Coincident photoelectron spectroscopy on superconductors

International Nuclear Information System (INIS)

Voss, Stefan

2011-01-01

Aim of the performed experiments of this thesis was to attempt to detect Cooper pairs as carriers of the superconducting current directly by means of the photoelectric effect. The method of the coincident photoelectron spectroscopy aims thereby at the detection of two coherently emitted electrons by the interaction with a photon. Because electrostatic analyzers typically cover only a very small spatial angle, which goes along with very low coincidence rates, in connection with this thesis a time-of-flight projection system has been developed, which maps nearly the whole spatial angle on a position-resolving detector. The pulsed light source in form of special synchrotron radiation necessary for the measurement has been adjusted so weak, that only single photons could arrive at the sample. Spectroscoped were beside test measurements on silver layers both a lead monocrystal as representative of the classical BCS superconductors and monocrystalline Bi 2 Sr 2 CaCu 2 O 8 from the family of the high-temperature superconductors. With excitation energies up to 40 eV could be shown that sufficiently smooth and clean surfaces in the superconducting phase exhibit within the resolving power of about 0.5 eV no recognizable differences in comparison to the normally conducting phase. Beside these studies furthermore the simple photoemission at the different samples and especially in the case of the lead crystal is treated, because here no comparable results are known. Thereby the whole momentum space is discussed and the Fermi surface established as three-dimensional model, by means of which the measurement results are discussed. in the theoretical descriptions different models for the Cooper-pair production are presented, whereby to the momentum exchange with the crystal a special role is attributed, because this can only occur in direct excitations via discrete lattice vectors.

Review of the theoretical description of time-resolved angle-resolved photoemission spectroscopy in electron-phonon mediated superconductors

Energy Technology Data Exchange (ETDEWEB)

Kemper, A.F. [Department of Physics, North Carolina State University, Raleigh, NC (United States); Sentef, M.A. [Max Planck Institute for the Structure and Dynamics of Matter, Center for Free Electron Laser Science, Hamburg (Germany); Moritz, B. [Stanford Institute for Materials and Energy Sciences (SIMES), SLAC National Accelerator Laboratory, Menlo Park, CA (United States); Devereaux, T.P. [Stanford Institute for Materials and Energy Sciences (SIMES), SLAC National Accelerator Laboratory, Menlo Park, CA (United States); Geballe Laboratory for Advanced Materials, Stanford University, Stanford, CA (United States); Freericks, J.K. [Department of Physics, Georgetown University, Washington, DC (United States)

2017-09-15

We review recent work on the theory for pump/probe photoemission spectroscopy of electron-phonon mediated superconductors in both the normal and the superconducting states. We describe the formal developments that allow one to solve the Migdal-Eliashberg theory in nonequilibrium for an ultrashort laser pumping field, and explore the solutions which illustrate the relaxation as energy is transferred from electrons to phonons. We focus on exact results emanating from sum rules and approximate numerical results which describe rules of thumb for relaxation processes. In addition, in the superconducting state, we describe how Anderson-Higgs oscillations can be excited due to the nonlinear coupling with the electric field and describe mechanisms where pumping the system enhances superconductivity. (copyright 2017 by WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim)

Application of ESCA spectroscopy to the study of electronic structure of high temperature superconductors

International Nuclear Information System (INIS)

Dagoury, G.

1988-01-01

Characteristics of high T c oxide superconductors are very sensitive to slight variation of chemical composition, ESCA spectroscopy is used for identification of YBaCuO superconductivity. Binding energy of the different electronic levels and structure of valence band are determined [fr

Contact spectroscopy of high-temperature superconductors (Review). I - Physical and methodological principles of the contact spectroscopy of high-temperature superconductors. Experimental results for La(2-x)Sr(x)CuO4 and their discussion

Science.gov (United States)

Ianson, I. K.

1991-03-01

Research in the field of high-temperature superconductors based on methods of tunneling and microcontact spectroscopy is reviewed in a systematic manner. The theoretical principles of the methods are presented, and various types of contacts are described and classified. Attention is given to deviations of the measured volt-ampere characteristics from those predicted by simple theoretical models and those observed for conventional superconductors. Results of measurements of the energy gap and fine structure of volt ampere characteristic derivatives are presented for La(2-x)Sr(x)CuO4.

Laser spectroscopy and laser isotope separation of atomic gadolinium

International Nuclear Information System (INIS)

Chen, Y. W.; Yamanaka, C.; Nomaru, K.; Kou, K.; Niki, H.; Izawa, Y.; Nakai, S.

1994-01-01

Atomic vapor laser isotope separation (AVLIS) is a process which uses intense pulsed lasers to selectively photoionize one isotopic species of a chemical element, after which these ions are extracted electromagnetically. The AVLIS has several advantages over the traditional methods based on the mass difference, such as high selectivity, low energy consumption, short starting time and versatility to any atoms. The efforts for atomic vapor laser isotope separation at ILT and ILE, Osaka University have been concentrated into the following items: 1) studies on laser spectroscopy and laser isotope separation of atomic gadolinium, 2) studies on interaction processes including coherent dynamics, propagation effects and atom-ion collision in AVLIS system, 3) development of laser systems for AVLIS. In this paper, we present experimental results on the laser spectroscopy and laser isotope separation of atomic gadolinium.

Double pulse laser ablation and plasma: Laser induced breakdown spectroscopy signal enhancement

International Nuclear Information System (INIS)

Babushok, V.I.; DeLucia, F.C.; Gottfried, J.L.; Munson, C.A.; Miziolek, A.W.

2006-01-01

A review of recent results of the studies of double laser pulse plasma and ablation for laser induced breakdown spectroscopy applications is presented. The double pulse laser induced breakdown spectroscopy configuration was suggested with the aim of overcoming the sensitivity shortcomings of the conventional single pulse laser induced breakdown spectroscopy technique. Several configurations have been suggested for the realization of the double pulse laser induced breakdown spectroscopy technique: collinear, orthogonal pre-spark, orthogonal pre-heating and dual pulse crossed beam modes. In addition, combinations of laser pulses with different wavelengths, different energies and durations were studied, thus providing flexibility in the choice of wavelength, pulse width, energy and pulse sequence. The double pulse laser induced breakdown spectroscopy approach provides a significant enhancement in the intensity of laser induced breakdown spectroscopy emission lines up to two orders of magnitude greater than a conventional single pulse laser induced breakdown spectroscopy. The double pulse technique leads to a better coupling of the laser beam with the plasma plume and target material, thus providing a more temporally effective energy delivery to the plasma and target. The experimental results demonstrate that the maximum effect is obtained at some optimum separation delay time between pulses. The optimum value of the interpulse delay depends on several factors, such as the target material, the energy level of excited states responsible for the emission, and the type of enhancement process considered. Depending on the specified parameter, the enhancement effects were observed on different time scales ranging from the picosecond time level (e.g., ion yield, ablation mass) up to the hundred microsecond level (e.g., increased emission intensity for laser induced breakdown spectroscopy of submerged metal target in water). Several suggestions have been proposed to explain

Laser spectroscopy

International Nuclear Information System (INIS)

Letokhov, V.S.

1981-01-01

This article describes recent progress in the application of laser atomic spectroscopy to study parameters of nuclei available in very small quantities; radioactive nuclei, rare isotopes, nuclear isomers, etc, for which study by conventional spectroscopic methods is difficult. (author)

Laser spectroscopy

CERN Document Server

Demtröder, Wolfgang

2008-01-01

Keeping abreast of the latest techniques and applications, this new edition of the standard reference and graduate text on laser spectroscopy has been completely revised and expanded. While the general concept is unchanged, the new edition features a broad array of new material, e.g., frequency doubling in external cavities, reliable cw-parametric oscillators, tunable narrow-band UV sources, more sensitive detection techniques, tunable femtosecond and sub-femtosecond lasers (X-ray region and the attosecond range), control of atomic and molecular excitations, frequency combs able to synchronize independent femtosecond lasers, coherent matter waves, and still more applications in chemical analysis, medical diagnostics, and engineering.

Ultrafast Laser-Based Spectroscopy and Sensing: Applications in LIBS, CARS, and THz Spectroscopy

Science.gov (United States)

Leahy-Hoppa, Megan R.; Miragliotta, Joseph; Osiander, Robert; Burnett, Jennifer; Dikmelik, Yamac; McEnnis, Caroline; Spicer, James B.

2010-01-01

Ultrafast pulsed lasers find application in a range of spectroscopy and sensing techniques including laser induced breakdown spectroscopy (LIBS), coherent Raman spectroscopy, and terahertz (THz) spectroscopy. Whether based on absorption or emission processes, the characteristics of these techniques are heavily influenced by the use of ultrafast pulses in the signal generation process. Depending on the energy of the pulses used, the essential laser interaction process can primarily involve lattice vibrations, molecular rotations, or a combination of excited states produced by laser heating. While some of these techniques are currently confined to sensing at close ranges, others can be implemented for remote spectroscopic sensing owing principally to the laser pulse duration. We present a review of ultrafast laser-based spectroscopy techniques and discuss the use of these techniques to current and potential chemical and environmental sensing applications. PMID:22399883

Ultrafast Laser-Based Spectroscopy and Sensing: Applications in LIBS, CARS, and THz Spectroscopy

Directory of Open Access Journals (Sweden)

Megan R. Leahy-Hoppa

2010-04-01

Full Text Available Ultrafast pulsed lasers find application in a range of spectroscopy and sensing techniques including laser induced breakdown spectroscopy (LIBS, coherent Raman spectroscopy, and terahertz (THz spectroscopy. Whether based on absorption or emission processes, the characteristics of these techniques are heavily influenced by the use of ultrafast pulses in the signal generation process. Depending on the energy of the pulses used, the essential laser interaction process can primarily involve lattice vibrations, molecular rotations, or a combination of excited states produced by laser heating. While some of these techniques are currently confined to sensing at close ranges, others can be implemented for remote spectroscopic sensing owing principally to the laser pulse duration. We present a review of ultrafast laser-based spectroscopy techniques and discuss the use of these techniques to current and potential chemical and environmental sensing applications.

Femtosecond laser spectroscopy

CERN Document Server

Hannaford, Peter

2005-01-01

As concepts and methodologies have evolved over the past two decades, the realm of ultrafast science has become vast and exciting and has impacted many areas of chemistry, biology and physics, and other fields such as materials science, electrical engineering, and optical communication. The field has recently exploded with the announcement of a series of remarkable new developments and advances. This volume surveys this recent growth in eleven chapters written by leading international researchers in the field. It includes sections on femtosecond optical frequency combs, soft x-ray femtosecond laser sources, and attosecond laser sources. In addition, the contributors address real-time spectroscopy of molecular vibrations with sub-5-fs pulses and multidimensional femtosecond coherent spectroscopies for studying molecular and electron dynamics. Novel methods for measuring and characterizing ultrashort laser pulses and ultrashort pulses of light are also described. The topics covered are revolutionizing the field...

Instabilities in superconductors and in intense laser produced plasma's

International Nuclear Information System (INIS)

Banerjee, Satyajit S.; Mohan, Shyam; Sinha, Jaivardhan; Kahaly, Subendhu; Ravindra Kumar, G.

2007-01-01

In this talk I will attempt to discuss phenomena's in two areas of physics which appear quite divorced from each other, viz., superconductivity and plasma's. The first portion of the talk will describe the behavior of a collection of vortices in superconductors in a random pinning environment. Vortices manifest themselves in a variety of systems, like in fluids and in type II superconductors. A collection of vortices inside superconductors behaves like an elastic media. Investigating this elastic medium of the vortex state is a convenient prototype for investigating similar physics in a wide variety of systems, viz., charge density waves, Wigner crystals, magnetic domains, etc. The behavior of all these systems can be generalized under, nature of elastic media in the presence of a random pinning environment and thermal fluctuations. Based on the idea that softer matter is easy to pin we have attempted to investigate how the vortex lattice disorders as its gets softer. Surprisingly we find evidence to two distinct types of instabilities in the vortex lattice instead of one. These two instabilities produce vastly different effects on certain quantities associated with the extent of disorder in the superconductor. It appears that prior to softening of the vortex state, a heterogeneously pinned state of the vortex matter appears, perhaps through a KT like transition. In the second part of the talk, I will attempt to describe some of our recent results pertaining to instabilities and the appearance of giant magnetic fields in plasma's. These results have been obtained with a high sensitivity magneto-optical imaging setup we have developed at IIT Kanpur. Using the setup, we investigate distribution of magnetic fields around dense solid plasmas generated by intense p-polarized laser (∼10 16 Wcm -2 , 100 fs) irradiation of magnetic tapes, using high sensitivity magneto optical imaging technique. We demonstrate giant axial magnetic fields and map out for the first time

Infrared diode laser spectroscopy

Czech Academy of Sciences Publication Activity Database

Civiš, Svatopluk; Cihelka, Jaroslav; Matulková, Irena

2010-01-01

Roč. 18, č. 4 (2010), s. 408-420 ISSN 1230-3402 R&D Projects: GA AV ČR IAA400400705 Institutional research plan: CEZ:AV0Z40400503 Keywords : FTIR spectroscopy * absorption spectroscopy * laser diodes Subject RIV: CF - Physical ; Theoretical Chemistry Impact factor: 1.027, year: 2010

Laser-induced breakdown spectroscopy analysis of asbestos

International Nuclear Information System (INIS)

Caneve, L.; Colao, F.; Fabbri, F.; Fantoni, R.; Spizzichino, V.; Striber, J.

2005-01-01

Laser-induced breakdown spectroscopy was applied to test the possibility of detecting and identifying asbestos in different samples in view of the perspective at field operation without sample preparation which is peculiar to this technique. Several like-resin materials were first investigated by laser-induced breakdown spectroscopy, in order to find an asbestos container assuring safe laboratory operation during the material characterization aimed to identify indicators suitable for a quick identification on field. Successively, spectra of asbestos samples of both in serpentine and amphibole forms were measured and the variability in elemental composition was calculated from the emission spectra. Ratios of intensities of characteristic elements were tested as indicators for asbestos recognition. Laser-induced breakdown spectroscopy results were compared with those obtained by analyzing the same asbestos samples with a scanning electron microscopy equipped with an energy dispersive X-ray spectroscopy, a good correlation was found for Mg/Si and Fe/Si, thus showing the capability of laser-induced breakdown spectroscopy as a diagnostic tool for this category of materials. In particular, it was demonstrated that the method based on two indicators derived from laser-induced breakdown spectroscopy intensity ratios allows to discriminate between asbestos and cements in single shot measurements suitable to field operation

Proceedings of the 3rd Symposium on Laser Spectroscopy

International Nuclear Information System (INIS)

1995-11-01

This proceedings contains articles of the 3rd Symposium on Laser Spectroscopy. It was held on Nov 10-11, 1995 in Taejeon, Korea. The main topics are as follows: Laser Isotope, Laser Spectroscopy, Laser Fusion, Laser Applications and so on. (Yi, J. H.)

Proceedings of the 5th Symposium on Laser Spectroscopy

International Nuclear Information System (INIS)

1997-11-01

This proceedings contains articles of the 5th Symposium on Laser Spectroscopy. It was held on Nov 7-8, 1997 in Taejeon, Korea. The main topics are as follows: Laser Isotope, Laser Spectroscopy, Laser Fusion, Laser Applications and so on. (Yi, J. H.)

Proceedings of the 4th Symposium on Laser Spectroscopy

International Nuclear Information System (INIS)

1996-11-01

This proceedings contains articles of the 4th Symposium on Laser Spectroscopy. It was held on Nov 8-9, 1996 in Taejeon, Korea. The main topics are as follows: Laser Isotope, Laser Spectroscopy, Laser Fusion, Laser Applications and so on. (Yi, J. H.)

Proceedings of the 1st Symposium on Laser Spectroscopy

International Nuclear Information System (INIS)

1993-11-01

This proceedings contains articles of the 1st Symposium on Laser Spectroscopy. It was held on Nov 11, 1993 in Taejeon, Korea. The main topics are as follows: Laser Isotope, Laser Spectroscopy, Laser Fusion, Laser Applications and so on. (Yi, J. H.)

Proceedings of the 2nd Symposium on Laser Spectroscopy

International Nuclear Information System (INIS)

1994-11-01

This proceedings contains articles of the 2nd Symposium on Laser Spectroscopy. It was held on Nov 3-4, 1994 in Taejeon, Korea. The main topics are as follows: Laser Isotope, Laser Spectroscopy, Laser Fusion, Laser Applications and so on. (Yi, J. H.)

BCS superconductors: The out-of-equilibrium response to a laser pulse

Science.gov (United States)

Avella, Adolfo

2018-05-01

The dynamics of a 2D d-wave BCS superconductor driven out-of-equilibrium by a perpendicularly-impinging polarized laser pulse is analyzed on varying the laser pulse characteristics. The observed effects include: oscillations both in the amplitude and in the phase of the superconducting order parameter, suppression of the superconductivity, but also its enhancement with a strong dependence on all varying parameters and, in particular, on the polarization in plane of the applied vector potential and on the value of its frequency. This study opens up the possibility to distinguish very clearly the behavior of the nodal and anti-nodal non-thermal excitations and to tackle some of the puzzling results of the current experimental scenario in the field.

Structure, stoichiometry and spectroscopy of oxide superconductors

Science.gov (United States)

Rao, C. N. R.

In the new oxide superconductors, structure and oxygen stoichiometry play the most crucial role. Thus, all the high-temperature oxide superconductors are orthorhombic perovskites with low-dimensional features. Oxygen stoichiometry in YBa2Cu3O7-δ has an important bearing on the structure as well as superconductivity. This is equally true in the La3-xBa3+xCu 6O14+δ system of which only the 123 oxide (x = 1) with the orthorhombic structure shows high Tc. Orthorhombicity though not essential, is generally found ; it is necessary for the formation of twins. The nature of oxygen and copper in the cuprates has been examined by electron spectroscopy. Copper in these cuprates is only in 1 + and 2 + states. It seems likely that oxygen holes are responsible for superconductivity of the cuprates as well as Ba(Bi, Pb)O3. High Tc superconductivity is also found in oxides of the Bi-(Ca, Sr)-Cu-O and related oxides possessing Cu-O sheets. Dans les nouveaux oxydes supraconducteurs, la structure et la stoechiométrie de l'oxygène jouent un rôle absolument crucial. Ainsi, tous les oxydes supraconducteurs à haute température critique sont des pérovskites orthorhombiques possédant des propriétés de basse dimensionnalité. La stoechiométrie de l'oxygène dans YBa2Cu3O7- δ a une influence importante tant sur la structure que sur la supraconductibilité. Ceci est également valable pour les composés du type La3 -xBa3 + xCu 6O14 + δ parmi lesquels seul l'oxyde 123 (x = 1) à structure orthorhombique présente un grand T. Bien que ce ne soit pas essentiel, cette orthorhombicité est fréquente ; elle est nécessaire à la formation de macles. La nature de l'oxygène et du cuivre a été observée par spectroscopie électronique... Dans ces cuprates, le cuivre est dans les seuls états de valence + 1 et + 2. Vraisemblablement, les trous logés sur l'oxygène sont responsables de la supraconductibilité des cuprates comme de Ba(Bi, Pb)O3. La supraconductibilité existe aussi

Laser Materials and Laser Spectroscopy - A Satellite Meeting of IQEC '88

Science.gov (United States)

Wang, Zhijiang; Zhang, Zhiming

1989-03-01

The Table of Contents for the book is as follows: * Laser Materials * Laser Site Spectroscopy of Transition Metal Ions in Glass * Spectroscopy of Chromium Doped Tunable Laser Materials * Spectroscopic Properties of Nd3+ Ions in LaMgAl11O19 Crystal * Spectral Study and 2.938 μm Laser Emission of Er3+ in the Y3Al5O12 Crystal * Raman-infrared Spectra and Radiationless Relaxation of Laser Crystal NdAl3(BO3)4 * A Study on HB and FLN in BaFCl0.5Br0.5:Sm2+ at 77K * Pair-pumped Upconversion Solid State Lasers * CW Upconversion Laser Action in Neodymium and Erbium doped Solids * Ultra-high Sensitive Upconversion Fluorescence of YbF3 Doped with Trace Tm3+ and Er3+ * The Growth and Properties of NYAB and EYAB Multifunctional Crystal * Study on Fluorescence and Laser Light of Er3+ in Glass * Growth and Properties of Single Crystal Fibers for Laser Materials * A Study on the Quality of Sapphire, Ruby and Ti3+ Doped Sapphire Grown by Temperature Gradient Technique (TGT) and Czochralski Technique (CZ) * The Measurement of Output Property of Ti3+ Al2O3 Laser Crystal * An Xα Study of the Laser Crystal MgF2 : V2+ * Q-switched NAB Laser * Miniature YAG Lasers * Study of High Efficiency {LiF}:{F}^-_2 Color Center Crystals * Study on the Formation Conditions and Optical Properties of (F2+)H Color Center in NaCl:OH- Crystals * Novel Spectroscopic Properties of {LiF}:{F}^+_3 - {F}_2 Mixed Color Centers Laser Crystals * Terraced Substrate Visible GaAlAs Semiconductor Lasers with a Large Optical Cavity * The Temperature Dependence of Gain Spectra, Threshold Current and Auger Recombination in InGaAsP-InP Double Heterojunction Laser diode * Time-resolved Photoluminescence and Energy Transfer of Bound Excitons in GaP:N Crystals * Optical Limiting with Semiconductors * A Critical Review of High-efficiency Crystals for Tunable Lasers * Parametric Scattering in β - BaB2O4 Crystal Induced by Picosecond Pulses * Generation of Picosecond Pulses at 193 nm by Frequency Mixing in β - BaB2O4

New electrodynamic and electrostatic models with applications to antenna theory, superconductor slots, and lasers

International Nuclear Information System (INIS)

Eggleston, S.W.

1988-01-01

The common set of functions used as a basis for the solution to Helmholtz and Laplace's equations is expanded to include solutions not found in the handbooks. With this complete set of basis functions of integer indexes, a multicentered model is developed using Debye-like potentials for electrodynamics and standard potentials for electrostatics. The resonant modes of the model are the exact solution to a wide variety of thin linear antennas and antenna-like structures, narrow linear gaps in superconductors, microscopic linear lasers, and arbitrary linear charge distributions. The model is applied to a linear antenna of large-diameter, via Pocklington's and Hallen's integral equation. The nonsinusoidal current of this linear antenna of large-diameter is decomposed into idealized components using equal and unequal spacing, and single and many centered linear antennas. Babinet's principal is brought into play to apply the model to gaps in superconductors. The model of a laser is in the microscopic domain, a domain that has not been looked at previously. The electrostatic model allows the modeling of an arbitrary linear charge distribution between two points

Recent advancements in spectroscopy using tunable diode lasers

International Nuclear Information System (INIS)

Nasim, Hira; Jamil, Yasir

2013-01-01

Spectroscopy using tunable diode lasers is an area of research that has gone through a dramatic evolution over the last few years, principally because of new exciting approaches in the field of atomic and molecular spectroscopy. This article attempts to review major recent advancements in the field of diode laser based spectroscopy. The discussion covers the developments made so far in the field of diode lasers and illustrates comprehensively the properties of free-running diode lasers. Since the commercially available free-running diode lasers are not suitable for high-precision spectroscopic studies, various techniques developed so far for converting these free-running diode lasers into true narrow linewidth tunable laser sources are discussed comprehensively herein. The potential uses of diode lasers in different spectroscopic fields and their extensive list of applications have also been included, which may be interesting for the novice and the advanced user as well. (topical review)

Linear and Nonlinear Molecular Spectroscopy with Laser Frequency Combs

Science.gov (United States)

Picque, Nathalie

2013-06-01

The regular pulse train of a mode-locked femtosecond laser can give rise to a comb spectrum of millions of laser modes with a spacing precisely equal to the pulse repetition frequency. Laser frequency combs were conceived a decade ago as tools for the precision spectroscopy of atomic hydrogen. They are now becoming enabling tools for an increasing number of applications, including molecular spectroscopy. Recent experiments of multi-heterodyne frequency comb Fourier transform spectroscopy (also called dual-comb spectroscopy) have demonstrated that the precisely spaced spectral lines of a laser frequency comb can be harnessed for new techniques of linear absorption spectroscopy. The first proof-of-principle experiments have demonstrated a very exciting potential of dual-comb spectroscopy without moving parts for ultra-rapid and ultra-sensitive recording of complex broad spectral bandwidth molecular spectra. Compared to conventional Michelson-based Fourier transform spectroscopy, recording times could be shortened from seconds to microseconds, with intriguing prospects for spectroscopy of short lived transient species. The resolution improves proportionally to the measurement time. Therefore longer recordings allow high resolution spectroscopy of molecules with extreme precision, since the absolute frequency of each laser comb line can be known with the accuracy of an atomic clock. Moreover, since laser frequency combs involve intense ultrashort laser pulses, nonlinear interactions can be harnessed. Broad spectral bandwidth ultra-rapid nonlinear molecular spectroscopy and imaging with two laser frequency combs is demonstrated with coherent Raman effects and two-photon excitation. Real-time multiplex accessing of hyperspectral images may dramatically expand the range of applications of nonlinear microscopy. B. Bernhardt et al., Nature Photonics 4, 55-57 (2010); A. Schliesser et al. Nature Photonics 6, 440-449 (2012); T. Ideguchi et al. arXiv:1201.4177 (2012) T

Effect of laser pulse energies in laser induced breakdown spectroscopy in double-pulse configuration

International Nuclear Information System (INIS)

Benedetti, P.A.; Cristoforetti, G.; Legnaioli, S.; Palleschi, V.; Pardini, L.; Salvetti, A.; Tognoni, E.

2005-01-01

In this paper, the effect of laser pulse energy on double-pulse laser induced breakdown spectroscopy signal is studied. In particular, the energy of the first pulse has been changed, while the second pulse energy is held fixed. A systematic study of the laser induced breakdown spectroscopy signal dependence on the interpulse delay is performed, and the results are compared with the ones obtained with a single laser pulse of energy corresponding to the sum of the two pulses. At the same time, the crater formed at the target surface is studied by video-confocal microscopy, and the variation in crater dimensions is correlated to the enhancement of the laser induced breakdown spectroscopy signal. The results obtained are consistent with the interpretation of the double-pulse laser induced breakdown spectroscopy signal enhancement in terms of the changes in ambient gas pressure produced by the shock wave induced by the first laser pulse

Ultrafast laser spectroscopy in complex solid state materials

Energy Technology Data Exchange (ETDEWEB)

Li, Tianqi [Iowa State Univ., Ames, IA (United States)

2014-12-01

This thesis summarizes my work on applying the ultrafast laser spectroscopy to the complex solid state materials. It shows that the ultrafast laser pulse can coherently control the material properties in the femtosecond time scale. And the ultrafast laser spectroscopy can be employed as a dynamical method for revealing the fundamental physical problems in the complex material systems.

Laser spectroscopy used in nuclear physics; La spectroscopie laser appliquee a la physique nucleaire

Energy Technology Data Exchange (ETDEWEB)

Le Blanc, F

2001-04-05

The study of nuclear shapes is a basic topic since it constitutes an excellent ground for testing and validating nuclear models. Measurements of the electron quadrupolar moment, of the nuclear charge radius and of the magnetic dipolar moment shed light on the nuclear deformation. Laser spectroscopy is a specific tool for such measurements, it is based on the interaction of the nucleus with the surrounding electron cloud (hyperfine structure), it is then an external approach of the shape of the nucleus whereas the classical nuclear spectroscopy ({alpha}, {beta} or {gamma}) gives information on the deformation from the inside of the nucleus. The author describes 2 techniques of laser spectroscopy: the colinear spectroscopy directly applied to a beam issued from an isotope separator and the resonant ionization spectroscopy linked with atom desorption that allows the study of particular nuclei. In order to illustrate both methods some effective measurements are presented: - the colinear spectroscopy has allowed the achievement of the complete description of the isomeric state (T = 31 years) of hafnium-178; - The experiment Complis has revealed an unexpected even-odd zigzag effect on very neutron-deficient platinum isotopes; and - the comparison of 2 isotopes of gold and platinum with their isomers has shown that the inversion of 2 levels of neutron, that was found out by nuclear spectroscopy, is in fact a consequence of a change in the nuclear shape. (A.C.)

Laser spectroscopy: Assessment of research needs for laser technologies applied to advanced spectroscopic methods

International Nuclear Information System (INIS)

Hurst, G.S.

1990-05-01

This report is organized as follows. Section 2 summarizes the current program of DOE's Office of Health and Environmental Research (OHER) and provides some remarks on low laser science and technology could beneficially impact most of the research programs. Section 3 provides a brief global perspective on laser technology and attempts to define important trends in the field. Similarly, Section 4 provides a global perspective on laser spectroscopy and addresses important trends. Thus, Section 5 focuses on the trends in laser technology and spectroscopy which could impact the OHER mission in significant ways and contains the basis for recommendations made in the executive summary. For those with limited familiarity with laser technology and laser spectroscopy, reference is made to Appendix 1 for a list of abbreviations and acronyms. Appendix 2 can serve a useful review or tutorial for those who are not deeply involved with laser spectroscopy. Even those familiar with laser spectroscopy and laser technology may find it useful to know precisely what the authors of this document mean by certain specialized terms and expressions. Finally, a note on the style of referencing may be appropriate. Whenever possible a book or review articles is referenced as the preferred citation. However, we frequently found it useful to reference a number of individual papers of recent origin or those which were not conveniently found in the review articles

Proceedings of the 10th International Symposium on Laser Spectroscopy

International Nuclear Information System (INIS)

2002-01-01

This proceedings contains articles of the 10th International Symposium on Laser Spectroscopy. It was held on 1-2 Nov 2002 in Taejeon, Korea. The main topics are as follows: Laser Isotope, Laser Spectroscopy, Laser Fusion, Laser Applications and so on. (Yi, J. H.)

Proceedings of the 9th International Symposium on Laser Spectroscopy

International Nuclear Information System (INIS)

2001-11-01

This proceedings contains articles of the 9th International Symposium on Laser Spectroscopy. It was held on 2-3 Nov 2001 in Taejeon, Korea. The main topics are as follows: Laser Isotope, Laser Spectroscopy, Laser Fusion, Laser Applications and so on. (Yi, J. H.)

Proceedings of the 11th International Symposium on Laser Spectroscopy

International Nuclear Information System (INIS)

2003-11-01

This proceedings contains articles of the 11th International Symposium on Laser Spectroscopy. It was held on 7-8 Nov 2003 in Taejeon, Korea. The main topics are as follows: Laser Isotope, Laser Spectroscopy, Laser Fusion, Laser Applications and so on. (Yi, J. H.)

Foundations of laser spectroscopy

CERN Document Server

Stenholm, Stig

2005-01-01

A simple presentation of the theoretical foundations of steady-state laser spectroscopy, this text helps students to apply theory to calculations with a systematic series of examples and exercises. 1984 edition.

Deposition of high Tc superconductor thin films by pulsed excimer laser ablation and their post-synthesis processing

International Nuclear Information System (INIS)

Ogale, S.B.

1992-01-01

This paper describes the use of pulsed excimer laser ablation technique for deposition of high quality superconductor thin films on different substrate materials such as Y stabilized ZrO 2 , SrTiO 3 , LiNbO 3 , Silicon and Stainless Steels, and dopant incorporation during the film depositions. Processing of deposited films using ion and laser beams for realisation of device features are presented. 28 refs., 16 figs

Laser techniques for spectroscopy of core-excited atomic levels

Science.gov (United States)

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

1982-01-01

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

Fermi Surface and Band Structure of (Ca,La)FeAs2 Superconductor from Angle-Resolved Photoemission Spectroscopy

International Nuclear Information System (INIS)

Liu Xu; Liu De-Fa; Zhao Lin; Guo Qi; Mu Qing-Ge; Chen Dong-Yun; Shen Bing; Yi He-Mian; Huang Jian-Wei; He Jun-Feng; Peng Ying-Ying; Liu Yan; He Shao-Long; Liu Guo-Dong; Dong Xiao-Li; Zhang Jun; Ren Zhi-An; Zhou Xing-Jiang; Chen Chuang-Tian; Xu Zu-Yan

2013-01-01

The (Ca,R)FeAs 2 (R=La, Pr, etc.) superconductors with a signature of superconductivity transition above 40 K possess a new kind of block layers that consist of zig-zag As chains. We report the electronic structure of the new (Ca,La)FeAs 2 superconductor investigated by both band structure calculations and high resolution angle-resolved photoemission spectroscopy measurements. Band structure calculations indicate that there are four hole-like bands around the zone center Γ(0,0) and two electron-like bands near the zone corner M(π, π) in CaFeAs 2 . In our angle-resolved photoemission measurements on (Ca 0.9 La 0.1 )FeAs 2 , we have observed three hole-like bands around the Γ point and one electron-like Fermi surface near the M(π, π) point. These results provide important information to compare and contrast with the electronic structure of other iron-based compounds in understanding the superconductivity mechanism in the iron-based superconductors. (express letter)

Atomic spectroscopy with diode lasers

International Nuclear Information System (INIS)

Tino, G.M.

1994-01-01

Some applications of semiconductor diode lasers in atomic spectroscopy are discussed by describing different experiments performed with lasers emitting in the visible and in the near-infrared region. I illustrate the results obtained in the investigation of near-infrared transitions of atomic oxygen and of the visible intercombination line of strontium. I also describe how two offset-frequency-locked diode lasers can be used to excite velocity selective Raman transitions in Cs. I discuss the spectral resolution, the accuracy of frequency measurements, and the detection sensitivity achievable with diode lasers. (orig.)

Laser spectroscopy probes the nucleus

International Nuclear Information System (INIS)

Griffith, J.; Billowes, J.

1998-01-01

Extremely sensitive optical measurements are shedding new light on the shape and size of nuclei, and the properties of nuclear matter far from stability. Of the 7000 or so isotopes known to nuclear physicists, less than 270 are stable. In general isotopes become more and more unstable as we move away from the so-called valley of stability, and therefore become more difficult to study in experiments. The tests of the theory also become more demanding. Laser spectroscopy is one of the techniques that is helping to explore the properties of these isotopes and improve our understanding of the forces inside the nucleus. High-resolution laser spectroscopy of short-lived radioactive atoms now makes it possible to measure the nuclear charge radius of many elements, including many isotopes far from stability. The method can reveal fine details of the sizes, shapes and structures of nuclei. In addition, laser spectroscopy is making significant contributions to our understanding of the nuclear force in unstable nuclei with unusual, or extreme, proton-neutron ratios. In this article the authors discuss the latest advances in studying heavy nuclei. (author)

Laser Spectroscopy : XII International Conference

CERN Document Server

Allegrini, Maria; Sasso, Antonio

1996-01-01

This text includes all the recent advances in the field of laser spectroscopy. Major results span from the control of matter by electromagnetic fields (trapping and coding) to high precision measurements on simple atomic systems and to quantum optics with single atoms. It includes a report of the Bose-Einstein condensation achieved by laser-cooling of rubidium atoms. Achievements in the technology of tunable sources, in particular of miniaturized solid state devices, are also reported. Most recent advances in molecular spectroscopy are illustrated with emphasis on "cooled" spectra, clusters and high accuracy frequency references. Topics such as atomic interferometry and microcavity quantum optics are also covered.

High-resolution in-source laser spectroscopy in perpendicular geometry

Energy Technology Data Exchange (ETDEWEB)

Heinke, R., E-mail: reinhard.heinke@uni-mainz.de; Kron, T. [Universität Mainz, Institut für Physik (Germany); Raeder, S. [Helmholtz-Institut Mainz (Germany); Reich, T.; Schönberg, P. [Universität Mainz, Institut für Kernchemie (Germany); Trümper, M.; Weichhold, C.; Wendt, K. [Universität Mainz, Institut für Physik (Germany)

2017-11-15

Operation of the novel laser ion source unit LIST (Laser Ion Source and Trap), operating at the on-line radioactive ion beam facility ISOLDE at CERN allowed for the production of ultra-pure beams of exotic isotopes far-off stability as well as direct isobar-free laser spectroscopy, giving access to the study of atomic and nuclear properties of so far inaccessible nuclides. We present a specific upgrade and adaption of the LIST targeted for high resolution spectroscopy with a Doppler-reduced perpendicular atom - laser beam geometry. With this PI-LIST (Perpendicularly Illuminated Laser Ion Source and Trap) setup, experimental linewidths below 100 MHz could be demonstrated in optical laser spectroscopy off-line, applying a pulsed injection-locked high repetition rate Ti:sapphire laser. A dual repeller configuration ensured highest suppression of isobaric interferences and almost background-free measurements on small samples in the order of 10{sup 11} atoms.

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.

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.

Time-resolved and doppler-reduced laser spectroscopy on atoms

International Nuclear Information System (INIS)

Bergstroem, H.

1991-10-01

Radiative lifetimes have been studied in neutral boron, carbon, silicon and strontium, in singly ionized gadolinium and tantalum and in molecular carbon monoxide and C 2 . The time-resolved techniques were based either on pulsed lasers or pulse-modulated CW lasers. Several techniques have been utilized for the production of free atoms and ions such as evaporation into an atomic beam, sputtering in hollow cathodes and laser-produced plasmas. Hyperfine interactions in boron, copper and strontium have been examined using quantum beat spectroscopy, saturation spectroscopy and collimated atomic beam spectroscopy. Measurement techniques based on effusive hollow cathodes as well as laser produced plasmas in atomic physics have been developed. Investigations on laser produced plasmas using two colour beam deflection tomography for determination of electron densities have been performed. Finally, new possibilities for view-time-expansion in light-in-flight holography using mode-locked CW lasers have been demonstrated. (au)

Electromagnetic properties of metals and superconductors

International Nuclear Information System (INIS)

Sinha, K.P.

1977-01-01

Part 1: Metals. 1. Introduction. 1.1. Normal and anomalous skin effects. 2. Helicons and magneto-plasma waves. 3. Helicon-phonon interaction. 3.1. Magneto-plasma (Alfven) waves. 4. Cyclotron waves. 5. Spin waves in electron system. Part 2: Superconductors. 6. Introduction. 6.1. Response to weak electromagnetic fields. 7. Effect of strong radiation field on superconductors. 8. Laser-induced non-equilibrium state in superconductors. 9. Possibility of photon-induced electron pairing - one-boson processes. 10. Possibility of photon-induced electron pairing -two-boson processes. (author)

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.

Tunneling spectroscopy on grain boundary junctions in electron-doped high-temperature superconductors

International Nuclear Information System (INIS)

Welter, B.

2007-01-01

Some methods are developed anf presented, by means of which from experimental tunnel spectra, especially on symmetric SIS contacts, informations about the properties of electrodes and tunnel barriers can be obtained. Especially a procedure for the numerical unfolding of symmetric SIS spectra is proposed. Furthermore a series of models is summarized, which can explain the linear background conductivity observed in many spectra on high-temperature superconductors. The results of resistance measurements on film bridges are presented. Especially different methods for the determination of H c2 (T) respectively H c2 (0) are presented and applied to the experimental data. Finally the results of the tunnel-spectroscopy measurements are shown

Time-resolved laser spectroscopy in the UV/VUV spectral region

International Nuclear Information System (INIS)

Bengtsson, J.

1992-01-01

Radiative lifetimes ranging from 3 to 500 ns were measured on various states of Ag, N, Se, Te and As, by recording the fluorescence light decay after excitation by a laser pulse. Ag was supplied by a collimated atomic beam while Se, Te and As were contained in quartz cells. Pulsed laser radiation, with a wavelength down to 185 nm, was generated by different set-ups, using Nd-YAG pumped dye lasers combined with non-linear crystals and Raman shifting. Short laser pulses were produced by a nitrogen laser or a distributed feedback dye laser. Two-photon processes and stepwise excitation were used to populate high-lying levels. Depletion spectroscopy, quantum-beat spectroscopy and optical double resonance spectroscopy were also performed

Laser excitation spectroscopy of uranium

International Nuclear Information System (INIS)

Solarz, R.W.

1976-01-01

Laser excitation spectroscopy, recently applied to uranium enrichment research at LLL, has produced a wealth of new and vitally needed information about the uranium atom and its excited states. Among the data amassed were a large number of cross sections, almost a hundred radiative lifetimes, and many level assignments. Rydberg states, never before observed in uranium or any of the actinides, have been measured and cataloged. This work puts a firm experimental base under laser isotope separation, and permits a choice of the laser frequencies most appropriate for practical uranium enrichment

In situ TEM Raman spectroscopy and laser-based materials modification

Energy Technology Data Exchange (ETDEWEB)

Allen, F.I., E-mail: fiallen@lbl.gov [Department of Materials Science and Engineering, University of California, Berkeley, CA 94720 (United States); National Center for Electron Microscopy, Molecular Foundry, Lawrence Berkeley National Laboratory, Berkeley, CA 94720 (United States); Kim, E. [Department of Mechanical Engineering, University of California, Berkeley, CA 94720 (United States); Andresen, N.C. [Engineering Division, Lawrence Berkeley National Laboratory, Berkeley, CA 94720 (United States); Grigoropoulos, C.P. [Department of Mechanical Engineering, University of California, Berkeley, CA 94720 (United States); Minor, A.M., E-mail: aminor@lbl.gov [Department of Materials Science and Engineering, University of California, Berkeley, CA 94720 (United States); National Center for Electron Microscopy, Molecular Foundry, Lawrence Berkeley National Laboratory, Berkeley, CA 94720 (United States)

2017-07-15

We present a modular assembly that enables both in situ Raman spectroscopy and laser-based materials processing to be performed in a transmission electron microscope. The system comprises a lensed Raman probe mounted inside the microscope column in the specimen plane and a custom specimen holder with a vacuum feedthrough for a tapered optical fiber. The Raman probe incorporates both excitation and collection optics, and localized laser processing is performed using pulsed laser light delivered to the specimen via the tapered optical fiber. Precise positioning of the fiber is achieved using a nanomanipulation stage in combination with simultaneous electron-beam imaging of the tip-to-sample distance. Materials modification is monitored in real time by transmission electron microscopy. First results obtained using the assembly are presented for in situ pulsed laser ablation of MoS{sub 2} combined with Raman spectroscopy, complimented by electron-beam diffraction and electron energy-loss spectroscopy. - Highlights: • Raman spectroscopy and laser-based materials processing in a TEM are demonstrated. • A lensed Raman probe is mounted in the sample chamber for close approach. • Localized laser processing is achieved using a tapered optical fiber. • Raman spectroscopy and pulsed laser ablation of MoS{sub 2} are performed in situ.

In situ TEM Raman spectroscopy and laser-based materials modification

International Nuclear Information System (INIS)

Allen, F.I.; Kim, E.; Andresen, N.C.; Grigoropoulos, C.P.; Minor, A.M.

2017-01-01

We present a modular assembly that enables both in situ Raman spectroscopy and laser-based materials processing to be performed in a transmission electron microscope. The system comprises a lensed Raman probe mounted inside the microscope column in the specimen plane and a custom specimen holder with a vacuum feedthrough for a tapered optical fiber. The Raman probe incorporates both excitation and collection optics, and localized laser processing is performed using pulsed laser light delivered to the specimen via the tapered optical fiber. Precise positioning of the fiber is achieved using a nanomanipulation stage in combination with simultaneous electron-beam imaging of the tip-to-sample distance. Materials modification is monitored in real time by transmission electron microscopy. First results obtained using the assembly are presented for in situ pulsed laser ablation of MoS_2 combined with Raman spectroscopy, complimented by electron-beam diffraction and electron energy-loss spectroscopy. - Highlights: • Raman spectroscopy and laser-based materials processing in a TEM are demonstrated. • A lensed Raman probe is mounted in the sample chamber for close approach. • Localized laser processing is achieved using a tapered optical fiber. • Raman spectroscopy and pulsed laser ablation of MoS_2 are performed in situ.

Investigation of Diode Pumped Alkali Laser Atmospheric Transmission Using Tunable Diode Laser Absorption Spectroscopy

Science.gov (United States)

2012-09-01

Optics Letters, 28(23):2336–2338, 2003. 48. Lavan, M. “High Energy Laser Systems for Short Range Defense”. Acta Physica Polonica -Series A General Physics...able diode laser spectrometer for the remote sensing of vehicle emissions”. Spec- trochimica Acta Part A: Molecular and Biomolecular Spectroscopy, 60...P. “A review of recent advances in semiconductor laser based gas mon- itors”. Spectrochimica Acta Part A: Molecular and Biomolecular Spectroscopy, 54

Molecular Laser Spectroscopy as a Tool for Gas Analysis Applications

Directory of Open Access Journals (Sweden)

Javis Anyangwe Nwaboh

2011-01-01

Full Text Available We have used the traceable infrared laser spectrometric amount fraction measurement (TILSAM method to perform absolute concentration measurements of molecular species using three laser spectroscopic techniques. We report results performed by tunable diode laser absorption spectroscopy (TDLAS, quantum cascade laser absorption spectroscopy (QCLAS, and cavity ring down spectroscopy (CRDS, all based on the TILSAM methodology. The measured results of the different spectroscopic techniques are in agreement with respective gravimetric values, showing that the TILSAM method is feasible with all different techniques. We emphasize the data quality objectives given by traceability issues and uncertainty analyses.

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.

Optical spectroscopy using gas-phase femtosecond laser filamentation.

Science.gov (United States)

Odhner, Johanan; Levis, Robert

2014-01-01

Femtosecond laser filamentation occurs as a dynamic balance between the self-focusing and plasma defocusing of a laser pulse to produce ultrashort radiation as brief as a few optical cycles. This unique source has many properties that make it attractive as a nonlinear optical tool for spectroscopy, such as propagation at high intensities over extended distances, self-shortening, white-light generation, and the formation of an underdense plasma. The plasma channel that constitutes a single filament and whose position in space can be controlled by its input parameters can span meters-long distances, whereas multifilamentation of a laser beam can be sustained up to hundreds of meters in the atmosphere. In this review, we briefly summarize the current understanding and use of laser filaments for spectroscopic investigations of molecules. A theoretical framework of filamentation is presented, along with recent experimental evidence supporting the established understanding of filamentation. Investigations carried out on vibrational and rotational spectroscopy, filament-induced breakdown, fluorescence spectroscopy, and backward lasing are discussed.

Evidence of a spin resonance mode in the iron-based superconductor Ba(0.6)K(0.4)Fe2As2 from scanning tunneling spectroscopy.

Science.gov (United States)

Shan, Lei; Gong, Jing; Wang, Yong-Lei; Shen, Bing; Hou, Xingyuan; Ren, Cong; Li, Chunhong; Yang, Huan; Wen, Hai-Hu; Li, Shiliang; Dai, Pengcheng

2012-06-01

We used high-resolution scanning tunneling spectroscopy to study the hole-doped iron pnictide superconductor Ba(0.6)K(0.4)Fe(2)As(2) (T(c)=38 K). Features of a bosonic excitation (mode) are observed in the measured quasiparticle density of states. The bosonic features are intimately associated with the superconducting order parameter and have a mode energy of ~14 meV, similar to the spin resonance measured by inelastic neutron scattering. These results indicate a strong electron-spin excitation coupling in iron pnictide superconductors, similar to that in high-T(c) copper oxide superconductors.

Laser Spectroscopy for Atmospheric and Environmental Sensing

Directory of Open Access Journals (Sweden)

Solomon Bililign

2009-12-01

Full Text Available Lasers and laser spectroscopic techniques have been extensively used in several applications since their advent, and the subject has been reviewed extensively in the last several decades. This review is focused on three areas of laser spectroscopic applications in atmospheric and environmental sensing; namely laser-induced fluorescence (LIF, cavity ring-down spectroscopy (CRDS, and photoluminescence (PL techniques used in the detection of solids, liquids, aerosols, trace gases, and volatile organic compounds (VOCs.

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

Principles of laser spectroscopy and quantum optics

CERN Document Server

Berman, Paul R

2011-01-01

Principles of Laser Spectroscopy and Quantum Optics is an essential textbook for graduate students studying the interaction of optical fields with atoms. It also serves as an ideal reference text for researchers working in the fields of laser spectroscopy and quantum optics. The book provides a rigorous introduction to the prototypical problems of radiation fields interacting with two- and three-level atomic systems. It examines the interaction of radiation with both atomic vapors and condensed matter systems, the density matrix and the Bloch vector, and applications involving linear absorptio

Coincident photoelectron spectroscopy on superconductors; Koinzidente Photoelektronenspektroskopie an Supraleitern

Energy Technology Data Exchange (ETDEWEB)

Voss, Stefan

2011-07-01

Aim of the performed experiments of this thesis was to attempt to detect Cooper pairs as carriers of the superconducting current directly by means of the photoelectric effect. The method of the coincident photoelectron spectroscopy aims thereby at the detection of two coherently emitted electrons by the interaction with a photon. Because electrostatic analyzers typically cover only a very small spatial angle, which goes along with very low coincidence rates, in connection with this thesis a time-of-flight projection system has been developed, which maps nearly the whole spatial angle on a position-resolving detector. The pulsed light source in form of special synchrotron radiation necessary for the measurement has been adjusted so weak, that only single photons could arrive at the sample. Spectroscoped were beside test measurements on silver layers both a lead monocrystal as representative of the classical BCS superconductors and monocrystalline Bi{sub 2}Sr{sub 2}CaCu{sub 2}O{sub 8} from the family of the high-temperature superconductors. With excitation energies up to 40 eV could be shown that sufficiently smooth and clean surfaces in the superconducting phase exhibit within the resolving power of about 0.5 eV no recognizable differences in comparison to the normally conducting phase. Beside these studies furthermore the simple photoemission at the different samples and especially in the case of the lead crystal is treated, because here no comparable results are known. Thereby the whole momentum space is discussed and the Fermi surface established as three-dimensional model, by means of which the measurement results are discussed. in the theoretical descriptions different models for the Cooper-pair production are presented, whereby to the momentum exchange with the crystal a special role is attributed, because this can only occur in direct excitations via discrete lattice vectors.

Laser spectroscopy on a ''shoestring''

International Nuclear Information System (INIS)

Camparo, J.C.; Klimcak, C.M.

1983-01-01

The advent of tunable lasers has had a profound influence on both experimental and theoretical physics. Unfortunately, since these laser systems are typically hazardous and expensive, the physics student at the undergraduate or first-year graduate level has no real familiarity with their application in modern physics; and thus cannot fully appreciate their significance. Tunable single mode laser diodes, however, may offer a remedy to this situation. To demonstrate their applicability, we have designed a relatively simple and inexpensive experiment of laser diode spectroscopy in an atomic beam which illustrates the effect of hyperfine structure and the isotope shift in the rubidium D 1 transition (5 2 S/sub 1/2/-5 2 P/sub 1/2/). Furthermore, this experiment demonstrates the possibility of investigating basic physics without major expenditures for laser systems and laboratory facilities

Laser spectroscopy of gas confined in nanoporous materials

OpenAIRE

Svensson, Tomas; Shen, Zhijian

2010-01-01

We show that high-resolution laser spectroscopy can probe surface interactions of gas confined in nanocavities of porous materials. We report on strong line broadening and unfamiliar line shapes due to tight confinement, as well as signal enhancement due to multiple photon scattering. This new domain of laser spectroscopy constitute a challenge for the theory of collisions and spectroscopic line shapes, and open for new ways of analyzing porous materials and processes taking place therein.

Magnetic field modulated microwave spectroscopy across phase transitions and the search for new superconductors

International Nuclear Information System (INIS)

Ramírez, Juan Gabriel; Basaran, Ali C; De la Venta, J; Pereiro, Juan; Schuller, Ivan K

2014-01-01

This article introduces magnetic field modulated microwave spectroscopy (MFMMS) as a unique and high-sensitivity technique for use in the search for new superconductors. MFMMS measures reflected microwave power as a function of temperature. The modulation induced by the external ac magnetic field enables the use of phase locked detection with the consequent sensitivity enhancement. The MFMMS signal across several prototypical structural, magnetic, and electronic transitions is investigated. A literature review on microwave absorption across superconducting transitions is included. We show that MFMMS can be used to detect superconducting transitions selectively with very high sensitivity. (report on progress)

Laser spectroscopy on organic molecules.

Science.gov (United States)

Imasaka, T

1996-06-01

Various laser spectrometric methods have been developed until now. Especially, laser fluorometry is most sensitive and is frequently combined with a separation technique such as capillary electrophoresis. For non-fluorescent compounds, photothermal spectrometry may be used instead. A diode laser is potentially useful for practical trace analysis, because of its low cost and long-term trouble-free operation. On the other hand, monochromaticity of the laser is essential in high-resolution spectrometry, e.g. in low temperature spectrometry providing a very sharp spectral feature. Closely-related compounds such as isomers can easily be differentiated, and information for assignment is obtained from the spectrum. Multiphoton ionization mass spectrometry is useful for soft ionization, providing additional information concerned with molecular weight and chemical structure. A short laser pulse with a sufficient energy is suitable for rapid heating of the solid surface. A matrix-assisted laser desorption/ion-ization technique is recently employed for introduction of a large biological molecule into a vacuum for mass analysis. In the future, laser spectrometry will be developed by a combination with state-of-the-art laser technology. In the 21st century, new laser spectrometry will be developed, which may be based on revolutionary ideas or unexpected discoveries. Such studies will open new frontiers in analytical laser spectroscopy.

Optical spectroscopy of laser-produced plasmas for standoff isotopic analysis

Science.gov (United States)

Harilal, S. S.; Brumfield, B. E.; LaHaye, N. L.; Hartig, K. C.; Phillips, M. C.

2018-06-01

Rapid, in-field, and non-contact isotopic analysis of solid materials is extremely important to a large number of applications, such as nuclear nonproliferation monitoring and forensics, geochemistry, archaeology, and biochemistry. Presently, isotopic measurements for these and many other fields are performed in laboratory settings. Rapid, in-field, and non-contact isotopic analysis of solid material is possible with optical spectroscopy tools when combined with laser ablation. Laser ablation generates a transient vapor of any solid material when a powerful laser interacts with a sample of interest. Analysis of atoms, ions, and molecules in a laser-produced plasma using optical spectroscopy tools can provide isotopic information with the advantages of real-time analysis, standoff capability, and no sample preparation requirement. Both emission and absorption spectroscopy methods can be used for isotopic analysis of solid materials. However, applying optical spectroscopy to the measurement of isotope ratios from solid materials presents numerous challenges. Isotope shifts arise primarily due to variation in nuclear charge distribution caused by different numbers of neutrons, but the small proportional nuclear mass differences between nuclei of various isotopes lead to correspondingly small differences in optical transition wavelengths. Along with this, various line broadening mechanisms in laser-produced plasmas and instrumental broadening generated by the detection system are technical challenges frequently encountered with emission-based optical diagnostics. These challenges can be overcome by measuring the isotope shifts associated with the vibronic emission bands from molecules or by using the techniques of laser-based absorption/fluorescence spectroscopy to marginalize the effect of instrumental broadening. Absorption and fluorescence spectroscopy probe the ground state atoms existing in the plasma when it is cooler, which inherently provides narrower

Laser induced breakdown spectroscopy in water | Boudjemai ...

African Journals Online (AJOL)

Sparks were generated in water by the focused beam of a Q-switched Nd:YAG laser Na and Cu aqueous solutions exhibited fluorescence signal on the decaying edge of plasma emission at their respective characteristic resonance lines. Potential of the laser plasma spectroscopy for in-situ pollution monitoring in natural ...

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...

Laser spectroscopy and its applications

International Nuclear Information System (INIS)

Radziemski, L.J.; Solarz, R.W.; Paisner, J.A.

1987-01-01

Laser spectroscopy has applications in diverse fields ranging from combustion studies and trace-sample detection to biological research. At the same time, it has also contributed greatly to the discovery of hundreds of new lasers. This symbiotic relationship has promoted an especially rapid expansion of the field. This book provides a review of the subject. It includes, for example, chapters on laser isotope separation techniques, enabling scientists to compare their relative advantages and drawbacks. This volume also gives numerous tables that summarize important features of lasers, experiments, and parameters for quick reference. In addition, it presents diagrams for visualizing rotational molecular energy levels of high J in order to enhance our understanding of molecular motions and their relationship to molecular energy levels. Offering insights into how experts think this technology will improve, it considers research and development in each topic discussed

Tunnelling spectroscopy of BaFe{sub 2}As{sub 2}/Au/PbIn thin film junctions

Energy Technology Data Exchange (ETDEWEB)

Doering, Sebastian; Schmidt, Stefan; Schmidl, Frank; Tympel, Volker; Grosse, Veit; Seidel, Paul [Institut fuer Festkoerperphysik, Friedrich-Schiller-Universitaet Jena (Germany); Haindl, Silvia; Iida, Kazumasa; Kurth, Fritz; Holzapfel, Bernhard [IFW Dresden, Institut fuer Metallische Werkstoffe, Dresden (Germany)

2011-07-01

Tunnelling spectroscopy is an important tool to investigate the properties of iron-based superconductors. In contrast to commonly used point contact Andreev reflection (PCAR) technique, we fabricated hybrid superconductor / normal metal / superconductor (SNS) thin film structures, with tunable barrier thickness and area. For the base electrode we use Ba(Fe{sub 0.9}Co{sub 0.1}){sub 2}As{sub 2} thin films, produced via pulsed laser deposition (PLD). A gold layer was sputtered to form the barrier, while the counter electrode material is the conventional superconductor PbIn with a T{sub c} of 7.2 K. For temperatures below 7.2 K the spectrum shows a subharmonic gap structure (SGS), described by an extended model of Octavio, Tinkham, Blonder and Klapwijk (OTBK), while at higher temperatures the SGS vanishes and an SN-like behaviour can be observed.

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...

Diode-Laser Induced Fluorescence Spectroscopy of an Optically Thick Plasma in Combination with Laser Absorption Spectroscopy

Directory of Open Access Journals (Sweden)

S. Nomura

2013-01-01

Full Text Available Distortion of laser-induced fluorescence profiles attributable to optical absorption and saturation broadening was corrected in combination with laser absorption spectroscopy in argon plasma flow. At high probe-laser intensity, saturated absorption profiles were measured to correct probe-laser absorption. At low laser intensity, nonsaturated absorption profiles were measured to correct fluorescence reabsorption. Saturation broadening at the measurement point was corrected using a ratio of saturated to non-saturated broadening. Observed LIF broadening and corresponding translational temperature without correction were, respectively, 2.20±0.05 GHz and 2510±100 K and corrected broadening and temperature were, respectively, 1.96±0.07 GHz and 1990±150 K. Although this correction is applicable only at the center of symmetry, the deduced temperature agreed well with that obtained by LAS with Abel inversion.

Spectroscopy of beryllium-like nitrogen ions by laser-induced recombination

International Nuclear Information System (INIS)

Uhlenberg, G.

1996-04-01

The following topics were dealt with: Rydberg spectroscopy of beryllium-like nitrogen (N 3+ ) by laser-induced recombination, transition enrgies, Rydberg level shift, configuration interaction, laser intensity effect, laser band width

High resolution UV spectroscopy and laser-focused nanofabrication

NARCIS (Netherlands)

Myszkiewicz, G.

2005-01-01

This thesis combines two at first glance different techniques: High Resolution Laser Induced Fluorescence Spectroscopy (LIF) of small aromatic molecules and Laser Focusing of atoms for Nanofabrication. The thesis starts with the introduction to the high resolution LIF technique of small aromatic

Spectroscopy of laser-produced plasmas

Indian Academy of Sciences (India)

It is a well-known fact that laser-induced breakdown spectroscopy (LIBS) has emerged as one of the best analytical techniques for multi-elemental compositional analysis of samples. We report assembling and optimization of LIBS set up using high resolution and broad-range echelle spectrograph coupled to an intensified ...

Towards laser spectroscopy of antihydrogen

NARCIS (Netherlands)

Walz, J.; Pahl, A.; Eikema, K.S.E.; Hansch, T.W.

2000-01-01

The development of the first continuous coherent source at 121.56 nm is described. Radiation at this wavelength of Lyman-alpha can be used for laser-cooling of antihydrogen on the strong 1S-2P transition. It also opens up a possibility for precision spectroscopy that requires just a few antihydrogen

Emission spectroscopy analysis during Nopal cladodes dethorning by laser ablation

Science.gov (United States)

Peña-Díaz, M.; Ponce, L.; Arronte, M.; Flores, T.

2007-04-01

Optical emission spectroscopy of the pulsed laser ablation of spines and glochids from Opuntia (Nopal) cladodes was performed. Nopal cladodes were irradiated with Nd:YAG free-running laser pulses on their body, glochids and spines. Emission spectroscopy analyses in the 350-1000 nm region of the laser induced plasma were made. Plasma plume evolution characterization, theoretical calculations of plasma plume temperature and experiments varying the processing atmosphere showed that the process is dominated by a thermally activated combustion reaction which increases the dethorning process efficiency. Therefore, appropriate laser pulse energy for minimal damage of cladodes body and in the area beneath glochids and spines can be obtained.

Emission spectroscopy analysis during Nopal cladodes dethorning by laser ablation

Energy Technology Data Exchange (ETDEWEB)

Pena-Diaz, M; Ponce, L; Arronte, M; Flores, T [Laboratorio TecnologIa Laser, CICATA-IPN, Unidad Altamira, Carretera Tampico-Puerto Ind. Altamira, 89600, TAMPS (Mexico)

2007-04-15

Optical emission spectroscopy of the pulsed laser ablation of spines and glochids from Opuntia (Nopal) cladodes was performed. Nopal cladodes were irradiated with Nd:YAG free-running laser pulses on their body, glochids and spines. Emission spectroscopy analyses in the 350-1000 nm region of the laser induced plasma were made. Plasma plume evolution characterization, theoretical calculations of plasma plume temperature and experiments varying the processing atmosphere showed that the process is dominated by a thermally activated combustion reaction which increases the dethorning process efficiency. Therefore, appropriate laser pulse energy for minimal damage of cladodes body and in the area beneath glochids and spines can be obtained.

Emission spectroscopy analysis during Nopal cladodes dethorning by laser ablation

International Nuclear Information System (INIS)

Pena-Diaz, M; Ponce, L; Arronte, M; Flores, T

2007-01-01

Optical emission spectroscopy of the pulsed laser ablation of spines and glochids from Opuntia (Nopal) cladodes was performed. Nopal cladodes were irradiated with Nd:YAG free-running laser pulses on their body, glochids and spines. Emission spectroscopy analyses in the 350-1000 nm region of the laser induced plasma were made. Plasma plume evolution characterization, theoretical calculations of plasma plume temperature and experiments varying the processing atmosphere showed that the process is dominated by a thermally activated combustion reaction which increases the dethorning process efficiency. Therefore, appropriate laser pulse energy for minimal damage of cladodes body and in the area beneath glochids and spines can be obtained

Development of pulsed UV lasers and their application in laser spectroscopy

International Nuclear Information System (INIS)

De la Rosa, M I; Perez, C; Gruetzmacher, K; GarcIa, D; Bustillo, A

2011-01-01

The application of two-photon laser spectroscopy to plasma diagnostics requires tuneable UV-laser spectrometers providing: some mJ pulse energy at ns time scale with spectral quality close to Fourier Transform Limit, good pulse to pulse reproducibility and tuning linearity. We report about two different systems, a first laser specially optimized for the radiation at 243 nm, which is required for the 1S-2S two photon transition of atomic hydrogen, and a second one generating 205 nm suited for the transition 1S - 3S/3D.

Utilizing atomic force spectroscopy to test an alternative electrodynamic theory of superconductors

Energy Technology Data Exchange (ETDEWEB)

Peronio, Angelo; Giessibl, Franz J. [Institut fuer Experimentelle und Angewandte Physik, Universitaet Regensburg, D-93040 Regensburg (Germany)

2016-07-01

In the traditional theoretical description of superconductivity, a static electric field cannot penetrate a superconductor, since screening occurs like in a normal metal. This can be traced back to the fact that the London equations, the phenomenological equations describing the electrodynamics of superconductors, are derived within the Coulomb gauge. J. E. Hirsch proposes to use the Lorenz gauge instead [2], deriving a consistent solution where the electric field penetrates the superconductor up to the London penetration depth. We report on initial experiments to test Hirsch's hypothesis, performed with a combined STM/AFM qPlus sensor equipped with a superconducting tip. If a superconductor screens electric fields differently from a normal metal, the electrostatic interaction between tip and sample should change when the tip becomes superconductive.

A Simple LIBS (Laser-Induced Breakdown Spectroscopy) Laboratory Experiment to Introduce Undergraduates to Calibration Functions and Atomic Spectroscopy

Science.gov (United States)

Chinni, Rosemarie C.

2012-01-01

This laboratory experiment introduces students to a different type of atomic spectroscopy: laser-induced breakdown spectroscopy (LIBS). LIBS uses a laser-generated spark to excite the sample; once excited, the elemental emission is spectrally resolved and detected. The students use LIBS to analyze a series of standard synthetic silicate samples…

Filament-induced remote surface ablation for long range laser-induced breakdown spectroscopy operation

International Nuclear Information System (INIS)

Rohwetter, Ph.; Stelmaszczyk, K.; Woeste, L.; Ackermann, R.; Mejean, G.; Salmon, E.; Kasparian, J.; Yu, J.; Wolf, J.-P.

2005-01-01

We demonstrate laser induced ablation and plasma line emission from a metallic target at distances up to 180 m from the laser, using filaments (self-guided propagation structures ∼ 100 μm in diameter and ∼ 5 x 10 13 W/cm 2 in intensity) appearing as femtosecond and terawatt laser pulses propagating in air. The remarkable property of filaments to propagate over a long distance independently of the diffraction limit opens the frontier to long range operation of the laser-induced breakdown spectroscopy technique. We call this special configuration of remote laser-induced breakdown spectroscopy 'remote filament-induced breakdown spectroscopy'. Our results show main features of filament-induced ablation on the surface of a metallic sample and associated plasma emission. Our experimental data allow us to estimate requirements for the detection system needed for kilometer-range remote filament-induced breakdown spectroscopy experiment

Prospects for laser-induced breakdown spectroscopy for biomedical applications: a review.

Science.gov (United States)

Singh, Vivek Kumar; Rai, Awadhesh Kumar

2011-09-01

We review the different spectroscopic techniques including the most recent laser-induced breakdown spectroscopy (LIBS) for the characterization of materials in any phase (solid, liquid or gas) including biological materials. A brief history of the laser and its application in bioscience is presented. The development of LIBS, its working principle and its instrumentation (different parts of the experimental set up) are briefly summarized. The generation of laser-induced plasma and detection of light emitted from this plasma are also discussed. The merit and demerits of LIBS are discussed in comparison with other conventional analytical techniques. The work done using the laser in the biomedical field is also summarized. The analysis of different tissues, mineral analysis in different organs of the human body, characterization of different types of stone formed in the human body, analysis of biological aerosols using the LIBS technique are also summarized. The unique abilities of LIBS including detection of molecular species and calibration-free LIBS are compared with those of other conventional techniques including atomic absorption spectroscopy, inductively coupled plasma atomic emission spectroscopy and mass spectroscopy, and X-ray fluorescence.

Frequency-comb-assisted broadband precision spectroscopy with cascaded diode lasers

DEFF Research Database (Denmark)

Liu, Junqiu; Brasch, Victor; Pfeiffer, Martin H. P.

2016-01-01

Frequency-comb-assisted diode laser spectroscopy, employing both the accuracy of an optical frequency comb and the broad wavelength tuning range of a tunable diode laser, has been widely used in many applications. In this Letter, we present a novel method using cascaded frequency agile diode lasers......, which allows us to extend the measurement bandwidth to 37.4 THz (1355-1630 nm) at megahertz resolution with scanning speeds above 1 THz/s. It is demonstrated as a useful tool to characterize a broadband spectrum for molecular spectroscopy, and in particular it enables us to characterize the dispersion...

Mid-infrared quantum cascade laser spectroscopy probing of the ...

Indian Academy of Sciences (India)

Aparajeo Chattopadhyay

2018-05-07

May 7, 2018 ... cm3 molecule. −1 s. −1 ... Quantum cascade laser; time-resolved mid-infrared spectroscopy; transient absorption; peroxy radicals .... peak of the laser emission profile. .... cal with O2 is a termolecular reaction (Eq. 3) and the.

Picometer-resolution dual-comb spectroscopy with a free-running fiber laser.

Science.gov (United States)

Zhao, Xin; Hu, Guoqing; Zhao, Bofeng; Li, Cui; Pan, Yingling; Liu, Ya; Yasui, Takeshi; Zheng, Zheng

2016-09-19

Dual-comb spectroscopy holds the promise as real-time, high-resolution spectroscopy tools. However, in its conventional schemes, the stringent requirement on the coherence between two lasers requires sophisticated control systems. By replacing control electronics with an all-optical dual-comb lasing scheme, a simplified dual-comb spectroscopy scheme is demonstrated using one dual-wavelength, passively mode-locked fiber laser. Pulses with a intracavity-dispersion-determined repetition-frequency difference are shown to have good mutual coherence and stability. Capability to resolve the comb teeth and a picometer-wide optical spectral resolution are demonstrated using a simple data acquisition system. Energy-efficient, free-running fiber lasers with a small comb-tooth-spacing could enable low-cost dual-comb systems.

XPS, AES and laser raman spectroscopy: A fingerprint for a materials surface characterisation

International Nuclear Information System (INIS)

Zaidi Embong

2011-01-01

This review briefly describes some of the techniques available for analysing surfaces and illustrates their usefulness with a few examples such as a metal and alloy. In particular, Auger electron spectroscopy (AES), X-ray photoelectron spectroscopy (XPS) and laser Raman spectroscopy are all described as advanced surface analytical techniques. In analysing a surface, AES and XPS would normally be considered first, with AES being applied where high spatial resolution is required and XPS where chemical state information is needed. Laser Raman spectroscopy is useful for determining molecular bonding. A combination of XPS, AES and Laser Raman spectroscopy can give quantitative analysis from the top few atomic layers with a lateral spatial resolution of < 10 nm. (author)

Part I: $\\beta$-delayed fission, laser spectroscopy and shape-coexistence studies with astatine beams; Part II: Delineating the island of deformation in the light gold isotopes by means of laser spectroscopy

CERN Document Server

Andreyev, Andrei

2013-01-01

Part I: $\\beta$-delayed fission, laser spectroscopy and shape-coexistence studies with astatine beams; Part II: Delineating the island of deformation in the light gold isotopes by means of laser spectroscopy

Comb-Resolved Dual-Comb Spectroscopy Stabilized by Free-Running Continuous-Wave Lasers

Science.gov (United States)

Kuse, Naoya; Ozawa, Akira; Kobayashi, Yohei

2012-11-01

We demonstrate dual-comb spectroscopy with relatively phase-locked two frequency combs, instead of frequency combs firmly fixed to the absolute frequency references. By stabilizing two beat frequencies between two mode-locked lasers at different wavelengths observed via free-running continuous-wave (CW) lasers, two combs are tightly phase locked to each other. The frequency noise of the CW lasers barely affects the performance of dual-comb spectroscopy because of the extremely fast common-mode noise rejection. Transform-limited comb-resolved dual-comb spectroscopy with a 6 Hz radio frequency linewidth is demonstrated by the use of Yb-fiber oscillators.

Elemental profiling of laser cladded multilayer coatings by laser induced breakdown spectroscopy and energy dispersive X-ray spectroscopy

Science.gov (United States)

Lednev, V. N.; Sdvizhenskii, P. A.; Filippov, M. N.; Grishin, M. Ya.; Filichkina, V. A.; Stavertiy, A. Ya.; Tretyakov, R. S.; Bunkin, A. F.; Pershin, S. M.

2017-09-01

Multilayer tungsten carbide wear resistant coatings were analyzed by laser induced breakdown spectroscopy (LIBS) and energy dispersive X-ray (EDX) spectroscopy. Coaxial laser cladding technique was utilized to produce tungsten carbide coating deposited on low alloy steel substrate with additional inconel 625 interlayer. EDX and LIBS techniques were used for elemental profiling of major components (Ni, W, C, Fe, etc.) in the coating. A good correlation between EDX and LIBS data was observed while LIBS provided additional information on light element distribution (carbon). A non-uniform distribution of tungsten carbide grains along coating depth was detected by both LIBS and EDX. In contrast, horizontal elemental profiling showed a uniform tungsten carbide particles distribution. Depth elemental profiling by layer-by-layer LIBS analysis was demonstrated to be an effective method for studying tungsten carbide grains distribution in wear resistant coating without any sample preparation.

Opportunities for sub-laser-cycle spectroscopy in condensed phase

International Nuclear Information System (INIS)

Ivanov, Misha; Smirnova, Olga

2013-01-01

Highlights: ► We discuss how sub-cycle attosecond spectroscopy can be extended from gas to condensed phase. ► We show that attosecond streaking measurements can be applied to bound electrons. ► We discuss time-resolving the formation of band structure in laser fields. - Abstract: To a large extent, progress of attosecond spectroscopy in the gas phase has been driven by designing approaches where time-resolution is not limited by the pulse duration. Instead, the time resolution comes from exploiting the sensitivity of electronic response to the oscillations of the electric field in the laser pulse and attosecond control over these oscillations. This paper discusses perspectives and opportunities for transporting the ideas of sub-cycle spectroscopy from gas to condensed phase

Probing multiband superconductivity by point-contact spectroscopy

International Nuclear Information System (INIS)

Daghero, D; Gonnelli, R S

2010-01-01

Point-contact spectroscopy was originally developed for the determination of the electron-phonon spectral function in normal metals. However, in the past 20 years it has become an important tool in the investigation of superconductors. As a matter of fact, point contacts between a normal metal and a superconductor can provide information on the amplitude and symmetry of the energy gap that, in the superconducting state, opens up at the Fermi level. In this paper we review the experimental and theoretical aspects of point-contact spectroscopy in superconductors, and we give an experimental survey of the most recent applications of this technique to anisotropic and multiband superconductors. (topical review)

Chirped laser dispersion spectroscopy using a directly modulated quantum cascade laser

International Nuclear Information System (INIS)

Hangauer, Andreas; Nikodem, Michal; Wysocki, Gerard; Spinner, Georg

2013-01-01

Chirped laser dispersion spectroscopy (CLaDS) utilizing direct modulation of a quantum cascade laser (QCL) is presented. By controlling the laser bias nearly single- and dual-sideband CLaDS operation can be realized in an extremely simplified optical setup with no external optical modulators. Capability of direct single-sideband modulation is a unique feature of QCLs that exhibit a low linewidth enhancement factor. The developed analytical model shows excellent agreement with the experimental, directly modulated CLaDS spectra. This method overcomes major technical limitations of mid-infrared CLaDS systems by allowing significantly higher modulation frequencies and eliminating optical fringes introduced by external modulators

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

Fast gas spectroscopy using pulsed quantum cascade lasers

Science.gov (United States)

Beyer, T.; Braun, M.; Lambrecht, A.

2003-03-01

Laser spectroscopy has found many industrial applications, e.g., control of automotive exhaust and process monitoring. The midinfrared region is of special interest because it has stronger absorption lines compared to the near infrared (NIR). However, in the NIR high quality reliable laser sources, detectors, and passive optical components are available. A quantum cascade laser could change this situation if fundamental advantages can be exploited with compact and reliable systems. It will be shown that, using pulsed lasers and available fast detectors, lower residual sensitivity levels than in corresponding NIR systems can be achieved. The stability is sufficient for industrial applications.

Characterization of hard coatings produced by laser cladding using laser-induced breakdown spectroscopy technique

Energy Technology Data Exchange (ETDEWEB)

Varela, J.A.; Amado, J.M.; Tobar, M.J.; Mateo, M.P.; Yañez, A.; Nicolas, G., E-mail: gines@udc.es

2015-05-01

Highlights: • Chemical mapping and profiling by laser-induced breakdown spectroscopy (LIBS) of coatings produced by laser cladding. • Production of laser clads using tungsten carbide (WC) and nickel based matrix (NiCrBSi) powders. • Calibration by LIBS of hardfacing alloys with different WC concentrations. - Abstract: Protective coatings with a high abrasive wear resistance can be obtained from powders by laser cladding technique, in order to extend the service life of some industrial components. In this work, laser clad layers of self-fluxing NiCrBSi alloy powder mixed with WC powder have been produced on stainless steel substrates of austenitic type (AISI 304) in a first step and then chemically characterized by laser-induced breakdown spectroscopy (LIBS) technique. With the suitable laser processing parameters (mainly output power, beam scan speed and flow rate) and powders mixture proportions between WC ceramics and NiCrBSi alloys, dense pore free layers have been obtained on single tracks and on large areas with overlapped tracks. The results achieved by LIBS technique and applied for the first time to the analysis of laser clads provided the chemical composition of the tungsten carbides in metal alloy matrix. Different measurement modes (multiple point analyses, depth profiles and chemical maps) have been employed, demonstrating the usefulness of LIBS technique for the characterization of laser clads based on hardfacing alloys. The behavior of hardness can be explained by LIBS maps which evidenced the partial dilution of some WC spheres in the coating.

Next generation laser-based standoff spectroscopy techniques for Mars exploration.

Science.gov (United States)

Gasda, Patrick J; Acosta-Maeda, Tayro E; Lucey, Paul G; Misra, Anupam K; Sharma, Shiv K; Taylor, G Jeffrey

2015-01-01

In the recent Mars 2020 Rover Science Definition Team Report, the National Aeronautics and Space Administration (NASA) has sought the capability to detect and identify elements, minerals, and most importantly, biosignatures, at fine scales for the preparation of a retrievable cache of samples. The current Mars rover, the Mars Science Laboratory Curiosity, has a remote laser-induced breakdown spectroscopy (LIBS) instrument, a type of quantitative elemental analysis, called the Chemistry Camera (ChemCam) that has shown that laser-induced spectroscopy instruments are not only feasible for space exploration, but are reliable and complementary to traditional elemental analysis instruments such as the Alpha Particle X-Ray Spectrometer. The superb track record of ChemCam has paved the way for other laser-induced spectroscopy instruments, such as Raman and fluorescence spectroscopy. We have developed a prototype remote LIBS-Raman-fluorescence instrument, Q-switched laser-induced time-resolved spectroscopy (QuaLITy), which is approximately 70 000 times more efficient at recording signals than a commercially available LIBS instrument. The increase in detection limits and sensitivity is due to our development of a directly coupled system, the use of an intensified charge-coupled device image detector, and a pulsed laser that allows for time-resolved measurements. We compare the LIBS capabilities of our system with an Ocean Optics spectrometer instrument at 7 m and 5 m distance. An increase in signal-to-noise ratio of at least an order of magnitude allows for greater quantitative analysis of the elements in a LIBS spectrum with 200-300 μm spatial resolution at 7 m, a Raman instrument capable of 1 mm spatial resolution at 3 m, and bioorganic fluorescence detection at longer distances. Thus, the new QuaLITy instrument fulfills all of the NASA expectations for proposed instruments.

High-Resolution Spectroscopy of Laser Ablation Plumes Using Laser-Induced Fluorescence

Energy Technology Data Exchange (ETDEWEB)

Harilal, Sivanandan S.; LaHaye, Nicole L.; Phillips, Mark C.

2017-02-06

We used a CW laser as a narrow-band (~50kHz) tunable LIF excitation source to probe absorption from selected atomic transitions (Al, U etc. ) in a ns laser ablation plume. A comparison of fluorescence signal with respect to emission spectroscopy show significant increase in the magnitude and persistence from selected Al and U transitions in a LIBS plume. The high spectral resolution provided by the LIF measurement allows peaks to be easily separated even if they overlap in the emission spectra.

Hyper-Ramsey spectroscopy with probe-laser-intensity fluctuations

Science.gov (United States)

Beloy, K.

2018-03-01

We examine the influence of probe-laser-intensity fluctuations on hyper-Ramsey spectroscopy. We assume, as is appropriate for relevant cases of interest, that the probe-laser intensity I determines both the Rabi frequency (∝√{I } ) and the frequency shift to the atomic transition (∝I ) during probe-laser interactions with the atom. The spectroscopic signal depends on these two quantities that covary with fluctuations in the probe-laser intensity. Introducing a simple model for the fluctuations, we find that the signature robustness of the hyper-Ramsey method can be compromised. Taking the Yb+ electric octupole clock transition as an example, we quantify the clock error under different levels of probe-laser-intensity fluctuations.

[Hyperfine structure and isotope shift measurements of short lived elements by laser spectroscopy

International Nuclear Information System (INIS)

Schuessler, H.A.

1986-01-01

The aim of this research is to determine nuclear moments and charge distributions of short-lived isotopes produced both on-line and off-line to a nuclear facility. These measurements give detailed information on the nuclear force and are used to test current nuclear models. The small amounts of nuclei which can be produced off stability constitute the challenge in these experiments. Presently mainly neutron-rich isotopes are being studied by three ultrasensitive high-resolution laser techniques. These are collinear fast ion-beam laser spectroscopy, stored-ion laser spectroscopy and fluorescence spectroscopy. 5 figs

Laser spectroscopy of molecules: State-of-the-art and possible trends

International Nuclear Information System (INIS)

Demtroeder, W.

1990-01-01

A review is given on different techniques in laser spectroscopy of atoms and molecules, which allow high spectral resolution and a very high detection sensitivity of small samples. Analytical applications of the techniques are discussed for basic scientific research, as well as for environmental problems and technical processes. Possible trends of laser spectroscopy, in particular with respect to applications in biology and medicine are shortly outlined. (orig.)

DFB laser diodes for sensing applications using photoacoustic spectroscopy

International Nuclear Information System (INIS)

Koeth, J; Fischer, M; Legge, M; Seufert, J; Roessner, K; Groninga, H

2010-01-01

We present typical device characteristics of novel DFB laser diodes which are employed in various sensing applications including high resolution photoacoustic spectroscopy. The laser diodes discussed are based on a genuine fabrication technology which allows for the production of ultra stable devices within a broad spectral range from 760 nm up to 3000 nm wavelength. The devices exhibit narrow linewidths down to <1 MHz which makes them ideally suited for all photoacoustic sensing applications where a high spectral purity is required. As an example we will focus on a typical medical application where these diodes are used for breath analysis using photoacoustic spectroscopy.

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

Science.gov (United States)

Negnevitsky, V; Turner, L D

2013-02-11

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

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

Oxygen measurement by multimode diode lasers employing gas correlation spectroscopy.

Science.gov (United States)

Lou, Xiutao; Somesfalean, Gabriel; Chen, Bin; Zhang, Zhiguo

2009-02-10

Multimode diode laser (MDL)-based correlation spectroscopy (COSPEC) was used to measure oxygen in ambient air, thereby employing a diode laser (DL) having an emission spectrum that overlaps the oxygen absorption lines of the A band. A sensitivity of 700 ppm m was achieved with good accuracy (2%) and linearity (R(2)=0.999). For comparison, measurements of ambient oxygen were also performed by tunable DL absorption spectroscopy (TDLAS) technique employing a vertical cavity surface emitting laser. We demonstrate that, despite slightly degraded sensitivity, the MDL-based COSPEC-based oxygen sensor has the advantages of high stability, low cost, ease-of-use, and relaxed requirements in component selection and instrument buildup compared with the TDLAS-based instrument.

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).

Trace gas detection by laser intracavity photothermal spectroscopy

International Nuclear Information System (INIS)

Fung, K.H.; Lin, H.h.

1986-01-01

A novel laser intracavity photothermal detector is described. In this scheme, sample absorption of the pump laser power takes place within the cavity of a probe He-Ne laser causing modulation in the gain and in turn the output power. Comparison of this intracavity detector with two other photothermal techniques, namely, phase fluctuation optical heterodyne spectroscopy and thermal beam deflection, is made in terms of practicality and sensitivity. For in situ measurements, sensitivity of 0.5 x 10 -7 cm -1 for a probe length of 3 cm has been achieved

Proceedings of the sixth symposium on laser spectroscopy

International Nuclear Information System (INIS)

1998-11-01

This proceedings contains articles of the 6th symposium on laser spectroscopy and this symposium is held on Nov. 3-4, 1998 by KAERI. Laser spectroscopy is one of the most important areas in optical science and engineering and we discussed about the recently developed subjects in detail during the this symposium. This proceedings is composed of two major parts. One is the invitational lectures and the other is the research papers. This have a very important and very valuable lecture by Dr. William Phillips who is the 1997 Nobel Laureate in Physics. His special lecture was very wonderful and fruitful. And we have a number of invited speakers from several advanced countries. Their talks are the highlights of this symposium. (Cho, G. S.)

On the electronic structure of high Tc superconductors

International Nuclear Information System (INIS)

Fink, J.; Nuecker, N.; Romberg, H.; Alexander, M.; Knupfer, M.; Mante, J.; Claessen, R.; Buslaps, T.; Harm, S.; Manzke, R.; Skibowski, M.

1992-01-01

Studies of the electronic structure of high-T c superconductors and related compounds by high-energy spectroscopies are reviewed. In particular, we report on investigations by electron energy-loss, angle-resolved photoemission, and inverse angle-resolved photoemission spectroscopy. Information on the symmetry and the character of states close to the Fermi level has been obtained. 25 refs., 8 figs

Laser spectroscopy of gallium isotopes using the ISCOOL RFQ cooler

CERN Multimedia

Blaum, K; Kowalska, M; Ware, T; Procter, T J

2007-01-01

We propose to study the radioisotopes of gallium (Z=31) by collinear laser spectroscopy using the ISCOOL RFQ ion cooler. The proposed measurements on $^{62-83}$Ga will span both neutron-deficient and neutron-rich isotopes. Of key interest is the suggested development of a proton-skin in the neutron-deficient isotopes. The isotope shifts measured by laser spectroscopy will be uniquely sensitive to this feature. The measurements will also provide a wealth of new information on the gallium nuclear spins, static moments and nuclear charge radii.

Laser spectroscopy applied to environmental, ecological, food safety, and biomedical research.

Science.gov (United States)

Svanberg, Sune; Zhao, Guangyu; Zhang, Hao; Huang, Jing; Lian, Ming; Li, Tianqi; Zhu, Shiming; Li, Yiyun; Duan, Zheng; Lin, Huiying; Svanberg, Katarina

2016-03-21

Laser spectroscopy provides many possibilities for multi-disciplinary applications in environmental monitoring, in the ecological field, for food safety investigations, and in biomedicine. The paper gives several examples of the power of multi-disciplinary applications of laser spectroscopy as pursued in our research group. The studies utilize mostly similar and widely applicable spectroscopic approaches. Air pollution and vegetation monitoring by lidar techniques, as well as agricultural pest insect monitoring and classification by elastic scattering and fluorescence spectroscopy are described. Biomedical aspects include food safety applications and medical diagnostics of sinusitis and otitis, with strong connection to the abatement of antibiotics resistance development.

Combination of laser-induced breakdown spectroscopy and Raman spectroscopy for multivariate classification of bacteria

Czech Academy of Sciences Publication Activity Database

Procházka, D.; Mazura, M.; Samek, Ota; Rebrošová, K.; Pořízka, P.; Klus, J.; Procházková, P.; Novotný, J.; Novotný, K.; Kaiser, J.

2018-01-01

Roč. 139 (2018), s. 6-12 ISSN 0584-8547 R&D Projects: GA ČR(CZ) GA15-20645S; GA ČR(CZ) GA16-12477S; GA MŠk(CZ) LO1212; GA MŠk ED0017/01/01 Institutional support: RVO:68081731 Keywords : laser-induced breakdown spectroscopy * Raman spectroscopy * chemometrics * bacteria Impact factor: 3.241, year: 2016

A versatile interaction chamber for laser-based spectroscopic applications, with the emphasis on Laser-Induced Breakdown Spectroscopy

International Nuclear Information System (INIS)

Novotný, J.; Brada, M.; Petrilak, M.; Prochazka, D.; Novotný, K.; Hrdička, A.; Kaiser, J.

2014-01-01

The technical note describes the interaction chamber developed particularly for the laser spectroscopy technique applications, such as Laser-Induced Breakdown Spectroscopy (LIBS), Raman Spectroscopy and Laser-Induced Fluorescence. The chamber was designed in order to provide advanced possibilities for the research in mentioned fields and to facilitate routine research procedures. Parameters and the main benefits of the chamber are described, such as the built-in module for automatic 2D chemical mapping and the possibility to set different ambient gas conditions (pressure value and gas type). Together with the chamber description, selected LIBS application examples benefiting from chamber properties are described. - Highlights: • Development of the interaction chamber for LIBS applications • Example of automated chemical mapping of lead in a chalcopyrite sample • Example of LIBS measurement of fluorine in underpressure • Overview of chamber benefits

Optimizing laser crater enhanced Raman scattering spectroscopy

Science.gov (United States)

Lednev, V. N.; Sdvizhenskii, P. A.; Grishin, M. Ya.; Fedorov, A. N.; Khokhlova, O. V.; Oshurko, V. B.; Pershin, S. M.

2018-05-01

The laser crater enhanced Raman scattering (LCERS) spectroscopy technique has been systematically studied for chosen sampling strategy and influence of powder material properties on spectra intensity enhancement. The same nanosecond pulsed solid state Nd:YAG laser (532 nm, 10 ns, 0.1-1.5 mJ/pulse) was used for laser crater production and Raman scattering experiments for L-aspartic acid powder. Increased sampling area inside crater cavity is the key factor for Raman signal improvement for the LCERS technique, thus Raman signal enhancement was studied as a function of numerous experimental parameters including lens-to-sample distance, wavelength (532 and 1064 nm) and laser pulse energy utilized for crater production. Combining laser pulses of 1064 and 532 nm wavelengths for crater ablation was shown to be an effective way for additional LCERS signal improvement. Powder material properties (particle size distribution, powder compactness) were demonstrated to affect LCERS measurements with better results achieved for smaller particles and lower compactness.

Optimizing laser crater enhanced Raman spectroscopy.

Science.gov (United States)

Lednev, V N; Sdvizhenskii, P A; Grishin, M Ya; Filichkina, V A; Shchegolikhin, A N; Pershin, S M

2018-03-20

Raman signal enhancement by laser crater production was systematically studied for 785 nm continuous wave laser pumping. Laser craters were produced in L-aspartic acid powder by a nanosecond pulsed solid state neodymium-doped yttrium aluminum garnet laser (532 nm, 8 ns, 1 mJ/pulse), while Raman spectra were then acquired by using a commercial spectrometer with 785 nm laser beam pumping. The Raman signal enhancement effect was studied in terms of the number of ablating pulses used, the lens-to-sample distance, and the crater-center-laser-spot offset. The influence of the experiment parameters on Raman signal enhancement was studied for different powder materials. Maximum Raman signal enhancement reached 11 fold for loose powders but decreased twice for pressed tablets. Raman signal enhancement was demonstrated for several diverse powder materials like gypsum or ammonium nitrate with better results achieved for the samples tending to give narrow and deep craters upon the laser ablation stage. Alternative ways of cavity production (steel needle tapping and hole drilling) were compared with the laser cratering technique in terms of Raman signal enhancement. Drilling was found to give the poorest enhancement of the Raman signal, while both laser ablation and steel needle tapping provided comparable results. Here, we have demonstrated for the first time, to the best of our knowledge, that a Raman signal can be enhanced 10 fold with the aid of simple cavity production by steel needle tapping in rough highly reflective materials. Though laser crater enhancement Raman spectroscopy requires an additional pulsed laser, this technique is more appropriate for automatization compared to the needle tapping approach.

Laser induced fluorescence spectroscopy for FTU

International Nuclear Information System (INIS)

Hughes, T.P.

1995-07-01

Laser induced fluorescence spectroscopy (LIFS) is based on the absorption of a short pulse of tuned laser light by a group of atoms and the observation of the resulting fluorescence radiation from the excited state. Because the excitation is resonant it is very efficient, and the fluorescence can be many times brighter than the normal spontaneous emission, so low number densities of the selected atoms can be detected and measured. Good spatial resolution can be achieved by using a narrow laser beam. If the laser is sufficiently monochromatic, and it can be tuned over the absorption line profile of the selected atoms, information can also be obtained about the velocities of the atoms from the Doppler effect which can broaden and shift the line. In this report two topics are examined in detail. The first is the effect of high laser irradiance, which can cause 'power broadening' of the apparent absorption line profile. The second is the effect of the high magnetic field in FTU. Detailed calculations are given for LIFS of neutral iron and molybdenum atoms, including the Zeeman effect, and the implementation of LIFS for these atoms on FTU is discussed

Laser-Induced Breakdown Spectroscopy Infrared Emission From Inorganic and Organic Substances

National Research Council Canada - National Science Library

Yang, C.S; Brown, E; Hommerich, U; Trivedi, S. B; Snyder, A. P; Samuels, A. C

2006-01-01

Laser-induced breakdown spectroscopy (LIBS) has been established as a powerful method for identifying trace elemental contaminants by analyzing the atomic spectral emission lines that result subsequent to plasmas generated by laser power...

Remote imaging laser-induced breakdown spectroscopy and laser-induced fluorescence spectroscopy using nanosecond pulses from a mobile lidar system.

Science.gov (United States)

Grönlund, Rasmus; Lundqvist, Mats; Svanberg, Sune

2006-08-01

A mobile lidar system was used in remote imaging laser-induced breakdown spectroscopy (LIBS) and laser-induced fluorescence (LIF) experiments. Also, computer-controlled remote ablation of a chosen area was demonstrated, relevant to cleaning of cultural heritage items. Nanosecond frequency-tripled Nd:YAG laser pulses at 355 nm were employed in experiments with a stand-off distance of 60 meters using pulse energies of up to 170 mJ. By coaxial transmission and common folding of the transmission and reception optical paths using a large computer-controlled mirror, full elemental imaging capability was achieved on composite targets. Different spectral identification algorithms were compared in producing thematic data based on plasma or fluorescence light.

UV laser-induced fluorescence spectroscopy and laser Doppler flowmetry in the diagnostics of alopecia

Science.gov (United States)

Skomorokha, Diana P.; Pigoreva, Yulia N.; Salmin, Vladimir V.

2016-04-01

Development of optical biopsy methods has a great interest for medical diagnostics. In clinical and experimental studies it is very important to analyze blood circulation quickly and accurately, thereby laser Doppler flowmetry (LDF) is widely used. UV laser-induced fluorescence spectroscopy (UV LIFS) is express highly sensitive and widely-spread method with no destructive impact, high excitation selectivity and the possibility to use in highly scattering media. The goal of this work was to assess a correlation of UV laser-induced fluorescence spectroscopy and laser Doppler flowmetry parameters, and a possibility to identify or to differentiate various types of pathological changes in tissues according to their autofluorescence spectra. Three groups of patients with diffuse (symptomatic) alopecia, androgenic alopecia, and focal alopecia have been tested. Each groups consisted of not less than 20 persons. The measurements have been done in the parietal and occipital regions of the sculls. We used the original automated spectrofluorimeter to record autofluorescence spectra, and standard laser Doppler flowmeter BLF-21 (Transonic Systems, Inc., USA) to analyze the basal levels of blood circulation. Our results show that UV LIFS accurately distinguishes the zones with different types of alopecia. We found high correlation of the basal levels of blood circulation and the integrated intensity of autofluorescence in the affected tissue.

Laser photothermal spectroscopy of light-induced absorption

Energy Technology Data Exchange (ETDEWEB)

Skvortsov, L A [Institute of Cryptography, Communications and Informatics, Moscow (Russian Federation)

2013-01-31

Basic methods of laser photothermal spectroscopy, which are used to study photoinduced absorption in various media, are briefly considered. Comparative analysis of these methods is performed and the latest results obtained in this field are discussed. Different schemes and examples of their practical implementation are considered. (review)

Laser-induced breakdown spectroscopy theory and applications

CERN Document Server

Perini, Umberto

2014-01-01

This book deals with the Laser-Induced Breakdown Spectroscopy (LIBS), a widely used atomic emission spectroscopy technique for elemental analysis of materials. It is based on the use of a high-power, short pulse laser excitation. The book is divided into two main sections: the first one concerning theoretical aspects of the technique, the second one describing the state of the art in applications of the technique in different scientific/technological areas. Numerous examples of state of the art applications provide the readers an almost complete scenario of the LIBS technique. The LIBS theoretical aspects are reviewed. The book helps the readers who are less familiar with the technique to understand the basic principles. Numerous examples of state of the art applications give an almost complete scenario of the LIBS technique potentiality. These examples of applications may have a strong impact on future industrial utilization. The authors made important contributions to the development of this field.

Proceedings of the seventh symposium on laser spectroscopy

International Nuclear Information System (INIS)

1999-01-01

This proceedings contains articles of the 7th symposium on laser spectroscopy and this symposium is held on Nov. 5-6, 1999 by KAERI. Both the laser and laser beams are critically used in many most precise measurements in science and technology. We discussed about the recently developed subjects in detail during the this symposium. This proceedings is composed of two major parts. One is the invitational lectures and the other is the research papers. And we have a number of invited speakers from several advanced countries. Their talks are the highlights of this symposium. (Cho, G. S.)

Proceedings of the eighth symposium on laser spectroscopy

International Nuclear Information System (INIS)

2000-01-01

This proceedings contains articles of the 8th symposium on laser spectroscopy and this symposium is held on Nov. 3-4, 2000 by KAERI. Both the laser and laser beams are critically used in many most precise measurements in science and technology. We discussed about the recently developed subjects in detail during the this symposium. This proceedings is composed of two major parts. One is the invitational lectures and the other is the research papers. And we have a number of invited speakers from several advanced countries. Their talks are the highlights of this symposium. (Yi, J. H.)

[Study on physical deviation factors on laser induced breakdown spectroscopy measurement].

Science.gov (United States)

Wan, Xiong; Wang, Peng; Wang, Qi; Zhang, Qing; Zhang, Zhi-Min; Zhang, Hua-Ming

2013-10-01

In order to eliminate the deviation between the measured LIBS spectral line and the standard LIBS spectral line, and improve the accuracy of elements measurement, a research of physical deviation factors in laser induced breakdown spectroscopy technology was proposed. Under the same experimental conditions, the relationship of ablated hole effect and spectral wavelength was tested, the Stark broadening data of Mg plasma laser induced breakdown spectroscopy with sampling time-delay from 1.00 to 3.00 micros was also studied, thus the physical deviation influences such as ablated hole effect and Stark broadening could be obtained while collecting the spectrum. The results and the method of the research and analysis can also be applied to other laser induced breakdown spectroscopy experiment system, which is of great significance to improve the accuracy of LIBS elements measuring and is also important to the research on the optimum sampling time-delay of LIBS.

Precision Spectroscopy, Diode Lasers, and Optical Frequency Measurement Technology

Science.gov (United States)

Hollberg, Leo (Editor); Fox, Richard (Editor); Waltman, Steve (Editor); Robinson, Hugh

1998-01-01

This compilation is a selected set of reprints from the Optical Frequency Measurement Group of the Time and Frequency Division of the National Institute of Standards and Technology, and consists of work published between 1987 and 1997. The two main programs represented here are (1) development of tunable diode-laser technology for scientific applications and precision measurements, and (2) research toward the goal of realizing optical-frequency measurements and synthesis. The papers are organized chronologically in five, somewhat arbitrarily chosen categories: Diode Laser Technology, Tunable Laser Systems, Laser Spectroscopy, Optical Synthesis and Extended Wavelength Coverage, and Multi-Photon Interactions and Optical Coherences.

Developments towards in-gas-jet laser spectroscopy studies of actinium isotopes at LISOL

International Nuclear Information System (INIS)

Raeder, S.; Bastin, B.; Block, M.; Creemers, P.; Delahaye, P.; Ferrer, R.; Fléchard, X.; Franchoo, S.; Ghys, L.; Gaffney, L.P.; Granados, C.; Heinke, R.; Hijazi, L.

2016-01-01

To study exotic nuclides at the borders of stability with laser ionization and spectroscopy techniques, highest efficiencies in combination with a high spectral resolution are required. These usually opposing requirements are reconciled by applying the in-gas-laser ionization and spectroscopy (IGLIS) technique in the supersonic gas jet produced by a de Laval nozzle installed at the exit of the stopping gas cell. Carrying out laser ionization in the low-temperature and low density supersonic gas jet eliminates pressure broadening, which will significantly improve the spectral resolution. This article presents the required modifications at the Leuven Isotope Separator On-Line (LISOL) facility that are needed for the first on-line studies of in-gas-jet laser spectroscopy. Different geometries for the gas outlet and extraction ion guides have been tested for their performance regarding the acceptance of laser ionized species as well as for their differential pumping capacities. The specifications and performance of the temporarily installed high repetition rate laser system, including a narrow bandwidth injection-locked Ti:sapphire laser, are discussed and first preliminary results on neutron-deficient actinium isotopes are presented indicating the high capability of this novel technique.

Developments towards in-gas-jet laser spectroscopy studies of actinium isotopes at LISOL

Energy Technology Data Exchange (ETDEWEB)

Raeder, S., E-mail: s.raeder@gsi.de [KU Leuven, Instituut voor Kern- en Stralingsfysica, Celestijnenlaan 200D, B-3001 Leuven (Belgium); Helmholtz-Institut Mainz, 55128 Mainz (Germany); GSI Helmholtzzentrum für Schwerionenforschung GmbH, Planckstraße 1, 64291 Darmstadt (Germany); Bastin, B. [GANIL, CEA/DSM-CNRS/IN2P3, B.P. 55027, 14076 Caen (France); Block, M. [Helmholtz-Institut Mainz, 55128 Mainz (Germany); GSI Helmholtzzentrum für Schwerionenforschung GmbH, Planckstraße 1, 64291 Darmstadt (Germany); Institut für Kernchemie, Johannes Gutenberg Universität, 55128 Mainz (Germany); Creemers, P. [KU Leuven, Instituut voor Kern- en Stralingsfysica, Celestijnenlaan 200D, B-3001 Leuven (Belgium); Delahaye, P. [GANIL, CEA/DSM-CNRS/IN2P3, B.P. 55027, 14076 Caen (France); Ferrer, R. [KU Leuven, Instituut voor Kern- en Stralingsfysica, Celestijnenlaan 200D, B-3001 Leuven (Belgium); Fléchard, X. [LPC Caen, ENSICAEN, Université de Caen, CNRS/IN2P3, Caen (France); Franchoo, S. [Institute de Physique Nucléaire (IPN) d’Orsay, 91406 Orsay, Cedex (France); Ghys, L. [KU Leuven, Instituut voor Kern- en Stralingsfysica, Celestijnenlaan 200D, B-3001 Leuven (Belgium); SCK-CEN, Belgian Nuclear Research Center, Boeretang 200, 2400 Mol (Belgium); Gaffney, L.P.; Granados, C. [KU Leuven, Instituut voor Kern- en Stralingsfysica, Celestijnenlaan 200D, B-3001 Leuven (Belgium); Heinke, R. [Institut für Physik, Johannes Gutenberg Universität, 55128 Mainz (Germany); Hijazi, L. [GANIL, CEA/DSM-CNRS/IN2P3, B.P. 55027, 14076 Caen (France); and others

2016-06-01

To study exotic nuclides at the borders of stability with laser ionization and spectroscopy techniques, highest efficiencies in combination with a high spectral resolution are required. These usually opposing requirements are reconciled by applying the in-gas-laser ionization and spectroscopy (IGLIS) technique in the supersonic gas jet produced by a de Laval nozzle installed at the exit of the stopping gas cell. Carrying out laser ionization in the low-temperature and low density supersonic gas jet eliminates pressure broadening, which will significantly improve the spectral resolution. This article presents the required modifications at the Leuven Isotope Separator On-Line (LISOL) facility that are needed for the first on-line studies of in-gas-jet laser spectroscopy. Different geometries for the gas outlet and extraction ion guides have been tested for their performance regarding the acceptance of laser ionized species as well as for their differential pumping capacities. The specifications and performance of the temporarily installed high repetition rate laser system, including a narrow bandwidth injection-locked Ti:sapphire laser, are discussed and first preliminary results on neutron-deficient actinium isotopes are presented indicating the high capability of this novel technique.

Aerosol distribution measurements by laser - Doppler - spectroscopy

International Nuclear Information System (INIS)

Baldassari, J.

1977-01-01

Laser-Doppler-Spectroscopy is used to study particle size distribution, especially sodium aerosols, in the presence of uncondensable gases. Theoretical basis are given, and an experimental technique is described. First theoretical results show reasonably good agreement with experimental data available; this method seems to be a promising one. (author)

Overview of applications of Laser-Induced Breakdown Spectroscopy (LIBS)

International Nuclear Information System (INIS)

Cremers, D.A.

1987-01-01

Laser-induced breakdown spectroscopy (LIBS) is a method of performing elemental analyses of solids, liquids, and gases using the microplasma produced by a focused laser pulse. Because the microplasma is formed by optical radiation, LIBS has some important advantages compared to conventional laboratory based analytical methods. Three applications are discussed which use the LIBS method. 6 refs., 8 figs., 2 tabs

Blue Diode Laser Absorption Spectroscopy of Pulsed Magnetron Discharge

Czech Academy of Sciences Publication Activity Database

Olejníček, Jiří; Do, H.T.; Hubička, Zdeněk; Hippler, R.; Jastrabík, Lubomír

2006-01-01

Roč. 45, 10B (2006), s. 8090-8094 ISSN 0021-4922 R&D Projects: GA AV ČR 1QS100100563; GA ČR GA202/05/2242 Institutional research plan: CEZ:AV0Z10100521; CEZ:AV0Z10100520 Keywords : laser absorption spectroscopy * pulsed magnetron * sputtering parameters Subject RIV: BH - Optics, Masers, Lasers Impact factor: 1.222, year: 2006

Recent trends in spin-resolved photoelectron spectroscopy

Science.gov (United States)

Okuda, Taichi

2017-12-01

Since the discovery of the Rashba effect on crystal surfaces and also the discovery of topological insulators, spin- and angle-resolved photoelectron spectroscopy (SARPES) has become more and more important, as the technique can measure directly the electronic band structure of materials with spin resolution. In the same way that the discovery of high-Tc superconductors promoted the development of high-resolution angle-resolved photoelectron spectroscopy, the discovery of this new class of materials has stimulated the development of new SARPES apparatus with new functions and higher resolution, such as spin vector analysis, ten times higher energy and angular resolution than conventional SARPES, multichannel spin detection, and so on. In addition, the utilization of vacuum ultra violet lasers also opens a pathway to the realization of novel SARPES measurements. In this review, such recent trends in SARPES techniques and measurements will be overviewed.

Using laser absorption spectroscopy to monitor composition and physical properties of metal vapors

International Nuclear Information System (INIS)

Berzins, L.V.

1993-01-01

The Atomic Vapor Laser Isotope Separation (AVLIS) program has been using laser absorption spectroscopy to monitor vapor densities for over 15 years. Laser absorption spectroscopy has proven itself to be an accurate and reliable method to monitor both density and composition. During this time the diagnostic has moved from a research tool toward a robust component of a process control system. The hardware used for this diagnostic is discussed elsewhere at this symposium. This paper describes how the laser absorption spectroscopy diagnostic is used as a component of a process control system as well as supplying detailed measurements on vapor densities, composition, flow velocity, internal and kinetic temperatures, and constituent distributions. Examples will be drawn from the uranium AVLIS program. In addition potential applications such as composition control in the production of metal matrix composites or aircraft alloys will be discussed

Evidence of multiband superconductivity in the quaternary borocarbide superconductor YNi2B2C using directional point-contact spectroscopy

International Nuclear Information System (INIS)

Raychaudhuri, Pratap; Sheet, Goutam; Mukhopadhyay, Sourin; Takeya, H.

2007-01-01

In this paper, we review our recent investigations on the gap anisotropy of the quaternary borocarbide superconductor YNi 2 B 2 C using directional point-contact spectroscopy. Through a detailed study of the temperature and magnetic field dependence of the superconducting energy gaps we show that the gap anisotropy in this material originates from electrons on different Fermi sheets having very different Fermi velocities. The gap anisotropy in this material is therefore well explained through a multiband scenario where electrons in different k-directions have very different electron-phonon coupling strength

Laser spectroscopy of radioactive beams

International Nuclear Information System (INIS)

Otten, E.W.

1983-01-01

The problem of using the laser spectroscopy in investigations radioactive beams is considered. The main attention is payed to the isotope shift of nuclear charge radii delta 2 >. The general trend of delta 2 > is discussed. Predictions for delta>r 2 < in the framework of the droplet model are given. It is noted that two parameter interpretation of the isotope shift based on the droplet model works the better, the further the distance spans and the clearer the nuclear structure is

Laser spectroscopy and dynamics of transient species

Energy Technology Data Exchange (ETDEWEB)

Clouthier, D.J. [Univ. of Kentucky, Lexington (United States)

1993-12-01

The goal of this program is to study the vibrational and electronic spectra and excited state dynamics of a number of transient sulfur and oxygen species. A variety of supersonic jet techniques, as well as high resolution FT-IR and intracavity dye laser spectroscopy, have been applied to these studies.

Laser spectroscopy of exotic RI atoms in superfluid helium-OROCHI experiment

International Nuclear Information System (INIS)

Furukawa, T.; Matsuo, Y.; Hatakeyama, A.; Fujikake, K.; Matsuura, Y.; Kobayashi, T.; Shimoda, T.

2010-01-01

We have been developing a new laser spectroscopic technique 'OROCHI,' which is based on the combination of superfluid helium as a stopper of radioactive isotope (RI) beam and in-situ laser spectroscopy of RI atoms, for determining spins and moments of exotic RIs. By using this unique technique, it is feasible to measure nuclear spins and electromagnetic moments of extremely low yield RI (estimated as less than 1 pps). Recently, we have demonstrated that nuclear spins and moments are obtained from Zeeman and hyperfine splittings of stable Rb isotopes measured using this OROCHI technique. Details of this laser spectroscopy method in He II 'OROCHI' and the summary of our development are presented.

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

Validation studies on quick analysis of MOX fuel by combination of laser induced breakdown spectroscopy and ablation resonance absorption spectroscopy

International Nuclear Information System (INIS)

Wakaida, Ikuo; Akaoka, Katsuaki; Miyabe, Masabumi; Kato, Masaaki; Otobe, Haruyoshi; Ohoba, Hironori; Khumaeni, Ali

2014-01-01

Research and development of laser based quick analysis without chemical analysis and neutron measurement for next-generation Minor Actinide containing MOX fuel has been carried out, and the basic performances by using un-irradiated MOX fuel were demonstrated. The glove box had been re-constructed and specialized for laser spectroscopy, and the remote spectroscopy of MOX sample contained several concentrations of Pu was performed. In elemental analysis by Laser Induced Breakdown Spectroscopy (LIBS) with high resolution spectrometer, relative error of 2.9% at 30% Pu and the detection lower limit of 2500ppm in natural U oxide were demonstrated with the operation time of 5 min. In isotope ratio analysis by Ablation Resonance Absorption Spectroscopy, tunable semiconductor laser system was constructed, and the performances such as relative deviation less than 1% in the ratio of "2"4"0Pu/"2"3"9Pu and the sensitivity of 30-100ppm in natural U were also accomplished with laser operation time of 3 to 5min. As for an elemental analysis of the simulated liquid sample, ultra-thin laminate flow was experimented as LIBS target, and the sensitivity comparable to conventional ICP-AES was confirmed. Present study includes the result of the entrusted project by the Ministry of Education, Culture, Sports, Science and Technology of Japan (MEXT). (author)

Proximity Effect between Two Superconductors Spatially Resolved by Scanning Tunneling Spectroscopy

Directory of Open Access Journals (Sweden)

V. Cherkez

2014-03-01

Full Text Available We present a combined experimental and theoretical study of the proximity effect in an atomic-scale controlled junction between two different superconductors. Elaborated on a Si(111 surface, the junction comprises a Pb nanocrystal with an energy gap Δ_{1}=1.2  meV, connected to a crystalline atomic monolayer of lead with Δ_{2}=0.23  meV. Using in situ scanning tunneling spectroscopy, we probe the local density of states of this hybrid system both in space and in energy, at temperatures below and above the critical temperature of the superconducting monolayer. Direct and inverse proximity effects are revealed with high resolution. Our observations are precisely explained with the help of a self-consistent solution of the Usadel equations. In particular, our results demonstrate that in the vicinity of the Pb islands, the Pb monolayer locally develops a finite proximity-induced superconducting order parameter, well above its own bulk critical temperature. This leads to a giant proximity effect where the superconducting correlations penetrate inside the monolayer a distance much larger than in a nonsuperconducting metal.

Cavity-enhanced Raman spectroscopy with optical feedback cw diode lasers for gas phase analysis and spectroscopy.

Science.gov (United States)

Salter, Robert; Chu, Johnny; Hippler, Michael

2012-10-21

A variant of cavity-enhanced Raman spectroscopy (CERS) is introduced, in which diode laser radiation at 635 nm is coupled into an external linear optical cavity composed of two highly reflective mirrors. Using optical feedback stabilisation, build-up of circulating laser power by 3 orders of magnitude occurs. Strong Raman signals are collected in forward scattering geometry. Gas phase CERS spectra of H(2), air, CH(4) and benzene are recorded to demonstrate the potential for analytical applications and fundamental molecular studies. Noise equivalent limits of detection in the ppm by volume range (1 bar sample) can be achieved with excellent linearity with a 10 mW excitation laser, with sensitivity increasing with laser power and integration time. The apparatus can be operated with battery powered components and can thus be very compact and portable. Possible applications include safety monitoring of hydrogen gas levels, isotope tracer studies (e.g., (14)N/(15)N ratios), observing isotopomers of hydrogen (e.g., radioactive tritium), and simultaneous multi-component gas analysis. CERS has the potential to become a standard method for sensitive gas phase Raman spectroscopy.

High-speed photography of laser ablation plasmas from the high temperature superconductor YBa2Cu3O7-δ

International Nuclear Information System (INIS)

Scott, K.; Huntley, J.M.; Phillips, W.A.

1993-01-01

The luminous plume formed by laser ablation of the high-temperature superconductor YBa 2 Cu 3 O 7-δ has been investigated using high-speed framing photography. Variation of the background oxygen pressure was found to significantly influence the velocity distribution of the ablated species, leading in particular to shock wave formation and instabilities on the shock front at higher pressures. Spectral characteristics of the plume were studied using optical interference filters, and two distinct regions of emission were identified. (orig.)

Frequency modulation spectroscopy with a THz quantum-cascade laser.

Science.gov (United States)

Eichholz, R; Richter, H; Wienold, M; Schrottke, L; Hey, R; Grahn, H T; Hübers, H-W

2013-12-30

We report on a terahertz spectrometer for high-resolution molecular spectroscopy based on a quantum-cascade laser. High-frequency modulation (up to 50 MHz) of the laser driving current produces a simultaneous modulation of the frequency and amplitude of the laser output. The modulation generates sidebands, which are symmetrically positioned with respect to the laser carrier frequency. The molecular transition is probed by scanning the sidebands across it. In this way, the absorption and the dispersion caused by the molecular transition are measured. The signals are modeled by taking into account the simultaneous modulation of the frequency and amplitude of the laser emission. This allows for the determination of the strength of the frequency as well as amplitude modulation of the laser and of molecular parameters such as pressure broadening.

Laser Spectroscopy of Antiprotonic Helium Atoms

CERN Multimedia

2002-01-01

%PS205 %title\\\\ \\\\Following the discovery of metastable antiprotonic helium atoms ($\\overline{p}He^{+} $) at KEK in 1991, systematic studies of their properties were made at LEAR from 1991 to 1996. In the first two years the lifetime of $\\overline{p}He^{+}$ in liquid and gaseous helium at various temperatures and pressures was measured and the effect of foreign gases on the lifetime of these atoms was investigated. Effects were also discovered which gave the antiproton a 14\\% longer lifetime in $^4$He than in $^3$He, and resulted in important differences in the shape of the annihilation time spectra in the two isotopes.\\\\ \\\\Since 1993 laser spectroscopy of the metastable $\\overline{p}He^{+}$ atoms became the main focus of PS205. Transitions were stimulated between metastable and non-metastable states of the $\\overline{p}He^{+}$ atom by firing a pulsed dye laser beam into the helium target every time an identified metastable atom was present (Figure 1). If the laser frequency matched the transition energy, the...

Reply to the ''Comment on 'Observation of trapped O2 in high-Tc metal oxide superconductors' ''

International Nuclear Information System (INIS)

Chen, C.H.; Phillips, R.C.; Payne, M.G.

1990-01-01

Desorption of O 2 in certain high-T c superconductors was observed from scraping the surfaces of superconductors by Rosenberg and Wen. Their conclusion agrees with the results from the observation of O 2 trapping by a laser ablation of superconductors. However, the local heating due to the scraping process can possibly raise the local surface temperature significantly higher than the temperature of the bulk

Features of laser spectroscopy and diagnostics of plasma ions in high magnetic fields

International Nuclear Information System (INIS)

Semerok, A F; Fomichev, S V

2003-01-01

Laser induced fluorescence and laser absorption spectroscopies of plasma ions in high magnetic fields have been investigated. Both the high degree of Zeeman splitting of the resonant transitions and the ion rotational movement drastically change the properties of the resonance interaction of the continuous wave laser radiation with ions in highly magnetized plasma. Numerical solution of the density matrix equation for a dissipative two-level system with time-dependent detuning from resonance was used to analyse this interaction. A theoretical simulation was performed and compared with the experimental results obtained from the laser spectroscopy diagnostics of barium plasma ions in high magnetic fields in the several tesla range

Laser induced breakdown spectroscopy for applications in nuclear industry

International Nuclear Information System (INIS)

Suri, B.M.

2010-01-01

There are several analytical techniques employing laser spectroscopy - each with its own distinctive potential. Laser Induced Breakdown Spectroscopy (LIBS) is one such technique which is attractive in view of its relative compactness and simplicity (in configuration), remote and online analysis (with no sample handling requirement) and high spatial resolution allowing compositional map or homogeneity analysis. In this technique, a high power pulsed (mostly nanosecond) laser is employed to irradiate the sample causing spark emission, characteristics of the sample composition, which is collected using suitable optics and analysed spectroscopically. Remote and online capability is derived from long distance delivery of laser beams and collection of emitted light by fibres or conventional optics. Since laser can be focused sharply on the target, it can facilitate compositional mapping. Beam Technology Development Group at BARC had initiated work on LIBS of nuclear materials several years ago. Recently the challenge of online monitoring of radioactive waste vitrification plant in a hot cell has been taken up. The theoretical and experimental work done by the group related to instrument development, plasma characterization, quantitative compositional analysis of ternary alloys and uranium vitrified glass samples (comprising more than dozen elements) are described. The future plans for setting up online glass homogeneity monitoring facility are also described. This should fulfill an important demand for optimization of vitrification process. Various other demands of nuclear industry are also reviewed

Comparison between measurements of hyperfine structures of Pr II - lines investigated by collinear laser ion beam spectroscopy (CLIBS) ans saturation spectroscopy

Energy Technology Data Exchange (ETDEWEB)

Akhtar, Nadeem; Anjum, Naveed [Inst. f. Experimentalphysik, Techn. Univ. Graz, Petersgasse 16, A-8010 Graz (Austria); Optics Labs, Nilore, Islamabad (Pakistan); Huehnermann, Harry [Inst. f. Experimentalphysik, Techn. Univ. Graz, Petersgasse 16, A-8010 Graz (Austria); Fachbereich Physik, Univ. Marburg/Lahn (Germany); Windholz, Laurentius [Inst. f. Experimentalphysik, Techn. Univ. Graz, Petersgasse 16, A-8010 Graz (Austria)

2011-07-01

Investigation of narrow hyperfine structures needs a reduction of the Doppler broadening of the investigated lines. Here we have used two methods: collinear laser spectroscopy (CLIBS) and laser saturation spectroscopy. In the first method, the Doppler width is reduced by accelerating Pr ions to a high velocity and excitation with a collinear laser beam, while in the second method ions with velocity group zero are selected by nonlinear saturation. In this work the hyperfine spectra of several Pr II lines were investigated using CLIBS. A line width of ca. 60 MHz was measured. The same lines were then investigated in a hollow cathode discharge lamp using intermodulated laser-induced fluorescence spectroscopy. Using this technique a spectral line width of about 200 MHz was achieved. In both methods, the excitation source is a ring dye laser operated with R6G. Using a fit program, magnetic dipole interaction constants A and the electric-quadrupole interaction constants B of the involved levels have been determined in both cases. We discuss advantages and disadvantages of both methods.

Recombination and propagation of quasiparticles in cuprate superconductors

International Nuclear Information System (INIS)

Gedik, Nuh

2004-01-01

Rapid developments in time-resolved optical spectroscopy have led to renewed interest in the nonequilibrium state of superconductors and other highly correlated electron materials. In these experiments, the nonequilibrium state is prepared by the absorption of short (less than 100 fs) laser pulses, typically in the near-infrared, that perturb the density and energy distribution of quasiparticles. The evolution of the nonequilibrium state is probed by time resolving the changes in the optical response functions of the medium that take place after photoexcitation. Ultimately, the goal of such experiments is to understand not only the nonequilibrium state, but to shed light on the still poorly understood equilibrium properties of these materials. We report nonequilibrium experiments that have revealed aspects of the cup rates that have been inaccessible by other techniques. Namely, the diffusion and recombination coefficients of quasiparticles have been measured in both YBa 2 Cu 3 O 6.5 and Bi 2 Sr 2 CaCu 2 O 8+x using time-resolved optical spectroscopy. Dependence of these measurements on doping, temperature and laser intensity is also obtained. To study the recombination of quasiparticles, we measure the change in reflectivity ΔR which is directly proportional to the nonequilibrium quasiparticle density created by the laser. From the intensity dependence, we estimate β, the inelastic scattering coefficient and γ th thermal equilibrium quasiparticle decay rate. We also present the dependence of recombination measurements on doping in Bi 2 Sr 2 CaCu 2 O 8+x . Going from underdoped to overdoped regime, the sign of ΔR changes from positive to negative right at the optimal doping. This is accompanied by a change in dynamics. The decay of ΔR stops being intensity dependent exactly at the optimal doping. We provide possible interpretations of these two observations. To study the propagation of quasiparticles, we interfered two laser pulses to introduce a spatially

Calibration of the ISOLDE acceleration voltage using a high-precision voltage divider and applying collinear fast beam laser spectroscopy

CERN Document Server

Krieger, A.; Catherall, R.; Hochschulz, F.; Kramer, J.; Neugart, R.; Rosendahl, S.; Schipper, J.; Siesling, E.; Weinheimer, Ch.; Yordanov, D.T.; Nortershauser, W.

2011-01-01

A high-voltage divider with accuracy at the ppm level and collinear laser spectroscopy were used to calibrate the highvoltage installation at the radioactive ion beam facility ISOLDE at CERN. The accurate knowledge of this voltage is particularly important for collinear laser spectroscopy measurements. Beam velocity measurements using frequencycomb based collinear laser spectroscopy agree with the new calibration. Applying this, one obtains consistent results for isotope shifts of stable magnesium isotopes measured using collinear spectroscopy and laser spectroscopy on laser-cooled ions in a trap. The long-term stability and the transient behavior during recovery from a voltage dropout were investigated for the different power supplies currently applied at ISOLDE.

Real-time control of ultrafast laser micromachining by laser-induced breakdown spectroscopy

International Nuclear Information System (INIS)

Tong Tao; Li Jinggao; Longtin, Jon P.

2004-01-01

Ultrafast laser micromachining provides many advantages for precision micromachining. One challenging problem, however, particularly for multilayer and heterogeneous materials, is how to prevent a given material from being ablated, as ultrafast laser micromachining is generally material insensitive. We present a real-time feedback control system for an ultrafast laser micromachining system based on laser-induced breakdown spectroscopy (LIBS). The characteristics of ultrafast LIBS are reviewed and discussed so as to demonstrate the feasibility of the technique. Comparison methods to identify the material emission patterns are developed, and several of the resulting algorithms were implemented into a real-time computer control system. LIBS-controlled micromachining is demonstrated for the fabrication of microheater structures on thermal sprayed materials. Compared with a strictly passive machining process without any such feedback control, the LIBS-based system provides several advantages including less damage to the substrate layer, reduced machining time, and more-uniform machining features

Indirect absorption spectroscopy using quantum cascade lasers: mid-infrared refractometry and photothermal spectroscopy.

Science.gov (United States)

Pfeifer, Marcel; Ruf, Alexander; Fischer, Peer

2013-11-04

We record vibrational spectra with two indirect schemes that depend on the real part of the index of refraction: mid-infrared refractometry and photothermal spectroscopy. In the former, a quantum cascade laser (QCL) spot is imaged to determine the angles of total internal reflection, which yields the absorption line via a beam profile analysis. In the photothermal measurements, a tunable QCL excites vibrational resonances of a molecular monolayer, which heats the surrounding medium and changes its refractive index. This is observed with a probe laser in the visible. Sub-monolayer sensitivities are demonstrated.

Photoacoustic Spectroscopy with Quantum Cascade Lasers for Trace Gas Detection

Directory of Open Access Journals (Sweden)

Gaetano Scamarcio

2006-10-01

Full Text Available Various applications, such as pollution monitoring, toxic-gas detection, noninvasive medical diagnostics and industrial process control, require sensitive and selectivedetection of gas traces with concentrations in the parts in 109 (ppb and sub-ppb range.The recent development of quantum-cascade lasers (QCLs has given a new aspect toinfrared laser-based trace gas sensors. In particular, single mode distributed feedback QCLsare attractive spectroscopic sources because of their excellent properties in terms of narrowlinewidth, average power and room temperature operation. In combination with these lasersources, photoacoustic spectroscopy offers the advantage of high sensitivity and selectivity,compact sensor platform, fast time-response and user friendly operation. This paper reportsrecent developments on quantum cascade laser-based photoacoustic spectroscopy for tracegas detection. In particular, different applications of a photoacoustic trace gas sensoremploying a longitudinal resonant cell with a detection limit on the order of hundred ppb ofozone and ammonia are discussed. We also report two QC laser-based photoacousticsensors for the detection of nitric oxide, for environmental pollution monitoring andmedical diagnostics, and hexamethyldisilazane, for applications in semiconductormanufacturing process.

Invited Article: High resolution angle resolved photoemission with tabletop 11 eV laser

Energy Technology Data Exchange (ETDEWEB)

He, Yu; Vishik, Inna M.; Yi, Ming; Yang, Shuolong; Lee, James J.; Chen, Sudi; Rebec, Slavko N.; Leuenberger, Dominik; Shen, Zhi-Xun [SIMES, SLAC National Accelerator Laboratory, Menlo Park, California 94025 (United States); Department of Applied Physics, Stanford University, Stanford, California 94305 (United States); Liu, Zhongkai [SIMES, SLAC National Accelerator Laboratory, Menlo Park, California 94025 (United States); Department of Physics, Stanford University, Stanford, California 94305 (United States); Zong, Alfred [Department of Physics, Stanford University, Stanford, California 94305 (United States); Jefferson, C. Michael; Merriam, Andrew J. [Lumeras LLC, 207 McPherson St, Santa Cruz, California 95060 (United States); Moore, Robert G.; Kirchmann, Patrick S. [SIMES, SLAC National Accelerator Laboratory, Menlo Park, California 94025 (United States)

2016-01-15

We developed a table-top vacuum ultraviolet (VUV) laser with 113.778 nm wavelength (10.897 eV) and demonstrated its viability as a photon source for high resolution angle-resolved photoemission spectroscopy (ARPES). This sub-nanosecond pulsed VUV laser operates at a repetition rate of 10 MHz, provides a flux of 2 × 10{sup 12} photons/s, and enables photoemission with energy and momentum resolutions better than 2 meV and 0.012 Å{sup −1}, respectively. Space-charge induced energy shifts and spectral broadenings can be reduced below 2 meV. The setup reaches electron momenta up to 1.2 Å{sup −1}, granting full access to the first Brillouin zone of most materials. Control over the linear polarization, repetition rate, and photon flux of the VUV source facilitates ARPES investigations of a broad range of quantum materials, bridging the application gap between contemporary low energy laser-based ARPES and synchrotron-based ARPES. We describe the principles and operational characteristics of this source and showcase its performance for rare earth metal tritellurides, high temperature cuprate superconductors, and iron-based superconductors.

Quantum cascade laser infrared spectroscopy of single cancer cells

KAUST Repository

Patel, Imran; Rajamanickam, Vijayakumar Palanisamy; Bertoncini, Andrea; Pagliari, Francesca; Tirinato, Luca; Laptenok, Sergey P.; Liberale, Carlo

2017-01-01

Quantum cascade laser infrared spectroscopy is a next generation novel imaging technique allowing high resolution spectral imaging of cells. We show after spectral pre-processing, identification of different cancer cell populations within minutes.

Quantum cascade laser infrared spectroscopy of single cancer cells

KAUST Repository

Patel, Imran

2017-03-27

Quantum cascade laser infrared spectroscopy is a next generation novel imaging technique allowing high resolution spectral imaging of cells. We show after spectral pre-processing, identification of different cancer cell populations within minutes.

OH spectroscopy with frequency-doubled dye laser radiation

Energy Technology Data Exchange (ETDEWEB)

ter Meulen, J J

1979-01-01

Discusses the excitation of the OH radical by UV radiation for the determination of the hyperfine structure of the excited states. The 307 nm UV light is obtained by doubling the frequency (in double-refraction crystals) of a tunable dye laser. Details of the laser set-up are given. The method is suitable for application to other high-resolution molecular spectroscopy experiments in the area between 200 and 400 nm. Further extensions can be expected with ring compound dyes and external doubling of the frequency.

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.

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.

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.

Laser systems for collinear spectroscopy and the charge radius of 12Be

International Nuclear Information System (INIS)

Krieger, Andreas

2012-01-01

Collinear laser spectroscopy has been used to investigate the nuclear charge radii of shortlived medium- and heavy-Z nuclei for more than three decades. But it became only recently be applicable to low-Z nuclei. This region of the nuclear chart attracts attention because so-called ab-initio nuclear models, based on realistic nucleon-nucleon potentials, can only be applied to the lightest elements due to the rapidly increasing calculational demands with the number of nucleons. Furthermore, strong clusterization of atomic nuclei occurs and the encountered halo nuclei are presently subject of intense research. The isotopic chain of beryllium exhibits the prime example of a one-neutron halo nucleus, 11 Be, and the two- or four-neutron halo nucleus 14 Be. 12 Be is a key isotope between these two exotic nuclei and particularly interesting because the nuclear shell model predicts a shell closure for the magic neutron number N = 8. In the course of this thesis, several frequency-stabilized laser systems for collinear laser spectroscopy have been developed. At TRIGA-SPEC a frequency-doubled diode laser system with a tapered amplifier and a frequency comb-stabilized titanium-sapphire laser with a frequency doubling stage are now available for the spectroscopy of refractory metals above molybdenum. They have already been used for test-experiments and commissioning of the TRIGA-LASER beamline. Furthermore, frequency-quadrupling of the Ti:Sa laser was demonstrated to expand the emitted wavelengths into the 200 nm region. At ISOLDE/CERN a frequency comb-stabilized and an iodine-stabilized dye laser were installed and applied for laser spectroscopy of 9,10,11,12 Be + . The improved laser system and the development of a delayed photon-ion coincidence detection improved the sensitivity of the beryllium spectroscopy by more than two orders of magnitude and, thus, the previous measurements of 7-11 Be could be extended for the first time to the short-lived isotope 12 Be. In addition

Characterization of redeposited carbon layers on TEXTOR limiter by Laser Raman spectroscopy

International Nuclear Information System (INIS)

Egashira, K.; Tanabe, T.; Yoshida, M.; Nakazato, H.; Philipps, V.; Brezinsek, S.; Kreter, A.

2011-01-01

Highlights: ► Laser Raman technique has applied to analyze the deposited carbon layers on TEXTOR test limiters of C and W. ► The carbon deposited layers showed the Raman spectra composed of G-peak and D-peak. ► For W limiter, hydrogen concentrations in the deposited carbon layers and their thicknesses correlated to the two peaks. ► The Laser Raman spectroscopy is a promising tool for in situ analysis of carbon redeposit layers on plasma facing W materials. - Abstract: Laser Raman spectroscopy is quite sensitive to detect the changes of graphite structure. In this study, the Laser Raman technique was applied to analyze the deposited carbon layers on TEXTOR test limiters of carbon (C) and tungsten (W) produced by intentional carbon deposition experiments by methane gas puffing. The carbon deposited layers showed the Raman spectra composed of two broad peaks, G-peak and D-peak, centered at around 1580 and 1355 cm −1 respectively. For W limiter, the G-peak position and the integrated intensity of the two peaks well correlate to hydrogen concentrations in the deposited carbon layers and their thicknesses, respectively. Hence Laser Raman spectroscopy is a promising tool for the in situ analysis of carbon redeposit layers on plasma facing W materials and probably on Be materials.

Quantitative analysis of chromium concentration in nickel based alloys by laser induced breakdown spectroscopy at atmospheric pressure using a nanosecond ultraviolet Nd:YAG laser

International Nuclear Information System (INIS)

Gupta, G.P.; Suri, B.M.; Verma, A.; Sundararaman, M.; Unnikrishnan, V.K.; Alti, K.; Kartha, V.B.; Santhosh, C.

2010-01-01

Laser-induced breakdown spectroscopy (LIBS) has been well recognized as a simple, fast and direct analytical technique of elemental analysis of multi-element materials by a number of research groups all over the world. It is based on the focusing of a high-power pulsed laser beam with a power density > 100 MW/cm 2 onto a sample surface followed by optical emission spectroscopy of the plasma produced over the surface. In the present work, they have carried out the quantitative analysis of chromium in nickel-based-alloys using laser-induced breakdown spectroscopy (LIBS) in air at atmospheric pressure. In the present work the quantitative analysis of chromium in nickel-based-alloys using laser-induced break-down spectroscopy (LIBS) in air at atmospheric pressure has been carried out

Infrared-laser spectroscopy using a long-pathlength absorption cell

International Nuclear Information System (INIS)

Kim, K.C.; Briesmeister, R.A.

1983-01-01

The absorption measurements in an ordinary cell may require typically a few torr pressure of sample gas. At these pressures the absorption lines are usually pressure-broadened and, therefore, closely spaced transitions are poorly resolved even at diode-laser resolution. This situation is greatly improved in Doppler-limited spectroscopy at extremely low sample pressures. Two very long-pathlength absorption cells were developed to be used in conjunction with diode lasers. They were designed to operate at controlled temperatures with the optical pathlength variable up to approx. 1.5 km. Not only very low sample pressures are used for studies with such cells but also the spectroscopic sensitivity is enhanced over conventional methods by a factor of 10 3 to 10 4 , improving the analytical capability of measuring particle densities to the order of 1 x 10'' molecules/cm 3 . This paper presents some analytical aspects of the diode laser spectroscopy using the long-pathlength absorption cells in the areas of absorption line widths, pressure broadening coefficients, isotope composition measurements and trace impurity analysis

Optical and electron microanalysis of cuprate superconductors

International Nuclear Information System (INIS)

Hoff, H.A.; Osofsky, M.S.; Toth, L.E.; Richards, L.E.; Pande, C.S.; Lechter, W.L.

1990-01-01

Individual anisotropic grains in heterogeneous and opaque cuprate materials, when viewed in a reflected-light optical microscope through crossed polarizers, often have characteristic colors, when a daylight source is used. Of the cuprate superconductors, regardless of charge carrier type, examined so far, only one characteristic color has been observed We have studied the presence of color and found a strong correlation with the existence of superconductivity. The change in color from insulator to metal to superconductor and the compositions corresponding to these changes found by quantitative energy dispersive x-ray spectroscopy on superconducting Tl-Sr-Ca-Cu-O and metallic but not superconducting La-Sr-Cu-O materials is discussed

Calibration of the ISOLDE acceleration voltage using a high-precision voltage divider and applying collinear fast beam laser spectroscopy

Energy Technology Data Exchange (ETDEWEB)

Krieger, A., E-mail: kriegea@uni-mainz.d [Institut fuer Kernchemie, Johannes Gutenberg, Universitaet Mainz, Fritz-Strassmann-Weg 2, 55128 Mainz (Germany); Geppert, Ch. [Institut fuer Kernchemie, Johannes Gutenberg, Universitaet Mainz, Fritz-Strassmann-Weg 2, 55128 Mainz (Germany); GSI Helmholtzzentrum fuer Schwerionenforschung, 64291 Darmstadt (Germany); Catherall, R. [CERN, CH-1211 Geneve 23 (Switzerland); Hochschulz, F. [Institut fuer Kernphysik, Universitaet Muenster, 48149 Muenster (Germany); Kraemer, J.; Neugart, R. [Institut fuer Kernchemie, Johannes Gutenberg, Universitaet Mainz, Fritz-Strassmann-Weg 2, 55128 Mainz (Germany); Rosendahl, S. [Institut fuer Kernphysik, Universitaet Muenster, 48149 Muenster (Germany); Schipper, J.; Siesling, E. [CERN, CH-1211 Geneve 23 (Switzerland); Weinheimer, Ch. [Institut fuer Kernphysik, Universitaet Muenster, 48149 Muenster (Germany); Yordanov, D.T. [Max-Planck-Institut fuer Kernphysik, 69117 Heidelberg (Germany); Noertershaeuser, W. [Institut fuer Kernchemie, Johannes Gutenberg, Universitaet Mainz, Fritz-Strassmann-Weg 2, 55128 Mainz (Germany); GSI Helmholtzzentrum fuer Schwerionenforschung, 64291 Darmstadt (Germany)

2011-03-11

A high-voltage divider with accuracy at the ppm level and collinear laser spectroscopy were used to calibrate the high-voltage installation at the radioactive ion beam facility ISOLDE at CERN. The accurate knowledge of this voltage is particularly important for collinear laser spectroscopy measurements. Beam velocity measurements using frequency-comb based collinear laser spectroscopy agree with the new calibration. Applying this, one obtains consistent results for isotope shifts of stable magnesium isotopes measured using collinear spectroscopy and laser spectroscopy on laser-cooled ions in a trap. The long-term stability and the transient behavior during recovery from a voltage dropout were investigated for the different power supplies currently applied at ISOLDE.

Commissioning of the collinear laser spectroscopy system in the BECOLA facility at NSCL

International Nuclear Information System (INIS)

Minamisono, K.; Mantica, P.F.; Klose, A.; Vinnikova, S.; Schneider, A.; Johnson, B.; Barquest, B.R.

2013-01-01

A collinear laser-spectroscopy (CLS) system in the BEam COoler and LAser spectroscopy (BECOLA) facility was constructed at National Superconducting Cyclotron Laboratory (NSCL) at Michigan State University. The BECOLA facility will be used to advance measurements of nuclear properties of low-energy rare isotope beams generated via in-flight reactions and subsequent beam thermalization in a buffer gas. The CLS studies at BECOLA will complement laser spectroscopy studies of charge radii and nuclear moments mostly obtained so far at Isotope SeOn Line (ISOL) facilities. Commissioning tests of the CLS system have been performed using an offline ion source to produce stable-ion beams. The tests set the ground work for experiments at the future Facility for Rare Isotope Beams (FRIB) as well as experiments at the current Coupled Cyclotron Facility at NSCL

The rates of elementary atomic processes and laser spectroscopy

International Nuclear Information System (INIS)

Rudzikas, Z.; Sereapinas, P.; Kaulakys, B.

1989-01-01

Laser spectroscopy and physics of the atom are closely interrelated. Spectra are the fundamental characteristics of atoms. Modern atomic spectroscopy deals with the structure and properties of any atom of the periodic table as well as of ions of any ionization degree. Therefore, one has to develop fairly universal and, at the same time, exact methods. In this paper briefly analyze the contemporary status of the theory of many-electron atoms and ions, the peculiarities of their structure and spectra, as well as of the processes of their interaction with radiation, interatomic interaction and of the plasma spectroscopy. The attention mainly is paid to the spectroscopy of multiply charged ions and to the processes with highly excited atoms

Fiber-ring laser-based intracavity photoacoustic spectroscopy for trace gas sensing.

Science.gov (United States)

Wang, Qiang; Wang, Zhen; Chang, Jun; Ren, Wei

2017-06-01

We demonstrated a novel trace gas sensing method based on fiber-ring laser intracavity photoacoustic spectroscopy. This spectroscopic technique is a merging of photoacoustic spectroscopy (PAS) with a fiber-ring cavity for sensitive and all-fiber gas detection. A transmission-type PAS gas cell (resonant frequency f0=2.68  kHz) was placed inside the fiber-ring laser to fully utilize the intracavity laser power. The PAS signal was excited by modulating the laser wavelength at f0/2 using a custom-made fiber Bragg grating-based modulator. We used this spectroscopic technique to detect acetylene (C2H2) at 1531.6 nm as a proof of principle. With a low Q-factor (4.9) of the PAS cell, our sensor achieved a good linear response (R2=0.996) to C2H2 concentration and a minimum detection limit of 390 ppbv at 2-s response time.

High-resolution laser spectroscopy of nickel isotopes

CERN Multimedia

This proposal aims to measure the nuclear ground-state spins, moments and mean-square charge radii of $^{56-71}$Ni using collinear laser spectroscopy. This will enable direct measurements of isotopes in the region of shell closure $^{56}$Ni, structural change $^{68}$Ni and monopole migration beyond N = 40. Optical spectroscopy serves as a detailed probe not only of the changing single-particle behaviour, but also for the study of collective properties such as size and shape. Measurements of the most neutron-rich isotopes available at ISOLDE will critically test models which seek to extrapolate the data to the doubly magic region of $^{78}$Ni.

Angle-Resolved Photoemission Spectroscopy on Electronic Structure and Electron-Phonon Coupling in Cuprate Superconductors

Energy Technology Data Exchange (ETDEWEB)

Zhou, X.J.

2010-04-30

In addition to the record high superconducting transition temperature (T{sub c}), high temperature cuprate superconductors are characterized by their unusual superconducting properties below T{sub c}, and anomalous normal state properties above T{sub c}. In the superconducting state, although it has long been realized that superconductivity still involves Cooper pairs, as in the traditional BCS theory, the experimentally determined d-wave pairing is different from the usual s-wave pairing found in conventional superconductors. The identification of the pairing mechanism in cuprate superconductors remains an outstanding issue. The normal state properties, particularly in the underdoped region, have been found to be at odd with conventional metals which is usually described by Fermi liquid theory; instead, the normal state at optimal doping fits better with the marginal Fermi liquid phenomenology. Most notable is the observation of the pseudogap state in the underdoped region above T{sub c}. As in other strongly correlated electrons systems, these unusual properties stem from the interplay between electronic, magnetic, lattice and orbital degrees of freedom. Understanding the microscopic process involved in these materials and the interaction of electrons with other entities is essential to understand the mechanism of high temperature superconductivity. Since the discovery of high-T{sub c} superconductivity in cuprates, angle-resolved photoemission spectroscopy (ARPES) has provided key experimental insights in revealing the electronic structure of high temperature superconductors. These include, among others, the earliest identification of dispersion and a large Fermi surface, an anisotropic superconducting gap suggestive of a d-wave order parameter, and an observation of the pseudogap in underdoped samples. In the mean time, this technique itself has experienced a dramatic improvement in its energy and momentum resolutions, leading to a series of new discoveries not

Angle-Resolved Photoemission Spectroscopy on Electronic Structure and Electron-Phonon Coupling in Cuprate Superconductors

International Nuclear Information System (INIS)

Zhou, X.J.

2010-01-01

In addition to the record high superconducting transition temperature (T c ), high temperature cuprate superconductors are characterized by their unusual superconducting properties below T c , and anomalous normal state properties above T c . In the superconducting state, although it has long been realized that superconductivity still involves Cooper pairs, as in the traditional BCS theory, the experimentally determined d-wave pairing is different from the usual s-wave pairing found in conventional superconductors. The identification of the pairing mechanism in cuprate superconductors remains an outstanding issue. The normal state properties, particularly in the underdoped region, have been found to be at odd with conventional metals which is usually described by Fermi liquid theory; instead, the normal state at optimal doping fits better with the marginal Fermi liquid phenomenology. Most notable is the observation of the pseudogap state in the underdoped region above T c . As in other strongly correlated electrons systems, these unusual properties stem from the interplay between electronic, magnetic, lattice and orbital degrees of freedom. Understanding the microscopic process involved in these materials and the interaction of electrons with other entities is essential to understand the mechanism of high temperature superconductivity. Since the discovery of high-T c superconductivity in cuprates, angle-resolved photoemission spectroscopy (ARPES) has provided key experimental insights in revealing the electronic structure of high temperature superconductors. These include, among others, the earliest identification of dispersion and a large Fermi surface, an anisotropic superconducting gap suggestive of a d-wave order parameter, and an observation of the pseudogap in underdoped samples. In the mean time, this technique itself has experienced a dramatic improvement in its energy and momentum resolutions, leading to a series of new discoveries not thought possible

A universal explanation of tunneling conductance in exotic superconductors

OpenAIRE

Hong, Jongbae; Abergel, D. S. L.

2016-01-01

A longstanding mystery in understanding cuprate superconductors is the inconsistency between the experimental data measured by scanning tunneling spectroscopy (STS) and angle-resolved photoemission spectroscopy (ARPES). In particular, the gap between prominent side peaks observed in STS is much bigger than the superconducting gap observed by ARPES measurements. Here, we reconcile the two experimental techniques by generalising a theory which was previously applied to zero-dimensional mesoscop...

Laser activated superconducting switch

International Nuclear Information System (INIS)

Wolf, A.A.

1976-01-01

A superconducting switch or bistable device is described consisting of a superconductor in a cryogen maintaining a temperature just below the transition temperature, having a window of the proper optical frequency band for passing a laser beam which may impinge on the superconductor when desired. The frequency of the laser is equal to or greater than the optical absorption frequency of the superconducting material and is consistent with the ratio of the gap energy of the switch material to Planck's constant, to cause depairing of electrons, and thereby normalize the superconductor. Some embodiments comprise first and second superconducting metals. Other embodiments feature the two superconducting metals separated by a thin film insulator through which the superconducting electrons tunnel during superconductivity

Review of x-ray spectroscopy from laser-produced plasmas

International Nuclear Information System (INIS)

Kauffman, R.L.

1987-09-01

Recent progress in x-ray spectroscopy from laser plasmas is reviewed. Advances in the use of K-shell spectra as a diagnostic tool is discussed. Much activity in understanding complex spectra especially from Ne I and Ni I isoelectronic series have been made. Much of the progress has been due to observation of amplification from Δn = O transitions from these configurations. The spectroscopy will be discussed and examples of spectra of the amplified lines will be shown. Finally, recent work on using x-ray spectroscopy to diagnose high density implosions will be discussed. 33 refs

Adaptive sampling dual terahertz comb spectroscopy using dual free-running femtosecond lasers.

Science.gov (United States)

Yasui, Takeshi; Ichikawa, Ryuji; Hsieh, Yi-Da; Hayashi, Kenta; Cahyadi, Harsono; Hindle, Francis; Sakaguchi, Yoshiyuki; Iwata, Tetsuo; Mizutani, Yasuhiro; Yamamoto, Hirotsugu; Minoshima, Kaoru; Inaba, Hajime

2015-06-02

Terahertz (THz) dual comb spectroscopy (DCS) is a promising method for high-accuracy, high-resolution, broadband THz spectroscopy because the mode-resolved THz comb spectrum includes both broadband THz radiation and narrow-line CW-THz radiation characteristics. In addition, all frequency modes of a THz comb can be phase-locked to a microwave frequency standard, providing excellent traceability. However, the need for stabilization of dual femtosecond lasers has often hindered its wide use. To overcome this limitation, here we have demonstrated adaptive-sampling THz-DCS, allowing the use of free-running femtosecond lasers. To correct the fluctuation of the time and frequency scales caused by the laser timing jitter, an adaptive sampling clock is generated by dual THz-comb-referenced spectrum analysers and is used for a timing clock signal in a data acquisition board. The results not only indicated the successful implementation of THz-DCS with free-running lasers but also showed that this configuration outperforms standard THz-DCS with stabilized lasers due to the slight jitter remained in the stabilized lasers.

Optical Fiber Sensing Based on Reflection Laser Spectroscopy

Directory of Open Access Journals (Sweden)

Gianluca Gagliardi

2010-03-01

Full Text Available An overview on high-resolution and fast interrogation of optical-fiber sensors relying on laser reflection spectroscopy is given. Fiber Bragg-gratings (FBGs and FBG resonators built in fibers of different types are used for strain, temperature and acceleration measurements using heterodyne-detection and optical frequency-locking techniques. Silica fiber-ring cavities are used for chemical sensing based on evanescent-wave spectroscopy. Various arrangements for signal recovery and noise reduction, as an extension of most typical spectroscopic techniques, are illustrated and results on detection performances are presented.

Development of a compact vertical-cavity surface-emitting laser end-pumped actively Q-switched laser for laser-induced breakdown spectroscopy

Energy Technology Data Exchange (ETDEWEB)

Li, Shuo; Chen, Rongzhang; Nelsen, Bryan; Chen, Kevin, E-mail: pec9@pitt.edu [Department of Electrical and Computer Engineering, University of Pittsburgh, Pittsburgh, Pennsylvania 15260 (United States); Liu, Lei; Huang, Xi; Lu, Yongfeng [Department of Electrical and Computer Engineering, University of Nebraska-Lincoln, Lincoln, Nebraska 68588 (United States)

2016-03-15

This paper reports the development of a compact and portable actively Q-switched Nd:YAG laser and its applications in laser-induced breakdown spectroscopy (LIBS). The laser was end-pumped by a vertical-cavity surface-emitting laser (VCSEL). The cavity lases at a wavelength of 1064 nm and produced pulses of 16 ns with a maximum pulse energy of 12.9 mJ. The laser exhibits a reliable performance in terms of pulse-to-pulse stability and timing jitter. The LIBS experiments were carried out using this laser on NIST standard alloy samples. Shot-to-shot LIBS signal stability, crater profile, time evolution of emission spectra, plasma electron density and temperature, and limits of detection were studied and reported in this paper. The test results demonstrate that the VCSEL-pumped solid-state laser is an effective and compact laser tool for laser remote sensing applications.

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.

Time resolved measurement of laser-ablated particles by LAPXAS (Laser Plasma Soft X-ray Absorption Spectroscopy)

International Nuclear Information System (INIS)

Miyashita, Atsumi; Yoda, Osamu; Murakami, Kouichi

1999-01-01

The time- and spatially-resolved properties of laser ablated carbon, boron and silicon particles were measured by LAPXAS (Laser Plasma Soft X-ray Absorption Spectroscopy). The maximum speed of positively charged ions is higher than those of neutral atoms and negatively charged ions. The spatial distributions of the laser-ablated particles in the localized rare gas environment were measured. In helium gas environment, by the helium cloud generated on the top of ablation plume depressed the ablation plume. There is no formation of silicon clusters till 15 μs after laser ablation in the argon gas environment. (author)

Time-Resolved Spectroscopy Diagnostic of Laser-Induced Optical Breakdown

Directory of Open Access Journals (Sweden)

Christian G. Parigger

2010-01-01

Full Text Available Transient laser plasma is generated in laser-induced optical breakdown (LIOB. Here we report experiments conducted with 10.6-micron CO2 laser radiation, and with 1.064-micron fundamental, 0.532-micron frequency-doubled, 0.355-micron frequency-tripled Nd:YAG laser radiation. Characterization of laser induced plasma utilizes laser-induced breakdown spectroscopy (LIBS techniques. Atomic hydrogen Balmer series emissions show electron number density of 1017 cm−3 measured approximately 10 μs and 1 μs after optical breakdown for CO2 and Nd:YAG laser radiation, respectively. Recorded molecular recombination emission spectra of CN and C2 Swan bands indicate an equilibrium temperature in excess of 7000 Kelvin, inferred for these diatomic molecules. Reported are also graphite ablation experiments where we use unfocused laser radiation that is favorable for observation of neutral C3 emission due to reduced C3 cation formation. Our analysis is based on computation of diatomic molecular spectra that includes accurate determination of rotational line strengths, or Hönl-London factors.

Real-time monitoring of atom vapor concentration with laser absorption spectroscopy

International Nuclear Information System (INIS)

Fan Fengying; Gao Peng; Jiang Tao

2012-01-01

The technology of laser absorption spectroscopy was used for real-time monitoring of gadolinium atom vapor concentration measurement and the solid state laser pumped ring dye laser was used as optical source. The optical fiber was taken to improve the stability of laser transmission. The multi-pass absorption technology combined with reference optical signal avoided the influence of laser power fluctuation. The experiment result shows that the system based on this detection method has a standard error of 4%. It is proved that the monitoring system provides reliable data for atom vapor laser isotope separation process and the separation efficiency can be improved. (authors)

Dual-comb spectroscopy of water vapor with a free-running semiconductor disk laser.

Science.gov (United States)

Link, S M; Maas, D J H C; Waldburger, D; Keller, U

2017-06-16

Dual-comb spectroscopy offers the potential for high accuracy combined with fast data acquisition. Applications are often limited, however, by the complexity of optical comb systems. Here we present dual-comb spectroscopy of water vapor using a substantially simplified single-laser system. Very good spectroscopy measurements with fast sampling rates are achieved with a free-running dual-comb mode-locked semiconductor disk laser. The absolute stability of the optical comb modes is characterized both for free-running operation and with simple microwave stabilization. This approach drastically reduces the complexity for dual-comb spectroscopy. Band-gap engineering to tune the center wavelength from the ultraviolet to the mid-infrared could optimize frequency combs for specific gas targets, further enabling dual-comb spectroscopy for a wider range of industrial applications. Copyright © 2017, American Association for the Advancement of Science.

Laser induced breakdown spectroscopy (LIBS) as a rapid tool for material analysis

International Nuclear Information System (INIS)

Hussain, T; Gondal, M A

2013-01-01

Laser induced breakdown spectroscopy (LIBS) is a novel technique for elemental analysis based on laser-generated plasma. In this technique, laser pulses are applied for ablation of the sample, resulting in the vaporization and ionization of sample in hot plasma which is finally analyzed by the spectrometer. The elements are identified by their unique spectral signatures. LIBS system was developed for elemental analysis of solid and liquid samples. The developed system was applied for qualitative as well as quantitative measurement of elemental concentration present in iron slag and open pit ore samples. The plasma was generated by focusing a pulsed Nd:YAG laser at 1064 nm on test samples to study the capabilities of LIBS as a rapid tool for material analysis. The concentrations of various elements of environmental significance such as cadmium, calcium, magnesium, chromium, manganese, titanium, barium, phosphorus, copper, iron, zinc etc., in these samples were determined. Optimal experimental conditions were evaluated for improving the sensitivity of developed LIBS system through parametric dependence study. The laser-induced breakdown spectroscopy (LIBS) results were compared with the results obtained using standard analytical technique such as inductively couple plasma emission spectroscopy (ICP). Limit of detection (LOD) of our LIBS system were also estimated for the above mentioned elements. This study demonstrates that LIBS could be highly appropriate for rapid online analysis of iron slag and open pit waste.

Laser induced breakdown spectroscopy (LIBS) as a rapid tool for material analysis

Science.gov (United States)

Hussain, T.; Gondal, M. A.

2013-06-01

Laser induced breakdown spectroscopy (LIBS) is a novel technique for elemental analysis based on laser-generated plasma. In this technique, laser pulses are applied for ablation of the sample, resulting in the vaporization and ionization of sample in hot plasma which is finally analyzed by the spectrometer. The elements are identified by their unique spectral signatures. LIBS system was developed for elemental analysis of solid and liquid samples. The developed system was applied for qualitative as well as quantitative measurement of elemental concentration present in iron slag and open pit ore samples. The plasma was generated by focusing a pulsed Nd:YAG laser at 1064 nm on test samples to study the capabilities of LIBS as a rapid tool for material analysis. The concentrations of various elements of environmental significance such as cadmium, calcium, magnesium, chromium, manganese, titanium, barium, phosphorus, copper, iron, zinc etc., in these samples were determined. Optimal experimental conditions were evaluated for improving the sensitivity of developed LIBS system through parametric dependence study. The laser-induced breakdown spectroscopy (LIBS) results were compared with the results obtained using standard analytical technique such as inductively couple plasma emission spectroscopy (ICP). Limit of detection (LOD) of our LIBS system were also estimated for the above mentioned elements. This study demonstrates that LIBS could be highly appropriate for rapid online analysis of iron slag and open pit waste.

Some actinide speciation using laser induced photoacoustic spectroscopy

International Nuclear Information System (INIS)

Pollard, P.M.; McMillan, J.W.; Phillips, G.; Thomason, H.P.; Ewart, F.T.

1988-01-01

Laser induced photoacoustic spectroscopy is an attractive method for the speciation of actinides in solutions from nuclear disposal studies because it is essentially non-invasive and has a reasonably high sensitivity, down to ca 10 -8 M. A novel true dual beam system has been constructed and commissioned at Harwell with a performance at least equal to any others in existence. It is based on a XeCl excimer laser and a dye laser, beam splitter, two laser power monitors and photoacoustic cells. The wavelength scanning, data collection, and spectra processing and display are controlled by an Apricot computer. The sample and reference cells are housed in an inert atmosphere glove box. Early applications of the equipment described include measurements of Am and Np species under varying conditions of pH, Eh and carbonate concentration. The observations show some correlation with predictions made using the geochemical modelling code PHREEQE. (orig.)

Applications of laser-induced gratings to spectroscopy and dynamics

Energy Technology Data Exchange (ETDEWEB)

Rohlfing, E.A. [Sandia National Laboratories, Livermore, CA (United States)

1993-12-01

This program has traditionally emphasized two principal areas of research. The first is the spectroscopic characterization of large-amplitude motion on the ground-state potential surface of small, transient molecules. The second is the reactivity of carbonaceous clusters and its relevance to soot and fullerene formation in combustion. Motivated initially by the desire to find improved methods of obtaining stimulated emission pumping (SEP) spectra of transients, most of our recent work has centered on the use of laser-induced gratings or resonant four-wave mixing in free-jet expansions. These techniques show great promise for several chemical applications, including molecular spectroscopy and photodissociation dynamics. The author describes recent applications of two-color laser-induced grating spectroscopy (LIGS) to obtain background-free SEP spectra of transients and double resonance spectra of nonfluorescing species, and the use of photofragment transient gratings to probe photodissociation dynamics.

Laser-excited fluorescence spectroscopy of oxide glasses

International Nuclear Information System (INIS)

Weber, M.J.

1977-01-01

Laser-induced fluorescence line narrowing was applied to investigate the local fields and interactions of paramagnetic ions in oxide glasses. Studies included the site dependence of energy levels, radiative and nonradiative transition probabilities, homogeneous line broadening, and ion--ion energy transfer of rare earth ions. These results and the experimental techniques are reviewed briefly; the use of paramagnetic ions other than the rare earths is also considered. Recently, laser-excited fluorescence spectroscopy was used to investigate modifications in the local structure of lithium borate glass caused by compositional changes and phase separation and the site dependence of nonradiative relaxation of paramagnetic ions by multiphonon processes. These results and their implications are discussed. 6 figures

Investigations into the electronic structure of the high-Tc superconductors by means of photoelectron spectroscopy

International Nuclear Information System (INIS)

Dauth, B.H.

1989-08-01

The electronic structure of various polycrystalline samples including the new YBaCuO- and BiCaSrCuO- high T c superconductors (HTSC) and related systems is investigated by photoelectron spectroscopy. Additional characterization is performed by conductivity measurements. In particular, the binding energy of the Cu-2p 3/2 - and the O-1s-levels of various HTSC is determined. For the first time the controversial 531 eV oxygen line was shown to be an intrinsic electronic structure effect. Sintered CuO-samples are obtained for the first time. The electronic structure of the sintered CuO turns out to be drastically different with respect to pressed CuO powder. For the first time a crossover resonance from a O-1s- into a Cu-3d-level was observed with synchrotron radiation. This is additional evidence for the strong hybridization between the Cu-3d and the O-2p states. Photoemission spectroscopy shows that the holes in the HTSC's are located at the oxygen p-band. Fe and Al overlayers on the HTSC-samples induce a drastic change in the electronic properties of the interface: apparently oxygen is removed from the HTSC to the overlayer. (orig./BHO)

Ceramic superconductors II

International Nuclear Information System (INIS)

Yan, M.F.

1988-01-01

This volume compiles papers on ceramic superconductors. Topics include: structural patterns in High-Tc superconductors, phase equilibria of barium oxide superconductors, localized electrons in tetragonal YBa/sub 2/Cu/sub 3/O/sub 7-δ/, lattice and defect structure and properties of rare earth/alkaline earth-copper-oxide superconductors, alternate candidates for High-Tc superconductors, perovskite-structure superconductors; superconductive thin film fabrication, and superconductor/polymer composites

Laser-Raman spectroscopy of living cells

International Nuclear Information System (INIS)

Webb, S.J.

1980-01-01

Investigations into the laser-Raman shift spectra of bacterial and mammalian cells have revealed that many Raman lines observed at 4-6 K, do not appear in the spectra of cells held at 300 K. At 300 K, Raman activity, at set frequencies, is observed only when the cells are metabolically active; however, the actual live cell spectrum, between 0 and 3400 cm -1 , has been found to alter in a specific way with time as the cells' progress through their life cycles. Lines above 300 cm -1 , from in vivo Raman active states, appear to shift to higher wave numbers whereas those below 300 cm -1 seem to shift to lower ones. The transient nature of many shift lines observed and the intensity of them when present in the spectrum indicates that, in, vivo, a metabolically induced condensation of closely related states occurs at a set time in the life of a living cell. In addition, the calculated ratio between the intensities of Stokes and anti-Stokes lines observed suggests that the metabolically induced 'collective' Raman active states are produced, in vivo, by non thermal means. It appears, therefore, that the energetics of the well established cell 'time clock' may be studied by laser-Raman spectroscopy; moreover, Raman spectroscopy may yield a new type of information regarding the physics of such biological phenomena as nutrition, virus infection and oncogenesis. (orig.)

Concealed d-wave pairs in the s± condensate of iron-based superconductors.

Science.gov (United States)

Ong, Tzen; Coleman, Piers; Schmalian, Jörg

2016-05-17

A central question in iron-based superconductivity is the mechanism by which the paired electrons minimize their strong mutual Coulomb repulsion. In most unconventional superconductors, Coulomb repulsion is minimized through the formation of higher angular momentum Cooper pairs, with Fermi surface nodes in the pair wavefunction. The apparent absence of such nodes in the iron-based superconductors has led to a belief they form an s-wave ([Formula: see text]) singlet state, which changes sign between the electron and hole pockets. However, the multiorbital nature of these systems opens an alternative possibility. Here, we propose a new class of [Formula: see text] state containing a condensate of d-wave Cooper pairs, concealed by their entanglement with the iron orbitals. By combining the d-wave ([Formula: see text]) motion of the pairs with the internal angular momenta [Formula: see text] of the iron orbitals to make a singlet ([Formula: see text]), an [Formula: see text] superconductor with a nontrivial topology is formed. This scenario allows us to understand the development of octet nodes in potassium-doped Ba1-x KXFe2As2 as a reconfiguration of the orbital and internal angular momentum into a high spin ([Formula: see text]) state; the reverse transition under pressure into a fully gapped state can then be interpreted as a return to the low-spin singlet. The formation of orbitally entangled pairs is predicted to give rise to a shift in the orbital content at the Fermi surface, which can be tested via laser-based angle-resolved photoemission spectroscopy.

Surface transport properties of Fe-based superconductors: The influence of degradation and inhomogeneity

Energy Technology Data Exchange (ETDEWEB)

Plecenik, T.; Gregor, M.; Sobota, R.; Truchly, M.; Satrapinskyy, L.; Kus, P.; Plecenik, A. [Department of Experimental Physics, FMPI, Comenius University, 842 48 Bratislava (Slovakia); Kurth, F.; Holzapfel, B.; Iida, K. [Institute for Metallic Materials, IFW Dresden, P. O. Box 270116, D-01171 Dresden (Germany)

2013-07-29

Surface properties of Co-doped BaFe{sub 2}As{sub 2} epitaxial superconducting thin films were inspected by X-ray photoelectron spectroscopy, scanning spreading resistance microscopy (SSRM), and point contact spectroscopy (PCS). It has been shown that surface of Fe-based superconductors degrades rapidly if being exposed to air, what results in suppression of gap-like structure on PCS spectra. Moreover, SSRM measurements revealed inhomogeneous surface conductivity, what is consistent with strong dependence of PCS spectra on contact position. Presented results suggest that fresh surface and small probing area should be assured for surface sensitive measurements like PCS to obtain intrinsic properties of Fe-based superconductors.

Nanoparticle detection in aqueous solutions using Raman and Laser Induced Breakdown Spectroscopy

NARCIS (Netherlands)

Sovago, M.; Buis, E.-J.; Sandtke, M.

2013-01-01

We show the chemical identification and quantification of the concentration and size of nanoparticle (NP) dispersions in aqueous solutions by using a combination of Raman Spectroscopy and Laser Induced Breakdown Spectroscopy (LIBS). The two spectroscopic techniques are applied to demonstrate the NP

Research On Bi-Based High-Temperature Superconductors

Science.gov (United States)

Banks, Curtis; Doane, George B., III; Golben, John

1993-01-01

Brief report describes effects of melt sintering on Bi-based high-temperature superconductor system, as well as use of vibrating-sample magnetometer to determine hysteresis curves at 77 K for partially melt-sintered samples. Also discussed is production of high-temperature superconducting thin films by laser ablation: such films potentially useful in detection of signals of very low power.

Laser spectroscopy monitoring of cancer therapy

International Nuclear Information System (INIS)

Jyothi Lakshmi, R.; Ullas, G.; Kartha, V.B.; Alexander, Mohan

2000-01-01

Surgery, radiation therapy and chemotherapy are the major treatment modalities for many forms of cancer at present. Monitoring of the therapy, follow up studies on regression of the disease and detection of recurrence are very essential for successful treatment. Any technique which will be of assistance for these purposes will thus be of great help. This paper presents some of our results of Raman and Pulsed Laser fluorescence spectroscopy studies on tissues, body fluids and bone, in oral cancer subjects after radiation therapy

Real-time dual-comb spectroscopy with a free-running bidirectionally mode-locked fiber laser

Science.gov (United States)

Mehravar, S.; Norwood, R. A.; Peyghambarian, N.; Kieu, K.

2016-06-01

Dual-comb technique has enabled exciting applications in high resolution spectroscopy, precision distance measurements, and 3D imaging. Major advantages over traditional methods can be achieved with dual-comb technique. For example, dual-comb spectroscopy provides orders of magnitude improvement in acquisition speed over standard Fourier-transform spectroscopy while still preserving the high resolution capability. Wider adoption of the technique has, however, been hindered by the need for complex and expensive ultrafast laser systems. Here, we present a simple and robust dual-comb system that employs a free-running bidirectionally mode-locked fiber laser operating at telecommunication wavelength. Two femtosecond frequency combs (with a small difference in repetition rates) are generated from a single laser cavity to ensure mutual coherent properties and common noise cancellation. As the result, we have achieved real-time absorption spectroscopy measurements without the need for complex servo locking with accurate frequency referencing, and relatively high signal-to-noise ratio.

Applications of ultra-short pulsed laser ablation: thin films deposition and fs/ns dual-pulse laser-induced breakdown spectroscopy

International Nuclear Information System (INIS)

Teghil, R; De Bonis, A; Galasso, A; Santagata, A; Albano, G; Villani, P; Spera, D; Parisi, G P

2008-01-01

In this paper, we report a survey of two of the large number of possible practical applications of the laser ablation performed by an ultra-short pulse laser, namely pulsed laser deposition (PLD) and fs/ns dual-pulse laser-induced breakdown spectroscopy (DP-LIBS). These applications differ from those using just longer pulsed lasers as a consequence of the distinctive characteristics of the plasma produced by ultra-short laser beams. The most important feature of this plasma is the large presence of particles with nanometric size which plays a fundamental role in both applications.

Far infrared spectroscopy of high-Tc superconductors at the National Synchrotron Light Source

International Nuclear Information System (INIS)

Perkowitz, S.; Williams, G.P.

1989-01-01

This paper reports the first far infrared transmission spectra for micron-thick films of high-T c rare-earth superconductors such as DyBaCuO, with implications for the superconducting gap. Spectra were obtained at Brookhaven's National Synchrotron Light Source, a new high-intensity, broad-band millimeter to infrared source. The National Synchrotron Light Source at Brookhaven National Laboratory, known for powerful X-ray and UV output, is also a high-intensity (10 to 1000 times above a black body), high-brightness (intensity per solid angle), broad-band, picosecond, millimeter to infrared source. These features make it valuable for far-infrared condensed matter experiments, especially those in highly absorbing or extremely small systems. A first application has been to measure very small infrared transmissions through thick bulk-like high-T c superconducting films. Preliminary measurements through films of the conventional superconductor Nb 3 Ge established techniques. These were followed by the first measurements (to the author's knowledge) through micron-thick films of high-T c rare-earth superconductors such as DyBaCuO over 10-300 cm -1 , which includes the superconducting gap according to BCS or moderately strong-coupled theory. The authors discuss the transmission evidence bearing on the existence of a gap and other important features of high-T c superconductors, and describe the synchrotron and instrumentation features which make possible these unusual measurements

The laser spectroscopy for the quality and safety food of vegetables

International Nuclear Information System (INIS)

Falconieri, Mauro; Sighicelli, Maria

2015-01-01

ENEA has long been engaged in research in order to the development of instrumentation and application of spectroscopic methods for monitoring and diagnostics early and non-destructive state of health of plants and the quality of food products. In addition to the most common spectroscopic techniques (such as the Fourier transform infrared spectroscopy, the spectroscopy transmittance and reflectance in the visible and near infrared spectroscopy and photoluminescence), the use of which in the agro-industry is well documented in the scientific literature, particular attention has recently been paid to the Raman spectroscopy and reflectance spectroscopy Time resolved (time-resolved reflectivity spectroscopy, TRRS) with ultrashort laser pulses (in the domain of hundreds of femto seconds, 10 -15 s). [it

Laser frequency stabilization by combining modulation transfer and frequency modulation spectroscopy.

Science.gov (United States)

Zi, Fei; Wu, Xuejian; Zhong, Weicheng; Parker, Richard H; Yu, Chenghui; Budker, Simon; Lu, Xuanhui; Müller, Holger

2017-04-01

We present a hybrid laser frequency stabilization method combining modulation transfer spectroscopy (MTS) and frequency modulation spectroscopy (FMS) for the cesium D2 transition. In a typical pump-probe setup, the error signal is a combination of the DC-coupled MTS error signal and the AC-coupled FMS error signal. This combines the long-term stability of the former with the high signal-to-noise ratio of the latter. In addition, we enhance the long-term frequency stability with laser intensity stabilization. By measuring the frequency difference between two independent hybrid spectroscopies, we investigate the short-and long-term stability. We find a long-term stability of 7.8 kHz characterized by a standard deviation of the beating frequency drift over the course of 10 h and a short-term stability of 1.9 kHz characterized by an Allan deviation of that at 2 s of integration time.

Effect of Laser Irradiation on Cell Function and Its Implications in Raman Spectroscopy.

Science.gov (United States)

Yuan, Xiaofei; Song, Yanqing; Song, Yizhi; Xu, Jiabao; Wu, Yinhu; Glidle, Andrew; Cusack, Maggie; Ijaz, Umer Z; Cooper, Jonathan M; Huang, Wei E; Yin, Huabing

2018-04-15

Lasers are instrumental in advanced bioimaging and Raman spectroscopy. However, they are also well known for their destructive effects on living organisms, leading to concerns about the adverse effects of laser technologies. To implement Raman spectroscopy for cell analysis and manipulation, such as Raman-activated cell sorting, it is crucial to identify nondestructive conditions for living cells. Here, we evaluated quantitatively the effect of 532-nm laser irradiation on bacterial cell fate and growth at the single-cell level. Using a purpose-built microfluidic platform, we were able to quantify the growth characteristics, i.e., specific growth rates and lag times of individual cells, as well as the survival rate of a population in conjunction with Raman spectroscopy. Representative Gram-negative and Gram-positive species show similar trends in response to a laser irradiation dose. Laser irradiation could compromise the physiological function of cells, and the degree of destruction is both dose and strain dependent, ranging from reduced cell growth to a complete loss of cell metabolic activity and finally to physical disintegration. Gram-positive bacterial cells are more susceptible than Gram-negative bacterial strains to irradiation-induced damage. By directly correlating Raman acquisition with single-cell growth characteristics, we provide evidence of nondestructive characteristics of Raman spectroscopy on individual bacterial cells. However, while strong Raman signals can be obtained without causing cell death, the variety of responses from different strains and from individual cells justifies careful evaluation of Raman acquisition conditions if cell viability is critical. IMPORTANCE In Raman spectroscopy, the use of powerful monochromatic light in laser-based systems facilitates the detection of inherently weak signals. This allows environmentally and clinically relevant microorganisms to be measured at the single-cell level. The significance of being able to

High energy spectra on Fe-based unconventional superconductors

Energy Technology Data Exchange (ETDEWEB)

Nag, Pranab Kumar; Baumann, Danny; Schlegel, Ronny; Beck, Robert; Hess, Christian [Leibniz-Institute for Solid State and Materials Research, IFW-Dresden, 01171 Dresden (Germany); Wurmehl, Sabine; Buechner, Bernd [Leibniz-Institute for Solid State and Materials Research, IFW-Dresden, 01171 Dresden (Germany); Institut fuer Festkoerperphysik, TU Dresden, D-01062 Dresden (Germany); Wolf, Thomas [Karlsruher Institut fuer Technologie, Institut fuer Festkoerperphysik, Postfach 3640, D-76021 Karlsruhe (Germany)

2015-07-01

We have performed low-temperature scanning tunneling microscopy and spectroscopy on LiFeAs, Co doped NaFeAs and FeSe superconductors. The spectroscopy data routinely reveal important aspects of the electronic structure both very close to the Fermi level, i.e. the superconducting gap, and distinct features at higher energies. The latter appear in occupied states roughly between -0.3 eV and -0.5 eV in these materials, and allow specific comparison with ARPES band structure data.

The superconductor

International Nuclear Information System (INIS)

Lad, J.K.

1979-01-01

Techniques for fabrication of a few important superconductors like Nb, Ti and Nb 3 Sn are described. Copper or bronze or both can be used as a matrix in the superconductor. Current densities obtained for different ratios of copper to superconductor are studied. The specifications of multi-filament Nb 3 Sn superconductors are given. The relative merits of the two superconductors are discussed. The temperature range obtained is approximately 3 0 K and a magnetic field of 9T(tesla) can be achieved. (A.K.)

Laser based analytical spectroscopy of uranium

International Nuclear Information System (INIS)

Argekar, A.A.; Kulkarni, M.J.; Godbole, S.V.; Page, A.G.; Samuel, J.K.; Paranjape, D.B.; Singh Mudher, K.D.

1992-01-01

Analytical spectroscopy of uranium has been studied using a XeCl excimer laser, using the fluorescence emission of U(VI) ions doped in a solid solution of sodium fluoride (NaF) and sodium chloride (NaCl) in 3:2 proportion. An electronic circuitry involving time-gating of the photomultiplier tube and facility to integrate the analytical signal over ten laser pulses has been developed to enable laser operation and signal detection with high S/N ratio. The matrix enhanced U(VI) fluorescence emission is free from chemical and spectral interferences due to the concomitant presence of ten metallic elements generally associated with uranium. The digital signal output is highly precise and does not saturate upto 5 ppm uranium concentration. X-ray diffraction patterns obtained for uranium doped compounds at 2.5% and 10% dopant concentrations are broadly similar to that of Na 2 U 2 O 7 . The detailed studies have, however, revealed fine structure for individual peaks, thereby, revealing the formation of sodium fluoro-uranate complex which is responsible for the enhanced intensity of fluorescence emission. (author). 10 refs., 6 figs., 2 tabs

Laser spectroscopy of relativistic beams of H- and H

International Nuclear Information System (INIS)

Smith, W.W.; Tang, C.Y.; Harris, P.G.; Mohagheghi, A.H.; Bryant, H.C.; Reeder, R.A.; Toutounchi, H.; Sharifian, H.

1989-01-01

Laser spectroscopy on near-light velocity H- ions and H atoms has been carried out at the Los Alamos Meson Physics Facility using a variety of fixed frequency lasers intersecting accelerated beams at variable angles. Beam energies up to 800 MeV (v/c) = 0.84 make possible an unusually wide tuning range at modestly high resolution. A dedicated beam line, the High Resolution Atomic Beam (HIRAB), also makes possible Stark effect and field ionization studies in the multi-megavolt/cm range. Preliminary results on multiphoton detachment of fast H-ions using a pulsed CO 2 laser focussed to ∼10 11 W/cm 2 over a factor 10 photon energy range (CM frame) are presented in this paper

Contributions to process monitoring by laser-induced breakdown spectroscopy

Science.gov (United States)

Rusak, David Alexander

1998-12-01

When a pulsed laser of sufficient energy and pulse duration is brought to a focus, multi-photon ionization creates free electrons in the focal volume. These electrons are accelerated in a process known as inverse Bremsstrahlung and cause collisional ionization of species in the focal volume. More charge carriers are produced and the process continues for the duration of the laser pulse. The manifestation of this process is a visible spark or plasma which typically lasts for tens of microseconds. This laser-induced plasma can serve as a source in an atomic emission experiment. Because the composition of the plasma is determined in large part by the environment in which it forms, elements in the laser target can be determined spectroscopically. The goal of a laser-induced breakdown spectroscopy (LIBS) experiment is to establish a relationship between the concentration of an element of interest in the target and the intensity of light emitted from the laser-induced plasma at a wavelength characteristic of that element. Because LIBS requires only optical access to the sample and can perform elemental determinations in solids, liquids, or gases with little sample preparation, there is interest in using it as an on-line technique for process monitoring in a number of industrial applications. However, before the technique becomes useful in industrial applications, many issues regarding instrumentation and data analysis need to be addressed in the lab. The first two chapters of this dissertation provide, respectively, the basics of the atomic emission experiment and a background of laser-induced breakdown spectroscopy. The next two chapters examine the effect of target water content on the laser-induced plasma and the use of LIBS for analysis of aqueous samples. Chapter 5 describes construction of a fiber optic LIBS probe and its use to study temporal electron number density evolution in plasmas formed on different metals. Chapter 6 is a study of excitation, vibrational

Combination of laser-induced breakdown spectroscopy and Raman spectroscopy for multivariate classification of bacteria

Science.gov (United States)

Prochazka, D.; Mazura, M.; Samek, O.; Rebrošová, K.; Pořízka, P.; Klus, J.; Prochazková, P.; Novotný, J.; Novotný, K.; Kaiser, J.

2018-01-01

In this work, we investigate the impact of data provided by complementary laser-based spectroscopic methods on multivariate classification accuracy. Discrimination and classification of five Staphylococcus bacterial strains and one strain of Escherichia coli is presented. The technique that we used for measurements is a combination of Raman spectroscopy and Laser-Induced Breakdown Spectroscopy (LIBS). Obtained spectroscopic data were then processed using Multivariate Data Analysis algorithms. Principal Components Analysis (PCA) was selected as the most suitable technique for visualization of bacterial strains data. To classify the bacterial strains, we used Neural Networks, namely a supervised version of Kohonen's self-organizing maps (SOM). We were processing results in three different ways - separately from LIBS measurements, from Raman measurements, and we also merged data from both mentioned methods. The three types of results were then compared. By applying the PCA to Raman spectroscopy data, we observed that two bacterial strains were fully distinguished from the rest of the data set. In the case of LIBS data, three bacterial strains were fully discriminated. Using a combination of data from both methods, we achieved the complete discrimination of all bacterial strains. All the data were classified with a high success rate using SOM algorithm. The most accurate classification was obtained using a combination of data from both techniques. The classification accuracy varied, depending on specific samples and techniques. As for LIBS, the classification accuracy ranged from 45% to 100%, as for Raman Spectroscopy from 50% to 100% and in case of merged data, all samples were classified correctly. Based on the results of the experiments presented in this work, we can assume that the combination of Raman spectroscopy and LIBS significantly enhances discrimination and classification accuracy of bacterial species and strains. The reason is the complementarity in

Nuclear laser spectroscopy with on-line ion traps

International Nuclear Information System (INIS)

Wada, M.; Nakamura, T.; Ohtani, S.

1996-01-01

The hyperfine structure of atoms informs us various static characteristics of nuclei, particularly for electro-magnetic moments and their distributions. We have been developing an experimental method to perform laser-microwave double-resonance spectroscopy for the hyperfine structure of Be and Ca isotopes, including unstable nuclei. The purpose and the status of the experiments are described. (orig.)

Detection of early caries by laser-induced breakdown spectroscopy

Science.gov (United States)

Sasazawa, Shuhei; Kakino, Satoko; Matsuura, Yuji

2015-07-01

To improve sensitivity of dental caries detection by laser-induced breakdown spectroscopy (LIBS) analysis, it is proposed to utilize emission peaks in the ultraviolet. We newly focused on zinc whose emission peaks exist in ultraviolet because zinc exists at high concentration in the outer layer of enamel. It was shown that by using ratios between heights of an emission peak of Zn and that of Ca, the detection sensitivity and stability are largely improved. It was also shown that early caries are differentiated from healthy part by properly setting a threshold in the detected ratios. The proposed caries detection system can be applied to dental laser systems such as ones based on Er:YAG-lasers. When ablating early caries part by laser light, the system notices the dentist that the ablation of caries part is finished. We also show the intensity of emission peaks of zinc decreased with ablation with Er:YAG laser light.

Optical spectroscopy of laser-produced plasmas for standoff isotopic analysis

Energy Technology Data Exchange (ETDEWEB)

Harilal, Sivanandan S.; Brumfield, Brian E.; LaHaye, Nicole L.; Hartig, Kyle C.; Phillips, Mark C.

2018-04-20

This review article covers the present status of isotope detection through emission, absorption, and fluorescence spectroscopy of atoms and molecules in a laser-produced plasma formed from a solid sample. A description of the physics behind isotope shifts in atoms and molecules is presented, followed by the physics behind solid sampling of laser ablation plumes, optical methods for isotope measurements, the suitable physical conditions of laser-produced plasma plumes for isotopic analysis, and the current status. Finally, concluding remarks will be made on the existing gaps between previous works in the literature and suggestions for future work.

Diode laser spectroscopy of oxygen electronic band at 760 nm

International Nuclear Information System (INIS)

Lucchesini, A.; De Rosa, M.; Gozzini, S.

1998-01-01

Collisional broadening and shift coefficients have been obtained by analyzing the line shapes of oxygen absorptions in the 760 nm electronic band. By using a diode laser spectrometer with commercially available etherostructure Al x Ga 1-x As diode lasers operating in 'free-running mode', line shape parameters have been collected at room temperature by varying the gas pressure. A systematic study has been carried on seven absorption lines by scanning the diode laser emission wavelength around the gas resonances. The weak absorption lines have been detected by using the wavelength modulation (WM) spectroscopy technique with second-harmonic detection

Detection of elemental mercury by multimode diode laser correlation spectroscopy.

Science.gov (United States)

Lou, Xiutao; Somesfalean, Gabriel; Svanberg, Sune; Zhang, Zhiguo; Wu, Shaohua

2012-02-27

We demonstrate a method for elemental mercury detection based on correlation spectroscopy employing UV laser radiation generated by sum-frequency mixing of two visible multimode diode lasers. Resonance matching of the multimode UV laser is achieved in a wide wavelength range and with good tolerance for various operating conditions. Large mode-hops provide an off-resonance baseline, eliminating interferences from other gas species with broadband absorption. A sensitivity of 1 μg/m3 is obtained for a 1-m path length and 30-s integration time. The performance of the system shows promise for mercury monitoring in industrial applications.

Tunneling processes into localized subgap states in superconductors

Energy Technology Data Exchange (ETDEWEB)

Ruby, Michael; Heinrich, Benjamin W.; Franke, Katharina J. [Freie Universitaet Berlin, Arnimallee 14, 14195 Berlin (Germany); Pientka, Falko; Peng, Yang; Oppen, Felix von [Freie Universitaet Berlin, Arnimallee 14, 14195 Berlin (Germany); Dahlem Center for Complex Quantum Systems, Freie Universitaet Berlin, 14195 Berlin (Germany)

2016-07-01

The Yu-Shiba-Rusinov states bound by magnetic impurities in conventional s-wave superconductors are a simple model system for probing the competition between superconducting and magnetic correlations. Shiba states can be observed in scanning tunneling spectroscopy (STS) as a pair of resonances at positive and negative bias voltages in the superconducting gap. These resonances have been interpreted in terms of single-electron tunneling into the localized sub-gap states. This requires relaxation mechanisms that depopulate the state after an initial tunneling event. Recently, theory suggests that the current can also be carried by Andreev processes which resonantly transfer a Cooper pair into the superconductor. We performed high-resolution STS experiments on single adatom Shiba states on the superconductor Pb, and provide evidence for the existence of two transport regimes. The single-electron processes dominate at large tip-sample distances and small tunneling currents, whereas Andreev processes become important at stronger tunneling. Our conclusions are based on a careful comparison of experiment and theory.

Broadband high-resolution two-photon spectroscopy with laser frequency combs

OpenAIRE

Hipke, Arthur; Meek, Samuel A.; Ideguchi, Takuro; Hänsch, Theodor W.; Picqué, Nathalie

2013-01-01

Two-photon excitation spectroscopy with broad spectral span is demonstrated at Doppler-limited resolution. We describe first Fourier transform two-photon spectroscopy of an atomic sample with two mode-locked laser oscillators in a dual-comb technique. Each transition is uniquely identified by the modulation imparted by the interfering comb excitations. The temporal modulation of the spontaneous two-photon fluorescence is monitored with a single photodetector, and the spectrum is revealed by a...

Wavelength comparison for laser induced breakdown spectroscopy caries detection

Science.gov (United States)

Amaral, Marcello M.; Raele, Marcus P.; Ana, Patrícia A.; Núñez, Sílvia C.; Zamataro, Claudia B.; Zezell, Denise M.

2018-02-01

Laser Induced Breakdown Spectroscopy (LIBS) is a technique capable to perform elemental analyses of a variety of samples, independent of matter state. Other spectroscopy techniques may require a destructive and time-consuming sample preparation. On the other hand, LIBS is a less destructive technique with no (or considerably less) sample preparation, using a relatively simple experimental setup. LIBS also provides a multielement analysis into one single spectrum acquisition, applying a Nd:YAG short-pulsed laser to ensure the stoichiometry between the sample and the generated plasma. LIBS have been applied on the study of carious lesions using a Nd:YAG into its fundamental emission at 1064 nm. It was shown that ratio of P/Ca and Zn/Ca can be used to monitor the cariogenic process. Another minor elements, e.g. C and Cu, associated with bacteria biofilm were also measured with the Nd:YAG laser. The fundamental wavelength emission (1064 nm) of Nd:YAG is coincident with a hydroxyapatite transmission window and it may affect the result. In order to address this issue a study used the second harmonic of the Nd:YAG laser at 532 nm. It was show that it is also possible perform LIBS on carious lesion using the Nd:YAG at 532 nm. However, there is not a work direct comparing the LIBS at 532 nm and 1064 nm for carious lesion detection. So, the aim of this work was to investigate the influence of laser wavelength on the LIBS performance for carious lesion detection. In both cases the carious lesion was detected with the advantage of no interference with hydroxyapatite at 532 nm.

Laser spectroscopy of neutron deficient gold and platinum isotopes

International Nuclear Information System (INIS)

Savard, G.

1988-03-01

A new method for on-line laser spectroscopy of radioactive atoms based on the resonant ionization spectroscopy of laser-desorbed radioactive samples has been devised. An experimental setup has been installed on-line at the ISOCELE mass separator in Orsay (France) and experiments have been performed on the region of transitional nuclei around Z=79. Isotopic shift measurements on four new isotopes 194 Au, 196 Au, 198 Au, 199 Au have been performed on gold and results on the neutron deficient isotopes down to 186 Au have been obtained confirming the nuclear ground-state shape transition from oblate to prolate between 187 Au and 186 Au. The first isotopic shift measurements on radioactive platinum isotopes have been obtained on 186 Pt, 188 Pt, 189 Pt. Indications of a shape transition have been observed between 186 Pt and 188 Pt. The extracted experimental changes in mean square charge radii δ 2 > A,A' along isotopic chains are compared to self-consistent Hartree-Fock plus BCS calculations

Laser photodissociation and spectroscopy of mass-separated biomolecular ions

CERN Document Server

Polfer, Nicolas C

2014-01-01

This lecture notes book presents how enhanced structural information of biomolecular ions can be obtained from interaction with photons of specific frequency - laser light. The methods described in the book ""Laser photodissociation and spectroscopy of mass-separated biomolecular ions"" make use of the fact that the discrete energy and fast time scale of photoexcitation can provide more control in ion activation. This activation is the crucial process producing structure-informative product ions that cannot be generated with more conventional heating methods, such as collisional activation. Th

Collinear laser spectroscopy of manganese isotopes using optical pumping in ISCOOL

CERN Multimedia

Marsh, B A; Neyens, G; Flanagan, K; Rajabali, M M; Reponen, M; Campbell, P; Procter, T J

Recently, optical pumping of ions has been achieved inside an ion beam cooler-buncher. By illuminating the central axis of the cooler with laser light, subsequent decay populates selected ionic metastable states. This population enhancement is retained as the ion beam is delivered to an experimental station. In the case of collinear laser spectroscopy, transitions can then be excited from a preferred metastable level, rather than the ground-state. This proposal seeks to establish and develop the technique for ISCOOL. As a test of efficiency, this will be applied to the study of $^{55-66}$Mn isotopes using collinear laser spectroscopy-expanding an earlier study where the benefit of the technique was demonstrated. This will provide nuclear spins, magnetic-dipole and electric-quadrupole moments and changes in mean-square charge radii across N = 40 shell closure candidate and into a region where an onset of deformation, and a new "island of inversion" is predicted.

Sensing cocaine in saliva with infrared laser spectroscopy

Science.gov (United States)

Hans, Kerstin M.-C.; Müller, Matthias; Gianella, Michele; Wägli, Ph.; Sigrist, Markus W.

2013-02-01

Increasing numbers of accidents caused by drivers under the influence of drugs, raise drug tests to worldwide interest. We developed a one-step extraction technique for cocaine in saliva and analyzed reference samples with laser spectroscopy employing two different schemes. The first is based on attenuated total reflection (ATR), which is applied to dried samples. The second scheme uses transmission measurements for the analysis of liquid samples. ATR spectroscopy achieved a limit of detection (LOD) of 3μg/ml. The LOD for the transmission approach in liquid samples is cocaine. An improved stabilization of the set-up should lower the limit of detection significantly.

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

Epitaxial growth of Fe-based superconductor thin films

Energy Technology Data Exchange (ETDEWEB)

Meyer, Sven; Haenisch, Jens; Holzapfel, Bernhard [Institut fuer Technische Physik, Karlsruher Institut fuer Technologie, Hermann-von-Helmholtz-Platz 1, 76344 Eggenstein-Leopoldshafen (Germany)

2016-07-01

The Fe-based superconductors (FBS), discovered in 2008, are not only interesting for possible applications due to their large upper critical fields and low anisotropies, but also for basic understanding of unconventional superconductivity. With their properties, they constitute a link between the classic low-T{sub c} superconductors (low anisotropies, low thermal fluctuations, s-wave type symmetry) and the oxocuprates (T{sub c} up to 55 K, large H{sub c2}, unconventional pairing). Their multi-band nature reminds of MgB{sub 2}. We prepare thin films of FBS in the so called 122 family, namely Co- and P-doped BaFe{sub 2}As{sub 2} to investigate application relevant properties, such as critical current density J{sub c}, by pulsed laser deposition using a frequency-tripled Nd:YAG laser (λ = 355 nm). Microstructure and chemical composition will be investigated by XRD, AFM and SEM, and electrical transport using a 14 T PPMS. The results are compared to literature data on films grown at different wavelengths.

Laser systems for collinear spectroscopy and the charge radius of {sup 12}Be

Energy Technology Data Exchange (ETDEWEB)

Krieger, Andreas

2012-03-30

Collinear laser spectroscopy has been used to investigate the nuclear charge radii of shortlived medium- and heavy-Z nuclei for more than three decades. But it became only recently be applicable to low-Z nuclei. This region of the nuclear chart attracts attention because so-called ab-initio nuclear models, based on realistic nucleon-nucleon potentials, can only be applied to the lightest elements due to the rapidly increasing calculational demands with the number of nucleons. Furthermore, strong clusterization of atomic nuclei occurs and the encountered halo nuclei are presently subject of intense research. The isotopic chain of beryllium exhibits the prime example of a one-neutron halo nucleus, {sup 11}Be, and the two- or four-neutron halo nucleus {sup 14}Be. {sup 12}Be is a key isotope between these two exotic nuclei and particularly interesting because the nuclear shell model predicts a shell closure for the magic neutron number N = 8. In the course of this thesis, several frequency-stabilized laser systems for collinear laser spectroscopy have been developed. At TRIGA-SPEC a frequency-doubled diode laser system with a tapered amplifier and a frequency comb-stabilized titanium-sapphire laser with a frequency doubling stage are now available for the spectroscopy of refractory metals above molybdenum. They have already been used for test-experiments and commissioning of the TRIGA-LASER beamline. Furthermore, frequency-quadrupling of the Ti:Sa laser was demonstrated to expand the emitted wavelengths into the 200 nm region. At ISOLDE/CERN a frequency comb-stabilized and an iodine-stabilized dye laser were installed and applied for laser spectroscopy of {sup 9,10,11,12}Be{sup +}. The improved laser system and the development of a delayed photon-ion coincidence detection improved the sensitivity of the beryllium spectroscopy by more than two orders of magnitude and, thus, the previous measurements of {sup 7-11}Be could be extended for the first time to the short

Trace gas absorption spectroscopy using laser difference-frequency spectrometer for environmental application

Science.gov (United States)

Chen, W.; Cazier, F.; Boucher, D.; Tittel, F. K.; Davies, P. B.

2001-01-01

A widely tunable infrared spectrometer based on difference frequency generation (DFG) has been developed for organic trace gas detection by laser absorption spectroscopy. On-line measurements of concentration of various hydrocarbons, such as acetylene, benzene, and ethylene, were investigated using high-resolution DFG trace gas spectroscopy for highly sensitive detection.

Dual-wavelength external cavity laser device for fluorescence suppression in Raman spectroscopy

Science.gov (United States)

Zhang, Xuting; Cai, Zhijian; Wu, Jianhong

2017-10-01

Raman spectroscopy has been widely used in the detection of drugs, pesticides, explosives, food additives and environmental pollutants, for its characteristics of fast measurement, easy sample preparation, and molecular structure analyzing capability. However, fluorescence disturbance brings a big trouble to these applications, with strong fluorescence background covering up the weak Raman signals. Recently shifted excitation Raman difference spectroscopy (SERDS) not only can completely remove the fluorescence background, but also can be easily integrated into portable Raman spectrometers. Usually, SERDS uses two lasers with small wavelength gap to excite the sample, then acquires two spectra, and subtracts one to the other to get the difference spectrum, where the fluorescence background will be rejected. So, one key aspects of successfully applying SERDS method is to obtain a dual-wavelength laser source. In this paper, a dual-wavelength laser device design based on the principles of external cavity diode laser (ECDL) is proposed, which is low-cost and compact. In addition, it has good mechanical stability because of no moving parts. These features make it an ideal laser source for SERDS technique. The experiment results showed that the device can emit narrow-spectral-width lasers of two wavelengths, with the gap smaller than 2 nanometers. The laser power corresponding to each wavelength can be up to 100mW.

Diffusion of nonequilibrium quasi-particles in a cuprate superconductor

International Nuclear Information System (INIS)

Gedik, N.; Orenstein, J.; Liang, Ruixing; Bonn, D.A.; Hardy, W.N.

2003-01-01

We report a transport study of nonequilibrium quasi-particles in a high-transition-temperature cuprate superconductor using the transient grating technique. Low-intensity laser excitation (at a photon energy of 1.5 electron volts) was used to introduce a spatially periodic density of quasi-particles into a high-quality untwinned single crystal of YBa2Cu3O6.5. Probing the evolution of the initial density through space and time yielded the quasi-particle diffusion coefficient and the inelastic and elastic scattering rates. The technique reported here is potentially applicable to precision measurements of quasi-particle dynamics not only in cuprate superconductors but in other electronic systems as well

Applications of Cr:ZnSe and Cr:ZnS lasers to ultrabroadband high-resolution spectroscopy

International Nuclear Information System (INIS)

Sorokin, E.; Sorokina, I.; Picque, N.; Guelachvili, G.

2006-01-01

Full text: Cr 2+ :ZnSe laser, and since recently also the Cr 2+ :ZnS laser proved to be versatile laser sources for trace gas measurements in the whole range between 2 and 3.1 μm. Among the existing methods of sensitive gas detection, intracavity laser absorption spectroscopy (ICLAS) offers some distinct advantages such as the simultaneous coverage of a broad spectral domain and large dynamic range. Under ICLAS the absorbing medium is put inside a laser cavity with broadband gain. As a result, the laser cavity acts as a multipass cell. Equivalent absorption path length of tens of kilometers can be achieved, corresponding to high detection sensitivities of the order of 10 -8 cm -1 and better. Only few examples of ICLAS spectrometers were demonstrated beyond 2 μm. Among them are: KCl:Li Fa(II) color center laser with coverage up to 4 nm at 2638 nm, Co:MgF 2 , covering up to 30 nm around 2040 and 2245 nm, Tm:YAG with coverage up to 35 nm at 2030 nm, and pulsed Cr:ZnSe, with coverage up to 50 nmat 2500 nm. In this talk we discuss application of a Cr 2+ :ZnSe laser to high-resolution and high-sensitivity intracavity absorption spectroscopy (ICLAS) analyzed by time-resolved Fourier transform spectroscopy. This represents the extreme limit presently reached in the infrared by ICLAS with Doppler limited resolution. Our most recent works concern application of a Cr 2+ :ZnS laser for broadband ultrasensitive intracavity laser spectroscopy (ICLAS), with effective absorption path up to about 50 km in the 2.4 μm range. The spectrometer operates with both Er-fiber and direct diode pumping in the very interesting water-free window between ∼ 2.1 and 2.5 μm. The sensitivity of 2 x 10 -9 cm -1 at Doppler-limited resolution allows obtaining spectral information that was previously unreachable in laboratory conditions. Summarizing, intracavity laser spectroscopy technique has been successfully used for measuring and detecting gas constituents with extreme sensitivity and

Analysis of organic vapors with laser induced breakdown spectroscopy

Energy Technology Data Exchange (ETDEWEB)

Nozari, Hadi; Tavassoli, Seyed Hassan [Laser and Plasma Research Institute, Shahid Beheshti University, G. C, 1983963113 Evin, Tehran (Iran, Islamic Republic of); Rezaei, Fatemeh, E-mail: fatemehrezaei@kntu.ac.ir [Department of Physics, K. N. Toosi University of Technology, 15875-4416 Shariati, Tehran (Iran, Islamic Republic of)

2015-09-15

In this paper, laser induced breakdown spectroscopy (LIBS) is utilized in the study of acetone, ethanol, methanol, cyclohexane, and nonane vapors. Carbon, hydrogen, oxygen, and nitrogen atomic emission spectra have been recorded following laser-induced breakdown of the organic vapors that are mixed with air inside a quartz chamber at atmospheric pressure. The plasma is generated with focused, Q-switched Nd:YAG radiation at the wavelength of 1064 nm. The effects of ignition and vapor pressure are discussed in view of the appearance of the emission spectra. The recorded spectra are proportional to the vapor pressure in air. The hydrogen and oxygen contributions diminish gradually with consecutive laser-plasma events without gas flow. The results show that LIBS can be used to characterize organic vapor.

Analysis of organic vapors with laser induced breakdown spectroscopy

International Nuclear Information System (INIS)

Nozari, Hadi; Tavassoli, Seyed Hassan; Rezaei, Fatemeh

2015-01-01

In this paper, laser induced breakdown spectroscopy (LIBS) is utilized in the study of acetone, ethanol, methanol, cyclohexane, and nonane vapors. Carbon, hydrogen, oxygen, and nitrogen atomic emission spectra have been recorded following laser-induced breakdown of the organic vapors that are mixed with air inside a quartz chamber at atmospheric pressure. The plasma is generated with focused, Q-switched Nd:YAG radiation at the wavelength of 1064 nm. The effects of ignition and vapor pressure are discussed in view of the appearance of the emission spectra. The recorded spectra are proportional to the vapor pressure in air. The hydrogen and oxygen contributions diminish gradually with consecutive laser-plasma events without gas flow. The results show that LIBS can be used to characterize organic vapor

Tunneling spectroscopy on grain boundary junctions in electron-doped high-temperature superconductors; Tunnelspektroskopie an Korngrenzenkontakten aus elektronendotierten Hochtemperatur-Supraleitern

Energy Technology Data Exchange (ETDEWEB)

Welter, B.

2007-12-07

Some methods are developed anf presented, by means of which from experimental tunnel spectra, especially on symmetric SIS contacts, informations about the properties of electrodes and tunnel barriers can be obtained. Especially a procedure for the numerical unfolding of symmetric SIS spectra is proposed. Furthermore a series of models is summarized, which can explain the linear background conductivity observed in many spectra on high-temperature superconductors. The results of resistance measurements on film bridges are presented. Especially different methods for the determination of H{sub c2}(T) respectively H{sub c2}(0) are presented and applied to the experimental data. Finally the results of the tunnel-spectroscopy measurements are shown.

Apparatus, system, and method for laser-induced breakdown spectroscopy

Science.gov (United States)

Effenberger, Jr., Andrew J; Scott, Jill R; McJunkin, Timothy R

2014-11-18

In laser-induced breakdown spectroscopy (LIBS), an apparatus includes a pulsed laser configured to generate a pulsed laser signal toward a sample, a constructive interference object and an optical element, each located in a path of light from the sample. The constructive interference object is configured to generate constructive interference patterns of the light. The optical element is configured to disperse the light. A LIBS system includes a first and a second optical element, and a data acquisition module. The data acquisition module is configured to determine an isotope measurement based, at least in part, on light received by an image sensor from the first and second optical elements. A method for performing LIBS includes generating a pulsed laser on a sample to generate light from a plasma, generating constructive interference patterns of the light, and dispersing the light into a plurality of wavelengths.

High-speed high-sensitivity infrared spectroscopy using mid-infrared swept lasers (Conference Presentation)

Science.gov (United States)

Childs, David T. D.; Groom, Kristian M.; Hogg, Richard A.; Revin, Dmitry G.; Cockburn, John W.; Rehman, Ihtesham U.; Matcher, Stephen J.

2016-03-01

Infrared spectroscopy is a highly attractive read-out technology for compositional analysis of biomedical specimens because of its unique combination of high molecular sensitivity without the need for exogenous labels. Traditional techniques such as FTIR and Raman have suffered from comparatively low speed and sensitivity however recent innovations are challenging this situation. Direct mid-IR spectroscopy is being speeded up by innovations such as MEMS-based FTIR instruments with very high mirror speeds and supercontinuum sources producing very high sample irradiation levels. Here we explore another possible method - external cavity quantum cascade lasers (EC-QCL's) with high cavity tuning speeds (mid-IR swept lasers). Swept lasers have been heavily developed in the near-infrared where they are used for non-destructive low-coherence imaging (OCT). We adapt these concepts in two ways. Firstly by combining mid-IR quantum cascade gain chips with external cavity designs adapted from OCT we achieve spectral acquisition rates approaching 1 kHz and demonstrate potential to reach 100 kHz. Secondly we show that mid-IR swept lasers share a fundamental sensitivity advantage with near-IR OCT swept lasers. This makes them potentially able to achieve the same spectral SNR as an FTIR instrument in a time x N shorter (N being the number of spectral points) under otherwise matched conditions. This effect is demonstrated using measurements of a PDMS sample. The combination of potentially very high spectral acquisition rates, fundamental SNR advantage and the use of low-cost detector systems could make mid-IR swept lasers a powerful technology for high-throughput biomedical spectroscopy.

Characterization of hard coatings produced by laser cladding using laser-induced breakdown spectroscopy technique

Science.gov (United States)

Varela, J. A.; Amado, J. M.; Tobar, M. J.; Mateo, M. P.; Yañez, A.; Nicolas, G.

2015-05-01

Protective coatings with a high abrasive wear resistance can be obtained from powders by laser cladding technique, in order to extend the service life of some industrial components. In this work, laser clad layers of self-fluxing NiCrBSi alloy powder mixed with WC powder have been produced on stainless steel substrates of austenitic type (AISI 304) in a first step and then chemically characterized by laser-induced breakdown spectroscopy (LIBS) technique. With the suitable laser processing parameters (mainly output power, beam scan speed and flow rate) and powders mixture proportions between WC ceramics and NiCrBSi alloys, dense pore free layers have been obtained on single tracks and on large areas with overlapped tracks. The results achieved by LIBS technique and applied for the first time to the analysis of laser clads provided the chemical composition of the tungsten carbides in metal alloy matrix. Different measurement modes (multiple point analyses, depth profiles and chemical maps) have been employed, demonstrating the usefulness of LIBS technique for the characterization of laser clads based on hardfacing alloys. The behavior of hardness can be explained by LIBS maps which evidenced the partial dilution of some WC spheres in the coating.

High resolution laser spectroscopy as a diagnostic tool in beams

International Nuclear Information System (INIS)

Bergmann, K.; Hefter, U.; Hering, P.

1977-01-01

The combination of high resolution laser spectroscopy with the technique of molecular beams allows a very detailed beam research since molecules or atoms in specific quantum states can be sampled yielding previously unavailable sources of data. In these experiments a Na/Na 2 beam emerges from a 0.2 mm nozzle and is collimated by a 2 mm wide slit 50 cm downstream. To probe the molecules a single mode Ar + -laser was used which can be tuned within the gain profile of the laser line (8 GHz) to several transitions between specific levels in the ground state and second electronically excited state of the Na 2 molecule. (Auth.)

Laser-induced breakdown spectroscopy of tantalum plasma

International Nuclear Information System (INIS)

Khan, Sidra; Bashir, Shazia; Hayat, Asma; Khaleeq-ur-Rahman, M.; Faizan–ul-Haq

2013-01-01

Laser Induced Breakdown spectroscopy (LIBS) of Tantalum (Ta) plasma has been investigated. For this purpose Q-switched Nd: YAG laser pulses (λ∼ 1064 nm, τ∼ 10 ns) of maximum pulse energy of 100 mJ have been employed as an ablation source. Ta targets were exposed under the ambient environment of various gases of Ar, mixture (CO 2 : N 2 : He), O 2 , N 2 , and He under various filling pressure. The emission spectrum of Ta is observed by using LIBS spectrometer. The emission intensity, excitation temperature, and electron number density of Ta plasma have been evaluated as a function of pressure for various gases. Our experimental results reveal that the optical emission intensity, the electron temperature and density are strongly dependent upon the nature and pressure of ambient environment. The SEM analysis of the ablated Ta target has also been carried out to explore the effect of ambient environment on the laser induced grown structures. The growth of grain like structures in case of molecular gases and cone-formation in case of inert gases is observed. The evaluated plasma parameters by LIBS analysis such as electron temperature and the electron density are well correlated with the surface modification of laser irradiated Ta revealed by SEM analysis

Laser-induced breakdown spectroscopy of tantalum plasma

Energy Technology Data Exchange (ETDEWEB)

Khan, Sidra; Bashir, Shazia; Hayat, Asma; Khaleeq-ur-Rahman, M.; Faizan–ul-Haq [Centre for Advanced Studies in Physics, GC University, Lahore (Pakistan)

2013-07-15

Laser Induced Breakdown spectroscopy (LIBS) of Tantalum (Ta) plasma has been investigated. For this purpose Q-switched Nd: YAG laser pulses (λ∼ 1064 nm, τ∼ 10 ns) of maximum pulse energy of 100 mJ have been employed as an ablation source. Ta targets were exposed under the ambient environment of various gases of Ar, mixture (CO{sub 2}: N{sub 2}: He), O{sub 2}, N{sub 2}, and He under various filling pressure. The emission spectrum of Ta is observed by using LIBS spectrometer. The emission intensity, excitation temperature, and electron number density of Ta plasma have been evaluated as a function of pressure for various gases. Our experimental results reveal that the optical emission intensity, the electron temperature and density are strongly dependent upon the nature and pressure of ambient environment. The SEM analysis of the ablated Ta target has also been carried out to explore the effect of ambient environment on the laser induced grown structures. The growth of grain like structures in case of molecular gases and cone-formation in case of inert gases is observed. The evaluated plasma parameters by LIBS analysis such as electron temperature and the electron density are well correlated with the surface modification of laser irradiated Ta revealed by SEM analysis.

Probing superconductors. Spectroscopic-imaging scanning tunneling microscopy

International Nuclear Information System (INIS)

Hanaguri, Tetsuo

2011-01-01

Discovery of high-temperature superconductivity in a cuprate triggered developments of various spectroscopic tools which have been utilized to elucidate electronic states of this mysterious compound. Particularly, angle-resolved photoemission spectroscopy and scanning-tunneling microscopy/spectroscopy are improved considerably. It is now possible to map the superconducting gap in both momentum and real spaces using these two techniques. Here we review spectroscopic-imaging scanning tunneling microscopy which is able to explore momentum-space phase structure of the superconducting gap, as well as real-space structure. Applications of this technique to a cuprate and an iron-based superconductor are discussed. (author)

Novel nuclear laser spectroscopy method using superfluid helium for measurement of spins and moments of exotic nuclei

International Nuclear Information System (INIS)

Furukawa, Takeshi; Wakui, Takashi; Yang, Xiaofei; Fujita, Tomomi; Imamura, Kei; Yamaguchi, Yasuhiro; Tetsuka, Hiroki; Tsutsui, Yoshiki; Mitsuya, Yosuke; Ichikawa, Yuichi; Ishibashi, Yoko; Yoshida, Naoki; Shirai, Hazuki; Ebara, Yuta; Hayasaka, Miki; Arai, Shino; Muramoto, Sosuke

2013-01-01

Highlights: • Development of a novel nuclear laser spectroscopy method using superfluid helium. • Observation of the Zeeman resonance with the 85 Rb beam introduced into helium. • Demonstration of deducing the nuclear spins from the observed resonance spectrum. -- Abstract: We have been developing a novel nuclear laser spectroscopy method “OROCHI” for determining spins and moments of exotic radioisotopes. In this method, we use superfluid helium as a stopping material of energetic radioisotope beams and then stopped radioisotope atoms are subjected to in situ laser spectroscopy in superfluid helium. To confirm the feasibility of this method for rare radioisotopes, we carried out a test experiment using a 85 Rb beam. In this experiment, we have successfully measured the Zeeman resonance signals from the 85 Rb atoms stopped in superfluid helium by laser-RF double resonance spectroscopy. This method is efficient for the measurement of spins and moments of more exotic nuclei

Time resolved optical emission spectroscopy of cross-beam pulsed laser ablation on graphite targets

International Nuclear Information System (INIS)

Sangines, R.; Sanchez Ake, C.; Sobral, H.; Villagran-Muniz, M.

2007-01-01

Cross-beam pulsed laser ablation with two delayed lasers is performed on two perpendicular graphite targets. The time delay between lasers is varied by up to 5 μs, and physical changes on the second plasma, due to the interaction with the first generated one, are determined by time resolved optical emission spectroscopy

Briefing on superconductor developments

International Nuclear Information System (INIS)

Larbalestier, D.

1987-01-01

In this paper, the author covers the technology of the new oxide superconductors and how they might relate to the existing superconductors. He discusses old-fashioned superconductors; the material science of superconductors; the new oxide superconductors; and the future of oxide superconductors. 13 figures, 1 table

S-I-N tunneling spectroscopy of MgB2 superconductor: evidence of two superconducting energy gaps

International Nuclear Information System (INIS)

Sen, Shashwati; Aswal, D.K.; Singh, Ajay; Gadkari, S.C.; Shah, K.; Gupta, S.K.; Sahni, V.C.

2002-01-01

The tunneling spectra of polycrystalline MgB 2 , have been recorded, at different temperatures between 29 K and T c , using planar superconductor- insulating-normal (S-I-N) tunneling spectroscopy. The planar S-I-N tunnel junctions have been fabricated by thermally evaporating Ag electrodes on MgB 2 surface. The naive layer, which forms at the surface of MgB 2 , due to atmospheric degradation, was employed as an insulating layer between Ag electrodes and MgB 2 . We have found presence of two clear superconducting energy gaps in MgB 2 . The magnitudes of these gaps at 29.5 K are 1.8 and 5.9 MeV, respectively. In the vicinity of T c , while larger energy gap obeyed BCS temperature dependence, the smaller energy gap deviated from BCS dependence. All the spectra exhibited zero-bias conductance, which decreased linearly with temperature and vanished at T c . (author)

Metastable Magnesium fluorescence spectroscopy using a frequency-stabilized 517 nm laser

DEFF Research Database (Denmark)

He, Ming; Jensen, Brian B; Therkildsen, Kasper T

2009-01-01

We present a laser operating at 517 nm for our Magnesium laser-cooling and atomic clock project. A two-stage Yb-doped fiber amplifier (YDFA) system generates more than 1.5 W of 1034 nm light when seeded with a 15 mW diode laser. Using a periodically poled lithium niobate (PPLN) waveguide, we obta...... obtained more than 40 mW of 517 nm output power by single pass frequency doubling. In addition, fluorescence spectroscopy of metastable magnesium atoms could be used to stabilize the 517 nm laser to an absolute frequency within 1 MHz.......We present a laser operating at 517 nm for our Magnesium laser-cooling and atomic clock project. A two-stage Yb-doped fiber amplifier (YDFA) system generates more than 1.5 W of 1034 nm light when seeded with a 15 mW diode laser. Using a periodically poled lithium niobate (PPLN) waveguide, we...

Laser Ultrasound Spectroscopy Scanning for 3D Printed Parts

Energy Technology Data Exchange (ETDEWEB)

Brennan, Guendalyn Kendra [Los Alamos National Lab. (LANL), Los Alamos, NM (United States)

2017-08-04

One of the challenges of additive manufacturing is quality control due to the possibility of unseen flaws in the final product. The current methods of inspection are lacking in detail, too slow for practical use, or unable to validate internal structure. This report examines the use of laser ultrasound spectroscopy in layer by layer scans of 3D printed parts as they are created. The result is fast and detailed quality control. An additional advantage of this method is the ability to cancel a print as soon as a defect is detected, therefore saving materials and time. This technique, though simple in concept, has been a challenge to implement. I discuss tweaking the 3D printer configuration, and finding the optimal settings for laser scanning small parts made of ABS plastic, as well as the limits of how small of a detail the laser can detect. These settings include the frequency of the ultrasonic transducer, the speed of the laser, and the distance from the laser to the part.

Laser frequency stabilization and shifting by using modulation transfer spectroscopy

Science.gov (United States)

Cheng, Bing; Wang, Zhao-Ying; Wu, Bin; Xu, Ao-Peng; Wang, Qi-Yu; Xu, Yun-Fei; Lin, Qiang

2014-10-01

The stabilizing and shifting of laser frequency are very important for the interaction between the laser and atoms. The modulation transfer spectroscopy for the 87Rb atom with D2 line transition F = 2 → F' = 3 is used for stabilizing and shifting the frequency of the external cavity grating feedback diode laser. The resonant phase modulator with electro—optical effect is used to generate frequency sideband to lock the laser frequency. In the locking scheme, circularly polarized pump- and probe-beams are used. By optimizing the temperature of the vapor, the pump- and probe-beam intensity, the laser linewidth of 280 kHz is obtained. Furthermore, the magnetic field generated by a solenoid is added into the system. Therefore the system can achieve the frequency locking at any point in a range of hundreds of megahertz frequency shifting with very low power loss.

MgB2 energy gap determination by scanning tunnelling spectroscopy

International Nuclear Information System (INIS)

Heitmann, T W; Bu, S D; Kim, D M; Choi, J H; Giencke, J; Eom, C B; Regan, K A; Rogado, N; Hayward, M A; He, T; Slusky, J S; Khalifah, P; Haas, M; Cava, R J; Larbalestier, D C; Rzchowski, M S

2004-01-01

We report scanning tunnelling spectroscopy (STS) measurements of the gap properties of both ceramic MgB 2 and c-axis oriented epitaxial MgB 2 thin films. Both show a temperature dependent zero bias conductance peak and evidence for two superconducting gaps. We report tunnelling spectroscopy of superconductor-insulator-superconductor (S-I-S) junctions formed in two ways in addition to normal metal-insulator-superconductor (N-I-S) junctions. We find a gap δ = 2.2-2.8 meV, with spectral features and temperature dependence that are consistent between S-I-S junction types. In addition, we observe evidence of a second, larger gap, δ 7.2 meV, consistent with a proposed two-band model

A comparative study of the laser induce breakdown spectroscopy in single- and double-pulse laser geometry

International Nuclear Information System (INIS)

Sun Duixiong; Su Maogen; Dong Chenzhong; Wen Guanhong; Cao Xiangnian

2013-01-01

A time resolved laser induced breakdown spectroscopy technique (LIBS) was used for the investigation of emission signal enhancement on double-pulse LIBS. Two Q-switched Nd:YAG lasers at 1064 nm wavelength have been employed to generate laser-induced plasma on aluminium-based alloys. The plasma emission signals were recorded by spectrometer with ICCD detector. Spectral response calibration was performed by using deuterium and tungsten halogen lamps. Time evolution of the plasma temperature and electron density was investigated in SP and DP experiments. Based on the investigation of plasma parameters, the enhancements of emission line intensities were investigated, and the mechanisms of it were discussed. (author)

Laser-Induced Breakdown Spectroscopy (LIBS) for Monitoring the Formation of Hydroxyapatite Porous Layers

OpenAIRE

Sola, Daniel; Paulés, Daniel; Grima, Lorena; Anzano, Jesús

2017-01-01

Laser-induced breakdown spectroscopy (LIBS) is applied to characterize the formation of porous hydroxyapatite layers on the surface of 0.8CaSiO3-0.2Ca3(PO4)2 biocompatible eutectic glass immersed in simulated body fluid (SBF). Compositional and structural characterization analyses were also conducted by field emission scanning electron microscopy (FESEM), energy dispersive X-ray spectroscopy (EDX), and micro-Raman spectroscopy.

The influence of laser-particle interaction in laser induced breakdown spectroscopy and laser ablation inductively coupled plasma spectrometry

International Nuclear Information System (INIS)

Lindner, Helmut; Loper, Kristofer H.; Hahn, David W.; Niemax, Kay

2011-01-01

Particles produced by previous laser shots may have significant influence on the analytical signal in laser-induced breakdown spectroscopy (LIBS) and laser ablation inductively coupled plasma (LA-ICP) spectrometry if they remain close to the position of laser sampling. The effects of these particles on the laser-induced breakdown event are demonstrated in several ways. LIBS-experiments were conducted in an ablation cell at atmospheric conditions in argon or air applying a dual-pulse arrangement with orthogonal pre-pulse, i.e., plasma breakdown in a gas generated by a focussed laser beam parallel and close to the sample surface followed by a delayed crossing laser pulse in orthogonal direction which actually ablates material from the sample and produces the LIBS plasma. The optical emission of the LIBS plasma as well as the absorption of the pre-pulse laser was measured. In the presence of particles in the focus of the pre-pulse laser, the plasma breakdown is affected and more energy of the pre-pulse laser is absorbed than without particles. As a result, the analyte line emission from the LIBS plasma of the second laser is enhanced. It is assumed that the enhancement is not only due to an increase of mass ablated by the second laser but also to better atomization and excitation conditions favored by a reduced gas density in the pre-pulse plasma. Higher laser pulse frequencies increase the probability of particle-laser interaction and, therefore, reduce the shot-to-shot line intensity variation as compared to lower particle loadings in the cell. Additional experiments using an aerosol chamber were performed to further quantify the laser absorption by the plasma in dependence on time both with and without the presence of particles. The overall implication of laser-particle interactions for LIBS and LA-ICP-MS/OES are discussed.

The influence of laser-particle interaction in laser induced breakdown spectroscopy and laser ablation inductively coupled plasma spectrometry

Science.gov (United States)

Lindner, Helmut; Loper, Kristofer H.; Hahn, David W.; Niemax, Kay

2011-02-01

Particles produced by previous laser shots may have significant influence on the analytical signal in laser-induced breakdown spectroscopy (LIBS) and laser ablation inductively coupled plasma (LA-ICP) spectrometry if they remain close to the position of laser sampling. The effects of these particles on the laser-induced breakdown event are demonstrated in several ways. LIBS-experiments were conducted in an ablation cell at atmospheric conditions in argon or air applying a dual-pulse arrangement with orthogonal pre-pulse, i.e., plasma breakdown in a gas generated by a focussed laser beam parallel and close to the sample surface followed by a delayed crossing laser pulse in orthogonal direction which actually ablates material from the sample and produces the LIBS plasma. The optical emission of the LIBS plasma as well as the absorption of the pre-pulse laser was measured. In the presence of particles in the focus of the pre-pulse laser, the plasma breakdown is affected and more energy of the pre-pulse laser is absorbed than without particles. As a result, the analyte line emission from the LIBS plasma of the second laser is enhanced. It is assumed that the enhancement is not only due to an increase of mass ablated by the second laser but also to better atomization and excitation conditions favored by a reduced gas density in the pre-pulse plasma. Higher laser pulse frequencies increase the probability of particle-laser interaction and, therefore, reduce the shot-to-shot line intensity variation as compared to lower particle loadings in the cell. Additional experiments using an aerosol chamber were performed to further quantify the laser absorption by the plasma in dependence on time both with and without the presence of particles. The overall implication of laser-particle interactions for LIBS and LA-ICP-MS/OES are discussed.

Selective laser spectroscopy of molecules and ions in solids: a history, fundamentals and applications

Science.gov (United States)

Sapozhnikov, Michael

2018-03-01

A history of the development of selective laser spectroscopy is presented, beginning with a pioneering work by Yu. V. Denisov and V. A. Kizel in 1967, who were the first to demonstrate the possibility of removing the inhomogeneous broadening of luminescence spectra of impurity ions in glasses upon monochromatic resonance excitation. Selective excitation of optical centers can be achieved due to existence of zero-phonon transitions corresponding to narrow homogeneous zero-phonon lines in the spectra of impurity centers in solids, which are hidden in broad inhomogeneous optical bands upon usual nonselective excitation. The fundamentals of zero-phonon transition spectroscopy are considered and the mechanism of removing the inhomogeneous broadening of optical spectra of ions and molecules in crystals and amorphous solids under selective laser excitation of luminescence and persistent hole burning in absorption spectra is presented in detail. Various applications of selective laser spectroscopy for fundamental and applied studies are discussed.

Development and Optical Testing of the Camera, Hand Lens, and Microscope Probe with Scannable Laser Spectroscopy (CHAMP-SLS)

Science.gov (United States)

Mungas, Greg S.; Gursel, Yekta; Sepulveda, Cesar A.; Anderson, Mark; La Baw, Clayton; Johnson, Kenneth R.; Deans, Matthew; Beegle, Luther; Boynton, John

2008-01-01

Conducting high resolution field microscopy with coupled laser spectroscopy that can be used to selectively analyze the surface chemistry of individual pixels in a scene is an enabling capability for next generation robotic and manned spaceflight missions, civil, and military applications. In the laboratory, we use a range of imaging and surface preparation tools that provide us with in-focus images, context imaging for identifying features that we want to investigate at high magnification, and surface-optical coupling that allows us to apply optical spectroscopic analysis techniques for analyzing surface chemistry particularly at high magnifications. The camera, hand lens, and microscope probe with scannable laser spectroscopy (CHAMP-SLS) is an imaging/spectroscopy instrument capable of imaging continuously from infinity down to high resolution microscopy (resolution of approx. 1 micron/pixel in a final camera format), the closer CHAMP-SLS is placed to a feature, the higher the resultant magnification. At hand lens to microscopic magnifications, the imaged scene can be selectively interrogated with point spectroscopic techniques such as Raman spectroscopy, microscopic Laser Induced Breakdown Spectroscopy (micro-LIBS), laser ablation mass-spectrometry, Fluorescence spectroscopy, and/or Reflectance spectroscopy. This paper summarizes the optical design, development, and testing of the CHAMP-SLS optics.

Laser Cleaning and Spectroscopy: A Synergistic Approach in the Conservation of a Modern Painting

International Nuclear Information System (INIS)

Melessanaki, K.; Fotakis, C.; Anglos, D.; Stringari, C.; Solomon, R.

2006-01-01

We present results from preliminary laser cleaning studies performed on a 20th century modern painting, in which laser-induced breakdown spectroscopy (LIBS) was employed for monitoring the progress of material removal. This synergistic approach, that combines laser ablation cleaning with spectroscopic control, is of obvious importance as it offers a reliable means of ensuring proper conservation and could be the basis of a standard protocol for laser-based restoration procedures.

Laser induced breakdown spectroscopy library for the Martian environment

International Nuclear Information System (INIS)

Cousin, A.; Forni, O.; Maurice, S.; Gasnault, O.

2011-01-01

The NASA Mars Science Laboratory rover will carry the first Laser Induced Breakdown Spectroscopy experiment in space: ChemCam. We have developed a laboratory model which mimics ChemCam's main characteristics. We used a set of target samples relevant to Mars geochemistry, and we recorded individual spectra. We propose a data reduction scheme for Laser Induced Breakdown Spectroscopy data incorporating de-noising, continuum removal, and peak fitting. Known effects of the Martian atmosphere are confirmed with our experiment: better Signal-to-Noise Ratio on Mars compared to Earth, narrower peak width, and essentially no self-absorption. The wavelength shift of emission lines from air to Mars pressure is discussed. The National Institute of Standards and Technology vacuum database is used for wavelength calibration and to identify the elemental lines. Our Martian database contains 1336 lines for 32 elements: H, Li, Be, B, C, N, O, F, Na, Mg, Al, Si, P, S, Cl, K, Ar, Ca, Ti, V, Cr, Mn, Fe, Ni, Cu, Zn, As, Rb, Sr, Cs, Ba, and Pb. It is a subset of the National Institute of Standards and Technology database to be used for Martian geochemistry. Finally, synthetic spectra can be built from the Martian database. Correlation calculations help to distinguish between elements in case of uncertainty. This work is used to create tools and support data for the interpretation of ChemCam results. - Highlights: ► Chemcam: first Laser Induced Breakdown Spectroscopy technique on Mars. ► Creation of a LIBS specific database to ChemCam on Mars. ► Data reduction scheme is proposed. ► Best signal under Martian conditions. ► LIBS emission lines database: subset of NIST database for Martian geochemistry.

RFQ beam cooler and buncher for collinear laser spectroscopy of rare isotopes

Science.gov (United States)

Barquest, B. R.; Bollen, G.; Mantica, P. F.; Minamisono, K.; Ringle, R.; Schwarz, S.; Sumithrarachchi, C. S.

2017-09-01

A radiofrequency quadrupole (RFQ) ion beam cooler and buncher has been developed to deliver bunched beams with low transverse emittance, energy spread, and time spread to the BECOLA collinear laser spectroscopy system at the National Superconducting Cyclotron Laboratory (NSCL) at Michigan State University. The beam cooler and buncher contains new features which enhance performance, especially for high count rate beams, as well as simplifying construction, maintenance, and operation. The transverse emittance, energy spread, and time spread of the bunched beam, as well as buncher efficiency are reported, showcasing the capabilities of the BECOLA facility to perform collinear laser spectroscopy measurements with bunched rare isotope beams at NSCL and at the future Facility for Rare Isotope Beams (FRIB).

Analysis of relaxing laser-induced plasmas by absorption spectroscopy: Toward a new quantitative diagnostic technique

International Nuclear Information System (INIS)

Ribiere, M.; Cheron, B.G.

2010-01-01

Broad-band near UV absorption spectroscopy was used to analyze atmospheric laser-induced plasmas formed on metallic and refractory targets. When the common emission spectroscopy only provides the density of the radiating atomic excited states, the technique reported in this paper is able to achieve high spatial resolution in the measurement of absolute number densities in expanding laser-induced plasmas. The reliability and the versatility of this technique, which is based on the comparison between results of the numerical integration of the radiative transfer equation and experimental spectra, were tested on different targets. The evolutions in time and space of the absolute population of the plasma species originating from metallic alloys (Al-Mg and Cu-Ni) and refractory materials (C/SiC) were achieved over large time scales. Owing to its accuracy, this absorption technique (that we call 'LIPAS' for Laser Induced Plasma Absorption Spectroscopy) should bring a new and enhanced support to the validation of collisional-radiative models attempting to provide reliable evolutions of laser-induced plasmas.

Superconductors

CERN Document Server

Narlikar, A V

2014-01-01

Superconductors is neither about basic aspects of superconductivity nor about its applications, but its mainstay is superconducting materials. Unusual and unconventional features of a large variety of novel superconductors are presented and their technological potential as practical superconductors assessed. The book begins with an introduction to basic aspects of superconductivity. The presentation is readily accessible to readers from a diverse range of scientific and technical disciplines, such as metallurgy, materials science, materials engineering, electronic and device engineering, and chemistry. The derivation of mathematical formulas and equations has been kept to a minimum and, wherever necessary, short appendices with essential mathematics have been added at the end of the text. The book is not meant to serve as an encyclopaedia, describing each and every superconductor that exists, but focuses on important milestones in their exciting development.

[Gas pipeline leak detection based on tunable diode laser absorption spectroscopy].

Science.gov (United States)

Zhang, Qi-Xing; Wang, Jin-Jun; Liu, Bing-Hai; Cai, Ting-Li; Qiao, Li-Feng; Zhang, Yong-Ming

2009-08-01

The principle of tunable diode laser absorption spectroscopy and harmonic detection technique was introduced. An experimental device was developed by point sampling through small multi-reflection gas cell. A specific line near 1 653. 7 nm was targeted for methane measurement using a distributed feedback diode laser as tunable light source. The linearity between the intensity of second harmonic signal and the concentration of methane was determined. The background content of methane in air was measured. The results show that gas sensors using tunable diode lasers provide a high sensitivity and high selectivity method for city gas pipeline leak detection.

Frequency stabilization of a 1083 nm fiber laser to {sup 4}He transition lines with optical heterodyne saturation spectroscopies

Energy Technology Data Exchange (ETDEWEB)

Gong, W.; Peng, X., E-mail: xiangpeng@pku.edu.cn; Li, W.; Guo, H., E-mail: hongguo@pku.edu.cn [State Key Laboratory of Advanced Optical Communication Systems and Networks, School of Electronics Engineering and Computer Science, Center for Quantum Information Technology, and Center for Computational Science and Engineering (CCSE), Peking University, Beijing 100871 (China)

2014-07-15

Two kinds of optical heterodyne saturation spectroscopies, namely, frequency modulation spectroscopy (FMS) and modulation transfer spectroscopy (MTS), are demonstrated for locking a fiber laser to the transition lines of metastable {sup 4}He atoms around 1083 nm. The servo-loop error signals of FMS and MTS for stabilizing laser frequency are optimized by studying the dependence of the peak-to-peak amplitude and slope on the optical power of pump and probe beams. A comparison of the stabilization performances of FMS/MTS and polarization spectroscopy (PS) is presented, which shows that MTS exhibits relatively superior performance with the least laser frequency fluctuation due to its flat-background dispersive signal, originated from the four-wave mixing process. The Allan deviation of the stabilized laser frequency is 5.4 × 10{sup −12}@100 s with MTS for data acquired in 1000 s, which is sufficiently applicable for fields like laser cooling, optical pumping, and optical magnetometry.

Laser-Induced Breakdown Spectroscopy (LIBS for Monitoring the Formation of Hydroxyapatite Porous Layers

Directory of Open Access Journals (Sweden)

Daniel Sola

2017-12-01

Full Text Available Laser-induced breakdown spectroscopy (LIBS is applied to characterize the formation of porous hydroxyapatite layers on the surface of 0.8CaSiO3-0.2Ca3(PO42 biocompatible eutectic glass immersed in simulated body fluid (SBF. Compositional and structural characterization analyses were also conducted by field emission scanning electron microscopy (FESEM, energy dispersive X-ray spectroscopy (EDX, and micro-Raman spectroscopy.

Laser-Induced Breakdown Spectroscopy for Qualitative Analysis of Metals in Simulated Martian Soils

Science.gov (United States)

Mowry, Curtis; Milofsky, Rob; Collins, William; Pimentel, Adam S.

2017-01-01

This laboratory introduces students to laser-induced breakdown spectroscopy (LIBS) for the analysis of metals in soil and rock samples. LIBS employs a laser-initiated spark to induce electronic excitation of metal atoms. Ensuing atomic emission allows for qualitative and semiquantitative analysis. The students use LIBS to analyze a series of…

Superconductor-ferromagnet-superconductor nanojunctions from perovskite materials

International Nuclear Information System (INIS)

Štrbík, V.; Beňačka, Š.; Gaži, Š.; Španková, M.; Šmatko, V.; Knoška, J.; Gál, N.; Chromik, Š.; Sojková, M.; Pisarčík, M.

2017-01-01

Highlights: • Superconductor-ferromagnet-superconductor nanojunction. • Nanojunctions prepared by Ga"3"+ focused ion beam patterning. • Indication of triplet Cooper pair component in junction superconducting current. • Qualitative agreement with theoretical model. - Abstract: The lateral superconductor-ferromagnet–superconductor (SFS) nanojunctions based on high critical temperature superconductor YBa_2Cu_3O_x (YBCO) and half-metallic ferromagnet La_0_._6_7Sr_0_._3_3MnO_3 (LSMO) thin films were prepared to investigate a possible presence of long range triplet component (LRTC) of Cooper pairs in the LSMO. We applied Ga"3"+ focused ion beam patterning to create YBCO/LSMO/YBCO lateral type nanojunctions with LSMO length as small as 40 nm. The resistivity vs. temperature, critical current density vs. temperature and resistance vs. magnetic field dependence were studied to recognize the LRTC of Cooper pairs in the LSMO. A non-monotonic temperature dependence of junction critical current density and a decrease of the SFS nanojunction resistance in increased magnetic field were observed. Only weak manifestations of LRTC and some qualitative agreement with theory were found out in SFS nanojunctions realized from the perovskite materials. The presence of equal-spin triplet component of Cooper pairs in half-metallic LSMO ferromagnet is not such apparent as in SFS junctions prepared from low temperature superconductors NbTiN and half-metallic ferromagnet CrO_2.

Sizes and shapes of short-lived nuclei via laser spectroscopy. Final report

International Nuclear Information System (INIS)

Lewis, D.A.

1985-10-01

This project, a collaboration involving Iowa State University, Argonne National Lab., and the University of Minnesota, was aimed at the determination of properties of short-lived nuclei through their atomic hyperfine structure and optical isotope shifts. The basic approach was to use a cryogenic He-jet system to thermalize, neutralize, and transport radioactive nuclei produced online into a region suitable for laser spectroscopy. The photon burst method was then used for high sensitivity with the resulting continuous atomic beam. The experiment was located on beamline of the ANL superconducting heavy-ion accelerator. The He-jet system developed would reliably transport approx.10 2 nuclei into phase space useful for high resolution laser spectroscopy. The laser system developed could accurately and reproducibly sweep small frequency ranges for periods greater than or equal to1 day and sensitivity limits less than or equal to1 atom/s were achieved. However the nuclei were not transported as free atoms precluding nuclear determinations. Attempts to obtain free atoms by eliminating turbulence and contamination were not successful. Some of the high sensitivity spectroscopy techniques developed in this work are now being applied in a search for nuclear relics of the Big Bang and in studies of the photon statistics of light scattered by a single atom. 3 refs., 4 figs

Modern spectroscopy

CERN Document Server

Hollas, J Michael

2013-01-01

The latest edition of this highly acclaimed title introduces the reader to a wide range of spectroscopies, and includes both the background theory and applications to structure determination and chemical analysis.  It covers rotational, vibrational, electronic, photoelectron and Auger spectroscopy, as well as EXAFs and the theory of lasers and laser spectroscopy. A  revised and updated edition of a successful, clearly written book Includes the latest developments in modern laser techniques, such as cavity ring-down spectroscopy and femtosecond lasers Provides numerous worked examples, calculations and questions at the end of chapters.

Nodal quasiparticle dynamics in the heavy fermion superconductor CeCoIn₅ revealed by precision microwave spectroscopy.

Science.gov (United States)

Truncik, C J S; Huttema, W A; Turner, P J; Ozcan, S; Murphy, N C; Carrière, P R; Thewalt, E; Morse, K J; Koenig, A J; Sarrao, J L; Broun, D M

2013-01-01

CeCoIn₅ is a heavy fermion superconductor with strong similarities to the high-Tc cuprates, including quasi-two-dimensionality, proximity to antiferromagnetism and probable d-wave pairing arising from a non-Fermi-liquid normal state. Experiments allowing detailed comparisons of their electronic properties are of particular interest, but in most cases are difficult to realize, due to their very different transition temperatures. Here we use low-temperature microwave spectroscopy to study the charge dynamics of the CeCoIn₅ superconducting state. The similarities to cuprates, in particular to ultra-clean YBa₂Cu₃O(y), are striking: the frequency and temperature dependence of the quasiparticle conductivity are instantly recognizable, a consequence of rapid suppression of quasiparticle scattering below T(c); and penetration-depth data, when properly treated, reveal a clean, linear temperature dependence of the quasiparticle contribution to superfluid density. The measurements also expose key differences, including prominent multiband effects and a temperature-dependent renormalization of the quasiparticle mass.

Polarization spectroscopy on laser-produced plasmas and Z-pinch plasmas

Energy Technology Data Exchange (ETDEWEB)

Kim, Dong E. [POSTECH, Kyungbuk (Korea); Baronova, Elena O. [RRC Kurchatov Institute, Nuclear Fusion Institute, Moscow (Russian Federation); Jakubowski, Lech [Soltan Institute for Nuclear Studies, Swierk-Otwock (Poland)

2002-08-01

PPS experiments on laser-produced plasmas are reviewed. Polarization is interpreted in terms of the anisotropic velocity distribution of electrons due to non-local transport. The polarization of an x-ray laser, and recent results regarding the recombining plasma are also presented. X-ray polarization spectroscopy experiments on heliumlike ion lines from a vacuum spark and from a plasma focus are presented: in both cases, the resonance line of the heliumlike ions shows polarization in the direction perpendicular to the discharge axis. Two possible interpretations are suggested. (author)

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

Photoacoustic-based detector for infrared laser spectroscopy

Energy Technology Data Exchange (ETDEWEB)

Scholz, L.; Palzer, S., E-mail: stefan.palzer@imtek.uni-freiburg.de [Department of Microsystems Engineering-IMTEK, Laboratory for Gas Sensors, University of Freiburg, Georges-Köhler-Allee 102, Freiburg 79110 (Germany)

2016-07-25

In this contribution, we present an alternative detector technology for use in direct absorption spectroscopy setups. Instead of a semiconductor based detector, we use the photoacoustic effect to gauge the light intensity. To this end, the target gas species is hermetically sealed under excess pressure inside a miniature cell along with a MEMS microphone. Optical access to the cell is provided by a quartz window. The approach is particularly suitable for tunable diode laser spectroscopy in the mid-infrared range, where numerous molecules exhibit large absorption cross sections. Moreover, a frequency standard is integrated into the method since the number density and pressure inside the cell are constant. We demonstrate that the information extracted by our method is at least equivalent to that achieved using a semiconductor-based photon detector. As exemplary and highly relevant target gas, we have performed direct spectroscopy of methane at the R3-line of the 2v{sub 3} band at 6046.95 cm{sup −1} using both detector technologies in parallel. The results may be transferred to other infrared-active transitions without loss of generality.

X-ray spectroscopy of laser imploded targets

International Nuclear Information System (INIS)

Yaakobi, B.; Skupsky, S.; McCrory, R.L.; Hooper, C.F.; Deckman, H.; Bourke, P.; Soures, J.M.

1981-01-01

X-ray spectroscopy provides a variety of means for studying the interaction of lasers with plasmas, in particular the interaction with imploding targets in inertial confinement fusion. A typical fusion target is composed of materials other than the thermonuclear fuel which play a variety of roles (tamping, shielding, thermal isolation, etc.). These structural elements emit characteristic X-ray lines and continua, and through their spectral and spatial distributions can yield very valuable information on the interaction and implosion dynamics. Examples are the study of heat conductivity, the mixing of different target layers, and the determination of temperature and density at the compressed target core. Results will be shown for electron densities Nsub(e) approximately equal to 10 24 cm -3 and temperatures T approximately equal to 1 keV measured during compression of argon-filled targets with a six-beam laser of peak power 2 TW. (author)

Laser spectroscopy of muonic hydrogen and the puzzling proton

International Nuclear Information System (INIS)

Pohl, Randolf

2016-01-01

Laser spectroscopy of muonic hydrogen atoms, μp, has revealed a proton root-mean-square (rms) charge radius r_E that is an order of magnitude more accurate than the CODATA world average from elastic electron–proton scattering and precision spectroscopy of regular (electronic) hydrogen. Interestingly, though, the value of r_E from μp is 4%, or 7 combined standard deviations smaller than the CODATA value of r_E. This discrepancy has been coined “proton radius puzzle”. We summarize the experiment and give a brief overview of the theory in muonic hydrogen. Finally we discuss some possible scenarios for the resolution of the “proton radius puzzle”. (author)

Optical-fiber-based laser-induced breakdown spectroscopy for detection of early caries

Science.gov (United States)

Sasazawa, Shuhei; Kakino, Satoko; Matsuura, Yuji

2015-06-01

A laser-induced breakdown spectroscopy (LIBS) system targeting for the in vivo analysis of tooth enamel is described. The system is planned to enable real-time analysis of teeth during laser dental treatment by utilizing a hollow optical fiber that transmits both Q-switched Nd:YAG laser light for LIBS and infrared Er:YAG laser light for tooth ablation. The sensitivity of caries detection was substantially improved by expanding the spectral region under analysis to ultraviolet (UV) light and by focusing on emission peaks of Zn in the UV region. Subsequently, early caries were distinguished from healthy teeth with accuracy rates above 80% in vitro.

Laser Calorimetry Spectroscopy for ppm-level Dissolved Gas Detection and Analysis.

Science.gov (United States)

K S, Nagapriya; Sinha, Shashank; R, Prashanth; Poonacha, Samhitha; Chaudhry, Gunaranjan; Bhattacharya, Anandaroop; Choudhury, Niloy; Mahalik, Saroj; Maity, Sandip

2017-02-20

In this paper we report a newly developed technique - laser calorimetry spectroscopy (LCS), which is a combination of laser absorption spectroscopy and calorimetry - for the detection of gases dissolved in liquids. The technique involves determination of concentration of a dissolved gas by irradiating the liquid with light of a wavelength where the gas absorbs, and measuring the temperature change caused by the absorbance. Conventionally, detection of dissolved gases with sufficient sensitivity and specificity was done by first extracting the gases from the liquid and then analyzing the gases using techniques such as gas chromatography. Using LCS, we have been able to detect ppm levels of dissolved gases without extracting them from the liquid. In this paper, we show the detection of dissolved acetylene in transformer oil in the mid infrared (MIR) wavelength (3021 nm) region.

Superconductor-ferromagnet-superconductor nanojunctions from perovskite materials

Energy Technology Data Exchange (ETDEWEB)

Štrbík, V., E-mail: vladimir.strbik@savba.sk [Institute of Electrical Engineering, SAS, Dúbravská Cesta 9, Bratislava (Slovakia); Beňačka, Š.; Gaži, Š.; Španková, M.; Šmatko, V. [Institute of Electrical Engineering, SAS, Dúbravská Cesta 9, Bratislava (Slovakia); Knoška, J. [Center for Free-Electron Laser Science, DESY, Notkestraße 85, 22607, Hamburg (Germany); Department of Physics, University of Hamburg, Luruper Chaussee 149, 22607, Hamburg (Germany); Gál, N.; Chromik, Š.; Sojková, M.; Pisarčík, M. [Institute of Electrical Engineering, SAS, Dúbravská Cesta 9, Bratislava (Slovakia)

2017-02-15

Highlights: • Superconductor-ferromagnet-superconductor nanojunction. • Nanojunctions prepared by Ga{sup 3+} focused ion beam patterning. • Indication of triplet Cooper pair component in junction superconducting current. • Qualitative agreement with theoretical model. - Abstract: The lateral superconductor-ferromagnet–superconductor (SFS) nanojunctions based on high critical temperature superconductor YBa{sub 2}Cu{sub 3}O{sub x} (YBCO) and half-metallic ferromagnet La{sub 0.67}Sr{sub 0.33}MnO{sub 3} (LSMO) thin films were prepared to investigate a possible presence of long range triplet component (LRTC) of Cooper pairs in the LSMO. We applied Ga{sup 3+} focused ion beam patterning to create YBCO/LSMO/YBCO lateral type nanojunctions with LSMO length as small as 40 nm. The resistivity vs. temperature, critical current density vs. temperature and resistance vs. magnetic field dependence were studied to recognize the LRTC of Cooper pairs in the LSMO. A non-monotonic temperature dependence of junction critical current density and a decrease of the SFS nanojunction resistance in increased magnetic field were observed. Only weak manifestations of LRTC and some qualitative agreement with theory were found out in SFS nanojunctions realized from the perovskite materials. The presence of equal-spin triplet component of Cooper pairs in half-metallic LSMO ferromagnet is not such apparent as in SFS junctions prepared from low temperature superconductors NbTiN and half-metallic ferromagnet CrO{sub 2}.

Picometer-resolution dual-comb spectroscopy with a free-running fibre laser

OpenAIRE

Zhao, Xin; Hu, Guoqing; Zhao, Bofeng; Li, Cui; Pan, Yingling; Liu, Ya; Yasui, Takeshi; Zheng, Zheng

2016-01-01

Dual-comb spectroscopy utilizes two sets of comb lines with slightly different comb-tooth-spacings, and optical spectral information is acquired by measuring the radio-frequency beat notes between the sets of comb lines. It holds the promise as a real-time, high-resolution analytical spectroscopy tool for a range of applications. However, the stringent requirement on the coherence between comb lines from two separate lasers and the sophisticated control system to achieve that have confined th...

Zeeman structure of red lines of lanthanum observed by laser spectroscopy methods

Science.gov (United States)

Sobolewski, Ł. M.; Windholz, L.; Kwela, J.

2017-11-01

Laser Induced Fluorescence (LIF) Spectroscopy and Optogalvanic (OG) Spectroscopy were used for the investigation of the Zeeman hyperfine (hf) structures of 27 spectral lines of La I in the wavelength range between 633.86 and 667.54 nm. As a source of free La atoms a hollow cathode discharge lamp was used. Spectra were recorded in the presence of a relatively weak magnetic field (about 800G) produced by a permanent magnet, for two linear polarization directions of the exciting laser beam. As a result of the measurements, we determined for the first time the Landé gJ- factors of 18 levels of La I. The Landé gJ- factors of 12 other levels were re-investigated and determined with higher accuracy.

Atomic site tunneling spectroscopy on high-Tc superconductors

International Nuclear Information System (INIS)

Hasegawa, T.; Nantoh, M.; Takagi, A.; Yamaguchi, W.; Ogino, M.; Kawasaki, M.

1994-01-01

Superconducting gap structures of Bi 2 Sr 2 CaCu 2 O y (BSCCO) and YBa 2 Cu 3 O y (YBCO) have been probed by scanning tunneling microscopy (STM) at cryogenic temperatures. The tunneling conductance curves observed on bulk single crystals of BSCCO and epitaxial thin films of YBCO revealed clear obershooting peaks and flat bottom regions around V=0 with quite low zero-bias conductances of ∝1%. Since the electron tunneling process in STM is essentially incoherent, the present observation is favored by the s-wave pairing mechanism. However, the conductance curves were found to be substantially smeared in comparison with the conventional spectra predicted in the BCS (isotropic s-wave) superconductors, suggesting gap anisotropy. (orig.)

The Goettingen high-Tc superconductivity research pool: the effects of structure and structural defects on the performance of high-Tc superconductors. Final reports

International Nuclear Information System (INIS)

1992-02-01

The compilation presents the final reports prepared by the various teams of the Goettingen research pool for high-Tc superconductivity. The reports are entitled: Structure and phase transition in high-Tc superconductors (Krebs/Freyhardt). Preparation and critical properties of high-Tc superconductors (Freyhardt/Heinemann/Zimmermann). EMC measurements in high-Tc superconductors (Bormann/Noelting). Phase analysis of the various phases observed in the preparation of high-Tc superconductors (Faupel/Hehenkamp). Positron annihilation in high-Tc superconductors (Hehenkamp). Preparation and characterization of thin films consisting of superconducting oxide ceramics (v. Minnigerode/Samwer). High-Tc superconductivity in monocrystals (Winzer/Beuermann). Microwave conductivity in high-Tc superconductors (Helberg). High-resolution structural analyses in high-Tc superconductors (Kupcik/Bente). Synthesis, structural analyses and spectroscopy of high-Tc superconductors (Bente). Synthesis, monocrystal growing, crystal structure of high-Tc superconductors (Schwarzmann). Ion-beam-aided studies in high-Tc superconductors (Uhrmacher). (orig./MM) [de

A review of the development of portable laser induced breakdown spectroscopy and its applications

Czech Academy of Sciences Publication Activity Database

Rakovský, Jozef; Čermák, P.; Musset, O.; Veis, P.

2014-01-01

Roč. 101, NOV 2014 (2014), s. 269-287 ISSN 0584-8547 R&D Projects: GA ČR GA13-11635S Institutional support: RVO:61388955 Keywords : Fiber laser * Fieldable LIBS * Laser-induced breakdown spectroscopy Subject RIV: CF - Physical ; Theoretical Chemistry Impact factor: 3.176, year: 2014

Application of a compact diode pumped solid-state laser source for quantitative laser-induced breakdown spectroscopy analysis of steel

Science.gov (United States)

Tortschanoff, Andreas; Baumgart, Marcus; Kroupa, Gerhard

2017-12-01

Laser-induced breakdown spectroscopy (LIBS) technology holds the potential for onsite real-time measurements of steel products. However, for a mobile and robust LIBS measurement system, an adequate small and ruggedized laser source is a key requirement. In this contribution, we present tests with our compact high-power laser source, which, initially, was developed for ignition applications. The CTR HiPoLas® laser is a robust diode pumped solid-state laser with a passive Q-switch with dimensions of less than 10 cm3. The laser generates 2.5-ns pulses with 30 mJ at a maximum continuous repetition rate of about 30 Hz. Feasibility of LIBS experiments with the laser source was experimentally verified with steel samples. The results show that the laser with its current optical output parameters is very well-suited for LIBS measurements. We believe that the miniaturized laser presented here will enable very compact and robust portable high-performance LIBS systems.

Gas spectroscopy with integrated frequency monitoring through self-mixing in a terahertz quantum-cascade laser.

Science.gov (United States)

Chhantyal-Pun, Rabi; Valavanis, Alexander; Keeley, James T; Rubino, Pierluigi; Kundu, Iman; Han, Yingjun; Dean, Paul; Li, Lianhe; Davies, A Giles; Linfield, Edmund H

2018-05-15

We demonstrate a gas spectroscopy technique, using self-mixing in a 3.4 terahertz quantum-cascade laser (QCL). All previous QCL spectroscopy techniques have required additional terahertz instrumentation (detectors, mixers, or spectrometers) for system pre-calibration or spectral analysis. By contrast, our system self-calibrates the laser frequency (i.e., with no external instrumentation) to a precision of 630 MHz (0.02%) by analyzing QCL voltage perturbations in response to optical feedback within a 0-800 mm round-trip delay line. We demonstrate methanol spectroscopy by introducing a gas cell into the feedback path and show that a limiting absorption coefficient of ∼1×10 -4   cm -1 is resolvable.

Laser Raman spectroscopy in heat and flow technology

International Nuclear Information System (INIS)

Leipertz, A.

1981-01-01

The laser Raman spectroscopy based on the inelastic scattering of incident laser photons on the molecules of the fluid to be investigated, has advantages which partly reach beyond the usual scattered light methods: The signales are molecule-specific, the vibration line of various gases can be spectrally well recognized, the field of application is wide, the energy state of the molecules is hardly influenced. By measuring the line intensity, one obtains the concentration of the observed gas components via the molecule number, the temperature and total pressure; from the uptake of the partial density of the single components one can obtain the density of the gas mixture; vibration temperature and rotation temperature can be measured independently. Measuring methods and construction of a Raman probe are given. (WB) [de

Gel stabilization in chelate sol-gel preparation of Bi-2223 superconductors

Czech Academy of Sciences Publication Activity Database

Rubešová, K.; Jakeš, V.; Hlásek, T.; Vašek, Petr; Matějka, P.

2012-01-01

Roč. 73, č. 3 (2012), s. 448-453 ISSN 0022-3697 Institutional research plan: CEZ:AV0Z10100521 Keywords : superconductors * sol-gel growth * infrared spectroscopy * thermogravimetric analysis (TGA) * X-ray diffraction Subject RIV: BM - Solid Matter Physics ; Magnetism Impact factor: 1.527, year: 2012

Quantitative analysis of essential oils of Thymus daenensis using laser-induced fluorescence and Raman spectroscopy.

Science.gov (United States)

Khoshroo, H; Khadem, H; Bahreini, M; Tavassoli, S H; Hadian, J

2015-11-10

Laser-induced fluorescence and Raman spectroscopy are used for the investigation of different genotypes of Thymus daenensis native to the Ilam province of Iran. Different genotypes of T. daenensis essential oils, labeled T1 through T7, possess slight differences with regard to the composition of the thymol. The gas chromatography-mass spectrometry (GC-MS) method is performed to determine the concentration of each constituent as a reference method. The Raman spectra of different concentrations of pure thymol dissolved in hexane as standard samples are obtained via a laboratory prototype Raman spectroscopy setup for the calculation of the calibration curve. The regression coefficient and limit of detection are calculated. The possibility of the differentiation of different genotypes of T. daenensis is also examined by laser-induced fluorescence spectroscopy, although we do not know the exact amounts of their components. All the fluorescence spectral information is used jointly by cluster analysis to differentiate between 7 genotypes. Our results demonstrate the acceptable precision of Raman spectroscopy with GC-MS and corroborate the capacity of Raman spectroscopy in applications in the quantitative analysis field. Furthermore, the cluster analysis results show that laser-induced fluorescence spectroscopy is an acceptable technique for the rapid classification of different genotypes of T. daenensis without having any previous information of their exact amount of constituents. So, the ability to rapidly and nondestructively differentiate between genotypes makes it possible to efficiently select high-quality herbs from many samples.

Laser plasma x-ray source for ultrafast time-resolved x-ray absorption spectroscopy

Directory of Open Access Journals (Sweden)

L. Miaja-Avila

2015-03-01

Full Text Available We describe a laser-driven x-ray plasma source designed for ultrafast x-ray absorption spectroscopy. The source is comprised of a 1 kHz, 20 W, femtosecond pulsed infrared laser and a water target. We present the x-ray spectra as a function of laser energy and pulse duration. Additionally, we investigate the plasma temperature and photon flux as we vary the laser energy. We obtain a 75 μm FWHM x-ray spot size, containing ∼106 photons/s, by focusing the produced x-rays with a polycapillary optic. Since the acquisition of x-ray absorption spectra requires the averaging of measurements from >107 laser pulses, we also present data on the source stability, including single pulse measurements of the x-ray yield and the x-ray spectral shape. In single pulse measurements, the x-ray flux has a measured standard deviation of 8%, where the laser pointing is the main cause of variability. Further, we show that the variability in x-ray spectral shape from single pulses is low, thus justifying the combining of x-rays obtained from different laser pulses into a single spectrum. Finally, we show a static x-ray absorption spectrum of a ferrioxalate solution as detected by a microcalorimeter array. Altogether, our results demonstrate that this water-jet based plasma source is a suitable candidate for laboratory-based time-resolved x-ray absorption spectroscopy experiments.

Theory of tunneling and photoemission spectroscopy for high-temperature superconductors

International Nuclear Information System (INIS)

Kouznetsov, K.; Coffey, L.

1996-01-01

A comprehensive analysis is presented of the tunneling conductance and angle-resolved photoemission spectra in high-temperature superconductors. It is shown that unexplained features of the tunneling and photoemission spectra such as broad backgrounds, dips, and asymmetry of the tunneling conductance can arise in a model of spin-fluctuation mediated inelastic tunneling. Effects of directionality in tunneling play an important role in determining the behavior of the tunneling conductance. copyright 1996 The American Physical Society

Superconductors

International Nuclear Information System (INIS)

1988-01-01

The chapter 6.3 p. 143 to 153 of this book deals with superconductors 19 items are briefly presented with address of manufacturer or laboratory to contact, mainly in the USA or Japan. In particular magnets, films, high temperature superconductors and various applications are presented [fr

Quantitative measurement of carbon isotopic composition in CO2 gas reservoir by Micro-Laser Raman spectroscopy

Science.gov (United States)

Li, Jiajia; Li, Rongxi; Zhao, Bangsheng; Guo, Hui; Zhang, Shuan; Cheng, Jinghua; Wu, Xiaoli

2018-04-01

The use of Micro-Laser Raman spectroscopy technology for quantitatively determining gas carbon isotope composition is presented. In this study, 12CO2 and 13CO2 were mixed with N2 at various molar fraction ratios to obtain Raman quantification factors (F12CO2 and F13CO2), which provide a theoretical basis for calculating the δ13C value. And the corresponding values were 0.523 (0 Laser Raman analysis were carried out on natural CO2 gas from Shengli Oil-field at room temperature under different pressures. The δ13C values obtained by Micro-Laser Raman spectroscopy technology and Isotope Ratio Mass Spectrometry (IRMS) technology are in good agreement with each other, and the relative errors range of δ13C values is 1.232%-6.964%. This research provides a fundamental analysis tool for determining gas carbon isotope composition (δ13C values) quantitatively by using Micro-Laser Raman spectroscopy. Experiment of results demonstrates that this method has the potential for obtaining δ13C values in natural CO2 gas reservoirs.

Electronic Structure, Irreversibility Line and Magnetoresistance of Cu_0_._3Bi_2Se_3 Superconductor

International Nuclear Information System (INIS)

Yi He-Mian; Chen Chao-Yu; Sun Xuan; Xie Zhuo-Jin; Feng Ya; Liang Ai-Ji; Peng Ying-Ying; He Shao-Long; Zhao Lin; Liu Guo-Dong; Dong Xiao-Li; Zhang Jun; Zhou Xing-Jiang; Chen Chuang-Tian; Xu Zu-Yan; Gu Gen-Da

2015-01-01

Cu_xBi_2Se_3 is a superconductor that is a potential candidate for topological superconductors. We report our laser-based angle-resolved photoemission measurement on the electronic structure of the Cu_xBi_2Se_3 superconductor, and a detailed magneto-resistance measurement in both normal and superconducting states. We find that the topological surface state of the pristine Bi_2Se_3 topological insulator remains robust after the Cu-intercalation, while the Dirac cone location moves downward due to electron doping. Detailed measurements on the magnetic field-dependence of the resistance in the superconducting state establishes an irreversibility line and gives a value of the upper critical field at zero temperature of ∼4000 Oe for the Cu_0_._3Bi_2Se_3 superconductor with a middle point T_c of 1.9K. The relation between the upper critical field H_c_2 and temperature T is different from the usual scaling relation found in cuprates and in other kinds of superconductors. Small positive magneto-resistance is observed in Cu_0_._3Bi_2Se_3 superconductors up to room temperature. These observations provide useful information for further study of this possible candidate for topological superconductors. (paper)

Advanced magneto-optical Kerr effect measurements of superconductors at low temperatures

Directory of Open Access Journals (Sweden)

Claudia Stahl

2017-10-01

Full Text Available Magneto-optical Kerr-effect (MOKE measurements of superconducting films with soft-magnetic coatings are performed at low temperatures using a laser-based MOKE set-up. An elaborate measurement scheme with internal reference allows the quantitative comparison of the temperature dependent Kerr-amplitude with the magnetic field generated by supercurrents. For this purpose, an amorphous CoFeB thin film exhibiting a large Kerr-signal is deposited directly on top of the YBCO superconductor acting as field sensing layer. It is shown that the resulting magnetic hysteresis loops of the soft-magnetic film can be used to reconstruct the electric properties of the superconductor.

Optical Emission Spectroscopy of Plasma in Hybrid Pulsed Laser Deposition System

Czech Academy of Sciences Publication Activity Database

Novotný, Michal; Jelínek, Miroslav; Bulíř, Jiří; Lančok, Ján; Jastrabík, Lubomír; Zelinger, Zdeněk

2002-01-01

Roč. 52, Suppl. D (2002), s. 292-298 ISSN 0011-4626 R&D Projects: GA AV ČR IAA1010110 Keywords : optical emission spectroscopy * pulsed laser deposition * RF discharge Subject RIV: CF - Physical ; Theoretical Chemistry Impact factor: 0.311, year: 2002

Recent progress of laser spectroscopy experiments on antiprotonic helium

Science.gov (United States)

Hori, Masaki

2018-03-01

The Atomic Spectroscopy and Collisions Using Slow Antiprotons (ASACUSA) collaboration is currently carrying out laser spectroscopy experiments on antiprotonic helium ? atoms at CERN's Antiproton Decelerator facility. Two-photon spectroscopic techniques have been employed to reduce the Doppler width of the measured ? resonance lines, and determine the atomic transition frequencies to a fractional precision of 2.3-5 parts in 109. More recently, single-photon spectroscopy of buffer-gas cooled ? has reached a similar precision. By comparing the results with three-body quantum electrodynamics calculations, the antiproton-to-electron mass ratio was determined as ?, which agrees with the known proton-to-electron mass ratio with a precision of 8×10-10. The high-quality antiproton beam provided by the future Extra Low Energy Antiproton Ring (ELENA) facility should enable further improvements in the experimental precision. This article is part of the Theo Murphy meeting issue `Antiproton physics in the ELENA era'.

Diode laser excited optogalvanic spectroscopy of glow discharges

International Nuclear Information System (INIS)

Barshick, C. M.; Shaw, R. W.; Jennings, L. W.; Post-Zwicker, A.; Young, J. P.; Ramsey, J. M.

1997-01-01

The development of diode-laser-excited isotopically-selective optogalvanic spectroscopy (OGS) of uranium metal, oxide and fluoride in a glow discharge (GD) is presented. The technique is useful for determining 235 U/( 235 U+ 238 U) isotope ratios in these samples. The precision and accuracy of this determination is evaluated, and a study of experimental parameters pertaining to optimization of the measurement is discussed. Application of GD-OGS to other f-transition elements is also described

Diode laser excited optogalvanic spectroscopy of glow discharges

International Nuclear Information System (INIS)

Barshick, C.M.; Shaw, R.W.; Post-Zwicker, A., Young, J.P.; Ramsey, J.M.

1996-01-01

The development of diode-laser-excited isotopically-selective optogalvanic spectroscopy (OGS) of uranium metal, oxide and fluoride in a glow discharge (GD) is presented. The technique is useful for determining isotopic ratios of 235 U/( 235 U + 238 U) in the above samples. The precision and accuracy of this determination is evaluated, and a study of experimental parameters pertaining to optimization of he measurement is discussed. Application of the GD-OGS to other f-transition elements is also described

[Signal analysis and spectrum distortion correction for tunable diode laser absorption spectroscopy system].

Science.gov (United States)

Bao, Wei-Yi; Zhu, Yong; Chen, Jun; Chen, Jun-Qing; Liang, Bo

2011-04-01

In the present paper, the signal of a tunable diode laser absorption spectroscopy (TDLAS) trace gas sensing system, which has a wavelength modulation with a wide range of modulation amplitudes, is studied based on Fourier analysis method. Theory explanation of spectrum distortion induced by laser intensity amplitude modulation is given. In order to rectify the spectrum distortion, a method of synchronous amplitude modulation suppression by a variable optical attenuator is proposed. To validate the method, an experimental setup is designed. Absorption spectrum measurement experiments on CO2 gas were carried out. The results show that the residual laser intensity modulation amplitude of the experimental system is reduced to -0.1% of its original value and the spectrum distortion improvement is 92% with the synchronous amplitude modulation suppression. The modulation amplitude of laser intensity can be effectively reduced and the spectrum distortion can be well corrected by using the given correction method and system. By using a variable optical attenuator in the TDLAS (tunable diode laser absorption spectroscopy) system, the dynamic range requirements of photoelectric detector, digital to analog converter, filters and other aspects of the TDLAS system are reduced. This spectrum distortion correction method can be used for online trace gas analyzing in process industry.

Surface-enhanced Raman spectroscopy on laser-engineered ruthenium dye-functionalized nanoporous gold

Science.gov (United States)

Schade, Lina; Franzka, Steffen; Biener, Monika; Biener, Jürgen; Hartmann, Nils

2016-06-01

Photothermal processing of nanoporous gold with a microfocused continuous-wave laser at λ = 532 nm provides a facile means in order engineer the pore and ligament size of nanoporous gold. In this report we take advantage of this approach in order to investigate the size-dependence of enhancement effects in surface-enhanced Raman spectroscopy (SERS). Surface structures with laterally varying pore sizes from 25 nm to ≥200 nm are characterized using scanning electron microscopy and then functionalized with N719, a commercial ruthenium complex, which is widely used in dye-sensitized solar cells. Raman spectroscopy reveals the characteristic spectral features of N719. Peak intensities strongly depend on the pore size. Highest intensities are observed on the native support, i.e. on nanoporous gold with pore sizes around 25 nm. These results demonstrate the particular perspectives of laser-fabricated nanoporous gold structures in fundamental SERS studies. In particular, it is emphasized that laser-engineered porous gold substrates represent a very well defined platform in order to study size-dependent effects with high reproducibility and precision and resolve conflicting results in previous studies.

Collinear laser spectroscopy on radioactive praseodymium ions and cadmium ions

International Nuclear Information System (INIS)

Froemmgen, Nadja

2013-01-01

Collinear laser spectroscopy is a tool for the model independent determination of spins, charge radii and electromagnetic moments of nuclei in ground and long-lived isomeric states. In the context of this thesis a new offline ion source for high evaporating temperatures and an ion beam analysis system were implemented at the TRIGA-LASER Experiment at the Institute for Nuclear Chemistry at the University of Mainz. The main part of the thesis deals with the determination of the properties of radioactive praseodymium and cadmium isotopes by collinear laser spectroscopy at ISOLDE/CERN. The necessary test measurements for the spectroscopy of praseodymium ions have been conducted with the aforementioned offline ion source at the TRIGA-LASER experiment. The spectroscopy of the praseodymium ions was motivated by the observation of a modulation of the electron capture decay rates of hydrogen-like 140 Pr 58+ . The nuclear magnetic moment of the nucleus is, among others, required for the explanation of the so-called GSI Oscillations and has not been studied experimentally before. Additionally, the determined electron capture decay constant of hydrogen-like 140 Pr 58+ is lower than the one of helium-like 140 Pr 57+ . The explanation of this phenomenon requires a positive magnetic moment. During the experiment at the COLLAPS apparatus the magnetic moments of the neutron-deficient isotopes 135 Pr, 136 Pr and 137 Pr could be determined for the first time. Unfortunately, due to a too low production yield the desired isotope 140 Pr could not be studied.The systematic study of cadmium isotopes was motivated by nuclear physics in the tin region. With Z=48 two protons are missing for the shell closure and the isotopes extend from the magic neutron number N=50 to the magic neutron number N=82. The extracted nuclear properties allow tests of different nuclear models in this region. In this thesis the obtained results of the spectroscopy of the cadmium isotopes 106-124,126 Cd and their

Laser Spark Formamide Decomposition Studied by FT-IR Spectroscopy

Czech Academy of Sciences Publication Activity Database

Ferus, Martin; Kubelík, Petr; Civiš, Svatopluk

2011-01-01

Roč. 115, č. 44 (2011), s. 12132-12141 ISSN 1089-5639 R&D Projects: GA AV ČR IAA400400705; GA AV ČR IAAX00100903; GA ČR GAP208/10/2302 Institutional research plan: CEZ:AV0Z40400503 Keywords : FT-IR spectroscopy * high-power laser * induced dielectric-breakdown Subject RIV: CF - Physical ; Theoretical Chemistry Impact factor: 2.946, year: 2011

New enhanced sensitivity infrared laser spectroscopy techniques applied to reactive plasmas and trace gas detection

NARCIS (Netherlands)

Welzel, S.

2009-01-01

Infrared laser absorption spectroscopy (IRLAS) employing both tuneable diode and quantum cascade lasers (TDLs, QCLs) has been applied with both high sensitivity and high time resolution to plasma diagnostics and trace gas measurements. TDLAS combined with a conventional White type multiple pass cell

Liquid steel analysis by laser-induced plasma spectroscopy

International Nuclear Information System (INIS)

Gruber, J.

2002-11-01

When a nanosecond pulsed laser is focused onto a sample and the intensity exceeds a certain threshold, material is vaporized and a plasma is formed above the sample surface. The laser-light becomes increasingly absorbed by inverse bremsstrahlung and by photo-excitation and photo-ionization of atoms and molecules. The positive feedback, by which the number of energetic electrons for ionization is increased in an avalanche-like manner under the influence of laser-light, is the so-called optical breakdown. Radiating excited atoms and ions within the expanding plasma plume produce a characteristic optical emission spectrum. A spectroscopic analysis of this optical emission of the laser-induced plasma permits a qualitative and quantitative chemical analysis of the investigated sample. This technique is therefore often called laser-induced plasma spectroscopy (LIPS) or laser-induced breakdown spectroscopy (LIBS). LIPS is a fast non-contact technique, by which solid, liquid or gaseous samples can be analyzed with respect to their chemical composition. Hence, it is an appropriate tool for the rapid in-situ analysis of not easily accessible surfaces for process control in industrial environments. In this work, LIPS was studied as a technique to determine the chemical composition of solid and liquid steel. A LIPS set-up was designed and built for the remote and continuous in-situ analysis of the steel melt. Calibration curves were prepared for the LIPS analysis of Cr, Mn, Ni and Cu in solid steel using reference samples with known composition. In laboratory experiments an induction furnace was used to melt steel samples in crucibles, which were placed at a working distance of 1.5 m away from the LIPS apparatus. The response of the LIPS system was monitored on-line during the addition of pure elements to the liquid steel bath within certain concentration ranges (Cr: 0.11 - 13.8 wt%, Cu: 0.044 - 0.54 wt%, Mn: 1.38 - 2.5 wt%, Ni: 0.049 - 5.92 wt%). The analysis of an element

Chirped laser dispersion spectroscopy for remote open-path trace-gas sensing.

Science.gov (United States)

Nikodem, Michal; Wysocki, Gerard

2012-11-28

In this paper we present a prototype instrument for remote open-path detection of nitrous oxide. The sensor is based on a 4.53 μm quantum cascade laser and uses the chirped laser dispersion spectroscopy (CLaDS) technique for molecular concentration measurements. To the best of our knowledge this is the first demonstration of open-path laser-based trace-gas detection using a molecular dispersion measurement. The prototype sensor achieves a detection limit down to the single-ppbv level and exhibits excellent stability and robustness. The instrument characterization, field deployment performance, and the advantages of applying dispersion sensing to sensitive trace-gas detection in a remote open-path configuration are presented.

Characterization of organic photovoltaic devices using femtosecond laser induced breakdown spectroscopy

Science.gov (United States)

Banerjee, S. P.; Sarnet, Thierry; Siozos, Panayiotis; Loulakis, Michalis; Anglos, Demetrios; Sentis, Marc

2017-10-01

The potential of laser induced breakdown spectroscopy (LIBS) as a non-contact probe, for characterizing organic photovoltaic devices during selective laser scribing, was investigated. Samples from organic solar cells were studied, which consisted of several layers of materials including a top electrode (Al, Mg or Mo), organic layer, bottom electrode (indium tin oxide), silicon nitride barrier layer and substrate layer situated from the top consecutively. The thickness of individual layers varies from 115 to 250 nm. LIBS measurements were performed by use of a 40 femtosecond Ti:Sapphire laser operated at very low pulse energy (solar cell structure, demonstrating the potential of LIBS for fast, non-contact characterization of organic photovoltaic coatings.

Organic superconductors

International Nuclear Information System (INIS)

Bulaevskij, L.N.; Shchegolev, I.F.

1986-01-01

Main achievements in creating new organic conducting materials - synthetic metals and superconductors, are considered. The processes of superconductivity occurrence in organic materials are discussed. It is shown that conjugated bonds between C and H atoms in organic molecules play an important role in this case. At present ''crystal direction'' in organic superconductor synthesis is mainly developed. Later on, organic superconductor crystals are supposed to be introduced into usual polymers, e.g. polyethylene

Magnetoanisotropic spin-triplet Andreev reflection in ferromagnet-Ising superconductor junctions

Science.gov (United States)

Lv, Peng; Zhou, Yan-Feng; Yang, Ning-Xuan; Sun, Qing-Feng

2018-04-01

We theoretically study the electronic transport through a ferromagnet-Ising superconductor junction. A tight-binding Hamiltonian describing the Ising superconductor is presented. Then by combining the nonequilibrium Green's function method, the expressions of Andreev reflection coefficient and conductance are obtained. A strong magnetoanisotropic spin-triplet Andreev reflection is shown, and the magnetoanisotropic period is π instead of 2 π as in the conventional magnetoanisotropic system. We demonstrate a significant increase of the spin-triplet Andreev reflection for the single-band Ising superconductor. Furthermore, the dependence of the Andreev reflection on the incident energy and incident angle are also investigated. A complete Andreev reflection can occur when the incident energy is equal to the superconducting gap, regardless of the Fermi energy (spin polarization) of the ferromagnet. For the suitable oblique incidence, the spin-triplet Andreev reflection can be strongly enhanced. In addition, the conductance spectroscopies of both zero bias and finite bias are studied, and the influence of gate voltage, exchange energy, and spin-orbit coupling on the conductance spectroscopy are discussed in detail. The conductance exhibits a strong magnetoanisotropy with period π as the Andreev reflection coefficient. When the magnetization direction is parallel to the junction plane, a large conductance peak always emerges at the superconducting gap. This work offers a comprehensive and systematic study of the spin-triplet Andreev reflection and has an underlying application of π -periodic spin valve in spintronics.

An overview of the Fe-chalcogenide superconductors

International Nuclear Information System (INIS)

Wu, M K; Wen, Y C; Chen, T K; Chang, C C; Wu, P M; Wang, M J; Lin, P H; Lee, W C

2015-01-01

This review intends to summarize recent advancements in FeSe and related systems. The FeSe and related superconductors are currently receiving considerable attention for the high critical temperature (T C ) observed and for many similar features to the high T C cuprate superconductors. These similarities suggest that understanding the FeSe-based compounds could potentially help our understanding of the cuprates. We begin the review by presenting common features observed in the FeSe- and FeAs-based systems. Then we discuss the importance of careful control of the material preparation allowing for a systematic structure characterization. With this control, numerous rich phases have been observed. Importantly, we suggest that the Fe-vacancy ordered phases found in the FeSe-based compounds, which are non-superconducting magnetic Mott insulators, are the parent compounds of the superconductors. Superconductivity can emerge from the parent phases by disordering the Fe vacancy order, often by a simple annealing treatment. Then we review physical properties of the Fe chalcogenides, specifically the optical properties and angle-resolved photoemission spectroscopy (ARPES) results. From the literature, strong evidence points to the existence of orbital modification accompanied by a gap-opening, prior to the structural phase transition, which is closely related to the occurrence of superconductivity. Furthermore, strong lattice to spin coupling are important for the occurrence of superconductivity in FeSe. Therefore, it is believed that the iron selenides and related compounds will provide essential information to understand the origin of superconductivity in the iron-based superconductors, and possibly the superconducting cuprates. (topical review)

Temperature dependence of the phonon structure in the high-temperature superconductor Bi2Sr2CaCu2O8 studied by infrared reflectance spectroscopy

International Nuclear Information System (INIS)

Kamaras, K.; Herr, S.L.; Porter, C.D.; Tanner, D.B.; Etemad, S.; Tarascon, J.

1991-01-01

We have investigated a ceramic sample of the high-temperature superconductor Bi 2 Sr 2 CaCu 2 O 8 (T c =85 K) by infrared and visible reflectance spectroscopy at several temperatures both below and above the superconducting transition. We find that the temperature variation in the vibrational region is associated with minima or antiresonance features of the optical conductivity, instead of maxima, indicating strong Fano-type electron-phonon interaction and implying that the phonon structure in the infrared is strongly affected by the ab-plane response

Quantitative mixture fraction measurements in combustion system via laser induced breakdown spectroscopy

KAUST Repository

Mansour, Mohy S.; Imam, Hisham; Elsayed, Khaled A.; Elbaz, Ayman M.; Abbass, Wafaa

2015-01-01

Laser induced breakdown spectroscopy (LIBS) technique has been applied to quantitative mixture fraction measurements in flames. The measured spectra of different mixtures of natural gas and air are used to obtain the calibration parameters for local

Laser-induced breakdown spectroscopy (LIBS): a new spectrochemical technique

International Nuclear Information System (INIS)

Radziemski, L.J.; Loree, T.R.; Cremers, D.A.

1982-01-01

We have used the breakdown spark from a focused laser beam to generate analytically useful emission spectra of minor constituents in air and other carrier gases. The medium was sampled directly. It was not necessary to reduce the sample to solution nor to introduce electrodes. The apparatus is particularly simple; a pulsed laser, spectrometer, and some method for time resolution. The latter is essential in laser-induced-breakdown spectroscopy (LIBS) because of the strong early continuum. High temperatures in the spark result in vaporization of small particles, dissociation of molecules, and excitation of atomic and ionic spectra, including species which are normally difficult to detect. In one application, we have monitored beryllium in air at conventrations below 1 μg/m 3 , which is below 1 ppB (w/w). In another we have monitored chlorine and fluorine atoms in real time. LIBS has the potential for real-time direct sampling of contaminants in situ

Surface-enhanced Raman spectroscopy (SERS) using Ag nanoparticle films produced by pulsed laser deposition

Energy Technology Data Exchange (ETDEWEB)

Smyth, C.A., E-mail: smythc2@tcd.ie [School of Physics, Trinity College Dublin, Dublin 2 (Ireland); Mirza, I.; Lunney, J.G.; McCabe, E.M. [School of Physics, Trinity College Dublin, Dublin 2 (Ireland)

2013-01-01

Highlights: Black-Right-Pointing-Pointer Pulsed laser deposition (PLD) produces silver nanoparticle films. Black-Right-Pointing-Pointer These films can be used for surface-enhanced Raman spectroscopy (SERS). Black-Right-Pointing-Pointer Commercial film shows good SERS reproducibility but poor signal intensity. Black-Right-Pointing-Pointer PLD shows a good SERS response coupled with good reproducibility. - Abstract: Thin silver nanoparticle films, of thickness 7 nm, were deposited onto glass microslides using pulsed laser deposition (PLD). The films were then characterised using UV-vis spectroscopy and scanning transmission electron microscopy before Rhodamine 6G was deposited onto them for investigation using surface-enhanced Raman spectroscopy (SERS). The sensitivity obtained using SERS was compared to that obtained using a colloidal silver suspension and also to a commercial SERS substrate. The reproducibility of the films is also examined using statistical analysis.

Diode laser excited optogalvanic spectroscopy of glow discharges

International Nuclear Information System (INIS)

Barshick, C.M.; Shaw, R.W.; Jennings, L.W.; Post-Zwicker, A.; Young, J.P.; Ramsey, J.M.

1997-01-01

The development of diode-laser-excited isotopically-selective optogalvanic spectroscopy (OGS) of uranium metal, oxide and fluoride in a glow discharge (GD) is presented. The technique is useful for determining 235 U/( 235 U+ 238 U) isotope ratios in these samples. The precision and accuracy of this determination is evaluated, and a study of experimental parameters pertaining to optimization of the measurement is discussed. Application of GD-OGS to other f-transition elements is also described. copyright 1997 American Institute of Physics

Changes in nail keratin observed by Raman spectroscopy after Nd:YAG laser treatment.

Science.gov (United States)

Shin, Min Kyung; Kim, Tae In; Kim, Wan Sun; Park, Hun-Kuk; Kim, Kyung Sook

2017-04-01

Lasers and photodynamic therapy have been considered a convergence treatment for onychomycosis, which is a fungal infection on the nail bed and nail plate. Laser therapies have shown satisfactory results without significant complications for onychomycosis; however, the mechanism of clearing remains unknown. In this work, we investigated changes in the chemical structure of nail keratin induced by Nd:YAG laser using Raman spectroscopy. Toe nails with onychomycosis were treated with 1064 nm Nd:YAG laser. After laser treatment, the disulfide band (490-590 cm -1 ) of nail keratin was rarely observed or was reduced in intensity. The amide I band (1500-1700 cm -1 ) also showed changes induced by the laser. The α-helical (1652 cm -1 ) structures dominated the β-sheet (1673 cm -1 ) in nontreated nail, but the opposite phenomenon was observed after laser treatment. © 2016 Wiley Periodicals, Inc.

Widely tunable Sampled Grating Distributed Bragg Reflector Quantum Cascade laser for gas spectroscopy applications

Science.gov (United States)

Diba, Abdou Salam

Since the advent of semiconductor lasers, the development of tunable laser sources has been subject of many efforts in industry and academia arenas. This interest towards broadly tunable lasers is mainly due to the great promise they have in many applications ranging from telecommunication, to environmental science and homeland security, just to name a few. After the first demonstration of quantum cascade laser (QCL) in the early nineties, QCL has experienced a rapid development, so much so that QCLs are now the most reliable and efficient laser source in the Mid-IR range covering between 3 microm to 30 microm region of the electromagnetic spectrum. QCLs have almost all the desirable characteristics of a laser for spectroscopy applications such as narrow spectral linewidth ideal for high selectivity measurement, high power enabling high sensitivity sensing and more importantly they emit in the finger-print region of most of the trace gases and large molecules. The need for widely tunable QCLs is now more pressing than ever before. A single mode quantum cascade laser (QCL) such as a distributed feedback (DFB) QCL, is an ideal light source for gas sensing in the MIR wavelength range. Despite their performance and reliability, DFB QCLs are limited by their relatively narrow wavelength tuning range determined by the thermal rollover of the laser. An external cavity (EC) QCL, on the other hand, is a widely tunable laser source, and so far is the choice mid-infrared single frequency light sources for detecting multiple species/large molecules. However, EC QCLs can be complex, bulky and expensive. In the quest for finding alternative broadly wavelength tunable sources in the mid-infrared, many monolithic tunable QCLs are recently proposed and fabricated, including SG-DBR, DFB-Arrays, Slot-hole etc. and they are all of potentially of interest as a candidate for multi-gas sensing and monitoring applications, due to their large tuning range (>50 cm-1), and potentially low

Plans for laser spectroscopy of trapped cold hydrogen-like HCI

International Nuclear Information System (INIS)

Winters, D.F.A.; Abdulla, A.M.; Castrejon Pita, J.R.; Lange, A. de; Segal, D.M.; Thompson, R.C.

2005-01-01

Laser spectroscopy studies are being prepared to measure the 1s ground state hyperfine splitting in trapped cold highly charged ions. The purpose of such experiments is to test quantum electrodynamics in the strong electric field regime. These experiments form part of the HITRAP project at GSI. A brief review of the planned experiments is presented

Recent results on neutron rich tin isotopes by laser spectroscopy

CERN Document Server

Roussière, B; Crawford, J E; Essabaa, S; Fedosseev, V; Geithner, W; Genevey, J; Girod, M; Huber, G; Horn, R; Kappertz, S; Lassen, J; Le Blanc, F; Lee, J K P; Le Scornet, G; Lettry, Jacques; Mishin, V I; Neugart, R; Obert, J; Oms, J; Ouchrif, A; Peru, S; Pinard, J; Ravn, H L; Sauvage, J; Verney, D

2001-01-01

Laser spectroscopy measurements have been performed on neutron rich tin isotopes using the COMPLIS experimental setup. The nuclear charge radii of the even-even isotopes from A=108 to 132 are compared to the results of macroscopic and microscopic calculations. The improvements and optimizations needed to perform the isotope shift measurement on $^{134}$Sn are presented.

Laser induced breakdown spectroscopy of the uranium including calcium. Time resolved measurement spectroscopic analysis (Contract research)

International Nuclear Information System (INIS)

Akaoka, Katsuaki; Maruyama, Youichiro; Oba, Masaki; Miyabe, Masabumi; Otobe, Haruyoshi; Wakaida, Ikuo

2010-05-01

For the remote analysis of low DF TRU (Decontamination Factor Transuranic) fuel, Laser Breakdown Spectroscopy (LIBS) was applied to uranium oxide including a small amount of calcium oxide. The characteristics, such as spectrum intensity and plasma excitation temperature, were measured using time-resolved spectroscopy. As a result, in order to obtain the stable intensity of calcium spectrum for the uranium spectrum, it was found out that the optimum observation delay time of spectrum is 4 microseconds or more after laser irradiation. (author)

Collinear Laser Spectroscopy of Potassium Nuclear Charge Radii beyond N = 28

CERN Document Server

AUTHOR|(CDS)2078903; Jochim, Selim

Nuclear ground-state properties, such as spin, charge radius, and magnetic dipole and electric quadrupole moments are important quantities to describe the nucleus. The comparison of experimental data to shell-model calculations gives insight in the underlying nuclear structure and composition of ground-state wave functions. Spins and charge radii can also be used to test the predictions of state-of-the-art microscopic models. This work contributes to these studies providing new measurements in the region of the nuclear chart around the magic proton number Z = 20. The data have been obtained at the collinear laser spectroscopy setup COLLAPS located at the radioactive-ion-beam facility ISOLDE at CERN. Using bunched-beam laser spectroscopy hyperne structure spectra of the potassium isotopes with mass number A = 48 51 could be recorded for the first time. Ground-state spins and isotope shifts could be deduced for 4851K contributing to the evolution of the d3=2 orbital beyond the shell closure at the magi...

On laser spectroscopy of the element nobelium (Z=102)

International Nuclear Information System (INIS)

Laatiaoui, M.; Backe, H.; Lauth, W.; Block, M.; Hessberger, F.P.; Kunz, P.; Lautenschlaeger, F.; Walther, T.; Sewtz, M.

2014-01-01

Optical transitions were sought for in 254 No, which was produced at the UNILAC accelerator at GSI in the reaction 208 Pb( 48 Ca, 2n) 254 No. After separation from the projectile beam by the velocity filter SHIP, the nobelium ions were stopped inside a buffer gas cell and guided onto a tantalum filament. The activation energy for desorption of nobelium from tantalum was determined to be 246 (24) kJ/mol. In a first experiment, the search for the 7s7p 1 P 1 level of nobelium by laser resonance ionization spectroscopy was started. Based on level predictions by multi-configuration Dirac-Fock and relativistic coupled-cluster calculations, the wavenumber ranges from 25900 cm -1 to 28260 cm -1 and from 28040 cm -1 to 31000 cm -1 were scanned with two excimer laser-pumped dye lasers and a frequency doubled Nd:YAG laser pumped OPO system, respectively. The measurements delivered no clear evidence for a resonance. However, five wavenumber positions, viz. 27997 cm -1 , 28015 cm - 1, 28230 cm -1 , 28792 cm -1 , and 29516 cm -1 , remain potential candidates for the transition and subject for upcoming investigations. (authors)

Spectroscopic scanning tunneling microscopy insights into Fe-based superconductors

International Nuclear Information System (INIS)

Hoffman, Jennifer E

2011-01-01

In the first three years since the discovery of Fe-based high T c superconductors, scanning tunneling microscopy (STM) and spectroscopy have shed light on three important questions. First, STM has demonstrated the complexity of the pairing symmetry in Fe-based materials. Phase-sensitive quasiparticle interference (QPI) imaging and low temperature spectroscopy have shown that the pairing order parameter varies from nodal to nodeless s± within a single family, FeTe 1-x Se x . Second, STM has imaged C4 → C2 symmetry breaking in the electronic states of both parent and superconducting materials. As a local probe, STM is in a strong position to understand the interactions between these broken symmetry states and superconductivity. Finally, STM has been used to image the vortex state, giving insights into the technical problem of vortex pinning, and the fundamental problem of the competing states introduced when superconductivity is locally quenched by a magnetic field. Here we give a pedagogical introduction to STM and QPI imaging, discuss the specific challenges associated with extracting bulk properties from the study of surfaces, and report on progress made in understanding Fe-based superconductors using STM techniques.

Time-resolved x-ray laser induced photoelectron spectroscopy of isochoric heated copper

International Nuclear Information System (INIS)

Nelson, A.J.; Dunn, J.; Hunter, J.; Widmann, K.

2005-01-01

Time-resolved x-ray photoelectron spectroscopy is used to probe the nonsteady-state evolution of the valence band electronic structure of laser heated ultrathin (50 nm) copper. A metastable phase is studied using a 527 nm wavelength 400 fs laser pulse containing 0.1-2.5 mJ laser energy focused in a large 500x700 μm 2 spot to create heated conditions of 0.07-1.8x10 12 W cm -2 intensity. Valence band photoemission spectra are presented showing the changing occupancy of the Cu 3d level with heating are presented. These picosecond x-ray laser induced time-resolved photoemission spectra of laser-heated ultrathin Cu foil show dynamic changes in the electronic structure. The ultrafast nature of this technique lends itself to true single-state measurements of shocked and heated materials

Coherent and correlated spin transport in nanoscale superconductors

Energy Technology Data Exchange (ETDEWEB)

Morten, Jan Petter

2008-03-15

Motivated by the desire for better understanding of nano electronic systems, we theoretically study the conductance and noise characteristics of current flow between superconductors, ferromagnets, and normal-metals. Such nano structures can reveal information about superconductor proximity effects, spin-relaxation processes, and spintronic effects with potential applications for different areas of mesoscopic physics. We employ the quasiclassical theory of superconductivity in the Keldysh formalism, and calculate the nonequilibrium transport of spin and charge using various approaches like the circuit theory of quantum transport and full counting statistics. For two of the studied structures, we have been able to compare our theory to experimental data and obtain good agreement. Transport and relaxation of spin polarized current in superconductors is governed by energy-dependent transport coefficients and spin-flip rates which are determined by quantum interference effects. We calculate the resulting temperature-dependent spin flow in ferromagnet-superconductor devices. Experimental data for spin accumulation and spin relaxation in a superconducting nano wire is in agreement with the theory, and allows for a spin-flip spectroscopy that determines the dominant mechanism for spin-flip relaxation in the studied samples. A ferromagnet precessing under resonance conditions can give rise to pure spin current injection into superconductors. We find that the absorbed spin current is measurable as a temperature dependent Gilbert damping, which we calculate and compare to experimental data. Crossed Andreev reflection denotes superconducting pairing of electrons flowing from different normal-metal or ferromagnet terminals into a superconductor. We calculate the nonlocal currents resulting from this process in competition with direct electron transport between the normal-metal terminals. We take dephasing into account, and study the nonlocal current when the types of contact in

PREFACE: 21st International Conference on Laser Spectroscopy - ICOLS 2013

Science.gov (United States)

Budker, Dmitry; Häffner, Hartmut; Müller, Holger

2013-12-01

The 21st International Conference on Laser Spectroscopy (ICOLS) took place at Berkeley, California on 9-14 June 2013. Following the tradition of previous meetings in this series, the conference featured about thirty invited talks broadly covering this burgeoning field of science that refuses to show any sign of saturation after more than half a century of continuous boom. In addition to the invited talks, there were two informative poster sessions, where the more than 300 ICOLS participants had an opportunity to exchange the latest scientific news and ideas while enjoying the gorgeous view of the San Francisco Bay from the vista of the Claremont Hotel, the meeting's venue. The heights of the cultural program of the meeting were excursions to several of the Bay Area gems (including the Lick observatory), as well as the conference banquet where the participants were treated to addresses by an inventor of the laser Professor Charles H Townes, a nonlinear optics pioneer Professor Erwin L Hahn, and one of the previous ICOLS chairs Professor Y R Shen. While the field of Laser Spectroscopy and the series of the bi-annual ICOLS meetings are as 'healthy' as one could imagine, the same cannot be said about the concept of published conference proceedings. With new ways to publish scientific articles and preprints, submitting papers to conference proceedings seems to be rapidly losing popularity. For this meeting, the great interest in attendance and opportunities to present is sharply contrasted with a somewhat sluggish response to the call for submission of the proceedings papers. The present collection represents a dozen or so contributions from the 'hero' invited speakers, to whom we are deeply grateful for submitting their work. We hope that this selection will faithfully convey to the readers the excitement of modern laser spectroscopy. In addition to these papers, we draw the reader's attention to the audio recordings and selected viewgraphs from the invited talks, and

$\\beta$-delayed fission, laser spectroscopy and shape-coexistence studies with radioactive At beams

CERN Multimedia

We propose to study the $\\beta$-delayed fission, laser spectroscopy and radioactive decay of the newly available pure beams of neutron-deficient and neutron-rich astatine (Z=85) isotopes. The fission probability and the fission fragment distribution of the even-even isotopes $^{194,196}$Po following the $\\beta$-decay of the isotopes $^{194,196}$At will be studied with the Windmill setup. In-source laser spectroscopy will be performed on the entire astatine isotopic chain, using a combination of the Windmill setup, ISOLTRAP MR-ToF and ISOLDE Faraday. Radioactive decay data will be acquired at the Windmill setup throughout those studies and contribute to the global understanding of the phenomenon of shape coexistence in the neutron-deficient lead region.

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

Precision atomic beam density characterization by diode laser absorption spectroscopy

Energy Technology Data Exchange (ETDEWEB)

Oxley, Paul; Wihbey, Joseph [Physics Department, The College of the Holy Cross, Worcester, Massachusetts 01610 (United States)

2016-09-15

We provide experimental and theoretical details of a simple technique to determine absolute line-of-sight integrated atomic beam densities based on resonant laser absorption. In our experiments, a thermal lithium beam is chopped on and off while the frequency of a laser crossing the beam at right angles is scanned slowly across the resonance transition. A lock-in amplifier detects the laser absorption signal at the chop frequency from which the atomic density is determined. The accuracy of our experimental method is confirmed using the related technique of wavelength modulation spectroscopy. For beams which absorb of order 1% of the incident laser light, our measurements allow the beam density to be determined to an accuracy better than 5% and with a precision of 3% on a time scale of order 1 s. Fractional absorptions of order 10{sup −5} are detectable on a one-minute time scale when we employ a double laser beam technique which limits laser intensity noise. For a lithium beam with a thickness of 9 mm, we have measured atomic densities as low as 5 × 10{sup 4} atoms cm{sup −3}. The simplicity of our technique and the details we provide should allow our method to be easily implemented in most atomic or molecular beam apparatuses.

Precision atomic beam density characterization by diode laser absorption spectroscopy

International Nuclear Information System (INIS)

Oxley, Paul; Wihbey, Joseph

2016-01-01

We provide experimental and theoretical details of a simple technique to determine absolute line-of-sight integrated atomic beam densities based on resonant laser absorption. In our experiments, a thermal lithium beam is chopped on and off while the frequency of a laser crossing the beam at right angles is scanned slowly across the resonance transition. A lock-in amplifier detects the laser absorption signal at the chop frequency from which the atomic density is determined. The accuracy of our experimental method is confirmed using the related technique of wavelength modulation spectroscopy. For beams which absorb of order 1% of the incident laser light, our measurements allow the beam density to be determined to an accuracy better than 5% and with a precision of 3% on a time scale of order 1 s. Fractional absorptions of order 10 −5 are detectable on a one-minute time scale when we employ a double laser beam technique which limits laser intensity noise. For a lithium beam with a thickness of 9 mm, we have measured atomic densities as low as 5 × 10 4 atoms cm −3 . The simplicity of our technique and the details we provide should allow our method to be easily implemented in most atomic or molecular beam apparatuses.

Precision atomic beam density characterization by diode laser absorption spectroscopy.

Science.gov (United States)

Oxley, Paul; Wihbey, Joseph

2016-09-01

We provide experimental and theoretical details of a simple technique to determine absolute line-of-sight integrated atomic beam densities based on resonant laser absorption. In our experiments, a thermal lithium beam is chopped on and off while the frequency of a laser crossing the beam at right angles is scanned slowly across the resonance transition. A lock-in amplifier detects the laser absorption signal at the chop frequency from which the atomic density is determined. The accuracy of our experimental method is confirmed using the related technique of wavelength modulation spectroscopy. For beams which absorb of order 1% of the incident laser light, our measurements allow the beam density to be determined to an accuracy better than 5% and with a precision of 3% on a time scale of order 1 s. Fractional absorptions of order 10 -5 are detectable on a one-minute time scale when we employ a double laser beam technique which limits laser intensity noise. For a lithium beam with a thickness of 9 mm, we have measured atomic densities as low as 5 × 10 4 atoms cm -3 . The simplicity of our technique and the details we provide should allow our method to be easily implemented in most atomic or molecular beam apparatuses.

Fabrication of high temperature superconductors

Science.gov (United States)

Balachandran, Uthamalingam; Dorris, Stephen E.; Ma, Beihai; Li, Meiya

2003-06-17

A method of forming a biaxially aligned superconductor on a non-biaxially aligned substrate substantially chemically inert to the biaxially aligned superconductor comprising is disclosed. A non-biaxially aligned substrate chemically inert to the superconductor is provided and a biaxially aligned superconductor material is deposited directly on the non-biaxially aligned substrate. A method forming a plume of superconductor material and contacting the plume and the non-biaxially aligned substrate at an angle greater than 0.degree. and less than 90.degree. to deposit a biaxially aligned superconductor on the non-biaxially aligned substrate is also disclosed. Various superconductors and substrates are illustrated.

Laser Induced Breakdown Spectroscopy, advances in resolution and portability

International Nuclear Information System (INIS)

Ponce, L.; Flores, T.; Arronte, M.; Moreira, L.; Hernandez, L. C.; Posada, E. de

2009-01-01

Laser Induced Breakdown Spectroscopy (LIBS), can be considered as one of the most dynamic and promising technique in the field of analytical spectroscopy. LIBS has turned into a powerful alternative for a wide front of applications, from the geological exploration to the industrial inspection, including the environmental monitoring, the biomedical analysis, the study of patrimonial works, the safety and defense. The advances in LIBS instrumentation have allowed improving gradually the analysis services and quality, on the basis of a better knowledge of the technology principles. Recently, systems of double pulse have facilitated a better dosing of energy, the improvement of the signal-noise relation and the study of the different process stages. Femtosecond lasers offers the possibility of study in detail the ablation and atomic emission processes. New advances like multi-pulse or multi-wavelength systems -in fact stilling without exploring, must offer new information to advance in this knowledge. Finally, which it does to this technology really attractive, is the aptitude to be employed in field conditions, or for the detection of the elementary composition at long distances. In this presentation there are discussed the designs of portable instrumentation, compact and low cost, which can improve substantially the LIBS possibilities. (Author)

Axial segregation in high intensity discharge lamps measured by laser absorption spectroscopy

NARCIS (Netherlands)

Stoffels, W.W.; Flikweert, A.J.; Nimalasuriya, T.; Groothuis, C.H.J.M.; Haverlag, M.; Kroesen, G.M.W.

2005-01-01

HID lamps containing rare earth additives (in our case dysprosium) show color separation because of axial segregation, caused by diffusion and convection. Two-dimensional atomic Dy density profiles are measured by means of laser absorption spectroscopy. The radially resolved atomic density

Laser-produced lithium plasma as a narrow-band extended ultraviolet radiation source for photoelectron spectroscopy.

Science.gov (United States)

Schriever, G; Mager, S; Naweed, A; Engel, A; Bergmann, K; Lebert, R

1998-03-01

Extended ultraviolet (EUV) emission characteristics of a laser-produced lithium plasma are determined with regard to the requirements of x-ray photoelectron spectroscopy. The main features of interest are spectral distribution, photon flux, bandwidth, source size, and emission duration. Laser-produced lithium plasmas are characterized as emitters of intense narrow-band EUV radiation. It can be estimated that the lithium Lyman-alpha line emission in combination with an ellipsoidal silicon/molybdenum multilayer mirror is a suitable EUV source for an x-ray photoelectron spectroscopy microscope with a 50-meV energy resolution and a 10-mum lateral resolution.

Analysis of fresco by laser induced breakdown spectroscopy

International Nuclear Information System (INIS)

Caneve, L.; Diamanti, A.; Grimaldi, F.; Palleschi, G.; Spizzichino, V.; Valentini, F.

2010-01-01

The laser-based techniques have been shown to be a very powerful tool for artworks characterization and are used in the field of cultural heritage for the offered advantages of minimum invasiveness, in situ applicability and high sensitivity. Laser induced breakdown spectroscopy, in particular, has been applied in this field to many different kinds of ancient materials with successful results. In this work, a fragment of a Roman wall painting from the archaeological area of Pompeii has been investigated by LIBS. The sample elemental composition resulting from LIBS measurements suggested the presence of certain pigments. The ratio of the intensities of different lines related to some characteristic elements is proposed as an indicator for pigment recognition. The depth profiling permitted to put in evidence the presence of successive paint layers with different compositions. A comparison with the results obtained by the microscopy inspection of the sample has been done.

Scanning tunneling microscopy/scanning tunneling spectroscopy of the organic superconductors (TNTSF)2-PF6 and (TMTSF)2-ClO4

International Nuclear Information System (INIS)

Fainchtein, R.; Murphy, J.C.

1991-01-01

This paper reports on direct observations of the organic superconductors (tetramethyltetraselenafulvalene) (TMTSF) 2 -PF 6 and (TMTSF) 2 -ClO 4 made in air at room temperature. The samples consisted of single crystals electrochemically grown. Images revealing the molecular structural arrangement along different crystallographic orientations will be presented as well as spectroscopic data related to the electronic density of states. The images reveal a structure made up of flat molecules that stack on top of one another to form columns and are responsible for the quasi-one-dimensional nature of the electrical conductivity. Although both materials have similar crystal structure the differences in the symmetry and orientation of the counter anions are not resolved. Tunneling spectroscopy data at room temperature shows no apparent difference in the electronic density of states of both materials

[Classification of results of studying blood plasma with laser correlation spectroscopy based on semiotics of preclinical and clinical states].

Science.gov (United States)

Ternovoĭ, K S; Kryzhanovskiĭ, G N; Musiĭchuk, Iu I; Noskin, L A; Klopov, N V; Noskin, V A; Starodub, N F

1998-01-01

The usage of laser correlation spectroscopy for verification of preclinical and clinical states is substantiated. Developed "semiotic" classifier for solving the problems of preclinical and clinical states is presented. The substantiation of biological algorithms as well as the mathematical support and software for the proposed classifier for the data of laser correlation spectroscopy of blood plasma are presented.

Laser spectroscopy of collisionally prepared target species: atomic caesium

International Nuclear Information System (INIS)

Moreau, J.-P.; Tremblay, Julien; Knystautas, E.J.; Laperriere, S.C.; Larzilliere, Michel

1989-01-01

Fast ion beam bombardment was used to collisionally prepare a target gas in excited states, to which conventional laser spectroscopy was then applied. The versatility of this method is demonstrated with atomic targets of caesium, for a state of Cs + that is 16 eV above the ground state, as well as for a short-lived state (38 ns) of the neutral atom. The local temperature in the caesium oven is also obtained. (Author)

Sub-Doppler spectroscopy

International Nuclear Information System (INIS)

Hansch, T.W.

1983-01-01

This chapter examines Doppler-free saturation spectroscopy, tunable cw sources, and Doppler-free two-photon spectroscopy. Discusses saturation spectroscopy; continuous wave saturation spectroscopy in the ultraviolet; and two-photon spectroscopy of atomic hydrogen 1S-2S. Focuses on Doppler-free laser spectroscopy of gaseous samples. Explains that in saturation spectroscopy, a monochromatic laser beam ''labels'' a group of atoms within a narrow range of axial velocities through excitation or optical pumping, and a Doppler-free spectrum of these selected atoms is observed with a second, counterpropagating beam. Notes that in two-photon spectroscopy it is possible to record Doppler-free spectra without any need for velocity selection by excitation with two counterpropagating laser beams whose first order Doppler shifts cancel

Continuous lengths of oxide superconductors

Science.gov (United States)

Kroeger, Donald M.; List, III, Frederick A.

2000-01-01

A layered oxide superconductor prepared by depositing a superconductor precursor powder on a continuous length of a first substrate ribbon. A continuous length of a second substrate ribbon is overlaid on the first substrate ribbon. Sufficient pressure is applied to form a bound layered superconductor precursor powder between the first substrate ribbon and the second substrate ribbon. The layered superconductor precursor is then heat treated to establish the oxide superconducting phase. The layered oxide superconductor has a smooth interface between the substrate and the oxide superconductor.

Rapid-swept CW cavity ring-down laser spectroscopy for carbon isotope analysis

International Nuclear Information System (INIS)

Tomita, Hideki; Watanabe, Kenichi; Takiguchi, Yu; Kawarabayashi, Jun; Iguchi, Tetsuo

2006-01-01

With the aim of developing a portable system for an in field isotope analysis, we investigate an isotope analysis based on rapid-swept CW cavity ring-down laser spectroscopy, in which the concentration of a chemical species is derived from its photo absorbance. Such a system can identify the isotopomer and still be constructed as a quite compact system. We have made some basic experimental measurements of the overtone absorption lines of carbon dioxide ( 12 C 16 O 2 , 13 C 16 O 2 ) by rapid-swept cavity ring-down spectroscopy with a CW infrared diode laser at 6,200 cm -1 (1.6 μm). The isotopic ratio has been obtained as (1.07±0.13)x10 -2 , in good agreement with the natural abundance within experimental uncertainty. The detection sensitivity in absorbance has been estimated to be 3x10 -8 cm -1 . (author)

Process analysis of recycled thermoplasts from consumer electronics by laser-induced plasma spectroscopy.

Science.gov (United States)

Fink, Herbert; Panne, Ulrich; Niessner, Reinhard

2002-09-01

An experimental setup for direct elemental analysis of recycled thermoplasts from consumer electronics by laser-induced plasma spectroscopy (LIPS, or laser-induced breakdown spectroscopy, LIBS) was realized. The combination of a echelle spectrograph, featuring a high resolution with a broad spectral coverage, with multivariate methods, such as PLS, PCR, and variable subset selection via a genetic algorithm, resulted in considerable improvements in selectivity and sensitivity for this complex matrix. With a normalization to carbon as internal standard, the limits of detection were in the ppm range. A preliminary pattern recognition study points to the possibility of polymer recognition via the line-rich echelle spectra. Several experiments at an extruder within a recycling plant demonstrated successfully the capability of LIPS for different kinds of routine on-line process analysis.

Production of photofission fragments and study of their nuclear structure by laser spectroscopy

International Nuclear Information System (INIS)

Gangrskij, Yu.P.; Zemlyanoj, S.G.; Karaivanov, D.V.; Marinova, K.P.; Markov, B.N.; Mel'nikova, L.M.; Myshinskij, G.V.; Penionzhkevich, Yu.Eh.; Zhemenik, V.I.

2005-01-01

The prospective nuclear structure investigations of the fission fragments by resonance laser spectroscopy methods are discussed. Research in this field is currently being carried out as part of the DRIBs project, which is under development at the Laboratory of Nuclear Reactions, JINR. The fission fragments under study are mainly very neutron-rich nuclei near the proton (Z=50) and neutron (N=50 and 82) closed shells, nuclei in the region of strong deformation (N>60 and N>90) and nuclei with high-spin isomeric states. Resonance laser spectroscopy is used successfully in the study of the structure of such nuclei. It allows one to determine a number of nuclear parameters (mean-square charge radius, magnetic dipole and electric quadrupole moments) and to make conclusions about the collective and single particle properties of the nuclei

Determination of Different Metals in Steel Waste Samples Using laser Induced Breakdown Spectroscopy

Directory of Open Access Journals (Sweden)

A. H. Bakry

2007-12-01

Full Text Available Elemental analysis of waste samples collected from steel products manufacturing plant (SPS located at industrial city of Jeddah, Saudi-Arabia has been carried out using Laser Induced Breakdown Spectroscopy (LIBS. The 1064 nm laser radiations from a Nd:YAG laser at an irradiance of 7.6  1010 W cm –2 were used. Atomic emission spectra of the elements present in the waste samples were recorded in the 200 – 620 nm region. Elements such as Fe, W, Ti, Al, Mg, Ca, S, Mn, and Na were detected in these samples. Quantitative determination of the elemental concentration was obtained for these metals against certified standard samples. Parametric dependences of LIBS signal intensity on incident laser energy and time delay between the laser pulse and data acquisition system were also carried out.

Discrimination of forensic trace evidence using laser induced breakdown spectroscopy

Science.gov (United States)

Bridge, Candice Mae

Elemental analysis in forensic laboratories can be tedious and many trace evidence items are not analyzed to determine their elemental composition. Presently, scanning electron microscopy-energy dispersive x-ray spectroscopy (SEM-EDS) is the primary analytical tool for determining the elemental composition of trace evidence items. However, due to the time it takes to obtain the required vacuum and the limited number of samples that can be analyzed at any one time, SEM-EDS can be impractical for a high volume of evidence items. An alternative instrument that can be used for this type of analysis is laser ablation inductively coupled plasma mass spectrometry (LA-ICP-MS). While LA-ICP-MS is a very precise and quantitative analytical method that determines elemental composition based on isotopic mass measurements; however, the instrumentation is relatively expensive and therefore is budgetarily prohibitive for many forensic laboratories. It is the purpose of this research to evaluate an inexpensive instrument that can potentially provide rapid elemental analysis for many forensic laboratories. Laser induced breakdown spectroscopy (LIBS) is an analytical method that meets these requirements and offers information about the elemental composition based on ionic, atomic and diatomic molecular emissions.

Tunneling spectroscopy of a spiral Luttinger liquid in contact with superconductors

Science.gov (United States)

Liu, Dong E.; Levchenko, Alex

2014-03-01

One-dimensional wires with Rashba spin-orbit coupling, magnetic field, and strong electron-electron interactions are described by a spiral Luttinger liquid model. We develop a theory to investigate the tunneling density of states into a spiral Luttinger liquid in contact with superconductors at its two ends. This approach provides a way to disentangle the delicate interplay between superconducting correlations and strong electron interactions. If the wire-superconductor boundary is dominated by Andreev reflection, we find that in the vicinity of the interface the zero-bias tunneling anomaly reveals a power law enhancement with the unusual exponent. This zero-bias due to Andreev reflections may coexist and thus mask possible peak due to Majorana bound states. Far away from the interface strong correlations inherent to the Luttinger liquid prevail and restore conventional suppression of the tunneling density of states at the Fermi level, which acquires a Friedel-like oscillatory envelope with the period renormalized by the strength of the interaction. D.E.L. was supported by Michigan State University and in part by ARO through Contract No. W911NF-12-1-0235. A.L. acknowledges support from NSF under Grant No. PHYS-1066293, and the hospitality of the Aspen Center for Physics.

Online analysis of potassium fertilizers by Laser-Induced Breakdown Spectroscopy

International Nuclear Information System (INIS)

Groisman, Y.; Gaft, M.

2010-01-01

Presently, online analysis in potassium fertilizers industry is performed by Natural Radioactivity Analyzers. Laser Distance Spectrometry (LDS) has tested, by laboratory scale, the possibility of Laser-Induced Breakdown Spectroscopy (LIBS) technique implementation for online fertilizers production control. The main advantage of the system comparing to the existing technique is the principal possibility to analyze all relevant elements, such as K, Na, Mg, and not only K40 isotope as done in natural radiation analytical systems. Good correlations between online LIBS results with chemical analysis data of K, Na and Mg impurities of samples from Russia, Belarus and Israel demonstrate that LIBS system is a perspective tool for online control of those elements in field conditions.

LASER CORRELATION SPECTROSCOPY (LCS AND ITS CLINICAL PERSPECTIVES IN OPHTHALMOLOGY

Directory of Open Access Journals (Sweden)

Karganov Mikhail

2015-12-01

Full Text Available The method of laser correlation spectroscopy (LCS is based on the analysis of the spectrum of quasielastic light scatter during coherent monochromatic laser irradiation of micro-particles in biological fluids (blood serum, urine, oropharyngeal washout fluid, tear fluid etc.. Spectrum provides information on dynamic processes in the analyzed system: translation motion of scattering particles and their orientation and conformation dynamics. Special procedures of cluster analysis make it possible to find out to which linkage group a particular spectrum belongs. LCS allows evaluation of sub-fractional composition of biological fluids in a wide range of molecular sizes (from 1 to 10,000 nm, which determines principal novelty of this approach in ophthalmology.

Infrared and visible laser spectroscopy for highly-charged Ni-like ions

Science.gov (United States)

Ralchenko, Yuri

2017-10-01

Application of visible or infrared (IR) lasers for spectroscopy of highly-charged ions (HCI) has not been particularly extensive so far due to a mismatch in typical energies. We show here that the energy difference between the two lowest levels within the first excited configuration 3d9 4 s in Ni-like ions of heavy elements from ZN = 60 to ZN = 92 is within the range of visible or near-IR lasers. The wavelengths of these transitions are calculated within the relativistic model potential formalism and compared with other theoretical and limited experimental data. Detailed collisional-radiative simulations of non-Maxwellian and thermal plasmas are performed showing that photopumping between these levels using relatively moderate lasers is sufficient to provide a two-order of magnitude increase of the pumped level population. This accordingly results in a similar rise of the X-ray line intensity thereby allowing control of X-ray emission with visible/IR lasers.

Doppler-free laser spectroscopy of buffer-gas-cooled molecular radicals

International Nuclear Information System (INIS)

Skoff, S M; Hendricks, R J; Sinclair, C D J; Tarbutt, M R; Hudson, J J; Segal, D M; Sauer, B E; Hinds, E A

2009-01-01

We demonstrate Doppler-free saturated absorption spectroscopy of cold molecular radicals formed by laser ablation inside a cryogenic buffer gas cell. By lowering the temperature, congested regions of the spectrum can be simplified, and by using different temperatures for different regions of the spectrum a wide range of rotational states can be studied optimally. We use the technique to study the optical spectrum of YbF radicals with a resolution of 30 MHz, measuring the magnetic hyperfine parameters of the electronic ground state. The method is suitable for high-resolution spectroscopy of a great variety of molecules at controlled temperature and pressure, and is particularly well suited to those that are difficult to produce in the gas phase.

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.

Time-resolved tunable diode laser absorption spectroscopy of pulsed plasma

Czech Academy of Sciences Publication Activity Database

Adámek, Petr; Olejníček, Jiří; Čada, Martin; Kment, Š.; Hubička, Zdeněk

2013-01-01

Roč. 38, č. 14 (2013), s. 2428-2430 ISSN 0146-9592 R&D Projects: GA MŠk LH12045; GA ČR(CZ) GAP205/11/0386; GA MŠk LD12002; GA MŠk LH12043 Institutional support: RVO:68378271 Keywords : diode laser s * plasma diagnostics * absorption spectroscopy * time resolved Subject RIV: BL - Plasma and Gas Discharge Physics Impact factor: 3.179, year: 2013

Surface cleaning and adsorbate layer formation: Dual role of alkylamines in the formation of self-assembled monolayers on cuprate superconductors

International Nuclear Information System (INIS)

Ritchie, J.E.; Murray, W.R.; Kershan, K.; Diaz, V.; Tran, L.; McDevitt, J.T.

1999-01-01

The development of monolayer adsorption chemistry for superconductor surfaces is particularly important for a number of practical and fundamental reasons. As high-T c superconductors begin to approach the marketplace in areas of communications, power industries, medical applications, and scientific instrumentation, the development of new soft chemistry approaches for the surface modification of these technologically relevant electronic materials becomes increasingly important. Monolayer adsorption chemistry has been developed extensively for electronic materials such as metals, semiconductors, and insulators. These methodologies have been expanded recently to include a variety of high-temperature superconductors (HTSCs). The authors describe a series of new X-ray photoelectron spectroscopy (XPS), four-point conductivity, critical current, atomic absorption spectroscopy (AAS), grazing angle infrared spectroscopy, and GE--MS experiments, which lead the suggestion that an entirely different mechanism is involved in the formation of HTSC-localized monolayers. According to the new model, the amine reagents serve two chemically distinct roles. In the initial phase, the degraded superconductor exteriors is etched away with the help of the amine compounds. The etching process proceeds to the point where fresh YBa 2 Cu 3 O 7 is exposed, and only at this point do the amines adsorb and remain at the YBa 2 Cu 3 O 7 surface. As the adsorption process continues, there is an accumulation of an organized monolayer at the surface, which prevents further etching of the YBa 2 Cu 3 O 7 material

Characterization of coal fly ash components by laser-induced breakdown spectroscopy

International Nuclear Information System (INIS)

Ctvrtnickova, Tereza; Mateo, Mari-Paz; Yanez, Armando; Nicolas, Gines

2009-01-01

The high sensitivity of laser-induced breakdown spectroscopy (LIBS) for the detection of most of the fly ash components enables the analysis of these residues produced during the combustion of coal. Fly ash consists of oxides (SiO 2 , Al 2 O 3 , Fe 2 O 3 , CaO...) and unburnt carbon which is the major determinant of combustion efficiency in coal fired boilers. For example, an excessive amount of residual carbon dispersed in the fly ash means a significant loss of energy (Styszko et al., 2004). Standard methods employed for the analysis of fly ash make not possible a control of boiler in real time. LIBS technique can significantly reduce the time of analysis, in some cases even an online detection can be performed. For this reason, some studies have been addressed in order to demonstrate the capability of the laser-induced breakdown spectroscopy technique for the detection of carbon content in high pressure conditions typical of thermal power plants (Noda et al., 2002) and for the monitoring of unburnt carbon for the boiler control in real time (Kurihara et al., 2003). In particular, the content of unburnt carbon is a valuable indicator for the control of fly ash quality and for the boiler combustion. Depending on this unburnt carbon content, fly ash can be disposed as an industrial waste or as a raw material for the production of concrete in the construction sector. In this study, analyses were performed on specimens of various forms of preparation. Pressed pellets were prepared with two different binders. Presented results concern the nature and amount of the binder used to pelletize the powder, and the laser-induced breakdown spectroscopy parameters and procedure required to draw calibration curves of elements from the fly ash. Analysis 'on tape' was performed in order to establish the experimental conditions for the future 'online analysis'.

Cavity-enhanced resonant photoacoustic spectroscopy with optical feedback cw diode lasers: A novel technique for ultratrace gas analysis and high-resolution spectroscopy.

Science.gov (United States)

Hippler, Michael; Mohr, Christian; Keen, Katherine A; McNaghten, Edward D

2010-07-28

Cavity-enhanced resonant photoacoustic spectroscopy with optical feedback cw diode lasers (OF-CERPAS) is introduced as a novel technique for ultratrace gas analysis and high-resolution spectroscopy. In the scheme, a single-mode cw diode laser (3 mW, 635 nm) is coupled into a high-finesse linear cavity and stabilized to the cavity by optical feedback. Inside the cavity, a build-up of laser power to at least 2.5 W occurs. Absorbing gas phase species inside the cavity are detected with high sensitivity by the photoacoustic effect using a microphone embedded in the cavity. To increase sensitivity further, coupling into the cavity is modulated at a frequency corresponding to a longitudinal resonance of an organ pipe acoustic resonator (f=1.35 kHz and Q approximately 10). The technique has been characterized by measuring very weak water overtone transitions near 635 nm. Normalized noise-equivalent absorption coefficients are determined as alpha approximately 4.4x10(-9) cm(-1) s(1/2) (1 s integration time) and 2.6x10(-11) cm(-1) s(1/2) W (1 s integration time and 1 W laser power). These sensitivities compare favorably with existing state-of-the-art techniques. As an advantage, OF-CERPAS is a "zero-background" method which increases selectivity and sensitivity, and its sensitivity scales with laser power.

An infrared view of high Tc superconductors

International Nuclear Information System (INIS)

Tanner, D.B.; Timusk, T.; McMaster Univ., Hamilton, ON

1989-01-01

Studies of the infrared properties of the high T c superconductors are reviewed, with particular emphasis on attempts to determine the energy gap by far infrared spectroscopy and on the properties of the strong absorption that occurs in the mid infrared. The authors argue that this mid-infrared absorption is a direct particle-hole excitation rather than a Holstein emission process. In addition, they conclude that although the energy gap is not easily observed, several recent experiments place it in the weak to moderate strong coupling range

Q-switched Nd:YAG/V:YAG microchip 1338 nm laser for laser-induced breakdown spectroscopy

Science.gov (United States)

Šulc, Jan; Jelínková, Helena; Nejezchleb, Karel; Škoda, Václav

2017-12-01

Q-switched microchip laser emitting radiation at wavelength 1338nm was tested as a radiation source for laser induced breakdown spectroscopy (LIBS). This laser used sandwich crystal which combined in one piece the cooling part (undoped YAG crystal 4mm long), the active laser part (Nd:YAG crystal 12mm long), and the saturable absorber (V:YAG crystal 0.7mm long). The diameter of this crystal was 5 mm. The microchip resonator consisted of dielectric mirrors directly deposited on the monolith crystal surfaces. The pump mirror (HT @ 808 nm, HR @ 1.3 ¹m) was placed on the undoped YAG part. The output coupler (R = 90% @ 1338 nm) was placed on the V:YAG part. The fibre-coupled 808nm pumping laser diode was operating in pulsed regime (rep. rate 250 Hz, pulse width 300 ¹s, pulse energy 6 mJ). Using this pumping, stable and high reproducible Q-switched pulses were generated at wavelength 1338 nm. Pulse length was 6.2 ns (FWHM) and the mean output power was 33mW. The single pulse energy and peak power was 0.13mJ and 21kW, respectively. Laser was operating in fundamental TEM00 mode. The laser radiation was focused on a tested sample using single plano-convex lens (focal length 75 mm). The focal spot radius was 40 ¹m. The corresponding peak-power density was 0.83GW/cm2. The laser induced break-down was successfully reached and corresponding laser-induced plasma spectra were recorded for set of metallic elements (Cu, Ag, Au, In, Zn, Al, Fe, Ni, Cr) and alloys (Sn-Pb solder, duralumin, stainless-steel, brass). To record the spectra, StellarNet BLACK-Comet concave grating CCD-based spectrometer was used without any special collimation optics. Thanks to used laser wavelength far from the detector sensitivity, no special filtering was needed to overcome the CCD dazzling. The constructed laser could significantly improve repletion-rate of up-to-date LIBS devices.

Chapter 27. Superconductors

International Nuclear Information System (INIS)

Vavra, O.

2007-01-01

In this chapter author deals with superconductors and superconductivity. Different chemical materials used as high-temperature superconductors are presented. Some applications of superconductivity are presented.

Laser spectroscopy of antiprotonic helium

CERN Document Server

Hori, M

2005-01-01

When antiprotons (i.e. the antimatter counterpart of protons) are stopped in helium gas, 97% of them annihilate within picoseconds by reacting with the helium nuclei; a 3% fraction, however, survive with an anomalously long lifetime of several microseconds. This longevity is due to the formation of antiprotonic helium, which is a three-body Rydberg atom composed of an antiproton, electron, and helium nucleus. The ASACUSA experimental collaboration has recently synthesized large numbers of these atoms using CERN's Antiproton Decelerator facility, and measured the atom's transition frequencies to 60 parts per billion by laser spectroscopy. By comparing the experimental results with recent three-body QED calculations and the known antiproton cyclotron frequency, we were able to show that the antiproton mass and charge are the same as the corresponding proton values to a precision of 10 parts per billion. Ongoing and future series of experiments will further improve the experimental precision by using chirp-compe...

Optical emission spectroscopy of metal vapor dominated laser-arc hybrid welding plasma

International Nuclear Information System (INIS)

Ribic, B.; DebRoy, T.; Burgardt, P.

2011-01-01

During laser-arc hybrid welding, plasma properties affect the welding process and the weld quality. However, hybrid welding plasmas have not been systematically studied. Here we examine electron temperatures, species densities, and electrical conductivity for laser, arc, and laser-arc hybrid welding using optical emission spectroscopy. The effects of arc currents and heat source separation distances were examined because these parameters significantly affect weld quality. Time-average plasma electron temperatures, electron and ion densities, electrical conductivity, and arc stability decrease with increasing heat source separation distance during hybrid welding. Heat source separation distance affects these properties more significantly than the arc current within the range of currents considered. Improved arc stability and higher electrical conductivity of the hybrid welding plasma result from increased heat flux, electron temperatures, electron density, and metal vapor concentrations relative to arc or laser welding.

Probing defect states in polycrystalline GaN grown on Si(111) by sub-bandgap laser-excited scanning tunneling spectroscopy

Science.gov (United States)

Hsiao, F.-M.; Schnedler, M.; Portz, V.; Huang, Y.-C.; Huang, B.-C.; Shih, M.-C.; Chang, C.-W.; Tu, L.-W.; Eisele, H.; Dunin-Borkowski, R. E.; Ebert, Ph.; Chiu, Y.-P.

2017-01-01

We demonstrate the potential of sub-bandgap laser-excited cross-sectional scanning tunneling microscopy and spectroscopy to investigate the presence of defect states in semiconductors. The characterization method is illustrated on GaN layers grown on Si(111) substrates without intentional buffer layers. According to high-resolution transmission electron microscopy and cathodoluminescence spectroscopy, the GaN layers consist of nanoscale wurtzite and zincblende crystallites with varying crystal orientations and hence contain high defect state densities. In order to discriminate between band-to-band excitation and defect state excitations, we use sub-bandgap laser excitation. We probe a clear increase in the tunnel current at positive sample voltages during sub-bandgap laser illumination for the GaN layer with high defect density, but no effect is found for high quality GaN epitaxial layers. This demonstrates the excitation of free charge carriers at defect states. Thus, sub-bandgap laser-excited scanning tunneling spectroscopy is a powerful complimentary characterization tool for defect states.

Characterization of laser-induced breakdown spectroscopy (LIBS) for application to space exploration

International Nuclear Information System (INIS)

Knight, Andrew K.; Scherbarth, Nancy L.; Cremers, David A.; Ferris, Monty J.

2000-01-01

Early in the next century, several space missions are planned with the goal of landing craft on asteroids, comets, the Moon, and Mars. To increase the scientific return of these missions, new methods are needed to provide (1) significantly more analyses per mission lifetime, and (2) expanded analytical capabilities. One method that has the potential to meet both of these needs for the elemental analysis of geological samples is laser-induced breakdown spectroscopy (LIBS). These capabilities are possible because the laser plasma provides rapid analysis and the laser pulse can be focused on a remotely located sample to perform a stand-off measurement. Stand-off is defined as a distance up to 20 m between the target and laser. Here we present the results of a characterization of LIBS for the stand-off analysis of soils at reduced air pressures and in a simulated Martian atmosphere (5-7 torr pressure of CO 2 ) showing the feasibility of LIBS for space exploration. For example, it is demonstrated that an analytically useful laser plasma can be generated at distances up to 19 m by using only 35 mJ/pulse from a compact laser. Some characteristics of the laser plasma at reduced pressure were also investigated. Temporally and spectrally resolved imaging showed significant changes in the plasma as the pressure was reduced and also showed that the analyte signals and mass ablated from a target were strongly dependent on pressure. As the pressure decreased from 590 torr to the 40-100 torr range, the signals increased by a factor of about 3-4, and as the pressure was further reduced the signals decreased. This behavior can be explained by pressure-dependent changes in the mass of material vaporized and the frequency of collisions between species in the plasma. Changes in the temperature and the electron density of the plasmas with pressure were also examined and detection limits for selected elements were determined. (c) 2000 Society for Applied Spectroscopy

Characterization of laser-induced breakdown spectroscopy (LIBS) for application to space exploration

Energy Technology Data Exchange (ETDEWEB)

Knight, Andrew K. [Group CST-1, MS J565, Chemical Science and Technology Division, Los Alamos National Laboratory, Los Alamos, New Mexico 87545 (United States); Scherbarth, Nancy L. [Group CST-1, MS J565, Chemical Science and Technology Division, Los Alamos National Laboratory, Los Alamos, New Mexico 87545 (United States); Cremers, David A. [Group CST-1, MS J565, Chemical Science and Technology Division, Los Alamos National Laboratory, Los Alamos, New Mexico 87545 (United States); Ferris, Monty J. [Group CST-1, MS J565, Chemical Science and Technology Division, Los Alamos National Laboratory, Los Alamos, New Mexico 87545 (United States)

2000-03-01

Early in the next century, several space missions are planned with the goal of landing craft on asteroids, comets, the Moon, and Mars. To increase the scientific return of these missions, new methods are needed to provide (1) significantly more analyses per mission lifetime, and (2) expanded analytical capabilities. One method that has the potential to meet both of these needs for the elemental analysis of geological samples is laser-induced breakdown spectroscopy (LIBS). These capabilities are possible because the laser plasma provides rapid analysis and the laser pulse can be focused on a remotely located sample to perform a stand-off measurement. Stand-off is defined as a distance up to 20 m between the target and laser. Here we present the results of a characterization of LIBS for the stand-off analysis of soils at reduced air pressures and in a simulated Martian atmosphere (5-7 torr pressure of CO{sub 2}) showing the feasibility of LIBS for space exploration. For example, it is demonstrated that an analytically useful laser plasma can be generated at distances up to 19 m by using only 35 mJ/pulse from a compact laser. Some characteristics of the laser plasma at reduced pressure were also investigated. Temporally and spectrally resolved imaging showed significant changes in the plasma as the pressure was reduced and also showed that the analyte signals and mass ablated from a target were strongly dependent on pressure. As the pressure decreased from 590 torr to the 40-100 torr range, the signals increased by a factor of about 3-4, and as the pressure was further reduced the signals decreased. This behavior can be explained by pressure-dependent changes in the mass of material vaporized and the frequency of collisions between species in the plasma. Changes in the temperature and the electron density of the plasmas with pressure were also examined and detection limits for selected elements were determined. (c) 2000 Society for Applied Spectroscopy.

Optical emission spectroscopy of carbon laser plasma ion source

Science.gov (United States)

Balki, Oguzhan; Rahman, Md. Mahmudur; Elsayed-Ali, Hani E.

2018-04-01

Carbon laser plasma generated by an Nd:YAG laser (wavelength 1064 nm, pulse width 7 ns, fluence 4-52 J cm-2) is studied by optical emission spectroscopy and ion time-of-flight. Up to C4+ ions are detected with the ion flux strongly dependent on the laser fluence. The increase in ion charge with the laser fluence is accompanied by observation of multicharged ion lines in the optical spectra. The time-integrated electron temperature Te is calculated from the Boltzmann plot using the C II lines at 392.0, 426.7, and 588.9 nm. Te is found to increase from ∼0.83 eV for a laser fluence of 22 J cm-2 to ∼0.90 eV for 40 J cm-2. The electron density ne is obtained from the Stark broadened profiles of the C II line at 392 nm and is found to increase from ∼ 2 . 1 × 1017cm-3 for 4 J cm-2 to ∼ 3 . 5 × 1017cm-3 for 40 J cm-2. Applying an external electric field parallel to the expanding plume shows no effect on the line emission intensities. Deconvolution of ion time-of-flight signal with a shifted Maxwell-Boltzmann distribution for each charge state results in an ion temperature Ti ∼4.7 and ∼6.0 eV for 20 and 36 J cm-2, respectively.

Highly sensitive analysis of boron and lithium in aqueous solution using dual-pulse laser-induced breakdown spectroscopy.

Science.gov (United States)

Lee, Dong-Hyoung; Han, Sol-Chan; Kim, Tae-Hyeong; Yun, Jong-Il

2011-12-15

We have applied a dual-pulse laser-induced breakdown spectroscopy (DP-LIBS) to sensitively detect concentrations of boron and lithium in aqueous solution. Sequential laser pulses from two separate Q-switched Nd:YAG lasers at 532 nm wavelength have been employed to generate laser-induced plasma on a water jet. For achieving sensitive elemental detection, the optimal timing between two laser pulses was investigated. The optimum time delay between two laser pulses for the B atomic emission lines was found to be less than 3 μs and approximately 10 μs for the Li atomic emission line. Under these optimized conditions, the detection limit was attained in the range of 0.8 ppm for boron and 0.8 ppb for lithium. In particular, the sensitivity for detecting boron by excitation of laminar liquid jet was found to be excellent by nearly 2 orders of magnitude compared with 80 ppm reported in the literature. These sensitivities of laser-induced breakdown spectroscopy are very practical for the online elemental analysis of boric acid and lithium hydroxide serving as neutron absorber and pH controller in the primary coolant water of pressurized water reactors, respectively.

A conceptual design of the set-up for solid state spectroscopy with free electron laser and insertion device radiation

CERN Document Server

Makhov, V N

2001-01-01

The set-up for complex solid state spectroscopy with the use of enhanced properties of radiation from insertion devices and free electron lasers is proposed. Very high flux and pulsed properties of radiation from insertion devices and free electron lasers offer the possibility for the use of such powerful techniques as electron paramagnetic resonance (EPR) and optically detected magnetic resonance (ODMR) for the studies of excited states of electronic excitations or defects in solids. The power density of radiation can become high enough for one more method of exited-state spectroscopy: transient optical absorption spectroscopy. The set-up is supposed to combine the EPR/ODMR spectrometer, i.e. cryostat supplied with superconducting magnet and microwave system, and the optical channels for excitation (by radiation from insertion devices or free electron laser) and detection of luminescence (i.e. primary and secondary monochromators). The set-up can be used both for 'conventional' spectroscopy of solids (reflec...

Standoff Detection of Explosives at 1 m using Laser Induced Breakdown Spectroscopy

Czech Academy of Sciences Publication Activity Database

Junjuri, R.; Myakalwar, A.K.; Gundawar, M.K.

2017-01-01

Roč. 67, č. 6 (2017), s. 623-630 ISSN 0011-748X Institutional support: RVO:67985882 Keywords : Laser induced breakdown spectroscopy * Multivariate analysis * Principal component analysis * Explosive detection Subject RIV: JB - Sensors, Measurment, Regulation OBOR OECD: Electrical and electronic engineering Impact factor: 0.500, year: 2016

Superconductors with excess quasiparticles

International Nuclear Information System (INIS)

Elesin, V.F.; Kopaev, Y.V.

1981-01-01

This review presents a systematic kinetic theory of nonequilibrium phenomena in superconductors with excess quasiparticles created by electromagnetic or tunnel injection. The energy distributions of excess quasiparticles and of nonequilibrium phonons, dependence of the order parameter on the power and frequency (or intensity) of the electromagnetic field, magnetic properties of nonequilibrium superconductors, I-V curves of superconductor-insulator-superconductor junctions, and other properties are described in detail. The stability of superconducting states far from thermodynamic equilibrium is investigated and it is shown that characteristic instabilities leading to the formation of nonuniform states of a new type or phase transitions of the first kind are inherent to superconductors with excess quasiparticles. The results are compared with experimental data

How to measure the cooper pair mass using plasmons in low-dimensional superconductor structures

International Nuclear Information System (INIS)

Mishonov, T.M.

1990-06-01

The creation of the Cooper pair mass-spectroscopy is suggested. The plasmons in low-dimensional superconductor structures (layers or wires in dielectric background) are theoretically considered to that purpose. The Cooper pair mass m * can be determined by measurements of the Doppler shift of the plasmon frequency when a direct current is applied through the superconductor. The plasmons with frequency ω lower than the superconducting gap 2 Δ can be detected by the same fare-infrared (FIR) absorption technique and grating couplings used previously for investigation of two-dimension (2D) plasmons in semiconductor microstructures. (author). 17 refs, 2 figs

Remote in-situ laser-induced breakdown spectroscopy using optical fibers

Science.gov (United States)

Marquardt, Brian James

The following dissertation describes the development of methods for performing remote Laser-Induced Breakdown Spectroscopy (LIBS) using optical fibers. Studies were performed to determine the optimal excitation and collection parameters for remote LIBS measurements of glasses, soils and paint. A number of fiber-optic LIBS probes were developed and used to characterize various samples by plasma emission spectroscopy. A novel method for launching high-power laser pulses into optical fibers without causing catastrophic failure is introduced. A systematic study of a number of commercially available optical fibers was performed to determine which optical fibers were best suited for delivering high-power laser pulses. The general design of an all fiber-optic LIBS probe is described and applied to the determination of Pb in soil. A fiber-optic probe was developed for the microanalysis of solid samples remotely by LIBS, Raman spectroscopy and Raman imaging. The design of the probe allows for real-time sample imaging in-situ using coherent imaging fibers. This allows for precise atomic emission and Raman measurements to be performed remotely on samples in hostile or inaccessible environments. A novel technique was developed for collecting spectral plasma images using an acousto-optic tunable filter (AOTF). The spatial and temporal characteristics of the plasma were studied as a function of delay time. From the plasma images the distribution of Pb emission could be determined and fiber-optic designs could be optimized for signal collection. The performance of a two fiber LIBS probe is demonstrated for the determination of the amount of lead in samples of dry paint. It is shown that dry paint samples can be analyzed for their Pb content in-situ using a fiber-optic LIBS probe with detection limits well below the levels currently regulated by the Consumer Products Safety Commission. It is also shown that these measurements can be performed on both latex and enamel paints, and

What can Andreev bound states tell us about superconductors?

Science.gov (United States)

Millo, Oded; Koren, Gad

2018-08-06

Zero-energy Andreev bound states, which manifest themselves in the tunnelling spectra as zero-bias conductance peaks (ZBCPs), are abundant at interfaces between superconductors and other materials and on the nodal surface of high-temperature superconductors. In this review, we focus on the information such excitations can provide on the properties of superconductor systems. First, a general introduction to the physics of Andreev bound states in superconductor/normal metal interfaces is given with a particular emphasis on why they appear at zero energy in d -wave superconductors. Then, specific spectroscopic tunnelling studies of thin films, bilayers and junctions are described, focusing on the corresponding ZBCP features. Scanning tunnelling spectroscopy (STS) studies show that the ZBCPs on the c -axis YBa 2 Cu 3 O 7- δ (YBCO) films are correlated with the surface morphology and appear only in proximity to (110) facets. STS on c -axis La 1.88 Sr 0.12 CuO 4 (LSCO) films exhibiting the 1/8 anomaly shows spatially modulated peaks near zero bias associated with the anti-phase ordering of the d -wave order parameter predicted at this doping level. ZBCPs were also found in micrometre-size edge junctions of YBCO/SrRuO 3 /YBCO, where SrRuO 3 is ferromagnetic. Here, the results are consistent with a crossed Andreev reflection effect (CARE) at the narrow domain walls of the SrRuO 3 ZBCPs measured in STS studies of manganite/cuprate bilayers could not be attributed to CARE because the manganite's domain wall is much larger than the coherence length in YBCO, and instead are attributed to proximity-induced triplet-pairing superconductivity with non-conventional symmetry. And finally, ZBCPs found in junctions of non-intentionally doped topological insulator films of Bi 2 Se 3 and the s -wave superconductor NbN are attributed to proximity-induced p x  + ip y triplet order parameter in the topological material.This article is part of the theme issue 'Andreev bound states'. �

Ionic classification of Xe laser lines: A new approach through time resolved spectroscopy

International Nuclear Information System (INIS)

Schinca, D.; Duchowicz, R.; Gallardo, M.

1992-01-01

Visible and UV laser emission from a highly ionized pulsed Xe plasma was studied in relation to the ionic assignment of the laser lines. Time-resolved spectroscopy was used to determine the ionic origin of the studied lines. The results are in agreement with an intensity versus pressure analysis performed over the same wavelength range. From the temporal behaviour of the spontaneous emission, a probable classification can be obtained. (author). 7 refs, 7 figs, 1 tab

Scanning tunneling microscopy and spectroscopy studies of the heavy-electron superconductor TlNi2Se2

Science.gov (United States)

Wilfert, Stefan; Schmitt, Martin; Schmidt, Henrik; Mauerer, Tobias; Sessi, Paolo; Wang, Hangdong; Mao, Qianhui; Fang, Minghu; Bode, Matthias

2018-01-01

We report on the structural and superconducting electronic properties of the heavy-electron superconductor TlNi2Se2 . By using a variable-temperature scanning tunneling microscopy (VT-STM) the coexistence of (√{2 }×√{2 }) R 45∘ and (2 ×1 ) surface reconstructions is observed. Similar to earlier observations on the "122" family of Fe-based superconductors, we find that their respective surface fraction strongly depends on the temperature during cleavage, the measurement temperature, and the sample's history. Cleaving at low temperature predominantly results in the (√{2 }×√{2 }) R 45∘ -reconstructed surface. A detailed analysis of the (√{2 }×√{2 }) R 45∘ -reconstructed domains identifies (2 ×1 ) -ordered dimers, tertramers, and higher order even multimers as domain walls. Higher cleaving temperatures and the warming of low-temperature-cleaved samples increases the relative weight of the (2 ×1 ) surface reconstruction. By slowly increasing the sample temperature Ts inside the VT-STM we find that the (√{2 }×√{2 }) R 45∘ surface reconstructions transforms into the (2 ×1 ) structure at Ts=123 K. We identify the polar nature of the TlNi2Se2 (001) surface as the most probable driving mechanism of the two reconstructions, as both lead to a charge density ρ =0.5 e- , thereby avoiding divergent electrostatic potentials and the resulting "polar catastrophe." Low-temperature scanning tunneling spectroscopy (STS) performed with normal metal and superconducting probe tips shows a superconducting gap which is best fit with an isotropic s wave. We could not detect any correlation between the local surface reconstruction, suggesting that the superconductivity is predominantly governed by TlNi2Se2 bulk properties. Correspondingly, temperature- and field-dependent data reveal that both the critical temperature and critical magnetic field are in good agreement with bulk values obtained earlier from transport measurements. In the superconducting state

Real-time trace gas sensor using a multimode diode laser and multiple-line integrated cavity enhanced absorption spectroscopy.

Science.gov (United States)

Karpf, Andreas; Rao, Gottipaty N

2015-07-01

We describe and demonstrate a highly sensitive trace gas sensor based on a simplified design that is capable of measuring sub-ppb concentrations of NO2 in tens of milliseconds. The sensor makes use of a relatively inexpensive Fabry-Perot diode laser to conduct off-axis cavity enhanced spectroscopy. The broad frequency range of a multimode Fabry-Perot diode laser spans a large number of absorption lines, thereby removing the need for a single-frequency tunable laser source. The use of cavity enhanced absorption spectroscopy enhances the sensitivity of the sensor by providing a pathlength on the order of 1 km in a small volume. Off-axis alignment excites a large number of cavity modes simultaneously, thereby reducing the sensor's susceptibility to vibration. Multiple-line integrated absorption spectroscopy (where one integrates the absorption spectra over a large number of rovibronic transitions of the molecular species) further improves the sensitivity of detection. Relatively high laser power (∼400  mW) is used to compensate for the low coupling efficiency of a broad linewidth laser to the optical cavity. The approach was demonstrated using a 407 nm diode laser to detect trace quantities of NO2 in zero air. Sensitivities of 750 ppt, 110 ppt, and 65 ppt were achieved using integration times of 50 ms, 5 s, and 20 s respectively.

A Polarization-Adjustable Picosecond Deep-Ultraviolet Laser for Spin- and Angle-Resolved Photoemission Spectroscopy

International Nuclear Information System (INIS)

Zhang Feng-Feng; Yang Feng; Zhang Shen-Jin; Wang Zhi-Min; Xu Feng-Liang; Peng Qin-Jun; Zhang Jing-Yuan; Xu Zu-Yan; Wang Xiao-Yang; Chen Chuang-Tian

2012-01-01

We report on a polarization-adjustable picosecond deep-ultraviolet (DUV) laser at 177.3 nm. The DUV laser was produced by second harmonic generation from a mode-locked laser at 355 nm in nonlinear optical crystal KBBF. The laser delivered a maximum average output power of 1.1 mW at 177.3 nm. The polarization of the 177.3 nm beam was adjusted with linear and circular polarization by means of λ/4 and λ/2 wave plates. To the best of our knowledge, the laser has been employed as the circularly polarized and linearly polarized DUV light source for a spin- and angle-resolved photoemission spectroscopy with high resolution for the first time. (fundamental areas of phenomenology(including applications))

Identification of inks and structural characterization of contemporary artistic prints by laser-induced breakdown spectroscopy

International Nuclear Information System (INIS)

Oujja, M.; Vila, A.; Rebollar, E.; Garcia, J.F.; Castillejo, M.

2005-01-01

Identification of the inks used in artistic prints and the order in which different ink layers have been applied on a paper substrate are important factors to complement the classical stylistic aspects for the authentication of this type of objects. Laser-induced breakdown spectroscopy (LIBS) is investigated to determine the chemical composition and structural distribution of the constituent materials of model prints made by applying one or two layers of several blue and black inks on an Arches paper substrate. By using suitable laser excitation conditions, identification of the inks was possible by virtue of emissions from key elements present in their composition. Analysis of successive spectra on the same spot allowed the identification of the order in which the inks were applied on the paper. The results show the potential of laser-induced breakdown spectroscopy for the chemical and structural characterization of artistic prints

Broadband Doppler-limited two-photon and stepwise excitation spectroscopy with laser frequency combs

Science.gov (United States)

Hipke, Arthur; Meek, Samuel A.; Ideguchi, Takuro; Hänsch, Theodor W.; Picqué, Nathalie

2014-07-01

Multiplex two-photon excitation spectroscopy is demonstrated at Doppler-limited resolution. We describe first Fourier-transform two-photon spectroscopy of an atomic sample with two mode-locked laser oscillators in a dual-comb technique. Each transition is uniquely identified by the modulation imparted by the interfering comb excitations. The temporal modulation of the spontaneous two-photon fluorescence is monitored with a single photodetector, and the spectrum of all excited transitions is revealed by a Fourier transform.

Iron based pnictide and chalcogenide superconductors studied by muon spin spectroscopy

International Nuclear Information System (INIS)

Shermadini, Zurab

2014-01-01

In the present thesis the superconducting properties of the Iron-based Ba 1-x Rb x Fe 2 As 2 arsenides, and A x Fe 2-y Se 2 (A=Cs,Rb,K) chalcogenides are investigated by means of Muon Spin Rotation Spectroscopy. The temperature and pressure dependence of the magnetic penetration depth is obtained form μSR experiments and analyzed to probe the superconducting gap-symmetries for each samples. The Ba 1-x Rb x Fe 2 As 2 system is described within the multi-gap s+s-wave scenario and results are discussed in the light of the suppression of inter-band processes upon hole doping. Due to the lowered upper critical field B c2 and reduced T c , a large section of B-T-p phase diagram is studied for the hole-overdoped x=1 case. By applying hydrostatic pressure, the RbFe 2 As 2 system exhibits a classical BCS superconducting characteristics. The A x Fe 2-y Se 2 chalcogenide represents a system containing magnetically ordered and superconducting phases simultaneously. In all investigated chalcogenide samples, about 90% of the total volume show the strong antiferromagnetic phase and 10% exhibit a paramagnetic behavior. Magnetization measurements reveal a 100% Meissner effect, while μSR clearly indicates that the paramagnetic phase is a perfect superconductor. Up to now, there is no clear evidence whether the antiferromagnetic phase is also superconducting. The microscopic coexistence and/or phase separation of superconductivity and magnetism is discussed. Moreover, a new hydrostatic double-wall pressure cell is developed and produced, satisfying the demands of μSR experiments. The designs and characteristics of the new pressure cell are reviewed in the present thesis.

Differential laser-induced perturbation spectroscopy and fluorescence imaging for biological and materials sensing

Science.gov (United States)

Burton, Dallas Jonathan

The field of laser-based diagnostics has been a topic of research in various fields, more specifically for applications in environmental studies, military defense technologies, and medicine, among many others. In this dissertation, a novel laser-based optical diagnostic method, differential laser-induced perturbation spectroscopy (DLIPS), has been implemented in a spectroscopy mode and expanded into an imaging mode in combination with fluorescence techniques. The DLIPS method takes advantage of deep ultraviolet (UV) laser perturbation at sub-ablative energy fluences to photochemically cleave bonds and alter fluorescence signal response before and after perturbation. The resulting difference spectrum or differential image adds more information about the target specimen, and can be used in combination with traditional fluorescence techniques for detection of certain materials, characterization of many materials and biological specimen, and diagnosis of various human skin conditions. The differential aspect allows for mitigation of patient or sample variation, and has the potential to develop into a powerful, noninvasive optical sensing tool. The studies in this dissertation encompass efforts to continue the fundamental research on DLIPS including expansion of the method to an imaging mode. Five primary studies have been carried out and presented. These include the use of DLIPS in a spectroscopy mode for analysis of nitrogen-based explosives on various substrates, classification of Caribbean fruit flies versus Caribbean fruit flies that have been irradiated with gamma rays, and diagnosis of human skin cancer lesions. The nitrogen-based explosives and Caribbean fruit flies have been analyzed with the DLIPS scheme using the imaging modality, providing complementary information to the spectroscopic scheme. In each study, a comparison between absolute fluorescence signals and DLIPS responses showed that DLIPS statistically outperformed traditional fluorescence techniques

Laser-induced breakdown spectroscopy for quantification of heavy metals in soils and sediments

CSIR Research Space (South Africa)

Ambushe, AA

2010-09-01

Full Text Available Laser-induced breakdown spectroscopy (LIBS) will be used to determine the contents of heavy metals in soils and sediments. LIBS results will be compared with the results obtained by inductively coupled plasma-optical emission spectrometry (ICP...

Low-energy excitations and Fermi surface topology of parent cobaltate superconductor

International Nuclear Information System (INIS)

Hasan, M.Z.; Qian, D.; Foo, M.; Cava, R.J.

2007-01-01

The essential framework for cuprate superconductivity is that of a spin-1/2 electron system in the vicinity of a half filled (Mott limit) lattice. Of all oxide superconductors, this framework is most closely matched in the sodium doped cobalt oxides except that it is realized on a triangular lattice. We employ angle-resolved photoemission spectroscopy to study the quasiparticle dynamics of the parent cobaltate superconductor. Results reveal a single hole-like Fermi surface generated by the crossing of heavy (∼15 m e ∼ 3m LDA ) quasiparticles with a negative effective hopping (t eff F (k → )∼v F ∼0.4±0.1 eV A) observed. ARPES data is consistent with bulk thermodynamic specific heat and quantum oscillation measurements

Hybrid molecule/superconductor assemblies

International Nuclear Information System (INIS)

McDevitt, J.T.; Haupt, S.G.; Riley, D.R.; Zhao, J.; Zhou, J.P., Jones, C.

1993-01-01

The fabrication of electronic devices from molecular materials has attracted much attention recently. Schottky diodes, molecular transistors, metal-insulator-semiconductor diodes, MIS field effect transistors and light emitting diodes have all been prepared utilizing such substances. The active elements in these devices have been constructed by depositing the molecular phase onto the surface of a metal, semiconductor or insulating substrate. With the recent discovery of high temperature superconductivity, new opportunities now exist for the study of molecule/superconductor interactions as well as for the construction of novel hybrid molecule/superconductor devices. In this paper, methods for preparing the initial two composite molecule/semiconductor devices will be reported. Consequently, light sensors based on dye-coated superconductor junctions as well as molecular switches fashioned from conductive polymer coated superconductor junctions as well as molecular switches fashioned from conductive polymer coated superconductor microbridges will be discussed. Moreover, molecule/superconductor energy and electron transfer phenomena will be illustrated also for the first time

ANALISIS UNSUR Ag PADA SAMPEL CAIR DENGAN LASER INDUCED BREAKDOWN SPECTROSCOPY (LIBS

Directory of Open Access Journals (Sweden)

Sinaga Natalia Declarossy

2014-02-01

Full Text Available It has been done research on the analysis of Ag element in the liquid electrolyte with Laser Induced Breakdown Spectroscopy (LIBS through electrolysis method. Observations conducted by LIBS using Nd-YAG laser (1064nm, 7ns. Prior to analyze, first looking for the optimum conditions of experiments had been done. The results showed that the optimum laser energy to the characterization of the elements Ag was 100 mJ and optimum conditions of electric current and time deposition on electrolysis process were 4.93 mA and 10 minutes, respectively. These conditions, next, for the application of quantitative analysis of Ag solution that started from concentration 300 ppm to the lowest concentration and limit of detection obtained 1 ppm.

Time-resolved X-ray absorption spectroscopy for laser-ablated silicon particles in xenon gas

International Nuclear Information System (INIS)

Makimura, Tetsuya; Sakuramoto, Tamaki; Murakami, Kouichi

1996-01-01

We developed a laboratory-scale in situ apparatus for soft X-ray absorption spectroscopy with a time resolution of 10 ns and a space resolution of 100 μm. Utilizing this spectrometer, we have investigated the dynamics of silicon atoms formed by laser ablation in xenon gas. It was found that 4d-electrons in the xenon atoms are excited through collision with electrons in the laser-generated silicon plasma. (author)

Laser-spectroscopy studies of the nuclear structure of neutron-rich radium

Science.gov (United States)

Lynch, K. M.; Wilkins, S. G.; Billowes, J.; Binnersley, C. L.; Bissell, M. L.; Chrysalidis, K.; Cocolios, T. E.; Goodacre, T. Day; de Groote, R. P.; Farooq-Smith, G. J.; Fedorov, D. V.; Fedosseev, V. N.; Flanagan, K. T.; Franchoo, S.; Garcia Ruiz, R. F.; Gins, W.; Heinke, R.; Koszorús, Á.; Marsh, B. A.; Molkanov, P. L.; Naubereit, P.; Neyens, G.; Ricketts, C. M.; Rothe, S.; Seiffert, C.; Seliverstov, M. D.; Stroke, H. H.; Studer, D.; Vernon, A. R.; Wendt, K. D. A.; Yang, X. F.

2018-02-01

The neutron-rich radium isotopes, Ra-233222, were measured with Collinear Resonance Ionization Spectroscopy (CRIS) at the ISOLDE facility, CERN. The hyperfine structure of the 7 s2S10→7 s 7 p P31 transition was probed, allowing measurement of the magnetic moments, quadrupole moments, and changes in mean-square charge radii. These results are compared to existing literature values, and the new moments and change in mean-square charge radii of 231Ra are presented. Low-resolution laser spectroscopy of the very neutron-rich 233Ra has allowed the isotope shift and relative charge radius to be determined for the first time.

EDITORIAL: The electromagnetic properties of iron-based superconductors The electromagnetic properties of iron-based superconductors

Science.gov (United States)

Prozorov, Ruslan; Gurevich, Alex; Luke, Graeme

2010-05-01

cuprates, a superconducting 'dome' is formed upon doping the parent compounds, which exhibits antiferromagnetic and structural transitions at temperatures well above the superconducting critical temperature. This special section touches on several key aspects of these new iron-based superconductors. These topics include materials synthesis and basic characterization, the role of impurities and pairing symmetry, and mapping of the superconducting phase diagram as a function of chemical doping and pressure. Studies of transport, magnetic and optical properties account for a substantial portion of this special section. Particular attention is devoted to the role of magnetic excitations and the issue of the possible coexistence of magnetism and superconductivity. Attempts to understand the nature of the superconducting pairing are discussed from several angles, including tunneling spectroscopy and the London penetration depth. The vortex state is probed by magnetization, transport and neutron scattering, while the irreversible state is probed by studies of magnetic and transport critical current density.

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...

Direct angle resolved photoemission spectroscopy and ...

Indian Academy of Sciences (India)

Since 1997 we systematically perform direct angle resolved photoemission spectroscopy (ARPES) on in-situ grown thin (< 30 nm) cuprate films. Specifically, we probe low-energy electronic structure and properties of high-c superconductors (HTSC) under different degrees of epitaxial (compressive vs. tensile) strain.

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.

Ultra-short laser pulse ablation using shear-force feedback: Femtosecond laser induced breakdown spectroscopy feasibility study

International Nuclear Information System (INIS)

Samek, Ota; Kurowski, Andre; Kittel, Silke; Kukhlevsky, Sergei; Hergenroeder, Roland

2005-01-01

This work reports on a feasibility study of proximity ablation using femtosecond pulses. Ultra-short pulses were launched to a bare tapered optical fiber and delivered to the sample. The tip-sample distance was controlled by means of shear-force feedback. Consequently, ablation craters with submicrometer dimensions were obtained. Potential analytical applications for Laser Induced Breakdown Spectroscopy (LIBS) technique, such as e.g. inclusions in steel or bio cells, are suggested

Comparing predictive ability of Laser-Induced Breakdown Spectroscopy to Near Infrared Spectroscopy for soil texture and organic carbon determination

DEFF Research Database (Denmark)

Knadel, Maria; Peng, Yi; Gislum, René

Soil organic carbon (SOC) and texture have a practical value for agronomy and the environment. Thus, alternative techniques to supplement or substitute for the expensive conventional analysis of soil are developed. Here the feasibility of laser-induced breakdown spectroscopy (LIBS) to determine SOC...... and texture was tested and compared with near infrared spectroscopy (NIRS) technique and traditional laboratory analysis. Calibration models were developed on 50 topsoil samples. For all properties except silt, higher predictive ability of LIBS than NIRS models was obtained. Successful calibrations indicate...... that LIBS can be used as a fast and reliable method for SOC and texture estimation....

Two classes of superconductors discovered in our material research: Iron-based high temperature superconductor and electride superconductor

International Nuclear Information System (INIS)

Hosono, Hideo

2009-01-01

We discovered two new classes of superconductors in the course of material exploration for electronic-active oxides. One is 12CaO . 7Al 2 O 3 crystal in which electrons accomodate in the crystallographic sub-nanometer-sized cavities. This material exhibiting metal-superconductor transition at 0.2 K is the first electride superconductor. The other is iron oxypnicitides with a layered structure. This superconductor is rather different from high T c cuprates in several respects. The high T c is emerged by doping carriers to the metallic parent phases which undergo crystallographic transition (tetra to ortho) and Pauli para to antiferromagnetic transition at ∼150 K. The T c is robust to impurity doping to the Fe sites or is induced by partial substitution of the Fe 2+ sites with Co 2+ or Ni 2+ . This article gives a brief summary of these discoveries and recent advances.

Spectroscopic views of high-Tc superconductors

International Nuclear Information System (INIS)

Wendin, G.

1989-01-01

In this paper progress in the field of photoelectron spectroscopy, electron energy loss spectroscopy, inverse photoemission, and infrared- and optical reflectivity applied to high-T c superconductors in analyzed in terms of correlation effects, transport properties and Fermi liquid behavior. For the CuO 2 based materials, a picture emerges of localized holes in copper 3d levels and itinerant holes in oxygen 2p-like bands. A Fermi liquid picture and a superconducting gap is indicated by angle-resolved photoemission, infrared absorption, and NMR. A Fermi surface is indicated by positron annihilation. Infrared absorption revels strongly frequency and temperature dependent scattering and polaronic behavior for frequencies below 0.1 eV. Infrared absorption indicates a maximum superconducting gas of 2Δ/K B T c = 8 and suggests that ordinary samples may show a range of gaps 2 B T c B = 5

Laser Induced Breakdown Spectroscopy in archeometry: A review of its application and future perspectives

Science.gov (United States)

Spizzichino, Valeria; Fantoni, Roberta

2014-09-01

Laser Induced Breakdown Spectroscopy (LIBS) in the last decades has been more and more applied to the field of Cultural Heritage with great results obtained either alone or in combination with complementary laser techniques. Its ability to analyze, with a minimal loss, different kinds of materials in laboratory, in situ and even in hostile environments has been highly appreciated. The main aim of this paper is to present a review of LIBS applications in the interdisciplinary field of archeometry. The LIBS technique is shortly described both from a theoretical and practical point of view, discussing the instrumental setup, also in comparison with typical features of laser induced fluorescence (LIF) and Raman spectroscopy apparata. The complementary with multivariate analysis, a method that can help in reducing data set dimensions and in pulling out effective information, is stressed. In particular the role of LIBS in Cultural Heritage material characterization, recognition of fakes and indirect dating is described, reporting general considerations and case studies on metal alloys, mural paintings, decorated ceramics, glasses, stones and gems.

Principles of electron tunneling spectroscopy

CERN Document Server

Wolf, E L

2012-01-01

Electron tunnelling spectroscopy as a research tool has strongly advanced understanding of superconductivity. This book explains the physics and instrumentation behind the advances illustrated in beautiful images of atoms, rings of atoms and exotic states in high temperature superconductors, and summarizes the state of knowledge that has resulted.

Temperature and Electron Density Determination on Laser-Induced Breakdown Spectroscopy (LIBS) Plasmas: A Physical Chemistry Experiment

Science.gov (United States)

Najarian, Maya L.; Chinni, Rosemarie C.

2013-01-01

This laboratory is designed for physical chemistry students to gain experience using laser-induced breakdown spectroscopy (LIBS) in understanding plasma diagnostics. LIBS uses a high-powered laser that is focused on the sample causing a plasma to form. The emission of this plasma is then spectrally resolved and detected. Temperature and electron…

Time-resolved ultraviolet laser-induced breakdown spectroscopy for organic material analysis

Energy Technology Data Exchange (ETDEWEB)

Baudelet, Matthieu; Boueri, Myriam [Laboratoire de Spectrometrie Ionique et Moleculaire, Universite Claude Bernard Lyon 1, UMR CNRS 5579, 43, Bd. du 11 Novembre 1918, F-69622 Villeurbanne Cedex (France); Yu Jin [Laboratoire de Spectrometrie Ionique et Moleculaire, Universite Claude Bernard Lyon 1, UMR CNRS 5579, 43, Bd. du 11 Novembre 1918, F-69622 Villeurbanne Cedex (France)], E-mail: jin.yu@lasim.univ-lyon1.fr; Mao, Samuel S; Piscitelli, Vincent; Xianglei, Mao; Russo, Richard E [Lawrence Berkeley National Laboratory, Berkeley, California 94720 (United States)

2007-12-15

Ultraviolet pulses (266 nm) delivered by a quadrupled Nd:YAG laser were used to analyze organic samples with laser-induced breakdown spectroscopy (LIBS). We present characteristics of the spectra obtained from organic samples with special attentions on the emissions of organic elements, O and N, and molecular bonds CN. The choice of these atomic or molecular species is justified on one hand, by the importance of these species to specify organic or biological materials; and on the other hand by the possible interferences with ambient air when laser ablation takes place in the atmosphere. Time-resolved LIBS was used to determine the time-evolution of line intensity emitted from these species. We demonstrate different kinetic behaviors corresponding to different origins of emitters: native atomic or molecular species directly vaporized from the sample or those generated through dissociation or recombination due to interaction between laser-induced plasma and air molecules. Our results show the ability of time-resolved UV-LIBS for detection and identification of native atomic or molecular species from an organic sample.

Combination of laser correlation and dielectric spectroscopy in albumin investigations

International Nuclear Information System (INIS)

Nepomnyashchaya, E; Cheremiskina, A; Velichko, E; Aksenov, E; Bogomaz, T

2015-01-01

Joint use of laser correlation and dielectric spectroscopies for studies of biomolecular properties of albumin in water solution is considered. The conditions and parameters of the experiments are discussed. Similar behaviours of albumin molecular sizes and maximum frequency of peak of dielectric dissipation factor with increasing acidity were revealed. Using the suggested approach, biomolecular aggregation dynamics and changes in electrophysical properties on transition from one molecular structure to another may be investigated. (paper)

Strong nonequilibrium coherent states in mesoscopic superconductor-semiconductor-superconductor junctions

DEFF Research Database (Denmark)

Kutchinsky, Jonatan; Wildt, Morten; Taboryski, Rafael Jozef

1999-01-01

A biased superconductor-normal metal-superconductor junction is known to be a strong nonequilibrium system, where Andreev scattering at the interfaces creates a quasiparticle distribution function far from equilibrium, a manifestation of this is the well-known subgap structure in the I...

Accuracy Enhancement of Raman Spectroscopy Using Complementary Laser-Induced Breakdown Spectroscopy (LIBS) with Geologically Mixed Samples.

Science.gov (United States)

Choi, Soojin; Kim, Dongyoung; Yang, Junho; Yoh, Jack J

2017-04-01

Quantitative Raman analysis was carried out with geologically mixed samples that have various matrices. In order to compensate the matrix effect in Raman shift, laser-induced breakdown spectroscopy (LIBS) analysis was performed. Raman spectroscopy revealed the geological materials contained in the mixed samples. However, the analysis of a mixture containing different matrices was inaccurate due to the weak signal of the Raman shift, interference, and the strong matrix effect. On the other hand, the LIBS quantitative analysis of atomic carbon and calcium in mixed samples showed high accuracy. In the case of the calcite and gypsum mixture, the coefficient of determination of atomic carbon using LIBS was 0.99, while the signal using Raman was less than 0.9. Therefore, the geological composition of the mixed samples is first obtained using Raman and the LIBS-based quantitative analysis is then applied to the Raman outcome in order to construct highly accurate univariate calibration curves. The study also focuses on a method to overcome matrix effects through the two complementary spectroscopic techniques of Raman spectroscopy and LIBS.

Double-pulse standoff laser-induced breakdown spectroscopy for versatile hazardous materials detection

Energy Technology Data Exchange (ETDEWEB)

Gottfried, Jennifer L. [U.S. Army Research Laboratory, AMSRD-ARL-WM-BD, Aberdeen Proving Ground, MD, 21005-5069 (United States)], E-mail: jennifer.gottfried@arl.army.mil; De Lucia, Frank C.; Munson, Chase A.; Miziolek, Andrzej W. [U.S. Army Research Laboratory, AMSRD-ARL-WM-BD, Aberdeen Proving Ground, MD, 21005-5069 (United States)

2007-12-15

We have developed a double-pulse standoff laser-induced breakdown spectroscopy (ST-LIBS) system capable of detecting a variety of hazardous materials at tens of meters. The use of a double-pulse laser improves the sensitivity and selectivity of ST-LIBS, especially for the detection of energetic materials. In addition to various metallic and plastic materials, the system has been used to detect bulk explosives RDX and Composition-B, explosive residues, biological species such as the anthrax surrogate Bacillus subtilis, and chemical warfare simulants at 20 m. We have also demonstrated the discrimination of explosive residues from various interferents on an aluminum substrate.

Two photon laser spectroscopy of antiprotonic helium atoms at CERN’s AD

CERN Document Server

Hori, M

2014-01-01

The ASACUSA collaboration of CERN has carried out two-photon laser spectroscopy of antiprotonic helium atoms using counter-propagating ultraviolet laser beams. This excited some non-linear transitions of the antiproton at the wavelengths λ = 139.8–197.0 nm, in a way that reduced the thermal Doppler broadening of the observed resonances. The resulting narrow spectral lines allowed the measurement of three transition frequencies with fractional precisions of 2.3–5 parts in 109. By comparing these values with three-body QED calculations, the antiproton-to-electron mass ratio was derived as 1836.1526736(23). We briefly review these results.

Development of superconductor bulk for superconductor bearing

Energy Technology Data Exchange (ETDEWEB)

Kim, Chan Joong; Jun, Byung Hyuk; Park, Soon Dong (and others)

2008-08-15

Current carrying capacity is one of the most important issues in the consideration of superconductor bulk materials for engineering applications. There are numerous applications of Y-Ba-Cu-O (YBCO) bulk superconductors e.g. magnetic levitation train, flywheel energy storage system, levitation transportation, lunar telescope, centrifugal device, magnetic shielding materials, bulk magnets etc. Accordingly, to obtain YBCO materials in the form of large, single crystals without weak-link problem is necessary. A top seeded melt growth (TSMG) process was used to fabricate single crystal YBCO bulk superconductors. The seeded and infiltration growth (IG) technique was also very promising method for the synthesis of large, single-grain YBCO bulk superconductors with good superconducting properties. 5 wt.% Ag doped Y211 green compacts were sintered at 900 .deg. C {approx} 1200 .deg.C and then a single crystal YBCO was fabricated by an infiltration method. A refinement and uniform distribution of the Y211 particles in the Y123 matrix were achieved by sintering the Ag-doped samples. This enhancement of the critical current density was ascribable to a fine dispersion of the Y211 particles, a low porosity and the presence of Ag particles. In addition, we have designed and manufactured large YBCO single domain with levitation force of 10-13 kg/cm{sup 2} using TSMG processing technique.

Dual-Comb Coherent Raman Spectroscopy with Lasers of 1-GHz Pulse Repetition Frequency

OpenAIRE

Mohler, Kathrin J.; Bohn, Bernhard J.; Yan, Ming; Hänsch, Theodor W.; Picqué, Nathalie

2016-01-01

We extend the technique of multiplex coherent Raman spectroscopy with two femtosecond mode-locked lasers to oscillators of a pulse repetition frequency of 1 GHz. We demonstrate spectra of liquids, which span 1100 cm$^{-1}$ of Raman shifts. At a resolution of 6 cm$^{-1}$, their measurement time may be as short as 5 microseconds for a refresh rate of 2 kHz. The waiting period between acquisitions is improved ten-fold compared to previous experiments with two lasers of 100-MHz repetition frequen...

Laser spectroscopy of a halocarbocation in the gas phase: CH2I+.

Science.gov (United States)

Tao, Chong; Mukarakate, Calvin; Reid, Scott A

2006-07-26

We report the first gas-phase observation of the electronic spectrum of a simple halocarbocation, CH2I+. The ion was generated rotationally cold (Trot approximately 20 K) using pulsed discharge methods and was detected via laser spectroscopy. The identity of the spectral carrier was confirmed by modeling the rotational contour observed in the excitation spectra and by comparison of ground state vibrational frequencies determined by single vibronic level emission spectroscopy with Density Functional Theory (DFT) predictions. The transition was assigned as 3A1 gas phase should open new avenues for study of the structure and reactivity of these important ions.

Laser spectroscopy of neutron deficient Sn isotopes

CERN Multimedia

We propose to study the ground state properties of neutron-deficient Sn isotopes towards the doubly-magic nucleus $^{100}$Sn. Nuclear spins, changes in the rms charge radii and electromagnetic moments of $^{101-121}$Sn will be measured by laser spectroscopy using the CRIS experimental beam line. These ground-state properties will help to clarify the evolution of nuclear structure properties approaching the $\\textit{N = Z =}$ 50 shell closures. The Sn isotopic chain is currently the frontier for the application of state-of-the-art ab-initio calculations. Our knowledge of the nuclear structure of the Sn isotopes will set a benchmark for the advances of many-body methods, and will provide an important test for modern descriptions of the nuclear force.

Quasiparticle current in superconductor-semiconductor-superconductor junctions

International Nuclear Information System (INIS)

Tartakovskij, A.V.; Fistul', M.V.

1988-01-01

It is shown that the quasiparticle current in a superconductor-semiconductor-superconductor junction may significantly increase as a result of resonant passage of the quasiparticle along particular trajectories from periodically situated localized centers. A prediction of the theory is that with increasing junction resistance there should be a change from an excessive current to a insufficient current on the current-voltage characteristics (at high voltages). The effect of transparency of the boundaries on resonance tunneling in such junctions is also investigated

Quantum cascade laser absorption spectroscopy with the amplitude-to-time conversion technique for atmospheric-pressure plasmas

International Nuclear Information System (INIS)

Yumii, Takayoshi; Kimura, Noriaki; Hamaguchi, Satoshi

2013-01-01

The NO 2 concentration, i.e., density, in a small plasma of a nitrogen oxide (NOx) treatment reactor has been measured by highly sensitive laser absorption spectroscopy. The absorption spectroscopy uses a single path of a quantum cascade laser beam passing through a plasma whose dimension is about 1 cm. The high sensitivity of spectroscopy is achieved by the amplitude-to-time conversion technique. Although the plasma reactor is designed to convert NO in the input gas to NO 2 , it has been demonstrated by this highly sensitive absorption spectroscopy that NO 2 in a simulated exhaust gas that enters the reactor is decomposed by the plasma first and then NO 2 is formed again, possibly more than it was decomposed, through a series of gas-phase reactions by the time the gas exits the reactor. The observation is consistent with that of an earlier study on NO decomposition by the same type of a plasma reactor [T. Yumii et al., J. Phys. D 46, 135202 (2013)], in which a high concentration of NO 2 was observed at the exit of the reactor.

Laser spectroscopy with a cooler ring at the ESR (GSI) and the TSR (MPI Heidelberg)

International Nuclear Information System (INIS)

Kuehl, T.; Borneis, S.; Greten, G.; Marx, D.; Neumann, R.; Schroeder, S.; Grieser, R.; Hoog, I.; Huber, G.; Klaft, I.; Klein, R.; Merz, P.; Balykin, V.; Bock, M.; Ellert, C.; Forck, P.; Grieser, M.; Grimm, R.; Habs, D.; Miesner, H.J.; Petrich, W.; Wanner, B.; Becker, C.; Schwalm, D.; Wolf, A.

1992-01-01

At the TSR cooler ring at Heidelberg, laser studies were carried out using singly charged lithium and beryllium ions. Laser spectroscopy of relativistic lithium ions (υ = 0.04c) yielded signals with a narrow linewidth, suitable for an experimental test of special relativity. A dramatic reduction of the beam temperature, as defined by the longitudinal velocity spread, was achieved via laser cooling in both cases. At the ion energies available at ESR it will become possible to prepare and store bare ions up to U 92+ . Electron cooling was successfully demonstrated for hydrogen-like Bi 82+ ions, where a laser experiment is scheduled to study the ground-state hyperfine splitting. (orig.)

Novel estimation of the humification degree of soil organic matter by laser-induced breakdown spectroscopy

Energy Technology Data Exchange (ETDEWEB)

Ferreira, Edilene Cristina, E-mail: edilene@iq.unesp.br [Embrapa Instrumentation, Rua XV de Novembro, 1452, CEP 13560-970 São Carlos, SP (Brazil); São Paulo State University—UNESP, Analytical Chemistry Department, P.O. Box 355, 14801-970 Rua Prof. Francisco Degni, 55, CEP 14800-900 Araraquara, SP (Brazil); Ferreira, Ednaldo José, E-mail: ednaldo.ferreira@embrapa.br [Embrapa Instrumentation, Rua XV de Novembro, 1452, CEP 13560-970 São Carlos, SP (Brazil); Villas-Boas, Paulino Ribeiro, E-mail: paulino.villas-boas@embrapa.br [Embrapa Instrumentation, Rua XV de Novembro, 1452, CEP 13560-970 São Carlos, SP (Brazil); Senesi, Giorgio Saverio, E-mail: giorgio.senesi@ba.imip.cnr.it [Institute of Inorganic Methodologies and Plasmas, CNR, Bari 70126 (Italy); Carvalho, Camila Miranda, E-mail: camilamc@gmail.com [Embrapa Instrumentation, Rua XV de Novembro, 1452, CEP 13560-970 São Carlos, SP (Brazil); Physics Institute of São Carlos, University of São Paulo, IFSC-USP, Av. Trabalhador são-carlense, 400 Pq. Arnold Schimid, 13566-590 São Carlos, SP (Brazil); Romano, Renan Arnon, E-mail: renan.romano@gmail.com [Embrapa Instrumentation, Rua XV de Novembro, 1452, CEP 13560-970 São Carlos, SP (Brazil); Physics Institute of São Carlos, University of São Paulo, IFSC-USP, Av. Trabalhador são-carlense, 400 Pq. Arnold Schimid, 13566-590 São Carlos, SP (Brazil); Martin-Neto, Ladislau, E-mail: ladislau.martin@embrapa.br [Embrapa Instrumentation, Rua XV de Novembro, 1452, CEP 13560-970 São Carlos, SP (Brazil); and others

2014-09-01

Soil organic matter (SOM) constitutes an important reservoir of terrestrial carbon and can be considered an alternative for atmospheric carbon storage, contributing to global warming mitigation. Soil management can favor atmospheric carbon incorporation into SOM or its release from SOM to atmosphere. Thus, the evaluation of the humification degree (HD), which is an indication of the recalcitrance of SOM, can provide an estimation of the capacity of carbon sequestration by soils under various managements. The HD of SOM can be estimated by using various analytical techniques including fluorescence spectroscopy. In the present work, the potential of laser-induced breakdown spectroscopy (LIBS) to estimate the HD of SOM was evaluated for the first time. Intensities of emission lines of Al, Mg and Ca from LIBS spectra showing correlation with fluorescence emissions determined by laser-induced fluorescence spectroscopy (LIFS) reference technique were used to obtain a multivaried calibration model based on the k-nearest neighbor (k-NN) method. The values predicted by the proposed model (A-LIBS) showed strong correlation with LIFS results with a Pearson's coefficient of 0.87. The HD of SOM obtained after normalizing A-LIBS by total carbon in the sample showed a strong correlation to that determined by LIFS (0.94), thus suggesting the great potential of LIBS for this novel application. - Highlights: • Humification degree of soil organic matter (HD) • Importance of soil organic matter HD in keeping carbon in soil • Laser induced fluorescence spectroscopy (LIFS) for HD estimation (reference method) • New LIBS application to predict HD.

Cavity-Enhanced Raman Spectroscopy of Natural Gas with Optical Feedback cw-Diode Lasers.

Science.gov (United States)

Hippler, Michael

2015-08-04

We report on improvements made on our previously introduced technique of cavity-enhanced Raman spectroscopy (CERS) with optical feedback cw-diode lasers in the gas phase, including a new mode-matching procedure which keeps the laser in resonance with the optical cavity without inducing long-term frequency shifts of the laser, and using a new CCD camera with improved noise performance. With 10 mW of 636.2 nm diode laser excitation and 30 s integration time, cavity enhancement achieves noise-equivalent detection limits below 1 mbar at 1 bar total pressure, depending on Raman cross sections. Detection limits can be easily improved using higher power diodes. We further demonstrate a relevant analytical application of CERS, the multicomponent analysis of natural gas samples. Several spectroscopic features have been identified and characterized. CERS with low power diode lasers is suitable for online monitoring of natural gas mixtures with sensitivity and spectroscopic selectivity, including monitoring H2, H2S, N2, CO2, and alkanes.

Dual-wavelength DFB quantum cascade lasers: sources for multi-species trace gas spectroscopy

Science.gov (United States)

Kapsalidis, Filippos; Shahmohammadi, Mehran; Süess, Martin J.; Wolf, Johanna M.; Gini, Emilio; Beck, Mattias; Hundt, Morten; Tuzson, Béla; Emmenegger, Lukas; Faist, Jérôme

2018-06-01

We report on the design, fabrication, and performance of dual-wavelength distributed-feedback (DFB) quantum cascade lasers (QCLs) emitting at several wavelengths in the mid-infrared (mid-IR) spectrum. In this work, two new designs are presented: for the first one, called "Neighbour" DFB, two single-mode DFB QCLs are fabricated next to each other, with minimal lateral distance, to allow efficient beam-coupling into multi-pass gas cells. In addition, the minimal distance allows either laser to be used as an integrated heater for the other, allowing to extend the tuning range of its neighbour without any electrical cross-talk. For the second design, the Vernier effect was used to realize a switchable DFB laser, with two target wavelengths which are distant by about 300 cm^{-1}. These devices are promising laser sources for Tunable Diode Laser Absorption Spectroscopy applications targeting simultaneous detection of multiple gasses, with distant spectral features, in compact and mobile setups.

Portable laser synthesizer for high-speed multi-dimensional spectroscopy

Science.gov (United States)

Demos, Stavros G [Livermore, CA; Shverdin, Miroslav Y [Sunnyvale, CA; Shirk, Michael D [Brentwood, CA

2012-05-29

Portable, field-deployable laser synthesizer devices designed for multi-dimensional spectrometry and time-resolved and/or hyperspectral imaging include a coherent light source which simultaneously produces a very broad, energetic, discrete spectrum spanning through or within the ultraviolet, visible, and near infrared wavelengths. The light output is spectrally resolved and each wavelength is delayed with respect to each other. A probe enables light delivery to a target. For multidimensional spectroscopy applications, the probe can collect the resulting emission and deliver this radiation to a time gated spectrometer for temporal and spectral analysis.

Combining Raman and laser induced breakdown spectroscopy by double pulse lasing.

Science.gov (United States)

Lednev, Vasily N; Pershin, Sergey M; Sdvizhenskii, Pavel A; Grishin, Mikhail Ya; Fedorov, Alexander N; Bukin, Vladimir V; Oshurko, Vadim B; Shchegolikhin, Alexander N

2018-01-01

A new approach combining Raman spectrometry and laser induced breakdown spectrometry (LIBS) within a single laser event was suggested. A pulsed solid state Nd:YAG laser running in double pulse mode (two frequency-doubled sequential nanosecond laser pulses with dozens microseconds delay) was used to combine two spectrometry methods within a single instrument (Raman/LIBS spectrometer). First, a low-energy laser pulse (power density far below ablation threshold) was used for Raman measurements while a second powerful laser pulse created the plasma suitable for LIBS analysis. A short time delay between two successive pulses allows measuring LIBS and Raman spectra at different moments but within a single laser flash-lamp pumping. Principal advantages of the developed instrument include high quality Raman/LIBS spectra acquisition (due to optimal gating for Raman/LIBS independently) and absence of target thermal alteration during Raman measurements. A series of high quality Raman and LIBS spectra were acquired for inorganic salts (gypsum, anhydrite) as well as for pharmaceutical samples (acetylsalicylic acid). To the best of our knowledge, the quantitative analysis feasibility by combined Raman/LIBS instrument was demonstrated for the first time by calibration curves construction for acetylsalicylic acid (Raman) and copper (LIBS) in gypsum matrix. Combining ablation pulses and Raman measurements (LIBS/Raman measurements) within a single instrument makes it an efficient tool for identification of samples hidden by non-transparent covering or performing depth profiling analysis including remote sensing. Graphical abstract Combining Raman and laser induced breakdown spectroscopy by double pulse lasing.

Peculiarities of plasma homeostasis in the patients with rectal cancer according to laser correlation spectroscopy findings

International Nuclear Information System (INIS)

Byilenko, O.A.; Bazhora, Yu.Yi.; Sokolov, V.M.; Andronov, D.Yu.

1997-01-01

Laser correlation spectroscopy was used to investigate plasma homeostasis in 82 patients with rectal cancer. The spectra of the blood plasma from 21 donors of the transfusion station were used as the control. The blood plasma homeostasis changes reheated with laser correlation spectrometry in the patients with rectal cancer allow to use them for diagnosis of this pathology

High-resolution three-dimensional compositional imaging by double-pulse laser-induced breakdown spectroscopy

International Nuclear Information System (INIS)

Schiavo, C.; Grifoni, E.; Legnaioli, S.; Lorenzetti, G.; Poggialini, F.; Pagnotta, S.; Palleschi, V.; Menichetti, L.

2016-01-01

In this paper we present a new instrument specifically realized for high-resolution three-dimensional compositional analysis and mapping of materials. The instrument is based on the coupling of a Double-Pulse Laser-Induced Breakdown Spectroscopy (LIBS) instrument with an optical microscope. The compositional mapping of the samples is obtained by scanning the laser beam across the surface of the sample, while the in depth analysis is performed by sending multiple laser pulses on the same point. Depths of analysis of several tens of microns can be obtained. The instrument presented has definite advantages with respect to Laser Ablation-ICP Mass Spectrometry in many applications related to material analysis, biomedicine and environmental diagnostics. An application to the diagnostics of industrial ceramics is presented, demonstrating the feasibility of Double-Pulse LIBS Imaging and its advantages with respect to conventional single-pulse LIBS imaging.

The disordered Bose condensate in two dimensions: application to high-Tc superconductors

International Nuclear Information System (INIS)

Gold, A.

1992-01-01

We calculate the dynamical conductivity for a weakly disordered Bose condensate in two dimensions. The disorder is due to neutral impurities. We compare the asymptotic laws (for small and large frequencies) for neutral impurities with the ones for charged impurities. Universal functions for the dynamical transport properties are derived. The plasmon density of states shows a linear increase with energy for intermediate energies and a peak structure at larger energies. Our theoretical results are compared with experimental results (far-infrared, electron-energy-loss and Raman spectroscopy) found in the high-Tc superconductor YBa 2 Cu 3 O 7-δ . The occurrence of a quasi-gap in a disordered Bose condensate is described and discussed in connection with experiments on high-Tc superconductors. (orig.)

Prospects of real-time single-particle biological aerosol analysis: A comparison between laser-induced breakdown spectroscopy and aerosol time-of-flight mass spectrometry

International Nuclear Information System (INIS)

Beddows, D.C.S.; Telle, H.H.

2005-01-01

In this paper we discuss the prospects of real-time, in situ laser-induced breakdown spectroscopy applied for the identification and classification of bio-aerosols (including species of potential bio-hazard) within common urban aerosol mixtures. In particular, we address the issues associated with the picking out of bio-aerosols against common background aerosol particles, comparing laser-induced breakdown spectroscopy measurements with data from a mobile single-particle aerosol mass spectrometer (ATOFMS). The data from the latter provide statistical data over an extended period of time, highlighting the variation of the background composition. While single-particle bio-aerosols are detectable in principle, potential problems with small (∼ 1 μm size) bio-aerosols have been identified; constituents of the air mass other than background aerosols, e.g. gaseous CO 2 in conjunction with common background aerosols, may prevent unique recognition of the bio-particles. We discuss whether it is likely that laser-induced breakdown spectroscopy on its own can provide reliable, real-time identification of bio-aerosol in an urban environment, and it is suggested that more than one technique should be or would have to be used. A case for using a combination of laser-induced breakdown spectroscopy and Raman (and/or) laser-induced fluorescence spectroscopy is made

Detection of Anomalies in Citrus Leaves Using Laser-Induced Breakdown Spectroscopy (LIBS).

Science.gov (United States)

Sankaran, Sindhuja; Ehsani, Reza; Morgan, Kelly T

2015-08-01

Nutrient assessment and management are important to maintain productivity in citrus orchards. In this study, laser-induced breakdown spectroscopy (LIBS) was applied for rapid and real-time detection of citrus anomalies. Laser-induced breakdown spectroscopy spectra were collected from citrus leaves with anomalies such as diseases (Huanglongbing, citrus canker) and nutrient deficiencies (iron, manganese, magnesium, zinc), and compared with those of healthy leaves. Baseline correction, wavelet multivariate denoising, and normalization techniques were applied to the LIBS spectra before analysis. After spectral pre-processing, features were extracted using principal component analysis and classified using two models, quadratic discriminant analysis and support vector machine (SVM). The SVM resulted in a high average classification accuracy of 97.5%, with high average canker classification accuracy (96.5%). LIBS peak analysis indicated that high intensities at 229.7, 247.9, 280.3, 393.5, 397.0, and 769.8 nm were observed of 11 peaks found in all the samples. Future studies using controlled experiments with variable nutrient applications are required for quantification of foliar nutrients by using LIBS-based sensing.

New techniques of laser spectroscopy on exotic isotopes of gallium and francium

CERN Document Server

Procter, Thomas John

The neutron-deficient gallium isotopes down to ${N}$=32 have had their hyperfine structures and isotope shifts measured via collinear laser spectroscopy using the COLLAPS (COllinear LAser sPectroScopy) beam line. The ground-state spin of $^{63}$Ga has been determined as ${I}$ = 3/2 and its magnetic dipole and electric quadrupole moments were measured to be $\\mu$ = +1.469(5) $_{\\mu N}$ and ${ Q}$s = +0.212(14) b respectively. The nuclear moments of $^{70}$Ga were measured to be ${\\mu}$= +0.571(2) $_{\\mu}$ and ${Q}$s = +0.105(7) b. New isotope shift results were combined with previously measured values of the neutron-rich isotopes and the changes in mean-square charge radii of the entire gallium isotope chain were investigated. Analysis of the trend in the neutron-deficient charge radii demonstrated that there is no evidence of anomalous charge radii behaviour in gallium in the region of ${N}$=32. A sudden increase of the charge radii was observed at the ${N}$=50 shell gap and an inversion of the normal odd-eve...

Laser Spectroscopy Study on the Neutron-Rich and Neutron-Deficient Te Isotopes

CERN Multimedia

2002-01-01

We propose to perform laser spectroscopy measurements on the Te isotopes. This will give access to fundamental properties of the ground and rather long-lived isomeric states such as the change in the mean square charge radius ($\\delta\\langle$r$^2_c\\rangle$) and the nuclear moments. For these medium-mass isotopes, at this moment the optical resolution obtained with RILIS is not high enough to perform isotope shift measurements. Thus we will use the COMPLIS experimental setup which allows Resonant Ionization Spectroscopy (RIS) on laser desorbed atoms. The 5p$^{4}$ $^{3}$P$_{2} \\rightarrow$ 5p$^{3}$ 6s $^{3}$S$_{1}$ and 5p$^{4}$ $^{3}$P$_{2} \\rightarrow$ 5p$^{3}$ 6s $^{5}$S$_{2}$ optical transitions have been used to perform, on the stable Te isotopes, the tests required by the INTC committee. For this purpose stable-ion sources have been built and Te isotopes have been delivered as stable beams by the injector coupled to the COMPLIS setup. ISOLDE offers the opportunity for studying the Te isotope series over a ...

Coupling spin qubits via superconductors

DEFF Research Database (Denmark)

Leijnse, Martin; Flensberg, Karsten

2013-01-01

We show how superconductors can be used to couple, initialize, and read out spatially separated spin qubits. When two single-electron quantum dots are tunnel coupled to the same superconductor, the singlet component of the two-electron state partially leaks into the superconductor via crossed...... Andreev reflection. This induces a gate-controlled singlet-triplet splitting which, with an appropriate superconductor geometry, remains large for dot separations within the superconducting coherence length. Furthermore, we show that when two double-dot singlet-triplet qubits are tunnel coupled...... to a superconductor with finite charging energy, crossed Andreev reflection enables a strong two-qubit coupling over distances much larger than the coherence length....

Temperature dependence of the infrared properties of Hg–Ba–Cu–O high-temperature superconductor

Czech Academy of Sciences Publication Activity Database

Tomašovičová, N.; Knížek, Karel; Veverka, Miroslav

378-380, - (2006), s. 455-456 ISSN 0921-4526 Grant - others:VEGA(SK) 2/4060/04; Science and Technology Assistence Agency(SK) APVT-51-027904 Institutional research plan: CEZ:AV0Z10100521 Keywords : mercury superconductors * infrared spectroscopy Subject RIV: BM - Solid Matter Physics ; Magnetism Impact factor: 0.872, year: 2006

Quantitative analysis of mineral powders by DRIFTS: Determination of SrCO3 in superconductor precursor powders

DEFF Research Database (Denmark)

Bak, J.; Kindl, B.

1997-01-01

An application of diffuse reflectance infrared Fourier transform spectroscopy (DRIFTS) has been demonstrated to be able to determine small concentrations, down to the 100-ppm level, of carbonates in powdery superconductor (SPC) precursor samples, The detection of carbonates in SPC precursor powders...

Dual-comb coherent Raman spectroscopy with lasers of 1-GHz pulse repetition frequency.

Science.gov (United States)

Mohler, Kathrin J; Bohn, Bernhard J; Yan, Ming; Mélen, Gwénaëlle; Hänsch, Theodor W; Picqué, Nathalie

2017-01-15

We extend the technique of multiplex coherent Raman spectroscopy with two femtosecond mode-locked lasers to oscillators of a pulse repetition frequency of 1 GHz. We demonstrate a spectra of liquids, which span 1100  cm-1 of Raman shifts. At a resolution of 6  cm-1, their measurement time may be as short as 5 μs for a refresh rate of 2 kHz. The waiting period between acquisitions is improved 10-fold compared to previous experiments with two lasers of 100-MHz repetition frequencies.

Quantitative measurement of carbon isotopic composition in CO2 gas reservoir by Micro-Laser Raman spectroscopy.

Science.gov (United States)

Li, Jiajia; Li, Rongxi; Zhao, Bangsheng; Guo, Hui; Zhang, Shuan; Cheng, Jinghua; Wu, Xiaoli

2018-04-15

The use of Micro-Laser Raman spectroscopy technology for quantitatively determining gas carbon isotope composition is presented. In this study, 12 CO 2 and 13 CO 2 were mixed with N 2 at various molar fraction ratios to obtain Raman quantification factors (F 12CO2 and F 13CO2 ), which provide a theoretical basis for calculating the δ 13 C value. And the corresponding values were 0.523 (0Raman peak area can be used for the determination of δ 13 C values within the relative errors range of 0.076% to 1.154% in 13 CO 2 / 12 CO 2 binary mixtures when F 12CO2 /F 13CO2 is 0.466972625. In addition, measurement of δ 13 C values by Micro-Laser Raman analysis were carried out on natural CO 2 gas from Shengli Oil-field at room temperature under different pressures. The δ 13 C values obtained by Micro-Laser Raman spectroscopy technology and Isotope Ratio Mass Spectrometry (IRMS) technology are in good agreement with each other, and the relative errors range of δ 13 C values is 1.232%-6.964%. This research provides a fundamental analysis tool for determining gas carbon isotope composition (δ 13 C values) quantitatively by using Micro-Laser Raman spectroscopy. Experiment of results demonstrates that this method has the potential for obtaining δ 13 C values in natural CO 2 gas reservoirs. Copyright © 2018. Published by Elsevier B.V.

First quantitative measurements by IR spectroscopy of dioxins and furans by means of broadly tunable quantum cascade lasers

International Nuclear Information System (INIS)

Siciliani de Cumis, M; D’Amato, F; Viciani, S; Patrizi, B; Foggi, P; Galea, C L

2013-01-01