WorldWideScience

Sample records for laser resonance ionization

  1. Resonance Ionization Laser Ion Sources

    CERN Document Server

    Marsh, B

    2013-01-01

    The application of the technique of laser resonance ionization to the production of singly charged ions at radioactive ion beam facilities is discussed. The ability to combine high efficiency and element selectivity makes a resonance ionization laser ion source (RILIS) an important component of many radioactive ion beam facilities. At CERN, for example, the RILIS is the most commonly used ion source of the ISOLDE facility, with a yearly operating time of up to 3000 hours. For some isotopes the RILIS can also be used as a fast and sensitive laser spectroscopy tool, provided that the spectral resolution is sufficiently high to reveal the influence of nuclear structure on the atomic spectra. This enables the study of nuclear properties of isotopes with production rates even lower than one ion per second and, in some cases, enables isomer selective ionization. The solutions available for the implementation of resonance laser ionization at radioactive ion beam facilities are summarized. Aspects such as the laser r...

  2. In-Source Laser Resonance Ionization at ISOL Facilities

    CERN Document Server

    Marsh, Bruce; Feddosseev, Valentin

    Resonance ionization laser ion source development has been carried out at two radioactive ion beam facilities: ISOLDE (CERN, Switzerland) and the IGISOL facility (Jyvaskyla, Finland). The scope of the Resonance Ionization Laser Ion Source has been extended to 27 elements with the development of new three-step ionization schemes for Sb, Sc, Dy, Y and Au. The efficiencies were determined to be in the range of 2 - 20 %. Additionally, a new two-step ionization scheme has been developed for bismuth in an off-line atomic beam unit. The scheme relies on ionization via a strong and broad auto-ionizing resonance at an energy of 63196.79 cm$^{−1}$. This scheme may offer an improvement over the existing RILIS efficiency and will be more convenient for use during resonance ionization spectroscopy of Bi isotopes. The RILIS can be used as a spectroscopic tool to probe features such as the hyperfine structures and the isotope-shifts of radioisotopes with low production rates. By coupling a laser scanning process that dire...

  3. Current developments with TRIUMF’s titanium-sapphire laser based resonance ionization laser ion source

    Energy Technology Data Exchange (ETDEWEB)

    Lassen, J., E-mail: LASSEN@triumf.ca; Li, R. [TRIUMF (Canada); Raeder, S. [GSI Helmholtzzentrum für Schwerionenforschung GmbH (Germany); Zhao, X.; Dekker, T. [TRIUMF (Canada); Heggen, H. [GSI Helmholtzzentrum für Schwerionenforschung GmbH (Germany); Kunz, P.; Levy, C. D. P.; Mostanmand, M.; Teigelhöfer, A.; Ames, F. [TRIUMF (Canada)

    2017-11-15

    Developments at TRIUMF’s isotope separator and accelerator (ISAC) resonance ionization laser ion source (RILIS) in the past years have concentrated on increased reliability for on-line beam delivery of radioactive isotopes to experiments, as well as increasing the number of elements available through resonance ionization and searching for ionization schemes with improved efficiency. The current status of these developments is given with a list of two step laser ionization schemes implemented recently.

  4. Resonance ionization mass spectrometry using tunable diode lasers

    International Nuclear Information System (INIS)

    Shaw, R.W.; Young, J.P.; Smith, D.H.

    1990-01-01

    Tunable semiconductor diode lasers will find many important applications in atomic spectroscopy. They exhibit the desirable attributes of lasers: narrow bandwidth, tunability, and spatial coherence. At the same time, they possess few of the disadvantages of other tunable lasers. They require no alignment, are simple to operate, and are inexpensive. Practical laser spectroscopic instruments can be envisioned. The authors have applied diode lasers to resonance ionization mass spectrometry (RIMS) of some of the lanthanide elements. Sub-Doppler resolution spectra have been recorded and have been used for atomic hyperfine structure analysis. Isotopically-selective ionization has been accomplished, even in cases where photons from a broadband dye laser are part of the overall ionization process and where the isotopic spectral shift is very small. A convenient RIMS instrument for isotope ratio measurements that employs only diode lasers, along with electric field ionization, should be possible

  5. A resonant ionization laser ion source at ORNL

    Energy Technology Data Exchange (ETDEWEB)

    Liu, Y.; Stracener, D.W.

    2016-06-01

    Multi-step resonance laser ionization has become an essential tool for the production of isobarically pure radioactive ion beams at the isotope separator on-line (ISOL) facilities around the world. A resonant ionization laser ion source (RILIS) has been developed for the former Holifield Radioactive Ion Beam Facility (HRIBF) of Oak Ridge National Laboratory. The RILIS employs a hot-cavity ion source and a laser system featuring three grating-tuned and individually pumped Ti:Sapphire lasers, especially designed for stable and simple operation. The RILIS has been installed at the second ISOL production platform of former HRIBF and has successfully provided beams of exotic neutron-rich Ga isotopes for beta decay studies. This paper reports the features, advantages, limitations, and on-line and off-line performance of the RILIS.

  6. Resonance ionization laser ion sources for on-line isotope separators (invited)

    International Nuclear Information System (INIS)

    Marsh, B. A.

    2014-01-01

    A Resonance Ionization Laser Ion Source (RILIS) is today considered an essential component of the majority of Isotope Separator On Line (ISOL) facilities; there are seven laser ion sources currently operational at ISOL facilities worldwide and several more are under development. The ionization mechanism is a highly element selective multi-step resonance photo-absorption process that requires a specifically tailored laser configuration for each chemical element. For some isotopes, isomer selective ionization may even be achieved by exploiting the differences in hyperfine structures of an atomic transition for different nuclear spin states. For many radioactive ion beam experiments, laser resonance ionization is the only means of achieving an acceptable level of beam purity without compromising isotope yield. Furthermore, by performing element selection at the location of the ion source, the propagation of unwanted radioactivity downstream of the target assembly is reduced. Whilst advances in laser technology have improved the performance and reliability of laser ion sources and broadened the range of suitable commercially available laser systems, many recent developments have focused rather on the laser/atom interaction region in the quest for increased selectivity and/or improved spectral resolution. Much of the progress in this area has been achieved by decoupling the laser ionization from competing ionization processes through the use of a laser/atom interaction region that is physically separated from the target chamber. A new application of gas catcher laser ion source technology promises to expand the capabilities of projectile fragmentation facilities through the conversion of otherwise discarded reaction fragments into high-purity low-energy ion beams. A summary of recent RILIS developments and the current status of laser ion sources worldwide is presented

  7. Resonance ionization in a gas cell: a feasibility study for a laser ion source

    International Nuclear Information System (INIS)

    Qamhieh, Z.N.; Vandeweert, E.; Silverans, R.E.; Duppen, P. van; Huyse, M.; Vermeeren, L.

    1992-01-01

    A laser ion source based on resonance photo-ionization in a gas cell is proposed. The gas cell, filled with helium, consists of a target chamber in which the recoil products are stopped and neutralized, and an ionization chamber where the atoms of interest are selectively ionized by the laser light. The extraction of the ions from the ionization chamber through the exit hole-skimmer setup is similar to the ion-guide system. The conditions to obtain an optimal system are given. The results of a two-step one-laser resonance photo-ionization of nickel and the first results of laser ionization in a helium buffer gas cell are presented. (orig.)

  8. Laser resonance ionization scheme development for tellurium and germanium at the dual Ti:Sa–Dye ISOLDE RILIS

    CERN Document Server

    Day Goodacre, T.; Fedosseev, V.N.; Forster, L.; Marsh, B.A.; Rossel, R.E.; Rothe, S.; Veinhard, M.

    2016-01-01

    The resonance ionization laser ion source (RILIS) is the principal ion source of the ISOLDE radioactive beam facility based at CERN. Using the method of in-source laser resonance ionization spectroscopy, a transition to a new autoionizing state of tellurium was discovered and applied as part of a three-step, three-resonance, photo-ionization scheme. In a second study, a three-step, two-resonance, photo-ionization scheme for germanium was developed and the ionization efficiency was measured at ISOLDE. This work increases the range of ISOLDE RILIS ionized beams to 31 elements. Details of the spectroscopy studies are described and the new ionization schemes are summarized.

  9. Laser resonance ionization scheme development for tellurium and germanium at the dual Ti:Sa–Dye ISOLDE RILIS

    Energy Technology Data Exchange (ETDEWEB)

    Day Goodacre, T., E-mail: thomas.day.goodacre@cern.ch [CERN, CH-1211 Geneva 23 (Switzerland); School of Physics and Astronomy, The University of Manchester, Manchester M13 9PL (United Kingdom); Fedorov, D. [Petersburg Nuclear Physics Institute, 188350 Gatchina (Russian Federation); Fedosseev, V.N.; Forster, L.; Marsh, B.A. [CERN, CH-1211 Geneva 23 (Switzerland); Rossel, R.E. [CERN, CH-1211 Geneva 23 (Switzerland); Institut für Physik, Johannes Gutenberg Universität, D-55099 Mainz (Germany); Faculty of Design, Computer Science and Media, Hochschule RheinMain, Wiesbaden (Germany); Rothe, S.; Veinhard, M. [CERN, CH-1211 Geneva 23 (Switzerland)

    2016-09-11

    The resonance ionization laser ion source (RILIS) is the principal ion source of the ISOLDE radioactive beam facility based at CERN. Using the method of in-source laser resonance ionization spectroscopy, a transition to a new autoionizing state of tellurium was discovered and applied as part of a three-step, three-resonance, photo-ionization scheme. In a second study, a three-step, two-resonance, photo-ionization scheme for germanium was developed and the ionization efficiency was measured at ISOLDE. This work increases the range of ISOLDE RILIS ionized beams to 31 elements. Details of the spectroscopy studies are described and the new ionization schemes are summarized.

  10. Modeling and simulation of two-step resonance ionization processes using CW and pulsed lasers

    CERN Document Server

    de Groote, Ruben; Flanagan, Kieran

    This thesis derives and discusses equations that describe the evolution of atomic systems subjected to two monochromatic and coherent radiation fields and treats both continuous and temporally pulsed irradiation. This theoretical description is de- veloped mainly to understand the influence of the photon field intensities on experimental ionization spectra. The primary ap- plication of this theoretical framework is on methods that rely on resonant laser excitation and non-resonant laser ionization to extract information on the hyperfine structure of atomic systems. In particular, qualitative and quantitative discussions on the laser-related changes in hyperfine splitting extracted from ion- ization spectra are presented. Also, a method for increasing the resolution of resonance ionization techniques (potentially up un- til the natural linewidth of the electronic transitions) is discussed and theoretically justified. Both topics are illustrated with exper- imental data.

  11. Hot-cavity studies for the Resonance Ionization Laser Ion Source

    International Nuclear Information System (INIS)

    Henares, J.L.; Lecesne, N.; Hijazi, L.; Bastin, B.; Kron, T.; Lassen, J.; Le Blanc, F.; Leroy, R.; Osmond, B.; Raeder, S.; Schneider, F.; Wendt, K.

    2016-01-01

    The Resonance Ionization Laser Ion Source (RILIS) has emerged as an important technique in many Radioactive Ion Beam (RIB) facilities for its reliability, and ability to ionize target elements efficiently and element selectively. GISELE is an off-line RILIS test bench to study the implementation of an on-line laser ion source at the GANIL separator facility. The aim of this project is to determine the best technical solution which combines high selectivity and ionization efficiency with small ion beam emittance and stable long term operation. The ion source geometry was tested in several configurations in order to find a solution with optimal ionization efficiency and beam emittance. Furthermore, a low work function material was tested to reduce the contaminants and molecular sidebands generated inside the ion source. First results with ZrC ionizer tubes will be presented. Furthermore, a method to measure the energy distribution of the ion beam as a function of the time of flight will be discussed.

  12. Improving the Selectivity of the ISOLDE Resonance Ionization Laser Ion Source and In-Source Laser Spectroscopy of Polonium

    CERN Document Server

    Fink, Daniel Andreas; Jochim, Selim

    Exotic atomic nuclei far away from stability are fascinating objects to be studied in many scientic elds such as atomic-, nuclear-, and astrophysics. Since these are often short-lived isotopes, it is necessary to couple their production with immediate extraction and delivery to an experiment. This is the purpose of the on-line isotope separator facility, ISOLDE, at CERN. An essential aspect of this laboratory is the Resonance Ionization Laser Ion Source (RILIS) because it provides a fast and highly selective means of ionizing the reaction products. This technique is also a sensitive laser-spectroscopy tool for the development and improvement of electron excitation schemes for the resonant laser photoionization and the study of the nuclear structure or fundamental atomic physics. Each of these aspects of the RILIS applications are subjects of this thesis work: a new device for the suppression of unwanted surface ionized contaminants in RILIS ion beams, known as the Laser Ion Source and Trap (LIST), was impleme...

  13. Historical survey of resonance ionization spectroscopy

    International Nuclear Information System (INIS)

    Hurst, G.S.

    1984-04-01

    We have recently celebrated the 10th birthday of Resonance Ionization Spectroscopy (RIS), and this seems an appropriate time to review the history of its development. Basically, RIS is a photophysics process in which tunable light sources are used to remove a valence electron from an atom of selected atomic number, Z. If appropriate lasers are used as the light source, one electron can be removed from each atom of the selected Z in the laser pulse. This implies that RIS can be a very efficient, as well as selective, ionization process. In what we normally call RIS, laser schemes are employed which preserve both of these features. In contrast, multiphoton ionization (MPI) is more general, although not necessarily Z selective or very efficient because resonances are often not used. Early research completed in the USSR and described as selective two-step photoionization, employed resonances to ionize the rubidium atom and served to guide work on laser isotope separation. 29 references, 8 figures

  14. Resonant-enhanced above-threshold ionization of atoms by XUV short laser pulses

    Energy Technology Data Exchange (ETDEWEB)

    Rodriguez, V.D. [Departamento de Fisica, FCEyN, Universidad de Buenos Aires, 1428 Buenos Aires (Argentina)], E-mail: vladimir@df.uba.ar; Macri, P.A. [Instituto de Investigaciones Fisicas de Mar del Plata (IFIMAR), Departamento de Fisica, FCEyN, Universidad Nacional de Mar del Plata, CONICET, Funes 3350, 7600 Mar del Plata (Argentina); Arbo, D.G. [Instituto de Astronomia y Fisica del Espacio, UBA-CONICET, CC 67 Suc 28 Buenos Aires (Argentina)

    2009-01-15

    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 cross sections.

  15. Resonantly enhanced collisional ionization measurements of radionuclides

    International Nuclear Information System (INIS)

    Whitaker, T.J.; Bushaw, B.A.; Gerke, G.K.

    1986-01-01

    The authors developed a new laser technique to analyze for radionuclides at extremely low levels. The technique, called resonantly enhanced collisional ionization (RECI), uses two nitrogen-laser pumped dye lasers to excite the target isotope to a high-energy Rydberg state. Atoms in these Rydberg states (within a few hundred wavenumbers in energy from the ionization threshold) efficiently ionize upon colliding with an inert gas and the ions can be detected by conventional means. The principal advantage of resonantly-enhanced collisional ionization is the extreme sensitivity coupled with its relative simplicity and low cost. Actinides typically have an ionization potential of about 6eV (uranium I.P. = 6.2 eV, plutonium I.P. = 5.7 eV). Two-step laser excitation to a state just below threshold requires wavelengths in the blue region of the visible spectrum. They showed that when both steps in the excitation process are resonant steps, relatively low-power lasers can populate the Rydberg state with almost unit efficiency. This is because the resonant excitations have much larger cross-sections than do photoionization processes. They also demonstrated that a few torr of a buffer gas will cause most of the excited-state atoms to be ionized

  16. Resonance ionization scheme development for europium

    Energy Technology Data Exchange (ETDEWEB)

    Chrysalidis, K., E-mail: katerina.chrysalidis@cern.ch; Goodacre, T. Day; Fedosseev, V. N.; Marsh, B. A. [CERN (Switzerland); Naubereit, P. [Johannes Gutenberg-Universität, Institiut für Physik (Germany); Rothe, S.; Seiffert, C. [CERN (Switzerland); Kron, T.; Wendt, K. [Johannes Gutenberg-Universität, Institiut für Physik (Germany)

    2017-11-15

    Odd-parity autoionizing states of europium have been investigated by resonance ionization spectroscopy via two-step, two-resonance excitations. The aim of this work was to establish ionization schemes specifically suited for europium ion beam production using the ISOLDE Resonance Ionization Laser Ion Source (RILIS). 13 new RILIS-compatible ionization schemes are proposed. The scheme development was the first application of the Photo Ionization Spectroscopy Apparatus (PISA) which has recently been integrated into the RILIS setup.

  17. Above-threshold ionization of atoms by resonant XUV laser pulses

    Energy Technology Data Exchange (ETDEWEB)

    Rodriguez, V D [Departamento de Fisica and IFIBA-CONICET, FCEyN, Universidad de Buenos Aires, 1428 Buenos Aires (Argentina); Arbo, D G [Instituto de AstronomIa y Fisica del Espacio, FCEN-UBA CONICET, CC 67 Suc 28 Buenos Aires (Argentina); Macri, P A, E-mail: vladimir@df.uba.ar [Departamento de Fisica, FCEyN, Instituto de Investigaciones Fisicas de Mar del Plata (IFIMAR), Universidad Nacional de Mar del Plata-CONICET, Funes 3350, 7600 Mar del Plata (Argentina)

    2011-06-28

    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 Schroedinger equation considering a few bound states. The close-coupling Coulomb-Volkov theory, fully accounting for the important 1s-2p transition, explains the photoelectron spectrum as well as the total ionization cross sections for the resonant case. We also compare the partial wave populations and angular distributions given by the theory with the numerical solutions of the time-dependent Schroedinger equation.

  18. Laser resonance ionization for ultra-trace analysis on long-lived ...

    Indian Academy of Sciences (India)

    for producing pure beams of short-lived isotopes at on-line facilities. .... mental design is to develop a compact table-top RIS experiment which allows for. 1058 ... partial beams which are merged by dichroic mirrors and polarization beam splitter ... A quasi-cw 35 W CO2 laser is used for efficient non-resonant ionization of.

  19. Generation of low-energy muons with laser resonant ionization

    International Nuclear Information System (INIS)

    Matsuda, Y.; Bakule, P.; Iwasaki, M.; Matsuzaki, T.; Miyake, Y.; Ikedo, Y.; Strasser, P.; Shimomura, K.; Makimura, S.; Nagamine, K.

    2006-01-01

    We have constructed a low-energy muSR spectrometer at RIKEN-RAL muon facility in ISIS, the UK. With low-background of pulsed muon beam, and short pulse width from laser resonant ionization method, it is hoped this instrument will open new possibilities for studies of material sciences with muon beam. It is enphasized that this method is well suited to the facility where intense pulsed proton beam is available

  20. Resonant ionization by laser beams: application to ions sources and to study the nuclear structure of radioactive tellurium isotopes

    International Nuclear Information System (INIS)

    Sifi, R.

    2007-07-01

    The radioactive ion beams that are produced through current isotope separators are well separated according to the A mass but not according to the Z parameter. The resonant ionization through laser beams applied to ion sources allows the production of radioactive ion beam in a very selective and efficient way by eliminating the isobaric contamination. The first chapter is dedicated to the resonant ionization by laser beams, we describe the principle, the experimental setting, the lasers used, the ionization schemes and the domain of application. The second chapter deals with the application of resonant ionization to laser ion sources for the production of radioactive ion beams. We present experimental tests performed for getting copper ion beams. Resonant ionization through laser is also used in the spectroscopy experiments performed at the Isolde (isotope separation on-line device) installation in CERN where more than 20 elements are ionized very efficiently. The technique is based on a frequency scanning around the excitation transition of the atoms in order to probe the hyperfine structure. Laser spectroscopy allows the determination of the hyperfine structure as well as the isotopic shift of atoms. In the third chapter the method is applied to the spectroscopy of tellurium atoms. First, we define the 2 parameters on which the extraction is based: charge radius and nuclear moments, then we present several theoretical models that we have used to assess our experimental results. (A.C.)

  1. Quantifying Uranium Isotope Ratios Using Resonance Ionization Mass Spectrometry: The Influence of Laser Parameters on Relative Ionization Probability

    Energy Technology Data Exchange (ETDEWEB)

    Isselhardt, Brett H. [Univ. of California, Berkeley, CA (United States)

    2011-09-01

    Resonance Ionization Mass Spectrometry (RIMS) has been developed as a method to measure relative uranium isotope abundances. In this approach, RIMS is used as an element-selective ionization process to provide a distinction between uranium atoms and potential isobars without the aid of chemical purification and separation. We explore the laser parameters critical to the ionization process and their effects on the measured isotope ratio. Specifically, the use of broad bandwidth lasers with automated feedback control of wavelength was applied to the measurement of 235U/238U ratios to decrease laser-induced isotopic fractionation. By broadening the bandwidth of the first laser in a 3-color, 3-photon ionization process from a bandwidth of 1.8 GHz to about 10 GHz, the variation in sequential relative isotope abundance measurements decreased from >10% to less than 0.5%. This procedure was demonstrated for the direct interrogation of uranium oxide targets with essentially no sample preparation. A rate equation model for predicting the relative ionization probability has been developed to study the effect of variation in laser parameters on the measured isotope ratio. This work demonstrates that RIMS can be used for the robust measurement of uranium isotope ratios.

  2. Resonant multiphoton ionization of caesium atoms by ultra-short laser pulses at 1.06 μm

    International Nuclear Information System (INIS)

    Lompre, L.A.; Mainfray, G.; Manus, C.; Thebault, J.

    1978-01-01

    This paper reports the four-photon ionization of caesium atoms when the laser frequency is tuned through the resonant three-photon transition 6S → 6F. This experiment was performed by using a tunable-wavelength bandwidth-limited subnanosecond laser pulse at 1.06 μm, in the 10 8 -10 9 W.cm -2 laser intensity range. Pulse widths of 1.5 ns, 50 ps, and 15 ps were used. The resonant character of the multiphoton ionization process was observed, even with the shortest pulse of 15 ps. Nevertheless the influence of a temporal effect is demonstrated according to theoretical predictions. The resonance shift ΔE of the 6S → 6F transition energy was found to be linear with the laser intensity I within the range 10 8 -10 9 W.cm -2 . ΔE = αI, with α = 2 cm -1 /GW.cm -2 . This results confirms previous measurements performed with single-mode 35 ns laser pulses and is in very good agreement with calculated resonance shifts

  3. Selective isotope determination of lanthanum by diode-laser-initiated resonance-ionization mass spectrometry

    International Nuclear Information System (INIS)

    Young, J.P.; Shaw, R.W.

    1995-01-01

    A diode-laser step has been incorporated into a resonance-ionization mass spectrometry optical excitation process to enhance the isotopic selectivity of the technique. Lanthanum isotope ratio enhancements as high as 10 3 were achieved by use of a single-frequency cw diode laser tuned to excite the first step of a three-step excitation--ionization optical process; the subsequent steps were excited by use of a pulsed dye laser. Applying the same optical technique, we measured atomic hyperfine constants for the high-lying even-parity 4 D 5/2 state of lanthanum at 30 354 cm --1 . The general utility of this spectral approach is discussed

  4. Laser-induced ionization of Na vapor

    International Nuclear Information System (INIS)

    Wu, R.C.Y.; Judge, D.L.; Roussel, F.; Carre, B.; Breger, P.; Spiess, G.

    1982-01-01

    The production of Na 2 + ions by off-resonant laser excitation in the 5800-6200A region mainly results from two-photon absorption by the Na 2 molecule to highly excited gerade states followed by (a) direct ionization by absorbing a third photon or (b) coupling to the molecular Na 2 D 1 PIμ Rydberg state which is subsequently ionized by absorbing a third photon. This mechanism, i.e., a two-photon resonance three photon ionization process, explains a recent experimental observation of Roussel et al. It is suggested that the very same mechanism is also responsible for a similar observation reported by Polak-Dingels et al in their work using two crossed Na beams. In the latter two studies the laser-induced associative ionization processes were reported to be responsible for producing the Na 2 + ion. From the ratio of molecular to atomic concentration in the crossed beam experiment of Polak-Dingels et al we estimate that the cross section for producing Na 2 + through laser-induced associative ionization is at least four orders of magnitude smaller than ionization through the two-photon resonance three photon ionization process in Na 2 molecules

  5. Two-step laser ionization schemes for in-gas laser ionization and spectroscopy of radioactive isotopesa

    OpenAIRE

    Kudryavtsev, Yuri; Ferrer, Rafael; Huyse, Mark; Van den Bergh, Paul; Van Duppen, Piet; Vermeeren, L.

    2014-01-01

    The in-gas laser ionization and spectroscopy technique has been developed at the Leuven isotope separator on-line facility for the production and in-source laser spectroscopy studies of short-lived radioactive isotopes. In this article, results from a study to identify efficient optical schemes for the two-step resonance laser ionization of 18 elements are presented. © 2013 AIP Publishing LLC.

  6. Study of Low Work Function Materials for Hot Cavity Resonance Ionization Laser Ion Sources

    CERN Document Server

    Catherall, R; Fedosseev, V; Marsh, B; Mattolat, C; Menna, Mariano; Österdahl, F; Raeder, S; Schwellnus, F; Stora, T; Wendt, K; CERN. Geneva. AB Department

    2008-01-01

    The selectivity of a hot cavity resonance ionization laser ion source (RILIS) is most often limited by contributions from competing surface ionization on the hot walls of the ionization cavity. In this article we present investigations on the properties of designated high-temperature, low-work function materials regarding their performance and suitability as cavity material for RILIS. Tungsten test cavities, impregnated with a mixture of barium oxide and strontium oxide (BaOSrO on W), or alternatively gadolinium hexaboride (GdB6) were studied in comparison to a standard tungsten RILIS cavity as being routinely used for hot cavity laser ionization at ISOLDE. Measurement campaigns took place at the off-line mass separators at ISOLDE / CERN, Geneva and RISIKO / University of Mainz.

  7. Study of low work function materials for hot cavity resonance ionization laser ion sources

    CERN Document Server

    Schwellnus, F; Crepieux, B; Fedosseev, V N; Marsh, B A; Mattolat, Ch; Menna, M; Österdahl, F K; Raeder, S; Stora, T; Wendta, K

    2009-01-01

    The selectivity of a hot cavity resonance ionization laser ion source (RILIS) is most often limited by contributions from competing surface ionization of the hot walls of the ionization cavity. In this article we present investigations on the properties of designated high temperature, low work function materials regarding their performance and suitability as cavity material for RILIS. Tungsten test cavities, impregnated with a mixture of barium oxide and strontium oxide (BaOSrO on W), or alternatively gadolinium hexaboride (GdB6) were studied in comparison to a standard tungsten RILIS cavity as being routinely used for hot cavity laser ionization at ISOLDE. Measurement campaigns took place at the off-line mass separators at ISOLDE/CERN, Geneva and RISIKO/University of Mainz.

  8. Laser resonance ionization spectroscopy on lutetium for the MEDICIS project

    Energy Technology Data Exchange (ETDEWEB)

    Gadelshin, V., E-mail: gadelshin@uni-mainz.de [University of Mainz, Institute of Physics (Germany); Cocolios, T. [KU Leuven, Institute for Nuclear and Radiation Physics (Belgium); Fedoseev, V. [CERN, EN Department (Switzerland); Heinke, R.; Kieck, T. [University of Mainz, Institute of Physics (Germany); Marsh, B. [CERN, EN Department (Switzerland); Naubereit, P. [University of Mainz, Institute of Physics (Germany); Rothe, S.; Stora, T. [CERN, EN Department (Switzerland); Studer, D. [University of Mainz, Institute of Physics (Germany); Duppen, P. Van [KU Leuven, Institute for Nuclear and Radiation Physics (Belgium); Wendt, K. [University of Mainz, Institute of Physics (Germany)

    2017-11-15

    The MEDICIS-PROMED Innovative Training Network under the Horizon 2020 EU program aims to establish a network of early stage researchers, involving scientific exchange and active cooperation between leading European research institutions, universities, hospitals, and industry. Primary scientific goal is the purpose of providing and testing novel radioisotopes for nuclear medical imaging and radionuclide therapy. Within a closely linked project at CERN, a dedicated electromagnetic mass separator system is presently under installation for production of innovative radiopharmaceutical isotopes at the new CERN-MEDICIS laboratory, directly adjacent to the existing CERN-ISOLDE radioactive ion beam facility. It is planned to implement a resonance ionization laser ion source (RILIS) to ensure high efficiency and unrivaled purity in the production of radioactive ions. To provide a highly efficient ionization process, identification and characterization of a specific multi-step laser ionization scheme for each individual element with isotopes of interest is required. The element lutetium is of primary relevance, and therefore was considered as first candidate. Three two-step excitation schemes for lutetium atoms are presented in this work, and spectroscopic results are compared with data of other authors.

  9. Laser resonance ionization spectroscopy on lutetium for the MEDICIS project

    Science.gov (United States)

    Gadelshin, V.; Cocolios, T.; Fedoseev, V.; Heinke, R.; Kieck, T.; Marsh, B.; Naubereit, P.; Rothe, S.; Stora, T.; Studer, D.; Van Duppen, P.; Wendt, K.

    2017-11-01

    The MEDICIS-PROMED Innovative Training Network under the Horizon 2020 EU program aims to establish a network of early stage researchers, involving scientific exchange and active cooperation between leading European research institutions, universities, hospitals, and industry. Primary scientific goal is the purpose of providing and testing novel radioisotopes for nuclear medical imaging and radionuclide therapy. Within a closely linked project at CERN, a dedicated electromagnetic mass separator system is presently under installation for production of innovative radiopharmaceutical isotopes at the new CERN-MEDICIS laboratory, directly adjacent to the existing CERN-ISOLDE radioactive ion beam facility. It is planned to implement a resonance ionization laser ion source (RILIS) to ensure high efficiency and unrivaled purity in the production of radioactive ions. To provide a highly efficient ionization process, identification and characterization of a specific multi-step laser ionization scheme for each individual element with isotopes of interest is required. The element lutetium is of primary relevance, and therefore was considered as first candidate. Three two-step excitation schemes for lutetium atoms are presented in this work, and spectroscopic results are compared with data of other authors.

  10. Production of radioactive ion beams and resonance ionization spectroscopy with the laser ion source at on-line isotope separator ISOLDE

    International Nuclear Information System (INIS)

    Fedosseev, V.N.; )

    2005-01-01

    Full text: The resonance ionisation laser ion source (RILIS) of the ISOLDE on-line isotope separation facility at CERN is based on the method of laser step-wise resonance ionisation of atoms in a hot metal cavity. Using the system of dye lasers pumped by copper vapour lasers the ion beams of many different metallic elements have been produced at ISOLDE with an ionization efficiency of up to 27%. The high selectivity of the resonance ionization is an important asset for the study of short-lived nuclides produced in targets bombarded by the proton beam of the CERN Booster accelerator. Radioactive ion beams of Be, Mg, Al, Mn, Ni, Cu, Zn, Ga, Ag, Cd, In, Sn, Sb, Tb, Yb, Tl, Pb and Bi have been generated with the RILIS. Setting the RILIS laser in the narrow line-width mode provides conditions for a high-resolution study of hyperfine structure and isotopic shifts of atomic lines for short-lived isotopes. The isomer selective ionization of Cu, Ag and Pb isotopes has been achieved by appropriate tuning of laser wavelengths

  11. Analysis of chirality by femtosecond laser ionization mass spectrometry.

    Science.gov (United States)

    Horsch, Philipp; Urbasch, Gunter; Weitzel, Karl-Michael

    2012-09-01

    Recent progress in the field of chirality analysis employing laser ionization mass spectrometry is reviewed. Emphasis is given to femtosecond (fs) laser ionization work from the author's group. We begin by reviewing fundamental aspects of determining circular dichroism (CD) in fs-laser ionization mass spectrometry (fs-LIMS) discussing an example from the literature (resonant fs-LIMS of 3-methylcyclopentanone). Second, we present new data indicating CD in non-resonant fs-LIMS of propylene oxide. Copyright © 2012 Wiley Periodicals, Inc., A Wiley Company.

  12. Two-step resonance ionization spectroscopy of Na atomic beam using cw and pulsed lasers

    International Nuclear Information System (INIS)

    Katsuragawa, H.; Minowa, T.; Shimazu, M.

    1988-01-01

    Two-step photoionization of sodium atomic beam has been carried out using a cw and a pulsed dye lasers. Sodium ions have been detected by a time of flight method in order to reduce background noise. With a proper power of the pulsed dye laser the sodium atomic beam has been irradiated by a resonant cw dye laser. The density of the sodium atomic beam is estimated to be 10 3 cm -3 at the ionization area. (author)

  13. An All-Solid-State High Repetiton Rate Titanium:Sapphire Laser System For Resonance Ionization Laser Ion Sources

    Science.gov (United States)

    Mattolat, C.; Rothe, S.; Schwellnus, F.; Gottwald, T.; Raeder, S.; Wendt, K.

    2009-03-01

    On-line production facilities for radioactive isotopes nowadays heavily rely on resonance ionization laser ion sources due to their demonstrated unsurpassed efficiency and elemental selectivity. Powerful high repetition rate tunable pulsed dye or Ti:sapphire lasers can be used for this purpose. To counteract limitations of short pulse pump lasers, as needed for dye laser pumping, i.e. copper vapor lasers, which include high maintenance and nevertheless often only imperfect reliability, an all-solid-state Nd:YAG pumped Ti:sapphire laser system has been constructed. This could complement or even replace dye laser systems, eliminating their disadvantages but on the other hand introduce shortcomings on the side of the available wavelength range. Pros and cons of these developments will be discussed.

  14. Analysis of 81Kr in groundwater using laser resonance ionization spectroscopy

    International Nuclear Information System (INIS)

    Kramer, S.D.; Hurst, G.S.; Chen, C.H.

    1985-10-01

    A new analytical technique based on resonant ionization of krypton with a vacuum ultraviolet (VUV) laser source was used to determine low-level 81 Kr concentrations in groundwater. The long half-life (210,000 years) and low concentration (1.3 x 10 3 81 Kr atoms per liter of modern water at 10 0 C) make the detection of 81 Kr by radioactive counting techniques extremely difficult. In this method, krypton gas was removed from water taken from an underground Swiss aquifer using standard cryogenic and chromatographic techniques. Stable krypton isotopes were then reduced by a factor of 10 7 by a two-stage isotopic enrichment cycle using a commercially available mass spectrometer. The enriched gas containing about 10 8 stable krypton atoms and about 10 3 atoms of 81 Kr was implanted into a silicon disc. This disc was then placed in the high vacuum final counting chamber and the krypton was released by laser annealing. This chamber contained a quadrupole mass spectrometer which used a pulsed VUV laser source as the ionizer. The measured signal indicated that the sample contained 1200 (+-300) atoms of 81 Kr

  15. Atomic and molecular resonance ionization

    International Nuclear Information System (INIS)

    Botter, R.; Petit, A.

    1990-01-01

    Published in summary form only the paper recalls the principle of resonance photoionization, transition probability, selectivity and critical parameters. Examples of applications are briefly treated: Trace analysis by resonance ionization mass spectroscopy for detection of Fe in Zr F 4 for fabrication of optical fibers and laser isotopic separation of U 235 and Gd 157 [fr

  16. The identification of autoionizing states of atomic chromium for the resonance ionization laser ion source of the ISOLDE radioactive ion beam facility

    CERN Document Server

    Goodacre, T Day

    2017-01-01

    The resonance ionization laser ion source (RILIS) is the principal ion source of the ISOLDE radioactive beam facility based at CERN. Using the method of in-source resonance ionization spectroscopy, an optimal three-step, three-resonance photo-ionization scheme has been developed for chromium. The scheme uses an ionizing transition to one of the 14 newly observed autoionizing states. This work increases the range of ISOLDE-RILIS ionized beams to 32 chemical elements. Details of the spectroscopic studies are described and the new ionization scheme is summarized. A link to the complete version of this document will be added here following publication:

  17. Laser resonant ionization spectroscopy and laser-induced resonant fluorescence spectra of samarium atom

    International Nuclear Information System (INIS)

    Jin, Changtai

    1995-01-01

    We have measured new high-lying levels of Sm atom by two-colour resonant photoionisation spectroscopy; we have observed the isotope shifts of Sm atom by laser-induced resonant fluorescence spectroscopy; the lifetime of eight low-lying levels of Sm atom were measured by using pulsed laser-Boxcar technique in atomic beam.

  18. A data acquisition system for measuring ionization cross section in laser multi-step resonant ionization experiment

    International Nuclear Information System (INIS)

    Qian Dongbin; Guo Yuhui; Zhang Dacheng; Chinese Academy of Sciences, Beijing; Ma Xinwen; Zhao Zhizheng; Wang Yanyu; Zu Kailing

    2006-01-01

    A CAMAC data acquisition system for measuring ionization cross section in laser multi-step resonant ionization experiment is described. The number of scalers in the front-end CAMAC can be adjusted by changing the data read-out table files. Both continuous and manual acquisition models are available, and there is a wide adjustable range from 1 ms to 800 s with the acquisition time unit. The long-term stability, Δt/t, for the data acquisition system with an acquisition time unit of 100 s was measured to be better than ±0.01%, thus validating its reliability in long-term online experimental data acquisition. The time response curves for three electrothermal power-meters were also measured by this DAQ system. (authors)

  19. Laser ablation/ionization studies in a glow discharge

    International Nuclear Information System (INIS)

    Hess, K.R.; Harrison, W.W.

    1985-01-01

    The pin cathode glow discharge is used in the laboratory as an atomization/ionization source for a variety of applications, including solids mass spectrometry. Coupled with a tunable dye laser, the glow discharge may also serve as an atom reservoir for resonance ionization mass spectrometry in which the laser ionizes the discharge sputtered atoms. By tightly focusing the laser onto solid samples, various ablation effects may also be investigated. The laser may be used to generate an ionized plasma which may be directly analyzed by mass spectrometry. Alternatively, the ablated neutral atoms may be used in post-ablation excitation/ionization processes, in this case the glow discharge. The results of these investigations are the basis of this paper

  20. Determination of iodine in oyster tissue by isotope dilution laser resonance ionization mass spectrometry

    International Nuclear Information System (INIS)

    Fassett, J.D.; Murphy, T.J.

    1990-01-01

    The technique of laser resonance ionization mass spectrometry has been combined with isotope dilution analysis to determine iodine in oyster tissue. The long-lived radioisotope, 129I, was used to spike the samples. Samples were equilibrated with the 129I, wet ashed under controlled conditions, and iodine separated by coprecipitation with silver chloride. The analyte was dried as silver ammonium iodide upon a tantalum filament from which iodine was thermally desorbed in the resonance ionization mass spectrometry instrument. A single-color, two-photon resonant plus one-photon ionization scheme was used to form positive iodine ions. Long-lived iodine signals were achieved from 100 ng of iodine. The precision of 127I/129I measurement has been evaluated by replicate determinations of the spike, the spike calibration samples, and the oyster tissue samples and was 1.0%. Measurement precision among samples was 1.9% for the spike calibration and 1.4% for the oyster tissue. The concentration of iodine determined in SRM 1566a, Oyster Tissue, was 4.44 micrograms/g with an estimate of the overall uncertainty for the analysis of +/- 0.12 microgram/g

  1. Extremely-high vacuum pressure measurement by laser ionization

    International Nuclear Information System (INIS)

    Kokubun, Kiyohide

    1991-01-01

    Laser ionization method has the very high sensitivity for detecting atoms and molecules. Hurst et al. successfully detected a single Cs atom by means of resonance ionization spectroscopy developed by them. Noting this high sensitivity, the authors have attempted to apply the laser ionization method to measure gas pressure, particularly in the range down to extremely high vacuum. At present, hot cathode ionization gauges are used for measuring gas pressure down to ultrahigh vacuum, however, those have a number of disadvantages. The pressure measurement using lasers does not have such disadvantages. The pressure measurement utilizing the laser ionization method is based on the principle that when laser beam is focused through a lens, the amount of atom or molecule ions generated in the focused space region is proportional to gas pressure. In this paper, the experimental results are presented on the nonresonant multiphoton ionization characteristics of various kinds of gases, the ion detection system with high sensitivity and an extremely high vacuum system prepared for the laser ionization experiment. (K.I.)

  2. Spectroscopic studies on technetium and silicon. A solid-state laser system for the resonance-ionization spectroscopy; Spektroskopische Untersuchungen an Technetium und Silizium. Ein Festkoerperlasersystem fuer die Resonanzionisationsspektroskopie

    Energy Technology Data Exchange (ETDEWEB)

    Mattolat, Christoph

    2010-11-15

    This doctoral thesis describes advancement and refinement of the titanium:sapphire laser system of the working group LARISSA, Institut fuer Physik, Johannes Gutenberg- Universitaet Mainz and its application to resonance ionization spectroscopy. Activities on the laser systems comprised three major tasks: The output power of the conventional titanium:sapphire lasers could be increased by a factor of two in order to match the needs at resonance ionization laser ion source at ISOL facilities. Additionally, the laser system was complemented by a titanium:sapphire laser in Littrow geometry, which ensures a mode-hop free tuning range from 700 nm to 950 nm, and by an injection seeded titanium:sapphire laser with a spectral width of 20 MHz (in respect to a spectral width of 3 GHz for the conventional lasers). The performance of the new laser system was tested in spectroscopic investigations of highly excited atomic levels of gold and technetium. From the measured level positions the ionization potential of gold could be verified by using the Rydberg-Ritz formula, while the ionization potential of technetium could be determined precisely for the first time. Using the seeded titanium: sapphire laser Doppler-free two-photon spectroscopy inside a hot ionizer cavity was demonstrated. A width of the recorded resonances of 90 MHz was achieved and the hyperfine structure and isotope shift of stable silicon isotopes was well resolved with this method. (orig.)

  3. Applications of resonance ionization spectroscopy in neutron dosimetry

    International Nuclear Information System (INIS)

    Whitaker, T.J.; Hurst, G.S.

    1982-01-01

    Resonance Ionization Spectroscopy (RIS) is a new analytical technique which is orders of magnitude more sensitive than previous methods of atomic analysis. In this method, lasers are used to selectively excite specific electronic transitions in the element being analyzed. A second laser photon can then ionize the excited atoms. Commercial lasers have sufficient intensity to assure that every atom located in the central portion of the laser beam will be ionized, and therefore can be detected. In this paper the concept of a xenon-containing matrix (XCM) which would release xenon atoms when exposed to neutrons is explored. Accumulated xenon would be measured using RIS to determine total dose. The total dosimeter would consist of an XCM, a radiator, and an encapsulation around both to contain released xenon atoms

  4. Laser ionization and dissociation of hydrogen

    International Nuclear Information System (INIS)

    Buck, J.D.

    1987-01-01

    Experiments undertaken to further characterize the spectroscopic and photophysical properties of some important excited singlet states of molecular hydrogen and its deuterium isotopes are described. Attention was centered on high vibrational levels of the B, C, and B' states within about 1000 cm -1 of the second dissociation limit. A double-resonance excitation scheme was needed to access levels with a large average bond distance from the ground state. Two-photon absorption of tunable uv-laser radiation-pumped ground-state hydrogen molecules into selected rovibronic levels of the metastable EF double-minimum electronic state. A second tunable near-IR probe laser was scanned to generate ions by resonant multiphoton ionization, where the resonant levels were provided by B, C, B', and other levels near the dissociation limit. New information was obtained regarding line shapes and intensities. Time-of-flight ion mass selection permitted observation of additional excitation channels with dissociation superimposed on the ionization process to produce protons

  5. Study of surface ionization and LASER ionization processes using the SOMEIL ion source: application to the Spiral 2 laser ion source development

    Energy Technology Data Exchange (ETDEWEB)

    Bajeat, O., E-mail: bajeat@ganil.fr; Lecesne, N.; Leroy, R.; Maunoury, L.; Osmond, B.; Sjodin, M. [GANIL (France); Maitre, A.; Pradeilles, N. [Laboratoire Science des Procedes Ceramiques et de Traitements de Surface (SPCTS) 12 (France)

    2013-04-15

    SPIRAL2 is the new project under construction at GANIL to provide radioactive ion beams to the Nuclear Physics Community and in particular neutron rich ion beams. For the production of condensable radioactive elements, a resonant ionization laser ion source is under development at GANIL. In order to generate the ions of interest with a good selectivity and purity, our group is studying the way to minimize surface ionization process by using refractory materials with low work function as ionizer tube. To do those investigations a dedicated ion source, called SOMEIL (Source Optimisee pour les Mesures d'Efficacite d'Ionisation Laser) is used. Numerous types of ionizer tubes made in various materials and geometry are tested. Surface ionization and laser ionization efficiencies can be measured for each of them.

  6. Trends in resonance ionization spectroscopy

    International Nuclear Information System (INIS)

    Hurst, G.S.

    1986-01-01

    The author reviews the history of resonance ionization spectroscopy and then comments on the delineations of RIS with reference to many related laser processes. The substance of the paper deals with the trends in RIS and especially how the needs for sensitive analytical methods have overshadowed the orginal plan to study excited species. 9 refs., 1 fig

  7. Indigenously built resonance ionization mass spectrometer

    International Nuclear Information System (INIS)

    Razvi, M.A.N.; Jayasekharan, T.; Thankarajan, K.; Guhagarkar, M.B.; Dixit, M.N.; Bhale, G.L.

    2000-04-01

    Design, fabrication and performance testing of an indigenously built Resonance Ionization Mass Spectrometer (RIMS) is presented in this report. The instrument is totally indigenous, but for the laser components consisting of the excimer laser and tunable dye lasers. Constructional details of atomic beam source and linear time-of-flight mass spectrometer are included. Finally, commissioning and performance testing of the instrument is described. Mass resolving power of 400 and a detection limit of 100 atoms has been achieved using this RIMS set-up. (author)

  8. Resonance Ionization Mass Spectrometry (RIMS): applications in spectroscopy and chemical dynamics

    International Nuclear Information System (INIS)

    Naik, P.D.; Kumar, Awadhesh; Upadhyaya, Hari; Bajaj, P.N.

    2009-01-01

    Resonance ionization is a photophysical process wherein electromagnetic radiation is used to ionize atoms, molecules, transient species, etc., by exciting them through their quantum states. The number of photons required to ionize depends on the species being investigated and energy of the photon. Once a charged particle is produced, it is easy to detect it with high efficiency. With the advent of narrow band high power pulsed and cw tunable dye lasers, it has blossomed into a powerful spectroscopic and analytical technique, commonly known as resonance ionization spectroscopy (RIS)/resonance enhanced multiphoton ionization (REMPI). The alliance of resonance ionization with mass spectrometry has grown into a still more powerful technique, known as resonance ionization mass spectrometry (RIMS), which has made significant contributions in a variety of frontier areas of research and development, such as spectroscopy, chemical dynamics, analytical chemistry, cluster science, surface science, radiochemistry, nuclear physics, biology, environmental science, material science, etc. In this article, we shall describe the application of resonance ionization mass spectrometry to spectroscopy of uranium and chemical dynamics of polyatomic molecules

  9. Study of the ionization of sodium vapor in the presence of resonant laser radiation

    International Nuclear Information System (INIS)

    Carre, B.

    1986-06-01

    Ionization of a diffuse sodium jet, excited by laser radiation (D2 resonance), either continuous or pulsed, is studied by electron spectroscopy. Results show: associative ionization (AI) in the collision of two Na(3p) excited atoms; occupancy of highly excited nl states in energy association collisions of two Na(3p) followed by Penning collisional ionization (CI) in the system Na(nl) + Na(3p); heating of electrons by 1, 2, or 3 superelastic collisions with Na(3p). For both the excitation cases (continuous or pulsed source) analysis of experiment results leads to a description of the whole of the ionized medium, characterized as being low density and the site of the ambipolar diffusion of charged particles. A highly simplified model describes the kinetic and electrokinetic equilibrium (continuous case) in which the different populations of distinct nonthermalized energy (low energy primary electrons, hot electrons) play specific roles. The cross sections associated with AI and CI are estimated from experiment results using the model [fr

  10. Resonantly-enhanced, four-photon ionization of krypton at laser intensities exceeding 1013 W/cm2

    International Nuclear Information System (INIS)

    Perry, M.D.; Landen, O.L.; Campbell, E.M.

    1987-12-01

    The yield of singly- and multiply- charged ions of krypton and xenon is presented as a function of laser intensity and frequency. The measurements were performed using the second harmonic output of a well-characterized, tunable picosecond dye laser in the range 285 to 310 nm at laser intensities from 1 x 10 12 to 10 14 W/cm 2 . Enhancement of the Kr + yield by two orders of magnitude by three-photon resonant, four-photon ionization is observed in the vicinity of the 4d'[5/2] 3 and the 4d[3/2] 1 intermediate states. A model incorporating line shifts and widths scaling linearly with intensity is in good agreement with the experimental results

  11. Alkali suppression within laser ion-source cavities and time structure of the laser ionized ion-bunches

    CERN Document Server

    Lettry, Jacques; Köster, U; Georg, U; Jonsson, O; Marzari, S; Fedosseev, V

    2003-01-01

    The chemical selectivity of the target and ion-source production system is an asset for Radioactive Ion-Beam (RIB) facilities equipped with mass separators. Ionization via laser induced multiple resonant steps Ionization has such selectivity. However, the selectivity of the ISOLDE Resonant Ionization Laser Ion-Source (RILIS), where ionization takes place within high temperature refractory metal cavities, suffers from unwanted surface ionization of low ionization potential alkalis. In order to reduce this type of isobaric contaminant, surface ionization within the target vessel was used. On-line measurements of the efficiency of this method is reported, suppression factors of alkalis up to an order of magnitude were measured as a function of their ionization potential. The time distribution of the ion bunches produced with the RILIS was measured for a variety of elements and high temperature cavity materials. While all ions are produced within a few nanoseconds, the ion bunch sometimes spreads over more than 1...

  12. Resonant excitation of uranium atoms by an argon ion laser

    Energy Technology Data Exchange (ETDEWEB)

    Maeyama, H; Morikawa, M; Aihara, Y; Mochizuki, T; Yamanaka, C [Osaka Univ. (Japan)

    1979-03-01

    Photoionization of uranium atoms by UV lines, 3511 A and 3345 A, of an argon ion laser was observed and attributed due to resonant two-photon ionization. The dependence of the photoion currents on laser power was measured in focusing and non-focusing modes of laser beam, which has enabled us to obtain an absorption cross section and an ionization cross section independently. The orders of magnitude of these cross sections averaged over the fine structure were determined to be 10/sup -14/ cm/sup 2/ and 10/sup -17/ cm/sup 2/ respectively from a rate equation model. Resonance between 3511-A laser line and the absorption line of uranium isotopes was also confirmed by the ionization spectra obtained by near-single-frequency operation of the ion laser, which allowed the isotopic selective excitation of the uranium atoms. The maximum value of the enrichment of /sup 235/U was about 14%. The isotope separation of uranium atoms by this resonant excitation has been discussed.

  13. Conceptual basis of resonance ionization spectroscopy

    International Nuclear Information System (INIS)

    Payne, M.G.

    1984-04-01

    Resonance Ionization Spectroscopy (RIS) can b defined as a state-selective detection process in which tunable lasers are used to promote transitions from the selected state of the atoms or molecules in question to higher states, one of which will be ionized by the absorption of another photon. At least one resonance step is used in the stepwise ionization process, and it has been shown that the ionization probability of the spectroscopically selected species can nearly always be made close to unity. Since measurements of the number of photoelectrons or ions can be made very precisely and even one electron (or under vacuum conditions, one ion) can be detected, the technique can be used to make quantitative measurements of very small populations of the state-selected species. Counting of individual atoms has special meaning for detection of rare events. The ability to make saturated RIS measurements opens up a wide variety of applications to both basic and applied research. We view RIS as a specific type of multi-photon ionization in which the goal is to make quantitative measurements of quantum-selected populations in atomic or molecular systems. 16 references

  14. Laser ionization installation for measurement of atomic beam parameters

    CERN Document Server

    Tukhlibaev, O; Khalilov, E E; Alimov, U Z

    2002-01-01

    The design of the laser ionization installation for determination of the atomic beam intensity, density and spatial structure is described. The method of the atoms laser resonance staged photoionization is applied in the installation. The above installation consists of two lasers on the dyestuffs, the atomizer, the ionization system and the ion signals registration system. The results of studies on the spatial structure of the In atoms beam are presented. The proposed method provides for the spatial resolution at the level of 10-100 mu m

  15. Trace analysis of actinides in the environment using resonance ionization mass spectrometry

    International Nuclear Information System (INIS)

    Raeder, Sebastian

    2011-01-01

    In this work the resonant ionization of neutral atoms using laser radiation was applied and optimized for ultra-trace analysis of the actinides thorium, uranium, neptunium and plutonium. The sensitive detection of these actinides is a challange for the monitoring and quantification of radioactive releases from nuclear facilities. Using resonance ionization spectroscopy combined with a newly developed quadrupole-mass-spectrometer, numerous energy levels in the atomic structure of these actinides could be identified. With this knowledge efficient excitation schemes for the mentioned actinides could be identified and characterised. The applied in-source-ionization ensures for a high detection efficiency due to the good overlap of laser radiation with the atomic beam and allows therefore for a low sample consumption which is required for the analysis of radio nuclides. The selective excitation processes in the resonant ionization method supresses unwanted contaminations and was optimized for analytical detection of ultra-trace amounts in environmental samples as well as for determination of isotopic compositions. The efficient in-source-ionization combined with high power pulsed laser radiation allows for detections efficiency up to 1%. For plutonium detection limits in the range of 10 4 -10 5 atoms could be demonstrated for synthetic samples as well as for first environmental samples. The usage of narrow bandwidth continuous wave lasers in combination with a transversal overlap of the laser radiation and the free propagating atomic beam enable for resolving individual isotopic shifts of the resonant transitions. This results in a high selectivity against dominant neighboring isotopes but with a significant loss in detection efficiency. For the ultra-trace isotope 236 U a detection limit down to 10 -9 for the isotope ratio N ( 236 U)/N ( 238 U) could be determined.

  16. Multiphoton ionization processes in strong laser

    International Nuclear Information System (INIS)

    Krstic, P.

    1982-01-01

    Multiphoton ionization of hydrogen in ultrastrong laser fields is studied. The previous calculations of this process yield differing result for the transition rate. We show the relations between them and difficulties with each of them. One difficulty is that the finite spatial and time extent of the laser field has been omitted. It is also found that a laser field, which is sufficiently intense to be labeled ultrastrong, makes the electron move relativistically so that it becomes necessary to use Volkov states to describe the electron in the laser field. The transition rate is obtained, using a CO laser as an example, and it is found that the transition rate rises as the laser intensity rises. This is a consequence of the use of relativistic kinematics and is not true nonrelativistically. We also discuss the multiple peaks observed in the energy spectrum of electrons resulting from multiphoton ionization of atoms by lasers. When the laser intensity is large enough for the ponderomotive force to result in appreciable broading of the peaks we show the shape of the broadened peaks contains useful information. We show that the multiphoton ionization probability as a function of laser intensity can be obtained but that the free-free cross sections, which are in principle also obtainable, are probably not obtainable in practice. Finally, we describe the theory of the absorption of more than minimum numbers of photons needed to ionize an atom by an intense laser. The basic approximation used is that the atom is adiabatically deformed by the laser and an impulsive interaction then results in multiphoton absorption. In our first calculation we allow only one resonant excited state to be included in the adiabatic deformation. In our second we also allow the lowest energy continuum to be included. The two results are then compared

  17. Diode laser based resonance ionization mass spectrometry for spectroscopy and trace analysis of uranium isotopes

    International Nuclear Information System (INIS)

    Hakimi, Amin

    2013-01-01

    In this doctoral thesis, the upgrade and optimization of a diode laser system for high-resolution resonance ionization mass spectrometry is described. A frequency-control system, based on a double-interferometric approach, allowing for absolute stabilization down to 1 MHz as well as frequency detunings of several GHz within a second for up to three lasers in parallel was optimized. This laser system was used for spectroscopic studies on uranium isotopes, yielding precise and unambiguous level energies, total angular momenta, hyperfine constants and isotope shifts. Furthermore, an efficient excitation scheme which can be operated with commercial diode lasers was developed. The performance of the complete laser mass spectrometer was optimized and characterized for the ultra-trace analysis of the uranium isotope 236 U, which serves as a neutron flux dosimeter and tracer for radioactive anthropogenic contaminations in the environment. Using synthetic samples, an isotope selectivity of ( 236 U)/( 238 U) = 4.5(1.5) . 10 -9 was demonstrated.

  18. Resonant ionization by laser beams: application to ions sources and to study the nuclear structure of radioactive tellurium isotopes; Ionisation resonante par faisceaux laser: application aux sources d'ions et a l'etude de la structure des noyaux radioactifs de tellure

    Energy Technology Data Exchange (ETDEWEB)

    Sifi, R

    2007-07-15

    The radioactive ion beams that are produced through current isotope separators are well separated according to the A mass but not according to the Z parameter. The resonant ionization through laser beams applied to ion sources allows the production of radioactive ion beam in a very selective and efficient way by eliminating the isobaric contamination. The first chapter is dedicated to the resonant ionization by laser beams, we describe the principle, the experimental setting, the lasers used, the ionization schemes and the domain of application. The second chapter deals with the application of resonant ionization to laser ion sources for the production of radioactive ion beams. We present experimental tests performed for getting copper ion beams. Resonant ionization through laser is also used in the spectroscopy experiments performed at the Isolde (isotope separation on-line device) installation in CERN where more than 20 elements are ionized very efficiently. The technique is based on a frequency scanning around the excitation transition of the atoms in order to probe the hyperfine structure. Laser spectroscopy allows the determination of the hyperfine structure as well as the isotopic shift of atoms. In the third chapter the method is applied to the spectroscopy of tellurium atoms. First, we define the 2 parameters on which the extraction is based: charge radius and nuclear moments, then we present several theoretical models that we have used to assess our experimental results. (A.C.)

  19. Resonance ionization spectroscopy of Europium The first application of the PISA at ISOLDE-RILIS

    CERN Document Server

    AUTHOR|(CDS)2099873; Marsh, Bruce Alan

    The following work has been carried out at the radioactive ion beam facility ISOLDE at CERN. A compact atomic beam unit named PISA (Photo Ionization Spectroscopy Apparatus) has been implemented as a recent addition to the laboratory of the Resonance Ionization Laser Ion Source (RILIS). The scope of this thesis work was to demonstrate different applications of the PISA, using the existing and highly developed laser setup of the RILIS installation. In a demonstration of the suitability of PISA for ionization scheme development, a new ionization scheme for Europium has been developed. This resulted in the observation of several new autoionizing states and Rydberg series. Through the analysis of the observed Rydberg resonances a refined value of $45734.33(3)(3)$ cm$^{-1}$ for the ionization potential of the europium atom has been determined. In addition this thesis reports on the feasibility of the use of the PISA as a RILIS performance monitoring device during laser ion source operations. Finally the present wor...

  20. Progress in zirconium resonance ionization spectroscopy

    International Nuclear Information System (INIS)

    Page, R.H.; Dropinski, S.C.; Worden, E.F.; Stockdale, J.A.D.

    1993-01-01

    The authors have examined the stepwise-resonant three-photon-ionization spectrum of neutral zirconium atoms using three separately-tunable pulsed visible dye lasers. The ground-level (first-step) transitions were chosen on the basis of demonstrated 91 Zr selectivity. Lifetimes of even-parity levels around 36,000 cm -1 , measured with the delayed-photoionization technique, range from 10 to 100 nsec. Direct ionization cross sections appear to be less than 10 -17 cm 2 ; newly-detected autoionizing levels give peak ionization cross sections (inferred from saturation fluences) up to 10 -15 cm 2 . Portions of Rydberg series converging to the 315 and 763 cm -1 levels of Zr + were identified. Clumps of autoionizing levels are thought to be due to Rydberg-valence mixing

  1. Laser post-ionization secondary neutral mass spectroscopy

    International Nuclear Information System (INIS)

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

    1987-01-01

    Three different instruments using laser ionization techniques will be described. Results from the SARISA instrument with a demonstrated figure of merit of .05 (atoms detected/atoms sputtered) for resonance ionization; detection of Fe at the sub-part-per-billion level in ultrapure Si; and features of the instrument such as energy and angle refocusing time-of-flight (EARTOF) mass spectrometer and multiplexing for simultaneous detection of secondary ions and neutrals. 12 refs., 3 figs

  2. Pulsed plasma sources for the production of intense ion beams based on catalytic resonance ionization

    International Nuclear Information System (INIS)

    Knyazev, B.A.; Mel'nikov, P.I.; Bluhm, H.

    1994-01-01

    In this paper we describe a technique to produce planar and volumetric ion sources of nearly every element. This technique is based on a generalization of the LIBORS-process (Laser Ionization Based On Resonant Saturation) which because of its similarity to chemical catalytic reactions has been called CATRION (CATalytic Resonance IONization). A vapor containing the desired atomic species is doped with a suitable element processing resonance transitions that can be pumped ro saturation with a laser. By superelastic collisions with the excited atoms and by simulated bremsstrahlung absorption seed electrons are heated. It is the heated electron component which then by collisional processes ionizes the desired atomic species and are multiplied. 41 refs.; 4 figs.; 3 tabs

  3. Application of resonance ionization mass spectrometry for trace analysis and in fundamental research

    International Nuclear Information System (INIS)

    Passler, G.

    1997-01-01

    Resonance ionization mass spectrometry (RIMS) has been used for ultra-trace analysis on long-lived radioisotopes like Pu, Tc and 89,90 Sr in various environmental samples. The experimental approaches cover pulsed laser spectroscopy on a thermal atomic beam and subsequent time-of-flight mass analysis, a pulsed laser ion source combined with conventional mass spectrometry, and collinear resonance ionization on a mass-separated fast atomic beam. The high sensitivity of RIMS also enables atomic spectroscopy on rare isotopes. For the first time experimental values for the ionization potential of actinides up to Cf have been determined. The paper reviews the dependency of the different experimental approaches on the analytical problem. copyright 1997 American Institute of Physics

  4. Isomer separation of $^{70g}Cu$ and $^{70m}Cu$ with a resonance ionization laser ion source

    CERN Document Server

    Köster, U; Mishin, V I; Weissman, L; Huyse, M; Kruglov, K; Müller, W F; Van Duppen, P; Van Roosbroeck, J; Thirolf, P G; Thomas, H C; Weisshaar, D W; Schulze, W; Borcea, R; La Commara, M; Schatz, H; Schmidt, K; Röttger, S; Huber, G; Sebastian, V; Kratz, K L; Catherall, R; Georg, U; Lettry, Jacques; Oinonen, M; Ravn, H L; Simon, H

    2000-01-01

    Radioactive copper isotopes were ionized with the resonance ionization laser ion source at the on-line isotope separator ISOLDE (CERN). Using the different hyperfine structure in the 3d/sup 10/ 4s /sup 2/S/sub 1/2/-3d/sup 10/ 4p /sup 2/P/sub 1/2//sup 0/ transition the low- and high-spin isomers of /sup 70/Cu were selectively enhanced by tuning the laser wavelength. The light was provided by a narrow-bandwidth dye laser pumped by copper vapor lasers and frequency doubled in a BBO crystal. The ground state to isomeric state intensity ratio could be varied by a factor of 30, allowing to assign gamma transitions unambiguously to the decay of the individual isomers. It is shown that the method can also be used to determine magnetic moments. In a first experiment for the 1/sup +/ ground state of /sup 70/Cu a magnetic moment of (+)1.8(3) mu /sub N/ and for the high-spin isomer of /sup 70/Cu a magnetic moment of (+or-)1.2(3) mu /sub N/ could be deduced. (20 refs).

  5. A Study of the r-Process Path Nuclides,$^{137,138,139}$Sb using the Enhanced Selectivity of Resonance Ionization Laser Ionization

    CERN Multimedia

    Walters, W

    2002-01-01

    The particular features of the r-process abundances with 100 < A < 150 have demonstrated the close connection between knowledge of nuclear structure and decay along the r-process path and the astrophysical environement in which these elements are produced. Key to this connection has been the measurement of data for nuclides (mostly even-N nuclides) that lie in the actual r-process path. Such data are of direct use in r-process calculations and they also serve to refine and test the predictive power of nuclear models where little or no data now exist. In this experiment we seek to use the newly developed ionization scheme for the Resonance Ionization Laser Ion Source (RILIS) to achieve selective ionization of neutron-rich antimony isotopes in order to measure the decay properties of r-process path nuclides $^{137,138,139}$Sb. These properties include the half-lives, delayed neutron branches, and daughter $\\gamma$-rays. The new nuclear structure data for the daughter Te nuclides is also of considerable in...

  6. Determination of organic compounds in nano-particles by laser breakdown and resonant ionization time-of-flight mass spectrometry

    International Nuclear Information System (INIS)

    Deguchi, Yoshihiro; Tanaka, Nobuyuki

    2005-01-01

    Laser breakdown and resonance ionization time-of-flight mass spectrometry (TOFMS) with a differential mobility analyzer (DMA) was developed and applied to detect compositions and organic substances in nano-particles. The laser breakdown TOFMS method is capable of reaching pptv sensitivity, which is generally much better than the normal LIBS techniques. The system was demonstrated to successfully detect signals in the mass range of 1 to 300 amu for 60 and 140 nm particles in diesel engine exhaust. The detected signals showed that the nano-particles contained both aromatic and chain hydrocarbons

  7. Theory of the effect of third-harmonic generation on three-photon resonantly enhanced multiphoton ionization in focused beams

    International Nuclear Information System (INIS)

    Payne, M.G.; Garrett, W.R.

    1983-01-01

    Multiphoton ionization in the region near a three-photon resonance is treated for focused, plane-polarized Gaussian beams with diffraction-limited beam divergence. In this situation, a third-harmonic field is generated within the laser beam. At, and very near, three-photon resonance the driving rate for the upper-state probability amplitude due to one-photon absorption of third-harmonic light becomes nearly equal to the corresponding three-photon rate due to the laser field, but these effects are 180 0 out of phase. As a consequence of this cancellation between two pumping terms, the three-photon resonance line essentially disappears at moderate concentrations and the observed ionization has a line shape that is close to the phase-matching curve for third-harmonic generation. The ionization signal, near but not on the resonance, is due almost entirely to absorption of third-harmonic photons plus other laser photons; three-photon resonantly enhanced multiphoton ionization by the laser is much weaker. This is particularly true on the blue side of the three-photon resonance at detunings where phase matching occurs. The problem is treated quite generally with predictions of the full line shape for n-photon ionization and third-harmonic light generation near three-photon resonance, including the rather strong influences of positively dispersive buffer gases. We also show that the cancellation between the one-photon and the three-photon process is partially spoiled in the presence of a counterpropagating beam at the same frequency

  8. Determination of trace elements by resonant ionization mass spectrometry (RIMS)

    International Nuclear Information System (INIS)

    Ruster, W.; Ames, F.; Rehklau, D.; Mang, M.; Muehleck, C.; Rimke, H.; Sattelberger, P.; Herrmann, G.; Trautmann, N.; Kluge, H.J.; Otten, E.W.

    1988-01-01

    A resonant ionization mass spectrometer has been developed as an analytical tool for the detection of trace elements, especially of plutonium and other radionuclides. The sample, deposited on a rhenium filament, is evaporated by electrical heating and the atoms of the element under investigation are selectively ionized by laser light delivered from three dye lasers pumped by a copper vapour laser. The resulting photoions are detected in a time-of-flight spectrometer with a channelplate detector. For plutonium a mass resolution of M/ΔM=1500 was obtained and an overall detection efficiency of 4x10 -6 was determined for stepwise excitation and ionization via autoionizing states. With a laser light bandwidth of 3-5 GHz neighbouring isotopes could be suppressed by a factor of 20 due to isotope shifts in the excitation transitions. The isotope composition of synthetic samples was measured and good agreement was found with mass spectroscopic results. The influence of the hyperfine structure on the isotope ratios is discussed. (orig.)

  9. Ionization mechanism of cesium plasma produced by irradiation of dye laser

    International Nuclear Information System (INIS)

    Yamada, Jun; Shibata, Kohji; Uchida, Yoshiyuki; Hioki, Yoshiaki; Sahashi, Toshio.

    1992-01-01

    When a cesium vapor was irradiated by a dye laser which was tuned to the cesium atomic transition line, the number of charged particles produced by the laser radiation was observed. Several sharp peaks in the number of charged particles were observed, which corresponded to the atomic transition where the lower level was the 6P excited atom. The ionization mechanism of the laser-produced cesium plasma has been discussed. An initial electron is produced by laser absorptions of the cesium dimer. When the cesium density is high, many 6P excited atoms are excited by electron collisions. The 6P excited atom further absorbs the laser photon and is ionized through the higher-energy state. As the cesium vapor pressure increases, the resonance effect becomes observable. The 6P excited atom plays dominant role in the ionization mechanism of the laser-produced cesium plasma. (author)

  10. Development of resonance-enhanced multiphoton ionization system

    International Nuclear Information System (INIS)

    Naik, P.D.; Upadhyaya, Hari P.; Kumar, Awadhesh; Bajaj, P.N.; Sinha, A.K.; Bhatt, S.; Gupta, M.D.P.

    2009-05-01

    Radiation and Photochemistry Division has developed a Molecular Beam-Resonance Enhanced Multiphoton Ionization-Time-of-Flight spectrometer, a highly sensitive and selective analytical detection system, for investigation of photodissociation dynamics of isolated molecules. In this system, the molecular beam is intersected in the extraction region of a Wiley-McLaren type Time-of-Flight mass spectrometer by the photolysis laser beam, propagating perpendicular to both the molecular beams and the Time-of-Flight tube. The probe (ionization) laser beam counter propagating to the photolysis beam, ionizes the stable products and the radicals produced on photodissociation. The important features of the system, namely, the resolution and the detection limit, have been determined from the studies of aniline molecular beam, generated by seeding 1% aniline in helium. For the present configuration, using one metre long flight tube, the resolution has been found to be about 400, and detection limit is better than 106 species per cm 3 . The integrity of the set-up is obtained from the photodissociation dynamics studies of bromoform. (author)

  11. Resonance ionization spectroscopy 1990

    International Nuclear Information System (INIS)

    Parks, J.E.; Omenetto, N.

    1991-01-01

    The Fifth International Symposium on Resonance Ionization Spectroscopy (RIS) and its Applications was held in Varese, Italy, 16-21 September 1990. Interest in RIS and its applications continues to grow, and RIS is expanding into a more diverse and mature field of study. This maturity was evident in this meeting both in the basic science and understanding of RIS processes and in the number of new and improved applications and techniques. The application of RIS techniques to molecular detection problems made remarkable progress since the last meeting two years ago. Subtle effects pertaining to isotopic discrimination received more theoretical attention, and there now seems to be good understanding of these effects, which can lead to correction procedures and/or methods to avoid isotopic effects. RIS applications were presented in which significant, real world problems were addressed, demonstrating its capability to solve problems that previously could not be accurately solved by other more traditional techniques. The contributions to the conference are grouped under the following major topic headings: physics applications of rare atoms; laser ionization mechanisms - spectroscopy; atomic, molecular and ion sources; molecular RIS; atomic RIS - Rydberg states; environmental trace analysis; biological and medical applications; state selected chemistry; new laser sources and techniques; ultra-high resolution and isotopic selectivity; surface and bulk analysis. (Author)

  12. Effects of four-wave mixing on four-photon resonance excitation and ionization in the presence of a three-photon intermediate state resonance enhancement

    International Nuclear Information System (INIS)

    Payne, M.G.; Miller, J.C.; Hart, R.C.; Garrett, W.R.

    1991-01-01

    We consider effects which occur when four-wave sum frequency generation and multiphoton ionization are induced by lasers tuned near a three-photon resonance and simultaneously near or at a dipole allowed four-photon resonance. In studies with unfocused laser beams, if the phase mismatch of the generated four-wave-mixing field is large and the related two-photon resonance for the absorption of a four-wave-mixing photon and a laser photon results in strong absorption of the four-wave-mixing field, a coherent cancellation occurs between the pumping of the resonance by two- and four-photon processes. This interference effect occurs when the first laser is tuned on either side of the three-photon resonance and |Δk rL |much-gt 1, where Δk r is the mismatch and L is the length of the path of the laser beams in the gas. With focused laser beams large differences occur between ionization with unidirectional beams and with counterpropagating laser beams when |Δk rb |much-gt 1, where b is the confocal parameter of the focused laser beams. Strong absorption of the four-wave-mixing field is shown not to be necessary for strong destructive interference with focused laser beams when the phase mismatch is large. This work also suggests an explanation for earlier experiments where the presence of a four-photon resonance enabled the generation of third-harmonic light in a positively dispersive wavelength region. We argue that this process can occur when the laser used to achieve the four-photon resonance is focused on the small z (z is the coordinate in the direction of propagation) side of the focal point of the laser responsible for the third-harmonic generation

  13. Resonant laser ablation: mechanisms and applications

    International Nuclear Information System (INIS)

    Anderson, J.E.; Bodla, R.; Eiden, G.C.; Nogar, N.S.; Smith, C.H.

    1996-01-01

    Resonant laser ablation (RLA) typically relies on irradiation of a sample in a mass spectrometer with modest intensity laser pulses tuned to a one or two photon resonant transition in the analyte of interest. This paper shows that RLA is well suited for highly sensitive analyses of complex samples. The examples actually studied are trace components in rhenium and technetium in nickel. The authors also studied the 2+1 multiphoton ionization spectrum of iron-56 detected by RLA of Re containing 70 ppm iron. Two-photon transition rates for Fe transitions were calculated perturbatively and found to agree semi-quantitatively with experimentally observed intensities. 17 refs., 3 figs

  14. Reactions of metal ions and their clusters in the gas phase using laser ionization: ion cyclotron resonance spectroscopy

    International Nuclear Information System (INIS)

    Freiser, B.S.

    1981-04-01

    Two subjects are discussed in this report: advances in proposed studies on metal ion chemistry and expansion of laboratory facilities. The development of a combined pulsed laser source-ion cyclotron resonance spectrometer has proven to be a convenient and powerful method for generating metal ions and for studying their subsequent chemistry in the gas phase. The main emphasis of this research has been on the application of metal ions as a selective chemical ionization reagents and progress in this area are discussed. The goal is to identify trends in reactivity i.e. mechanisms useful in interpreting the chemical ionization spectra of unknown compounds and to test for the functional group selectivity of the various metal ions. The feasibility of these goals have been demonstrated in extensive studies on Cu + with esters and ketones, on Fe + with ethers, ketones, and hydrocarbons, and on Ti + with hydrocarbons. In addition, preliminary results on sulfur containing compounds and on a variety of other metallic ions have been obtained. Laboratory facilities were expanded from one ion cyclotron resonance (ICR) spectrometer to two, plus a third instrument the Fourier Transform Ion Cyclotron Resonance (FTICR) spectrometer

  15. Laser-enhanced ionization spectroscopy around the ionization limit

    International Nuclear Information System (INIS)

    Axner, O.; Berglind, T.; Sjoestroem, S.

    1986-01-01

    Laser-induced photoionization and Laser-Enhanced collision Ionization (LEI) of Na, Tl, and Li in flames are detected by measuring the production of charges following a laser excitation. The ionization signal is investigated for excitations of the atoms from lower lying states both to Rydberg states close to the ionization limit, as well as to continuum states, i.e. the process of collision ionization is compared with that of photoionization. The qualitative behaviour of the ionization signal when scanning across the ionization limit is studied. It is shown that the ionization signal has a smooth behaviour when passing from bound states into continuum states. The laser-induced photoionization signal strength of atoms in flames is both calculated and measured and a good agreement is obtained. A calculation of wavelength dependent photoionization signal strengths for a number of elements is also presented. Photoionization is used to determine flame- and geometry-dependent parameters. An implication of photoionization in connection with LEI spectrometry for trace element analysis is that there will be a significant increase in background noise if the sample contains high concentrations of easily photoionizing elements and short wavelength light is used. (orig.)

  16. Matrix-assisted laser-desorption-ionization mass spectrometry of proteins using a free-electron laser

    International Nuclear Information System (INIS)

    Cramer, R.; Hillenkamp, F.; Haglund, R.

    1995-01-01

    Matrix-assisted laser desorption-ionization (MALDI) mass spectrometry (MS) is one of the most promising techniques for spectral fingerprinting large molecules, such as proteins, oligonucleotides and carbohydrates. In the usual implementation of this technique, the analyte molecule is dissolved in an aromatic liquid matrix material which resonantly absorbs ultraviolet laser light. Resonant absorption by π-π* transitions volatilizes the matrix and initiates subsequent charge transfer to the analyte molecules, which are detected by time-of-flight mass spectrometry. Recent MALDI-MS studies with Er:YAG (2.94 μm) and CO 2 4 (9.4-10.6 μm) lasers suggest that them is significant unexplored potential for mass spectrometry of macromolecules, including oligonucleotide, in the mid-infrared. Preliminary experiments show that it is possible to capitalize on the rich rovibronic absorption spectrum of virtually all organics to initiate resonant desorption in matrix material over the entire range of pH values. However, the mechanism of charge transfer is particularly problematic for infrared MALDI because of the low photon energy. In this paper, we report the results of MALI-MS studies on small proteins using the Vanderbilt FEL and several matrix materials. Proteins with masses up to roughly 6,000 amu were detected with high resolution in a linear time-of-flight mass spectrometer. By varying the pulse duration using a broadband Pockels cell, we have been able to compare the results of relatively long (5 μs) and short (0.1 μs) irradiation on the desorption and ionization processes. Compared to uv-MALDI spectra of identical analytes obtained with a nitrogen laser (337 nm) in the same time-of-flight spectrometer, the infrared results appear to show that the desorption and ionization process goes on over a somewhat longer time scale

  17. X-ray laser studies using plasmas created by optical field ionization

    International Nuclear Information System (INIS)

    Krushelnick, K.M.; Tighe, W.; Suckewer, S.

    1995-01-01

    X-ray laser experiments involving the creation of fast recombining plasmas by optical field ionization of preformed targets were conducted. A nonlinear increase in the intensity of the 13.5nm Lyman-α line in Li III with the length of the target plasma was observed but only for distances less than the laser confocal parameter and for low plasma electron temperatures. Multiphoton pumping of resonant atomic transitions was also examined and the process of multiphoton ionization of FIII was found to be more probable than multiphoton excitation

  18. Detection of single atoms by resonance ionization spectroscopy

    International Nuclear Information System (INIS)

    Hurst, G.S.

    1986-01-01

    Rutherford's idea for counting individual atoms can, in principle, be implemented for nearly any type of atom, whether stable or radioactive, by using methods of resonance ionization. With the RIS technique, a laser is tuned to a wavelength which will promote a valence electron in a Z-selected atom to an excited level. Additional resonance or nonresonance photoabsorption steps are used to achieve nearly 100% ionization efficiencies. Hence, the RIS process can be saturated for the Z-selected atoms; and since detectors are available for counting either single electrons or positive ions, one-atom detection is possible. Some examples are given of one-atom detection, including that of the noble gases, in order to show complementarity with AMS methods. For instance, the detection of 81 Kr using RIS has interesting applications for solar neutrino research, ice-cap dating, and groundwater dating. 39 refs., 7 figs., 2 tabs

  19. Development of an Ionization Scheme for Gold using the Selective Laser Ion Source at the On-Line Isotope Separator ISOLDE

    CERN Document Server

    Fedosseev, V; Marsh, B A; CERN. Geneva. AB Department

    2006-01-01

    At the ISOLDE on-line isotope separation facility, the resonance ionization laser ion source (RILIS) can be used to ionize reaction products as they effuse from the target. The RILIS process of laser step-wise resonance ionization of atoms in a hot metal cavity provides a highly element selective stage in the preparation of the radioactive ion beam. As a result, the ISOLDE mass separators can provide beams of a chosen isotope with greatly reduced isobaric contamination. The number of elements available at RILIS has been extended to 26, with the addition of a new three-step ionization scheme for gold. The optimal ionization scheme was determined during an extensive study of the atomic energy levels and auto-ionizing states of gold, carried out by means of in-source resonance ionization spectroscopy. Details of the ionization scheme and a summary of the spectroscopy study are presented.

  20. In-gas-cell laser ionization studies of plutonium isotopes at IGISOL

    Science.gov (United States)

    Pohjalainen, I.; Moore, I. D.; Kron, T.; Raeder, S.; Sonnenschein, V.; Tomita, H.; Trautmann, N.; Voss, A.; Wendt, K.

    2016-06-01

    In-gas-cell resonance laser ionization has been performed on long-lived isotopes of Pu at the IGISOL facility, Jyväskylä. This initiates a new programme of research towards high-resolution optical spectroscopy of heavy actinide elements which can be produced in sufficient quantities at research reactors and transported to facilities elsewhere. In this work a new gas cell has been constructed for fast extraction of laser-ionized elements. Samples of 238-240,242Pu and 244Pu have been evaporated from Ta filaments, laser ionized, mass separated and delivered to the collinear laser spectroscopy station. Here we report on the performance of the gas cell through studies of the mass spectra obtained in helium and argon, before and after the radiofrequency quadrupole cooler-buncher. This provides valuable insight into the gas phase chemistry exhibited by Pu, which has been additionally supported by measurements of ion time profiles. The resulting monoatomic yields are sufficient for collinear laser spectroscopy. A gamma-ray spectroscopic analysis of the Pu samples shows a good agreement with the assay provided by the Mainz Nuclear Chemistry department.

  1. High-resolution, three-step resonance ionization mass spectrometry of gadolinium

    International Nuclear Information System (INIS)

    Blaum, K.; Wendt, K.; Bushaw, B.A.; Noertershaeuser, W.

    2001-01-01

    High-resolution resonance ionization mass spectrometry has been used to measure triple-resonance autoionization (AI) spectra of gadolinium. Al resonances as narrow as 10 MHz have been observed and isotope shifts and hyperfine structure have been measured in selected AI states. The strongest AI state observed at 49663.576 cm-1 with a photoionization cross section of >3.6x10 -15 cm 2 was found to have an overall detection efficiency of >3x10 -5 , allowing application to a number of ultratrace determination problems. Analytical measurements with a diode-laser-based system have been successfully performed on bio-medical tissue samples

  2. Experimental REMPI [Resonance Enhanced Multiphoton Ionization] studies of small molecules

    International Nuclear Information System (INIS)

    Dehmer, J.L.; Dehmer, P.M.; Pratt, S.T.; O'Halloran, M.A.; Tomkins, F.S.

    1986-01-01

    Resonance Enhanced Multiphoton Ionization (REMPI) utilizes tunable dye lasers to ionize an atom or molecule by first preparing an excited state by multiphoton absorption and then ionizing that state before it can decay. This process is highly selective with respect to both the initial and resonant intermediate states of the target, and it can be extremely sensitive. In addition, the products of the REMPI process can be detected as needed by analyzing the resulting electrons, ions, fluorescence, or by additional REMPI. This points to a number of exciting opportunities for both basic and applied science. On the applied side, REMPI has great potential as an ultrasensitive, highly selective detector for trace, reactive, or transient species. On the basic side, REMPI affords an unprecedented means of exploring excited state physics and chemistry at the quantum-state-specific level. We shall give an overview together with examples of current studies of excited molecular states to illustrate the principles of and prospects for REMPI. 27 refs., 3 figs

  3. A new in-gas-laser ionization and spectroscopy laboratory for off-line studies at KU Leuven

    International Nuclear Information System (INIS)

    Kudryavtsev, Yu.; Creemers, P.; Ferrer, R.; Granados, C.; Gaffney, L.P.; Huyse, M.; Mogilevskiy, E.; Raeder, S.; Sels, S.; Van den Bergh, P.; Van Duppen, P.; Zadvornaya, A.

    2016-01-01

    The in-gas laser ionization and spectroscopy (IGLIS) technique is used to produce and to investigate short-lived radioactive isotopes at on-line ion beam facilities. In this technique, the nuclear reaction products recoiling out of a thin target are thermalized and neutralized in a high-pressure noble gas, resonantly ionized by the laser beams in a two-step process, and then extracted from the ion source to be finally accelerated and mass separated. Resonant ionization of radioactive species in the supersonic gas jet ensures very high spectral resolution because of essential reduction of broadening mechanisms. To obtain the maximum efficiency and the best spectral resolution, properties of the supersonic jet and the laser beams must be optimized. To perform these studies a new off-line IGLIS laboratory, including a new high-repetition-rate laser system and a dedicated off-line mass separator, has been commissioned. In this article, the specifications of the different components necessary to achieve optimum conditions in laser-spectroscopy studies of radioactive beams using IGLIS are discussed and the results of simulations are presented.

  4. Isotopically selective RIMS of rare radionuclides by double-resonance excitation with cw lasers

    International Nuclear Information System (INIS)

    Bushaw, B.A.; Munley, J.T.

    1990-09-01

    Double-resonance, Resonance Ionization Mass Spectroscopy (RIMS) using two single-frequency dye lasers and a CO 2 laser for photoionization has been shown to be both extremely sensitive and highly selective. Measurements on the radioisotope 210 Pb have demonstrated optical selectivity in excess of 10 9 and detection limits of less than 1 femtogram

  5. Simultaneous atomization and ionization of large organic molecules using femtosecond laser ablation

    International Nuclear Information System (INIS)

    Kurata-Nishimura, Mizuki; Tokanai, Fuyuki; Matsuo, Yukari; Kobayashi, Tohru; Kawai, Jun; Kumagai, Hiroshi; Midorikawa, Katsumi; Tanihata, Isao; Hayashizaki, Yoshihide

    2002-01-01

    We have experimentally demonstrated femtosecond laser ablation for simultaneous atomization and ionization (fs-SAI) of organic molecules on solid substrates. We find most of the constituent atoms of organic molecules are atomized and ionized non-resonantly by femtosecond laser ablation. This observation is in contrast with that for the photoionization of cyclic aromatic hydrocarbons by femtosecond laser in the gas phase where little fragmentation has been observed. Crucial contribution of ablation plasma of solid sample to fs-SAI process is suggested. The ratio of natural abundance of stable isotopes contained in sample molecules is well reproduced, which confirms fs-SAI can be applied to the quantitative chemical analysis of isotope-labeled large organic molecules

  6. In-gas-cell laser ionization studies of plutonium isotopes at IGISOL

    International Nuclear Information System (INIS)

    Pohjalainen, I.; Moore, I.D.; Kron, T.; Raeder, S.; Sonnenschein, V.; Tomita, H.; Trautmann, N.; Voss, A.; Wendt, K.

    2016-01-01

    In-gas-cell resonance laser ionization has been performed on long-lived isotopes of Pu at the IGISOL facility, Jyväskylä. This initiates a new programme of research towards high-resolution optical spectroscopy of heavy actinide elements which can be produced in sufficient quantities at research reactors and transported to facilities elsewhere. In this work a new gas cell has been constructed for fast extraction of laser-ionized elements. Samples of "2"3"8"–"2"4"0","2"4"2Pu and "2"4"4Pu have been evaporated from Ta filaments, laser ionized, mass separated and delivered to the collinear laser spectroscopy station. Here we report on the performance of the gas cell through studies of the mass spectra obtained in helium and argon, before and after the radiofrequency quadrupole cooler-buncher. This provides valuable insight into the gas phase chemistry exhibited by Pu, which has been additionally supported by measurements of ion time profiles. The resulting monoatomic yields are sufficient for collinear laser spectroscopy. A gamma-ray spectroscopic analysis of the Pu samples shows a good agreement with the assay provided by the Mainz Nuclear Chemistry department.

  7. Optically-ionized plasma recombination x-ray lasers

    International Nuclear Information System (INIS)

    Amendt, P.; Eder, D.C.; Wilks, S.C.; Dunning, M.J.; Keane, C.J.

    1991-01-01

    Design studies for recombination x-ray lasers based on plasmas ionized by high intensity, short pulse optical lasers are presented. Transient lasing on n = 3 to n = 2 transitions in Lithium-like Neon allows for moderately short wavelengths (≤ 100 angstrom) without requiring ionizing intensities associated with relativistic electron quiver energies. The electron energy distribution following the ionizing pulse affects directly the predicted gains for this resonance transition. Efficiencies of 10 -6 or greater are found for plasma temperatures in the vicinity of 40 eV. Simulation studies of parametric heating phenomena relating to stimulated Raman and Compton scattering are presented. For electron densities less than about 2.5 x 10 20 cm -3 and peak driver intensity of 2 x 10 17 W/cm 2 at 0.25 μm with pulse length of 100 fsec, the amount of electron heating is found to be marginally significant. For Lithium-like Aluminum, the required relativistic ionizing intensity gives excessive electron heating and reduced efficiency, thereby rendering this scheme impractical for generating shorter wavelength lasing (≤ 50 angstrom) in the transient case. Following the transient lasing phase, a slow hydrodynamic expansion into the surrounding cool plasma is accompanied by quasi-static gain on the n = 4 to n = 3 transition in Lithium-like Neon. Parametric heating effects on gain optimization in this regime are also discussed. 18 refs., 6 figs

  8. Resonance ionization mass spectrometry of ion beam sputtered neutrals for element- and isotope-selective analysis of plutonium in micro-particles

    Energy Technology Data Exchange (ETDEWEB)

    Erdmann, N. [Institute for Transuranium Elements, European Commission Joint Research Centre, Karlsruhe (Germany); Kratz, J.V.; Trautmann, N. [Johannes Gutenberg-University Mainz, Institute of Nuclear Chemistry, Mainz (Germany); Passler, G. [Johannes Gutenberg-University Mainz, Institute of Physics, Mainz (Germany)

    2009-11-15

    Micro-particles containing actinides are of interest for risk assessments of contaminated areas, nuclear forensic analyses, and IAEA as well as Euratom safeguards programs. For their analysis, secondary ion mass spectrometry (SIMS) has been established as the state-of-the-art standard technique. In the case of actinide mixtures within the particles, however, SIMS suffers from isobaric interferences (e.g., {sup 238}U/{sup 238}Pu, {sup 241}Am/{sup 241}Pu). This can be eliminated by applying resonance ionization mass spectrometry which is based on stepwise resonant excitation and ionization of atoms with laser light, followed by mass spectrometric detection of the produced ions, combining high elemental selectivity with the analysis of isotopic compositions. This paper describes the instrumental modifications for coupling a commercial time-of-flight (TOF)-SIMS apparatus with three-step resonant post-ionization of the sputtered neutrals using a high-repetition-rate (kHz) Nd:YAG laser pumped tunable titanium:sapphire laser system. Spatially resolved ion images obtained from actinide-containing particles in TOF-SIMS mode demonstrate the capability for isotopic and spatial resolution. Results from three-step resonant post-ionization of bulk Gd and Pu samples successfully demonstrate the high elemental selectivity of this process. (orig.)

  9. Radionuclide measurements using resonantly enhanced collisional ionization

    International Nuclear Information System (INIS)

    Whitaker, T.J.; Bushaw, B.A.; Gerke, G.K.

    1987-01-01

    This report describes development of a laser-enhanced collisional ionization method for direct radionuclide measurements that are independent of radioactive decay. The technique uses two nitrogen-laser-pumped dye lasers to selectively excite the target isotope to an electronic state near the ionization threshold. The excited actinide atoms then undergo collisions with a buffer gas and are efficiently ionized. The resulting ions can be detected by conventional methods. The attributes of this approach include highly sensitive isotope analysis with relatively inexpensive lasers and a simple vacuum system. 9 refs., 3 figs

  10. Highly sensitive high resolution Raman spectroscopy using resonant ionization methods

    International Nuclear Information System (INIS)

    Owyoung, A.; Esherick, P.

    1984-05-01

    In recent years, the introduction of stimulated Raman methods has offered orders of magnitude improvement in spectral resolving power for gas phase Raman studies. Nevertheless, the inherent weakness of the Raman process suggests the need for significantly more sensitive techniques in Raman spectroscopy. In this we describe a new approach to this problem. Our new technique, which we call ionization-detected stimulated Raman spectroscopy (IDSRS), combines high-resolution SRS with highly-sensitive resonant laser ionization to achieve an increase in sensitivity of over three orders of magnitude. The excitation/detection process involves three sequential steps: (1) population of a vibrationally excited state via stimulated Raman pumping; (2) selective ionization of the vibrationally excited molecule with a tunable uv source; and (3) collection of the ionized species at biased electrodes where they are detected as current in an external circuit

  11. Cyclotron resonant gas breakdown with a 1.22-nm 13CH3F laser

    International Nuclear Information System (INIS)

    Hacker, M.P.; Lax, B.; Metz, R.N.; Temkin, R.J.

    1979-01-01

    Cyclotron-resonant laser-induced gas breakdown has been studied for the first time in the transverse geometry, using 1.222-nm 13 CH 3 F laser radiation propagating perpendicular to the magnetic field axis. The line shape of absorbed laser radiation versus magnetic field near electron cyclotron resonance (87.75 kG) indicates a strong dependence of the line shape on the focused laser intensity. This dependence is not predicted by the standard equilibrium theory of high-frequency gas breakdown in a magnetic field. We have developed an analytic theory to explain the observed line shapes. The theory takes into account the laser propagation characteristics, in particular that there is nonuniform ionization due to strong resonant absorption of the laser radiation in a length comparable to or shorter than that of the laser focal volume. The transverse geometry simplifies the theoretical analysis because the observed line shapes are not significantly affected by Doppler broadening. Extensive data have been obtained on the fraction of laser pulse energy absorbed in the gas breakdown volume as a function of magnetic field, helium gas pressure, and incident laser pulse energy. Good quantitative agreement is obtained between the observed laser pulse absorption line shapes and the nonuniform ionization theory

  12. Analysis of sample composition using resonant ionization and time-of-flight techniques

    International Nuclear Information System (INIS)

    Cruz, A. de la; Ortiz, M.; Campos, J.

    1995-01-01

    This paper describes the setting up of a linear time-of-flight mass spectrometer that uses a tunable laser to produce resonant ionization of atoms and molecules in a pulsed supersonic beam. The ability of this kind of systems to produce time resolved signals for each species present in the sample allows quantitative analysis of its composition. By using a tunable laser beam of high spectral resolution to produce ionization, studies based on the structure of the photoionization spectra obtained are possible. In the present work several isotopic species of ordinary and deuterated benzene have been studied. Special care has been dedicated to the influence of the presence of a 13C in the ring. In this way values for spectroscopic constants and isotopic shifts have been obtained. Another system based in a homemade proportional counter has been designed and used is an auxiliary system. The results obtained with it are independent of these mentioned above and compatible with them. This system is of great utility for laser wavelength tuning to produce ionization in the mass spectrometer. (Author) 98 refs

  13. Analysis of sample composition using resonant ionization and time-of-flight techniques

    International Nuclear Information System (INIS)

    Luz, A. de la; Ortiz, M.; Campos, J.

    1995-01-01

    This paper describes the setting up of a linear time-of-flight mass spectrometer that uses a tunable laser to produce resonant ionization of atoms and molecules in a pulsed supersonic beam. The ability of this kind of systems to produce time resolved signals for each species present in the samples allows quantitative analysis of its composition. By using a tunable laser beam of high spectral resolution to produce ionization, studies based on the structure of the photoionization spectra obtained are possible. In the present work several isotopic species of ordinary and deuterated benzene have been studies. special care has been dedicated to the influence of the presence of a ''13 C in the ring. In this way values for spectroscopic constants and isotopic shifts have been obtained. Another system based in a homemade proportional counter has been designed and used as an auxiliary system. The results obtained with it are independent of these mentioned above and compatible with them. This system is of great utility for laser wavelength tuning to produce ionization in the mass spectrometer

  14. Determination of Nerve Agent Metabolites by Ultraviolet Femtosecond Laser Ionization Mass Spectrometry.

    Science.gov (United States)

    Hamachi, Akifumi; Imasaka, Tomoko; Nakamura, Hiroshi; Li, Adan; Imasaka, Totaro

    2017-05-02

    Nerve agent metabolites, i.e., isopropyl methylphosphonic acid (IMPA) and pinacolyl methylphosphonic acid (PMPA), were derivatized by reacting them with 2,3,4,5,6-pentafluorobenzyl bromide (PFBBr) and were determined by mass spectrometry using an ultraviolet femtosecond laser emitting at 267 and 200 nm as the ionization source. The analytes of the derivatized compounds, i.e., IMPA-PFB and PMPA-PFB, contain a large side-chain, and molecular ions are very weak or absent in electron ionization mass spectrometry. The use of ultraviolet femtosecond laser ionization mass spectrometry, however, resulted in the formation of a molecular ion, even for compounds such as these that contain a highly bulky functional group. The signal intensity was larger at 200 nm due to resonance-enhanced two-photon ionization. In contrast, fragmentation was suppressed at 267 nm (nonresonant two-photon ionization) especially for PMPA-PFB, thus resulting in a lower background signal. This favorable result can be explained by the small excess energy in ionization at 267 nm and by the low-frequency vibrational mode of a bulky trimethylpropyl group in PMPA.

  15. Characterization of non-polar aromatic hydrocarbons in crude oil using atmospheric pressure laser ionization and Fourier transform ion cyclotron resonance mass spectrometry (APLI FT-ICR MS).

    Science.gov (United States)

    Schrader, Wolfgang; Panda, Saroj K; Brockmann, Klaus J; Benter, Thorsten

    2008-07-01

    We report on the successful application of the recently introduced atmospheric pressure laser ionization (APLI) method as a novel tool for the analysis of crude oil and its components. Using Fourier transform ion cyclotron resonance mass spectrometry, unambiguous determination of key compounds in this complex matrix with unprecedented sensitivity is presented.

  16. Combination of electrospray ionization, atmospheric pressure photoionization and laser desorption ionization Fourier transform ion cyclotronic resonance mass spectrometry for the investigation of complex mixtures – Application to the petroleomic analysis of bio-oils

    Energy Technology Data Exchange (ETDEWEB)

    Hertzog, Jasmine [LCP-A2MC, FR 2843 Institut Jean Barriol de Chimie et Physique Moléculaires et Biomoléculaires, FR 3624 Réseau National de Spectrométrie de Masse FT-ICR à très haut champ, Université de Lorraine, ICPM, 1 boulevard Arago, 57078 Metz Cedex 03 (France); Carré, Vincent, E-mail: vincent.carre@univ-lorraine.fr [LCP-A2MC, FR 2843 Institut Jean Barriol de Chimie et Physique Moléculaires et Biomoléculaires, FR 3624 Réseau National de Spectrométrie de Masse FT-ICR à très haut champ, Université de Lorraine, ICPM, 1 boulevard Arago, 57078 Metz Cedex 03 (France); Le Brech, Yann [LRGP, CNRS, Université de Lorraine, ENSIC, 1, Rue Grandville, 54000 Nancy (France); Mackay, Colin Logan [SIRCAMS, School of Chemistry, University of Edinburgh, Edinburgh, EH9 3FJ, Scotland (United Kingdom); Dufour, Anthony [LRGP, CNRS, Université de Lorraine, ENSIC, 1, Rue Grandville, 54000 Nancy (France); Mašek, Ondřej [UK Biochar Research Center, School of Geosciences, University of Edinburgh, Kings Buildings, Edinburgh, EH9 3JN (United Kingdom); and others

    2017-05-29

    The comprehensive description of complex mixtures such as bio-oils is required to understand and improve the different processes involved during biological, environmental or industrial operation. In this context, we have to consider how different ionization sources can improve a non-targeted approach. Thus, the Fourier transform ion cyclotron resonance mass spectrometry (FT-ICR MS) has been coupled to electrospray ionization (ESI), laser desorption ionization (LDI) and atmospheric pressure photoionization (APPI) to characterize an oak pyrolysis bio-oil. Close to 90% of the all 4500 compound formulae has been attributed to C{sub x}H{sub y}O{sub z} with similar oxygen class compound distribution. Nevertheless, their relative abundance in respect with their double bound equivalent (DBE) value has evidenced significant differences depending on the ion source used. ESI has allowed compounds with low DBE but more oxygen atoms to be ionized. APPI has demonstrated the efficient ionization of less polar compounds (high DBE values and less oxygen atoms). The LDI behavior of bio-oils has been considered intermediate in terms of DBE and oxygen amounts but it has also been demonstrated that a significant part of the features are specifically detected by this ionization method. Thus, the complementarity of three different ionization sources has been successfully demonstrated for the exhaustive characterization by petroleomic approach of a complex mixture. - Highlights: • Non-targeted mass spectrometry by combining electrospray ionization, atmospheric pressure photoionization and laser/desorption ionization. • Exhaustive description of pyrolytic bio-oil components. • Distinction of sugaric derivatives, lignin derivatives and lipids contained in a woody-based pyrolytic bio-oil.

  17. Trace analysis of actinides in the environment using resonance ionization mass spectrometry; Spurenanalyse von Aktiniden in der Umwelt mittels Resonanzionisations-Massenspektrometrie

    Energy Technology Data Exchange (ETDEWEB)

    Raeder, Sebastian

    2011-04-12

    In this work the resonant ionization of neutral atoms using laser radiation was applied and optimized for ultra-trace analysis of the actinides thorium, uranium, neptunium and plutonium. The sensitive detection of these actinides is a challange for the monitoring and quantification of radioactive releases from nuclear facilities. Using resonance ionization spectroscopy combined with a newly developed quadrupole-mass-spectrometer, numerous energy levels in the atomic structure of these actinides could be identified. With this knowledge efficient excitation schemes for the mentioned actinides could be identified and characterised. The applied in-source-ionization ensures for a high detection efficiency due to the good overlap of laser radiation with the atomic beam and allows therefore for a low sample consumption which is required for the analysis of radio nuclides. The selective excitation processes in the resonant ionization method supresses unwanted contaminations and was optimized for analytical detection of ultra-trace amounts in environmental samples as well as for determination of isotopic compositions. The efficient in-source-ionization combined with high power pulsed laser radiation allows for detections efficiency up to 1%. For plutonium detection limits in the range of 10{sup 4}-10{sup 5} atoms could be demonstrated for synthetic samples as well as for first environmental samples. The usage of narrow bandwidth continuous wave lasers in combination with a transversal overlap of the laser radiation and the free propagating atomic beam enable for resolving individual isotopic shifts of the resonant transitions. This results in a high selectivity against dominant neighboring isotopes but with a significant loss in detection efficiency. For the ultra-trace isotope {sup 236}U a detection limit down to 10{sup -9} for the isotope ratio N ({sup 236}U)/N ({sup 238}U) could be determined.

  18. Chemical analysis of surfaces by resonance ionization mass spectroscopy associated to ionic pulverization

    International Nuclear Information System (INIS)

    Kern, P.

    1995-01-01

    This work shows that if resonance ionization mass spectroscopy was first applied in isotopic separation, it's also an analyzing method adapted to the study of semi-conductor materials and thin foils. We have improved this technic: a neodymium laser coupled with a dye laser, a new argon ions gun, a gallium ions gun and a new collection optic for the secondary ions quadrupole spectrometer to allow quantitative and selective measurements. (S.G.). 84 refs

  19. Development of sodium leak detection technology using laser resonance ionization mass spectrometry. Design and functional test using prototype sodium detection system

    International Nuclear Information System (INIS)

    Aoyama, Takafumi; Ito, Chikara; Harano, Hideki; Okazaki, Koki; Watanabe, Kenichi; Iguchi, Tetsuo

    2009-01-01

    In a sodium-cooled fast reactor, highly sensitive technology is required to detect small amounts of sodium leaking from the cooling system piping or components. The conventional sodium leak detectors have a fundamental difficulty in improving the detection sensitivity for a sodium leak because of the presence of salinity ( 23 NaCl) in the atmosphere around the components and piping of cooling systems. In order to overcome this problem, an innovative technology has been developed to selectively detect the radioactive sodium ( 22 Na) produced by a neutron reaction in the primary cooling system using Laser Resonance Ionization Mass Spectrometry (RIMS). In this method, sodium ions produced with the two processes of (1) atomization of sodium aerosols and (2) resonance ionization of sodium atom, are detected selectively using a time-of-flight mass spectrometer. The 22 Na can be distinguished from the stable isotope ( 23 Na) by mass spectrometry, which is the advantage of RIMS comparing to the other methods. The design and the construction of the prototype system based on fundamental experiments are shown in the paper. The aerodynamic lens was newly introduced, which can transfer aerosols at atmospheric pressure into a vacuum chamber while increasing the aerosol density at the same time. Furthermore, the ionization process was applied by using the external electric field after resonance exciting from the ground level to the Rydberg level in order to increase the ionization efficiency. The preliminary test results using the stable isotope ( 23 Na) showed that prototype system could easily detect sodium aerosol of 100 ppb, equivalent to the sensitivity of the conventional detectors. (author)

  20. The Application of Resonance-Enhanced Multiphoton Ionization Technique in Gas Chromatography Mass Spectrometry

    Directory of Open Access Journals (Sweden)

    Adan Li

    2014-01-01

    Full Text Available Gas chromatography resonance-enhanced multiphoton ionization time-of-flight mass spectrometry (GC/REMPI-TOFMS using a nanosecond laser has been applied to analyze the 16 polycyclic aromatic hydrocarbons (PAHs. The excited-state lifetime, absorption characters, and energy of electronic states of the 16 PAHs were investigated to optimize the ionization yield. A river water sample pretreated by means of solid phase extraction was analyzed to evaluate the performance of the analytical instrument. The results suggested that REMPI is superior to electron impact ionization method for soft ionization and suppresses the background signal due to aliphatic hydrocarbons. Thus, GC/REMPI-TOFMS is a more reliable method for the determination of PAHs present in the environment.

  1. Possible ionization ''ignition'' in laser-driven clusters

    International Nuclear Information System (INIS)

    Rose-Petruck, C.; Schafer, K.J.; Barty, C.P.J.

    1995-01-01

    The authors use Classical Trajectory Monte Carlo (CTMC) simulations to study the ionization of small rare gas clusters in short pulse, high intensity laser fields. They calculate, for a cluster of 25 neon atoms, the ionization stage reached and the average kinetic energy of the ionized electrons as functions of time and peak laser intensity. The CTMC calculations mimic the results of the much simpler barrier suppression model in the limit of isolated atoms. At solid density the results give much more ionization in the cluster than that predicted by the barrier suppression model. They find that when the laser intensity reaches a threshold value such that on average one electron is ionized from each atom, the cluster atoms rapidly move to higher ionization stages, approaching Ne +8 in a few femtoseconds. This ignition process creates an ultrafast pulse of energetic electrons in the cluster at quite modest laser intensities

  2. Gas ionization by focused laser beams

    International Nuclear Information System (INIS)

    Brito, A.L. de.

    1984-01-01

    It is shown that the effect of line broadening by focusing may considerably contribute to the observed laser-induced ionization of gases when the ionization energy of the gas molecules is well above the mean photon energy of the laser radiation. (Author) [pt

  3. Resonance ionization mass spectrometry system for measurement of environmental samples

    International Nuclear Information System (INIS)

    Pibida, L.; McMahon, C.A.; Noertershaeuser, W.; Bushaw, B.A.

    2002-01-01

    A resonance ionization mass spectrometry (RIMS) system has been developed at the National Institute of Standards and Technology (NIST) for sensitive and selective determination of radio-cesium in the environment. The overall efficiency was determined to be 4x10-7 with a combined (laser and mass spectrometer) selectivity of 108 for both 135Cs and 137Cs with respect to 133Cs. RIMS isotopic ratio measurements of 135Cs/ 137Cs were performed on a nuclear fuel burn-up sample and compared to measurements on a similar system at Pacific Northwest National Laboratory (PNNL) and to conventional thermal ionization mass spectrometry (TIMS). Results of preliminary RIMS investigations on a freshwater lake sediment sample are also discussed

  4. Structural characterization of phospholipids by matrix-assisted laser desorption/ionization Fourier transform ion cyclotron resonance mass spectrometry.

    Science.gov (United States)

    Marto, J A; White, F M; Seldomridge, S; Marshall, A G

    1995-11-01

    Matrix-assisted laser desorption/ionization (MALDI) Fourier transform ion cyclotron resonance mass spectrometry provides for structural analysis of the principal biological phospholipids: glycerophosphatidylcholine, -ethanolamine, -serine, and -inositol. Both positive and negative molecular or quasimolecular ions are generated in high abundance. Isolated molecular ions may be collisionally activated in the source side of a dual trap mass analyzer, yielding fragments serving to identify the polar head group (positive ion mode) and fatty acid side chains (negative ion mode). Azimuthal quadrupolar excitation following collisionally activated dissociation refocuses productions close to the solenoid axis; subsequent transfer of product ions to the analyzer ion trap allows for high-resolution mass analysis. Cyro-cooling of the sample probe with liquid nitrogen greatly reduces matrix adduction encountered in the negative ion mode.

  5. Development of High Resolution Resonance Ionization Mass Spectrometry for Neutron Dosimetry Technique with93Nb(n,n'93mNb Reaction

    Directory of Open Access Journals (Sweden)

    Tomita Hideki

    2016-01-01

    Full Text Available We have proposed an advanced technique to measure the 93mNb yield precisely by Resonance Ionization Mass Spectrometry, instead of conventional characteristic X-ray spectroscopy. 93mNb-selective resonance ionization is achievable by distinguishing the hyperfine splitting of the atomic energy levels between 93Nb and 93mNb at high resolution. In advance of 93mNb detection, we could successfully demonstrate high resolution resonant ionization spectroscopy of stable 93Nb using an all solid-state, narrow-band and tunable Ti:Sapphire laser system operated at 1 kHz repetition rate.

  6. Tunnel ionization of H2 in a low-frequency laser field: A wave-packet approach

    International Nuclear Information System (INIS)

    Nguyen-Dang, T.; Chateauneuf, F.; Manoli, S.; Atabek, O.; Keller, A.

    1997-01-01

    The dynamics of multielectron dissociative ionization (MEDI) of H 2 in an intense IR laser pulse are investigated using a wave-packet propagation scheme. The electron tunneling processes corresponding to the successive ionizations of H 2 are expressed in terms of field-free Born-Oppenheimer (BO) potential energy surfaces (PES) by transforming the tunnel shape resonance picture into a Feshbach resonance problem. This transformation is achieved by defining a new, time-dependent electronic basis in which the bound electrons are still described by field-free BO electronic states while the ionized ones are described by Airy functions. In the adiabatic, quasistatic approximation, these functions describe free electrons under the influence of the instantaneous electric field of the laser and such an ionized electron can have a negative total energy. As a consequence, when dressed by the continuous ejected electron energy, the BO PES of an ionic channel can be brought into resonance with states of the parent species. This construction gives a picture in which wave packets are to be propagated on a continuum of coupled electronic manifolds. A reduction of the wave-packet propagation scheme to an effective five-channel problem has been obtained for the description of the first dissociative ionization process in H 2 by using Fano's formalism [U. Fano, Phys. Rev. 124, 1866 (1961)] to analytically diagonalize the infinite, continuous interaction potential matrix and by using the properties of Fano's solutions. With this algorithm, the effect that continuous ionization of H 2 has on the dissociation dynamics of the H 2 + ion has been investigated. In comparison with results that would be obtained if the first ionization of H 2 was impulsive, the wave-packet dynamics of the H 2 + ion prepared continuously by tunnel ionization are markedly nonadiabatic. (Abstract Truncated)

  7. Atomic population redistribution in a dense Ga vapour proceeding via energy pooling ionization induced by resonant laser-assisted collisions

    International Nuclear Information System (INIS)

    Barsanti, S; Bicchi, P

    2002-01-01

    In this paper we report on the atomic population redistribution originating from the ionization that takes place in a dense Ga vapour kept in quartz cells and resonantly excited by laser radiation, in the collisions between two excited atoms. This ionization process is known as energy-pooling ionization (EPI). The electron/ion recombination that takes place in the low density plasma produced gives rise to population in the atomic Rydberg levels and from the latter via cascade transitions to lower lying ones. We have monitored the fluorescences relative to the radiative emissions from such levels, namely those corresponding to the nP → 5S 1/2 series, with 9 ≤ n ≤ 26, and the 4D → 4P 1/2,3/2 transitions. Their characteristics testify to their origin as being due to the EPI process. Further confirmation is obtained by performing a time-resolved analysis of such fluorescences, whose appearance and time evolution is strongly influenced by the dynamics of the process. The effect of the introduction of a few Torr of buffer gas inside the quartz cell, resulting in the quenching of all the fluorescences for n ≥ 12, is also discussed

  8. Resonance ionization spectroscopy in dysprosium

    Energy Technology Data Exchange (ETDEWEB)

    Studer, D., E-mail: dstuder@uni-mainz.de; Dyrauf, P.; Naubereit, P.; Heinke, R.; Wendt, K. [Johannes Gutenberg-Universität Mainz, Institut für Physik (Germany)

    2017-11-15

    We report on resonance ionization spectroscopy (RIS) of high-lying energy levels in dysprosium. We developed efficient excitation schemes and re-determined the first ionization potential (IP) via analysis of Rydberg convergences. For this purpose both two- and three-step excitation ladders were investigated. An overall ionization efficiency of 25(4) % could be demonstrated in the RISIKO mass separator of Mainz University, using a three-step resonance ionization scheme. Moreover, an extensive analysis of the even-parity 6sns- and 6snd-Rydberg-series convergences, measured via two-step excitation was performed. To account for strong perturbations in the observed s-series, the approach of multichannel quantum defect theory (MQDT) was applied. Considering all individual series limits we extracted an IP-value of 47901.76(5) cm{sup −1}, which agrees with the current literature value of 47901.7(6) cm{sup −1}, but is one order of magnitude more precise.

  9. Focusing effects of a laser beam in the non resonant MPI of gases

    International Nuclear Information System (INIS)

    Baravian, G.; Sultan, G.

    1984-09-01

    The authors give a method to interpret correctly the multiphoton ionization in the case of no resonance and saturation. The calculation model is applied to hydrogen to calculate the ion production related to the intensity of laser pulse. Different applications and methods are given. The six-photon ionization cross-section of the krypton is calculated [fr

  10. Injection-controlled laser resonator

    Science.gov (United States)

    Chang, J.J.

    1995-07-18

    A new injection-controlled laser resonator incorporates self-filtering and self-imaging characteristics with an efficient injection scheme. A low-divergence laser signal is injected into the resonator, which enables the injection signal to be converted to the desired resonator modes before the main laser pulse starts. This injection technique and resonator design enable the laser cavity to improve the quality of the injection signal through self-filtering before the main laser pulse starts. The self-imaging property of the present resonator reduces the cavity induced diffraction effects and, in turn, improves the laser beam quality. 5 figs.

  11. Inorganic trace analysis by laser ionization mass spectrometry

    International Nuclear Information System (INIS)

    Becker, S.; Dietze, H.J.

    1991-01-01

    Among the different spectrometric techniques for trace analysis Laser Ionization Mass Spectrometry (LIMS) is well established as a trace analytic method with a wide coverage. In the LIMS the sample material is evaporated and ionized by means of a focused pulsed laser beam in a laser microplasma, which is formed in the spot area of the irradiated sample. All chemical elements in the sample materials are evaporated and ionized in the laser plasma. The formed ions are separated according to mass and energy by a time-of-flight, quadrupole or double focusing mass spectrometer. In this review the characteristics and analytical features, some recent developments, and applications of laser ionization mass spectrometry in inorganic trace analysis are described. (orig.)

  12. Laser ionization mass spectrometry in inorganic trace analysis

    International Nuclear Information System (INIS)

    Becker, J.S.; Dietze, H.J.

    1992-01-01

    Among the different spectrometric techniques for trace analysis Laser Ionization Mass Spectrometry (LIMS) is well established as a trace analytical method. With the LIMS technique the sample material is evaporated and ionized by means of a focused pulsed laser in a laser microplasma, which is formed in the spot area of the irradiated sample. All chemical elements in the sample materials are evaporated and ionized in the laser plasma. The ions formed are separated according to their mass and energy by a time-of-flight, quadrupole or double focusing mass spectrometer. In this review the characteristics and analytical features, some recent developments and applications of laser ionization mass spectrometry in inorganic trace analysis are described. (orig.)

  13. Resonance ionization spectroscopy using ultraviolet laser

    CERN Document Server

    Han, J M; Ko, D K; Park, H M; Rhee, Y J

    2002-01-01

    In this study, Ti:sapphire laser which is pumped by the enhanced Nd:YAG laser using laser diode, was designed and manufactured. The AO Q-switched CW Nd:YAG laser was converted into a high repetition plus-type laser using the AO Q-switch, and two heads were installed inside the cavity in order to improve the laser beam quality. The Nd:YAG laser enhancement was completed by optimization using a simulation for the cavity length, structure and thermal lens effect that greatly effected the laser beam output and quality. As the result of the enhancement, a 30W laser at 532nm and at 5k-Hz was successfully made. Also, the Ti:sapphire laser that will be used for atomic spectroscopy which is pumped by the Nd:YAG laser, was completely designed. As a basic experiment for laser oscillation. We measured the tunability of the laser, and it turned out that the wave tunability range was 730 850 nm. A self-seeding type tunable laser using grating for narrow line width, is planned to be designed due to the fact that the Ti:sapp...

  14. Epicyclic helical channels for parametric resonance ionization cooling

    Energy Technology Data Exchange (ETDEWEB)

    Johson, Rolland Paul [Thomas Jefferson National Accelerator Facility (TJNAF), Newport News, VA (United States); Derbenev, Yaroslav [Muons, Inc., Batavia, IL (United States)

    2015-08-23

    Proposed next-generation muon colliders will require major technical advances to achieve rapid muon beam cooling requirements. Parametric-resonance Ionization Cooling (PIC) is proposed as the final 6D cooling stage of a high-luminosity muon collider. In PIC, a half-integer parametric resonance causes strong focusing of a muon beam at appropriately placed energy absorbers while ionization cooling limits the beam’s angular spread. Combining muon ionization cooling with parametric resonant dynamics in this way should then allow much smaller final transverse muon beam sizes than conventional ionization cooling alone. One of the PIC challenges is compensation of beam aberrations over a sufficiently wide parameter range while maintaining the dynamical stability with correlated behavior of the horizontal and vertical betatron motion and dispersion. We explore use of a coupling resonance to reduce the dimensionality of the problem and to shift the dynamics away from non-linear resonances. PIC simulations are presented.

  15. Theory of the effect of odd-photon destructive interference on optical shifts in resonantly enhanced multiphoton excitation and ionization

    International Nuclear Information System (INIS)

    Payne, M.G.; Deng, L.; Garrett, W.R.

    1998-01-01

    We present a theory for two- and three-photon excitation, optical shifting, and four-wave mixing when a first laser is tuned onto, or near, a two-photon resonance and a second much more intense laser is tuned near or on resonance between the two-photon resonance and a second excited state. When the second excited state has a dipole-allowed transition back to the ground state and the concentration is sufficiently high, a destructive interference is produced between three-photon coupling of the ground state and the second excited state and one-photon coupling between the same states by the internally generated four-wave mixing field. This interference leads to several striking effects. For instance, as the onset of the interference occurs, the optical shifts in the two-photon resonance excitation line shape become smaller in copropagating geometry so that the line shapes for multiphoton ionization enhanced by the two-photon resonance eventually become unaffected by the second laser. In the same range of concentrations the four-wave mixing field evolves to a concentration-independent intensity. With counterpropagating laser beams the line shape exhibits normal optical shifts like those observed for both copropagating and counterpropagating laser beams at very low concentrations. The theoretical work presented here extends our earlier works by including the effect of laser bandwidth and by removing the restriction of having the second laser be tuned far from three-photon resonance. In this way we have now included, as a special case, the effect of both laser bandwidth and interference on laser-induced transparency. Unlike other effects related to odd-photon destructive interference, the effect of a broad bandwidth is to bring about the predicted effects at much lower concentrations. Studies in rubidium show good agreement between theory and experiment for both ionization line shapes and four-wave mixing intensity as a function of concentration. copyright 1998 The

  16. Doubly resonant multiphoton ionization

    International Nuclear Information System (INIS)

    Crance, M.

    1978-01-01

    A particular case of doubly resonant multiphoton ionization is theoretically investigated. More precisely, two levels quasi-resonant with two successive harmonics of the field frequency are considered. The method used is based on the effective operator formalism first introduced for this problem by Armstrong, Beers and Feneuille. The main result is to show the possibility of observing large interference effects on the width of the resonances. Moreover this treatment allows us to make more precise the connection between effective operator formalism and standard perturbation theory

  17. Design of 1+ Ion Source Coupling First Design of the Resonant Ionization Laser Ion Source For the Multi-Mega Watt Target Station

    CERN Document Server

    A. Olivier-Kaiser, F. Le Blanc, C. Lau

    The realisation of next-generation ion sources suitable for the EURISOL multi-mega-watt (MMW) target station needs exhaustive studies and developments. An exhaustive review was carried out to evaluate the capability of the ion-sources to operate under the irradiation conditions of the MMW target station. In addition, selectivity must be taken into account to avoid the spread of unwanted radioactivity out of the target-ion-source system (TIS).These studies led to consider RILIS (Resonance Ionization Laser Ion Source) as the reference ion source for this target station.

  18. Study of the ionization of H+2 ions in strong laser fields

    International Nuclear Information System (INIS)

    Odenweller, Matthias

    2010-01-01

    In the framework of this thesis it has been succeeded to develop a worldwide unique measurement apparatur, by which hydrogen-molecule ions can be ionized by means of short laser pulses and the reaction product kinematically completely measured. For this a detection method following the Coltrims technique, in which both protons and electrons can be detected over the complete spatial angle. The H + 2 ions origin from a high-frequency ion source and are accelerated to 400 keV. This ion beam is overlapped with a 780-nm laser pulse othe pulse length 40 fs. After the reaction the molecule ions fragments either via the dissociation channel H + 2 +nhν→H+H + or via an ionization followed by a Coulomb explosion: H + 2 +nhν→H + +H + +e - . The projectiles are detected after a drift path of about 3 m on an ion detector. For the detection of the electrons a special spectrometer was concipated. In the reaction it comes by the comparatively long pulse length already at low intensities to dissociation processes. The dissociating molecule reaches still during the increasing side of the laser pulse in this way distances, in which the charge-resonance-enhanced-ionization (CREI) can take place. Also the angular distribution of the measured protons lying in a very small angular range around the polarization direction of the laser suggests that CREI is the dominant ionization process. At circular polarization however a netto-acceleration of the electrons perpendicularly to the direction of the electric field at the ionization time takes place, so that the measurement of the electron momenta represents a suited measurement quantity for the study of the ionization process. By this way angular distributions of the electrons relatively to the internuclear axis within the polarization plane could be measured.

  19. Determination of the absolute two-photon ionization cross section of He by an XUV free electron laser

    International Nuclear Information System (INIS)

    Sato, Takahiro; Iwasaki, Atsushi; Ishibashi, Kazuki; Okino, Tomoya; Yamanouchi, Kaoru; Adachi, Junichi; Yagishita, Akira; Yazawa, Hiroki; Aoyma, Makoto; Yabashi, Makina; Nagasono, Mitsuru; Higashiya, Atsushi; Ishikawa, Tetsuya; Kannari, Fumihiko; Yamakawa, Koichi; Midorikawa, Katsumi; Nakano, Hidetoshi

    2011-01-01

    The resonant and non-resonant two-photon single ionization processes of He were investigated using intense free electron laser light in the extreme ultraviolet (XUV) region (53.4-61.4 nm) covering the 1s-2p and 1s-3p resonant transitions of He. On the basis of the dependences of the yield of He + on the XUV light-field intensity at 53.4, 58.4, 56.0 and 61.4 nm, the absolute values of the two-photon ionization cross sections of He at the four different wavelengths and their dependence on the light-field intensity were determined for the first time. (fast track communication)

  20. Comparing Laser Desorption Ionization and Atmospheric Pressure Photoionization Coupled to Fourier Transform Ion Cyclotron Resonance Mass Spectrometry To Characterize Shale Oils at the Molecular Level

    Science.gov (United States)

    Cho, Yunjo; Jin, Jang Mi; Witt, Matthias; Birdwell, Justin E.; Na, Jeong-Geol; Roh, Nam-Sun; Kim, Sunghwan

    2013-01-01

    Laser desorption ionization (LDI) coupled to Fourier transform ion cyclotron resonance mass spectrometry (FT-ICR MS) was used to analyze shale oils. Previous work showed that LDI is a sensitive ionization technique for assessing aromatic nitrogen compounds, and oils generated from Green River Formation oil shales are well-documented as being rich in nitrogen. The data presented here demonstrate that LDI is effective in ionizing high-double-bond-equivalent (DBE) compounds and, therefore, is a suitable method for characterizing compounds with condensed structures. Additionally, LDI generates radical cations and protonated ions concurrently, the distribution of which depends upon the molecular structures and elemental compositions, and the basicity of compounds is closely related to the generation of protonated ions. This study demonstrates that LDI FT-ICR MS is an effective ionization technique for use in the study of shale oils at the molecular level. To the best of our knowledge, this is the first time that LDI FT-ICR MS has been applied to shale oils.

  1. RILIS-ionized mercury and tellurium beams at ISOLDE CERN

    Energy Technology Data Exchange (ETDEWEB)

    Day Goodacre, T., E-mail: thomas.day.goodacre@cern.ch [CERN (Switzerland); Billowes, J. [The University of Manchester, School of Physics and Astronomy (United Kingdom); Chrysalidis, K. [CERN (Switzerland); Fedorov, D. V. [Petersburg Nuclear Physics Institute (Russian Federation); Fedosseev, V. N.; Marsh, B. A. [CERN (Switzerland); Molkanov, P. L. [Petersburg Nuclear Physics Institute (Russian Federation); Rossel, R. E.; Rothe, S.; Seiffert, C. [CERN (Switzerland); Wendt, K. D. A. [Johannes Gutenberg Universität, Institut für Physik (Germany)

    2017-11-15

    This paper presents the results of ionization scheme development for application at the ISOLDE Resonance Ionization Laser Ion Source (RILIS). Two new ionization schemes for mercury are presented: a three-step three-resonance ionization scheme, ionizing via an excitation to a Rydberg level and a three-step two-resonance ionization scheme, with a non-resonant final step to the ionization continuum that corresponded to a factor of four higher ionization efficiency. The efficiency of the optimal mercury ionization scheme was measured, together with the efficiency of a new three-step three resonance ionization scheme for tellurium. The efficiencies of the mercury and tellurium ionization schemes were determined to be 6 % and >18 % respectively.

  2. Ionization of a multilevel atom by ultrashort laser pulses

    International Nuclear Information System (INIS)

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

    2010-01-01

    Specific features of ionization of single atoms by laser fields of a near-atomic strength are investigated. Calculations are performed for silver atoms interacting with femtosecond laser pulses with wavelengths λ = 800 nm (Ti:Sapphire) and λ = 1.064 μm (Nd:YAG). The dependences of the probability of ionization and of the form of the photoelectron energy spectra on the field of laser pulses for various values of their duration are considered. It is shown that the behavior of the probability of ionization in the range of subatomic laser pulse fields is in good agreement with the Keldysh formula. However, when the field strength attains values close to the atomic field strength, the discrepancies in these dependences manifested in a decrease in the ionization rate (ionization stabilization effect) or in its increase (accelerated ionization) are observed. These discrepancies are associated with the dependence of the population dynamics of excited discrete energy levels of the atom on the laser pulse field amplitude.

  3. Stark-shift induced resonances in multiphoton ionization

    International Nuclear Information System (INIS)

    Potvliege, R M; Vuci, Svetlana

    2006-01-01

    The resonance enhancements marking the ATI spectrum of argon are discussed in the light of a recently compiled map of the quasienergies of this atom. Many of the dressed excited states of interest shift nonponderomotively in complicated ways, but keep an ionization width narrow enough to produce sharp substructures of both low and high ATI peaks through Stark-shift induced resonances. The most prominent enhancement observed in the high-order ATI peaks originates from ionization from the dressed ground state perturbed by the influence of neighbouring resonant dressed states

  4. Non-Liouvillean ion injection via resonantly enhanced two-photon ionization

    Directory of Open Access Journals (Sweden)

    B. A. Knyazev

    2004-03-01

    Full Text Available The charge-exchange method is now one of the main techniques for ion injection into accelerators and storage rings. The disadvantages of conventional methods, based on the atom or ion stripping in a material target, are emittance growth, energy straggling, and production of ions in many charge states. Recently suggested stripping methods based on direct photoionization require employment of hard-UV lasers, which still do not exist and must obviously be very bulky and expensive. An alternative method, suggested for injection of proton beams, employs excitation of the atom to 3p intermediate state with subsequent Lorentz ionization in a magnetic field gradient. This technique applies rigid requirements to laser characteristic and is not free of growing of the beam divergence. In this paper a variant of the stripping technique based on the resonantly enhanced two-photon ionization (RETPI is considered. The technique allows ionization of singly charged ions of the elements from helium to bismuth. A variant of the technique can be used for proton injection. RETPI can be applied for both ion injection and stacking, as well as for diagnostics of ion beam characteristics on the orbit. Stripping efficiency can be about 100% for the singly charged ions having the singlet ground state and decreases for the other ions. Special methods for “cleaning” unwanted atomic states in such ions, that can provide high stripping efficiency, are discussed. Excimer lasers with very moderate parameters can be employed for implementation of this technique for almost all elements. Numerical examples show that for most of the singly charged ions and for hydrogen atom necessary laser-beam energy density is merely 0.5–8  J/cm^{2} for a 1 m interaction region, and is 10 times higher for several light ions.

  5. Mass spectrometry of solid samples in open air using combined laser ionization and ambient metastable ionization

    International Nuclear Information System (INIS)

    He, X.N.; Xie, Z.Q.; Gao, Y.; Hu, W.; Guo, L.B.; Jiang, L.; Lu, Y.F.

    2012-01-01

    Mass spectrometry of solid samples in open air was carried out using combined laser ionization and metastable ionization time-of-flight mass spectrometry (LI-MI-TOFMS) in ambient environment for qualitative and semiquantitative (relative analyte information, not absolute information) analysis. Ambient metastable ionization using a direct analysis in realtime (DART) ion source was combined with laser ionization time-of-flight mass spectrometry (LI-TOFMS) to study the effects of combining metastable and laser ionization. A series of metallic samples from the National Institute of Standards and Technology (NIST 494, 495, 498, 499, and 500) and a pure carbon target were characterized using LI-TOFMS in open air. LI-MI-TOFMS was found to be superior to laser-induced breakdown spectroscopy (LIBS). Laser pulse energies between 10 and 200 mJ at the second harmonic (532 nm) of an Nd:YAG laser were applied in the experiment to obtain a high degree of ionization in plasmas. Higher laser pulse energy improves signal intensities of trace elements (such as Fe, Cr, Mn, Ni, Ca, Al, and Ag). Data were analyzed by numerically calculating relative sensitivity coefficients (RSCs) and limit of detections (LODs) from mass spectrometry (MS) and LIBS spectra. Different parameters, such as boiling point, ionization potential, RSC, LOD, and atomic weight, were shown to analyze the ionization and MS detection processes in open air.

  6. Increased ionization rate in laser enrichment

    International Nuclear Information System (INIS)

    Janes, G.S.; Pike, G.T.

    1977-01-01

    A system employing multiple, upper excitation levels in a technique for isotopically selective ionization to improve the ionization efficiency is described. Laser radiation is employed to excite particles with isotopic selectivity. Excitation is produced to a plurality of excited states below the ionization level with the result of increasing the number of available excited particles for ionization and thereby increasing the ionization cross section for improved system efficiency

  7. Wavelength dependent photoelectron circular dichroism of limonene studied by femtosecond multiphoton laser ionization and electron-ion coincidence imaging

    Science.gov (United States)

    Rafiee Fanood, Mohammad M.; Janssen, Maurice H. M.; Powis, Ivan

    2016-09-01

    Enantiomers of the monoterpene limonene have been investigated by (2 + 1) resonance enhanced multiphoton ionization and photoelectron circular dichroism employing tuneable, circularly polarized femtosecond laser pulses. Electron imaging detection provides 3D momentum measurement while electron-ion coincidence detection can be used to mass-tag individual electrons. Additional filtering, by accepting only parent ion tagged electrons, can be then used to provide discrimination against higher energy dissociative ionization mechanisms where more than three photons are absorbed to better delineate the two photon resonant, one photon ionization pathway. The promotion of different vibrational levels and, tentatively, different electronic ion core configurations in the intermediate Rydberg states can be achieved with different laser excitation wavelengths (420 nm, 412 nm, and 392 nm), in turn producing different state distributions in the resulting cations. Strong chiral asymmetries in the lab frame photoelectron angular distributions are quantified, and a comparison made with a single photon (synchrotron radiation) measurement at an equivalent photon energy.

  8. Combination of electrospray ionization, atmospheric pressure photoionization and laser desorption ionization Fourier transform ion cyclotronic resonance mass spectrometry for the investigation of complex mixtures - Application to the petroleomic analysis of bio-oils.

    Science.gov (United States)

    Hertzog, Jasmine; Carré, Vincent; Le Brech, Yann; Mackay, Colin Logan; Dufour, Anthony; Mašek, Ondřej; Aubriet, Frédéric

    2017-05-29

    The comprehensive description of complex mixtures such as bio-oils is required to understand and improve the different processes involved during biological, environmental or industrial operation. In this context, we have to consider how different ionization sources can improve a non-targeted approach. Thus, the Fourier transform ion cyclotron resonance mass spectrometry (FT-ICR MS) has been coupled to electrospray ionization (ESI), laser desorption ionization (LDI) and atmospheric pressure photoionization (APPI) to characterize an oak pyrolysis bio-oil. Close to 90% of the all 4500 compound formulae has been attributed to C x H y O z with similar oxygen class compound distribution. Nevertheless, their relative abundance in respect with their double bound equivalent (DBE) value has evidenced significant differences depending on the ion source used. ESI has allowed compounds with low DBE but more oxygen atoms to be ionized. APPI has demonstrated the efficient ionization of less polar compounds (high DBE values and less oxygen atoms). The LDI behavior of bio-oils has been considered intermediate in terms of DBE and oxygen amounts but it has also been demonstrated that a significant part of the features are specifically detected by this ionization method. Thus, the complementarity of three different ionization sources has been successfully demonstrated for the exhaustive characterization by petroleomic approach of a complex mixture. Copyright © 2017 Elsevier B.V. All rights reserved.

  9. An intense polarized beam by a laser ionization injection

    International Nuclear Information System (INIS)

    Ohmori, Chihiro; Hiramatsu, Shigenori; Nakamura, Takeshi.

    1990-12-01

    Accumulation of protons and polarized protons by photo-ionization injection are described. This method consists of (1)producing the neutral hydrogen beam by Lorentz stripping, (2)excitation of the neutral hydrogen beam with a laser, and (3)ionization of the hydrogen beam in the 2P excited state with another laser. When the laser for the excitation is circularly polarized, we can get a polarized proton beam. An ionization efficiency of 98% and a polarization of 80% can be expected by an intense laser beam from a FEL(Free Electron Laser). (author)

  10. Trace isotope analysis using resonance ionization mass spectrometry based on isotope selection with doppler shift of laser ablated atoms

    International Nuclear Information System (INIS)

    Higuchi, Yuki; Watanabe, Kenichi; Kawarabayashi, Jun; Iguchi, Tetsuo

    2005-01-01

    We have proposed a novel isotope selective Resonance Ionization Mass Spectroscopy (RIMS) concept, which can avoid the Doppler broadening on solid sample direct measurement based on laser ablation technique. We have succeeded in experimentally demonstrating the principle of our RIMS concept. Through comparison between the simulated and experimental results, we have validated the simulation model. It would be concluded from these results that we could achieve the isotope selectivity defined as the ratio of 41 Ca to 40 Ca sensitivity to be 4.5x10 10 by adopting the multi-step excitation scheme in the present method. As future works, we will try to experimentally perform the multi-step excitation scheme and improve the detection efficiency by modifying the ion extraction configuration. (author)

  11. Trace analysis of plutonium in environmental samples by resonance ionization mass spectroscopy (RIMS)

    International Nuclear Information System (INIS)

    Erdmann, N.; Herrmann, G.; Huber, G.; Koehler, S.; Kratz, J.V.; Mansel, A.; Nunnemann, M.; Passler, G.; Trautmann, N.; Waldek, A.

    1997-01-01

    Trace amounts of plutonium in the environment can be detected by resonance ionization mass spectroscopy (RIMS). An atomic beam of plutonium is produced after its chemical separation and deposition on a filament. The atoms are ionized by a three-step excitation using pulsed dye-lasers. The ions are mass-selectively detected in a time-of-flight (TOF) mass spectrometer. With this setup a detection limit of 1·10 6 atoms of plutonium has been achieved. Furthermore, the isotopic composition can be determined. Different samples, including soil from the Chernobyl area, IAEA-certified sediments from the Mururoa Atoll and urine, have been investigated. copyright 1997 American Institute of Physics

  12. Multiphoton ionization of (Xe)/sub n/ and (NO)/sub n/ clusters using a picosecond laser

    International Nuclear Information System (INIS)

    Smith, D.B.; Miller, J.C.

    1989-01-01

    In an effort to extend the application of multiphoton ionization (MPI) spectroscopy to the study of weakly bound systems, we have begun a systematic investigation of picosecond MPI in van der Waals molecules and clusters. To our knowledge no previous picosecond MPI studies of weakly bound systems have been reported. We present here results of picosecond MPI of Xe/sub n/(n = 1-20) and (NO)/sub n/(n = 1-4) clusters. Previous MPI studies using nanosecond lasers have not detected the NO cluster series, presumably because of fast dissociation channels. The use of high peak-power allows resonant and non-resonant photon absorption to the ionization limit to compete effectively with fast dissociative processes. 10 refs., 2 figs

  13. Ionization of EPA contaminants in direct and dopant-assisted atmospheric pressure photoionization and atmospheric pressure laser ionization.

    Science.gov (United States)

    Kauppila, Tiina J; Kersten, Hendrik; Benter, Thorsten

    2015-06-01

    Seventy-seven EPA priority environmental pollutants were analyzed using gas chromatography-mass spectrometry (GC-MS) equipped with an optimized atmospheric pressure photoionization (APPI) and an atmospheric pressure laser ionization (APLI) interface with and without dopants. The analyzed compounds included e.g., polycyclic aromatic hydrocarbons (PAHs), nitro compounds, halogenated compounds, aromatic compounds with phenolic, acidic, alcohol, and amino groups, phthalate and adipatic esters, and aliphatic ethers. Toluene, anisole, chlorobenzene, and acetone were tested as dopants. The widest range of analytes was ionized using direct APPI (66/77 compounds). The introduction of dopants decreased the amount of compounds ionized in APPI (e.g., 54/77 with toluene), but in many cases the ionization efficiency increased. While in direct APPI the formation of molecular ions via photoionization was the main ionization reaction, dopant-assisted (DA) APPI promoted ionization reactions, such as charge exchange and proton transfer. Direct APLI ionized a much smaller amount of compounds than APPI (41/77 compounds), showing selectivity towards compounds with low ionization energies (IEs) and long-lived resonantly excited intermediate states. DA-APLI, however, was able to ionize a higher amount of compounds (e.g. 51/77 with toluene), as the ionization took place entirely through dopant-assisted ion/molecule reactions similar to those in DA-APPI. Best ionization efficiency in APPI and APLI (both direct and DA) was obtained for PAHs and aromatics with O- and N-functionalities, whereas nitro compounds and aliphatic ethers were the most difficult to ionize. Halogenated aromatics and esters were (mainly) ionized in APPI, but not in APLI.

  14. Small sample analysis using sputter atomization/resonance ionization mass spectrometry

    International Nuclear Information System (INIS)

    Christie, W.H.; Goeringer, D.E.

    1986-01-01

    We have used secondary ion mass spectrometry (SIMS) to investigate the emission of ions via argon sputtering from U metal, UO 2 , and U 3 O 8 samples. We have also used laser resonance ionization techniques to study argon-sputtered neutral atoms and molecules emitted from these same samples. For the case of U metal, a significant enhancement in detection sensitivity for U is obtained via SA/RIMS. For U in the fully oxidized form (U 3 O 8 ), SA/RIMS offers no improvement in U detection sensitivity over conventional SIMS when sputtering with argon. 9 refs., 1 fig., 2 tabs

  15. Broadband non-selective excitation of plutonium isotopes for isotope ratio measurements in resonance ionization mass spectrometry: a theoretical study.

    Science.gov (United States)

    Sankari, M

    2012-10-15

    Making isotope ratio measurements with minimum isotope bias has always been a challenging task to mass spectrometrists, especially for the specific case of plutonium, owing to the strategic importance of the element. In order to use resonance ionization mass spectrometry (RIMS) as a tool for isotope ratio measurements, optimization of the various laser parameters and other atomic and system parameters is critical to minimize isotopic biases. Broadband simultaneous non-selective excitation of the isotopes of plutonium in the triple resonance excitation scheme with λ(1) = 420.77 nm, λ(2) = 847.28 nm, and λ(3) = 767.53 nm based on density matrix formalism has been theoretically computed for the determination of isotope ratios. The effects of the various laser parameters and other factors such as the atomization temperature and the dimensions of the atomic beam on the estimation of isotope ratios were studied. The effects of Doppler broadening, and time-dependent excitation parameters such as Rabi frequencies, ionization rate and the effect of non-Lorenztian lineshape have all been incorporated. The average laser powers and bandwidths for the three-excitation steps were evaluated for non-selective excitation. The laser intensity required to saturate the three-excitation steps were studied. The two-dimensional lineshape contour and its features were investigated, while the reversal of peak asymmetry of two-step and two-photon excitation peaks under these conditions is discussed. Optimized powers for the non-selective ionization of the three transitions were calculated as 545 mW, 150 mW and 545 mW and the laser bandwidth for all the three steps was ~20 GHz. The isotopic bias between the resonant and off-resonant isotope under the optimized conditions was no more than 9%, which is better than an earlier reported value. These optimized laser power and bandwidth conditions are better than in the earlier experimental work since these comprehensive calculations yield

  16. Exploring Biosignatures Associated with Thenardite by Geomatrix-Assisted Laser Desorption/Ionization Fourier Transform Ion Cyclotron Resonance Mass Spectrometry (GALDI-FTICR-MS)

    Energy Technology Data Exchange (ETDEWEB)

    C. Doc Richardson; Nancy W. Hinman; Timothy R. McJunkin; J. Michelle Kotler; Jill R. Scott

    2008-10-01

    Geomatrix-assisted laser desorption/ionization (GALDI) in conjunction with a Fourier transform ion cyclotron resonance mass spectrometer (FTICR-MS) has been employed to determine how effectively bio/organic molecules associated with the mineral thenardite (Na2SO4) can be detected. GALDI is based on the ability of the mineral host to assist desorption and ionization of bio/organic molecules without additional sample preparation. When glycine was mixed with thenardite, glycine was deprotonated to produce C2H4NO-2 at m/z 74.025. The combination of stearic acid with thenardite produced a complex cluster ion at m/z 390.258 in the negative mode, which was assigned a composition ofC18H39O7Na-. Anatural sample of thenardite from Searles Lake in California also produced a peak at m/z 390.260. The bio/organic signatures in both the laboratory-based and natural samples were heterogeneously dispersed as revealed by chemical imaging. The detection limits for the stearic acid and thenardite combination were estimated to be 3 parts per trillion or~7 zeptomoles (10-21) per laser spot. Attempts to improve the signal-to-noise ratio by co-adding FTICR-MS data predetermined to contain the biosignatures of interest revealed problems due to a lack of phase coherence between data sets.

  17. Modeling of Plutonium Ionization Probabilities for Use in Nuclear Forensic Analysis by Resonance Ionization Mass Spectrometry

    Science.gov (United States)

    2016-12-01

    masses collide, they form a supercritical mass . Criticality refers to the neutron population within the system. A critical system is one that can...Spectrometry, no. 242, pp. 161–168, 2005. [9] S. Raeder, “Trace analysis of actinides in the environment by means of resonance ionization mass ...first ionization potential of actinide elements by resonance ionization mass spectrometry.” Spectrochimica Acta part B: Atomic Spectroscopy. vol. 52

  18. Towards non-sequential double ionization of Ne and Ar using a femtosecond laser oscillator.

    Science.gov (United States)

    Liu, Yunquan; Tschuch, Sebastian; Dürr, Martin; Rudenko, Artem; Moshammer, Robert; Ullrich, Joachim; Siegel, Martin; Morgner, Uwe

    2007-12-24

    We report on first proof-of-principles results on non-sequential double ionization of argon and neon achieved by using a newly developed long-cavity Ti:sapphire femtosecond oscillator with a pulse duration of 45 fs and a repetition of 6.2 MHz combined with a dedicated reaction microscope. Under optimized experimental conditions, peak intensities larger than 2.310(14) W/cm(2) have been achieved. Ion momentum distributions were recorded for both rare gases and show significantly different features for single as well as for double ionization. For single ionization of neon a spike of zero-momentum electrons is found when decreasing the laser intensity towards the lowest ionization rate we can measure which is attributed to a non-resonant ionization channel. As to double ionization, the longitudinal momentum distribution for Ne(2+) displays a clear double-hump structure whereas this feature is found to be smoothened out with a maximum at zero momentum for Ar(2+).

  19. Theory of resonant multiphoton ionization of krypton by intense ultraviolet laser radiation

    International Nuclear Information System (INIS)

    Tang, X.; Lambropoulos, P.; L'Huillier, A.; Dixit, S.N.

    1989-01-01

    We present a theoretical interpretation of the experimental results on three-photon-resonant four-photon ionization of Kr reported by Landen, Perry, and Campbell [Phys. Rev. Lett. 59, 2558 (1987)] and Perry and Landen [Phys. Rev. A 38, 2815 (1988)]. Our calculations are based on multichannel quantum-defect theory combined with a density-matrix formalism describing the spatiotemporal development of the process. We obtain good agreement with the data, which even at intensities as high as 10 14 W/cm 2 show the imprint of the underlying atomic structure

  20. Studies on laser-assisted Penning ionization by the optogalvanic effect in Ne/Eu hollow cathode discharge.

    Science.gov (United States)

    Saini, V K; Kumar, P; Dixit, S K; Nakhe, S V

    2015-02-01

    Laser-assisted Penning ionization (LAPI) is detected in a Ne/Eu hollow cathode (HC) discharge lamp using the pulsed optogalvanic (OG) method. In the Ne/Eu discharge, doubly ionized europium excited energy levels Eu[4f(7)(P(7/2,5/2)6)] lie within the thermal limit (∼kT) from the laser-excited neon's energy level [2p(5)(P3/202)3p or 2p(8) (in Paschen notation)] lying at 149,848  cm(-1). Therefore, Penning ionization (PI) of europium atoms likely to occur into its highly excited ionic states is investigated. To probe the PI of europium, the temporal profiles of its counterpart neon OG signal are studied as a function of discharge current for the transitions (1s(4)→2p(8)) and (1s(2)→2p(2)), corresponding to 650.65 and 659.89 nm wavelengths, respectively. It is observed that PI of europium alters the overall discharge characteristics significantly and, hence, modifies the temporal profile of the OG signals accordingly. The quasi-resonant ionizing energy transfer collisions between laser-excited Ne 2p(8) atoms and electronically excited europium P(9/2)10 atoms are used to explain the LAPI mechanism. Such LAPI studies carried out in HC discharge could be useful for the discharge of a metal-vapor laser with appropriate Penning mixtures.

  1. Multiphoton ionization of (Xe)n and (NO)n clusters using a picosecond laser

    International Nuclear Information System (INIS)

    Smith, D.B.; Miller, J.C.

    1989-01-01

    Mass-resolved multiphoton ionization (MPI) spectroscopy is an established technique for detecting and analyzing van der Waals molecules and larger clusters. MPI spectroscopy provides excellent detection sensitivity, moderately high resolution, and selectivity among cluster species. In addition to information provided by the analysis of photoions following MPI, photoelectron spectroscopy can reveal details regarding the structure of ionic states. Unfortunately, the technique is limited by its tendency to produce extensive fragmentation. Fragmentation is also a problem with other ionization techniques (e.g., electron impact ionization), but the intense laser beams required for MPI cause additional dissociation channels to become available. These channels include absorption of additional photons by parent ions (ion ladder mechanism), absorption of additional photons by fragment ions (ladder switching mechanism), and resonances with dissociative states in the neutral manifold. The existence of these dissociation channels can preclude the use of MPI spectroscopy in many situations. Recently, MPI studies of stable molecules using picosecond lasers (pulse length = 1 - 10 ps) have indicated that limitations due to fragmentation might be subdued. With picosecond lasers, dissociation mechanisms can be altered and in some cases fragmentation can be eliminated or reduced. Additional photon absorption competes effectively with dissociation channels when a very short laser pulse or, perhaps more importantly, a sufficiently high peak-power is used. In the case where ionic absorption and fragmentation occurs, it has been shown that picosecond MPI might favor the ion ladder mechanism rather than the ladder switching mechanism

  2. Use of a 3-MV proton accelerator for study of noble gases, including laser ionization of excited states

    International Nuclear Information System (INIS)

    Hurst, G.S.; Judish, J.P.; Nayfeh, M.H.; Parks, J.E.; Payne, M.G.; Wagner, E.B.

    1974-01-01

    The use of a pulsed 3-MV accelerator to study energy pathways in the noble gases is described. The objectives of pathways research are to obtain (1) information on the spectrum of excited states produced by a charged particle in a noble gas, (2) the rate of decay of the various states through various channels as a function of gas pressure, and (3) the modification of the decay channels due to the introduction of foreign species. A new energy pathways model is presented for helium as a general illustration. A method for the study of excited states, using a laser ionization technique is reported. Use is made of a laser which is tuned to a resonance transition between the desired excited state and some higher excited state. Photons in the same pulse photoionize the higher excited state; thus the ionization current vs photon wavelength has a resonance structure. Absolute yields of selected excited states can be obtained whenever the photon fluence per pulse is large enough to saturate the ionization current. A general summary is given of experimental facilities which include a 3-MV Van de Graaff accelerator, electronics for measuring radiation lifetimes, vacuum ultraviolet spectrometers, and a pulsed laser facility for direct study of excited states. Finally, the relevance of pathways research to (1) the interaction of radiation with matter, (2) the development of gas lasers, and (3) methods of ultrasensitive elemental analysis is pointed out

  3. First observation of the beta decay of neutron-rich $^{218}Bi$ by the pulsed-release technique and resonant laser ionization

    CERN Document Server

    De Witte, H; Borzov, I N; Caurier, E; Cederkäll, J; De Smet, A; Eckhaudt, S; Fedorov, D V; Fedosseev, V; Franchoo, S; Górska, M; Grawe, H; Huber, G; Huyse, M; Janas, Z; Köster, U; Kurcewicz, W; Kurpeta, J; Plochocki, A; Van Duppen, P; Van de Vel, K; Weissman, L

    2004-01-01

    The neutron-rich isotope /sup 218/Bi has been produced in proton- induced spallation of a uranium carbide target at the ISOLDE facility at CERN, extracted from the ion source by the pulsed-release technique and resonant laser ionization, and its beta decay is studied for the first time. A half-life of 33(1)s was measured and is discussed in the self-consistent continuum-quasi particle-random- phase approximation framework that includes Gamow-Teller and first- forbidden transitions. A level scheme was constructed for /sup 218 /Po, and a deexcitation pattern of stretched E2 transitions 8/sup +/ to 6/sup +/ to 4/sup +/ to 2/sup +/ to 0/sup +/ to the ground state is suggested. Shell-model calculations based on the Kuo-Herling interaction reproduce the experimental results satisfactorily. (28 refs).

  4. Ionization processes in combined high-voltage nanosecond - laser discharges in inert gas

    Science.gov (United States)

    Starikovskiy, Andrey; Shneider, Mikhail; PU Team

    2016-09-01

    Remote control of plasmas induced by laser radiation in the atmosphere is one of the challenging issues of free space communication, long-distance energy transmission, remote sensing of the atmosphere, and standoff detection of trace gases and bio-threat species. Sequences of laser pulses, as demonstrated by an extensive earlier work, offer an advantageous tool providing access to the control of air-plasma dynamics and optical interactions. The avalanche ionization induced in a pre-ionized region by infrared laser pulses where investigated. Pre-ionization was created by an ionization wave, initiated by high-voltage nanosecond pulse. Then, behind the front of ionization wave extra avalanche ionization was initiated by the focused infrared laser pulse. The experiment was carried out in argon. It is shown that the gas pre-ionization inhibits the laser spark generation under low pressure conditions.

  5. Electrospray ionization and matrix assisted laser desorption/ionization mass spectrometry: powerful analytical tools in recombinant protein chemistry

    DEFF Research Database (Denmark)

    Andersen, Jens S.; Svensson, B; Roepstorff, P

    1996-01-01

    Electrospray ionization and matrix assisted laser desorption/ionization are effective ionization methods for mass spectrometry of biomolecules. Here we describe the capabilities of these methods for peptide and protein characterization in biotechnology. An integrated analytical strategy is presen......Electrospray ionization and matrix assisted laser desorption/ionization are effective ionization methods for mass spectrometry of biomolecules. Here we describe the capabilities of these methods for peptide and protein characterization in biotechnology. An integrated analytical strategy...... is presented encompassing protein characterization prior to and after cloning of the corresponding gene....

  6. Resonances above the ionization threshold in positron-hydrogen scattering

    International Nuclear Information System (INIS)

    Kernoghan, A.A.; Walters, H.R.J.; McAlinden, M.T.

    1994-01-01

    Resonances appearing above the ionization threshold in coupled-state calculations of positron-atom scattering are discussed. Calculations in the six state approximation Ps(1s, 2s, 2p) + H(1s, 2s, 2p), which show such resonance structure, are compared with a more extensive 18-state approximation Ps(1s, 2s, 3s, 4s, 2p, 3p, 4p, 3d, 4d) + H(1s, 2s, 3s, 4s, 2p, 3p, 4p, 3d, 4d) in which channels other than 1s, 2s and 2p are represented by pseudostates. The results strongly indicate that the above ionization threshold resonances observed in the six-state approximation, and in other small basis set calculations, are not real. It is suggested that they are a consequence of the neglect, or inadequate representation in other approximations, of ionization channels. In the six-state approximation the positronium component of the system wavefunction attempts to represent the missing ionization channels but in so doing produces unreal resonances above the ionization threshold. More generally it is suggested that, in coupled-state calculations of positron-atom scattering, the atom part of the system wavefunction will try to compensate for defects in the positronium component and vice versa. When the defects are serious, for example, the omission of important ionization channels, unusual spurious behaviour is to be expected. (Author)

  7. Development of laser atomic spectroscopic technology

    International Nuclear Information System (INIS)

    Lee, Jong Min; Ohr, Young Gie; Cha, Hyung Ki

    1990-06-01

    Some preliminary results on the resonant ionization spectroscopy for Na and Pb atoms are presents both in theory and in experiment. A single color multiphoton ionization process is theoretically analysed in detail, for the resonant and non-resonant cases, and several parameters determining the overall ionization rate are summarized. In particular, the AC stark shift, the line width and the non-linear coefficient of ionization rate are recalculated using the perturbation theory in resolvent approach. On the other hand, the fundamental equipments for spectroscopic experiments have been designed and manufactured, which include a Nd:YAG laser, a GIM-type dye laser, a vacuum system ionization cells, a heat pipe oven, and an ion current measuring system. The characteristics of the above equipments have also been examined. Using the spectroscopic data available, several ionization schemes are considered and the relative merits for ionization have been discussed. Moreover, the effects due to the buffer gas pressure, laser intensity, vapor density and electrode voltage have been investigated in detail. The experiments will be extended to multi-color processes with several resonances, and the ultimate goal is to develop a ultrasensitive analytical method for pollutive heavy metal atoms using the resonant ionization spectroscopy. (author)

  8. Interpreting tunneling time in circularly polarized strong-laser ionization

    OpenAIRE

    Yuan, MingHu; Xin, PeiPei; Chu, TianShu; Liu, HongPing

    2016-01-01

    We propose a method to study the tunneling process by analyzing the time-dependent ionization yield in circularly polarized laser. A numerical calculation shows that for an atom exposed to a long laser pulse, if its initial electronic state wave function is non-spherical symmetric, the delayed phase shift of the ionization rate vs. the laser cycle period in real time in the region close to the peak intensity of the laser pulse can be used to probe the tunneling time. In this region, an obviou...

  9. Collinear resonant ionization laser spectroscopy of rare francium isotopes

    CERN Multimedia

    Neyens, G; Flanagan, K; Rajabali, M M; Le blanc, F M; Ware, T; Procter, T J

    2008-01-01

    We propose a programme of collinear resonant ionization spectroscopy (CRIS) of the francium isotopes up to and including $^{201}$Fr and $^{218,219}$Fr. This work aims at answering questions on the ordering of quantum states, and effect of the ($\\pi s_{1/2}^{-1}$)1/2$^{+}$ intruder state, which is currently believed to be the ground state of $^{199}$Fr. This work will also study the edge of the region of reflection asymmetry through measurement of the moments and radii of $^{218,219}$Fr. This proposal forms the first part of a series of experiments that will study nuclei in this region of the nuclear chart. Based on the success of this initial proposal it is the intention of the collaboration to perform high resolution measurements on the isotopes of radium and radon that surround $^{201}$Fr and $^{218}$Fr and thus providing a comprehensive description of the ground state properties of this region of the nuclear chart. Recent in-source spectroscopy measurements of lead, bismuth and polonium have demonstrated a...

  10. Multiphoton ionization of H2+ in xuv laser pulses

    International Nuclear Information System (INIS)

    Guan Xiaoxu; Secor, Ethan B.; Bartschat, Klaus; Schneider, Barry I.

    2011-01-01

    We consider the ionization of the hydrogen molecular ion after one-, two-, and three-photon absorption over a large range of photon energies between 9 and 40 eV in the fixed-nuclei approximation. The temporal development of the system is obtained in a fully ab initio time-dependent grid-based approach in prolate spheroidal coordinates. The alignment dependence of the one-photon ionization amplitude is highlighted in the framework of time-dependent perturbation theory. For one-photon ionization as a function of the nuclear separation, the calculations reveal a significant minimum in the ionization probability. The suppressed ionization is attributed to a Cooper-type minimum, which is similar, but not identical, to the cancellation effect observed in photoionization cross sections of some noble-gas atoms. The effect of the nonspherical two-center Coulomb potential is analyzed. For two- and three-photon ionization, the angle-integrated cross sections clearly map out intermediate-state resonances, and the predictions of the current computations agree very well with those from time-independent calculations. The dominant emission modes for two-photon ionization are found to be very similar in both resonance and off-resonance regions.

  11. Features of single and double ionization processes induced by few cycle laser pulses

    International Nuclear Information System (INIS)

    Starace, A.F.

    2005-01-01

    Full text: The advent of laser pulses with attosecond pulse lengths ushers in the regime of few cycle laser pulse interactions with atoms and ions, including the interesting cases of single and half cycle laser pulses. In this talk I will present results of recent studies of single electron ionization/detachment and double electron ionization/detachment produced by a few cycle laser pulse. For the former case, we shall demonstrate that the ionized/detached electron momentum distribution reflects the interference of electron probability wave packets produced by each half cycle of a single cycle pulse. Also, that the ionized/detached electron momentum distribution uniquely characterizes the phase of the single cycle laser pulse within the laser pulse envelope. Regarding double ionization/detachment, our numerical experiments have shown that single cycle and double half cycle pulses produce different electron angular distributions. Some double ionization features that are present only in the single cycle case can only have been produced by electron impact ionization during rescattering of an initially ionized electron and thus represent a sensitive measure of the rescattering process. Refs. 2 (author)

  12. Generation of Multicharged Krypton Ions in Nanosecond Laser Ionization of Krypton Beam%纳秒激光电离产生Kr17+的研究

    Institute of Scientific and Technical Information of China (English)

    罗晓琳; 孔祥蕾; 牛冬梅; 渠洪波; 李海洋

    2004-01-01

    Up to Kr17+ muhicharged krypton ions have been observed in time-of-flight mass spectrum by a 25 ns Nd-YAG 1. 064 μm laser at laser intensity about 1012 W/cm2. Experimental results indicate that the muhicharged ions appear only when the laser interacts with the middle part of the pulsed beam, and the intensities of the multi charged ions increase dramatically by increasing the backing pressure of Kr gas, which indicates that the clusters in the beam is essential to the production of muhicharged ions. From the experimental results, it is concluded that the cluster is ionized via multiphoton ionization and forms a nanoplasma ball, which can absorb the laser resonantly to further ionize the single charge ion to the high charge state.

  13. Laser systems for on-line laser ion sources

    International Nuclear Information System (INIS)

    Geppert, Christopher

    2008-01-01

    Since its initiation in the middle of the 1980s, the resonant ionization laser ion source has been established as a reliable and efficient on-line ion source for radioactive ion beams. In comparison to other on-line ion sources it comprises the advantages of high versatility for the elements to be ionized and of high selectivity and purity for the ion beam generated by resonant laser radiation. Dye laser systems have been the predominant and pioneering working horses for laser ion source applications up to recently, but the development of all-solid-state titanium:sapphire laser systems has nowadays initiated a significant evolution within this field. In this paper an overview of the ongoing developments will be given, which have contributed to the establishment of a number of new laser ion source facilities worldwide during the last five years.

  14. An all-solid state laser system for the laser ion sources RILIS and in-source laser spectroscopy of astatine at ISOLDE/CERN

    International Nuclear Information System (INIS)

    Rothe, Sebastian

    2012-01-01

    This doctoral thesis describes the extension of the resonance ionization laser ion source RILIS at CERN/ISOLDE by the addition of an all-solid state tunable titanium:sapphire (Ti:Sa) laser system to complement the well-established system of dye lasers. Synchronous operation of the so called Dual RILIS system of Ti:Sa and dye lasers was investigated and the potential for increased ion beam intensity, reliability, and reduced setup time has been demonstrated. In-source resonance ionization spectroscopy was performed at ISOLDE/CERN and at ISAC/TRIUMF radioactive ion beam facilities to develop an efficient and selective three-colour ionization scheme for the purely radioactive element astatine. A LabVIEW based monitoring, control and measurement system was conceived which enabled, in conjunction with Dual RILIS operation, the spectroscopy of high lying Rydberg states, from which the ionization potential of the astatine atom was determined for the first time experimentally.

  15. An all-solid state laser system for the laser ion source RILIS and in-source laser spectroscopy of astatine at ISOLDE, CERN

    CERN Document Server

    Rothe, Sebastian; Nörtershäuser, W

    This doctoral thesis describes the extension of the resonance ionization laser ion source RILIS at ISOLDE, CERN, by the addition of an all-solid state tuneable titanium: sapphire (Ti:Sa) laser system to complement the well-established system of dye lasers. Synchronous operation of the so called Dual RILIS system of Ti:Sa and dye lasers was investigated and the potential for increased ion beam intensity, reliability, and reduced setup time has been demonstrated. In-source resonance ionization spectroscopy was performed at ISOLDE, CERN, and at ISAC, TRIUMF, radioactive ion beam facilities to develop an efficient and selective three-colour ionization scheme for the purely radioactive element astatine. A LabVIEW based monitoring, control and measurement system was conceived which enabled, in conjunction with Dual RILIS operation, the spectroscopy of high lying Rydberg states, from which the ionization potential of the astatine atom was determined for the first time experimentally.

  16. An all-solid state laser system for the laser ion sources RILIS and in-source laser spectroscopy of astatine at ISOLDE/CERN

    Energy Technology Data Exchange (ETDEWEB)

    Rothe, Sebastian

    2012-09-24

    This doctoral thesis describes the extension of the resonance ionization laser ion source RILIS at CERN/ISOLDE by the addition of an all-solid state tunable titanium:sapphire (Ti:Sa) laser system to complement the well-established system of dye lasers. Synchronous operation of the so called Dual RILIS system of Ti:Sa and dye lasers was investigated and the potential for increased ion beam intensity, reliability, and reduced setup time has been demonstrated. In-source resonance ionization spectroscopy was performed at ISOLDE/CERN and at ISAC/TRIUMF radioactive ion beam facilities to develop an efficient and selective three-colour ionization scheme for the purely radioactive element astatine. A LabVIEW based monitoring, control and measurement system was conceived which enabled, in conjunction with Dual RILIS operation, the spectroscopy of high lying Rydberg states, from which the ionization potential of the astatine atom was determined for the first time experimentally.

  17. Controlling branching in streamer discharge by laser background ionization

    International Nuclear Information System (INIS)

    Takahashi, E; Kato, S; Furutani, H; Sasaki, A; Kishimoto, Y

    2011-01-01

    Irradiation with a KrF laser controlled the positive streamer branching in atmospheric argon gas. This laser irradiation changed the amount of background ionization before the streamer discharge. Measuring the ionization current allowed us to evaluate the initial electron density formed by the KrF laser. We observed characteristic feather-like branching structure and found that it was only suppressed in the irradiated region. The threshold of ionization density which can influence the branching was evaluated to be 5 x 10 5 cm -3 . The relationship between the size of avalanche head and mean distance between initial electrons explained this suppression behaviour. These experimental results support that the feather-like structure originates from the branching model of Loeb-Meek, a probabilistic merging of individual avalanches.

  18. Laser-supported ionization wave in under-dense gases and foams

    International Nuclear Information System (INIS)

    Gus'kov, S. Yu.; Limpouch, J.; Nicolaie, Ph.; Tikhonchuk, V. T.

    2011-01-01

    Propagation of laser-supported ionization wave in homogeneous and porous materials with a mean density less than the critical plasma density is studied theoretically in the one-dimensional geometry. It is shown that the velocity of the ionization wave in a foam is significantly decreased in comparison with the similar wave in a homogeneous fully ionized plasma of the same density. That difference is attributed to the ionization and hydro-homogenization processes forming an under-critical density environment in the front of ionization wave. The rate of energy transfer from laser to plasma is found to be in a good agreement with available experimental data.

  19. The ISOLDE RILIS pump laser upgrade and the LARIS Laboratory

    International Nuclear Information System (INIS)

    Marsh, B. A.; Berg, L.-E.; Fedorov, D. V.; Fedosseev, V. N.; Launila, O. J.; Lindroos, M.; Losito, R.; Osterdahl, F. K.; Pauchard, T.; Pohjalainen, I. T.; Sassenberg, U.; Seliverstov, M. D.; Sjoedin, A. M.; Transtroemer, G.

    2010-01-01

    On account of its high efficiency, speed and unmatched selectivity, the Resonance Ionization Laser Ion Source (RILIS) is the preferred method for ionizing the nuclear reaction products at the ISOLDE on-line isotope separator facility. By exploiting the unique electronic energy level 'fingerprint' of a chosen element, the RILIS process of laser step-wise resonance ionization enables an ion beam of high chemical purity to be sent through the mass selective separator magnet. The isobaric purity of a beam of a chosen isotope is therefore greatly increased. The RILIS, comprising of up to three frequency tunable pulsed dye lasers has been upgraded with the installation of a Nd:YAG pump laser as a replacement for the old Copper Vapor Laser (CVL) system. A summary of the current Nd:YAG pumped RILIS performance is given. To accompany the RILIS pump laser upgrade, a new ionization scheme for manganese has been developed at the newly constructed LAser Resonance Ionization Spectroscopy (LARIS) laboratory and successfully applied for on-line RILIS operation. An overview of the LARIS facility is given along with details of the ionization scheme development work for manganese.

  20. Novel Laser Ignition Technique Using Dual-Pulse Pre-Ionization

    Science.gov (United States)

    Dumitrache, Ciprian

    Recent advances in the development of compact high power laser sources and fiber optic delivery of giant pulses have generated a renewed interest in laser ignition. The non-intrusive nature of laser ignition gives it a set of unique characteristics over the well-established capacitive discharge devices (or spark plugs) that are currently used as ignition sources in engines. Overall, the use of laser ignition has been shown to have a positive impact on engine operation leading to a reduction in NOx emission, fuel saving and an increased operational envelope of current engines. Conventionally, laser ignition is achieved by tightly focusing a high-power q-switched laser pulse until the optical intensity at the focus is high enough to breakdown the gas molecules. This leads to the formation of a spark that serves as the ignition source in engines. However, there are certain disadvantages associated with this ignition method. This ionization approach is energetically inefficient as the medium is transparent to the laser radiation until the laser intensity is high enough to cause gas breakdown. As a consequence, very high energies are required for ignition (about an order of magnitude higher energy than capacitive plugs at stoichiometric conditions). Additionally, the fluid flow induced during the plasma recombination generates high vorticity leading to high rates of flame stretching. In this work, we are addressing some of the aforementioned disadvantages of laser ignition by developing a novel approach based on a dual-pulse pre-ionization scheme. The new technique works by decoupling the effect of the two ionization mechanisms governing plasma formation: multiphoton ionization (MPI) and electron avalanche ionization (EAI). An UV nanosecond pulse (lambda = 266 nm) is used to generate initial ionization through MPI. This is followed by an overlapped NIR nanosecond pulse (lambda = 1064 nm) that adds energy into the pre-ionized mixture into a controlled manner until the

  1. Atomic resonances above the total ionization energy

    International Nuclear Information System (INIS)

    Doolen, G.

    1975-01-01

    A rigorous result obtained using the theory associated with dilatation analytic potentials is that by performing a complex coordinate rotation, r/subj/ → r/subj/e/subi//sup theta/, on a Hamiltonian whose potential involves only pairwise Coulombic interactions, one can show that when theta = π/2, no complex eigenvalues (resonances) appear whose energies have a real part greater than the total ionization energy of the atomic system. This appears to conflict with experimental results of Walton, Peart, and Dolder, who find resonance behavior above the total ionization energy of the H -- system and also the theoretical stabilization results of Taylor and Thomas for the same system. A possible resolution of this apparent conflict is discussed and a calculation to check its validity is proposed

  2. Secondary ionization processes in laser induced breakdown of electronegative gases

    International Nuclear Information System (INIS)

    Gamal Yosr, E.E.D.; Shafik, M.S.; Abdel-Moneim, H.M.

    1990-08-01

    This paper presents an investigation of the stepwise ionization processes which occur during the interaction of laser radiation with electronegative gases. Calculations are carried out adopting a modified version of the electron cascade model previously developed by Evans and Gamal. The modifications of the model are performed for the case of molecular oxygen to account for electron attachment losses. Particular attention is devoted to molecular oxygen at a pressure of 2.8 x 10 4 Torr irradiated by 10 ns pulse of Nd:YAG laser (λ=1.064 μm) at a peak intensity of 1.7x10 11 Wcm -2 . The calculations consider the effect of the secondary ionization processes on the electron energy distribution function and its parameters (evolution of the density of the excited molecules, electrons density as well as the electron mean energy during the laser flash). This analysis shows how the removal of slow electrons by attachment to oxygen molecules creates a strong competition between the stepwise ionization processes. These processes namely photoionization and collisional ionization deplete the electronic excited states and contribute eventually to the ionization growth rate in laser induced breakdown of electronegative gases. (author). 7 refs, 6 figs, 1 tab

  3. One- and two-photon single ionization of 1D helium: resolving the role of individual decay channels and resonance states

    Energy Technology Data Exchange (ETDEWEB)

    Neimanns, Vera; Zimmermann, Klaus; Joerder, Felix; Buchleitner, Andreas [Albert-Ludwigs-Univ., Freiburg im Breisgau (Germany). Quantum Optics and Statistics; Lugan, Pierre [Laboratory of Theoretical Physics of Nanosystems, Institute of Theoretical Physics, EPF Lausanne (Switzerland)

    2012-07-01

    We combine the method of complex rotation and Floquet theory to analyze the multiphoton ionization of helium atoms in strong laser fields. We focus on 1D Z{sup 2+}e{sup -}e{sup -} helium to highlight the methods that allow us to extract the partial decay rates associated with various decay channels. In the regime of one-photon single ionization, we study the dependence of the partial rates associated with the singly ionized He{sup +}(N) states on the field frequency. We show that the electron-electron interaction provides couplings to higher single-ionization continua. Finally, we examine two-photon single-ionization processes, and analyze the role of the internal electronic structure of the atom, specifically the signature of resonant coupling to intermediate bound states on the decay rates.

  4. Regime for a Self-ionizing Raman Laser Amplifier

    International Nuclear Information System (INIS)

    Clark, D.S.; Fisch, N.J.

    2001-01-01

    Backward Raman amplification and compression at high power might occur if a long pumping laser pulse is passed through a plasma to interact resonantly with a counter-propagating short seed pulse [V.M. Malkin, et al., Phys. Rev. Lett. 82 (1999) 4448-4451]. One critical issue, however, is that the pump may be unacceptably depleted due to spontaneous Raman backscatter from intrinsic fluctuations in the amplifying plasma medium prior to its useful interaction with the seed. Premature backscatter may be avoided, however, by employing a gaseous medium with pump intensities too low to ionize the medium, and using the intense seed to produce the plasma by rapid photoionization as it is being amplified [V.M. Malkin, et al., Phys. Plasmas (2001)]. In addition to allowing that only rather low power pumps be used, photoionization introduces a damping of the short pulse which must be overcome by the Raman growth rate for net amplification to occur. The parameter space of gas densities, laser wavelengths, and laser intensities is surveyed to identify favorable regimes for this effect. Output laser intensities of 10(superscript ''17'') W/cm(superscript ''2'') for 0.5 mm radiation are found to be feasible for such a scheme using a pump of 10(superscript ''13'') W/cm(superscript ''2'') and an initial seed of 5 x 10(superscript ''14'') W/cm(superscript ''2'') over an amplification length of 5.6 cm in hydrogen gas

  5. A new Technique for ultrafast velocity distribution measurements of atomic species by post-ionization laser induced fluorescence (PILIF)

    International Nuclear Information System (INIS)

    Tabares, F.L.

    1992-01-01

    A new method for single shot velocity distribution measurement of metallic impurities of relevance for studies involving continuous sources, such as limiter experiments in fusion devices or sputtering experiments, based in the combination of Resonant Enhanced Multiphoton Ionization (REMPI) and Laser Induced Fluorescence (LIF) is proposed. High ionization yield and good time resolution are expected according to the numerical simulation of the experiment that has been run for several atomic species. Other possible applications of REMPI to plasma edge physics and to conventional techniques for velocity distribution measurements are briefly addressed. (author)

  6. A new technique for ultrafast velocity distribution measurements of atomic species by post-ionization laser induced fluorescent (PILIF)

    International Nuclear Information System (INIS)

    Tabares, F.L.

    1992-01-01

    A new method for single shot velocity distribution measurement of metallic impurities of relevance for studies involving continuous sources, such as limiter experiments in fusion devices or sputtering experiments, based in the combination of Resonant Enhanced Multiphoton ionization (REMPI) and Laser Induced Fluorescence (LIF) is proposed. High ionization yield and good time resolution are expected according to the numerical simulation of the experiment that has been run for several atomic species. Other possible applications of REMPI to plasma edge physics and to conventional techniques for velocity distribution measurements are briefly addressed. (Author) 8 refs

  7. A new technique for ultrafast velocity distribution measurements of atomic species by post-ionization laser induced fluorescent (PILIF)

    Energy Technology Data Exchange (ETDEWEB)

    Tabares, F.L.

    1992-07-01

    A new method for single shot velocity distribution measurement of metallic impurities of relevance for studies involving continuous sources, such as limiter experiments in fusion devices or sputtering experiments, based in the combination of Resonant Enhanced Multiphoton ionization (REMPI) and Laser Induced Fluorescence (LIF) is proposed. High ionization yield and good time resolution are expected according to the numerical simulation of the experiment that has been run for several atomic species. Other possible applications of REMPI to plasma edge physics and to conventional techniques for velocity distribution measurements are briefly addressed. (Author) 8 refs.

  8. Performance of a high repetition pulse rate laser system for in-gas-jet laser ionization studies with the Leuven laser ion source LISOL

    International Nuclear Information System (INIS)

    Ferrer, R.; Sonnenschein, V.T.; Bastin, B.; Franchoo, S.; Huyse, M.; Kudryavtsev, Yu.; Kron, T.; Lecesne, N.; Moore, I.D.; Osmond, B.; Pauwels, D.; Radulov, D.; Raeder, S.; Rens, L.

    2012-01-01

    The laser ionization efficiency of the Leuven gas cell-based laser ion source was investigated under on- and off-line conditions using two distinctly different laser setups: a low-repetition rate dye laser system and a high-repetition rate Ti:sapphire laser system. A systematic study of the ion signal dependence on repetition rate and laser pulse energy was performed in off-line tests using stable cobalt and copper isotopes. These studies also included in-gas-jet laser spectroscopy measurements on the hyperfine structure of 63 Cu. A final run under on-line conditions in which the radioactive isotope 59 Cu (T 1/2 = 81.5 s) was produced, showed a comparable yield of the two laser systems for in-gas-cell ionization. However, a significantly improved time overlap by using the high-repetition rate laser system for in-gas-jet ionization was demonstrated by an increase of the overall duty cycle, and at the same time, pointed to the need for a better shaped atomic jet to reach higher ionization efficiencies.

  9. Hyperfine structure of 147,149Sm measured using saturated absorption spectroscopy in combination with resonance-ionization mass spectroscopy

    International Nuclear Information System (INIS)

    Park, Hyunmin; Lee, Miran; Rhee, Yongjoo

    2003-01-01

    The hyperfine structures of four levels of the Sm isotopes have been measured by means of diode-laser-based Doppler-free saturated absorption spectroscopy in combination with a diode-laser-initiated resonance-ionization mass spectroscopy. It was demonstrated that combining the two spectroscopic methods was very effective for the identification and accurate measurement of the spectral lines of atoms with several isotopes, such as the rare-earth elements. From the obtained spectra, the hyperfine constants A and B for the odd-mass isotopes 147 Sm and 149 Sm were determined for four upper levels of the studied transitions.

  10. Ionization of molecular hydrogen in ultrashort intense laser pulses

    Energy Technology Data Exchange (ETDEWEB)

    Vanne, Yulian V.

    2010-03-18

    A novel ab initio numerical approach is developed and applied that solves the time-dependent Schroedinger equation describing two-electron diatomic molecules (e.g. molecular hydrogen) exposed to an intense ultrashort laser pulse. The method is based on the fixed-nuclei and the non-relativistic dipole approximations and aims to accurately describe both correlated electrons in full dimensionality. The method is applicable for a wide range of the laser pulse parameters and is able to describe both few-photon and many-photon single ionization processes, also in a non-perturbative regime. A key advantage of the method is its ability to treat the strong-field response of the molecules with arbitrary orientation of the molecular axis with respect to the linear-polarized laser field. Thus, this work reports on the first successful orientation-dependent analysis of the multiphoton ionization of H{sub 2} performed by means of a full-dimensional numerical treatment. Besides the investigation of few-photon regime, an extensive numerical study of the ionization by ultrashort frequency-doubled Ti:sapphire laser pulses (400 nm) is presented. Performing a series of calculations for different internuclear separations, the total ionization yields of H{sub 2} and D{sub 2} in their ground vibrational states are obtained for both parallel and perpendicular orientations. A series of calculations for 800 nm laser pulses are used to test a popular simple interference model. Besides the discussion of the ab initio numerical method, this work considers different aspects related to the application of the strong-field approximation (SFA) for investigation of a strong-field response of an atomic and molecular system. Thus, a deep analysis of the gauge problem of SFA is performed and the quasistatic limit of the velocity-gauge SFA ionization rates is derived. The applications of the length-gauge SFA are examined and a recently proposed generalized Keldysh theory is criticized. (orig.)

  11. Ionization of molecular hydrogen in ultrashort intense laser pulses

    International Nuclear Information System (INIS)

    Vanne, Yulian V.

    2010-01-01

    A novel ab initio numerical approach is developed and applied that solves the time-dependent Schroedinger equation describing two-electron diatomic molecules (e.g. molecular hydrogen) exposed to an intense ultrashort laser pulse. The method is based on the fixed-nuclei and the non-relativistic dipole approximations and aims to accurately describe both correlated electrons in full dimensionality. The method is applicable for a wide range of the laser pulse parameters and is able to describe both few-photon and many-photon single ionization processes, also in a non-perturbative regime. A key advantage of the method is its ability to treat the strong-field response of the molecules with arbitrary orientation of the molecular axis with respect to the linear-polarized laser field. Thus, this work reports on the first successful orientation-dependent analysis of the multiphoton ionization of H 2 performed by means of a full-dimensional numerical treatment. Besides the investigation of few-photon regime, an extensive numerical study of the ionization by ultrashort frequency-doubled Ti:sapphire laser pulses (400 nm) is presented. Performing a series of calculations for different internuclear separations, the total ionization yields of H 2 and D 2 in their ground vibrational states are obtained for both parallel and perpendicular orientations. A series of calculations for 800 nm laser pulses are used to test a popular simple interference model. Besides the discussion of the ab initio numerical method, this work considers different aspects related to the application of the strong-field approximation (SFA) for investigation of a strong-field response of an atomic and molecular system. Thus, a deep analysis of the gauge problem of SFA is performed and the quasistatic limit of the velocity-gauge SFA ionization rates is derived. The applications of the length-gauge SFA are examined and a recently proposed generalized Keldysh theory is criticized. (orig.)

  12. Resonance Raman Spectroscopy of Free Radicals Produced by Ionizing Radiation

    DEFF Research Database (Denmark)

    Wilbrandt, Robert Walter

    1984-01-01

    Applications of time-resolved resonance Raman spectroscopy to the study of short-lived free radicals produced by ionizing radiation are briefly reviewed. Potential advantages and limitations of this technique are discussed in the light of given examples. The reduction of p-nitrobenzylchloride and......Applications of time-resolved resonance Raman spectroscopy to the study of short-lived free radicals produced by ionizing radiation are briefly reviewed. Potential advantages and limitations of this technique are discussed in the light of given examples. The reduction of p......-nitrobenzylchloride and subsequent formation of the p-nitrobenzyl radical and the reaction of p-nitrotoluene with O– are studied by resonance Raman and optical absorption spectroscopy....

  13. Novel two-step laser ablation and ionization mass spectrometry (2S-LAIMS) of actor-spectator ice layers: Probing chemical composition of D2O ice beneath a H2O ice layer

    International Nuclear Information System (INIS)

    Yang, Rui; Gudipati, Murthy S.

    2014-01-01

    In this work, we report for the first time successful analysis of organic aromatic analytes imbedded in D 2 O ices by novel infrared (IR) laser ablation of a layered non-absorbing D 2 O ice (spectator) containing the analytes and an ablation-active IR-absorbing H 2 O ice layer (actor) without the analyte. With these studies we have opened up a new method for the in situ analysis of solids containing analytes when covered with an IR laser-absorbing layer that can be resonantly ablated. This soft ejection method takes advantage of the tenability of two-step infrared laser ablation and ultraviolet laser ionization mass spectrometry, previously demonstrated in this lab to study chemical reactions of polycyclic aromatic hydrocarbons (PAHs) in cryogenic ices. The IR laser pulse tuned to resonantly excite only the upper H 2 O ice layer (actor) generates a shockwave upon impact. This shockwave penetrates the lower analyte-containing D 2 O ice layer (spectator, a non-absorbing ice that cannot be ablated directly with the wavelength of the IR laser employed) and is reflected back, ejecting the contents of the D 2 O layer into the vacuum where they are intersected by a UV laser for ionization and detection by a time-of-flight mass spectrometer. Thus, energy is transmitted from the laser-absorbing actor layer into the non-absorbing spectator layer resulting its ablation. We found that isotope cross-contamination between layers was negligible. We also did not see any evidence for thermal or collisional chemistry of PAH molecules with H 2 O molecules in the shockwave. We call this “shockwave mediated surface resonance enhanced subsurface ablation” technique as “two-step laser ablation and ionization mass spectrometry of actor-spectator ice layers.” This method has its roots in the well-established MALDI (matrix assisted laser desorption and ionization) method. Our method offers more flexibility to optimize both the processes—ablation and ionization. This new technique

  14. Minimizing matrix effect by femtosecond laser ablation and ionization in elemental determination.

    Science.gov (United States)

    Zhang, Bochao; He, Miaohong; Hang, Wei; Huang, Benli

    2013-05-07

    Matrix effect is unavoidable in direct solid analysis, which usually is a leading cause of the nonstoichiometric effect in quantitative analysis. In this research, experiments were carried out to study the overall characteristics of atomization and ionization in laser-solid interaction. Both nanosecond (ns) and femtosecond (fs) lasers were applied in a buffer-gas-assisted ionization source coupled with an orthogonal time-of-flight mass spectrometer. Twenty-nine solid standards of ten different matrices, including six metals and four dielectrics, were analyzed. The results indicate that the fs-laser mode offers more stable relative sensitivity coefficients (RSCs) with irradiance higher than 7 × 10(13) W·cm(-2), which could be more reliable in the determination of element composition of solids. The matrix effect is reduced by half when the fs-laser is employed, owing to the fact that the fs-laser ablation and ionization (fs-LAI) incurs an almost heat-free ablation process and creates a dense plasma for the stable ionization.

  15. Time-resolved spectroscopy of nonequilibrium ionization in laser-produced plasmas

    International Nuclear Information System (INIS)

    Marjoribanks, R.S.

    1988-01-01

    The highly transient ionization characteristic of laser-produced plasmas at high energy densities has been investigated experimentally, using x-ray spectroscopy with time resolution of less than 20 ps. Spectroscopic diagnostics of plasma density and temperature were used, including line ratios, line profile broadening and continuum emission, to characterize the plasma conditions without relying immediately on ionization modeling. The experimentally measured plasma parameters were used as independent variables, driving an ionization code, as a test of ionization modeling, divorced from hydrodynamic calculations. Several state-of-the-art streak spectrographs, each recording a fiducial of the laser peak along with the time-resolved spectrum, characterized the laser heating of thin signature layers of different atomic numbers imbedded in plastic targets. A novel design of crystal spectrograph, with a conically curved crystal, was developed. Coupled with a streak camera, it provided high resolution (λ/ΔΛ > 1000) and a collection efficiency roughly 20-50 times that of planar crystal spectrographs, affording improved spectra for quantitative reduction and greater sensitivity for the diagnosis of weak emitters. Experimental results were compared to hydrocode and ionization code simulations, with poor agreement. The conclusions question the appropriateness of describing electron velocity distributions by a temperature parameter during the time of laser illumination and emphasis the importance of characterizing the distribution more generally

  16. Resonance ionization detection of combustion radicals

    Energy Technology Data Exchange (ETDEWEB)

    Cool, T.A. [Cornell Univ., Ithaca, NY (United States)

    1993-12-01

    Fundamental research on the combustion of halogenated organic compounds with emphasis on reaction pathways leading to the formation of chlorinated aromatic compounds and the development of continuous emission monitoring methods will assist in DOE efforts in the management and disposal of hazardous chemical wastes. Selective laser ionization techniques are used in this laboratory for the measurement of concentration profiles of radical intermediates in the combustion of chlorinated hydrocarbon flames. A new ultrasensitive detection technique, made possible with the advent of tunable VUV laser sources, enables the selective near-threshold photoionization of all radical intermediates in premixed hydrocarbon and chlorinated hydrocarbon flames.

  17. Ultra slow muon microscopy by laser resonant ionization at J-PARC, MUSE

    Science.gov (United States)

    Miyake, Y.; Ikedo, Y.; Shimomura, K.; Strasser, P.; Kawamura, N.; Nishiyama, K.; Koda, A.; Fujimori, H.; Makimura, S.; Nakamura, J.; Nagatomo, T.; Kadono, R.; Torikai, E.; Iwasaki, M.; Wada, S.; Saito, N.; Okamura, K.; Yokoyama, K.; Ito, T.; Higemoto, W.

    2013-04-01

    As one of the principal muon beam line at the J-PARC muon facility (MUSE), we are now constructing a Muon beam line (U-Line), which consists of a large acceptance solenoid made of mineral insulation cables (MIC), a superconducting curved transport solenoid and superconducting axial focusing magnets. There, we can extract 2 × 108/s surface muons towards a hot tungsten target. At the U-Line, we are now establishing a new type of muon microscopy; a new technique with use of the intense ultra-slow muon source generated by resonant ionization of thermal Muonium (designated as Mu; consisting of a μ + and an e - ) atoms generated from the surface of the tungsten target. In this contribution, the latest status of the Ultra Slow Muon Microscopy project, fully funded, is reported.

  18. Multiphoton ionization of H{sub 2}{sup +} in xuv laser pulses

    Energy Technology Data Exchange (ETDEWEB)

    Guan Xiaoxu; Secor, Ethan B.; Bartschat, Klaus [Department of Physics and Astronomy, Drake University, Des Moines, Iowa 50311 (United States); Schneider, Barry I. [Office of Cyberinfrastructure, National Science Foundation, Arlington, Virgina 22230 (United States)

    2011-09-15

    We consider the ionization of the hydrogen molecular ion after one-, two-, and three-photon absorption over a large range of photon energies between 9 and 40 eV in the fixed-nuclei approximation. The temporal development of the system is obtained in a fully ab initio time-dependent grid-based approach in prolate spheroidal coordinates. The alignment dependence of the one-photon ionization amplitude is highlighted in the framework of time-dependent perturbation theory. For one-photon ionization as a function of the nuclear separation, the calculations reveal a significant minimum in the ionization probability. The suppressed ionization is attributed to a Cooper-type minimum, which is similar, but not identical, to the cancellation effect observed in photoionization cross sections of some noble-gas atoms. The effect of the nonspherical two-center Coulomb potential is analyzed. For two- and three-photon ionization, the angle-integrated cross sections clearly map out intermediate-state resonances, and the predictions of the current computations agree very well with those from time-independent calculations. The dominant emission modes for two-photon ionization are found to be very similar in both resonance and off-resonance regions.

  19. Collective ion acceleration via laser controlled ionization channel

    International Nuclear Information System (INIS)

    Destler, W.W.; O'Shea, P.G.; Rodgers, J.; Segalov, Z.

    1987-01-01

    Initial results from a successful laser-controlled collective ion acceleration experiment at the University of Maryland are presented. In the experiment, positive ions are trapped in the potential well at the head of an intense relativistic electron beam injected at current levels above the space charge limit. Seed ions for acceleration are provided by puff valve injection of a neutral gas cloud localized to within 3 cm of the injection point. Control over the acceleration of the well and the ions is then achieved by means of a laser-generated ionization channel produced by passing the light from a Q-switched ruby laser through a series of partially and fully reflecting mirrors in such a way as to provide time-sequenced laser ionization of a target located on the drift tube wall. Using this system, controlled acceleration of protons at a rate of approximately 40 MV/m has been demonstrated over a distance of about 50 cm

  20. The laser desorption/laser ionization mass spectra of some methylated xanthines and the laser desorption of caffeine and theophylline from thin layer chromatography plates

    Science.gov (United States)

    Rogers, Kevin; Milnes, John; Gormally, John

    1993-02-01

    Laser desorption/laser ionization time-of-flight mass spectra of caffeine, theophylline, theobromine and xanthine are reported. These mass spectra are compared with published spectra obtained using electron impact ionization. Mass spectra of caffeine and theophylline obtained by IR laser desorption from thin layer chromatography plates are also described. The laser desorption of materials from thin layer chromatography plates is discussed.

  1. Laser desorption ionization and peptide sequencing on laser induced silicon microcolumn arrays

    Science.gov (United States)

    Vertes, Akos [Reston, VA; Chen, Yong [San Diego, CA

    2011-12-27

    The present invention provides a method of producing a laser-patterned silicon surface, especially silicon wafers for use in laser desorption ionization (LDI-MS) (including MALDI-MS and SELDI-MS), devices containing the same, and methods of testing samples employing the same. The surface is prepared by subjecting a silicon substrate to multiple laser shots from a high-power picosecond or femtosecond laser while in a processing environment, e.g., underwater, and generates a remarkable homogenous microcolumn array capable of providing an improved substrate for LDI-MS.

  2. Ultra slow muon microscopy by laser resonant ionization at J-PARC, MUSE

    Energy Technology Data Exchange (ETDEWEB)

    Miyake, Y., E-mail: yasuhiro.miyake@kek.jp; Ikedo, Y.; Shimomura, K.; Strasser, P.; Kawamura, N.; Nishiyama, K.; Koda, A.; Fujimori, H.; Makimura, S.; Nakamura, J.; Nagatomo, T.; Kadono, R. [High Energy Accelerator Research Organization (KEK), Muon Science Laboratory (Japan); Torikai, E. [Yamanashi University, Faculty of Engineering (Japan); Iwasaki, M. [RIKEN Nishina Center, Advanced Meson Science Laboratory (Japan); Wada, S.; Saito, N. [RIKEN, Advanced Science Institute (Japan); Okamura, K. [RIKEN-WAKO Incubation Plaza 301, Megaopto Co., Ltd. (Japan); Yokoyama, K. [RIKEN Nishina Center, Advanced Meson Science Laboratory (Japan); Ito, T.; Higemoto, W. [J-PARC Center, Muon Section, Materials and Life Science Division (Japan)

    2013-04-15

    As one of the principal muon beam line at the J-PARC muon facility (MUSE), we are now constructing a Muon beam line (U-Line), which consists of a large acceptance solenoid made of mineral insulation cables (MIC), a superconducting curved transport solenoid and superconducting axial focusing magnets. There, we can extract 2 Multiplication-Sign 10{sup 8}/s surface muons towards a hot tungsten target. At the U-Line, we are now establishing a new type of muon microscopy; a new technique with use of the intense ultra-slow muon source generated by resonant ionization of thermal Muonium (designated as Mu; consisting of a {mu}{sup + } and an e{sup - }) atoms generated from the surface of the tungsten target. In this contribution, the latest status of the Ultra Slow Muon Microscopy project, fully funded, is reported.

  3. Three-color resonance ionization spectroscopy of Zr in Si

    International Nuclear Information System (INIS)

    Hansen, C.S.; Calaway, W.F.; Pellin, M.J.; Wiens, R.C.; Burnett, D.S.

    1997-01-01

    It has been proposed that the composition of the solar wind could be measured directly by transporting ultrapure collectors into space, exposing them to the solar wind, and returning them to earth for analysis. In a study to help assess the applicability of present and future postionization secondary neutral mass spectrometers for measuring solar wind implanted samples, measurements of Zr in Si were performed. A three-color resonant ionization scheme proved to be efficient while producing a background count rate limited by secondary ion signal (5x10 -4 counts/laser pulse). This lowered the detection limit for these measurements to below 500 ppt for 450,000 averages. Unexpectedly, the Zr concentration in the Si was measured to be over 4 ppb, well above the detection limit of the analysis. This high concentration is thought to result from contamination during sample preparation, since a series of tests were performed that rule out memory effects during the analysis. copyright 1997 American Institute of Physics

  4. Three-color resonance ionization spectroscopy of Zr in Si

    International Nuclear Information System (INIS)

    Hansen, C. S.; Calaway, W. F.; Pellin, M. J.; Wiens, R. C.; Burnett, D. S.

    1997-01-01

    It has been proposed that the composition of the solar wind could be measured directly by transporting ultrapure collectors into space, exposing them to the solar wind, and returning them to earth for analysis. In a study to help assess the applicability of present and future postionization secondary neutral mass spectrometers for measuring solar wind implanted samples, measurements of Zr in Si were performed. A three-color resonant ionization scheme proved to be efficient while producing a background count rate limited by secondary ion signal (5x10 -4 counts/laser pulse). This lowered the detection limit for these measurements to below 500 ppt for 450,000 averages. Unexpectedly, the Zr concentration in the Si was measured to be over 4 ppb, well above the detection limit of the analysis. This high concentration is thought to result from contamination during sample preparation, since a series of tests were performed that rule out memory effects during the analysis

  5. Classical trajectory perspective of atomic ionization in strong laser fields. Semiclassical modeling

    International Nuclear Information System (INIS)

    Liu, Jie

    2014-01-01

    Dealing with timely and interesting issues in strong laser physics. Illustrates complex strong field atomic ionization with the simple semiclassical model of classical trajectory perspective for the first time. Provides a theoretical model that can be used to account for recent experiments. The ionization of atoms and molecules in strong laser fields is an active field in modern physics and has versatile applications in such as attosecond physics, X-ray generation, inertial confined fusion (ICF), medical science and so on. Classical Trajectory Perspective of Atomic Ionization in Strong Laser Fields covers the basic concepts in this field and discusses many interesting topics using the semiclassical model of classical trajectory ensemble simulation, which is one of the most successful ionization models and has the advantages of a clear picture, feasible computing and accounting for many exquisite experiments quantitatively. The book also presents many applications of the model in such topics as the single ionization, double ionization, neutral atom acceleration and other timely issues in strong field physics, and delivers useful messages to readers with presenting the classical trajectory perspective on the strong field atomic ionization. The book is intended for graduate students and researchers in the field of laser physics, atom molecule physics and theoretical physics. Dr. Jie Liu is a professor of Institute of Applied Physics and Computational Mathematics, China and Peking University.

  6. A cyclotron resonance laser accelerator

    International Nuclear Information System (INIS)

    Sprangle, P.; Tang, C.M.; Vlahos, L.

    1983-01-01

    A laser acceleration mechanism which utilizes a strong static, almost uniform, magnetic field together with an intense laser pulse is analyzed. The interaction and acceleration mechanism relies on a self resonance effect. Since the laser field is assumed to be diffraction limited, the magnetic field must be spatially varied to maintain resonance. The effective accelerating gradient is shown to scale like 1/√E /SUB b/ , where E /SUB b/ is the electron energy. For a numerical illustration the authors consider a 1 x 10 13 W/cm 2 , CO 2 laser and show that electrons can be accelerated to more than 500 MeV in a distance of 15 m (approximately two Rayleigh lengths)

  7. Isotope-selective ionization using four-pulse alignment

    International Nuclear Information System (INIS)

    Akagi, Hiroshi; Kasajima, Tatsuya; Kumada, Takayuki; Itakura, Ryuji; Yokoyama, Atsushi; Hasegawa, Hirokazu; Ohshima, Yasuhiro

    2013-01-01

    We have proposed a laser isotope separation method utilizing molecular alignment and non-resonant multiphoton ionization, and demonstrated isotope-selective ionization of 14 N 2 and 15 N 2 isotopomers, using one-pulse alignment. In the present work, we used a train of four identical pulses, instead of one pulse, to obtain the higher selectivity. (author)

  8. Explosives vapour identification in ion mobility spectrometry using a tunable laser ionization source: a comparison with conventional 63Ni ionization

    International Nuclear Information System (INIS)

    Clark, A.; Deas, R.M.; Kosmidis, C.; Ledingham, K.W.D.; Marshall, A.; Singhal, R.P.

    1995-01-01

    Laser multiphoton ionization (MPI) is used to produce ions from explosive vapours at atmospheric pressure in air for analysis by ion mobility spectrometry (IMS). In the positive ion mode of detection, NO + ions, generated directly by multiphoton dissociation/ionization of the explosive compounds, show strong variation with laser wavelength. This provides a means of identifying the presence of nitro-containing compounds. Moreover, electrons formed in the MPI of gaseous components in the air carrier stream, primarily O 2 , are transferred via neutral molecular oxygen (O 2 ) to trace explosive vapour, forming negative ions which give rise to characteristic and identifiable ion mobility spectra. Further, negative ion mobility spectra of several explosive vapours are presented using conventional 63 Ni ionization and are compared qualitatively with the laser ionization approach. (author)

  9. Resonance ionization and time-of-flight mass spectrometry for the analysis of trace substances in complex gas mixtures

    International Nuclear Information System (INIS)

    Nagel, Holger; Weickhardt, Christian; Boesl, Ulrich; Frey, Ruediger

    1995-01-01

    The analysis of mixtures of technical gases still comprises a lot of problems: the large number of components with very different and often rapidly varying concentrations makes great demands on analytical methods. By use of conventional analytical methods, signals of trace substances may interfere with signals of main components, whereas small signals representing low concentrations are covered by signals of main substances.The resonant-enhanced multiphoton ionization (REMPI) makes use of excited intermediate states of molecules. As these states are characteristic of each substance, one or more components of interest can be ionized with high efficiency without interference of other molecules by using a special laser-wavelength. The combination of the above mentioned ionization method with a reflectron time-of-flight mass spectrometer permits a very fast and sensitive detection of preselected trace substances.As ionization processes of higher order strongly depend on the laser intensity, there is no direct relation between ion signals and concentrations of exhaust components. Quantitative assessments are based on an especially developed calibration technique that makes use of internal standards. Applied under environmental aspects, this new analytical method helps to analyze a large number of components extracted from exhaust gases of combustion engines with high time resolution (<20 ms motor synchronously), high sensitivity (1 ppm) and high quantitative accuracy (more than 10%). A preliminary list of detectable compounds contains 30 substances

  10. Tuning excitation laser wavelength for secondary resonance in low-intensity phase-selective laser-induced breakdown spectroscopy for in-situ analytical measurement of nanoaerosols

    Science.gov (United States)

    Xiong, Gang; Li, Shuiqing; Tse, Stephen D.

    2018-02-01

    In recent years, a novel low-intensity phase-selective laser-induced breakdown spectroscopy (PS-LIBS) technique has been developed for unique elemental-composition identification of aerosolized nanoparticles, where only the solid-phase nanoparticles break down, forming nanoplasmas, without any surrounding gas-phase breakdown. Additional work has demonstrated that PS-LIBS emissions can be greatly enhanced with secondary resonant excitation by matching the excitation laser wavelength with an atomic transition line in the formed nanoplasma, thereby achieving low limits of detection. In this work, a tunable dye laser is employed to investigate the effects of excitation wavelength and irradiance on in-situ PS-LIBS measurements of TiO2 nanoaerosols. The enhancement factor by resonant excitation can be 220 times greater than that for non-resonant cases under similar conditions. Moreover, the emitted spectra are unique for the selected resonant transition lines for a given element, suggesting the potential to make precise phase-selective and analyte-selective measurements of nanoparticles in a multicomponent multiphase system. The enhancement factor by resonant excitation is highly sensitive to excitation laser wavelength, with narrow excitation spectral windows, i.e., 0.012 to 0.023 nm (FWHM, full width at half maximum) for Ti (I) neutral atomic lines, and 0.051 to 0.139 nm (FWHM) for Ti (II) single-ionized atomic lines. Boltzmann analysis of the emission intensities, temporal response of emissions, and emission dependence on excitation irradiance are investigated to understand aspects of the generated nanoplasmas such as temperature, local thermodynamic equilibrium (LTE), and excitation mechanism.

  11. Quantum interference in laser-induced nonsequential double ionization

    Science.gov (United States)

    Quan, Wei; Hao, XiaoLei; Wang, YanLan; Chen, YongJu; Yu, ShaoGang; Xu, SongPo; Xiao, ZhiLei; Sun, RenPing; Lai, XuanYang; Hu, ShiLin; Liu, MingQing; Shu, Zheng; Wang, XiaoDong; Li, WeiDong; Becker, Wilhelm; Liu, XiaoJun; Chen, Jing

    2017-09-01

    Quantum interference plays an important role in various intense-laser-driven atomic phenomena, e.g., above-threshold ionization and high-order-harmonic generation, and provides a useful tool in ultrafast imaging of atomic and molecular structure and dynamics. However, it has eluded observation in nonsequential double ionization (NSDI), which serves as an ideal prototype to study electron-electron correlation. Thus far, NSDI usually could be well understood from a semiclassical perspective, where all quantum aspects have been ignored after the first electron has tunneled. Here we perform coincidence measurements for NSDI of xenon subject to laser pulses at 2400 nm. It is found that the intensity dependence of the asymmetry parameter between the yields in the second and fourth quadrants and those in the first and third quadrants of the electron-momentum-correlation distributions exhibits a peculiar fast oscillatory structure, which is beyond the scope of the semiclassical picture. Our theoretical analysis indicates that this oscillation can be attributed to interference between the contributions of different excited states in the recollision-excitation-with-subsequent-ionization channel. Our work demonstrates the significant role of quantum interference in NSDI and may create an additional pathway towards manipulation and imaging of the ultrafast atomic and molecular dynamics in intense laser fields.

  12. High resolution collinear resonance ionization spectroscopy of neutron-rich $^{76,77,78}$Cu isotopes

    CERN Document Server

    AUTHOR|(CDS)2083035

    In this work, nuclear magnetic dipole moments, electric quadrupole moments, nuclear spins and changes in the mean-squared charge radii of radioactive copper isotopes are presented. Reaching up to $^{78}$Cu ($Z=29$, $N=49$), produced at rates of only 10 particles per second, these measurements represent the most exotic laser spectroscopic investigations near the doubly-magic and very exotic $^{78}$Ni ($Z=28$,$N=50$) to date. This thesis outlines the technical developments and investigations of laser-atom interactions that were performed during this thesis. These developments were crucial for establishing a high-resolution, high sensitivity collinear resonance ionization spectroscopy experiment at ISOLDE, CERN. This thesis furthermore provides a detailed description of the analysis tools that were implemented and applied to extract the nuclear observables from the experimental data. The results were compared to several large-scale shell model calculations, and provide deep insight into the structure of $^{78}$N...

  13. Particle-in-cell Simulations of Raman Laser Amplification in Ionizing Plasmas

    International Nuclear Information System (INIS)

    Clark, Daniel S.; Fisch, Nathaniel J.

    2003-01-01

    By using the amplifying laser pulse in a plasma-based backward Raman laser amplifier to generate the plasma by photo-ionization of a gas simultaneous with the amplification process, possible instabilities of the pumping laser pulse can be avoided. Particle-in-cell simulations are used to study this amplification mechanism, and earlier results using more elementary models of the Raman interaction are verified [D.S. Clark and N.J. Fisch, Phys. Plasmas, 9 (6): 2772-2780, 2002]. The effects (unique to amplification in ionizing plasmas and not included in previous simulations) of blue-shifting of the pump and seed laser pulses and the generation of a wake are observed not significantly to impact the amplification process. As expected theoretically, the peak output intensity is found to be limited to I ∼ 10 17 W/cm 2 by forward Raman scattering of the amplifying seed. The integrity of the ionization front of the seed pulse against the development of a possible transverse modulation instability is also demonstrated

  14. Relativistic electron acceleration in focused laser fields after above-threshold ionization

    International Nuclear Information System (INIS)

    Dodin, I.Y.; Fisch, N.J.

    2003-01-01

    Electrons produced as a result of above-threshold ionization of high-Z atoms can be accelerated by currently producible laser pulses up to GeV energies, as shown recently by Hu and Starace [Phys. Rev. Lett. 88, 245003 (2002)]. To describe electron acceleration by general focused laser fields, we employ an analytical model based on a Hamiltonian, fully relativistic, ponderomotive approach. Though the above-threshold ionization represents an abrupt process compared to laser oscillations, the ponderomotive approach can still adequately predict the resulting energy gain if the proper initial conditions are introduced for the particle drift following the ionization event. Analytical expressions for electron energy gain are derived and the applicability conditions of the ponderomotive formulation are studied both analytically and numerically. The theoretical predictions are supported by numerical computations

  15. Photoionization of resonantly driven atomic states by an extreme ultraviolet-free-electron laser: intensity dependence and renormalization of Rabi frequencies

    International Nuclear Information System (INIS)

    Kaiser, B; Brand, A; Glässl, M; Vagov, A; Axt, V M; Pietsch, U

    2013-01-01

    We analyze theoretically the high intensity photoionization dynamics of a system with two atomic states resonantly coupled by coherent extreme ultraviolet laser radiation that also gives rise to the ionization. The ground state occupation of such a system is shown to exhibit damped Rabi oscillations. The corresponding ionization, which is responsible for the damping, scales almost linearly with the field intensity when the pulse length exceeds the Rabi period. For shorter pulses a quadratic scaling is found. The Rabi frequency is shifted compared to its value for an isolated two-level system. The shift increases with excitation intensity and can acquire a high percentage of the unrenormalized frequency at high intensities. Analytical results obtained within a simplified solvable model demonstrate that the damping and the shift both result from the coupling of the discrete states to the ionization continuum and are therefore closely related. Numerical simulations for a two-electron system reveal at high intensities the importance of off-resonant ionization channels. (paper)

  16. Studies of photoionization in liquids using a laser two-photon ionization conductivity technique

    International Nuclear Information System (INIS)

    Siomos, K.; Christophorou, L.G.

    1981-01-01

    One-photon ionization studies of solute molecules in a liquid medium are limited by the absorption of the host medium. A laser two-photon ionization (TPI) technique using a frequency tunable dye laser has been developed, whereby the photoionization threshold of a solute molecule was determined from the induced conductivity in the liquid medium under study due to electron-ion pair formation via two-photon ionization of the solute. The two-photon induced electron-ion current is measured as a function of the laser wavelength, lambda/sub laser/. In this paper, results are reported and discussed on the photoionization of N,N,N',N'-tetramethyl-p-phenylenediamine (TMPD), pyrene and fluoranthene in liquid n-pentane

  17. Measurement of the first ionization potential of astatine by laser ionization spectroscopy

    Science.gov (United States)

    Rothe, S.; Andreyev, A. N.; Antalic, S.; Borschevsky, A.; Capponi, L.; Cocolios, T. E.; De Witte, H.; Eliav, E.; Fedorov, D. V.; Fedosseev, V. N.; Fink, D. A.; Fritzsche, S.; Ghys, L.; Huyse, M.; Imai, N.; Kaldor, U.; Kudryavtsev, Yuri; Köster, U.; Lane, J. F. W.; Lassen, J.; Liberati, V.; Lynch, K. M.; Marsh, B. A.; Nishio, K.; Pauwels, D.; Pershina, V.; Popescu, L.; Procter, T. J.; Radulov, D.; Raeder, S.; Rajabali, M. M.; Rapisarda, E.; Rossel, R. E.; Sandhu, K.; Seliverstov, M. D.; Sjödin, A. M.; Van den Bergh, P.; Van Duppen, P.; Venhart, M.; Wakabayashi, Y.; Wendt, K. D. A.

    2013-01-01

    The radioactive element astatine exists only in trace amounts in nature. Its properties can therefore only be explored by study of the minute quantities of artificially produced isotopes or by performing theoretical calculations. One of the most important properties influencing the chemical behaviour is the energy required to remove one electron from the valence shell, referred to as the ionization potential. Here we use laser spectroscopy to probe the optical spectrum of astatine near the ionization threshold. The observed series of Rydberg states enabled the first determination of the ionization potential of the astatine atom, 9.31751(8) eV. New ab initio calculations are performed to support the experimental result. The measured value serves as a benchmark for quantum chemistry calculations of the properties of astatine as well as for the theoretical prediction of the ionization potential of superheavy element 117, the heaviest homologue of astatine. PMID:23673620

  18. Coumarins as new matrices for matrix-assisted laser-desorption/ionization Fourier transform ion cyclotron resonance mass spectrometric analysis of hydrophobic compounds

    Energy Technology Data Exchange (ETDEWEB)

    Wang, Hang, E-mail: hangwang@sjtu.edu.cn [Instrumental Analysis Center, Shanghai Jiao Tong University, Dongchuan Road 800, Shanghai 200240 (China); Dai, Bona [Instrumental Analysis Center, Shanghai Jiao Tong University, Dongchuan Road 800, Shanghai 200240 (China); Liu, Bin [Key Laboratory of Kidney Disease Pathogenesis and Intervention of Hubei Province, College of Medicine, Hubei Polytechnic University, Huangshi, Hubei 435003 (China); Lu, Han [Department of Anesthesiology, Ruijin Hospital, Shanghai Jiao Tong University School of Medicine (SJTU-SM), 197, Rui Jin Er Road, Shanghai 200025 (China)

    2015-07-02

    Highlights: • Coumarins were used as new MALDI matrices. • Coumarins were used for MALDI-FT ICR MS detection of hydrophobic compounds. • DCA had improvement in detection sensitivity, stability, selectivity and reproducibility. • DCA was applied to sterols detection in yeast cells. - Abstract: Hydrophobic compounds with hydroxyl, aldehyde or ketone groups are generally difficult to detect using matrix-assisted laser desorption/ionization mass spectrometry (MALDI-MS), because these compounds have low proton affinity and are poorly ionized by MALDI. Herein, coumarins have been used as new matrices for MALDI-MS analysis of a variety of hydrophobic compounds with low ionization efficiency, including steroids, coenzyme Q10, a cyclic lipopeptide and cholesterol oleate. Five coumarins, including coumarin, umbelliferone, esculetin, 7-hydroxycoumarin-3-carboxylic acid (HCA) and 6,7-dihydroxycoumarin-3-carboxylic acid (DCA), were compared with the conventional matrices of 2,5-dihydroxybenzoic acid (DHB) and α-cyano-4-hydroxycinnamic acid (CHCA). Coumarins with hydroxyl or carboxylic acid groups enabled detection. Taking DCA as an example, this matrix proved to be superior to DHB or CHCA in detection sensitivity, stability, spot-to-spot and sample-to-sample reproducibility, and accuracy. DCA increased the stability of the target compounds and decreased the loss of water. The [M + Na]{sup +} peaks were observed for all target compounds by adding NaCl as an additive, and the [M − H{sub 2}O + H]{sup +} and [M + H]{sup +} peaks decreased. DCA was selected for the identification of sterols in yeast cells, and thirteen sterols were detected by Fourier transform ion cyclotron resonance (FT ICR) mass spectrometry. This work demonstrates the potential of DCA as a new matrix for detection of hydrophobic molecules by MALDI-MS and provides an alternative tool for screening sterols in antifungal research.

  19. The ionization mechanisms in direct and dopant-assisted atmospheric pressure photoionization and atmospheric pressure laser ionization.

    Science.gov (United States)

    Kauppila, Tiina J; Kersten, Hendrik; Benter, Thorsten

    2014-11-01

    A novel, gas-tight API interface for gas chromatography-mass spectrometry was used to study the ionization mechanism in direct and dopant-assisted atmospheric pressure photoionization (APPI) and atmospheric pressure laser ionization (APLI). Eight analytes (ethylbenzene, bromobenzene, naphthalene, anthracene, benzaldehyde, pyridine, quinolone, and acridine) with varying ionization energies (IEs) and proton affinities (PAs), and four common APPI dopants (toluene, acetone, anisole, and chlorobenzene) were chosen. All the studied compounds were ionized by direct APPI, forming mainly molecular ions. Addition of dopants suppressed the signal of the analytes with IEs above the IE of the dopant. For compounds with suitable IEs or Pas, the dopants increased the ionization efficiency as the analytes could be ionized through dopant-mediated gas-phase reactions, such as charge exchange, proton transfer, and other rather unexpected reactions, such as formation of [M + 77](+) in the presence of chlorobenzene. Experiments with deuterated toluene as the dopant verified that in case of proton transfer, the proton originated from the dopant instead of proton-bound solvent clusters, as in conventional open or non-tight APPI sources. In direct APLI using a 266 nm laser, a narrower range of compounds was ionized than in direct APPI, because of exceedingly high IEs or unfavorable two-photon absorption cross-sections. Introduction of dopants in the APLI system changed the ionization mechanism to similar dopant-mediated gas-phase reactions with the dopant as in APPI, which produced mainly ions of the same form as in APPI, and ionized a wider range of analytes than direct APLI.

  20. Excitation mechanisms in singly ionized krypton laser

    International Nuclear Information System (INIS)

    El-Sherbini, Th.M.

    1982-01-01

    Lifetimes for the low lying 4p 4 4d and 4p 4 5s levels of singly ionized krypton laser are calculated, taking into account configuration interaction effects. The results show that some of these levels are metastable. They also suggest a two step excitation from the ground state of the ion (or the atom) to the upper 4p 4 5p laser levels involving some intermediate metastable states as a possible excitation mechanism. (author)

  1. Narrow linewidth operation of the RILIS titanium: Sapphire laser at ISOLDE/CERN

    CERN Document Server

    Rothe, S; Wendt, K D A; Fedosseev, V N; Kron, T; Marsh, B A

    2013-01-01

    A narrow linewidth operating mode for the Ti:sapphire laser of the CERN ISOLDE Resonance Ionization Laser Ion Source (RILIS) has been developed. This satisfies the laser requirements for the programme of in-source resonance ionization spectroscopy measurements and improves the selectivity for isomer separation using RILIS. A linewidth reduction from typically 10 GHz down to 1 GHz was achieved by the intra-cavity insertion of a second (thick) Fabry-Perot etalon. Reliable operation during a laser scan was achieved through motorized control of the tilt angle of each etalon. A scanning, stabilization and mode cleaning procedure was developed and implemented in LabVIEW. The narrow linewidth operation was confirmed in a high resolution spectroscopy study of francium isotopes by the Collinear Resonance Ionization Spectroscopy experiment. The resulting laser scans demonstrate the suitability of the laser, in terms of linewidth, spectral purity and stability for high resolution in-source spectroscopy and isomer select...

  2. Laser magnetic resonance spectroscopy

    International Nuclear Information System (INIS)

    Ferrari, C.A.

    1985-01-01

    The technique of laser resonance magnetic resonance allows one to study the high-resolution spectroscopy of transient paramagnetic species, viz, atoms, radicals, and molecular ions. This article is a brief exposition of the method, describing the principles, instrumentation and applicability of the IR and FIR-LMR and shows results of HF + . (Author) [pt

  3. Determination of the first ionization potential of actinides by resonance ionization mass spectroscopy

    International Nuclear Information System (INIS)

    Koehler, S.; Albus, F.; Dibenberger, R.; Erdmann, N.; Funk, H.; Hasse, H.; Herrmann, G.; Huber, G.; Kluge, H.; Nunnemann, M.; Passler, G.; Rao, P.M.; Riegel, J.; Trautmann, N.; Urban, F.

    1995-01-01

    Resonance ionization mass spectroscopy (RIMS) is used for the precise determination of the first ionization potential of transuranium elements. The first ionization potentials (IP) of americium and curium have been measured for the first time to IP Am =5.9738(2) and IP Cm =5.9913(8) eV, respectively, using only 10 12 atoms of 243 Am and 248 Cm. The same technique was applied to thorium, neptunium, and plutonium yielding IP T H =6.3067(2), IP N P =6.2655(2), and IP Pu =6.0257(8) eV. The good agreement of our results with the literature data proves the precision of the method which was additionally confirmed by the analysis of Rydberg seris of americium measured by RIMS. copyright American Institute of Physics 1995

  4. Monolithic optofluidic ring resonator lasers created by femtosecond laser nanofabrication.

    Science.gov (United States)

    Chandrahalim, Hengky; Chen, Qiushu; Said, Ali A; Dugan, Mark; Fan, Xudong

    2015-05-21

    We designed, fabricated, and characterized a monolithically integrated optofluidic ring resonator laser that is mechanically, thermally, and chemically robust. The entire device, including the ring resonator channel and sample delivery microfluidics, was created in a block of fused-silica glass using a 3-dimensional femtosecond laser writing process. The gain medium, composed of Rhodamine 6G (R6G) dissolved in quinoline, was flowed through the ring resonator. Lasing was achieved at a pump threshold of approximately 15 μJ mm(-2). Detailed analysis shows that the Q-factor of the optofluidic ring resonator is 3.3 × 10(4), which is limited by both solvent absorption and scattering loss. In particular, a Q-factor resulting from the scattering loss can be as high as 4.2 × 10(4), suggesting the feasibility of using a femtosecond laser to create high quality optical cavities.

  5. Resonance enhanced laser mass spectrometry for process- and environmental-analysis: Applications and perspectives

    International Nuclear Information System (INIS)

    Zimmermann, Ralf; Dorfner, Ralph; Kettrup, Antonius; Heger, Hans Joerg; Boesl, Ulrich

    1998-01-01

    Laser induced Resonance-Enhanced Multi-Photon Ionization Time-Of-Flight Mass Spectrometry (REMPI TOFMS) is a highly selective as well as sensitive analytical technique, well suited for species selective, on-line monitoring of trace-substances. In this contribution some analytical applications of a mobile REMPI-TOFMS are presented. This includes REMPI-TOMS on-line analysis of coffee roasting gas and waste incineration flue gas as well as headspace measurements of pulp processing lye or rapid analysis of polycyclic aromatic hydrocarbons from soil samples via thermal desorption

  6. Multivariate correction in laser-enhanced ionization with laser sampling

    International Nuclear Information System (INIS)

    Popov, A.M.; Labutin, T.A.; Sychev, D.N.; Gorbatenko, A.A.; Zorov, N.B.

    2007-01-01

    The opportunity of normalizing laser-enhanced ionization (LEI) signals by several reference signals (RS) measured simultaneously has been examined in view of correcting variations of laser parameters and matrix interferences. Opto-acoustic, atomic emission and non-selective ionization signals and their paired combination were used as RS for Li determination in aluminum alloys (0-6% Mg, 0-5% Cu, 0-1% Sc, 0-1% Ag). The specific normalization procedure in case of RS essential multicollinearity has been proposed. LEI and RS for each definite ablation pulse energy were plotted in Cartesian co-ordinates (x and y axes - the RS values, z axis - LEI signal). It was found that in the three-dimensional space the slope of the correlation line to the plane of RS depends on the analyte content in the solid sample. The use of this slope has therefore been proposed as a multivariate corrected analytical signal. Multivariate correlative normalization provides analytical signal free of matrix interferences for Al-Mg-Cu-Li alloys. The application of this novel approach to the determination of Li allows plotting unified calibration curves for Al-alloys of different matrix composition

  7. Multivariate correction in laser-enhanced ionization with laser sampling

    Energy Technology Data Exchange (ETDEWEB)

    Popov, A.M. [Department of Chemistry, M. V. Lomonosov Moscow State University, 119992 Russia Moscow GSP-2, Leninskie Gory 1 build.3 (Russian Federation); Labutin, T.A. [Department of Chemistry, M. V. Lomonosov Moscow State University, 119992 Russia Moscow GSP-2, Leninskie Gory 1 build.3 (Russian Federation)], E-mail: timurla@laser.chem.msu.ru; Sychev, D.N.; Gorbatenko, A.A.; Zorov, N.B. [Department of Chemistry, M. V. Lomonosov Moscow State University, 119992 Russia Moscow GSP-2, Leninskie Gory 1 build.3 (Russian Federation)

    2007-03-15

    The opportunity of normalizing laser-enhanced ionization (LEI) signals by several reference signals (RS) measured simultaneously has been examined in view of correcting variations of laser parameters and matrix interferences. Opto-acoustic, atomic emission and non-selective ionization signals and their paired combination were used as RS for Li determination in aluminum alloys (0-6% Mg, 0-5% Cu, 0-1% Sc, 0-1% Ag). The specific normalization procedure in case of RS essential multicollinearity has been proposed. LEI and RS for each definite ablation pulse energy were plotted in Cartesian co-ordinates (x and y axes - the RS values, z axis - LEI signal). It was found that in the three-dimensional space the slope of the correlation line to the plane of RS depends on the analyte content in the solid sample. The use of this slope has therefore been proposed as a multivariate corrected analytical signal. Multivariate correlative normalization provides analytical signal free of matrix interferences for Al-Mg-Cu-Li alloys. The application of this novel approach to the determination of Li allows plotting unified calibration curves for Al-alloys of different matrix composition.

  8. Theoretical investigation of dielectric corona pre-ionization TEA nitrogen laser based on transmission line method

    Science.gov (United States)

    Bahrampour, Alireza; Fallah, Robabeh; Ganjovi, Alireza A.; Bahrampour, Abolfazl

    2007-07-01

    This paper models the dielectric corona pre-ionization, capacitor transfer type of flat-plane transmission line traveling wave transverse excited atmospheric pressure nitrogen laser by a non-linear lumped RLC electric circuit. The flat-plane transmission line and the pre-ionizer dielectric are modeled by a lumped linear RLC and time-dependent non-linear RC circuit, respectively. The main discharge region is considered as a time-dependent non-linear RLC circuit where its resistance value is also depends on the radiated pre-ionization ultra violet (UV) intensity. The UV radiation is radiated by the resistance due to the surface plasma on the pre-ionizer dielectric. The theoretical predictions are in a very good agreement with the experimental observations. The electric circuit equations (including the ionization rate equations), the equations of laser levels population densities and propagation equation of laser intensities, are solved numerically. As a result, the effects of pre-ionizer dielectric parameters on the electrical behavior and output laser intensity are obtained.

  9. Novel two-step laser ablation and ionization mass spectrometry (2S-LAIMS) of actor-spectator ice layers: Probing chemical composition of D{sub 2}O ice beneath a H{sub 2}O ice layer

    Energy Technology Data Exchange (ETDEWEB)

    Yang, Rui, E-mail: ryang73@ustc.edu; Gudipati, Murthy S., E-mail: gudipati@jpl.nasa.gov [Science Division, Jet Propulsion Laboratory, California Institute of Technology, Mail Stop 183-301, 4800 Oak Grove Drive, Pasadena, California 91109 (United States)

    2014-03-14

    In this work, we report for the first time successful analysis of organic aromatic analytes imbedded in D{sub 2}O ices by novel infrared (IR) laser ablation of a layered non-absorbing D{sub 2}O ice (spectator) containing the analytes and an ablation-active IR-absorbing H{sub 2}O ice layer (actor) without the analyte. With these studies we have opened up a new method for the in situ analysis of solids containing analytes when covered with an IR laser-absorbing layer that can be resonantly ablated. This soft ejection method takes advantage of the tenability of two-step infrared laser ablation and ultraviolet laser ionization mass spectrometry, previously demonstrated in this lab to study chemical reactions of polycyclic aromatic hydrocarbons (PAHs) in cryogenic ices. The IR laser pulse tuned to resonantly excite only the upper H{sub 2}O ice layer (actor) generates a shockwave upon impact. This shockwave penetrates the lower analyte-containing D{sub 2}O ice layer (spectator, a non-absorbing ice that cannot be ablated directly with the wavelength of the IR laser employed) and is reflected back, ejecting the contents of the D{sub 2}O layer into the vacuum where they are intersected by a UV laser for ionization and detection by a time-of-flight mass spectrometer. Thus, energy is transmitted from the laser-absorbing actor layer into the non-absorbing spectator layer resulting its ablation. We found that isotope cross-contamination between layers was negligible. We also did not see any evidence for thermal or collisional chemistry of PAH molecules with H{sub 2}O molecules in the shockwave. We call this “shockwave mediated surface resonance enhanced subsurface ablation” technique as “two-step laser ablation and ionization mass spectrometry of actor-spectator ice layers.” This method has its roots in the well-established MALDI (matrix assisted laser desorption and ionization) method. Our method offers more flexibility to optimize both the processes—ablation and

  10. Self-focusing and guiding of short laser pulses in ionizing gases and plasmas

    International Nuclear Information System (INIS)

    Esarey, E.; Sprangle, P.; Krall, J.; Ting, A.

    1997-01-01

    The propagation of intense laser pulses in gases and plasmas is relevant to a wide range of applications, including laser-driven accelerators, laser-plasma channeling, harmonic generation, supercontinuum generation, X-ray lasers, and laser-fusion schemes. Here, several features of intense, short-pulse (≤1 ps) laser propagation in gases undergoing ionization and in plasmas are reviewed, discussed, and analyzed. The wave equations for laser pulse propagation in a gas undergoing ionization and in a plasma are derived. The source-dependent expansion method is discussed, which is a general method for solving the paraxial wave equation with nonlinear source terms. In gases, the propagation of high-power (near the critical power) laser pulses is considered including the effects of diffraction, nonlinear self-focusing, ionization, and plasma generation. Self-guided solutions and the stability of these solutions are discussed. In plasmas, optical guiding by relativistic effects, ponderomotive effects, and preformed density channels is considered. The self-consistent plasma response is discussed, including plasma wave effects and instabilities such as self-modulation. Recent experiments on the guiding of laser pulses in gases and in plasmas are briefly summarized

  11. Development of laser excited atomic fluorescence and ionization methods

    International Nuclear Information System (INIS)

    Winefordner, J.D.

    1991-01-01

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

  12. Corona discharge secondary ionization of laser desorbed neutral molecules from a liquid matrix at atmospheric pressure

    Energy Technology Data Exchange (ETDEWEB)

    Turney, Kevin [Department of Chemistry, University of Florida, Gainesville, Florida 32611 (United States); Harrison, W.W. [Department of Chemistry, University of Florida, Gainesville, Florida 32611 (United States)]. E-mail: harrison@chem.ufl.edu

    2006-06-15

    Matrix assisted laser desorption/ionization (MALDI) is studied at atmospheric pressure using liquid sampling methods. A time-of-flight mass spectrometer couples to an open sample stage accessed by a UV laser for desorption and ionization. Also coupled to the sampling state is a corona discharge for auxiliary ionization of desorbed neutral molecules. The interaction of the laser desorption and corona ionization is studied for a range of desorption conditions, showing enhanced analyte ionization, but the effect is analytically advantageous only at low desorption rates. The effect of corona discharge voltage was also explored. The decoupling of neutral molecule formation and subsequent ionization provides an opportunity to study each process separately.

  13. Corona discharge secondary ionization of laser desorbed neutral molecules from a liquid matrix at atmospheric pressure

    International Nuclear Information System (INIS)

    Turney, Kevin; Harrison, W.W.

    2006-01-01

    Matrix assisted laser desorption/ionization (MALDI) is studied at atmospheric pressure using liquid sampling methods. A time-of-flight mass spectrometer couples to an open sample stage accessed by a UV laser for desorption and ionization. Also coupled to the sampling state is a corona discharge for auxiliary ionization of desorbed neutral molecules. The interaction of the laser desorption and corona ionization is studied for a range of desorption conditions, showing enhanced analyte ionization, but the effect is analytically advantageous only at low desorption rates. The effect of corona discharge voltage was also explored. The decoupling of neutral molecule formation and subsequent ionization provides an opportunity to study each process separately

  14. Analysis of sample composition using resonant ionization and time-of-flight techniques; Analisis de composicion de muestras mediante ionizacion resonante y tecnicas de tiempo de vuelo

    Energy Technology Data Exchange (ETDEWEB)

    Cruz, A de la; Ortiz, M; Campos, J

    1995-07-01

    This paper describes the setting up of a linear time-of-flight mass spectrometer that uses a tunable laser to produce resonant ionization of atoms and molecules in a pulsed supersonic beam. The ability of this kind of systems to produce time resolved signals for each species present in the sample allows quantitative analysis of its composition. By using a tunable laser beam of high spectral resolution to produce ionization, studies based on the structure of the photoionization spectra obtained are possible. In the present work several isotopic species of ordinary and deuterated benzene have been studied. Special care has been dedicated to the influence of the presence of a 13C in the ring. In this way values for spectroscopic constants and isotopic shifts have been obtained. Another system based in a homemade proportional counter has been designed and used is an auxiliary system. The results obtained with it are independent of these mentioned above and compatible with them. This system is of great utility for laser wavelength tuning to produce ionization in the mass spectrometer. (Author) 98 refs.

  15. Lasers probe the atomic nucleus

    International Nuclear Information System (INIS)

    Eastham, D.

    1986-01-01

    The article is contained in a booklet on the Revised Nuffield Advanced Physics Course, and concentrates on two techniques to illustrate how lasers probe the atomic nucleus. Both techniques employ resonance fluorescence spectroscopy for obtaining atomic transition energies. The first uses lasers to determine the change in the nuclear charge radius with isotope, the second concerns the use of lasers for ultrasensitive detection of isotopes and elements. The application of lasers in resonance ionization spectroscopy and proton decay is also described. (UK)

  16. Multiphoton ionization/dissociation of osmium tetroxide

    International Nuclear Information System (INIS)

    Ding, D.; Puretzky, A.A.; Compton, R.N.

    1993-01-01

    The mechanisms leading to laser multiphoton ionization and dissociation (MPI/MPD) of osmium tetroxide (OsO 4 ) have been investigated from measurements of the kinetic energies of product ions (Os + , Os 2+ , OsO + , O 2 + , O + ) and photoelectrons as a function of the laser wavelength. Neutral channels, intermediate to the dominant Os + ionization channel, such as OsO 4 →OsO 4-n +nO are examined using resonance-enhanced multiphoton ionization (REMPI) of the fast O atoms. Equipartition of the available photon energy among the fragments is observed. The wavelength dependence of the Os + ion signal suggests that one or more of the steps leading to Os + ions involve molecular ions and/or excited neutral atoms. The observed preponderance of very slow ( 2+ is shown to result primarily from REMPI of Os +

  17. Thin films deposited by laser ablation for the measurement of the ionizing and non-ionizing radiation

    International Nuclear Information System (INIS)

    Villarreal B, J.E.; Escobar A, L.; Camps, E.; Romero, S.; Gonzalez, P.; Salinas, B.

    2001-01-01

    In this work the obtained results to synthesize thin films of amorphous carbon with incorporated nitrogen and hydrogen are presented, as well as thin films of aluminium oxide using the laser ablation technique. The thin films were exposed to ionizing radiation (gamma rays of a 60 Co source, beta radiation of a 90 Sr source) and a non-ionizing radiation (UV radiation). The obtained results show that it is possible to obtain materials in thin film form with thickness of hundreds of nanometers, which present thermoluminescent response when being irradiated with ionizing radiation and non-ionizing radiation. (Author)

  18. Use of a radio-frequency resonance circuit in studies of alkali ionization in flames

    International Nuclear Information System (INIS)

    Borgers, A.J.

    1978-01-01

    The construction of a radio-frequency resonance system and its use in the study of alkali metal ionization in flames is described. The author re-determines the values of the alkali ionization rate constants for a CO flame with N 2 as diluent gas of known temperature using the RF resonance method. (Auth.)

  19. Chemical analysis of surfaces by resonance ionization mass spectroscopy associated to ionic pulverization; Analyse chimique de surfaces par spectrometrie d`ionisation resonante associee a la pulverisation ionique

    Energy Technology Data Exchange (ETDEWEB)

    Kern, P

    1995-12-19

    This work shows that if resonance ionization mass spectroscopy was first applied in isotopic separation, it`s also an analyzing method adapted to the study of semi-conductor materials and thin foils. We have improved this technic: a neodymium laser coupled with a dye laser, a new argon ions gun, a gallium ions gun and a new collection optic for the secondary ions quadrupole spectrometer to allow quantitative and selective measurements. (S.G.). 84 refs.

  20. Surface-assisted laser desorption ionization mass spectrometry techniques for application in forensics.

    Science.gov (United States)

    Guinan, Taryn; Kirkbride, Paul; Pigou, Paul E; Ronci, Maurizio; Kobus, Hilton; Voelcker, Nicolas H

    2015-01-01

    Matrix-assisted laser desorption ionization (MALDI) mass spectrometry (MS) is an excellent analytical technique for the rapid and sensitive analysis of macromolecules (>700 Da), such as peptides, proteins, nucleic acids, and synthetic polymers. However, the detection of smaller organic molecules with masses below 700 Da using MALDI-MS is challenging due to the appearance of matrix adducts and matrix fragment peaks in the same spectral range. Recently, nanostructured substrates have been developed that facilitate matrix-free laser desorption ionization (LDI), contributing to an emerging analytical paradigm referred to as surface-assisted laser desorption ionization (SALDI) MS. Since SALDI enables the detection of small organic molecules, it is rapidly growing in popularity, including in the field of forensics. At the same time, SALDI also holds significant potential as a high throughput analytical tool in roadside, work place and athlete drug testing. In this review, we discuss recent advances in SALDI techniques such as desorption ionization on porous silicon (DIOS), nano-initiator mass spectrometry (NIMS) and nano assisted laser desorption ionization (NALDI™) and compare their strengths and weaknesses with particular focus on forensic applications. These include the detection of illicit drug molecules and their metabolites in biological matrices and small molecule detection from forensic samples including banknotes and fingerprints. Finally, the review highlights recent advances in mass spectrometry imaging (MSI) using SALDI techniques. © 2014 Wiley Periodicals, Inc.

  1. Determination of ultra-low levels of uranium using resonance ionization mass spectrometry

    International Nuclear Information System (INIS)

    Kiran Kumar, P.V.; Acharyulu, G.V.S.G.

    2015-01-01

    The determination of isotopic composition of actinides like U and Pu is important, due to their distribution in the environment as a result of nuclear weapons testing, fuel reprocessing, reactor operations and to a smaller extent from accidental releases. The analytical methods like fission track analysis (FTA), thermal ionization mass spectrometry (TIMS), inductively coupled plasma mass spectrometry (ICPMS) and resonance ionization mass spectrometry (RIMS) have evolved as sensitive techniques. Resonance Ionization Mass Spectrometry yields rapid isotopic signature data for material containing actinides without requiring time-consuming sample preparation and chemical separation procedures. In this paper, authors presented the details of the methodology and results for low-level detection of uranium using RIMS

  2. Laser desorption/ionization from nanostructured surfaces: nanowires, nanoparticle films and silicon microcolumn arrays

    International Nuclear Information System (INIS)

    Chen Yong; Luo Guanghong; Diao Jiajie; Chornoguz, Olesya; Reeves, Mark; Vertes, Akos

    2007-01-01

    Due to their optical properties and morphology, thin films formed of nanoparticles are potentially new platforms for soft laser desorption/ionization (SLDI) mass spectrometry. Thin films of gold nanoparticles (with 12±1 nm particle size) were prepared by evaporation-driven vertical colloidal deposition and used to analyze a series of directly deposited polypeptide samples. In this new SLDI method, the required laser fluence for ion detection was equal or less than what was needed for matrix-assisted laser desorption/ionization (MALDI) but the resulting spectra were free of matrix interferences. A silicon microcolumn array-based substrate (a.k.a. black silicon) was developed as a new matrix-free laser desorption ionization surface. When low-resistivity silicon wafers were processed with a 22 ps pulse length 3xω Nd:YAG laser in air, SF 6 or water environment, regularly arranged conical spikes emerged. The radii of the spike tips varied with the processing environment, ranging from approximately 500 nm in water, to ∼2 μm in SF 6 gas and to ∼5 μm in air. Peptide mass spectra directly induced by a nitrogen laser showed the formation of protonated ions of angiotensin I and II, substance P, bradykinin fragment 1-7, synthetic peptide, pro14-arg, and insulin from the processed silicon surfaces but not from the unprocessed areas. Threshold fluences for desorption/ionization were similar to those used in MALDI. Although compared to silicon nanowires the threshold laser pulse energy for ionization is significantly (∼10x) higher, the ease of production and robustness of microcolumn arrays offer complementary benefits

  3. Photoionization pathways and thresholds in generation of Lyman-α radiation by resonant four-wave mixing in Kr-Ar mixture

    OpenAIRE

    Oleg A. Louchev; Norihito Saito; Yu Oishi; Koji Miyazaki; Kotaro Okamura; Jumpei Nakamura; Masahiko Iwasaki; Satoshi Wada

    2016-01-01

    We develop a set of analytical approximations for the estimation of the combined effect of various photoionization processes involved in the resonant four-wave mixing generation of ns pulsed Lyman-α (L-α) radiation by using 212.556 nm and 820-845 nm laser radiation pulses in Kr-Ar mixture: (i) multi-photon ionization, (ii) step-wise (2+1)-photon ionization via the resonant 2-photon excitation of Kr followed by 1-photon ionization and (iii) laser-induced avalanche ionization produced by genera...

  4. In-Source Laser Spectroscopy with the Laser Ion Source and Trap: First Direct Study of the Ground-State Properties of ^{217,219}Po

    Directory of Open Access Journals (Sweden)

    D. A. Fink

    2015-02-01

    Full Text Available A Laser Ion Source and Trap (LIST for a thick-target, isotope-separation on-line facility has been implemented at CERN ISOLDE for the production of pure, laser-ionized, radioactive ion beams. It offers two modes of operation, either as an ion guide, which performs similarly to the standard ISOLDE resonance ionization laser ion source (RILIS, or as a more selective ion source, where surface-ionized ions from the hot ion-source cavity are repelled by an electrode, while laser ionization is done within a radio-frequency quadrupole ion guide. The first physics application of the LIST enables the suppression of francium contamination in ion beams of neutron-rich polonium isotopes at ISOLDE by more than 1000 with a reduction in laser-ionization efficiency of only 20. Resonance ionization spectroscopy is performed directly inside the LIST device, allowing the study of the hyperfine structure and isotope shift of ^{217}Po for the first time. Nuclear decay spectroscopy of ^{219}Po is performed for the first time, revealing its half-life, α-to-β-decay branching ratio, and α-particle energy. This experiment demonstrates the applicability of the LIST at radioactive ion-beam facilities for the production and study of pure beams of exotic isotopes.

  5. Time delay between singly and doubly ionizing wavepackets in laser-driven helium

    International Nuclear Information System (INIS)

    Parker, J S; Doherty, B J S; Meharg, K J; Taylor, K T

    2003-01-01

    We present calculations of the time delay between single and double ionization of helium, obtained from full-dimensionality numerical integrations of the helium-laser Schroedinger equation. The notion of a quantum mechanical time delay is defined in terms of the interval between correlated bursts of single and double ionization. Calculations are performed at 390 and 780 nm in laser intensities that range from 2 x 10 14 to 14 x 10 14 Wcm -2 . We find results consistent with the rescattering model of double ionization but supporting its classical interpretation only at 780 nm. (letter to the editor)

  6. Multiphoton ionization of atomic cesium

    International Nuclear Information System (INIS)

    Compton, R.N.; Klots, C.E.; Stockdale, J.A.D.; Cooper, C.D.

    1984-01-01

    We describe experimental studies of resonantly enhanced multiphoton ionization (MPI) of cesium atoms in the presence and absence of an external electric field. In the zero-field studies, photoelectron angular distributions for one- and two-photon resonantly enhanced MPI are compared with the theory of Tang and Lambropoulos. Deviations of experiment from theory are attributed to hyperfine coupling effects in the resonant intermediate state. The agreement between theory and experiment is excellent. In the absence of an external electric field, signal due to two-photon resonant three-photon ionization of cesium via np states is undetectable. Application of an electric field mixes nearby nd and ns levels, thereby inducing excitation and subsequent ionization. Signal due to two-photon excitation of ns levels in field-free experiments is weak due to their small photoionization cross section. An electric field mixes nearby np levels which again allows detectable photoionization signal. For both ns and np states the field induced MPI signal increases as the square of the electric field for a given principal quantum number and increases rapidly with n for a given field strength. Finally, we note that the classical two-photon field-ionization threshold is lower for the case in which the laser polarization and the electric field are parallel than it is when they are perpendicular. 22 references, 11 figures

  7. Stimulated resonance Raman spectroscopy: An alternative to laser-rf double resonance for ion spectroscopy

    International Nuclear Information System (INIS)

    Young, L.; Dinneen, T.; Mansour, N.B.

    1988-01-01

    Stimulated resonance Raman spectroscopy is presented as an alternative to laser-rf double resonance for obtaining high-precision measurements in ion beams. By use of a single-phase modulated laser beam to derive the two required fields, the laser--ion-beam alignment is significantly simplified. In addition, this method is especially useful in the low-frequency regime where the laser-rf double-resonance method encounters difficulties due to modifications of the ion-beam velocity distribution. These modifications, which result from interaction with the traveling rf wave used to induce magnetic dipole transitions, are observed and quantitatively modeled

  8. Comparative study of the dissociative ionization of 1,1,1-trichloroethane using nanosecond and femtosecond laser pulses

    CSIR Research Space (South Africa)

    Du Plessis, A

    2010-03-01

    Full Text Available , but different fragmentation patterns. A general trend is that when using femtosecond laser pulses for ionization, the parent molecular ion is observed but not for nanosecond laser ionization. There is also a fundamental interest in laser...-molecule interactions at the high intensities available from femtosecond lasers [12,13]. These papers describe the multiphoton ionization mechanisms termed ladder climbing and ladder switching, which explain the presence of parent molecular ion in ultrashort pulse...

  9. Fundamental studies of molecular multiphoton ionization

    International Nuclear Information System (INIS)

    Miller, J.C.; Compton, R.N.

    1984-04-01

    For several years the authors have performed fundamental studies of molecular multiphoton ionization (MPI). We will present a potpourri of techniques and results chosen to illustrate the interesting complexities of molecular MPI. Techniques used include time-of-flight mass spectroscopy, photoelectron spectroscopy, supersonic expansion cooling of molecular beams, harmonic generation, two-color laser MPI, and polarization spectroscopy. Whenever possible the relevance of these results to resonance ionization spectroscopy schemes will be delineated. 23 references, 10 figures

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

    International Nuclear Information System (INIS)

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

    2015-01-01

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

  11. Ultra-low emittance beam generation using two-color ionization injection in a CO2 laser-driven plasma accelerator

    International Nuclear Information System (INIS)

    Schroeder, Carl; Benedetti, Carlo; Bulanov, Stepan; Chen, Min; Esarey, Eric; Geddes, Cameron; Vay, J.; Yu, Lule; Leemans, Wim

    2015-01-01

    Ultra-low emittance (tens of nm) beams can be generated in a plasma accelerator using ionization injection of electrons into a wakefield. An all-optical method of beam generation uses two laser pulses of different colors. A long-wavelength drive laser pulse (with a large ponderomotive force and small peak electric field) is used to excite a large wakefield without fully ionizing a gas, and a short-wavelength injection laser pulse (with a small ponderomotive force and large peak electric field), co-propagating and delayed with respect to the pump laser, to ionize a fraction of the remaining bound electrons at a trapped wake phase, generating an electron beam that is accelerated in the wake. The trapping condition, the ionized electron distribution, and the trapped bunch dynamics are discussed. Expressions for the beam transverse emittance, parallel and orthogonal to the ionization laser polarization, are presented. An example is shown using a 10-micron CO 2 laser to drive the wake and a frequency-doubled Ti:Al 2 O 3 laser for ionization injection.

  12. Intensity dependence of nonsequential double ionization of helium in IR+XUV two-color laser fields

    International Nuclear Information System (INIS)

    Jin, Facheng; Wang, Bingbing; Chen, Jing; Yang, Yujun; Yan, Zong-Chao

    2016-01-01

    By applying the frequency-domain theory, we investigate the dependence of momentum spectra on laser intensity in a nonsequential double ionization (NSDI) process of helium in infrared (IR) and extreme ultraviolet (XUV) two-color laser fields. We find that the two-color laser fields play distinct roles in an NSDI process, where the IR laser field mainly determines the width of each band, and the XUV laser field mainly plays a role on the NSDI probability. Furthermore, an NSDI process can be decoupled into a two-step process: an above-threshold ionization (ATI), followed by a laser-assisted collision (LAC). It is found that, the IR laser field is responsible for broadening the peak in the ATI process and providing additional momenta to the two ionized electrons in the LAC process; while the XUV laser field plays a crucial role on the strength of the spectrum in the ATI process, and influences the radii of orbits in momentum space in the LAC process. (paper)

  13. Multi-photon resonant effects in strong-field ionization: origin of the dip in experimental longitudinal momentum distributions

    International Nuclear Information System (INIS)

    Alnaser, A S; Maharjan, C M; Wang, P; Litvinyuk, I V

    2006-01-01

    We studied ionization of neon and argon by intense linearly polarized femtosecond laser pulses of different wavelengths (400 nm and 800 nm) and peak intensities, and by measuring momentum distributions of singly charged positive ions in the direction parallel to laser polarization. For Ne the momentum distributions exhibited a characteristic dip at zero momentum at 800 nm and a complex multipeak structure at 400 nm. Similarly, for Ar the momentum distributions evolved from a complex multipeak structure with a pronounced dip in the centre at 400 nm, to a smooth distribution characteristic of pure tunneling ionization (800 nm, high intensities). In the intermediate regime (800 nm, medium to low intensities), for both atoms we observed recoil ion momentum distributions modulated by quasi-periodic structures usually seen in the photoelectron energy spectra in a multi-photon regime (ATI spectra). Ne did show a characteristic 'dip' at low momentum, while the longitudinal momentum distribution for Ar exhibited a spike at zero momentum instead. The spectra did dramatically change at 400 nm, where both ions show the pronounced dip near zero momentum. Based on our results, we conclude that the structures observed in Ne and Ar momentum distributions reflect the specifics of atomic structure of the two targets and should not be attributed to effects of electron recollision, as was suggested earlier. Instead, as our results indicate, they are due to the effects of multi-photon resonant enhancement of strong-field ionization. (letter to the editor)

  14. Ghost peaks observed after atmospheric pressure matrix-assisted laser desorption/ionization experiments may disclose new ionization mechanism of matrix-assisted hypersonic velocity impact ionization.

    Science.gov (United States)

    Moskovets, Eugene

    2015-08-30

    Understanding the mechanisms of matrix-assisted laser desorption/ionization (MALDI) promises improvements in the sensitivity and specificity of many established applications in the field of mass spectrometry. This paper reports a serendipitous observation of a significant ion yield in a post-ionization experiment conducted after the sample had been removed from a standard atmospheric pressure (AP)-MALDI source. This post-ionization is interpreted in terms of collisions of microparticles moving with a hypersonic velocity into a solid surface. Calculations show that the thermal energy released during such collisions is close to that absorbed by the top matrix layer in traditional MALDI. The microparticles, containing both the matrix and analytes, could be detached from a film produced inside the inlet capillary during the sample ablation and accelerated by the flow rushing through the capillary. These observations contribute some new perspective to ion formation in both laser and laser-less matrix-assisted ionization. An AP-MALDI ion source hyphenated with a three-stage high-pressure ion funnel system was utilized for peptide mass analysis. After the laser had been turned off and the MALDI sample removed, ions were detected during a gradual reduction of the background pressure in the first funnel. The constant-rate pressure reduction led to the reproducible appearance of different singly and doubly charged peptide peaks in mass spectra taken a few seconds after the end of the MALDI analysis of a dried-droplet spot. The ion yield as well as the mass range of ions observed with a significant delay after a completion of the primary MALDI analysis depended primarily on the background pressure inside the first funnel. The production of ions in this post-ionization step was exclusively observed during the pressure drop. A lower matrix background and significant increase in relative yield of double-protonated ions are reported. The observations were partially consistent

  15. Investigation on a TEA-CO II laser with surface corona pre-ionization

    Science.gov (United States)

    Behjat, A.; Aram, M.; Soltanmoradi, F.; Shabanzadeh, M.

    2006-05-01

    The construction of a surface corona UV pre-ionized TEA CO II laser is described and dependence of its average output energy of the laser to gas mixture, discharge voltage and repetition rate is investigated. The electric circuit diagram and geometry of the pre-ionization system are presented. Configuration of circuit has been designed to produce only impulsive voltage difference between the laser electrodes. Also, the triggering configuration of trigatron is prepared for fast operation to minimize the arc occurrence as much as possible. Some data of current, voltage, laser pulses and average output energy versus gas mixture and applied voltages are given. IR spectrometer is used for measurements of central output wavelength of the laser. Operation of the laser on two adjacent vibrational-rotational transitions of CO II molecule has been observed that shows the ability of this laser for working on multi-line in a same time for special applications.

  16. Double ionization of molecule H2 in intense ultrashort laser fields

    International Nuclear Information System (INIS)

    Le, Thu-Thuy; Nguyen, Ngoc-Ty

    2015-01-01

    By solving numerically the time-dependent Schrödinger equation (TDSE), we have calculated the double ionization probability when a vibrating hydrogen molecule interacts with intense ultrashort laser pulses. The results show that in the case of vibrating nuclei the double ionization probability is higher than that of the fixed nuclei. Additionally, the double ionization probability is larger if the molecule is vibrating in a higher level. This is due to the decreasing of ionization potential when the inter-nuclei separation increases. (paper)

  17. Multiphoton ionization of H+2 at critical internuclear separations: non-Hermitian Floquet analysis

    International Nuclear Information System (INIS)

    Likhatov, P V; Telnov, D A

    2009-01-01

    We present ab initio time-dependent non-Hermitian Floquet calculations of multiphoton ionization (MPI) rates of hydrogen molecular ions subject to an intense linearly polarized monochromatic laser field with a wavelength of 800 nm. The orientation of the molecular axis is parallel to the polarization vector of the laser field. The MPI rates are computed for a wide range of internuclear separations R with high resolution in R and reproduce resonance and near-threshold structures. We show that enhancement of ionization at critical internuclear separations is related to resonance series with higher electronic states. The effect of two-centre interference on the MPI signal is discussed.

  18. Progress on resonance ionization detection of combustion radicals

    International Nuclear Information System (INIS)

    Cool, T.A.

    1994-01-01

    Selective laser ionization techniques are used in our laboratory for the measurement of concentration profiles of radical intermediates in the combustion of chlorinated hydrocarbon flames. A new ultrasensitive detection technique, made possible with the advent of tunable VUV laser sources, enables the selective near-threshold photoionization of all radical intermediates in premixed hydrocarbon and chlorinated hydrocarbon flames. The progress made on the following three separate experiments during the past year is briefly described in this report. Flame Radical Concentration Measurements with VUV Spectroscopy; observation of hyperfine quantum beats in cyanogen; and the spectroscopy of the ClCO radical

  19. Trace determination of 90Sr and 89Sr in environmental samples by collinear resonance ionization spectroscopy

    International Nuclear Information System (INIS)

    Lantzsch, J.; Bushaw, B. A.; Bystrow, V. A.; Herrmann, G.; Kluge, H.-J.; Niess, S.; Otten, E. W.; Passler, G.; Schwalbach, R.; Schwarz, M.; Stenner, J.; Trautmann, N.; Wendt, K.; Yushkevich, Y. V.; Zimmer, K.

    1995-01-01

    Collinear resonance ionization spectroscopy has been developed as a sensitive technique for fast trace detection of 90 Sr and 89 Sr in the environment. A detection limit for 90 Sr of 10 7 atoms in the presence of 10 17 atoms in the presence of 10 17 atoms of stable Strontium has been achieved, while the applicability of the method has been demonstrated on real world samples. After collection and chemical separation, strontium is surface ionized, accelerated to 33keV and mass separated. The ions are neutralized and the emerging fast atoms interact with an argon ion laser beam (γ=364 nm) in a quasi-collinear geometry. Optical excitation starts from the long-lived 5s4d 3 D2 state of strontium, which is populated in the charge exchange process, and the fast atoms are selectively excited into the high-lying 5s23f 3 F3 Rydberg state. The Rydberg-atoms are subsequently field-ionized and detected by a channeltron detector after energy selection. The described method was successfully used to determine the 90 Sr-content in air samples collected near Munich during the Chernobyl reactor accident in April 1986

  20. Resonance ionization spectroscopy of argon, krypton, and xenon using vacuum ultraviolet light

    International Nuclear Information System (INIS)

    Kramer, S.D.

    1984-04-01

    Resonant, single-photon excitation of ground state inert gases requires light in the vacuum ultraviolet spectral region. This paper discusses methods for generating this light. Efficient schemes for ionizing argon, krypton, and xenon using resonant, stepwise single-photon excitation are presented

  1. Resonantly-enhanced two-photon ionization and mass-analyzed threshold ionization (MATI) spectroscopy of 2-hydroxypyridine

    CERN Document Server

    Lee, D H; Choi, K W; Choi, Y S; Kim, S K

    2002-01-01

    Mass-analyzed threshold ionization (MATI) spectra of 2-hydroxypyridines existing as lactims (2-pyridionl) in a molecular beam are obtained via (1+1') two-photon process to give accurate ionization energies of 8.9344 +- 0.0005 and 8.9284 +- 0.0005 eV for 2-pyridinol (2Py-OH) and its deuterated analogue (2Py-OD), respectively. Resonantly-enhanced two-photon ionization spectra of these compounds are also presented to give vibrational structures of their S sub 1 states. Vibrational frequencies of 2Py-OH and 2Py-OD in ionic ground states are accurately determined from MATI spectra taken via various S sub 1 intermediate states, and associated vibrational modes are assigned with the aid of ab initio calculations.

  2. Superthin resonator dye laser with THz intermode frequency separation

    International Nuclear Information System (INIS)

    Rudych, P D; Surovtsev, N V

    2014-01-01

    Two-color laser irradiation is considered an effective way to pump THz excitations for numerous scientific and applied goals. We present a design for convenient laser source with THz intermode frequency separation. The setup is based on dye laser with superthin resonator pumped by a subnanosecond pulse laser. It was proven that the superthin resonator dye laser is useful, possesses high stability and high energy conversion, and generates narrow laser modes. The ability of this laser to pump CARS processes for THz vibrations is demonstrated. (letter)

  3. Direct Laser Ablation and Ionization of Solids for Chemical Analysis by Mass Spectrometry

    Energy Technology Data Exchange (ETDEWEB)

    Holt, J K; Nelson, E J; Klunder, G L [Forensic Science Center, Lawrence Livermore National Laboratory, Livermore, CA 94551 (United States)

    2007-04-15

    A laser ablation/ionization mass spectrometer system is described for the direct chemical analysis of solids. An Nd:YAG laser is used for ablation and ionization of the sample in a quadrupole ion trap operated in an ion-storage (IS) mode that is coupled with a reflectron time-of-flight mass spectrometer (TOF-MS). Single pulse experiments have demonstrated simultaneous detection of up to 14 elements present in glasses in the ppm range. However, detection of the components has produced non-stoichiometric results due to difference in ionization potentials and fractionation effects. Time-of-flight secondary ionization mass spectrometry (TOF-SIMS) was used to spatially map elemental species on the surface and provide further evidence of fractionation effects. Resolution (m/{delta}m) of 1500 and detection limits of approximately 10 pg have been achieved with a single laser pulse. The system configuration and related operating principles for accurately measuring low concentrations of isotopes are described.

  4. The multiphoton ionization of uranium hexafluoride

    International Nuclear Information System (INIS)

    Armstrong, D.P.

    1992-05-01

    Multiphoton ionization (MPI) time-of-flight mass spectroscopy and photoelectron spectroscopy studies of UF 6 have been conducted using focused light from the Nd:YAG laser fundamental (λ=1064 nm) and its harmonics (λ=532, 355, or 266 nm), as well as other wavelengths provided by a tunable dye laser. The MPI mass spectra are dominated by the singly and multiply charged uranium ions rather than by the UF x + fragment ions even at the lowest laser power densities at which signal could be detected. The laser power dependence of U n+ ions signals indicates that saturation can occur for many of the steps required for their ionization. In general, the doubly-charged uranium ion (U 2+ ) intensity is much greater than that of the singly-charged uranium ion (U + ). For the case of the tunable dye laser experiments, the U n+ (n = 1- 4) wavelength dependence is relatively unstructured and does not show observable resonance enhancement at known atomic uranium excitation wavelengths. The dominance of the U 2+ ion and the absence or very small intensities of UF x + fragments, along with the unsaturated wavelength dependence, indicate that mechanisms may exist other than ionization of bare U atoms after the stepwise photodissociation of F atoms from the parent molecule

  5. Collinear Resonance Ionization Spectroscopy of Neutron-Deficient Francium Isotopes

    CERN Document Server

    Flanagan, K T; Ruiz, R F Garcia; Budincevic, I; Procter, T J; Fedosseev, V N; Lynch, K M; Cocolios, T E; Marsh, B A; Neyens, G; Strashnov, I; Stroke, H H; Rossel, R E; Heylen, H; Billowes, J; Rothe, S; Bissell, M L; Wendt, K D A; de Groote, R P; De Schepper, S

    2013-01-01

    The magnetic moments and isotope shifts of the neutron-deficient francium isotopes Fr202-205 were measured at ISOLDE-CERN with use of collinear resonance ionization spectroscopy. A production-to-detection efficiency of 1\\% was measured for Fr-202. The background from nonresonant and collisional ionization was maintained below one ion in 10(5) beam particles. Through a comparison of the measured charge radii with predictions from the spherical droplet model, it is concluded that the ground-state wave function remains spherical down to Fr-205, with a departure observed in Fr-203 (N = 116).

  6. Suitability test of a high beam quality Nd:YVO4 industrial laser for the ISOLDE RILIS installation.

    CERN Document Server

    Marsh, B; Fink, D; Goodacre, T; Rothe, S; Seliverstov, M; Imai, N; Sjodin, M; Rossel, R

    2013-01-01

    A multi-stage test of a Blaze 532-40-HE diode pumped Nd:YVO4 laser, supplied as a loan by Lumera Laser GmbH, has been performed at the ISOLDE RILIS installation. The feasibility of the integration of this laser within the existing laser setup was confirmed and its suitability for non-resonant ionization, dye laser pumping and Ti:Sa laser pumping has been assessed. The high beam quality (M2=1.1) and low jitter (<3 ns) are important parameters for effective power delivery to the ISOLDE ion source to provide the radiation for the non-resonant final step of a RILIS ionization scheme. To fulfil the reliability demands of an industrial laser, features such as multi-parameter logging, remote performance monitoring and optimization are included. The tests demonstrate the suitability of the laser for the three applications at RILIS, particularly for non-resonant ionization and dye laser pumping. The integration of this laser in the ISOLDE RILIS setup would be a significant upgrade to the laboratory that would resul...

  7. Coffee-ring effects in laser desorption/ionization mass spectrometry.

    Science.gov (United States)

    Hu, Jie-Bi; Chen, Yu-Chie; Urban, Pawel L

    2013-03-05

    This report focuses on the heterogeneous distribution of small molecules (e.g. metabolites) within dry deposits of suspensions and solutions of inorganic and organic compounds with implications for chemical analysis of small molecules by laser desorption/ionization (LDI) mass spectrometry (MS). Taking advantage of the imaging capabilities of a modern mass spectrometer, we have investigated the occurrence of "coffee rings" in matrix-assisted laser desorption/ionization (MALDI) and surface-assisted laser desorption/ionization (SALDI) sample spots. It is seen that the "coffee-ring effect" in MALDI/SALDI samples can be both beneficial and disadvantageous. For example, formation of the coffee rings gives rise to heterogeneous distribution of analytes and matrices, thus compromising analytical performance and reproducibility of the mass spectrometric analysis. On the other hand, the coffee-ring effect can also be advantageous because it enables partial separation of analytes from some of the interfering molecules present in the sample. We report a "hidden coffee-ring effect" where under certain conditions the sample/matrix deposit appears relatively homogeneous when inspected by optical microscopy. Even in such cases, hidden coffee rings can still be found by implementing the MALDI-MS imaging technique. We have also found that to some extent, the coffee-ring effect can be suppressed during SALDI sample preparation. Copyright © 2013 Elsevier B.V. All rights reserved.

  8. Analysis of laser ablation: Contribution of ionization energy to the plasma and shock wave properties

    International Nuclear Information System (INIS)

    Wen, S.-B.; Mao Xianglei; Greif, Ralph; Russo, Richard E.

    2007-01-01

    By fitting simulation results with experimentally measured trajectories of the shock wave and the vapor/background gas contact surface, we found that inclusion of ionization energy in the analysis leads to a change in the evolution of the pressure, mass density, electron number density, and temperature of the vapor plume. The contribution of ionization energy to both the plasma and shock wave has been neglected in most studies of laser ablation. Compared to previous simulations, the densities, pressures, and temperatures are lower shortly after the laser pulse ( 50 ns). The predicted laser energy conversion ratio also showed about a 20% increase (from 35% to 45%) when the ionization energy is considered. The changes in the evolution of the physical quantities result from the retention of the ionization energy in the vapor plume, which is then gradually transformed to kinetic and thermal energies. When ionization energy is included in the simulation, the vapor plume attains higher expansion speeds and temperatures for a longer time after the laser pulse. The better determination of the temperature history of the vapor plume not only improves the understanding of the expansion process of the laser induced vapor plume but also is important for chemical analysis. The accurate temperature history provides supplementary information which enhances the accuracy of chemical analysis based on spectral emission measurements (e.g., laser induced breakdown spectroscopy)

  9. Laser ionization of molecular clusters

    International Nuclear Information System (INIS)

    Desai, S.; Feigerle, C.S.

    1995-01-01

    Multiphoton ionization coupled with mass spectrometry was used to investigate molecular cluster distributions. Three examples will be discussed in this presentation. First, in studies of neat nitric oxide clusters, (NO) m , an interesting odd-even intensity alternation was observed and will be discussed in terms of electron-pairing considerations. In a separate study, the binary clusters comprising nitric oxide and methane preferentially form a stoichiometric cluster made up of repeating units of (NO) 2 CH 4 . These presumably represent a particularly strongly bound open-quotes van der Waalsclose quotes subunit. Finally, in similar studies of neat carbon disulfide clusters, (CS 2 ) m , additional photon absorption after the two-photon ionization step stimulates a series of intracluster ion-molecular reactions leading to formation of S m + and (CS) m + polymers, as well as intermediate species such as S m + (CS 2 ). This molecular cluster analogue of open-quotes laser snowclose quotes will be described in detail

  10. Ionization of oriented carbonyl sulfide molecules by intense circularly polarized laser pulses

    DEFF Research Database (Denmark)

    Dimitrovski, Darko; Abu-Samha, Mahmoud; Madsen, Lars Bojer

    2011-01-01

    We present combined experimental and theoretical results on strong-field ionization of oriented carbonyl sulfide molecules by circularly polarized laser pulses. The obtained molecular frame photoelectron angular distributions show pronounced asymmetries perpendicular to the direction of the molec......We present combined experimental and theoretical results on strong-field ionization of oriented carbonyl sulfide molecules by circularly polarized laser pulses. The obtained molecular frame photoelectron angular distributions show pronounced asymmetries perpendicular to the direction......-dimensionally-oriented polar molecules, in particular asymmetries in the emission direction of the photoelectrons. In the following article [Phys. Rev. A 83, 023406 (2011)] the focus is to understand strong-field ionization from three-dimensionally-oriented asymmetric top molecules, in particular the suppression of electron...

  11. Characterization of collisionally pumped optical-field-ionization soft X-ray lasers

    Czech Academy of Sciences Publication Activity Database

    Mocek, Tomáš; Sebban, S.; Bettaibi, I.; Upcraft, L. M.; Balcou, P.; Breger, P.; Zeitoun, P.; Le Pape, S.; Ros, D.; Klisnick, A.; Carillon, A.; Jamelot, G.; Rus, Bedřich; Wyart, J. F.

    2004-01-01

    Roč. 78, - (2004), s. 939-944 ISSN 0946-2171 Grant - others:HPRI(XE) 199900086 Institutional research plan: CEZ:AV0Z1010921 Keywords : X-ray lasers * optical-field-ionization * collisional excitation Subject RIV: BH - Optics, Masers, Lasers Impact factor: 2.215, year: 2004

  12. Associative ionization of two laser excited Na atoms

    International Nuclear Information System (INIS)

    Meijer, H.A.J.

    1988-01-01

    An investigation into the associative ionization of two sodium atoms excited by polarized laser beams is described. It was possible to excite the Na atoms in a velocity-selective way by exploiting the Doppler effect. The excitation of Na to the 3 2 P 3/2 , F=3 level is discussed on the basis of so-called saturation curves. Experiments with seven different combinations of polarization of the two exciting laser beams are described and the results discussed. 86 refs.; 53 figs.; 6 tabs

  13. Giant resonance phenomena in the electron impact ionization of heavy atoms and ions

    International Nuclear Information System (INIS)

    Younger, S.M.

    1986-01-01

    Heavy atoms and ions offer an interesting opportunity to study atomic physics in a region where the atomic structure is dominated by the interelectronic interactions. One illustration of this is the profound term dependence of atomic orbitals for certain configurations of heavy atoms and ions. The appearance of giant scattering resonances in the cross sections for ionization of heavy atoms by electron impact is a manifestation of resonance behavior. Such resonant structures arise from the double well nature of the scattering potential and have recently been identified in the cross sections for the electron impact ionization of several xenon-like ions. The results of calculations showing effects for a variety of other ions are summarized. 7 refs., 4 figs

  14. Resonance ionization mass spectrometry for long-lived radionuclide assay

    International Nuclear Information System (INIS)

    Fassett, J.D.; Travis, J.C.; Lucatorto, T.B.

    1986-01-01

    Isotopic ratios of /sup 10/Be:/sup 9/Be and /sup 129/I:/sup 127/I are measured from isotopic standards with ratios of 1:1000 and less. A high-resolution laser system is built and is capable of producing 25 mJ pulses of 10 nsec duration at 560 nm with 150 MHz bandwidth. This laser system is applied to the first isotopic shift measurement for beryllium. The issues involved in making low-level radioisotope measurements by RIMS, including atomization and ionization efficiencies, selectivity, and calibration are discussed

  15. Hole dynamics and spin currents after ionization in strong circularly polarized laser fields

    International Nuclear Information System (INIS)

    Barth, Ingo; Smirnova, Olga

    2014-01-01

    We apply the time-dependent analytical R-matrix theory to develop a movie of hole motion in a Kr atom upon ionization by strong circularly polarized field. We find rich hole dynamics, ranging from rotation to swinging motion. The motion of the hole depends on the final energy and the spin of the photoelectron and can be controlled by the laser frequency and intensity. Crucially, hole rotation is a purely non-adiabatic effect, completely missing in the framework of quasistatic (adiabatic) tunneling theories. We explore the possibility to use hole rotation as a clock for measuring ionization time. Analyzing the relationship between the relative phases in different ionization channels we show that in the case of short-range electron-core interaction the hole is always initially aligned along the instantaneous direction of the laser field, signifying zero delays in ionization. Finally, we show that strong-field ionization in circular fields creates spin currents (i.e. different flow of spin-up and spin-down density in space) in the ions. This phenomenon is intimately related to the production of spin-polarized electrons in strong laser fields Barth and Smirnova (2013 Phys. Rev. A 88 013401). We demonstrate that rich spin dynamics of electrons and holes produced during strong field ionization can occur in typical experimental conditions and does not require relativistic intensities or strong magnetic fields. (paper)

  16. Few-Photon Multiple Ionization of Ne and Ar by Strong Free-Electron-Laser Pulses

    International Nuclear Information System (INIS)

    Moshammer, R.; Jiang, Y. H.; Rudenko, A.; Ergler, Th.; Schroeter, C. D.; Luedemann, S.; Zrost, K.; Dorn, A.; Ferger, T.; Kuehnel, K. U.; Ullrich, J.; Foucar, L.; Titze, J.; Jahnke, T.; Schoeffler, M.; Doerner, R.; Fischer, D.; Weber, T.; Zouros, T. J. M.; Duesterer, S.

    2007-01-01

    Few-photon multiple ionization of Ne and Ar atoms by strong vacuum ultraviolet laser pulses from the free-electron laser at Hamburg was investigated differentially with the Heidelberg reaction microscope. The light-intensity dependence of Ne 2+ production reveals the dominance of nonsequential two-photon double ionization at intensities of I 12 W/cm 2 and significant contributions of three-photon ionization as I increases. Ne 2+ recoil-ion-momentum distributions suggest that two electrons absorbing ''instantaneously'' two photons are ejected most likely into opposite hemispheres with similar energies

  17. Target Plate Material Influence on Fullerene-C60 Laser Desorption/Ionization Efficiency

    Science.gov (United States)

    Zeegers, Guido P.; Günthardt, Barbara F.; Zenobi, Renato

    2016-04-01

    Systematic laser desorption/ionization (LDI) experiments of fullerene-C60 on a wide range of target plate materials were conducted to gain insight into the initial ion formation in matrix-assisted laser desorption/ionization (MALDI) mass spectrometry. The positive and negative ion signal intensities of precursor, fragment, and cluster ions were monitored, varying both the laser fluence (0-3.53 Jcm-2) and the ion extraction delay time (0-950 ns). The resulting species-specific ion signal intensities are an indication for the ionization mechanisms that contribute to LDI and the time frames in which they operate, providing insight in the (MA)LDI primary ionization. An increasing electrical resistivity of the target plate material increases the fullerene-C60 precursor and fragment anion signal intensity. Inconel 625 and Ti90/Al6/V4, both highly electrically resistive, provide the highest anion signal intensities, exceeding the cation signal intensity by a factor ~1.4 for the latter. We present a mechanism based on transient electrical field strength reduction to explain this trend. Fullerene-C60 cluster anion formation is negligible, which could be due to the high extraction potential. Cluster cations, however, are readily formed, although for high laser fluences, the preferred channel is formation of precursor and fragment cations. Ion signal intensity depends greatly on the choice of substrate material, and careful substrate selection could, therefore, allow for more sensitive (MA)LDI measurements.

  18. Selective laser ionization for mass-spectral isotopic analysis

    International Nuclear Information System (INIS)

    Miller, C.M.; Nogar, N.S.; Downey, S.W.

    1983-01-01

    Resonant enhancement of the ionization process can provide a high degree of elemental selectivity, thus eliminating or drastically reducing the interference problem. In addition, extension of this method to isotopically selective ionization has the potential for greatly increasing the range of isotope ratios that can be determined experimentally. This gain can be realized by reducing or eliminating the tailing of the signal from the high-abundance isotope into that of the low-abundance isotope, augmenting the dispersion of the mass spectrometer. We briefly discuss the hardware and techniques used in both our pulsed and cw RIMS experiments. Results are presented for both cw ionization experiments on Lu/Yb mixtures, and spectroscopic studies of multicolor RIMS of Tc. Lastly, we discuss practical limits of cw RIMS analysis in terms of detection limits and measurable isotope ratios

  19. Method of concentrating and separating lithium isotopes by laser

    International Nuclear Information System (INIS)

    Yamashita, Mikio; Kashiwagi, Hiroshi.

    1976-01-01

    Purpose: To eliminate the need for repeating separating operation in many stages and permit concentrated lithium of high purity to be obtained in a short period of time. Constitution: Lithium atom vapor is irradiated by a laser of wavelengths resonant to 6 Li or 7 Li absorption spectra present in the neighborhood of 6,707.84 A or 3,232.61 A (chromatic laser being used for oscillation in the neighborhood of 6,707.84 A and ultraviolet laser used for oscillation in the neighborhood of 6,707.84 A) for selectively exciting 6 Li or 7 Li alone. Then, ionization is brought about by using other types of lasers (ultraviolet Ar ion laser being used as the former wavelength laser and visible Ar ion laser as the latter wavelength laser), and only the ionized isotopes are passed through a mass filter and collected by an ion collector, thereby effecting separation of the ionized isotopes from the non-ionized neutral isotopes and their concentration. (Aizawa, K.)

  20. Numerical study of laser-induced blast wave coupled with unsteady ionization processes

    International Nuclear Information System (INIS)

    Ogino, Y; Ohnishi, N; Sawada, K

    2008-01-01

    We present the results of the numerical simulation of laser-induced blast wave coupled with rate equations to clarify the unsteady property of ionization processes during pulse heating. From comparison with quasi-steady computations, the plasma region expands more widely, which is sustained by the inverse-bremsstrahlung since an ionization equilibrium does not establish at the front of the plasma region. The delayed relaxation leads to the rapid expansion of the driving plasma and enhances the energy conversion efficiency from a pulse heating laser to the blast wave

  1. Ultra-low emittance electron beam generation using ionization injection in a plasma beatwave accelerator

    Science.gov (United States)

    Schroeder, Carl; Benedetti, Carlo; Esarey, Eric; Leemans, Wim

    2017-10-01

    Ultra-low emittance beams can be generated using ionization injection of electrons into a wakefield excited by a plasma beatwave accelerator. This all-optical method of electron beam generation uses three laser pulses of different colors. Two long-wavelength laser pulses, with frequency difference equal to the plasma frequency, resonantly drive a plasma wave without fully ionizing a gas. A short-wavelength injection laser pulse (with a small ponderomotive force and large peak electric field), co-propagating and delayed with respect to the beating long-wavelength lasers, ionizes a fraction of the remaining bound electrons at a trapped wake phase, generating an electron beam that is accelerated in the wakefield. Using the beating of long-wavelength pulses to generate the wakefield enables atomically-bound electrons to remain at low ionization potentials, reducing the required amplitude of the ionization pulse, and, hence, the initial transverse momentum and emittance of the injected electrons. An example is presented using two lines of a CO2 laser to form a plasma beatwave accelerator to drive the wake and a frequency-doubled Ti:Al2O3 laser for ionization injection. Supported by the U.S. Department of Energy under Contract No. DE-AC02-05CH11231.

  2. Nanoparticle assisted laser desorption/ionization mass spectrometry for small molecule analytes.

    Science.gov (United States)

    Abdelhamid, Hani Nasser

    2018-03-01

    Nanoparticle assisted laser desorption/ionization mass spectrometry (NPs-ALDI-MS) shows remarkable characteristics and has a promising future in terms of real sample analysis. The incorporation of NPs can advance several methods including surface assisted LDI-MS, and surface enhanced LDI-MS. These methods have advanced the detection of many thermally labile and nonvolatile biomolecules. Nanoparticles circumvent the drawbacks of conventional organic matrices for the analysis of small molecules. In most cases, NPs offer a clear background without interfering peaks, absence of fragmentation of thermally labile molecules, and allow the ionization of species with weak noncovalent interactions. Furthermore, an enhancement in sensitivity and selectivity can be achieved. NPs enable straightforward analysis of target species in a complex sample. This review (with 239 refs.) covers the progress made in laser-based mass spectrometry in combination with the use of metallic NPs (such as AuNPs, AgNPs, PtNPs, and PdNPs), NPs consisting of oxides and chalcogenides, silicon-based NPs, carbon-based nanomaterials, quantum dots, and metal-organic frameworks. Graphical abstract An overview is given on nanomaterials for use in surface-assisted laser desorption/ionization mass spectrometry of small molecules.

  3. Quantum mechanical theory of collisional ionization in the presence of intense laser radiation

    Science.gov (United States)

    Bellum, J. C.; George, T. F.

    1978-01-01

    The paper presents a quantum mechanical formalism for treating ionizing collisions occurring in the presence of an intense laser field. Both the intense laser radiation and the internal electronic continuum states associated with the emitted electrons are rigorously taken into account by combining discretization techniques with expansions in terms of electronic-field representations for the quasi-molecule-plus-photon system. The procedure leads to a coupled-channel description of the heavy-particle dynamics which involves effective electronic-field potential surfaces and continua. It is suggested that laser-influenced ionizing collisions can be studied to verify the effects of intense laser radiation on inelastic collisional processes. Calculation procedures for electronic transition dipole matrix elements between discrete and continuum electronic states are outlined.

  4. Laser vaporization/ionization interface for coupling microscale separation techniques with mass spectrometry

    Science.gov (United States)

    Yeung, E.S.; Chang, Y.C.

    1999-06-29

    The present invention provides a laser-induced vaporization and ionization interface for directly coupling microscale separation processes to a mass spectrometer. Vaporization and ionization of the separated analytes are facilitated by the addition of a light-absorbing component to the separation buffer or solvent. 8 figs.

  5. Calculation of laser induced impulse based on the laser supported detonation wave model with dissociation, ionization and radiation

    International Nuclear Information System (INIS)

    Gan, Li; Mousen, Cheng; Xiaokang, Li

    2014-01-01

    In the laser intensity range that the laser supported detonation (LSD) wave can be maintained, dissociation, ionization and radiation take a substantial part of the incidence laser energy. There is little treatment on the phenomenon in the existing models, which brings obvious discrepancies between their predictions and the experiment results. Taking into account the impact of dissociation, ionization and radiation in the conservations of mass, momentum and energy, a modified LSD wave model is developed which fits the experimental data more effectively rather than the existing models. Taking into consideration the pressure decay of the normal and the radial rarefaction, the laser induced impulse that is delivered to the target surface is calculated in the air; and the dependencies of impulse performance on laser intensity, pulse width, ambient pressure and spot size are indicated. The results confirm that the dissociation is the pivotal factor of the appearance of the momentum coupling coefficient extremum. This study focuses on a more thorough understanding of LSD and the interaction between laser and matter

  6. Calculation of laser induced impulse based on the laser supported detonation wave model with dissociation, ionization and radiation

    Energy Technology Data Exchange (ETDEWEB)

    Gan, Li, E-mail: ligan0001@gmail.com; Mousen, Cheng; Xiaokang, Li [College of Aerospace Science and Engineering, National University of Defense Technology, Changsha (China)

    2014-03-15

    In the laser intensity range that the laser supported detonation (LSD) wave can be maintained, dissociation, ionization and radiation take a substantial part of the incidence laser energy. There is little treatment on the phenomenon in the existing models, which brings obvious discrepancies between their predictions and the experiment results. Taking into account the impact of dissociation, ionization and radiation in the conservations of mass, momentum and energy, a modified LSD wave model is developed which fits the experimental data more effectively rather than the existing models. Taking into consideration the pressure decay of the normal and the radial rarefaction, the laser induced impulse that is delivered to the target surface is calculated in the air; and the dependencies of impulse performance on laser intensity, pulse width, ambient pressure and spot size are indicated. The results confirm that the dissociation is the pivotal factor of the appearance of the momentum coupling coefficient extremum. This study focuses on a more thorough understanding of LSD and the interaction between laser and matter.

  7. Nonsequential multiphoton double ionization of He in intense laser - a QED approach

    International Nuclear Information System (INIS)

    Bhattacharyya, S.; Mazumder, Mina; Chakrabarti, J.; Faisal, F.H.M.

    2010-01-01

    The non-sequential muItiphoton double ionization (NSDI) of He in intense laser field is not yet completely understood, more so for spin resolved currents. We are tempted to use QED and Feynman diagram to obtain spin polarized currents. Hartree-Fock (HF) ground-state correlated wave function of He atom is considered in circularly polarized laser. In QED approach one of the electrons is directly ionized by photon absorption while the second electron is shaken off due to the change in the internal potential of the atom. In He-atom the two ionized electrons can only be in the singlet spin state. Spin-symmetric and spin-flip transitions are eventually possible for the direct and the shake-off electrons. In an ensemble of (HF type) He-atoms the ionized Volkov electrons may acquire 4 pairs of momenta indicating e-e correlation in the final state. Coulomb correction is taken care off through the Sommerfeld factor

  8. Subcellular analysis by laser ablation electrospray ionization mass spectrometry

    Science.gov (United States)

    Vertes, Akos; Stolee, Jessica A; Shrestha, Bindesh

    2014-12-02

    In various embodiments, a method of laser ablation electrospray ionization mass spectrometry (LAESI-MS) may generally comprise micro-dissecting a cell comprising at least one of a cell wall and a cell membrane to expose at least one subcellular component therein, ablating the at least one subcellular component by an infrared laser pulse to form an ablation plume, intercepting the ablation plume by an electrospray plume to form ions, and detecting the ions by mass spectrometry.

  9. Laser cooling at resonance

    Science.gov (United States)

    Yudkin, Yaakov; Khaykovich, Lev

    2018-05-01

    We show experimentally that three-dimensional laser cooling of lithium atoms on the D2 line is possible when the laser light is tuned exactly to resonance with the dominant atomic transition. Qualitatively, it can be understood by applying simple Doppler cooling arguments to the specific hyperfine structure of the excited state of lithium atoms, which is both dense and inverted. However, to build a quantitative theory, we must resolve to a full model which takes into account both the entire atomic structure of all 24 Zeeman sublevels and the laser light polarization. Moreover, by means of Monte Carlo simulations, we show that coherent processes play an important role in showing consistency between the theory and the experimental results.

  10. SFC-APLI-(TOF)MS: Hyphenation of Supercritical Fluid Chromatography to Atmospheric Pressure Laser Ionization Mass Spectrometry.

    Science.gov (United States)

    Klink, Dennis; Schmitz, Oliver Johannes

    2016-01-05

    Atmospheric-pressure laser ionization mass spectrometry (APLI-MS) is a powerful method for the analysis of polycyclic aromatic hydrocarbon (PAH) molecules, which are ionized in a selective and highly sensitive way via resonance-enhanced multiphoton ionization. APLI was presented in 2005 and has been hyphenated successfully to chromatographic separation techniques like high performance liquid chromatography (HPLC) and gas chromatography (GC). In order to expand the portfolio of chromatographic couplings to APLI, a new hyphenation setup of APLI and supercritical-fluid chromatography (SFC) was constructed and aim of this work. Here, we demonstrate the first hyphenation of SFC and APLI in a simple designed way with respect to different optimization steps to ensure a sensitive analysis. The new setup permits qualitative and quantitative determination of native and also more polar PAH molecules. As a result of the altered ambient characteristics within the source enclosure, the quantification of 1-hydroxypyrene (1-HP) in human urine is possible without prior derivatization. The limit of detection for 1-HP by SFC-APLI-TOF(MS) was found to be 0.5 μg L(-1), which is lower than the 1-HP concentrations found in exposed persons.

  11. Relativistic theory of tunnel and multiphoton ionization of atoms in a strong laser field

    International Nuclear Information System (INIS)

    Popov, V. S.; Karnakov, B. M.; Mur, V. D.; Pozdnyakov, S. G.

    2006-01-01

    Relativistic generalization is developed for the semiclassical theory of tunnel and multiphoton ionization of atoms and ions in the field of an intense electromagnetic wave (Keldysh theory). The cases of linear, circular, and elliptic polarizations of radiation are considered. For arbitrary values of the adiabaticity parameter γ, the exponential factor in the ionization rate for a relativistic bound state is calculated. For low-frequency laser radiation , an asymptotically exact formula for the tunnel ionization rate for the atomic s level is obtained including the Coulomb, spin, and adiabatic corrections and the preexponential factor. The ionization rate for the ground level of a hydrogen-like atom (ion) with Z ≤ 100 is calculated as a function of the laser radiation intensity. The range of applicability is determined for nonrelativistic ionization theory. The imaginary time method is used in the calculations

  12. Study of the ionization of H{sup +}{sub 2} ions in strong laser fields; Untersuchung der Ionisation von H{sup +}{sub 2}-Ionen in starken Laserfeldern

    Energy Technology Data Exchange (ETDEWEB)

    Odenweller, Matthias

    2010-07-01

    In the framework of this thesis it has been succeeded to develop a worldwide unique measurement apparatur, by which hydrogen-molecule ions can be ionized by means of short laser pulses and the reaction product kinematically completely measured. For this a detection method following the Coltrims technique, in which both protons and electrons can be detected over the complete spatial angle. The H{sup +}{sub 2} ions origin from a high-frequency ion source and are accelerated to 400 keV. This ion beam is overlapped with a 780-nm laser pulse othe pulse length 40 fs. After the reaction the molecule ions fragments either via the dissociation channel H{sup +}{sub 2}+nh{nu}{yields}H+H{sup +} or via an ionization followed by a Coulomb explosion: H{sup +}{sub 2}+nh{nu}{yields}H{sup +}+H{sup +}+e{sup -}. The projectiles are detected after a drift path of about 3 m on an ion detector. For the detection of the electrons a special spectrometer was concipated. In the reaction it comes by the comparatively long pulse length already at low intensities to dissociation processes. The dissociating molecule reaches still during the increasing side of the laser pulse in this way distances, in which the charge-resonance-enhanced-ionization (CREI) can take place. Also the angular distribution of the measured protons lying in a very small angular range around the polarization direction of the laser suggests that CREI is the dominant ionization process. At circular polarization however a netto-acceleration of the electrons perpendicularly to the direction of the electric field at the ionization time takes place, so that the measurement of the electron momenta represents a suited measurement quantity for the study of the ionization process. By this way angular distributions of the electrons relatively to the internuclear axis within the polarization plane could be measured.

  13. All-solid-state deep ultraviolet laser for single-photon ionization mass spectrometry.

    Science.gov (United States)

    Yuan, Chengqian; Liu, Xianhu; Zeng, Chenghui; Zhang, Hanyu; Jia, Meiye; Wu, Yishi; Luo, Zhixun; Fu, Hongbing; Yao, Jiannian

    2016-02-01

    We report here the development of a reflectron time-of-flight mass spectrometer utilizing single-photon ionization based on an all-solid-state deep ultraviolet (DUV) laser system. The DUV laser was achieved from the second harmonic generation using a novel nonlinear optical crystal KBe2BO3F2 under the condition of high-purity N2 purging. The unique property of this laser system (177.3-nm wavelength, 15.5-ps pulse duration, and small pulse energy at ∼15 μJ) bears a transient low power density but a high single-photon energy up to 7 eV, allowing for ionization of chemicals, especially organic compounds free of fragmentation. Taking this advantage, we have designed both pulsed nanospray and thermal evaporation sources to form supersonic expansion molecular beams for DUV single-photon ionization mass spectrometry (DUV-SPI-MS). Several aromatic amine compounds have been tested revealing the fragmentation-free performance of the DUV-SPI-MS instrument, enabling applications to identify chemicals from an unknown mixture.

  14. Resonance ionization spectroscopy: Counting noble gas atoms

    International Nuclear Information System (INIS)

    Hurst, G.S.; Payne, M.G.; Chen, C.H.; Willis, R.D.; Lehmann, B.E.; Kramer, S.D.

    1981-01-01

    The purpose of this paper is to describe new work on the counting of noble gas atoms, using lasers for the selective ionization and detectors for counting individual particles (electrons or positive ions). When positive ions are counted, various kinds of mass analyzers (magnetic, quadrupole, or time-of-flight) can be incorporated to provide A selectivity. We show that a variety of interesting and important applications can be made with atom-counting techniques which are both atomic number (Z) and mass number (A) selective. (orig./FKS)

  15. Study of ionization process of matrix molecules in matrix-assisted laser desorption ionization

    Energy Technology Data Exchange (ETDEWEB)

    Murakami, Kazumasa; Sato, Asami; Hashimoto, Kenro; Fujino, Tatsuya, E-mail: fujino@tmu.ac.jp

    2013-06-20

    Highlights: ► Proton transfer and adduction reaction of matrix in MALDI were studied. ► Hydroxyl group forming intramolecular hydrogen bond was related to the ionization. ► Intramolecular proton transfer in the electronic excited state was the initial step. ► Non-volatile analytes stabilized protonated matrix in the ground state. ► A possible mechanism, “analyte support mechanism”, has been proposed. - Abstract: Proton transfer and adduction reaction of matrix molecules in matrix-assisted laser desorption ionization were studied. By using 2,4,6-trihydroxyacetophenone (THAP), 2,5-dihydroxybenzoic acid (DHBA), and their related compounds in which the position of a hydroxyl group is different, it was clarified that a hydroxyl group forming an intramolecular hydrogen bond is related to the ionization of matrix molecules. Intramolecular proton transfer in the electronic excited state of the matrix and subsequent proton adduction from a surrounding solvent to the charge-separated matrix are the initial steps for the ionization of matrix molecules. Nanosecond pump–probe NIR–UV mass spectrometry confirmed that the existence of analyte molecules having large dipole moment in their structures is necessary for the stabilization of [matrix + H]{sup +} in the electronic ground state.

  16. Opto-mechanical design of vacuum laser resonator for the OSQAR experiment

    Science.gov (United States)

    Hošek, Jan; Macúchová, Karolina; Nemcová, Šárka; Kunc, Štěpán.; Šulc, Miroslav

    2015-01-01

    This paper gives short overview of laser-based experiment OSQAR at CERN which is focused on search of axions and axion-like particles. The OSQAR experiment uses two experimental methods for axion search - measurement of the ultra-fine vacuum magnetic birefringence and a method based on the "Light shining through the wall" experiment. Because both experimental methods have reached its attainable limits of sensitivity we have focused on designing a vacuum laser resonator. The resonator will increase the number of convertible photons and their endurance time within the magnetic field. This paper presents an opto-mechanical design of a two component transportable vacuum laser resonator. Developed optical resonator mechanical design allows to be used as a 0.8 meter long prototype laser resonator for laboratory testing and after transportation and replacement of the mirrors it can be mounted on the LHC magnet in CERN to form a 20 meter long vacuum laser resonator.

  17. Single-mode Brillouin fiber laser passively stabilized at resonance frequency with self-injection locked pump laser

    International Nuclear Information System (INIS)

    Spirin, V V; Lopez-Mercado, C A; Megret, P; Fotiadi, A A

    2012-01-01

    We demonstrate a single-mode Brillouin fiber ring laser, which is passively stabilized at pump resonance frequency by using self-injection locking of semiconductor pump laser. Resonance condition for Stokes radiation is achieved by length fitting of Brillouin laser cavity. The laser generate single-frequency Stokes wave with linewidth less than 0.5 kHz using approximately 17-m length cavity

  18. Investigation of the energy levels of the gadolinium atom using resonance ionization mass spectrometry

    International Nuclear Information System (INIS)

    Kim, Jin Tae; Yi, Jong Hoon; Rhee, Yong Joo; Lee, Jong Min

    2000-01-01

    We have investigated the ionization processes, the energy values, and the strengths of ion signals by using a dye laser frequency in the ultra-violet range with one-color multi-photon ionization. Also, two color multi-photon ionization by using another near infrared photon has been done to investigate energy levels with odd-parity in the energy range of between 35500 cm -1 and 37700 cm -1

  19. Picosecond multiphoton ionization of atomic and molecular clusters

    International Nuclear Information System (INIS)

    Miller, J.C.; Smith, D.B.

    1990-01-01

    High peak-power picosecond laser pulses have been used for the first time to effect nonresonant or resonant multiphoton ionization (MPI) of clusters generated in a supersonic nozzle expansion. The resulting ions are subsequently detected and characterized by time-of-flight mass spectroscopy. Specifically, we present results involving MPI of clusters of xenon and nitric oxide. Previous MPI studies of many molecular clusters using nanosecond lasers have not been successful in observing the parent ion, presumably due to fast dissociation channels. It is proposed that the present technique is a new and rather general ionization source for cluster studies which is complementary to electron impact but may, in addition, provide unique spectroscopic or dynamical information. 23 refs., 5 figs

  20. Enhanced asymmetry in few-cycle attosecond pulse ionization of He in the vicinity of autoionizing resonances

    International Nuclear Information System (INIS)

    Djiokap, J M Ngoko; Starace, Anthony F; Hu, S X; Jiang Weichao; Peng Liangyou

    2012-01-01

    By solving the two-active-electron, time-dependent Schrödinger equation in its full dimensionality, we investigate the carrier-envelope phase (CEP) dependence of single ionization of He to the He + (1s) state triggered by an intense few-cycle attosecond pulse with carrier frequency ω corresponding to the energy ℏω = 36 eV. Effects of electron correlations are probed by comparing projections of the final state of the two-electron wave packet onto field-free highly correlated Jacobi matrix wave functions with projections onto uncorrelated Coulomb wave functions. Significant differences are found in the vicinity of autoionizing resonances. Owing to the broad bandwidths of our 115 and 230 as pulses and their high intensities (1–2 PW cm −2 ), asymmetries are found in the differential probability for ionization of electrons parallel and antiparallel to the linear polarization axis of the laser pulse. These asymmetries stem from interference of the one- and two-photon ionization amplitudes for producing electrons with the same momentum along the linear polarization axis. Whereas these asymmetries generally decrease with increasing ionized electron kinetic energy, we find a large enhancement of the asymmetry in the vicinity of two-electron doubly excited (autoionizing) states on an energy scale comparable to the widths of the autoionizing states. The CEP dependence of the energy-integrated asymmetry agrees very well with the predictions of time-dependent perturbation theory (Pronin et al 2009 Phys. Rev. A 80 063403). (paper)

  1. Simulation of self-focusing of laser beam through medium with multi-step photo-ionization

    International Nuclear Information System (INIS)

    Akaoka, Katsuaki; Wakaida, Ikuo; Arisawa, Takashi

    1995-01-01

    We built a computation code for the coupled nonlinear Maxwell-Density Matrix equations of multi-level atomic systems including transverse and time-dependent variations. Numerical solutions for two-level atomic systems shown as a function of laser detuning in Na and U are in good agreement with the experimental result. Applying this code to the laser beam propagation through medium with two-step photo-ionization, it is concluded that the group velocity in the spatial edge of a laser pulse is slower than that in the center, and the self-focusing and the temporal reshaping of the laser pulse used for the first-excitation are more distinguished than that used for ionization. (author)

  2. Multiple ionization dynamics of molecules in intense laser fields

    International Nuclear Information System (INIS)

    Ichimura, Atsushi; Ohyama-Yamaguchi, Tomoko

    2005-01-01

    A classical field-ionization model is developed for sequential multiple ionization of diatomic and linear triatomic molecules exposed to intense (∼ 10 15 W/cm 2 ) laser fields. The distance R ion of Coulomb explosion is calculated for a combination of fragment charges, by considering nonadiabatic excitation followed by field ionization associated with the inner and outer saddle points. For diatomic molecules (N 2 , NO, and I 2 ), the model explains behaviors observed in experiments, as R ion (21→31) ion (21→22) between competing charge-asymmetric and symmetric channels, and even-odd fluctuation along a principal pathway. For a triatomic molecule CO 2 , a comparison of the model with an experiment suggests that charge-symmetric (or nearly symmetric) channels are dominantly populated. (author)

  3. Use of resonance ionization spectroscopy to detect DNA bands on ultrathin spin-coated gels.

    Science.gov (United States)

    Doktycz, M J; Gibson, W A; Arlinghaus, H F; Allen, R C; Jacobson, K B

    1993-01-01

    Development of alternative electrophoresis procedures are necessary for large volume sequencing and mapping studies. The use of stable isotopes as DNA labels and ultrathin gels promises to greatly increase the rate of sequencing. Spin coating is presented as an alternative method for producing ultrathin polyacrylamide gels. The technique has the potential of producing gels of micron to submicron thicknesses by varying the viscosity of the acrylamide solution and the spinning speed. Thirty micron thick 6% (weight %) gels were produced in this manner. Tin-labeled DNA oligomers were electrophoresed and detected using sputter-initiated resonance ionization spectroscopy (SIRIS). The usefulness of SIRIS and laser atomization RIS (LARIS) to sample the surface and deeper layers of 240 microns thick gels was investigated. With LARIS, whole cross-sections of the gel can be atomized, possibly allowing complete sampling of labels.

  4. Desorption and ionization processes in laser mass spectrometry

    International Nuclear Information System (INIS)

    Peyl, G.J.Q. van der.

    1984-01-01

    In this thesis results are reported from a study on the desorption- and ionization process initiated by infra-red laser irradiation (LDMS) or ion bombardment (SIMS) of thin organic sample layers. The study is especially focused on the formation of quasimolecular ions under these conditions. Results of these investigations can be used for a better optimization of the LDMS and SIMS techniques in organic mass spectrometry. First, an overview is given of laser desorption mass spectrometry. Next, the coupling of the laser energy into the organic sample layer is investigated. It is concluded that the laser energy is primarily absorbed by the substrate material and not by the organic overlayer. The formation of quasi-molecular ions, either in the gas phase or in the substrate surface is investigated. The final section reports kinetic energy distributions for ions sputtered from organic solids and liquids. (Auth.)

  5. Investigation of the energy levels of the gadolinium atom using resonance ionization mass spectrometry

    CERN Document Server

    Kim, J T; Rhee, Y J; Lee, J M

    2000-01-01

    We have investigated the ionization processes, the energy values, and the strengths of ion signals by using a dye laser frequency in the ultra-violet range with one-color multi-photon ionization. Also, two color multi-photon ionization by using another near infrared photon has been done to investigate energy levels with odd-parity in the energy range of between 35500 cm sup - sup 1 and 37700 cm sup - sup 1

  6. Iron oxide nanomatrix facilitating metal ionization in matrix-assisted laser desorption/ionization mass spectrometry.

    Science.gov (United States)

    Obena, Rofeamor P; Lin, Po-Chiao; Lu, Ying-Wei; Li, I-Che; del Mundo, Florian; Arco, Susan dR; Nuesca, Guillermo M; Lin, Chung-Chen; Chen, Yu-Ju

    2011-12-15

    The significance and epidemiological effects of metals to life necessitate the development of direct, efficient, and rapid method of analysis. Taking advantage of its simple, fast, and high-throughput features, we present a novel approach to metal ion detection by matrix-functionalized magnetic nanoparticle (matrix@MNP)-assisted MALDI-MS. Utilizing 21 biologically and environmentally relevant metal ion solutions, the performance of core and matrix@MNP against conventional matrixes in MALDI-MS and laser desorption ionization (LDI) MS were systemically tested to evaluate the versatility of matrix@MNP as ionization element. The matrix@MNPs provided 20- to >100-fold enhancement on detection sensitivity of metal ions and unambiguous identification through characteristic isotope patterns and accurate mass (<5 ppm), which may be attributed to its multifunctional role as metal chelator, preconcentrator, absorber, and reservoir of energy. Together with the comparison on the ionization behaviors of various metals having different ionization potentials (IP), we formulated a metal ionization mechanism model, alluding to the role of exciton pooling in matrix@MNP-assisted MALDI-MS. Moreover, the detection of Cu in spiked tap water demonstrated the practicability of this new approach as an efficient and direct alternative tool for fast, sensitive, and accurate determination of trace metal ions in real samples.

  7. Uv laser triggering of high-voltage gas switches

    International Nuclear Information System (INIS)

    Woodworth, J.R.; Frost, C.A.; Green, T.A.

    1982-01-01

    Two different techniques are discussed for uv laser triggering of high-voltage gas switches using a KrF laser (248 nm) to create an ionized channel through the dielectric gas in a spark gap. One technique uses an uv laser to induce breakdown in SF 6 . For this technique, we present data that demonstrate a 1-sigma jitter of +- 150 ps for a 0.5-MV switch at 80% of its self-breakdown voltage using a low-divergence KrF laser. The other scheme uses additives to the normal dielectric gas, such as tripropylamine, which are selected to undergo resonant two-step ionization in the uv laser field

  8. Localization of ionization-induced trapping in a laser wakefield accelerator using a density down-ramp

    CERN Document Server

    Hansson, M.; Ekerfelt, H.; Aurand, B.; Gallardo Ganzalez, I.; Desforges, F. G.; Davoine, X.; Maitrallain, A.; Reymond, S.; Monot, P.; Persson, A.; Dobosz Dufrénoy S.; Wahlström C-G.; Cros, B.; Lundh, O.

    2016-01-01

    We report on a study on controlled trapping of electrons, by field ionization of nitrogen ions, in laser wakefield accelerators in variable length gas cells. In addition to ionization-induced trapping in the density plateau inside the cells, which results in wide, but stable, electron energy spectra, a regime of ionization-induced trapping localized in the density down-ramp at the exit of the gas cells, is found. The resulting electron energy spectra are peaked, with 10% shot-to-shot fluctuations in peak energy. Ionization-induced trapping of electrons in the density down-ramp is a way to trap and accelerate a large number of electrons, thus improving the efficiency of the laser-driven wakefield acceleration.

  9. Laser material purification of neodymium. Hikari reiki seiseiho ni yoru neodymium no kojundoka

    Energy Technology Data Exchange (ETDEWEB)

    Ogawa, Y.; Ozaki, T.; Yoshimatsu, S. (National Research Institute for Metals, Tokyo (Japan)); Chiba, K.; Umeda, H.; Saeki, M. (Nippon Steel Corp., Tokyo (Japan))

    1991-05-20

    Selective photoexcitation and photoionization of neodymium atoms were studied basically by using laser. Also, using their properties, feasibility of laser material purification (LPM) technology in gaseous phase was presented. In the selective 3-step ionization, laser beam with two kinds of proper wave length causes resonance exitation of the target element, which goes up to the excitation level of the first step, and the element is ionized by the second laser beam and the third laser beam. The 3-step ionization scheme by a single wave length laser beam of 577.612nm was used for the ionization of Nd. Nd ionized selectively by laser beam was recovered as thin layer at the negative potential side of plane electrodes placed at both sides of the laser irradiation area. In the layer formed by the TPD technology with this scheme, it is possible to decrease impuritis such as Pr by 1/16 and to form highly purified thin layer. 13 refs., 12 figs., 1 tab.

  10. Optical Analysis of Grazing Incidence Ring Resonators for Free-Electron Lasers

    Science.gov (United States)

    Gabardi, David Richard

    1990-08-01

    The design of resonators for free-electron lasers (FELs) which are to operate in the soft x-ray/vacuum ultraviolet (XUV) region of the spectrum is complicated by the fact that, in this wavelength regime, normal incidence mirrors, which would otherwise be used for the construction of the resonators, generally have insufficient reflectivities for this purpose. However, the use of grazing incidence mirrors in XUV resonators offers the possibility of (1) providing sufficient reflectivity, (2) a lessening of the mirrors' thermal loads due to the projection of the laser beam onto an oblique surface, and (3) the preservation of the FEL's tunability. In this work, the behavior of resonators employing grazing incidence mirrors in ring type configurations is explored. In particular, two designs, each utilizing four off-axis conic mirrors and a number of flats, are examined. In order to specify the location, orientation, and surface parameters for the mirrors in these resonators, a design algorithm has been developed based upon the properties of Gaussian beam propagation. Two computer simulation methods are used to perform a vacuum stability analysis of the two resonator designs. The first method uses paraxial ray trace techniques with the resonators' thin lens analogues while the second uses the diffraction-based computer simulation code GLAD (General Laser Analysis and Design). The effects of mirror tilts and deviations in the mirror surface parameters are investigated for a number of resonators designed to propagate laser beams of various Rayleigh ranges. It will be shown that resonator stability decreases as the laser wavelength for which the resonator was designed is made smaller. In addition, resonator stability will also be seen to decrease as the amount of magnification the laser beam receives as it travels around the resonator is increased.

  11. Exploring Redox Properties of Aromatic Amino Acids in Water: Contrasting Single Photon vs Resonant Multiphoton Ionization in Aqueous Solutions.

    Science.gov (United States)

    Roy, Anirban; Seidel, Robert; Kumar, Gaurav; Bradforth, Stephen E

    2018-04-12

    Direct measurements of the valence ionization energies and the reorganization energies of the three aromatic amino acids, l-tyrosine, l-tryptophan, and l-phenylalanine, in aqueous solution using the liquid microjet technique and two different photoemission methods-X-ray photoelectron spectroscopy (XPS) at 175 eV photon energy and resonant two-photon ionization (R2PI) using 2 × 267 nm (2 × 4.64 eV) UV laser light-are reported. l-Tryptophan has the lowest vertical ionization energy, 7.3 eV, followed by tyrosine (7.8 eV) and phenylalanine (∼8.7 eV). Essentially, no variation in recovered orbital energies is observed comparing near threshold ionization to X-ray ionization. Superior sensitivity of the (background-free) R2PI scheme for solutions with very low solute concentration (<2 mM) is demonstrated in contrast to the single-photon XPS measurements, which often requires solute concentrations of 0.1-1 molar. This higher sensitivity along with chemical selectivity of the R2PI technique can be exploited for both spectroscopic assignment and as an analytical tool. The nature of the adiabatic ionization energy for the three aromatic amino acids has been explored by the R2PI approach and by empirically formulating the correlation between the estimated ionization onset with electronic and nuclear relaxation on the excited state surface. Our results have implications for understanding one-electron transfer within enzymes and in redox situations where (ir)reversible deprotonation occurs such as those manifest in the biochemistry of oxidation damage.

  12. Resonant laser printing of structural colors on high-index dielectric metasurfaces

    DEFF Research Database (Denmark)

    Zhu, Xiaolong; Yan, Wei; Levy, Uriel

    2017-01-01

    -dependent resonances. Strong on-resonance energy absorption under pulsed laser irradiation locally elevates the lattice temperature (exceeding 1200 K) in an ultrashort time scale (1 ns). This forms the basis for resonant laser printing, where rapid melting allows for surface energy-driven morphology changes...

  13. Spin dynamics in relativistic ionization with highly charged ions in super-strong laser fields

    International Nuclear Information System (INIS)

    Klaiber, Michael; Yakaboylu, Enderalp; Bauke, Heiko; Hatsagortsyan, Karen Z; Müller, Carsten; Paulus, Gerhard G

    2014-01-01

    Spin dynamics and induced spin effects in above-threshold ionization of hydrogenlike highly charged ions in super-strong laser fields are investigated. Spin-resolved ionization rates in the tunnelling regime are calculated by employing two versions of a relativistic Coulomb-corrected strong-field approximation (SFA). An intuitive simpleman model is developed which explains the derived scaling laws for spin flip and spin asymmetry effects. The intuitive model as well as our ab initio numerical simulations support the analytical results for the spin effects obtained in the dressed SFA where the impact of the laser field on the electron spin evolution in the bound state is taken into account. In contrast, the standard SFA is shown to fail in reproducing spin effects in ionization even at a qualitative level. The anticipated spin-effects are expected to be measurable with modern laser techniques combined with an ion storage facility. (paper)

  14. Laser mass spectrometry of chemical warfare agents using ultrashort laser pulses

    International Nuclear Information System (INIS)

    Weickhardt, C.; Grun, C.; Grotemeyer, J.

    1998-01-01

    Fast relaxation processes in excited molecules such as IC, ISC, and fragmentation are observed in many environmentally and technically relevant substances. They cause severe problems to resonance ionization mass spectrometry because they reduce the ionization yield and lead to mass spectra which do not allow the identification of the compound. By the use of ultrashort laser pulses these problems can be overcome and the advantages of REMPI over conventional ionization techniques in mass spectrometry can be regained. This is demonstrated using soil samples contaminated with a chemical warfare agent

  15. Laser-enhanced ionization of mercury atoms in an inert atmosphere with avalanche amplification of the signal.

    Science.gov (United States)

    Clevenger, W L; Matveev, O I; Cabredo, S; Omenetto, N; Smith, B W; Winefordner, J D

    1997-07-01

    A new method for laser-enhanced ionization detection of mercury atoms in an inert gas atmosphere is described. The method, which is based on the avalanche amplification of the signal resulting from the ionization from a selected Rydberg level reached by a three-step laser excitation of mercury vapor in a simple quartz cell, can be applied to the determination of this element in various matrices by the use of conventional cold atomization techniques. The overall (collisional + photo) ionization efficiency is investigated at different temperatures, and the avalanche amplification effect is reported for Ar and P-10 gases at atmospheric pressure. It is shown that the amplified signal is related to the number of charges produced in the laser-irradiated volume. Under amplifier noise-limited conditions, a detection limit of ∼15 Hg atoms/laser pulse in the interaction region is estimated.

  16. Silver nanostructures in laser desorption/ionization mass spectrometry and mass spectrometry imaging.

    Science.gov (United States)

    Sekuła, Justyna; Nizioł, Joanna; Rode, Wojciech; Ruman, Tomasz

    2015-09-21

    Silver nanoparticles have been successfully applied as a matrix replacement for the laser desorption/ionization time-of-flight mass spectrometry (LDI-ToF-MS). Nanoparticles, producing spectra with highly reduced chemical background in the low m/z region, are perfectly suited for low-molecular weight compound analysis and imaging. Silver nanoparticles (AgNPs) can efficiently absorb ultraviolet laser radiation, transfer energy to the analyte and promote analyte desorption, but also constitute a source of silver ions suitable for analyte cationisation. This review provides an overview of the literature on silver nanomaterials as non-conventional desorption and ionization promoters in LDI-MS and mass spectrometry imaging.

  17. Cyclotron resonance cooling by strong laser field

    International Nuclear Information System (INIS)

    Tagcuhi, Toshihiro; Mima, Kunioka

    1995-01-01

    Reduction of energy spread of electron beam is very important to increase a total output radiation power in free electron lasers. Although several cooling systems of particle beams such as a stochastic cooling are successfully operated in the accelerator physics, these cooling mechanisms are very slow and they are only applicable to high energy charged particle beams of ring accelerators. We propose here a new concept of laser cooling system by means of cyclotron resonance. Electrons being in cyclotron motion under a strong magnetic field can resonate with circular polarized electromagnetic field, and the resonance take place selectively depending on the velocity of the electrons. If cyclotron frequency of electrons is equal to the frequency of the electromagnetic field, they absorb the electromagnetic field energy strongly, but the other electrons remain unchanged. The absorbed energy will be converted to transverse kinetic energy, and the energy will be dumped into the radiation energy through bremastrahlung. To build a cooling system, we must use two laser beams, where one of them is counter-propagating and the other is co-propagating with electron beam. When the frequency of the counter-propagating laser is tuned with the cyclotron frequency of fast electrons and the co-propagating laser is tuned with the cyclotron frequency of slow electrons, the energy of two groups will approach and the cooling will be achieved. We solve relativistic motions of electrons with relativistic radiation dumping force, and estimate the cooling rate of this mechanism. We will report optimum parameters for the electron beam cooling system for free electron lasers

  18. Electron acceleration by a radially polarized laser pulse during ionization of low density gases

    Directory of Open Access Journals (Sweden)

    Kunwar Pal Singh

    2011-03-01

    Full Text Available The acceleration of electrons by a radially polarized intense laser pulse has been studied. The axial electric field of the laser is responsible for electron acceleration. The axial electric field increases with decreasing laser spot size; however, the laser pulse gets defocused sooner for smaller values and the electrons do not experience high electric field for long, reducing the energy they can reach. The electron remains confined in the electric field of the laser for longer and the electron energy peaks for the normalized laser spot size nearly equal to the normalized laser intensity parameter. Electron energy peaks for initial laser phase ϕ_{0}=π due to accelerating laser phase and decreases with transverse initial position of the electrons. The energy and angle of the emittance spectrum of the electrons generated during ionization of krypton and argon at low densities have been obtained and a right choice of laser parameters has been suggested to obtain high energy quasimonoenergetic collimated electron beams. It has been found that argon is more suitable than krypton to obtain high energy electron beams due to higher ionization potential of inner shells for the former.

  19. Examination of Laser Microprobe Vacuum Ultraviolet Ionization Mass Spectrometry with Application to Mapping Mars Returned Samples

    Science.gov (United States)

    Burton, A. S.; Berger, E. L.; Locke, D. R.; Lewis, E. K.; Moore, J. F.

    2018-04-01

    Laser microprobe of surfaces utilizing a two laser setup whereby the desorption laser threshold is lowered below ionization, and the resulting neutral plume is examined using 157nm Vacuum Ultraviolet laser light for mass spec surface mapping.

  20. Plasma diagnostics using laser-excited coupled and transmission ring resonators

    International Nuclear Information System (INIS)

    Haas, R.A.

    1976-01-01

    In this paper a simple two-level laser model is used to investigate the frequency response of coupled-cavity laser interferometers. It is found that under certain circumstances, often satisfied by molecular gas lasers, the frequency response exhibits a resonant behavior. This behavior severely complicates the interpretation of coupled-cavity laser interferometer measurements of rapidly varying plasmas. To circumvent this limitation a new type of laser interferometer plasma diagnostic with significantly improved time response was developed. In this interferometer the plasma is located in one arm of a transmission ring resonator cavity that is excited by an externally positioned laser. Thus, the laser is decoupled from the interferometer cavity and the time response of the interferometer is then limited by the Q of the ring resonator cavity. This improved time response is acquired without loss of spatial resolution, but requires a more sensitive signal detector since the laser is no longer used as a detector as it is in conventional coupled-cavity laser interferometers. Thus, the new technique incorporates the speed of the Mach--Zender interferometer and the sensitivity of the coupled-cavity laser interferometer. The basic operating principles of this type of interferometer have been verified using a CO 2 laser

  1. Identification of Fatty Acids, Phospholipids, and Their Oxidation Products Using Matrix-Assisted Laser Desorption Ionization Mass Spectrometry and Electrospray Ionization Mass Spectrometry

    Science.gov (United States)

    Harmon, Christopher W.; Mang, Stephen A.; Greaves, John; Finlayson-Pitts, Barbara J.

    2010-01-01

    Electrospray ionization mass spectrometry (ESI-MS) and matrix-assisted laser desorption ionization mass spectrometry (MALDI-MS) have found increasing application in the analysis of biological samples. Using these techniques to solve problems in analytical chemistry should be an essential component of the training of undergraduate chemists. We…

  2. Microwave Triggered Laser Ionization of Air

    Science.gov (United States)

    Vadiee, Ehsan; Prasad, Sarita; Jerald Buchenauer, C.; Schamiloglu, Edl

    2012-10-01

    The goal of this work is to study the evolution and dynamics of plasma expansion when a high power microwave (HPM) pulse is overlapped in time and space on a very small, localized region of plasma formed by a high energy laser pulse. The pulsed Nd:YAG laser (8 ns, 600mJ, repetition rate 10 Hz) is focused to generate plasma filaments in air with electron density of 10^17/cm^3. When irradiated with a high power microwave pulse these electrons would gain enough kinetic energy and further escalate avalanche ionization of air due to elastic electron-neutral collisions thereby causing an increased volumetric discharge region. An X-band relativistic backward wave oscillator(RBWO) at the Pulsed Power,Beams and Microwaves laboratory at UNM is constructed as the microwave source. The RBWO produces a microwave pulse of maximum power 400 MW, frequency of 10.1 GHz, and energy of 6.8 Joules. Special care is being given to synchronize the RBWO and the pulsed laser system in order to achieve a high degree of spatial and temporal overlap. A photodiode and a microwave waveguide detector will be used to ensure the overlap. Also, a new shadowgraph technique with a nanosecond time resolution will be used to detect changes in the shock wave fronts when the HPM signal overlaps the laser pulse in time and space.

  3. Resonance-enhanced multiphoton ionization photoelectron spectroscopy of even-parity autoionizing Rydberg states of atomic sulphur

    NARCIS (Netherlands)

    Woutersen, S.; de Milan, J.B.; de Lange, C.A.; Buma, W.J.

    1997-01-01

    Several previously unobserved Rydberg states of the sulphur atom above the lowest ionization threshold are identified and assigned using (2 + 1) resonance-enhanced multiphoton-ionization photoelectron spectroscopy. All states were accessed by two-photon transitions from either the 3P ground or the

  4. Dynamical resonance shift and unification of resonances in short-pulse laser-cluster interaction

    Science.gov (United States)

    Mahalik, S. S.; Kundu, M.

    2018-06-01

    Pronounced maximum absorption of laser light irradiating a rare-gas or metal cluster is widely expected during the linear resonance (LR) when Mie-plasma wavelength λM of electrons equals the laser wavelength λ . On the contrary, by performing molecular dynamics (MD) simulations of an argon cluster irradiated by short 5-fs (FWHM) laser pulses it is revealed that, for a given laser pulse energy and a cluster, at each peak intensity there exists a λ —shifted from the expected λM—that corresponds to a unified dynamical LR at which evolution of the cluster happens through very efficient unification of possible resonances in various stages, including (i) the LR in the initial time of plasma creation, (ii) the LR in the Coulomb expanding phase in the later time, and (iii) anharmonic resonance in the marginally overdense regime for a relatively longer pulse duration, leading to maximum laser absorption accompanied by maximum removal of electrons from cluster and also maximum allowed average charge states for the argon cluster. Increasing the laser intensity, the absorption maxima is found to shift to a higher wavelength in the band of λ ≈(1 -1.5 ) λM than permanently staying at the expected λM. A naive rigid sphere model also corroborates the wavelength shift of the absorption peak as found in MD and unequivocally proves that maximum laser absorption in a cluster happens at a shifted λ in the marginally overdense regime of λ ≈(1 -1.5 ) λM instead of λM of LR. The present study is important for guiding an optimal condition laser-cluster interaction experiment in the short-pulse regime.

  5. High-efficiency generation of pulsed Lyman-α radiation by resonant laser wave mixing in low pressure Kr-Ar mixture.

    Science.gov (United States)

    Saito, Norihito; Oishi, Yu; Miyazaki, Koji; Okamura, Kotaro; Nakamura, Jumpei; Louchev, Oleg A; Iwasaki, Masahiko; Wada, Satoshi

    2016-04-04

    We report an experimental generation of ns pulsed 121.568 nm Lyman-α radiation by the resonant nonlinear four-wave mixing of 212.556 nm and 845.015 nm radiation pulses providing a high conversion efficiency 1.7x10-3 with the output pulse energy 3.6 μJ achieved using a low pressure Kr-Ar mixture. Theoretical analysis shows that this efficiency is achieved due to the advantage of using (i) the high input laser intensities in combination with (ii) the low gas pressure allowing us to avoid the onset of full-scale discharge in the laser focus. In particular, under our experimental conditions the main mechanism of photoionization caused by the resonant 2-photon 212.556 nm radiation excitation of Kr atoms followed by the 1-photon ionization leads to ≈17% loss of Kr atoms and efficiency loss only by the end of the pulse. The energy of free electrons, generated by 212.556 nm radiation via (2 + 1)-photon ionization and accelerated mainly by 845.015 nm radiation, remains during the pulse below the level sufficient for the onset of full-scale discharge by the electron avalanche. Our analysis also suggests that ≈30-fold increase of 845.015 nm pulse energy can allow one to scale up the L-α radiation pulse energy towards the level of ≈100 μJ.

  6. Technology of discharge and laser resonators for high power CO2 lasers. Koshutsuryoku CO2 laser ni tsukawareru hoden reiki laser kyoshinki gijutsu

    Energy Technology Data Exchange (ETDEWEB)

    Takenaka, Y.; Kuzumoto, M. (Mitsubishi Electric Corp., Tokyo (Japan))

    1994-03-20

    This paper describes discharge excitation technology and resonator technology as basic technologies for high power CO2 lasers. As a result of progress in high-frequency power element techniques, the discharge excitation technology now generally uses laser excitation using AC discharge of capacity coupling type. Its representative example is silent discharge (SD) excitation. This is a system to excite laser by applying high voltages with as high frequency as 100 kHz to 1 MHz across a pair of electrodes covered with a dielectric material. The system maintains stability in discharge even if power supply voltage amplitude is modulated, and easily provides pulse outputs. Discharge excitation for diffusion cooled type CO2 laser generates a discharge in a gap with a gap length of about 2 mm, and can perform gas cooling by means of thermal conduction of gas, whereas a compact resonator can be fabricated. A resonator for the diffusion cooled type CO2 laser eliminates gas circulation and cooling systems, hence the device can be made more compact. A report has been given that several of these compact resonators were combined, from which a laser output of 85W was obtained by using RF discharge of 2kW. 43 refs., 21 figs.

  7. Three-photon resonances due to autoionizing states in calcium

    Energy Technology Data Exchange (ETDEWEB)

    Zawadzka, A.; Dygdala, R.S.; Raczynski, A.; Zaremba, J.; Kobus, J. [Instytut Fizyki, Uniwersytet M Kopernika w Toruniu, Torun (Poland)

    2002-04-28

    In the present study we have investigated three-photon ionization in Ca in which autoionizing states are engaged. The two-photon resonant process (from the Ca ground state 4s{sup 2} {sup 1}S{sub 0}) occurred through or at least in the vicinity of one of the following states: 4s4d {sup 1}D{sub 2}, 4p{sup 2} {sup 3}P{sub 2}, 4s6s {sup 1}S{sub 0}, 4p{sup 2} {sup 1}D{sub 2} and 4p{sup 2} {sup 1}S{sub 0}, with the third photon either reaching the continuum directly or one of the autoionizing states. The three-photon resonant transitions to 3dmp, mf: {sup 1}P{sub 1}, {sup 3}P{sub 1} and {sup 3}D{sub 1} autoionizing states for m up to 21 have been observed. Some of the autoionizing resonances which we have found had not been observed before in a high-resolution one-photon absorption experiment (for J=1) and in multiphoton experiments (for J=3). We have compared the ionization signal as a function of the laser detuning and the laser intensity with theoretical curves obtained within a simple model (three-level atom + one-mode laser field). This gives information about the order of magnitude of the three-photon ionization probability through autoionizing states. (author)

  8. Ratios of double to single ionization of He and Ne by strong 400-nm laser pulses using the quantitative rescattering theory

    Science.gov (United States)

    Chen, Zhangjin; Li, Xiaojin; Zatsarinny, Oleg; Bartschat, Klaus; Lin, C. D.

    2018-01-01

    We present numerical simulations of the ratio between double and single ionization of He and Ne by intense laser pulses at wavelengths of 390 and 400 nm, respectively. The yields of doubly charged ions due to nonsequential double ionization (NSDI) are obtained by employing the quantitative rescattering (QRS) model. In this model, the NSDI ionization probability is expressed as a product of the returning electron wave packet (RWP) and the total scattering cross sections for laser-free electron impact excitation and electron impact ionization of the parent ion. According to the QRS theory, the same RWP is also responsible for the emission of high-energy above-threshold ionization photoelectrons. To obtain absolute double-ionization yields, the RWP is generated by solving the time-dependent Schrödinger equation (TDSE) within a one-electron model. The same TDSE results can also be taken to obtain single-ionization yields. By using the TDSE results to calibrate single ionization and the RWP obtained from the strong-field approximation, we further simplify the calculation such that the nonuniform laser intensity distribution in the focused laser beam can be accounted for. In addition, laser-free electron impact excitation and ionization cross sections are calculated using the state-of-the-art many-electron R -matrix theory. The simulation results for double-to-single-ionization ratios are found to compare well with experimental data and support the validity of the nonsequential double-ionization mechanism for the covered intensity region.

  9. Electron impact ionization of B-like ion N2+. Resonance enhancement of the single-channel cross section

    International Nuclear Information System (INIS)

    Li Guohe; Qian Xingzhong; Pan Soufu

    1998-01-01

    The electron impact ionization cross sections of B-like ion N 2+ are calculated in the Coulomb-Born no exchange approximation by using R-matrix method, and the single differential cross section is given. The calculated results exhibit the Rydberg series of resonances. The resonance enhancement of the single-channel cross section is significantly greater than direct ionization cross section. It is agreement with that of Chidichimo

  10. Study on laser atomic spectroscopy

    International Nuclear Information System (INIS)

    Lee, Jong Min; Song, Kyu Seok; Jeong, Do Young; Kim, Chul Joong; Han, Phil Soon

    1992-01-01

    Electric discharge type atomic vaporizer is developed for the spectroscopic study on actinide elements. Laser induced fluorescence study on actinide elements is performed by using this high temperature type atomizer. For the effective photoionization of elements, copper vapor laser pumped dye laser and electron beam heating type atomic vaporizer are built and their characteristics are measured. In addition, resonance ionization mass spectroscopic analysis for lead sample as well as laser induced fluorescence study on uranium sample in solution phase is made. (Author)

  11. Ionization dynamics of a xenon atom in super-strong laser fields

    International Nuclear Information System (INIS)

    Yamakawa, Koichi; Akahane, Yutaka; Fukuda, Yuji; Aoyama, Makoto; Inoue, Norihiro; Ueda, Hideki; Utsumi, Takayuki

    2003-12-01

    We report on detailed investigations of ionization dynamics of a xenon atom exposed to intense 800-nm pulses of 20-fs duration in the extensive intensity range from 10 13 to 10 18 W/cm 2 . Ion yields of Xe + to Xe 20+ were observed as a function of laser intensity and compared with the results from a single active electron (SAE) based Ammosov-Delone-Krainov (ADK) model. Unexpected ionization probabilities for lower charge states and also no interplay between the inner- and outer-shells by screening are inferred. Suppression of nonsequential ionization towards higher intensity and few optical cycle regimes is also proved. (author)

  12. Laser heating of large noble gas clusters: from the resonant to the relativistic interaction regimes

    Energy Technology Data Exchange (ETDEWEB)

    Gumbrell, E T; Moore, A S; Clark, E L; Garbett, W J; Comley, A J; Edwards, R D; Eagleton, R E [Plasma Physics Division, AWE Aldermaston, Reading RG7 4PR (United Kingdom); Lazarus, J A; Nilson, P M; Robinson, J S; Hohenberger, M; Symes, D R; Smith, R A [Blackett Laboratory, Imperial College, London SW7 2BZ (United Kingdom); Clarke, R J [Rutherford Appleton Laboratory, Chilton OX11 0QX (United Kingdom)], E-mail: edward.gumbrell@awe.co.uk, E-mail: r.a.smith@imperial.ac.uk

    2008-12-15

    Wide-ranging measurements of sub-picosecond laser interactions with large noble gas cluster targets have been conducted in order to help clarify the nature and extent of the underlying laser-plasma heating. Within the sub-relativistic vacuum irradiance range of 10{sup 16}-10{sup 17} W cm{sup -2}, we find that electron temperatures measured with continuum x-ray spectroscopy exhibit a pronounced multi-keV enhancement. Analysis indicates this behaviour to be consistent with collisional or collisionless resonant heating mechanisms. We also present the first measurements of laser-to-cluster energy deposition at relativistic vacuum irradiances, our data demonstrating absorption fractions of 90% or more. Optical probing was used to resolve the onset of a supersonic ionization front resulting from this very high absorption, and shows that despite significant pre-focus heating, the greatest plasma energy densities can be generated about the vacuum focus position. Electron energy spectra measurements confirm that laser-plasma super-heating occurs, and together with ion data establish that relativistic laser-plasma coupling in atomic clusters can take place without significant MeV particle beam production. In conjunction with optical self-emission data, the optical probing also indicates laser pre-pulse effects at peak vacuum irradiance of 5 x 10{sup 19} W cm{sup -2}. Laser absorption, plasma heating and energy transport data are supported throughout with analytical and numerical modelling.

  13. An initial study on atmospheric pressure ion transport by laser ionization and electrostatic fields.

    OpenAIRE

    Peralta Conde, Álvaro; Romero, Carolina; Boyero, Juan; Apiñaniz Aginako, Jon Imanol; Raposo Funcia, Cesar; Roso Franco, Luis; Padilla Moreno, Carlos Manuel

    2014-01-01

    Laser ionization of mixtures of gases at atmospheric pressure and the subsequent transport through electrostatic field is studied. A prototype is designed to perform the transport and detection of the ions. Relevance of the composition of the mixture of gases and ionization parameters is shown

  14. CrossRef Large numbers of cold positronium atoms created in laser-selected Rydberg states using resonant charge exchange

    CERN Document Server

    McConnell, R; Kolthammer, WS; Richerme, P; Müllers, A; Walz, J; Grzonka, D; Zielinski, M; Fitzakerley, D; George, MC; Hessels, EA; Storry, CH; Weel, M

    2016-01-01

    Lasers are used to control the production of highly excited positronium atoms (Ps*). The laser light excites Cs atoms to Rydberg states that have a large cross section for resonant charge-exchange collisions with cold trapped positrons. For each trial with 30 million trapped positrons, more than 700 000 of the created Ps* have trajectories near the axis of the apparatus, and are detected using Stark ionization. This number of Ps* is 500 times higher than realized in an earlier proof-of-principle demonstration (2004 Phys. Lett. B 597 257). A second charge exchange of these near-axis Ps* with trapped antiprotons could be used to produce cold antihydrogen, and this antihydrogen production is expected to be increased by a similar factor.

  15. Radiation reaction effect on laser driven auto-resonant particle acceleration

    International Nuclear Information System (INIS)

    Sagar, Vikram; Sengupta, Sudip; Kaw, P. K.

    2015-01-01

    The effects of radiation reaction force on laser driven auto-resonant particle acceleration scheme are studied using Landau-Lifshitz equation of motion. These studies are carried out for both linear and circularly polarized laser fields in the presence of static axial magnetic field. From the parametric study, a radiation reaction dominated region has been identified in which the particle dynamics is greatly effected by this force. In the radiation reaction dominated region, the two significant effects on particle dynamics are seen, viz., (1) saturation in energy gain by the initially resonant particle and (2) net energy gain by an initially non-resonant particle which is caused due to resonance broadening. It has been further shown that with the relaxation of resonance condition and with optimum choice of parameters, this scheme may become competitive with the other present-day laser driven particle acceleration schemes. The quantum corrections to the Landau-Lifshitz equation of motion have also been taken into account. The difference in the energy gain estimates of the particle by the quantum corrected and classical Landau-Lifshitz equation is found to be insignificant for the present day as well as upcoming laser facilities

  16. Correlated Keldysh-Faisal-Reiss theory of above-threshold double ionization of He in intense laser fields

    International Nuclear Information System (INIS)

    Becker, A.; Faisal, F.H.M.

    1994-01-01

    We have developed a correlated Keldysh-Faisal-Reiss theory of laser-induced double ionization of a two-electron atom. The basic N-photon T matrix and the expression for N-photon triple-differential rates or cross sections (TDCS's) are derived. The theory is applied to investigate the TDCS's for very-high-order multiphoton double ionization of He with lasers of wavelength λ=248 nm and λ=617 nm. Comparison with the uncorrelated results reveals a dramatic influence of the final-state e-e correlation on the above-threshold TDCS's to be measured in coincidence experiments in intense laser fields. The limiting case of the TDCS's for weak-field double ionization of He by a synchrotron photon is also investigated; the results confirm the earlier theoretical findings and recent experimental results in that case

  17. Nd:YAG (2 omega) pumped dye laser using self-filtering unstable resonator

    CERN Document Server

    Rahimian, K; Hariri, H

    2002-01-01

    A self-filtering unstable resonator with a magnification of M=-3 in a Nd:YAG (2 omega) dye laser has been studied. The dye solution is Rhodamine 6 G in alcohol with the concentration of 5*10 sub - 3 Mol/lit. The spatial intensity distribution of the resonator has been compared has been compared with that of a plane-parallel resonator of equal length. The output energy in both configurations are comparable (20 mu J ,and 26 mu J ,respectively). A significant difference between these two resonators is the laser beam divergence, where beam divergences of 0.77 mrad for the self-filtering unstable resonator and 1.6 mrad for the plane-parallel resonator have been measured. The brightness corresponding to these two resonators are 1.5* 10 sub 1 1 and 2.2* 10 sub 1 0W.cm sub - 2.Sr sub - 1, and the pulse widths are 7 and 17 ns, respectively. These figures show clearly that laser resonator based on the self-filtering unstable resonator design an increase the laser brightness a factor of 10, with a beam divergence of a f...

  18. Coherent combs in ionization by intense and short laser pulses

    Energy Technology Data Exchange (ETDEWEB)

    Krajewska, K., E-mail: Katarzyna.Krajewska@fuw.edu.pl [Institute of Theoretical Physics, Faculty of Physics, University of Warsaw, Pasteura 5, 02-093 Warszawa (Poland); Department of Physics and Astronomy, University of Nebraska, Lincoln, NE 68588-0299 (United States); Kamiński, J.Z., E-mail: Jerzy.Kaminski@fuw.edu.pl [Institute of Theoretical Physics, Faculty of Physics, University of Warsaw, Pasteura 5, 02-093 Warszawa (Poland)

    2016-03-22

    Photoionization of positive ions by a train of intense, short laser pulses is investigated within the relativistic strong field approximation, using the velocity gauge. The formation of broad peak structures in the high-energy domain of photoelectrons is observed and interpreted. The emergence of coherent photoelectron energy combs within these structures is demonstrated, and it is interpreted as the consequence of the Fraunhofer-type interference/diffraction of probability amplitudes of ionization from individual pulses comprising the train. Extensions to the coherent angular combs are also studied, and effects related to the radiation pressure are presented. - Highlights: • We develop relativistic Strong-Field Approximation for ionization by intense and short laser pulses of arbitrary spectral compositions. • We show that the consistent interpretation of results is provided by the Keldysh-type saddle point analysis of probability amplitudes. • We derive a general Fraunhofer-type interference/diffraction formula for finite train of pulses. • We study the coherent combs in photoelectron probability distributions.

  19. Development of resonance ionization spectroscopy system for fusion material surface analysis

    Energy Technology Data Exchange (ETDEWEB)

    Iguchi, Tetsuo [Tokyo Univ., Tokai, Ibaraki (Japan). Nuclear Engineering Research Lab.; Satoh, Yasushi; Nakazawa, Masaharu

    1996-10-01

    A Resonance Ionization Spectroscopy (RIS) system is now under development aiming at in-situ observation and analysis neutral particles emitted from fusion material surfaces under irradiation of charged particles and neutrons. The basic performance of the RIS system was checked through a preliminary experiment on Xe atom detection. (author)

  20. Generation of attosecond electron beams in relativistic ionization by short laser pulses

    Science.gov (United States)

    Cajiao Vélez, F.; Kamiński, J. Z.; Krajewska, K.

    2018-03-01

    Ionization by relativistically intense short laser pulses is studied in the framework of strong-field quantum electrodynamics. Distinctive patterns are found in the energy probability distributions of photoelectrons, which are sensitive to the properties of a driving laser field. It is demonstrated that these electrons are generated in the form of solitary attosecond wave packets. This is particularly important in light of various applications of attosecond electron beams such as in ultrafast electron diffraction and crystallography, or in time-resolved electron microscopy of physical, chemical, and biological processes. We also show that, for intense laser pulses, high-energy ionization takes place in narrow regions surrounding the momentum spiral, the exact form of which is determined by the shape of a driving pulse. The self-intersections of the spiral define the momenta for which the interference patterns in the energy distributions of photoelectrons are observed. Furthermore, these interference regions lead to the synthesis of single-electron wave packets characterized by coherent double-hump structures.

  1. Interference of laser-induced resonances in the continuous structures of a helium atom

    International Nuclear Information System (INIS)

    Magunov, A I; Strakhova, S I

    2003-01-01

    Coherent effects in the interference of overlapping laser-induced resonances in helium atoms are considered. The simultaneous action of single-mode radiation of the 294-nm second harmonic of a cw dye laser and a 1064-nm Nd:YAG laser on helium atoms provides the overlap of two resonances induced by transitions from the 1s2s 1 S and 1s4s 1 S helium levels. The shape of the overlapping laser-induced resonances in the rotating-wave approximation is described by analytic expressions, which depend on the laser radiation intensities and the ratio of laser frequencies. (nonlinear optical phenomena)

  2. Application of resonance ionisation spectroscopy in atomic physics

    International Nuclear Information System (INIS)

    Kluge, H.J.

    1997-01-01

    Resonance ionization spectroscopy (RIS) and resonance ionization mass spectroscopy (RIMS) techniques have proved to be a powerful tool in atomic spectroscopy and trace analysis. Detailed atomic spectroscopy can be performed on samples containing less than 10 12 atoms. This sensitivity is especially important for investigating atomic properties of transuranium elements. RIMS is especially suitable for ultra trace determination of long lived radioactive isotopes. The extremely low detection limits allow analysis of samples in the sub-femtogram regime. High elemental and isotopic selectivity can be obtained. To produce isobarically pure ion beams, a RIS based laser ion source can be used

  3. Thin films deposited by laser ablation for the measurement of the ionizing and non-ionizing radiation; Peliculas delgadas depositadas por ablacion laser para la medicion de radiacion ionizante y no ionizante

    Energy Technology Data Exchange (ETDEWEB)

    Villarreal B, J.E.; Escobar A, L.; Camps, E.; Romero, S.; Gonzalez, P.; Salinas, B. [Instituto Nacional de Investigaciones Nucleares, A.P. 18-1027, 11801 Mexico D.F. (Mexico)

    2001-07-01

    In this work the obtained results to synthesize thin films of amorphous carbon with incorporated nitrogen and hydrogen are presented, as well as thin films of aluminium oxide using the laser ablation technique. The thin films were exposed to ionizing radiation (gamma rays of a {sup 60} Co source, beta radiation of a {sup 90} Sr source) and a non-ionizing radiation (UV radiation). The obtained results show that it is possible to obtain materials in thin film form with thickness of hundreds of nanometers, which present thermoluminescent response when being irradiated with ionizing radiation and non-ionizing radiation. (Author)

  4. Supersonic propagation of ionization waves in an underdense, laser-produced plasma

    International Nuclear Information System (INIS)

    Constantin, C.; Back, C.A.; Fournier, K.B.; Gregori, G.; Landen, O.L.; Glenzer, S.H.; Dewald, E.L.; Miller, M.C.

    2005-01-01

    A laser-driven supersonic ionization wave propagating through a millimeter-scale plasma of subcritical density up to 2-3 keV electron temperatures was observed. Propagation velocities initially ten times the sound speed were measured by means of time-resolved x-ray imaging diagnostics. The measured ionization wave trajectory is modeled analytically and by a two-dimensional radiation-hydrodynamics code. The comparison to the modeling suggests that nonlocal heat transport effects may contribute to the attenuation of the heat-wave propagation

  5. Double resonance modulation characteristics of optically injection-locked Fabry–Perot lasers

    International Nuclear Information System (INIS)

    Dorogush, E S; Afonenko, A A

    2015-01-01

    The distributed resonator model is used to show the presence of several resonance responses on the modulation characteristic of optically injection-locked Fabry–Perot lasers. The positions of the resonance peaks on the modulation characteristic are determined by the resonator length and frequency detuning of optical injection. It is shown that an appropriate choice of the resonator length and injection locking conditions allows one to obtain efficient modulation in two ranges near 40 – 60 GHz or to increase the direct modulation bandwidth up to 50 GHz. (control of laser radiation parameters)

  6. Double resonance modulation characteristics of optically injection-locked Fabry–Perot lasers

    Energy Technology Data Exchange (ETDEWEB)

    Dorogush, E S; Afonenko, A A [Belarusian State University, Minsk (Belarus)

    2015-12-31

    The distributed resonator model is used to show the presence of several resonance responses on the modulation characteristic of optically injection-locked Fabry–Perot lasers. The positions of the resonance peaks on the modulation characteristic are determined by the resonator length and frequency detuning of optical injection. It is shown that an appropriate choice of the resonator length and injection locking conditions allows one to obtain efficient modulation in two ranges near 40 – 60 GHz or to increase the direct modulation bandwidth up to 50 GHz. (control of laser radiation parameters)

  7. Laser modes and threshold condition i N-mirror resonator

    DEFF Research Database (Denmark)

    Pedersen, Christian; Skettrup, Torben

    1996-01-01

    Two formal methods for finding laser modes and threshold conditions in laser resonators containing as many as N mirrors are presented. The first method is based on an analysis determining the reflectivity and the transmittivity of an N-mirror system with gain. This is an extension of the classical...... 2 × 2 matrix method. The second method is based on self-consistency equations for the system and directly yields the circulating fields of the individual resonators. A set of rules has been proved to allow these fields to be calculated directly by means of inspection. The laser oscillation condition...

  8. Thin disk laser with unstable resonator and reduced output coupler

    Science.gov (United States)

    Gavili, Anwar; Shayganmanesh, Mahdi

    2018-05-01

    In this paper, feasibility of using unstable resonator with reduced output coupling in a thin disk laser is studied theoretically. Unstable resonator is modeled by wave-optics using Collins integral and iterative method. An Yb:YAG crystal with 250 micron thickness is considered as a quasi-three level active medium and modeled by solving rate equations of energy levels populations. The amplification of laser beam in the active medium is calculated based on the Beer-Lambert law and Rigrod method. Using generalized beam parameters method, laser beam parameters like, width, divergence, M2 factor, output power as well as near and far-field beam profiles are calculated for unstable resonator. It is demonstrated that for thin disk laser (with single disk) in spite of the low thickness of the disk which leads to low gain factor, it is possible to use unstable resonator (with reduced output coupling) and achieve good output power with appropriate beam quality. Also, the behavior of output power and beam quality versus equivalent Fresnel number is investigated and optimized value of output coupling for maximum output power is achieved.

  9. Performance appraisal studies of laser-enhanced ionization in flames - the determination of nickel in petroleum products

    International Nuclear Information System (INIS)

    Turk, G.C.; Harvilla, G.J.; Webb, J.D.; Forster, A.R.; Shell Development Co., Houston, TX; The Standard Oil Co., Cleveland, OH)

    1984-01-01

    Laser-enhanced ionization (LEI) in flames is an ultrasensitive atomic flame spectrometric technique based on the efficient thermal ionization of atomic species which have been selectively excited by tunable laser radiation. The performance of LEI for real sample analysis is presently being evaluated. A successful determination of trace Ni concentrations in heavy oil flash distillate and Standard Reference Material Fuel Oil has been performed. One gram samples were diluted into 100 to 700 mL volumes of a xylene/n-butanol solvent mixture and aspirated directly into an air-acetylene flame. Stepwise laser excitation of Ni was performed using a Nd:YAG pumped dual-dye laser system. Accurate and reproducible results were obtained. 17 refs., 1 fig., 1 tab

  10. Photoionization pathways and thresholds in generation of Lyman-α radiation by resonant four-wave mixing in Kr-Ar mixture

    Directory of Open Access Journals (Sweden)

    Oleg A. Louchev

    2016-09-01

    Full Text Available We develop a set of analytical approximations for the estimation of the combined effect of various photoionization processes involved in the resonant four-wave mixing generation of ns pulsed Lyman-α (L-α radiation by using 212.556 nm and 820-845 nm laser radiation pulses in Kr-Ar mixture: (i multi-photon ionization, (ii step-wise (2+1-photon ionization via the resonant 2-photon excitation of Kr followed by 1-photon ionization and (iii laser-induced avalanche ionization produced by generated free electrons. Developed expressions validated by order of magnitude estimations and available experimental data allow us to identify the area for the operation under high input laser intensities avoiding the onset of full-scale discharge, loss of efficiency and inhibition of generated L-α radiation. Calculations made reveal an opportunity for scaling up the output energy of the experimentally generated pulsed L-α radiation without significant enhancement of photoionization.

  11. Photoionization pathways and thresholds in generation of Lyman-α radiation by resonant four-wave mixing in Kr-Ar mixture

    Science.gov (United States)

    Louchev, Oleg A.; Saito, Norihito; Oishi, Yu; Miyazaki, Koji; Okamura, Kotaro; Nakamura, Jumpei; Iwasaki, Masahiko; Wada, Satoshi

    2016-09-01

    We develop a set of analytical approximations for the estimation of the combined effect of various photoionization processes involved in the resonant four-wave mixing generation of ns pulsed Lyman-α (L-α ) radiation by using 212.556 nm and 820-845 nm laser radiation pulses in Kr-Ar mixture: (i) multi-photon ionization, (ii) step-wise (2+1)-photon ionization via the resonant 2-photon excitation of Kr followed by 1-photon ionization and (iii) laser-induced avalanche ionization produced by generated free electrons. Developed expressions validated by order of magnitude estimations and available experimental data allow us to identify the area for the operation under high input laser intensities avoiding the onset of full-scale discharge, loss of efficiency and inhibition of generated L-α radiation. Calculations made reveal an opportunity for scaling up the output energy of the experimentally generated pulsed L-α radiation without significant enhancement of photoionization.

  12. Laser Beam and Resonator Calculations on Desktop Computers.

    Science.gov (United States)

    Doumont, Jean-Luc

    There is a continuing interest in the design and calculation of laser resonators and optical beam propagation. In particular, recently, interest has increased in developing concepts such as one-sided unstable resonators, supergaussian reflectivity profiles, diode laser modes, beam quality concepts, mode competition, excess noise factors, and nonlinear Kerr lenses. To meet these calculation needs, I developed a general-purpose software package named PARAXIA ^{rm TM}, aimed at providing optical scientists and engineers with a set of powerful design and analysis tools that provide rapid and accurate results and are extremely easy to use. PARAXIA can handle separable paraxial optical systems in cartesian or cylindrical coordinates, including complex-valued and misaligned ray matrices, with full diffraction effects between apertures. It includes the following programs:. ABCD provides complex-valued ray-matrix and gaussian -mode analyses for arbitrary paraxial resonators and optical systems, including astigmatism and misalignment in each element. This program required that I generalize the theory of gaussian beam propagation to the case of an off-axis gaussian beam propagating through a misaligned, complex -valued ray matrix. FRESNEL uses FFT and FHT methods to propagate an arbitrary wavefront through an arbitrary paraxial optical system using Huygens' integral in rectangular or radial coordinates. The wavefront can be multiplied by an arbitrary mirror profile and/or saturable gain sheet on each successive propagation through the system. I used FRESNEL to design a one-sided negative-branch unstable resonator for a free -electron laser, and to show how a variable internal aperture influences the mode competition and beam quality in a stable cavity. VSOURCE implements the virtual source analysis to calculate eigenvalues and eigenmodes for unstable resonators with both circular and rectangular hard-edged mirrors (including misaligned rectangular systems). I used VSOURCE to

  13. Unstable Resonator Retrofitted Handheld Laser Designator

    Science.gov (United States)

    1978-06-01

    retrofitted with a negative-branch unstable resona- tor laser and hybrid pump cavity in place of the conventional plane-mirror/ porro prism resonator and...directed by prism B to an expanding telescope, shared with the viewing system of the designator. The actual, unfolded resonator length is approxi...was performed based on using a plane- parallel cavity consisting of a 47% reflectivity output coupler, porro - prism reflector, and the same LiNb03

  14. Fast elastic e-H(2s) scattering in laser fields

    International Nuclear Information System (INIS)

    Vucic, S.; Hewitt, R.; Hewitt, R.

    1997-01-01

    A numerical method for the evaluation of the Born endash Floquet amplitude for laser-assisted scattering is proposed for the case when a large basis set is required to achieve convergence. The method is applied to analyze the elastic scattering of fast electrons by the H(2s) state in a low-intensity laser field of varying frequency and to study the resonant scattering with increasing laser intensity. While the behavior of an atom in a resonant field of low intensity is determined by virtual transitions between resonant levels, at high intensity a great number of nonresonant virtual transitions may significantly influence laser-assisted processes. As a consequence, the attenuation of resonant effects could appear, as well as the open-quotes localclose quotes stabilization of the atom against ionization. copyright 1997 The American Physical Society

  15. Non-resonant two and three-photon ionization of the singlet and triplet metastable helium atoms of an atomic jet

    International Nuclear Information System (INIS)

    Mathieu, Bernard.

    1978-01-01

    The three-photon ionization cross-section of the helium metastables He(2 1 S) and He(2 3 S) is determined by means of the linearly polarized radiation of a pulsed ruby laser with an emission wavelength equal to 6946.4 A at 19 0 C. Two-photon ionization, obtained by doubling the laser beam frequency, is also studied [fr

  16. Self-optimizing approach for automated laser resonator alignment

    Science.gov (United States)

    Brecher, C.; Schmitt, R.; Loosen, P.; Guerrero, V.; Pyschny, N.; Pavim, A.; Gatej, A.

    2012-02-01

    Nowadays, the assembly of laser systems is dominated by manual operations, involving elaborate alignment by means of adjustable mountings. From a competition perspective, the most challenging problem in laser source manufacturing is price pressure, a result of cost competition exerted mainly from Asia. From an economical point of view, an automated assembly of laser systems defines a better approach to produce more reliable units at lower cost. However, the step from today's manual solutions towards an automated assembly requires parallel developments regarding product design, automation equipment and assembly processes. This paper introduces briefly the idea of self-optimizing technical systems as a new approach towards highly flexible automation. Technically, the work focuses on the precision assembly of laser resonators, which is one of the final and most crucial assembly steps in terms of beam quality and laser power. The paper presents a new design approach for miniaturized laser systems and new automation concepts for a robot-based precision assembly, as well as passive and active alignment methods, which are based on a self-optimizing approach. Very promising results have already been achieved, considerably reducing the duration and complexity of the laser resonator assembly. These results as well as future development perspectives are discussed.

  17. Lifetime measurement of the cesium 6P3/2 state using ultrafast laser-pulse excitation and ionization

    International Nuclear Information System (INIS)

    Sell, J. F.; Patterson, B. M.; Ehrenreich, T.; Brooke, G.; Scoville, J.; Knize, R. J.

    2011-01-01

    We report a precision measurement of the cesium 6P 3/2 excited-state lifetime. Two collimated, counterpropagating thermal Cs beams cross perpendicularly to femtosecond pulsed laser beams. High timing accuracy is achieved from having excitation and ionization laser pulses which originate from the same mode-locked laser. Using pulse selection we vary the separation in time between excitation and ionization laser pulses while counting the ions produced. We obtain a Cs 6P 3/2 lifetime of 30.460(38) ns, which is a factor of two improvement from previous measurements and with an uncertainty of 0.12%, is one of the most accurate lifetime measurements on record.

  18. Depth profiling of inks in authentic and counterfeit banknotes by electrospray laser desorption ionization/mass spectrometry.

    Science.gov (United States)

    Kao, Yi-Ying; Cheng, Sy-Chyi; Cheng, Chu-Nian; Shiea, Jentaie

    2016-01-01

    Electrospray laser desorption ionization is an ambient ionization technique that generates neutrals via laser desorption and ionizes those neutrals in an electrospray plume and was utilized to characterize inks in different layers of copy paper and banknotes of various currencies. Depth profiling of inks was performed on overlapping color bands on copy paper by repeatedly scanning the line with a pulsed laser beam operated at a fixed energy. The molecules in the ink on a banknote were desorbed by irradiating the banknote surface with a laser beam operated at different energies, with results indicating that different ions were detected at different depths. The analysis of authentic $US100, $100 RMB and $1000 NTD banknotes indicated that ions detected in 'color-shifting' and 'typography' regions were significantly different. Additionally, the abundances of some ions dramatically changed with the depth of the aforementioned regions. This approach was used to distinguish authentic $1000 NTD banknotes from counterfeits. Copyright © 2015 John Wiley & Sons, Ltd. Copyright © 2015 John Wiley & Sons, Ltd.

  19. A four-component Dirac theory of ionization of a hydrogen molecular ion in a super-intense laser field

    International Nuclear Information System (INIS)

    Faisal, F H M

    2009-01-01

    In this communication, a four-component Dirac theory of ionization of a hydrogen molecular ion, H + 2 , in a super-intense laser field is presented. Analytic expressions for the spin-specific as well as the total ionization currents emitted from the ground state of the ion are derived. The results are given for arbitrary intensity, frequency, wavenumber and polarization of the field, and for the up or down spin of the bound and ionized states of the electron. They also apply for the case of inner-shell ionization of analogous heavier diatomic molecular ions. The presence of molecular two-slit interference effect, first found in the non-relativistic case, the spin-flip ionization current, and an asymmetry of the up- and down-spin currents similar to that predicted in the atomic case, is found to hold for the present relativistic molecular ionic case as well. The possibility of controlling the spin of the dominant ionization current in any direction by simply selecting the handedness of a circularly polarized incident laser field is pointed out. Finally, we note that the present results obtained within the strong field 'KFR' ansatz open up the way for an analogous fully relativistic four-component treatment for ionization of polyatomic molecules and clusters in super-intense laser fields. (fast track communication)

  20. Dissociative multiple ionization of diatomic molecules by extreme-ultraviolet free-electron-laser pulses

    DEFF Research Database (Denmark)

    Madsen, Lars Bojer; Leth, Henriette Astrup

    2011-01-01

    Nuclear dynamics in dissociative multiple ionization processes of diatomic molecules exposed to extreme-ultraviolet free-electron-laser pulses is studied theoretically using the Monte Carlo wave packet approach. By simulated detection of the emitted electrons, the model reduces a full propagation...... of the system to propagations of the nuclear wave packet in one specific electronic charge state at a time. Suggested ionization channels can be examined, and kinetic energy release spectra for the nuclei can be calculated and compared with experiments. Double ionization of O2 is studied as an example, and good...

  1. Silver nanoparticles as matrix for laser desorption/ionization mass spectrometry of peptides

    International Nuclear Information System (INIS)

    Hua Lin; Chen Jianrong; Ge Liya; Tan, Swee Ngin

    2007-01-01

    Silver nanoparticle synthesized from chemical reduction has been successfully utilized as a matrix in matrix-assisted laser desorption/ionization time-of-flight mass spectrometry (MALDI-TOF-MS) of peptides. Acting as a substrate to adsorb analytes, as well as a transmission medium for UV laser, silver nanoparticle was found to assist in the desorption/ionization of peptides with little or no induced fragmentation. The size of the nanoparticle was typically in the range of 160 ± 20 nm. One of the key advantages of silver nanoparticle for peptides analysis is its simple step for on-probe sample preparation. In addition, it also minimizes the interferences of sodium dodecyl sulfate (SDS) surfactant background signal, resulting in cleaner mass spectra and more sensitive signal, when compared to α-cyano-4-hydroxycinnamic acid (CCA) matrix

  2. Inner-shell photo-ionized X-ray laser schemes for low-Z elements

    International Nuclear Information System (INIS)

    Moon, S.J.; Strobel, G.L.

    1994-01-01

    Gain calculations for inner-shell photo-ionized lasing in C at 45 angstrom are performed. An incident x-ray source represented by a 150 eV blackbody with a rise time of 50 fsec gives a gain of order 10 cm -1 . The x-ray source and thus the driving optical laser requirements are significantly reduced as compared to what is needed for Ne at 15 angstrom. The authors expect that existing ultra-short pulse lasers can produce the required x-ray source and thus produce a table-top x-ray laser at 45 angstrom

  3. Toward single-cell analysis by plume collimation in laser ablation electrospray ionization mass spectrometry.

    Science.gov (United States)

    Stolee, Jessica A; Vertes, Akos

    2013-04-02

    Ambient ionization methods for mass spectrometry have enabled the in situ and in vivo analysis of biological tissues and cells. When an etched optical fiber is used to deliver laser energy to a sample in laser ablation electrospray ionization (LAESI) mass spectrometry, the analysis of large single cells becomes possible. However, because in this arrangement the ablation plume expands in three dimensions, only a small portion of it is ionized by the electrospray. Here we show that sample ablation within a capillary helps to confine the radial expansion of the plume. Plume collimation, due to the altered expansion dynamics, leads to greater interaction with the electrospray plume resulting in increased ionization efficiency, reduced limit of detection (by a factor of ~13, reaching 600 amol for verapamil), and extended dynamic range (6 orders of magnitude) compared to conventional LAESI. This enhanced sensitivity enables the analysis of a range of metabolites from small cell populations and single cells in the ambient environment. This technique has the potential to be integrated with flow cytometry for high-throughput metabolite analysis of sorted cells.

  4. Multiply ionization of diethyl ether clusters by 532 nm nanosecond laser: The influence of laser intensity and the electron energy distribution

    International Nuclear Information System (INIS)

    Zhang Nazhen; Wang Weiguo; Zhao Wuduo; Han Fenglei; Li Haiyang

    2010-01-01

    Graphical abstract: The formation mechanism for multiply charged ions (C q+ and O q+ (q = 2-4)) were investigated experimentally and theoretically using a dual polarity time-of-flight mass spectrometer when diethyl ether clusters interacted with nanosecond laser pulse. - Abstract: The formation mechanism for multiply charged ions (C q+ and O q+ (q = 2-4)) were investigated using a dual polarity time-of-flight mass spectrometer when diethyl ether clusters interacted with nanosecond laser pulse. The signal intensity of multiply charged ions and electron energy was measured experimentally. It was shown that the intensity of multiply charged ions increased about 50 times when laser intensity increased from 7.6 x 10 9 to 7.0 x 10 10 W/cm 2 , then saturated as laser intensity increased further. It is interesting that the evolution of the mean value of electron energy was same to that of multiply charged ions. The theoretical calculation showed the ionization potential of atomic ions could be significantly decreased due to the effect of Coulomb screening especially at low laser intensity. It indicated that the electron ionization combined with Coulomb screening effect could explain the production of multiply charged ions in nanosecond laser field.

  5. Multiphoton ionization and fragmentation study of acetone using 308 nm laser radiation

    Science.gov (United States)

    Liu Houxiang, Li Shutao, Han Jingcheng, Zhu Rong, Guan Yifu, Wu Cunkai

    1988-10-01

    Multiphoton ionization and fragmentation (MPI-F) of acetone molecules using 308 nm laser radiation was studied by using a molecular beam and quadrupole mass spectrometer. The ion peaks of acetone molecule appear at m/e=15 and 43, corresponding to the two fragments CH3+ and CH3CO+. It is considered that these two ions are, respectively, formed by direct (2+1) and 2-photon ionization of methyl and acetyl radicals, generated by photodissociation of acetone molecule.

  6. On the fast gas ionization wave in an intense laser beam

    International Nuclear Information System (INIS)

    Fisher, V.I.

    1980-01-01

    The transfer of the adsorption zone of laser radiation along a beam is considered. It is shown that for a sufficiently strong laser beam intensity, q 0 >q tilde, the conditions of wave propagation differ principally from those known previously. In particular, the plasma temperature behind the wave front Tsup(*) decreases with the increase of q 0 , whereas the wave velocity D(q 0 ) grows faster than a linear function. The structure and laws of propagation of the ionization wave are determined

  7. Single-frequency, fully integrated, miniature DPSS laser based on monolithic resonator

    Science.gov (United States)

    Dudzik, G.; Sotor, J.; Krzempek, K.; Soboń, G.; Abramski, K. M.

    2014-02-01

    We present a single frequency, stable, narrow linewidth, miniature laser sources operating at 532 nm (or 1064 nm) based on a monolithic resonators. Such resonators utilize birefringent filters formed by YVO4 beam displacer and KTP or YVO4 crystals to force single frequency operation at 532 nm or 1064 nm, respectively. In both configurations Nd:YVO4 gain crystal is used. The resonators dimensions are 1x1x10.5 mm3 and 1x1x8.5 mm3 for green and infrared configurations, respectively. Presented laser devices, with total dimensions of 40x52x120 mm3, are fully equipped with driving electronics, pump diode, optical and mechanical components. The highly integrated (36x15x65 mm3) low noise driving electronics with implemented digital PID controller was designed. It provides pump current and resonator temperature stability of ±30 μA@650 mA and ±0,003ºC, respectively. The laser parameters can be set and monitored via the USB interface by external application. The developed laser construction is universal. Hence, the other wavelengths can be obtained only by replacing the monolithic resonator. The optical output powers in single frequency regime was at the level of 42 mW@532 nm and 0.5 W@1064 nm with the long-term fluctuations of ±0.85 %. The linewidth and the passive frequency stability under the free running conditions were Δν < 100 kHz and 3ṡ10-9@1 s integration time, respectively. The total electrical power supply consumption of laser module was only 4 W. Presented compact, single frequency laser operating at 532 nm and 1064 nm may be used as an excellent source for laser vibrometry, interferometry or seed laser for fiber amplifiers.

  8. Atomic scattering in the presence of a low-frequency laser

    International Nuclear Information System (INIS)

    Banerji, J.

    1982-01-01

    In the first four chapters of this thesis previous work on non-resonant potential scattering, resonant potential scattering and non-resonant electron-atom scattering in the presence of a low-frequency laser has been discussed and extended. Chapter 6 deals with the experimental aspects of laser-modified atomic scattering. In chapter 7, the problem of electron-atom ionizing collisions (both resonant and non-resonant) in the presence of a low-frequency laser is discussed. In the next chapter the cut-off Coulomb potential scattering in the presence of a low-frequency laser has been considered. Because of the long range of the Coulomb potential, the result deviates sharply from that obtained for short range potentials unless, of course, the collision energy is very high. Moreover, it has been suggested that the experiments are not reproducible unless the details of the cut-off Coulomb potential are spelled out

  9. Photoelectron imaging spectroscopy for (2+1) resonance-enhanced multiphoton ionization of atomic bromine

    International Nuclear Information System (INIS)

    Kim, Yong Shin; Jung, Young Jae; Kang, Wee Kyung; Jung, Kyung Hoon

    2002-01-01

    Two-photon resonant third photon ionization of atomic bromine (4p 5 2 P 3/2 and 2 P 1/2 ) has been studied using a photoelectron imaging spectroscopy in the wavelength region 250-278 nm. The technique has yielded simultaneously both relative branching ratios to the three levels of Br + ( 3 P 2 , 3 P 0,1 and 1 D 2 ) with 4p 4 configuration and the angular distributions of outgoing photoelectrons. The product branching ratios reveal a strong propensity to populate particular levels in many cases. Several pathways have been documented for selective formation of Br + ( 3 P 2 ) and Br + ( 3 P 0,1 ) ions. In general, the final ion level distributions are dominated by the preservation of the ion core configuration of a resonant excited state. Some deviations from this simple picture are discussed in terms of the configuration interaction of resonant states and the autoionization in the continuum. The photoelectron angular distributions are qualitatively similar for all transitions, with a positive A 2 anisotropy coefficient of 1.0 - 2.0 and negligible A 4 in most cases, which suggests that the angular distribution is mainly determined by the single-photon ionization process of a resonant excited state induced from the third photon absorption

  10. Resonance-enhanced multiphoton ionization (REMPI) spectroscopy of p-chlorofluorobenzene

    Science.gov (United States)

    Tuttle, William D.; Gardner, Adrian M.; Wright, Timothy G.

    2017-09-01

    The S1 ← S0 (A˜1 B2 ← X˜1 A1) electronic transition of para-chlorofluorobenzene has been investigated using resonance-enhanced multiphoton ionization (REMPI) spectroscopy. Assignment of the vibrational structure has been achieved by comparison with corresponding spectra of related molecules, via quantum chemical calculations, and via shifts in bands between the spectra of the 35Cl and 37Cl isotopologues. In addition, we have also partially reassigned a previously-published spectrum of para-dichlorobenzene.

  11. Ionization in matrix-assisted laser desorption/ionization: singly charged molecular ions are the lucky survivors.

    Science.gov (United States)

    Karas, M; Glückmann, M; Schäfer, J

    2000-01-01

    A new model for the ionization processes in UV matrix-assisted laser desorption/ionization (MALDI) which accounts for the major phenomena observed is presented and discussed. The model retains elements of earlier approaches, such as photoionization and photochemical reactions, but it redefines these in the light of new working questions, most importantly why only singly charged ions are detected. Based on experimental evidence, the formation of singly and multiply charged clusters by a deficiency/excess of ions and also by photoionization and subsequent photochemical processes is pointed out to be the major ionization processes, which typically occur in parallel. The generation of electrons and their partial loss into the surrounding vacuum and solid, on the one hand, results in a positively charged ion-neutral plume facilitating a high overall ionization yield. On the other hand, these electrons, and also the large excess of protonated matrix ions in the negative ion mode, induce effective ion reneutralization in the plume. These neutralization processes are most effective for the highly charged cluster ions initially formed. Their fragmentation behaviour is evidenced in fast metastable fragmentation characteristics and agrees well with an electron capture dissociation mechanism and the enthalpy transfer upon neutralization forms the rationale for the prominent fragmentation and intense chemical noise accompanying successful MALDI. Within the course of the paper, cross-correlations with other desorption/ionization techniques and with earlier discussions on their mechanisms are drawn. Copyright 2000 John Wiley & Sons, Ltd.

  12. Laser Ion Source Development for ISOL Systems at RIA

    CERN Document Server

    Liu, Yuan; Beene, James R; Bilheux, Hassina Z; Brueck, Kim; Geppert, Christopher; Havener, Charles; Kessler, Thomas; Krause, Herbert F; Schultz, David R; Stracener, Dan; Vane, C R; Wendt, Klaus

    2005-01-01

    The isobaric purity of radioactive ion beams (RIBs) is of crucial importance to many experiments. Laser ion sources based on resonant photoionization have already proved to be of great value at existing ISOL RIB facilities. In these ion sources, ions of a selected isotope are produced by laser radiation via stepwise atomic resonant excitations followed by ionization in the last transition. Because each element has its own unique atomic energy levels, the resonant photoionization process can provide elemental selectivity of nearly 100%. We have initiated a research effort to develop a prototype laser ion source with the potential to achieve the high selectivity and high efficiency required for research with ISOL-generated RIBs at the Rare Isotope Accelerator (RIA). A pilot experiment has been conducted to demonstrate resonant photoionization of three atomic species using all-solid-state tunable Ti:Sapphire lasers. Three Ti:Sapphire lasers were provided by the University of Mainz and used in the experiment for ...

  13. Multiphoton atomic ionization in the field of a very short laser pulse

    International Nuclear Information System (INIS)

    Popov, V.S.

    2001-01-01

    Closed analytic expressions are derived for the probability of multiphoton atomic and ionic ionization in a variable electric field E(t), which are applicable for arbitrary Keldysh parameters γ. Dependencies of the ionization probability and photoelectron pulse spectrum on the shape of a very short laser pulse are analyzed. Examples of pulse fields of various forms, including a modulated light pulse with a Gaussian or Lorentz envelope, are considered in detail. The interference effect in the photoelectron energy spectrum during atomic ionization by a periodic field of a general form is examined. The range of applicability of the adiabatic approximation in the multiphoton ionization theory is discussed. The imaginary time method is used in the calculations, which allows the probability of particle tunneling through oscillating barriers to be effectively calculated

  14. D2O laser pumped by an injection-locked CO2 laser for ion-temperature measurements

    International Nuclear Information System (INIS)

    Okada, Tatsuo; Ohga, Tetsuaki; Yokoo, Masakazu; Muraoka, Katsunori; Akazaki, Masanori.

    1986-01-01

    The cooperative Thomson scattering method is one of the various new techniques proposed for measuring the temperature of ions in nuclear fusion critical plasma, for which a high-performance FIR laser pumped by an injection-locked CO 2 laser is required. This report deals with D 2 O laser with a wavelength of 385 μm which is pumped by injection-locked single-mole TEA CO 2 laser composed of a driver laser and an output-stage laser. A small-sized automatic pre-ionization type laser is employed for the driver. The resonator of the driver laser consists of a plane grating of littrow arrangement and ZnSe plane output mirrors with reflection factor of 50 %. An aperture and ZnSe etalon are inserted in the resonator to produce single transverse- and longitudinal-mode oscillation, respectively. The output-stage laser is also of the automatic pre-ionization type. Theoretically, an injection power of 0.1 pW/mm 3 is required for a CO 2 laser. Single-mode oscillation of several hundred nW/mm 3 can be produced by the CO 2 laser used in this study. Tuning of the output-stage laser is easily controlled by the driver laser. High stability of the injection-locked operation is demonstrated. CO 2 laser beam is introduced into the D 2 O laser through a KCl window to excite D 2 O laser beam in the axial direction. Input and output characteristics of the D 2 O laser are shown. Also presented are typical pulse shapes from the D 2 O laser pumped by a free-running CO 2 laser pulse or by an injection-locked single-mode CO 2 laser pulse. (Nogami, K.)

  15. Laser desorption/ionization mass spectrometry of lipids using etched silver substrates.

    Science.gov (United States)

    Schnapp, Andreas; Niehoff, Ann-Christin; Koch, Annika; Dreisewerd, Klaus

    2016-07-15

    Silver-assisted laser desorption/ionization mass spectrometry can be used for the analysis of small molecules. For example, adduct formation with silver cations enables the molecular analysis of long-chain hydrocarbons, which are difficult to ionize via conventional matrix-assisted laser desorption ionization (MALDI). Here we used highly porous silver foils, produced by etching with nitric acid, as sample substrates for LDI mass spectrometry. As model system for the analysis of complex lipid mixtures, cuticular extracts of fruit flies (Drosophila melanogaster) and worker bees (Apis mellifera) were investigated. The mass spectra obtained by spotting extract onto the etched silver substrates demonstrate the sensitive detection of numerous lipid classes such as long-chain saturated and unsaturated hydrocarbons, fatty acyl alcohols, wax esters, and triacylglycerols. MS imaging of cuticular surfaces with a lateral resolution of a few tens of micrometers became possible after blotting, i.e., after transferring lipids by physical contact with the substrate. The examples of pheromone-producing male hindwings of the squinting bush brown butterfly (Bicyclus anynana) and a fingermark are shown. Because the substrates are also easy to produce, they provide a viable alternative to colloidal silver nanoparticles and other so far described silver substrates. Copyright © 2016 Elsevier Inc. All rights reserved.

  16. Multiphoton ionization as a probe of molecular photofragmentation: statistical and dynamical energy partitioning in the multiphoton dissociation of nitromethane

    International Nuclear Information System (INIS)

    Rockney, B.H.

    1982-01-01

    Multiphoton ionization (MPI) appears in its first use as a probe of laser-induced photofragmentation. Specifically, MPI here reveals the internal and translational energy content of the nascent fragments from the infrared multiphoton dissociation (MPD) of nitromethane (CH 3 NO 2 ). The apparatus for this work consists of a pulsed supersonic molecular beam crossed by two pulsed and focused lasers - a CO 2 laser to induce collision-free unimolecular dissociation of CH 3 NO 2 , and a tunable dye laser following immediately to ionize selectively one of the pair of dissociation fragments for detection by a mass spectrometer and particle multiplier. A computer simulation of each fragment's MPI spectrum, a series of four photon resonances to members of the npsigma/sub u/ Rydberg state of NO 2 and three photon resonances to two vibrational members of the #betta# 1 Rydberg state of CH 3 , aids in determining the fragment's internal energy content. The dye laser is delayed and its focus is traced through a small quarter circle centered at the focus of the CO 2 laser. The flight times of the fragments from the point of dissociation and their laboratory scattering angular distributions at fixed ionizing laser wavelength provide their center of mass recoil velocity distributions. The energy deposited in the fragments evidences a striking mixture of statistical and dynamical energy partitioning. The statistical RRKM theory of unimolecular decomposition accurately predicts the amount of internal energy found in the fragments

  17. Gas breakdown at cyclotron resonance with a submillimeter laser

    International Nuclear Information System (INIS)

    Hacker, M.P.; Temkin, R.J.; Lax, B.

    1976-01-01

    A pulsed 496-μm CH 3 F laser is used to produce gas breakdown in He at pressures between 1 and 300 Torr in an intense longitudinal magnetic field. Breakdown is detected by the observation of visible light when the electron cyclotron frequency (eB/m) equals the laser frequency, which occurs at B=216 kG for lambda=496 μm. At the lowest helium pressures and near cyclotron resonance, the focused laser intensity of 40 kW/cm 2 gives rise to very large electron heating rates, well beyond the limit of validity of conventional equilibrium breakdown theory. The observed result is an intensity-dependent resonant linewidth, much larger than predicted by equilibrium theories

  18. UV Resonant Raman Spectrometer with Multi-Line Laser Excitation

    Science.gov (United States)

    Lambert, James L.; Kohel, James M.; Kirby, James P.; Morookian, John Michael; Pelletier, Michael J.

    2013-01-01

    A Raman spectrometer employs two or more UV (ultraviolet) laser wavel engths to generate UV resonant Raman (UVRR) spectra in organic sampl es. Resonant Raman scattering results when the laser excitation is n ear an electronic transition of a molecule, and the enhancement of R aman signals can be several orders of magnitude. In addition, the Ra man cross-section is inversely proportional to the fourth power of t he wavelength, so the UV Raman emission is increased by another fact or of 16, or greater, over visible Raman emissions. The Raman-scatter ed light is collected using a high-resolution broadband spectrograph . Further suppression of the Rayleigh-scattered laser light is provi ded by custom UV notch filters.

  19. Achieving sensitive, high-resolution laser spectroscopy at CRIS

    Energy Technology Data Exchange (ETDEWEB)

    Groote, R. P. de [Instituut voor Kern- en Stralingsfysica, KU Leuven (Belgium); Lynch, K. M., E-mail: kara.marie.lynch@cern.ch [EP Department, CERN, ISOLDE (Switzerland); Wilkins, S. G. [The University of Manchester, School of Physics and Astronomy (United Kingdom); Collaboration: the CRIS collaboration

    2017-11-15

    The Collinear Resonance Ionization Spectroscopy (CRIS) experiment, located at the ISOLDE facility, has recently performed high-resolution laser spectroscopy, with linewidths down to 20 MHz. In this article, we present the modifications to the beam line and the newly-installed laser systems that have made sensitive, high-resolution measurements possible. Highlights of recent experimental campaigns are presented.

  20. Drawing a different picture with pencil lead as matrix-assisted laser desorption/ionization matrix for fullerene derivatives.

    Science.gov (United States)

    Nye, Leanne C; Hungerbühler, Hartmut; Drewello, Thomas

    2018-02-01

    Inspired by reports on the use of pencil lead as a matrix-assisted laser desorption/ionization matrix, paving the way towards matrix-free matrix-assisted laser desorption/ionization, the present investigation evaluates its usage with organic fullerene derivatives. Currently, this class of compounds is best analysed using the electron transfer matrix trans-2-[3-(4-tert-butylphenyl)-2-methyl-2-propenylidene] malononitrile (DCTB), which was employed as the standard here. The suitability of pencil lead was additionally compared to direct (i.e. no matrix) laser desorption/ionization-mass spectrometry. The use of (DCTB) was identified as the by far gentler method, producing spectra with abundant molecular ion signals and much reduced fragmentation. Analytically, pencil lead was found to be ineffective as a matrix, however, appears to be an extremely easy and inexpensive method for producing sodium and potassium adducts.

  1. Rabi oscillations in extreme ultraviolet ionization of atomic argon

    Science.gov (United States)

    Flögel, Martin; Durá, Judith; Schütte, Bernd; Ivanov, Misha; Rouzée, Arnaud; Vrakking, Marc J. J.

    2017-02-01

    We demonstrate Rabi oscillations in nonlinear ionization of argon by an intense femtosecond extreme ultraviolet (XUV) laser field produced by high-harmonic generation. We monitor the formation of A r2 + as a function of the time delay between the XUV pulse and an additional near-infrared (NIR) femtosecond laser pulse, and show that the population of an A r+* intermediate resonance exhibits strong modulations both due to an NIR laser-induced Stark shift and XUV-induced Rabi cycling between the ground state of A r+ and the A r+* excited state. Our experiment represents a direct experimental observation of a Rabi-cycling process in the XUV regime.

  2. Modeling laser brightness from cross Porro prism resonators

    Science.gov (United States)

    Forbes, Andrew; Burger, Liesl; Litvin, Igor Anatolievich

    2006-08-01

    Laser brightness is a parameter often used to compare high power laser beam delivery from various sources, and incorporates both the power contained in the particular mode, as well as the propagation of that mode through the beam quality factor, M2. In this study a cross Porro prism resonator is considered; crossed Porro prism resonators have been known for some time, but until recently have not been modeled as a complete physical optics system that allows the modal output to be determined as a function of the rotation angle of the prisms. In this paper we consider the diffraction losses as a function of the prism rotation angle relative to one another, and combine this with the propagation of the specific modes to determine the laser output brightness as a function of the prism orientation.

  3. Application of laser resonance scattering to the study of high-temperature plasma-wall interaction

    International Nuclear Information System (INIS)

    Maeda, Mitsuo; Muraoka, Katsunori; Hamamoto, Makoto; Akazaki, Masanori; Miyazoe, Yasushi

    1981-01-01

    Studies on laser resonance scattering and its application to the study of high-temperature plasma-wall interaction are reviewed. The application of dye laser beam to resonant scattering method has been developed. This method is able to detect low density atoms. The fluorescent photon counts can be estimated for a two-level system and a three-level system. The S/N ratio, Which is in close connection with the detection limit, has been estimated. The doppler effect due to the thermal motion of atoms is taken into consideration. The calibration of the absolute number of atoms is necessary. Tunable coherent light is used as the light source for resonance scattering method. This is able to excite atoms strongly and to increase the detection efficiency. As dye lasers, a N 2 laser, a YAG laser, and a KrF excimer laser have been studied. In VUV region, rare gas or rare gas halide lasers can be used. The strong output power can be expected when the resonance lines of atoms meet the synchronizing region of the excimer laser. The resonance scattering method is applied to the detection of impurity metal atoms in plasma. The studies of laser systems for the detection of hydrogen atoms are also in progress. (Kato, T.)

  4. Design of high power solid-state pulsed laser resonators

    International Nuclear Information System (INIS)

    Narro, R.; Ponce, L.; Arronte, M.

    2009-01-01

    Methods and configurations for the design of high power solid-state pulsed laser resonators, operating in free running, are presented. For fundamental mode high power resonators, a method is proposed for the design of a resonator with joined stability zones. In the case of multimode resonators, two configurations are introduced for maximizing the laser overall efficiency due to the compensation of the astigmatism induced by the excitation. The first configuration consists in a triangular ring resonator. The results for this configuration are discussed theoretically, showing that it is possible to compensate the astigmatism of the thermal lens virtually in a 100%; however this is only possible for a specific pumping power. The second configuration proposes a dual-active medium resonator, rotated 90 degree one from the other around the optical axis, where each active medium acts as an astigmatic lens of the same dioptric power. The reliability of this configuration is corroborated experimentally using a Nd:YAG dual-active medium resonator. It is found that in the pumping power range where the astigmatism compensation is possible, the overall efficiency is constant, even when increasing the excitation power with the consequent increase of the thermal lens dioptric power. (Author)

  5. Resonator design and performance estimation for a space-based laser transmitter

    Science.gov (United States)

    Agrawal, Lalita; Bhardwaj, Atul; Pal, Suranjan; Kamalakar, J. A.

    2006-12-01

    Development of a laser transmitter for space applications is a highly challenging task. The laser must be rugged, reliable, lightweight, compact and energy efficient. Most of these features are inherently achieved by diode pumping of solid state lasers. Overall system reliability can further be improved by appropriate optical design of the laser resonator besides selection of suitable electro-optical and opto-mechanical components. This paper presents the design details and the theoretically estimated performance of a crossed-porro prism based, folded Z-shaped laser resonator. A symmetrically pumped Nd: YAG laser rod of 3 mm diameter and 60 mm length is placed in the gain arm with total input peak power of 1800 W from laser diode arrays. Electro-optical Q-switching is achieved through a combination of a polarizer, a fractional waveplate and LiNbO 3 Q-switch crystal (9 x 9 x 25 mm) placed in the feedback arm. Polarization coupled output is obtained by optimizing azimuth angle of quarter wave plate placed in the gain arm. Theoretical estimation of laser output energy and pulse width has been carried out by varying input power levels and resonator length to analyse the performance tolerances. The designed system is capable of meeting the objective of generating laser pulses of 10 ns duration and 30 mJ energy @ 10 Hz.

  6. Supersonic Ionization Wave Driven by Radiation Transport in a Short-Pulse Laser-Produced Plasma

    International Nuclear Information System (INIS)

    Ditmire, T.; Gumbrell, E.T.; Smith, R.A.; Mountford, L.; Hutchinson, M.H.

    1996-01-01

    Through the use of an ultrashort (2ps) optical probe, we have time resolved the propagation of an ionization wave into solid fused silica. This ionization wave results when a plasma is created by the intense irradiation of a solid target with a 2ps laser pulse. We find that the velocity of the ionization wave is consistent with radiation driven thermal transport, exceeding the velocity expected from simple electron thermal conduction by nearly an order of magnitude. copyright 1996 The American Physical Society

  7. Quantitative study of the ionization-induced refraction of picosecond laser pulses in gas-jet targets

    International Nuclear Information System (INIS)

    Mackinnon, A.J.; Borghesi, M.; Iwase, A.; Jones, M.W.; Pert, G.J.; Rae, S.; Burnett, K.; Willi, O.

    1996-01-01

    A quantitative study of refractive whole beam defocusing and small scale breakup induced by optical ionization of subpicosecond and picosecond, 0.25 and 1 μm, laser pulses in gas-jet targets at densities above 1x10 19 cm -3 has been carried out. A significant reduction of the incident laser intensity was observed due to refraction from ionization-induced density gradients. The level of refraction measured with optical probing correlated well with the fraction of energy transmitted through the plasma. The numerical and analytical models were found to agree well with experimental observations. copyright 1996 The American Physical Society

  8. Study of the mechanisms of matrix assisted laser desorption / ionization

    International Nuclear Information System (INIS)

    Manuelli, Pascal

    1995-01-01

    This research thesis aims at a better knowledge of some aspects of a complex mechanism: the matrix-assisted laser desorption/ionization (MALDI). The author first proposes a comparative analysis of results obtained by time-of-flight (TOF) mass spectrometry and by Fourier transform mass spectrometry. He reports the study of the matrix role (notably a polymeric matrix) as a matter submitted to laser desorption. In this respect, the influence of the incident wavelength has been studied. The author also reports a comparative of ions produced by matrix laser desorption (study performed by Fourier transform mass spectrometry) and of neutral molecules (study performed by flash pyrolysis coupled with gas chromatography and with mass spectrometry). Finally, results obtained on derivatives and complexes based on beta-cyclodextrins highlight benefits as well as limitations of this technique [fr

  9. Five-photon ionization of atomic hydrogen at wavelengths around the threshold for four-photon ionization

    International Nuclear Information System (INIS)

    Gontier, Y.; Trahin, M.; Wolff-Rottke, B.; Rottke, H.; Welge, K.H.; Feldmann, D.

    1992-01-01

    Theoretical and experimental studies show the strong influence of the three-photon nearly resonant 2p state on four- and five-photon ionization of atomic hydrogen near the threshold for four-photon ionization. Changes in five-photon ionization occur when the four-photon ionization channel opens. The angular distributions of photoelectrons from five-photon ionization of H are studied at five wavelengths which cover the range from four-photon resonance with high-lying Rydberg states (n≥10) to direct four-photon ionization into the continuum. The role of resonances in this ionization process is discussed. A fair agreement is found in comparing experimental and theoretical results

  10. A high-power diode-laser-pumped CW Nd:YAG laser using a stable-unstable resonator

    International Nuclear Information System (INIS)

    Mudge, M.; Ostermeyer, P.; Veitch, J.; Munch, J.; Hamilton, M.W.

    2000-01-01

    Full text: The design and operation of a power-scalable diode-laser-pumped CW Nd:YAG zigzag slab laser that uses a stable-unstable resonator with a graded reflectivity mirror as an output coupler is described. We demonstrate control of the thermal lens strength in the unstable plane and weak thermal lensing in the stable plane that is independent of pump power, vital for efficient scalability. This enabled CW operation of the stable-unstable resonator with excellent near- and far-field beam quality

  11. Ion beam production and study of radioactive isotopes with the laser ion source at ISOLDE

    Science.gov (United States)

    Fedosseev, Valentin; Chrysalidis, Katerina; Day Goodacre, Thomas; Marsh, Bruce; Rothe, Sebastian; Seiffert, Christoph; Wendt, Klaus

    2017-08-01

    At ISOLDE the majority of radioactive ion beams are produced using the resonance ionization laser ion source (RILIS). This ion source is based on resonant excitation of atomic transitions by wavelength tunable laser radiation. Since its installation at the ISOLDE facility in 1994, the RILIS laser setup has been developed into a versatile remotely operated laser system comprising state-of-the-art solid state and dye lasers capable of generating multiple high quality laser beams at any wavelength in the range of 210-950 nm. A continuous programme of atomic ionization scheme development at CERN and at other laboratories has gradually increased the number of RILIS-ionized elements. At present, isotopes of 40 different elements have been selectively laser-ionized by the ISOLDE RILIS. Studies related to the optimization of the laser-atom interaction environment have yielded new laser ion source types: the laser ion source and trap and the versatile arc discharge and laser ion source. Depending on the specific experimental requirements for beam purity or versatility to switch between different ionization mechanisms, these may offer a favourable alternative to the standard hot metal cavity configuration. In addition to its main purpose of ion beam production, the RILIS is used for laser spectroscopy of radioisotopes. In an ongoing experimental campaign the isotope shifts and hyperfine structure of long isotopic chains have been measured by the extremely sensitive in-source laser spectroscopy method. The studies performed in the lead region were focused on nuclear deformation and shape coexistence effects around the closed proton shell Z = 82. The paper describes the functional principles of the RILIS, the current status of the laser system and demonstrated capabilities for the production of different ion beams including the high-resolution studies of short-lived isotopes and other applications of RILIS lasers for ISOLDE experiments. This article belongs to the Focus on

  12. Matrix-assisted laser desorption/ionization mass spectrometry for the structural characterization of modified oligonucleotides

    International Nuclear Information System (INIS)

    Hurst, G.B.; Hettich, R.L.; Buchanan, M.V.; Stemmler, E.A.

    1993-01-01

    Matrix-assisted laser desorption ionization (MALDI) Fourier transform ion cyclotron resonance mass spectrometry (FTMS) and MALDI time-of-flight mass spectrometry (TOFMS) are being used to characterize conditions for the efficient desorption and ionization of normal and modified nucleic acid components. Basic and acidic matrix materials have been evaluated on the components. Basic and acidic matrix materials have been evaluated on the FTMS and TOFMS. Using MALDI-FTMS at 355 nm, less fragmentation has been observed using 2,5-dihydroxybenzoic acid, while more extensive fragmentation is observed for basic matrices, such as 1,5-diaminonaphthalene and 9-aminophenanthrene. Elevation of the cell pressure by the addition of Ar or CO 2 provides collisional cooling of desorbed ions, resulting in an enhancement of [M--H] - and structurally significant high-mass fragment ions. Using MALDI-TOFMS at 337 nm, fragmentation is significantly reduced relative to that observed on the FTMS, perhaps as a consequence of the longer times required for FTMS detection. On the FTMS and TOFMS, cluster ions have been observed in the negative ion mode when metal ions are present in the 2,5-dihydroxybenzoic acid matrix. Metal ion additions and clusters with matrix salts have also been observed for dinucleotides. Applications of MALDI-FTMS and MALDI-TOF to the detection of hydroxylated PAH nucleoside adducts are presented

  13. Magnetic resonance thermometry for monitoring photothermal effects of interstitial laser irradiation

    Science.gov (United States)

    Goddard, Jessica; Jose, Jessnie; Figueroa, Daniel; Le, Kelvin; Liu, Hong; Nordquist, Robert E.; Hode, Tomas; Chen, Wei R.

    2012-03-01

    Selective photothermal interaction using dye-assisted non-invasive laser irradiation has limitations when treating deeper tumors or when the overlying skin is heavily pigmented. We developed an interstitial laser irradiation method to induce the desired photothermal effects. An 805-nm near-infrared laser with a cylindrical diffuser was used to treat rat mammary tumors by placing the active tip of the fiber inside the target tumors. Three different power settings (1.0 to 1.5 watts) were applied to treat animal tumors with an irradiation duration of 10 minutes. The temperature distributions of the treated tumors were measured by a 7.1-Tesla magnetic resonance imager using proton resonance frequency (PRF) method. Three-dimensional temperature profiles were reconstructed and assessed using PRF. This is the first time a 7.1-Tesla magnetic resonance imager has been used to monitor interstitial laser irradiation via PRF. This study provides a basic understanding of the photothermal interaction needed to control the thermal damage inside tumor using interstitial laser irradiation. It also shows that PRF can be used effectively in monitoring photothermal interaction. Our long-term goal is to develop a PRF-guided laser therapy for cancer treatment.

  14. resonance fluorescence in Al, Ti, Cu and potential applications for X-ray sources

    Science.gov (United States)

    Nahar, Sultana N.; Pradhan, Anil K.

    2015-04-01

    The Kα resonance fluorescence (RFL) effect via photoabsorptions of inner shell electrons as the element goes through multiple ionization states is studied. We demonstrate that the resonances observed recently in Kα (1s-2p) fluorescence in aluminum plasmas by using a high-intensity X-ray free-electron laser [1] are basically K-shell resonances in hollow atoms going through multiple ionization states at resonant energies as predicted earlier for gold and iron ions [2]. These resonances are formed below the K-shell ionization edge and shift toward higher energies with ionization states, as observed. Fluorescence emission intensities depend on transition probabilities for each ionization stage of the given element for all possible Kα (1 s → 2 p) transition arrays. The present calculations for resonant photoabsorptions of Kα photons in Al have reproduced experimentally observed features. Resonant cross sections and absorption coefficients are presented for possible observation of Kα RFL in the resonant energy ranges of 4.5-5.0 keV for Ti ions and 8.0-8.7 keV for Cu ions respectively. We suggest that theoretically the Kα RFL process may be driven to enhance the Auger cycle by a twin-beam monochromatic X-ray source, tuned to the K-edge and Kα energies, with potential applications such as the development of narrow-band biomedical X-ray devices.

  15. Internal energy deposition with silicon nanoparticle-assisted laser desorption/ionization (SPALDI) mass spectrometry

    Science.gov (United States)

    Dagan, Shai; Hua, Yimin; Boday, Dylan J.; Somogyi, Arpad; Wysocki, Ronald J.; Wysocki, Vicki H.

    2009-06-01

    The use of silicon nanoparticles for laser desorption/ionization (LDI) is a new appealing matrix-less approach for the selective and sensitive mass spectrometry of small molecules in MALDI instruments. Chemically modified silicon nanoparticles (30 nm) were previously found to require very low laser fluence in order to induce efficient LDI, which raised the question of internal energy deposition processes in that system. Here we report a comparative study of internal energy deposition from silicon nanoparticles to previously explored benzylpyridinium (BP) model compounds during LDI experiments. The internal energy deposition in silicon nanoparticle-assisted laser desorption/ionization (SPALDI) with different fluorinated linear chain modifiers (decyl, hexyl and propyl) was compared to LDI from untreated silicon nanoparticles and from the organic matrix, [alpha]-cyano-4-hydroxycinnamic acid (CHCA). The energy deposition to internal vibrational modes was evaluated by molecular ion survival curves and indicated that the ions produced by SPALDI have an internal energy threshold of 2.8-3.7 eV. This is slightly lower than the internal energy induced using the organic CHCA matrix, with similar molecular survival curves as previously reported for LDI off silicon nanowires. However, the internal energy associated with desorption/ionization from the silicon nanoparticles is significantly lower than that reported for desorption/ionization on silicon (DIOS). The measured survival yields in SPALDI gradually decrease with increasing laser fluence, contrary to reported results for silicon nanowires. The effect of modification of the silicon particle surface with semifluorinated linear chain silanes, including fluorinated decyl (C10), fluorinated hexyl (C6) and fluorinated propyl (C3) was explored too. The internal energy deposited increased with a decrease in the length of the modifier alkyl chain. Unmodified silicon particles exhibited the highest analyte internal energy

  16. Experiments on resonantly photo-pumped x-ray lasers

    International Nuclear Information System (INIS)

    Nilsen, J.; Porter, J.L.; Da Silva, L.B.; MacGowan, B.; Beiersdorfer, P..; Elliott, S.R.; Young, B.K.

    1992-01-01

    We describe our recent effort to identify and study a promising resonantly photopumped x-ray laser scheme. In particular we will describe a scheme which uses the strong emission lines of a nickel-like ion to resonantly photo-pump a neon-like ion and enhance the lasing of the neon-like 3p → 3s transitions

  17. Peak quantification in surface-enhanced laser desorption/ionization by using mixture models

    NARCIS (Netherlands)

    Dijkstra, Martijn; Roelofsen, Han; Vonk, Roel J.; Jansen, Ritsert C.

    2006-01-01

    Surface-enhanced laser desorption/ionization (SELDI) time of flight (TOF) is a mass spectrometry technology for measuring the composition of a sampled protein mixture. A mass spectrum contains peaks corresponding to proteins in the sample. The peak areas are proportional to the measured

  18. A laser-based FAIMS detector for detection of ultra-low concentrations of explosives

    Science.gov (United States)

    Akmalov, Artem E.; Chistyakov, Alexander A.; Kotkovskii, Gennadii E.; Sychev, Alexey V.; Tugaenko, Anton V.; Bogdanov, Artem S.; Perederiy, Anatoly N.; Spitsyn, Eugene M.

    2014-06-01

    A non-contact method for analyzing of explosives traces from surfaces was developed. The method is based on the laser desorption of analyzed molecules from the surveyed surfaces followed by the laser ionization of air sample combined with the field asymmetric ion mobility spectrometry (FAIMS). The pulsed radiation of the fourth harmonic of a portable GSGG: Cr3+ :Nd3+ laser (λ = 266 nm) is used. The laser desorption FAIMS analyzer have been developed. The detection limit of the analyzer equals 40 pg for TNT. The results of detection of trinitrotoluene (TNT), cyclotrimethylenetrinitramine (RDX) and cyclotetramethylenetetranitramine (HMX) are presented. It is shown that laser desorption of nitro-compounds from metals is accompanied by their surface decomposition. A method for detecting and analyzing of small concentrations of explosives in air based on the laser ionization and the FAIMS was developed. The method includes a highly efficient multipass optical scheme of the intracavity fourthharmonic generation of pulsed laser radiation (λ = 266 nm) and the field asymmetric ion mobility (FAIM) spectrometer disposed within a resonator. The ions formation and detection proceed inside a resonant cavity. The laser ion source based on the multi-passage of radiation at λ = 266 nm through the ionization region was elaborated. On the basis of the method the laser FAIMS analyzer has been created. The analyzer provides efficient detection of low concentrations of nitro-compounds in air and shows a detection limit of 10-14 - 10-15 g/cm3 both for RDX and TNT.

  19. Differential interferometer for measurement of displacement of laser resonator mirrors

    Science.gov (United States)

    Macúchová, Karolina; Němcová, Šárka; Hošek, Jan

    2015-01-01

    This paper covers a description and a technique of a possible optical method of mode locking within a laser resonator. The measurement system is a part of instrumentation of laser-based experiment OSQAR at CERN. The OSQAR experiment aims at search of axions, axion-like particles and measuring of ultra-fine vacuum magnetic birefringence. It uses a laser resonator to enhance the coupling constant of hypothetical photon-to-axion conversion. The developed locking-in technique is based on differential interferometry. Signal obtained from the measurement provide crucial information for adaptive control of the locking-in of the resonator in real time. In this paper we propose several optical setups used for measurement and analysis of mutual position of the resonator mirrors. We have set up a differential interferometer under our laboratory conditions. We have done measurements with hemi-spherical cavity resonator detuned with piezo crystals. The measurement was set up in a single plane. Laser light was directed through half-wave retarder to a polarizing beam splitter and then converted to circular polarization by lambda/4 plates. After reflection at the mirrors, the beam is recombined in a beam splitter, sent to analyser and non-polarizing beam splitter and then inspected by two detectors with mutually perpendicular polarizers. The 90 degrees phase shift between the two arms allows precise analysis of a mutual distance change of the mirrors. Because our setup was sufficiently stable, we were able to measure the piezo constant and piezo hysteresis. The final goal is to adapt the first prototype to 23 m resonator and measure the displacement in two planes.

  20. Highly scalable, resonantly cladding-pumped, Er-doped fiber laser with record efficiency.

    Science.gov (United States)

    Dubinskii, M; Zhang, J; Ter-Mikirtychev, V

    2009-05-15

    We report the performance of a resonantly cladding-pumped, Yb-free, Er-doped fiber laser. We believe this is the first reported resonantly cladding-pumped fiber-Bragg-grating-based, Er-doped, large-mode-area (LMA) fiber laser. The laser, pumped by fiber-coupled InGaAsP/InP laser diode modules at 1,532.5 nm, delivers approximately 48 W of cw output at 1,590 nm. It is believed to be the highest power ever reported from a Yb-free Er-doped LMA fiber. This fully integrated laser also has the optical-to-optical efficiency of approximately 57%, to the best of our knowledge, the highest efficiency reported for cladding-pumped unidirectionally emitting Er-doped laser.

  1. Alignment dependence in above-threshold ionization of H2+: role of intermediate resonances

    DEFF Research Database (Denmark)

    Hernández, Jorge Fernández; Madsen, Lars Bojer

    2009-01-01

    We report a 3D ab initio investigation of the dependence of above-threshold ionization of the H2+ molecule on the orientation of a linearly polarized intense femtosecond laser pulse with respect to the molecular axis. The calculations were performed in the frozen nuclei approximation for the 2Σ+g(1......sσg) ground and the 2Σ+u(2pσu) first excited electronic states, in laser pulses of seven optical cycles (19 fs) with a wavelength of 800 nm and for different intensities. The numerical procedure combines two different techniques, a grid-based split-step method to propagate the wave packet during...... the pulse, and a bound and scattering states B-spline basis set calculation to extract the information from the former. We show that the orientation dependence of the above-threshold ionization spectra is very sensitive to the intensity of the field and to the final electron energy. For some intensities...

  2. Dissociative double ionization of H2 and D2: Comparison between experiment and Monte Carlo wave packet calculations

    DEFF Research Database (Denmark)

    Leth, Henriette Astrup; Madsen, Lars Bojer; Mølmer, Klaus

    2010-01-01

    Theoretical calculations on dissociative double ionization of H2 and D2 in short intense laser pulses using the Monte Carlo wave packet technique are presented for several different field intensities, wavelengths, and pulse durations. We find convincing agreement between theory and experimental...... results for the kinetic energy release spectra of the nuclei. Besides the correctly predicted spectra the Monte Carlo wave packet method offers insight into the nuclear dynamics during the pulse and makes it possible to address the origin of different structures observed in the spectra. Three......-photon resonances in the singly ionized molecule and charge-resonance-enhanced ionization are shown to be the main processes responsible for the observed nuclear energy distributions....

  3. Significance of the Resonance Condition for Controlling the Seam Position in Laser-assisted TIG Welding

    Science.gov (United States)

    Emde, B.; Huse, M.; Hermsdorf, J.; Kaierle, S.; Wesling, V.; Overmeyer, L.; Kozakov, R.; Uhrlandt, D.

    As an energy-preserving variant of laser hybrid welding, laser-assisted arc welding uses laser powers of less than 1 kW. Recent studies have shown that the electrical conductivity of a TIG welding arc changes within the arc in case of a resonant interaction between laser radiation and argon atoms. This paper presents investigations on how to control the position of the arc root on the workpiece by means of the resonant interaction. Furthermore, the influence on the welding result is demonstrated. The welding tests were carried out on a cooled copper plate and steel samples with resonant and non-resonant laser radiation. Moreover, an analysis of the weld seam is presented.

  4. Effects of nuclear vibration on the ionization process of H2+ in ultrashort intense laser field

    International Nuclear Information System (INIS)

    Phan, Ngoc-Loan; Nguyen, Ngoc-Ty; Truong, Tran-Chau

    2015-01-01

    By numerically solving the time-dependent Schrödinger equation, we calculate the ionization probability of a vibrating H 2 + exposed to ultrashort intense laser fields. The results show that the ionization probability increases by time and gets a saturation value. We also find that with some first vibration levels, the ionization probability from a higher vibration level is larger than that from a lower one. However, with higher vibration levels, at a certain level the ionization probability will take maximum and decrease with next levels. (paper)

  5. Ultratrace analysis of plutonium in environmental samples by resonance ionization mass spectrometry (RIMS)

    International Nuclear Information System (INIS)

    Trautmann, N.; Erdmann, N.; Gruening, C.; Kratz, J. V.; Waldek, A.; Huber, G.; Nunnemann, M.; Passler, G.

    2000-01-01

    Plutonium is present in the environment mainly as a result of global fallout from nuclear weapons tests, satellite and reactor accidents as well as releases from nuclear facilities. Sensitive and fast detection methods are required for risk assessment, low-level surveillance of the environment, personnel dose monitoring, studies of biological effects and investigations of the migration behavior of plutonium. Furthermore, the isotopic composition is of interest to get information from what source the plutonium contamination originated. Alpha-spectroscopy is most frequently used for the determination of trace amounts of plutonium in the environment with the disadvantage that the detection sensitivity depends on the half-life of the isotope to be measured and that there are limitations in the isotopic resolution. Conventional mass spectrometry may suffer from isobaric interferences. Therefore, in the last years resonant laser ionization mass spectrometry (RIMS) has been explored as an alternative for ultratrace analysis of plutonium. This method provides a high element and isotope selectivity and a good overall efficiency, resulting in a detection limit of ∼10 6 atoms (∼0.4 fg). RIMS meets also the requirements of a low background and a short measuring time (1-2 h)

  6. O2 rotational temperature measurements in an atmospheric air microdischarge by radar resonance-enhanced multiphoton ionization

    International Nuclear Information System (INIS)

    Sawyer, Jordan; Wu, Yue; Zhang, Zhili; Adams, Steven F.

    2013-01-01

    Nonintrusive spatially resolved rotational temperature measurements in an atmospheric air microdischarge are presented. The measurements were based on coherent microwave Rayleigh scattering (Radar) from resonance-enhanced multiphoton ionization of molecular oxygen. The open air DC microdischarge source operated in a stable “normal-glow” mode and pin-to-pin electrodes spaced 1.3 mm apart. The second harmonic of a tunable dye laser beam was focused between the two electrodes and scanned between 286 and 288 nm. Coherent microwave Rayleigh scattering was used to collect the two-photon rotational spectra of O 2 at C 3 Π(v = 2)←X 3 Σ(v′ = 0) transitions. The Boltzmann plots from analyses of the O 2 rotational lines determined local rotational temperatures at various axial locations between the electrodes. The molecular oxygen rotational temperature varied from ∼1150 K to ∼1350 K within the discharge area. The measurements had an accuracy of ∼±50 K.

  7. O2 rotational temperature measurements in an atmospheric air microdischarge by radar resonance-enhanced multiphoton ionization

    Science.gov (United States)

    Sawyer, Jordan; Wu, Yue; Zhang, Zhili; Adams, Steven F.

    2013-06-01

    Nonintrusive spatially resolved rotational temperature measurements in an atmospheric air microdischarge are presented. The measurements were based on coherent microwave Rayleigh scattering (Radar) from resonance-enhanced multiphoton ionization of molecular oxygen. The open air DC microdischarge source operated in a stable "normal-glow" mode and pin-to-pin electrodes spaced 1.3 mm apart. The second harmonic of a tunable dye laser beam was focused between the two electrodes and scanned between 286 and 288 nm. Coherent microwave Rayleigh scattering was used to collect the two-photon rotational spectra of O2 at C3Π(v = 2)←X3Σ(v' = 0) transitions. The Boltzmann plots from analyses of the O2 rotational lines determined local rotational temperatures at various axial locations between the electrodes. The molecular oxygen rotational temperature varied from ˜1150 K to ˜1350 K within the discharge area. The measurements had an accuracy of ˜±50 K.

  8. Ionization Cooling using Parametric Resonances

    International Nuclear Information System (INIS)

    Johnson, Rolland P.

    2008-01-01

    Ionization Cooling using Parametric Resonances was an SBIR project begun in July 2004 and ended in January 2008 with Muons, Inc., (Dr. Rolland Johnson, PI), and Thomas Jefferson National Accelerator Facility (JLab) (Dr. Yaroslav Derbenev, Subcontract PI). The project was to develop the theory and simulations of Parametric-resonance Ionization Cooling (PIC) so that it could be used to provide the extra transverse cooling needed for muon colliders in order to relax the requirements on the proton driver, reduce the site boundary radiation, and provide a better environment for experiments. During the course of the project, the theoretical understanding of PIC was developed and a final exposition is ready for publication. Workshops were sponsored by Muons, Inc. in May and September of 2007 that were devoted to the PIC technique. One outcome of the workshops was the interesting and somewhat unexpected realization that the beam emittances using the PIC technique can get small enough that space charge forces can be important. A parallel effort to develop our G4beamline simulation program to include space charge effects was initiated to address this problem. A method of compensating for chromatic aberrations by employing synchrotron motion was developed and simulated. A method of compensating for spherical aberrations using beamline symmetry was also developed and simulated. Different optics designs have been developed using the OptiM program in preparation for applying our G4beamline simulation program, which contains all the power of the Geant4 toolkit. However, no PIC channel design that has been developed has had the desired cooling performance when subjected to the complete G4beamline simulation program. This is believed to be the consequence of the difficulties of correcting the aberrations associated with the naturally large beam angles and beam sizes of the PIC method that are exacerbated by the fringe fields of the rather complicated channel designs that have been

  9. Ionization Cooling using Parametric Resonances

    Energy Technology Data Exchange (ETDEWEB)

    Johnson, Rolland P.

    2008-06-07

    Ionization Cooling using Parametric Resonances was an SBIR project begun in July 2004 and ended in January 2008 with Muons, Inc., (Dr. Rolland Johnson, PI), and Thomas Jefferson National Accelerator Facility (JLab) (Dr. Yaroslav Derbenev, Subcontract PI). The project was to develop the theory and simulations of Parametric-resonance Ionization Cooling (PIC) so that it could be used to provide the extra transverse cooling needed for muon colliders in order to relax the requirements on the proton driver, reduce the site boundary radiation, and provide a better environment for experiments. During the course of the project, the theoretical understanding of PIC was developed and a final exposition is ready for publication. Workshops were sponsored by Muons, Inc. in May and September of 2007 that were devoted to the PIC technique. One outcome of the workshops was the interesting and somewhat unexpected realization that the beam emittances using the PIC technique can get small enough that space charge forces can be important. A parallel effort to develop our G4beamline simulation program to include space charge effects was initiated to address this problem. A method of compensating for chromatic aberrations by employing synchrotron motion was developed and simulated. A method of compensating for spherical aberrations using beamline symmetry was also developed and simulated. Different optics designs have been developed using the OptiM program in preparation for applying our G4beamline simulation program, which contains all the power of the Geant4 toolkit. However, no PIC channel design that has been developed has had the desired cooling performance when subjected to the complete G4beamline simulation program. This is believed to be the consequence of the difficulties of correcting the aberrations associated with the naturally large beam angles and beam sizes of the PIC method that are exacerbated by the fringe fields of the rather complicated channel designs that have been

  10. Analysis of the X-ray spectra emitted by laser-produced plasma of highly ionized lanthanum and praseodymium in the 8. 4 to 12. 0 A wavelength range

    Energy Technology Data Exchange (ETDEWEB)

    Zigler, A [Racah Inst. of Physics, Hebrew Univ., Jerusalem (Israel); Mandelbaum, P [Racah Inst. of Physics, Hebrew Univ., Jerusalem (Israel); Schwob, J L [Racah Inst. of Physics, Hebrew Univ., Jerusalem (Israel); Mitnik, D [Racah Inst. of Physics, Hebrew Univ., Jerusalem (Israel)

    1994-06-01

    A detailed analysis of the X-ray spectra emitted by laser produced plasma of lanthanum (8.5-12.5 A) and praseodymium (8.4-11.3 A) is given, using ab-initio calculations with the HULLAC relativistic code. Resonance 3d-nf (n 4, 5, 6) and 3p-4s, 4d transitions of the La XXX and Pr XXXII Ni I-like ions and neighbouring ionization states (La XXVIII to La XXXVI, Pr XXX to Pr XXXVI) have been identified. (orig.).

  11. Electron impact excitation and ionization of laser-excited sodium atoms Na*(7d)

    International Nuclear Information System (INIS)

    Nienhaus, J.; Dorn, A.; Mehlhorn, W.; Zatsarinny, O.I.

    1997-01-01

    We have investigated the ejected-electron spectrum following impact excitation and ionization of laser-excited Na * (nl) atoms by 1.5 keV electrons. By means of two-laser excitation 3s → 3p 3/2 → 7d and subsequent cascading transitions about 8% (4%) of the target atoms were in excited states with n > 3 (7d). The experimental ejected-electron spectrum due to the decay of Auger and autoionization states of laser-excited atoms Na * (nl) with n = 4-7 has been fully interpreted by comprehensive calculations of the energies, cross sections and decay probabilities of the corresponding states. The various processes contributing to the ejected-electron spectrum are with decreasing magnitude: 2s ionization leading to 2s2p 6 nl Auger states, 2p → 3s excitation leading to 2p 5 3s( 1 P)nl autoionization states and 2s → 3l' excitation leading to 2s2p 6 3l'( 1 L)nl autoionization states. (Author)

  12. Manipulating the wavelength-drift of a Tm laser for resonance enhancement in an intra-cavity pumped Ho laser.

    Science.gov (United States)

    Huang, Haizhou; Huang, Jianhong; Liu, Huagang; Li, Jinhui; Lin, Zixiong; Ge, Yan; Dai, Shutao; Deng, Jing; Lin, Wenxiong

    2018-03-05

    We demonstrate an enhancement mechanism and thermal model for intra-cavity pumped lasers, where resonance enhancement in intra-cavity pumped Ho laser was achieved by manipulating the wavelength-drift nature of the Tm laser for the first time. Optical conversion efficiency of 37.5% from an absorbed 785 nm diode laser to a Ho laser was obtained with a maximum output power of 7.51 W at 2122 nm, which is comparable to the conversion efficiency in 1.9 μm LD pumped Ho lasers. Meanwhile, more severe thermal effects in the Ho-doped gain medium than the Tm-doped one at high power operation were verified based on the built thermal model. This work benefits the design or evaluation of intra-cavity pumped lasers, and the resonance enhancement originated from the difference in reabsorption loss between stark levels at the lasing manifolds of quasi-three-level rare-earth ions has great interest to improve the existing intra-cavity pumped lasers or explore novel lasers.

  13. COMPLIS: COllinear spectroscopy Measurements using a Pulsed Laser Ion Source

    CERN Multimedia

    2002-01-01

    A Pulsed Laser spectroscopy experiment has been installed for the study of hyperfine structure and isotope shift of refractory and daughter elements from ISOLDE beams. It includes decelerated ion-implantation, element-selective laser ionization, magnetic and time-of-flight mass separation. The laser spectroscopy has been performed on the desorbed atoms in a set-up at ISOLDE-3 but later on high resolution laser collinear spectroscopy with the secondary pulsed ion beam is planned for the Booster ISOLDE set-up. During the first operation time of ISOLDE-3 we restricted our experiments to Doppler-limited resonant ionization laser and $\\gamma$-$\\gamma$ nuclear spectroscopy on neutron deficient platinum isotopes of even mass number down to A~=~186 and A~=~179 respectively. These isotopes have been produced by implantation of radioactive Hg and their subsequent $\\beta$-decay.

  14. Double ionization of nitrogen molecules in orthogonal two-color femtosecond laser fields

    Science.gov (United States)

    Song, Qiying; Li, Hui; Wang, Junping; Lu, Peifen; Gong, Xiaochun; Ji, Qinying; Lin, Kang; Zhang, Wenbin; Ma, Junyang; Li, Hanxiao; Zeng, Heping; He, Feng; Wu, Jian

    2018-04-01

    Double ionization of nitrogen molecules in orthogonally polarized two-color femtosecond laser fields is investigated by varying the relative intensity between the fundamental wave (FW) and its second harmonic (SH) components. The yield ratios of the double ionization channels, i.e., the non-dissociative {{{{N}}}2}2+ and Coulomb exploded (N+, N+), to the singly charged N2 + channel exhibit distinct dependences on the relative strength between the FW and SH fields. As the intensity ratio of SH to FW increases, the yield ratio of (N+, N+)/N2 + gradually increases, while the ratio of {{{{N}}}2}2+/N2 + first descends and then increases constituting a valley shape which is similar to the behavior of Ar2+/Ar+ observed in the same experimental condition. Based on the classical trajectory simulations, we found that the different characteristics of the two doubly ionized channels stem from two mechanisms, i.e., the {{{{N}}}2}2+ is mostly accessed by the (e, 2e) impact ionization while the recollision-induced excitation with subsequent ionization plays an important role in producing the (N+, N+) channel.

  15. Investigation of optimal photoionization schemes for Sm by multi-step resonance ionization

    International Nuclear Information System (INIS)

    Cha, H.; Song, K.; Lee, J.

    1997-01-01

    Excited states of Sm atoms are investigated by using multi-color resonance enhanced multiphoton ionization spectroscopy. Among the ionization signals one observed at 577.86 nm is regarded as the most efficient excited state if an 1-color 3-photon scheme is applied. Meanwhile an observed level located at 587.42 nm is regarded as the most efficient state if one uses a 2-color scheme. For 2-color scheme a level located at 573.50 nm from this first excited state is one of the best second excited state for the optimal photoionization scheme. Based on this ionization scheme various concentrations of standard solutions for samarium are determined. The minimum amount of sample which can be detected by a 2-color scheme is determined as 200 fg. The detection sensitivity is limited mainly due to the pollution of the graphite atomizer. copyright 1997 American Institute of Physics

  16. Automatic laser beam position control on the Isolde-Rilis experiment

    CERN Document Server

    Grancharova, D; Fedosseev, V; Suberlucq, Guy; CERN. Geneva. AB Department

    2003-01-01

    The On-Line Isotope Mass Separator ISOLDE at CERN is a facility for production of radioactive ion beams by the interaction of proton beams with a thick target. One of the most widely used types of ion source at ISOLDE is a chemically selective laser ion source based on the method of laser ionization of atoms in a hot cavity - RILIS (Resonance Ionization Laser Ion Source). The optical set-up of RILIS includes three copper vapour lasers, a set of dye lasers and frequency multiplication crystals giving up to three different beams of tuneable wavelengths. This paper will focus on the transport of the laser beams to the targets at distances of 18 m and 23 m, the development of the acquisition of their position and finally the automatic control of optics for an accurate alignment.

  17. Laser-assisted electron scattering in strong-field ionization of dense water vapor by ultrashort laser pulses

    International Nuclear Information System (INIS)

    Wilke, M; Al-Obaidi, R; Moguilevski, A; Kothe, A; Engel, N; Metje, J; Kiyan, I Yu; Aziz, E F

    2014-01-01

    We report on strong-field ionization of dense water gas in a short infrared laser pulse. By employing a unique combination of photoelectron spectroscopy with a liquid micro-jet technique, we observe how the character of electron emission at high kinetic energies changes with the increase of the medium density. This change is associated with the process of laser-assisted electron scattering (LAES) on neighboring particles, which becomes a dominant mechanism of hot electron emission at higher medium densities. The manifestation of this mechanism is found to require densities that are orders of magnitude lower than those considered for heating the laser-generated plasmas via the LAES process. The experimental results are supported by simulations of the LAES yield with the use of the Kroll–Watson theory. (paper)

  18. Effect of polarization and focusing on laser pulse driven auto-resonant particle acceleration

    International Nuclear Information System (INIS)

    Sagar, Vikram; Sengupta, Sudip; Kaw, Predhiman

    2014-01-01

    The effect of laser polarization and focusing is theoretically studied on the final energy gain of a particle in the Auto-resonant acceleration scheme using a finite duration laser pulse with Gaussian shaped temporal envelope. The exact expressions for dynamical variables viz. position, momentum, and energy are obtained by analytically solving the relativistic equation of motion describing particle dynamics in the combined field of an elliptically polarized finite duration pulse and homogeneous static axial magnetic field. From the solutions, it is shown that for a given set of laser parameters viz. intensity and pulse length along with static magnetic field, the energy gain by a positively charged particle is maximum for a right circularly polarized laser pulse. Further, a new scheme is proposed for particle acceleration by subjecting it to the combined field of a focused finite duration laser pulse and static axial magnetic field. In this scheme, the particle is initially accelerated by the focused laser field, which drives the non-resonant particle to second stage of acceleration by cyclotron Auto-resonance. The new scheme is found to be efficient over two individual schemes, i.e., auto-resonant acceleration and direct acceleration by focused laser field, as significant particle acceleration can be achieved at one order lesser values of static axial magnetic field and laser intensity

  19. Laser-induced breakdown spectroscopy with laser irradiation resonant with vibrational transitions

    International Nuclear Information System (INIS)

    Khachatrian, Ani; Dagdigian, Paul J.

    2010-01-01

    An investigation of laser-induced breakdown spectroscopy (LIBS) of polymers, both in bulk form and spin coated on Si wafers, with laser irradiation in the mid-infrared spectral region is presented. Of particular interest is whether the LIBS signals are enhanced when the laser wavelength is resonant with a fundamental vibrational transition of the polymer. Significant increases in the LIBS signals were observed for irradiation on hydride stretch fundamental transitions, and the magnitude of the enhancement showed a strong dependence on the mode excited. The role of the substrate was investigated by comparison of results for bulk and spin-coated samples. The polymers investigated were Nylon 12 and poly(vinyl alcohol-co-ethylene).

  20. Determination of the Isotope Ratio for Metal Samples Using a Laser Ablation/Ionization Time-of-flight Mass Spectrometry

    International Nuclear Information System (INIS)

    Song, Kyu Seok; Cha, Hyung Ki; Kim, Duk Hyeon; Min, Ki Hyun

    2004-01-01

    The laser ablation/ionization time-of-flight mass spectrometry is applied to the isotopic analysis of solid samples using a home-made instrument. The technique is convenient for solid sample analysis due to the onestep process of vaporization and ionization of the samples. The analyzed samples were lead, cadmium, molybdenum, and ytterbium. To optimize the analytical conditions of the technique, several parameters, such as laser energy, laser wavelength, size of the laser beam on the samples surface, and high voltages applied on the ion source electrodes were varied. Low energy of laser light was necessary to obtain the optimal mass resolution of spectra. The 532 nm light generated mass spectra with the higher signal-to-noise ratio compared with the 355 nm light. The best mass resolution obtained in the present study is ∼1,500 for the ytterbium

  1. Resonantly diode-pumped continuous-wave and Q-switched Er:YAG laser at 1645 nm.

    Science.gov (United States)

    Chang, N W H; Simakov, N; Hosken, D J; Munch, J; Ottaway, D J; Veitch, P J

    2010-06-21

    We describe an efficient Er:YAG laser that is resonantly pumped using continuous-wave (CW) laser diodes at 1470 nm. For CW lasing, it emits 6.1 W at 1645 nm with a slope efficiency of 36%, the highest efficiency reported for an Er:YAG laser that is pumped in this manner. In Q-switched operation, the laser produces diffraction-limited pulses with an average power of 2.5 W at 2 kHz PRF. To our knowledge this is the first Q-switched Er:YAG laser resonantly pumped by CW laser diodes.

  2. Resonance-enhanced laser-induced plasma spectroscopy: ambient gas effects

    International Nuclear Information System (INIS)

    Lui, S.L.; Cheung, N.H.

    2003-01-01

    When performing laser-induced plasma spectroscopy for elemental analysis, the sensitivity could be significantly enhanced if the plume was resonantly rekindled by a dye laser pulse. The extent of the enhancement was found to depend on the ambient gas. Air, nitrogen, helium, argon and xenon at pressures ranging from vacuum to 1 bar were investigated. In vacuum, the analyte signal was boosted because of reduced cooling, but it soon decayed as the plume freely expanded. By choosing the right ambient gas at the right pressure, the expanding plume could be confined as well as thermally insulated to maximize the analyte signal. For instance, an ambient of 13 mbar xenon yielded a signal-to-noise ratio of 110. That ratio was 53 when the pellet was ablated in air, and decreased further to 5 if the dye laser was tuned off resonance

  3. Photo-triggering and secondary electron produced ionization in electric discharge ArF* excimer lasers

    Science.gov (United States)

    Xiong, Zhongmin; Kushner, Mark J.

    2011-10-01

    Electric discharge excimer lasers are sustained in multi-atmosphere attaching gas mixtures that are typically preionized to enable a reproducible, uniform glow, which maximizes optical quality and gain. This preionization is often accomplished using UV light produced by a corona discharge within the plasma cavity. To quantify the relationship between corona discharge properties and those of the laser discharge, the triggering of electron avalanche by preionizing UV light in an electric discharge-pumped ArF* excimer laser was numerically investigated using a two-dimensional model. The preionizing UV fluxes were generated by a corona-bar discharge driven by the same voltage pulse as the main discharge sustained in a multi-atmospheric Ne/Ar/Xe/F2 gas mixture. The resulting peak photo-electron density in the inter-electrode spacing is around 108 cm-3, and its distribution is biased toward the UV source. The preionization density increases with increasing dielectric constant and capacitance of the corona bar. The symmetry and uniformity of the discharge are, however, improved significantly once the main avalanche develops. In addition to bulk electron impact ionization, the ionization generated by sheath accelerated secondary electrons was found to be important in sustaining the discharge current at experimentally observed values. At peak current, the magnitude of the ionization by sheath accelerated electrons is comparable to that from bulk electron impact in the vicinity of the cathode.

  4. Single-Photon Ionization Soft-X-Ray Laser Mass Spectrometry of Potential Hydrogen Storage Materials

    Science.gov (United States)

    Dong, F.; Bernstein, E. R.; Rocca, J. J.

    A desk-top size capillary discharge 46.9 nm lasear is applied in the gas phase study of nanoclusters. The high photon energy allows for single-photon ionization mass spectrometry with reduced cluster fragmentation. In the present studies, neutral Al m C n and Al m C n H x cluster are investigation for the first time. Single photon ionization through 46.9 nm, 118 nm, 193 nm lasers is used to detect neutral cluster distributions through time of flight mass spectrometry. Al m C n clusters are generated through laser ablation of a mixture of Al and C powders pressed into a disk. An oscillation of the vertical ionization energies (VIEs) of Al m C n clusters is observed in the experiments. The VIEs of Al m C n clusters changes as a function of the numbers of Al and C atoms in the clusters. Al m C n H x clusters are generated through an Al ablation plasma-hydrocarbon reaction, an Al-C ablation plasma reacting with H2 gas, or through cold Al m C n clusters reacting with H2 gas in a fast flow reactor. DFT and ab inito calculations are carried out to explore the structures, IEs, and electronic structures of Al m C n H x clusters. C=C bonds are favored for the lowest energy structures for Al m C n clusters. Be m C n H x are generated through a beryllium ablation plasma-hydrocarbon reaction and detected by single photon ionization of 193 nm laser. Both Al m C n H x and Be m C n H x are considered as potential hydrogen storage materials.

  5. Examination of excited state populations in sputtering using Multiphoton Resonance Ionization

    International Nuclear Information System (INIS)

    Kimock, F.M.; Baxter, J.P.; Pappas, D.L.; Kobrin, P.H.; Winograd, N.

    1984-01-01

    Multiphoton Resonance Ionization has been employed to study the populations of excited state atoms ejected from ion bombarded metal surfaces. Preliminary investigations have focused on three model systems: aluminum, indium and cobalt. In this paper the authors examine the effect of primary ion energy (2 to 12 keV Ar + ) on excited state yields for these three systems. The influence of the sample matrix on excited state populations of sputtered atoms is also discussed

  6. Use of a radio-frequency resonance circuit in studies of alkali ionization in flames

    International Nuclear Information System (INIS)

    Borgers, A.J.

    1978-01-01

    The context of the investigations are outlined with a short review about recent flame studies at Utrecht University and a discussion about discrepancies and agreements in the literature concerning alkali ionization in flames. The measuring technique chosen is described and the general design of the radio-frequency resonance system presented. The optical track measurements and the theoretical calculations of flame rise velocity are dealt with. The collisional ionization rate constants for Na, K and Cs are determined. The collisional-ionization rate constant for lithium is treated separately by reason of the hydroxide formation. Finally a theoretical model for the conducting flame in a weak, alternating electric field is developed. The relation betaeen the admittance and the flame conductivity in first order approximations is derived. (Auth.)

  7. Radioactive beams produced by the ISOL method: development for laser ionization and for surface ionization; Faisceaux exotiques par methode ISOL: developpements pour l'ionisation par laser et l'ionisation de surface

    Energy Technology Data Exchange (ETDEWEB)

    Hosni, Faouzi

    2004-10-01

    The works were carried out in the framework of the research program PARRNe (production of radioactive neutron-rich nuclei). This program aims to determine optimal conditions to produce intense beams of neutron-rich isotopes. This thesis treats multiple technical aspects related to the production of separate radioactive isotopes in line (ISOL). It deals mainly with the development of the target-source unit which is the key element for projects such as SPIRAL-2 or EURISOL.The first part presents the various methods using fission as production mode and compares them: fission induced by thermal neutrons, induced by fast neutrons and photofission. The experiment carried out at CERN validated the interest of the photofission as a promising production mode of radioactive ions. That is why the institute of nuclear physics of Orsay decided to build a linear electron accelerator at the Tandem d'Orsay (ALTO).The second part of this thesis deals with the development of uranium targets. The X-rays diffraction and Scanning Electron Microscopy have been used as analysis techniques. They allowed to determine the chemical and structural characteristics of uranium carbide targets as function of various heating temperatures. After the production, the process of ionization has been studied. Two types of ion source have been worked out: the first one is a surface ion source and the second one is a source based on resonant ionization by laser. These two types of sources will be used for the ALTO project. (author)

  8. Fundamentals of metasurface lasers based on resonant dark states

    International Nuclear Information System (INIS)

    Droulias, Sotiris; Technology - Hellas; Jain, Aditya; Koschny, Thomas; Soukoulis, Costas M.; Technology - Hellas; Ames Laboratory and Iowa State University, Ames, IA

    2017-01-01

    Recently, our group proposed a metamaterial laser design based on explicitly coupled dark resonant states in low-loss dielectrics, which conceptually separates the gain-coupled resonant photonic state responsible for macroscopic stimulated emission from the coupling to specific free-space propagating modes, allowing independent adjustment of the lasing state and its coherent radiation output. Due to this functionality, it is now possible to make lasers that can overcome the trade-off between system dimensions and Q factor, especially for surface emitting lasers with deeply subwavelength thickness. In this paper, we give a detailed discussion of the key functionality and benefits of this design, such as radiation damping tunability, directionality, subwavelength integration, and simple layer-by-layer fabrication. Finally, we examine in detail the fundamental design tradeoffs that establish the principle of operation and must be taken into account and give guidance for realistic implementations.

  9. A validation of a simple model for the calculation of the ionization energies in X-ray laser-cluster interactions

    Energy Technology Data Exchange (ETDEWEB)

    White, Jeff; Ackad, Edward [Department of Physics, Southern Illinois University Edwardsville, Edwardsville, Illinois 62026 (United States)

    2015-02-15

    The outer-ionization of an electron from a cluster is an unambiguous quantity, while the inner-ionization threshold is not, resulting in different microscopic quantum-classical hybrid models used in laser-cluster interactions. A simple local ionization threshold model for the change in the ionization energy is proposed and examined, for atoms and ions, at distances in between the initial configuration of the cluster to well into the cluster's disintegration. This model is compared with a full Hartree-Fock energy calculation which accounts for the electron correlation effects using the coupled cluster method with single and double excitations with perturbative triples (CCSD(T)). Good agreement is found between the two lending a strong theoretical support to works which rely on such models for the final and transient properties of the laser-cluster interaction.

  10. Internuclear Separation Dependent Ionization of the Valence Orbitals of I2 by Strong Laser Fields

    Science.gov (United States)

    Chen, H.; Tagliamonti, V.; Gibson, G. N.

    2012-11-01

    Using a pump-dump-probe technique and Fourier-transform spectroscopy, we study the internuclear separation R dependence and relative strength of the ionization rates of the π and σ electrons of I2, whose valence orbitals are σg2πu4πg4σu0. We find that ionization of the highest occupied molecular orbital (HOMO)-2 (σg) has a strong dependence on R while the HOMO and HOMO-1 do not. Surprisingly, the ionization rate of the HOMO-2 exceeds the combined ionization rate of the less bound orbitals and this branching ratio increases with R. Since our technique produces target molecules that are highly aligned with the laser polarization, the σ orbitals will be preferentially ionized and undergo enhanced ionization at larger R compared to the π orbitals. Nevertheless, it is highly unusual that an inner orbital provides the dominant strong field ionization pathway in a small molecule.

  11. Pulse length of ultracold electron bunches extracted from a laser cooled gas

    Directory of Open Access Journals (Sweden)

    J. G. H. Franssen

    2017-07-01

    Full Text Available We present measurements of the pulse length of ultracold electron bunches generated by near-threshold two-photon photoionization of a laser-cooled gas. The pulse length has been measured using a resonant 3 GHz deflecting cavity in TM110 mode. We have measured the pulse length in three ionization regimes. The first is direct two-photon photoionization using only a 480 nm femtosecond laser pulse, which results in short (∼15 ps but hot (∼104 K electron bunches. The second regime is just-above-threshold femtosecond photoionization employing the combination of a continuous-wave 780 nm excitation laser and a tunable 480 nm femtosecond ionization laser which results in both ultracold (∼10 K and ultrafast (∼25 ps electron bunches. These pulses typically contain ∼103 electrons and have a root-mean-square normalized transverse beam emittance of 1.5 ± 0.1 nm rad. The measured pulse lengths are limited by the energy spread associated with the longitudinal size of the ionization volume, as expected. The third regime is just-below-threshold ionization which produces Rydberg states which slowly ionize on microsecond time scales.

  12. Electron paramagnetic resonance study on the ionizing radiation induced defects of the tooth enamel hydroxyapatite

    International Nuclear Information System (INIS)

    Oliveira, Liana Macedo de

    1995-01-01

    Hydroxyapatite is the main constituent of calcified tissues. Defects induced by ionizing radiations in this biomineral can present high stability and then, these are used as biological markers in radiological accidents, irradiated food identifying and geological and archaeological dating. In this work, paramagnetic centers induced on the enamel of the teeth by environmental ionizing radiation, are investigated by electron paramagnetic resonance (EPR). Decay thermal kinetic presents high complexity and shows the formation of different electron ligation energy centers and structures

  13. Feasibility study of the single particle analysis of uranium by laser ionization time-of-flight mass spectrometry

    International Nuclear Information System (INIS)

    Ha, Yeong Keong; Han, Sun Ho; Pyo, Hyung Yeol; Park, Yong Joon; Song, Kyu Seok

    2004-01-01

    The control of activities in nuclear facilities worldwide is one of the most important tasks of nuclear safeguard. To meet the needs for nuclear safeguard, International Atomic Energy Agency (IAEA) strengthened the control of nuclear activities to detect these activities earlier. Thus, it is very important to develop analytical techniques to determine the isotopic composition of hot particles from swipe samples. The precise measurement of the 234 U/ 238 U, 235 U/ 238 U and 236 U/ 238 U ratios is important because it provides information about the initial enrichment of reactor uranium, core history, and post accident story. Because conventional α-spectrometry is not sufficiently sensitive for the determination of long-lived radionuclides in environmental samples, several analytical techniques, such as SNMS (Sputtered Neutral Mass Spectrometry), RIMS (Resonance Ionization Mass Spectrometry), AMS (Accelerator Mass Spectrometry) etc., have been proposed for uranium isotope measurements. In case of microparticles, analytical techniques such as SIMS (Secondary Ion Mass Spectrometry) have been applied for the isotopic characterization. The aim of this work was the development of a sensitive analytical technique for determination of isotopic ratio of uranium in swipe samples. In this work, feasibility of LIMS (Laser Ionization Mass Spectrometry) for the determination of such particles has been evaluated using a reference material of natural uranium

  14. Self-resonant wakefield excitation by intense laser pulse in plasmas

    International Nuclear Information System (INIS)

    Andreev, N.E.; Pogosova, A.A.; Gorbunov, L.M.; Ramazashvili, R.R.; Kirsanov, V.I.

    1993-01-01

    It is demonstrated by theoretical analysis and numerical calculations that in an underdense plasma the process of three-dimensional evolution of the short and strong laser pulse (with duration equal to several plasma periods) leads to compression and self-modulation of the pulse, so that during a fairly long period of time beats of pulse amplitude generates resonantly a strong and stable plasma wakefield. The intensity of the wake-field is so high that it can provide a new promising outlook for the plasma based accelerator concept. Linear analysis of dispersion relation predicts that taking into account transverse component of wavenumber considerably increases the growth rate of resonance instability of the pulse. The numerical simulations demonstrate that considered self-focusing and resonant-modulation instability are essentially three dimensional processes. Laser field evolution in each transverse cross section of the pulse is synchronized by the regular structure of plasma wave that is excited by the pulse. The considered effect of resonant modulation has a threshold. For the pulses with the intensity below the threshold the refraction dominates and no modulation appears. The studied phenomenon can be referred to as the Self-Resonant Wakefield (SRWF) excitation that is driven by self-focusing and self-modulation of laser pulse with quite a moderate initial duration. In fact, this method of excitation differs from both suggested in Ref.1 (PBWA) and in Refs.2,3 (LWFA), being even more than the combination of these concepts. Unlike the first scheme it does not require initially the two-frequency laser pulse, since the modulation here appears in the most natural way due to evolution of the pulse. In contrast with the LWFA, the considered SRWF generation scheme gives the possibility to raise the intensity of wake-excitation due to pulse self-focusing ( initial stage) and self modulation (second stage)

  15. Near resonant absorption by atoms in intense fluctuating laser fields

    International Nuclear Information System (INIS)

    Smith, S.J.

    1994-01-01

    The objective of this program was to make quantitative measurements of the effects of higher-order phase/frequency correlations in a laser beam on nonlinear optical absorption processes in atoms. The success of this program was due in large part to a unique experimental capability for modulating the extracavity beam of a stabilized (approx-lt 200 kHz) continuous-wave laser with statistically-well-characterized stochastic phase (or frequency) fluctuations, in order to synthesize laser bandwidths to ∼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 1/2 (F = 2, M F = 2) → 3P 3/2 (F = 3, M F = 3) two- level Na resonance, using a weak probe to the 4D 5/2 level; (2) the variance and spectra of fluorescence intensity fluctuations in the two-level Na resonance; (3) the Hanle effect in the 1 S 0 - 3 P 1 , transition at λ = 555.6 nm in 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

  16. Examination of excited state populations in sputtering using multiphoton resonance ionization

    International Nuclear Information System (INIS)

    Kimock, F.M.; Baxter, J.P.; Pappas, D.L.; Kobrin, P.H.; Winograd, N.

    1984-01-01

    Multiphoton Resonance Ionization has been employed to study the populations of excited state atoms ejected from ion bombarded metal surfaces. Preliminary investigations have focused on three model systems: aluminum, indium and cobalt. In this paper we examine the effect of primary ion energy (2 to 12 keV Ar + ) on excited state yields for these three systems. The influence of the sample matrix on excited state populations of sputtered atoms is also discussed. 8 refs., 4 figs

  17. Ionization and bound-state relativistic quantum dynamics in laser-driven multiply charged ions

    International Nuclear Information System (INIS)

    Hetzheim, Henrik

    2009-01-01

    The interaction of ultra-strong laser fields with multiply charged hydrogen-like ions can be distinguished in an ionization and a bound dynamics regime. Both are investigated by means of numerically solving the Dirac equation in two dimensions and by a classical relativistic Monte-Carlo simulation. For a better understanding of highly nonlinear physical processes the development of a well characterized ultra-intense relativistic laser field strength has been driven forward, capable of studying e.g. the magnetic field effects of the laser resulting in an additional electron motion in the laser propagation direction. A novel method to sensitively measure these ultra-strong laser intensities is developed and employed from the optical via the UV towards the XUV frequency regime. In the bound dynamics field, the determination of multiphoton transition matrixelements has been investigated between different bound states via Rabi oscillations. (orig.)

  18. Ionization and bound-state relativistic quantum dynamics in laser-driven multiply charged ions

    Energy Technology Data Exchange (ETDEWEB)

    Hetzheim, Henrik

    2009-01-14

    The interaction of ultra-strong laser fields with multiply charged hydrogen-like ions can be distinguished in an ionization and a bound dynamics regime. Both are investigated by means of numerically solving the Dirac equation in two dimensions and by a classical relativistic Monte-Carlo simulation. For a better understanding of highly nonlinear physical processes the development of a well characterized ultra-intense relativistic laser field strength has been driven forward, capable of studying e.g. the magnetic field effects of the laser resulting in an additional electron motion in the laser propagation direction. A novel method to sensitively measure these ultra-strong laser intensities is developed and employed from the optical via the UV towards the XUV frequency regime. In the bound dynamics field, the determination of multiphoton transition matrixelements has been investigated between different bound states via Rabi oscillations. (orig.)

  19. Barium Tagging from nEXO Using Resonance Ionization Spectroscopy

    Science.gov (United States)

    Twelker, K.; Kravitz, S.

    nEXO is a 5-ton liquid enriched-xenon time projection chamber (TPC) to search for neutrinoless double-beta decay, designed to have the sensitivity to completely probe the inverted mass hierarchy of Majorana neutrinos. The detector will accommodate-as a background reduction technique-a system to recover and identify the barium decay product. This upgrade will allow a background-free measurement of neutrinoless double-beta decay and increase the half-life sensitivity of the experiment by at least one order of magnitude. Ongoing research and development includes a system to test barium extraction from liquid xenon using surface adsorption and Resonance Ionization Spectroscopy (RIS).

  20. Detection of polychlorinated biphenyls in transformer oils in Vietnam by multiphoton ionization mass spectrometry using a far-ultraviolet femtosecond laser as an ionization source.

    Science.gov (United States)

    Duong, Vu Thi Thuy; Duong, Vu; Lien, Nghiem Thi Ha; Imasaka, Tomoko; Tang, Yuanyuan; Shibuta, Shinpei; Hamachi, Akifumi; Hoa, Do Quang; Imasaka, Totaro

    2016-03-01

    Polychlorinated biphenyls (PCBs) in transformer and food oils were measured using gas chromatography combined with multiphoton ionization mass spectroscopy. An ultrashort laser pulse emitting in the far-ultraviolet region was utilized for efficient ionization of the analytes. Numerous signal peaks were clearly observed for a standard sample mixture of PCBs when the third and fourth harmonic emissions (267 and 200nm) of a femtosecond Ti:sapphire laser (800nm) were employed. The signal intensities were found to be greater when measured at 200nm compared with those measured at 267nm, providing lower detection limits especially for highly chlorinated PCBs at shorter wavelengths. After simple pretreatment using disposable columns, PCB congeners were measured and found to be present in the transformer oils used in Vietnam. Copyright © 2015 Elsevier B.V. All rights reserved.

  1. Bistable laser device with multiple coupled active vertical-cavity resonators

    Science.gov (United States)

    Fischer, Arthur J.; Choquette, Kent D.; Chow, Weng W.

    2003-08-19

    A new class of bistable coupled-resonator vertical-cavity semiconductor laser devices has been developed. These bistable laser devices can be switched, either electrically or optically, between lasing and non-lasing states. A switching signal with a power of a fraction of a milliwatt can change the laser output of such a device by a factor of a hundred, thereby enabling a range of optical switching and data encoding applications.

  2. Laser pulse propagation in a meter scale rubidium vapor/plasma cell in AWAKE experiment

    Energy Technology Data Exchange (ETDEWEB)

    Joulaei, A. [Max-Planck Institute for Physics, Munich (Germany); University of Mazandaran (Iran, Islamic Republic of); Moody, J. [Max-Planck Institute for Physics, Munich (Germany); Berti, N.; Kasparian, J. [University of Geneva (Switzerland); Mirzanejhad, S. [University of Mazandaran (Iran, Islamic Republic of); Muggli, P. [Max-Planck Institute for Physics, Munich (Germany)

    2016-09-01

    We present the results of numerical studies of laser pulse propagating in a 3.5 cm Rb vapor cell in the linear dispersion regime by using a 1D model and a 2D code that has been modified for our special case. The 2D simulation finally aimed at finding laser beam parameters suitable to make the Rb vapor fully ionized to obtain a uniform, 10 m-long, at least 1 mm in radius plasma in the next step for the AWAKE experiment. - Highlights: • Discussion the AWAKE plasma source based on photoionization of rubidium vapor with a TW/cm^2 Intensity laser with a spectrum across valence ground state transition resonances. • Examines the propagation of the AWAKE ionization laser through rubidium vapor at design density on a small scale and reduced intensity with a linear numerical model compared to experimental results. • Discusses physics of pulse propagation through the vapor at high intensity regime where strong ionization occurs within the laser pulse.

  3. Direct analysis of triterpenes from high-salt fermented cucumbers using infrared matrix-assisted laser desorption electrospray ionization (IR-MALDESI)

    Science.gov (United States)

    High-salt samples present a challenge to mass spectrometry (MS) analysis, particularly when electrospray ionization (ESI) is used, requiring extensive sample preparation steps such as desalting, extraction, and purification. In this study, infrared matrix-assisted laser desorption electrospray ioniz...

  4. Questioning the observation of laser-assisted ionization in fast collisions of He(2 /sup 1,3/S) with He

    International Nuclear Information System (INIS)

    Gillen, K.T.

    1989-01-01

    In four recent papers Pradel et al. [Phys. Rev. Lett. 54, 2600 (1985); Phys. Rev. A 35, 1062 (1987)] and Monchicourt et al. [Phys. Rev. A 33, 3515 (1986); Chem. Phys. Lett. 152, 336 (1988)] give arguments claiming the observation of laser-assisted ionization of the short-lived collision complex formed during collisions of He/sup */(2 /sup 1,3/S) with He. However, estimates of the relative sizes of the assisted and unassisted ion signals observed make it very unlikely that laser-assisted ionization has been observed in those experiments. Collisional excitation to higher He/sup */ states, followed by (single-photon) ionization of the excited states, seems a more likely explanation at all energies considered

  5. A chemically selective laser ion source for the on-line isotope separation

    International Nuclear Information System (INIS)

    Scheerer, F.

    1993-03-01

    In this thesis a laser ion source is presented. In a hot chamber the atoms of the elements to be studied are resonantly by light of pulsed dye lasers, which are pumped by pulsed copper-vapor lasers with extremely high pulse repetition rate (ν rep ∼ 10 kHz), stepwise excited and ionized. By the storage of the atoms in a hot chamber and the high pulse repetition rate of the copper-vapor lasers beyond the required high efficiency (ε ∼ 10%) can be reached. First preparing measurements were performed at the off-line separator at CERN with the rare earth elements ytterbium and thulium. Starting from the results of these measurements further tests of the laser ion source were performed at the on-line separator with in a thick tantalum target produced neutron-deficient ytterbium isotopes. Under application of a time-of-flight mass spectrometer in Mainz an efficient excitation scheme on the resonance ionization of tin was found. This excitation scheme is condition for an experiment at the GSI for the production of the extremely neutron-deficient, short-lived nucleus 102 Sn. In the summer 1993 is as first application of the newly developed laser ion source at the PSB-ISOLDE at CERN an astrophysically relevant experiment for the nuclear spectroscopy of the neutron-rich silver isotopes 124-129 Ag is planned. This experiment can because of the lacking selectivity of conventional ion sources only be performed by means of the here presented laser ion source. The laser ion source shall at the PSB-ISOLDE 1993 also be applied for the selective ionization of manganese. (orig./HSI) [de

  6. Calibration of matrix-assisted laser desorption/ionization time-of-flight peptide mass fingerprinting spectra

    DEFF Research Database (Denmark)

    Hjernø, Karin; Højrup, Peter

    2007-01-01

    This chapter describes a number of aspects important for calibration of matrix-assisted laser desorption/ionization time-of-flight spectra prior to peptide mass fingerprinting searches. Both multipoint internal calibration and mass defect-based calibration is illustrated. The chapter describes ho...

  7. Multi-photon ionization of the H+2 molecule by an xuv laser pulse

    International Nuclear Information System (INIS)

    Secor, Ethan; Guan Xiaoxu; Bartschat, Klaus; Schneider, Barry I

    2012-01-01

    We present theoretical predictions for one-, two-, and three-photon ionization of H + 2 by an xuv laser pulse. The results were obtained by solving the time-dependent Schrödinger equation in prolate spheroidal coordinates. Good agreement is obtained with results from a time-independent perturbative model.

  8. Ultratrace Uranium Fingerprinting with Isotope Selective Laser Ionization Spectrometry

    International Nuclear Information System (INIS)

    Ziegler, Summer L.; Bushaw, Bruce A.

    2008-01-01

    Uranium isotope ratios can provide source information for tracking uranium contamination in a variety of fields, ranging from occupational bioassay to monitoring aftereffects of nuclear accidents. We describe the development of Isotope Selective Laser Ionization Spectrometry (ISLIS) for ultratrace measurement of the minor isotopes 234U, 235U, and 236U with respect to 238U. Optical isotopic selectivity in three-step excitation with single-mode continuous wave lasers is capable of measuring the minor isotopes at relative abundances below 1 ppm, and is not limited by isobaric interferences such as 235UH+ during measurement of 236U. This relative abundance limit approaches the threshold for measurement of uranium minor isotopes with conventional mass spectrometry, typically 10-7, but without mass spectrometric analysis of the laser-created ions. Uranyl nitrate standards from an international blind comparison were used to test analytical performance for different isotopic compositions and with quantities ranging from 11 ng to 10 (micro)g total uranium. Isotopic ratio determination was demonstrated over a linear dynamic range of 7 orders of magnitude with a few percent relative precision and detection limits below 500 fg for the minor isotopes

  9. Dissociation and ionization of molecular ions by ultra-short intense laser pulses probed by coincidence 3D momentum imaging

    International Nuclear Information System (INIS)

    Ben-Itzhak, Itzik; Wang, Pengqian; Xia, Jiangfan; Max Sayler, A.; Smith, Mark A.; Maseberg, J.W.; Carnes, Kevin D.; Esry, Brett D.

    2005-01-01

    We have experimentally explored laser-induced dissociation and ionization of diatomic molecular ions using coincidence 3D momentum imaging. The vibrationally excited molecular ion beam (4-8 keV) is crossed by an ultrafast intense laser beam (28-200 fs, 10 13 -10 14 W/cm 2 ). The resulting fragments are recorded in coincidence by a time and position-sensitive detector. Complete angular distributions and kinetic energy release maps are reconstructed from the measured dissociation-momentum vectors. The angular distribution of the H + + H fragments was found to be strongly correlated to their kinetic energy release upon dissociation. Low KER was associated with very narrow angular distributions and high KER with distributions peaking away from the laser polarization. Ionization was found to be smaller than dissociation and increased with laser intensity. The H + + H + fragments have a very narrow angular distribution along the laser polarization

  10. Development of high-power CO2 lasers and laser material processing

    Science.gov (United States)

    Nath, Ashish K.; Choudhary, Praveen; Kumar, Manoj; Kaul, R.

    2000-02-01

    Scaling laws to determine the physical dimensions of the active medium and optical resonator parameters for designing convective cooled CO2 lasers have been established. High power CW CO2 lasers upto 5 kW output power and a high repetition rate TEA CO2 laser of 500 Hz and 500 W average power incorporated with a novel scheme for uniform UV pre- ionization have been developed for material processing applications. Technical viability of laser processing of several engineering components, for example laser surface hardening of fine teeth of files, laser welding of martensitic steel shroud and titanium alloy under-strap of turbine, laser cladding of Ni super-alloy with stellite for refurbishing turbine blades were established using these lasers. Laser alloying of pre-placed SiC coating on different types of aluminum alloy, commercially pure titanium and Ti-6Al-4V alloy, and laser curing of thermosetting powder coating have been also studied. Development of these lasers and results of some of the processing studies are briefly presented here.

  11. Resonantly-pumped soft-x-ray lasers using ICF drivers

    International Nuclear Information System (INIS)

    Hagelstein, P.L.

    1982-12-01

    Some aspects of laser design relating to experiments planned for the NOVETTE laser system at Livermore in early 1983 are discussed. The experiments are aimed at testing several resonantly-pumped lasers with transition energies between 42.3 eV and 153 eV. These experiments follow several years of theoretical work, a set of flashlamp characterization experiments performed on the SHIVA laser system (LLNL) in December, 1981, and some high precision spectroscopic studies carried out at KMS during the summer of 1982. Some of the major physics design issues as the relate to the experiments, and some of the numerical simulations that have been carried out so far are reviewed

  12. Laser ion sources

    Energy Technology Data Exchange (ETDEWEB)

    Bykovskij, Yu

    1979-02-01

    The characteristics a laser source of multiply-ionized ions are described with regard to the interaction of laser radiation and matter, ion energy spectrum, angular ion distribution. The amount of multiple-ionization ions is evaluated. Out of laser source applications a laser injector of multiple-ionization ions and nuclei, laser mass spectrometry, laser X-ray microradiography, and a laser neutron generators are described.

  13. XeCl excimer laser with new prism resonator configurations and its performance characteristics

    Energy Technology Data Exchange (ETDEWEB)

    Benerji, N. S., E-mail: nsb@rrcat.gov.in, E-mail: bsingh@rrcat.gov.in; Singh, A.; Varshnay, N.; Singh, Bijendra, E-mail: nsb@rrcat.gov.in, E-mail: bsingh@rrcat.gov.in [Excimer Laser Section, LMPD, Raja Ramanna Center for Advanced Technology, Indore 452013 (India)

    2015-07-15

    New resonator cavity configurations, namely, the prism resonator and unstable prism resonator, are demonstrated for the first time in an excimer (XeCl) laser with interesting and novel results. High misalignment tolerance ∼50 mrad is achieved with considerably reduced beam divergence of less than ∼1 mrad without reduction in output power capabilities of the laser. The misalignment tolerance of ∼50 mrad is a dramatic improvement of ∼25 times compared to ∼2 mrad normally observed in standard excimer laser with plane-plane cavity. Increase in depth of focus from 3 mm to 5.5 mm was also achieved in case of prism resonator configuration with an improvement of about 60%. Unstable prism resonator configuration is demonstrated here in this paper with further reduction in beam divergence to about 0.5 mrad using plano-convex lens as output coupler. The misalignment tolerance in case of unstable prism resonator was retained at about 30 mrad which is a high value compared to standard unstable resonators. The output beam spot was completely filled with flat-top profile with prism resonator configurations, which is desired for various material processing applications. Focusing properties and beam divergence in case of prism resonator have been investigated using SEM (scanning electron microscope) images. SEM images of the focused spot size (∼20 μm holes) on metal sheet indicate beam divergence of about 0.05 mrad which is about 1.5 times diffraction limit. Energy contained in this angle is thus sufficient for micro-machining applications. Clean and sharp edges of the micro-holes show high pointing stability with multiple shot exposures. Such characteristics of the excimer laser system will be extremely useful in micro-machining and other field applications.

  14. Adiabatic theory of ionization of atoms by intense laser pulses

    International Nuclear Information System (INIS)

    Tolstikhin, Oleg I; Morishita, Toru; Watanabe, Shinichi

    2009-01-01

    As a first step towards the adiabatic theory of ionization of atoms by intense laser pulses, here we consider the simplest one-dimensional zero-range potential model. The asymptotic solution to the time-dependent Schroedinger equation in the adiabatic regime is obtained and the photoelectron spectrum is calculated. The factorization formula for the photoelectron spectrum in the back-rescattering region, first suggested by Morishita et al. [Phys. Rev. Lett. 100, 013903 (2008)] on the basis of ab initio calculations, is derived analytically.

  15. Analytical applications of resonance ionization mass spectrometry (RIMS)

    International Nuclear Information System (INIS)

    Fassett, J.D.; Travis, J.C.

    1988-01-01

    A perspective on the role of resonance ionization mass spectrometry (RIMS) in the field of analytical chemistry is presented. RIMS provides new, powerful, and complementary capabilities relative to traditional methods of inorganic mass spectrometry. Much of the initial work in RIMS has been to illustrate these capabilities and define the potential of RIMS in the generalized field of chemical analysis. Three areas of application are reviewed here: (1) noble gas measurements; (2) materials analysis using isotope dilution (IDMS); and, (3) solids analysis using direct sampling. The role of RIMS is discussed relative to the more traditional mass spectrometric methods of analysis in these areas. The applications are meant to illustrate the present state-of-the-art as well as point to the future state-of-the-art of RIMS in chemical analysis. (author)

  16. On formation of a partially coherent beam in a stable-resonator laser

    International Nuclear Information System (INIS)

    Suvorov, A A

    2010-01-01

    A new method involving the expansion of the field coherence function in partially coherent modes - the eigensolutions of the problem for the second-order coherence function in a stable resonator - is proposed for the theoretical description of the process of multimode laser beam formation. The method for solving the problem for arbitrary partially coherent modes is formulated and the expressions for these modes are derived in the general form. The characteristics of the fundamental partially coherent mode, which coincides with the coherence function of a Gaussian partially coherent beam, are analysed in detail. The partially coherent modes are shown to possess two spatial scales - the effective radius and the coherence radius, which makes them a convenient tool for solving the problem of generation of a partially coherent beam. It is found that the unambiguous relation between the characteristics of partially coherent modes and the stable-resonator parameters is achieved by involving into consideration not only the process of the beam formation by the resonator mirrors but also the process of interaction of radiation with the active laser medium. (laser beams and resonators)

  17. Laser assisted nuclear decay spectroscopy: A new method for studying neutron-deficient francium

    CERN Document Server

    Lynch, Kara Marie

    2015-01-01

    Radioactive decay studies of rare isotopes produced at radioactive ion beam facilities have often been hindered by the presence of isobaric and isomeric contamination. The Collinear Resonance Ionization Spectroscopy (CRIS) experiment at ISOLDE, CERN uses laser radiation to stepwise excite and ionize an atomic beam in a particular isomeric state. Deflection of this selectively ionized beam of exotic nuclei, from the remaining neutral contaminants, allows ultra-sensitive detection of rare isotopes and nuclear structure measurements in background-free conditions.\

  18. A time-dependent B-spline R-matrix approach to double ionization of atoms by XUV laser pulses

    Energy Technology Data Exchange (ETDEWEB)

    Guan Xiaoxu; Zatsarinny, O; Noble, C J; Bartschat, K [Department of Physics and Astronomy, Drake University, Des Moines, IA 50311 (United States); Schneider, B I [Physics Division, National Science Foundation, Arlington, Virgina 22230 (United States)], E-mail: xiaoxu.guan@drake.edu, E-mail: oleg.zatsarinny@drake.edu, E-mail: cjn@maxnet.co.nz, E-mail: klaus.bartschat@drake.edu, E-mail: bschneid@nsf.gov

    2009-07-14

    We present an ab initio and non-perturbative time-dependent approach to the problem of double ionization of a general atom driven by intense XUV laser pulses. After using a highly flexible B-spline R-matrix method to generate field-free Hamiltonian and electric dipole matrices, the initial state is propagated in time using an efficient Arnoldi-Lanczos scheme. Test calculations for double ionization of He by a single laser pulse yield good agreement with benchmark results obtained with other methods. The method is then applied to two-colour pump-probe processes, for which momentum and energy distributions of the two outgoing electrons are presented.

  19. Electrospray Ionization Fourier Transform Ion Cyclotron Resonance Analysis of Large Polymerases Chain Reaction Products

    International Nuclear Information System (INIS)

    Wunschel, David S.; Pasa Tolic, Ljiljana; Feng, Bingbing; Smith, Richard D.

    2000-01-01

    We have attempted to expand the size range of PCR products that can be analyzed by electroscopy ionization (ESI) Fourier transformion cyclotron resonance (FTICR) mass spectrometry. The mass measurement accuracy obtained illustrates that a signel base substitution could be identified at the size of PCR product with a 7 tesla ESI-FTICR

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

    CERN Multimedia

    Rothe, S

    2014-01-01

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

  1. Laser-based secondary neutral mass spectroscopy: Useful yield and sensitivity

    International Nuclear Information System (INIS)

    Young, C.E.; Pellin, M.J.; Calaway, W.F.; Joergensen, B.; Schweitzer, E.L.; Gruen, D.M.

    1986-01-01

    A variety of problems exist in order to optimally apply resonance ionization spectroscopy (RIS) to the detection of sputtered neutral atoms, however. Several of these problems and their solutions are examined in this paper. First, the possible useful yields obtainable and the dependence of useful yield on various laser parameters for this type of sputtered neutral mass spectrometer (SNMS) are considered. Second, the choice of a mass spectrometer and its effect on the instrumental useful yield is explored in light of the unique ionization region for laser based SNMS. Finally a brief description of noise sources and their effect on the instrumental sensitivity is discussed. 33 refs., 12 figs

  2. Approaches for the analysis of low molecular weight compounds with laser desorption/ionization techniques and mass spectrometry.

    Science.gov (United States)

    Bergman, Nina; Shevchenko, Denys; Bergquist, Jonas

    2014-01-01

    This review summarizes various approaches for the analysis of low molecular weight (LMW) compounds by different laser desorption/ionization mass spectrometry techniques (LDI-MS). It is common to use an agent to assist the ionization, and small molecules are normally difficult to analyze by, e.g., matrix assisted laser desorption/ionization mass spectrometry (MALDI-MS) using the common matrices available today, because the latter are generally small organic compounds themselves. This often results in severe suppression of analyte peaks, or interference of the matrix and analyte signals in the low mass region. However, intrinsic properties of several LDI techniques such as high sensitivity, low sample consumption, high tolerance towards salts and solid particles, and rapid analysis have stimulated scientists to develop methods to circumvent matrix-related issues in the analysis of LMW molecules. Recent developments within this field as well as historical considerations and future prospects are presented in this review.

  3. Measurement of laser activated electron tunneling from semiconductor zinc oxide to adsorbed organic molecules by a matrix assisted laser desorption ionization mass spectrometer

    International Nuclear Information System (INIS)

    Zhong Hongying; Fu Jieying; Wang Xiaoli; Zheng Shi

    2012-01-01

    Highlights: ► Irradiation of photons with energies more than the band gap generates electron–hole pairs. ► Electron tunneling probability is dependent on the electron mobility. ► Tunneling electrons are captured by charge deficient atoms. ► Unpaired electrons induce cleavages of chemical bonds. - Abstract: Measurement of light induced heterogeneous electron transfer is important for understanding of fundamental processes involved in chemistry, physics and biology, which is still challenging by current techniques. Laser activated electron tunneling (LAET) from semiconductor metal oxides was observed and characterized by a MALDI (matrix assisted laser desorption ionization) mass spectrometer in this work. Nanoparticles of ZnO were placed on a MALDI sample plate. Free fatty acids and derivatives were used as models of organic compounds and directly deposited on the surface of ZnO nanoparticles. Irradiation of UV laser (λ = 355 nm) with energy more than the band gap of ZnO produces ions that can be detected in negative mode. When TiO 2 nanoparticles with similar band gap but much lower electron mobility were used, these ions were not observed unless the voltage on the sample plate was increased. The experimental results indicate that laser induced electron tunneling is dependent on the electron mobility and the strength of the electric field. Capture of low energy electrons by charge-deficient atoms of adsorbed organic molecules causes unpaired electron-directed cleavages of chemical bonds in a nonergodic pathway. In positive detection mode, electron tunneling cannot be observed due to the reverse moving direction of electrons. It should be able to expect that laser desorption ionization mass spectrometry is a new technique capable of probing the dynamics of electron tunneling. LAET offers advantages as a new ionization dissociation method for mass spectrometry.

  4. Laser enhanced microwave plasma isotope separation. Final report, September 30, 1992--September 29, 1995

    International Nuclear Information System (INIS)

    Brake, M.L.; Gilgenbach, R.M.

    1996-06-01

    The experimental research was to focus on laser excitation of a low abundance isotope and then ionize and separate the isotope of low abundance using a microwave/ECR discharge at 2.45 GHz. A small compact electron cyclotron resonance ion source, which uses permanent magnets, was constructed during this project. The dye laser was purchased and later an excimer laser had to also be purchased because it turned out that the dye laser could not be pumped by our copper laser. It was intended that the dye laser be tuned to a wavelength of 670.8 nm, which would excite 6 Li which would then be preferentially ionized by the ECR source and collected with a charged grid. The degree of enrichment was to be determined using thermal ionization mass spectrometry. The final objective of this project was to assess the feasibility of this system to large-scale production of stable isotopes. However the funding of this project was interrupted and we were not able to achieve all of our goals

  5. Collinear resonance ionization spectroscopy of radium ions

    CERN Multimedia

    We propose to study the neutron-deficient radium isotopes with high-resolution collinear resonance ionization spectroscopy. Probing the hyperfine structure of the $7{s}\\,^2\\!{S}\\!_{1/2}\\,\\rightarrow\\,7{p}\\,^{2}\\!{P}\\!_{1/2}$ and $7{s}\\,^{2}\\!{S}\\!_{1/2}\\,\\rightarrow\\,7{p}\\,^{2}\\!{P}\\!_{3/2}$ transitions in Ra II will provide atomic-structure measurements that have not been achieved for $^{{A}<208}$Ra. Measurement of the $7{s}\\,^{2}\\!{S}\\!_{1/2}\\,\\rightarrow\\,7{p}\\,^{2}\\!{P}\\!_{3/2}$ transition in $^{{A}<214}$Ra will allow the spectroscopic quadrupole moments to be directly measured for the first time. In addition, the technique will allow tentative spin assignments to be confirmed and the magnetic dipole moments measured for $^{\\textit{A}<208}$Ra. Measurement of the hyperfine structure (in particular the isotope shifts) of the neutron-deficient radium will provide information to further constrain the nuclear models away from the N=126 shell closure.

  6. Atmospheric pressure chemical ionization Fourier transform ion cyclotron resonance mass spectrometry for complex thiophenic mixture analysis

    KAUST Repository

    Hourani, Nadim; Andersson, Jan T.; Mö ller, Isabelle; Amad, Maan H.; Witt, Matthí as; Sarathy, Mani

    2013-01-01

    oil (VGO) and injected using the same method. The samples were analyzed using Fourier transform ion cyclotron resonance mass spectrometry (FTICR MS). RESULTS PASH model analytes were successfully ionized and mainly [M + H]+ ions were produced. The same

  7. Numerical simulation of laser resonators

    International Nuclear Information System (INIS)

    Yoo, J. G.; Jeong, Y. U.; Lee, B. C.; Rhee, Y. J.; Cho, S. O.

    2004-01-01

    We developed numerical simulation packages for laser resonators on the bases of a pair of integral equations. Two numerical schemes, a matrix formalism and an iterative method, were programmed for finding numeric solutions to the pair of integral equations. The iterative method was tried by Fox and Li, but it was not applicable for high Fresnel numbers since the numerical errors involved propagate and accumulate uncontrollably. In this paper, we implement the matrix method to extend the computational limit further. A great number of case studies are carried out with various configurations of stable and unstable r;esonators to compute diffraction losses, phase shifts, intensity distributions and phases of the radiation fields on mirrors. Our results presented in this paper show not only a good agreement with the results previously obtained by Fox and Li, but also the legitimacy of our numerical procedures for high Fresnel numbers.

  8. In gas laser ionization and spectroscopy experiments at the Superconducting Separator Spectrometer (S3): Conceptual studies and preliminary design

    International Nuclear Information System (INIS)

    Ferrer, R.; Bastin, B.; Boilley, D.; Creemers, P.; Delahaye, P.; Liénard, E.; Fléchard, X.; Franchoo, S.; Ghys, L.; Huyse, M.; Kudryavtsev, Yu.; Lecesne, N.; Lu, H.; Lutton, F.; Mogilevskiy, E.; Pauwels, D.; Piot, J.; Radulov, D.; Rens, L.; Savajols, H.

    2013-01-01

    Highlights: • A setup to perform In-Gas Laser Ionization and Spectroscopy experiments at the Super Separator Spectrometer is presented. • The reported studies address important aspects necessary to applied the IGLIS technique to short-lived isotopes. • An R and D phase required to reach an enhanced spectral resolution will be carried out at KU Leuven. • High-sensitivity and enhanced-resolution laser spectroscopy studies will be possible with the IGLIS setup at S 3 . -- Abstract: The results of preparatory experiments and the preliminary designs of a new in-gas laser ionization and spectroscopy setup, to be coupled to the Super Separator Spectrometer S 3 of SPIRAL2-GANIL, are reported. Special attention is given to the development and tests to carry out a full implementation of the in-gas jet laser spectroscopy technique. Application of this novel technique to radioactive species will allow high-sensitivity and enhanced-resolution laser spectroscopy studies of ground- and excited-state properties of exotic nuclei

  9. Resonance multiphoton ionization and dissociation of dimethyl ether via the {\\skew1\\tilde{\\rm C}^{\\prime}}, {\\skew1\\tilde{\\rm C}} and \\tilde{\\rm B} states

    Science.gov (United States)

    Mejia-Ospino, E.; García, G.; Guerrero, A.; Alvarez, I.; Cisneros, C.

    2005-01-01

    The three-photon resonance four-photon ionization and dissociation spectra of dimethyl ether (DME) are presented in the wavelength range 450-550 nm at 1 nm intervals. The (3+1) REMPI spectra show three prominent bands corresponding to the \\tildeB \\leftarrow \\skew1\\tildeX, {\\skew1\\tildeC} \\leftarrow \\skew1\\tildeX and {\\skew1\\tildeC^{\\prime}} \\leftarrow \\skew1\\tildeX transitions with origins at 61 457 cm-1 (7.615 eV), 59 055 cm-1 (7.322 eV) and 58 010 cm-1 (7.194 eV), respectively. Several ionized species, CH3+, CHnO+ (n = 1-3) and CH3OCH3+, are observed in the region of wavelengths studied here. In order to compare the results, a shorter wavelength multiphoton dissociation and ionization of DME at 355 nm is also presented. At this wavelength, DME undergoes neutral dissociation to CH3 and CH3O and each fragment is then ionized by multiphoton absorption. The fragmentation at 355 nm is very intense and only small fragments such as CH3+, CHO+, CH2+, CH+ and C+ ions are observed. The measurement of photoelectron energy allows us to establish that the DME ionization potential is at least 9.55 ± 0.15 eV. The experiments were performed using a Nd:YAG-OPO (optical parametric oscillator) tunable laser system coupled to a time-of-flight mass spectrometer and a hemispherical electron energy analyser.

  10. Investigation of parameters of the working substance - low temperature plasma in the ionization resonator chamber of the RF reactive engine

    International Nuclear Information System (INIS)

    Vdovin, V.S.; Zajtzev, B.V.; Kobetz, A.F.; Bomko, V.A.; Rashkovan, V.M.; Bazyma, L.A.; Belokon, V.I.

    2003-01-01

    This paper is the extension of investigations of the RF engine designed for orientation and stabilization of the spacecrafts orbit, and it is undertaken for measuring of plasma parameters of RF discharge in the ionization resonator chamber. The experiments were performed at the frequency of 80 MHz on the model engine, in which a length of coaxial line with shortening capacities at the ends was used as the ionization resonator chamber. As the result of the experiments, conditions of the RF discharge ignition in the resonator chamber are studied; dependencies of plasma density and temperature versus applied power and working body pressure are obtained for various gases. The measurements of the thrust were performed at the special-purpose test bench

  11. Laser spectroscopy and laser ion source development at UNISOR

    International Nuclear Information System (INIS)

    Bingham, C.

    1991-01-01

    The development of the laser spectroscopy facility at UNISOR will be described. The method of collinear laser-atomic beams interaction is utilized to achieve atomic spectra essentially free of Doppler spreading. Measurement of resonance fluorescence via an efficient fiber-optic light collector is used to observe the atomic excitation by the laser beam. The system has been utilized to measure the atomic lifetime of the 6p 4 Ps/2 0 level in Xe II. In other experiment the relativistic Doppler effect was measured as a test of time dilation. Hyperfine structure and isotope shift measurements have been made for a series of Tl atoms ranging in mass from 187 to 205. Magnetic dipole and electric quadrupole moments were deduced for several of these isotopes; these quantities and the isotope shifts added greatly to our understanding of nuclear shapes in this transition region. Future directions will focus around more sensitive detection techniques and the development of purer beams in order to enable the study of nuclei farther from stability. The development of a laser ion source which operates in a completely cold mode and utilizes resonant absorption in the ionization process world facilitate the production of ultra-pure atomic beams

  12. Dynamics of dissociation versus ionization in strong laser fields

    International Nuclear Information System (INIS)

    DiMauro, L.F.; Yang, B.

    1993-01-01

    In this paper, experimental results are presented which clearly demonstrate the effectiveness that an external field has in altering the dissociation dynamics. The experiment examines the strong-field dissociation dynamics of molecular hydrogen ions and its deuterated isotopes. These studies involve multiphoton excitation in the intensity regime of 10 11-14 W/cm 2 with the fundamental and second harmonic of a ND:YAG or ND:YLF laser system. Measurements include energy resolved electron and mass spectroscopy which provide useful probes in elucidating the interaction dynamics predicted by existing models. The example this in this paper, examines the strong-field dissociation of H 2 + , HD + , and D 2 + at green (0.5 μm) and (1μm) frequencies. The diatomic ions are formed via multiphonon ionization of the neutral precursor which is physically separable from the dissociation process. This study provides the first observation of the dynamics associated with the above threshold dissociation (ATD) process and analogies will be made with the more familiar above threshold ionization (ATI) phenomenon

  13. High power laser-matter interaction

    CERN Document Server

    Mulser, Peter

    2010-01-01

    This book intended as a guide for scientists and students who have just discovered the field as a new and attractive area of research, and for scientists who have worked in another field and want to join now the subject of laser plasmas. In the first chapter the plasma dynamics is described phenomenologically by a two fluid model and similarity relations from dimensional analysis. Chapter 2 is devoted to plasma optics and collisional absorption in the dielectric and ballistic model. Linear resonance absorption at the plasma frequency and its mild nonlinearities as well as the self-quenching of high amplitude electron plasma waves by wave breaking are discussed in Chapter 3. With increasing laser intensity the plasma dynamics is dominated by radiation pressure, at resonance producing all kinds of parametric instabilities and out of resonance leading to density steps, self-focusing and filamentation, described in Chapters 4 and 5. A self-contained treatment of field ionization of atoms and related phenomena ar...

  14. Influence of resonator length on catastrophic optical damage in high-power AlGaInP broad-area lasers

    Science.gov (United States)

    Bou Sanayeh, Marwan

    2017-05-01

    The increasing importance of extracting high optical power out of semiconductor lasers motivated several studies in catastrophic optical damage (COD) level improvement. In this study, the influence of the resonator length in high-power broad-area (BA) AlGaInP lasers on COD is presented. For the analyses, several 638 nm AlGaInP 60 μm BA lasers from the same wafer were used. Resonator lengths of 900, 1200, 1500, and 1800 μm were compared. In order to independently examine the effect of the resonator length on the maximum power reached by the lasers before COD (PCOD), the lasers used are uncoated and unmounted, and PCOD under pulsed mode was determined. It was found that higher output powers and eventually higher PCOD can be achieved using longer resonators; however, it was also found that this is mainly useful when working at high output powers far away from the laser threshold, since the threshold current and slope efficiency worsen when the resonator length increases.

  15. Influence of the He-Ne laser in different irradiation regimes on the cornea cells after ionizing irradiation

    International Nuclear Information System (INIS)

    Bulyakova, N.V.

    1984-01-01

    A study was made on epithelium cells of the eye cornea in mices entering the first postradiation mitosis. The influence of laser rays acting in the course of each exposure during one and the same period of time, or continuously, or by pulses was compared. The effect of laser radiation was evaluated from the frequency of occurrence of cells with chromosomal aberrations, mitotic index, coefficient of mitosis phases. It has been established that pulse radiation of a helium-neon laser in a certain operation regime produces a sanitating effect on cells of eye cornea epithelium in white mice damaged by ionizing radiation. Cells being killed in the interphase were not revealed in epithelium of the eye cornea. It enables to conclude that the amount of aberrant mitoses decreases as a result of postradiation repair of cells damaged by ionizing radiation, but not as a result of their elimination

  16. Clocking Femtosecond Collisional Dynamics via Resonant X-Ray Spectroscopy

    Science.gov (United States)

    van den Berg, Q. Y.; Fernandez-Tello, E. V.; Burian, T.; Chalupský, J.; Chung, H.-K.; Ciricosta, O.; Dakovski, G. L.; Hájková, V.; Hollebon, P.; Juha, L.; Krzywinski, J.; Lee, R. W.; Minitti, M. P.; Preston, T. R.; de la Varga, A. G.; Vozda, V.; Zastrau, U.; Wark, J. S.; Velarde, P.; Vinko, S. M.

    2018-02-01

    Electron-ion collisional dynamics is of fundamental importance in determining plasma transport properties, nonequilibrium plasma evolution, and electron damage in diffraction imaging applications using bright x-ray free-electron lasers (FELs). Here we describe the first experimental measurements of ultrafast electron impact collisional ionization dynamics using resonant core-hole spectroscopy in a solid-density magnesium plasma, created and diagnosed with the Linac Coherent Light Source x-ray FEL. By resonantly pumping the 1 s →2 p transition in highly charged ions within an optically thin plasma, we have measured how off-resonance charge states are populated via collisional processes on femtosecond time scales. We present a collisional cross section model that matches our results and demonstrates how the cross sections are enhanced by dense-plasma effects including continuum lowering. Nonlocal thermodynamic equilibrium collisional radiative simulations show excellent agreement with the experimental results and provide new insight on collisional ionization and three-body-recombination processes in the dense-plasma regime.

  17. Ro-vibrational laser spectroscopy of ESD neutrals from chemisorbed species

    International Nuclear Information System (INIS)

    Burns, A.R.; Stechel, E.B.; Jennison, D.R.

    1987-01-01

    Ever since the introduction of intense tunable laser radiation, the fields of molecular spectroscopy and dynamics have expanded tremendously. Indeed, with each technical improvement in laser resolution and output power, new applications have emerged with correspondingly increased levels of sophistication and information. In the field of electron-stimulated desorption (ESD), not only has the utilization of lasers resulted in the detection of neutral species, which were previously difficult to observe without specially-designed analyzers, but also the quantum-specific nature of the resonant laser interaction with the neutrals has yielded valuable information concerning internal energies. In this article, we will discuss some of the experimental methods in the application of laser resonance-ionization spectroscopy (RIS) to the study of the ESD of neutrals, in particular, chemisorbed NO and CO desorption from Pt(111). We will also show how the detailed information obtained in these experiments has identified a new desorption mechanism

  18. Resonant laser mass spectrometry for environmental and industrial chemical trace analysis

    International Nuclear Information System (INIS)

    Boesl, Ulrich; Rink, Joerg; Distelrath, Volker; Pueffel, Peter

    2001-01-01

    A promising new method for pollutant trace analysis is resonant laser mass spectrometry. It combines selectivity, sensitivity, and speed of measurement. In this paper, two examples of application are presented: exhaust analysis of combustion engines and analysis of polycylcic aromatic compounds in soil samples. The sensitivity of small, mobile instruments is discussed as well as alternative laser-based techniques in the case formation of cations by nanosecond lasers is improbable

  19. Time-resolved resonance fluorescence spectroscopy for study of chemical reactions in laser-induced plasmas.

    Science.gov (United States)

    Liu, Lei; Deng, Leimin; Fan, Lisha; Huang, Xi; Lu, Yao; Shen, Xiaokang; Jiang, Lan; Silvain, Jean-François; Lu, Yongfeng

    2017-10-30

    Identification of chemical intermediates and study of chemical reaction pathways and mechanisms in laser-induced plasmas are important for laser-ablated applications. Laser-induced breakdown spectroscopy (LIBS), as a promising spectroscopic technique, is efficient for elemental analyses but can only provide limited information about chemical products in laser-induced plasmas. In this work, time-resolved resonance fluorescence spectroscopy was studied as a promising tool for the study of chemical reactions in laser-induced plasmas. Resonance fluorescence excitation of diatomic aluminum monoxide (AlO) and triatomic dialuminum monoxide (Al 2 O) was used to identify these chemical intermediates. Time-resolved fluorescence spectra of AlO and Al 2 O were used to observe the temporal evolution in laser-induced Al plasmas and to study their formation in the Al-O 2 chemistry in air.

  20. Polarization effects in above-threshold ionization with a mid-infrared strong laser field

    Science.gov (United States)

    Kang, Hui-Peng; Xu, Song-Po; Wang, Yan-Lan; Yu, Shao-Gang; Zhao, Xiao-Yun; Hao, Xiao-Lei; Lai, Xuan-Yang; Pfeifer, Thomas; Liu, Xiao-Jun; Chen, Jing; Cheng, Ya; Xu, Zhi-Zhan

    2018-05-01

    Using a semiclassical approach, we theoretically study the above-threshold ionization of magnesium by intense, mid-infrared laser pulses. The formation of low-energy structures in the photoelectron spectrum is found to be enhanced by comparing with a calculation based on the single-active electron approximation. By performing electron trajectory and recollision-time distribution analysis, we demonstrate that this phenomenon is due to the laser-induced ionic core polarization effects on the recolliding electrons. We also show that the polarization effects should be experimentally detectable. Our finding provides new insight into ultrafast control of strong-field photoionization and imaging of polar molecules.

  1. Charge exchange induced X-ray transitions of hollow ions in laser field ionized plasmas

    International Nuclear Information System (INIS)

    Rosmej, F.B.; Hoffmann, D.H.H.; Faenov, A. Ya.; Pikuz, T.A.; Magunov, A.I.; Skobelev, I.Yu.; Auguste, T.; D'Oliveira, P.; Hulin, S.; Monot, P.

    2000-01-01

    Double electron charge exchange is proposed for the formation of hollow He-like ions when laser field ionized nuclei penetrate into the residual gas. Using transitions from different configurations in hollow ions a method for the determination of the electron temperature in the long lasting recombination phase is developed

  2. Shock velocity in weakly ionized nitrogen, air, and argon

    International Nuclear Information System (INIS)

    Siefert, Nicholas S.

    2007-01-01

    The goal of this research was to determine the principal mechanism(s) for the shock velocity increase in weakly ionized gases. This paper reports experimental data on the propagation of spark-generated shock waves (1< Mach<3) into weakly ionized nitrogen, air, and argon glow discharges (1 < p<20 Torr). In order to distinguish between effects due solely to the presence of electrons and effects due to heating of the background gas via elastic collisions with electrons, the weakly ionized discharge was pulsed on/off. Laser deflection methods determined the shock velocity, and the electron number density was collected using a microwave hairpin resonator. In the afterglow of nitrogen, air, and argon discharges, the shock velocity first decreased, not at the characteristic time for electrons to diffuse to the walls, but rather at the characteristic time for the centerline gas temperature to equilibrate with the wall temperature. These data support the conclusion that the principal mechanism for the increase in shock velocity in weakly ionized gases is thermal heating of the neutral gas species via elastic collisions with electrons

  3. Quantitation of peptides and proteins by matrix-assisted laser desorption/ionization mass spectrometry using (18)O-labeled internal standards

    DEFF Research Database (Denmark)

    Mirgorodskaya, O A; Kozmin, Y P; Titov, M I

    2000-01-01

    A method for quantitating proteins and peptides in the low picomole and sub-picomole range has been developed using matrix-assisted laser desorption/ionization mass spectrometry (MALDI-MS) with internal (18)O-labeled standards. A simple procedure is proposed to produce such internal standards for...... inhibitor, were quantified by MALDI-time-of-flight (TOF) mass spectrometry.......A method for quantitating proteins and peptides in the low picomole and sub-picomole range has been developed using matrix-assisted laser desorption/ionization mass spectrometry (MALDI-MS) with internal (18)O-labeled standards. A simple procedure is proposed to produce such internal standards...

  4. Resonant ablation of single-wall carbon nanotubes by femtosecond laser pulses

    International Nuclear Information System (INIS)

    Arutyunyan, N R; Komlenok, M S; Kononenko, V V; Pashinin, V P; Pozharov, A S; Konov, V I; Obraztsova, E D

    2015-01-01

    The thin 50 nm film of bundled arc-discharge single-wall carbon nanotubes was irradiated by femtosecond laser pulses with wavelengths 675, 1350 and 1745 nm corresponding to the absorption band of metallic nanotubes E 11 M , to the background absorption and to the absorption band of semiconducting nanotubes E 11 S , respectively. The aim was to induce a selective removal of nanotubes of specific type from the bundled material. Similar to conducted thermal heating experiments, the effect of laser irradiation results in suppression of all radial breathing modes in the Raman spectra, with preferential destruction of the metallic nanotubes with diameters less than 1.26 nm and of the semiconducting nanotubes with diameters 1.36 nm. However, the etching rate of different nanotubes depends on the wavelength of the laser irradiation. It is demonstrated that the relative content of nanotubes of different chiralities can be tuned by a resonant laser ablation of undesired nanotube fraction. The preferential etching of the resonant nanotubes has been shown for laser wavelengths 675 nm (E 11 M ) and 1745 nm (E 11 S ). (paper)

  5. Babinet principle and diffraction losses in laser resonators

    International Nuclear Information System (INIS)

    Kubarev, V V

    2000-01-01

    A simple analytical technique, based on the Babinet principle, for calculating low diffraction losses of different kinds in stable resonators is described. The technique was verified by comparison with the known numerical and analytical calculations of the losses in specific diffraction problems. (laser applications and other topics in quantum electronics)

  6. Analysis of laser-generated plasma ionizing radiation by synthetic single crystal diamond detectors

    Czech Academy of Sciences Publication Activity Database

    Marinelli, M.; Milani, E.; Prestopino, G.; Verona, C.; Verona-Rinati, G.; Cutroneo, M.; Torrisi, L.; Margarone, Daniele; Velyhan, Andriy; Krása, Josef; Krouský, Eduard

    2013-01-01

    Roč. 272, May (2013), s. 104-108 ISSN 0169-4332 R&D Projects: GA MŠk ED1.1.00/02.0061; GA MŠk EE2.3.20.0279; GA MŠk EE.2.3.20.0087; GA MŠk(CZ) 7E09092; GA MŠk(CZ) LC528 Grant - others:ELI Beamlines(XE) CZ.1.05/1.1.00/02.0061; OPVK 3 Laser Zdroj(XE) CZ.1.07/2.3.00/20.0279; OP VK 2 LaserGen(XE) CZ.1.07/2.3.00/20.0087; 7FP LASERLAB-EUROPE(XE) 228334 Program:EE; FP7 Institutional support: RVO:68378271 Keywords : single crystal diamond * diamond detector * laser-generated plasma * ionizing radiation * time-of-fight spectrometer Subject RIV: BL - Plasma and Gas Discharge Physics Impact factor: 2.538, year: 2013

  7. Resonance enhanced multiphoton ionization spectra of molecules and molecular fragments. Annual progress report, March 1992 - February 1993

    International Nuclear Information System (INIS)

    1993-01-01

    In this report, the author will review the progress made in his studies of ion rotational distributions resulting from resonance enhanced multiphoton ionization of excited electronic states and from single-photon ionization of ground electronic states of jet-cooled molecules by coherent VUV and XUV radiation. To do so he will select a few examples from his studies which serve to highlight his progress and to identify the background and significance of the specific spectral features and systems he has chosen to study

  8. The Collinear Resonance Ionization Spectroscopy (CRIS) experimental setup at CERN-ISOLDE

    CERN Document Server

    Cocolios, T E; Procter, T J; Rothe, S; Garcia Ruiz, R F; Stroke, H H; Rossel, R E; Heylen, H; Franchoo, S; Marsh, B A; Verney, D; Papuga, J; Strashnov, I; Billowes, J; de Groote, R P; Le Blanc, F; Simpson, G S; Fedosseev, V N; Lynch, K M; Wood, R T; Budincevic, I; Mason, P J R; Wendt, K D A; Flanagan, K T; De Schepper, S; Rajabali, M M; Al Suradi, H H; Walker, P M; Smith, A J

    2013-01-01

    The CRIS setup at CERN-ISOLDE is a laser spectroscopy experiment dedicated to the high-resolution study of the spin, hyperfine structure and isotope shift of radioactive nuclei with low production rates (a few per second). It combines the Doppler-free resolution of the in-flight collinear geometry with the high detection efficiency of resonant ionisation. A recent commissioning campaign has demonstrated a 1\\% experimental efficiency, and as low as a 0.001\\% non-resonant ionisation. The current status of the experiment and its recent achievements with beams of francium isotopes are reported. The first identified systematic effects are discussed. (C) 2013 The Authors. Published by Elsevier B.V. All rights reserved.

  9. Determination of Pesticides by Gas Chromatography Combined with Mass Spectrometry Using Femtosecond Lasers Emitting at 267, 400, and 800 nm as the Ionization Source.

    Science.gov (United States)

    Yang, Xixiang; Imasaka, Tomoko; Imasaka, Totaro

    2018-04-03

    A standard sample mixture containing 51 pesticides was separated by gas chromatography (GC), and the constituents were identified by mass spectrometry (MS) using femtosecond lasers emitting at 267, 400, and 800 nm as the ionization source. A two-dimensional display of the GC/MS was successfully used for the determination of these compounds. A molecular ion was observed for 38 of the compounds at 267 nm and for 30 of the compounds at 800 nm, in contrast to 27 among 50 compounds when electron ionization was used. These results suggest that the ultraviolet laser is superior to the near-infrared laser for molecular weight determinations and for a more reliable analysis of these compounds. In order to study the conditions for optimal ionization, the experimental data were examined using the spectral properties (i.e., the excitation and ionization energies and absorption spectra for the neutral and ionized species) obtained by quantum chemical calculations. A few molecules remained unexplained by the currently reported rules, requiring additional rules for developing a full understanding of the femtosecond ionization process. The pesticides in the homogenized matrix obtained from kabosu ( citrus sphaerocarpa) were measured using lasers emitting at 267 and 800 nm. The pesticides were clearly separated and measured on the two-dimensional display, especially for the data measured at 267 nm, suggesting that this technique would have potential for use in the practical trace analysis of the pesticides in the environment.

  10. uv laser induced molecular multiphoton ionization and fragmentation. [Intensity dependence, ion properties and yield

    Energy Technology Data Exchange (ETDEWEB)

    Rockwood, S; Reilly, J P; Hohla, K; Kompa, K L

    1979-02-01

    It has been demonstrated that the output from a discharge pumped KrF laser (249 nm) is capable of ionizing a variety of molecules. The nature and yield of ions generated in this process, which were identified by time-of-flight mass spectrometry, exhibit a striking intensity dependence. 12 references, 3 figures.

  11. Three-Rod Resonator for Krypton Lamp Pumped 1.8 kW Continuous-Wave Nd:YAG Laser

    Institute of Scientific and Technical Information of China (English)

    LI Qiang; FANG Ming-Xing; WANG Zhi-Yong; YU Zhen-Sheng; LEI Hong; GUO Jiang; LI Gang; ZUO Tie-Chuan

    2004-01-01

    @@ A three-rod series resonator cw Nd:YAG laser suitable for the industrial applications is presented. The symmetrical resonator laser has been developed and is rated at 1820-W output power with beam parameter product 24 mm.mrad. By utilizing the symmetrical resonator design, the characteristic of beam with multi-rod is not obviously decreased compared with that of a single one. The system total electro-optics efficiency of lamp pumped YAG crystal is as high as 4.0%. The main factors, which affect output power and beam quality of high power solid-state laser module, are theoretically analysed.

  12. Is energy pooling necessary in ultraviolet matrix-assisted laser desorption/ionization?

    Science.gov (United States)

    Lin, Hou-Yu; Song, Botao; Lu, I-Chung; Hsu, Kuo-Tung; Liao, Chih-Yu; Lee, Yin-Yu; Tseng, Chien-Ming; Lee, Yuan-Tseh; Ni, Chi-Kung

    2014-01-15

    Energy pooling has been suggested as the key process for generating the primary ions during ultraviolet matrix-assisted laser desorption/ionization (UV-MALDI). In previous studies, decreases in fluorescence quantum yields as laser fluence increased for 2-aminobenzoic acid, 2,5-dihydroxybenzoic acid (2,5-DHB), and 3-hydroxypicolinic acid were used as evidence of energy pooling. This work extends the research to other matrices and addresses whether energy pooling is a universal property in UV-MALDI. Energy pooling was investigated in a time-resolved fluorescence experiment by using a short laser pulse (355 nm, 20 ps pulse width) for excitation and a streak camera (1 ps time resolution) for fluorescence detection. The excited-state lifetime of 2,5-DHB decreased with increases in laser fluence. This suggests that a reaction occurs between two excited molecules, and that energy pooling may be one of the possible reactions. However, the excited-state lifetime of 2,4,6-trihydroxyacetophenone (THAP) did not change with increases in laser fluence. The upper limit of the energy pooling rate constant for THAP is estimated to be approximately 100-500 times smaller than that of 2,5-DHB. The small energy pooling rate constant for THAP indicates that the potential contribution of the energy pooling mechanism to the generation of THAP matrix primary ions should be reconsidered. Copyright © 2013 John Wiley & Sons, Ltd.

  13. Excitation and ionization of hydrogen and helium atoms by femtosecond laser pulses: theoretical approach by Coulomb-Volkov states

    International Nuclear Information System (INIS)

    Guichard, R.

    2007-12-01

    We present a theoretical approach using Coulomb-Volkov states that appears useful for the study of atomic multi-photonic processes induced by intense XUV femtosecond laser pulses. It predicts hydrogen ionization spectra when it is irradiated by laser pulses in perturbations conditions. Three ways have been investigated. Extension to strong fields when ℎω > I p : it requires to include the hydrogen ground state population, introducing it in standard Coulomb-Volkov amplitude leads to saturated multi-photonic ionization. Extension to multi-photonic transitions with ℎω p : new quantum paths are open by the possibility to excite the lower hydrogen bound states. Multiphoton excitation of these states is investigated using a Coulomb-Volkov approach. Extension to helium: two-photon double ionization study shows the influence of electronic correlations in both ground and final state. Huge quantity of information such as angular and energetic distributions as well as total cross sections is available. (author)

  14. Progress in 41Ca ultratrace determination by diode-laser-based RIMS

    International Nuclear Information System (INIS)

    Mueller, P.; Blaum, K.; Diel, S.; Geppert, Ch.; Wendt, K.; Bushaw, B.A.; Trautmann, N.

    2001-01-01

    We report on progress in development and application of 41 Ca ultratrace determination by diode-laser-based RIMS. Applications include biomedical isotope-tracer studies of human calcium kinetics, cosmochemical investigations of meteorites, environmental dosimetry and radiodating. Depending on the application, 41 Ca needs to be determined at isotopic abundance in the range of 10 -9 to 10 -15 relative to the major stable isotope 40 Ca. We use either a double- or triple-resonance excitation scheme and subsequent non-resonant photoionization of calcium atoms in a collimated atomic beam. All resonant steps are excited with narrow bandwidth extended cavity diode lasers, non-resonant photo-ionization is attained with either an argon ion laser or a CO 2 laser. The resulting photo-ions are detected with a quadrupole mass spectrometer. With double-resonance excitation, the optical isotopic selectivity for 41 Ca against 40 Ca is 2x10 4 , while the triple-resonance scheme provides optical selectivity of more than 10 9 . By adding the third resonant step, overall detection efficiency increases from 1x10 -6 to 5x10 -5 and the detection limit for relative 41 Ca abundance improves from 5x10 -10 to 2x10 -13 . Both schemes have been applied to various sample types and accuracy and reproducibility of the resulting 41 Ca/ 40 Ca isotope ratios have been determined to be better than 5%

  15. New possibilities for using laser polarimetry technology to study electron paramagnetic resonance

    Energy Technology Data Exchange (ETDEWEB)

    Aleksandrov, E V; Zapasskii, V S

    1982-01-01

    Optical methods of recording electron paramagnetic resonance which arose in the early 50's as applied to the problem of recording the magnetic resonance of excited atoms is at the present time widely used in studying the electron paramagnetic resonance of the ground and excited states of free atoms and paramagnetic centers in condensed media. At the present time attention is devoted to the additional possibilities of optical methods of electron paramagnetic resonance which are realized using laser sources.

  16. Dating the Martian meteorite Zagami by the ⁸⁷Rb-⁸⁷Sr isochron method with a prototype in situ resonance ionization mass spectrometer.

    Science.gov (United States)

    Anderson, F Scott; Levine, Jonathan; Whitaker, Tom J

    2015-01-30

    The geologic history of the Solar System builds on an extensive record of impact flux models, crater counts, and ~270 kg of lunar samples analyzed in terrestrial laboratories. However, estimates of impactor flux may be biased by the fact that most of the dated Apollo samples were only tenuously connected to an assumed geologic context. Moreover, uncertainties in the modeled cratering rates are significant enough to lead to estimated errors for dates on Mars and the Moon of ~1 Ga. Given the great cost of sample return missions, combined with the need to sample multiple terrains on multiple planets, we have developed a prototype instrument that can be used for in situ dating to better constrain the age of planetary samples. We demonstrate the first use of laser ablation resonance ionization mass spectrometry for (87)Rb-(87)Sr isochron dating of geological specimens. The demands of accuracy and precision have required us to meet challenges including regulation of the ambient temperature, measurement of appropriate backgrounds, sufficient ablation laser intensity, avoidance of the defocusing effect of the plasma created by ablation pulses, and shielding of our detector from atoms and ions of other elements. To test whether we could meaningfully date planetary materials, we have analyzed a piece of the Martian meteorite Zagami. In each of four separate measurements we obtained (87)Rb-(87)Sr isochron ages for Zagami consistent with its published age, and, in both of two measurements that reached completion, we obtained better than 200 Ma precision. Combining all our data into a single isochron with 581 spot analyses gives an (87)Rb-(87)Sr age for this specimen of 360 ±90 Ma. Our analyses of the Zagami meteorite represent the first successful application of resonance ionization mass spectrometry to isochron geochronology. Furthermore, the technique is miniaturizable for spaceflight and in situ dating on other planetary bodies. © 2014 The Authors. Rapid Communications in

  17. Gas laser spectrometer for nuclear investigation at nucleonic stability limit. (project)

    International Nuclear Information System (INIS)

    Myshinskij, G.V.

    1989-01-01

    It is proposed to obtain the atomic beam of the proton-rich and neutron-rich nuclides with half-lives of up to 1 ms, by using the gas-jet technique. Subsequently their properties are investigated using the methods of laser resonance ionization and nuclear spectroscopy. 8 refs.; 4 figs

  18. A pulsated weak-resonant-cavity laser diode with transient wavelength scanning and tracking for injection-locked RZ transmission.

    Science.gov (United States)

    Lin, Gong-Ru; Chi, Yu-Chieh; Liao, Yu-Sheng; Kuo, Hao-Chung; Liao, Zhi-Wang; Wang, Hai-Lin; Lin, Gong-Cheng

    2012-06-18

    By spectrally slicing a single longitudinal-mode from a master weak-resonant-cavity Fabry-Perot laser diode with transient wavelength scanning and tracking functions, the broadened self-injection-locking of a slave weak-resonant-cavity Fabry-Perot laser diode is demonstrated to achieve bi-directional transmission in a 200-GHz array-waveguide-grating channelized dense-wavelength-division-multiplexing passive optical network system. Both the down- and up-stream slave weak-resonant-cavity Fabry-Perot laser diodes are non-return-to-zero modulated below threshold and coherently injection-locked to deliver the pulsed carrier for 25-km bi-directional 2.5 Gbits/s return-to-zero transmission. The master weak-resonant-cavity Fabry-Perot laser diode is gain-switched at near threshold condition and delivers an optical coherent pulse-train with its mode linewidth broadened from 0.2 to 0.8 nm by transient wavelength scanning, which facilitates the broadband injection-locking of the slave weak-resonant-cavity Fabry-Perot laser diodes with a threshold current reducing by 10 mA. Such a transient wavelength scanning induced spectral broadening greatly releases the limitation on wavelength injection-locking range required for the slave weak-resonant-cavity Fabry-Perot laser diode. The theoretical modeling and numerical simulation on the wavelength scanning and tracking effects of the master and slave weak-resonant-cavity Fabry-Perot laser diodes are performed. The receiving power sensitivity for back-to-back transmission at bit-error-rate transmission is less than 2 dB for all 16 channels.

  19. A possibility of local measurements of ion temperature in a high-temperature plasma by laser induced ionization

    International Nuclear Information System (INIS)

    Kantor, M

    2012-01-01

    A new diagnostic for local measurements of ion temperature and drift velocity in fusion plasmas is proposed in the paper. The diagnostic is based on laser induced ionization of excited hydrogen and deuterium atoms from the levels which ionization energy less than the laser photon energy. A high intensive laser beam ionizes nearly all the excited atoms in the beam region resulting in a quench of spontaneous line emission of the appropriate optical transitions. The measurements of the quenching emission have been used in the past for local measurements of hydrogen atom density in tokamak plasma. The idea of the new diagnostic is spectral resolution of the quenching emission. The measured spectrum relates directly to the velocity distribution of the excited atoms. This distribution is strongly coupled to the distribution of the hydrogen atoms at the ground state. So, the spectral resolution of quenching emission is a way of local measurements of the temperature and drift velocity of hydrogen atoms in plasma. The temperature of hydrogen atoms is well coupled to the local ion temperature as long as the mean free path of the atoms is shorter than the ion gradient length in plasma. In this case the new diagnostic can provide local measurements of ion temperature in plasma. The paper considers technical capabilities of the diagnostic, physical restrictions of its application and interpretation of the measurements.

  20. Effects of molecular orientation in the laser ionization of molecules

    International Nuclear Information System (INIS)

    Xinhua Xie; Gerald Jordan; Christopher Ede; Armin Scrinzi

    2006-01-01

    Complete test of publication follows. Time-dependent electron momentum distributions are calculated during ionization of linear molecules by a strong laser pulse and upon recollision. For typical experimental laser parameters, we find a strong influence of molecular orientation and initial state symmetry on the total ionization rates and also on momentum distributions, compared to which the effect of electron correlation is less important for simple molecules. The dynamics of electron release and subsequent recollision with the parent ion largely determines the time-frequency structure of harmonic radiation, which underlies the generation of attosecond XUV pulses and the time-resolved imaging techniques for the electronic structure of molecules. In the present work, the effects of orientation and initial orbital symmetry are investigated by solving the time-dependent Schroedinger equation for a two-dimensional diatomic molecule in the single-active electron approximation. As in the presence of strong external fields recolliding electrons cannot be easily separated from bound electrons, the electron wave packet is probed at some distance from where all electrons can be safety considered as detached. We find that momentum distributions strongly depend on molecular size, orientation of the molecular axis, and node structure of the initial state. In order to determine the momentum spectra at the time of electron release and upon recollision, we classically propagate the Wigner distributions of probed wavepackets backward and forward in time, respectively. We find that the times of peak recollision current can vary strongly with the orientation of the molecule. Moreover, correlation effects on the electron spectra are included using the multi-configuration time-dependent Hartree-Fock method. The calculations are performed in three spatial dimensions with the restriction to cylindrical symmetry, where the molecule is aligned with the laser field. Correlation is studied

  1. Recent developments in and applications of resonance ionization mass spectrometry

    International Nuclear Information System (INIS)

    Wendt, K.; Blaum, K.; Horn, R.; Huber, G.; Kunz, P.; Mueller, P.; Noertershaeuser, W.; Nunnemann, M.; Passler, G.; Schmitt, A.; Gruening, C.; Kratz, J.V.; Trautmann, N.; Waldek, A.

    1999-01-01

    Resonance Ionization Mass Spectrometry (RIMS) has nowadays reached the status of a routine method for sensitive and selective ultratrace determination of long-lived radioactive isotopes in environmental, biomedical and technical samples. It provides high isobaric suppression, high to ultra-high isotopic selectivity and good overall efficiency. Experimental detection limits are as low as 10 6 atoms per sample and permit the fast and sensitive determination of ultratrace amounts of radiotoxic contaminations. Experimental arrangements for the detection of different radiotoxic isotopes, e.g. 236-244 Pu, 89,90 Sr and 99 Tc in environmental samples are described, and the application of RIMS to the ultrarare long-lived radioisotope 41 Ca for cosmochemical, radiodating and medical purposes are presented. (orig.)

  2. Investigation of thin ZnO layers in view of laser desorption-ionization

    Energy Technology Data Exchange (ETDEWEB)

    Grechnikov, A A; Borodkov, A S [Vernadsky Institute of Geochemistry and Analytical Chemistry, Russian Academy of Sciences, 19 Kosygin Str., 119991 Moscow (Russian Federation); Georgieva, V B [Georgi Nadjakov Institute of Solid State Physics, Bulgarian Academy of Sciences, 72 Tzarigradsko Chaussee, 1784 Sofia (Bulgaria); Alimpiev, S S; Nikiforov, S M; Simanovsky, Ya O [General Physics Institute, Russian Academy of Sciences, 38 Vavilov Str., 119991 Moscow (Russian Federation); Dimova-Malinovska, D; Angelov, O I, E-mail: lazarova@issp.bas.b [Laboratory for Solar Energy and New Energy Sources, Bulgarian Academy of Sciences, 72 Tzarigradsko Chaussee, 1784 Sofia (Bulgaria)

    2010-04-01

    Thin zinc oxide films (ZnO) were developed as a matrix-free platform for surface assisted laser desorption-ionization (SALDI) time-of-flight mass spectrometry. The ZnO films were deposited by RF magnetron sputtering of ZnO ceramic targets in Ar atmospheres on monocrystalline silicon. The generation under UV (355 nm) laser irradiation of positive ions of atenolol, reserpine and gramicidin S from the ZnO layers deposited was studied. All analytes tested were detected as protonated molecules with no or very structure-specific fragmentation. The mass spectra obtained showed low levels of chemical background noise. All ZnO films studied exhibited high stability and good reproducibility. The detection limits for test analytes are in the 10 femtomol range.

  3. Comparison study for multiple ionization of carbonyl sulfide by linearly and circularly polarized intense femtosecond laser fields using Coulomb explosion imaging

    Science.gov (United States)

    Ma, Pan; Wang, Chuncheng; Luo, Sizuo; Yu, Xitao; Li, Xiaokai; Wang, Zhenzhen; Hu, Wenhui; Yu, Jiaqi; Yang, Yizhang; Tian, Xu; Cui, Zhonghua; Ding, Dajun

    2018-05-01

    We studied the relative yields and dissociation dynamics for two- and three-body Coulomb explosion (CE) channels from highly charged carbonyl sulfide molecules in intense laser fields using the CE imaging technique. The electron recollision contributions are evaluated by comparing the relative yields for the multiple ionization process in linearly polarized and circularly polarized (LP and CP) laser fields. The nonsequential multiple ionization is only confirmed for the charge states of 2 to 4 because the energy for further ionization from the inner orbital is much larger than the maximum recollision energy, 3.2U p . The novel deviations of kinetic energy releases distributions between LP and CP pulses are observed for the charge states higher than 4. It can be attributed to the stronger molecular bending in highly charged states before three-body CE with CP light, in which the bending wave packet is initialed by the triple or quartic ionization and spread along their potential curves. Compared to LP light, CP light ionizes a larger fraction of bending molecules in the polarization plane.

  4. Nonlinear ionization of many-electron systems over a broad photon-energy range

    International Nuclear Information System (INIS)

    Karamatskou, Antonia

    2015-11-01

    Rapid developments in laser technology and, in particular, the advances in the realm of free-electron lasers have initiated tremendous progress in both theoretical and experimental atomic, molecular and optical physics. Owing to high intensities in combination with short pulse durations we can enter the utterly nonlinear regime of light-matter interaction and study the dynamics and features of matter under extreme conditions. The capabilities of X-ray free-electron laser sources have promoted the importance of nonlinear optics also in the X-ray regime. I show in my thesis how we can exploit the nonlinear response regime to reveal hidden information about resonance structures that are not resolved in the weak-field regime. This prospect points to many applications for future investigations of various complex systems with free-electron lasers. In the present thesis the interaction of atomic closed-shell systems with ultrashort and strong laser pulses is investigated. Over a broad photon-energy range the characteristics of the atomic shell are studied with a particular focus on the nonlinear response regime and on electron correlation effects. Several computational extensions of the XCID package for multi-electron dynamics are presented and their applications in various studies are demonstrated; a completely new capability of the numerical method is realized by implementing the calculation of photoelectron spectra and by calculating eigenstates of the many-electron Hamiltonian. The field of study within the present work encompasses (1) the strong-field regime, where the question of the adiabatic character in tunneling ionization is discussed and analyzed, especially for the case of few-cycle pulses; (2) the XUV regime, in which we show for the first time that the collectivity in resonant excitation reveals new information; and (3) the (hard) x-ray regime, which is highly relevant for x-ray free-electron laser experiments, and where we show how important two

  5. Multiphoton Ionization Detection in Collinear Laser Spectroscopy of Isolde Beams

    CERN Multimedia

    2002-01-01

    The experiments using the multiphoton ionization technique have been continued in the beginning of 1990 with stable beam tests on the modified apparatus and with another radioactive beam time on Yb. Higher laser power and an increased vacuum in the ionization region (see figure) yielded a further gain in sensitivity, mainly due to the better suppression of the background ions produced in rest gas collisions. For even Yb isotopes we have now reached a detection efficiency of $\\epsilon$~=~1~x~10$^{-5}$ ions per incoming atom at a background count rate of 30~ions from a beam of 5~x~10$^9$. This sensitivity was high enough for spectroscopy on $^{157}$Yb, where the typical ISOLDE yield of 5~x~10$^7$Yb ions is covered by an isobaric contamination of more than 10$^{10}$ ions. Measurements have also been performed on $^{175}$Yb. These give the first precise value for the magnetic moment of this isotope, $\\mu$~=~0.766(8)$ mu _{N} $, which agrees rather well with the magnetic moment of the isotone $^{177}$Hf. The isoto...

  6. Production of highly charged ions of argon by optical field ionization in a relativistic laser field

    International Nuclear Information System (INIS)

    Sagisaka, Akito; Akahane, Yutaka; Aoyama, Makoto; Nakano, Fumihiko; Yamakawa, Koichi

    2001-01-01

    We observed the highly charged ions of argon by optical field ionization in a relativistic intensity regime. Charge states up to Ar 15+ were produced at the highest intensity of 800 nm, linearly polarized 20 fs Ti: sapphire laser pulses. The peak intensity of the pulse is determined by comparing the measured ion production curve for Ar 9+ with ADK theory. The results of these measurements of the ionization indicate that the maximum peak intensity is achieved to ∼2x10 19 W/cm 2 . (author)

  7. A three-dimensional model for calculating the micro disk laser resonant-modes

    International Nuclear Information System (INIS)

    Sabetjoo, H.; Bahrampor, A.; Farrahi-Moghaddam, R.

    2006-01-01

    In this article, a semi-analytical model for theoretical analysis of micro disk lasers is presented. Using this model, the necessary conditions for the existence of loss less and low-loss modes of micro-resonators are obtained. The resonance frequency of the resonant modes and also the attenuation of low-loss modes are calculated. By comparing the results with results of finite difference method, their validity is certified.

  8. An improved prism for use in laser resonators

    Science.gov (United States)

    Richards, J.

    1981-08-01

    The use of compound total internal reflection prisms rather than Porro prisms in polarisation coupled lasers is proposed. Performance advantages resulting from the use of these prisms include higher output without the need to bias the Pockels cell, ability to give a larger range of output coupling and independence of performance on the refractive index of the prism. In conventional Q-switched lasers the use of the prism at the Pockels cell end of the resonator instead of the usual 100% reflecting mirror also leads to some advantages including better hold-off, elimination of the need to bias the Pockels cell and insensitivity in one plane to angular misalignment.

  9. Development of Laser-Polarized Noble Gas Magnetic Resonance Imaging (MRI) Technology

    Science.gov (United States)

    Walsworth, Ronald L.

    2004-01-01

    We are developing technology for laser-polarized noble gas nuclear magnetic resonance (NMR), with the aim of enabling it as a novel biomedical imaging tool for ground-based and eventually space-based application. This emerging multidisciplinary technology enables high-resolution gas-space magnetic resonance imaging (MRI)-e.g., of lung ventilation, perfusion, and gas-exchange. In addition, laser-polarized noble gases (3He and 1BXe) do not require a large magnetic field for sensitive NMR detection, opening the door to practical MRI with novel, open-access magnet designs at very low magnetic fields (and hence in confined spaces). We are pursuing two specific aims in this technology development program. The first aim is to develop an open-access, low-field (less than 0.01 T) instrument for MRI studies of human gas inhalation as a function of subject orientation, and the second aim is to develop functional imaging of the lung using laser-polarized He-3 and Xe-129.

  10. Modeling of mode-locked coupled-resonator optical waveguide lasers

    DEFF Research Database (Denmark)

    Agger, Christian; Skovgård, Troels Suhr; Gregersen, Niels

    2010-01-01

    Coupled-resonator optical waveguides made from coupled high-Q photonic crystal nanocavities are investigated for use as cavities in mode-locked lasers. Such devices show great potential in slowing down light and can serve to reduce the cavity length of a mode-locked laser. An explicit expression...... of the emerging pulse train. A range of tuning around this frequency allows for effective mode locking. Finally, noise is added to the generalized single-cavity eigenfrequencies in order to evaluate the effects of fabrication imperfections on the cold-cavity transmission properties and consequently on the locking...

  11. Collective acceleration of ions on the basis of resonance surface photoionization

    International Nuclear Information System (INIS)

    Antsiferov, V.V.; Smirnov, G.I.; Telegin, G.G.

    1994-01-01

    The effects of ion beam shaping and collective acceleration on the basis of resonance surface ionization are discussed. The principle diagram of the device for collective acceleration of positive ions is given. The method suggested for positive ion acceleration provides the efficiency increase, the design simplification, the size decrease and the increase in the frequency of the collective laser ion accelerator pulses

  12. Lasers as a tool for plasma diagnostics

    International Nuclear Information System (INIS)

    Jahoda, F.C.

    1981-01-01

    Lasers can be used as non-perturbative probes to measure many plasma parameters. Plasma refractivity is primarily a function of electron density, and interferometric measurements of phase changes with either pulsed or CW lasers can determine this parameter with spatial or temporal resolution over several orders of magnitude sensitivity by using laser wavelengths from the near uv to the far infrared. Laser scattering from free electrons yields the most fundamental electron temperature measurements in the plasma parameter range where individual scattering events are uncorrelated in phase and ion temperature or plasma wave and turbulence structure in the opposite limit. Laser scattering from bound electrons can be many orders of magnitude larger if the laser is matched to appropriate resonance frequencies and can be used in specialized circumstances for measuring low-ionized impurity or dominant species neutral concentrations and velocities

  13. Multi-photon ionization of atoms in intense short-wavelength radiation fields

    Science.gov (United States)

    Meyer, Michael

    2015-05-01

    The unprecedented characteristics of XUV and X-ray Free Electron Lasers (FELs) have stimulated numerous investigations focusing on the detailed understanding of fundamental photon-matter interactions in atoms and molecules. In particular, the high intensities (up to 106 W/cm2) giving rise to non-linear phenomena in the short wavelength regime. The basic phenomenology involves the production of highly charged ions via electron emission to which both sequential and direct multi-photon absorption processes contribute. The detailed investigation of the role and relative weight of these processes under different conditions (wavelength, pulse duration, intensity) is the key element for a comprehensive understanding of the ionization dynamics. Here the results of recent investigations are presented, performed at the FELs in Hamburg (FLASH) and Trieste (FERMI) on atomic systems with electronic structures of increasing complexity (Ar, Ne and Xe). Mainly, electron spectroscopy is used to obtain quantitative information about the relevance of various multi-photon ionization processes. For the case of Ar, a variety of processes including above threshold ionization (ATI) from 3p and 3s valence shells, direct 2p two-photon ionization and resonant 2p-4p two-photon excitations were observed and their role was quantitatively determined comparing the experimental ionization yields to ab-initio calculations of the cross sections for the multi-photon processes. Using Ar as a benchmark to prove the reliability of the combined experimental and theoretical approach, the more complex and intriguing case of Xe was studied. Especially, the analysis of the two-photon ATI from the Xe 4d shell reveals new insight into the character of the 4d giant resonance, which was unresolved in the linear one-photon regime. Finally, the influence of intense XUV radiation to the relaxation dynamics of the Ne 2s-3p resonance was investigated by angle-resolved electron spectroscopy, especially be observing

  14. Resonant Laser Manipulation of an Atomic Beam

    Science.gov (United States)

    2010-07-01

    Technical Paper 3. DATES COVERED (From - To) 4. TITLE AND SUBTITLE 5a. CONTRACT NUMBER Resonant Laser Manipulation of an Atomic Beam...steering and collimating flows with higher densities and energies than current common practice . One impediment to this extension is the development of...where Δεg is the ground state Stark shift, Ω is the Rabi frequency (related to intensity), Isat is the saturation intensity of the transition, and I(r

  15. Anisotropy in semipolar InGaN laser diodes: Consequences for resonator design and facet formation

    Energy Technology Data Exchange (ETDEWEB)

    Rass, Jens; Vogt, Patrick [Technische Universitaet Berlin (Germany). Institute of Solid State Physics; Wernicke, Tim; John, Wilfred; Einfeldt, Sven; Weyers, Markus [Ferdinand-Braun-Institut fuer Hoechstfrequenztechnik, Berlin (Germany); Kneissl, Michael [Technische Universitaet Berlin (Germany). Institute of Solid State Physics; Ferdinand-Braun-Institut fuer Hoechstfrequenztechnik, Berlin (Germany)

    2010-07-01

    For InAlGaN-based light emitting devices on nonpolar and semipolar substrate orientations the polarization fields can be reduced. Birefringence and gain anisotropy influence the optical modes of semipolar separate confinement hetero structures. We have investigated the threshold for amplified spontaneous emission and the optical polarization state of the eigenmodes for laser resonators with different orientations on various semipolar and nonpolar substrates. We found that semipolar resonators along the projection of the c-axis onto the surface have a lower threshold and the light is TE-polarized. Nonpolar resonators perpendicular to the c-axis on the other hand have elevated thresholds and hence a lower gain as well as a tilted linear optical polarization with the electric field nearly parallel to the c-axis of the crystal. In order to obtain devices with low threshold and maximum performance, laser resonators on semipolar substrates have to be oriented along the semipolar orientation, posing a challenge for the fabrication of laser facets. Technologies such as laser assisted cleaving, chemical dry etching and wet chemical post processing are presented and their suitability for the generation of smooth vertical facets is discussed.

  16. Efficient mass-selective three-photon ionization of zirconium atoms

    Science.gov (United States)

    Page, Ralph H.

    1994-01-01

    In an AVLIS process, .sup.91 Zr is selectively removed from natural zirconium by a three-step photoionization wherein Zr atoms are irradiated by a laser beam having a wavelength .lambda..sub.1, selectively raising .sup.91 Zr atoms to an odd-parity E.sub.1 energy level in the range of 16000-19000 cm.sup.-1, are irradiated by a laser beam having a wavelength .lambda..sub.2 to raise the atoms from an E.sub.l level to an even-parity E.sub.2 energy level in the range of 35000-37000 cm.sup.-1 and are irradiated by a laser beam having a wavelength .lambda..sub.3 to cause a resonant transition of atoms from an E.sub.2 level to an autoionizing level above 53506 cm.sup.-1. .lambda..sub.3 wavelengths of 5607, 6511 or 5756 .ANG. will excite a zirconium atom from an E.sub.2 energy state of 36344 cm.sup.-1 to an autoionizing level; a .lambda..sub.3 wavelength of 5666 .ANG. will cause an autoionizing transition from an E.sub.2 level of 36068 cm.sup.-1 ; and a .lambda. .sub.3 wavelength of 5662 .ANG. will cause an ionizing resonance of an atom at an E.sub.2 level of 35904 cm.sup.-1.

  17. Laser Resonators and Beam Propagation Fundamentals, Advanced Concepts and Applications

    CERN Document Server

    Hodgson, Norman

    2005-01-01

    Optical Resonators provides a detailed discussion of the properties of optical resonators for lasers from basic theory to recent research. In addition to describing the fundamental theories of resonators such as geometrical optics, diffraction, and polarisation the characteristics of all important resonator schemes and their calculation are presented. Experimental examples, practical problems and a collection of measurement techniques support the comprehensive treatment of the subject. Optical Resonators is the only book currently available that provides a comprehensive overview of the the subject. Combined with the structure of the text and the autonomous nature of the chapters this work will be as suitable for those new to the field as it will be invaluable to specialists conducting research. This second edition has been enlarged by new sections on Q-switching and resonators with internal phase/amplitude control. In addition, the whole book has been brought up-to-date.

  18. Resonance Enhanced Multi-photon Spectroscopy of DNA

    Science.gov (United States)

    Ligare, Marshall Robert

    its intrinsic molecular properties and possibly a hydrogen bonding solvent capable of dissipating excess vibrational energy. Due to the high specificity and sensitivity of resonant two photon ionization coupled with molecular beam mass spectrometry a new analytical technique for identifying molecular markers in archaeological vessels is presented. The xanthine alkaloids theobromine, theophylline and caffeine are identified in Central American and North American pottery sherds by direct desorption/resonant laser ionization mass spectrometry.

  19. Relativistic electronic dressing in laser-assisted ionization of atomic hydrogen by electron impact

    International Nuclear Information System (INIS)

    Attaourti, Y.; Taj, S.

    2004-01-01

    Within the framework of the coplanar binary geometry where it is justified to use plane wave solutions for the study of the (e,2e) reaction and in the presence of a circularly polarized laser field, we introduce as a first step the Dirac-Volkov plane wave Born approximation 1 where we take into account only the relativistic dressing of the incident and scattered electrons. Then, we introduce the Dirac-Volkov plane wave Born approximation 2 where we take totally into account the relativistic dressing of the incident, scattered, and ejected electrons. We then compare the corresponding triple differential cross sections for laser-assisted ionization of atomic hydrogen by electron impact both for the nonrelativistic and the relativistic regime

  20. Laser-induced multiphoton transitions

    International Nuclear Information System (INIS)

    Stenholm, S.

    1978-06-01

    Laser induced multiphoton processes are reviewed. The effects of strong fields on atoms are discussed. The perturbation treatment is presented and also its generalization to treat intermediate resonances. The influence of atomic coherence is discussed heuristically and the relation between quantal and classical descriptions of the field is elucidated by reference to the dressed atom description. Atomic ionization experiments are reviewed and the present understanding of multiphoton dissociation of molecules is explained. Finally some prospects for the future are discussed. (author)