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1

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

Microsoft Academic Search

We discuss the basic physical principles of laser optical pumping double-resonance spectroscopy, which form the basis of state-of-the-art vapour-cell atomic frequency standards using laser optical pumping of Rb atoms. The main effects limiting the frequency stability of Rb vapour-cell atomic clocks are identified, and their impact on the development of high-performance frequency standars and their transfer from research laboratories to

Gaetano Mileti; C. Affolderbach

2005-01-01

2

Some new trends in laser isotope separation in atomic vapours  

SciTech Connect

New approaches to the methods of laser isotope separation are considered and realised which substantially extend the possibilities of the methods. To narrow down an absorption line and decrease parasitic absorption at transitions in isotope atoms that do not belong to an isotope being separated, two-photon excitation of atoms was used both in collinear and counterpropagating light beams. By using two-photon excitation in counterpropagating light beams, the weight amounts of Zn isotopes were separated under the conditions when the isotopic structure of a resonance transition was completely masked by the Doppler broadening. Two-photon excitation in collinear beams was used for efficient purification of lead from a rare {sup 210}Pb isotope to obtain a low-radioactive lead. A detailed computer simulation of separation of isotopes of Zn, B, Pb, and Si using two-photon excitation was performed. An efficient method of isotope separation involving chemical reactions with selectively excited long-lived atoms was proposed and realised. The method offers some advantages over the conventional photoionisation method. (invited paper)

Bokhan, P A; Zakrevskii, D E; Kalugin, M M; Fateev, N V [Institute of Semiconductor Physics, Siberian Branch of the Russian Academy of Sciences, Novosibirsk (Russian Federation); Buchanov, V V [Astrofisika Research and Production Association, Moscow (Russian Federation); Kazaryan, M A [P.N. Lebedev Physics Institute, Russian Academy of Sciences, Moscow (Russian Federation); Prokhorov, A M [A.M. Prokhorov General Physics Institute, Russian Academy of Sciences, Moscow (Russian Federation)

2002-07-31

3

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

NASA Astrophysics Data System (ADS)

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

Mileti, Gaetano; Affolderbach, C.

2005-04-01

4

Nonlinear behaviour of atomic fluorescence in mercury vapours following double-resonance laser excitation  

NASA Astrophysics Data System (ADS)

When mercury atoms, present with a buffer gas (N2 or Ar) in a quartz cell or in a graphite furnace are excited into the 7(sup 3)S(sub 1) level by means of two pulsed dye lasers tuned at 253.652 nm (6(sup 1)S(sub 0) yields 6(sup 3)P(sub 1)) and 435.835 nm (6(sup 3)P(sub 1) yields 7(sup 3)S(sub 1)), a laser-like, collimated emission is observed along the axis of the cell at the green mercury line (7(sup 3)S(sub 1) yields 6(sup 3)P(sub 2)), 546.074 nm). This radiation exhibits a pronounced non-linear dependence upon the number density of the mercury atoms in the cell. This behaviour is interpreted as being due to amplified spontaneous emission (ASE), which occurs as a result of the transient population inversion between the 7s(sup 3)S(sub 1) and 6p(sup 3) P(sup 0)(sub 2) levels. The parameters governing the population inversion can be deduced by applying a rate equation analysis to the atomic system. A time-resolved observation of both ASE and spontaneous fluorescence signals confirms the totally different characteristics of the two emission processes.

Omenetto, N.; Matveev, O. I.; Resto, W.; Badini, R.; Smith, B. W.; Winefordner, J. D.

1994-04-01

5

Atomic vapour microcells: Tubes for quantum electronics  

NASA Astrophysics Data System (ADS)

Micrometre-sized atomic vapour cells hosting robust entangled atomic states at room temperature offer a promising route to the realization of quantum photonic devices such as quantum gates and single-photon sources.

Rost, Jan-Michael

2010-02-01

6

IV INTERNATIONAL CONFERENCE ON ATOM AND MOLECULAR PULSED LASERS (AMPL'99): Critical electron density in a self-contained copper vapour laser in the restricted pulse repetition rate  

NASA Astrophysics Data System (ADS)

One of the mechanisms of the inversion breaking in copper vapour lasers caused by a high prepulse electron density is considered. Inversion breaking occurs at a critical electron density Ne cr. If the prepulse electron density exceeds Ne cr, the electron temperature Te cr cannot reach, during a plasma heating pulse, the temperature of ~2eV required for lasing. A simple estimate of Ne cr is made.

Yakovlenko, Sergei I.

2000-06-01

7

Atom Lasers.  

National Technical Information Service (NTIS)

The general goal of this research was the generation, manipulation and characterization of coherent and non-classical matter waves, including atom lasers. The research involved both a theoretical and an experimental component. Major achievements from the ...

P. Meystre P. Jessen

2000-01-01

8

Laser Keyhole Welding: The Vapour Phase  

NASA Astrophysics Data System (ADS)

Several aspects of the properties of the keyhole and its relationship to the weld pool in laser keyhole welding are considered. The aspect of most immediate importance is the exchange of energy between the laser beam itself and the molten material of the weld pool. Many mechanisms are involved, but the two considered here are the process of direct absorption at the keyhole wall (Fresnel absorption) and the two-stage process of absorption of energy by inverse bremsstrahlung into the ionised vapour that forms in the case of the longer-wavelength lasers such as the CO2, laser, followed by thermal conduction to the wall. Consideration is given to the role of the Knudsen layer at the boundary. The possibility that the exchange may be influenced by the vapour flow in the keyhole is considered. More generally, the dynamics of the flow is investigated and the balances necessary to keep the keyhole open are investigated. A simple model of the interaction of the vapour with the molten material in the weld pool is proposed which can be used to investigate their interaction. Order of magnitude estimates suggest that it is far from simple but that some simplifying approximations are possible.

Dowden, John

9

XUV photoabsorption of laser generated Au vapour  

Microsoft Academic Search

Photoabsorption by atomic Au in the 5p and 4f excitation region has been studied using the dual laser plasma (DLP) technique. The observed features are dominated by two prominent Fano-type resonance lines which can be attributed to 5p to 5d and 4f to 5d transitions of valence excited 5d96s2(2D52\\/) Au followed by autoionization. The experimental results are compared to spectra

U. Koble; J. T. Costello; J. P. Mosnier; E. T. Kennedy; M. Martins

1995-01-01

10

Transition Correlation Studies in a Water Vapour Laser  

Microsoft Academic Search

The interaction between several pairs of coupled water vapour lines was investigated with a compound mirror -grating-grating (MGG) laser, which allows the simultaneous and coaxial lasing of two linearly polarized wavelengths parallel or perpendicular to each other. The interaction experiments were done with four pairs of competitive water vapour lines; the 26.6 and 47.70, 26.6 and 47.47, 27.97 and 47.70,

Paul Adrien Rochefort

1987-01-01

11

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

SciTech Connect

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)

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

2012-10-31

12

Development of insulated gate bipolar transistor-based power supply for elemental copper vapour laser  

Microsoft Academic Search

The elemental copper vapour laser is a widely used laser from a family of metal vapour lasers for applications such as dye\\u000a laser pumping, micromachining etc. In this paper, we report the development and performance of IGBT-based pulsed power supply\\u000a that replaced conventional thyratron-based power supply for 4.7 cm diameter, 150 cm long copper vapour laser. The laser tube\\u000a delivered

R. K. Mishra; S. V. Nakhe; G. N. Tiwari; J. K. Mittal

2010-01-01

13

Strontium vapour laser with a pulse repetition rate of up to 1 MHz  

SciTech Connect

For the first time it has been shown that the pulse repetition rate of the lasers on the self-terminating transitions of metal atoms may be as high as {approx}1 MHz. The highest pulse repetition rate equal to {approx}830 kHz was realised on self-terminating IR transitions in Sr I atoms ({lambda} = 6.456 {mu}m and {approx}3 {mu}m) and in Sr II ions ({lambda} {approx} 1 {mu}m) in a strontium vapour laser operating in a self-heating pulse periodic regime. The energy yield of a Sr laser was found to be proportional to the energy input into the active medium in a wide range of excitation pulse repetition frequencies; in this case, the average total specific output laser power is equal to 30 - 40 mW cm{sup -3}. (lasers)

Soldatov, Anatolii N; Yudin, Nikolai A; Vasilieva, Anna V; Kolmakov, E A; Polunin, Yurii P; Kostyrya, I D

2012-01-31

14

INTERACTION OF LASER RADIATION WITH MATTER: Resonance laser-induced ionisation of sodium vapour taking radiative transfer into account  

NASA Astrophysics Data System (ADS)

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

Kosarev, N. I.; Shaparev, N. Ya

2006-04-01

15

Mixed Garnet laser crystals for water vapour DIAL transmitter  

NASA Astrophysics Data System (ADS)

There are more or less well established technologies such as the optical-parametric-oscillator (OPO), the Raman-laser, and the Ti-Sapphire laser, which are able to emit laser light in the region of the water vapour absorption lines. For WALES the regions of about 935 nm, 942 nm, and 944 nm have been identified as the most suitable wavelength ranges. However, each of these laser designs is highly sophisticated. Current baseline for WALES is the Ti-Sapphire laser. A fourth possibility to achieve these wavelength ranges is to shift the groundstate laser lines (938 nm and 946 nm) of the Nd:YAG laser by replacing Aluminium and Yttrium by other rare earth elements. Changes of the host lattice characteristics lead to a shift of the upper and lower laser levels. These modified crystals are summarized under the name of "Mixed Garnet" crystals. Only the Mixed Garnet lasers can be pumped directly with diode laser and use a direct approach to generate the required laser pulses without frequency conversion. Therefore no additional non-linear crystals are needed and a higher electric to optical efficiency is expected as well as single frequency operation using spectral tuning elements like etalons. Such lasers have the great potential to fulfil the requirements and to become the preferred transmitter concept for WALES as well as for follow up missions. Within a ESA study several crystal compositions have been grown, spectrally characterised and analysed. Absorbed space radiation energy in the crystal lattice causes colour centres, which can reabsorb the pump and laser wavelength and consequently reduce the laser gain considerably. Co-dopants such as Chromium and Cerium are able to suppress the colour centres and are candidates for effective radiation hardening. The results of the crystal tuning, the co-doping with different radiation hardeners and the radiation tests will be presented. There applicability for a space based water vapour DIAL transmitter will be discussed.

Treichel, Rainer; Czeranowsky, Christoph; Ileri, Bilge; Petermann, Klaus; Huber, Günter

2004-06-01

16

Atomic physics of lasers  

SciTech Connect

This book illustrates the basic concepts using lasers. It describes physical processes rather than comprehensive mathematical formulations. Topics considered include an elementary review of the structure of atoms and molecules, interaction of electromagnetic radiation with atoms, light amplification, solid and liquid lasers, and gas lasers.

Eastham, D.A.

1986-01-01

17

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

NASA Astrophysics Data System (ADS)

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.

Cartaleva, S.; Krasteva, A.; Moi, L.; Sargsyan, A.; Sarkisyan, D.; Slavov, D.; Todorov, P.; Vaseva, K.

2013-09-01

18

Manufacturing diamond films using copper vapour lasers  

SciTech Connect

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.

McLean, M., LLNL

1996-01-08

19

Laser physico-chemical vapour deposition of cubic boron nitride thin films  

Microsoft Academic Search

A laser physico-chemical vapour deposition (LPCVD) technique was developed based on the interaction of an ultraviolet laser beam with a boron nitride target and borazine gas to synthesize cubic boron nitride (CBN) thin films on silicon substrates. The process involved a hybrid of pulsed laser ablation (PLA) of a solid HBN target and chemical vapour deposition (CVD) using borazine as

P. A. Molian

1994-01-01

20

Metal atom oxidation laser  

DOEpatents

A chemical laser which operates by formation of metal or carbon atoms and reaction of such atoms with a gaseous oxidizer in an optical resonant cavity is described. The lasing species are diatomic or polyatomic in nature and are readily produced by exchange or other abstraction reactions between the metal or carbon atoms and the oxidizer. The lasing molecules may be metal or carbon monohalides or monoxides.

Jensen, R.J.; Rice, W.W.; Beattie, W.H.

1975-10-28

21

Metal atom oxidation laser  

DOEpatents

A chemical laser which operates by formation of metal or carbon atoms and reaction of such atoms with a gaseous oxidizer in an optical resonant cavity is described. The lasing species are diatomic or polyatomic in nature and are readily produced by exchange or other abstraction reactions between the metal or carbon atoms and the oxidizer. The lasing molecules may be metal or carbon monohalides or monoxides. (auth)

Jensen, R.J.; Rice, W.W.; Beattie, W.H.

1975-10-28

22

Coherent excitation of Rydberg atoms in micrometre-sized atomic vapour cells  

NASA Astrophysics Data System (ADS)

The coherent control of mesoscopic ensembles of atoms and Rydberg atom blockade are the basis for proposed quantum devices such as integrable gates and single-photon sources. To date, experimental progress has been limited to complex experimental set-ups that use ultracold atoms. Here, we show that coherence times of ~100 ns are achievable with coherent Rydberg atom spectroscopy in micrometre-sized thermal vapour cells. We investigate states with principle quantum numbers between 30 and 50. Our results demonstrate that microcells with a size on the order of the blockade radius (~2 µm), at temperatures of 100-300 °C, are robust and promising candidates for investigating low-dimensional strongly interacting Rydberg gases, constructing quantum gates and building single-photon sources.

Kübler, H.; Shaffer, J. P.; Baluktsian, T.; Löw, R.; Pfau, T.

2010-02-01

23

Guided quasicontinuous atom laser.  

PubMed

We report the first realization of a guided quasicontinuous atom laser by rf outcoupling a Bose-Einstein condensate from a hybrid optomagnetic trap into a horizontal atomic waveguide. This configuration allows us to cancel the acceleration due to gravity and keep the de Broglie wavelength constant at 0.5 microm during 0.1 s of propagation. We also show that our configuration, equivalent to pigtailing an optical fiber to a (photon) semiconductor laser, ensures an intrinsically good transverse mode matching. PMID:17155665

Guerin, W; Riou, J-F; Gaebler, J P; Josse, V; Bouyer, P; Aspect, A

2006-11-13

24

CONTROL OF LASER RADIATION PARAMETERS: Control of the radiation parameters of a copper vapour laser  

NASA Astrophysics Data System (ADS)

The possibility of controlling the pulse shape and duration and the beam divergence of a copper vapour laser operating in the mode of double pump pulses, when the first pulse excites lasing in the active medium and the second amplifies it. It is shown that a change in the delay of the second pump pulse relative to the laser pulse initiated by the first pump pulse allows an efficient control of the laser-radiation characteristics. In this case, the coefficient of laser-radiation conversion into a beam with a diffraction-limited divergence may reach ~80 %.

Polunin, Yu P.; Yudin, Nikolai A.

2003-09-01

25

INTERACTION OF LASER RADIATION WITH MATTER. LASER PLASMA: Dynamics of laser deposition of metals from the vapour phase on insulators  

NASA Astrophysics Data System (ADS)

Laser deposition of metals from the vapour phase on insulator surfaces by the action of cw laser radiation is investigated theoretically. Changes in the surface morphology during deposition and the temperature dependence of the vapour medium are taken into account. It is shown that during the initial stage the deposit may be mushroom-shaped, whereas later it becomes rod-shaped. If a moving laser beam is employed, the deposit may assume the form of a series of rods (fibres) tilted relative to the substrate surface.

Kirichenko, N. A.; Nikolaeva, E. G.

1997-03-01

26

Study on laser atomic spectroscopy.  

National Technical Information Service (NTIS)

Laser atomic spectroscopic study on actinium element has been performed in many areas of spectroscopy. The study on characteristics of atomic vapor has been done for copper atom and the spatial density distribution of copper vapor is measured. This experi...

H. K. Cha K. S. Song D. Y. Jeong J. Lee J. H. Yi

1993-01-01

27

Pulsed atomic soliton laser  

SciTech Connect

It is shown that simultaneously changing the scattering length of an elongated, harmonically trapped Bose-Einstein condensate from positive to negative and inverting the axial portion of the trap, so that it becomes expulsive, results in a train of self-coherent solitonic pulses. Each pulse is itself a nondispersive attractive Bose-Einstein condensate that rapidly self-cools. The axial trap functions as a waveguide. The solitons can be made robustly stable with the right choice of trap geometry, number of atoms, and interaction strength. Theoretical and numerical evidence suggests that such a pulsed atomic soliton laser can be made in present experiments.

Carr, L.D.; Brand, J. [JILA, National Institute for Standards and Technology and University of Colorado, Boulder, Colorado 80309-0440 (United States); Max Planck Institute for the Physics of Complex Systems, Noethnitzer Strasse 38, 01187 Dresden (Germany)

2004-09-01

28

Modelling of the kinetics and parametric behaviour of a copper vapour laser: Output power limitation issues  

SciTech Connect

A self-consistent computer model was used to simulate the plasma kinetics (radially resolved) and parametric behaviour of an 18 mm bore (6 W) copper vapour laser for a wide range of optimum and non-optimum operating conditions. Good quantitative agreement was obtained between modelled results and experimental data including the temporal evolution of the 4p{sup 2}P{sub 3/2}, 4s{sup 2} {sup 2}D{sub 5/2} and 4s{sup 2}{sup 2}D{sub 3/2} Cu laser level populations derived from hook method measurements. The modelled results show that the two most important parameters that affect laser behaviour are the ground state copper density and the peak electron temperature T{sub e}. For a given pulse repetition frequency (prf), maximum laser power is achieved by matching the copper atom density to the input pulse energy thereby maintaining the peak T{sub e} at around 3 eV. However, there is a threshold wall temperature (and copper density) above which the plasma tube becomes thermally unstable. At low prf ({lt}8 kHz), this thermal instability limits the attainable copper density (and consequently the laser output power) to values below the optimum for matching to the input pulse energy. For higher prf values ({gt}8 kHz), the copper density can be matched to the input pulse energy to give maximum laser power because the corresponding wall temperature then falls below the threshold temperature for thermal instability. For prf {gt}14 kHz, the laser output becomes highly annular across the tube diameter due to a severe depletion of the copper atom density on axis caused by radial ion pumping. {copyright} {ital 1997 American Institute of Physics.}

Carman, R.J. [Centre for Lasers and Applications, Macquarie University, North Ryde, Sydney, New South Wales 2109 (Australia)

1997-07-01

29

XUV photoabsorption of laser-generated W and Pt vapours  

Microsoft Academic Search

The absorption spectra of atomic W and Pt have been recorded by the dual laser plasma technique in the range of the 4f and 5p excitations. Broad, strong and asymmetric 5p to 5d resonances dominate the spectra. The Pt 4f to 5d transitions give rise to prominent maxima superimposed on the high energy slope of the 5p to 5d resonances.

J. T. Costello; E. T. Kennedy; B. F. Sonntag; C. L. Cromer

1991-01-01

30

Atomic laser-beam finder.  

PubMed

We report on an experimental method to align a laser beam to a cloud of atoms trapped in a magneto-optical trap (MOT). We show how balanced lock-in detection leads to a very sensitive method to align the laser beam to the atoms in the plane perpendicular to the propagation direction. This provides a very reliable and fast way of aligning laser beams to atoms trapped in a MOT. PMID:23187377

Viering, Kirsten; Medellin, David; Mo, Jianyong; Raizen, Mark G

2012-11-01

31

Application of copper vapour lasers for controlling activity of uranium isotopes  

NASA Astrophysics Data System (ADS)

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

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

2013-06-01

32

Quantitative vapour-liquid visualization using laser-induced exciplex fluorescence  

Microsoft Academic Search

We describe an optical technique for quantitative evaluation of the concentrations of coexisting vapour and liquid phases in a spray. A laser-induced exciplex fluorescence visualization system allows time-resolved two-dimensional fluorescence images of vapour and liquid distributions to be acquired simultaneously using two-colour emission. The method is based on the exciplex formers DMA (N,N-dimethylaniline) and 1,4,6-TMN (trimethylnaphthalene) in a non-polar solvent.

Jong-Uk Kim; Byungyou Hong

2001-01-01

33

Collision lasers on atomic transitions  

SciTech Connect

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. (review)

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

2009-02-28

34

Quantitative vapour-liquid visualization using laser-induced exciplex fluorescence  

NASA Astrophysics Data System (ADS)

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

Kim, Jong-Uk; Hong, Byungyou

2001-09-01

35

Lasers, Understanding the Atom Series.  

ERIC Educational Resources Information Center

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

Hellman, Hal

36

Lasers, Understanding the Atom Series.  

ERIC Educational Resources Information Center

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

Hellman, Hal

37

Diode laser atomic absorption spectrometry  

NASA Astrophysics Data System (ADS)

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

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

2005-01-01

38

The Collective Atomic Recoil Laser  

SciTech Connect

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

Courteille, Ph.W.; Cube, C. avon; Deh, B.; Kruse, D.; Ludewig, A.; Slama, S.; Zimmermann, C. [Physikalisches Institut, Eberhard-Karls-Universitaet Tuebingen, Auf der Morgenstelle 14, D-72076 Tuebingen (Germany)

2005-05-05

39

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

SciTech Connect

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

Iliev, I P [Department of Physics, Technical University of Plovdiv, Plovdiv (Bulgaria); Gocheva-Ilieva, S G [Department of Applied Mathematics and Modelling, Faculty of Mathematics and Informatics, Paisii Hilendarski University of Plovdiv (Bulgaria)

2010-08-27

40

High-power copper vapour lasers and applications  

SciTech Connect

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

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

1995-08-01

41

Diode laser atomic absorption spectrometry  

Microsoft Academic Search

The paper reviews the past 11 years of literature on the application of diode lasers in atomic absorption spectrometry with graphite furnaces (GF), plasmas and flames as atomizers. Experimental arrangements and techniques for powerful absorption measurements as well as the theoretical background are covered. The analytical possibilities of high-resolution spectroscopy, including Doppler-free techniques for isotope selective measurements and isotope dilution

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

2005-01-01

42

Atomic vapor laser isotope separation process  

DOEpatents

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

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

1990-08-21

43

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

NASA Astrophysics Data System (ADS)

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

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

2006-06-01

44

Kinetically enhanced copper vapour lasers employing H2-HCl-Ne buffer gas mixtures  

NASA Astrophysics Data System (ADS)

The output powers from 25 mm (volume 0.49 l) and 40 mm (volume 1.9 l) diameter copper vapour lasers (nominally 20 and 55 W devices) are approximately doubled to >50 and >100 W respectively by adding small partial pressures of both H2 and HCl to the neon buffer gas. Our studies show that this gas mixture performs better than a H2-HBr admix, a result we attribute to more efficient reassociation of HCl in the plasma region.

Withford, Michael J.; Brown, Daniel J. W.; Carman, Robert J.; Piper, James A.

1998-08-01

45

Four-wave-mixing stopped light in hot atomic rubidium vapour  

NASA Astrophysics Data System (ADS)

Digital signal processing, holography, and quantum and classical information processing rely heavily upon recording the amplitude and phase of coherent optical signals. One method for achieving coherent information storage makes use of electromagnetically induced transparency. Storage is achieved by compressing the optical pulse using the steep dispersion of the electromagnetically induced transparency medium and then mapping the electric field to local atomic quantum-state superpositions. Here we show that nonlinear optical processes may enhance pulse compression and storage, and that information about the nonlinear process itself may be stored coherently. We report on a pulse storage scheme in hot atomic rubidium vapour, in which a four-wave-mixing normal mode is stored using a double-? configuration. The entire (broadened) waveform of the input signal is recovered after several hundred microseconds (1/e time of about 120 µs), as well as a new optical mode (idler) generated from the four-wave-mixing process.

Camacho, Ryan M.; Vudyasetu, Praveen K.; Howell, John C.

2009-02-01

46

Tunable transient evolutional behaviours of a four-level atomic vapour and the application to photonic logic gates  

Microsoft Academic Search

The evolutional optical behaviours (turn-on dynamics) of a four-level N-configuration atomic system are considered based on the transient solution to the equations of motion of atomic probability amplitudes. It is shown that the quantum interference between the signal and control fields can lead to the controllable absorption and transparency properties of the atomic vapour. One of the most remarkable properties

Arash Gharibi; Jian Qi Shen; Jing Gu

2009-01-01

47

Atomic vapor laser isotope separation  

SciTech Connect

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

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

1985-11-08

48

Mixed garnet laser crystals for water vapour detection  

Microsoft Academic Search

The main objective of this work is the realization of a ground state laser at the required wavelengths of the differential absorption lidar (DIAL)-transmitter, the emission wavelengths of each crystal-type has been analysed. Two possible Nd-doped garnet crystals for different wavelength regions have been identified: GSAG for 942 nm and YGG for 935 nm. In addition to the first grown

B. Ileri; C. Czeranowsky; K. Petermann; G. Huber

2005-01-01

49

Atom laser based on Raman transitions  

Microsoft Academic Search

In this paper we present an atom laser scheme using a Raman transition for the output coupling of atoms. A beam of thermal atoms (bosons) in a metastable atomic state is pumped into a multimode atomic cavity. This cavity is coupled through spontaneous emission to another cavity for the atomic ground state. Above a certain threshold pumping rate a large

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

1997-01-01

50

An Atom Laser Based on Raman Transitions  

Microsoft Academic Search

In this paper we present an atom laser scheme using a Raman transition for the output coupling of atoms. A beam of thermal atoms (bosons) in a metastable atomic state $|1 >$ are pumped into a multimode atomic cavity. This cavity is coupled through spontaneous emission to a single mode of another cavity for the ground atomic state, $|2 >$.

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

1996-01-01

51

Laser cooling of thulium atoms  

NASA Astrophysics Data System (ADS)

We demonstrated laser cooling and trapping of thulium atoms at sub-Doppler temperatures in a magneto-optical trap (MOT). Up to 3 × 106 thulium atoms were trapped in the MOT at temperatures down to 25(5) ?K which is approximately 10 times lower than the Doppler limit. The lifetime of atoms in the MOT varied between 0.3-1.5 s and was restricted mostly by optical leaks from the upper cooling level. The lower limit for the leaking rate was estimated to be 22(6) s-1. Due to a big magnetic moment of Tm atoms, a part of them were trapped in a magnetic trap from the quadrupole field of the MOT. We observed about 3 × 104 purely magnetically trapped atoms at temperature of 25 ?K with a lifetime in the trap of 0.5 s. Also we set up a "dark" MOT consisting of six crossed hollow beams which increased the number of trapped atoms by a factor of 5 leading to 1.5 × 107 atoms at the expense of higher temperature.

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

2011-10-01

52

ACTIVE MEDIA: Dynamics of operation of a CO2 laser with methanol and ethanol vapours as intracavity saturable absorbers  

Microsoft Academic Search

The results are given of experimental and theoretical investigations of the dynamics of operation of a CO2 laser with methanol and ethanol vapours as intracavity saturable absorbers. A model of such a laser is proposed. This model accounts for the existence of two longitudinal modes when the frequency is scanned within the limits of the gain profile. The numerical calculations

O. L. Gaiko; L. A. Kotomtseva; Vladimir V. Nevdakh; L. N. Orlov; A. M. Samson

1994-01-01

53

Photo-acoustic laser spectroscopy of water vapour and cloud content onboard passenger aircraft  

NASA Astrophysics Data System (ADS)

Water in form of water vapour and clouds is one of the most important trace species in the upper troposphere and lower stratosphere (UTLS), as it is responsible for ~75% (or ~25 K) of the natural greenhouse effect (Schmidt et al., JGR, 2010) and carries huge amounts of latent heat. Better climate models and realistic future predictions are therefore depending on how well the global hydrological cycle is understood and described in the models. Accurate measurements of water vapour and cloud water/ice in the UTLS are one essential step towards this goal. Here, we describe the technical set-up of a 2-channel photo-acoustic laser spectrometer (PAS) that was designed for fully unattended use aboard the CARIBIC passenger aircraft. The instrument makes use of an accurate frost-point hygrometer for in-flight calibration of two fast-responding PA channels to measure water vapour and cloud water, respectively. The efforts that were necessary to achieve high-precision (low acoustic noise) photo-acoustic signals within a noisy environment are described. Detailed system analyses were carried out prior and during the operational phase of this instrument. The precision of the instrument is ~0.8 ppmv at 3 sec integration time, and can be improved to 85 ppbv when averaging the data for 300 s. The accuracy is determined by the frost-point hygrometer, and is found to be better than ~0.5 ppmv. With its capability to accurately measure both water vapour and cloud water, this instrument provides unique insight in the hydrological cycle. It is operated since 2005 for four intercontinental flights per month aboard the CARIBIC passenger aircraft. Some scientific results gained during its airborne operation are presented. These include (i) a flight through ice clouds which demonstrates the performance of the device, (ii) the seasonal variation of water vapour from the UT up to 5 km above above the (mid-latitude) tropopause, or (iii) the distribution of the supersaturation inside and outside of clouds.

Sanati, Shahrokh; Zahn, Andreas; Dyroff, Christoph

2013-04-01

54

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

NASA Astrophysics Data System (ADS)

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 proposed a searching algorithm for a single-pass configuration and developed a novel iterative algorithm for a double-pass case which has taken the single-pass solution as an initial value. The calculation process demonstrates a fast rate of convergence and high degree of accuracy. By this algorithm, some special cases, for example, the non-uniform longitudinal distribution of alkali atom concentration, can also be solved well. The model and the numerical approach described in this paper demonstrate a new method to simulate the CW end-pumped quasi-three- or three-level lasers. In this way, no significant assumptions or simplifications are needed in the model, and both the detailed intra-cavity information and pump power distribution can be obtained. To ensure the correctness of our model, a comparison between our model and Beach et al's model is made. The result shows that when the non-uniformity of the longitudinal population distribution is less than 20% or the pump intensity is far beyond the threshold, the assumption of longitudinal population average is valid and the two models are equivalent. When the pump intensity is near the threshold, this assumption may be invalid due to the large longitudinal population variation. If this case happens or more detailed laser information is required, we could use this model to obtain a more accurate solution.

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

2011-04-01

55

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

Microsoft Academic Search

A simple and accurate method has been developed for the determination of total mercury in environmental and biological samples. The method utilises an off-line microwave digestion stage followed by analysis using a flow injection system with detection by cold vapour atomic absorption spectrometry.The method has been validated using two certified reference materials (DORM-1 dogfish and MESS-2 estuarine sediment) and the

James Murphy; Phil Jones; Steve J. Hill

1996-01-01

56

Emission actinometric investigations of atomic hydrogen and CH radicals in plasma-enhanced chemical vapour deposition processes of hexamethyldisiloxane  

Microsoft Academic Search

Spectral investigations were carried out in a plasma-enhanced chemical vapour deposition (PECVD) process using hexamethyldisiloxane (HMDSO) thin film deposition. The experiments were performed in a closed reactor with r.f. plasma generation in the pressure range of 20–40 Pa and power range of 10–20 W.It is shown that the emission lines of atomic hydrogen (486 nm) and CH radicals (431 nm)

V. Shogun; A. Tyablikov; St. Schreiter; W. Scharff; T. Wallendorf; S. Marke

1998-01-01

57

Tunable pulse-periodic converter operating in the blue part of the spectrum and pumped by a copper vapour laser  

Microsoft Academic Search

Two-stage conversion of the radiation of a pulse- periodic copper vapour laser to the blue part of the spectrum was achieved experimentally. The average output power attained in such conversion was 400 mW for the 450 nm line when the pulse repetition frequency was 15625 Hz and the pulse duration was 50 ns. (letters to the editor)

M A Kazaryan; Sergei V Kruzhalov; Yurii M Mokrushin; V A Parfenov; Nikolai A Lyabin; A M Prokhorov; O V Shakin

1998-01-01

58

[Research on the laser atomization treatment machine].  

PubMed

This text has introduces a new-type laser treatment device. It utilizes the ultrasound atomized gas passage as its optics and makes the laser beams together with the atomized medicine to be transmitted to the patient's respiratory track and lungs for treatment. PMID:16419948

Jiang, Bei-sheng; Tian, Rong-zhe; Zhang, Liang

2005-07-01

59

Generic model of an atom laser  

Microsoft Academic Search

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 nonvanishing value in the steady state. We study the transient regime of this atom laser, and find oscillations around the stationary solution

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

1998-01-01

60

Atom laser based on Raman transitions  

Microsoft Academic Search

In this paper we present an atom laser scheme using a Raman transition for\\u000athe output coupling of atoms. A beam of thermal atoms (bosons) in a metastable\\u000aatomic state $|1 >$ are pumped into a multimode atomic cavity. This\\u000acavity is coupled through spontaneous emission to a single mode of another\\u000acavity for the ground atomic state, $|2 >$.

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

1997-01-01

61

Nanosecond pulsed excimer laser machining of chemical vapour deposited diamond and highly oriented pyrolytic graphite: Part I An experimental investigation  

Microsoft Academic Search

A laser beam offers the benefits of high precision, contamination-free, high speed, and low bulk temperature for machining\\u000a of chemically vapour deposited (CVD) diamond thin films that in turn enable ultrafine finishing of diamond coated cutting\\u000a tool inserts and drills, and for finishing and drilling of diamond coated multichip module applications. In this work, laser\\u000a hole drilling and polishing of

R. WINDHOLZ; P. A. MOLIAN

1997-01-01

62

Quantum Theory of Atom Laser Cooling  

Microsoft Academic Search

In this paper, we study the laser cooling mechanisms with extended Schrodinger quantum wave equation, which can describe a\\u000a particle in conservative and non-conservative force field. We prove the atom in laser field can be cooled with the theory,\\u000a and predict that the atom cooling temperature T is directly proportional to the atom vibration frequency ?, which are in accordance

Xiang-Yao Wu; Bai-Jun Zhang; Jing-Hai Yang; Xiao-Jing Liu; Yi-Heng Wu; Qing-Cai Wang; Yan Wang; Nuo Ba; Jing-Wu Li

2011-01-01

63

Push-Pull Laser-Atomic Oscillator  

SciTech Connect

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.

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

2007-11-30

64

A 10 kHz Ce:LiSAF laser pumped by the sum-frequency-mixed output of a copper vapour laser  

Microsoft Academic Search

We report what we believe is the first Ce:LiSAF laser pumped by the 271 nm sum-frequency-mixed output of a copper vapour laser. The 10 kHz pulse-repetition-frequency (PRF) free-lasing Ce:LiSAF laser yielded a maximum output power of 70 mW, with a slope efficiency of 21%. With a single prism tunability from 285–295 nm was achieved, which is believed to be the

A. J. S. McGonigle; D. W. Coutts; S. Girard; R. Moncorgé

2001-01-01

65

The atomic iodine photodissociation laser  

SciTech Connect

After almost two decades of laboratory research and development, the iodine photodissociation laser is now a developed system with industrial and scientific applications. This article reviews the progress of the iodine laser, the basic configuration and performance of a flashlamp-pumped system, and several applications areas. The major impetus behind the development of the iodine photodissociation laser (IPL) has been the requirement for a high-power, short-pulse, terawatt laser for laser fusion studies.

Bannister, J.J.; King, T.A.

1984-08-01

66

A 10 kHz Ce:LiSAF laser pumped by the sum-frequency-mixed output of a copper vapour laser  

NASA Astrophysics Data System (ADS)

We report what we believe is the first Ce:LiSAF laser pumped by the 271 nm sum-frequency-mixed output of a copper vapour laser. The 10 kHz pulse-repetition-frequency (PRF) free-lasing Ce:LiSAF laser yielded a maximum output power of 70 mW, with a slope efficiency of 21%. With a single prism tunability from 285-295 nm was achieved, which is believed to be the first report of tunable laser operation from a Ce:LiSAF laser, operating at high (multi-kHz) PRFs.

McGonigle, A. J. S.; Coutts, D. W.; Girard, S.; Moncorgé, R.

2001-06-01

67

Liquid chromatographic--cold vapour atomic fluorescence spectrometric determination of mercury species.  

PubMed

Solvent extraction, sonication, and microwave-assisted extractions in the presence of extraction agents (thioacetic acid, citric acid, cysteine, 2-mercaptoethanol, HCl + NaCl, etc.) were tested for the isolation of mercury species. A mixture of 6 M HCl and 0.1 M NaCl was selected as the most suitable extraction agent. The extraction efficiency was about 10% higher and the RSD below 3.3% when microwave-assisted extraction was applied instead of sonication. The liquid chromatography-cold vapour atomic fluorescence spectrometry (LC/CV-AFS) method was optimised and used for separation and determination of inorganic mercury cations and alkylated and arylated mercury species. Isocratic elution at a flow rate of 0.15 mL/min (with a mobile phase containing 0.05% 2-mercaptoethanol (pH = 5) and 7% methanol and with a stepwise increase of methanol content up to 100% MeOH in the 15th min) was used for separation of mercury species on a Hypersil BDS C18 RP column. The limits of detection of the LC/CV-AFS system were estimated as 0.2 microg/L (3%) for MeHg+, 0.07 microg/L (5.3%) for inorganic Hg, 0.06 microg/L (3.4%) for PhHg+, and 0.12 microg/L (4.4%) for EtHg with the corresponding RSDs at 5 microg/L (n = 10) given in parentheses. The concentrations (2-10 mg/kg fresh weight) of total mercury and methylmercury (90-99% of the total mercury) in selected fish obtained by HPLC/CV-AFS were in good agreement (absolute deviations 0.05 mg/kg) but more precise (RSDs <5.4% at 5 mg/L, n = 10) than those determined by GC coupled to an electron capture detector. The RSDs (3.1-8.2% and 4.1-9.0%) of the overall analytical procedure for the determination of total mercury (AMA 254) and methylmercury (HPLC/CV-AFS) were determined for intra-day and inter-day assays, respectively. PMID:16524099

Houserová, Pavlina; Matejícek, David; Kubán, Vlastimil; Pavlícková, Jana; Komárek, Josef

2006-02-01

68

High Intensity Laser Interactions with Atomic Clusters.  

National Technical Information Service (NTIS)

The development of ultrashort pulse table top lasers with peak pulse powers in excess of 1 TW has permitted an access to studies of matter subject to unprecedented light intensities. Such interactions have accessed exotic regimes of multiphoton atomic and...

T. Ditmire

2000-01-01

69

Rapid method for the determination of total mercury in urine samples using cold vapour atomic fluorescence spectrometry.  

PubMed

A rapid method for the determination of total mercury in urine samples is proposed. Samples are digested using a bromination procedure at room temperature. Analysis is performed using automated continuous flow vapour generation coupled to atomic fluorescence spectrometry. This approach allowed the analysis of 30 samples per hour and a limit of detection of 1 ng l-1. The analytical procedure was assessed using certified reference material NBS 2672a freeze-dried urine and two batches of Seronorm trace elements in urine samples. PMID:7872489

Corns, W T; Stockwell, P B; Jameel, M

1994-11-01

70

Trapping cold atoms with ultrafast laser pulses  

NASA Astrophysics Data System (ADS)

The aim of this research is to pave the way for making a trap for cold neutral atoms based on the force generated by pulses of a mode-locked laser. As an onset towards such a trap we decided to use a far-off-resonance trap (FORT) loaded with cold rubidium atoms from a magneto-optical trap (MOT). Our FORT setup consists of a titanium-sapphire laser that can operate both in continuous wave mode and in mode-locked mode. Our MOT setup uses a magnetic field gradient, and two diode lasers whose frequency is locked very accurately to the atomic transition using polarisation spectroscopy. Since the measurements we do require very precise timing of the order of less than one millisecond between the various phases of the experiment, a time-sequencing program was developed. Using this sophisticated setup, several characteristics of FORTs made with continuous and pulsed lasers were analysed. For example, we have investigated the loading behaviour of the traps and found that under general circumstances there is no significant difference. However, under special conditions it is possible to load more atoms into a pulsed trap. The lifetime of the number of atoms in the trap shows no dependence on the power of the trap laser in the continuous case. For the pulsed trap, however, the increased scattering due to the high peak intensities of the pulses does limit the achievable lifetimes. Moreover, due to the presence of a large number of photoassociation lines, i.e. lines were loosely bound molecules are formed by the interaction of two atoms an a photon, the two-particle losses depend heavily on the wavelength of the trap laser. Furthermore we have done measurements of the temperature of the trapped atoms, which revealed that the temperature is a constant fraction of the trap depth. We also looked at the effects of parametric excitation of the atoms in the FORT. The anharmonicity of the trap formed by the titanium-sapphire laser results in interesting physics, including a change in the average temperature of the atoms, depending on the modulation frequency. We also investigated the trapping behaviour of the FORT at low pulse repetition rates by switching the laser intensity on and off on a kHz scale. We investigated the dependence of the number of atoms on the polarisation of the FORT laser light, both for continuous and pulsed traps. Atoms can be trapped at elliptical polarisations as well, although the number of trapped atoms is less. As the laser is detuned further to the red of the rubidium D line, this effect becomes less and less pronounced, as predicted by our model.

Karssen, L. C.

2008-10-01

71

Laser densification of TiO2 films prepared by aerosol assisted vapour deposition  

NASA Astrophysics Data System (ADS)

This paper concerns the microstructural development and phase transition of the aerosol deposited nanocrystalline titanium dioxide films by laser densification. Dense titanium dioxide films have been prepared using laser densification of porous films, which have been deposited using aerosol assisted spray deposition (AASD) at low temperature from a colloidal suspension and a metalorganic precursor. The AASD process involves spraying atomized aerosol precursor towards a heated zone where the droplets undergo chemical reactions at the heated substrate to deposit a solid film. Processing parameters can be varied to control microstructure, porosity, grain size and phase of the titanium dioxide films. The effect of the processing parameter of laser energy density has been investigated and 7.6 7.8 J mm-2 is an optimal energy density for laser densification of titanium dioxide films prepared by the AASD. X-ray diffraction (XRD) was used to analyze the crystalline phase of titanium dioxide films before and after laser irradiation and heat treatment. The microstructure of laser irradiated films and the morphology of nanoparticle precursor were characterized using scanning electron microscopy (SEM) and transmitting electron microscopy (TEM). Laser densification has been shown to be a promising technique to densify porous films rapidly without deleterious effect on thermally sensitive substrates.

Wu, Yiquan; Choy, Kwang-Leong; Hench, Larry L.

2005-07-01

72

Laser modification of ultracold atomic collisions: Theory  

Microsoft Academic Search

Specific molecular mechanisms are proposed for associative ionization collisions of ultracold sodium atoms in a hybrid optical trap. When an intense, strongly detuned optical trap laser is on, the ionization rate is modulated by molecular bound-state resonances which are strongly affected by field dressing. When the weak, slightly detuned optical molasses lasers are on to provide cooling, an excitation mechanism

Paul S. Julienne; Robert Heather

1991-01-01

73

Diode-Pumped Alkali Atom Lasers.  

National Technical Information Service (NTIS)

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, Rubidiu...

R. H. Page R. J. Beach

2005-01-01

74

Single-frequency Nd:YGG laser at 935 nm for future water-vapour DIAL systems  

Microsoft Academic Search

For future satellite based water vapour DIAL systems, efficient and rugged laser sources are required preferably around 935 nm. The quasi 4-level transition from R2 to Z5 in Nd:YGG is a promising candidate for its direct generation. Q-switch operation at 100 Hz with pulse energies up to 7.7 mJ is reported as well as single frequency operation with an injection

Jens Löhring; Ansgar Meissner; Valentin Morasch; Peter Becker; Wolfgang Heddrich; Dieter Hoffmann

2009-01-01

75

Laser trapping of radioactive francium atoms  

Microsoft Academic Search

The difficult problem of quickly slowing and cooling nuclear reaction products so that they can be injected into a laser trap has been solved by several groups and there are now strong efforts to work with the trapped atoms. The atoms are confined in the trap to a small spatial volume of the order of 1 mm3, but more importantly,

G. D. Sprouse; L. A. Orozco; J. E. Simsarian; W. Shi; W. Z. Zhao

1997-01-01

76

Laser trapping of radioactive francium atoms  

Microsoft Academic Search

The difficult problem of quickly slowing and cooling nuclear reaction products so that they can be injected into a laser trap has been solved by several groups and there are now strong efforts to work with the trapped atoms. The atoms are confined in the trap to a small spatial volume of the order of 1 mm3, but more importantly,

G. D. Sprouse; L. A. Orozco; J. E. Simsarian; W. Shi; W. Z. Zhao

1996-01-01

77

Atomic stabilization by super-intense lasers.  

PubMed

Supercomputer simulations predict the creation of an unexpectedly stable form of atomic matter when ordinary atoms are irradiated by very intense, high-frequency laser pulses. In the rising edge of a very intense pulse of ionizing radiation, the atom's wave function distorts adiabatically into a distribution with two well-separated peaks. As the intensity increases, the peak spacing increases so that the atomic electron spends more time far from the nucleus and the ionization rate decreases. This leads to the surprising and counter-intuitive result that the atom becomes more stable as the ionizing radiation gets stronger. PMID:17772644

Eberly, J H; Kulander, K C

1993-11-19

78

Determination of total arsenic content in water by atomic absorption spectroscopy (AAS) using vapour generation assembly (VGA).  

PubMed

Analysis of arsenic in water is important in view of contamination of ground water with arsenic in some parts of the world including West Bengal in India and neighboring country Bangladesh. WHO has fixed the threshold for arsenic in drinking water to 10ppb (microg/l) level, hence the methodology for determination of arsenic is required to be sensitive at ppb level. Atomic absorption spectrophotometry with vapour generation assembly (AAS-VGA) is well known technique for the trace analysis of arsenic. However, total arsenic analysis [As(III)+As(V)] is very crucial and it requires reduction of As(V) to As(III) for correct analysis. As(III) is reduced to AsH3 vapours and finally to free As atoms, which are responsible for absorption signal in AAS. To accomplish this the vapour generation assembly attached to AAS has acid channel filled with 10 M HCl and the reduction channel with sodium borohydride. Further sample can be reduced either before aspiration for analysis, using potassium iodide (KI) or the sample can be introduced in the instrument directly and KI can be added in the reduction channel along with the sodium borohydride. The present work shows that samples prepared in 3 M HCl can be reduced with KI for 30 min before introduction in the instrument. Alternatively samples can be prepared in 6 M HCl and directly aspirated in AAS using KI in VGA reduction channel. The latter methodology is more useful when the sample size is large and time cycle is difficult to maintain. It is observed that the acid concentration of the sample in both the situations plays an important role. Further reduction in acid concentration and analysis time is achieved for the arsenic analysis by using modified method. Analysis in both the methods is sensitive at ppb level. PMID:16213544

Behari, Jai Raj; Prakash, Rajiv

2005-10-06

79

Atom-photon pair laser  

SciTech Connect

We study the quantum dynamics of an ultracold atomic gas trapped in an optical lattice within an optical high-Q resonator. The atoms are coherently illuminated with the cavity resonance tuned to a blue vibrational sideband so that stimulated gain of the resonator mode is accompanied by vibrational cooling of the atoms. This system exhibits a threshold above which pairwise stimulated generation of a cavity photon and an atom in the lowest vibrational band dominates spontaneous scattering and we find a combination of optical lasing with a buildup of a macroscopic population in the lowest lattice band. Including output coupling of ground-state atoms and replenishing of hot atoms into the cavity volume leads to a coherent, quantum correlated atom-photon pair source very analogous to twin light beam generation in a nondegenerate optical parametric oscillator.

Salzburger, Thomas; Ritsch, Helmut [Institute for Theoretical Physics, University of Innsbruck, Technikerstrasse 25/2, 6020 Innsbruck (Austria)

2007-06-15

80

Quantum motion of laser trapped atoms  

SciTech Connect

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

Jessen, P.S.

1993-05-01

81

Collisions Between Laser-Cooled Atoms  

Microsoft Academic Search

Collisions between laser-cooled atoms have a number of remarkable features. The exceptionally low temperature in laser-cooled clouds (<100 muK) means that the collision dynamics are not only sensitive to very long-range interatomic forces (even as modified by tiny hyperfine interactions), but also strongly depend on multiple light emission and absorption processes during the course of the collision. The light-induced collision

Thad Walker

1997-01-01

82

Detecting Individual Atoms and Molecules with Lasers  

Microsoft Academic Search

Resonance-ionization spectroscopy was developed by the author and his colleagues at the U.S.S.R. Academy of Sciences and, independently, by G. Samuel Husrst and his colleagues at the Oak Ridge National Laboratory. Resonance-ionization spectroscopy relies on lasers. Lasers having a set of chosen wavelengths can be exploited to detect a desired atom or molecule in a mixture. The wavelengths can be

Vladilen S. Letokhov

1988-01-01

83

Influence of the pre-pulse plasma electron density on the performance of elemental copper vapour lasers  

NASA Astrophysics Data System (ADS)

A detailed computer model for the kinetics in an elemental copper vapour laser (Cu-Ne-H2) has been used to investigate the importance of the pre-pulse electron density on the performance and lasing characteristics of such a device. The results show that the laser output power and operating efficiency are increased by 65% and 100%, respectively, at a pulse repetition frequency of 17 kHz, if the pre-pulse electron density is reduced by a factor of 5-10. Modelling of the plasma kinetics during the afterglow period suggests that such a reduction is brought about when trace quantities (~0.3%) of HCl are introduced into the plasma to increase the electron density decay rates via dissociative attachment reactions. The predicted improvements in laser performance which occur as a result of a reduced pre-pulse electron density are consistent with the observed operating characteristics of Kinetically Enhanced copper vapour lasers which use HCl-H2-Ne buffer gas mixtures.

Carman, Robert J.; Withford, Michael J.; Brown, Daniel J. W.; Piper, James A.

1998-12-01

84

Prospects of laser cooling in atomic thallium  

SciTech Connect

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

Fan, Isaac; Chen, Tzu-Ling; Liu, Yu-Sheng; Lien, Yu-Hung; Liu, Yi-Wei [Department of Physics, National Tsing Hua University, Hsinchu 30013, Taiwan (China); Shy, Jow-Tsong [Department of Physics, National Tsing Hua University, Hsinchu 30013, Taiwan (China); Institute of Photonics Technologies, National Tsing Hua University, Hsinchu 30013, Taiwan (China)

2011-10-15

85

Laser trapping of {sup 21}Na atoms  

SciTech Connect

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.

Lu, Zheng-Tian

1994-09-01

86

Optimal laser positioning for laser-assisted atom probe tomography.  

PubMed

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

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

2013-03-23

87

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

NASA Astrophysics Data System (ADS)

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

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

1996-12-01

88

Apparatus For Laser Excitation of Lithium Atoms.  

NASA Astrophysics Data System (ADS)

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.

Daly, James; Flaherty, Suzy; Oxley, Paul

2006-10-01

89

Lattice Interferometer for Laser-Cooled Atoms  

SciTech Connect

We demonstrate an atom interferometer in which atoms are laser cooled into a 1D optical lattice, suddenly released, and later subjected to a pulsed optical lattice. For short pulses, a simple analytical theory predicts the signal. We investigate both short and longer pulses where the analytical theory fails. Longer pulses yield higher precision and larger signals, and we observe a coherent signal at times that can differ significantly from the expected echo time. The interferometer has potential for precision measurements of (Planck constant/2pi)/m{sub A}, and can probe the dynamics of atoms in an optical lattice.

Andersen, Mikkel F.; Sleator, Tycho [Atomic Physics Division, National Institute of Standards and Technology, Gaithersburg, Maryland 20899-8424 (United States) and Jack Dodd Center for Quantum Technology, Department of Physics, University of Otago (New Zealand); Department of Physics, New York University, 4 Washington Place, New York, New York 10003 (United States)

2009-08-14

90

Evaluation of a Continuous Flow Furnance Atomizer for Laser Excited Atomic Fluorescence Spectrometry  

Microsoft Academic Search

A system for continuous sample introduction into a ceramic atomization furnace for laser excited atomic fluorescence spectrometry (LEAFS) was developed. The system was evaluated using two different excitation sources, a nitrogen laser-pumped dye laser and a copper vapor laser-pumped dye laser. Pure aqueous Pb solutions were used for system optimization and analytical calibration curves. These curves were linear over at

J. B. Womack; C. A. Ricard; B. W. Smith; J. D. Winefordner

1989-01-01

91

Bohmian picture of laser-atom interaction  

NASA Astrophysics Data System (ADS)

We present the implementation of the Bohmian hydrodynamic formulation of quantum mechanics to the description of electron dynamics in one-dimensional laser-atom interaction. The resulting quantum trajectories clearly picture the dynamics and yield an accurate description of observables.

Botheron, P.; Pons, B.

2009-11-01

92

Laser manipulation of atoms and particles  

NASA Astrophysics Data System (ADS)

A variety of powerful techniques to control the position and velocity of neutral particles has been developed. As examples of this new ability, lasers have been used to construct a variety of traps, to cool atoms to temperatures below 3 x 10 exp -6th K, and to create atomic fountains that may give a hundredfold increase in the accuracy of atomic clocks. Bacteria can be held with laser traps while they are being viewed in an optical microscope, and organelles within a cell can be manipulated without puncturing the cell wall. Single molecules of DNA can now be stretched out and pinned down in a water solution with optical traps. These new capabilities may soon be applied to a wide variety of scientific questions as diverse as precision measurements of fundamental symmetries in physics and the study of biochemistry on a single molecule basis.

Chu, Steven

1991-08-01

93

Waveguide atom beam splitter for laser-cooled neutral atoms.  

PubMed

A laser-cooled neutral-atom beam from a low-velocity intense source is split into two beams while it is guided by a magnetic-field potential. We generate our multimode beam-splitter potential with two current-carrying wires upon a glass substrate combined with an external transverse bias field. The atoms are guided around curves and a beam-splitter region within a 10-cm guide length. We achieve a maximum integrated flux of 1.5x10(5)atoms/s with a current density of 5x10(4)amp/cm (2) in the 100-microm -diameter wires. The initial beam can be split into two beams with a 50/50 splitting ratio. PMID:18066224

Müller, D; Cornell, E A; Prevedelli, M; Schwindt, P D; Zozulya, A; Anderson, D Z

2000-09-15

94

Photoassociation of Laser-cooled Ytterbium Atoms  

NASA Astrophysics Data System (ADS)

We report photoassociation of laser-cooled ytterbium (Yb) atoms. By detecting the trap loss of 174Yb atoms in the FORT due to the photoassociation beam, we could observe more than 90 photoassociation resonances of vibrational levels in the {}1? u^ + state which connects asymptotically to the 1S0+1P1 atomic state in the dissociation limit. From the observed resonance frequencies we could precisely determine the atomic radiative lifetime of the 1P1 state to 5.464 ± 0.005 ns. We have also observed linebroadening of photoassociation resonances, which is ascribed to the predissociation to the triplet states, and determined the transition probability to be 0.2. Furthermore, we have observed the decrease of the intensity of photoassiciation signal at 435 GHz detuning from the 1S0+1P1 asymptote, from which the scattering length is estimated to be equal to or less than 3 nm.

Takahashi, Y.; Takasu, Y.; Komori, K.; Honda, K.; Kumakura, M.; Yabuzaki, T.

2003-04-01

95

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

Microsoft Academic Search

.   An all-diode-laser-based spectrometer is used for the simultaneous detection of methane, oxygen and water vapour. This is\\u000a accomplished using a 760-nm diode laser and a 980-nm diode laser in conjunction with difference-frequency generation to 3.4 ?m\\u000a in a periodically poled lithium niobate crystal. Each of the output wavelengths is resonant with one of the molecular species.\\u000a Simultaneous recordings over a

U. Gustafsson; J. Sandsten; S. Svanberg

2000-01-01

96

Collisions with Laser-Cooled, Metastable Helium Atoms  

Microsoft Academic Search

Laser manipulation techniques have been used to create a bright beam of metastable He(2^3S) atoms which is used, amongst other things, as a source of cold atoms for loading a 3-D magneto-optical trap of He(2^3S). The trapped atoms provide an ideal vehicle for collision studies including atom-atom and electron-atom collisions, both with and without resonant, or near-resonant laser fields present.

Stephen J. Buckman

2003-01-01

97

Analysis of Laser Beam Propagation Effects in Atomic Laser Isotope Separation  

Microsoft Academic Search

In the atomic laser isotope separation process, the laser beams propagate through the atomic vapor over a long distance. It has been shown that the laser-atom interactions significantly modify the laser pulse shape and propagation velocity, resulting in degradation of the isotope separation efficiency. These propagation effects have been analyzed quantitatively, and a simple scaling formula has been derived to

Yen-Wei Chen; Yasukazu Izawa; Sadao Nakai; Chiyoe Yamanaka

1995-01-01

98

Laser cooling and trapping of atomic mercury  

NASA Astrophysics Data System (ADS)

The level structure of the Hg atom is similar to other alkaline earth-like atoms, offering the possibility to realize an extremely high quality resonance factor (Q) on the ``clock'' transition (^1S0- ^3P0) when confined in an optical lattice at the Stark-shift free wavelength. A key feature of the Hg system is the reduced uncertainty due to black-body induced Stark shifts, making it an interesting candidate as an optical frequency standard. For cooling on the ^1S0- ^3P1 transition at 253.7 nm, we employ an optically pumped semiconductor laser (OPSEL) operating at 1015 nm. The OPSEL frequency is quadrupled, generating over 120 mW at 253.7 nm. With this laser source we have trapped Hg^199 from a background vapor in a standard MOT. We trap up to 2 x 10^6 atoms with a 1/e^2 radius of our MOT of ˜310 microns, corresponding to a density of 1.28 x10^11 atoms/cm^3. Using the time- of-flight method, we have measured a doppler-limited temperature of 46?K for the MOT. We have also generated 10 mW at the 266 nm clock transition using a frequency-quadrupled fiber laser. This light will be referenced to an iodine standard for assisting in high-precision spectroscopy of the ^1S0- ^3P0 transition. We present updated results on the MOT and the probe laser system.

Paul, Justin; Lytle, Christian; Jones, Jason

2011-10-01

99

Design for a compact CW atom laser  

NASA Astrophysics Data System (ADS)

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 x 0.5 mm wires carrying 5 A each embedded in a Si wafer; a 1.5 mm x 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.

Power, Erik; Raithel, Georg

2011-06-01

100

LETTERS TO THE EDITOR: Tunable pulse-periodic converter operating in the blue part of the spectrum and pumped by a copper vapour laser  

Microsoft Academic Search

Two-stage conversion of the radiation of a pulse- periodic copper vapour laser to the blue part of the spectrum was achieved experimentally. The average output power attained in such conversion was 400 mW for the 450 nm line when the pulse repetition frequency was 15625 Hz and the pulse duration was 50 ns. Bibtex entry for this abstract Preferred format

M. A. Kazaryan; Sergei V. Kruzhalov; Nikolai A. Lyabin; Yurii M. Mokrushin; V. A. Parfenov; A. M. Prokhorov; O. V. Shakin

1998-01-01

101

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

SciTech Connect

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)

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

102

Atomic - vapour - deposited HfO 2 and Sr 4Ta 2O 9 layers for metal-insulator-metal applications  

Microsoft Academic Search

Sr4Ta2O9 and HfO2 films were prepared on 200 mm TiN\\/Si(100) substrates by Atomic Vapour Deposition (AVD). Depositions were carried out within a thermal budget of CMOS back end of line. Electrical properties have been investigated in metal-insulator-metal capacitors after sputter deposition of Au top electrodes. Both Sr4Ta2O9 and HfO2 dielectrics show excellent electrical performances. Oxides possess high capacitance densities of

M. Lukosius; Ch. Wenger; T. Schroeder; J. Dabrowski; R. Sorge; I. Costina; H.-J. Müssig; S. Pasko; Ch. Lohe

2007-01-01

103

Recent applications and advances in laser manipulation of atoms  

Microsoft Academic Search

A series of experiments which owe their existence to advances in laser cooling and trapping of atoms will be presented. Emphasis will be given to the demonstration of an interferometer for atoms using laser cooled sodium atoms and the mechanical effects of velocity sensitive stimulated Raman transitions. This interferometer, configured as an accelerometer, was used to measure the acceleration due

Kasevich

1993-01-01

104

Diode pumped Nd:YGG laser for direct generation of pulsed 935 nm radiation for water vapour measurements  

NASA Astrophysics Data System (ADS)

A resonator setup applying a double-sided diode end-pumped configuration and an electro-optical Q-switch for efficient generation of 4 mJ pulses (< 60 ns fwhm) at 935 nm from Nd:YGG is presented, to our knowledge for the first time. The optical-optical efficiency is 9 % (absorbed pump light to laser out). High quality crystals have been investigated, showing high damage threshold, high efficiency and good optical properties permitting Q-switched mode of operation. Experimental small signal gain data coincide with spectroscopic measurements. For vapour detection frequency stable single mode operation is required. Injection seeding with a single frequency cw-signal has been successfully achieved. Frequency control mechanisms are currently under investigation. The direct generation of 935 nm radiation simplifies future LIDAR systems significantly compared to current approaches based on OPO, Raman or Ti:Sapphire technology.

Löhring, J.; Nicklaus, K.; Kujath, N.; Hoffmann, D.

2007-02-01

105

Single-frequency Nd:YGG laser at 935 nm for future water-vapour DIAL systems  

NASA Astrophysics Data System (ADS)

For future satellite based water vapour DIAL systems, efficient and rugged laser sources are required preferably around 935 nm. The quasi 4-level transition from R2 to Z5 in Nd:YGG is a promising candidate for its direct generation. Q-switch operation at 100 Hz with pulse energies up to 7.7 mJ is reported as well as single frequency operation with an injection seeded system stabilized by ramp-and-fire-method. The pulse energy of a 4.5 mJ oscillator was scaled to 32 mJ with an InnoSlab-based amplifier at nearly diffraction limited beam quality of M2 < 1.4. Heterodyne measurements show a line width of less than 28 MHz.

Löhring, Jens; Meissner, Ansgar; Morasch, Valentin; Becker, Peter; Heddrich, Wolfgang; Hoffmann, Dieter

2009-02-01

106

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

SciTech Connect

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

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

2012-11-30

107

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

NASA Astrophysics Data System (ADS)

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

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

2012-11-01

108

Control of atomic dynamics in laser-assisted electron-atom scattering through the driving-laser ellipticity  

NASA Astrophysics Data System (ADS)

Orders of magnitude increases of the cross sections are predicted for laser-assisted low-energy electron-atom scattering (accompanied by absorption of laser photons) as the laser ellipticity is increased. These ellipticity-controlled enhancements are manifestations of the field-free electron-atom scattering dynamics, such as the Ramsauer-Townsend effect in low-energy elastic electron-atom scattering. The strong sensitivity of laser-assisted scattering cross sections to this dynamics and the laser ellipticity is illustrated for e-Ne and e-Ar scattering in both midinfrared (?=3.5?m) and CO2 (?=10.6?m) laser fields of moderate intensities.

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

2013-03-01

109

Characterization of denatured metallothioneins by reversed phase coupled with on-line chemical vapour generation and atomic fluorescence spectrometric detection.  

PubMed

A new analytical hyphenated technique is proposed for determination and characterization of thiolic proteins, based on reverse phase chromatography (RPC) coupled on-line with cold vapour generation atomic fluorescence spectrometry (CVGAFS). Proteins are pre-column simultaneously denatured and derivatized in phosphate buffer solution containing 8.0 mol l(-1) urea and p-hydroxymercurybenzoate (PHMB). The derivatized proteins are separated on a C4 Vydac Reverse Phase column. Post-column on-line reaction of derivatized denatured proteins with bromine, generated in situ by KBr/KBrO3 in HCl medium, allowed the fast conversion of both the uncomplexed PHMB and of the PHMB bound to proteins to inorganic mercury, also in the presence of methanol in the RPC eluent phase. Hg(II) is selectively detected by AFS in a Ar/H2 miniaturized flame after sodium borohydride reduction to Hg degrees. Under optimized conditions, on-line bromine treatment gives a 98+/-2% recovery of both free and protein-complexed PHMB. The effect of methanol on the sensitivity of Hg(II) detection was studied and controlled. RPC-CVGAFS system has been applied to the analysis of metallothioneins from rabbit liver (MT(RL)) standard solutions, and their commercial isoforms MT-1 and MT-2. The analysis of denatured, PHMB-complexed MTs allowed the determination of the number of thiolic groups complexed by PHMB. It was found that MTs from rabbit liver have 10.0+/-0.3 (MT-1) and 6.7+/-0.3 (MT-2 and MT(RL)) -SH groups complexed by PHMB. The detection limit (LODc) for PHMB in 95% methanol in the optimized conditions was about 9.3 x 10(-9) mol l(-1) and for the denatured MTs LODc was about 8.6 x 10(-10) mol l(-1), taking into account an approximate complexating ratio PHMB:MTs of 7:1. PMID:15553155

Bramanti, Emilia; Lomonte, Cristina; Galli, Alvaro; Onor, Massimo; Zamboni, Roberto; Raspi, Giorgio; D'Ulivo, Alessandro

2004-10-29

110

Quantum theory of atomic motion in laser light  

Microsoft Academic Search

We review recent progress in the theory of the center-of-mass motion of atoms in laser light. The coherent and incoherent motion of cold atoms is analyzed for various interaction configurations. These configurations are designed to realize e.g. laser cooling down to the single photon recoil and localization of atoms in optical lattices. For conditions of negligible spontaneous emission atom optical

H. Wallis

1995-01-01

111

An improved model of gas temperature in a copper bromide vapour laser  

SciTech Connect

A new analytic model is proposed for calculating the temperature profile of gas in the transverse section of the discharge tube of copper bromide lasers emitting at 510.6 and 578.2 nm. The model is described by the quasi-stationary heat conduction equation with the boundary conditions of the third and fourth kinds taking into account the alternating volume electric power along the tube radius. The exact solution of the problem is obtained. The model was used to calculate the temperature profiles of the discharge in the case of natural and forced convection cooling. The obtained results are compared with previously known temperature distributions. The improved model proposed in the paper can be used to analyse existing lasers and develop new lasers. (lasers and amplifiers)

Iliev, I P [Department of Physics, Technical University of Plovdiv, Plovdiv (Bulgaria); Gocheva-Ilieva, S G [Department of Applied Mathematics and Modelling, Faculty of Mathematics and Informatics, Paisii Hilendarski University of Plovdiv (Bulgaria); Sabotinov, N V [Metal Vapour Lasers Department, Georgi Nadjakov Institute of Solid State Physics, Bulgarian Academy of Sciences, Sofia (Bulgaria)

2009-05-31

112

Production of neutral atoms by pulsed laser heating  

Microsoft Academic Search

Sodium and thallium surfaces were heated in vacuum by a short intense pulse from a CO2 TEA laser. The time-dependent emission of neutral atoms following the laser pulse was measured in the density range 1011–1012 atoms\\/cm3 by monitoring the absorption from a beam of resonance light. The temperature of the metal surface and the depth of heating after the laser

A. T. Prengel; J. Dehaven; E. J. Johnson; P. Davidovits

1977-01-01

113

Development of laser excited atomic fluorescence and ionization methods  

SciTech Connect

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.

Winefordner, J.D.

1991-01-01

114

Implantation of neutral atoms into liquid helium by laser sputtering  

Microsoft Academic Search

We have developed a new method for producing a high density of neutral atoms in liquid helium; laser sputtering within liquid helium. When we irradiate samples immersed in liquid helium with a pulsed laser, a large number of clusters are introduced into the liquid. When we further irradiate these clusters with an additional pulse laser, the clusters are sputtered and

A. Fujisaki; K. Sano; T. Kinoshita; Y. Takahashi; T. Yabuzaki

1993-01-01

115

Using a Mode-Locked Laser for Atomic Lifetime Measurements  

Microsoft Academic Search

We present a new technique for measuring atomic lifetimes, in which a single pulse from a mode-locked Ti:Sapphire laser excites atoms in a thermal beam to an excited state. A subsequent laser pulse is frequency-doubled and used to ionize any atoms remaining in the excited state, which are collected using a charged particle detector. The measurement is repeated using excitation

B. M. Patterson; G. Brooke; T. Takekoshi; R. J. Knize

2003-01-01

116

Mercury speciation by a high performance liquid chromatography—atomic fluorescence spectrometry hyphenated system with photo-induced chemical vapour generation reagent in the mobile phase  

Microsoft Academic Search

Speciation of mercury was accomplished by using a simple interface with photo-induced chemical vapour generation in a high\\u000a performance liquid chromatography—atomic fluorescence spectrometry (HPLC-AFS) hyphenated system. Acetic acid and 2-mercaptoethanol\\u000a in the mobile phase were used as photochemical reagent. The operating parameters were optimized to give limits of detection\\u000a of 0.53 µg L?1, 0.22 µg L?1, 0.18 µg L?1 and 0.25 µg L?1 for inorganic mercury, methylmercury, ethylmercury

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

2009-01-01

117

Correlations and Counting Statistics of an Atom Laser  

SciTech Connect

We demonstrate time-resolved counting of single atoms extracted from a weakly interacting Bose-Einstein condensate of {sup 87}Rb atoms. The atoms are detected with a high-finesse optical cavity and single atom transits are identified. An atom laser beam is formed by continuously output coupling atoms from the Bose-Einstein condensate. We investigate the full counting statistics of this beam and measure its second order correlation function g{sup (2)}({tau}) in a Hanbury Brown-Twiss type experiment. For the monoenergetic atom laser we observe a constant correlation function g{sup (2)}({tau})=1.00{+-}0.01 and an atom number distribution close to a Poissonian statistics. A pseudothermal atomic beam shows a bunching behavior and a Bose distributed counting statistics.

Oettl, Anton; Ritter, Stephan; Koehl, Michael; Esslinger, Tilman [Institute of Quantum Electronics, ETH Zuerich, Hoenggerberg, CH-8093 Zurich (Switzerland)

2005-08-26

118

Correlations and counting statistics of an atom laser.  

PubMed

We demonstrate time-resolved counting of single atoms extracted from a weakly interacting Bose-Einstein condensate of 87Rb atoms. The atoms are detected with a high-finesse optical cavity and single atom transits are identified. An atom laser beam is formed by continuously output coupling atoms from the Bose-Einstein condensate. We investigate the full counting statistics of this beam and measure its second order correlation function g((2))(tau) in a Hanbury Brown-Twiss type experiment. For the monoenergetic atom laser we observe a constant correlation function g((2))(tau)=1.00 +/- 0.01 and an atom number distribution close to a Poissonian statistics. A pseudothermal atomic beam shows a bunching behavior and a Bose distributed counting statistics. PMID:16197193

Ottl, Anton; Ritter, Stephan; Köhl, Michael; Esslinger, Tilman

2005-08-26

119

PHARAO space atomic clocks: new developments on the laser source  

NASA Astrophysics Data System (ADS)

The PHARAO project purpose is to open the way for a new atomic clock generation in space, where laser cooling techniques and microgravity allow high frequency stability and accuracy. The French space agency, CNES is funding and managing the clock construction. The French SYRTE and LKB laboratories are scientific and technical advisers for the clock requirements and the follow-up of subsystem development in industrial companies. EADS SODERN is developing two main subsystems of the PHARAO clock: the Laser Source and the Cesium Tube where atoms are cooled, launched, selected and detected by laser beams. The Laser Source includes an optical bench and electronic devices to generate the laser beams required. This paper describes PHARAO and the role laser beams play in its principle of operation. Then we present the Laser Source design, the technologies involved, and the status of development. Lastly, we focus of a key equipment to reach the performances expected, which is the extended Cavity Laser Diode.

Saccoccio, Muriel; Loesel, Jacques; Coatantiec, Claude; Simon, Eric; Laurent, Philippe; Lemonde, Pierre; Maksimovic, I.; Abgrall, M.

2004-06-01

120

Bessel beams of laser-driven two-level atoms  

NASA Astrophysics Data System (ADS)

We study Bessel beams of two-level atoms that are coupled to a linearly polarized laser field. For such atom beams, we construct exact Bessel-type solutions of the Schrödinger equation beyond the paraxial approximation for beam propagation. In particular, we examine the probability density for Bessel beams of neutral two-level atoms driven by a laser field but without the level damping being taken into account. We show how the radial dependence of the probability density (from the beam axis) can be affected by tuning the parameters of the atom-laser system, such as the resonant frequency and amplitude of the laser field and/or the nuclear charge and velocity of the atomic beam.

Hayrapetyan, A. G.; Fritzsche, S.

2013-09-01

121

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

NASA Astrophysics Data System (ADS)

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.

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

2009-08-01

122

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)

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.

Zhang, Wen-Tao; Zhu, Bao-Hua

2009-07-01

123

Laser-Enabled Auger Decay in Rare-Gas Atoms  

SciTech Connect

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

Ranitovic, P.; Hogle, C. W.; Zhou, X.; Murnane, M. M.; Kapteyn, H. C. [JILA and Department of Physics, University of Colorado and NIST, Boulder, Colorado 80309-0440 (United States); 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); Liu, Y. [College of Engineering, University of California at Berkeley, California 94720 (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)

2011-02-04

124

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)

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.

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

1995-02-01

125

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

NASA Astrophysics Data System (ADS)

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.

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

2011-09-01

126

Laser Induced Fluorescence Measurements on Atoms with Low Energies.  

National Technical Information Service (NTIS)

In recent measurements of velocity spectra of sputtered atoms using the Doppler-shift laser fluorescence spectrosocopy several problems have been encountered concerning the interpretation of the obtained fluorescence spectra. Essential to the interpretati...

K. Thomsen

1982-01-01

127

Atomic Fluorescence Using a Tunable Flashlamp Pumped Dye Laser.  

National Technical Information Service (NTIS)

Determination of analytical calibration curves for the atomic fluorescence of sodium vapor is described. A tunable flashlamp pumped Rhodamine 6G dye laser was used as the excitation source. The sample cell consisted of an evacuated quartz tube containing ...

H. L. Brod

1975-01-01

128

Production of neutral atoms by pulsed laser heating  

Microsoft Academic Search

Sodium and thallium surfaces were heated in vacuum by a short intense pulse from a CO2 TEA laser. The time-dependent emission of neutral atoms following the laser pulse was measured in the density range 10 to the 11th to 10 to the 12th atoms\\/cu cm by monitoring the absorption from a beam of resonance light. The temperature of the metal

A. T. Prengel; J. Dehaven; E. J. Johnson; P. Davidovits

1977-01-01

129

Output from an atom laser: theory vs. experiment  

Microsoft Academic Search

.   Atom lasers based on rf-outcoupling can be described by a set of coupled generalized Gross–Pitaevskii equations (GPE). We\\u000a compare the theoretical predictions obtained by numerically integrating the time-dependent GPE of an effective one-dimensional\\u000a model with recently measured experimental data for the F=2 and F=1 states of Rb-87. We conclude that the output of a rf atom-laser can be described

Jens Schneider; Axel Schenzle

1999-01-01

130

Theoretical tools for atom-laser-beam propagation  

Microsoft Academic Search

We present a theoretical model for the propagation of non-self-interacting atom laser beams. We start from a general propagation integral equation and we use the same approximations as in photon optics to derive tools to calculate the atom-laser-beam propagation. We discuss the approximations that allow one to reduce the general equation whether to a Fresnel-Kirchhoff integral calculated by using the

J.-F. Riou; Y. Le Coq; F. Impens; W. Guerin; C. J. Bordé; A. Aspect; P. Bouyer

2008-01-01

131

Probing Molecules with Laser-Cooled Atomic Ions  

NASA Astrophysics Data System (ADS)

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

Brown, Kenneth R.

2012-06-01

132

Laser manipulation of atomic and molecular flows  

Microsoft Academic Search

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

Taylor C. Lilly

2010-01-01

133

Theory of Auger decay by laser-dressed atoms  

Microsoft Academic Search

We devise an ab initio formalism for the quantum dynamics of Auger decay by laser-dressed atoms which are inner-shell ionized by extreme ultraviolet (xuv) light. The optical dressing laser is assumed to be sufficiently weak such that ground-state electrons are neither excited nor ionized by it. However, the laser has a strong effect on continuum electrons which we describe in

Christian Buth; Kenneth J. Schafer

2009-01-01

134

Optical dipole traps for cold atoms using diffracted laser light  

SciTech Connect

We theoretically investigate the feasibility of using intensity distributions of light of a single laser beam diffracted by a circular aperture as optical dipole traps for cold neutral atoms. Localized and cylindrically symmetric traps on the central axis of the circular aperture exist for both blue- and red-detuned laser light. Experimental mapping of the spots of interest using CO{sub 2} laser light demonstrates the existence of these light distributions for laboratory conditions and their agreement with theoretical predictions.

Gillen, Glen D.; Guha, Shekhar; Christandl, Katharina [Air Force Research Laboratory, Materials and Manufacturing Directorate, Wright-Patterson Air Force Base, Dayton, Ohio 45433 (United States); Department of Physics, Ohio State University, Columbus, Ohio 43210 (United States)

2006-01-15

135

Atomic\\/Molecular-Level Simulations of Laser–Materials Interactions  

Microsoft Academic Search

Molecular\\/atomic-level computer modeling of laser–materials interactions is playing an increasingly important role in the\\u000a investigation of complex and highly nonequilibrium processes involved in short-pulse laser processing and surface modification.\\u000a This chapter provides an overview of recent progress in the development of computational methods for simulation of laser interactions\\u000a with organic materials and metals. The capabilities, advantages, and limitations of the

Leonid V. Zhigilei; Zhibin Lin; Dmitriy S. Ivanov; Elodie Leveugle; William H. Duff; Derek Thomas; Carlos Sevilla; Stephen J. Guy

136

Velocity distribution of the yttrium atoms in laser produced plasma  

Microsoft Academic Search

We have investigated the velocity distribution functions of atoms in laser produced plasma. In our experiments plasma is cheated during the laser sputtering of YBa2Cu3O7-x ceramics target. We used KrF excimer laser for target sputtering. All sputtering conditions that were the same as usual for high Tc films deposition are used. We used time-of-flight method to investigate the velocity distribution

Alexander N. Zherikhin; Oleg V. Boyarkin; Vladimir N. Burimov; Vladimir S. Golubev; Valerie L. Popkov

1994-01-01

137

Laser Induced Fluorescence Spectroscopy in Atomic Beams of Radioactive Nuclides.  

National Technical Information Service (NTIS)

Measurements of the resonant scattering of light from CW tunable dye lasers, by a well collimated atomic beam, enable hyperfine splittings and optical isotope shifts to be determined with high precision and high sensitivity. Recent off-line atomic beam ex...

H. Rebel G. Schatz

1982-01-01

138

Strongly driven one-atom laser and decoherence monitoring  

NASA Astrophysics Data System (ADS)

We propose the implementation of a strongly driven one-atom laser, based on the off-resonant interaction of a three-level atom in ? 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 (Schrödinger 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.

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

2007-09-01

139

Laser-Raman spectroscopic study of the vapour phase equilibria above molten SnCl 2  

NASA Astrophysics Data System (ADS)

Raman spectra of the gaseous phase of SnCl 2 are reported over the temperature range 666 K to 1047 K. The development of a furnace designed for optical studies at temperatures up to 1100 K is described. Agreement with previous Raman studies is excellent and in addition new features are observed which are attributed to the dimeric species Sn 2Cl 4. Extensive force constant calculations have been carried out to establish the structure of this molecule. The results show that the dimer molecule has Cs-symmetry with one bridging chlorine atom. The enthalpy of formation of Sn 2Cl 4 has been calculated using second-law methods, and is in agreement with a previous result from mass spectrometry. Predicted vibrational band wavenumbers from force constant calculations are used to calculate values of the heat capacity C p?, the enthalpy H T? - H 298?, and the entropy S T? - S 0? of Sn 2Cl 4 from 0 K to 6000 K. The molten phase of SnCl 2 has also been examined.

Fields, M.; Devonshire, R.; Edwards, H. G. M.; Fawcett, V.

1995-11-01

140

Atom dynamical dissipation in the laser cavity with quasimode  

NASA Astrophysics Data System (ADS)

In this paper we study the atom dissipation effect in a laser cavity. The cavity field mode is described by the Fox—Li quasimode due to the leakiness of the cavity. Our results show that the atom decay rate versus the decay rate of the quasimode is a Lorentz type. Effects of the atom—cavity detuning as well as cavity size are also discussed.

Jiang, Wen-Ying; Zhao, Zhi-Min; Tian, Tian; Zheng, Li; Zheng, Tai-Yu

2013-06-01

141

Laser cooling of a magnetically guided ultra cold atom beam  

Microsoft Academic Search

We report on the transverse laser cooling of a magnetically guided beam of\\u000aultra cold chromium atoms. Radial compression by a tapering of the guide is\\u000aemployed to adiabatically heat the beam. Inside the tapered section heat is\\u000aextracted from the atom beam by a two-dimensional optical molasses\\u000aperpendicular to it, resulting in a significant increase of atomic phase space

Anoush Aghajani-Talesh; Markus Falkenau; Valentin V. Volchkov; Leah E. Trafford; Tilman Pfau; Axel Griesmaier

2010-01-01

142

PARCS: NASA's laser-cooled atomic clock in space  

Microsoft Academic Search

The Primary Atomic Reference Clock in Space (PARCS) mission is designed to perform certain tests of relativity theory, to study the performance of individual GPS space-vehicle clocks, to study the dynamics of atom motion in microgravity, to advance the state-of-the art for space clocks, and to serve as a pathfinder for precision instruments based on laser cooling of atoms. After

D. B. Sullivan; N. Ashby; E. A. Donley; T. P. Heavner; L. W. Hollberg; S. R. Jefferts; W. M. Klipstein; W. D. Phillips; D. J. Seidel

2005-01-01

143

LASERS: Low-threshold short-cavity diode laser for a miniature atomic clock  

NASA Astrophysics Data System (ADS)

Short-cavity diode lasers (SCDLs) emitting at the 894-nm D1 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.

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

2009-06-01

144

Probing a Bose-Einstein condensate with an atom laser.  

PubMed

A pulsed atom laser derived from a Bose-Einstein condensate is used to probe a second target condensate. The target condensate scatters the incident atom laser pulse. From the spatial distribution of scattered atoms, one can infer important properties of the target condensate and its interaction with the probe pulse. As an example, we measure the s-wave scattering length that, in low energy collisions, describes the interaction between the |F = 1,m(F) = -1) and |F = 2,m(F) = 0) hyperfine ground states in (87)Rb. PMID:18773000

Döring, D; Robins, N P; Figl, C; Close, J D

2008-09-01

145

Bragg diffraction of an atom laser by an optical standing wave  

SciTech Connect

We derive the exact explicit analytical expressions of incident and diffracted atom lasers and their difference in phase from the Bragg diffraction of an atom laser from an optical standing wave in the presence of two-body atomic interactions. These expressions demonstrate that two-body atomic interactions may significantly affect the Bragg diffraction of an atom laser from an optical standing wave, and they provide a convenient basis for discussing and designing the future Bragg devices of strong atom lasers.

Wu Ying; Yang Xiaoxue [Department of Physics and National Key Laboratory for Laser Technique, Huazhong University of Science and Technology, Wuhan 430074 (China); School of Physics Science and Information Technology, Liaocheng University, Liaocheng, Shandong 252059 (China); Department of Physics, Huazhong University of Science and Technology, Wuhan 430074 (China)

2006-05-15

146

Laser action of optically pumped atomic vanadium vapor  

NASA Astrophysics Data System (ADS)

Vanadium vapor is generated from a vanadium metal by irradiation of a pulsed YAG laser of 2.2 J energy, and the vanadium atoms are optically pumped by a XeCl laser of 7.3 mJ energy. Laser action has been observed on the vanadium 409.5 nm 4F(7/2)-4D(5/2) transition. This laser pulse has a pulse width of 4 ns and peak power of 1.08 W, and the optical gain is 0.46/cm.

Ninomiya, H.; Abe, M.; Takashima, N.

1991-04-01

147

Collisions with Laser-Cooled, Metastable Helium Atoms  

NASA Astrophysics Data System (ADS)

Laser manipulation techniques have been used to create a bright beam of metastable He(2^3S) atoms which is used, amongst other things, as a source of cold atoms for loading a 3-D magneto-optical trap of He(2^3S). The trapped atoms provide an ideal vehicle for collision studies including atom-atom and electron-atom collisions, both with and without resonant, or near-resonant laser fields present. This talk will review the motivation for such studies and discuss the techniques which we use to create a cold ( 300 mK), dense ( 10^8 atoms/cc) cloud of trapped, excited He atoms. Experimental results for total electron scattering cross sections from He(2^3S) at energies between 5 and 100 eV will be presented, as will results of scattering from He(2^3P) atoms, formed in the trap by optical pumping of the 2^3S atoms at 1083 nm.

Buckman, Stephen J.

2003-10-01

148

Laser cooling and trapping of atoms  

SciTech Connect

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

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

1987-09-25

149

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

NASA Astrophysics Data System (ADS)

This paper studies the multiphoton ionization of the hydrogen atom exposed to the linearly or circularly polarized laser pulses by solving the time-dependent Schrödinger 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.

Wang, Pei-Jie; He, Feng

2009-12-01

150

REVIEW ARTICLE: Towards a random laser with cold atoms  

NASA Astrophysics Data System (ADS)

Atoms can scatter light and they can also amplify it by stimulated emission. From this simple starting point, we examine the possibility of realizing a random laser in a cloud of laser-cooled atoms. The answer is not obvious as both processes (elastic scattering and stimulated emission) seem to exclude one another: pumping atoms to make them behave as an amplifier drastically reduces their scattering cross-section. However, we show that even the simplest atom model allows the efficient combination of gain and scattering. Moreover, the supplementary degrees of freedom that atoms offer allow the use of several gain mechanisms, depending on the pumping scheme. We thus first study these different gain mechanisms and show experimentally that they can induce (standard) lasing. We then present how the constraint of combining scattering and gain can be quantified, which leads to an evaluation of the random laser threshold. The results are promising and we draw some prospects for a practical realization of a random laser with cold atoms.

Guerin, W.; Mercadier, N.; Michaud, F.; Brivio, D.; Froufe-Pérez, L. S.; Carminati, R.; Eremeev, V.; Goetschy, A.; Skipetrov, S. E.; Kaiser, R.

2010-02-01

151

Interaction of Intense laser Pulses with Ultra-cold Atoms  

NASA Astrophysics Data System (ADS)

The recent development of laser cooling and trapping techniques has made possible the controlled realization of dense and cold atomic samples, thus opening the way for spectroscopic investigations in the low and ultra-low temperature regimes not accessible with conventional techniques. In our lab, an apparatus for laser cooling and Bose-Einstein condensation of rubidium atoms is in operation, producing a sample large enough to perform reliable investigations by absorption or emission techniques. Moving from previous photoionization experiments of laser-cooled atoms in a magneto-optical trap irradiated by cw-laser radiation [1] and stimulated by the interest grown recently on ultra-cold plasma [2], we have started a series of experiments aimed at investigating the interaction of intense laser pulses with the ultra-cold neutral sample, boty aboeand below the condensation temperature. Radiation from an excimer-pumped dye laser was used at a wavelength close to 594 nm, corresponding to the ionization threshold of rubidium for two photon non-resonant absorption from the ground state, with intensities in the tens of MW/cm^2 range and a pulse duration of 16 ns. Preliminary results, attained through the dynamical analysis (atom number, temperature) of the cold atom sample after the arrival of the laser pulse, suggest the occurrence of different processes, initiated by multi-photon ionization, involving collisions between cold electrons and ultra-cold neutrals, recombination at low temperatures and collective processes in the weak and cold plasma. Interpretation of those results demonstrates that this class of experiments, based on a variety of topics typical of atomic, plasma and statistical physics, can open the way for novel and intriguing investigations of laser-matter interaction. Further experimental developments will include duplication of the laser pulse frequency and one photon ionization of ground state rubidium laser-cooled atoms. [1] O. Maragò et al., Phys. Rev. A 57 R4110 (1998); E., Arimondo et al., Appl. Surf. Sci. 154-155 527 (2000); F. Fuso et al., Opt. Commun. 173 223 (2000). [2] T.C. Killian et al., Phys. Rev. Lett. 83 4776 (1999); S. Kulin et al., Phys. Rev. Lett. 85 318 (2000).

Ciampini, Donatella; Fuso, Francesco; Mûller, Jorg H.; Anderlini, Marco; Morsch, Oliver; Arimondo, Ennio

2001-05-01

152

Theory of a single-atom laser including light forces  

SciTech Connect

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

Salzburger, Thomas; Ritsch, Helmut [Institute for Theoretical Physics, University of Innsbruck, A-6020 Innsbruck, Technikerstrae 25/2 (Austria); Domokos, Peter [Research Institute for Solid State Physics and Optics, P.O. Box 49, H-1525 Budapest (Hungary)

2005-09-15

153

Laser particle acceleration: Pushing atoms with light  

NASA Astrophysics Data System (ADS)

Controlling the velocity of neutral particles is an experimental challenge, owing to their absence of charge. Scientists have now demonstrated a technique that can be used to accelerate neutral argon atoms by polarizing them in moving optical lattices.

Osterwalder, Andreas

2012-06-01

154

Polarization switching with sodium vapour  

SciTech Connect

Results are given of an experiment which demonstrates switching of the polarization state of the output of a near-concentric Fabry-Perot containing sodium vapour, excited via the homogeneously broadened Dl transition. An example of the output, for linearly polarized laser input, at 1.5 GHz below line center shows switching with hysteresis at high input power (approximately 400 mW) due to saturation, as well as the switching at lower power (approximately mW) due to optical pumping effects. Purely absorptive polarization switching at approximately 50 mW input power was observed. Polarization switching has been predicted in the context of three state atoms in an optical cavity, and the lower power switchin has been previously observed using the inhomogeneously broadened Dl transition of sodium in a Fabry-Perot with the laser detuned above line center. By using argon buffer gas at up to 100 torr, importance of hyperfine structure and inhomogeneous broadening was reduced so as to make the transition approximate a J + 1/2 to J - 1/2 transition.

Hamilton, M.W.; Sandle, W.J.

1984-01-01

155

Laser-assisted elastic electron-atom collisions  

Microsoft Academic Search

We report experimental measurements of electron spectra resulting from the scattering of 9.5-eV electrons by helium atoms through an angle of 9° in the presence of a high-intensity (~108 W cm-2) CO2 laser. The intensities of the additional peaks which occur separated from the elastic scattering peak by multiples of the photon energy in the presence of the laser are

B. Wallbank; J. K. Holmes

1993-01-01

156

Ionization of atomic hydrogen in strong infrared laser fields  

Microsoft Academic Search

We have used the matrix iteration method of Nurhuda and Faisal [Phys. Rev. A 60, 3125 (1999)] to treat ionization of atomic hydrogen by a strong laser pulse. After testing our predictions against a variety of previous calculations, we present ejected-electron spectra as well as angular distributions for few-cycle infrared laser pulses with peak intensities of up to 10¹⁵ W\\/cm².

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

2010-01-01

157

A Theory of Laser Induced Nuclear Reaction in Single Atoms  

SciTech Connect

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

Faisal, F. H. M.; Donner, C. [Fakultaet fuer Physik, Universitaet Bielefeld, Postfach 100131, D-33501 Bielefeld (Germany)

2010-02-02

158

Search for electron EDM with laser cooled radioactive atom  

NASA Astrophysics Data System (ADS)

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

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

2013-05-01

159

Continuous beam of laser-cooled Yb atoms  

NASA Astrophysics Data System (ADS)

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

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

2013-05-01

160

Bowls made of Laser Light to Corral Ultracold Atoms  

NASA Astrophysics Data System (ADS)

Using stable lasers, it is now possible to create nearly perfect bowls made of pure light, which are smaller than a piece of lint and store atoms for several minutes in an ultrahigh vacuum environment. These almost frictionless bowls are ideal for cooling atoms by evaporation, the same way that alcohol cools the skin. In just a few seconds, atoms trapped in the bowl are cooled to temperatures of ten of billionths of a degree above absolute zero, where the de Broglie wavelength is several microns. These ultracold atoms occupy the quantum energy levels of the bowl, producing a giant quantum system that can be directly observed using laser flash photography. I will describe our laser trapping methods and show how they can be use to study a unique quantum gas of spin-up and spin-down ^6Li atoms, which are fermions that obey the Pauli exclusion principle. I will describe how this ultracold atomic gas now tests predictions in nearly all fields of physics, from high temperature superconductors to neutron stars, the quark-gluon plasma of the Big Bang, and even string theory.

Thomas, John

2010-10-01

161

Sub-Doppler laser cooling of potassium atoms  

SciTech Connect

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

Landini, M. [LENS and Dipartimento di Fisica e Astronomia, Universita di Firenze, I-50019 Sesto Fiorentino (Italy); INFN, Sezione di Firenze, I-50019 Sesto Fiorentino (Italy); Dipartimento di fisica, Universita di Trento, I-38123 Povo (Trento) (Italy); Roy, S.; Carcagni, L.; Trypogeorgos, D. [LENS and Dipartimento di Fisica e Astronomia, Universita di Firenze, I-50019 Sesto Fiorentino (Italy); Fattori, M.; Inguscio, M.; Modugno, G. [LENS and Dipartimento di Fisica e Astronomia, Universita di Firenze, I-50019 Sesto Fiorentino (Italy); INFN, Sezione di Firenze, I-50019 Sesto Fiorentino (Italy)

2011-10-15

162

Sub-Doppler laser cooling of potassium atoms  

NASA Astrophysics Data System (ADS)

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

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

2011-10-01

163

Optical mask for laser-cooled atoms  

SciTech Connect

An optical mask is a standing wave of light in resonance with an open atomic transition. The mask depletes the population of the initial internal state everywhere except in a narrow vicinity of the nodes. We have experimentally explored the optical mask as a tool for creating a periodic pattern in the density of cold rubidium atoms (in a particular hyperfine ground state) and also as an instrument for imaging the density in situ. The instrumental width of the imaging technique is a small fraction of the optical wavelength and is limited due to an effect of the dipole force rather than the initial velocity spread.

Turlapov, Andrey; Tonyushkin, Alexei; Sleator, Tycho [Department of Physics, New York University, 4 Washington Place, New York, New York 10003, USA (United States)

2003-08-01

164

Controlling atomic structures and photoabsorption processes by an infrared laser  

SciTech Connect

We propose a theoretical method to calculate the infrared (IR) laser-assisted photoabsorption cross sections over a broad energy range by a single calculation. In this method we define an initial wave function as the product of the dipole operator and the atomic ground state, propagate the initial wave function in the IR laser field with different initial phases, then calculate the generalized autocorrelation function, which is defined as the averaged value of the autocorrelation function over the initial phase from 0 to 2{pi} (or one IR optical cycle). The IR laser-assisted photoabsorption cross sections are obtained by the Fourier transform of the generalized autocorrelation function. We apply this method to study the IR laser-assisted photoabsorption of He atoms. From the simulation results, we see that the IR laser field affects not only the resonant position but also the lifetime or the width of the bound states. This photoabsorption cross section is an important quantity to analyze the IR-laser-assisted dynamical processes by an attosecond pulse, a pulse train, or a free-electron laser.

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); 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)

2010-06-15

165

Numerical study of femtosecond laser-assisted atom probe tomography  

NASA Astrophysics Data System (ADS)

We investigate the mechanisms of a laser-assisted atom probe tomography technique. In this method, a sub-wavelength tip is subjected both to a very strong static electric field and to a femtosecond laser pulse. As a result, ions are ejected from the tip one by one. By using femtosecond lasers, one can analyze not only metals but also semiconductors and dielectric materials. To better understand the ejection process, a numerical model is developed based on the drift-diffusion approach. The model accounts for such effects as field penetration, hole and electron movement, and laser absorption. For the given value of the dc field, a substantial band bending and an increase in hole density at the surface of the silicon tip are observed. This bending effect changes silicon absorption coefficient at the surface and significantly increases recombination time of laser-induced carriers.

Silaeva, E. P.; Shcheblanov, N. S.; Itina, T. E.; Vella, A.; Houard, J.; Sévelin-Radiguet, N.; Vurpillot, F.; Deconihout, B.

2013-03-01

166

Atomic spectroscopy with laser and synchrotron radiation.  

National Technical Information Service (NTIS)

Oxygen and nitrogen atoms which play a crucial role in many chemical processes are studied with photoelectron spectroscopy. In the case of oxygen, synchrotron radiation is employed to study the inner-valence excitation region between 20 and 30 eV and deta...

P. van de Meulen E. de Beer C. A. de Lange N. P. C. Westwood M. O. Krause

1991-01-01

167

Investigation of shadow effect in laser-focused atomic deposition  

NASA Astrophysics Data System (ADS)

The feature width broadening and height increasing of the Cr nanostructure have been experimentally observed in the gradual atom flux distribution divergent area on one sample along the standing wave direction in laser-focused atomic deposition. By applying an optimized ballistic deposition surface growth model to simulate this situation, it is demonstrated that the shadow effect of the forming nanostructure influences the deposition sites of the subsequent incident atoms, which leads to feature broadening and contrast decreasing of the nanostructures. The shadow effect theory provides a new understanding for the explanation of the discrepancy between the calculated results and the experimental observations.

Deng, Xiao; Ma, Yan; Zhang, Pingping; Zhang, Wanjing; Chen, Sheng; Xiao, Shengwei; Li, Tongbao

2012-11-01

168

Atomic and Molecular Systems in Intense Ultrashort Laser Pulses  

Microsoft Academic Search

The full quantum mechanical treatment of atomic and molecular systems exposed to intense laser pulses is a so far unsolved challenge, even for systems as small as molecular hydrogen. Therefore, a number of simplified qualitative and quantitative models have been introduced in order to provide at least some interpretational tools for experimental data. The assessment of these models describing the

A. Saenz

2008-01-01

169

Picosecond phase conjugation by degenerate four wave mixing in alkali vapours - A method for measuring perturbation times of the atomic wavefunctions  

NASA Astrophysics Data System (ADS)

Phase conjugated waves via degenerate four wave mixing with picosecond laser pulses having a FWHM of 80 ps have been observed in alkali vapors. The dephasing time of the 2P(3/2) state in sodium was found to be 7.4 ns. This is the lifetime of the transient volume grating of the atomic states which are involved in the phase conjugated experiment. The average time of the perturbation of the atomic wave functions due to a 'hot' collision (from a frequency modulation of a Markov type) was found to be 5 x 10 to the -14th sec.

Cefalas, A. C.; Spyrou, S.; Nicolaides, C. A.

1989-06-01

170

Heteronuclear collisions between laser-cooled metastable neon atoms  

NASA Astrophysics Data System (ADS)

We investigate heteronuclear collisions in isotope mixtures of laser-cooled metastable (3P2) neon. Experiments are performed with spin-polarized atoms in a magnetic trap for all two-isotope combinations of the stable neon isotopes 20Ne, 21Ne, and 22Ne. We determine the rate coefficients for heteronuclear ionizing collisions to ?21,20=(3.9±2.7)×10-11 cm3/s, ?22,20=(2.6±0.7)×10-11 cm3/s, and ?21,22=(3.9±1.9)×10-11 cm3/s. We also study heteronuclear elastic collision processes and give upper bounds for heteronuclear thermal relaxation cross sections. This work significantly extends the limited available experimental data on heteronuclear ionizing collisions for laser-cooled atoms involving one or more rare gas atoms in a metastable state.

Schütz, Jan; Feldker, Thomas; John, Holger; Birkl, Gerhard

2012-08-01

171

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

SciTech Connect

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)

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

172

Extreme Ultraviolet Laser Excites Atomic Giant Resonance  

SciTech Connect

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

Richter, M. [Physikalisch-Technische Bundesanstalt, Abbestrasse 2-12, 10587 Berlin (Germany); Amusia, M. Ya.; Bobashev, S. V. [Ioffe Physico-Technical Institute, Polytekhnicheskaya 26, 194021 St. Petersburg (Russian Federation); Feigl, T. [Fraunhofer-Institut fuer Angewandte Optik und Feinmechanik, Albert-Einstein-Strasse 7, 07745 Jena (Germany); Juranic, P. N.; Tiedtke, K. [Deutsches Elektronen-Synchrotron, Notkestrasse 85, 22603 Hamburg (Germany); Martins, M. [Universitaet Hamburg, Institut fuer Experimentalphysik, Luruper Chaussee 149, 22761 Hamburg (Germany); Sorokin, A. A. [Physikalisch-Technische Bundesanstalt, Abbestrasse 2-12, 10587 Berlin (Germany); Ioffe Physico-Technical Institute, Polytekhnicheskaya 26, 194021 St. Petersburg (Russian Federation)

2009-04-24

173

Laser separation of uranium chosen for scaleup. [Atomic vapor laser isotope separation, molecular laser isotope separation plasma separation process  

Microsoft Academic Search

Atomic vapor laser isotope separation (AVLIS) has been selected by the Department of Energy to go into large-scale engineering development and demonstration over two other advanced technologies, molecular laser isotope separation and plasma separation. DOE will continue to support development of another uranium enrichment technology, gas centrifugation. By or around 1990, the most promising gas centrifuge technique will be compared

Rawls

1982-01-01

174

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

NASA Astrophysics Data System (ADS)

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

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

1990-08-01

175

Laser cooling of a magnetically guided ultracold atom beam  

NASA Astrophysics Data System (ADS)

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

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

2010-06-01

176

Laser cooling of cesium atoms below 3 microkelvins  

SciTech Connect

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

Salomon, C.; Dalibard, J.; Phillips, W.D. (Laboratoire de Spectroscopie Hertzienne (Unite de recherche de l'Ecole Normale Superieure et de l Universite Paris 6, associee au CNRS-U.R.A. 18), Departement de Physique de l ENS, 24 rue Lhomond, F-75231 Paris Cedex 05 (France)); Clairon, A. (Laboratoire Primaire du Temps et Frequences, 61 avenue de l'Observatoire, 75014 Paris (France)); Guellati, S. (Laboratoire Aime Cotton, Batiment 505, 91405 Orsay (France))

1991-08-05

177

Harmonic generation by laser-driven classical hydrogen atoms  

SciTech Connect

We present the results of our investigations of the dynamics of a classical hydrogen atom submitted to an intense classical radiation field with a relatively low frequency as compared to the characteristic Kepler frequency of the atomic system. We discuss here the harmonic spectra which can be deduced from a Fourier analysis of the time evolution of the strongly driven atomic dipole, associated either with a single trajectory or with ensembles of trajectories evolving from an initial microcanonical distribution. The spectra obtained from ensemble-averaged atomic dipoles qualitatively reproduce the main features of those recently observed in experiments and allow, in particular, discussion of the occurrence of a plateau in the distribution of harmonic intensities as a function of their order. The possible competition between harmonic generation and multiphoton ionization, which both take place in the same laser-intensity range, is also discussed.

Bandarage, G. (Department of Chemistry, Texas A M University, College Station, Texas 77843-3255 (United States)); Maquet, A.; Menis, T.; Taieeb, R.; Veniard, V. (Laboratoire de Chimie Physique, Universite Pierre et Marie Curie, 11 Rue Pierre et Marie Curie, F75231 Paris CEDEX 05 (France)); Cooper, J. (Joint Insitute for Laboratory Astrophysics and National Institute of Standards and Technology, University of Colorado, Boulder, Colorado 80309-0440 (United States))

1992-07-01

178

Metastable atoms in gasdynamic and atomic beams: Velocity distribution and state density by laser diagnostics  

SciTech Connect

The velocity distributions and state densities of metastable Ca(4s4p /sup 3/P/sub 2/) atoms emerging from discharge beam sources were measured by probing the Doppler shift in laser induced fluorescence. In order to cover the widely spread distribution of the longitudinal velocity component a single-mode dye laser was used in mode hopping technique. In this way up to 4 A can be covered in steps of 182 MHz distance. The longitudinal and transverse components are sampled simultaneously. For the gasdynamic jet the transfer velocities were measured from some 10 m/s up to supersonic values. Using the transverse laser beam the absorption caused by Ca in the /sup 3/P/sub 2/ state was tested. Absorptions up to 0.995 could be achieved in the free jet. A /sup 3/P density of 7 x 10/sup 11/ cm/sup -3/ is calculated. Similarly for the atomic beam 2 x 10/sup 10/ cm/sup -3/ is found, the flux being 4.7 x 10/sup 15/ metastable atoms/s sr. Details of the atomic beam source for metastable atoms are given.

Brinkmann, U.; Kluge, J.; Pippert, K.

1980-09-01

179

Atomic mass dependent electrostatic diagnostics of colliding laser plasma plumes  

NASA Astrophysics Data System (ADS)

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.

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

2013-09-01

180

Gauge Structures in Atom-Laser Interaction: Bloch Oscillations in a Dark Lattice  

Microsoft Academic Search

Atoms in dark atomic ground states do not interact with the laser light present and are therefore not susceptible to spontaneous processes. Laser cooling populates these states. Confinement of atoms in dark states in a (periodic) gauge potential allows for a lattice of atoms with a very low decay rate, a dark lattice. A dark lattice is a promising system

R. Dum; M. Olshanii

1996-01-01

181

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

Microsoft Academic Search

Photo-induced chemical vapour generation (CVG) with formic acid in mobile phase as reaction reagent was developed as interface to on-line couple HPLC with atomic fluorescence spectrometry for the separation and determination of inorganic mercury, methylmercury (MeHg), ethylmercury (EtHg) and phenylmercury (PhHg). In the developed procedure, formic acid in mobile phase was used to decompose organomercuries and reduce Hg2+ to mercury

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

2008-01-01

182

Atomic laser action in rare gas-SF6mixtures  

Microsoft Academic Search

Pulsed-laser action is described on a number of atomic transitions of ArI, one of which has not been reported previously. The addition of SF6to Ar shifts the laser action in the Ar from the3d'(3\\/2)min{1}max{0} - 4p'(1\\/2)_{1}transition to six ArI transitions originating from the three lowest states of the3p^{5}3delectron configuration. Significant enhancement of the intensity is observed over that resulting from

D. Sutton; L. Galvan; P. Valenzuela; S. Suchard

1975-01-01

183

Pulsed laser gates for trapped atomic qubits  

NASA Astrophysics Data System (ADS)

Current experimental techniques for entangling multiple trapped ion qubits via the quantized modes of motion are inherently limited in speed and thus sensitive to many sources of noise. We use high power mode-locked lasers to perform ultrafast qubit operations via stimulated Raman transitions. We show that complete control over the spin state of a single qubit can be accomplished in tens of picoseconds by splitting a single pulse and varying the delay [1]. We also investigate improvements to the fidelity of current protocols using a weak pulse train at a large (33 THz) detuning [2]. Future work will focus on generating entangling gates on timescales faster than a motional period, by tailoring the ions' motional evolution with pulse sequences of varying Rabi frequency [3] or using spin-dependent momentum kicks fashioned from a few strong pulses [4,5]. [1] W.C. Campbell et al., PRL 105, 090502 (2010) [2] D. Hayes et al., PRL 104, 140501 (2010) [3] S.-L. Zhu et al., Europhys. Letters 73, 485 (2006) [4] J.J. Garcia-Ripoll et al., PRL 91, 157901 (2003) [5] L.-M. Duan, PRL 93, 100502 (2004).

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

2011-06-01

184

Strongly Interacting Atom Lasers in Three-Dimensional Optical Lattices  

SciTech Connect

We show that the dynamical melting of a Mott insulator in a three-dimensional lattice leads to condensation at nonzero momenta, a phenomenon that can be used to generate strongly interacting atom lasers in optical lattices. For infinite on-site repulsion, the case considered here, the momenta at which bosons condense are determined analytically and found to have a simple dependence on the hopping amplitudes. The occupation of the condensates is shown to scale linearly with the total number of atoms in the initial Mott insulator. Our results are obtained by using a Gutzwiller-type mean-field approach, gauged against exact-diagonalization solutions of small systems.

Hen, Itay; Rigol, Marcos [Department of Physics, Georgetown University, Washington, D.C. 20057 (United States)

2010-10-29

185

Four-level superradiant laser with full atomic cooperativity  

SciTech Connect

We investigate a four-level superradiant laser whose intensity is proportional to N{sup 2} and whose linewidth scales as 1/N{sup 2}. In the absence of spontaneous emissions, we derive the stationary solutions of the atomic full cooperativity, analyze their stabilities, and find the corresponding irreducible representation based on group U(4). We also investigate the spectra of the phase and amplitude fluctuations of the fields inside and outside the cavity and find that the amplitude fluctuations of the output fields cannot be squeezed in the low-frequency limit, which is completely different from the three-level superradiant laser system. Finally, we consider the stationary solutions corresponding to the partial cooperativity due to the symmetry breaking of U(4) induced by the atomic spontaneous emissions.

Yu Deshui [Department of Applied Physics, Graduate School of Engineering, University of Tokyo, Bunkyo-ku, Tokyo 113-8656 (Japan); Chen Jingbiao [Institute of Quantum Electronics and State Key Laboratory of Advanced Optical Communication System and Network, School of Electronics Engineering and Computer Science, Peking University, Beijing 100871 (China); State Key Laboratory of Precision Spectroscopy, East China Normal University, Shanghai, 200062 (China)

2010-05-15

186

Effect of Laser Power on Atom Probe Tomography of Silicates  

NASA Astrophysics Data System (ADS)

Atom probe tomography (APT) is an emerging analytical method that has the potential to produce nm-scale spatial resolution of atom positions with ppm-level detection limits. Until recently, APT has been limited to analysis of conducting samples due to the high pulsed electrical fields previously required. The recent development of laser-assisted APT now allows much lower laser powers to be used, opening the door to analysis of geologic minerals. The potential applications are many, ranging from diffusion profiles to the distribution of nano-phases to grain boundary chemical properties. We reported the first analysis of natural olivine using APT last year (Parman et al, 2010). While the spatial resolution was good (nm-scale), the accuracy of the compositional analysis was not. Two of the primary barriers to accurate ion identification in APT are: 1) Specimen overheating - This is caused by the interaction of the laser with the low thermal conductivity insulating specimens. Ions are assumed to have left the surface of the sample at the time the laser is pulsed during the analysis (laser pulse width = 12 ps). If the laser power is too high, the surface remains heated for an appreciable time (greater than 5 ns in some cases) after the laser pulse, causing atoms to field evaporate from the surface well after the laser pulse. Since they hit the detector later than the atoms that were released during the pulse, they are interpreted to be higher mass. Thus overheating appears in the analysis as a smearing of mass/charge peaks to higher mass/charge ratios (thermal tails). For well separated peaks, this is not a substantial problem, but for closely spaced peaks, overheating causes artificial mass interferences. 2) Molecular evaporation or clustering - This is also caused by overheating by the laser. Ideally, atoms are field evaporated individually from the surface of the cylindrical specimen. However, if the absorbed energy is high enough, clusters of atoms will be formed via surface diffusion and subsequently evaporated. Identifying clusters in the TOF data is problematic and may result in uncounted or misidentified ions. This problem appears to be exacerbated in high oxygen content materials like silicates due to the overlap of O+ and O2++. Both of these factors contributed to the high errors on the initial olivine APT analyses. Here, we report the results of using a laser with 100 times lower power than our previous analyses (500 pJ vs. 5 pJ). As expected, this yields a substantial improvement in both overheating and clustering, resulting in improved accuracy of the compositional analyses. In terms of mass resolution, the improvement is observable as a notable decrease in the full peak width at 1/10th peak maximum, from 5 ns to 0.4 ns.

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

2011-12-01

187

Atomic Physics at Accelerators: Laser Spectroscopy and Applications  

NASA Astrophysics Data System (ADS)

From 19 to 24 September, 1999, the First European Conference Atomic Physics at Accelerators: Laser Spectroscopy and Applications (APAC'99) was held at University of Mainz and Schloss Waldhausen (Budenheim, Germany) under the chairmanship of H. Backe and G. Huber. The idea of this up-to-date conference was associated with the 65th anniversary of Professor Ernst Otten (University of Mainz) who, together with H. Kluge, contributed much to the development of this work at CERN, University of Mainz, and Darmstadt.

Letokhov, Vladilen

188

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

Microsoft Academic Search

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

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

1987-01-01

189

A laser-cooled chromium atomic beam under 1 mrad for direct-write atom-lithography  

NASA Astrophysics Data System (ADS)

We have developed an apparatus for laser-cooling chromium atomic beams using one-dimensional optical molasses. The divergence of the atomic beam was reduced from 4.5 mrad to 0.87 mrad and the intensity of fluorescence was increased by 1.79 times with a 45 mW laser power.

Zhang, Wentao; Zhu, Baohua; Xiong, Xianming; Yuan, Zongheng; Zhang, Baowu; Ma, Yan; Li, Tongbao

2008-12-01

190

Laser-induced electron diffraction for probing rare gas atoms.  

PubMed

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

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

2012-12-05

191

Cooling and Trapping 88Sr Atoms with 461 nm Laser  

NASA Astrophysics Data System (ADS)

We report the experimental realization of a 88Sr magneto-optical trap (MOT) operating at the wavelength of 461 nm. The MOT is loaded via a 32 cm long spin-flip type Zeeman slower which enhances the MOT population by a factor of 22. The total laser power available in our experiment is about 300 mW. We have trapped 1.6 × 108 88Sr atoms with a 679nm and 707 nm repumping laser. The two repumping lasers enhance the trap population and trap lifetime by factors of 11 and 7, respectively. The 88Sr cloud has a temperature of about 2.3 mK, measured by recording the time evolution of the absorption signal.

Wang, Shao-Kai; Wang, Qiang; Lin, Yi-Ge; Wang, Min-Ming; Lin, Bai-Ke; Zang, Er-Jun; Li, Tian-Chu; Fang, Zhan-Jun

2009-09-01

192

INTERACTION OF LASER RADIATION WITH MATTER. LASER PLASMA: Stability of the melt in a vapour---gas channel during melting of metals by pulsed laser radiation  

Microsoft Academic Search

An analysis was made of the experimental data on the stability of a molten bath when millisecond pulses from a free-running laser with a variable time profile interacted with steel. At certain critical radiation power densities, the molten bath began to lose its stability and liquid metal particles were ejected under the action of pulses with different profiles. It was

S. V. Kayukov; A. A. Gusev

1996-01-01

193

High-frequency modulation of 1.52-micron vapour-phase-transported InGaAsP lasers  

Microsoft Academic Search

Modifications to the vapor-phase-transported (VPT) InGaAsP laser are described which increase the small-signal modulation bandwidth from the typical value of 3 GHz to as high as 8 GHz. A schematic diagram of the modified VPT InGaAsP laser is presented, and the limitations to the bandwidth resulting from laser parasitics and nonlinear effects are examined. It is shown that the bandwidth

J. E. Bowers; T. L. Koch; B. R. Hemenway; T. J. Bridges; E. G. Burkhardt; D. P. Wilt

1985-01-01

194

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

PubMed

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

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

2007-09-01

195

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

SciTech Connect

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

McCarron, Daniel J.; Hughes, Ifan G.; Tierney, Patrick; Cornish, Simon L. [Department of Physics, Durham University, South Road, Durham DH1 3LE (United Kingdom)

2007-09-15

196

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

NASA Astrophysics Data System (ADS)

The design and performance of a compact heated vapor cell unit for realizing a dichroic atomic vapor laser lock (DAVLL) for the D2 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.

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

2007-09-01

197

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

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

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

2011-09-01

198

Search for a permanent EDM using laser cooled radioactive atom  

NASA Astrophysics Data System (ADS)

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

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

2011-07-01

199

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

NASA Astrophysics Data System (ADS)

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 mm2 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 48Ca 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 103-104 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.

Cayzac, Witold; Frank, Alexander; Schumacher, Dennis; Roth, Markus; Blaževi?, Abel; Wamers, Felix; Träger, Michael; Berdermann, Elèni; Voss, Bernd; Hessling, Thomas

2013-04-01

200

Nuclear-driven flashlamp pumping of the atomic iodine laser  

SciTech Connect

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.

Miley, G.H.

1992-03-01

201

The Effect of Intense Laser Radiation on Atomic Collisions  

NASA Astrophysics Data System (ADS)

Available from UMI in association with The British Library. Requires signed TDF. We have carried out theoretical and experimental studies into the effect of intense laser radiation on atomic collisions. The first experiment used neon. Excitation by electron impact in a gas discharge demanded a pressure of at least 0.075 Torr. Measurement of the intensity of 3^1S_0to 3^1P_1 fluorescence has been made for the case where high intensity ASE wings in the laser profile and background laser scatter are unimportant, with the laser tuned to resonance. The field intensity required to produce strong field fluorescence (exemplified by the Mollow triplet) was found to give rise to complications capable of screening the effects sought. Our theoretical model has suggested that at finite detunings, line-centre fluorescence will dominate Rayleigh scatter and omega_3 fluorescence. Our measurements provide information on the saturation of neon fluorescence but not of the variation of the intense field collision rate. Absorption of weak field 253.7 nm laser photons by ground state mercury atoms yielded a high 6 ^3P_1 population at a lower pressure of 0.02 Torr. The Mollow triplet has been observed in the self-broadened mercury system. Dressing of the upper transition (6^3P_1rightarrow 7^3S_1) by an intense laser close to 435.8 nm yielded the strong field signal. Polarisation studies were made possible by the 3-level mercury system (radiation trapping in a 2-level system would depolarise fluorescence) perturbed by argon. The studies yielded results that were explainable in terms of the selective population of Stark shifted dressed states by a detuned, weak probe field. Use has been made of the electric-dipole radiation selection rule m_{J}=0 rightarrow m_{J^' } = 0 unless J=J^' to devise a 'Stark shift collision switch'. The competition between collision and radiation induced transitions within the mercury atom has then been studied. The resonant, strong lambda 435.8 nm field was used in conjunction with the weak lambda 253.7 nm field detuned by 0 to 6 cm^ {-1}. Measurement of fluorescence intensity in two perpendicular planes of polarisation has revealed the dominant | e_1> to | e_2> excitation channel as a function of the Stark shift by way of the U.V. detuning. Competition between the channels was dependent on the generalised Rabi frequency. However, we could only monitor the relative strength of the channels and were thus unable to say that the Stark shift switched collisions off. (Abstract shortened by UMI.).

Young, Stephen Michael Radley

1991-02-01

202

Ionization of atomic hydrogen in strong infrared laser fields  

SciTech Connect

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

Grum-Grzhimailo, Alexei N.; Abeln, Brant; Bartschat, Klaus; Weflen, Daniel; Urness, Timothy [Department of Physics and Astronomy, Drake University, Des Moines, Iowa 50311 (United States); Department of Mathematics and Computer Science, Drake University, Des Moines, Iowa 50311 (United States)

2010-04-15

203

Search for permanent EDM using laser cooled Fr atoms  

NASA Astrophysics Data System (ADS)

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

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

2013-03-01

204

Observing the profile of an atom laser beam  

SciTech Connect

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

Koehl, M.; Esslinger, T. [Institute of Quantum Electronics, ETH Zuerich, CH-8093 Zurich (Switzerland); Busch, Th. [Department of Physics, University College Cork, College Road, Cork (Ireland); Department of Physics and Astronomy, University of Aarhus, DK-8000 Aarhus C (Denmark); Moelmer, K. [Department of Physics and Astronomy, University of Aarhus, DK-8000 Aarhus C (Denmark); Haensch, T. W. [Sektion Physik, Ludwig-Maximilians-Universitaet, Schellingstrasse 4/III, D-80799 Munich (Germany); Max-Planck-Institut fuer Quantenoptik, D-85748 Garching (Germany)

2005-12-15

205

Combined Atomic Force and Confocal Laser Scanning Microscope  

NASA Astrophysics Data System (ADS)

We present a novel combined atomic force microscope (AFM) and confocal laser scanning microscope (CLSM). The sample is supported from the side by a boom from a piezo tube scanner, allowing top and bottom access to the sample. The sample is scanned above an inverted microscope objective with a fixed optical path for fluorescent CLSM imaging. An AFM positioned directly above the sample simultaneously measures surface topography. The piezo tube scanner is angled, placing its center of scan curvature directly above the microscope objective. This geometry allows flat scans up to 300 [mu]m on a side. Because the sample is scanned, the AFM and CLSM images are acquired in direct registration.

Hillner, P. E.; Walters, D. A.; Lal, R.; Hansma, H. G.; Hansma, Rk.

1995-06-01

206

The Dynamics of Rubidium Atoms in THz Laser Fields  

NASA Astrophysics Data System (ADS)

By using B-spline basis set combined with model potential, energy levels and wave functions of rubidium atoms are obtained. Using a time-dependent multi-level approach, we study the dependence of the population of rubidium atoms excited from a low lying state to a target state on the parameters of a single or two broadband terahertz laser pulses. The population redistribution between the states n = 23 and n = 24 due to the interaction with terahertz pulses is analyzed in detail. Population oscillation in the initial and final states as a function of the time delay between two half cycle pulses is shown, and the oscillation period is the same as the Kepler period of the selected states. The calculation results agree well with the experiment and can be explained by the semiclassical picture.

Jia, Guang-Ru; Zhao, Yue-Jin; Zhang, Xian-Zhou; Liu, Yu-Fang; Yu, Kun

2013-07-01

207

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

SciTech Connect

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)

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

208

Atomic and Molecular Systems in Intense Ultrashort Laser Pulses  

NASA Astrophysics Data System (ADS)

The full quantum mechanical treatment of atomic and molecular systems exposed to intense laser pulses is a so far unsolved challenge, even for systems as small as molecular hydrogen. Therefore, a number of simplified qualitative and quantitative models have been introduced in order to provide at least some interpretational tools for experimental data. The assessment of these models describing the molecular response is complicated, since a comparison to experiment requires often a number of averages to be performed. This includes in many cases averaging of different orientations of the molecule with respect to the laser field, focal volume effects, etc. Furthermore, the pulse shape and even the peak intensity is experimentally not known with very high precision; considering, e.g., the exponential intensity dependence of the ionization signal. Finally, experiments usually provide only relative yields. As a consequence of all these averagings and uncertainties, it is possible that different models may successfully explain some experimental results or features, although these models disagree substantially, if their predictions are compared before averaging. Therefore, fully quantum-mechanical approaches at least for small atomic and molecular systems are highly desirable and have been developed in our group. This includes efficient codes for solving the time-dependent Schrodinger equation of atomic hydrogen, helium or other effective one- or two-electron atoms as well as for the electronic motion in linear (effective) one-and two-electron diatomic molecules like H_2.Very recently, a code for larger molecular systems that adopts the so-called single-active electron approximation was also successfully implemented and applied. In the first part of this talk popular models describing intense laser-field ionization of atoms and their extensions to molecules are described. Then their validity is discussed on the basis of quantum-mechanical calculations. Finally, some peculiar molecular strong-field effects and the possibility of strong-field control mechanisms will be demonstrated. This includes phenomena like enhanced ionization and bond softening as well as the creation of vibrational wavepacket in the non-ionized electronic ground state of H_2 by creating a Schrodinger-cat state between the ionized and the non-ionized molecules. The latter, theoretically predicted phenomenon was very recently experimentally observed and lead to the real-time observation of the so far fastest molecular motion.

Saenz, A.

2008-07-01

209

Chaotic scattering from hydrogen atoms in a circularly polarized laser field  

NASA Astrophysics Data System (ADS)

We investigate the classical dynamics of a hydrogen atom in a circularly polarized laser beam with finite radius. The spatial cutoff for the laser field allows us to use scattering processes to examine the laser-atom dynamics. We find that for certain field parameters, the delay times, the angular momentum, and the distance of closest approach of the scattered electron exhibit fractal behavior. This fractal behavior is a signature of chaos in the dynamics of the atom-field system.

Okon, Elias; Parker, William; Chism, Will; Reichl, Linda E.

2002-11-01

210

Atomic fountain of laser-cooled Yb atoms for precision measurements  

SciTech Connect

We demonstrate launching of laser-cooled Yb atoms in a cold atomic fountain. Atoms in a collimated thermal beam are first cooled and captured in a magneto-optical trap (MOT) operating on the strongly allowed {sup 1}S{sub 0}{yields}{sup 1}P{sub 1} transition at 399 nm (blue line). They are then transferred to a MOT on the weakly allowed {sup 1}S{sub 0}{yields}{sup 3}P{sub 1} transition at 556 nm (green line). Cold atoms from the green MOT are launched against gravity at a velocity of around 2.5 m/s using a pair of green beams. We trap more than 10{sup 7} atoms in the blue MOT and transfer up to 70% into the green MOT. The temperature for the odd isotope {sup 171}Yb is {approx}1 mK in the blue MOT, and reduces by a factor of 40 in the green MOT.

Pandey, Kanhaiya; Rathod, K. D.; Singh, Alok K.; Natarajan, Vasant [Department of Physics, Indian Institute of Science, Bangalore 560 012 (India)

2010-10-15

211

Measurement of Ar Excited Atoms Temperature in D.C planar Discharge by Diode laser technique  

NASA Astrophysics Data System (ADS)

A diode laser has been used to measure the temperature of Ar atoms. A D.C discharge is employed to make the Ar excited atoms between two planar stainless steel electrodes in a Pyrex glass tub. The laser beam passes through the plasma. This laser is calibrated on 772.3nm corresponding to the high intensity wavelength of light which emitted by Ar atoms. The diode laser input power is modulated as saw tooth mode by a signal generator. The temperature of the Ar atoms is calculated by full-width-half-maximum (FWHM) of Doppler absorption curve. Details of results will be discussed in full paper.

Mehranfar, Mona; Eshghabadi, Majid; Yasserian, Kioumars; Ghoranneviss, Mahmood

2008-10-01

212

Laser-Excited Atomic Fluorescence Techniques for Temperature Measurements in Flames: A Summary.  

National Technical Information Service (NTIS)

Twelve laser-excited atomic fluorescence methods suitable for absolute temperature measurements in flames and other atomic and/or ionic reservoirs are reviewed and summarized. The different characteristics of the techniques are discussed. Several importan...

G. Zizak N. Omenetto J. D. Winefordner

1984-01-01

213

Dynamics of excimer laser-ablated aluminum neutral atom plume measured by dye laser resonance absorption photography  

Microsoft Academic Search

We report the first dye laser resonance absorption photographs of a single species of aluminum ground-state neutral atoms in the plume ablated from solid aluminum by KrF excimer laser radiation. Aluminum ground-state neutral atoms were diagnosed by illuminating the ablated plume with a dye laser tuned to the 3²{ital P}ââ--4²{ital S}ââ transition at 394.4 nm. Measurements have been performed in

Ronald M. Gilgenbach; Peter L. G. Ventzek

1991-01-01

214

Dynamics of excimer laser-ablated aluminum neutral atom plume measured by dye laser resonance absorption photography  

Microsoft Academic Search

We report the first dye laser resonance absorption photographs of a single species of aluminum ground-state neutral atoms in the plume ablated from solid aluminum by KrF excimer laser radiation. Aluminum ground-state neutral atoms were diagnosed by illuminating the ablated plume with a dye laser tuned to the 32P1\\/2–42S1\\/2 transition at 394.4 nm. Measurements have been performed in vacuum as

Ronald M. Gilgenbach; Peter L. G. Ventzek

1991-01-01

215

Laser-assisted electron - atom resonance scattering and laser-induced resonance interference  

NASA Astrophysics Data System (ADS)

The weak-field soft-photon theory for free - free transitions is generalized to include atomic potentials which support resonances. The present formulation is not restricted by geometrical constraints. In particular, it may be applied in situations where the laser polarization is perpendicular to the electron momentum transfer. In this special geometry, former theories have predicted that laser-assisted electron - atom scattering resonances should appear as pure Breit - Wigner peaks on a vanishingly small background. The present theory includes higher-order terms and shows that the background amplitude may compete with the resonance part to produce characteristic Fano-type resonance signals. Considering tunable radiation fields it is shown that the laser may induce resonance-interference effects. The shapes of overlapping resonances are in general determined by an interplay between resonance scattering amplitudes and a laser-controlled contrast parameter. Characteristic spectral features in the laser-induced overlap between fine-structure components are uniquely related to the distinctly different interference properties of direct and spin-flip amplitudes.

Bojer Madsen, Lars; Taulbjerg, Knud

1997-03-01

216

PSDF of log-amplitude scintillation for 7 mu m band laser beam with absorption by water vapour  

Microsoft Academic Search

The power spectral density function (PSDF) of the log-amplitude scintillation for an infrared laser beam was measured experimentally. To investigate the contribution of the absorption and the dispersion that cause the scintillation, we chose 16 wavelengths of infrared light and one wavelength of visible light. It is found that the spectral density of scintillation for the infrared beam does not

Naoki Kagawa; Osami Wada; Ryuji Koga

1993-01-01

217

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

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

Xiaodong Yang

1998-01-01

218

Laser radiation field control of the divergence of an atomic beam channeled in a polycapillary  

NASA Astrophysics Data System (ADS)

The condition of minimal divergence of an atomic beam in a polycapillary system under conditions of laser radiation input into the polycapillary wall is considered. The effect of errors in the microcapillary size on atomic beam divergence is studied. The microcapillary radius ensuring minimal divergence of the atomic beam is optimized with allowance for the quantum character of atomic motion.

Bavizhev, M. D.; Bavizhev, A. D.; Kot, N. V.

2012-09-01

219

Optically pumped external-cavity semiconductor lasers for precision spectroscopy and laser cooling of atomic Hg  

NASA Astrophysics Data System (ADS)

We demonstrate the utility of optically pumped semiconductor lasers (OPSLs) in the eld of precision atomic spectroscopy. We have constructed an OPSL for the purpose of laser-cooling and trapping neutral Hg atoms. The OPSL lases at 1015 nm and is frequency quadrupled to provide the trapping light for the ground state cooling transition. We report up to 1.5 W of stable, single-frequency output power with a linewidth of < 70 kHz with active feedback. From the OPSL we generate deep-UV light at 253.7 nm used to form a neutral Hg magneto-optical trap (MOT). We present details of the MOT. We also report initial results for spectroscopy of the 61S0 - 63P0 clock transition in the Hg199 isotope.

Paul, Justin R.; Lytle, Christian R.; Kaneda, Yushi; Moloney, Jerome; Wang, Tsuei-Lian; Jones, R. Jason

2013-02-01

220

Diode pumped Nd:YGG laser for direct generation of pulsed 935 nm radiation for water vapour measurements  

Microsoft Academic Search

A resonator setup applying a double-sided diode end-pumped configuration and an electro-optical Q-switch for efficient generation of 4 mJ pulses (< 60 ns fwhm) at 935 nm from Nd:YGG is presented, to our knowledge for the first time. The optical-optical efficiency is 9 % (absorbed pump light to laser out). High quality crystals have been investigated, showing high damage threshold,

J. Löhring; K. Nicklaus; N. Kujath; D. Hoffmann

2007-01-01

221

IV INTERNATIONAL CONFERENCE ON ATOM AND MOLECULAR PULSED LASERS (AMPL'99): IV International Conference on Atomic and Molecular Pulsed Gas Lasers (AMPL'99)  

NASA Astrophysics Data System (ADS)

A brief review of the most interesting papers presented at the IV International Conference on Atomic and Molecular Pulsed Gas Lasers (AMPL'99), which was held in Tomsk, September 13-17, 1999, is provided.

Evtushenko, Gennadii S.; Kopylova, T. N.; Soldatov, A. N.; Tarasenko, Viktor F.; Yakovlenko, Sergei I.; Yancharina, A. M.

2000-06-01

222

Electron impact ionization of atomic clusters in ultraintense laser fields  

NASA Astrophysics Data System (ADS)

In this paper we report on inner ionization of Xe{n} clusters (n = 55{-} 2171) in ultraintense Gaussian laser fields (peak intensity I = 1015{-} 1020 Wcm-2, pulse width ? = 25 fs, frequency 0.35 fs-1). The cluster inner ionization process is induced by the barrier suppression ionization (BSI) mechanism and by electron impact ionization (EII), which occurs sequentially with the BSI. We address electron impact ionization of clusters, which pertains to inelastic reactive processes of the high-energy (100 eV 1 keV per electron) nanoplasma. We utilized experimental data for the energy dependence of the electron impact ionization cross-sections of Xej+ (j = 1{-}10) ions, which were fit by an empirical three-parameter Lotz-type equation, to explore EII in clusters by molecular dynamics simulations. Information was obtained on the yields and time-resolved dynamics of the EII levels (i.e., number nimp of electrons per cluster atom) in the Xe{n} clusters and their dependence on the laser intensity and cluster size. The relative long-time (t = 90 fs) yields for EII, nimp/nii (where nii is the total inner ionization yield) are rather low and increase with decreasing the laser intensity. In the intensity range I = 1015{-}1016 Wcm-2, nimp/nii = 0.21 for n = 2171 and nimp/nii = 0.09{-}0.14 for n = 459, while for I = 1018{-}1020 Wcm-2, nimp/nii = 0.01{-}0.05. The difference ? nimp between the EII yield at long time and at the termination of the laser pulse reflects on ionization dynamics by the nanoplasma when the laser pulse is switched off. For Xe{2171} in the lower intensity domain, ? nimp = 0.9 at I = 1015 Wcm-2 and ? nimp = 0.4 at 1016 Wcm-2, reflecting on EII by the persistent nanoplasma under “laser free” conditions, while in the higher intensity domain of I = 1017 {-} 1018 Wcm-2, ? nimp is negligibly small due to the depletion of the transient nanoplasma.

Heidenreich, A.; Last, I.; Jortner, J.

2005-09-01

223

Lithium vapour excitation at 2S?3D two-photon resonance  

NASA Astrophysics Data System (ADS)

We report study of processes which occur in lithium vapour under two-photon excitation of the Li(3D) state at 639.1 nm. A time-resolved technique has been used to measure the fluorescence from the Li(3D), Li(2P) and Li(3P) states. We have determined radiation rates for lithium atom densities in the range 1013-1014 cm-3 and laser powers (105-106 Wcm-2). The ground-state lithium atom density was determined by knowing temperature and vapour pressure in a modified heat-pipe oven. The contribution to radiation rates from different processes and prospect for cross-section determination of homonuclear reverse energy-pooling are discussed.

Labazan, I.; Miloševi?, S.

2000-01-01

224

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

SciTech Connect

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

Todd Ditmire

2004-10-21

225

Accurate time-resolved laser spectroscopy on sodium and bismuth atoms  

Microsoft Academic Search

It is demonstrated that time resolved laser spectroscopy can give atomic lifetime data with an accuracy of better than 0.5%. This is achieved by a single-photon counting delayed coincidence technique, using a mode-locked dye laser for the excitation. Natural radiative lifetimes are measured for the sodium and bismuth atoms.

J. Carlsson

1988-01-01

226

Atomic beam deflection by the light of a tunable dye laser  

Microsoft Academic Search

The deflection of a sodium atomic beam by the radiation pressure of the light of a cw dye laser was investigated. From the deflection observed it is deduced that the linear momentum trasferred corresponds to an average of 60 excitations per atom. The linewidth of the dye laser used for the measurements was smaller than 50 MHz.

R. Schieder; H. Walther; L. Wöste

1972-01-01

227

Growth of Spatial Nonuniformity of Laser Beam Propagating in Near-Resonant Atomic Vapor  

Microsoft Academic Search

Growth of spatial nonuniformity of laser beam propagating in the near-resonant atomic vapor was numerically studied for atomic vapor laser isotope separation (AVLIS). The simulation results well reproduced the linear and nonlinear growth and the beam breakup. The growing region of nonuniformity and the maximum growth rate were analyzed in relation to the spatial wavenumber of ripple and the nonlinear

Keiji NOMARU; Yasukazu IZAWA; Yen-Wei CHEN

1997-01-01

228

Resonances of coherent population trapping in samarium vapours  

SciTech Connect

Resonances of coherent population trapping were detected in atomic vapours of the rare-earth element samarium. The coherent population trapping was produced by two external-cavity diode lasers (672 and 686 nm) in a {Lambda}-system formed by the three levels of {sup 154}Sm: the 4f{sup 6}6s{sup 2}({sup 7}F{sub 0}) ground state, the first fine-structure 4f{sup 6}6s{sup 2}({sup 7}F{sub 1}) sublevel of the ground state and the 4f{sup 6}({sup 7}F)6s6p({sup 3}P{sup o}){sup 9}F{sup o}{sub 1} upper level. The dependence of the spectral shapes and resonance contrasts on the polarisation of the laser beams and the direction of the applied magnetic field was studied. The obtained results were analysed. (nonlinear optical phenomena)

Kolachevsky, Nikolai N; Akimov, A V; Kiselev, N A; Papchenko, A A; Sorokin, Vadim N; Kanorskii, S I [P.N. Lebedev Physics Institute, Russian Academy of Sciences, Moscow (Russian Federation)

2001-01-31

229

Dipole and quadrupole forces exerted on atoms in laser fields: The nonperturbative approach  

SciTech Connect

Manipulation of cold atoms by lasers has so far been studied solely within the framework of the conventional dipole approximation, and the atom-light interaction has been treated using low order perturbation theory. Laser control of atomic motions has been ascribed exclusively to the corresponding light-induced dipole forces. In this work, we present a general theory to derive the potential experienced by an atom in a monochromatic laser field in a context analogous to the Born-Oppenheimer approximation for molecules in the field-free case. The formulation goes beyond the dipole approximation and gives rise to the field-atom coupling potential terms which so far have not been taken into consideration in theoretical or experimental studies. Contrary to conventional approaches, our method is based upon the many electron Floquet theory and remains valid also for high intensity laser fields (i.e., for a strongly nonperturbative atom-light interaction). As an illustration of the developed theory, we investigate the trapping of cold atoms in optical lattices. We find that for some atoms for specific laser parameters, despite the absence of the dipole force, the laser trapping is still possible due to the electric quadrupole forces. Namely, we show that by using realistic laser parameters one can form a quadrupole optical lattice which is sufficiently strong to trap Ca and Na atoms.

Sindelka, Milan; Moiseyev, Nimrod [Department of Chemistry and Minerva Center of Nonlinear Physics in Complex Systems, Technion, Israel Institute of Technology, Haifa 32000 (Israel); Cederbaum, Lorenz S. [Theoretische Chemie, Physikalisch-Chemisches Institut, Universitaet Heidelberg, D-69120 Heidelberg (Germany)

2006-11-15

230

Electron impact ionization and excitation studies of laser prepared atomic targets  

NASA Astrophysics Data System (ADS)

A review of current work at Manchester is given, with emphasis on low energy electron impact ionization & excitation experiments from laser-prepared targets. Three different methods are considered: super-elastic scattering from targets prepared by laser radiation in an optical enhancement cavity, (e,2e) studies of laser-aligned atoms, and electron impact ionization studies from laser cooled atoms in a new type of atom trap - the AC-MOT. The status of each experimental programme is detailed, and new data presented. Future directions and techniques are then discussed.

Murray, Andrew James; Hussey, Martyn; Knight-Percival, Alex; Jhumka, Sarah; Nixon, Kate L.; Harvey, Matthew; Agomuo, John

2012-11-01

231

Techniques of laser spectroscopy in investigations of lanthanides' free atoms and ions  

NASA Astrophysics Data System (ADS)

Various experimental methods, used in Chair of Quantum Engineering and Metrology for determination of the hyperfine structure of electronic levels in lanthanides atoms and ions, are presented. In turn the spectroscopic methods on an atomic beam (laser induced fluorescence and laser-rf double resonance ABMR-LIRF), laser-rf double resonance in a Paul trap and spectroscopic methods in a hollow cathode discharge (optogalvanic detection and laser induced fluorescence) are presented. Each method has been characterized with its potential accuracy and domain of application. The results achieved for the atoms and the ions of lanthanum, praseodymium, neodymium and europium have been published in numerous articles (compiled in the reference list).

Furmann, B.; Szawiola, G.; Jarosz, A.; Krzykowski, A.; Stefanska, D.; Dembczynski, J.

2010-02-01

232

Interacting laser and Bose-Einstein-condensate atomic beams: Mutual guiding structures  

SciTech Connect

A basic set of equations describing the interaction of a Bose-Einstein condensate (BEC) with a laser field is derived based on a semiclassical model and applied to the problem of mutual guiding of laser and BEC atomic beams. Within this framework we have studied stationary spatially localized solutions of the nonlinear system which describe possible laser and BEC atomic beam guiding and have shown their stability as well. It is also shown that a self-guiding effect can be realized through both single- and multiple-scaled structures of a BEC atomic and a laser beam.

Cattani, F. [Department of Physics, Clarendon Laboratory, OX1 3PU, Oxford (United Kingdom); Geyko, V.; Kim, A. [Institute of Applied Physics, Russian Academy of Sciences, 603950 Nizhny Novgorod (Russian Federation); Anderson, D.; Lisak, M. [Department of Radio and Space Science, Chalmers University of Technology, SE-412 96 Goeteborg (Sweden)

2010-04-15

233

Nanoscale focused ion beam from laser-cooled lithium atoms  

NASA Astrophysics Data System (ADS)

We demonstrate a new type of nanoscale focused ion beam (FIB) based on photoionizing laser-cooled atoms held at millikelvin temperatures in a magneto-optical trap (MOT). This new source expands the range of available ionic species and accessible ion beam energies for FIBs, enhancing their role as one of the most important tools for nanoscale characterization and fabrication. We show examples of microscopy with lithium ions obtained by scanning the FIB and collecting the resulting secondary electrons, and characterize the beam focus by a 25-75% rise distance measurement of (26.7 ± 1.0) nm at a beam energy of 2 keV. We also examine the dependence of the focal size on MOT temperature and beam energy.

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

2011-10-01

234

Modifying atomic collision dynamics with intense ultrashort laser pulses  

SciTech Connect

It has been suggested that ''short'' pulses of intense laser radiation can modify atomic collision dynamics in new and interesting ways. Recent experimental results in sodium-argon vapor with 1.6-psec pulses verify the existence of such an effect, although smaller in magnitude and at somewhat higher field intensities than had been predicted from theoretical arguments. Using quantum-mechanical wave-packet propagation on a realistic potential-energy curve under the parameters of the experiment, we determine that the time between curve crossings, the standard against which pulse durations should be measured, is on the order of 0.8 psec or less. The experimental results can then be understood in the context of having used too long a pulse to have clearly observed short-pulse effects.

DeVries, P.L.

1988-02-01

235

Laser assisted electron-atom scattering in critical geometries  

NASA Astrophysics Data System (ADS)

We investigate the scattering of electrons off of neutral targets in the presence of a linearly polarized, low frequency laser field. The laser has large enough extent for the wavefunction to be treated in the Floquet expansion. The scattering geometries of interest are small angles where momentum transfer is nearly perpendicular to the field, and the Kroll Watson approximation breaks down. We use the eigenchannel R matrix method to solve the Schr"odinger equation, employing Hamiltonians in both the length and the velocity gauges in different regions. The target atom is represented by a model potential including a screened coulomb term near the origin and a longer range induced dipole interaction. The short range reaction matrix in the Kramers-Henneberger (acceleration) representation is found by matching the velocity gauge R matrix to spherical Gordon-Volkov states, and from this the cross section is derived. Experiments have shown emission and absorption cross sections at small angles to be much higher than the approximation predicts, and we hope to gain insight into the cause of this phenomenon.

Morrison, Nathan; Greene, Chris H.

2012-06-01

236

Interaction of intense laser pulses with atomic clusters: Measurements of ion emission, simulations and applications  

NASA Astrophysics Data System (ADS)

This review paper provides a general introduction to the interaction of intense (/>1015 Wcm-2), femtosecond laser pulses with atomic clusters in the size range 500-105 atoms. A nanoplasma model of the laser-cluster interaction is used to elucidate the underlying physics. Measurements of ion emission from the laser-cluster interaction are presented together with numerical simulations. Emerging applications are described.

Tisch, J. W. G.; Hay, N.; Mendham, K. J.; Springate, E.; Symes, D. R.; Comley, A. J.; Mason, M. B.; Gumbrell, E. T.; Ditmire, T.; Smith, R. A.; Marangos, J. P.; Hutchinson, M. H. R.

2003-05-01

237

Production of doubly charged ions in the ionisation of Ba atoms in two laser fields  

Microsoft Academic Search

The production of doubly charged ions is studied upon multiphoton ionisation of Ba atoms exposed simultaneously to two radiation fields: the fundamental radiation of a colour centre laser ( = 8800 - 8880 cm¹) and its second harmonic. A two-electron mechanism was shown to be responsible for the production of these ions. (interaction of laser radiation with matter. laser plasma)

I I Bondar; V V Suran

2001-01-01

238

Spatial and temporal behaviors of laser beam propagating in atomic vapor  

Microsoft Academic Search

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

K. Nomaru; Y.-W. Chen; Y. Izawa; S. Nakai; C. Yamanaka

1996-01-01

239

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

SciTech Connect

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.

Rhodes, C.K.

1986-01-01

240

Atomic photoionization with synchronized X-ray and optical lasers  

NASA Astrophysics Data System (ADS)

Photoionization is the dominant processes after the interaction of atoms with photons of short wavelength. New possibilities to obtain dynamical information about this extremely fast process were opened up in the last years due to the development of Free Electron Lasers, such as FLASH in Hamburg and LCLS in Stanford, with their unprecedented characteristics, especially the ultra-short temporal width of the pulses, which can be as short of a few femtoseconds, and the extremely high number of photons per pulse (about 10^12-10^13 photons/pulse) [1,2]. In a series of experiments at FLASH, the combination of XUV FEL radiation and synchronized NIR laser pulses was used to study the Above Threshold Ionization (ATI) in rare gases for the first time in a regime free from unwanted interference effects. Especially, the polarization dependence of the sideband structures in the electron spectra yields detailed insights into the photoionization dynamics, in particular into the distribution of angular momenta for the outgoing electrons [3]. Recent experiments at the LCLS have taken advantage of the very short (2-5fs) pulse durations, which are delivered by this new X-ray Free Electron Laser. This temporal width coincides with the lifetime of core hole states governing the dynamics of the Auger decay, and with the temporal width of one cycle of the electric field in the optical wavelength regime. By applying angle-resolved electron spectroscopy, the KLL Auger decay in atomic Ne was studied after excitation with few-fs X-ray (1 keV) pulses in the presence of an optical (800 nm) dressing field. The experimental spectra are marked by strong interference effects caused by the coherent emission of electrons produced during one cycle of the superimposed optical dressing field, in excellent agreement with recent theoretical work.[4pt] [1] C. Bostedt et al., Nucl. Instrum. Meth. A 601, 108 (2009).[0pt] [2] N. Berrah et al., J. Mod. Opt. 52, 1015 (2010).[0pt] [3] M. Meyer et al., Phys. Rev. Lett. 101, 193002 (2008).[0pt] [4] Y. Ding et al., Phys. Rev. Lett. 102, 254801 (2009).[0pt] [5] A.K. Kazansky, N.M. Kabachnik, J.Phys.B 42, 121002 (2009); 43, 035601 (2010).

Meyer, Michael

2011-06-01

241

Chemical oxygen-iodine laser with atomic iodine generated in a separate reactor  

NASA Astrophysics Data System (ADS)

The chemical oxygen-iodine laser (COIL) with a chemical method of atomic iodine generation was studied. Two methods of atomic iodine generation were proposed and developed. They are based on fast reactions of gaseous hydrogen iodide with chemically produced chlorine or fluorine atoms. Atomic iodine formation via Cl atoms we studied earlier by mixing of reaction gases directly in the primary O2(1?g) flow in COIL. A revealed oxidation of HI by singlet oxygen and the O2(1?g) quenching by some reaction product, however, reduced the attainable laser gain. This problem could be avoided by atomic iodine generation in separate reactors with following injection of atomic iodine into the primary O2(1?g) flow. Gain measurements using this arrangement are presented in this paper. New experimental results on atomic iodine production via F atoms are also summarized. Using of reactive gases commercially available in pressure cylinders is the main advantage of this method.

Špalek, Otomar; Jirásek, Vít; ?enský, Miroslav; Kodymova, Jarmila; Pickova, Irena; Jakubec, Ivo

2006-05-01

242

Long lifetime of single atom in optical tweezer with laser cooling  

NASA Astrophysics Data System (ADS)

Single cesium atom prepared in a large-magnetic-gradient magneto-optical trap (MOT) has been efficiently loaded into a microscopic far-off-resonance optical trap (FORT, or optical tweezer), and the atom can be transferred back and forth between two traps with high efficiency. The intensity noise spectra of tweezer laser are measured and the heating mechanisms in optical tweezer are analyzed. To prolong the lifetime of single atom trapped in optical tweezer, laser cooling technique is utilized to decrease atom's kinetic energy, and the effective temperature of single atom in tweezer is estimated by the release-and-recapture (R&R) method. Thanks to laser cooling, typical lifetime of ~ 130.6 +/- 1.8 s for single atom in tweezer is obtained. These works provides a good starting point for coherent manipulation of single atom.

Wang, Junmin; He, Jun; Yang, Baodong; Zhang, Tiancai; Peng, Kunchi

2010-04-01

243

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

NASA Astrophysics Data System (ADS)

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

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

1995-02-01

244

Polarity and Vapour Pressure  

Microsoft Academic Search

IN considering the effect of polarity on the vapour pressure and association of a liquid, a simple case is its influence on the partial vapour pressures of a polar liquid in its binary mixtures with a non-polar liquid, which, except for lack of polarity, should preferably be closely related in chemical structure to the polar liquid.

A. R. Martin

1931-01-01

245

Detection of chlorinated hydrocarbons via Laser-atomization/Laser-induced fluorescence  

NASA Astrophysics Data System (ADS)

Chlorinated hydrocarbons (CHC), photodissociated at 193 nm, are detected with high sensitivity by observing the atomic chlorine fragment via laser-induced fluorescence (LIF). Photofragment emission spectra from CH3Cl, CH2Cl2, CHCl3, CCl4, C2HCl3, and C2Cl4 demonstrate that photofragment fluorescence and chemiluminescence are negligible in the region 700 800 nm where the 3 p 44 p 4 S 0 ? 3 p 44 s 4 P fluorescence from atomic chlorine is detected. There is also negligible interference for photodissociation in Ar, N2, and air bath gases. Total CHC can be readily detected in air flows at mixing fractions less than 20 ppb and averaging times less than 1 minute. Techniques for considerable improvement in this detection limit are discussed.

Jeffries, J. B.; Raiche, G. A.; Jusinski, L. E.

1992-07-01

246

The XUV photoabsorption spectrum of uranium vapour  

Microsoft Academic Search

The XUV photoabsorption spectrum of uranium vapour has been recorded by means of a novel, twin laser-produced plasma technique. The spectrum is dominated by a broad collective resonance and is in good agreement with recent predictions of many-body theory. Within the limits of experimental error, the widths and positions of the peaks are similar to those of the solid but

P. K. Carroll; J. T. Costello

1987-01-01

247

Charge states of high Z atoms in a strong laser field  

SciTech Connect

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.

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

248

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

PubMed

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

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

2010-12-02

249

Above-threshold ionization in atomic hydrogen using intense few-cycle laser pulses  

Microsoft Academic Search

We have performed the first strong-field ionization experiment in atomic hydrogen using few-cycle laser pulses. Quantitative agreement between experimental data and advanced ab initio simulations has been achieved at the 10% level.

W. C. Wallace; M. G. Pullen; D. E. Laban; A. J. Palmer; G. F. Hanne; A. N. Grum-Grzhimailo; B. Abeln; K. Bartschat; D. Weflen; I. Ivanov; A. Kheifets; H. M. Quiney; I. V. Litvinyuk; R. T. Sang; D. Kielpinski

2011-01-01

250

Electron-impact ionization of atomic hydrogen in the presence of a laser field  

SciTech Connect

The influence of a laser field on the dynamics of fast (/ital e/,2/ital e/)collisions in atomic hydrogen is analyzed in the asymmetric, coplanar geometry.Particular attention is devoted to the construction of the dressed(laser-modified) target wave functions, in both the initial and final states. Adetailed account is also given of the techniques we have used to evaluate thescattering amplitudes. In addition to a nonperturbative approach (valid to allorders in the laser-projectile interaction), we also discuss a second-ordertreatment in the combined electron-atom and laser-system (electron plus atom)interactions. The influence of the laser parameters (frequency, intensity, anddirection of polarization) on the angular distribution of the ejected electronis discussed, and a number of illustrative examples are given. The structure ofthe triple differential cross section in the vicinity of resonances is alsoanalyzed.

Martin, P.; Veniard, V.; Maquet, A.; Francken, P.; Joachain, C. J.

1989-06-15

251

Observation of laser-induced collisional two-photon ionisation in a strontium-caesium mixture  

Microsoft Academic Search

Laser-induced collisional ionisation of caesium is observed in a strontium-caesium vapour mixture. In their initial state both atomic species are in the ground level. The ionisation of caesium is achieved when the system is illuminated by an intense laser light, the frequency of which is tuned across the resonance line of strontium. The process involves photoabsorption during the collisional interaction.

C. Brechignac; Ph Cahuzac; A. Debarre

1980-01-01

252

Laser-Induced Continuum Structure and Third Harmonic Generation in - and Two-Valence Atoms  

Microsoft Academic Search

A model for calculating third harmonic generation (THG) in a near-resonantly coupled 4-level atomic system in the presence of laser-induced continuum structure (LICS) is formulated in terms of the time dependent density matrix elements which can be obtained by solving the time dependent density matrix equations for the atomic system interacting with laser pulses. The theory is applied to a

Jian Zhang

1991-01-01

253

Coherent transient effects in laser-cooled and room temperature atoms  

Microsoft Academic Search

This thesis presents several coherent transient effects with laser cooled (100 muK) and room temperature (298K) 85Rb atoms. The understanding of interaction of nearly resonant radiation and matter, which is a fundamental problem of physics can be obtained by investigation of such transient phenomena. With the help of laser cooling techniques, an ideal two-level system is achieved. Atomic properties such

Unyob Shim

1997-01-01

254

Detection of titanium in electrothermal atomizers by laser-induced fluorescence. Part 2. Investigation of various types of atomizers  

Microsoft Academic Search

Different types of electrothermal atomizers (graphite and tungsten furnaces) have been studied for the determination of Ti by laser-induced fluorescence (LIF). It was found that all graphite furnaces suffer from both bulk contamination by Ti, corresponding to tens of pg per firing, and significant memory effects in such a way that the high sensitivity of the LIF technique could not

Per Ljung; Eric Nyström; Ove Axner; Wolfgang Frech

1997-01-01

255

Classical-trajectory simulation of accelerating neutral atoms with polarized intense laser pulses  

NASA Astrophysics Data System (ADS)

In the present paper, we perform the classical trajectory Monte Carlo simulation of the complex dynamics of accelerating neutral atoms with linearly or circularly polarized intense laser pulses. Our simulations involve the ion motion as well as the tunneling ionization and the scattering dynamics of valence electron in the combined Coulomb and electromagnetic fields, for both helium (He) and magnesium (Mg). We show that for He atoms, only linearly polarized lasers can effectively accelerate the atoms, while for Mg atoms, we find that both linearly and circularly polarized lasers can successively accelerate the atoms. The underlying mechanism is discussed and the subcycle dynamics of accelerating trajectories is investigated. We have compared our theoretical results with a recent experiment [Eichmann Nature (London)NATUAS0028-083610.1038/nature08481 461, 1261 (2009)].

Xia, Q. Z.; Fu, L. B.; Liu, J.

2013-03-01

256

New laser action of optically pumped atomic vanadium vapor  

NASA Astrophysics Data System (ADS)

Laser action has been observed on the vanadium 560.4-, 575.3-, 581.7-, and 637.9-nm lines. Vanadium vapor is produced from vanadium metal plate by YAG laser (2.0 J/pulse) irradiation, and optically pumped by an XeCl excimer laser of 25-mJ energy. The vanadium laser pulse has a duration of 50 ns and peak output power of about 7 W.

Yoshida, H.; Takashima, N.; Ninomiya, H.

1992-01-01

257

High resolution continuous wave laser induced fluorescence spectroscopy of sputtered Zr atoms  

SciTech Connect

High resolution laser induced fluorescence (LIF) spectroscopy utilizing a continuous wave ring dye laser was used to measure the velocity distribution of sputtered Zr atoms. The ring dye laser permitted the determination of the sputtered Zr atom velocity distribution with a resolution of 2.4 x 10/sup 3/ cm/s over the emission range of 0 to 2 x 10/sup 6/ cm/s. The sputtered Zr atoms were produced by bombardment of the metal target by normally incident 3 keV Kr/sup +/. Determination of the velocity distributions was accomplished by tuning the exciting laser frequency through the Doppler shifted absorption frequencies of the sputtered atoms. It was determined that such processes as laser power density and transit time broadening of the sputtered atom's energy levels, the laser pulse duration and bandwidth as well as the geometry of the fluorescence excitation and detection system were all critical parameters important to the understanding of the experimental LIF velocity distributions. A comparison is also made between the use of cw and pulsed laser sources to excite the LIF emission. The measured velocity distributions were found to be in good agreement with previously proposed theoretical distributions based on the linear collision cascade model of sputtering.

Wright, R.B.; Young, C.E.; Pellin, M.J.; Gruen, D.M.

1982-03-01

258

Cesium atom ground state coherence created by an optical frequency comb laser  

NASA Astrophysics Data System (ADS)

Quantum interference resolved by the coherent laser modes from a mode-locked laser is significant in demonstrating femtosecond-laser based high resolution spectroscopy. Moreover, the high Q frequency discriminator resulted from quantum interference phenomenon could possibly serve for comb laser repetition rate stabilization. We discovered a 5-Hz width transparent window when the repetition rate of our optical frequency comb laser [1] was adjusted to be on resonance of cesium atom ground state hyperfine transition. We showed that cesium atom ground state coherence might be created by the comb laser modes, based on the observation of Zeeman effects. We performed our experiment with 8700 Pascal Neon buffer gas and 100^oC (1 mK instability) wall temperature. Frequency shift by wall temperature and the other effects will be presented.[3pt] [1] Appl. Phys. B 92, 13-18 (2008).

Cheng, Wang-Yau; Wu, Tsung-Han; Lu, Sheng-Huei

2009-05-01

259

Gain measurements and high resolution spectroscopy of the 546.1 nm atomic mercury laser transition  

Microsoft Academic Search

An investigation of the gain of a CW atomic mercury laser using a tunable dye laser is reported. Several isotopes are seen to be simultaneously excited and found to lase in multiple isotope mixtures. The nitrogen pressure dependence of the gain is found to be in good agreement with rate equation analyses, provided a pressure dependent loss term due to

S. M. Skippon; T. A. King; M. D. Rabbett

1983-01-01

260

Investigations of field-evaporated end forms in voltage- and laser-pulsed atom probe tomography.  

PubMed

Atom Probe Tomography (APT) consists of analyzing a needle-shaped specimen on an atom-by-atom basis. In recent years, instruments have become commercially available, enabling the sequential analysis of the same specimen in both laser- and voltage-pulsed modes. In this contribution, a comparison of field evaporated end-forms as a function of the voltage and laser power is presented for silicon. Electron microscopy is utilized for visual inspection of the final tip end-forms. The field of evaporation for silicon is calculated based on these radius measurements for voltage and laser pulsing. Electron microscopy and analysis of the atom probe data show that the specimen end-forms for both pulsing modes can be different. We have observed two effects on the shape of a field-ion emitter when irradiated by a focused laser beam. One is a change in the 3-dimensional topology of the emitter due to different crystallographic orientations. Secondly, exposure to focused laser beam from one side may lead to a non-hemispherical tip shape especially when reasonably high laser energy is utilized. For comparison purposes to the laser mode, the voltage pulse evaporated tip end form is also analyzed for different specimen temperatures. Consequently, evaporation fields are calculated for different temperatures and laser conditions for silicon. PMID:19062187

Shariq, A; Mutas, S; Wedderhoff, K; Klein, C; Hortenbach, H; Teichert, S; Kücher, P; Gerstl, S S A

2008-11-01

261

Alternative applications of atomic vapor laser isotope separation technology  

SciTech Connect

This report was commissioned by the Secretary of Energy. It summarizes the main features of atomic vapor laser isotope separation (AVLIS) technology and subsystems; evaluates applications, beyond those of uranium enrichment, suggested by Lawrence Livermore National Laboratory (LLNL) and a wide range of US industries and individuals; recommends further work on several applications; recommends the provision of facilities for evaluating potential new applications; and recommends the full involvement of end users from the very beginning in the development of any application. Specifically excluded from this report is an evaluation of the main AVLIS missions, uranium enrichment and purification of plutonium for weapons. In evaluating many of the alternative applications, it became clear that industry should play a greater and earlier role in the definition and development of technologies with the Department of Energy (DOE) if the nation is to derive significant commercial benefit. Applications of AVLIS to the separation of alternate (nonuranium) isotopes were considered. The use of {sup 157}Gd as burnable poison in the nuclear fuel cycle, the use {sup 12}C for isotopically pure diamond, and the use of plutonium isotopes for several nonweapons applications are examples of commercially useful products that might be produced at a cost less than the product value. Separations of other isotopes such as the elemental constituents of semiconductors were suggested; it is recommended that proposed applications be tested by using existing supplies to establish their value before more efficient enrichment processes are developed. Some applications are clear, but their production costs are too high, the window of opportunity in the market has passed, or societal constraints (e.g., on reprocessing of reactor fuel) discourage implementation.

Not Available

1991-01-01

262

Investigation of wüstite (Fe1-xO) by femtosecond laser assisted atom probe tomography.  

PubMed

In this paper, we report results obtained from laser assisted three-dimensional (3-D) atom probe tomography (APT) on wüstite (Fe(1-x)O). Oxides are generally insulating and hence hard to analyse in conventional electrical assisted APT. To overcome this problem, femtosecond laser pulses are used instead of voltage pulses. Here we discuss some aspects of pulsed laser field evaporation and optimization of parameters to achieve better chemical accuracy. PMID:21159434

Bachhav, M; Danoix, R; Danoix, F; Hannoyer, B; Ogale, S; Vurpillot, F

2010-11-20

263

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

SciTech Connect

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.

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

264

Absolute Density Measurement of Metal Atoms by Laser Resonance Scattering with the Aid of Rayleigh Scattering  

Microsoft Academic Search

The absolute density of metal atoms such as iron and aluminium atoms, the knowledge of which is urgently needed for study of the high temperature plasma-wall interaction, was measured by the laser resonance scattering method within an accuracy of 50%. The calibration of the optical system was performed by using the Rayleigh scattering from argon gas at sub-atmospheric pressure, and

Makoto Hamamoto; Mitsuo Maeda; Katsunori Muraoka; Masanori Akazaki

1981-01-01

265

Productions of Hollow Atoms from Solids Irradiated by High Intensity Laser  

NASA Astrophysics Data System (ADS)

The production of hollow atoms through the collisions of fast electrons with a solid is studied. These electrons are produced by high-intensity short-pulse laser irradiation on a solid. The inner-shell ionization and excitation processes by the fast electron impact are investigated. It is found that ionization processes give more significant contribution to the production of hollow atoms.

Moribayashi, Kengo; Sasaki, Akira; Zhidkov, A.

266

Atomic-fluorescence method for determining the concentration of alkali metal vapor using a laser source  

Microsoft Academic Search

In this paper we examine the atomic-fluorescence method for determining the concentration of alkali metal vapors using a laser source for the example of cesium atoms. Alkali metal vapors of Rb and Cs are widely used as working substances in commercial quantum frequency standards [8], and the investigation of the dependence of their concentration on the temperature in the buffer-gas

L. A. Budkin; O. G. Okhotnikov; G. T. Pak; A. I. Pikhtelev; S. L. Puzanov

1984-01-01

267

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

Microsoft Academic Search

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;

Gábor Galbács

2006-01-01

268

Multiple species atom source for laser-cooling experiments  

SciTech Connect

We describe the design of a single beam, multiple species atom source in which the flux of any component can be separately adjusted. Using this design we have developed a {sup 23}Na-{sup 6}Li atom source for ultracold atom experiments. The fluxes of lithium and sodium are independently tunable, allowing operation as a single {sup 23}Na or {sup 6}Li source as well as a double source with equal atomic fluxes in each component.

Stan, C.A.; Ketterle, W. [Department of Physics, MIT-Harvard Center for Ultracold Atoms, and Research Laboratory of Electronics, MIT, Cambridge, Massachusetts 02139 (United States)

2005-06-15

269

Interaction-induced phase fluctuations in a guided atom laser  

SciTech Connect

In this paper we determine the magnitude of phase fluctuations caused by atom-atom interaction in a one-dimensional beam of bosonic atoms. We imagine that the beam is created with a large coherence length, and that interactions only act in a specific section of the beam, where the atomic density is high enough to validate a Bogoliubov treatment. The magnitude and coherence length of the ensuing phase fluctuations in the beam after the interaction zone are determined.

Bouchoule, Isabelle [Institut d'Optique, 91 403 Orsay Cedex (France); Moelmer, Klaus [QUANTOP, Danish National Research Foundation Center for Quantum Optics, Department of Physics and Astronomy, University of Aarhus, DK 8000 Aarhus C (Denmark)

2003-01-01

270

Efficient extension of the trapping lifetime of single atoms in an optical tweezer by laser cooling  

NASA Astrophysics Data System (ADS)

Optical tweezers have become powerful tools for the confinement and manipulation of neutral atoms, molecules, mesoscopic biological molecules and living cells. In our experiment, a single caesium atom was prepared in a large-magnetic-gradient magneto-optical trap (MOT). It was then efficiently transferred back and forth between the MOT and a 1064 nm microscopic optical tweezer. The atomic transfer between the MOT and the tweezer can be employed to measure the trapping lifetime and the energy distribution of the single atom in the tweezer. In order to extend the trapping lifetime, laser cooling is used to decrease the atom's kinetic energy. The trapping lifetime was extended from ~75 to ~130 s by applying a 10 ms laser cooling phase just after the single atom is transferred into the tweezer.

He, Jun; Yang, Baodong; Zhang, Tiancai; Wang, Junmin

2011-08-01

271

Generation of cold low divergent atomic beam of indium by laser ablation  

SciTech Connect

The formation of low-energy (below 100 m/s), low divergence (without any collimation optics) pulsed indium atomic beam via ablation of thin film by direct illumination (unfocused) from the rear side with second harmonic of Q-switched Nd:YAG laser under high vacuum ({approx}10{sup -5} Torr) is reported. Angular divergence of an ablated indium beam was measured for the different laser powers. Axial atomic and ionic velocities were studied as a function of laser energy per pulse using a beam deflection setup.

Alti, Kamlesh; Khare, Alika [Department of Physics Indian Institute of Technology Guwahati, Guwahati-781039 (India)

2005-11-15

272

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

SciTech Connect

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

Gulyaev, A. V., E-mail: gulyaevav@gmail.com; Tikhonova, O. V. [Moscow State University (Russian Federation)

2012-05-15

273

PARCS: NASA’s laser-cooled atomic clock in space  

Microsoft Academic Search

The Primary Atomic Reference Clock in Space (PARCS) mission is designed to perform certain tests of relativity theory, to study the performance of individual GPS space-vehicle clocks, to study the dynamics of atom motion in microgravity, to advance the state-of-the art for space clocks, and to serve as a pathfinder for precision instruments based on laser cooling of atoms. After

D. B. Sullivan; N. Ashby; E. A. Donley; T. P. Heavner; L. W. Hollberg; S. R. Jefferts; W. M. Klipstein; W. D. Phillips; D. J. Seidel

2005-01-01

274

NONLINEAR OPTICAL PHENOMENA: Resonances of coherent population trapping in samarium vapours  

Microsoft Academic Search

Resonances of coherent population trapping were detected in atomic vapours of the rare-earth element samarium. The coherent population trapping was produced by two external-cavity diode lasers (672 and 686 nm) in a Lambda-system formed by the three levels of 154Sm: the 4f66s2(7F0) ground state, the first fine-structure 4f66s2(7F1) sublevel of the ground state and the 4f6(7F)6s6p(3Po)9Fo1 upper level. The dependence

Nikolai N. Kolachevsky; A. V. Akimov; N. A. Kiselev; A. A. Papchenko; Vadim N. Sorokin; S. I. Kanorskii

2001-01-01

275

Atomic data for highly charged ions Applications to X-ray laser design and thermonuclear fusion  

NASA Astrophysics Data System (ADS)

A detailed understanding of a myriad of atomic processes is proving important for the development of short wavelength lasers and to the achievement of controlled thermonuclear fusion. A brief overview of some X-ray laser design issues is presented along with a discussion of relevant atomic data needs. Special attention is given to the need for experimental verification of rate coefficient data which are important for determining laser kinetics. Approaches to magnetic and inertial confinement fusion are reviewed with emphasis on atomic processes affecting both fuel burn and plasma diagnostics. Recent advances in the development of high power ICF drivers, both lasers and particle beams, are shown to suggest new areas of research involving very highly charged ions in dense hot plasmas.

Younger, Stephen M.

1987-04-01

276

From a quantum to a classical description of intense laser-atom physics with Bohmian trajectories  

NASA Astrophysics Data System (ADS)

In this paper, Bohmian mechanics is applied to intense laser-atom physics. The motion of an atomic electron in an intense laser field is obtained from the Bohm-Newton equation. We find that the quantum potential that dominates the quantum effect of a physical system becomes negligible as the electron is driven far from the parent ion by the intense laser field, i.e. the behavior of the electron smoothly tends towards classical soon after the electron is ionized. Our numerical calculations present direct positive evidence for semiclassical trajectory methods in intense laser-atom physics where the motion of the ionized electron is treated by classical mechanics, while quantum mechanics is needed before the ionization.

Lai, X. Y.; Cai, Qing-Yu; Zhan, M. S.

2009-11-01

277

Atomic-absorption method of analysis for biological samples with laser atomization  

Microsoft Academic Search

Investigations of the capabilities of lasers have shown that they can be successfully applied in various methods of spectral analysis of both organic as well as of inorganic materials. Until the advent of the laser there was no way of analyzing small regions in biological samples without specially removing a sample. Laser rad{ation focused on small objects converts them into

L. T. Sukhov; G. E. Zolotukhin; S. M. Zyabkina

1976-01-01

278

Hydrogen atom in a strong laser field: Numerical simulation versus Keldysh-type theories  

NASA Astrophysics Data System (ADS)

The dynamics of a 3D hydrogen atom in an intense laser pulse is investigated using the direct numerical integration of the nonstationary Schrödinger equation in the multiphoton regime of ionization. The results obtained are compared with the theoretical data of the strong-field approximation (SFA) method and the validity of the SFA and other Keldysh-type theories in the problem of the strong-field ionization of atoms is analyzed in a wide range of laser frequencies and intensities. The Reiss approximation (SFA) provides qualitative agreement with the numerical simulation for moderate laser intensities and reveals the channel closing phenomena during the multiphoton ionization. However, this approach is found to be inappropriate in the presence of strong fields where we numerically demonstrate the suppression of atomic ionization. The reason for the stabilization lies in the formation of a new system (dressed atom), which is not taken into account in the SFA and other Keldysh-type theories.

Popov, A. M.; Tikhonov, M. A.; Tikhonova, O. V.; Volkova, E. A.

2008-05-01

279

Colloquium: Laser probing of neutron-rich nuclei in light atoms  

NASA Astrophysics Data System (ADS)

The neutron-rich He6 and He8 isotopes exhibit an exotic nuclear structure that consists of a tightly bound He4-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 He4-He6-He8 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.

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

2013-10-01

280

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

SciTech Connect

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.''

Page, R H; Beach, R J

2005-02-16

281

Fully differential cross sections for ion atom impact ionization in the presence of a laser field  

NASA Astrophysics Data System (ADS)

We study fully differential cross sections (FDCS) for single ionization of helium by ion impact in the presence of a laser field. The field is assumed to have linear polarization, to be weak compared to the typical atomic field, and we use a frequency corresponding to a CO2 laser. We employ the continuum distorted wave-eikonal initial state (CDW-EIS) to describe our FDCS in the laser background. Analysing our numerical results we explore the dependence of the FDCS on the laser field properties as well as on the ionized electron parameters.

Ciappina, M. F.

2007-11-01

282

Sub-parts-per-quadrillion-level graphite furnace atomic absorption spectrophotometry based on laser wave mixing.  

PubMed

Nonlinear laser wave mixing in a common graphite furnace atomizer is presented as a zeptomole-level, sub-Doppler, high-resolution atomic absorption spectrophotometric method. A nonplanar three-dimensional wave-mixing optical setup is used to generate the signal beam in its own space. Signal collection is efficient and convenient using a template-based optical alignment. The graphite furnace atomizer offers advantages including fast and convenient introduction of solid, liquid, or gas analytes, clean atomization environment, and minimum background noise. Taking advantage of the unique features of the wave-mixing optical method and those of the graphite furnace atomizer, one can obtain both excellent spectral resolution and detection sensitivity. A preliminary concentration detection limit of 0.07 parts-per-quadrillion and a preliminary mass detection limit of 0.7 ag or 8 zmol are determined for rubidium using a compact laser diode as the excitation source. PMID:15018584

Mickadeit, Fritz K; Berniolles, Sandrine; Kemp, Helen R; Tong, William G

2004-03-15

283

A two-mode-laser as an excellent simple tool for exciting sodium atoms from both groundstate levels simultaneously  

Microsoft Academic Search

For manipulating atomic sodium beams we have built a two-mode laser in order to avoid interaction losses by optical pumping. The two laser frequencies have been actively stabilized with a precision of 1 MHz rms on two Na-D1-hf-transitions. The excellent properties of this simple laser set-up have been demonstrated by optically pumping an atomic sodium beam. The atomic beam polarizations

P. Strohmeier

1990-01-01

284

Orbital alignment in atoms generated by photodetachment in a strong laser field  

NASA Astrophysics Data System (ADS)

A pump-probe laser scheme is employed to investigate orbital alignment and its dynamics in the ground state of laser-generated neutral atoms. The alignment is initiated by electron photodetachment of an atomic negative ion in a strong laser pulse. The electron density distribution in the ground state of the residual atom is probed by means of strong-field ionization in a second laser pulse at a delayed time. The principle of the probe method relies on the fact that the portion of the electron density distribution oriented along the laser polarization axis constitutes the ionization yield in the high-energy jets of emitted electrons. A systematic study is carried out on C, Si, and Ge atoms, which possess two electrons in an open p shell. A pronounced temporal modulation in the yield of high-energy electrons is observed for C and Si, revealing a periodic spatial rearrangement of the electron density distribution in these atoms. Its period is defined by the beat between the J=1 and J=2 spin-orbit components of the ground state.

Eklund, Mikael; Hultgren, Hannes; Hanstorp, Dag; Kiyan, Igor Yu.

2013-08-01

285

Quantum fluctuations and entanglement in the collective atomic recoil laser using a Bose-Einstein condensate  

SciTech Connect

We present a quantum description of the interaction between a Bose-Einstein condensate and a single-mode quantized radiation field in the presence of a strong far-off-resonant pump laser. In the linear regime, the atomic medium is described approximately by two momentum states coupled to the radiation mode. We calculate the evolution of the operators in the Heisenberg picture and their expectation values, such as average and variance of the occupation numbers, atom-atom and atom-field correlations, and two-mode squeezing parameters. Then, we disentangle the evolution operator and obtain the exact evolution of the state vector in the linear regime. This allows us to demostrate that the system can be atom-atom or atom-field thermally entangled. We define the quasiclassical and the quantum recoil limits, for which explicit expressions of the average population numbers are obtained.

Piovella, N.; Cola, M.; Bonifacio, R. [Dipartimento di Fisica, Universita Degli Studi di Milano, INFN and INFM, Via Celoria 16, Milan I-20133 (Italy)

2003-01-01

286

Laser Cooling without Repumping: A Magneto-Optical Trap for Erbium Atoms  

SciTech Connect

We report on a novel mechanism that allows for strong laser cooling of atoms that do not have a closed cycling transition. This mechanism is observed in a magneto-optical trap (MOT) for erbium, an atom with a very complex energy level structure with multiple pathways for optical-pumping losses. We observe surprisingly high trap populations of over 10{sup 6} atoms and densities of over 10{sup 11} atoms cm{sup -3}, despite the many potential loss channels. A model based on recycling of metastable and ground state atoms held in the quadrupole magnetic field of the trap explains the high trap population, and agrees well with time-dependent measurements of MOT fluorescence. The demonstration of trapping of a rare-earth atom such as erbium opens a wide range of new possibilities for practical applications and fundamental studies with cold atoms.

McClelland, J.J.; Hanssen, J.L. [Electron Physics Group, Center for Nanoscale Science and Technology, National Institute of Standards and Technology, Gaithersburg, Maryland 20899 (United States)

2006-04-14

287

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

SciTech Connect

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

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

2006-07-06

288

Characterization of laser - induced plasmas by atomic emission spectroscopy  

NASA Astrophysics Data System (ADS)

In this work, Laser-induced breakdown spectroscopy (LIBS) has been applied to characterization of plasmas generated in air at atmospheric pressure from a calcium hydroxide sample with a known concentration of Mg by using an infrared Nd:YAG laser. The influence of laser irradiance on plasma morphology and emission intensity was studied. Spatially-integrated intensities of Mg I-II lines along the line-of-sight were measured for different laser energies and delay times. The plasma temperature and the electron density were determined in each case by using and algorithm that calculates the optical thickness of the spectral lines and reproduces their experimental profiles in a framework of an homogeneous plasma in LTE that takes into account the effects of self-absorption. The results obtained showed the usefulness of this approach to provide additional information retrieved from the optical thickness of spectral lines for plasma characterization in LIBS experiments.

Díaz Pace, Diego M.; Bertuccelli, Graciela; D'Angelo, Cristian A.

2011-01-01

289

Thermogravimetric analysis for boiling points and vapour pressure  

Microsoft Academic Search

A TGA instrument has been adapted for rapid measurement of boiling points and vapour pressure at temperatures from ambient up to 400°C 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

J. W. Goodrum; E. M. Siesel

1996-01-01

290

Electronic energy transfer induced by collision between two excited sodium atoms  

Microsoft Academic Search

We have observed the sodium doublets arising from the 32D, 52S, 42D, 62S, 52D-->32P and 42P-->32S transitions, whenever sodium vapour is illuminated with a cw dye laser tuned to the wavelength of one of the D-lines. The phenomenon is interpreted as an excitation transfer induced by collision between two excited atoms.

M. Allegrini; G. Alzetta; A. Kopystynska; L. Moi; G. Orriols

1976-01-01

291

Temporal behavior of population densities of V atoms in an optically pumped V vapor laser  

NASA Astrophysics Data System (ADS)

The time variation of population densities of V atoms in absorption levels pertinent to an optically pumped atomic V vapor laser is studied experimentally. V vapor is generated from a V metal by irradiation of a pulsed Nd:YAG (1.06 micron) laser of 2 J/pulse energy and 1.4 ms pulse duration. The population densities of the ground-state and excited-state (E about 2400/cm) V atoms have been measured by the interferometric method, and the temperature in the vapor is estimated from these populations. It has been experimentally observed that the populations of the ground state and the excited state are about 1 x 10 exp 14/cu cm and 4 x 10 exp 13/cu cm, respectively. The temperature in the vapor increased from about 1800 to 4000 K with time during the YAG laser irradiation.

Ninomiya, H.; Yoshida, H.; Takashima, N.

1992-04-01

292

Coherent phase control of excitation of atoms by bichromatic laser radiation in an electric field  

SciTech Connect

A new method for coherent phase control of excitation of atoms in a discrete spectrum under the action of bichromatic laser radiation with the frequency ratio 1:2 is analysed. An important feature of this control method is the presence of a electrostatic field, which removes the parity selection rule for one of the control channels. It is shown that for the phase difference between the monochromatic radiation components, corresponding to the destructive interference between channels, there exists the electrostatic field strength at which the excited atomic transition is 'bleached'. It is proposed to use luminescence at the adjacent atomic transition for detecting the phase dependence of optical excitation. (interaction of laser radiation with matter. laser plasma)

Astapenko, Valerii A [Laser Center, Moscow Institute of Physics and Technology, Dolgoprudnyi, Moscow region (Russian Federation)

2005-06-30

293

Characterization of photopyroelectric vapour analysis  

Microsoft Academic Search

In this work we present the quantitative and qualitative detection of organic vapours by a photopyroelectric (PPE) sensor. The PPE sensor consists of a pyroelectric detector covered with a sensitive polymer film. The vapour is sorbed within the film and excited by infrared radiation. The heat obtained by thermal relaxation depends on the amount of sorbed vapour. Finally, the electrical

W. Rumpler; H. Wurzer

1995-01-01

294

One and Two Electron Ionization of Atoms by a Strong Laser Field  

Microsoft Academic Search

We report on strong field-atom interactions at optical frequencies, notably, electron-ion ``rescattering'' in strong fields. Strong fields, generated by gigawatt peak power, high repetition rate lasers, were used to measure the intensity dependent ionization probabilities of the noble gases over an unprecedented twelve orders of magnitude between the laser intensities of 10^13 and 10^16 W\\/cm^2. The time dependent Schrödinger equation

Barry C. Walker

1997-01-01

295

Atomic photoionization in combined intense XUV free-electron and infrared laser fields  

Microsoft Academic Search

We present a systematic study of the photoionization of noble gas atoms exposed simultaneously to ultrashort (20 fs) monochromatic (1–2% spectral width) extreme ultraviolet (XUV) radiation from the Free-electron Laser in Hamburg (FLASH) and to intense synchronized near-infrared (NIR) laser pulses with intensities up to about 1013 W cm?2. Already at modest intensities of the NIR dressing field, the XUV-induced

P Radcliffe; M Arbeiter; W B Li; S Düsterer; H Redlin; P Hayden; P Hough; V Richardson; J T Costello; T Fennel; M Meyer

2012-01-01

296

Theory of laser-assisted Auger processes generated by ultrashort XUV pulses in atoms  

Microsoft Academic Search

A non-stationary quantum mechanical theory of the laser-assisted Auger process in atoms excited by an ultrashort (attosecond) electromagnetic pulse in the field of a few-cycle strong optical laser pulse is considered. The theory is based on numerically solving the time-dependent Schrödinger equation describing Auger decay. An approach is suggested which can be applied for the case of low-energy Auger electrons

A. K. Kazansky; I. P. Sazhina; N. M. Kabachnik

2011-01-01

297

Kinetic model of atomic and molecular emissions in laser-induced breakdown spectroscopy of organic compounds  

Microsoft Academic Search

A kinetic model previously developed to predict the relative intensities of atomic emission lines in laser-induced breakdown\\u000a spectroscopy has been extended to include processes related to CN and C2 molecular emissions. Simulations with this model were performed to predict the relative excited-state populations. The results\\u000a from the simulations are compared with experimentally determined excited-state populations from 1,064 nm laser irradiation\\u000a of

Qianli Ma; Paul J. Dagdigian

298

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

SciTech Connect

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

Krmpot, A. J.; Radonjic, M.; Cuk, S. M.; Nikolic, S. N.; Grujic, Z. D.; Jelenkovic, B. M. [Institute of Physics, University of Belgrade, Pregrevica 118, RS-11080 Belgrade (Serbia)

2011-10-15

299

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

SciTech Connect

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.

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

300

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

SciTech Connect

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

Bauer, Jaroslaw H. [Katedra Fizyki Teoretycznej Uniwersytetu Lodzkiego, Ul. Pomorska 149/153, PL-90-236 Lodz (Poland)

2011-03-15

301

Enhanced photon correlations due to strong laser-atom-cavity coupling  

NASA Astrophysics Data System (ADS)

We investigate the resonant quantum dynamics of a laser-pumped real or artificial two-level single-atom system embedded in a leaking microcavity. We found that for stronger laser-atom-cavity couplings the generated microcavity photons exhibit larger steady-state correlations. In particular, the second- and third-order photon correlation functions are greater than the corresponding ones obtained for an incoherent light source, respectively. Furthermore, the emitted microcavity photon flux is enhanced in comparison to weaker coupling cases.

Ciornea, Viorel; Bardetski, Profirie; Macovei, Mihai A.

2013-08-01

302

Perturbation-Variational Approach to Hydrogen Atoms in Strong Laser Fields  

NASA Astrophysics Data System (ADS)

In this letter, a perturbation variational approach (PVA) to atomic behavior in strong laser fields is expressed briefly. For the wide range of ?0 =0.1?50, the ground state energy of H-atom in laser fields is obtained by the present approach. The energy values obtained by PVA agree with the previous values given by Landgraf and Gavrila. In contrast, the advantage of the present method is to give both the energy eigenvalue and the wavefunction of the ground state analytically.

Chen, Baozhen

1994-07-01

303

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

NASA Astrophysics Data System (ADS)

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

Haghshenasfard, Zahra; Cottam, Michael G.

2013-09-01

304

Controlled dipole-dipole interactions between K Rydberg atoms in a laser-chopped effusive beam  

NASA Astrophysics Data System (ADS)

We explore pulsed-field control of resonant dipole-dipole interactions between K Rydberg atoms. A laser-based atomic beam chopper is used to reduce the relative velocities of Rydberg atoms excited from an effusive thermal source. Resonant energy transfer (RET) between pairs of atoms is controlled via Stark tuning of the relevant Rydberg energy levels. Resonance line shapes in the electric field dependence of the RET probability are used to determine the effective temperature of the sample. We demonstrate that the relative atom velocities can be reduced to the point where the duration of the electric-field tuning pulses, and not the motion of neighboring atoms, defines the interaction time for each pair within the ensemble. Coherent, transform-limited broadening of the resonance line shape is observed as the tuning pulse duration is reduced below the natural time scale for collisions.

Kutteruf, M. R.; Jones, R. R.

2010-12-01

305

Controlled dipole-dipole interactions between K Rydberg atoms in a laser-chopped effusive beam  

SciTech Connect

We explore pulsed-field control of resonant dipole-dipole interactions between K Rydberg atoms. A laser-based atomic beam chopper is used to reduce the relative velocities of Rydberg atoms excited from an effusive thermal source. Resonant energy transfer (RET) between pairs of atoms is controlled via Stark tuning of the relevant Rydberg energy levels. Resonance line shapes in the electric field dependence of the RET probability are used to determine the effective temperature of the sample. We demonstrate that the relative atom velocities can be reduced to the point where the duration of the electric-field tuning pulses, and not the motion of neighboring atoms, defines the interaction time for each pair within the ensemble. Coherent, transform-limited broadening of the resonance line shape is observed as the tuning pulse duration is reduced below the natural time scale for collisions.

Kutteruf, M. R.; Jones, R. R. [Department of Physics, University of Virginia, Charlottesville, Virginia 22904-4714 (United States)

2010-12-15

306

Comparing laser interferometry and atom interferometry approaches to space-based gravitational-wave measurement  

NASA Astrophysics Data System (ADS)

The science enabled by a space-based low-frequency gravitational-wave instrument is a high-priority objective of the international astronomy community. Mission concepts based on laser interferometry, such as the Laser Interferometer Space Antenna (LISA), have been thoroughly studied and determined to be capable of delivering significant science returns. Ongoing developments in laboratory atom interferometry techniques have inspired new gravitational-wave mission concepts. We present a comparative analysis of LISA-like light interferometer systems and atom interferometer systems for gravitational-wave detection. Specific attention is paid to the sources of instrumental noise that are most important for light interferometer systems. We find that the response to laser frequency noise is identical in light interferometer and atom interferometer systems and that similar mitigation strategies (e.g. multiple-arm interferometers) must be employed to reach interesting gravitational wave sensitivities. Response to acceleration of the optical platforms is slightly different, allowing smaller spacecraft separations in the atom interferometry approach, but the acceleration noise requirements are similar. Based on this analysis, we find no clear advantage of the atom interferometry approach over traditional laser interferometry.

Ira Thorpe, James; Jennrich, Oliver; McNamara, Paul; Baker, John G.

2012-07-01

307

Theory of x-ray absorption by laser-dressed atoms  

SciTech Connect

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

Buth, Christian; Santra, Robin [Argonne National Laboratory, Argonne, Illinois 60439 (United States)

2007-03-15

308

Entropy Driven Atomic Motion in Laser-Excited Bismuth  

SciTech Connect

We introduce a thermodynamical model based on the two-temperature approach in order to fully understand the dynamics of the coherent A{sub 1g} phonon in laser-excited bismuth. Using this model, we simulate the time evolution of (111) Bragg peak intensities measured by Fritz et al.[Science 315, 633 (2007)] in femtosecond x-ray diffraction experiments performed on a bismuth film for different laser fluences. The agreement between theoretical and experimental results is striking not only because we use fluences very close to the experimental ones but also because most of the model parameters are obtained from ab initio calculations performed for different electron temperatures.

Giret, Y.; Gelle, A.; Arnaud, B. [Institut de Physique de Rennes (IPR), UMR UR1-CNRS 6251, Campus de Beaulieu-Bat 11 A, 35042 Rennes Cedex, France, EU (France)

2011-04-15

309

Determination of the aluminum content in high-purity germanium by laser multistage photoionization of atoms  

Microsoft Academic Search

A new method is proposed for the determination of the amounts of impurities in high-purity materials. This involves thermal evaporation and atomization of the material in vacuum and selective detection of impurity atoms by laser multistage photoionization via Rydberg states. Aluminum impurities have been recorded in high-purity germanium (aluminum content 2 x 10 to the -7th%) with a signal-to-noise ratio

R. Akilov; G. I. Bekov; V. S. Letokhov; G. A. Maksimov; V. I. Mishin; V. N. Radaev; V. N. Shishov

1982-01-01

310

Ultraviolet-laser-induced desorption of atoms, ions, and molecules from lithium niobate  

SciTech Connect

We report measurements of ultraviolet-laser-induced desorption of atoms, ions, and molecules from the surface of single-crystal, Y-cut lithium niobate at intensities below the plasma threshold. Particularly striking is the desorption of LiNbO[sub 3] molecules at intensities well below the threshold for the atomic and ion emission. Measurement of oxygen and niobium yields above and below the plasma threshold show changes in surface stoichiometry.

Affatigato, M.; Tang, K.; Haglund, R.F. Jr. (Department of Physics and Astronomy, Vanderbilt University, Nashville, Tennessee 37235 (United States)); Chen, C.H. (Photophysics Section, Health and Safety Research Division, Oak Ridge National Laboratory, Oak Ridge, Tennessee 37837 (United States))

1994-10-03

311

Electronic structure of atoms in laser plasmas: a Debye shielding approach  

Microsoft Academic Search

Spectral properties of the low-lying singlet states of a helium atom and those of the low-lying doublet states of a lithium atom in laser plasmas are calculated using a quantum chemical configuration interaction method with a Debye shielding model Hamiltonian. A large spherical Gaussian basis set is adopted to describe the wavefunctions of electrons bound in a non-Coulombic Yukawa-type potential

Hiroshi Okutsu; Tokuei Sako; Kaoru Yamanouchi; Geerd H. F. Diercksen

2005-01-01

312

Production of a cold atomic vapor using diode-laser cooling  

SciTech Connect

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

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

1988-06-01

313

Velocity distribution measurements in atomic beams generated using laser induced back-ablation  

Microsoft Academic Search

We present measurements of the velocity distribution of calcium atoms in an atomic beam generated using a dual-stage laser back-ablation apparatus. Distributions are measured using a velocity selective Doppler time-of-flight technique. They are Boltzmann-like with rms velocities corresponding to temperatures above the melting point for calcium. Contrary to a recent report in the literature, this method does not generate a

A. Denning; A. Booth; S. Lee; M. Ammonson; S. D. Bergeson

2008-01-01

314

INTERACTION OF LASER RADIATION WITH MATTER. LASER PLASMA: Phase-sensitive electric modulation of photoluminescence upon bichromatic excitation of atoms  

NASA Astrophysics Data System (ADS)

A new type of modulation of the photoluminescence intensity of atoms excited by a bichromatic laser radiation with the frequency ratio 1:2 is proposed and analysed. The modulation is produced by alternating electric field acting on atoms and occurs due to the quantum interference of the amplitudes of two excitation channels of an atom, which proves to be possible because the applied electric field removes the parity selection rule for one of the excitation channels. An important feature of this process is the dependence of photoluminescence on the phase difference of monochromatic components of exciting radiation. The calculation was performed for an alkali metal atom excited at the s—s transition taking the saturation effect into account.

Astapenko, Valerii A.

2005-12-01

315

Atomic number scaling of the nickel-like soft x-ray lasers  

SciTech Connect

The authors report the review of the experimental results obtained at the Institute of Laser Engineering, Osaka University, of the soft X-ray lasing in various Ni-like ions whose atomic numbers range from 47(Ag) to 66(Dy). The lasing wavelengths are between 14 nm and 5 nm. X-ray lasing in these materials were obtained when the plasma profiles were properly controlled in time and space by irradiation of curved slab targets with multiple laser pulses. They also describe the original work of the atomic physics calculations which provide the transition energies, transition probabilities and other atomic constants for Ni-like ion species whose atomic numbers range from 36 to 92 calculated with GRASP code (multi-configuration Dirac Fock code) and YODA code (relativistic distorted wave code). Based on these atomic constants, they have calculated the kinetics of the population inversion with a simplified rate equation model in conjunction with a one-dimensional hydrodynamic code to find out the desired pumping conditions. They show a possibility for significant improvement in the pumping efficiency with the use of a picosecond laser irradiating a properly configured preformed plasma. Finally, a simplified estimation of the pumping efficiency is described based on the atomic constants and plasma physics issues.

Daido, H.; Ninomiya, S.; Imani, T. [Osaka Univ., Suita, Osaka (Japan). Inst. of Laser Engineering] [and others

1997-03-30

316

Atomic processes in plasmas under ultra-intense laser irradiation  

SciTech Connect

Lasers delivering subpicosecond pulses with energies of a fraction of a Joule have made it possible to generate irradiance levels approaching 10{sup 20} W/cm{sup 2}. We presently operate two such systems, a KrF based excimer laser capable of producing a few 10{sup 17} W/cm{sup 2} at 248 nm with a repetition rate of 3--5 Hz and a XeCl based excimer laser capable of producing mid 10{sup 19} W/cm{sup 2} at 308 nm and 1 Hz. We will discuss some experimental results and the theory and modeling of the interaction of such intense laser pulses with aluminum. Because of a small ASE prepulse the high intensity interaction is not at the solid surface but rather at the n{sub e} = 2 {times} 10{sup 22} cm{sup {minus}3} critical density of the blowoff plasma generated by the ASE. The transient behavior of the plasma following the energy deposition by the intense subpicosecond pulse can be viewed as the energy-impulse response of the plasma. Experimental results and modeling of the x-ray emission from this plasma will be presented. 15 refs., 8 figs.

Schappert, G.T.; Casperson, D.E.; Cobble, J.A.; Comly, J.C.; Jones, L.A.; Kyrala, G.A.; LaGattuta, K.J.; Lee, P.H.Y.; Olson, G.L.; Taylor, A.J.

1989-11-01

317

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

SciTech Connect

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.

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

318

Control of RILIS lasers at IGISOL facilities using a compact atomic beam reference cell  

NASA Astrophysics Data System (ADS)

The choice and proper operation of the laser systems for laser ion sources at on-line facilities using multi-step resonance ionization processes is the basis for production of intense and pure radioactive ion beams. These pave the way for numerous fundamental studies in nuclear and astrophysics. A comparison between systems of medium or high repetition rate pulsed tunable lasers based on dyes or crystals as active medium has been carried out at the IGISOL facility at Louvain-la-Neuve. The importance of properly controlling the operation conditions of the individual lasers via a reference atomic beam chamber is highlighted and design and implementation of such a compact device for permanent monitoring as well as possible regulation of the various laser parameters of relevance is discussed.

Kron, T.; Ferrer-Garcia, R.; Lecesne, N.; Sonnenschein, V.; Raeder, S.; Rossnagel, J.; Wendt, K.

2013-04-01

319

High-Power Al-free active region (lambda = 852nm) laser diodes for atomic clocks and interferometry applications  

Microsoft Academic Search

Atomic clocks will be used in the future European positioning system Galileo. Among them, the optically pumped clocks provide a more accurate alternative. For these systems, diode lasers emitting at 852nm are strategic components. The laser in a conventional bench for atomic clocks presents disadvantages for spatial applications. A better approach would be to realise a system based on a

Francois-Julien Vermersch; Michel Lecomte; Michel Calligaro; Olivier Parillaud; Shailendra Bansropun; Michel Krakowski

2006-01-01

320

Al-free active region (lambda = 852nm) DFB laser diodes for atomic clocks and interferometry applications  

Microsoft Academic Search

Atomic clocks will be used in the future European positioning system Galileo. Among them, the optically pumped clocks provide a better alternative with comparable accuracy for a more compact system. For these systems, diode lasers emitting at 852nm are strategic components. The laser in a conventional bench for atomic clocks presents disadvantages for spatial applications. A better approach would be

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

2006-01-01

321

TRINAT: measuring ?-decay correlations with laser-trapped atoms  

NASA Astrophysics Data System (ADS)

TRIUMF's neutral atom trap for ? decay (TRINAT) has been used to measure the most accurate ?-? correlation. Plans include improving that measurement, and also carrying out a full program of spin-polarized ? decay correlation measurements complementary to the decay of the neutron

Behr, J. A.; Gorelov, A.; Jackson, K. P.; Pearson, M. R.; Anholm, M.; Kong, T.; Behling, R. S.; Fenker, B.; Melconian, D.; Ashery, D.; Gwinner, G.

2013-10-01

322

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

NASA Astrophysics Data System (ADS)

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

Jaro?, A.; Kami?ski, J. Z.

1997-12-01

323

Photoionization by an ultraintense laser field: Response of atomic xenon  

SciTech Connect

We present energy- and angle-resolved photoionization from Xe in an ultrastrong laser field at 10{sup 19} W/cm{sup 2}. The observed yields are consistent with the tunneling ionization of Xe{sup 9+} to Xe{sup 24+}. However, energy and angle-resolved photoelectron spectra show differences for electrons whose final energies are above or below 0.5 MeV, which is approximately the ponderomotive energy at these intensities. Above 0.5 MeV, the observed photoelectron cutoff energy (between 1 and 1.35 MeV), photoelectron energy spectra, and the angle-resolved photoelectron azimuthal distributions agree with a model using tunneling ionization, multiple charge states, a classical relativistic continuum, and nonparaxial three-dimensional (3D) focused laser field. Below 0.5 MeV the yields and angular distributions observed indicate dynamics not included within a classical, single electron model of the interaction.

DiChiara, A. D.; Ghebregziabher, I.; Waesche, J. M.; Stanev, T.; Ekanayake, N.; Barclay, L. R.; Wells, S. J.; Watts, A.; Videtto, M.; Mancuso, C. A.; Walker, B. C. [Department of Physics and Astronomy, University of Delaware, Newark, Delaware 19716 (United States)

2010-04-15

324

Uranium accountancy in Atomic Vapor Laser Isotope Separation  

SciTech Connect

The AVLIS program pioneers the large scale industrial application of lasers to produce low cost enriched uranium fuel for light water reactors. In the process developed at Lawrence Livermore National Laboratory, normal uranium is vaporized by an electron beam, and a precisely tuned laser beam selectively photo-ionizes the uranium-235 isotopes. These ions are moved in an electromagnetic field to be condensed on the product collector. All other uranium isotopes remain uncharged and pass through the collector section to condense as tails. Tracking the three types of uranium through the process presents special problems in accountancy. After demonstration runs, the uranium on the collector was analyzed for isotopic content by Battelle Pacific Northwest Laboratory. Their results were checked at LLNL by analysis of parallel samples. The differences in isotopic composition as reported by the two laboratories were not significant.

Carver, R.D.

1986-01-01

325

Atomic-absorption spectrometry of laser-nebulized samples.  

PubMed

Thermal nebulization of nickel-base alloys, corundum plates and residues of solutions was performed with a laser beam. The solid aerosol was aspirated into an acetylene-air flame by an ejector. Linear analytical curves in wide concentration ranges were established and an average relative standard deviation of 10% was found. The detection limit is in the ng range for iron and copper, and lower for zinc, cadmium and sodium. PMID:18961933

Kántor, T; Pólos, L; Fodor, P; Pungor, E

1976-08-01

326

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

Microsoft Academic Search

A pulsed high flux source of nearly monoenergetic atomic oxygen has been developed at Physical Sciences Inc. (PSI) to perform accelerated erosion testing of spacecraft materials in a simulated low earth orbit (LEO) environment. Molecular oxygen is introduced into an evacuated conical expansion nozzle at several atmospheres pressure through a pulsed molecular beam valve. A laser induced breakdown is generated

Robert H. Krech; George E. Caledonia

1990-01-01

327

Silicon Atomic Layer Growth by Laser Beam/Si2H6 Adsorbates Interactions.  

National Technical Information Service (NTIS)

Saturated monomolecular adsorption of Si2H6 on a silicon surface held at temperatures around -60 deg C and subsequent irradiation of a single shot of ArF excimer laser fully decomposes the adsorbed layer to promote the atomic layer growth of Si. TEA CO2 l...

Y. Nagasawa T. Tanaka S. Miyazaki M. Hirose

1992-01-01

328

Spatial concentrations of silicon atoms by laser-induced fluorescence in a silane glow discharge  

Microsoft Academic Search

A capacitively coupled, rf glow discharge of silane in argon was studied to determine the spatial concentration of silicon atoms. Laser-induced fluorescence was used to determine the ground state concentration profiles. The fluorescence profiles clearly show the sharp boundaries of the sheath regions. These profiles were much more sensitive to plasma chemistry changes than profiles obtained from plasma emission. Experiments

R. M. Roth; K. G. Spears; G. Wong

1984-01-01

329

Coulomb Wave Function DVR: Application to Atomic Systems in Strong Laser Fields  

Microsoft Academic Search

We present an efficient and accurate grid method for solving the time-dependent Schrodinger equation of atomic systems interacting with intense laser pulses. As usual, the angular part of the wave function is expanded in terms of spherical harmonics. Instead of the usual finite difference (FD) scheme, the radial coordinate is discretized using the discrete variable representation which is constructed from

Liang-You Peng; Anthony F. Starace

330

Attosecond electron thermalization by laser-driven electron recollision in atoms  

Microsoft Academic Search

Nonsequential multiple ionization of atoms in intense laser fields is initiated by a recollision between an electron, freed by tunneling, and its parent ion. Following recollision, the initial electron shares its energy with several bound electrons. We use a classical model based on rapid electron thermalization to interpret recent experiments. For neon, good agreement with the available data is obtained

X. Liu; C. Figueira de Morisson; W. Becker; P. B. Corkum

2008-01-01

331

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

Microsoft Academic Search

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.

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

1988-01-01

332

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

SciTech Connect

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.

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

1988-09-01

333

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

SciTech Connect

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

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

1984-10-01

334

INTERACTION OF LASER RADIATION WITH MATTER. LASER PLASMA: Coherent phase control of excitation of atoms by bichromatic laser radiation in an electric field  

NASA Astrophysics Data System (ADS)

A new method for coherent phase control of excitation of atoms in a discrete spectrum under the action of bichromatic laser radiation with the frequency ratio 1:2 is analysed. An important feature of this control method is the presence of a electrostatic field, which removes the parity selection rule for one of the control channels. It is shown that for the phase difference between the monochromatic radiation components, corresponding to the destructive interference between channels, there exists the electrostatic field strength at which the excited atomic transition is 'bleached'. It is proposed to use luminescence at the adjacent atomic transition for detecting the phase dependence of optical excitation.

Astapenko, Valerii A.

2005-06-01

335

Termolecular association and laser-assisted electron-(excited) atom collisions. Annual report, 1 Jul 90-30 Jun 91  

SciTech Connect

The objective of the present research is to formulate, develop and implement new theoretical descriptions of the following atomic and molecular processes: Laser-Assisted Collisions: A new theory of laser-assisted electron-(excited) atom collisions, in which the dressed states of the atom A in the laser field are closely coupled and the Volkov states of the projectile electron in the laser field are included; Termolecular Recombination: The transport-collisional set of Master equations for Termolecular Recombination, A + B + M yields AB + M as a function of gas density has been developed by M. R. Flannery. Angular Momentum Changes in Collisions with excited atoms: Work is progressing on the cross sections for angular momentum changes, in heavy-particle and electron-atom (e-B) collisions where the target atom is initially in an excited state.

Flannery, M.R.

1991-08-23

336

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

SciTech Connect

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

Demeter, G.; Djotyan, G. P.; Soerlei, Zs.; Bakos, J. S. [Institute for Particle and Nuclear Physics of the Hungarian Academy of Sciences, Konkoly-Thege Miklos ut 29-33, H-1121 Budapest (Hungary)

2006-07-15

337

Coherently controlled emission from two atoms dressed via a standing wave laser field  

NASA Astrophysics Data System (ADS)

The influence of the standing wave amplitude on the resonance fluorescence of a three-level system of radiators is discussed. Great attention is devoted to the peculiarities of dressed states in the standing wave and the exchange integrals between two atoms situated in the anti-nodes or the nodes. The correlation functions of emitted photons at two dressed frequencies were obtained. It is shown that in the case when the distance between two atoms is smaller than the wavelength of the field, the emitted photons are strongly correlated. As was observed, for large values of laser field intensity, the control of spontaneous emission is possible at two frequencies as well as the atom-atom interaction process. The dependence of the fluorescent light spectrum as a function of the position of two atoms dressed in the standing wave is investigated.

Enaki, N. A.; Ciobanu, N.; Orszag, M.

2011-11-01

338

Measurement of the 6P_1\\/2,3\\/2 Atomic Lifetimes of Cesium using a Mode-Locked Laser  

Microsoft Academic Search

We will present a technique that employs a mode-locked Ti:Sapphire laser to measure the lifetimes of the 6P_1\\/2 and 6P_3\\/2 levels of cesium. A single pulse from the laser is used to excite atoms to the desired level in a thermal beam. A subsequent laser pulse is frequency-doubled and used to ionize the excited atoms. The ions are then counted

B. M. Patterson; T. Takekoshi; R. J. Knize; G. Brooke

2004-01-01

339

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

SciTech Connect

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.

Winefordner, J.D.

1991-12-31

340

Remark on polarization effects in small angle electron scattering by helium atoms in a CO2 laser field  

NASA Astrophysics Data System (ADS)

Referring to recent experiments by Wallbank and Holmes [Phys. Rev. A 48 (1993) R2515; J. Phys. B 27 (1994) 1221] on small angle, low energy electron scattering by helium atoms in a CO2 laser field, we investigate the possible influence of laser-induced target polarization and statistical fluctuations of the laser light on the observed non-linear cross section data.

Varró, S.; Ehlotzky, F.

1995-02-01

341

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

Microsoft Academic Search

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

Mark A. Shannon; Xianglei L. Mao; Alberto. Fernandez; Wing-Tat. Chan; Richard E. Russo

1995-01-01

342

Atomic Hydrogen and Molecular Carbon Emissions in Laser-Induced Breakdown Spectroscopy  

NASA Astrophysics Data System (ADS)

This article addresses hydrogen Balmer series measurements following laser-induced optical breakdown. Electron density on the order of 1 × 1025 m-3 can be inferred using H? Stark width and shift for plasma generated in 1 to 1.3 × 105 Pa, gaseous hydrogen. The H? line can be utilized for electron density up to 7 × 1023 m-3. Laser ablation of aluminium reveals limits of application of the Balmer series. Electron excitation temperature is inferred utilizing Boltzmann plot techniques that include H?, H? and H? atomic lines. H? and H? lines show presence of molecular carbon in a 2.7 and 6.5 × 105 Pa, expanding methane flow. Occurrence of superposition spectra in the plasma decay due to recombination or due to onset of chemical reactions necessitates consideration of both atomic and molecular emissions following laser-induced optical breakdown.

Parigger, Christian G.; Woods, Alexander C.; Rezaee, Mohammad R.

2012-12-01

343

High-fidelity local addressing of trapped ions and atoms by composite sequences of laser pulses.  

PubMed

A vital requirement for a quantum computer is the ability to locally address, with high fidelity, any of its qubits without affecting their neighbors. We propose an addressing method using composite sequences of laser pulses that dramatically reduces the addressing error in a lattice of closely spaced atoms or ions and at the same time significantly enhances the robustness of qubit manipulations. To this end, we design novel (to our knowledge) high-fidelity composite pulses for the most important single-qubit operations. In principle, this method allows one to beat the diffraction limit, for only atoms situated in a small spatial region around the center of the laser beam are excited, well within the laser beam waist. PMID:21479056

Ivanov, Svetoslav S; Vitanov, Nikolay V

2011-04-01

344

High-repetition-rate combustion thermometry with two-line atomic fluorescence excited by diode lasers.  

PubMed

We report on kilohertz-repetition-rate flame temperature measurements performed using blue diode lasers. Two-line atomic fluorescence was performed by using diode lasers emitting at around 410 and 451 nm to probe seeded atomic indium. At a repetition rate of 3.5 kHz our technique offers a precision of 1.5% at 2000 K in laminar methane/air flames. The spatial resolution is better than 150 microm, while the setup is compact and easy to operate, at much lower cost than alternative techniques. By modeling the spectral overlap between the locked laser and the probed indium lines we avoid the need for any calibration of the measurements. We demonstrate the capability of the technique for time-resolved measurements in an acoustically perturbed flame. The technique is applicable in flames with a wide range of compositions including sooting flames. PMID:19684826

Chrystie, Robin S M; Burns, Iain S; Hult, Johan; Kaminski, Clemens F

2009-08-15

345

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

SciTech Connect

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

Ciappina, Marcelo F.; Madsen, Lars Bojer [Max Planck Institute for the Physics of Complex Systems, Noethnitzer Strasse 38, D-01187 Dresden (Germany); Lundbeck Foundation Theoretical Center for Quantum System Research, Department of Physics and Astronomy, University of Aarhus, 8000 Aarhus C (Denmark)

2008-02-15

346

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

SciTech Connect

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

Argonov, V.Yu.; Prants, S.V. [Laboratory of Nonlinear Dynamical Systems, V.I.Il'ichev Pacific Oceanological Institute, Russian Academy of Sciences, 690041 Vladivostok (Russian Federation)

2005-05-15

347

INTERACTION OF LASER RADIATION WITH MATTER. LASER PLASMA: Production of doubly charged ions in the ionisation of Ba atoms in two laser fields  

NASA Astrophysics Data System (ADS)

The production of doubly charged ions is studied upon multiphoton ionisation of Ba atoms exposed simultaneously to two radiation fields: the fundamental radiation of a colour centre laser (? = 8800 — 8880 cm-1) and its second harmonic. A two-electron mechanism was shown to be responsible for the production of these ions.

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

2001-12-01

348

INTERACTION OF LASER RADIATION WITH MATTER. LASER PLASMA: Production of doubly charged ions in the ionisation of Ba atoms in two laser fields  

Microsoft Academic Search

The production of doubly charged ions is studied upon multiphoton ionisation of Ba atoms exposed simultaneously to two radiation fields: the fundamental radiation of a colour centre laser (omega = 8800 --- 8880 cm-1) and its second harmonic. A two-electron mechanism was shown to be responsible for the production of these ions. Bibtex entry for this abstract Preferred format for

I. I. Bondar; V. V. Suran

2001-01-01

349

Amplification of laser beams propagating through a collectionof strongly driven, Doppler-broadened two-level atoms  

Microsoft Academic Search

We investigate theoretically the amplification of a laser beam propagating through a collection of Doppler-broadened two-level atoms driven by an intense counterpropagating laser beam. Large amplification of the beam is predicted when the pump-beam Rabi frequency is comparable to the Doppler width of the atomic transition, even without including the effects of atomic recoil. The microscopic origin of the gain

William J. Brown; Jeff R. Gardner; Daniel J. Gauthier; R. Vilaseca

1997-01-01

350

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

NASA Astrophysics Data System (ADS)

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

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

2009-05-01

351

High-flux monochromatic ion and electron beams based on laser-cooled atoms  

NASA Astrophysics Data System (ADS)

We propose a source for high-brightness ion and electron beams based on the ionization of an effusive atomic beam which is transversely laser cooled and compressed. The very low transverse temperature (mK range) and the relative low density of the starting atomic sample ensure excellent initial conditions for obtaining bright and monochromatic charge sources. In contrast to the standard photoionization techniques used by similar sources, we utilize field ionization of Rydberg atoms. This approach allows a substantial reduction of the required laser power and copes differently with the problems of the energy spread created during the ionization process and of the stochastic space-charge effect. Theoretical modeling and prospective ideas of this emerging technology are given.

Kime, L.; Fioretti, A.; Bruneau, Y.; Porfido, N.; Fuso, F.; Viteau, M.; Khalili, G.; Šanti?, N.; Gloter, A.; Rasser, B.; Sudraud, P.; Pillet, P.; Comparat, D.

2013-09-01

352

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

NASA Astrophysics Data System (ADS)

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

Mourou, Gérard A.

2010-03-01

353

INTERACTION OF LASER RADIATION WITH MATTER. LASER PLASMA: Photoionisation of a helium atom involving autoionisation states coupled by a circularly polarised laser field  

NASA Astrophysics Data System (ADS)

The rotating wave approximation is used to obtain parametric expressions for the resonance cross section for the atomic ground state ionisation by linearly polarised probe radiation in the vicinity of an autoionisation state coupled resonantly to another autoionisation state through circularly polarised laser radiation. Calculations are made for the 2s2p 1P and 2s3d 1D states of the helium atom. It is shown that the structure of the photoionisation cross-section spectrum formed for circularly polarised laser radiation differs qualitatively from the structure formed in the case of linear polarisation. The dependence of this structure on the intensity and frequency of laser radiation and the direction of polarisation of the probe radiation is studied.

Gryzlova, E. V.; Magunov, A. I.; Rotter, I.; Strakhova, S. I.

2005-01-01

354

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

SciTech Connect

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

Demeter, G.; Dzsotjan, D.; Djotyan, G. P. [Institute for Particle and Nuclear Physics of the Hungarian Academy of Sciences, Konkoly-Thege Miklos ut 29-33, H-1121 Budapest (Hungary)

2007-08-15

355

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

NASA Astrophysics Data System (ADS)

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.

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

2013-01-01

356

Correlated multielectron dynamics in mid-infrared laser pulse interactions with neon atoms.  

PubMed

The multielectron dynamics in nonsequential triple ionization (NSTI) of neon atoms driven by mid-infrared (MIR) laser pulses is investigated with the three-dimensional classical ensemble model. In consistent with the experimental result, our numerical result shows that in the MIR regime, the triply charged ion longitudinal momentum spectrum exhibits a pronounced double-hump structure at low laser intensity. Back analysis reveals that as the intensity increases, the responsible triple ionization channels transform from direct (e, 3e) channel to the various mixed channels. This transformation of the NSTI channels leads to the results that the shape of ion momentum spectra becomes narrow and the distinct maxima shift towards low momenta with the increase of the laser intensity. By tracing the triply ionized trajectories, the various ionization channels at different laser intensities are clearly identified and these results provide an insight into the complex dynamics of the correlated three electrons in NSTI. PMID:24104018

Tang, Qingbin; Huang, Cheng; Zhou, Yueming; Lu, Peixiang

2013-09-01

357

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

SciTech Connect

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.

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

358

Light-pressure-induced nonlinear dispersion of a laser field interacting with an atomic gas  

SciTech Connect

We report on detailed studies of the effect of resonant light pressure on the optical response of an atomic gas to a single monochromatic laser field. In this very elementary situation of laser spectroscopy, the redistribution of atomic velocities that is induced by spontaneous light pressure leads to a novel contribution to the optical dispersion curve of the medium. This light-pressure-induced dispersion phenomenon displays a pronounced nonlinear dependence on the laser intensity. Moreover, for a given intensity, its strength is closely related to the laser beam diameter. As most important feature, this light-pressure-induced dispersion displays an even symmetry with respect to the optical detuning from line center. As a result, the total Doppler-broadened dispersion curve of the gas can become asymmetric, and a significant shift of the dispersion line center can occur. In addition to a detailed theoretical description of the phenomenon, we report on its experimental investigation on the {lambda}=555.6 nm {sup 1}{ital S}{sub 0}-{sup 3}{ital P}{sub 1} transition in atomic ytterbium vapor with the use of frequency-modulation spectroscopy. The experimental findings are in good quantitative agreement with theoretical predictions.

Grimm, R.; Mlynek, J. (Institute of Quantum Electronics, Swiss Federal Institute of Technology, (Eidgenoessische Technische Hochschule) Zuerich, CH-8093 Zuerich (Switzerland))

1990-09-01

359

Development of a Tellurium Frequency Standard for Laser Spectroscopy of Atomic Hydrogen.  

NASA Astrophysics Data System (ADS)

Available from UMI in association with The British Library. Doppler free spectra in Tellurium have been examined in the region of 486nm, close to one quarter of the hydrogen and deuterium 1S-2S transitions. The frequency of two selected lines have then been compared to the frequency of a 633nm HeNe laser actively stabilized to the 11-5R(127)'i' transition in I_sp{2}{127 }. Using a 150MHz plane/plane interferometer the two components were measured to a precision of 2 parts in 10^{10} (one standard deviation). These measured components constitute a useful transfer standard for the measurement of absolute frequencies of both Balmerbeta transitions and the 243nm two photon transitions in hydrogen and deuterium. A high density atomic hydrogen beam has been produced, suitable for laser spectroscopy on the 1S-2S transition. With a divergence half angle of 6 degrees the beam density was measured to be 5 times 10 ^{12} atoms cm^ {-3}, 25cm from the nozzle. This source was developed along with several systems for the selective detection of atomic hydrogen. A Tellurium Doppler-free spectral feature was also used to actively stabilize an Argon ion laser operating on the 488nm transition. The linewidth of the stabilised laser was measured to be 70MHz with a centre frequency of 614172.88GHz.

Girkin, John Michael

1987-09-01

360

Relativistic effects of the interaction of an intense femtosecond laser pulse with atomic clusters  

SciTech Connect

The effects of the interaction of an intense femtosecond laser pulse with large atomic clusters are considered. The pulse intensity is of the order of 10{sup 18} W cm{sup -2}. New effects appear when the magnetic component of the Lorentz force is taken into account. The second harmonic of laser radiation is generated. The second harmonic generation (SHG) efficiency is proportional to the square of the number of atoms in a cluster and the square of the laser radiation intensity. The resonance increase in the SHG efficiency at the Mie frequencies (both at the second-harmonic frequency and fundamental frequency) proved to be insignificant because of a fast passage through the resonance during the cluster expansion. The mechanisms of the expansion and accumulation of energy by electrons and ions in the cluster are discussed in detail. The energy accumulation by electrons mainly occurs due to stimulated inverse bremsstrahlung upon elastic reflection of the electrons from the cluster surface. The equations describing the cluster expansion take into account both the hydrodynamic pressure of heated electrons and the Coulomb explosion of the ionised cluster caused by outer shell ionisation. It is assumed that both inner shell and outer shell ionisation is described by the over-barrier mechanism. It is shown that atomic clusters are more attractive for generation of even harmonics than compared to solid and gas targets. (superstrong laser fields)

Rastunkov, V S; Krainov, Vladimir P [Moscow Institute of Physics and Technology (State University), Dolgoprudnyi, Moscow Region (Russian Federation)

2005-06-30

361

Collision of two atoms in laser radiation field with formation of Feshbach resonances  

NASA Astrophysics Data System (ADS)

Based on the simplest two-channel model we theoretically consider laser induced elastic and inelastic collision of two atoms with formation of Feshbach resonance. 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. We also study the laser-induced inelastic collision and its influence on the considered processes. In case of two-photon resonance between discrete vibrational molecular states the Feshbach resonances arise under action of magnetic field via Autler-Townes effect, while the laser-induced transition into the elastic-channel continuum is in this case absent. We obtain the cross-sections of elastic and inelastic scattering and show that quenching of resonance occurs under certain conditions. The obtained results can be employed in new studies of collisions of atoms, e.g., of alkali metal atoms, and for interpretation of new experiments in BECs.

Gazazyan, Emil A.; Gazazyan, Alfred D.; Chaltykyan, Vigen O.

2013-09-01

362

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

NASA Astrophysics Data System (ADS)

A pulsed high flux source of nearly monoenergetic atomic oxygen has been developed at Physical Sciences Inc. (PSI) to perform accelerated erosion testing of spacecraft materials in a simulated low earth orbit (LEO) environment. Molecular oxygen is introduced into an evacuated conical expansion nozzle at several atmospheres pressure through a pulsed molecular beam valve. A laser induced breakdown is generated in the nozzle throat by a pulsed CO2 TEA laser focused to intensities >~109 W/cm2. The resulting plasma is heated in excess of 20,000 K by the ensuing laser supported detonation wave, and then rapidly expands and cools. The nozzle geometry confines the expansion to promote rapid electron-ion recombination into atomic oxygen. The source generates an atomic oxygen beam with fluxes >~1018 atoms per pulse at 8+/-1.6 km/s with an ion content below 1% for LEO testing. For other applications the beam velocity can be varied over a range from 5 to 13 km/s by changing the discharge conditions. Materials testing has obtained the same surface oxygen enrichment in polyethylene samples as observed on the STS-8 mission, and scanning electron micrographs of the irradiated polymer surfaces reveal an erosion morphology similar to that obtained on low earth orbit.

Krech, Robert H.; Caledonia, George E.

1990-07-01

363

Development of two-color laser system for high-resolution polarization spectroscopy measurements of atomic hydrogen.  

PubMed

We have developed a high-spectral-resolution laser system for two-photon pump, polarization spectroscopy probe (TPP-PSP) measurements of atomic hydrogen in flames. In the TPP-PSP technique, a 243-nm laser beam excites the two-photon 1S-2S transition, and excited n=2 atoms are then detected by polarization spectroscopy of the n=2 to n=3 transition using 656-nm laser radiation. The single-frequency-mode 243 and 656-nm beams are produced using injection-seeded optical parametric generators coupled with pulsed dye amplifiers. The use of single-mode lasers allows accurate measurement of signal line shapes and intensities even with significant pulse-to-pulse fluctuations in pulse energies. Use of single-mode lasers and introduction of a scheme to select nearly constant laser energies enable repeatable extraction of important spectral features in atomic hydrogen transitions. PMID:22940950

Bhuiyan, A H; Satija, A; Naik, S V; Lucht, R P

2012-09-01

364

High-stability compact atomic clock based on isotropic laser cooling  

SciTech Connect

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.

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

365

Atomic antenna: Nonlinear scattering of a superatomic-intensity laser pulse  

NASA Astrophysics Data System (ADS)

A semiclassical model of high harmonic generation upon ionization by suppressing the atomic barrier is developed. The spreading of the wave packet of an ionized electron, which is chosen in the form of a Gaussian distribution, is considered. The quantum nature of the process is taken into account by the initial discrete level of the electron, and the finite wave packet spreading occurs in the continuum. After its detachment from the atom, the electron is assumed to be free and moving under the action of the laser pulse field and the Coulomb interaction of the electron with the atomic core can be treated as a perturbation. The radiation from the electron is calculated from its acceleration expressed in terms of the average force of interaction of the electron with the Coulomb center of the atom.

Golovinski, P. A.; Mikhailov, E. M.

2011-04-01

366

Stabilization of circular Rydberg atoms by circularly polarized infrared laser fields  

SciTech Connect

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

Askeland, S.; Soerngaard, S. A.; Nepstad, R.; Foerre, M. [Department of Physics and Technology, University of Bergen, N-5007 Bergen (Norway); Pilskog, I. [Department of Physics and Technology, University of Bergen, N-5007 Bergen (Norway); Laboratoire de Chimie Physique - Matiere et Rayonnement, Universite Pierre et Marie Curie - CNRS (UMR 7614), F-75231 Paris Cedex 05 (France)

2011-09-15

367

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

NASA Astrophysics Data System (ADS)

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

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

368

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

NASA Astrophysics Data System (ADS)

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

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

2012-12-01

369

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

NASA Astrophysics Data System (ADS)

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.

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

2009-03-01

370

Dipole Blockade at Foerster Resonances in High Resolution Laser Excitation of Rydberg States of Cesium Atoms  

SciTech Connect

High resolution laser excitation of np Rydberg states of cesium atoms shows a dipole blockade at Foerster resonances corresponding to the resonant dipole-dipole energy transfer of the np+np{yields}ns+(n+1)s reaction. The dipole-dipole interaction can be tuned on and off by the Stark effect, and such a process, observed for relatively low n(25-41), is promising for quantum gate devices. Both Penning ionization and saturation in the laser excitation can limit the range of observation of the dipole blockade.

Vogt, Thibault; Viteau, Matthieu; Zhao Jianming; Chotia, Amodsen; Comparat, Daniel; Pillet, Pierre [Laboratoire Aime Cotton, CNRS, Batiment 505, Campus d'Orsay, 91405 Orsay (France)

2006-08-25

371

Electron-beam-pumped high-pressure laser utilizing electronic transitions in the Kr atom  

SciTech Connect

An investigation was made of a high-power pulsed high-pressure laser utilizing 4d(1/2)/sup 0//sub 1/ --5p(3/2)/sub 2/ (lambda = 2.52 ..mu..) and 6p(1/2)/sub 1/--6s(3/2)/sup 0//sub 2/ (lambda = 3.07 ..mu..)= transitions in Kr atoms pumped by a fast-electron beam. When the volume of the active region was 10 liters and the pressure was 3.5 atm, the output energy of the laser reached 1.2 J and the efficiency was approx.1%.

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

1986-01-01

372

Modification of atomic structure of thin amorphous V2O5 films under UV laser irradiation  

NASA Astrophysics Data System (ADS)

Influence of ultra-violet radiation of the KrF laser (wave length 248 nm, pulse duration 20 ns) on atomic structure of amorphous vanadium pentoxide thin films, prepared by the pulsed laser deposition method, is studied. Calculations of the short-range order characteristics (radii and diffusiveness of coordination spheres, coordination numbers) were performed by the Finbak -Warren method. It is established that minimal structure unit of amorphous V2O5 film before and after irradiation is a strongly deformed oxygen octahedron. Distortions of tetragonal pyramids in the initial and modified film are different. Also, oxygen deficiency in a tetragonal pyramid is observed.

Cheremisin, B.; Loginova, S. V.; Velichko, A. A.; Putrolaynen, V. V.; Pergament, L.; Grishin, A. M.

2008-03-01

373

Electron impact excitation and ionization of laser-excited Na atoms  

Microsoft Academic Search

Electron spectra for 1.5 keV electron impact on Na are measured for one-step laser excitation to Na(3p32) and for two-step laser excitation to Na(4d52) or Na(5s). Auger states Na+ (2s2p6nl) with nl=3p, 4p, 5p; 5s, 6s, 7s; 4d, 5d, 6d are observed, most of them cannot be reached by ionization of the ground state atom Na(3s). State energies, shake probabilities,

A. Dorn; C. Winnewisser; M. Wetzstein; J. Nienhaus; A. N. Grum-Grzhimailo; O. I. Zatsarinny; W. Mehlhorn

1995-01-01

374

Honeycomb pattern formation by laser-beam filamentation in atomic sodium vapor.  

PubMed

We have observed transverse pattern formation leading to highly regular structures in both the near and far fields when a near-resonant laser beam propagates without feedback through an atomic sodium vapor. One example is a regular far-field honeycomb pattern, which results from the transformation of the laser beam within the vapor into a stable three-lobed structure with a uniform phase distribution and highly correlated power fluctuations. The predictions of a theoretical model of the filamentation process are in good agreement with these observations. PMID:11909401

Bennink, Ryan S; Wong, Vincent; Marino, Alberto M; Aronstein, David L; Boyd, Robert W; Stroud, C R; Lukishova, Svetlana; Gauthier, Daniel J

2002-02-27

375

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

PubMed

It has been an impedimental problem, for the laser detonation-type atom beam generator, that a poppet in the pulsed supersonic valve is rapidly eroded by the irradiation of powerful laser light and high temperature plasma. In order to operate the atom beam source for a long duration, a modification was made to hide the poppet from direct irradiation of laser and plasma. The alteration of device configuration resulted in great improvement in endurance of poppet more than 300,000 repetitions. Morphology of a polyimide film exposed to approximately 200,000 pulses of hyperthermal oxygen atom beam showed a shaglike carpet structure, which is a characteristic to that exposed to energetic oxygen atoms. A flux of the oxygen atom beam was estimated to be 5x10(14) atoms/cm2/pulse at a location of 30 cm away from the nozzle throat. PMID:18681693

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

2008-07-01

376

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

SciTech Connect

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.

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

377

Frequency response of an atomic resonance driven by weak free-electron-laser fluctuating pulses  

NASA Astrophysics Data System (ADS)

Motivated by recent experiments pertaining to the interaction of weak SASE-free-electron-laser (FEL) pulses with atoms and molecules, we investigate the conditions under which such interactions can be described in the framework of a simple phase-diffusion model with decorrelated atom–field dynamics. The nature of the fluctuations that are inevitably present in SASE-FEL pulses is shown to play a pivotal role in the success of the decorrelation. Our analysis is performed in connection with specific recent experimental results from FLASH in the soft x-ray regime.

Nikolopoulos, G. M.; Lambropoulos, P.

2013-08-01

378

Atomic plasma excitations in the field of a soft x-ray laser  

NASA Astrophysics Data System (ADS)

The interaction of atoms with short-wavelength radiation at ultra-high intensities is described by plasma excitation. In contrast to former works on optical radiation and ponderomotive motion of quasi-free electrons, the excitation of correlated and bound electrons is considered here. The ponderomotive motion of a free electron is included as a special case. Values for the energy transfer from the radiation field to an atom are obtained in fair agreement with the unexpectedly high charge states of xenon recently observed at the soft x-ray free-electron laser FLASH.

Richter, M.

2011-04-01

379

Tunable Diode Laser Absorption Spectroscopy of Metastable Atoms in Dusty Plasmas  

SciTech Connect

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

Hoang Tung Do; Hippler, Rainer [Institut fuer Physik, Felix-Hausdorff-Str. 6, 17489 Greifswald (Germany)

2008-09-07

380

Detection of very rare isotopes by laser collinear resonant ionization of fast atoms  

NASA Astrophysics Data System (ADS)

Results are presented of the work on the development of a method for detecting ultra rare isotopes, based on the collinear isotope-selective laser ionization of atoms in a fast bearn. The rare isotope3He was detected at a selectivity of 109 and isotope-selective ionization of krypton atoms was demonstrated. A scheme is suggested for detecting the rare radioactive isotopes85Kr and81Kr. The technique has been exploited for the measurement of hyperfine structures and isotope shifts of unstable Yb isotopes.

Kudryavtsev, Yu. A.

1992-10-01

381

Multiphoton ionization of atoms and ions by high-intensity X-ray lasers  

SciTech Connect

Coulomb corrections to the action function and rate of multiphoton ionization of atoms and ions in a strong linearly polarized electromagnetic field are calculated for high values of the Keldysh adiabaticity parameter. The Coulomb corrections significantly increase the ionization rate for atoms (by several orders of magnitude). An interpolation formula proposed for ionization rate is valid for arbitrary values of the adiabaticity parameter. The high accuracy of the formula is confirmed by comparison with the results of numerical calculations. The general case of elliptic polarization of laser radiation is also considered.

Popruzhenko, S. B., E-mail: poprz@theor.mephi.ru; Mur, V. D. [Moscow Institute of Engineering Physics (Russian Federation); Popov, V. S. [Institute for Theoretical and Experimental Physics (Russian Federation); Bauer, D. [Max-Plank Institut fuer Kernphysik (Germany)

2009-06-15

382

Atoms in strong fields and the quest for high intensity lasers  

NASA Astrophysics Data System (ADS)

In recent years, novel techniques have been developed to achieve high laser field intensities by shortening the duration of the pulses after several stages of amplification (by first stretching and subsequently compressing mode-locked laser pulses). A laser system built according to these principles at Imperial College is described. It is capable of reaching powers of ~ 1018 W cm-2 in pulse lengths of about 1 ps. The availability of field strengths 10 to 100 times as strong as the field experienced by the electron of the hydrogen atom in the first Bohr orbit opens up a new regime in the study of the interaction between light and matter. In particular, several effects, characteristic of very strong AC fields such as "above threshold ionisation" (ATI) high harmonic generation, etc are observed. Examples are given and their implications for atomic physics are discussed. Although such effects are novel and interesting in their own right, an important question which arises is the extent to which they may reveal new characteristics specific to the atom under study. Alternative possibilities are that most of the atomic features (correlations, shell structure, etc) are swamped by the effects of the strong field, or else that the atom is ionised before the strong field regime can even be reached. Some account of the controversies surrounding this question is given, and the importance of the dynamics is stressed. A theory is described which accounts for multiphoton excitation and ionisation by pulses of intense laser light in a generalised Landau-Zener model within a dressed atom basis of Floquet states. Different regimes of the interaction are classified, and a semi-classical limit is illustrated using action-angle plots of the Poincaré section. These reveal how excitation takes place across a separatrix between two modes of motion, and how the growth of chaotic trajectories near such a separatrix provides new paths leading to ionization. Our approach stresses the significance of the match between pulse rise time and the magnitude of the avoided crossings between dressed atom states for the atom or molecule concerned.

Connerade, J. P.; Dietz, K.; Hutchinson, M. H. R.

1995-01-01

383

Dynamical stabilization of atoms in intense laser pulses accessible to experiment  

NASA Astrophysics Data System (ADS)

We analyze the excitation of atoms by intense pulsed laser fields and describe a mechanism leading to effective dynamical stabilization at a photon energy below the unperturbed binding energy. At low and intermediate intensities, the atom is left in a coherent superposition of the initial state and a set of Rydberg states which is stable against ionization; this effect subsists for pulse durations presently accessible to experiment. At higher intensities, population is transferred through degenerate Raman coupling to Rydberg states of higher angular momentum.

Huens, Etienne; Piraux, Bernard

1993-02-01

384

Magnetic dichroism in K-shell photoemission from laser excited Li atoms.  

PubMed

Magnetic dichroism in the angular distribution has been demonstrated for single-electron photoemission from inner ns(2) subshells of gaseous atomic targets using the example of K-shell photoionization of polarized Li atoms laser prepared in the 1s(2)2p (2)P(3/2) 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. PMID:22181876

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

2011-11-14

385

Polarized atoms in a far-off-resonance yttrium-aluminum-garnet-laser optical dipole trap  

NASA Astrophysics Data System (ADS)

Optical trapping of radioactive atoms has a great potential in precision measurements for testing fundamental physics such as electric-dipole moment, atomic parity nonconservation, and parity-violating ? -decay correlation coefficients. One challenge that remains is to polarize the atoms to a high degree, and to measure the polarization of the sample and its evolution over time. In this paper we report on the polarization study of Rb atoms in a yttrium-aluminum-garnet (YAG)-laser optical dipole trap using both Faraday rotation polarimetry and resolved Zeeman spectroscopy techniques. We have prepared a cold cloud of polarized atoms and observed that its spin relaxation due to light scattering is suppressed in the YAG dipole trap. The spin polarization is further purified and maintained when the two-body collision loss rate between atoms in mixed spin states is greater than the one-body trap loss. These advancements are an important step toward a new generation of precision measurement with polarized trapped atoms.

Fang, F.; Wang, H.; Feldbaum, D.; Vieira, D. J.; Zhao, X.

2009-04-01

386

Polarized atoms in a far-off-resonance YAG laser optical dipole trap  

NASA Astrophysics Data System (ADS)

Optical trapping of radioactive atoms has a great potential in precision measurements for testing fundamental physics such as electric dipole moment (EDM), atomic parity non-conservation (PNC) and parity violating beta-decay correlation coefficients. One challenge that remains is to polarize the atoms to a high degree and to measure the polarization of the sample and its evolution over time. In this paper we report on the polarization study of Rb atoms in a yttrium-aluminum-garnett (YAG) laser optical dipole trap using both Faraday rotation polarimetry and resolved Zeeman spectroscopy techniques. We have prepared a cold cloud of polarized atoms and observed that its spin relaxation due to light scattering is suppressed in the YAG dipole trap. The spin polarization is further purified and maintained when the two-body collision loss rate between atoms in mixed spin states is greater than the one-body trap loss. These advancements are an important step towards a new generation of precision measurement with polarized trapped atoms.

Fang, Fang; Wang, Haiyan; Feldbaum, David; Vieira, David; Zhao, Xinxin

2009-05-01

387

The Vapour Density of Sodium  

Microsoft Academic Search

THERE is plenty of evidence in the literature to the effect that the vapour of sodium is monatomic. Robitsch (Ann. Physik, 38, 1027; 1912) determined the velocity of sound in the vapour at the boiling point and calculated the ratio of specific heats to be 1.68, and Taylor (Phys. Rev., 28, 576; 1926) found no evidence of molecules at pressures

W. H. Rodebush

1930-01-01

388

Wave packet dynamics of excited atomic electrons in intense laser fields  

SciTech Connect

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

Kulander, K.C. [Lawrence Livermore National Lab., CA (United States); Schafer, K.J. [Louisiana State Univ., Baton Rouge, LA (United States). Dept. of Physics and Astronomy

1996-08-01

389

Resonant-enhanced above-threshold ionization of atoms by XUV short laser pulses  

Microsoft Academic Search

Above-threshold ionization of atoms by XUV short laser pulses is investigated close to the resonant 1s-2p transitions. Both ab initio TDSE and a theoretical Coulomb-Volkov like theory are used to study the enhancement in the ionization probabilities. Our modified Coulomb-Volkov theory, fully accounting for the important 1s-2p transition is able to explain the spectrum as well as the total ionization

V. D. Rodríguez; P. A. Macri; D. G. Arbó

2009-01-01

390

Resonant-enhanced above-threshold ionization of atoms by XUV short laser pulses  

Microsoft Academic Search

Above-threshold ionization of atoms by XUV short laser pulses is investigated close to the resonant 1s–2p transitions. Both ab initio TDSE and a theoretical Coulomb–Volkov like theory are used to study the enhancement in the ionization probabilities. Our modified Coulomb–Volkov theory, fully accounting for the important 1s–2p transition is able to explain the spectrum as well as the total ionization

V. D. Rodríguez; P. A. Macri; D. G. Arbó

2009-01-01

391

Above-threshold ionization of atoms by resonant XUV laser pulses  

Microsoft Academic Search

Above-threshold ionization of atoms by XUV short laser pulses with frequencies close to the resonant 1s-2p transition is investigated. We present a theory based on a variational expression using trial wavefunctions for the final and the initial states. For the former we use a Coulomb-Volkov wavefunction, and for the latter a close-coupling solution of the time-dependent Schrödinger equation considering a

V. D. Rodríguez; D. G. Arbó; P. A. Macri

2011-01-01

392

Isotope Shift of Eleven Cesium Isotopes Determined by Atomic-Beam Laser Spectroscopy  

Microsoft Academic Search

Isotopes of 123-137Cs produced by spallation of lanthanum and separated in mass by the ISOLDE on-line facility have been transformed into an atomic beam which is illuminated with a tunable cw dye laser. From the sensitive detection of the optical resonance lines at 459 nm, the hyperfine structure of 123-132Cs, 137Cs, and 130mCs has been determined. The interpretation of isotope

G. Huber; F. Touchard; S. Buettgenbach; C. Thibault; R. Klapisch; S. Liberman; J. Pinard; H. T. Duong; P. Juncar; J. L. Vialle; P. Jacquinot; A. Pesnelle

1978-01-01

393

Measurement of the excited-atom density in a discharge in neon by laser resonance fluorescence  

Microsoft Academic Search

The method of laser resonance fluorescence has been used to study a steady-state gas-discharge plasma in a sealed-off inverted U-shaped tube with flat windows 8 mm in diameter at a neon pressure of 1.5 torr. Measured radial profiles of the relative density of excited atoms in the 2p 5 3s 3 P 0 1 state are presented for current densities

R. A. Akhmedzhanov; I. N. Polushkin; Ia. I. Khanin; V. V. Iazenkov

1982-01-01

394

Atomic high-order harmonic generation from a circularly polarized laser pulse  

NASA Astrophysics Data System (ADS)

We demonstrate theoretically that the high-order harmonic of an atom can be generated by a circularly polarized laser pulse. The harmonic spectrum shows a clear cutoff with an energy Ip + 2Up. In particular, the high-order harmonic generation comes from the multiple recombination of the ionized electron with non-zero initial velocity. These results are verified by the classical model theory and the time-frequency analysis of a harmonic spectrum.

Guo, Fu-Ming; Chen, Gao; Chen, Ji-Gen; Li, Su-Yu; Yang, Yu-Jun

2013-02-01

395

Photoelectron Spectra from Multiple Ionization of Atoms in Ultra-Intense Laser Pulses  

SciTech Connect

We address the question of the energy and angular distributions of the photoelectrons ejected from rare gas atoms submitted to ultra-intense infrared laser pulses, with peak intensities I{sub max}{approx}10{sup 18} W/cm{sup 2} . Several unsolved issues regarding the angular distributions of the photoelectrons are analyzed. We believe that our results should help to trigger new investigations.

Taieb, Richard; Veniard, Valerie; Maquet, Alfred

2001-07-30

396

Excitation of autoionizing states from laser excited and aligned atoms by electrons at intermediate energies  

Microsoft Academic Search

The investigation of resonance ionization by electron impact from laser excited and aligned atoms is extended to the domain of intermediate energies of the incident electrons. Calculations are performed in the distorted-wave approximation for the total excitation cross sections and anisotropy of the ejected electrons for the doublet of autoionizing resonances 2p53s3p2D32,52 in sodium. Predictions are made for a new

V. V. Balashov; E. I. Golokhov; A. N. Grum-Grzhimailo

1996-01-01

397

Angular anisotropy of autoionization electrons from sodium atoms simultaneously excited by laser and electron beams  

Microsoft Academic Search

First measurements of the angular distributions of autoionization electrons from 2p53s3p 2D5\\/2 state of Na atom excited by electron impact from the ground and laser excited 3p 2P3\\/2 state are reported. Strong anisotropy of the angular distribution is revealed, which has different signs for the excitation from the ground and excited states. Theoretical analysis based on the Born approximation is

A. Dorn; J. Nienhaus; M. Wetzstein; C. Winnewissert; W. Mehlhorn; V. V. Balashov; A. N. Grum-Grzhimailo; N. M. Kabachnik; O. I. Zatsarinny

1994-01-01

398

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

SciTech Connect

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.

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

399

Isotope shifts and hyperfine structure in polonium isotopes by atomic-beam laser spectroscopy  

NASA Astrophysics Data System (ADS)

Laser-induced fluorescence spectroscopy in a collimated atomic beam has been applied to determine isotope shifts and the hyperfine structure of an isotopic chain of the radioactive element polonium (200Po, 202Po, 204-210Po). The relative isotope shifts show a striking similarity with results for other elements in the vicinity of Pb, even reproducing details of the odd-even staggering.

Kowalewska, D.; Bekk, K.; Göring, S.; Hanser, A.; Kälber, W.; Meisel, G.; Rebel, H.

1991-08-01

400

Atomic collisions in the presence of laser radiation: Time dependence and the asymptotic wave function  

SciTech Connect

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

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

1982-09-01

401

Atomic inner-shell x-ray laser pumped by an x-ray free-electron laser  

SciTech Connect

We discuss possibilities of pumping an atomic inner-shell x-ray laser with an x-ray free-electron laser (XFEL). Self-consistent gain calculations show that with the first available XFEL, the Linac Coherent Light Source at Stanford, it will become possible to produce subfemtosecond x-ray pulses at intensities reaching 6x10{sup 16} W/cm{sup 2}. Small-signal gain calculations indicate that saturation of more than one lasing line is possible, resulting in temporally separated femtosecond x-ray pulses of different wavelengths. The presented lasing scheme creates broad capability for advancing the field of high-intensity ultrashort x-ray physics.

Rohringer, Nina; London, Richard [Lawrence Livermore National Laboratory, Livermore, California 94551 (United States)

2009-07-15

402

Direct writing of GaAs monolayers by laser-assisted atomic layer epitaxy  

NASA Astrophysics Data System (ADS)

Direct writing of GaAs epitaxial monolayers has been achieved by laser-assisted atomic layer epitaxy (LALE) technique on GaAs substrates. Sequential exposures of the substrate to trimethylgallium (TMG) and arsine (AsH3) were separated by periods of hydrogen purging to prevent mixing. Laser beam scanning of the samples took place either during the flow of TMG or AsH3. The selectively grown films at the one monolayer per cycle condition have a mirror-like surface and a flat top thickness profile. LALE has been realized at temperatures as low as 300 C and over a wide range of TMG flux and laser power densities. Photoluminescence results of the deposited films show that their quality are comparable to those achieved by conventional ALE.

Karam, N. H.; Liu, H.; Yoshida, I.; Bedair, S. M.

1988-04-01

403

Charge exchange of multiply charged laser plasma ions with rare-gas jet atoms  

SciTech Connect

The interaction of a gas jet (He, Ne, Xe) with the incident laser plasma from a solid target [B, (CH{sub 2}){sub n}, (CF{sub 4}){sub n}] removed by {approx}1 cm is investigated. Line spectra arising from the charge exchange of multiply charged plasma ions with rare-gas atoms are recorded in the multiply charged ions-gas interaction region. The ratios between the partial cross sections of the charge exchange with the production of these ions in excited states are determined from the relative intensities of the Balmer series transitions in BV and CVI ions. These results are compared with theoretical data. (interaction of laser radiation with matter. laser plasma)

Beigman, I L; Levashov, V E; Mednikov, K N; Pirozhkov, A S; Ragozin, E N; Tolstikhina, I Yu [P.N. Lebedev Physics Institute, Russian Academy of Sciences, Moscow (Russian Federation)

2007-11-30

404

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

SciTech Connect

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

Nafarizal, N. [Microelectronics and Nanotechnology-Shamsuddin Research Centre (MiNT-SRC), Faculty of Electrical and Electronic Engineering, University Tun Hussein Onn Malaysia, 86400 Batu Pahat, Johor (Malaysia); Takada, N. [Department of Electrical Engineering and Computer Science, Nagoya University, 464-8603 Chikusa-ku Nagoya (Japan); Sasaki, K. [Plasma Nanotechnology Research Center, Nagoya University, 464-8603 Chikusa-ku Nagoya (Japan)

2009-07-07

405

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

PubMed

We report on a low-noise diode laser oscillator at 972?nm actively stabilized to an ultrastable 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 intracavity electro-optical modulator. The fractional power in the carrier reaches 99.9%, which corresponds to an rms phase noise of ?(rms)2=1?mrad2 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 two-photon processes. PMID:22048397

Kolachevsky, N; Alnis, J; Parthey, C G; Matveev, A; Landig, R; Hänsch, T W

2011-11-01

406

Production of gallium atoms by excimer laser photolysis of trimethyl gallium  

SciTech Connect

The gas phase kinetics of group III elements such as gallium are important in possible chemically driven energy transfer lasers and in chemical vapor deposition processes in the electronics industry. Excimer laser photodissociation of volatile gallium compounds via multiple photon process provides, in principle, a convenient room temperature source of gallium atoms for study using laser photolysis-laser induced fluorescence techniques. In this paper, we report preliminary results of the multiple photon dissociation of trimethyl gallium at 193 nm. Prompt emission from a number of excited gallium states (5 /sup 2/S, 4 /sup 2/D, 6 /sup 2/S, 6 /sup 2/P/sup 0/, 5 /sup 2/D, and 4 /sup 4/P) has been observed. The time histories of the ground state (4/sup 2/P/sup 0//sub 1/2/) and the metastable (4 /sup 2/P/sup 0//sub 3/2/) have been measured using laser induced fluorescence. The resulting time profiles are complicated even in the absence of a reactant gas by the apparent production of ground state gallium at relatively long times (approx. 10 ..mu..s) after the excimer laser pulse. Possible mechanisms for this (i.e., radical reactions to produce gallium, energy transfer cascading from high lying metastable states, ionic processes, etc.) are being investigated. These results indicate that the photodissociation of trimethyl gallium at 193 nm is complex. Photolysis studies at other wavelengths and with other precursors are in progress to find a cleaner source of gas phase atomic gallium for kinetic studies. 20 refs., 7 figs.

Baughcum, S.L.; Oldenborg, R.C.; Winn, K.R.; Hof, D.E.

1985-03-01

407

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

Microsoft Academic Search

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 \\

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

2003-01-01

408

Laser-induced continuum structure and third harmonic generation in one- and two-valence-electron atoms  

Microsoft Academic Search

A model for calculating third harmonic generation (THG) in a near-resonantly coupled 4-level atomic system in the presence of laser-induced continuum structure (LICS) is formulated in terms of the time dependent density matrix elements which can be obtained by solving the time dependent density matrix equations for the atomic system interacting with laser pulses. The theory is applied to a

Zhang Jian

1991-01-01

409

A Laser-cooled Single-atom-on-demand Source For Si Quantum Computing  

NASA Astrophysics Data System (ADS)

A promising proposal by B. Kane for a scalable silicon quantum computer requires the placement of 31P atoms 20 nm apart and 10 nm below the surface in pure 28Si to 1 nm precision. This paper presents progress on a scheme for laser cooling and trapping single 31Si atoms in a magneto-optical trap (MOT), resonantly ionizing that one atom near threshold, and softly depositing the single 31Si+ ion in Si to nm precision at ~100 eV. A few hours after deposition, 31Si beta decays to 31P+. The hyperfine structure and isotope shifts of the 221.7 nm cooling transition for the stable isotopes of Si have been measured with precision for the first time. Sufficient power for the MOT at this wavelength has also been demonstrated. New autoionizing states near threshold have been found and ionization cross sections determined. The velocity distributions of laser ablated Si atoms have been measured, and unexpected results have been found. Construction of the MOT and design of the ion optics are underway.

Fairbank, W. M.; Lee, S. A.; Czajkowski, W. P.; Kluck, J. S.

2011-10-01

410

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

SciTech Connect

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

Metcalf, H.

1989-10-01

411

Coherent transient effects in laser-cooled and room temperature atoms  

NASA Astrophysics Data System (ADS)

This thesis presents several coherent transient effects with laser cooled (100 ?K) and room temperature (298K) 85Rb atoms. The understanding of interaction of nearly resonant radiation and matter, which is a fundamental problem of physics can be obtained by investigation of such transient phenomena. With the help of laser cooling techniques, an ideal two-level system is achieved. Atomic properties such as transition probabilities, branching ratio, and atomic coherence decay time have been measured using optical free induction decay (FID) and nutation. The first attempt to get Rabi oscillations using one of the coherent radiation of atomic polarization (FID) have been performed. Dressed state free induction decay newly developed have been observed and investigated with simple dressed state picture. One of new echo techniques recently suggested creating coherences between ground state magnetic sublevels was used to study velocity changing collision. At high buffer gas pressure, the revival of the coherent transient have been observed due to a kind of Dicke narrowing effect. The temporal modulation of this signal in the presence of magnetic fields has also been investigated with linear and circular polarized excitations. The velocity-changing collision cross section, diffusion coefficient and spin-flip collision cross section between Rb and noble gas were measured.

Shim, Unyob

1997-11-01

412

Compilation of atomic and molecular data revelant to gas lasers. volume viii. Technical report  

SciTech Connect

The present volume serves to update most of the areas covered in the previous documents. Such areas include all nuclear processes, and atomic collisions occurring at high energies, i.e., above about 100 eV impact energy. However, even in those areas where new data are not presented here, references are given to past volumes in order to facilitate access to the previous data. Another function of the present volume is to expand somewhat the scope of our data coverage, both with respect to atomic nd molecular structural properties and with respect to atomic collisions (by the latter term, we mean two- and three- body collisions between electrons, ions, atoms, molecules, and photons at impact energies sufficiently low that nuclear forces are unimportant). New species and sets of collision partners that have recently assumed importance are treated here, and other systems that may become important in the gas laser context are given attention. A significant amount of new material is also added to the chapter on surface impact phenomena, partly because of current interest in hollow-cathode lasers.

McDaniel, E.W.; Flannery, M.R.; Thomas, E.W.; Manson, S.T.; Gallagher, J.W.

1980-12-01

413

Highly efficient and isotope selective photo-ionization of barium atoms using diode laser and LED light.  

PubMed

We demonstrated a simple method to photo-ionize barium atoms using 791 nm diode laser together with 310 nm UV LED. It solved the bottle-neck problem of previous method using 791 nm diode laser and 337 nm N(2) laser, whose ionization rate was limited by the repetition rate of N(2) laser. Compared with previous method, it has advantages of high efficiency together with simple and cheap setups. By tuning the frequency of 791 nm laser to be resonant with the desired isotope, isotope selective photo-ionization has been realized. PMID:21935008

Wang, B; Zhang, J W; Gao, C; Wang, L J

2011-08-15

414

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

SciTech Connect

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

Jaron, A.; Kaminski, J.Z. [Institute of Theoretical Physics, Warsaw University, Hoza 69, 00-681 Warszawa (Poland)

1997-12-01

415

Observation of the cesium clock transition in laser-cooled atoms  

SciTech Connect

We have used the light from diode lasers to produce a nearly stationary (v approx. 15 cm/sec) sample of atomic cesium in optical molasses that is entirely in the F = 3 hyperfine state. In this sample we excite the 9.2-GHz 6S F = 3, m = 0 to F = 4, m = 0 clock transition. Most of the atoms remain for approx.20 msec in the 0.4-cm/sup 3/ observation region. We observe that transitions take place by monitoring the fluorescence when the atoms are illuminated with light tuned to the 6S F = 4 to 6P/sub 3/2/ F = 5 transition. Rabi resonance linewidths of less than 50 Hz are obtained.

Sesko, D.W.; Wieman, C.E.

1989-03-01

416

Determination of airblast atomized spray structure using state-of-the-art laser diagnostics  

NASA Astrophysics Data System (ADS)

This paper presents the results of an integrated qualitative-quantitative investigation into the detailed structure of an airblast atomized gas turbine spray at near atmospheric pressure and temperature conditions. Pre-filming airblast atomizer was studied with aviation kerosine as the test fuel. Phase Doppler anemometry was utilized to interrogate droplet size, velocity and number density characteristics while high-energy, pulsed laser sheet illumination technique enabled the visualization of the condition of the liquid at atomizer exit as well as variations in droplet concentration. The spray is found to be generally inhomogeneous in structure and the extent of size, velocity, number density inhomogeneity increases as the axial distance of the measurement plane diminishes. This has implications for the attainment of a satisfactory combustion-emissions performance from modern combustors with compact reaction zones.

Jasuja, A. K.; Tam, C. K.

1992-07-01

417

Millikelvin Reactive Collisions between Sympathetically Cooled Molecular Ions and Laser-Cooled Atoms in an Ion-Atom Hybrid Trap  

NASA Astrophysics Data System (ADS)

We report on a study of cold reactive collisions between sympathetically cooled molecular ions and laser-cooled atoms in an ion-atom hybrid trap. Chemical reactions were studied at average collision energies ?Ecoll?/kB?20mK, about 2 orders of magnitude lower than has been achieved in previous experiments with molecular ions. Choosing N2++Rb as a prototypical system, we find that the reaction rate is independent of the collision energy within the range studied, but strongly dependent on the internal state of Rb. Highly efficient charge exchange four times faster than the Langevin rate was observed with Rb in the excited (5p) P3/22 state. This observation is rationalized by a capture process dominated by the charge-quadrupole interaction and a near resonance between the entrance and exit channels of the system. Our results provide a test of classical models for reactions of molecular ions at the lowest energies reached thus far.

Hall, Felix H. J.; Willitsch, Stefan

2012-12-01

418

EFFECTS OF LASER RADIATION ON MATTER. LASER PLASMA: Characteristics of the scattering of neutral atoms by two counterpropagating pulsed optical fields  

NASA Astrophysics Data System (ADS)

The scattering of neutral sodium atoms by a strong field of two counterpropagating (incident on and reflected from a mirror) short laser pulses was used in an experimental investigation of a stimulated radiation pressure. The reasons for the anomalous frequency structure in the scattering of atoms were identified. The oscillatory nature of the dependence of the scattering on the detuning from resonance was found to be significant in strong laser radiation fields. The oscillation period depended on the distance between the reflecting mirror and the atomic beam.

Grinchuk, V. A.; Grishina, I. A.; Kuzin, E. F.; Nagaeva, M. L.; Ryabenko, G. A.; Yakovlev, V. P.

1994-04-01

419

A Simple LIBS (Laser-Induced Breakdown Spectroscopy) Laboratory Experiment to Introduce Undergraduates to Calibration Functions and Atomic Spectroscopy  

ERIC Educational Resources Information Center

|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…

Chinni, Rosemarie C.

2012-01-01

420

Characterization of laser seeding by use of group-velocity dispersion in an atomic-vapor filter  

Microsoft Academic Search

A method for measuring laser seeding efficiencies by use of group-velocity dispersion has been developed. By tuning the laser near a resonance in an atomic-vapor filter it is possible to temporally decouple the seeded (narrow-band) light from the unseeded (broadband) light. We measured a seeding efficiency of 99.8% of the third harmonic of an injection-seeded Ti:sapphire laser. A model for

Azer P. Yalin; Peter F. Barker; Richard B. Miles

2000-01-01

421

Al-free active region (? = 852nm) DFB laser diodes for atomic clocks and interferometry applications  

NASA Astrophysics Data System (ADS)

Atomic clocks will be used in the future European positioning system Galileo. Among them, the optically pumped clocks provide a better alternative with comparable accuracy for a more compact system. For these systems, diode lasers emitting at 852nm are strategic components. The laser in a conventional bench for atomic clocks presents disadvantages for spatial applications. A better approach would be to realise a system based on a distributed-feedback laser (DFB). We have developed the technological foundations of such lasers operating at 852nm. These include an Al-free active region, a single spatial mode waveguide and a DFB structure. The device is a separate confinement heterostructure with a GaInP large optical cavity and a single compressive-strained GaInAsP quantum well. The broad-area laser diodes are characterised by low internal losses (<3 cm-1), a high internal efficiency (94%) and a low transparency current density (100A/cm2). For an AR/HR coated 2mm long around 4?m wide ridge diode, we obtain a low threshold current (40mA) and a high slope efficiency (0.90W/A). With the Fabry-Perot laser structure we obtain 852nm wavelength at 145mW (I=200mA, 15°C). We measure an optical power of 230mW (I=280mA) in a single spatial mode with the beam quality parameter M2=1.3. With the DFB laser structure, we have obtained single frequency (side-mode-suppression ratio : SMSR over 30dB) and single mode lasers (M2<1.5) with a high optical power. An optical power of 150mW was obtained at 854nm wavelength and 20°C for AR-HR coated 2mm long, ~ 4?m wide devices. At this power, both near and far fields in the slow axis are gaussian-shaped with respective full widths at 1/e2 of 8?m and 9.2° respectively, corresponding to a single spatial mode emission with a beam quality parameter M2=1.29. The SMSR is over 30dB. Furthermore, the preliminary results of the linewidth obtained with a Fabry-Perot interferometer give a value of less than 2MHz.

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

2006-04-01

422

Near resonant absorption by atoms in intense fluctuating laser fields. Final report  

SciTech Connect

The objective of this program was to make quantitative measurements of the effects of higher-order phase/frequency correlations in a laser beam on nonlinear optical absorption processes in atoms. The success of this program was due in large part to a unique experimental capability for modulating the extracavity beam of a stabilized ({approx_lt}200 kHz) continuous-wave laser with statistically-well-characterized stochastic phase (or frequency) fluctuations, in order to synthesize laser bandwidths to {approximately}20 MHz (depending on noise amplitude), with profiles variable between Gaussian and Lorentzian (depending on noise bandwidth). Laser driven processes investigated included the following: (1) the optical Autler-Towns effect in the 3S{sub 1/2} (F = 2, M{sub F} = 2) {yields} 3P{sub 3/2} (F = 3, M{sub F} = 3) two- level Na resonance, using a weak probe to the 4D{sub 5/2} level; (2) the variance and spectra of fluorescence intensity fluctuations in the two-level Na resonance; (3) the Hanle effect in the {sup 1}S{sub 0} {minus} {sup 3}P{sub 1}, transition at {lambda} = 555.6 nm in {sup 174} Yb; (4) absorption (and gain) of a weak probe, when the probe is a time-delayed replica of the resonant (with the two-level Na transition) pump laser; and (5) four-wave-mixing in a phase-conjugate geometry, in a sodium cell, and, finally, in a diffuse atomic sodium beam. The experimental results from these several studies have provided important confirmation of advanced theoretical methods.

Smith, S.J.

1994-01-01

423

Atomic Absorption and Atomic Fluorescence Methods of Analysis: Their Merits and Limitations  

Microsoft Academic Search

Atomic absorption methods involve conversion of the sample into an atomic vapour and measurement of the absorbance of this vapour at a specific wavelength, characteristic of the analyte element. Flames and electrical furnances are the most widely used means of atomization. Flame atomic absorption methods are rapid and precise, can be carried out on simple equipment, and are applicable to

Alan Walsh; J. C. Riviere; T. S. West; A. F. Fell

1982-01-01

424

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

SciTech Connect

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

Yarovitsky, Alexander V; Vasil'ev, V V; Velichansky, Vladimir L; Razin, Oleg A; Sherstov, Ivan V [P.N. Lebedev Physics Institute, Russian Academy of Sciences, Moscow (Russian Federation); Prudnikov, O N [Novosibirsk State University, Novosibirsk (Russian Federation); Taichenachev, Aleksei V; Yudin, Valerii I [Institute of Laser Physics, Siberian Branch, Russian Academy of Sciences, Novosibirsk (Russian Federation)

2004-04-30

425

Comment on ''Generation of cold low divergent atomic beam of indium by laser ablation'' [Rev. Sci. Instrum. 76, 113302 (2005)  

SciTech Connect

We present measurements of the velocity distribution of calcium atoms in an atomic beam generated using a dual-stage laser back-ablation apparatus. Distributions are measured using a velocity selective Doppler time-of-flight technique. They are Boltzmann-like with rms velocities corresponding to temperatures above the melting point for calcium. Contrary to a recent report in the literature, this method does not generate a subthermal atomic beam.

Denning, A.; Booth, A.; Lee, S.; Amonson, M.; Bergeson, S. D. [Department of Physics and Astronomy, Brigham Young University, Provo, Utah 84602 (United States)

2009-04-15

426

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

Microsoft Academic Search

Single frequency and single spatial mode diode lasers emitting at 852nm are strategic components for systems such as atomic clocks (positioning systems for navigation, in space atomic clock like Galileo or Pharao (cold atom), measurement of fundamental constants), or interferometry applications. We have developed the technological foundations of lasers at 852nm to address these different applications. These include an Al

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

2007-01-01

427

Compilation of atomic and molecular data relevant to gas lasers. volume VII. Technical report  

SciTech Connect

This volume and the succeeding volume are the seventh and the eighth in a series that presents data relevant to research and development in the field of gas lasers. The present volumes serve to update most of the areas covered in the previous documents. Those areas not treated here are considered to have been adequately dealt with earlier, as far as immediate data needs are concerned. However, even in those areas where new data are not presented here, references are given to past volumes in order to facilitate access to the previous data. Another function of the present work is to expand somewhat the scope of our data coverage, both with respect to atomic and molecular structural properties and with respect to atomic collisions. New species and sets of collision partners that have recently assumed importance are treated here, and other systems that may become important in the gas laser contex are given attention. A significant amount of new material is also added to the chapter on surface impact phenomena, partly because of current interest in hollow-cathode lasers.

McDaniel, E.W.; Flannery, M.R.; Thomas, E.W.; Manson, S.T.; Gallagher, J.W.

1980-12-01

428

Hook spectroscopy as an atomic number density diagnostic applied to laser-ablated copper plasmas  

SciTech Connect

Hook spectroscopy has been used to determine the absolute number density of ground state copper atoms in laser-ablated plasma plumes. An ablation laser power flux of {approximately} 1.5 GW/cm{sup 2} is applied to a solid copper target in a background gas, producing a plasma plume suitable for studying homogeneous copper vapor condensation. Density is measured at post-ablation time delays ranging from 10 {mu}s to 3 ms with 25 torr of argon as the background gas. Planar laser-induced fluorescence (PLEF) images containing relative density information are used in conjunction with the hook spectra to resolve spatially the absolute density within the plume. Copper atom densities thus measured ranged from 1.9 {times} 10{sup 15} cm{sup {minus}3} at a delay of 10 {mu}s to 2.7 {times} 10{sup 13} cm{sup {minus}3} at 3 ms delay in 25 torr of argon The decrease in density is due to the condensation of copper vapor to form fine particulate. As a combustion diagnostic, the hook method may prove extremely useful for the determination of metal impurity density in coal fired flames as well as a single -- shot OH density and temperature diagnostic.

Zerkle, D.K.; Sappey, A.D.; Gamble, T.K.

1993-11-01

429

Theory of laser-assisted Auger processes generated by ultrashort XUV pulses in atoms  

NASA Astrophysics Data System (ADS)

A non-stationary quantum mechanical theory of the laser-assisted Auger process in atoms excited by an ultrashort (attosecond) electromagnetic pulse in the field of a few-cycle strong optical laser pulse is considered. The theory is based on numerically solving the time-dependent Schrödinger equation describing Auger decay. An approach is suggested which can be applied for the case of low-energy Auger electrons when it is necessary to take accurately into account the electron interaction with both the laser field and the field of the residual ion. We show that the amplitude of the process can be presented as a coherent sum of contributions from the corresponding Auger decays at consecutive moments of time. This presentation saves considerable computer time in numerical calculations of the Auger spectrogram. It also demonstrates that the Auger electrons emitted at different moments are coherent. As an example, the electron spectra for laser-assisted Auger decay are calculated for the MNN transition in Kr. The variation of the Auger spectra with time delay between the two pulses is discussed. The results are compared with those obtained within the strong-field approximation.

Kazansky, A. K.; Sazhina, I. P.; Kabachnik, N. M.

2011-11-01

430

Optimal Control of Atomic, Molecular and Electron Dynamics with Tailored Femtosecond Laser Pulses  

NASA Astrophysics Data System (ADS)

With the invention of the laser, the dream was realized to actively exert control over quantum systems. Active control over the dynamics of quantum mechanical systems is a fascinating perspective in modern physics. Cleavage and creation of predetermined chemical bonds, selective population transfer in atoms and molecules, and steering the dynamics of bound and free electrons have been important milestones along this way. A promising tool for this purpose is available with femtosecond laser technologies. In this chapter we review some of our work on adaptive femtosecond quantum control where a learning algorithm and direct experimental feedback signals are employed to optimize user-defined objectives. Femtosecond laser pulses are modified in frequency-domain pulse shapers, which apart from phase- and intensity-modulation can also modify the polarization state as a function of time. We will highlight the major advances in the field of optimal control by presenting our own illustrative experimental examples such as gas-phase and liquid-phase femtochemistry, control in weak and strong laser fields, and control of electron dynamics.

Brixner, Tobias; Pfeifer, Thomas; Gerber, Gustav; Wollenhaupt, Matthias; Baumert, Thomas

431

The halogen atom/metal trimer CW laser-engineering concept overview  

SciTech Connect

A halogen atom/metal vapor laser is discussed in terms of CW power and performance. Fluorine and sodium represent surrogates for the halogen and metal species; other combinations are possible. Since lasing may occur from a variety of excited electronic states, operation is expected to be broadly dispersed over the visible and near UV wavelength regions. The device is a low pressure, supersonic mixing laser that resembles the HF/DF CW laser, e.g., separate plenums are utilized for the fluorine and sodium vapors, and each plenum feeds a nozzle array. Sodium trimer formation begins in the nozzle and continues inside the laser cavity. The design of this nozzle is particularly important; the concept of controlled condensation is introduced. Downstream of the nozzle bank, the two vapor streams mix and the F-Na3 reaction pumps several electronically excited states that have gain in the blue-green region. Estimates are given for power per unit mass flow rate and power per unit nozzle bank cross-sectional area. 15 refs.

Emanuel, G.; Jacobs, T.A. (Oklahoma, University, Norman (United States))

1992-07-01

432

Laser pumping Cs atom magnetometer of theory research based on gradient tensor measuring  

NASA Astrophysics Data System (ADS)

At present, due to space exploration, military technology, geological exploration, magnetic navigation, medical diagnosis and biological magnetic fields study of the needs of research and development, the magnetometer is given strong driving force. In this paper, it will discuss the theoretical analysis and system design of laser pumping cesium magnetometer, cesium atomic energy level formed hyperfine structure with the I-J coupling, the hyperfine structure has been further split into Zeeman sublevels for the effects of magnetic field. To use laser pump and RF magnetic field make electrons transition in the hyperfine structure to produce the results of magneto-optical double resonance, and ultimately through the resonant frequency will be able to achieve accurate value of the external magnetic field. On this basis, we further have a discussion about magnetic gradient tensor measuring method. To a large extent, it increases the magnetic field measurement of information.

Yang, Zhang; Chong, Kang; Wang, Qingtao; Lei, Cheng; Zheng, Caiping

2011-02-01

433

Refraction and absorption of x rays by laser-dressed atoms.  

SciTech Connect

X-ray refraction and absorption by neon atoms under the influence of an 800 nm laser with an intensity of 10{sup 13} W/cm{sup 2} is investigated. For this purpose, we use an ab initio theory suitable for optical strong-field problems. Its results are interpreted in terms of a three-level model. On the Ne 1s {yields} 3p resonance, we find electromagnetically induced transparency (EIT) for x rays. Our work opens novel perspectives for ultrafast x-ray pulse shaping.

Buth, C.; Santra, R.; Young, L. (Chemical Sciences and Engineering Division)

2010-06-01

434

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

SciTech Connect

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.

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

435

Numerical observation of the rescattering wave packet in laser-atom interactions.  

PubMed

We present a full-quantum nonperturbative method to study the electron rescattering process in the intense laser-atom interactions. We separate the ionized wave function from the background by solving the time-integral equation. Imposing the incoming boundary condition on the wave function, we reproduce the motion of the rescattering wave packet predicted by the rescattering theory. Our calculated rescattering energies differ significantly from the semiclassical ones. The difference would be substantial for the evaluation of the rescattering induced dynamics such as the molecular dissociation. PMID:17931003

Tong, X M; Watahiki, S; Hino, K; Toshima, N

2007-08-28

436

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

SciTech Connect

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

Knuffman, B.; Steele, A. V.; McClelland, J. J. [Center for Nanoscale Science and Technology, National Institute of Standards and Technology, Gaithersburg, MD 20899 (United States); Orloff, J.; Maazouz, M. [FEI Company, Hillsboro, OR 97124 (United States)

2011-11-10

437

Electron-Helium Atom Collisions in the Presence of a Bichromatic Laser Field  

NASA Astrophysics Data System (ADS)

The differential cross section (DCS) for electron-helium atom collisions in the presence of a bichromatic CO2 laser field is investigated as a function of the scattering angle ? by employing first-Born approximation (FBA) with a simple screening electric potential. We discuss in detail the influence of the scattering geometry, the photon energy and the number of photons exchanged on the DCSs. These illustrate that the three factors have important effects on the elastic scattering and the screening electric potential is effective.

Zhu, Zun-Lue; Liang, Ming-Chao; Sun, Jin-Feng

2008-08-01

438

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

NASA Astrophysics Data System (ADS)

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

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

2010-11-01

439

Interaction of a model atom exposed to strong laser pulses: Role of the Coulomb potential  

NASA Astrophysics Data System (ADS)

With the help of the solution of the time-dependent Schrödinger equation in momentum space, we study the above-threshold ionization spectrum resulting from the interaction of atomic hydrogen with an infrared and XUV short laser pulses. Our calculations are based on a model where the kernel of the nonlocal Coulomb potential is replaced by a finite sum of N symmetric separable potentials, each of them supporting one bound state of atomic hydrogen. Here, we consider only the case of 1s, 2s, and 2p states. Thus, the theory fully accounting for the important 1s-2p transition, explains the photoelectron spectrum as well as the total ionization probability for the resonant case. We compared the results given by our theory with the numerical solutions of the time-dependent Schrödinger equation.

Tetchou Nganso, Hugues Merlain; Hamido, Aliou; Kwato Njock, Moïse Godfroy; Popov, Yuri Vladimirovich; Piraux, Bernard

2013-01-01

440

Total ionization rates and ion yields of atoms at nonperturbative laser intensities  

NASA Astrophysics Data System (ADS)

We investigate a simply corrected Keldysh-Faisal-Reiss (KFR) rate formula for laser-induced ionization of atoms in the nonperturbative intensity domain. Predictions of the formula are compared, first, with ab initio Floquet calculations, which show good agreement in the nonperturbative intensity domain for not too short wavelengths. Second, they are found to agree with the results of numerical simulations for the H atom, provided the pulse lengths are not shorter than three field cycles, so that the adiabatic rate becomes a valid parameter. Finally, total single-ionization yields predicted by the present model are compared with 36 different experimental data sets for He, Ne, Ar, Kr, and Xe, covering both linear and circular polarizations, and different wavelengths, pulse durations, and intensities; the results show a remarkable overall agreement with the data.

Becker, A.; Plaja, L.; Moreno, P.; Nurhuda, M.; Faisal, F. H.

2001-08-01

441

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

DOEpatents

Laser sustained discharge apparatus for the production of intense beams of high kinetic energy atomic species. A portion of the plasma resulting from a laser sustained continuous optical discharge which generates energetic atomic species from a gaseous source thereof is expanded through a nozzle into a region of low pressure. The expanded plasma contains a significant concentration of the high kinetic energy atomic species which may be used to investigate the interaction of surfaces therewith. In particular, O-atoms having velocities in excess of 3.5 km/s can be generated for the purpose of studying their interaction with materials in order to develop protective materials for spacecraft which are exposed to such energetic O-atoms during operation in low earth orbit.

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

1988-01-01

442

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

DOEpatents

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.

Cross, J.B.; Cremers, D.A.

1986-01-10

443

Sensitized and heavy atom induced production of acenaphthylene triplet: A laser flash photolysis study  

SciTech Connect

The triplet state of acenaphthylene has been examined by nanosecond laser flash photolysis using sensitization and heavy atom perturbation techniques. Although acenaphthylene does not form any observable triplet upon direct flash excitation, a transient with microsecond lifetime ({lambda}{sub max} = 315 nm) is observable when a solution of the sample is excited by sensitizers (benzophenone, thioxanthone, benzil). This transient is ascribed to the triplet of acenaphthylene on the basis of its quenching behavior toward oxygen, ferrocene, azulene, and {beta}-carotene. Quantitative data concerning the triplet-triplet absorption and quenching constants are presented. The triplet energy is estimated to lie between 46 and 47 kcal/mol. The triplet can also be produced by direct excitation in solvents containing heavy atoms (ethyl bromide, ethyl iodide). The triplet yield is found to increase with an increase of the amount of the heavy atom containing solvent. No saturation limit is obtained. These facts together with the effect of heavy atoms on the T{sub 1} {yields} S{sub 0} process allow the differing behavior of ethyl bromide and ethyl iodide on the photodimerization process of acenaphthylene to be explained. Triplet-state parameters (extinction coefficient and triplet yield) have been estimated in these solvents by the energy-transfer technique and actinometry.

Samanta, A.; Fessenden, R.W. (Univ. of Notre Dame, IN (USA))

1989-07-27

444

Stability of the far-off-resonance dipole-atom trap with superimposed laser cooling  

NASA Astrophysics Data System (ADS)

The stability region of a far-off-resonance dipole-atom trap (FORT) composed of a single trapping laser beam and a ?+-?- cooling field configuration is discussed for the simplest (3+5)-level atomic scheme. The ultimate parameters of the stable FORT are evaluated by extending the theory of the FORT to the fourth-order rate-equation approximation. It is shown that when the detuning of the trapping field is much larger than the detuning of the cooling field, and with a proper choice of a low optical saturation due to the trapping and cooling field, the mixing of the one-photon processes responsible for the trapping potential with the two-photon processes responsible for the sub-Doppler cooling of atoms in the trap remains weak. It is concluded that the FORT with superimposed cooling fields possesses a stability region where the diffusive heating is suppressed by the cooling processes. Numerical evaluations of the stability region for a model of a (3+5)-level atom are given.

Jun, Jin Woo; Minogin, V. G.

2001-08-01

445

Development of laser-plasma diagnostics using ultrafast atomic-scale dynamics. 96-ERD-046 final report  

SciTech Connect

Ultrashort laser pulse systems allow examination of intense, ultrafast laser-plasma interactions. More specifically, intense laser irradiation can induce short xuv/x-ray bursts from the surface of condensed phase targets. Ultrafast xuv/x-ray detection is needed to understand laser-plasma interactions in this dynamic regime. Support of the Stockpile Stewardship and Management Program requires this critical understanding. Our effort here has been to extend understanding of atomic-scale dynamics in such environments with the goal of developing next generation ultrafast xuv/x-ray diagnostics where the sensors will be the atoms and ions themselves and the time resolution will approach that of the induced atomic transitions ({approx} a few femtoseconds). Pivotal contributions to the rapidly developing field of highly nonperturbative interactions of ultrashort pulse lasers with atoms/ions have been made at this laboratory. In the visible/infrared wavelength regions the temporal and spectral content of ultrashort laser pulses are now reliably monitored within a single pulse using frequency resolved optical gating (FROG) which is based on rapid nonlinear optical processes such as the Kerr effect. New applications of this basic concept are still being developed. Corresponding detection for the xuv/x-ray wavelengths does not exist and is urgently needed in many laboratory programs. The FROG technique cannot be applied in the xuv/x-ray region. Current x-ray streak camera technology is limited to {approx}0.5 picosecond resolution.

Bolton, P.R.; Kulander, K.C. [Lawrence Livermore National Lab., CA (United States); Boreham, B.W. [Central Queensland Univ., Rockhampton, QLD (Australia). Dept. of Applied Physics

1997-03-01

446

Measurement of the neutral vapour density decay following the extinction of a high-current vacuum arc between copper electrodes  

Microsoft Academic Search

The decay of neutral copper vapour density which follows the extinction of a high current (2-11 kA) vacuum arc between copper electrodes has been measured. The results show that during the period 1-8 ms from current zero the vapour density decays at least an order of magnitude slower than expected on the assumption that vapour atoms generated by the arc

J. E. Jenkins; J. C. Sherman; R. Webster; R. Holmes

1975-01-01

447

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)

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.

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

448

Angular distribution of atoms ejected by laser ablation of different metals  

SciTech Connect

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.

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

449

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

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.

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

2013-01-01

450

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  

NASA Astrophysics Data System (ADS)

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.

Khan, Enamul H.; Langford, S. C.; Dickinson, J. T.; Boatner, L. A.

2013-08-01

451

Comparison of recoil-induced resonances and the collective atomic recoil laser  

NASA Astrophysics Data System (ADS)

The theories of recoil-induced resonances (RIR) [J. Guo, P. R. Berman, B. Dubetsky, and G. Grynberg, Phys. Rev. A 46, 1426 (1992)] and the collective atomic recoil laser (CARL) [R. Bonifacio and L. De Salvo, Nucl. Instrum. Methods Phys. Res. A 341, 360 (1994)] are compared. Both theories can be used to derive expressions for the gain experienced by a probe field interacting with an ensemble of two-level atoms that are simultaneously driven by a pump field. It is shown that the underlying formalisms of the RIR and CARL are equivalent. Differences between the RIR and CARL arise because the theories are typically applied for different ranges of the parameters appearing in the theory. The RIR limit is one in which the time derivative of the probe field amplitude, dE2/dt, depends locally on E2(t) and the gain depends linearly on the atomic density, while the CARL limit is one in which dE2/dt=?t0f(t,t')E2(t')dt', where f is a kernel, and the gain has a nonlinear dependence on the atomic density. Validity conditions for the RIR or CARL limits are established in terms of the various parameters characterizing the atom-field interaction. The probe gain for a probe-pump detuning equal to zero is analyzed in some detail, in order to understand how gain arises in a system which, at first glance, appears to have a symmetry that would preclude the possibility for gain. Moreover, it is shown that these calculations, carried out in perturbation theory, have a range of applicability beyond the recoil problem. Experimental possibilities for observing CARL are discussed.

Berman, P. R.

1999-01-01

452

Laser-induced plasma characterization using line profile analysis of chromium neutral atom and ion transitions  

NASA Astrophysics Data System (ADS)

In this paper, line profile analysis of several Cr transitions was carried out for characterization of a laser-induced plasma. The plasma was generated on a metallic alloy (nominal Cr concentration 29.7%) in air at atmospheric pressure by using an infrared Nd:YAG laser. The emission intensities of 24 Cr I lines and 25 Cr II lines were measured spatially integrated along the line-of-sight with good resolution. Their line profiles were analyzed applying a computational fitting algorithm under a framework of a homogeneous plasma in thermodynamic equilibrium. The effects of self-absorption and spatial inhomogeneity were taken into account. The plasma temperature and the parameters Nl (the atom/ion concentration times the length of the plasma along the line-of-sight) were accurately determined, and the electron density was estimated. The results were properly interpreted under the employed approach, demonstrating the important influence of the issues investigated on characterizing the physical state of laser-induced plasmas.

Díaz Pace, Diego M.

2013-11-01

453

Efficiency of generation of highly ionised atoms under resonance absorption of CO{sub 2}-laser radiation  

SciTech Connect

We consider the generation of beams of highly ionised atoms in solid targets irradiated with CO{sub 2}-laser pulses. We present experimental results on generation of Mg and Pb ions from laser plasma at a radiation flux density q Almost-Equal-To 10{sup 14} W cm{sup -2}. We have developed a theoretical model describing the plasma heating by CO{sub 2}-laser radiation at a high pulse intensity on the target, taking into account the ponderomotive forces affecting the behaviour of the interaction of light with the plasma. It is shown that in the case of resonance absorption of laser radiation by the plasma, the efficiency of generation of highly ionised atoms of the target substance is higher than the efficiency of generation in the case of classical absorption. The results of the numerical calculation by the developed model are in good agreement with the experiment.

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

2011-10-31

454

Alignment in two-step pulsed laser excitation of Rydberg levels in light atoms: The example of sodium  

Microsoft Academic Search

Aligned atomic Rydberg states of sodium can be prepared using two-step excitation from the ground state by linearly polarized pulsed lasers. Information that is normally inaccessible, e.g., sublevel partial cross sections in charge-transfer experiments, can be obtained when aligned targets are used. The calculations of orbital alignment must carefully allow for fine and hyperfine structure, laser linewidths, pulse widths and

Keith B. MacAdam; Michael A. Morrison

1993-01-01

455

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

SciTech Connect

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

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

456

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

NASA Astrophysics Data System (ADS)

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

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

2012-10-01

457

The effects of atomic rubidium vapor on the performance of optical windows in Diode Pumped Alkali Lasers (DPALs)  

NASA Astrophysics Data System (ADS)

Diode Pumped Alkali Lasers (DPALs) suffers from damage to its optical windows due to atomic alkali exposure. DPALs are of great interest since they can combine multiple lasers to achieve higher laser output power, scalable to megawatts, with very high quantum efficiency. However before scaling to higher laser output beam power, damage to the optical windows from atomic alkali exposure in the gain medium has to be addressed. A DPAL emulator chamber was constructed for the purpose of evaluating different optical windows in a representative hot alkali rich environment typical of a DPAL gain cell. Sample optical windows of fused silica, alumina, magnesium fluoride and calcium fluoride were exposed in the DPAL emulator in order to qualitatively and quantitatively demonstrate and assess the damaging effects of the atomic rubidium vapor on the optical windows. Methodologies to examine the damage were developed for comparing exposed and unexposed optical windows. We found that damage to the optical windows due to the atomic rubidium can be quantified by means of changes in laser energy transmission through the optical window after rubidium exposure.

Quarrie, Lindsay O'Brien

2013-03-01

458

Cavity-mediated cooling of a trapped ?-type three-level atom using a standing-wave laser field  

NASA Astrophysics Data System (ADS)

We propose a ground-state cavity-mediated cooling scheme for a trapped atom, which is in the ? configuration and confined inside a high-finesse optical cavity, using a standing-wave cooling laser. The carrier transition can be prohibited by placing the atom at the node of the cavity field, and the blue-sideband transition can be simultaneously eliminated by exploiting quantum interference via tuning the frequency of the cooling laser. As a consequence, the ground-state cooling for the trapped atom can be achieved. Moreover, we numerically demonstrate the superiority by placing the atom at the antinode of the standing-wave cooling laser as compared with the running-wave cooling laser, and the robustness of the scheme using the standing-wave laser. Meanwhile, the cooling rate can reach the same order of magnitude as that obtained in the cavity-electromagnetically-induced-transparency cooling scheme, and the explicit expression for the final phonon number in higher order is also presented.

Yi, Zhen; Li, Gao-xiang; Yang, Ya-ping

2013-05-01

459

A Dye Laser Spectrometer Stabilized to a Hyperfine Component of Molecular Iodine for the Magnetooptical Trap of Sodium Atoms  

Microsoft Academic Search

A dye laser spectrometer, whose sideband frequency was stabilized to a hyperfine component of molecular iodine, was developed for the magnetooptical trap of sodium atoms. The frequency difference between the transition from 3S1\\/2, F=2 to the 3P3\\/2, F\\\\prime=3 of a sodium atom and the f component of the P(38) line in the 15-2 band of the molecular iodine was measured

Shinichiro Watanabe; Yasuyuki Aizawa; Atsuo Morinaga

2003-01-01

460

An electrostatic glass actuator for ultrahigh vacuum: A rotating light trap for continuous beams of laser-cooled atoms  

SciTech Connect

This article describes the design, characterization, and performance of an electrostatic glass actuator adapted to an ultrahigh vacuum environment (10{sup -8} mbar). The three-phase rotary motor is used to drive a turbine that acts as a velocity-selective light trap for a slow continuous beam of laser-cooled atoms. This simple, compact, and nonmagnetic device should find applications in the realm of time and frequency metrology, as well as in other areas of atomic, molecular physics and elsewhere.

Fuezesi, F.; Jornod, A.; Thomann, P.; Plimmer, M. D.; Dudle, G.; Moser, R.; Sache, L.; Bleuler, H. [Observatoire cantonal de Neuchatel (ON), rue de l'Observatoire 58, CH-2000 Neuchatel (Switzerland); Federal Office of Metrology (METAS), Lindenweg 50, CH-3003 Bern-Wabern (Switzerland); Laboratory of Robotic Systems (LSRO), EPFL Lausanne, CH-1015 Lausanne (Switzerland)

2007-10-15