron transfer cross-sections when compared to available theoretical and experimental data. The effect of the laser pulse on the electron capture probability as a function of the impact parameter is such that the charge exchange probability increases considerably in the impact parameter radial region with an increase in the amplitude oscillations and a phase shift on the Stckelberg oscillations. We find an increase on the total electron exchange cross-section for low projectile collision energy when compared to the laser-free case with a minimal effect at high collision energies. We find that the 1 fs laser pulse has a minimal effect, except for very low collision energies. Although in general, the longer the laser pulse, the larger the electron capture probability, at very low collision energies all pulse widths have an effect. For processes in the atto-second region, our findings suggest that to enhance the laser-assisted charge exchange, the best region for short pulses is at very low collision energies. We also find that the s and p state charge exchange cross section are equally affected. We provide a qualitative discussion of these findings.

  4. Energy Analyses of Field-Emitted Ions Using the Pulsed-Laser Time-Of Atom Probe

    NASA Astrophysics Data System (ADS)

    Wang, Jong-Bor

    A high resolution pulsed-laser time-of-flight atom-probe developed in our group is used to measure the kinetic energy distribution of field emitted ions. Two kinds of ions are studied; one is the image gas ion and the other is the metal lattice ion. The energy distribution of field emitted ions reveals the spatial origin where the ions are formed and hence provides information on the mechanism of field desorption (or field evaporation). The critical ion energy deficit derived from the energy distribution also relates to many physical properties of the surface and the atoms, such as the work function, the ionization energy of ionized atoms, and the binding energy of the ionized atoms, etc. The energy distribution of field desorbed helium ions can reveal the local electronic density of states of the surface. However, no such study has been reported so far. I report here such a study using tungsten clusters of different sizes on a W(110) surface. We have first prepared tungsten clusters by laser-enhanced field evaporation. These W clusters include single W adatoms, W adatom dimers, two W adatoms separated by two lattice constants, four and five W adatoms in zigzag shapes. Then helium field desorption spectra from these tungsten clusters were collected using the pulsed-laser time-of-flight atom-probe. The ion energy distribution from the single W adatom shows an extra peak -like feature centered at 2.7 eV above the Fermi level with a full width at half maximum (FWHM) of 2.3 eV. The data from two tungsten adatoms separated by two lattice constants have nearly the same features with the peak located at 2.5 eV above the Fermi level. This peak-like feature occurs from a resonance tunneling with the adatom local density of states (LDOS). The He ion energy distribution of a tungsten dimer looks different, but it still has an extra peak centered at 1.5 eV above the Fermi level. The FWHM is about 4 eV. The spectra from four and five tungsten adatom clusters show only one peak each, similar to the He ion energy distribution from a macrotip. These are new experimental findings and they are explained by the degree of interactions between adatoms and the metal surface. The field-evaporation behavior of Mo is found to be very different from other metals and is examined by the pulsed-laser time-of-flight atom-probe. The ion energy distribution of Mo^{2+} shows a double peak structure and the ion energy distribution of Mo^{3+} has a broad energy peak. To explain the formation of the low energy peak of the Mo^{2+} ions and the abnormally small critical ion energy deficit of the Mo^{3+} ions, we propose a two-step field-evaporation mechanism for the field evaporation of molybdenum in which two Mo atoms line up with the field before they are field ionized and desorbed. Also at low field strengths (3.7 to 4.2 V/A) and high temperatures (about 600^circ K), ions of triply charged Mo dimers can be detected. (Abstract shortened by UMI.).

  5. Threshold of a Random Laser with Cold Atoms Luis S. Froufe-Perez,1

    E-print Network

    with a cloud of cold atoms, in which gain and scattering are provided by the same atoms. The lasing threshold the fundamentals of random lasing [7,8]. The broad interest of this topic is driven by potential applications (see is provided by a disordered scattering medium, while gain is provided by an active material lying in the host

  6. Absolute detection of metastable rare gas atoms by a cw laser photoionization method

    Microsoft Academic Search

    S. Schohl; D. Klar; T. Kraft; H. A. J. Meijer; M.-W. Ruf; U. Schmitz; S. J. Smith; H. Hotop

    1991-01-01

    A novel, accurate method for the absolute detection of metastable rare gas atoms is described and demonstrated. It involves a direct in situ determination of the electron emission coefficient ? for impact of the respective metastable atom on a conducting surface. ? is reliably obtained by a cw two-photon ionization depletion technique: the reduction ?IS in electron current from

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

    E-print Network

    Li, Hebin

    2011-08-08

    . The transmitted probe profile is shown as well. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 68 xii FIGURE Page 28 Experimental setup of intensity correlation in EIT and simplified energy level scheme of rubidium atoms. PBS... fit. . . . . . . . . . . . . . . . . . . . . . . . . . . . 79 32 Experimental setup of noise study in NMOR and the energy levels of rubidium atoms. (a) is the detection setup for measuring the correlation of noise, (b) is the detection setup...

  8. Limitations of an optically pumped rubidium laser imposed by atom recycle rate

    Microsoft Academic Search

    W. S. Miller; C. V. Sulham; J. C. Holtgrave; G. P. Perram

    2011-01-01

    A rubidium laser pumped on the 52S1\\/2-52P3\\/2 D2 transition by a pulsed dye laser at pump intensities exceeding 3.5 MW\\/cm2 (>1000 times threshold) has been demonstrated. Output energies as high as 12 muJ\\/pulse are limited by the rate for collision relaxation of the pumped 2P3\\/2 state to the upper laser 2P1\\/2 state. More than 250 photons are available for every

  9. Limitations of an optically pumped rubidium laser imposed by atom recycle rate

    Microsoft Academic Search

    W. S. Miller; C. V. Sulham; J. C. Holtgrave; G. P. Perram

    2011-01-01

    A rubidium laser pumped on the 52S1\\/252P3\\/2 D2 transition by a pulsed dye laser at pump intensities exceeding 3.5MW\\/cm2 (>1000 times threshold) has been demonstrated. Output energies as high as 12 ?J\\/pulse are limited by the rate for collision\\u000a relaxation of the pumped 2P3\\/2 state to the upper laser 2P1\\/2 state. More than 250 photons are available for every rubidium

  10. Investigation of laser blow-off atomic beams by electron impact excitation

    SciTech Connect

    Bakos, J.S.; Foeldes, I.B.; Ignacz, P.N.; Kocsis, G. (Central Research Institute for Physics, H-1525 Budapest P.O.B. 49, Hungary (HU) )

    1991-02-01

    Electron impact excitation in the edge region of the MT-1 tokamak was used to measure the velocity distribution of a sodium laser blow-off beam in a single shot. The different dependencies of the propagation velocity of the blow-off neutral beam on the laser fluence at different sodium layer thicknesses reveal different regimes of the blow-off process. In the case of thick targets laser ablation is the main accelerating mechanism giving a {ital v}{similar to}{ital I}{sup 1/3} dependence. Thin targets, however, burn through during the laser pulse, and simple thermal heating process results in {ital v}{similar to}{ital I}{sup 1/2} in good agreement with the experiments.

  11. 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.

  12. 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.

  13. A compact grating-stabilized diode laser system for atomic physics

    Microsoft Academic Search

    L. Ricci; M. Weidemller; T. Esslinger; A. Hemmerich; C. Zimmermann; V. Vuletic; W. Knig; T. W. Hnsch

    1995-01-01

    We describe a compact, economic and versatile diode laser system based on commercial laser diodes, optically stabilized by means of feedback from a diffraction grating. We offer detailed information which should enable the reader to copy our set-up which uses only easily machined mechanical parts. Our system offers single-mode operation with a linewidth of a few 100 kHz, continuous scans

  14. Modeling of laser-induced excitation and ionization in cesium atoms

    Microsoft Academic Search

    Y. E. E. Gamal; M. A. Mahmoud; H. A. Abd El-Rahman

    2005-01-01

    A theoretical model is presented to describe kinetics of the plasma formation in cesium undergone to resonant laser excitation (D1,2 line). The model is based on a rate equations approach where the following populations are considered: ground state (6s level), laser excited level (6p), a series of high excited levels close to the ionization limit, and the electron density. We

  15. ATOMIC AND MOLECULAR PHYSICS: Structural Deformation of CO22+ in Intense Femtosecond Laser Fields

    NASA Astrophysics Data System (ADS)

    Zhang, Sheng; Xia, Yuan-Qin; Wang, Yu-Quan; Lu, Zhen-Zhong; Chen, De-Ying

    2009-08-01

    The angular distributions of CO+ from the dissociation of CO2+2 and CO+2 in intense femtosecond laser fields (45 fs, about 5 1015 W/cm2) are studied at a laser wavelength of 800 nm based on the time-of-flight mass spectra of CO fragment ions. The experimental results show that structural deformation occurs in the charge state of CO2+2 and the CO+2 maintains linear geometrical structure.

  16. Reflectivity and energy balance in pulsed-laser deposition experiments from mono- and bi-atomic targets.

    PubMed

    Mller, T; Sinha, B K; Rohr, K P

    2002-08-01

    Reflectivity and complete energy balance from the planar targets of aluminum, copper, nickel, and molybdenum have been measured using a Nd: glass laser (lambda=1060 nm,tau=5 ns) in the low intensity regime of laser plasma interaction as a function of focal spot size. The magnitude of partition of total incident laser energy into different channels is observed to decrease as the focal spot size increases. It is further observed that the magnitude of partition of the incident energy into these channels, in general, decreases as the atomic number increases for any given focal spot size, although, the reflectivity component of the partitioned energy increases with focal spot size for any given element. The reflectivities of copper and tungsten and their alloy were measured separately. The reflectivity from the alloy plasma was reduced by a factor of 6 compared to either element separately. This observation confirms the recent theory that in the multiion plasma the ion acoustic waves are additionally damped due to additional Joule, thermal diffusion, and viscous terms in the modified ion-fluid theory of the ion acoustic waves in a multiion species plasma. PMID:12241293

  17. Electron collisions with cesium atomsbenchmark 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.

  18. 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 [Department of Physics, National University, 30 Jangjun-Dong, Geumjeong-Gu, Busan 609-735 (Korea, Republic of); Department of Physics Education, Korea National University of Education, Chung-buk, 363-791 (Korea, Republic of)

    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.

  19. 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 [Department of Advanced Energy, University of Tokyo, 5-1-5 Kashiwanoha, Kashiwa, Chiba 227-8568 (Japan); Oda, Tetsuji [Department of Electrical Engineering, University of Tokyo, 7-3-1 Hongo, Bunkyo-ku, Tokyo 113-8656 (Japan)

    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.

  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