Lacan - a global simulation code for laser isotope separation

International Nuclear Information System (INIS)

Goldstein, S.; Quaegebeur, J.P.

1990-01-01

Dimensioning a Laser Isotope Separation (LIS) plant means calculating the values of a large number of parameters in order to optimize some objective function. In such algorithms the calculation of the objective function must be repeated thousands of times, therefore each elementary calculation must consume little time. LACAN uses simple models to describe the elementary physical processes: evaporation, vapour expansion, interaction between photons and atoms, ion extraction etc ... These simple models are derived from refined modeling codes or are empirical. As an example the optimization of the separative work of an uranium facility is discussed

A physical model for laser metal vapour interactions and laser supported detonation waves

International Nuclear Information System (INIS)

Liu Chenghai; Pei Wenbing; Yan Jun; Fan Furu

1990-05-01

A physical model for laser metal-vapour interactions has been developed in this paper. The model developed by authors has been used to study numerically the Laser Supported Detonation Waves (LSDWs) in vapour in front of metal targets, and some good results about LSDWs, such as ignition mechanism, threshold, propagation law and so on, have been obtained numerically with the model. In the model developed, a assumption for non-equilibrium between electrons and ions has been taken, and the target vapour has been discribed with two-temperature hydrodynamic equations of electrons and ions in the Euler space. The ionization-equilibrium assumption has been taken, and the Saha equations have been solved. The laser energy is absorbed due to inverse bremsstrahlung. Energy exchange between electrons and ions is by Coulomb scattering, and energy exchange between electrons and neutral particles is by way of electron-neutral elastic scattering. Electron and ion (including neutral particle) thermal conductions are taken respectively. The LSDWs threshold obtained is in agreement with experement reasonably, and a power law between LSDWs threshold and laser pulse duration, I th ∞τ p -1/2 , has been obtained. Some useful results about the LSDWs shield effects have also been obtained. In the developping phase of LSDWs, the optical thickness of front of LSDWs may reach 5 ∼ 10 in order of magnitude. It is shown that the LSDWs are able to play a very strong shield role

Stable isotope characterization of pan-derived and directly sampled atmospheric water vapour

International Nuclear Information System (INIS)

Maric, R.; St. Amour, N.A.; Gibson, J.J.; Edwards, T.W.D.

2002-01-01

Isotopic characterization of atmospheric water vapour, δ A , and its temporal variability are important prerequisites for quantifying water balance of surface reservoirs and partitioning of evaporation and transpiration fluxes using isotope techniques. Here we present results from a detailed comparison of several methods for determining δ A in field situations, (i) by back-calculation from isotopic and micrometeorological monitoring of a steady-state terminal reservoir (standard Class-A evaporation pan) using boundary-layer mass transfer models [1], (ii) through direct (cryogenic) sampling of ambient atmospheric moisture, and (iii) using the precipitation-equilibrium approximation (i.e., δ A =δ P - ε*)

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

International Nuclear Information System (INIS)

Fedosseev, V.N.; )

2005-01-01

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

Charge exchange effect on laser isotope separation of atomic uranium

International Nuclear Information System (INIS)

Niki, Hideaki; Izawa, Yasukazu; Otani, Hiroyasu; Yamanaka, Chiyoe

1982-01-01

Uranium isotope separating experiment was performed using the two-step photoionization technique with dye laser and nitrogen laser by heating uranium metal with electron beam and producing atomic beam using generated vapour. The experimental results are described after explaining the two-step photoionization by laser, experimental apparatus, the selection of exciting wavelength and others. Enrichment factor depends largely on the spectrum purity of dye laser which is the exciting source. A large enrichment factor of 48.3 times was obtained for spectrum width 0.03A. To put the uranium isotope separation with laser into practice, the increase of uranium atomic density is considered to be necessary for improving the yield. Experimental investigation was first carried out on the charge exchange effect that seems most likely to affect the decrease of enrichment factor, and the charge exchange cross-section was determined. The charge exchange cross-section depends on the relative kinetic energy between ions and atoms. The experimental result showed that the cross-section was about 5 x 10 -13 cm 2 at 1 eV and 10 -13 cm 2 at 90 eV. These values are roughly ten times as great as those calculated in Lawrence Livermore Laboratory, and it is expected that they become the greatest factor for giving the upper limit of uranium atomic density in a process of practical application. (Wakatsuki, Y.)

Water vapour source impacts on oxygen isotope variability in tropical precipitation during Heinrich events

Directory of Open Access Journals (Sweden)

S. C. Lewis

2010-06-01

Full Text Available Water isotope records such as speleothems provide extensive evidence of past tropical hydrological changes. During Heinrich events, isotopic changes in monsoon regions have been interpreted as implying a widespread drying through the Northern Hemisphere tropics and an anti-phased precipitation response in the south. Here, we examine the sources of this variability using a water isotope-enabled general circulation model, Goddard Institute for Space Studies ModelE. We incorporate a new suite of vapour source distribution tracers to help constrain the impact of precipitation source region changes on the isotopic composition of precipitation and to identify nonlocal amount effects. We simulate a collapse of the North Atlantic meridional overturning circulation with a large freshwater input to the region as an idealised analogue to iceberg discharge during Heinrich events. An increase in monsoon intensity, defined by vertical wind shear, is modelled over the South American domain, with small decreases simulated over Asia. Simulated isotopic anomalies agree well with proxy climate records, with lighter isotopic values simulated over South America and enriched values across East Asia. For this particular abrupt climate event, we identify which climatic change is most likely linked to water isotope change – changes in local precipitation amount, monsoon intensity, water vapour source distributions or precipitation seasonality. We categorise individual sites according to the climate variability that water isotope changes are most closely associated with, and find that the dominant isotopic controls are not consistent across the tropics – simple local explanations, in particular, fall short of explaining water isotope variability at all sites. Instead, the best interpretations appear to be site specific and often regional in scale.

Mixed garnet laser crystals for water vapour DIAL transmitter

Science.gov (United States)

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

2017-11-01

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

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.

Lasers for the SILVA laser isotope separation process

International Nuclear Information System (INIS)

Lapierre, Y.

1997-01-01

The main principles of the laser isotope separation process for the production of enriched uranium at lower cost, are reviewed and the corresponding optimal laser characteristics are described. The development of the SILVA laser isotope separation process involved researches in the various domains of pump lasers, dye lasers, laser and optics systems and two test facilities for the feasibility studies which are expected for 1997

The stable isotopic composition of water vapour above Corsica during the HyMeX SOP1 campaign: insight into vertical mixing processes from lower-tropospheric survey flights

Science.gov (United States)

Sodemann, Harald; Aemisegger, Franziska; Pfahl, Stephan; Bitter, Mark; Corsmeier, Ulrich; Feuerle, Thomas; Graf, Pascal; Hankers, Rolf; Hsiao, Gregor; Schulz, Helmut; Wieser, Andreas; Wernli, Heini

2017-05-01

Stable isotopes of water vapour are powerful indicators of meteorological processes on a broad range of scales, reflecting evaporation, condensation, and air mass mixing processes. With the recent advent of fast laser-based spectroscopic methods, it has become possible to measure the stable isotopic composition of atmospheric water vapour in situ at a high temporal resolution. Here we present results from such comprehensive airborne spectroscopic isotope measurements in water vapour over the western Mediterranean at a high spatial and temporal resolution. Measurements have been acquired by a customized Picarro L2130-i cavity-ring down spectrometer deployed onboard the Dornier 128 D-IBUF aircraft together with a meteorological flux measurement package during the HyMeX SOP1 (Hydrological cycle in Mediterranean Experiment special observation period 1) field campaign in Corsica, France, during September and October 2012. Taking into account memory effects of the air inlet pipe, the typical time resolution of the measurements was about 15-30 s, resulting in an average horizontal resolution of about 1-2 km. Cross-calibration of the water vapour measurements from all humidity sensors showed good agreement under most flight conditions but the most turbulent ones. In total 21 successful stable isotope flights with 59 flight hours have been performed. Our data provide quasi-climatological autumn average conditions and vertical profiles of the stable isotope parameters δD, δ18O, and d-excess during the study period. A d-excess minimum in the overall average profile is reached in the region of the boundary-layer top, possibly caused by precipitation evaporation. This minimum is bracketed by higher d-excess values near the surface caused by non-equilibrium fractionation, and a maximum above the boundary layer related to the increasing d-excess in very depleted and dry high-altitude air masses. Repeated flights along the same pattern reveal pronounced day-to-day variability

Advances in laser isotope separation

International Nuclear Information System (INIS)

Herman, I.P.; Bernhardt, A.F.

1988-01-01

The physical and chemical concepts required to understand laser isotope separation are presented and discussed. The numerous successful demonstrations of separating isotopes using lasers are reviewed to 1983. Emphasis is placed on the separation of 235-U from 238-U by multi-step selective ioniation of uranium atomic vapor, and on the separation of D and H and of T from D, by pulsed infrared laser multiple-photon dissociation of fluoroform and chloroform, respectively, because they are among the most successful and important examples of laser isotope separation to date. 161 refs.; 7 figs

The evaporation pan technique revisited: Old theory and a new application for time-weighted synoptic tracing of the isotopic composition of atmospheric vapour

International Nuclear Information System (INIS)

Gibson, J.J.; Edwards, T.W.D.

1999-01-01

Reliable and consistent characterization of the stable isotope composition of atmospheric water vapour and its temporal variability are important prerequisites to the wider application of isotope mass balance methods in atmospheric and water balance studies. A new approach is proposed which utilizes standard class-A evaporation pans, which have sufficient volume to buffer short-term transient variations in atmospheric conditions, justifying the assumption of constant kinetic isotopic fractionation effects in concert with precisely measured temperature and relative humidity to derive vapour isotopic composition. The results of the studies suggest that isotopic sampling of existing, conventionally operated class-A evaporation pans could offer a straightforward and cost-effective solution to the problem of documenting the shifting isotopic distribution in atmospheric moisture

Investigation of the vapour-plasma plume in the welding of titanium by high-power ytterbium fibre laser radiation

Energy Technology Data Exchange (ETDEWEB)

Bykovskiy, D P; Petrovskii, V N; Uspenskiy, S A [National Research Nuclear University ' MEPhI' (Russian Federation)

2015-03-31

The vapour-plasma plume produced in the welding of 6-mm thick VT-23 titanium alloy plates by ytterbium fibre laser radiation of up to 10 kW power is studied in the protective Ar gas medium. High-speed video filming of the vapour-plasma plume is used to visualise the processes occurring during laser welding. The coefficient of inverse bremsstrahlung by the welding plasma plume is calculated from the data of the spectrometric study. (interaction of laser radiation with matter)

Hydrogen and carbon vapour pressure isotope effects in liquid fluoroform studied by density functional theory

Energy Technology Data Exchange (ETDEWEB)

Oi, Takao; Mitome, Ryota; Yanase, Satoshi [Sophia Univ., Tokyo (Japan). Faculty of Science and Technology

2017-06-01

H/D and {sup 12}C/{sup 13}C vapour pressure isotope effects (VPIEs) in liquid fluoroform (CHF{sub 3}) were studied at the MPW1PW91/6-31 ++ G(d) level of theory. The CHF{sub 3} monomer and CHF{sub 3} molecules surrounded by other CHF{sub 3} molecules in every direction in CHF{sub 3} clusters were used as model molecules of vapour and liquid CHF{sub 3}. Although experimental results in which the vapour pressure of liquid {sup 12}CHF{sub 3} is higher than that of liquid {sup 12}CDF{sub 3} and the vapour pressure of liquid {sup 13}CHF{sub 3} is higher than that of liquid {sup 12}CHF{sub 3} between 125 and 212 K were qualitatively reproduced, the present calculations overestimated the H/D VPIE and underestimated the {sup 12}C/{sup 13}C VPIE. Temperature-dependent intermolecular interactions between hydrogen and fluorine atoms of neighbouring molecules were required to explain the temperature dependences of both H/D and {sup 12}C/{sup 13}C VPIEs.

Partitioning understory evapotranspiration in semi-arid ecosystems in Namibia using the isotopic composition of water vapour

Science.gov (United States)

de Blécourt, Marleen; Gaj, Marcel; Holtorf, Kim-Kirsten; Gröngröft, Alexander; Brokate, Ralph; Himmelsbach, Thomas; Eschenbach, Annette

2016-04-01

In dry environments with a sparse vegetation cover, understory evapotranspiration is a major component of the ecosystem water balance. Consequently, knowledge on the size of evapotranspiration fluxes and the driving factors is important for our understanding of the hydrological cycle. Understory evapotranspiration is made up of soil evaporation and plant transpiration. Soil evaporation can be measured directly from patches free of vegetation. However, when understory vegetation is present distinguishing between soil evaporation and plant transpiration is challenging. In this study, we aim to partition understory evapotranspiration based on an approach that combines the measurements of water-vapour fluxes using the closed chamber method with measurements of the isotopic composition of water vapour. The measurements were done in the framework of SASSCAL (Southern African Science Service Centre for Climate Change and Adaptive Land Management). The study sites were located in three different semi-arid ecosystems in Namibia: thornbush savanna, Baikiaea woodland and shrubland. At each site measurements were done under tree canopies as well as at unshaded areas between the canopies. We measured evaporation from the bare soil and evapotranspiration from patches covered with herbaceous species and shrubs using a transparent chamber connected with an infrared gas analyser (LI-8100A, LICOR Inc.). The stable isotope composition of water vapour inside the chamber and depth profiles of soil water stable isotopes were determined in-situ using a tuneable off-axis integrated cavity output spectroscope (OA-ICOS, Los Gatos Research, DLT 100). Xylem samples were extracted using the cryogenic vacuum extraction method and the isotopic composition of the extracted water was measured subsequently with a cavity-ring-down spectrometer (CRDS L2120-i, Picarro Inc.). We will present the quantified fluxes of understory evapotranspiration measured in the three different ecosystems, show the

Investigation of the summation of copper-vapour laser frequencies

International Nuclear Information System (INIS)

Karpukhin, Vyacheslav T; Konev, Yu B; Malikov, Mikhail M

1998-01-01

An investigation was made of the conversion of the copper-vapour laser radiation ( λ 1 = 0.51 μm and λ 2 = 0.578 μm) into UV radiation at the sum frequency (λ 3 = 0.271 μm) in a DKDP crystal. The operation of this frequency converter was compared for two magnifications of the laser cavity: M = 5 and 200. The best results were obtained for M = 200 (average UV radiation power 0.75 W, conversion efficiency 12%). A study was made of the characteristics of the formation of radiation pulses representing the two lines in the laser beam as a whole and in its weakly diverging core. In a low-divergence beam the yellow- and green-line pulses were emitted practically simultaneously with approximately the same peak power, which facilitated the sum-frequency generation. (nonlinear optical phenomena)

Laser isotope separation studies in JAERI

International Nuclear Information System (INIS)

Arisawa, Takashi; Shiba, Koreyuki

1986-01-01

For uranium enrichment, Japan Atomic Energy Research Institute (JAERI) has been studying atomic vapor laser isotope separation since 1976, in addition to such separation methods as gas diffusion, chemical exchange and gas-dynamic techniques. Studies carried out to date in JAERI is briefly summarized in the first part of the report. Then, some major separation techniques which have been studied in JAERI are outlined, and typical results obtained are presented. A large part is devoted to the multiple-photon photoionization technique, which is commonly known as the atomic laser isotope separation method for uranium enrichment. It has such advantages as 1) very high spectral selectivity for the relevant isotope and 2) highly improved photoionizing effect by means of two- and three-step resonance photoionization processes. Here, the atomic laser isotope separation method is discussed in detail with respect to the evaporation process, energy levels, photoionization, selectivity, photoionization schemes, ion recovery, separation in macroscopic amounts, and separation of trace amounts of isotopes. Typical observed and claculated results related to these subjects are shown. In addition, the report briefly describes some other separation processes including laser induced chemical reaction, multiple photo-dissociation, multiple-photo excitation and UV dissociation, laser induced thermal diffusion, and laser centrifugation. (Nogami, K.)

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

International Nuclear Information System (INIS)

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

1995-01-01

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

Physical aspects of laser applications to modern nuclear technologies

International Nuclear Information System (INIS)

Semerok, A.

2001-11-01

This report has been presented by the author to obtain his HDR (accreditation to supervise research). After a brief presentation of his domain of skills, of his education, of his professional experience, and his awards, the author gives an overview of his work performed in the field of laser applications to modern nuclear technologies. Notably, he reports experimental studies dealing with the following topics: radiation source for uranium isotope separation by MLIS method, laser isotope separation in atom vapour, laser plasma diagnostics in strong magnetic field, laser ablation-time of flight mass spectrometry for low uranium isotope ratio measurements, laser ablation-optical emission spectroscopy for surface analysis. The report is completed by many published scientific articles

Low energy methods of molecular laser isotope separation

International Nuclear Information System (INIS)

Makarov, G N

2015-01-01

Of the many proposals to date for laser-assisted isotope separation methods, isotope-selective infrared (IR) multiphoton dissociation (MPD) of molecules has been the most fully developed. This concept served as the basis for the development and operation of the carbon isotope separation facility in Kaliningrad, Russia. The extension of this method to heavy elements, including uranium, is hindered by, among other factors, the high power consumption and the lack of high-efficiency high-power laser systems. In this connection, research and development covering low energy methods for the laser separation of isotopes (including those of heavy atoms) is currently in high demand. This paper reviews approaches to the realization of IR-laser-induced isotope-selective processes, some of which are potentially the basis on which low-energy methods for molecular laser isotope separation can be developed. The basic physics and chemistry, application potential, and strengths and weaknesses of these approaches are discussed. Potentially promising alternatives to the title methods are examined. (reviews of topical problems)

Laser isotope and isomer separations: History and trends

International Nuclear Information System (INIS)

Letok'ov, V.S.

1990-01-01

Paper will review history and principles of laser isotope and nuclear isomer separation: laser multistep photoionization of isotopic and isomeric atoms, laser IR-UV two-step photodissociation of molecules, laser IR multiphoton photodissociation of polyatomic molecules. The comparison and areas of applications of these methods will be considered. Paper will discuss a present state of art of technology of these methods in practical scale in various countries. In conclusion the trends of research in this field including applications of laser-separated isotopes and isomers will be considered

Isotope separation using tunable lasers

International Nuclear Information System (INIS)

Snavely, B.B.

1975-01-01

Various processes for laser isotope separation based upon the use of the spectroscopic isotope effect in atomic and molecular vapors are discussed. Emphasis is placed upon processes which are suitable for uranium enrichment. A demonstration process for the separation of uranium isotopes using selective photoionization is described. (U.S.)

Copper bromide vapour laser with an output pulse duration of up to 320 ns

International Nuclear Information System (INIS)

Gubarev, F A; Fedorov, K V; Evtushenko, G S; Fedorov, V F; Shiyanov, D V

2016-01-01

We report the development of a copper bromide vapour laser with an output pulse duration of up to 320 ns. To lengthen the pulse, the discharge current was limited using a compound switch comprising a pulsed hydrogen thyratron and a tacitron. This technique permits limiting the excitation of the working levels at the initial stage of the discharge development to lengthen the inversion lifetime. The longest duration of a laser pulse was reached in tubes 25 and 50 mm in diameter for a pulse repetition rate of 2 – 4 kHz. (lasers and laser beams)

Multi-wavelength copper vapour lasers for novel materials processing application

International Nuclear Information System (INIS)

Knowles, M.; Foster-Turner, R.; Kearsley, A.; Evans, J.

1995-01-01

The copper vapour laser (CVL) is a high average power, short pulse laser with a multi-kilohertz pulse repetition rate. The CVL laser lines (511 nm and 578 nm) combined with the good beam quality and high peak power available from these lasers allow it to operate in a unique parameter space. Consequently, it has demonstrated many unique and advantageous machining characteristics. We have also demonstrated efficient conversion of CVL radiation to other wavelengths using non-linear frequency conversion, dye lasers and Ti:AL 2 O 3 . Output powers of up to 4 W at 255 nm have been achieved by frequency doubling. The frequency doubled CVL is inherently narrow linewidth and frequency locked making it a suitable source for UV photolithography. Slope efficiencies in excess of 25 % have been achieved with CVL pumped Ti:Al 2 O 3 and dye lasers. These laser extend the wavelengths options into the red and infrared regions of the spectrum. The near diffraction limited beams from these tunable lasers can be efficiently frequency doubled into the blue and near UV. The wide range of wavelength options from the CVL enable a wide variety of materials processing and material interactions to be explored. A European consortium for Copper Laser Applications in Manufacture and Production (CLAMP) has been set up under the EUREKA scheme to coordinate the commercial and technical expertise currently available in Europe. (author)

Atomic lithium vapor laser isotope separation

International Nuclear Information System (INIS)

Olivares, I.E.; Rojas, C.

2002-01-01

An atomic vapor laser isotope separation in lithium was performed using tunable diode lasers. The method permits also the separation of the isotopes between the 6 LiD 2 and the 7 LiD 1 lines using a self-made mass separator which includes a magnetic sector and an ion beam designed for lithium. (Author)

Water Vapour Propulsion Powered by a High-Power Laser-Diode

Science.gov (United States)

Minami, Y.; Uchida, S.

Most of the laser propulsion schemes now being proposed and developed assume neither power supplies nor on-board laser devices and therefore are bound to remote laser stations like a kite via a laser beam “string”. This is a fatal disadvantage for a space vehicle that flies freely though it is often said that no need of installing an energy source is an advantage of a laser propulsion scheme. The possibility of an independent laser propulsion space vehicle that carries a laser source and a power supply on board is discussed. This is mainly due to the latest development of high power laser diode (LD) technology. Both high specific impulse-low thrust mode and high thrust-low specific impulse mode can be selected by controlling the laser output by using vapour or water as a propellant. This mode change can be performed by switching between a high power continuous wave (cw), LD engine for high thrust with a low specific impulse mode and high power LD pumping Q-switched Nd:YAG laser engine for low thrust with the high specific impulse mode. This paper describes an Orbital Transfer Vehicle equipped with the above-mentioned laser engine system and fuel cell that flies to the Moon from a space platform or space hotel in Earth orbit, with cargo shipment from lunar orbit to the surface of the Moon, including the possibility of a sightseeing trip.

Atomic lithium vapor laser isotope separation

CERN Document Server

Olivares, I E

2002-01-01

An atomic vapor laser isotope separation in lithium was performed using tunable diode lasers. The method permits also the separation of the isotopes between the sup 6 LiD sub 2 and the sup 7 LiD sub 1 lines using a self-made mass separator which includes a magnetic sector and an ion beam designed for lithium. (Author)

ArF Laser -Induced Chemical Vapour Deposition of Polythiene Films from Carbon Disulfide

Czech Academy of Sciences Publication Activity Database

Tomovska, R.; Bastl, Zdeněk; Vorlíček, Vladimír; Vacek, Karel; Šubrt, Jan; Plzák, Zbyněk; Pola, Josef

2003-01-01

Roč. 107, č. 36 (2003), s. 9793-9801 ISSN 1089-5647 R&D Projects: GA MŠk ME 612 Institutional research plan: CEZ:AV0Z4032918; CEZ:AV0Z4040901 Keywords : laser photolysis * ArF * chemical vapour deposition Subject RIV: CF - Physical ; Theoretical Chemistry Impact factor: 3.679, year: 2003

Laser assisted aerodynamic isotope separation

International Nuclear Information System (INIS)

Berg, H. van den

1985-01-01

It is shown that the efficiency of conventional aerodynamic isotope seperation can be improved by two orders of magnitude with the aid of a relatively weak cw infrared laser which is used to induce isotopically selective condensation. Overall isotope enrichment factors in excess of 2 are obtained as compared to about 1.02 in the conventional seperation. Sulphur isotopes in SF 6 as well as Silicon isotopes in SiF 4 and Bromine isotopes in CF 3 Br are seperated on a laboratory scale. Infrared vibrational predissociation by itself and in combination with isotopically selective condensation are also shown to be effective new ways of isotope separation. (orig.) [de

A copper bromide vapour laser with a high pulse repetition rate

International Nuclear Information System (INIS)

Shiyanov, D V; Evtushenko, Gennadii S; Sukhanov, V B; Fedorov, V F

2002-01-01

The results of an experimental study of a copper bromide vapour laser with a discharge-channel diameter above 2.5 cm and a high pump-pulse repetition rate are presented. A TGU1-1000/25 high-power tacitron used as a switch made it possible to obtain for the first time a fairly high output radiation power for pump-pulse repetition rates exceeding 200 kHz. At a maximum pump-pulse repetition rate of 250 kHz achieved in a laser tube 2.6 cm in diameter and 76 cm long, the output power was 1.5 W. The output powers of 3 and 10.5 W were reached for pump-pulse repetition rates of 200 and 100 kHz, respectively. These characteristics were obtained without circulating a buffer gas and (or) low-concentration active impurities through the active volume. (active media. lasers)

Developing a western Siberia reference site for tropospheric water vapour isotopologue observations obtained by different techniques (in situ and remote sensing

Directory of Open Access Journals (Sweden)

K. Gribanov

2014-06-01

water cycle, affected by changes in air mass origin, non-convective and convective processes and continental recycling. Novel remote sensing and in situ measuring techniques have recently offered opportunities for monitoring atmospheric water vapour isotopic composition. Recently developed infrared laser spectrometers allow for continuous in situ measurements of surface water vapour δDv and δ18Ov. So far, very few intercomparisons of measurements conducted using different techniques have been achieved at a given location, due to difficulties intrinsic to the comparison of integrated with local measurements. Nudged simulations conducted with high-resolution isotopically enabled general circulation models (GCMs provide a consistent framework for comparison with the different types of observations. Here, we compare simulations conducted with the ECHAM5-wiso model with two types of water vapour isotopic data obtained during summer 2012 at the forest site of Kourovka, western Siberia: hourly ground-based FTIR total atmospheric columnar δDv amounts, and in situ hourly Picarro δDv measurements. There is an excellent correlation between observed and predicted δDv at surface while the comparison between water column values derived from the model compares well with FTIR estimates.

Laser Isotope Enrichment for Medical and Industrial Applications

Energy Technology Data Exchange (ETDEWEB)

Leonard Bond

2006-07-01

Laser Isotope Enrichment for Medical and Industrial Applications by Jeff Eerkens (University of Missouri), Jay Kunze (Idaho State University), and Leonard Bond (Idaho National Laboratory) The principal isotope enrichment business in the world is the enrichment of uranium for commercial power reactor fuels. However, there are a number of other needs for separated isotopes. Some examples are: 1) Pure isotopic targets for irradiation to produce medical radioisotopes. 2) Pure isotopes for semiconductors. 3) Low neutron capture isotopes for various uses in nuclear reactors. 4) Isotopes for industrial tracer/identification applications. Examples of interest to medicine are targets to produce radio-isotopes such as S-33, Mo-98, Mo-100, W-186, Sn-112; while for MRI diagnostics, the non-radioactive Xe-129 isotope is wanted. For super-semiconductor applications some desired industrial isotopes are Si-28, Ga-69, Ge-74, Se-80, Te-128, etc. An example of a low cross section isotope for use in reactors is Zn-68 as a corrosion inhibitor material in nuclear reactor primary systems. Neutron activation of Ar isotopes is of interest in industrial tracer and diagnostic applications (e.g. oil-logging). . In the past few years there has been a sufficient supply of isotopes in common demand, because of huge Russian stockpiles produced with old electromagnetic and centrifuge separators previously used for uranium enrichment. Production of specialized isotopes in the USA has been largely accomplished using old ”calutrons” (electromagnetic separators) at Oak Ridge National Laboratory. These methods of separating isotopes are rather energy inefficient. Use of lasers for isotope separation has been considered for many decades. None of the proposed methods have attained sufficient proof of principal status to be economically attractive to pursue commercially. Some of the authors have succeeded in separating sulfur isotopes using a rather new and different method, known as condensation

Laser Isotope Enrichment for Medical and Industrial Applications

International Nuclear Information System (INIS)

Leonard Bond

2006-01-01

Laser Isotope Enrichment for Medical and Industrial Applications by Jeff Eerkens (University of Missouri), Jay Kunze (Idaho State University), and Leonard Bond (Idaho National Laboratory) The principal isotope enrichment business in the world is the enrichment of uranium for commercial power reactor fuels. However, there are a number of other needs for separated isotopes. Some examples are: (1) Pure isotopic targets for irradiation to produce medical radioisotopes. (2) Pure isotopes for semiconductors. (3) Low neutron capture isotopes for various uses in nuclear reactors. (4) Isotopes for industrial tracer/identification applications. Examples of interest to medicine are targets to produce radio-isotopes such as S-33, Mo-98, Mo-100, W-186, Sn-112; while for MRI diagnostics, the non-radioactive Xe-129 isotope is wanted. For super-semiconductor applications some desired industrial isotopes are Si-28, Ga-69, Ge-74, Se-80, Te-128, etc. An example of a low cross section isotope for use in reactors is Zn-68 as a corrosion inhibitor material in nuclear reactor primary systems. Neutron activation of Ar isotopes is of interest in industrial tracer and diagnostic applications (e.g. oil-logging). . In the past few years there has been a sufficient supply of isotopes in common demand, because of huge Russian stockpiles produced with old electromagnetic and centrifuge separators previously used for uranium enrichment. Production of specialized isotopes in the USA has been largely accomplished using old ''calutrons'' (electromagnetic separators) at Oak Ridge National Laboratory. These methods of separating isotopes are rather energy inefficient. Use of lasers for isotope separation has been considered for many decades. None of the proposed methods have attained sufficient proof of principal status to be economically attractive to pursue commercially. Some of the authors have succeeded in separating sulfur isotopes using a rather new and different method, known as condensation

Laser isotope separation - a new class of chemical process

International Nuclear Information System (INIS)

Woodall, K.B.; Mannik, L.; O'Neill, J.A.; Mader, D.L.; Nickerson, S.B.; Robins, J.R.; Bartoszek, F.E.; Gratton, D.

1983-01-01

Lasers may soon find several applications in chemical processing. The applications that have attracted the most research funding to date involve isotope separation for the nuclear industry. These isotopes have an unusually high value (≥$1000/kg) compared to bulk chemicals (∼$1/kg) and are generally required in very large quantities. In a laser isotope separation process, light is used to convert a separation that is very difficult or even impossible by conventional chemical engineering techniques to one that is readily handled by conventional separation technology. For some isotopes this can result in substantial capital and energy savings. A uranium enrichment process developed at the Lawrence Livermore National Laboratory is the closest to commercialization of the large scale laser isotope separation processes. Of particular interest to the Canadian nuclear industry are the laser separation of deuterium, tritium, zirconium-90 and carbon-14. In this paper, the basic principles behind laser isotope separation are reviewed and brief dscriptions of the more developed processes are given

Matrix effects in laser ablation molecular isotopic spectrometry

Energy Technology Data Exchange (ETDEWEB)

Brown, Staci, E-mail: staci.brown@cepast.famu.edu [Department of Physics, Florida A and M University, 2077 E. Paul Dirac Drive, Tallahassee, FL 32310 (United States); Ford, Alan, E-mail: alan.ford@alakaidefense.com [Alakai Defense Systems, 197 Replacement Ave, Suite 102, Fort Leonard Wood, MO 65473 (United States); Akpovo, Charlemagne C., E-mail: charlemagne.akpovo@cepast.famu.edu [Department of Physics, Florida A and M University, 2077 E. Paul Dirac Drive, Tallahassee, FL 32310 (United States); Martinez, Jorge, E-mail: jmartinez@cepast.famu.edu [Department of Physics, Florida A and M University, 2077 E. Paul Dirac Drive, Tallahassee, FL 32310 (United States); Johnson, Lewis, E-mail: lewis@cepast.famu.edu [Department of Physics, Florida A and M University, 2077 E. Paul Dirac Drive, Tallahassee, FL 32310 (United States)

2014-11-01

Recently, it has been shown that laser-induced breakdown spectroscopy (LIBS) can be used for the detection of isotopes of elements via isotopic shifts in diatomic species in a technique known as laser ablation molecular isotopic spectrometry (LAMIS). While LAMIS works quite well for isotopic analysis of pure compounds under optimal conditions, it is desirable for it to be applicable for a variety of compounds and matrices. However, the LIBS plasma emission associated with LAMIS depends on several parameters, including the applied electric field of the laser pulse, the physical properties of the material being investigated, and the presence of additional elements other than the element of interest. In this paper, we address some of the pitfalls arising from these dependencies when using LAMIS for the determination of the relative isotopic abundance of boron-containing materials with varying chemical matrices. - Highlights: • LAMIS usually determines isotopic composition of boron compounds within 3 percent. • LaBO{sub 3} and some boron-containing mixtures yield inaccurate LAMIS results. • Higher laser energy reduces variability but does not remedy poor LAMIS outcomes.

Laser pumped lasers for isotope separation

International Nuclear Information System (INIS)

Fry, S.M.

1976-01-01

A study of the isotope separation laser requirements reveals that high pressure polyatomic molecular gas laser pumped lasers can attain the necessary characteristics including tunability, energy output, pulse width, and repetition rate. The results of a search, made for molecules meeting the appropriate requirements for one of several pump schemes utilizing a CO 2 laser and with output in the 12 μm or 16μm wavelength range, are presented. Several methods of pumping are reviewed and two novel pump schemes are presented. A laser pumped laser device design is given, and operation of this device and associated diagnostic equipment is confirmed by repeating experiments in OCS and NH 3 . The results of OCS laser experiments show that an improvement in pump rate and output per unit length is obtained with the device, using a wedged transverse pumping scheme. A new multi-line laser system in NH 3 pumped by a TEA CO 2 laser is reported. More than forty transitions spanning the wavelength range of 9.2 to 13.8 μm are observed and identified. A strong output at 12.08 μm is one of the closest lines yet found to the required laser isotope separation wavelength. Far infrared emission near 65 μm is observed and is responsible for populating levels which lase in pure ammonia near 12.3 μm. Buffer gas (e.g., N 2 or He) pressures of approximately 40--800 torr cause energy transfer by collision-induced rotationaltransitions from the pumped antisymmetric to the lasing symmetric levels in the nu 2 = 1 band of ammonia. Most of the observed lines are aP(J,K) transitions which originate from the nu 2 /sup s/ band. Measurements of the pressure dependence of the laser output shows that some lines lase at pressures greater than one atmosphere. Transient behavior of the 12.08 μm line is calculated from a simplified analytic model and these calculations are compared to the experimental results

Molecular laser isotope separation programme at BARC

International Nuclear Information System (INIS)

Sarkar, Sisir K.; Parthasarathy, Venkatachari

2007-09-01

Little over thirty years ago, BARC ventured into a new frontier of scientific research: Molecular Laser Isotope Separation (MLIS) programme based on the interaction of lasers with molecules. The initial project was a scheme to produce enriched uranium. The idea was to use the intense, monochromatic light of lasers to break the chemical bonds of only those molecules containing the fissionable isotope uranium-235. At present the programme is evolving around separation of low and middle mass isotopes, namely sulphur 34/33/32, oxygen 17/18, carbon 13/12, hydrogen T/D/H to be followed by an advanced engineering programme designed to lead to a demonstration plant. The latest results have come very close to the design parameters specified for a full-scale separation of carbon isotopes. All these expertise provide an infra structure for future front line R and D activities in the general area of Laser Photochemical Technology which would include i) LIS of other useful elements ii) Material processing and iii) Fuel reprocessing/ waste management (author)

Lasers for isotope separation processes and their properties

International Nuclear Information System (INIS)

George, E.V.; Krupke, W.F.

1976-08-01

The laser system requirements for isotope enrichment are presented in the context of an atomic uranium vapor process. Coherently pumped dye lasers using as the pump laser either the frequency doubled Nd:YAG or copper vapor are seen to be quite promising for meeting the near term requirements of a laser isotope separation (LIS) process. The utility of electrical discharge excitation of the rare gas halogens in an LIS context is discussed

Laser-induced photochemical enrichment of boron isotopes

International Nuclear Information System (INIS)

Freund, S.M.; Ritter, J.J.

1976-01-01

A boron trichloride starting material containing both boron-10 isotopes and boron-11 isotopes is selectively enriched in one or the other of these isotopes by a laser-induced photochemical method involving the reaction of laser-excited boron trichloride with either H 2 S or D 2 S. The method is carried out by subjecting a low pressure gaseous mixture of boron trichloride starting material and the sulfide to infrared radiation from a carbon dioxide TE laser. The wave length of the radiation is selected so as to selectively excite one or the other of boron-10 BCl 3 molecules or boron-11 BCl 3 molecules, thereby making them preferentially more reactive with the sulfide. The laser-induced reaction produces both a boron-containing solid phase reaction product and a gaseous phase containing mostly unreacted BCl 3 and small amounts of sulfhydroboranes. Pure boron trichloride selectively enriched in one of the isotopes is recovered as the primary product of the method from the gaseous phase by a multi-step recovery procedure. Pure boron trichloride enriched in the other isotope is recovered as a secondary product of the method by the subsequent chlorination of the solid phase reaction product followed by separation of BCl 3 from the mixture of gaseous products resulting from the chlorination

Laser separation of isotopes of hydrogen

International Nuclear Information System (INIS)

Dave, S.M.; Ghosh, S.K.; Sadhukhan, H.K.

1980-01-01

Laser isotope separation technique is explained and various methods based on the technique are discussed in detail. Requirements of any laser isotope separation method to be acceptable for the production of heavy water are mentioned and economic viability of this process for heavy water production is examined. Investigations carried out to use this technique for deuterium separation using methanol, formaldehyde, propynal, 2,2,-dichloro-1-1-1,-trifluoroethane (Freon 123), polyvinyl chloride and fluoroform-d are reviewed. (M.G.B.)

Present and prospective situation in laser isotope separation: will the free electron laser be needed

International Nuclear Information System (INIS)

Rigny, P.

1984-09-01

The need for enriched isotopes, as it appears to day will be recalled for the foreseeable future, this need, in quantitative terms, will be confined to isotopes for nuclear energy. The interest of laser isotope separation will finally depend on our ability to fulfil a number of requirements as to the laser output light characteristics. These will be recalled for the most common laser processes (molecular photodissociation and atomic photoionisation). At this point a comparison with expectations from the FEL can already be attempted. Less common laser isotope separation schemes can gain interest from the possibilities opened by the FEL, especially by access to new wavelengths ranges. Some schemes implying UV or VUV photons will be discussed, as well as some possibilities involving IR photons. Attention will be paid to the problems that arise when considering scaled-up isotope separation installations. A large scale process results in more constraints on the laser parameters. Estimation of FEL capacity in this respect will be attempted

Spectroscopic and thermal properties of uranium relevant to atomic schemes for laser isotope separation

International Nuclear Information System (INIS)

Ahmad, S.A.; Pandey, P.L.

1980-01-01

Spectroscopic data on uranium atom and thermal properties of uranium relevant to atomic schemes for laser isotope separation have been presented in this report. All the relevant spectroscopic data reported in literature so far, as well as some other parameters like photo-absorption cross sections, branching ratios, effects of magnetic and electric fields, evaluated using the existing data, have been presented here. Among the thermal properties, parameters like vapour pressure and number densities for U/Liquid U, U/URe 2 and U/UP systems, partition function, percentage population distribution in energy levels, thermal ionisation and velocities of uranium atom have been presented at different temperatures. Different possible collision processes are mentioned and cross-sections of U-U + charge-exchange and U + + e radiative recombination processes have been also evaluated. (author)

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

Method of concentrating and separating lithium isotopes by laser

International Nuclear Information System (INIS)

Yamashita, Mikio; Kashiwagi, Hiroshi.

1976-01-01

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

Micromachining and dicing of sapphire, gallium nitride and micro LED devices with UV copper vapour laser

International Nuclear Information System (INIS)

Gu, E.; Jeon, C.W.; Choi, H.W.; Rice, G.; Dawson, M.D.; Illy, E.K.; Knowles, M.R.H.

2004-01-01

Gallium nitride (GaN) and sapphire are important materials for fabricating photonic devices such as high brightness light emitting diodes (LEDs). These materials are strongly resistant to wet chemical etching and also, low etch rates restrict the use of dry etching. Thus, to develop alternative high resolution processing and machining techniques for these materials is important in fabricating novel photonic devices. In this work, a repetitively pulsed UV copper vapour laser (255 nm) has been used to machine and dice sapphire, GaN and micro LED devices. Machining parameters were optimised so as to achieve controllable machining and high resolution. For sapphire, well-defined grooves 30 μm wide and 430 μm deep were machined. For GaN, precision features such as holes on a tens of micron length scale have been fabricated. By using this technique, compact micro LED chips with a die spacing 100 and a 430 μm thick sapphire substrate have been successfully diced. Measurements show that the performances of LED devices are not influenced by the UV laser machining. Our results demonstrate that the pulsed UV copper vapour laser is a powerful tool for micromachining and dicing of photonic materials and devices

Ultratrace Uranium Fingerprinting with Isotope Selective Laser Ionization Spectrometry

International Nuclear Information System (INIS)

Ziegler, Summer L.; Bushaw, Bruce A.

2008-01-01

Uranium isotope ratios can provide source information for tracking uranium contamination in a variety of fields, ranging from occupational bioassay to monitoring aftereffects of nuclear accidents. We describe the development of Isotope Selective Laser Ionization Spectrometry (ISLIS) for ultratrace measurement of the minor isotopes 234U, 235U, and 236U with respect to 238U. Optical isotopic selectivity in three-step excitation with single-mode continuous wave lasers is capable of measuring the minor isotopes at relative abundances below 1 ppm, and is not limited by isobaric interferences such as 235UH+ during measurement of 236U. This relative abundance limit approaches the threshold for measurement of uranium minor isotopes with conventional mass spectrometry, typically 10-7, but without mass spectrometric analysis of the laser-created ions. Uranyl nitrate standards from an international blind comparison were used to test analytical performance for different isotopic compositions and with quantities ranging from 11 ng to 10 (micro)g total uranium. Isotopic ratio determination was demonstrated over a linear dynamic range of 7 orders of magnitude with a few percent relative precision and detection limits below 500 fg for the minor isotopes

Atomic-vapor-laser isotope separation

International Nuclear Information System (INIS)

Davis, J.I.

1982-10-01

This paper gives a brief history of the scientific considerations leading to the development of laser isotope separation (LIS) processes. The close relationship of LIS to the broader field of laser-induced chemical processes is evaluated in terms of physical criteria to achieve an efficient production process. Atomic-vapor LIS processes under development at Livermore are reviwed. 8 figures

Pulsed CO laser for isotope separation of uranium

Energy Technology Data Exchange (ETDEWEB)

Baranov, Igor Y.; Koptev, Andrey V. [Rocket-Space Technics Department, Baltic State Technical University, 1, 1st Krasnoarmeyskaya st.,St. Petersburg, 190005 (Russian Federation)

2012-07-30

This article proposes a technical solution for using a CO laser facility for the industrial separation of uranium used in the production of fuel for nuclear power plants, employing a method of laser isotope separation of uranium with condensation repression in a free jet. The laser operation with nanosecond pulse irradiation can provide an acceptable efficiency in the separating unit and a high efficiency of the laser with the wavelength of 5.3 {mu}m. In the present work we also introduce a calculation model and define the parameters of a mode-locked CO laser with a RF discharge in the supersonic stream. The average pulsed CO laser power of 3 kW is sufficient for efficient industrial isotope separation of uranium in one stage.

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.

Copper vapour laser with an efficient semiconductor pump generator having comparable pump pulse and output pulse durations

Energy Technology Data Exchange (ETDEWEB)

Yurkin, A A [P N Lebedev Physics Institute, Russian Academy of Sciences, Moscow (Russian Federation)

2016-03-31

We report the results of experimental studies of a copper vapour laser with a semiconductor pump generator capable of forming virtually optimal pump pulses with a current rise steepness of about 40 A ns{sup -1} in a KULON LT-1.5CU active element. To maintain the operating temperature of the active element's channel, an additional heating pulsed oscillator is used. High efficiency of the pump generator is demonstrated. (lasers)

Separation of nitrogen isotopes by laser light

Energy Technology Data Exchange (ETDEWEB)

Izawa, Y; Noguchi, Y; Yamanaka, C [Osaka Univ., Suita (Japan). Faculty of Engineering

1976-06-01

The separation experiment on nitrogen isotopes by laser light was made. First, the nitrogen isotopes of /sup 14/N and /sup 15/N in NH/sub 3/ molecules were separated by CO/sub 2/ laser and UV light. The separation factor and the enrichment factor were calculated. It was shown that their pressure dependence was in good agreement with the measured values. The separation factor of about 2% was obtained with UV light of 10/sup 6/W/cm/sup 2/.

Lasers for isotope separation

International Nuclear Information System (INIS)

O'Hair, E.A.; Piltch, M.S.

1976-01-01

The Los Alamos Scientific Laboratory is conducting research on uranium enrichment. All processes being studied employ uranium molecules and use lasers to provide isotopic selectivity and enrichment. There are four well-defined infrared frequencies and two ultraviolet frequency bands of interest. The infrared frequencies are outside the range of the available lasers and an extensive research and development activity is currently underway. Lasers are available in the uv bands, however, much development work remains. The specification for the commercial uranium enrichment plant lasers will depend upon the results of the current enrichment experiments, the laser capital cost, reliability, and maintenance cost. For the processes under investigation there are specific photon requirements but latitude in how these requirements can be met. The final laser selections for the pilot plant need not be made until the mid-1980's. Between now and that time as extensive as possible a research and development effort will be maintained

Modeling of the Process of Three-Isotope (H, D, T) Exchange Between Hydrogen Gas and Water Vapour on Pt-SDBC Catalyst over a Wide Range of Deuterium Concentration

International Nuclear Information System (INIS)

Fedorchenko, O.A.; Alekseev, I.A.; Tchijov, A.S.; Uborsky, V.V.

2005-01-01

The large scale studies of Combined Electrolysis and Catalytic Exchange (CECE) process in Petersburg Nuclear Physics Institute showed a complicated influence of various factors on the process caused by the presence of two simultaneous isotope exchange sub processes: counter-current phase exchange (between liquid water and water vapour) and co-current catalytic exchange (between hydrogen gas and water vapour). A laboratory scale set-up of glass made apparatuses was established in such a way that it allows us to study phase and catalytic exchange apart. A computer model of the set-up has been developed.The catalytic isotope exchange model formulation is presented. A collection of reversible chemical reactions is accompanied by diffusion of the gaseous reactants and reaction products in the pores of catalyst carrier. This has some interesting features that are demonstrated. Thus it was noted that the flow rates ratio (gas to vapour - λ = G/V) as well as the concentrations of reactants exert influence on the process efficiency

Laser spectroscopy of radioactive barium and strontium isotopes

International Nuclear Information System (INIS)

Martin, A.G.

1986-01-01

An atomic beam system and a high resolution computer controlled dye laser system were developed to perform isotope shift measurements on accelerator-produced radioactive isotopes. Two different techniques were used to transport the radioactive isotopes to the laser interaction region. The first technique was based on the thermalization and deionization of the nuclear reaction products in a helium buffer gas. The reaction products were subsequently transported in the gas to the laser beam along a capillary tube. This technique suffered from problems with chemical reactions between impurities in the buffer gas and the reaction products and proved to be unsuccessful. The second technique was based on the implantation of the reaction products into a metal lattice. Subsequent heating of the metal lattice released the implanted ions from which an atomic beam was formed. The photon burst technique was used to enable detection of the extremely weak atomic beams formed in this manner. Measurements were performed of the known isotope shifts of radioactive 128 Ba and 126 Ba to test the sensitivity of the system. The previously unmeasured isotope shift of radioactive 82 Sr also was determined, and the result obtained was compared to predictions using the droplet model

Analysis of laser-induced evaporation of Al target under conditions of vapour plasma formation

International Nuclear Information System (INIS)

Mazhukin, V.I.; Nossov, V.V.; Smurov, I.

2004-01-01

The plasma-controlled evaporation of the Al target induced by the laser pulse with intensity of 10 9 W/cm 2 and wavelength of 1.06 μm is analysed with account for the two-dimensional effects. The self consistent model is applied, including the heat transfer equation in condensed medium, the equations of radiation gas dynamics in evaporated substance and the Knudsen layer model at the two media boundary. It is found that the phase transition at the target surface is controlled by the two factors: the surface temperature that depends on the transmitted radiation intensity, and the plasma pressure, governed by the expansion regime. The process comes through three characteristic stages, the sonic evaporation at the beginning, the condensation during the period of plasma formation and initial expansion, and finally, the re-start of evaporation in subsonic regime after the partial brightening of the plasma. During the subsonic evaporation stage the vapour flow and the mass removal rate are much higher near the beam boundaries than in the centre due to smaller plasma counter-pressure. The vapour plasma pattern is characterised by the dense hot zone near the surface where the absorption of laser energy occurs, and rapid decrease of density outside the zone due to three-dimensional expansion

Atomic vapour laser isotope separation in France

International Nuclear Information System (INIS)

Camarcat, N.; Lafon, A.; Perves, J.P.; Rosengard, A.

1993-01-01

France has a specific position in the uranium enrichment market. It has a major nuclear park, supplying 75% of the nation's electricity. On one hand the modern multinational EURODIF gaseous diffusion plant (10.8 M.SWU/y) works smoothly, and its supply of nuclear generated electricity offers customers a good long term view on enrichment costs. A program to improve its performances and to extend its lifespan is well in progress. It will offer a fast modulation capability, with advantage of off-peak power for about 3/4 of its electrical requirements. On the other hand, today's situation of over capacity, accentuated by non-commercial practices, may lead to a brutal restructuring of the world-wide enrichment industry in the coming years. The French approach has a long term goal, with a priority for a high performance process, which will be available when world stocks of enriched uranium are exhausted, and aging enrichment plants have to be shut down. To reach this goal, French Atomic Energy Commission has focused since 1985 on the atomic laser route, SILVA, in agreement with the industrial operator, COGEMA. Fully integrated pre-industrial experience, too costly, will be delayed as long as possible, toward the end of the decade. It will benefit from the most advanced options, taking into account the difficulty of changing them once demonstration has been achieved. The SILVA program is periodically assessed from both the scientific and the industrial point of view and a general assessment is to be made between 1996 and 1997, prior to pre-industrial development

On the problems of separation work unit for the laser isotope separation

International Nuclear Information System (INIS)

Wang, Lijun

2008-01-01

The concept of separation power or separation work, which is widely used in Uranium isotope separation industry is introduced historically for the weak separating machine and so-called 'ideal cascade'. Therefore, when this concept is applied to a laser isotope separation facility, which is deeply different from a cascade in structure and in mechanism of separation, some confusions may occur. By comparison the costs of SWU of laser isotope separation facility and an ideal cascade we come to a conclusion: the concept of separation work is not applicable for laser isotope separation. In order to compare the economics of laser isotope separation technique with diffusion or centrifugation techniques an equivalent cost of SWU is suggested in this paper. (author)

Cost analysis of lasers for a laser isotope separation system. Final report

International Nuclear Information System (INIS)

Mail, R.A.; Markovich, F.J.; Carr, R.H.

1977-01-01

To be of practical significance, laser isotope separation (LIS) for separation of 235 U from 238 U must exhibit attributes which make it preferable to expansion of the present facilities. Clearly the most attractive such attribute is the prospect of significant cost reductions, which preliminary studies at LLL suggest will amount to a factor of three and perhaps as much as ten. From these preliminary studies, it appears that the lasers themselves account for a very substantial portion of the capital cost of a LIS system, and a significant portion of the equipment replacement costs. Since the laser costs are so pivotal to the system cost, and the system cost is so pivotal to the choice of separation techniques, it is clear that a more detailed investigation of laser costs is required. Results are presented of a study performed by General Research Corporation (GRC) to assess the cost of lasers in a production laser isotope separation (LIS) plant

Radio-isotope production using laser Wakefield accelerators

International Nuclear Information System (INIS)

Leemans, W.P.; Rodgers, D.; Catravas, P.E.; Geddes, C.G.R.; Fubiani, G.; Toth, C.; Esarey, E.; Shadwick, B.A.; Donahue, R.; Smith, A.; Reitsma, A.

2001-01-01

A 10 Hz, 10 TW solid state laser system has been used to produce electron beams suitable for radio-isotope production. The laser beam was focused using a 30 cm focal length f/6 off-axis parabola on a gas plume produced by a high pressure pulsed gas jet. Electrons were trapped and accelerated by high gradient wakefields excited in the ionized gas through the self-modulated laser wakefield instability. The electron beam was measured to contain excesses of 5 nC/bunch. A composite Pb/Cu target was used to convert the electron beam into gamma rays which subsequently produced radio-isotopes through (gamma, n) reactions. Isotope identification through gamma-ray spectroscopy and half-life time measurements demonstrated that Cu 61 was produced which indicates that 20-25 MeV gamma rays were produced, and hence electrons with energies greater than 25-30 MeV. The production of high energy electrons was independently confirmed using a bending magnet spectrometer. The measured spectra had an exponential distribution with a 3 MeV width. The amount of activation was on the order of 2.5 uCi after 3 hours of operation at 1 Hz. Future experiments will aim at increasing this yield by post-accelerating the electron beam using a channel guided laser wakefield accelerator

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...

Efficiencies of laser dyes for atomic vapor laser isotope separation

International Nuclear Information System (INIS)

Maeda, Mitsuo; Oki, Yuji; Uchiumi, Michihiro; Takao, Takayuki; Igarashi, Kaoru; Shimamoto, Kojiro.

1995-01-01

Efficiencies of 30 laser dyes for the atomic vapor laser isotope separation (AVLIS) are experimentally evaluated with a dye laser pumped by a frequency-doubled Nd:YAG laser. On the other hand, a simulation code is developed to describe the laser action of Rhodamine 6G, and the dependence of the laser efficiency on the pump wavelength is calculated. Following conclusions are obtained by these considerations:space: 1) Pyrromethene 567 showed 16% higher laser efficiency than Rhodamine 6G by 532 nm pumping, and Pyrromethene 556 has an ability to provide better efficiency by green light pumping with a Cu vapor laser; 2) Kiton red 620 and Rhodamine 640, whose efficiencies were almost the same as Rhodamine 6G by 532 nm pumping, will show better efficiencies by two-wavelength pumping with a Cu vapor laser. (author)

Possible application of laser isotope separation

International Nuclear Information System (INIS)

Delionback, L.M.

1975-05-01

The laser isotope separation process is described and its special economic features discussed. These features are its low cost electric power operation, capital investment costs, and the costs of process materials. (Author)

Vapour pressure of D2O - Ice at temperatures below 237 K

International Nuclear Information System (INIS)

Heras, J.M.; Asensio, M.C.; Estiu, G.; Viscido, L.

1984-01-01

Accurate measurements of heavy water ice vapour pressures between 193 and 253 K have been carried out and an equation based on thermodynamic data has been derived in order to calculate the D 2 O-ice vapour pressures between 173 and 273 K. The agreement between our calculated vapour pressures and the available experimental data including those in this paper, is very good. The comparison between the theoretical calculations of H 2 O-ice and D 2 O-ice vapour pressures confirms the experimental evidence that H 2 O-ice is more volatile than D 2 O-ice at all temperatures in agreement with the vapour isotopic effect theory (VPIE).(author)

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 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.

An overview of copper-laser development for isotope separation

International Nuclear Information System (INIS)

Warner, B.E.

1987-01-01

We have developed a copper-laser pumped dye-laser system that addresses all of the requirements for atomic vapor laser isotope separation. The requirement for high average power for the laser system has led to the development of copper-laser chains with injection-locked oscillators and multihundred-watt amplifiers. By continuously operating the Laser Demonstration Facility, we gain valuable data for further upgrade and optimization

Isotope separation by laser deflection of an atomic beam

International Nuclear Information System (INIS)

Bernhardt, A.F.

1975-02-01

Separation of isotopes of barium was accomplished by laser deflection of a single isotopic component of an atomic beam. With a tunable narrow linewidth dye laser, small differences in absorption frequency of different barium isotopes on the 6s 2 1 S 0 --6s6p 1 P 1 5536A resonance were exploited to deflect atoms of a single isotopic component of an atomic beam through an angle large enough to physically separate them from the atomic beam. It is shown that the principal limitation on separation efficiency, the fraction of the desired isotopic component which can be separated, is determined by the branching ratio from the excited state into metastable states. The isotopic purity of the separated atoms was measured to be in excess of 0.9, limited only by instrumental uncertainty. To improve the efficiency of separation, a second dye laser was employed to excite atoms which had decayed to the 6s5d metastable state into the 6p5d 1 P 1 state from which they could decay to the ground state and continue to be deflected on the 5535A transition. With the addition of the second laser, separation efficiency of greater than 83 percent was achieved, limited by metastable state accumulation in the 5d 2 1 D 2 state which is accessible from the 6p5d 1 P 1 level. It was found that the decay rate from the 6p5d state into the 5d 2 metastable state was fully 2/3 the decay rate to the ground state, corresponding to an oscillator strength of 0.58. (U.S.)

Laser beam-forming by deformable mirror for laser isotope separation

International Nuclear Information System (INIS)

Nemoto, Koshichi; Fujii, Takashi; Goto, Naohiko

1995-01-01

A rectangular laser beam of uniform intensity is very suitable for laser isotope separation. In this paper, we propose a beam-forming system which consists two deformable mirrors. One of the mirrors changes the beam intensity and the other compensates for phase distortion. We developed a deformable mirror for beam-forming. Its deformed surface is similar to the ideal mirror surface for beam-forming. We reshaped a Gaussian-like He-Ne laser beam into a beam with a more uniform intensity profile by a simple deformable mirror. (author)

Synthesis of suspended carbon nanotubes on silicon inverse-opal structures by laser-assisted chemical vapour deposition

International Nuclear Information System (INIS)

Shi, J; Lu, Y F; Wang, H; Yi, K J; Lin, Y S; Zhang, R; Liou, S H

2006-01-01

Suspended single-walled carbon nanotubes (SWNTs) have been synthesized on Si inverse-opal structures by laser-assisted chemical vapour deposition (LCVD). A CW CO 2 laser at 10.6 μm was used to directly irradiate the substrates during the LCVD process. At a laser power density of 14.3 MW m -2 , suspended SWNT networks were found predominantly rooted at the sharp edges in the Si inverse-opal structures. Raman spectroscopy indicated that the SWNT networks were composed of high-quality defect-free SWNTs with an average diameter of 1.3 nm. At a lower laser power density (6.4 MW m -2 ), multi-walled carbon nanotubes (MWNTs) were grown on the entire surface of the substrates. The preference for the synthesis of SWNTs or MWNTs was attributed to the difference in the catalyst sizes as well as the growth temperature in the LCVD process

Dual-channel amplification in a single-mode diode laser for multi-isotope laser cooling

International Nuclear Information System (INIS)

Booth, James L.; Van Dongen, Janelle; Lebel, Paul; Klappauf, Bruce G.; Madison, Kirk W.

2007-01-01

The output from two grating-stabilized external-cavity diode lasers were injected into a single-mode diode laser. Operating at a wavelength of 780 nm, this laser produced ∼50 mW of power with two main frequency components of the same spectral characteristics of the seed lasers. The power ratio of the amplified components was freely adjustable due to gain saturation, and amplification was observed for frequency differences of the two seed lasers in the range from 73 MHz to 6.6 GHz. This system was used to realize a dual isotope magneto-optic trap (MOT) for rubidium ( 85 Rb and 87 Rb). The resulting position and cloud size of the dual isotope MOT was the same as that of the single species MOTs to within ±10 and ±20 μm, respectively. We also characterized the additional spectral components produced by four wave mixing (FWM) in the diode laser amplifier and utilized a particular FWM sideband to realize hyperfine pumping and subsequent laser trapping of 85 Rb in the absence of a 'repump' laser dedicated to hyperfine pumping

Isotope separation by selective dissociation of trifluoromethane with an infrared laser

International Nuclear Information System (INIS)

Hartford, A.J.

1982-01-01

A process for obtaining compounds enriched in a desired isotope of an element selected from hydrogen and carbon comprises exposing subatmospheric pressure gaseous trifluoromethane containing said desired isotope and one or more other isotopes of the same element to infrared laser radiation of a predetermined frequency, which selectively dissociates trifluoromethane molecules containing said desired isotope and separating the resulting dissociation product enriched in said desired isotope from the remainder of the gas. The term 'trifluoromethane' (TFM) refers to a mixture of CF 3 H and CF 3 D, the latter constituting about 0.015 percent of the total. TFM is irradiated with a CO 2 laser at an appropriate infrared wavelength

Laser separation of nitrogen isotopes by the IR+UV dissociation of ammonia molecules

International Nuclear Information System (INIS)

Apatin, V M; Klimin, S A; Laptev, V B; Lokhman, V N; Ogurok, D D; Pigul'skii, S V; Ryabov, E A

2008-01-01

The separation of nitrogen isotopes is studied upon successive single-photon IR excitation and UV dissociation of ammonia molecules. The excitation selectivity was provided by tuning a CO 2 laser to resonance with 14 NH 3 molecules [the 9R(30) laser line] or with 15 NH 3 molecules [the 9R(10) laser line]. Isotopic mixtures containing 4.8% and 0.37% (natural content) of the 15 NH isotope were investigated. The dependences of the selectivity and the dissociation yield for each isotopic component on the buffer gas pressure (N 2 , O 2 , Ar) and the ammonia pressure were obtained. In the limit of low NH 3 pressures (0.5-2 Torr), the dissociation selectivity α(15/14) for 15 N was 17. The selectivity mechanism of the IR+UV dissociation is discussed and the outlook is considered for the development of the nitrogen isotope separation process based on this approach. (laser isotope separation)

Vapour pressure of trideuterioammonia

Energy Technology Data Exchange (ETDEWEB)

Calado, J.C.G.; Lopes, J.N.C.; Rebelo, L.P.N. (Instituto Superior Tecnico, Lisbon (Portugal). Centro de Quimica Estrutural)

1992-09-01

The H-to-D vapour-pressure isotope effect in liquid ammonia has been measured at 62 temperatures between 228 K and 260 K. The vapour pressures, corrected to 100 per cent nuclidic purity, have been fitted to the equation: T ln r = A+B/T+CT, where r is the vapour-pressure ratio p(NH[sub 3])/p(ND[sub 3]). The fit yielded the parameters: A = -8.22508 K, B = 12338.2 K[sup 2], and C = -0.05544. Comparisons with the results of other authors were made in order to clarify some discrepancies found in the literature. Our values are in accord with the previous results of King et al. and an extrapolation of the fitted equation down to the triple-point temperature gave good agreement with the published results. The fitted equation was used in conjunction with the Clapeyron equation to calculate the difference in the molar enthalpies of vaporization between NH[sub 3] and ND[sub 3]. At T = 230 K that difference is -846 J.mol[sup -1] decreasing to -747 J.mol[sup -1] at 260 K. (author).

Laser alteration of accommodation coefficient for isotope separation

International Nuclear Information System (INIS)

Keck, J.C.

1976-01-01

This patent describes a method and an apparatus for separating isotope types by inducing an isotopically selective vibrational excitation of molecules containing at least one atom of the element type whose isotopes are to be separated. Vibrational excitation is induced in the molecules by finely tuned, narrow bandwidth laser radiation applied to a gaseous flow of the molecules. Isotopic separation of the molecules is achieved from the enhanced difference in diffusion rates for the molecules due to an alteration of the accommodation coefficients in the excited molecules. 40 claims, 4 figures

Preliminary review on isotope separation of long life fission products. Application research of laser isotope separation to 135Cs

International Nuclear Information System (INIS)

Oshita, Hironori; Ozawa, Masaki; Ishikawa, Makoto; Koyama, Shin'ichi; Akatsuka, Hiroshi

2007-09-01

Recently establishment of self consistent nuclear fuel cycle has been required with respect to economical efficiency, safety and reduction of the load to the environment. Especially 135 Cs included in spent fuel of nuclear power plants has extremely long half life (3.0x10 6 y) and its water solubility leads to the anxiety of exudation into ground water for geologic disposal. The conventional methods for isotope separation based on the mass difference of isotope could not gain large separation factors, which leads to the requirement of operational repetition and large equipment. Furthermore many elements of which the masses are near to that of the object isotope are included in spent fuel, which makes it difficult to expect high separation factor by the methods merely based on the mass difference. Recent technology development of laser e.g. dye laser or semi-conductor laser has come to make it possible in principle to excite a specific isotope and separate it from other isotopes making use of its intrinsic physical and chemical properties of the excited state. This laser isotope separation (LIS) technique is believed to be suitable for cesium because of its stable properties on light absorption and emission and many studies have come to be made. This document reviews the principle, application to the separation of 135 Cs and current status of LIS and reports the subjects to be solved and suggestions; especially laser induced chemical reactions expected as a low-cost and simple equipment isotope separation method. The resulting extracted subjects are 1) the specification of the excited states of cesium i.e. extra-nuclear electron configuration, life (or duration) and transition probability, 2) the factors that may effect on the isotope shift of cesium; the mean square radius of the nucleus, electric quadrupole moment and extra nuclear electron wave function at the nucleus, 3) the factors that may cause the disturbance of the selectivity; resonant energy transference

Some characteristics of isotopic separation laser systems

International Nuclear Information System (INIS)

Pochon, E.

1988-01-01

The principle of Laser Isotope Separation (LIS) is simple and based on either selective electronic photoexcitation and photoionization of atomic vapor, or selective vibrational photoexcitation and photodissociation of molecules in the gas phase. These processes, respectively called SILVA (AVLIS) and SILMO (MLIS) in France, both use specific laser systems with wavelengths spanning from infrared to ultraviolet. This article describes briefly some of the characteristics of a SILVA laser system. Following a three-step process, a SILVA laser system is based on dye copper vapor lasers. The pulse dye lasers provide the tunable laser light and are optically pumped by copper vapor laser operating at high repetition rates. In order to meet plant laser system requirements, the main improvements under way relate to copper vapor laser devices the power capability, efficiency, reliability and lifetime of which have to be increased. 1 fig

Innovative lasers for uranium isotope separation

International Nuclear Information System (INIS)

Brake, M.L.; Gilgenbach, R.M.

1993-07-01

Copper vapor laser have important applications to uranium atomic vapor laser isotope separation (AVLIS). We have investigated two innovative methods of exciting/pumping copper vapor lasers which have the potential to improve the efficiency and scaling of large laser systems used in uranium isotope separation. Experimental research has focused on the laser discharge kinetics of (1) microwave, and (2) electron beam excitation/pumping of large-volume copper vapor lasers. Microwave resonant cavity produced copper vapor plasmas at 2.45 GHz, have been investigated in three separate experimental configurations. The first examined the application of CW (0-500W) power and was found to be an excellent method for producing an atomic copper vapor from copper chloride. The second used a pulsed (5kW, 0.5--5 kHz) signal superimposed on the CW signal to attempt to produce vaporization, dissociation and excitation to the laser states. Enhanced emission of the optical radiation was observed but power densities were found to be too low to achieve lasing. In a third experiment we attempted to increase the applied power by using a high power magnetron to produce 100 kW of pulsed power. Unfortunately, difficulties with the magnetron power supply were encountered leaving inconclusive results. Detailed modeling of the electromagnetics of the system were found to match the diagnostics results well. An electron beam pumped copper vapor system (350 kV, 1.0 kA, 300 ns) was investigated in three separate copper chloride heating systems, external chamber, externally heated chamber and an internally heated chamber. Since atomic copper spectral lines were not observed, it is assumed that a single pulse accelerator is not capable of both dissociating the copper chloride and exciting atomic copper and a repetitively pulsed electron beam generator is needed

Atomic vapor laser isotope separation

International Nuclear Information System (INIS)

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

1985-01-01

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

Control strategies for laser separation of carbon isotopes

Indian Academy of Sciences (India)

Laser isotope separation (LIS) by infrared laser chemistry of polyatomic molecules has come a long way since its discovery. The last decade has seen considerable efforts in scaling up of the process for light elements like carbon, oxygen and silicon. These efforts aim at ways to improve both the enrichment factor and the ...

Isotope analysis of micro metal particles by adopting laser-ablation mass spectrometry

International Nuclear Information System (INIS)

Song, Kyu Seok; Ha, Young Kyung; Han, Sun Ho; Park, Yong Joon; Kim, Won Ho

2005-01-01

The isotope analysis of microparticles in environmental samples as well as laboratory samples is an important task. A special concern is necessary in particle analysis of swipe samples. Micro particles are normally analyzed either by dissolving particles in the solvents and adopting conventional analytical methods or direct analysis method such as a laser-ablation ICP mass spectrometry (LA-ICP-MS), SIMS, and SNMS (sputtered neutral mass spectrometry). But the LA-ICPMS uses large amount of samples because normally laser beam is tightly focused on the target particle for the complete ablation. The SIMS and SNMS utilize ion beams for the generation of sample ions from the particle. But the number of ions generated by an ion beam is less than 5% of the total generated particles in SIMS. The SNMS is also an excellent analytical technique for particle analysis, however, ion beam and frequency tunable laser system are required for the analysis. Recently a direct analysis of elements as well as isotopes by using laser-ablation is recognized one of the most efficient detection technology for particle samples. The laser-ablation mass spectrometry requires only one laser source without frequency tuneability with no sample pretreatment. Therefore this technique is one of the simplest analysis techniques for solid samples as well as particles. In this study as a part of the development of the new isotope analysis techniques for particles samples, a direct laser-ablation is adopted with mass spectrometry. Zinc and gadolinium were chosen as target samples, since these elements have isotopes with minor abundance (0.62% for Zn, and 0.2% for Gd). The preliminary result indicates that isotopes of these two elements are analyzed within 10% of natural abundance with good mass resolution by using direct laser-ablation mass spectrometry

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 assisted jet nozzle isotope separation

International Nuclear Information System (INIS)

1981-01-01

A process for separating fluent particles having different masses comprises the steps of: driving a fluent mixture of such particles around a curved passage toward a septum oriented to divide the mixture thereby accelerating such particles to impart a centrifugal force thereto; inducing type selective heating of a selected particle type in said mixture prior to termination of such acceleration; receiving the fraction of the mixture flowing past an outer surface of said septum in a first output conduit; and receiving the fraction of the mixture flowing past an inner surface of said septum in a second output conduit. The description of the process for isotope separation refers also to the use of infrared laser radiation to produce isotopically selective excitation of the U-235 isotope in UF 6 . (author)

Micro-scale novel stable isotope fractionation during weathering disclosed by femtosecond laser ablation

Science.gov (United States)

Schuessler, J. A.; von Blanckenburg, F.

2012-12-01

The stable isotope fractionation of metals and metalloids during chemical weathering and alteration of rocks at low temperature is a topic receiving increasing scientific attention. For these systems, weathering of primary minerals leads to selective partitioning of isotopes between the secondary minerals formed from them, and the dissolved phase of soil or river water. While the isotopic signatures of these processes have been mapped-out at the catchment or the soil scale, the actual isotopic fractionation is occurring at the mineral scale. To identify the processes underlying such micro-scale fractionation, the development of micro-analytical tools allows to investigate mechanisms of isotope fractionation in-situ, in combination with textural information of weathering reactions. We have developed a second-generation UV femtosecond (fs) laser system at GFZ Potsdam. The advantage of UV-fs laser ablation is the reduction of laser-induced isotopic and elemental fractionation by avoiding 'thermal effects' during ablation, such that accurate isotope ratios can be measured by standard-sample-standard bracketing using laser ablation multicollector ICP-MS; where the matrix of the bracketing standard does not need to match that of the sample [1]. Our system consists of the latest generation femtosecond solid-state laser (Newport Spectra Physics Solstice), producing an ultra short pulse width of about 100 femtoseconds at a wavelength of 196 nm. The system is combined with a custom-build computer-controlled sample stage and allows fully automated isotope analyses through synchronised operation of the laser with the Neptune MC-ICP-MS. To assess precision and accuracy of our laser ablation method, we analysed various geological reference materials. We obtained δ30Si values of -0.31 ± 0.23 (2SD, n = 13) for basalt glass BHVO-2G, and -1.25 ± 0.21 (2SD, n = 27) for pure Si IRMM17 when bracketed against NBS-28 quartz. δ56Fe and δ26Mg values obtained from non-matrix matched

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

International Nuclear Information System (INIS)

Marsh, B. A.

2014-01-01

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

Isotope Enrichment Detection by Laser Ablation - Laser Absorption Spectrometry: Automated Environmental Sampling and Laser-Based Analysis for HEU Detection

International Nuclear Information System (INIS)

Anheier, Norman C.; Bushaw, Bruce A.

2010-01-01

The global expansion of nuclear power, and consequently the uranium enrichment industry, requires the development of new safeguards technology to mitigate proliferation risks. Current enrichment monitoring instruments exist that provide only yes/no detection of highly enriched uranium (HEU) production. More accurate accountancy measurements are typically restricted to gamma-ray and weight measurements taken in cylinder storage yards. Analysis of environmental and cylinder content samples have much higher effectiveness, but this approach requires onsite sampling, shipping, and time-consuming laboratory analysis and reporting. Given that large modern gaseous centrifuge enrichment plants (GCEPs) can quickly produce a significant quantity (SQ ) of HEU, these limitations in verification suggest the need for more timely detection of potential facility misuse. The Pacific Northwest National Laboratory (PNNL) is developing an unattended safeguards instrument concept, combining continuous aerosol particulate collection with uranium isotope assay, to provide timely analysis of enrichment levels within low enriched uranium facilities. This approach is based on laser vaporization of aerosol particulate samples, followed by wavelength tuned laser diode spectroscopy to characterize the uranium isotopic ratio through subtle differences in atomic absorption wavelengths. Environmental sampling (ES) media from an integrated aerosol collector is introduced into a small, reduced pressure chamber, where a focused pulsed laser vaporizes material from a 10 to 20-(micro)m diameter spot of the surface of the sampling media. The plume of ejected material begins as high-temperature plasma that yields ions and atoms, as well as molecules and molecular ions. We concentrate on the plume of atomic vapor that remains after the plasma has expanded and then cooled by the surrounding cover gas. Tunable diode lasers are directed through this plume and each isotope is detected by monitoring absorbance

Cavity Ring-down Spectroscopy for Carbon Isotope Analysis with 2 μm Diode Laser

International Nuclear Information System (INIS)

Hiromoto, K.; Tomita, H.; Watanabe, K.; Kawarabayashi, J.; Iguchi, T.

2009-01-01

We have made a prototype based on CRDS with 2 μm diode laser for carbon isotope analysis of CO 2 in air. The carbon isotope ratio was obtained to be (1.085±0.012)x10 -2 which shows good agreement with the isotope ratio measured by the magnetic sector-type mass spectrometer within uncertainty. Hence, we demonstrated the carbon isotope analysis based on CRDS with 2 μm tunable diode laser.

Collinear laser spectroscopy on In isotopes from heavy ion fusion reactions

International Nuclear Information System (INIS)

Ulm, G.

1984-07-01

Indium isotopes 107-111 were produced by 16 O-fusion reactions and investigated in a collinear laser geometry. The hyperfine structure and isotopic shifts are measured and the deduced magnetic dipole moments are in agreement with shell model calculations. The nuclear charge radii are determined from the isotopic shifts. (WL)

Innovative lasers for uranium isotope separation. [Progress report

Energy Technology Data Exchange (ETDEWEB)

Brake, M.L.; Gilgenbach, R.M.

1991-06-01

Copper vapor lasers have important applications to uranium atomic vapor laser isotope separation (AVLIS). The authors have spent the first two years of their project investigating two innovative methods of exciting/pumping copper vapor lasers which have the potential to improve the efficiency and scaling of large laser systems used in uranium isotope separation. Experimental research has focused on the laser discharge kinetics of (1) microwave, and (2) electron beam excitation/pumping of large-volume copper vapor lasers. During the first year, the experiments have been designed and constructed and initial data has been taken. During the second year these experiments have been diagnosed. Highlights of some of the second year results as well as plans for the future include the following: Microwave resonant cavity produced copper vapor plasmas at 2.45 GHz, have been investigated. A CW (0--500 W) signal heats and vaporizes the copper chloride to provide the atomic copper vapor. A pulsed (5 kW, 0.5--5kHz) signal is added to the incoming CW signal via a hybrid mixer to excite the copper states to the laser levels. An enhancement of the visible radiation has been observed during the pulsed pardon of the signal. Electrical probe measurements have been implemented on the system to verify the results of the electromagnetic model formulated last year. Laser gain measurements have been initiated with the use of a commercial copper vapor laser. Measurements of the spatial profile of the emission are also currently being made. The authors plan to increase the amount of pulsed microwave power to the system by implementing a high power magnetron. A laser cavity will be designed and added to this system.

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.

LLNL medical and industrial laser isotope separation: large volume, low cost production through advanced laser technologies

International Nuclear Information System (INIS)

Comaskey, B.; Scheibner, K. F.; Shaw, M.; Wilder, J.

1998-01-01

The goal of this LDRD project was to demonstrate the technical and economical feasibility of applying laser isotope separation technology to the commercial enrichment (>lkg/y) of stable isotopes. A successful demonstration would well position the laboratory to make a credible case for the creation of an ongoing medical and industrial isotope production and development program at LLNL. Such a program would establish LLNL as a center for advanced medical isotope production, successfully leveraging previous LLNL Research and Development hardware, facilities, and knowledge

Spectral isotopic methods of determining nitrogen and carbon in plant specimens with laser volatization

International Nuclear Information System (INIS)

Lazeeva, G.S.

1986-01-01

Methods have been devised for the local determination of nitrogen and carbon isotope compositions in plant specimens, which provide separate and joint determination. Local laser evaporation has been combined with spectroscopic determination of the isotope compositions in the gas phase. A continuous-wave CO 2 laser is preferable for the local evaporation; the carbon isotope composition may be determined directly on the sum of the evaporation products, whereas nitrogen must first be separated as N 2 . Methods have also been developed for the local determination of total nitrogen and carbon in a sample with isotope dilution on the basis of laser evaporation. In order to eliminate systematic errors in determining total carbon in plant material, an evaporation method free from a rim has been devised. These methods have been used in determining isotope concentration profiles in plant specimens grown in experiments employing labeled nitrogen and carbon

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

International Nuclear Information System (INIS)

Hakimi, Amin

2013-01-01

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

Development of Laser Application Technology for Stable Isotope Production

Energy Technology Data Exchange (ETDEWEB)

Jeong, Do Young; Ko, Kwang Hoon; Kwon, Duck Hee [Korea Atomic Energy Research Institute, Daejeon (Korea, Republic of)] (and others)

2007-04-15

Tl-203 is used as a source material to produce Tl-201 radioisotope which is produced in a cyclotron by irradiating the enriched Tl-203 target. Tl-201 is a radiopharmaceutical for SPECT (single photon emission computerized tomography) to diagnose heart diseases and tumors. This Project aim to develop laser application technology to product stable isotopes such as Tl-203, Yb-168, and Yb-176. For this, photoion extraction device, atomic beam generator, dye lasers, and high power IR lasers are developed.

Development of Laser Application Technology for Stable Isotope Production

International Nuclear Information System (INIS)

Jeong, Do Young; Ko, Kwang Hoon; Kwon, Duck Hee

2007-04-01

Tl-203 is used as a source material to produce Tl-201 radioisotope which is produced in a cyclotron by irradiating the enriched Tl-203 target. Tl-201 is a radiopharmaceutical for SPECT (single photon emission computerized tomography) to diagnose heart diseases and tumors. This Project aim to develop laser application technology to product stable isotopes such as Tl-203, Yb-168, and Yb-176. For this, photoion extraction device, atomic beam generator, dye lasers, and high power IR lasers are developed

Control strategies for laser separation of carbon isotopes

Indian Academy of Sciences (India)

Unknown

Control strategies for laser separation of carbon isotopes. V PARTHASARATHY*, A K ... The emerging market for medical applications of C-13 is projected to be in the range of hundreds of ..... thermal effects during irradiation. In the absence of ...

High-power CO laser with RF discharge for isotope separation employing condensation repression

Science.gov (United States)

Baranov, I. Ya.; Koptev, A. V.

2008-10-01

High-power CO laser can be the effective tool in such applications as isotope separation using the free-jet CRISLA method. The way of transfer from CO small-scale experimental installation to industrial high-power CO lasers is proposed through the use of a low-current radio-frequency (RF) electric discharge in a supersonic stream without an electron gun. The calculation model of scaling CO laser with RF discharge in supersonic stream was developed. The developed model allows to calculate parameters of laser installation and optimize them with the purpose of reception of high efficiency and low cost of installation as a whole. The technical decision of industrial CO laser for isotope separation employing condensation repression is considered. The estimated cost of laser is some hundred thousand dollars USA and small sizes of laser head give possibility to install it in any place.

Automatic laser beam position control on the Isolde-Rilis experiment

CERN Document Server

Grancharova, D; Fedosseev, V; Suberlucq, Guy; CERN. Geneva. AB Department

2003-01-01

The On-Line Isotope Mass Separator ISOLDE at CERN is a facility for production of radioactive ion beams by the interaction of proton beams with a thick target. One of the most widely used types of ion source at ISOLDE is a chemically selective laser ion source based on the method of laser ionization of atoms in a hot cavity - RILIS (Resonance Ionization Laser Ion Source). The optical set-up of RILIS includes three copper vapour lasers, a set of dye lasers and frequency multiplication crystals giving up to three different beams of tuneable wavelengths. This paper will focus on the transport of the laser beams to the targets at distances of 18 m and 23 m, the development of the acquisition of their position and finally the automatic control of optics for an accurate alignment.

[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 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 ...

Laser enhanced microwave plasma isotope separation. Final report, September 30, 1992--September 29, 1995

International Nuclear Information System (INIS)

Brake, M.L.; Gilgenbach, R.M.

1996-06-01

The experimental research was to focus on laser excitation of a low abundance isotope and then ionize and separate the isotope of low abundance using a microwave/ECR discharge at 2.45 GHz. A small compact electron cyclotron resonance ion source, which uses permanent magnets, was constructed during this project. The dye laser was purchased and later an excimer laser had to also be purchased because it turned out that the dye laser could not be pumped by our copper laser. It was intended that the dye laser be tuned to a wavelength of 670.8 nm, which would excite 6 Li which would then be preferentially ionized by the ECR source and collected with a charged grid. The degree of enrichment was to be determined using thermal ionization mass spectrometry. The final objective of this project was to assess the feasibility of this system to large-scale production of stable isotopes. However the funding of this project was interrupted and we were not able to achieve all of our goals

Seeking excellence: An evaluation of 235 international laboratories conducting water isotope analyses by isotope-ratio and laser-absorption spectrometry.

Science.gov (United States)

Wassenaar, L I; Terzer-Wassmuth, S; Douence, C; Araguas-Araguas, L; Aggarwal, P K; Coplen, T B

2018-03-15

Water stable isotope ratios (δ 2 H and δ 18 O values) are widely used tracers in environmental studies; hence, accurate and precise assays are required for providing sound scientific information. We tested the analytical performance of 235 international laboratories conducting water isotope analyses using dual-inlet and continuous-flow isotope ratio mass spectrometers and laser spectrometers through a water isotope inter-comparison test. Eight test water samples were distributed by the IAEA to international stable isotope laboratories. These consisted of a core set of five samples spanning the common δ-range of natural waters, and three optional samples (highly depleted, enriched, and saline). The fifth core sample contained unrevealed trace methanol to assess analyst vigilance to the impact of organic contamination on water isotopic measurements made by all instrument technologies. For the core and optional samples ~73 % of laboratories gave acceptable results within 0.2 ‰ and 1.5 ‰ of the reference values for δ 18 O and δ 2 H, respectively; ~27 % produced unacceptable results. Top performance for δ 18 O values was dominated by dual-inlet IRMS laboratories; top performance for δ 2 H values was led by laser spectrometer laboratories. Continuous-flow instruments yielded comparatively intermediate results. Trace methanol contamination of water resulted in extreme outlier δ-values for laser instruments, but also affected reactor-based continuous-flow IRMS systems; however, dual-inlet IRMS δ-values were unaffected. Analysis of the laboratory results and their metadata suggested inaccurate or imprecise performance stemmed mainly from skill- and knowledge-based errors including: calculation mistakes, inappropriate or compromised laboratory calibration standards, poorly performing instrumentation, lack of vigilance to contamination, or inattention to unreasonable isotopic outcomes. To counteract common errors, we recommend that laboratories include 1-2 'known

Seeking excellence: An evaluation of 235 international laboratories conducting water isotope analyses by isotope-ratio and laser-absorption spectrometry

Science.gov (United States)

Wassenaar, L. I.; Terzer-Wassmuth, S.; Douence, C.; Araguas-Araguas, L.; Aggarwal, P. K.; Coplen, Tyler B.

2018-01-01

RationaleWater stable isotope ratios (δ2H and δ18O values) are widely used tracers in environmental studies; hence, accurate and precise assays are required for providing sound scientific information. We tested the analytical performance of 235 international laboratories conducting water isotope analyses using dual-inlet and continuous-flow isotope ratio mass spectrometers and laser spectrometers through a water isotope inter-comparison test.MethodsEight test water samples were distributed by the IAEA to international stable isotope laboratories. These consisted of a core set of five samples spanning the common δ-range of natural waters, and three optional samples (highly depleted, enriched, and saline). The fifth core sample contained unrevealed trace methanol to assess analyst vigilance to the impact of organic contamination on water isotopic measurements made by all instrument technologies.ResultsFor the core and optional samples ~73 % of laboratories gave acceptable results within 0.2 ‰ and 1.5 ‰ of the reference values for δ18O and δ2H, respectively; ~27 % produced unacceptable results. Top performance for δ18O values was dominated by dual-inlet IRMS laboratories; top performance for δ2H values was led by laser spectrometer laboratories. Continuous-flow instruments yielded comparatively intermediate results. Trace methanol contamination of water resulted in extreme outlier δ-values for laser instruments, but also affected reactor-based continuous-flow IRMS systems; however, dual-inlet IRMS δ-values were unaffected.ConclusionsAnalysis of the laboratory results and their metadata suggested inaccurate or imprecise performance stemmed mainly from skill- and knowledge-based errors including: calculation mistakes, inappropriate or compromised laboratory calibration standards, poorly performing instrumentation, lack of vigilance to contamination, or inattention to unreasonable isotopic outcomes. To counteract common errors, we recommend that

Laser Spectroscopic Analysis of Liquid Water Samples for Stable Hydrogen and Oxygen Isotopes

International Nuclear Information System (INIS)

2009-01-01

Stable isotope ratios of hydrogen and oxygen are tracers of choice for water cycle processes in hydrological, atmospheric and ecological studies. The use of isotopes has been limited to some extent because of the relatively high cost of isotope ratio mass spectrometers and the need for specialized operational skills. Here, the results of performance testing of a recently developed laser spectroscopic instrument for measuring stable hydrogen and oxygen isotope ratios of water samples are described, along with a procedure for instrument installation and operation. Over the last four years, the IAEA Water Resources Programme conducted prototype and production model testing of these instruments and this publication is the outcome of those efforts. One of the main missions of the IAEA is to promote the use of peaceful applications of isotope and nuclear methods in Member States and this publication is intended to facilitate the use of laser absorption based instruments for hydrogen and oxygen stable isotope analyses of liquid water samples for hydrological and other studies. The instrument uses off-axis integrated cavity output spectroscopy to measure absolute abundances of 2 HHO, HH 18 O, and HHO via laser absorption. Test results using a number of natural and synthetic water standards and samples with a large range of isotope values demonstrate adequate precision and accuracy (e.g. precisions of 1 per mille for δ 2 H and 0.2 per mille for δ 18 O). The laser instrument has much lower initial and maintenance costs than mass spectrometers and is substantially easier to operate. Thus, these instruments have the potential to bring about a paradigm shift in isotope applications by enabling researchers in all fields to measure isotope ratios by themselves. The appendix contains a detailed procedure for the installation and operation of the instrument. Using the procedure, new users should be able to install the instrument in less than two hours. It also provides step

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.

High-Voltage Power Supply System for Laser Isotope Separation

Energy Technology Data Exchange (ETDEWEB)

Ketaily, E.C.; Buckner, R.P.; Uhrik, R.L.

1979-06-26

This report presents several concepts for Laser High-Voltage Power Supply (HVPS) Systems for a Laser Isotope Separation facility. Selection of equipments and their arrangement into operational systems is based on proven designs and on application concepts now being developed. This report has identified a number of alternative system arrangements and has provided preliminary cost estimates for each. The report includes a recommendation for follow-on studies that will further define the optimum Laser HVPS Systems. Brief descriptions are given of Modulator/Regulator circuit trade-offs, system control interfaces, and their impact on costs.

High-Voltage Power Supply System for Laser Isotope Separation

International Nuclear Information System (INIS)

Ketaily, E.C.; Buckner, R.P.; Uhrik, R.L.

1979-01-01

This report presents several concepts for Laser High-Voltage Power Supply (HVPS) Systems for a Laser Isotope Separation facility. Selection of equipments and their arrangement into operational systems is based on proven designs and on application concepts now being developed. This report has identified a number of alternative system arrangements and has provided preliminary cost estimates for each. The report includes a recommendation for follow-on studies that will further define the optimum Laser HVPS Systems. Brief descriptions are given of Modulator/Regulator circuit trade-offs, system control interfaces, and their impact on costs

France makes steady progress with lasers [enrichment

International Nuclear Information System (INIS)

Coates, J.-H.; Clerc, M.; Plurien, P.

1988-01-01

With the CHEMEX process now a commercially available technology, the French Commissariat a l'Energie (CEA) is focussing its R and D activity on two enrichment processes: gaseous diffusion, and atomic vapour laser isotope separation (AVLIS or SILVA). The SILVA process is being developed, with particular attention being paid to test campaigns undertaken on the pilot unit installed at Saclay. A core of technical know-how is being maintained in gaseous diffusion in order to study the behaviour of, and possible improvements to, the newly named George Besse plant at the Tricastin site. (U.K.)

Selective photoionization of isotopic atoms with pulsed lasers

International Nuclear Information System (INIS)

Dai Changjian

1994-01-01

The dynamics of isotopically selective interactions between the radiation of three pulsed lasers and atoms with a four-levels scheme has been studied. Starting from the time-dependent Schroedinger equation with the rotating-wave approximation, authors applied Sylvester theorem to the dynamic equations associated with near-and off-resonant excitations, respectively. Authors obtained the explicit expressions for the four-levels occupation probabilities. The analytic treatment explored the properties of coherent oscillations occurred in the atomic excitation processes with intense monochromatic lasers. The conditions under which the population inversion takes place are derived from near-resonant excitations. The criteria to select the basic parameters of pulsed lasers involved in the process are also provided

High voltage fast switches for nuclear applications

International Nuclear Information System (INIS)

Chatroux, D.; Lausenaz, Y.; Villard, J.F.; Lafore, D.

1999-01-01

SILVA process consists in a selective ionization of the 235 uranium isotope, using laser beams generated by dye lasers pumped by copper vapour laser (C.V.L.). SILVA involves power electronic for 3 power supplies: - copper vapour laser power supply, - extraction power supply to generate the electric field in the vapour, and - electron beam power supply for vapour generation. This article reviews the main switches that are proposed on the market or are on development and that could be used in SILVA power supplies. The SILVA technical requirements are: high power, high voltage and very short pulses (200 ns width). (A.C.)

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...

Factors controlling stable isotope composition of European precipitation

International Nuclear Information System (INIS)

Rozanski, K.; Sonntag, C.; Muennich, K.O.

1982-01-01

The seasonal and spatial variations of stable isotope ratios in present day European precipitation are simulated with a simple multibox model of the mean west-east horizontal transport of the atmospheric water vapour across the European continent. Isotope fractionation during the formation of precipitation leads to an increasing depletion of heavy isotopes in the residual air moisture as it moves towards the centre of the continent. This isotopic depletion is partly compensated, particularly in summer, by evapotranspiration, which is assumed to transfer soil water into the atmosphere without isotope fractionation. The model estimates are based on horizontal water vapour flux data, varying seasonally between 88 and 130 kg m -1 s -1 for the Atlantic coast region, and on the monthly precipitation, evapotranspiration and surface air temperature data available for various locations in Europe. Both continental and seasonal temperature effects observed in the stable isotope composition of European precipitation are fairly well reproduced by the model. The calculations show that the isotopic composition of local precipitation is primarily controlled by regional scale processes, i.e. by the water vapour transport patterns into the continent, and by the average precipitation-evapotranspiration history of the air masses precipitating at a given place. Local parameters such as the surface and/or cloud base temperature or the amount of precipitation modify the isotope ratios only slightly. Implications of the model predictions for the interpretation of stable isotope ratios in earlier periods as they are preserved in ice cores and in groundwater are also discussed. (Auth.)

Ion beam production and study of radioactive isotopes with the laser ion source at ISOLDE

Science.gov (United States)

Fedosseev, Valentin; Chrysalidis, Katerina; Day Goodacre, Thomas; Marsh, Bruce; Rothe, Sebastian; Seiffert, Christoph; Wendt, Klaus

2017-08-01

At ISOLDE the majority of radioactive ion beams are produced using the resonance ionization laser ion source (RILIS). This ion source is based on resonant excitation of atomic transitions by wavelength tunable laser radiation. Since its installation at the ISOLDE facility in 1994, the RILIS laser setup has been developed into a versatile remotely operated laser system comprising state-of-the-art solid state and dye lasers capable of generating multiple high quality laser beams at any wavelength in the range of 210-950 nm. A continuous programme of atomic ionization scheme development at CERN and at other laboratories has gradually increased the number of RILIS-ionized elements. At present, isotopes of 40 different elements have been selectively laser-ionized by the ISOLDE RILIS. Studies related to the optimization of the laser-atom interaction environment have yielded new laser ion source types: the laser ion source and trap and the versatile arc discharge and laser ion source. Depending on the specific experimental requirements for beam purity or versatility to switch between different ionization mechanisms, these may offer a favourable alternative to the standard hot metal cavity configuration. In addition to its main purpose of ion beam production, the RILIS is used for laser spectroscopy of radioisotopes. In an ongoing experimental campaign the isotope shifts and hyperfine structure of long isotopic chains have been measured by the extremely sensitive in-source laser spectroscopy method. The studies performed in the lead region were focused on nuclear deformation and shape coexistence effects around the closed proton shell Z = 82. The paper describes the functional principles of the RILIS, the current status of the laser system and demonstrated capabilities for the production of different ion beams including the high-resolution studies of short-lived isotopes and other applications of RILIS lasers for ISOLDE experiments. This article belongs to the Focus on

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

International Nuclear Information System (INIS)

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

1995-01-01

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

Hydrochemical and isotope study of Lake Titicaca

International Nuclear Information System (INIS)

Gonfiantini, R.; Cioni, R.; Paredes, M.

2002-01-01

The chemical and isotopic compositions of Lake Titicaca and its inflow waters (precipitation, tributaries, groundwater) were determined with the aim of establishing the lake chemical and isotope balance. The three main regions of the lake, i.e. the Lago Mayor, the eastern and the western basins of Lago Menor, connected in cascade, show significant chemical and isotopic differences. Chloride and sodium balance indicates that an average of about 92% of the inflow water evaporates, and the remaining 8 % is lost through Rio Desaguadero and infiltration. The balance of each basin is also obtained, including the inter-basin fluxes. The stable isotope balance in not possible because no data are available on the mean atmospheric vapour isotopic composition. However, this was tentatively computed using the fluxes obtained from chemistry. The vapour δ-values are slightly more negative than those of rainfall. Tritium, noble gases and chloro-fluoro-carbons in vertical profiles show that the lake is vertically well mixed and there is no water segregation at depth. (author)

Sampling system of atmospheric water vapour for analysis of the γ sub(D) relationship

International Nuclear Information System (INIS)

Foloni, L.L.; Villa Nova, N.A.; Salati, E.

1979-01-01

The development of a system to water vapour air, for natural isotopic composition analysis of hydrogen is presented. The system uses molecular sieve, type '4A', without cooling agent and permits the choice of a sampling time, variyng from a few minutes to many hours, through the control of the admission of vapour flux. The system has good performance in field conditions, with errors of the order of + -3,0 0 /00 in the γ sub(D)( 0 /00) measurements [pt

The isotopic composition of precipitation from a winter storm – a case study with the limited-area model COSMOiso

Directory of Open Access Journals (Sweden)

K. Yoshimura

2012-02-01

Full Text Available Stable water isotopes are valuable tracers of the atmospheric water cycle, and potentially provide useful information also on weather-related processes. In order to further explore this potential, the water isotopes H218O and HDO are incorporated into the limited-area model COSMO. In a first case study, the new COSMOiso model is used for simulating a winter storm event in January 1986 over the eastern United States associated with intense frontal precipitation. The modelled isotope ratios in precipitation and water vapour are compared to spatially distributed δ18O observations. COSMOiso very accurately reproduces the statistical distribution of δ18O in precipitation, and also the synoptic-scale spatial pattern and temporal evolution agree well with the measurements. Perpendicular to the front that triggers most of the rainfall during the event, the model simulates a gradient in the isotopic composition of the precipitation, with high δ18O values in the warm air and lower values in the cold sector behind the front. This spatial pattern is created through an interplay of large scale air mass advection, removal of heavy isotopes by precipitation at the front and microphysical interactions between rain drops and water vapour beneath the cloud base. This investigation illustrates the usefulness of high resolution, event-based model simulations for understanding the complex processes that cause synoptic-scale variability of the isotopic composition of atmospheric waters. In future research, this will be particularly beneficial in combination with laser spectrometric isotope observations with high temporal resolution.

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

Energy Technology Data Exchange (ETDEWEB)

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

2011-09-01

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

LACAN Code for global simulation of SILVA laser isotope separation process

International Nuclear Information System (INIS)

Quaegebeur, J.P.; Goldstein, S.

1991-01-01

Functions used for the definition of a SILVA separator require quite a lot of dimensional and operating parameters. Sizing a laser isotope separation plant needs the determination of these parameters for optimization. In the LACAN simulation code, each elementary physical process is described by simplified models. An example is given for a uranium isotope separation plant whose separation power is optimized with 6 parameters [fr

Separation and enrichment of isotopes using laser photochemistry - fundamentals and prospectives

International Nuclear Information System (INIS)

Guesten, H.

1978-01-01

Basic knowledge is summed up on isotope separation by laser photochemistry. The principal prerequisites are explained of the application of atomic and molecular spectroscopy for this purpose. Practical examples are given of isotope separation of uranium, nitrogen, chlorine, carbon, sulfur, and molybdenum showing the application of two basic techniques, i.e., of gradual atom photoionization or gradual molecule photodissociation and of selective photochemical reactions. (L.K.)

Optical isotope shifts of sup(80,82)Sr from coincidence laser spectroscopy

International Nuclear Information System (INIS)

Eastham, D.A.; Walker, P.M.; Smith, J.R.H.; Griffith, J.A.R.; Evans, D.E.; Wells, S.A.; Fawcett, M.J.; Grant, I.S.

1986-01-01

The isotope shifts of radioactive sup(80,82)Sr have been measured by a new, ultrasensitive, laser fluorescence technique. The results have been used to calculate changes in nuclear charge radii. The values, together with those of nearby stable isotopes, are discussed in terms of changes in the static and dynamic nuclear deformations. (author)

The present state of laser isotope separation of uranium

International Nuclear Information System (INIS)

Tashiro, Hideo; Nemoto, Koshichi.

1994-01-01

As the methods of uranium enrichment, gas diffusion method and centrifugal separation method in which power consumption is less and the cost is low have been carried out. On the other hand, as the future technology, the research and development of laser isotope separation technology have been carried out. There are the atomic laser separation process in which the laser beam of visible light is irradiated to atomic state uranium and the molecular laser separation process in which far infrared laser beam is irradiated to uranium hexafluoride molecules. The atomic process is divided into three steps, that is, the processes of uranium evaporation, the reaction of uranium with laser beam and the recovery of enriched uranium. The principle of the laser separation is explained. The state of development of laser equipment and separation equipment is reported. The principle and the present state of development of the molecular separation process which consists of the cooling of UF 6 gas, the generation of high power 16 μm laser pulses and the collection of the reaction product are explained. The present state of both processes in foreign countries is reported. (K.I.)

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.

Direct isotope ratio measurement of uranium metal by emission spectrometry on a laser-produced plasma

International Nuclear Information System (INIS)

Pietsch, W.; Petit, A.; Briand, A.

1995-01-01

The method of Optical Emission Spectrometry on a Laser-Produced Plasma (OES/LPP) at reduced pressure has been studied for the determination of the uranium isotope ratio ( 235 U/ 238 U). Spectral profiles of the investigated transition U-II 424.437 nm show the possibility to obtain an isotopic spectral resolution in a laser-produced plasma under exactly defined experimental conditions. Spectroscopic data and results are presented. (author)

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)

Isotopic analysis of a single Pb particle by using laser ablation TOF-MS

Energy Technology Data Exchange (ETDEWEB)

Choi, I. H.; Yoo, H. S. [Chungbuk National Univ., Cheongju (Korea, Republic of); Song, K. S. [KAERI, Daejeon (Korea, Republic of)

2008-11-15

A laser ablation can be applied to a direct isotopic analysis of solid samples due to the following advantages. Because a laser ablation is a very powerful ionization source, an additional ionization source is not required and an one step vaporization and ionization of samples is possible. Due to the small size of a laser beam, an analysis of a local trace can be applied. Also, the contamination or loss of samples is reduced because there is no need for a sample preparation process. In this study, Pb particles with a size of∼150μm were analyzed by LA TOF MS and a second harmonic of the Nd:YAG laser, 532nm, was used for the laser ablation. First, the ion signal of Pb was measured depending on the matrices. For loading a Pb particle, a silicon wafer, cotton textile, and Ta metal plate were used as a basic plate. As a result, the silicon wafer plate was identified to be the best matrix for the analysis of Pb with a good resolution and its measured isotopic ratios reasonably agree with the natural abundance within 5%. The figure shows a mass spectrum of Pb onto a silicon wafer. In applying the resonance laser ablation, the detection sensitivity was increased by more than 10 times. In the experiment regarding the cotton textile, the mass resolution of Pb was more than 500 which was enough to measure the isotopes, and it is applicable to real swipe samples in various fields such as environmental analysis, industry, and nuclear forensic.

Iron isotope composition of particles produced by UV-femtosecond laser ablation of natural oxides, sulfides, and carbonates.

Science.gov (United States)

d'Abzac, Francois-Xavier; Beard, Brian L; Czaja, Andrew D; Konishi, Hiromi; Schauer, James J; Johnson, Clark M

2013-12-17

The need for femtosecond laser ablation (fs-LA) systems coupled to MC-ICP-MS to accurately perform in situ stable isotope analyses remains an open question, because of the lack of knowledge concerning ablation-related isotopic fractionation in this regime. We report the first iron isotope analysis of size-resolved, laser-induced particles of natural magnetite, siderite, pyrrhotite, and pyrite, collected through cascade impaction, followed by analysis by solution nebulization MC-ICP-MS, as well as imaging using electron microscopy. Iron mass distributions are independent of mineralogy, and particle morphology includes both spheres and agglomerates for all ablated phases. X-ray spectroscopy shows elemental fractionation in siderite (C-rich agglomerates) and pyrrhotite/pyrite (S-rich spheres). We find an increase in (56)Fe/(54)Fe ratios of +2‰, +1.2‰, and +0.8‰ with increasing particle size for magnetite, siderite, and pyrrhotite, respectively. Fe isotope differences in size-sorted aerosols from pyrite ablation are not analytically resolvable. Experimental data are discussed using models of particles generation by Hergenröder and elemental/isotopic fractionation by Richter. We interpret the isotopic fractionation to be related to the iron condensation time scale, dependent on its saturation in the gas phase, as a function of mineral composition. Despite the isotopic variations across aerosol size fractions, total aerosol composition, as calculated from mass balance, confirms that fs-LA produces a stoichiometric sampling in terms of isotopic composition. Specifically, both elemental and isotopic fractionation are produced by particle generation processes and not by femtosecond laser-matter interactions. These results provide critical insights into the analytical requirements for laser-ablation-based stable isotope measurements of high-precision and accuracy in geological samples, including the importance of quantitative aerosol transport to the ICP.

Contribution to the future prospects of laser separation of uranium isotopes

International Nuclear Information System (INIS)

Becker, F.S.

1981-04-01

In the past several years, the selective absorption of laser light has been considered as an alternative to the large-scale technical uranium isotope separation schemes based on the mass-dependence of the diffusion velocity or the centrifugal force. An analysis of the published results appears to show that two-frequency multiphoton dissociation is especially attractive for a technical process. To clarify the prospects of such a scheme, studies of the isotope selectivity of the multiphoton dissociation of statically cooled UF 6 with two infrared frequencies, one of which is tunable in the region of the UF 6 ν(3) band at 16 μm, are proposed. The construction and testing of a high-power laser, tunable in the 16 μm region, based on the frequency conversion of 10 μm CO 2 radiation by means of stimulated rotational Raman scattering in para-hydrogen, is described. Pulse-widths of about 80 nsec and pulse energies of about one half J are obtained which ought to permit, in combination with a CO 2 laser, the multiphoton dissociation of UF 6 without focussing. By means of UV-light experiments it is shown that optical dissociation of UF 6 can be obtained even in the presence of high F-concentrations, thus permitting a high dissociation yield without a F-scavenger which could negatively affect the isotope selectivity. (orig./HP) [de

The changing face of enrichment

International Nuclear Information System (INIS)

Dunckel, E.

1981-01-01

The AIS techniques considered are atomic vapour laser isotope separation, molecular laser isotope separation and plasma separation. The future of the AIS technique and their advantages over the gas centrifuge method are discussed in terms of economics, power consideration, and possible enrichment contracts. (U.K.)

Cr2O3 thin films grown at room temperature by low pressure laser chemical vapour deposition

International Nuclear Information System (INIS)

Sousa, P.M.; Silvestre, A.J.; Conde, O.

2011-01-01

Chromia (Cr 2 O 3 ) has been extensively explored for the purpose of developing widespread industrial applications, owing to the convergence of a variety of mechanical, physical and chemical properties in one single oxide material. Various methods have been used for large area synthesis of Cr 2 O 3 films. However, for selective area growth and growth on thermally sensitive materials, laser-assisted chemical vapour deposition (LCVD) can be applied advantageously. Here we report on the growth of single layers of pure Cr 2 O 3 onto sapphire substrates at room temperature by low pressure photolytic LCVD, using UV laser radiation and Cr(CO) 6 as chromium precursor. The feasibility of the LCVD technique to access selective area deposition of chromia thin films is demonstrated. Best results were obtained for a laser fluence of 120 mJ cm -2 and a partial pressure ratio of O 2 to Cr(CO) 6 of 1.0. Samples grown with these experimental parameters are polycrystalline and their microstructure is characterised by a high density of particles whose size follows a lognormal distribution. Deposition rates of 0.1 nm s -1 and mean particle sizes of 1.85 μm were measured for these films.

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).

Measurement of isotope shift of recycled uranium by laser induced fluorescence spectroscopy

International Nuclear Information System (INIS)

Oba, Masaki; Wakaida, Ikuo; Akaoka, Katsuaki; Miyabe, Masabumi

1999-07-01

Isotope shift of the recycled uranium atoms including the 236 U was measured by laser induced fluorescence method. Eight even levels at 2 eV and three odd levels at 4 eV were measured with isotope shifts among 238 U, 236 U and 235 U obtained. As for the measurement of the 4 eV levels, the Doppler free two photon absorption method was used, and the hyperfine structure of the 235 U was analyzed simultaneously. The isotope shift of 234 U was also observed in the three transition. (J.P.N.)

Laser fluorescence on radio-active isotopes produced in very low yield

International Nuclear Information System (INIS)

Dancy, D.E.; Billowes, J.; Grant, I.S.; Evans, D.E.; Griffith, J.A.R.; Wells, S.A.; Eastham, D.A.; Groves, J.; Smith, J.R.H.; Tolfree, D.W.L.; Walker, P.M.

1990-01-01

Fast particle-photon coincidence techniques, developed at Daresbury with strontium isotopes, allow ultra-sensitive laser fluorescence spectroscopy of beams of radio-active isotopes which can only be produced in very low yields. The technique has now been applied to neutron-deficient barium isotopes down to 120 Ba. From measured hyperfine splitting and isotope shifts, nuclear moments and changes in mean square radii have been determined. The work has revealed an abrupt increase in the mean square radius for 121 Ba large enough to disrupt the systematic staggering of nuclear size seen for the series. In a recent experiment an isomeric state of 127 Ba with a half-life of about 2 seconds has been produced in a very low yield; nevertheless we have succeeded in obtaining a fluorescence spectrum. (orig.)

Isotope dilution ICP-MS with laser-assisted sample introduction for direct determination of sulfur in petroleum products.

Science.gov (United States)

Boulyga, Sergei F; Heilmann, Jens; Heumann, Klaus G

2005-08-01

Inductively coupled plasma isotope dilution mass spectrometry (ICP-IDMS) with direct laser-assisted introduction of isotope-diluted samples into the plasma, using a laser ablation system with high ablation rates, was developed for accurate sulfur determinations in different petroleum products such as 'sulfur-free' premium gasoline, diesel fuel, and heating oil. Two certified gas oil reference materials were analyzed for method validation. Two different 34S-enriched spike compounds, namely, elementary sulfur dissolved in xylene and dibenzothiophene in hexane, were synthesized and tested for their usefulness in this isotope dilution technique. The isotope-diluted sample was adsorbed on a filter-paper-like material, which was fixed in a special holder for irradiation by the laser beam. Under these conditions no time-dependent spike/analyte fractionation was only observed for the dibenzothiophene spike during the laser ablation process, which means that the measured 34S/32S isotope ratio of the isotope-diluted sample remained constant-a necessary precondition for accurate results with the isotope dilution technique. A comparison of LA-ICP-IDMS results with the certified values of the gas oil reference materials and with results obtained from ICP-IDMS analyses with wet sample digestion demonstrated the accuracy of the new LA-ICP-IDMS method in the concentration range of 9.2 microg g(-1) ('sulfur-free' premium gasoline) to 10.4 mg g(-1) (gas oil reference material BCR 107). The detection limit for sulfur by LA-ICP-IDMS is 0.04 microg g(-1) and the analysis time is only about 10 min, which therefore also qualifies this method for accurate determinations of low sulfur contents in petroleum products on a routine level.

Study on improvement of laser system performance for uranium isotope separation

International Nuclear Information System (INIS)

Fujii, Takashi

1998-01-01

For the purpose of reducing the cost of Atomic Vapor Laser Isotope Separation (AVLIS), I developed the following laser technologies. (1) I developed a solid-state pulse power supply, of which output power was the almost highest value achieved for a copper vapor laser in 1989, using a GTO as a switching device and a magnetic pulse compression circuit. (2) I developed a new technique of tuning the laser wavelength to an atomic absorption band using high-speed wavelength shift of a laser diode by direct modulation. (3) I developed a new technique of stabilizing the laser wavelength at an absorption band of a target atom, by locking the sideband generated by phase modulation of a laser beam to a Fabry-Perot interferometer. (4) I proposed the Cr 4+ -doped forsterite laser system as an all solid-state laser system for the AVLIS. I obtained the slope efficiency of 25%, which was the highest value achieved in the case of pulse operation of the Cr 4+ -doped forsterite laser in 1995, using the forsterite with high Cr 4+ -ion concentration. (author)

Tunable lasers in isotope separation, a colorful view of a dye chemist

International Nuclear Information System (INIS)

Hammond, P.R.

1976-01-01

Some of the problems to be encountered in the large-scale use of dye lasers in an isotope separation plant are discussed. Why should dye lasers be employed. How can dye conversion efficiency be optimized. How can dye photochemical decomposition and hence running costs be minimized and how serious is this effect anyway. What are toxicity problems with the dye. These and similar issues are examined

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.

Archival processes of the water stable isotope signal in East Antarctic ice cores

Science.gov (United States)

Casado, Mathieu; Landais, Amaelle; Picard, Ghislain; Münch, Thomas; Laepple, Thomas; Stenni, Barbara; Dreossi, Giuliano; Ekaykin, Alexey; Arnaud, Laurent; Genthon, Christophe; Touzeau, Alexandra; Masson-Delmotte, Valerie; Jouzel, Jean

2018-05-01

The oldest ice core records are obtained from the East Antarctic Plateau. Water isotopes are key proxies to reconstructing past climatic conditions over the ice sheet and at the evaporation source. The accuracy of climate reconstructions depends on knowledge of all processes affecting water vapour, precipitation and snow isotopic compositions. Fractionation processes are well understood and can be integrated in trajectory-based Rayleigh distillation and isotope-enabled climate models. However, a quantitative understanding of processes potentially altering snow isotopic composition after deposition is still missing. In low-accumulation sites, such as those found in East Antarctica, these poorly constrained processes are likely to play a significant role and limit the interpretability of an ice core's isotopic composition. By combining observations of isotopic composition in vapour, precipitation, surface snow and buried snow from Dome C, a deep ice core site on the East Antarctic Plateau, we found indications of a seasonal impact of metamorphism on the surface snow isotopic signal when compared to the initial precipitation. Particularly in summer, exchanges of water molecules between vapour and snow are driven by the diurnal sublimation-condensation cycles. Overall, we observe in between precipitation events modification of the surface snow isotopic composition. Using high-resolution water isotopic composition profiles from snow pits at five Antarctic sites with different accumulation rates, we identified common patterns which cannot be attributed to the seasonal variability of precipitation. These differences in the precipitation, surface snow and buried snow isotopic composition provide evidence of post-deposition processes affecting ice core records in low-accumulation areas.

Model for the isotopic fractionation of water in the Amazon basin

International Nuclear Information System (INIS)

Dall'Olio, A.; Azevedo, C.T. de

1979-01-01

Two models on the isotopic fractionation of water are presented. In the first model. It is assumed that the only source of water vapour for the Amazon region is the Atlantic Ocean, introduced by the predominant easterly winds. The second model contains the assumption that the forest also serves as a source of water vapour contributing an equal volume of water to the regional rains as the vapour of oceanic origin. (Author) [pt

A chemically selective laser ion source for the on-line isotope separation

International Nuclear Information System (INIS)

Scheerer, F.

1993-03-01

In this thesis a laser ion source is presented. In a hot chamber the atoms of the elements to be studied are resonantly by light of pulsed dye lasers, which are pumped by pulsed copper-vapor lasers with extremely high pulse repetition rate (ν rep ∼ 10 kHz), stepwise excited and ionized. By the storage of the atoms in a hot chamber and the high pulse repetition rate of the copper-vapor lasers beyond the required high efficiency (ε ∼ 10%) can be reached. First preparing measurements were performed at the off-line separator at CERN with the rare earth elements ytterbium and thulium. Starting from the results of these measurements further tests of the laser ion source were performed at the on-line separator with in a thick tantalum target produced neutron-deficient ytterbium isotopes. Under application of a time-of-flight mass spectrometer in Mainz an efficient excitation scheme on the resonance ionization of tin was found. This excitation scheme is condition for an experiment at the GSI for the production of the extremely neutron-deficient, short-lived nucleus 102 Sn. In the summer 1993 is as first application of the newly developed laser ion source at the PSB-ISOLDE at CERN an astrophysically relevant experiment for the nuclear spectroscopy of the neutron-rich silver isotopes 124-129 Ag is planned. This experiment can because of the lacking selectivity of conventional ion sources only be performed by means of the here presented laser ion source. The laser ion source shall at the PSB-ISOLDE 1993 also be applied for the selective ionization of manganese. (orig./HSI) [de

Isotopes in the Arctic atmospheric water cycle

Science.gov (United States)

Bonne, Jean-Louis; Werner, Martin; Meyer, Hanno; Kipfstuhl, Sepp; Rabe, Benjamin; Behrens, Melanie; Schönicke, Lutz; Steen Larsen, Hans Christian; Masson-Delmotte, Valérie

2016-04-01

The ISO-ARC project aims at documenting the Arctic atmospheric hydrological cycle, by assessing the imprint of the marine boundary conditions (e.g. temperature variations, circulation changes, or meltwater input) to the isotopic composition of the atmospheric water cycle (H218O and HDO) with a focus on North Atlantic and Arctic oceans. For this purpose, two continuous monitoring water vapour stable isotopes cavity ring-down spectrometers have been installed in July 2015: on-board the Polarstern research vessel and in the Siberian Lena delta Samoylov research station (N 72° 22', E 126° 29'). The Polarstern measurements cover the summer 2015 Arctic campaign from July to mid-October, including six weeks in the Fram Strait region in July- August, followed by a campaign reaching the North Pole and a transect from the Norwegian Sea to the North Sea. These vapour observations are completed by water isotopic measurements in samples from the surface ocean water for Polarstern and from precipitation in Samoylov and Tiksi (120 km south-east of the station). A custom-made designed automatic calibration system has been implemented in a comparable manner for both vapour instruments, based on the injection of different liquid water standards, which are completely vaporised in dry air at high temperature. Subsequent humidity level can be adjusted from 2000 to at least 30000 ppm. For a better resilience, an independent calibration system has been added on the Samoylov instrument, allowing measurements of one standard at humidity levels ranging from 2000 to 15000 ppm: dry air is introduced in a tank containing a large amount of liquid water standard, undergoing evaporation under a controlled environment. The measurement protocol includes an automatic calibration every 25 hours. First instrument characterisation experiments depict a significant isotope-humidity effect at low humidity, dependant on the isotopic composition of the standard. For ambient air, our first isotope

Laser-spectroscopic nuclear-structure studies on radioactive silver and indium isotopes

International Nuclear Information System (INIS)

Dinger, U.

1988-05-01

Neutron-deficient silver and neutron-rich indium isotopes were studied by collinear laser spectroscopy. The neutron-deficient nuclei 101 , 103 , 104 , 105 , 105m , 106m Ag were produced as evaporation-residual nuclei in heavy-ion fusion reactions at the mass separator of the GSI in Darmstadt. The fourteen studied indium isotopes and isomers with even mass number in the range 112-126 In were produced by 600-MeV-proton induced fission of a uranium carbide target at the ISOLDE separator in Geneva. The mass-separated ion beam was subsequently deviated electrostatically, neutralized in a sodium vapor and superposed with a c w dye laser. A photon counting system detected the resonance fluorescence of the induced transitions. The hyperfine structure and the isotope shift of the 4d 9 5s 2 2 D 5/2 → 4d 10 6p 2 P 3/2 transition (λ=547.7 nm) in silver and the 5p 2 P 1/2,3/2 → 6s 2 s 1/2 transition (λ=410 respectively 451 nm) in indium were measured. While in indium for the analysis of the data earlier work could be referred to, in silver a detailed analysis of the isotope shift and hyperfine structure was performed by means of ab initio calculations and semi-empirical procedures. Thereby the configuration interactions were especially considered. The nuclear moments were discussed in the framework of existing nuclear models regarding nuclear-spectroscopic informations. (orig./HSI) [de

Isotope dilution ICP-MS with laser-assisted sample introduction for direct determination of sulfur in petroleum products

Energy Technology Data Exchange (ETDEWEB)

Boulyga, Sergei F.; Heilmann, Jens; Heumann, Klaus G. [Johannes Gutenberg-University Mainz (Germany). Institute of Inorganic Chemistry and Analytical Chemistry

2005-08-01

Inductively coupled plasma isotope dilution mass spectrometry (ICP-IDMS) with direct laser-assisted introduction of isotope-diluted samples into the plasma, using a laser ablation system with high ablation rates, was developed for accurate sulfur determinations in different petroleum products such as 'sulfur-free' premium gasoline, diesel fuel, and heating oil. Two certified gas oil reference materials were analyzed for method validation. Two different {sup 34}S-enriched spike compounds, namely, elementary sulfur dissolved in xylene and dibenzothiophene in hexane, were synthesized and tested for their usefulness in this isotope dilution technique. The isotope-diluted sample was adsorbed on a filter-paper-like material, which was fixed in a special holder for irradiation by the laser beam. Under these conditions no time-dependent spike/analyte fractionation was only observed for the dibenzothiophene spike during the laser ablation process, which means that the measured {sup 34}S/{sup 32}S isotope ratio of the isotope-diluted sample remained constant - a necessary precondition for accurate results with the isotope dilution technique. A comparison of LA-ICP-IDMS results with the certified values of the gas oil reference materials and with results obtained from ICP-IDMS analyses with wet sample digestion demonstrated the accuracy of the new LA-ICP-IDMS method in the concentration range of 9.2 {mu}g g{sup -1} ('sulfur-free' premium gasoline) to 10.4 mg g{sup -1} (gas oil reference material BCR 107). The detection limit for sulfur by LA-ICP-IDMS is 0.04 {mu}g g{sup -1} and the analysis time is only about 10 min, which therefore also qualifies this method for accurate determinations of low sulfur contents in petroleum products on a routine level. (orig.)

Chemistry, spectroscopy and isotope separation of zirconium and its compounds as revealed by laser diagnostics of laser produced metal beams

International Nuclear Information System (INIS)

Hackett, P.A.; Humphries, M.; Rayner, D.M.; Bourne, O.L.; Mitchell, A.

1986-01-01

Recent work from the author's laboratory on zirconium beams is reviewed. Zirconium metal beams have been produced by laser vaporization of solid zirconium targets coupled with supersonic expansion of helium gas. The resultant supersonic metal beam is shown to present an ideal environment for various spectroscopic techniques. The state distribution of zirconium atoms in the beam is obtained from low resolution laser induced fluorescence (LIF) studies. High resolution LIF studies give information on the hyperfine splitting in the ground state of the zirconium-91 isotope. Information on the hyperfine splitting in the excited state is obtained from quantum beat spectroscopy. Low resolution 2 color multiphoton ionization spectroscopy using a XeCl laser allows isotope separation of all isotopes of zirconium. These metal beams are highly reactive and can be used to produce novel chemical species. The results of two studies in which a reactant is added to the expansion gas are reported here. Zirconium oxide (ZrO), a molecule observed in the emission spectra of cool stars and in laboratory studies at high temperatures, is produced in a low temperature, collision free environment by adding small quantities of oxygen to the expansion gas. Zirconium fluoride (ZrF), a molecule previously unobserved, is produced by the addition of small quantities of CF/sub 4/

Diode laser operating on an atomic transition limited by an isotope ⁸⁷Rb Faraday filter at 780 nm.

Science.gov (United States)

Tao, Zhiming; Hong, Yelong; Luo, Bin; Chen, Jingbiao; Guo, Hong

2015-09-15

We demonstrate an extended cavity Faraday laser system using an antireflection-coated laser diode as the gain medium and the isotope (87)Rb Faraday anomalous dispersion optical filter (FADOF) as the frequency selective device. Using this method, the laser wavelength works stably at the highest transmission peak of the isotope (87)Rb FADOF over the laser diode current from 55 to 140 mA and the temperature from 15°C to 35°C. Neither the current nor the temperature of the laser diode has significant influence on the output frequency. Compared with previous extended cavity laser systems operating at frequencies irrelevant to spectacular atomic transition lines, the laser system realized here provides a stable laser source with the frequency operating on atomic transitions for many practical applications.

The instability of molecules in laser field and isotope separation

International Nuclear Information System (INIS)

Li, K.

1981-01-01

In the present paper the nonlinear differential equation describing the selective decomposition of a molecule as an unimolecular reaction has be deduced from the usual time dependent semi-classical Schroedinger equation. The selective conditions for the instability of a molecule are discussed. The thresholds of the required laser intensities for ICl and HCl diatomic molecules are estimated respectively, where on type of isotope molecules ought to be decomposed for hundred per cent in a laser pulse for different pulse widths. And possibly selective decomposition of the molecule without permanent dipole moment by Raman process is also discussed briefly. (orig.)

Preferential flow pathways revealed by field based stable isotope analysis of CO2 by mid-infrared laser spectroscopy

Science.gov (United States)

van Geldern, Robert; Nowak, Martin; Zimmer, Martin; Szizybalski, Alexandra; Myrttinen, Anssi; Barth, Johannes A. C.; Jost, Hj

2016-04-01

A newly developed and commercially available isotope ratio laser spectrometer for CO2 analyses has been tested during a 10-day field monitoring campaign at the Ketzin pilot site for CO2 storage in northern Germany. The laser instrument is based on tunable laser direct absorption in the mid-infrared. The instrument recorded a continuous 10-day carbon stable isotope data set with 30 minutes resolution directly on-site in a field-based laboratory container during a tracer experiment. To test the instruments performance and accuracy the monitoring campaign was accompanied by daily CO2 sampling for laboratory analyses with isotope ratio mass spectrometry (IRMS). The carbon stable isotope ratios measured by conventional IRMS technique and by the new mid-infrared laser spectrometer agree remarkably well within 2σ analytical precision (<0.3 ‰). This proves the capability of the new mid-infrared direct absorption technique to measure high precision and accurate real-time table isotope data directly in the field. The injected CO2 tracer had a distinct δ13C value that was largely different from the reservoir background value. The laser spectroscopy data revealed a prior to this study unknown, intensive dynamic with fast changing δ13C values. The arrival pattern of the tracer suggest that the observed fluctuations were probably caused by migration along separate and distinct preferential flow paths between injection well and observation well. The new technique might contribute to a better tracing of the migration of the underground CO2 plume and help to ensure the long-term integrity of the reservoir.

In Situ Carbon Isotope Analysis by Laser Ablation MC-ICP-MS.

Science.gov (United States)

Chen, Wei; Lu, Jue; Jiang, Shao-Yong; Zhao, Kui-Dong; Duan, Deng-Fei

2017-12-19

Carbon isotopes have been widely used in tracing a wide variety of geological and environmental processes. The carbon isotope composition of bulk rocks and minerals was conventionally analyzed by isotope ratio mass spectrometry (IRMS), and, more recently, secondary ionization mass spectrometry (SIMS) has been widely used to determine carbon isotope composition of carbon-bearing solid materials with good spatial resolution. Here, we present a new method that couples a RESOlution S155 193 nm laser ablation system with a Nu Plasma II MC-ICP-MS, with the aim of measuring carbon isotopes in situ in carbonate minerals (i.e., calcite and aragonite). Under routine operating conditions for δ 13 C analysis, instrumental bias generally drifts by 0.8‰-2.0‰ in a typical analytical session of 2-3 h. Using a magmatic calcite as the standard, the carbon isotopic composition was determined for a suite of calcite samples with δ 13 C values in the range of -6.94‰ to 1.48‰. The obtained δ 13 C data are comparable to IRMS values. The combined standard uncertainty for magmatic calcite is ICP-MS can serve as an appropriate method to analyze carbon isotopes of carbonate minerals in situ.

High-power copper vapour lasers and applications

Energy Technology Data Exchange (ETDEWEB)

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

1995-08-01

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

IR laser enrichment of light elements isotopes - challenges and prospects

International Nuclear Information System (INIS)

Parthasarathy, V.

2002-01-01

Full text: Infra-red multiple photon dissociation (IR MPD) of poly-atomic molecules has made considerable progress since its discovery in the early seventies. Since the process was found to be isotopically selective; the possibility of laser isotope separation (LIS) created a lot of initial excitement. While the early investigations were concerned with the fundamental dynamics and potential applications of the phenomenon, serious efforts for the isotope enrichment process have been made only during the last decade. These efforts focussed on aspects to improve both the enrichment factor and throughput in various systems. Many research groups have achieved a good measure of success for scaling up the process for various light elements like carbon, oxygen, silicon and sulphur whose isotopes are quite important in medicine and technology. Significant results have been reported especially for the separation of carbon isotopes wherein macroscopic operating scales have been already realised. This talk will give-a summary of our work carried out at BARC and highlight the current efforts for scaling up the process for carbon isotopes enrichment. This would include the design aspects of a large photochemical reactor with multi-pass, refocusing optics for efficient photon utilization. It will also cover the development of a cryogenic distillation set up and a preparative gas chromatograph for a large scale separation and collection of the isotopically enriched photoproduct in the post irradiation stage. Based on the experience gained and infra structure developed, plans are afoot to separate oxygen and sulphur isotopes using a similar approach

Surface polish of PLA parts in FDM using dichloromethane vapour

Directory of Open Access Journals (Sweden)

Jin Yifan

2017-01-01

Full Text Available Fused deposition modelling has become one of the most diffused rapid prototyping techniques, which is widely used to fabricate prototypes. However, further application of this technology is severely limited by poor surface roughness. Thus it is necessary to adopt some operations to improve surface quality. Chemical finishing is typically employed to finish parts in fused deposition modelling (FDM. The purpose of this paper is to decrease the surface roughness for polylactic acid (PLA parts in FDM. The chemical reaction mechanism during the treating process is analysed. Then NaOH solution and dichloromethane vapour are used to treat FDM specimens respectively. A 3D laser microscope has been applied to assess the effects in terms of surface topography and roughness. The experimental results show that treatment using dichloromethane vapour performs much better than NaOH solution. Compared with the untreated group, surface roughness obtained through vapour treatment decreases by 88 per cent. This research has been conducted to provide a better method to treat PLA parts using chemical reagents.

Determination of nuclear spins of short-lived isotopes by laser induced fluorescence

International Nuclear Information System (INIS)

Buchinger, F.; Dabkiewicz, P.; Kremmling, H.; Kuehl, T.; Mueller, A.C.; Schuessler, H.A.

1980-01-01

The spins of several nuclear ground and isomeric states have been measured for a number of mercury isotopes. The fluorescent light from the 6s6p 3 P 1 state is observed at 2537 Angstroem after excitation with the frequency doubled output of a pulsed dye laser. Four different laser induced fluorescence techniques were tested for their applicability: double resonance, Hanle effect, time delayed integral Hanle beats, and time resolved quantum beats. The sensitivity and selectivity of these models are compared with emphasis on the determination of spins of nuclei far from beta-stability, where short half lives and low production yields restrict the number of available atoms. The experiments were carried out on-line with the ISOLDE isotope separator at CERN at densities as low as 10 6 atoms/cm 3 . Results for the very neutron deficient high spin mercury isomers with half lives of several seconds, but also for the ground states of the abundant low spin stable mercury isotopes, are given as examples. The test measurements determined the nuclear spins of the odd sup(185m-191m)Hg isomers to be I = 13/2. (orig.)

Research and development prospects for the atomic uranium laser isotope separation process. Research report 442

International Nuclear Information System (INIS)

Janes, G.S.; Forsen, H.K.; Levy, R.H.

1977-06-01

Research and development activities are being conducted on many aspects of the atomic uranium laser isotope separation process. Extensive laser spectroscopy studies have been made in order to identify attractive multi-step selective ionization schemes. Using low density (10 10 atoms/cm 3 ) apparatus, the excited state spectra of atomic uranium have been investigated via multiple step laser excitation and photoionization studies using two, three and four pulsed lasers. Observation of the spectra was accomplished by observing the yield of 235 U and 238 U ions as a function of the wavelength, intensities and delays of the various lasers. These data yielded information on the photoexcitation and photoionizatin cross sections, and on the location, J values, lifetimes, isotope shifts and hyperfine structure of the various atomic levels of uranium. Experiments on selective ionization of uranium vapor by multiple step laser excitation followed by ion extraction at 10 13 atoms/cm 3 density have produced 6% enriched 235 U. These indicate that this process is well adapted to produce light water reactor fuel but less suitable for highly enriched material. Application has been made for license for a 1979 experimental facility to provide data for a mid-1980 commercial plant

Carbon and oxygen isotope ratios in wood constituents of Pinus halepensis as indicators of precipitation, temperature and vapour pressure deficit

International Nuclear Information System (INIS)

Ferrio, J.P.; Voltas, J.

2005-01-01

Carbon and oxygen isotope compositions (δ 13 C, δ 18 O) in tree rings have been shown to bear relevant climatic signals. However, little is known about the interrelationship between both isotopes in wood constituents for species from other than relatively wet climates. We hypothesized that in a species adapted to temporary droughts (e.g. Pinus halepensis Mill.) the signal derived from δ 18 O in precipitation would be hidden by the strong variability in leaf transpirative enrichment. To test this assumption, we compared the effect of precipitation, temperature and vapour pressure deficit (VPD) on δ 18 O and δ 13 C along 23 sites covering the ecological range for this species. We extracted the cores from the south side of four to six adult dominant trees per aspect (north/south) within each site. For each aspect and site, fragments of the period 1975-1999 were pooled and milled to a fine powder. To further test the postulated need for cellulose purification in the assessment of climatic information, we studied these relationships in whole and extracted wood, holocellulose and lignin. In all wood fractions, δ 13 C was related to annual precipitation [r=0.58 (P 18 O only holocellulose showed consistent relationships with climatic data, being strongly significant for VPD [r=0.66 (P 18 O in precipitation, confirming that transpirative enrichment (driven by VPD) dampened the source signal in P. halepensis. The relationships between δ 13 C and δ 18 O were generally poor, regardless of the wood constituent, suggesting that although both variables were somewhat related to transpirative demand, they were relatively independent. This was further confirmed by building stepwise models using both isotopes to predict annual and seasonal precipitation [r 2 = 0.34 (P 2 = 0.15 (P 2 = 0.31 (P< 0.01) to 0.55 (P< 0.001)]. We concluded that, even when partially describing the same climate variables, the information underlying the two isotopes can be regarded as complementary

Cr{sub 2}O{sub 3} thin films grown at room temperature by low pressure laser chemical vapour deposition

Energy Technology Data Exchange (ETDEWEB)

Sousa, P.M. [Universidade de Lisboa, Faculdade de Ciencias, Departamento de Fisica and ICEMS, Campo Grande, Ed. C8, 1749-016 Lisboa (Portugal); Silvestre, A.J., E-mail: asilvestre@deq.isel.ipl.p [Instituto Superior de Engenharia de Lisboa and ICEMS, R. Conselheiro Emidio Navarro 1, 1959-007 Lisboa (Portugal); Conde, O. [Universidade de Lisboa, Faculdade de Ciencias, Departamento de Fisica and ICEMS, Campo Grande, Ed. C8, 1749-016 Lisboa (Portugal)

2011-03-31

Chromia (Cr{sub 2}O{sub 3}) has been extensively explored for the purpose of developing widespread industrial applications, owing to the convergence of a variety of mechanical, physical and chemical properties in one single oxide material. Various methods have been used for large area synthesis of Cr{sub 2}O{sub 3} films. However, for selective area growth and growth on thermally sensitive materials, laser-assisted chemical vapour deposition (LCVD) can be applied advantageously. Here we report on the growth of single layers of pure Cr{sub 2}O{sub 3} onto sapphire substrates at room temperature by low pressure photolytic LCVD, using UV laser radiation and Cr(CO){sub 6} as chromium precursor. The feasibility of the LCVD technique to access selective area deposition of chromia thin films is demonstrated. Best results were obtained for a laser fluence of 120 mJ cm{sup -2} and a partial pressure ratio of O{sub 2} to Cr(CO){sub 6} of 1.0. Samples grown with these experimental parameters are polycrystalline and their microstructure is characterised by a high density of particles whose size follows a lognormal distribution. Deposition rates of 0.1 nm s{sup -1} and mean particle sizes of 1.85 {mu}m were measured for these films.

Excimer laser recrystallization of nanocrystalline-Si films deposited by inductively coupled plasma chemical vapour deposition at 150 deg. C

International Nuclear Information System (INIS)

Park, Joong-Hyun; Han, Sang-Myeon; Park, Sang-Geun; Han, Min-Koo; Shin, Moon-Young

2006-01-01

Polycrystalline silicon thin film transistors (poly-Si TFTs) fabricated at low temperature (under 200 deg. C) have been widely investigated for flexible substrate applications such as a transparent plastic substrate. Unlike the conventional TFT process using glass substrate, the maximum process temperature should be kept less than 200 deg. C in order to avoid thermal damage on flexible substrates. We report the characteristics of nanocrystalline silicon (nc-Si) irradiated by an excimer laser. Nc-Si precursors were deposited on various buffer layers by inductively coupled plasma chemical vapour deposition (ICP-CVD) at 150 deg. C. We employed various buffer layers, such as silicon nitride (SiN X ) and silicon dioxide (SiO 2 ), in order to report recrystallization characteristics in connection with a buffer layer of a different thermal conductivity. The dehydrogenation and recrystallization was performed by step-by-step excimer laser annealing (ELA) (XeCl,λ=308 nm) in order to prevent the explosive release of hydrogen atoms. The grain size of the poly-Si film, which was recrystallized on the various buffer layers, was measured by scanning electron microscopy (SEM) at each laser energy density. The process margin of step-by-step ELA employing the SiN X buffer layer is wider than SiO 2 and the maximum grain size slightly increased

Laser isotope purification of lead for use in semiconductor chip interconnects

International Nuclear Information System (INIS)

Scheibner, K.; Haynam, C.; Worden, E.; Esser, B.

1996-01-01

Lead, used throughout the electronics industries, typically contains small amounts of radioactive 210 Pb (a daughter product of the planets ubiquitous 238 U) whose 210 Po daughter emits an α-particle that is known to cause soft errors in electronic circuits. The 210 Pb is not separable by chemical means. This paper describes the generic Atomic Vapor Laser Isotope Separation (AVLIS) process developed at the Lawrence Livermore National Laboratory (LLNL) over the last 20 years, with particular emphasis on recent efforts to develop the process physics and component technologies required to remove the offending 210 Pb using lasers. We have constructed a developmental facility that includes a process laser development area and a test bed for the vaporizer and ion and product collectors. We will be testing much of the equipment and demonstrating pilot scale AVLIS on a surrogate material later this year. Detection of the very low alpha emission even from commercially available low-alpha lead is challenging. LLNL's detection capabilities will be described. The goal of the development of lead purification technology is to demonstrate the capability in FY97, and to deploy a production machine capable of up to several MT/y of isotopically purified material, possible beginning in FY98

A contribution to the future prospect of uranium laser-isotope separation

International Nuclear Information System (INIS)

Becker, F.S.

1981-01-01

The two-frequency multiphoton-dissociation of UF 6 seems promising, using a high-power laser, which is tunable in the 16 μm spectral region due to the frequency shift of the 10 μm CO 2 -laser radiation, induced by the stimulated rotational Raman effect of para-hydrogen. In the present experiments the isotope selectivity of the multiphoton-dissociation process is studied in order to contribute to the solution of some questions, as for example the influence of high fluorine concentrations on the optical dissociation of UF 6 . (DG) [de

The water vapour self-continuum absorption in the infrared atmospheric windows: new laser measurements near 3.3 and 2.0 µm

Science.gov (United States)

Lechevallier, Loic; Vasilchenko, Semen; Grilli, Roberto; Mondelain, Didier; Romanini, Daniele; Campargue, Alain

2018-04-01

The amplitude, the temperature dependence, and the physical origin of the water vapour absorption continuum are a long-standing issue in molecular spectroscopy with direct impact in atmospheric and planetary sciences. In recent years, we have determined the self-continuum absorption of water vapour at different spectral points of the atmospheric windows at 4.0, 2.1, 1.6, and 1.25 µm, by highly sensitive cavity-enhanced laser techniques. These accurate experimental constraints have been used to adjust the last version (3.2) of the semi-empirical MT_CKD model (Mlawer-Tobin_Clough-Kneizys-Davies), which is widely incorporated in atmospheric radiative-transfer codes. In the present work, the self-continuum cross-sections, CS, are newly determined at 3.3 µm (3007 cm-1) and 2.0 µm (5000 cm-1) by optical-feedback-cavity enhanced absorption spectroscopy (OFCEAS) and cavity ring-down spectroscopy (CRDS), respectively. These new data allow extending the spectral coverage of the 4.0 and 2.1 µm windows, respectively, and testing the recently released 3.2 version of the MT_CKD continuum. By considering high temperature literature data together with our data, the temperature dependence of the self-continuum is also obtained.

Installation for vacuum vapour deposition of nickel, more particularly for manufacturing neutron guides

International Nuclear Information System (INIS)

Samuel, F.

1986-01-01

The present invention proposes an installation for vacuum vapour deposition of Ni of the type including in a vacuum chamber a device for heating a mass of at least one Ni isotope to be evaporated, and a surface to be covered with deposited Ni facing the heater, is claimed, in which the heater includes a ribbon of W conformed in a middle part into a container in which is placed a refractory crucible in which is placed the Ni to be evaporated, and adapted to be connected at two terminal zones to an electrical circuit. The crucible is Al203. The invention finds an application in neutron guide fabrication, more particularly for Ni58 vapour deposition on the surfaces of the neutron guide [fr

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

International Nuclear Information System (INIS)

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

1986-09-01

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

Intercomparison of atmospheric water vapour measurements at a Canadian High Arctic site

Science.gov (United States)

Weaver, Dan; Strong, Kimberly; Schneider, Matthias; Rowe, Penny M.; Sioris, Chris; Walker, Kaley A.; Mariani, Zen; Uttal, Taneil; McElroy, C. Thomas; Vömel, Holger; Spassiani, Alessio; Drummond, James R.

2017-08-01

Water vapour is a critical component of the Earth system. Techniques to acquire and improve measurements of atmospheric water vapour and its isotopes are under active development. This work presents a detailed intercomparison of water vapour total column measurements taken between 2006 and 2014 at a Canadian High Arctic research site (Eureka, Nunavut). Instruments include radiosondes, sun photometers, a microwave radiometer, and emission and solar absorption Fourier transform infrared (FTIR) spectrometers. Close agreement is observed between all combination of datasets, with mean differences ≤ 1.0 kg m-2 and correlation coefficients ≥ 0.98. The one exception in the observed high correlation is the comparison between the microwave radiometer and a radiosonde product, which had a correlation coefficient of 0.92.A variety of biases affecting Eureka instruments are revealed and discussed. A subset of Eureka radiosonde measurements was processed by the Global Climate Observing System (GCOS) Reference Upper Air Network (GRUAN) for this study. Comparisons reveal a small dry bias in the standard radiosonde measurement water vapour total columns of approximately 4 %. A recently produced solar absorption FTIR spectrometer dataset resulting from the MUSICA (MUlti-platform remote Sensing of Isotopologues for investigating the Cycle of Atmospheric water) retrieval technique is shown to offer accurate measurements of water vapour total columns (e.g. average agreement within -5.2 % of GRUAN and -6.5 % of a co-located emission FTIR spectrometer). However, comparisons show a small wet bias of approximately 6 % at the high-latitude Eureka site. In addition, a new dataset derived from Atmospheric Emitted Radiance Interferometer (AERI) measurements is shown to provide accurate water vapour measurements (e.g. average agreement was within 4 % of GRUAN), which usefully enables measurements to be taken during day and night (especially valuable during polar night).

Interactions of fission product vapours with aerosols

Energy Technology Data Exchange (ETDEWEB)

Benson, C G; Newland, M S [AEA Technology, Winfrith (United Kingdom)

1996-12-01

Reactions between structural and reactor materials aerosols and fission product vapours released during a severe accident in a light water reactor (LWR) will influence the magnitude of the radiological source term ultimately released to the environment. The interaction of cadmium aerosol with iodine vapour at different temperatures has been examined in a programme of experiments designed to characterise the kinetics of the system. Laser induced fluorescence (LIF) is a technique that is particularly amenable to the study of systems involving elemental iodine because of the high intensity of the fluorescence lines. Therefore this technique was used in the experiments to measure the decrease in the concentration of iodine vapour as the reaction with cadmium proceeded. Experiments were conducted over the range of temperatures (20-350{sup o}C), using calibrated iodine vapour and cadmium aerosol generators that gave well-quantified sources. The LIF results provided information on the kinetics of the process, whilst examination of filter samples gave data on the composition and morphology of the aerosol particles that were formed. The results showed that the reaction of cadmium with iodine was relatively fast, giving reaction half-lives of approximately 0.3 s. This suggests that the assumption used by primary circuit codes such as VICTORIA that reaction rates are mass-transfer limited, is justified for the cadmium-iodine reaction. The reaction was first order with respect to both cadmium and iodine, and was assigned as pseudo second order overall. However, there appeared to be a dependence of aerosol surface area on the overall rate constant, making the precise order of the reaction difficult to assign. The relatively high volatility of the cadmium iodide formed in the reaction played an important role in determining the composition of the particles. (author) 23 figs., 7 tabs., 22 refs.

Interactions of fission product vapours with aerosols

International Nuclear Information System (INIS)

Benson, C.G.; Newland, M.S.

1996-01-01

Reactions between structural and reactor materials aerosols and fission product vapours released during a severe accident in a light water reactor (LWR) will influence the magnitude of the radiological source term ultimately released to the environment. The interaction of cadmium aerosol with iodine vapour at different temperatures has been examined in a programme of experiments designed to characterise the kinetics of the system. Laser induced fluorescence (LIF) is a technique that is particularly amenable to the study of systems involving elemental iodine because of the high intensity of the fluorescence lines. Therefore this technique was used in the experiments to measure the decrease in the concentration of iodine vapour as the reaction with cadmium proceeded. Experiments were conducted over the range of temperatures (20-350 o C), using calibrated iodine vapour and cadmium aerosol generators that gave well-quantified sources. The LIF results provided information on the kinetics of the process, whilst examination of filter samples gave data on the composition and morphology of the aerosol particles that were formed. The results showed that the reaction of cadmium with iodine was relatively fast, giving reaction half-lives of approximately 0.3 s. This suggests that the assumption used by primary circuit codes such as VICTORIA that reaction rates are mass-transfer limited, is justified for the cadmium-iodine reaction. The reaction was first order with respect to both cadmium and iodine, and was assigned as pseudo second order overall. However, there appeared to be a dependence of aerosol surface area on the overall rate constant, making the precise order of the reaction difficult to assign. The relatively high volatility of the cadmium iodide formed in the reaction played an important role in determining the composition of the particles. (author) 23 figs., 7 tabs., 22 refs

Isotopic estimation of the evapo-transpiration flux in a plain agricultural region (Po plain, Northern Italy)

International Nuclear Information System (INIS)

Elmi, Giovanni; Sacchi, Elisa; Zuppi, Gian Maria; Cerasuolo, Marcello; Allais, Enrico

2013-01-01

Highlights: ► Isotopic data from 19-months monitoring of water vapour and monthly precipitation. ► The mean annual weighted δ 18 O in rainwater samples is −6.90 ± 2.2. ► Results interpreted in relationship to climatic factors and to air masses circulation. ► Besides local vapour, moisture is carried by continental and maritime circulations. ► A computational method based on isotopes (EMMA) allows quantifying the local vapour fraction. - Abstract: Samples of water vapour and monthly precipitation were collected in Pavia, located 50 km south of Milan (Western Po plain, Northern Italy), over a period of 19 months, from March 2006 to September 2007. Results are interpreted in relation to the local climatic factors (temperature and precipitation rates), and to air mass circulation patterns, derived from sea level pressure maps, geopotential maps and satellite images. Since most water vapour samples represent a mixture of continental air masses and local evapo-transpiration fluxes, a computational method based on the stable isotope content (EMMA) has been used to evaluate the percentage of the different components and to quantify the local vapour fraction. The regression line equation for rainwater samples is: δ 2 H vs.VSMOW =8.8(±0.5)·δ 18 O vs.SMOW +14.5(±3.5)‰(R 2 =0.96;n=17) The slope of the line is extremely high and probably related to the dataset used, which includes two summer seasons and one winter season. In addition, the latter was somewhat anomalous, with recorded average temperatures higher than the average calculated for the years 1970–2002. The mean annual weighted δ 18 O in rainwater samples is equal to −6.90 ± 2.2‰. The regression line equation for water vapour samples is: δ 2 H vs.VSMOW =6.8(±0.3)·δ 18 O vs.SMOW -7.4(±4.9)‰(R 2 =0.92;n=37). The two regression lines meet at δ 18 O = −10.82 ± 13.97‰. This value appears more depleted than the mean annual weighted precipitation value, but is close to the isotope

Improved repetition rate mixed isotope CO{sub 2} TEA laser

Energy Technology Data Exchange (ETDEWEB)

Cohn, D. B., E-mail: dbctechnology@earthlink.net [DBC Technology Corp., 4221 Mesa St, Torrance, California 90505 (United States)

2014-09-15

A compact CO{sub 2} TEA laser has been developed for remote chemical detection that operates at a repetition rate of 250 Hz. It emits 700 mJ/pulse at 10.6 μm in a multimode beam with the {sup 12}C{sup 16}O{sub 2} isotope. With mixed {sup 12}C{sup 16}O{sub 2} plus {sup 13}C{sup 16}O{sub 2} isotopes it emits multiple lines in both isotope manifolds to improve detection of a broad range of chemicals. In particular, output pulse energies are 110 mJ/pulse at 9.77 μm, 250 mJ/pulse at 10 μm, and 550 mJ/pulse at 11.15 μm, useful for detection of the chemical agents Sarin, Tabun, and VX. Related work shows capability for long term sealed operation with a catalyst and an agile tuner at a wavelength shift rate of 200 Hz.

Isotopic changes due to convective moistening of the lower troposphere associated with variations in the ENSO and IOD from 2005 to 2006

Directory of Open Access Journals (Sweden)

Jeonghoon Lee

2015-04-01

Full Text Available We use the tropospheric emission spectrometer measurements of the isotopic composition of water vapour (δD in the lower troposphere to examine how changes in the distribution of convection and precipitation control water vapour amount and its isotope over the Indian Ocean. Measurements of the outgoing longwave radiation and vertical velocity from NCEP/NCAR Reanalysis and cloud ice water content from the Microwave Limb Sounder show distinct variations in convection due to a phase shift of both El Niño – Southern Oscillation (ENSO and Indian Ocean Dipole (IOD. These variations in convection are associated with changes in precipitation and water amount over the Western Indian Ocean (WIO and Eastern Indian Ocean (EIO, depending on the phases of ENSO and/or the IOD. Over the EIO in 2006, induced by the interplay of both positive ENSO and IOD, it is drier and less isotopically depleted due to less frequent and/or weaker deep convective activity and subsequent precipitation compared to 2005. By contrast, over the WIO in 2006, an increase in water vapour and precipitation but little isotopic fractionation in water vapour of clear sky compared to 2005 is likely associated with an increase in both enhanced deep and shallow convection, caused by the positive IOD. Therefore, paleoarchives of water isotopes near Africa will be more difficult to relate to a single process because changes in convective activity result in changes in precipitation but do not have a significant impact on the isotopic composition of the source vapour based on this case analysis.

An isotopic analysis process with optical emission spectrometry on a laser-produced plasma

International Nuclear Information System (INIS)

Mauchien, P.; Pietsch, W.; Petit, A.; Briand, A.

1994-01-01

The sample that is to be analyzed is irradiated with a laser beam to produce a plasma at the sample surface; the spectrum of the light emitted by the plasma is analyzed and the isotope composition of the sample is derived from the spectrometry. The process is preferentially applied to uranium and plutonium; it is rapid, simpler and cheaper than previous methods, and may be applied to 'in-situ' isotopic analysis in nuclear industry. 2 figs

Process and device for the excitation and selective dissociation by absorption of a laser light and application to isotopic enrichment

International Nuclear Information System (INIS)

Rigny, Paul.

1975-01-01

The description is given of a process for the excitation and selective dissociation by absorption of the monochromatic light emitted by a high power laser. The laser light at frequency ν 1 is beamed on to an isotopic mixture of gaseous molecules, some of these molecules presenting transitions, between two vibration levels corresponding to a given isotope, separated by an energy interval ΔE 1 =2h ν 1 , and the molecules of a given isotopic species are thus preferentially dissociated into several component parts [fr

On the potential of laser driven isotope generation at ELI-NP for positron emission tomography

Science.gov (United States)

Cucoanes, A. S.; Balabanski, D. L.; Canova, F.; Cuong, P.; Negoita, F.; Puicea, F.; Tanaka, K. A.

2017-05-01

The huge progress made in the laser driven ion acceleration had open the possibility of using ions generated in high power laser interactions with solid targets for the production of medical isotopes. Indeed, lasers could provide several key features with respect to the traditional method where the target activation is produced by particle beams delivered by cyclotrons. The price and the dimensions of high power lasers are on a descendant slope and the quality of the produced ion beams is continuously increasing. However, in order to compete with cyclotrons, the average proton current intensity has to be increased for example by increasing the frequency of the laser pulses. In our contribution, we review the general ideas of the laser-based radioisotope production and we present our analysis on the potential of the medical isotope generation at ELI-NP with a focus on 18F. We use estimations of the proton beam parameters and a code implemented in Geant4 for computing the yield of the main production channel taking into account the experimental conditions available soon at ELI-NP. The obtained results are compatible with previous studies and will be verified by experiments foreseen at the future ELI-NP facility, under construction now in Magurele, Romania.

Airborne differential absorption lidar for water vapour measurements in the upper troposphere and lower stratosphere in the spectral region around 940 nm

Energy Technology Data Exchange (ETDEWEB)

Poberaj, G.

2000-07-01

Two all-solid-state laser systems were developed and studied in detail to optimise their performance for an airborne water vapour differential absorption lidar (DIAL). Their special features are high average output powers and excellent spectral properties in the 940-nm spectral region relevant for monitoring very low water vapour contents in the upper troposphere and lower stratosphere. One system is an injection-seeded pulsed Ti:sapphire ring laser with a spectral bandwidth of 105 MHz and an average power of 1.1 W. The other system is an injection-seeded optical parametric oscillator (OPO) in a ring configuration. Using KTP as nonlinear crystal, a signal output with a spectral bandwidth of 140 MHz and an average power of 1.2 W was achieved. Both systems, the Ti:sapphire ring laser and the KTP OPO, possess spectral purity values higher than 99%. The pump source for these systems is a frequency doubled diode-pumped Nd:YAG laser operating at a repetition rate of 100 Hz. The KTP OPO system has been used as a transmitter in a new airborne water vapour DIAL instrument. For the first time, measurements of two-dimensional water vapour distributions with a high vertical (500 m) and horizontal (20 km) resolution across several potential vorticity streamers were performed. Very low water vapour mixing ratios (10-50 ppmv) and strong gradients were observed in the tropopause region. The sensitivity of the DIAL instrument in the centre of a stratospheric intrusion ranges from 3% in the near field to 12% in the far field (4 km). The first comparison experiments with in situ measuring instruments show a good agreement. Considerable differences are found between DIAL measurements and data obtained from the ECMWF operational analyses and a mesoscale numerical model. (orig.)

Infrared laser system

International Nuclear Information System (INIS)

Cantrell, C.D.; Carbone, R.J.

1977-01-01

An infrared laser system and method for isotope separation may comprise a molecular gas laser oscillator to produce a laser beam at a first wavelength, Raman spin flip means for shifting the laser to a second wavelength, a molecular gas laser amplifier to amplify said second wavelength laser beam to high power, and optical means for directing the second wavelength, high power laser beam against a desired isotope for selective excitation thereof in a mixture with other isotopes. The optical means may include a medium which shifts the second wavelength high power laser beam to a third wavelength, high power laser beam at a wavelength coincidental with a corresponding vibrational state of said isotope and which is different from vibrational states of other isotopes in the gas mixture

Dermatological laser treatment

International Nuclear Information System (INIS)

Moerk, N.J.; Austad, J.; Helland, S.; Thune, P.; Volden, G.; Falk, E.

1991-01-01

The article reviews the different lasers used in dermatology. Special emphasis is placed on the treatment of naevus flammeus (''portwine stain'') where lasers are the treatment of choice. Argon laser and pulsed dye laser are the main lasers used in vascular skin diseases, and the article focuses on these two types. Copper-vapour laser, neodymium-YAG laser and CO 2 laser are also presented. Information is provided about the availability of laser technology in the different health regions in Norway. 5 refs., 2 figs

Calculation of isotope selective excitation of uranium isotopes using spectral simulation method

International Nuclear Information System (INIS)

Al-Hassanieh, O.

2009-06-01

Isotope ratio enhancement factor and isotope selectivity of 235 U in five excitation schemes (I: 0→10069 cm - 1 →IP, II: 0 →10081 cm - 1 →IP, III: 0 →25349 cm - 1→ IP, IV: 0→28650 cm - 1 →IP, V: 0→16900 cm - 1 →34659 cm - 1 →IP), were computed by a spectral simulation approach. The effect of laser bandwidth and Doppler width on the isotope ratio enhancement factor and isotope selectivity of 235 U has been studied. The photoionization scheme V gives the highest isotope ratio enhancement factor. The main factors which effect the separation possibility are the isotope shift and the relative intensity of the transitions between hyperfine levels. The isotope ratio enhancement factor decreases exponentially by increasing the Doppler width and the laser bandwidth, where the effect of Doppler width is much greater than the effect of the laser bandwidth. (author)

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

Science.gov (United States)

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

2016-06-01

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

Studies on the optogalvanic effect and isotope-selective excitation of ytterbium in a hollow cathode discharge lamp using a pulsed dye laser.

Science.gov (United States)

Kumar, Pankaj; Kumar, Jitendra; Prakash, Om; Saini, Vinod K; Dixit, Sudhir K; Nakhe, Shankar V

2013-09-01

This paper presents studies on the pulsed optogalvanic effect and isotope-selective excitation of Yb 555.648 nm (0 cm(-1) → 17 992.007 cm(-1)) and 581.067 nm (17 992.007 cm(-1) → 35 196.98 cm(-1)) transitions, in a Yb/Ne hollow cathode lamp. The Yb atoms were excited by narrow linewidth (500-1000 MHz) Rh110 and Rh6G dye based pulsed lasers. Optogalvanic signal inversion for ground state transition at 555.648 nm was observed beyond a hollow cathode discharge current of 8.5 mA, in contrast to normal optogalvanic signal at 581.067 nm up to maximum current of 14 mA. The isotope-selective excitation studies of Yb were carried out by recording Doppler limited optogalvanic signals as a function of dye laser wavelength. For the 581.067 nm transition, three even isotopes, (172)Yb, (174)Yb, and (176)Yb, and one odd isotope, (171)Yb, were clearly resolved. These data were compared with selective isotope excitation by 10 MHz linewidth continuous-wave dye laser. For 555.648 nm transition, isotopes were not clearly resolved, although isotope peaks of low modulation were observed.

Direct determination of halogens in powdered geological and environmental samples using isotope dilution laser ablation ICP-MS

Science.gov (United States)

Boulyga, Sergei F.; Heumann, Klaus G.

2005-04-01

Laser ablation inductively coupled plasma isotope dilution mass spectrometry (LA-ICP-IDMS) with a special laser ablation system for bulk analyses (LINA-Spark(TM)-Atomiser) was applied for direct determinations of chlorine, bromine, and iodine in rock and sediment samples. Special attention was focused on possible inter-halogen fractionations and analyte/spike isotope fractionations by using LA-ICP-MS and LA-ICP-IDMS, respectively. A variation of Br/Cl and I/Cl element intensity ratios by a factor of 1.3-3 was observed when changing the nebulizer gas flow rate in the range of 0.84-1.0 L min-1 and the laser power density in the range of 2-10 GW cm-2, respectively. When using an internal standard for halogen quantification in LA-ICP-MS, this inter-element fractionation can cause systematic errors, which can be avoided by applying the isotope dilution technique. However, at high laser power densities (>5.7 GW cm-2 for iodine and >4.0 GW cm-2 for bromine and chlorine) the corresponding measured isotope ratio of the isotope-diluted sample deviates significantly from the target value. Under optimised conditions concentrations in the range of 30 [mu]g g-1-16 × 103 [mu]g g-1 for chlorine, <2-140 [mu]g g-1 for bromine, and <0.1-31 [mu]g g-1 for iodine were determined by LA-ICP-IDMS in two sediment reference materials (SRM 1646, SRM 2704) and three rock reference samples (GS-N, Granite; BX-N, Bauxite; DT-N, Disthene), which have not been certified for these halogens. The sediment results agree well within the given uncertainties with indicative values by different methods and the results of the rock samples with those obtained by negative thermal ionisation isotope dilution mass spectrometry. The detection limits of LA-ICP-IDMS are 8 [mu]g g-1 for chlorine, 1.7 [mu]g g-1 for bromine, and 0.1 [mu]g g-1 for iodine.

Deuteron-induced reactions generated by intense lasers for PET isotope production

Science.gov (United States)

Kimura, Sachie; Bonasera, Aldo

2011-05-01

We investigate the feasibility of using laser accelerated protons/deuterons for positron emission tomography (PET) isotope production by means of the nuclear reactions 11B(p, n) 11C and 10B(d, n) 11C. The second reaction has a positive Q-value and no energy threshold. One can, therefore, make use of the lower energy part of the laser-generated deuterons, which includes the majority of the accelerated deuterons. By assuming that the deuteron spectra are similar to the proton spectra, the 11C produced from the reaction 10B(d, n) 11C is estimated to be 7.4×10 9 per laser-shot at the Titan laser at Lawrence Livermore National Laboratory. Meanwhile a high-repetition table-top laser irradiation is estimated to generate 3.5×10 711C per shot from the same reaction. In terms of the 11C activity, it is about 2×10 4 Bq per shot. If this laser delivers kHz, the activity is integrated to 1 GBq after 3 min. The number is sufficient for the practical application in medical imaging for PET.

Resonances of coherent population trapping in samarium vapours

International Nuclear Information System (INIS)

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

2001-01-01

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

Isotope Exchange in Oxide Catalyst

Science.gov (United States)

Hess, Robert V.; Miller, Irvin M.; Schryer, David R.; Sidney, Barry D.; Wood, George M., Jr.; Hoyt, Ronald F.; Upchurch, Billy T.; Brown, Kenneth G.

1987-01-01

Replacement technique maintains level of CO2/18 in closed-cycle CO2 lasers. High-energy, pulsed CO2 lasers using rare chemical isotopes must be operated in closed cycles to conserve gas. Rare isotopes operated in closed cycles to conserve gas. Rare isotopes as CO2/18 used for improved transmission of laser beam in atmosphere. To maintain laser power, CO2 must be regenerated, and O2 concentration kept below few tenths of percent. Conditions achieved by recombining CO and O2.

Atomic vapor laser isotope separation at Lawrence Livermore National Laboratory: a status report

International Nuclear Information System (INIS)

Davis, J.I.

1980-01-01

The field of laser induced chemistry began in earnest early in the 1970's with the initiation of major efforts in laser isotope separation (LIS) of uranium. Though many specialized, small-scale photochemical and diagnostic applications have been identified and evaluated experimentally, and continue to show promise, currently the only high payoff, large-scale applications remain LIS of special elements. Aspects of the physical scaling, technology status and economic basis of uranium LIS are examined with special emphasis on the effort at LLNL

Alternative applications of atomic vapor laser isotope separation technology

International Nuclear Information System (INIS)

1991-01-01

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

Vapour pressures and enthalpies of vapourization of a series of the linear aliphatic nitriles

International Nuclear Information System (INIS)

Emel'yanenko, Vladimir N.; Verevkin, Sergey P.; Koutek, Bohumir; Doubsky, Jan

2005-01-01

Vapour pressures and the molar enthalpies of vapourization ΔlgHm-bar of the linear aliphatic nitriles C 7 -C 17 have been determined by the transpiration method. Kovat's indices of these compounds were measured by capillary gas-chromatography. A linear correlation of enthalpies of vapourization ΔlgHm-bar at T=298.15 K of the nitriles studied with the Kovats indices has been found

Isotope separation method and apparatus

International Nuclear Information System (INIS)

Lyon, R.K.; Eisner, P.N.; Thomas, W.R.L.

1980-01-01

A method and apparatus are specified for separating a mixture of isotopes present in a compound, preferably a gaseous compound, into two or more parts in each of which the abundances of the isotopes differ from the natural abundances of the isotopes in the compound. The invention particularly relates to carrying out a laser induced, isotopically selective conversion of gaseous molecules in such a manner as to achieve more than one stage of isotope separation along the length of the laser beam. As an example, the invention is applied to the separation of the isotopes of uranium in UF 6 , in which either the U-235 or U-238 isotope is selectively excited by means of irradiation from an infrared laser, and the selectively excited isotope converted into a product that can be recovered from UF 6 by one of a variety of methods that are described. (U.K.)

Process for exchanging hydrogen isotopes between gaseous hydrogen and water

International Nuclear Information System (INIS)

Hindin, S.G.; Roberts, G.W.

1977-01-01

A process is described for exchanging isotopes (particularly tritium) between water and gaseous hydrogen. Isotope depleted gaseous hydrogen and water containing a hydrogen isotope are introduced into the vapour phase in a first reaction area. The steam and gaseous hydrogen are brought into contact with a supported metal catalyst in this area in a parallel flow at a temperature range of around 225 and 300 0 C. An effluent flow comprising a mixture of isotope enriched gaseous hydrogen and depleted steam is evacuated from this area and the steam condensed into liquid water [fr

The exchange reaction between deuterium and water vapour on platinum deposited over a hydrophobic support

International Nuclear Information System (INIS)

Itsuo, Iida; Junko, Kato; Kenzi, Tamuru

1977-01-01

Isotope exchange reaction between deuterium gas and water vapour at room temperature and below on platinum deposited on hydrophobic supports such as polytetrafluoroethylene (PTFE) or Porapak Q (copolymer of styrene and divinylbenzene) was studied and the results were compared with those of the exchange reaction on platinum over hydrophilic support such as alumina. It was demonstrated that the exchange reaction at temperatures below the boiling point of water is markedly retarded by the multilayer adsorption of water over the platinum catalyst deposited on hydrophilic support, whereas the platinum catalyst on hydrophobic support exhibited a high catalytic activity, being not retarded by the water, forming no multilayer of adsorbed water over platinum surface. Therefore in the case of the hydrogen isotope exchange reaction on platinum over hydrophobic support, the chemical exchange rate can be measured even under a saturated vapour pressure of water. The surface area of platinum was estimated by hydrogen chemisorption and hydrogen titration and specific activities of the catalyst were calculated at both room temperature and freezing point of water, which revealed that the specific rate of this reaction does not differ so much over various supports. (orig.) [de

Sequencing of Isotope-Labeled Small RNA Using Femtosecond Laser Ablation Time-of-Flight Mass Spectrometry

Science.gov (United States)

Kurata-Nishimura, Mizuki; Ando, Yoshinari; Kobayashi, Tohru; Matsuo, Yukari; Suzuki, Harukazu; Hayashizaki, Yoshihide; Kawai, Jun

2010-04-01

A novel method for the analysis of sequences of small RNAs using nucleotide triphosphates labeled with stable isotopes has been developed using time-of-flight mass spectroscopy combined with femtosecond laser ablation (fsLA-TOF-MS). Small RNAs synthesized with nucleotides enriched in 13C and 15N were efficiently atomized and ionized by single-shot fsLA and the isotope ratios 13C/12C and 15N/14N were evaluated using the TOF-MS method. By comparing the isotope ratios among four different configurations, the number of nucleotide contents of the control RNA sample were successfully reproduced.

Radiation gradient isotope separator

International Nuclear Information System (INIS)

Hughes, J.L.

1980-01-01

A system is described for transporting, separating and storing charged particles, charged antiparticles and fully or partially ionized isotopes of any element comprising a laser beam generator, laser beam intensity profiler, a laser beam variable intensity attenuator, and means for injecting charged particles, charged antiparticles and ionized isotopes into the beam and extracting them from the system as required. The invention is particularly useful for channelling electrons and ions used for fuel pellet compression in inertial fusion systems, for separating the isotopes of elements and for the confinement of charged antiparticles and particle/antiparticle plasmas

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.

Laser separation of uranium isotopes

International Nuclear Information System (INIS)

Porter, J.T.

1981-01-01

Method and apparatus for separating uranium isotopes are claimed. The method comprises the steps of irradiating a uranyl source material at a wavelength selective to a desired isotope and at an effective temperature for isotope spectral line splitting below about 77 deg.K., further irradiating the source material within the fluorescent lifetime of the source material to selectively photochemically reduce the excited isotopic species, and chemically separating the reduced isotope species from the remaining uranyl salt compound

Isotope separation

International Nuclear Information System (INIS)

Eerkens, J.W.

1979-01-01

A method of isotope separation is described which involves the use of a laser photon beam to selectively induce energy level transitions of an isotope molecule containing the isotope to be separated. The use of the technique for 235 U enrichment is demonstrated. (UK)

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

International Nuclear Information System (INIS)

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

2016-01-01

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

Laser isotope separation

International Nuclear Information System (INIS)

1976-01-01

The claimed invention is a method of isotope separation based on the unimolecular decomposition of vibrationally excited negative ions which are produced in the reaction of thermal electrons and molecules which have been vibrationally excited in an isotope selective manner. This method is especially applicable to molecules represented by the formula MF 6 wherein M is selected from the group consisting of U, S, W, Se, Te, Mo, Re and Tc

The water vapour self-continuum absorption in the infrared atmospheric windows: new laser measurements near 3.3 and 2.0 µm

Directory of Open Access Journals (Sweden)

L. Lechevallier

2018-04-01

Full Text Available The amplitude, the temperature dependence, and the physical origin of the water vapour absorption continuum are a long-standing issue in molecular spectroscopy with direct impact in atmospheric and planetary sciences. In recent years, we have determined the self-continuum absorption of water vapour at different spectral points of the atmospheric windows at 4.0, 2.1, 1.6, and 1.25 µm, by highly sensitive cavity-enhanced laser techniques. These accurate experimental constraints have been used to adjust the last version (3.2 of the semi-empirical MT_CKD model (Mlawer-Tobin_Clough-Kneizys-Davies, which is widely incorporated in atmospheric radiative-transfer codes. In the present work, the self-continuum cross-sections, CS, are newly determined at 3.3 µm (3007 cm−1 and 2.0 µm (5000 cm−1 by optical-feedback-cavity enhanced absorption spectroscopy (OFCEAS and cavity ring-down spectroscopy (CRDS, respectively. These new data allow extending the spectral coverage of the 4.0 and 2.1 µm windows, respectively, and testing the recently released 3.2 version of the MT_CKD continuum. By considering high temperature literature data together with our data, the temperature dependence of the self-continuum is also obtained.

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

International Nuclear Information System (INIS)

Sifi, R.

2007-07-01

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

Isotopic separation of carbon by dissociation of CF2HCl irradiated by a Q-modulated CO2 laser

International Nuclear Information System (INIS)

Ezubchenko, A.N.; Ilyukhin, A.I.; Karchevskii, A.I.; Krasnikov, N.S.; Merzylakov, A.V.; Soloukhin, A.B.

1993-01-01

Isotopic separation of carbon by selective dissociation of CF 2 HCl by radiation from a CO 2 laser with mechanical Q-modulation has been studied experimentally. The modulation frequency was 10 4 sec -1 with a 20 W output. The peak radiation intensity is increased by a factor of 20-100 when modulated, while the average power is 0.5-0.9 that of the laser when operating in continuous mode. The authors show that under these conditions, a separation coefficient on the order of 40-50 is achieved as well as a high degree of the target isotope extraction (70%)

Nuclear structure of light thallium isotopes as deduced from laser spectroscopy on a fast atom beam

International Nuclear Information System (INIS)

Bounds, J.A.

1985-08-01

After optimizing the system by experiments on /sup 201,203,205/Tl, the neutron-deficient isotopes 189-193 Tl have been studied using the collinear fast atom beam laser spectroscopy system at UNISOR on-line to the Holifield Heavy Ion Research Facility. A sensitive system for the measurements was developed since the light isotopes were available in mass-separated beams of only 7 x 10 4 to 4 x 10 5 atoms per second. By laser excitation of the 535 nm atomic transitions of atoms in the beam, the 6s 2 7s 2 S/sub 1/2/ and 6s 2 6s 2 P/sub 3/2/ hyperfine structures were measured, as were the isotope shifts of the 535 nm transitions. From these, the magnetic dipole moments, spectroscopic quadrupole moments and isotopic changes in mean-square charge radius were deduced. The magnetic dipole moments are consistent with previous data. The /sup 190,192/Tl isotopes show a considerable difference in quadrupole deformations as well as an anomalous isotope shift with respect to 194 Tl. A large isomer shift in 193 Tl is observed implying a larger deformation in the 9/2 - isomer than in the 1/2 + ground state. The /sup 189,191,193/Tl isomers show increasing deformation away from stability. A deformed shell model calculation indicates that this increase in deformation can account for the dropping of the 9/2 - band in these isotopes while an increase in neutron pairing correlations, having opposite and compensating effects on the rotational moment of inertia, maintains the 9/2 - strong-coupled band structure. 105 refs., 27 figs

Method to separate various isotopes in compounds by means of laser radiation

International Nuclear Information System (INIS)

Meyer-Kretschmer, G.; Jetter, H.; Toennies, P.

1980-01-01

The uranium hexafluoride together with an inert addition gas is cooled down below 50 K by adiabatic expansion, then the state of oscillation of the molecules is changed specifically for each isotope using laser light, and subsequently positive ions are produced by means of an electron beam. The ions are removed from the gas by means of an electric field. (DG) [de

The Liquid Vapour Interface

DEFF Research Database (Denmark)

Als-Nielsen, Jens Aage

1985-01-01

In this short review we are concerned with the density variation across the liquid-vapour interface, i.e. from the bulk density of the liquid to the essentially zero density of the vapour phase. This density variation can in principle be determined from the deviation of the reflectivity from...

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

International Nuclear Information System (INIS)

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

2005-01-01

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

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.

Isotopic clusters

International Nuclear Information System (INIS)

Geraedts, J.M.P.

1983-01-01

Spectra of isotopically mixed clusters (dimers of SF 6 ) are calculated as well as transition frequencies. The result leads to speculations about the suitability of the laser-cluster fragmentation process for isotope separation. (Auth.)

Optical isotope shifts for unstable samarium isotopes

International Nuclear Information System (INIS)

Eastham, D.A.; Walker, P.M.; Griffith, J.A.R.; Evans, D.E.; Grant, I.S.; England, J.G.; Fawcett, M.J.

1984-01-01

Using a tunable dye laser beam intersecting a thermal atomic beam, optical isotope shifts and hyperfine splittings have been measured for the four unstable samarium isotopes between 144 Sm and 154 Sm, covering the well known transition region from spherical to deformed shapes. (orig.)

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

Bibliography on vapor pressure isotope effects

International Nuclear Information System (INIS)

Jancso, G.

1980-04-01

The first Bibliography on Vapour Pressure Isotope and covered the literature of the period from 1919 through December 1975. The present Supplement reviews the literature from January 1976 through December 1979. The bibliography is arranged in chronological order; within each year the references are listed alphabetically according to the name of the first author of each work. (author)

Near-IR laser-based spectrophotometer for comparative analysis of isotope content of CO2 in exhale air samples

International Nuclear Information System (INIS)

Stepanov, E V; Glushko, A N; Kasoev, S G; Koval', A V; Lapshin, D A

2011-01-01

We present a laser spectrophotometer aimed at high-accuracy comparative analysis of content of 12 CO 2 and 13 CO 2 isotope modifications in the exhale air samples and based on a tunable near-IR diode laser (2.05 μm). The two-channel optical scheme of the spectrophotometer and the special digital system for its control are described. An algorithm of spectral data processing aimed at determining the difference in the isotope composition of gas mixtures is proposed. A few spectral regions (near 4880 cm -1 ) are determined to be optimal for analysis of relative content of 12 CO 2 and 13 CO 2 in the exhale air. The use of the proposed spectrophotometer scheme and the developed algorithm makes the results of the analysis less susceptible to the influence of the interference in optical elements, to the absorption in the open atmosphere, to the slow drift of the laser pulse envelope, and to the offset of optical channels. The sensitivity of the comparative analysis of the isotope content of CO 2 in exhale air samples, achieved using the proposed scheme, is estimated to be nearly 0.1‰.

Isotope separation apparatus and method

International Nuclear Information System (INIS)

Feldman, B. J.

1985-01-01

The invention relates to an improved method and apparatus for laser isotope separation by photodeflection. A molecular beam comprising at least two isotopes to be separated intersects, preferably substantially perpendicular to one broad side of the molecular beam, with a laser beam traveling in a first direction. The laser beam is reflected back through the molecular beam, preferably in a second direction essentially opposite to the first direction. Because the molecules in the beam occupy various degenerate energy levels, if the laser beam comprises chirped pulses comprising selected wavelengths, the laser beam will very efficiently excite substantially all unexcited molecules and will cause stimulated emission of substantially all excited molecules of a selected one of the isotopes in the beam which such pulses encounter. Excitation caused by first direction chirped pulses moves molecules of the isotope excited thereby in the first direction. Stimulated emission of excited molecules of the isotope is brought about by returning chirped pulses traveling in the second direction. Stimulated emission moves emitting molecules in a direction opposite to the photon emitted. Because emitted photons travel in the second direction, emitting molecules move in the first direction. Substantial molecular movement of essentially all the molecules containing the one isotope is accomplished by a large number of chirped pulse-molecule interactions. A beam corer collects the molecules in the resulting enriched divergent portions of the beam

Environmental isotope data no. 10: World survey of isotope concentration in precipitation (1988-1991). Report from a network

International Nuclear Information System (INIS)

1994-01-01

This is the tenth volume of the publication Environmental Isotope Data: World Survey of Isotope Concentration in Precipitation. This volume is primarily concerned with the concentration of the environmental isotopes (tritium, deuterium and oxygen-18) in monthly samples of precipitation taken by a global network of 169 stations in the period 1988 to 1991. Selected meteorological data, such as the amount of precipitation, mean water vapour pressure and surface air temperature, are also presented. Data before 1988 which were unavailable at the time of the earlier issues have also been included in the latter part of this volume as late reports. The data are being widely used in hydrological, hydrometeorological and climatological studies. 9 refs, 2 figs

Frequency stabilization of quantum cascade laser for spectroscopic CO2 isotope analysis

Science.gov (United States)

Han, Luo; Xia, Hua; Pang, Tao; Zhang, Zhirong; Wu, Bian; Liu, Shuo; Sun, Pengshuai; Cui, Xiaojuan; Wang, Yu; Sigrist, Markus W.; Dong, Fengzhong

2018-06-01

Using off-axis integrated cavity output spectroscopy, named OA-ICOS, the absorption spectrum of CO2 at 4.32 μm is recorded by using a quantum cascade laser (QCL). The concentration of the three isotopologues 16O12C16O, 16O13C16O and 16O12C18O is detected simultaneously. The isotope abundance ratio of 13C and 18O in CO2 gas can be obtained, which is most useful for ecological research. Since the ambient temperature has a serious influence on the output wavelength of the laser, even small temperature variations seriously affect the stability and sensitivity of the system. In this paper, a wavelength locking technique for QCL is proposed. The output of a digital potentiometer integrated in the laser current driver control is modified by software, resulting in a correction of the driving current of the laser and thus of its wavelength. This method strongly reduces the influence of external factors on the wavelength drift of lasers and thus substantially improves the stability and performance of OA-ICOS as is demonstrated with long-time measurements on CO2 in laboratory air.

Quantifying the Components of Evapotranspiration from Plant Communities, Soil Evaporation and Plant Transpiration, with Oxygen-18 Isotopes and Micrometeorology

Energy Technology Data Exchange (ETDEWEB)

Denmead, Tom [CSIRO Centre for Environmental Mechanics, GPO Box 821, Canberra, ACT 2601 (Australia); Heng, Lee; Nguyen, Long [Soil and Water Management and Crop Nutrition Section, IAEA (Austria); Zeeman, Matthias [Karlsruhe Institute of Technology, Garmisch-Partenkirchen (Germany); Mayr, Leo; Arrillaga, Jose Luis [Soil and Water Management and Crop Nutrition Laboratory, IAEA (Austria); Cepuder, Peter [Department of Water-Atmosphere-Environment, Institute for Hydraulics and Rural Water Management (BOKU), Vienna (Austria)

2013-01-15

The Keeling plot (Keeling, 1961) approach has been shown to provide an estimate of the relative proportions of water vapour emanating from evaporation (E) from soil, and transpiration (T) from the plant canopy (Moreira et. al., 1997; Williams et al., 2004). This estimate can be used in conjunction with measurements of the net water vapour flux and evapotranspiration (ET), to quantify the E and T components using an Inverse Lagrangian (IL) approach based on canopy turbulence (Raupach, 1989), which allows the identification of water vapour in the different canopy layers (Denmead et al., 2005). A study was carried out on a wheat crop over a 3-day period in April (daily temperatures ranged from 14-23''oC) at the BOKU experimental field outside Vienna to provide an independent check of the relative proportions of soil evaporation (E) and plant transpiration (T) estimated by the Keeling plot {sigma}{sup 18}O isotope analysis and by the application of the IL model of water vapour transport in plant canopies. The eddy covariance instrumentation to measure ET was provided by the Karlsruhe Institute of Technology at Garmisch-Partenkirchen, Germany. Transpiration rates, estimated by the {sigma}{sup 18}O isotopic technique were similar to those derived from Inverse Lagrangian analyses. indicating that the IL and isotopic analyses gave essentially the same partitioning of evapotranspiration into E and T. The use of the IL analysis to determine water vapour in different segments of the canopy is illustrated. In these observations the soil was dry (9-12 %) and soil evaporation was small. The eddy covariance approach confirmed the correctness of the IL analysis for the total water loss from the canopy (to within 6%) (data not shown). The IL and the isotopic analyses gave essentially the same partitioning of ET into E and T for 3 days on a dry soil. The isotopic analysis using {sigma}{sup 18}O gave E/ET {approx} 4% and T/ET {approx} 96%, while IL analysis gave corresponding figures

Ground-state properties of K-isotopes from laser and $\\beta$-NMR spectroscopy

CERN Multimedia

Lievens, P; Rajabali, M M; Krieger, A R

By combining high-resolution laser spectroscopy with $\\beta$-NMR spectroscopy on polarized K-beams we aim to establish the ground-state spins and magnetic moments of the neutron-rich $^{48,49,50,51}$K isotopes from N=29 to N=32. Spins and magnetic moments of the odd-K isotopes up to N=28 reveal an inversion of the ground-state, from the normal $\\,{I}$=3/2 ($\\pi{d}_{3/2}^{-1}$) in $^{41-45}$K$\\to\\,{I}$=1/2 ($\\pi{s}_{1/2}^{-1}$) in $^{47}$K. This inversion of the proton single particle levels is related to the strong proton $d_{3/2}$ - neutron $f_{7/2}$ interaction which lowers the energy of the $\\pi{d}_{3/2}$ single particle state when filling the $\

Modelling non-steady-state isotope enrichment of leaf water in a gas-exchange cuvette environment.

Science.gov (United States)

Song, Xin; Simonin, Kevin A; Loucos, Karen E; Barbour, Margaret M

2015-12-01

The combined use of a gas-exchange system and laser-based isotope measurement is a tool of growing interest in plant ecophysiological studies, owing to its relevance for assessing isotopic variability in leaf water and/or transpiration under non-steady-state (NSS) conditions. However, the current Farquhar & Cernusak (F&C) NSS leaf water model, originally developed for open-field scenarios, is unsuited for use in a gas-exchange cuvette environment where isotope composition of water vapour (δv ) is intrinsically linked to that of transpiration (δE ). Here, we modified the F&C model to make it directly compatible with the δv -δE dynamic characteristic of a typical cuvette setting. The resultant new model suggests a role of 'net-flux' (rather than 'gross-flux' as suggested by the original F&C model)-based leaf water turnover rate in controlling the time constant (τ) for the approach to steady sate. The validity of the new model was subsequently confirmed in a cuvette experiment involving cotton leaves, for which we demonstrated close agreement between τ values predicted from the model and those measured from NSS variations in isotope enrichment of transpiration. Hence, we recommend that our new model be incorporated into future isotope studies involving a cuvette condition where the transpiration flux directly influences δv . There is an increasing popularity among plant ecophysiologists to use a gas-exchange system coupled to laser-based isotope measurement for investigating non-steady state (NSS) isotopic variability in leaf water (and/or transpiration); however, the current Farquhar & Cernusak (F&C) NSS leaf water model is unsuited for use in a gas-exchange cuvette environment due to its implicit assumption of isotope composition of water vapor (δv ) being constant and independent of that of transpiration (δE ). In the present study, we modified the F&C model to make it compatible with the dynamic relationship between δv and δE as is typically associated

A miniaturized laser-ablation mass spectrometer for in-situ measurements of isotope composition on solar body surfaces

Science.gov (United States)

Riedo, A.; Meyer, S.; Tulej, M.; Neuland, M.; Bieler, A.; Iakovleva, M.; Wurz, P.

2012-04-01

The in-situ analysis of extraterrestrial material onboard planetary rovers and landers is of considerable interest for future planetary space missions. Due to the low detection sensitivity of spectroscopic instruments, e.g. α-particle X-ray, γ-ray or neutron spectrometers, it is frequently possible to measure only major/minor elements in extraterrestrial materials. Nevertheless, the knowledge of minor/trace elements is of considerable interest to cosmochemistry. Chemistry puts constraints on the origin of solar system and its evolution enabling also a deeper inside to planetary transformation processes (e.g. volcanic surface alteration, space weathering). The isotopes play special role in analysis of the origin and transformation of planetary matter. They are robust tracers of the early events because their abundances are less disturbed as the elemental once. Nevertheless, if the isotope abundance ratios are fractionated, the underlying chemical and physical processes can be then encoded from the variations of abundance ratios. A detailed analysis of isotopic patterns of radiogenic elements can allow age dating of minerals and temporal evolution of planetary matter. High accuracy and sensitive measurements of isotopic pattern of bio-relevant elements, i.e., sulfur, found on planetary surfaces can be helpful for the identification of possible past and present extraterrestrial life in terms of biomarker identification. Our group has designed a self-optimizing miniaturized laser ablation time-of-flight mass spectrometer (LMS) for in situ planetary measurements (Wurz et al., 2012; Rohner et al., 2003). Initial studies utilizing IR laser radiation for ablation, atomization and ionization of solid materials indicated a high instrumental performance in terms of sensitivity and mass resolution (Tulej et al., 2011). Current studies are conducted with a UV radiation and a high spatial resolution is achieved by focussing the laser beam to 20µm spots onto the sample. The

High atomic weight isotope separator

International Nuclear Information System (INIS)

Book, D.L.

1978-01-01

A continuously operating device is described which separates one isotopic species of a given element from a mixture. The given element is vaporized and formed into a neutral beam containing the isotopes desired to be separated. The plasma is accelerated through a laser beam which is formed by two separate lasers which operate in the continuous wave mode in which the beams are as nearly as possible in the same beam path. The two laser output beams excite and ionize the isotope of interest while leaving the remaining atoms unaffected. The ionized isotopes are then separated from the beam by an electrostatic deflection technique and the unaffected atoms continue on in their path and are directed to a recovery device

Nuclear moments and isotopic variation of the mean square charge radii of strontium nuclei by atomic beam laser spectroscopy

International Nuclear Information System (INIS)

Chongkum, S.

1987-10-01

Hyperfine structure and optical isotope shift measurements have been performed on a series of stable and radioactive strontium isotopes (A = 80 to 90), including two isomers 85m and 87m. The spectroscopy applied continuous wave dye laser induced fluorescence of free atoms at λ=293.2 nm in a well collimated atomic beam. The 293.2 nm ultraviolet light was generated by frequency doubling the output of a dye laser in either a temperature tuned Ammonium Dihydrogen Arsenate (ADA) crystal or an angle tuned Lithium Iodate crystal. A special radio frequency (rf) technique was used to tune the dye laser frequency with long term stability. Radioactive Sr isotopes were produced either by neutron capture of stable strontium or by (α,xn) reactions from krypton gas. The samples were purified by an electromagnetic mass separator and their sizes were of order 100 pg, which corresponds to 10 11 atoms. The observed results of the hyperfine structure components are evaluated in terms of nuclear magnetic dipole moments and electric quadrupole moments. Changes in mean square charge radii of strontium nuclei which were extracted from the isotope shift measurements, exhibit a distinct shell effect at the neutron magic number N=50. The experimental data are analysed and compared with some theoretical nuclear model predictions. The strong increase of the nuclear charge radii with decreasing neutron number of isotopes below N=50 is in agreement with the variation of the mean square deformation extracted from measured B(E2) values. (orig.) [de

Keyhole behaviour during laser welding of zinc-coated steel

International Nuclear Information System (INIS)

Pan, Y; Richardson, I M

2011-01-01

The production of consistent, high-quality laser welds on zinc-coated steels for the automotive industry remains a challenge. A simple overlap joint geometry is desirable in these applications but has been shown to be extremely detrimental to laser welding because the zinc vapour formed at the interface between the two sheets expands into the keyhole and disrupts fluid flow in the melt pool, which often leads to metal ejection. In this work, laser welding on sheets with various coating thicknesses has been performed and it is observed that the sheets with thick coatings (∼20 μm) show surprisingly good weldability. High speed video camera visualizations of the keyhole provide insight into the keyhole dynamics during the process. It appears that the dynamic pressure of zinc vapour can effectively elongate the keyhole and the process can reach a stable state when an elongated keyhole is continuously present. A simple analytical model has been developed to describe the influence of zinc vapour on keyhole elongation.

Response of water vapour D-excess to land-atmosphere interactions in a semi-arid environment

KAUST Repository

Parkes, Stephen

2016-06-30

The stable isotopic composition of water vapour provides information about moisture sources and processes difficult to obtain with traditional measurement techniques. Recently, it has been proposed that the D-excess of water vapour can provide a diagnostic tracer of continental moisture recycling. However, D-excess exhibits a diurnal cycle that has been observed across a variety of ecosystems and may be influenced by a range of processes beyond regional-scale moisture recycling, including local evaporation (ET) fluxes. There is a lack of measurements of D-excess in evaporation (ET) fluxes, which has made it difficult to assess how ET fluxes modify the Dexcess in water vapour (dv). With this in mind, we employed a chamber-based approach to directly measure D-excess in ET (dET) fluxes. We show that ET fluxes imposed a negative forcing on the ambient vapour and could not explain the higher daytime dv values. The low dET observed here was sourced from a soil water pool that had undergone an extended drying period, leading to low D-excess in the soil moisture pool. A strong correlation between daytime dv and locally measured relative humidity was consistent with an oceanic moisture source, suggesting that remote hydrological processes were the major contributor to daytime dv variability. During the early evening, ET fluxes into a shallow nocturnal inversion layer caused a lowering of dv values near the surface. In addition, transient mixing of vapour with a higher D-excess from above the nocturnal inversion modified these values, causing large variability during the night. These results indicate dET can generally be expected to show

Spatially resolved δ13C analysis using laser ablation isotope ratio mass spectrometry

Science.gov (United States)

Moran, J.; Riha, K. M.; Nims, M. K.; Linley, T. J.; Hess, N. J.; Nico, P. S.

2014-12-01

Inherent geochemical, organic matter, and microbial heterogeneity over small spatial scales can complicate studies of carbon dynamics through soils. Stable isotope analysis has a strong history of helping track substrate turnover, delineate rhizosphere activity zones, and identifying transitions in vegetation cover, but most traditional isotope approaches are limited in spatial resolution by a combination of physical separation techniques (manual dissection) and IRMS instrument sensitivity. We coupled laser ablation sampling with isotope measurement via IRMS to enable spatially resolved analysis over solid surfaces. Once a targeted sample region is ablated the resulting particulates are entrained in a helium carrier gas and passed through a combustion reactor where carbon is converted to CO2. Cyrotrapping of the resulting CO2 enables a reduction in carrier gas flow which improves overall measurement sensitivity versus traditional, high flow sample introduction. Currently we are performing sample analysis at 50 μm resolution, require 65 ng C per analysis, and achieve measurement precision consistent with other continuous flow techniques. We will discuss applications of the laser ablation IRMS (LA-IRMS) system to microbial communities and fish ecology studies to demonstrate the merits of this technique and how similar analytical approaches can be transitioned to soil systems. Preliminary efforts at analyzing soil samples will be used to highlight strengths and limitations of the LA-IRMS approach, paying particular attention to sample preparation requirements, spatial resolution, sample analysis time, and the types of questions most conducive to analysis via LA-IRMS.

Optimization of post-run corrections for water stable isotope measurements by laser spectroscopy

Science.gov (United States)

van Geldern, Robert; Barth, Johannes A. C.

2013-04-01

Light stable isotope analyses of hydrogen and oxygen of water are used in numerous aquatic studies from various scientific fields. The advantage of using stable isotope ratios is that water molecules serve as ubiquitous and already present natural tracers. Traditionally, the samples were analyzed in the laboratory by isotope ratio mass spectrometry (IRMS). Within recent years these analyses have been revolutionized by the development of new isotope ratio laser spectroscopy (IRIS) systems that are said to be cheaper, more robust and mobile compared to IRMS. Although easier to operate, laser systems also need thorough calibration with international reference materials and raw data need correction for analytical effects. A major issue in systems that use liquid injection via a vaporizer module is the memory effect, i.e. the carry-over from the previous analyzed sample in a sequence. This study presents an optimized and simple post-run correction procedure for liquid water injection developed for a Picarro water analyzer. The Excel(TM) template will rely exclusively on standard features implemented in MS Office without the need to run macros, additional code written in Visual Basic for Applications (VBA) or to use a database-related software such as MS Access or SQL Server. These protocols will maximize precision, accuracy and sample throughput via an efficient memory correction. The number of injections per unknown sample can be reduced to 4 or less. This procedure meets the demands of faster throughput with reduced costs per analysis. Procedures were verified by an international proficiency test and traditional IRMS techniques. The template is available free for scientific use from the corresponding author or the journals web site (van Geldern and Barth, 2012). References van Geldern, R. and Barth, J.A.C. (2012) Limnol. Oceanogr. Methods 10:1024-1036 [doi: 10.4319/lom.2012.10.1024

Development of Stable Isotope Technology

International Nuclear Information System (INIS)

Jeong, Do Young; Kim, Cheol Jung; Han, Jae Min

2009-03-01

KAERI has obtained an advanced technology with singular originality for laser stable isotope separation. Objectives for this project are to get production technology of Tl-203 stable isotope used for medical application and are to establish the foundation of the pilot system, while we are taking aim at 'Laser Isotope Separation Technology to make resistance to the nuclear proliferation'. And we will contribute to ensuring a nuclear transparency in the world society by taking part in a practical group of NSG and being collaboration with various international groups related to stable isotope separation technology

Ground state properties of neutron-rich Mg isotopes the "island of inversion" studied with laser and $\\beta$-NMR spectroscopy

CERN Document Server

Kowalska, M

2006-01-01

Studies in regions of the nuclear chart in which the model predictions of properties of nuclei fail can bring a better understanding of the strong interaction in the nuclear medium. To such regions belongs the so called "island of inversion" centered around Ne, Na and Mg isotopes with 20 neutrons in which unexpected ground-state spins, large deformations and dense low-energy spectra appear. This is a strong argument that the magic N=20 is not a closed shell in this area. In this thesis investigations of isotope shifts of stable $^{24-26}$Mg, as well as spins and magnetic moments of short-lived $^{29,31}$Mg are presented. The successful studies were performed at the ISOLDE facility at CERN using collinear laser and $\\beta$-NMR spectroscopy techniques. The isotopes were investigated as single-charged ions in the 280 nm transition from the atomic ground state $^2\\!$S$_{1/2}$ to one of the two lowest excited states $^2\\!$P$_{1/2 ,\\,3/2}$ using continuous wave laser beams. The isotope-shift measurements with fluor...

Stable isotope ratio measurements on highly enriched water samples by means of laser spectrometry

NARCIS (Netherlands)

van Trigt, R; Kerstel, E.R.T.; Visser, GH; Meijer, H.A.J.

2001-01-01

We demonstrate the feasibility of using laser spectrometry (LS) to analyze isotopically highly enriched water samples (i.e., delta H-2 less than or equal to 15000 parts per thousand, delta O-18 less than or equal to 1200 parts per thousand), as often used in the biomedical doubly labeled water (DLW)

Laser spectroscopy and beta-NMR measurements of short-lived Mg isotopes

CERN Document Server

Kowalska, M

2005-01-01

The feasibility of studying the neutron-rich 29Mg, 31Mg and 33Mg isotopes has been demonstrated with the laser and beta-NMR spectroscopy setup at ISOLDE/CERN. The values of the magnetic moment and the nuclear spin of 31Mg are reported and reveal an intruder ground state. This proves the weakening of N=20 shell gap and places this nucleus inside the so called "island of inversion". The experimental setup and technique, as well as the results, are presented.

Determining Isotopic Composition of Dissolved Nitrate Using Bacterial Denitrification Followed by Laser Spectroscopy

International Nuclear Information System (INIS)

Yan Tiezhu; Lee Zhi Yi, Amelia; Heiling, Maria; Weltin, Georg; Toloza, Arsenio; Resch, Christian

2016-01-01

Nitrate (NO_3"-) pollution is a prevalent problem that can cause water quality degradation and eutrophication of water bodies. Quantifying the nitrogen and oxygen isotopic composition of nitrates will allow for better identification of their potential sources, which in turn will assist in remediation of contaminated water and the designing of future water management practices. In this research bacterial denitrification followed by laser spectroscopy are used to determine isotopic composition of δ"1"5N and δ"1"8O of dissolved nitrates. The objective of the project is to establish a standard operating procedure (SOP) that outlines the best practices for both methods in sequence and designed to be used as a technical guideline

Determining Isotopic Composition of Dissolved Nitrate Using Bacterial Denitrification Followed by Laser Spectroscopy

International Nuclear Information System (INIS)

Yan Tiezhu; Lee Zhi Yi, Amelia; Heiling, Maria; Weltin, Georg; Toloza, Arsenio; Resch, Christian

2016-01-01

Nitrate (NO 3 - ) pollution is a prevalent problem that can cause water quality degradation and eutrophication of water bodies. Quantifying the nitrogen and oxygen isotopic composition of nitrates will allow for better identification of their potential sources, which in turn will assist in remediation of contaminated water and the designing of future water management practices. In this research bacterial denitrification followed by laser spectroscopy are used to determine isotopic composition of δ 15 N and δ 18 O of dissolved nitrates. The objective of the project is to establish a standard operating procedure (SOP) that outlines the best practices for both methods in sequence and designed to be used as a technical guideline

Nuclear proliferation using laser isotope separation - Verification options

International Nuclear Information System (INIS)

Erickson, Stanley A.

2001-01-01

Full text: This paper discusses the use of laser isotope separation techniques for the purpose of nuclear proliferation by a Non-Nuclear Weapons State (NNWS) that is a signatory of the Non- Proliferation Treaty (NPT) and is subject to inspections by the IAEA. It includes an analysis of the feasibility of the technique by a NNWS, what conditions are necessary for success, what would be required for either the use of the technique as a covert enrichment method or its use as a non-declared adjunct to a declared enrichment facility, and what signs might be available for the detection of such activity. The Atomic Vapor Laser Isotope Separation (AVLIS) technology, developed by LLNL from 1973 through 1999, is used as a concrete example to allow more determination of the questions of feasibility, requirements, and signatures, as this technology has been further developed than others, and has been documented extensively. The question of feasibility of the technique for the enrichment of significant quantities of uranium or plutonium to produce weapons-grade materials is investigated by decomposing the development necessary for the technique into steps that can be analyzed for requirements, both in expertise, equipment, and scientific knowledge. The paper concludes that the technique is usable for proliferation, although with difficulty, by some nations during the next two decades. The technique may be developed in a completely covert method, with no declarations and no public indication that it is under research and development, or alternatively, some admissions may be made to allow or promote exchange of information. The technique can be disclosed as a research and development technology for the separation of non-radioactive isotopes, for the separation of radioactive isotopes including those in commercial use for medical or industrial purposes, or as part of a nuclear fuel cycle. The ability to translate development work from the first two of these to a system usable for

Catalytic recombination of dissociation products with Pt/SnO2 for rare and common isotope long-life, closed-cycle CO2 lasers

Science.gov (United States)

Brown, Kenneth G.; Sidney, B. D.; Schryer, D. R.; Upchurch, B. T.; Miller, I. M.

1986-01-01

This paper reports results on recombination of pulsed CO2 laser dissociation products with Pt/SnO2 catalysts, and supporting studies in a surrogate laboratory catalyst reactor. The closed-cycle, pulsed CO2 laser has been continuously operated for one million pulses with an overall power degradation of less than 5 percent by flowing the laser gas mixture through a 2-percent Pt/SnO2 catalyst bed. In the surrogate laboratory reactor, experiments have been conducted to determine isotopic exchange with the catalyst when using rare-isotope gases. The effects of catalyst pretreatment, sample weight, composition, and temperature on catalyst efficiency have also been determined.

The SILVA atomic process

International Nuclear Information System (INIS)

Cazalet, J.

1997-01-01

The SILVA laser isotope separation process is based on the laser selective photo-ionization of uranium atomic vapour; the process is presently under development by CEA and COGEMA in France, with the aim to reduce by a factor three the cost of uranium enrichment. The two main components of a SILVA process plant are the lasers (copper vapour lasers and dye lasers) and the separator for the vaporization (with a high energy electron beam), ionization and separation operations. Researches on the SILVA process started in 1985 and the technical and economical feasibility is to be demonstrated in 1997. The progresses of similar rival processes and other processes are discussed and the remaining research stages and themes of the SILVA program are presented

Vapour trap development and operational experience

International Nuclear Information System (INIS)

Jansing, W.; Kirchner, G.; Menck, J.

1977-01-01

Sodium aerosols have the unpleasant characteristic that they deposit at places with low temperature level. This effect can be utilized when sodium aerosols are to be trapped at places which are determined beforehand. Thus vapour traps were developed which can filter sodium vapour from the cover gas. By this means the necessity was eliminated to heat all gas lines and gas systems with trace heaters just as all sodium lines are heated. It was of special interest for the INTERATOM to develop vapour traps which must not be changed or cleaned after a certain limited operating period. The vapour traps were supposed to enable maintenance free operation, i.e. they were to operate 'self cleaning'

Hydrogen isotope correction for laser instrument measurement bias at low water vapor concentration using conventional isotope analyses: application to measurements from Mauna Loa Observatory, Hawaii.

Science.gov (United States)

Johnson, L R; Sharp, Z D; Galewsky, J; Strong, M; Van Pelt, A D; Dong, F; Noone, D

2011-03-15

The hydrogen and oxygen isotope ratios of water vapor can be measured with commercially available laser spectroscopy analyzers in real time. Operation of the laser systems in relatively dry air is difficult because measurements are non-linear as a function of humidity at low water concentrations. Here we use field-based sampling coupled with traditional mass spectrometry techniques for assessing linearity and calibrating laser spectroscopy systems at low water vapor concentrations. Air samples are collected in an evacuated 2 L glass flask and the water is separated from the non-condensable gases cryogenically. Approximately 2 µL of water are reduced to H(2) gas and measured on an isotope ratio mass spectrometer. In a field experiment at the Mauna Loa Observatory (MLO), we ran Picarro and Los Gatos Research (LGR) laser analyzers for a period of 25 days in addition to periodic sample collection in evacuated flasks. When the two laser systems are corrected to the flask data, they are strongly coincident over the entire 25 days. The δ(2)H values were found to change by over 200‰ over 2.5 min as the boundary layer elevation changed relative to MLO. The δ(2)H values ranged from -106 to -332‰, and the δ(18)O values (uncorrected) ranged from -12 to -50‰. Raw data from laser analyzers in environments with low water vapor concentrations can be normalized to the international V-SMOW scale by calibration to the flask data measured conventionally. Bias correction is especially critical for the accurate determination of deuterium excess in dry air. Copyright © 2011 John Wiley & Sons, Ltd.

Separation of rate processes for isotopic exchange between hydrogen and liquid water in packed columns 10

International Nuclear Information System (INIS)

Butler, J.P.; Hartog, J. den; Goodale, J.W.; Rolston, J.H.

1977-01-01

Wetproofed platinum catalysts in packed columns promote isotopic exchange between counter-current streams of hydrogen saturated with water vapour and liquid water. The net rate of deuterium transfer from isotopically enriched hydrogen has been measured and separated into two rate processes involving the transfer of deuterium from hydrogen to water vapour and from water vapour to liquid. These are compared with independent measurements of the two rate processes to test the two-step successive exchange model for trickle bed reactors. The separated transfer rates are independent of bed height and characterize the deuterium concentrations of each stream along the length of the bed. The dependences of the transfer rates upon hydrogen and liquid flow, hydrogen pressure, platinum loading and the effect of dilution of the hydrophobic catalyst with inert hydrophilic packing are reported. The results indicate a third process may be important in the transfer of deuterium between hydrogen and liquid water. (author)

Isotope separation apparatus and method

International Nuclear Information System (INIS)

Cotter, T.P.

1982-01-01

The invention relates to a method and apparatus for laser isotope separation by photodeflection. A molecular beam comprising at least two isotopes to be separated intersects, preferable substantially perpendicular to one broad side of the molecular beam, with a laser beam traveling in a first direction. The laser beam is reflected back through the molecular beam, preferably in a second direction essentially opposite to the first direction. The laser beam comprises pi-pulses of a selected wavelength which excite unexcited molecules, or cause stimulated emission of excited molecules of one of the isotopes. Excitation caused by first direction pi-pulses moves molecules of the isotope excited thereby in the first direction. Stimulated emission of excited molecules of the isotope is brought about by returning pi-pulses traveling in the second direction. Stimulated emission moves emitting molecules in a direction opposite to the photon emitted. Because emitted photons travel in the second direction, emitting molecules move in the first direction. Substantial molecular movement is accomplished by a large number of pi-pulse-molecule interactions. A beam corer collects the molecules in the resulting enriched divergent portions of the beam

Characteristic analysis of laser isotope separation process by two-step photodissociation method

International Nuclear Information System (INIS)

Okamoto, Tsuyoshi; Suzuki, Atsuyuki; Kiyose, Ryohei

1981-01-01

A large number of laser isotope separation experiments have been performed actively in many countries. In this paper, the selective two-step photodissociation method is chosen and simultaneous nonlinear differential equations that express the separation process are solved directly by using computer. Predicted separation factors are investigated in relation to the incident pulse energy and the concentration of desired molecules. Furthermore, the concept of separative work is used to evaluate the results of separation for this method. It is shown from an example of numerical calculation that a very large separation factor can be obtained if the concentration of desired molecules is lowered and two laser pulses to be closely synchronized are not always required in operation for the photodissociation of molecules. (author)

The Laboratory for Laser Energetics’ Hydrogen Isotope Separation System

Energy Technology Data Exchange (ETDEWEB)

Shmayda, W.T., E-mail: wshm@lle.rochester.edu; Wittman, M.D.; Earley, R.F.; Reid, J.L.; Redden, N.P.

2016-11-01

The University of Rochester’s Laboratory for Laser Energetics has commissioned a hydrogen Isotope Separation System (ISS). The ISS uses two columns—palladium on kieselguhr and molecular sieve—that act in a complementary manner to separate the hydrogen species by mass. The 4-sL per day throughput system is compact and has no moving parts. The columns and the attendant gas storage and handling subsystems are housed in a 0.8 -m{sup 3} glovebox. The glovebox uses a helium cover gas that is continuously processed to extract oxygen and water vapor that permeates through the glovebox gloves and any tritium that is released while attaching or detaching vessels to add feedstock to or drawing product from the system. The isotopic separation process is automated and does not require manual intervention. A total of 315 TBq of tritium was extracted from 23.6 sL of hydrogen with tritium purities reaching 99.5%. Deuterium was the sole residual component in the processed gas. Raffinate contained 0.2 TBq of activity was captured for reprocessing. The total emission from the system to the environment was 0.4 GBq over three weeks.

The response of liquid-filled pipes to vapour collapse

International Nuclear Information System (INIS)

Tijsseling, A.S.; Fan, D.

1991-01-01

The collapse of vapour cavities in liquid is usually accompanied with almost instantaneous pressure rises. These pressure rises impose severe loads on liquid-conveying pipes whenever the cavities become sufficiently large. Due to the impact nature of loadings, movement of the pipe walls can be expected. Tests are performed in a water-filled closed pipe suspended by thin steel wires. Vaporous cavities are induced in the liquid by hitting the pipe axially by a steel rod. The volume of the cavities can be varied by changing the initial pressure of the water. The developing and collapsing of cavities in the liquid is inferred from pressure measurements. Strain gauges and a laser Doppler vibrometer are used to record the response of the pipe to these pressures. The test results are compared with predictions from a numerical model. The model describes 1) axial stress wave propagations in the pipe and 2) water hammer and cavitation phenomena in the liquid. Pipe and liquid interact via 1) the radial expansion and contraction of the pipe wall and 2) the closed ends of the pipe, where large vapour cavities may develop. (author)

Stable carbon isotope analyses of nanogram quantities of particulate organic carbon (pollen) with laser ablation nano combustion gas chromatography/isotope ratio mass spectrometry

Science.gov (United States)

Sluijs, Appy; Laks, Jelmer J.; Reichart, Gert‐Jan

2016-01-01

Rationale Analyses of stable carbon isotope ratios (δ 13C values) of organic and inorganic matter remains have been instrumental for much of our understanding of present and past environmental and biological processes. Until recently, the analytical window of such analyses has been limited to samples containing at least several μg of carbon. Methods Here we present a setup combining laser ablation, nano combustion gas chromatography and isotope ratio mass spectrometry (LA/nC/GC/IRMS). A deep UV (193 nm) laser is used for optimal fragmentation of organic matter with minimum fractionation effects and an exceptionally small ablation chamber and combustion oven are used to reduce the minimum sample mass requirement compared with previous studies. Results Analyses of the international IAEA CH‐7 polyethylene standard show optimal accuracy, and precision better than 0.5‰, when measuring at least 42 ng C. Application to untreated modern Eucalyptus globulus (C3 plant) and Zea mays (C4 plant) pollen grains shows a ~ 16‰ offset between these species. Within each single Z. mays pollen grain, replicate analyses show almost identical δ 13C values. Conclusions Isotopic offsets between individual pollen grains exceed analytical uncertainties, therefore probably reflecting interspecimen variability of ~0.5–0.9‰. These promising results set the stage for investigating both δ 13C values and natural carbon isotopic variability between single specimens of a single population of all kinds of organic particles yielding tens of nanograms of carbon. © 2016 The Authors. Rapid Communications in Mass Spectrometry Published by John Wiley & Sons Ltd. PMID:27766694

Water vapour and wind measurements by a two micron space lidar

Science.gov (United States)

Ghibaudo, J.-B.; Labandibar, J.-Y.

2018-04-01

AEROSPATIALE presents the main results of the feasibility study under ESA contract on a coherent 2μm lidar instrument capable of measuring water vapour and wind velocity in the planetary boundary layer. The selected instrument configuration and the associated performance are provided, and the main critical subsystems identified (laser configuration, coherent receiver chain architecture, frequency locking and offsetting architecture. The second phase of this study is dedicated to breadboard the most critical elements of such an instrument in order to technologically consolidate its feasibility.

Application of laser ablation inductively coupled plasma multicollector mass spectometry in determination of lead isotope ratios in common glass for forensic purposes

International Nuclear Information System (INIS)

Sjåstad, Knut-Endre; Andersen, Tom; Simonsen, Siri Lene

2013-01-01

Samples of glass used as trace evidence in criminal cases are commonly small, with particle sizes below a millimeter. To perform chemical analysis suitable for forensic purposes, methods capable of analyzing such small samples are required. In this paper, analyses of lead isotope ratios by means of laser ablation inductively coupled multicollector mass spectrometry (LA-MC-ICP-MS) are presented. Sampling by use of laser ablation allows fragments down to 0.1 mg to be analyzed with sufficient precision to discriminate between glasses of different origin. In fact, the use of lead isotopes determined by LA-MC-ICP-MS approaches the discrimination attainable by multicollector inductively coupled plasma mass spectrometry (MC-ICP-MS) analysis of dissolved samples of 5 mg or more. Further, we have obtained a probability distribution by two dimensional kernel density estimates for the collected data set as an alternative presentation method to the well-established bivariate plot. The underlying information available from kernel density estimates is of importance for forensic scientists involved in probabilistic interpretation of physical evidence. - Highlights: • Lead isotope ratios prove suitable to discriminate glass for forensic purposes. • 96% of glass samples from different sources were separated by lead isotopic ratios. • Laser ablation allows fragments of glass with extension of 0.5 mm to be analyzed. • Isotopic ratios of lead are well suited for statistical analysis of evidence

Atomic collisions related to atomic laser isotope separation

International Nuclear Information System (INIS)

Shibata, Takemasa

1995-01-01

Atomic collisions are important in various places in atomic vapor laser isotope separation (AVLIS). At a vaporization zone, many atomic collisions due to high density have influence on the atomic beam characteristics such as velocity distribution and metastable states' populations at a separation zone. In the separation zone, a symmetric charge transfer between the produced ions and the neutral atoms may degrade selectivity. We have measured atomic excitation temperatures of atomic beams and symmetric charge transfer cross sections for gadolinium and neodymium. Gadolinium and neodymium are both lanthanides. Nevertheless, results for gadolinium and neodymium are very different. The gadolinium atom has one 5d electron and neodymium atom has no 5d electron. It is considered that the differences are due to existence of 5d electron. (author)

Optimal laser control of molecular wave packet dynamics under the influence of dissipation: possibility of isotope separation

International Nuclear Information System (INIS)

Ohtsuki, Yukiyoshi

2004-01-01

Possibility of fs-laser-pulse isotope separation is numerically investigated using optimal control theory. Optimal pulses that separate the 1:1 mixture of 79 Br 2 and 28 1 Br 2 are calculated. Quantum interferences induced by the optimally designed fs pulse efficiently enhance the isotope shifts through multiple electronic transitions, which results in a high enrichment factor. When utilizing vibrational multi-photon transitions (a virtual model), an optimal pulse can transfer the two isotopes to specified different vibrational states with almost 100% probability. In the presence of colored noises, the optimal pulse achieves the control with minimum loss of product yields within the bath correlation time. (author)

Elucidation of C{sub 2} and CN formation mechanisms in laser-induced plasmas through correlation analysis of carbon isotopic ratio

Energy Technology Data Exchange (ETDEWEB)

Dong, Meirong [School of Electric Power, South China University of Technology, Guangzhou, Guangdong 510640 (China); Lawrence Berkeley National Laboratory, Berkeley, CA 94720 (United States); Chan, George C.-Y.; Mao, Xianglei; Gonzalez, Jhanis J. [Lawrence Berkeley National Laboratory, Berkeley, CA 94720 (United States); Lu, Jidong [School of Electric Power, South China University of Technology, Guangzhou, Guangdong 510640 (China); Russo, Richard E., E-mail: RERusso@lbl.gov [Lawrence Berkeley National Laboratory, Berkeley, CA 94720 (United States)

2014-10-01

Laser ablation molecular isotopic spectrometry (LAMIS) was recently reported for rapid isotopic analysis by measuring molecular emission from laser-induced plasmas at atmospheric pressure. With {sup 13}C-labeled benzoic acid as a model sample, this research utilized the LAMIS approach to clarify the formation mechanisms of C{sub 2} and CN molecules during laser ablation of organic materials. Because the isotopic ratios in the molecular bands could deviate from statistical distribution depending on their formation pathways, the dominant mechanism can be identified through a comparison of the experimental observed isotopic patterns in the molecular emission with the theoretical statistical pattern. For C{sub 2} formation, the experimental {sup 12}C{sup 12}C/{sup 13}C{sup 12}C ratios not only support a recombination mechanism through atomic carbon at early delay time but also indicate the presence of other operating mechanisms as the plasma evolves; it is proposed that some of the C{sub 2} molecules are released directly from the aromatic ring of the sample as molecular fragments. In contrast, the temporal profiles in the {sup 12}C/{sup 13}C ratios derived from CN emission exhibited opposite behavior with those derived from C{sub 2} emission, which unambiguously refutes mechanisms that require C{sub 2} as a precursor for CN formation; CN formation likely involves atomic carbon or species with a single carbon atom. - Highlights: • C{sub 2} and CN formation mechanisms during laser ablation of organic material studied • Some C{sub 2} molecules are directly desorbed from the organic compound. • C{sub 2} molecules are not important precursor for CN-radical formation.

Optimizing design parameter for light isotopes separation by distillation method

International Nuclear Information System (INIS)

Ahmadi, M.

1999-01-01

More than methods are suggested in the world for producing heavy water, where between them chemical isotopic methods, distillation and electro lys are used widely in industrial scale. To select suitable method for heavy water production in Iran, taking into consideration, domestic technology an facilities, combination of hydrogen sulphide-water dual temperature process (Gs) and distillation (D W) may be proposed. Natural water, is firstly enriched up to 15 a% by G S process and then by distillation unit is enriched up to the grade necessary for Candu type reactors (99.8 a%). The aim of present thesis, is to achieve know-how, optimization of design parameters, and executing basic design for water isotopes separation using distillation process in a plant having minimum scale possible. In distillation, vapour phase resulted from liquid phase heating, is evidently composed of the same constituents as liquid phase. In isotopic distillation, the difference in composition of constituents is not considerable. In fact alteration of constituents composition is so small that makes the separation process impossible, however, direct separation and production of pure products without further processing which becomes possible by distillation, makes this process as one of the most important separation processes. Profiting distillation process to produce heavy water is based on difference existing between boiling point of heavy and light water. The trends of boiling points differences (heavy and light water) is adversely dependant with pressure. As the whole system pressure decreases, difference in boiling points increases. On the other hand according to the definition, separation factor is equal to the ratio of pure light water vapour pressure to that of heavy water, or we can say that the trend of whole system pressure decrease results in separation factor increase, which accordingly separation factor equation to pressure variable should be computed firstly. According to the

Feasibility studies on macroscopic separation of carbon isotopes by IR laser chemistry - a technical report

International Nuclear Information System (INIS)

Mathi, P.; Nayak, A.K.; Parthasarathy, V.; Abhinandan, L.; Sarkar, S.K.

2007-11-01

This report describes the feasibility studies for macroscopic separation of carbon isotopes (∼ 50% enrichment level) by infrared multiphoton dissociation (IRMPD) of Freon - 22 (CF 2 HCl) using a 10Hz pulsed carbon dioxide laser in a large volume (∼ 300 litre) photochemical reactor (PCR). After a general introduction to the objective, the importance of characterization studies with a 10 Hz CO 2 laser is brought out before large scale operation in the PCR is carried out. The laboratory scale results obtained in a small cell with a lower average power (0.5 W) CO 2 laser is verified with a higher power (10 W) laser under optimal conditions. Such an exercise helps in understanding of any anomalies of the results and for applying the appropriate corrective measures while scaling up. The report deals with the design details, fabrication, installation and commissioning of the major components of the setup namely laser system, photochemical reactor, low temperature distillation unit and preparative gas chromatograph for realizing the targeted task. It further describes the standardization methodology of a sensitive analytical technique using quadrupole mass spectrometry (QMS) to ascertain the C 2 F 4 product quality (i.e. enrichment). A pre- concentration method for separating C 2 F 4 from CF 2 HCl using gas chromatography has been developed for very low-level mass spectral analysis. During this exercise, an indigenous QMS developed in VPID (erstwhile MS and ES) has also been benchmarked by comparing its performance with a commercial QMS unit. The report gives in details the operational experience of carrying out the large scale enrichment task in a batch process. The modular PCR employing a multi-pass refocusing Herriott optics for efficient photon utilization and gas blower arrangement for gas circulation during laser photolysis has given a typical production rate of about 10 mg/hr for total carbon with a 13 C isotopic purity of ∼ 40%. It further indicates the scope

Laser isotope separation process

International Nuclear Information System (INIS)

Kaldor, A.

1976-01-01

The claimed invention is a method of isotope separation based on the unimolecular decomposition of vibrationally excited negative ions which are produced in the reaction of thermal electrons and molecules which have been vibrationally excited in an isotope selective manner. This method is especially applicable to molecules represented by the formula MF 6 wherein M is selected from the group consisting of U, S, W, Se, Te, Mo, Re, and Tc. 9 claims, 1 drawing figure

Spins, charge radii and magnetic moments of neutron-rich Mn isotopes measured with bunched beam Collinear Laser Spectroscopy

CERN Document Server

AUTHOR|(CDS)2085887; Heylen, Hanne

In this work, the odd-even $^{51–63}$Mn isotopes have been analyzed using collinear laser spectroscopy, from which the magnetic dipole moment and the change in change in mean square charge radius can be determined. The magnetic moment is very sensitive to the composition of the total nuclear wave function, while the charge radius gives information about the relative size and degree of deformation of the nucleus. An additional advantage of collinear laser spectroscopy is the possibility of direct measurement of the nuclear spin. The main motivation behind the study of these isotopes is to investigate the change in nuclear structure when approaching neutron number N = 40. This region is of interest due to the apparent doubly magic nature of $^{68}$Ni , which is not seen in the N = 40 isotopes of $^{26}$Fe and $^{24}$Cr. Mn, situated between these elements, offers another perspective due to its uncoupled proton. Based on the observed spectra and extracted moments, spins were assigned to $^{59,61,63}$Mn. The ex...

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

Science.gov (United States)

Sankari, M

2012-10-15

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

Tunable lasers in isotope separation: a colorful view of a dye chemist

International Nuclear Information System (INIS)

Hammond, P.R.

1977-01-01

Some of the problems to be encountered in the possible large scale use of dye lasers in an isotope separation plant are discussed.The effect of laser dye deterioration on performance is examined algebraically in terms of disappearance of dye molecules and the appearance of a new, single chemical product having absorption in the fluorescence band for a single pass through a transversely pumped amplifier. Loss of output, defined as ''quantum yield of laser deterioration'', Q/sub L/, is related to the true quantum yield of molecular destruction of the dye Q/sub M/, and other known parameters. 6-Diethylamino 3-keto fluoran, an example of an oxygen tricyclic merocyanine, is described. It was first reported in the pre-1900 German literature under the name of Chromogen Red B and it is an ineffective lasing dye on account of low fluorescence quantum yield. The techniques for measurement and the excited state absorption cross-sections are reported for the dyes rhodamine 6G fluoroborate in alcohol, rhodamine B basic solution in trifluoroethanol and kiton red S in trifluoroethanol

Calculations on isotope separation by laser induced photodissociation of polyatomic molecules. Final report

International Nuclear Information System (INIS)

Lamb, W.E. Jr.

1978-11-01

This report describes research on the theory of isotope separation produced by the illumination of polyatomic molecules by intense infrared laser radiation. Newton's equations of motion were integrated for the atoms of the SF 6 molecule including the laser field interaction. The first year's work has been largely dedicated to obtaining a suitable interatomic potential valid for arbitrary configurations of the seven particles. This potential gives the correct symmetry of the molecule, the equilibrium configuration, the frequencies of the six distinct normal modes of oscillation and the correct (or assumed) value of the total potential energy of the molecule. Other conditions can easily be imposed in order to obtain a more refined potential energy function, for example, by making allowance for anharmonicity data. A suitable expression was also obtained for the interaction energy between a laser field and the polyatomic molecule. The electromagnetic field is treated classically, and it would be easily possible to treat the cases of time dependent pulses, frequency modulation and noise

The potential of perennial cave ice in isotope palaeoclimatology

International Nuclear Information System (INIS)

Yonge, Charles J.; MacDonald, William D.

1999-01-01

Perennial ice from caves on and to the east of the Canadian Great Divide yield delta O 18 and delta D values which are usually high measurements where compared with the average precipitation for the region. Furthermore, these ice data fall below and along lines of lower slope than the Global Meteoric Water Line. To explain the observed relationships, we propose the following process. a vapour-ice isotopic fractionation mechanism operates on warm season vapour when it precipitates as hoar ice on entering the caves. The subsequent fall of hoar to the cave floor through mechanical overloading along with ice derived from ground-water seepage (with a mean annual isotopic composition), results in massive ice formation of a mixed composition. This mixed composition is what is observed in the characteristic relationships found here. Such findings suggest that a warm versus cold climate interpretation for ancient cave ice may be the opposite of that found in the more familiar polar and glacial ice caves. (Author) 3 figs., 1 tab., 12 refs

Resonance absorption spectroscopy for laser-ablated lanthanide atom. (1) Optimized experimental conditions for isotope-selective absorption of gadolinium (Contract research)

International Nuclear Information System (INIS)

Miyabe, Masabumi; Oba, Masaki; Iimura, Hideki; Akaoka, Katsuaki; Maruyama, Yoichiro; Wakaida, Ikuo; Watanabe, Kazuo

2008-06-01

For remote isotope analysis of low-decontaminated TRU fuel, we are developing an analytical technique on the basis of the resonance absorption spectroscopy for the laser-ablation plume. To improve isotopic selectivity and detection sensitivity of this technique, we measured absorption spectra of Gd atom with various plume production conditions (ablation laser intensity, ambient gas and its pressure) and observation conditions (transition, probe height from sample, observation timing). As a result, high resolution spectrum was obtained from the observation of slow component of the plume produced under low-pressure rare-gas ambient. The observed narrowest linewidth of about 0.85GHz was found to be close to the Doppler width estimated for Gd atom of room temperature. Furthermore, relaxation rate of higher meta-stable state was found to be higher than that of ground state, suggesting that use of the transition arising from ground state or lower meta-stable state is preferable for highly sensitive isotope analysis. (author)

The water vapour continuum in near-infrared windows - Current understanding and prospects for its inclusion in spectroscopic databases

Science.gov (United States)

Shine, Keith P.; Campargue, Alain; Mondelain, Didier; McPheat, Robert A.; Ptashnik, Igor V.; Weidmann, Damien

2016-09-01

Spectroscopic catalogues, such as GEISA and HITRAN, do not yet include information on the water vapour continuum that pervades visible, infrared and microwave spectral regions. This is partly because, in some spectral regions, there are rather few laboratory measurements in conditions close to those in the Earth's atmosphere; hence understanding of the characteristics of the continuum absorption is still emerging. This is particularly so in the near-infrared and visible, where there has been renewed interest and activity in recent years. In this paper we present a critical review focusing on recent laboratory measurements in two near-infrared window regions (centred on 4700 and 6300 cm-1) and include reference to the window centred on 2600 cm-1 where more measurements have been reported. The rather few available measurements, have used Fourier transform spectroscopy (FTS), cavity ring down spectroscopy, optical-feedback - cavity enhanced laser spectroscopy and, in very narrow regions, calorimetric interferometry. These systems have different advantages and disadvantages. Fourier Transform Spectroscopy can measure the continuum across both these and neighbouring windows; by contrast, the cavity laser techniques are limited to fewer wavenumbers, but have a much higher inherent sensitivity. The available results present a diverse view of the characteristics of continuum absorption, with differences in continuum strength exceeding a factor of 10 in the cores of these windows. In individual windows, the temperature dependence of the water vapour self-continuum differs significantly in the few sets of measurements that allow an analysis. The available data also indicate that the temperature dependence differs significantly between different near-infrared windows. These pioneering measurements provide an impetus for further measurements. Improvements and/or extensions in existing techniques would aid progress to a full characterisation of the continuum - as an example, we

System and method of plasma particle separation

International Nuclear Information System (INIS)

Schmidt, G.; Halpern, G.M.; Thomas, W.R.L.

1975-01-01

Several examples of the design are described to ionize flowing uranium or UF 6 vapour through laser beam and to conduct the thus produced flowing plasma into the region of a magnetic field gradient separating the isotopes. (GG/LH) [de

Laser fluorescence on radioactive isotopes produced in very low yield

International Nuclear Information System (INIS)

Wells, S.A.; Evans, D.E.; Griffith, J.A.R.; Eastham, D.A.; Groves, J.; Tolfree, D.W.L.; Warner, D.D.; Dancy, M.P.; Billowes, J.; Grant, I.S.; Walker, P.M.

1990-01-01

Heavy ion accelerators such as the NSF at Daresbury Laboratory are capable of producing a wide variety of radio-active beams. The intensities of the beams of atoms or ions are always modest, and ultra-sensitive methods are needed to observe laser-induced fluorescence. The fast ion-photon coincidence technique has been applied to neutron-deficient barium ions down to 120 Ba. Nuclear moments and changes in charge radii have been determined from the measured hyperfine splittings and isotope shifts. An abrupt increase in the mean square radius is observed at 121 Ba, large enough to disrupt the systematic staggering seen for the isotopic series. The hyperfine structure has also been observed for an isomeric state of 127 Ba which has a lifetime of about 2 seconds. The measurements lead to an unambiguous assignment of the spin of the isomer. Another technique has been tested with stable krypton atoms. Fluorescent photons in the VUV wavelength region are detected with a high efficiency using a channel plate detector. The background is small enough that it should be possible to measure hyperfine spectra on beams with fewer than 10 3 atoms per second

[Qualitative Determination of Organic Vapour Using Violet and Visible Spectrum].

Science.gov (United States)

Jiang, Bo; Hu, Wen-zhong; Liu, Chang-jian; Zheng, Wei; Qi, Xiao-hui; Jiang, Ai-li; Wang, Yan-ying

2015-12-01

Vapours of organic matters were determined qualitatively employed with ultraviolet-visible absorption spectroscopy. Vapours of organic matters were detected using ultraviolet-visible spectrophotometer employing polyethylene film as medium, the ultraviolet and visible absorption spectra of vegetable oil vapours of soybean oil, sunflower seed oil, peanut oil, rapeseed oil, sesame oil, cotton seed oil, tung tree seed oil, and organic compound vapours of acetone, ethyl acetate, 95% ethanol, glacial acetic acid were obtained. Experimental results showed that spectra of the vegetable oil vapour and the organic compound vapour could be obtained commendably, since ultra violet and visible spectrum of polyethylene film could be deducted by spectrograph zero setting. Different kinds of vegetable oils could been distinguished commendably in the spectra since the λ(max), λ(min), number of absorption peak, position, inflection point in the ultra violet and visible spectra obtained from the vapours of the vegetable oils were all inconsistent, and the vapours of organic compounds were also determined perfectly. The method had a good reproducibility, the ultraviolet and visible absorption spectra of the vapours of sunflower seed oil in 10 times determination were absolutely the same. The experimental result indicated that polyethylene film as a kind of medium could be used for qualitative analysis of ultraviolet and visible absorption spectroscopy. The method for determination of the vapours of the vegetable oils and organic compounds had the peculiarities of fast speed analysis, well reproducibility, accuracy and reliability and low cost, and so on. Ultraviolet and visible absorption spectrum of organic vapour could provide feature information of material vapour and structural information of organic compound, and provide a novel test method for identifying vapour of compound and organic matter.

Noise-cancelled, cavity-enhanced saturation laser spectroscopy for laser frequency stabilisation

International Nuclear Information System (INIS)

Vine, Glenn de; McClelland, David E; Gray, Malcolm B

2006-01-01

We employ a relatively simple experimental technique enabling mechanical-noise free, cavityenhanced spectroscopic measurements of an atomic transition and its hyperfine structure. We demonstrate this technique with the 532 nm frequency doubled output from a Nd:YAG laser and an iodine vapour cell. The resulting cavity-enhanced, noise-cancelled, iodine hyperfine error signal is used as a frequency reference with which we stabilise the frequency of the 1064nm Nd:YAG laser. Preliminary frequency stabilisation results are then presented

Stabilization of Leidenfrost vapour layer by textured superhydrophobic surfaces

KAUST Repository

Vakarelski, Ivan Uriev

2012-09-12

In 1756, Leidenfrost observed that water drops skittered on a sufficiently hot skillet, owing to levitation by an evaporative vapour film. Such films are stable only when the hot surface is above a critical temperature, and are a central phenomenon in boiling. In this so-called Leidenfrost regime, the low thermal conductivity of the vapour layer inhibits heat transfer between the hot surface and the liquid. When the temperature of the cooling surface drops below the critical temperature, the vapour film collapses and the system enters a nucleate-boiling regime, which can result in vapour explosions that are particularly detrimental in certain contexts, such as in nuclear power plants. The presence of these vapour films can also reduce liquid-solid drag. Here we show how vapour film collapse can be completely suppressed at textured superhydrophobic surfaces. At a smooth hydrophobic surface, the vapour film still collapses on cooling, albeit at a reduced critical temperature, and the system switches explosively to nucleate boiling. In contrast, at textured, superhydrophobic surfaces, the vapour layer gradually relaxes until the surface is completely cooled, without exhibiting a nucleate-boiling phase. This result demonstrates that topological texture on superhydrophobic materials is critical in stabilizing the vapour layer and thus in controlling-by heat transfer-the liquid-gas phase transition at hot surfaces. This concept can potentially be applied to control other phase transitions, such as ice or frost formation, and to the design of low-drag surfaces at which the vapour phase is stabilized in the grooves of textures without heating. © 2012 Macmillan Publishers Limited. All rights reserved.

Stabilization of Leidenfrost vapour layer by textured superhydrophobic surfaces

KAUST Repository

Vakarelski, Ivan Uriev; Patankar, Neelesh A.; Marston, Jeremy; Chan, Derek Y C; Thoroddsen, Sigurdur T

2012-01-01

In 1756, Leidenfrost observed that water drops skittered on a sufficiently hot skillet, owing to levitation by an evaporative vapour film. Such films are stable only when the hot surface is above a critical temperature, and are a central phenomenon in boiling. In this so-called Leidenfrost regime, the low thermal conductivity of the vapour layer inhibits heat transfer between the hot surface and the liquid. When the temperature of the cooling surface drops below the critical temperature, the vapour film collapses and the system enters a nucleate-boiling regime, which can result in vapour explosions that are particularly detrimental in certain contexts, such as in nuclear power plants. The presence of these vapour films can also reduce liquid-solid drag. Here we show how vapour film collapse can be completely suppressed at textured superhydrophobic surfaces. At a smooth hydrophobic surface, the vapour film still collapses on cooling, albeit at a reduced critical temperature, and the system switches explosively to nucleate boiling. In contrast, at textured, superhydrophobic surfaces, the vapour layer gradually relaxes until the surface is completely cooled, without exhibiting a nucleate-boiling phase. This result demonstrates that topological texture on superhydrophobic materials is critical in stabilizing the vapour layer and thus in controlling-by heat transfer-the liquid-gas phase transition at hot surfaces. This concept can potentially be applied to control other phase transitions, such as ice or frost formation, and to the design of low-drag surfaces at which the vapour phase is stabilized in the grooves of textures without heating. © 2012 Macmillan Publishers Limited. All rights reserved.

Diode laser absorption spectrometry for (CO2)-C-13/(CO2)-C-12 isotope ratio analysis : Investigation on precision and accuracy levels

NARCIS (Netherlands)

Castrillo, A; Casa, G; Kerstel, E; Gianfrani, L

2005-01-01

Near-infrared laser spectroscopy is used to measure the C-13/C-12 isotope abundance ratio in gas phase carbon dioxide. The spectrometer, developed expressly for field applications, is based on a 2 mu m distributed feedback diode laser in combination with sensitive wavelength modulation detection. It

Effects of the copper vapour laser radiation in the root canal wall dentine: in vitro experiment using scanning electron microscopy and stereoscopy

International Nuclear Information System (INIS)

Silveira, Maria Claudia Garcia da

2001-01-01

Ten human uniradicular teeth had their crown removed along the cement-enamel junction and right away a proper chemical-surgical preparation of the radicular canals was done; the roots were longitudinally sectioned in order to allow the irradiation of the surfaces of the root canals wall dentine. The hemi-roots were separated in two groups: group I (control), with four hemi-roots, not irradiated; and group II, with 16 hemi-roots, subdivided in four sub-groups submitted to the following exposition time: 0,02 s; 0,05 s; 0,1 s and 0,5 s. A copper vapour laser was used with a 510,6 nm wavelength, total average power of 11 W in green and yellow emissions; average power of 6,5 W in green emission; pulse repetition rate of 16.000 Hz and pulse duration of 30 ns. The pulse energy (green line) is 0,4 mJ and the peak power 13,5 W. The laser cavity is unstable type (R 1 =3.900 mm and R 2 -250 mm). The focusing have focal length lens f 1 =250 mm and f 2 =150 mm. The beam quality is of the M 2 =5. The results obtained by scanning electron microscopy analysis showed the appearance of a cavity in the region of the laser beam incidence in the edges of this cavity, dentin was melt and resolidified presenting also cracks due to heat diffusion. Based on these results, we concluded that the size of the cavity formed in the dentin is directly proportional to the rate of exposure and, the more laser emission in the same area, more damage in the root canals wall dentin occurs. More studies need to be done with different exposition's time in order to obtain a safety protocol that does not cause injury in dental and support tissue. (author)

Isotope separation of 17O by photodissociation of ozone with near-infrared laser irradiation

Science.gov (United States)

Hayashida, Shigeru; Kambe, Takashi; Sato, Tetsuya; Igarashi, Takehiro; Kuze, Hiroaki

2012-04-01

Oxygen-17 is a stable oxygen isotope useful for various diagnostics in both engineering and medical applications. Enrichment of 17O, however, has been very costly due to the lack of appropriate methods that enable efficient production of 17O on an industrial level. In this paper, we report the first 17O-selective photodissociation of ozone at a relatively high pressure, which has been achieved by irradiating a gas mixture of 10 vol% O3-90 vol% CF4 with narrowband laser. The experiment was conducted on a pilot-plant scale. A total laser power of 1.6 W was generated by external-cavity diode lasers with all the laser wavelengths fixed at the peak of an absorption line of 16O16O17O around 1 μm. The beams were introduced into a 25 -m long photoreaction cell under the sealed-off condition with a total pressure of 20 kPa. Lower cell temperature reduced the background decomposition of ozone, and at the temperature of 158 K, an 17O enrichment factor of 2.2 was attained.

Laser photochemical separation of hydrogen isotopes

International Nuclear Information System (INIS)

Fowler, M.C.

1979-01-01

A method of separating isotopes of hydrogen utilizing isotopically selective photodissociation of organic acid is disclosed. Specifically acetic or formic acid containing compounds of deuterated nd hydrogenated acid is irradiated by radiation having a wavelength in the infrared spectrum between 9.2 to 10.8 microns to produce deuterium hydroxide and deuterium hydride respectively. Maintaining the acid at an elevated temperature significantly improves the yield of isotope separation

Increasing Precision and Accuracy of Laser Isotope Analyser Data

International Nuclear Information System (INIS)

Chen, Janet; Mayr, Leopold; Resch, Christian; Dercon, Gerd

2017-01-01

Isotope analysis with laser spectroscopy is an emerging technology that is growing in scientific demand. Because this technology allows for real-time, in situ measurements of carbon-13 ("1"3C) and nitrogen-15 ("1"5N) of CO_2, CH_4 and N_2O, it is increasingly being used to monitor fluxes of these greenhouse gases. However, despite its potential to provide robust data to researchers, methods of calibration and data correction are still being developed and refined. Furthermore, standard reference gases are currently not available and researchers must make their own gases to ensure proper calibration and data correction. To improve quality of data and allow for comparison of data between studies, it is essential that standard CO_2, CH_4 and N_2O gases are accessible to researchers.

Laser spectroscopy of laser-desorbed gold isotopes

International Nuclear Information System (INIS)

Savard, G.; Crawford, J.E.; Lee, J.K.P.; Thekkadath, G.

1990-01-01

Changes in mean-square charge radius δ 2 >, and magnetic dipole moments μ I have been measured for a series of neutron-deficient gold isotopes between A=186 and 196, and for neutron-rich 198,199 Au, using the PILIS system on-line with the ISOCELE mass separator. These measurements confirm the existence of the shape transition between A=186 and 187. The measured μ I values have been compared with calculations using Nilsson, and symmetric-rotor-plus-quasiparticle models. The results are consistent with the interpretation that 186 Au is prolate, and that the heavier isotopes have oblate, or possibly triaxial deformation. (orig.)

Direct measurement of burn up monitor by Pulsed Laser Deposition (PLD) followed by Isotopic Dilution Mass Spectrometry

International Nuclear Information System (INIS)

Sajimol, R.; Manoravi, P.; NaIini, S.; Balasubramanian, R.; Joseph, M.

2012-01-01

Burn-up measurement is an important aspect in the assessment of fuel performance especially for experimental nuclear fuels. Conventional mass spectrometric technique offer the best accuracy for determination of burn-up but they suffer from the labour intensive and time consuming chemical separation procedures followed by mass spectrometric analysis. Our laboratory has reported a potential laser mass spectrometric technique with advantages of (i) direct and fast measurement of ion intensities of selected rare earth element and residual heavy element atoms to deduce burn up and (ii) adaptability to remote handling of radioactive samples. Direct quantification of burn up monitor element in fuel in the form of pellet as well as liquid was probed by pulsed laser deposition followed by Isotopic Dilution Mass Spectrometric technique (IDMS). The procedure involving laser ablation of heavy element (namely U and Pu) and fission product (Nd, La etc) from a simulated spent fuel matrix followed by isotopic dilution mass spectrometry using thermal ionization mass spectrometry (TIMS) has been presently attempted to arrive at the rare earth element to heavy element ratio to deduce burn up using the methodology described in our earlier work. The details of IDMS technique has been reviewed by Heumann et al. Accurately weighed amounts of major rare earth fission products such as Nd, La, Ce and Sm in solution form were mixed with known quantity of uranium solution (all the weights are corresponding to their fission yields and the residual heavy element atoms after a given burn up) and mixed together to attain uniformity. The solution is then dried and resulting powder was pelletized and sintered. Subsequently, the pellet was ablated with pulsed laser (8 ns, 532 nm, Nd-YAG) and the plume was deposited on a glass plate. This deposit was dissolved in minimum amount of nitric acid. A known volume of the solution was mixed with spike (for e.g., 150 Nd/ 142 Nd, 233 U/ 238 U in this study

UV-laser microdissection system - A novel approach for the preparation of high-resolution stable isotope records (δ13C/δ18O) from tree rings

Science.gov (United States)

Schollaen, Karina; Helle, Gerhard

2013-04-01

Intra-annual stable isotope (δ13C and δ18O) studies of tree rings at various incremental resolutions have been attempting to extract valuable seasonal climatic and environmental information or assessing plant ecophysiological processes. For preparing high-resolution isotope samples normally wood segments or cores are mechanically divided in radial direction or cut in tangential direction. After mechanical dissection, wood samples are ground to a fine powder and either cellulose is extracted or bulk wood samples are analyzed. Here, we present a novel approach for the preparation of high-resolution stable isotope records from tree rings using an UV-laser microdissection system. Firstly, tree-ring cellulose is directly extracted from wholewood cross-sections largely leaving the wood anatomical structure intact and saving time as compared to the classical procedure. Secondly, micro-samples from cellulose cross-sections are dissected with an UV-Laser dissection microscope. Tissues of interest from cellulose cross-sections are identified and marked precisely with a screen-pen and dissected via an UV-laser beam. Dissected cellulose segments were automatically collected in capsules and are prepared for stable isotope (δ13C and δ18O) analysis. The new techniques facilitate inter- and intra-annual isotope analysis on tree-ring and open various possibilities for comparisons with wood anatomy in plant eco-physiological studies. We describe the design and the handling of this novel methodology and discuss advantages and constraints given by the example of intra-annual oxygen isotope analysis on tropical trees.

A field-deployable compound-specific isotope analyzer based on quantum cascade laser and hollow waveguide

Science.gov (United States)

Wu, Sheng; Deev, Andrei

2013-01-01

A field deployable Compound Specific Isotope Analyzer (CSIA) coupled with capillary chromatogrpahy based on Quantum Cascade (QC) lasers and Hollow Waveguide (HWG) with precision and chemical resolution matching mature Mass Spectroscopy has been achieved in our laboratory. The system could realize 0.3 per mil accuracy for 12C/13C for a Gas Chromatography (GC) peak lasting as short as 5 seconds with carbon molar concentration in the GC peak less than 0.5%. Spectroscopic advantages of HWG when working with QC lasers, i.e. single mode transmission, noiseless measurement and small sample volume, are compared with traditional free space and multipass spectroscopy methods.

Leaf water stable isotopes and water transport outside the xylem.

Science.gov (United States)

Barbour, M M; Farquhar, G D; Buckley, T N

2017-06-01

How water moves through leaves, and where the phase change from liquid to vapour occurs within leaves, remain largely mysterious. Some time ago, we suggested that the stable isotope composition of leaf water may contain information on transport pathways beyond the xylem, through differences in the development of gradients in enrichment within the various pathways. Subsequent testing of this suggestion provided ambiguous results and even questioned the existence of gradients in enrichment within the mesophyll. In this review, we bring together recent theoretical developments in understanding leaf water transport pathways and stable isotope theory to map a path for future work into understanding pathways of water transport and leaf water stable isotope composition. We emphasize the need for a spatially, anatomically and isotopically explicit model of leaf water transport. © 2016 John Wiley & Sons Ltd.

Temporal structure of an electric signal produced upon interaction of radiation from a HF laser with the bottom surface of a water column

International Nuclear Information System (INIS)

Andreev, Sergei N; Kazantsev, S Yu; Kononov, I G; Pashinin, Pavel P; Firsov, K N

2009-01-01

Generation of an electric signal is investigated when a HF-laser pulse interacts with the lower surface of a water column in a cell with a bottom transparent to laser radiation, while the upper surface of the water column remains open. The electric signal exhibits a temporal structure of two spikes spaced by time τ which is linearly dependent on the laser output energy. It is found that the value of τ (up to 1.3 ms) is an order of magnitude greater than the time during which the vapour pressure in a cavity produced due to the volume explosive boiling of water in the exposed area is greater than the atmospheric pressure. The second spike was determined to appear upon the collapse of the vapour cavity. A mathematical model is constructed that explains the motion of the water column above the vapour cavity taking into account the temporal evolution of the vapour pressure above it. It is shown that the prolonged lifetime of the vapour cavity after the decrease in the vapour pressure down to the atmospheric value is caused by the inertial motion of the water column acquiring the velocity at the initial stage of the cavity expansion. The calculated time of the water column motion agrees well with the experimental time interval between the spikes of an electric signal. (interaction of laser radiation with matter)

Establishing Ideal Conditions for Complete Denitrification by Pseudomonas Aureofaciens - An Update on Determining Isotopic Composition of Dissolved Nitrate Using Bacterial Denitrification and Laser Spectroscopy

International Nuclear Information System (INIS)

Yi, Amelia Lee Zhi; Heiling, Maria; Toloza, Arsenio; Heng, Lee K.

2017-01-01

This serves as update on research entitled “Determining isotopic composition of dissolved nitrate using bacterial denitrification and laser spectroscopy” first published in the Vol. 39, No. 1, July 2016 SWMCN Soils Newsletter. In this research, isotopic δ"1"5N and δ"1"8O composition of dissolved nitrates is measured by laser spectroscopy after reduction of nitrate to N_2O by Pseudomonas aureofaciens. Quantifying the isotopic composition of nitrates in aqueous samples allows for better identification of potential nitrate sources, which in turn assists in remediation of nitrate-contaminated water and design of future agricultural management practises. The overall objective of the project is to establish a technical guide in the form of a standard operating procedure outlining best practises for denitrification method.

Second harmonic generation of frequency-locked pulsed dye laser for selective photoionization of T1-203 isotope

International Nuclear Information System (INIS)

Lim, Gwon; Jeong, Do Young; Ko, Kwang Hoon; Kim, Jae Woo; Kim, Taek Soo; Rho, Sipyo; Kim, Cheol Jung

2003-01-01

We have constructed the frequency-locked pulsed dye laser system. It is composed with a GIM-type oscillator and 3 stage longitudinally pumped amplifiers. The pump laser is the second harmonic of pulse Nd:YAG laser at the repetition rate of 6 kHz. Frequency-locking of dye laser oscillator is actively controlled by the feedback loop between a photoionization signal of T1-203 isotope and a wavelength tuning control. The tuning mirror rotates the order of micro degree per a step of step motor. Feedback system for frequency locking is operated with a PC-based control interface, including the data analysis of photoionization signals and the wavelength control using step pumping method for a medical application. Therefor, the dye laser has to be locked at 583.66 nm for SHG or BBO crystal. With the frequency-locking system, the photoionization experiment has been done for more than 10 hours.

Nuclear shape staggering in very neutron deficient Hg isotopes detected by laser spectroscopy

International Nuclear Information System (INIS)

Dabkiewicz, P.; Duke, C.; Fischer, H.; Kuehl, T.; Kluge, H.-J.

1978-01-01

The isotope shift in the lambda = 2537 A line of the even isotopes 206 Hg, 190 Hg, 188 Hg, 186 Hg, 184 Hg as well as of the I = 13/2 isomers of 191 Hg, 189 Hg, 187 Hg, 185 Hg has been measured by use of a tunable dye laser at the on-line masseparator ISOLDE at CERN. The resulting delta 2 > values follow the line, extrapolated from the chain 205 Hg- 187 Hg which is known to have spherical nuclear shape at the heavy end changing smoothly to slight oblate deformation for the lighter isotopes. Previous measurements of the I = 1/2 groundstates of 181 Hg. 183 Hg and 185 Hg revealed a sharp shape transition to strong deformation. Combined with the new results the following effects can be proved for the first time from the model-independent quantity delta 2 >: 1) the existence of odd even-shape staggering, 2) the coexistence of very different shapes in one and the same nucleus as manifested by the huge isomer shift in 185 Hg, 3) the absence of mixing of the different shapes. (author)

Stable Isotopic Composition of Rainfall in Western Cameroon

Energy Technology Data Exchange (ETDEWEB)

Ketchemen-Tandia, B.; Ngo Boum, S.; Ebonji Seth, C. R.; Nkoue Ndong, G. R.; Wonkam, C. [Universite de Douala, Douala (Cameroon); Huneau, F. [Universite de Bordeaux, EA Georessources and Environnement, Talence (France); Celle-Jeanton, H. [Clermont Universite, Clermont-Ferrand (France)

2013-07-15

Monthly rainfall collected at the douala station (Western cameroon) from 2006 to 2008 was analysed for oxygen-18 and deuterium content. The dataset, which is now integrated into the GNIP database, was compared to the local groundwater record in order to define the input function of regional hydrosystems. The isotope data displays a wide range of values from -0.59 to -6.14 per mille for oxygen-18 and from -7.75 to -38.8 per mille for deuterium, closely following the GMWL (global Meteoric Water line), suggesting that rain formation processes occurred under isotopic equilibrium conditions between the condensate and the corresponding vapour. No significant evaporation tendency was found. The comparison with the previous studies in the area provides a realistic pattern of isotope concentrations in both surface and groundwater throughout Cameroon. (author)

Laser-based measurements of 18O/16O stable isotope ratios (δ18O in wine samples

Directory of Open Access Journals (Sweden)

Gupta M

2013-09-01

Full Text Available Manish Gupta,1 J Brian Leen,1 Elena Simone Franklin Berman,1 Aldo Ciambotti2 1Los Gatos Research, Mountain View, CA, USA; 2Consiglio per la Ricerca e la Sperimentazione in Agricoltura, Centro di Ricerca per l'Enologia, Asti, Italy Abstract: Wine counterfeiting is an international, multi-billion dollar issue, with some estimates suggesting that up to 5% of wines sold at auctions or secondary markets are fraudulent. Isotope ratio mass spectrometer (IRMS measurements of the 18O/16O stable isotope ratio (δ18O of water-in-wine have been used for wine authentication; however, these analyses are time-consuming and costly. In this preliminary study, off-axis integrated cavity output spectroscopy (OA-ICOS is used to quantify δ18O in wines. This laser-based method has been extensively used to study water isotopes for hydrological and medical applications. Recently, the development of a spectral contaminant identifier (SCI has extended the application of these OA-ICOS analyzers to contaminated water samples (eg, plant, soil, and leaf waters. Here, we utilize OA-ICOS with the SCI to characterize wine samples (9%–15% ethanol, and show that the laser-based instrument provides a δ18O measurement precision of ±0.07‰ (1σ and agrees with IRMS to within ±0.63‰ (1σ. Moreover, by training the SCI on isotopically-characterized wines, the agreement with IRMS improves to within ±0.30‰ (1σ. The utility of the instrument is demonstrated by measuring watered and mixed wines. The method presented here can be readily extended to address other food authentication applications. Keywords: wine isotopes, wine fraud, counterfeit wines, OA-ICOS

Keyhole behaviour during laser welding of zinc-coated steel

NARCIS (Netherlands)

Pan, Y.; Richardson, I.M.

2011-01-01

The production of consistent, high-quality laser welds on zinc-coated steels for the automotive industry remains a challenge. A simple overlap joint geometry is desirable in these applications but has been shown to be extremely detrimental to laser welding because the zinc vapour formed at the

Construction of a two-photon-laser spectrometer and determination of the hyperfine splitting and isotopic shift of barium

International Nuclear Information System (INIS)

Jitschin, W.

1977-01-01

A sensitive two-photon-laser spectrometer was constructed, that allowed to measure atomic states with an energy from 31 000 up to 37500 cm -1 with about 2 MHz resolution. The large energy range and the high resolution were reached by using a wide-wavelength tunable, narrow-band dye-laser. With this spectrometer transitions could be detected at barium from the electron ground-state 6s 2 1 S 0 to 10 upper states in the 5 most common isotopes 138 Ba, 137 Ba, 136 Ba, 135 Ba and 134 Ba. The transitions could be measured precisely. It was possible to derive lower limits of the life-time of these states from the widths of the recorded resonance lines (typically several nsec), that should in fact not be smaller than the actual lifetimes. From the measured hyper-fine splitting of the 6 transitions with angular momentum J = 2 at the oddnumbered isotopes 137 Ba and 135 Ba the parameters of the hyper-fine splitting could be determined. Hereby an accuracy of about IMH 2 could be reached at the A-factor and about 5MHz at the B-factor. At the measured transitions the isotopic shifts of the particular isotope could be determined with an accuracy of a few MHz. There was only a simple theory of the isotopic shift with only few parameters worked out for the theoretical interpretation of the measured data, that describes the data even at the experimentally reached high accuracy. Two parameters of this theory depending only from atomic nucleus properties, could be determined with a 0.5 % error. (orig./WB) [de

Development of routines for simultaneous in situ chemical composition and stable Si isotope ratio analysis by femtosecond laser ablation inductively coupled plasma mass spectrometry

Energy Technology Data Exchange (ETDEWEB)

Frick, Daniel A., E-mail: dfrick@gfz-potsdam.de [GFZ German Research Centre for Geosciences, 14473 Potsdam (Germany); Schuessler, Jan A. [GFZ German Research Centre for Geosciences, 14473 Potsdam (Germany); Blanckenburg, Friedhelm von [GFZ German Research Centre for Geosciences, 14473 Potsdam (Germany); Institute of Geological Science, Freie Universität Berlin, 12249 Berlin (Germany)

2016-09-28

Stable metal (e.g. Li, Mg, Ca, Fe, Cu, Zn, and Mo) and metalloid (B, Si, Ge) isotope ratio systems have emerged as geochemical tracers to fingerprint distinct physicochemical reactions. These systems are relevant to many Earth Science questions. The benefit of in situ microscale analysis using laser ablation (LA) over bulk sample analysis is to use the spatial context of different phases in the solid sample to disclose the processes that govern their chemical and isotopic compositions. However, there is a lack of in situ analytical routines to obtain a samples' stable isotope ratio together with its chemical composition. Here, we evaluate two novel analytical routines for the simultaneous determination of the chemical and Si stable isotope composition (δ{sup 30}Si) on the micrometre scale in geological samples. In both routines, multicollector inductively coupled plasma mass spectrometry (MC-ICP-MS) is combined with femtosecond-LA, where stable isotope ratios are corrected for mass bias using standard-sample-bracketing with matrix-independent calibration. The first method is based on laser ablation split stream (LASS), where the laser aerosol is split and introduced simultaneously into both the MC-ICP-MS and a quadrupole ICP-MS. The second method is based on optical emission spectroscopy using direct observation of the MC-ICP-MS plasma (LA-MC-ICP-MS|OES). Both methods are evaluated using international geological reference materials. Accurate and precise Si isotope ratios were obtained with an uncertainty typically better than 0.23‰, 2SD, δ{sup 30}Si. With both methods major element concentrations (e.g., Na, Al, Si, Mg, Ca) can be simultaneously determined. However, LASS-ICP-MS is superior over LA-MC-ICP-MS|OES, which is limited by its lower sensitivity. Moreover, LASS-ICP-MS offers trace element analysis down to the μg g{sup −1}-range for more than 28 elements due to lower limits of detection, and with typical uncertainties better than 15%. For in situ

Development of routines for simultaneous in situ chemical composition and stable Si isotope ratio analysis by femtosecond laser ablation inductively coupled plasma mass spectrometry

International Nuclear Information System (INIS)

Frick, Daniel A.; Schuessler, Jan A.; Blanckenburg, Friedhelm von

2016-01-01

Stable metal (e.g. Li, Mg, Ca, Fe, Cu, Zn, and Mo) and metalloid (B, Si, Ge) isotope ratio systems have emerged as geochemical tracers to fingerprint distinct physicochemical reactions. These systems are relevant to many Earth Science questions. The benefit of in situ microscale analysis using laser ablation (LA) over bulk sample analysis is to use the spatial context of different phases in the solid sample to disclose the processes that govern their chemical and isotopic compositions. However, there is a lack of in situ analytical routines to obtain a samples' stable isotope ratio together with its chemical composition. Here, we evaluate two novel analytical routines for the simultaneous determination of the chemical and Si stable isotope composition (δ 30 Si) on the micrometre scale in geological samples. In both routines, multicollector inductively coupled plasma mass spectrometry (MC-ICP-MS) is combined with femtosecond-LA, where stable isotope ratios are corrected for mass bias using standard-sample-bracketing with matrix-independent calibration. The first method is based on laser ablation split stream (LASS), where the laser aerosol is split and introduced simultaneously into both the MC-ICP-MS and a quadrupole ICP-MS. The second method is based on optical emission spectroscopy using direct observation of the MC-ICP-MS plasma (LA-MC-ICP-MS|OES). Both methods are evaluated using international geological reference materials. Accurate and precise Si isotope ratios were obtained with an uncertainty typically better than 0.23‰, 2SD, δ 30 Si. With both methods major element concentrations (e.g., Na, Al, Si, Mg, Ca) can be simultaneously determined. However, LASS-ICP-MS is superior over LA-MC-ICP-MS|OES, which is limited by its lower sensitivity. Moreover, LASS-ICP-MS offers trace element analysis down to the μg g −1 -range for more than 28 elements due to lower limits of detection, and with typical uncertainties better than 15%. For in situ

Determination of the Isotope Ratio for Metal Samples Using a Laser Ablation/Ionization Time-of-flight Mass Spectrometry

International Nuclear Information System (INIS)

Song, Kyu Seok; Cha, Hyung Ki; Kim, Duk Hyeon; Min, Ki Hyun

2004-01-01

The laser ablation/ionization time-of-flight mass spectrometry is applied to the isotopic analysis of solid samples using a home-made instrument. The technique is convenient for solid sample analysis due to the onestep process of vaporization and ionization of the samples. The analyzed samples were lead, cadmium, molybdenum, and ytterbium. To optimize the analytical conditions of the technique, several parameters, such as laser energy, laser wavelength, size of the laser beam on the samples surface, and high voltages applied on the ion source electrodes were varied. Low energy of laser light was necessary to obtain the optimal mass resolution of spectra. The 532 nm light generated mass spectra with the higher signal-to-noise ratio compared with the 355 nm light. The best mass resolution obtained in the present study is ∼1,500 for the ytterbium

Lasers and uranium isotope separation

Energy Technology Data Exchange (ETDEWEB)

Gilles, L

1987-12-01

The use of lasers by the electronuclear industry to enrich uranium is discussed, particularly economic aspects. The SILMO and SILVA processes (chosen by France for industrial development) are presented. Criteria which lead to the choice of lasers and to their set-up (architecture of the chain) are described. For electricity - consumption linked to the use of lasers of 40 kWh/STU, a laser uranium enrichment plant with 10 STU/yr capacity requires 50kW of light from copper vapor lasers, i.e., 500 units each having 100W capacity, compared with the 40W units currently marketed.

Isotope enrichment

International Nuclear Information System (INIS)

Garbuny, M.

1979-01-01

The invention discloses a method for deriving, from a starting material including an element having a plurality of isotopes, derived material enriched in one isotope of the element. The starting material is deposited on a substrate at less than a critical submonatomic surface density, typically less than 10 16 atoms per square centimeter. The deposit is then selectively irradiated by a laser (maser or electronic oscillator) beam with monochromatic coherent radiation resonant with the one isotope causing the material including the one istope to escape from the substrate. The escaping enriched material is then collected. Where the element has two isotopes, one of which is to be collected, the deposit may be irradiated with radiation resonant with the other isotope and the residual material enriched in the one isotope may be evaporated from the substrate and collected

Measurement of the D/H, 18O/16O, and 17O/16O Isotope Ratios in Water by Laser Absorption Spectroscopy at 2.73 μm

Directory of Open Access Journals (Sweden)

Tao Wu

2014-05-01

Full Text Available A compact isotope ratio laser spectrometry (IRLS instrument was developed for simultaneous measurements of the D/H, 18O/16O and 17O/16O isotope ratios in water by laser absorption spectroscopy at 2.73 μm. Special attention is paid to the spectral data processing and implementation of a Kalman adaptive filtering to improve the measurement precision. Reduction of up to 3-fold in standard deviation in isotope ratio determination was obtained by the use of a Fourier filtering to remove undulation structure from spectrum baseline. Application of Kalman filtering enables isotope ratio measurement at 1 s time intervals with a precision (<1‰ better than that obtained by conventional 30 s averaging, while maintaining a fast system response. The implementation of the filter is described in detail and its effects on the accuracy and the precision of the isotope ratio measurements are investigated.

Atomic origins of water-vapour-promoted alloy oxidation.

Science.gov (United States)

Luo, Langli; Su, Mao; Yan, Pengfei; Zou, Lianfeng; Schreiber, Daniel K; Baer, Donald R; Zhu, Zihua; Zhou, Guangwen; Wang, Yanting; Bruemmer, Stephen M; Xu, Zhijie; Wang, Chongmin

2018-05-07

The presence of water vapour, intentional or unavoidable, is crucial to many materials applications, such as in steam generators, turbine engines, fuel cells, catalysts and corrosion 1-4 . Phenomenologically, water vapour has been noted to accelerate oxidation of metals and alloys 5,6 . However, the atomistic mechanisms behind such oxidation remain elusive. Through direct in situ atomic-scale transmission electron microscopy observations and density functional theory calculations, we reveal that water-vapour-enhanced oxidation of a nickel-chromium alloy is associated with proton-dissolution-promoted formation, migration, and clustering of both cation and anion vacancies. Protons derived from water dissociation can occupy interstitial positions in the oxide lattice, consequently lowering vacancy formation energy and decreasing the diffusion barrier of both cations and anions, which leads to enhanced oxidation in moist environments at elevated temperatures. This work provides insights into water-vapour-enhanced alloy oxidation and has significant implications in other material and chemical processes involving water vapour, such as corrosion, heterogeneous catalysis and ionic conduction.

Stable oxygen and hydrogen isotopes of brines - comparing isotope ratio mass spectrometry and isotope ratio infrared spectroscopy

Science.gov (United States)

Ahrens, Christian; Koeniger, Paul; van Geldern, Robert; Stadler, Susanne

2013-04-01

Today's standard analytical methods for high precision stable isotope analysis of fluids are gas-water equilibration and high temperature pyrolysis coupled to isotope ratio mass spectrometers (IRMS). In recent years, relatively new laser-based analytical instruments entered the market that are said to allow high isotope precision data on nearly every media. This optical technique is referred to as isotope ratio infrared spectroscopy (IRIS). The objective of this study is to evaluate the capability of this new instrument type for highly saline solutions and a comparison of the analytical results with traditional IRMS analysis. It has been shown for the equilibration method that the presence of salts influences the measured isotope values depending on the salt concentration (see Lécuyer et al, 2009; Martineau, 2012). This so-called 'isotope salt effect' depends on the salt type and salt concentration. These factors change the activity in the fluid and therefore shift the isotope ratios measured by the equilibration method. Consequently, correction factors have to be applied to these analytical data. Direct conversion techniques like pyrolysis or the new laser instruments allow the measurement of the water molecule from the sample directly and should therefore not suffer from the salt effect, i.e. no corrections of raw values are necessary. However, due to high salt concentrations this might cause technical problems with the analytical hardware and may require labor-intensive sample preparation (e.g. vacuum distillation). This study evaluates the salt isotope effect for the IRMS equilibration technique (Thermo Gasbench II coupled to Delta Plus XP) and the laser-based IRIS instruments with liquid injection (Picarro L2120-i). Synthetic salt solutions (NaCl, KCl, CaCl2, MgCl2, MgSO4, CaSO4) and natural brines collected from the Stassfurt Salt Anticline (Germany; Stadler et al., 2012) were analysed with both techniques. Salt concentrations ranged from seawater salinity

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

International Nuclear Information System (INIS)

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

1988-01-01

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

High mass isotope separation arrangement

International Nuclear Information System (INIS)

Eerkens, J.W.

1980-01-01

This invention relates to the isotope separation art and, more particularly, to a selectively photon-induced energy level transition of an isotopic molecule containing the isotope to be separated and a chemical reaction with a chemically reactive agent to provide a chemical compound containing atoms of the isotope desired. In particular a description is given of a method of laser isotope separation applied to the separation of 235 UF 6 from 238 UF 6 . (U.K.)

Isotopes as tracers of the sources of the lunar material and processes of lunar origin.

Science.gov (United States)

Pahlevan, Kaveh

2014-09-13

Ever since the Apollo programme, isotopic abundances have been used as tracers to study lunar formation, in particular to study the sources of the lunar material. In the past decade, increasingly precise isotopic data have been reported that give strong indications that the Moon and the Earth's mantle have a common heritage. To reconcile these observations with the origin of the Moon via the collision of two distinct planetary bodies, it has been proposed (i) that the Earth-Moon system underwent convective mixing into a single isotopic reservoir during the approximately 10(3) year molten disc epoch after the giant impact but before lunar accretion, or (ii) that a high angular momentum impact injected a silicate disc into orbit sourced directly from the mantle of the proto-Earth and the impacting planet in the right proportions to match the isotopic observations. Recently, it has also become recognized that liquid-vapour fractionation in the energetic aftermath of the giant impact is capable of generating measurable mass-dependent isotopic offsets between the silicate Earth and Moon, rendering isotopic measurements sensitive not only to the sources of the lunar material, but also to the processes accompanying lunar origin. Here, we review the isotopic evidence that the silicate-Earth-Moon system represents a single planetary reservoir. We then discuss the development of new isotopic tracers sensitive to processes in the melt-vapour lunar disc and how theoretical calculations of their behaviour and sample observations can constrain scenarios of post-impact evolution in the earliest history of the Earth-Moon system. © 2014 The Author(s) Published by the Royal Society. All rights reserved.

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

International Nuclear Information System (INIS)

Barsanti, S; Bicchi, P

2002-01-01

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

Boron isotope fractionation in magma via crustal carbonate dissolution.

Science.gov (United States)

Deegan, Frances M; Troll, Valentin R; Whitehouse, Martin J; Jolis, Ester M; Freda, Carmela

2016-08-04

Carbon dioxide released by arc volcanoes is widely considered to originate from the mantle and from subducted sediments. Fluids released from upper arc carbonates, however, have recently been proposed to help modulate arc CO2 fluxes. Here we use boron as a tracer, which substitutes for carbon in limestone, to further investigate crustal carbonate degassing in volcanic arcs. We performed laboratory experiments replicating limestone assimilation into magma at crustal pressure-temperature conditions and analysed boron isotope ratios in the resulting experimental glasses. Limestone dissolution and assimilation generates CaO-enriched glass near the reaction site and a CO2-dominated vapour phase. The CaO-rich glasses have extremely low δ(11)B values down to -41.5‰, reflecting preferential partitioning of (10)B into the assimilating melt. Loss of (11)B from the reaction site occurs via the CO2 vapour phase generated during carbonate dissolution, which transports (11)B away from the reaction site as a boron-rich fluid phase. Our results demonstrate the efficacy of boron isotope fractionation during crustal carbonate assimilation and suggest that low δ(11)B melt values in arc magmas could flag shallow-level additions to the subduction cycle.

Boron isotope fractionation in magma via crustal carbonate dissolution

Science.gov (United States)

Deegan, Frances M.; Troll, Valentin R.; Whitehouse, Martin J.; Jolis, Ester M.; Freda, Carmela

2016-08-01

Carbon dioxide released by arc volcanoes is widely considered to originate from the mantle and from subducted sediments. Fluids released from upper arc carbonates, however, have recently been proposed to help modulate arc CO2 fluxes. Here we use boron as a tracer, which substitutes for carbon in limestone, to further investigate crustal carbonate degassing in volcanic arcs. We performed laboratory experiments replicating limestone assimilation into magma at crustal pressure-temperature conditions and analysed boron isotope ratios in the resulting experimental glasses. Limestone dissolution and assimilation generates CaO-enriched glass near the reaction site and a CO2-dominated vapour phase. The CaO-rich glasses have extremely low δ11B values down to -41.5‰, reflecting preferential partitioning of 10B into the assimilating melt. Loss of 11B from the reaction site occurs via the CO2 vapour phase generated during carbonate dissolution, which transports 11B away from the reaction site as a boron-rich fluid phase. Our results demonstrate the efficacy of boron isotope fractionation during crustal carbonate assimilation and suggest that low δ11B melt values in arc magmas could flag shallow-level additions to the subduction cycle.

Development of laser application technologies for nuclear industry

International Nuclear Information System (INIS)

Kim, Cheol Jung; Rhee, Y.; Cha, B. H.

2004-03-01

The stable laser isotope facility will supply raw stable isotope material to produce radioisotope elements for medical and industrial applications. The medical stable isotope, Tl-203 was separated by the isotope selective optical pumping (ISOP) method native to the laboratory for quantum optics, KAERI. The extraction rate of 10 mg/hr was achieved from the separation chamber of 80cm x 80cm x 100cm dimension. The Yb-168 separation facility was improved in stability, durability, and efficiency. The old copper vapor pumping laser system was replaced with two 40W green DPSSL's. The tunable dye laser system was also improved in stability. The extraction rate was measured as 1.5 mg/hr in the improved system. The 200W infrared DPSSL system was also developed and used for photoionization of thallium isotopes. The adaptive optics and beam path control system was applied to the isotope separation facilities. Also the beam quality of the lasers was monitored and improved. To maintain constant isotope composition during reaction process, the wavelengths of tunable lasers are locked by being the mass composition information fed back into the oscillator control unit of the lasers. To optimize isotope separation process timely, the extractor surface is directly analyzed by laser irradiation and TOF mass spectrometer. And the final products in high purity is recovered in maximum by solution chemistry

Bibliographical study on photochemical separation of uranium isotopes

International Nuclear Information System (INIS)

Bougon, Roland

1975-01-01

The objective of this report is to propose an overview of knowledge and current works on isotopic separation of uranium by means of selective excitation where this excitation is obtained by a light source with a wave length corresponding to a selective or preferential absorption by a molecule or by the atom itself of one of the isotopes. After a brief overview of principles and requirements of isotopic separation by selective excitation, the author reviews compounds which can be used for this process. These compounds are mainly considered in terms of spectroscopy, and the study focuses on the most volatile among them, the uranium hexafluoride, its spectra, and possible processes for extraction. Some much less volatile uranium compounds are also mentioned with, when available, their spectroscopic properties. The uranium vapour excitation process is described, and some orientations for further researches are proposed [fr

Autonomous Chemical Vapour Detection by Micro UAV

Directory of Open Access Journals (Sweden)

Kent Rosser

2015-12-01

Full Text Available The ability to remotely detect and map chemical vapour clouds in open air environments is a topic of significant interest to both defence and civilian communities. In this study, we integrate a prototype miniature colorimetric chemical sensor developed for methyl salicylate (MeS, as a model chemical vapour, into a micro unmanned aerial vehicle (UAV, and perform flights through a raised MeS vapour cloud. Our results show that that the system is capable of detecting MeS vapours at low ppm concentration in real-time flight and rapidly sending this information to users by on-board telemetry. Further, the results also indicate that the sensor is capable of distinguishing “clean” air from “dirty”, multiple times per flight, allowing us to look towards autonomous cloud mapping and source localization applications. Further development will focus on a broader range of integrated sensors, increased autonomy of detection and improved engineering of the system.

Laser Spectroscopy of Neutron Rich Bismuth Isotopes

CERN Multimedia

2002-01-01

%IS344 :\\\\ \\\\ The aim of the experiment is to measure the optical isotope shifts and hyperfine structures of bismuth isotopes across the N=126 shell closure in order to extract the change in mean square charge radii ($\\delta\\langle r^{2}\\rangle$) and static moments. These include the first isotones of lead to be measured directly above the shell closure and will provide new information on the systematics of the kink ($\\delta\\langle r^{2}\\rangle)$ seen in the lead isotopic chain. After two very successful runs the programme has been extended to include the neutron deficient isotopes below $^{201}$Bi to study the systematics across the $i_{13/2}$ neutron sub-shell closure at N=118.\\\\ \\\\ During the initial 2 runs (9 shifts) the isotope shifts and hyperfine structures of three new isotopes, $ ^{210,212,213}$Bi and the 9$^{-}$ isomer of $^{210}$Bi have been measured. The accuracy of the previous measurements of $^{205,206,208}$Bi have been greatly improved. The samples of $ ^{208,210,210^{m}}$Bi were prepared by c...

Nuclear charge radius measurements of radioactive beryllium isotopes

CERN Multimedia

2002-01-01

We propose to measure the nuclear charge radii of the beryllium isotopes $^{7,9,10}$Be and the one-neutron halo isotope $^{11}$Be using laser spectroscopy of trapped ions. Ions produced at ISOLDE and ionized with the laser ion source will be cooled and bunched in the radio-frequency buncher of the ISOLTRAP experiment and then transferred into a specially designed Paul trap. Here, they will be cooled to temperatures in the mK range employing sympathetic and direct laser cooling. Precision laser spectroscopy of the isotope shift on the cooled ensemble in combination with accurate atomic structure calculations will provide nuclear charge radii with a precision of better than 3%. This will be the first model-independent determination of a one-neutron halo nuclear charge radius.

Infrared laser-induced chemical reactions

International Nuclear Information System (INIS)

Katayama, Mikio

1978-01-01

The experimental means which clearly distinguishes between infrared ray-induced reactions and thermal reactions has been furnished for the first time when an intense monochromatic light source has been obtained by the development of infrared laser. Consequently, infrared laser-induced chemical reactions have started to develop as one field of chemical reaction researches. Researches of laser-induced chemical reactions have become new means for the researches of chemical reactions since they were highlighted as a new promising technique for isotope separation. Specifically, since the success has been reported in 235 U separation using laser in 1974, comparison of this method with conventional separation techniques from the economic point of view has been conducted, and it was estimated by some people that the laser isotope separation is cheaper. This report briefly describes on the excitation of oscillation and reaction rate, and introduces the chemical reactions induced by CW laser and TEA CO 2 laser. Dependence of reaction yield on laser power, measurement of the absorbed quantity of infrared ray and excitation mechanism are explained. Next, isomerizing reactions are reported, and finally, isotope separation is explained. It was found that infrared laser-induced chemical reactions have the selectivity for isotopes. Since it is evident that there are many examples different from thermal and photo-chemical reactions, future collection of the data is expected. (Wakatsuki, Y.)

Using a laser-based CO2 carbon isotope analyser to investigate gas transfer in geological media

International Nuclear Information System (INIS)

Guillon, S.; Pili, E.; Agrinier, P.

2012-01-01

CO 2 stable carbon isotopes are very attractive in environmental research to investigate both natural and anthropogenic carbon sources. Laser-based CO 2 carbon isotope analysis provides continuous measurement at high temporal resolution and is a promising alternative to isotope ratio mass spectrometry (IRMS). We performed a thorough assessment of a commercially available CO 2 Carbon Isotope Analyser (CCIA DLT-100, Los Gatos Research) that allows in situ measurement of C-13 in CO 2 . Using a set of reference gases of known CO 2 concentration and carbon isotopic composition, we evaluated the precision, long-term stability, temperature sensitivity and concentration dependence of the analyser. Despite good precision calculated from Allan variance (5.0 ppm for CO 2 concentration, and 0.05 per thousand for δC-13 at 60 s averaging), real performances are altered by two main sources of error: temperature sensitivity and dependence of C-13 on CO 2 concentration. Data processing is required to correct for these errors. Following application of these corrections, we achieve an accuracy of 8.7 ppm for CO 2 concentration and 1.3 per thousand for δC-13, which is worse compared to mass spectrometry performance, but still allowing field applications. With this portable analyser we measured CO 2 flux degassed from rock in an underground tunnel. The obtained carbon isotopic composition agrees with IRMS measurement, and can be used to identify the carbon source. (authors)

A lidar for water vapour measurements in daytime at Lampedusa, Italy

Directory of Open Access Journals (Sweden)

F. Marenco

2003-06-01

Full Text Available ENEA is planning to develop a lidar system for measurement of the vertical profi le of water vapour mixing ratio in daytime at a remote site, the Station for Climate Observations located in Lampedusa, Italy. The Raman lidar technique has been retained because of its experimental simplicity with respect to DIAL, and the UV spectral range has been chosen because Raman cross-sections and detector effi ciencies are larger. For a wavelength larger than ~ 300 nm the signal is limited in daytime by sky background, but extinction is acceptable, and the aims of the system can be reached with a strong laser source. The 355 nm wavelength of a frequency-tripled Nd:YAG laser has been retained as this laser source permits to reach a large pulse energy while keeping the system simple to operate. Geometrical form factor calculations need to be performed to evaluate the near-range overlap between the laser beam and the fi eld-of-view of the receiver. Among several options, a dual-receiver system has been retained to account for the several orders of magnitude expected in the backscattered signal intensity: a smaller receiver, with a primary mirror of 200 mm diameter for the 0.2-1 km range, and a larger 500 mm receiver for the 1-3 km range.

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.

Welding zinc coated steel with a CO/sub 2/ laser

International Nuclear Information System (INIS)

Akhter, R.; Steen, W.M.

1993-01-01

Welding of zinc coated steel has been studied using a high power CO/sub 2/ laser. This process is of great interest to the manufactures of car, washing machines and other components made from sheet steel and subject to corrosion. The problem associated with the welding of zinc coated steel is the low boiling point of zinc (906C) relative to the high melting point of steel (1500C). The problem is particularly important in lap welding where the zinc layer is between the lapped sheets. Under these conditions the laser 'keyhole' will generate very high vapour pressure in the zinc layer with a consequent severe risk of vapour eruption destroying the continuity of the weld bead. Several techniques are presented for the removal of zinc vapours from the interface between the two sheets. It is shown that this problem solved by suitable gap between the sheets during lap welding. Hence full penetration welds without deterioration of the weld bead can be obtained. A theory has been presented which predicted an exact gap size needed to exhaust the zinc vapour. The gap depends upon the welding speed, zinc coating thickness and thickness of the sheet. The theory predicts the weld quality satisfactorily. (author)

Response of water vapour D-excess to land–atmosphere interactions in a semi-arid environment

KAUST Repository

Parkes, Stephen; McCabe, Matthew; Griffiths, Alan D.; Wang, Lixin; Chambers, Scott; Ershadi, Ali; Williams, Alastair G.; Strauss, Josiah; Element, Adrian

2017-01-01

The stable isotopic composition of water vapour provides information about moisture sources and processes difficult to obtain with traditional measurement techniques. Recently, it has been proposed that the D-excess of water vapour (d =δH-8× δO) can provide a diagnostic tracer of continental moisture recycling. However, D-excess exhibits a diurnal cycle that has been observed across a variety of ecosystems and may be influenced by a range of processes beyond regional-scale moisture recycling, including local evaporation (ET) fluxes. There is a lack of measurements of D-excess in evaporation (ET) fluxes, which has made it difficult to assess how ET fluxes modify the Dexcess in water vapour (d). With this in mind, we employed a chamber-based approach to directly measure D-excess in ET (d) fluxes. We show that ET fluxes imposed a negative forcing on the ambient vapour and could not explain the higher daytime d values. The low d observed here was sourced from a soil water pool that had undergone an extended drying period, leading to low D-excess in the soil moisture pool. A strong correlation between daytime d and locally measured relative humidity was consistent with an oceanic moisture source, suggesting that remote hydrological processes were the major contributor to daytime d variability. During the early evening, ET fluxes into a shallow nocturnal inversion layer caused a lowering of d values near the surface. In addition, transient mixing of vapour with a higher D-excess from above the nocturnal inversion modified these values, causing large variability during the night. These results indicate d can generally be expected to show large spatial and temporal variability and to depend on the soil moisture state. For long periods between rain events, common in semi-arid environments, ET would be expected to impose negative forcing on the surface d. Spatial and temporal variability of D-excess in ET fluxes therefore needs to be considered when using d to study

Response of water vapour D-excess to land–atmosphere interactions in a semi-arid environment

KAUST Repository

Parkes, Stephen

2017-01-27

The stable isotopic composition of water vapour provides information about moisture sources and processes difficult to obtain with traditional measurement techniques. Recently, it has been proposed that the D-excess of water vapour (d =δH-8× δO) can provide a diagnostic tracer of continental moisture recycling. However, D-excess exhibits a diurnal cycle that has been observed across a variety of ecosystems and may be influenced by a range of processes beyond regional-scale moisture recycling, including local evaporation (ET) fluxes. There is a lack of measurements of D-excess in evaporation (ET) fluxes, which has made it difficult to assess how ET fluxes modify the Dexcess in water vapour (d). With this in mind, we employed a chamber-based approach to directly measure D-excess in ET (d) fluxes. We show that ET fluxes imposed a negative forcing on the ambient vapour and could not explain the higher daytime d values. The low d observed here was sourced from a soil water pool that had undergone an extended drying period, leading to low D-excess in the soil moisture pool. A strong correlation between daytime d and locally measured relative humidity was consistent with an oceanic moisture source, suggesting that remote hydrological processes were the major contributor to daytime d variability. During the early evening, ET fluxes into a shallow nocturnal inversion layer caused a lowering of d values near the surface. In addition, transient mixing of vapour with a higher D-excess from above the nocturnal inversion modified these values, causing large variability during the night. These results indicate d can generally be expected to show large spatial and temporal variability and to depend on the soil moisture state. For long periods between rain events, common in semi-arid environments, ET would be expected to impose negative forcing on the surface d. Spatial and temporal variability of D-excess in ET fluxes therefore needs to be considered when using d to study

Stable isotope ratio measurements in hydrogen, nitrogen, and oxygen using Raman scattering

International Nuclear Information System (INIS)

Harney, R.C.; Bloom, S.D.; Milanovich, F.P.

1975-01-01

A method for measuring stable isotope ratios using laser Raman scattering was developed which may prove of significant utility and benefit in stable isotope tracer studies. Crude isotope ratio measurements obtained with a low-power laser indicate that with current technology it should be possible to construct an isotope ratio measurement system using laser Raman scattering that is capable of performing 0.1 percent accuracy isotope ratio measurements of 16 O/ 18 O in natural abundance oxygen gas or 14 N/ 15 N in natural abundance nitrogen gas in times less than two minutes per sample. Theory pertinent to the technique, designs of specific isotope ratio spectrometer systems, and data relating to isotope ratio measurements in hydrogen, nitrogen, and oxygen are presented. In addition, the current status of several studies utilizing this technique is discussed. (auth)

Laser diagnostics of a diamond depositing chemical vapour deposition gas-phase environment

International Nuclear Information System (INIS)

Smith, James Anthony

2002-01-01

Studies have been carried out to understand the gas-phase chemistry underpinning diamond deposition in hot filament and DC-arcjet chemical vapour deposition (CVD) systems. Resonance enhanced Multiphoton lonisation (REMPI) techniques were used to measure the relative H atom and CH 3 radical number densities and local gas temperatures prevalent in a hot filament reactor, operating on Ch 4 /H 2 and C 2 H 2 /H 2 gas mixtures. These results were compared to a 3D-computer simulation, and hence provided an insight into the nature of the gas-phase chemistry with particular reference to C 2 →C 1 species conversion. Similar experimental and theoretical studies were also carried out to explain the chemistry involved in NH 3 /CH 4 /H 2 and N 2 /CH 4 /H 2 gas mixtures. It was demonstrated that the reactive nature of the filament surface was dependent on the addition of NH 3 , influencing atomic hydrogen production, and thus the H/C/N gas-phase chemistry. Studies of the DC-arcjet diamond CVD reactor consisted of optical emission spectroscopic studies of the plume during deposition from an Ar/H 2 /CH 4 /N 2 gas mixture. Spatially resolved species emission intensity maps were obtained for C 2 (d→a), CN(B→X) and H β from Abel-inverted datasets. The C 2 (d→a) and CN(B→X) emission intensity maps both show local maxima near the substrate surface. SEM and Laser Raman analyses indicate that N 2 additions lead to a reduction in film quality and growth rate. Photoluminescence and SIMS analyses of the grown films provide conclusive evidence of nitrogen incorporation (as chemically bonded CN). Absolute column densities of C 2 (a) in a DC-arcjet reactor operating on an Ar/H 2 /CH 4 gas mixture, were measured using Cavity ring down spectroscopy. Simulations of the measured C 2 (v=0) transition revealed a rotational temperature of ∼3300 K. This gas temperature is similar to that deduced from optical emission spectroscopy studies of the C 2 (d→a) transition. (author)

Method and apparatus for isotope separation from a gas stream

International Nuclear Information System (INIS)

Szoke, A.

1978-01-01

A method and apparatus are described for isotope separation and in particular for separating the desired isotope from the gas in which it is contained by irradiating it with a laser. The laser selectively provides kinetic energy to the isotope through inelastic events, monomolecular or bimolecular, in order to cause it to segregate within or fly out of the gas stream in which it is contained

Isotopic imaging via nuclear resonance fluorescence with laser-based Thomson radiation

Science.gov (United States)

Barty, Christopher P. J. [Hayward, CA; Hartemann, Frederic V [San Ramon, CA; McNabb, Dennis P [Alameda, CA; Pruet, Jason A [Brentwood, CA

2009-07-21

The present invention utilizes novel laser-based, high-brightness, high-spatial-resolution, pencil-beam sources of spectrally pure hard x-ray and gamma-ray radiation to induce resonant scattering in specific nuclei, i.e., nuclear resonance fluorescence. By monitoring such fluorescence as a function of beam position, it is possible to image in either two dimensions or three dimensions, the position and concentration of individual isotopes in a specific material configuration. Such methods of the present invention material identification, spatial resolution of material location and ability to locate and identify materials shielded by other materials, such as, for example, behind a lead wall. The foundation of the present invention is the generation of quasimonochromatic high-energy x-ray (100's of keV) and gamma-ray (greater than about 1 MeV) radiation via the collision of intense laser pulses from relativistic electrons. Such a process as utilized herein, i.e., Thomson scattering or inverse-Compton scattering, produces beams having diameters from about 1 micron to about 100 microns of high-energy photons with a bandwidth of .DELTA.E/E of approximately 10E.sup.-3.

Medical cannabis use in Canada: vapourization and modes of delivery.

Science.gov (United States)

Shiplo, Samantha; Asbridge, Mark; Leatherdale, Scott T; Hammond, David

2016-10-29

The mode of medical cannabis delivery-whether cannabis is smoked, vapourized, or consumed orally-may have important implications for its therapeutic efficacy and health risks. However, there is very little evidence on current patterns of use among Canadian medical cannabis users, particularly with respect to modes of delivery. The current study examined modes of medical cannabis delivery following regulatory changes in 2014 governing how Canadians access medical cannabis. A total of 364 approved adult Canadian medical cannabis users completed an online cross-sectional survey between April and June 2015. The survey examined patterns of medical cannabis use, modes of delivery used, and reasons for use. Participants were recruited through a convenience sample from nine Health Canada licensed producers. Using a vapourizer was the most popular mode of delivery for medical cannabis (53 %), followed by smoking a joint (47 %). The main reason for using a vapourizer was to reduce negative health consequences associated with smoking. A majority of current vapourizer users reported using a portable vapourizer (67.2 %), followed by a stationary vapourizer (41.7 %), and an e-cigarette or vape pen (19.3 %). Current use of a vapourizer was associated with fewer respiratory symptoms (AOR = 1.28, 95 % CI 1.05-1.56, p = 0.01). The findings suggest an increase in the popularity of vapourizers as the primary mode of delivery among approved medical users. Using vapourizers has the potential to prevent some of the adverse respiratory health consequences associated with smoking and may serve as an effective harm reduction method. Monitoring implications of such current and future changes to medical cannabis regulations may be beneficial to policymakers.

Brome isotope selective control of CF3Br molecule clustering by IR laser radiation in gas-dynamic expansion of CF3Br - Ar mixture

Science.gov (United States)

Apatin, V. M.; Lokhman, V. N.; Makarov, G. N.; Ogurok, N.-D. D.; Ryabov, E. A.

2018-02-01

We report the results of research on the experimental control of CF3Br molecule clustering under gas-dynamic expansion of the CF3Br - Ar mixture at a nozzle exit by using IR laser radiation. A cw CO2 laser is used for exciting molecules and clusters in the beam and a time-of-flight mass-spectrometer with laser UV ionisation of particles for their detection. The parameters of the gas above the nozzle are determined (compositions and pressure) at which intensive molecule clustering occurs. It is found that in the case of the CF3Br gas without carrier when the pressure P0 above the nozzle does not exceed 4 atm, molecular clusters actually are not generated in the beam. If the gas mixture of CF3Br with argon is used at a pressure ratio 1 : N, where N >= 3, and the total pressure above the nozzle is P0 >= 2 atm, then there occurs molecule clustering. We study the dependences of the efficiency of suppressing the molecule clustering on parameters of the exciting pulse, gas parameters above the nozzle, and on a distance of the molecule irradiation zone from the nozzle exit section. It is shown that in the case of resonant vibrational excitation of gas-dynamically cooled CF3Br molecules at the nozzle exit one can realise isotope-selective suppression of molecule clustering with respect to bromine isotopes. With the CF3Br - Ar mixtures having the pressure ratio 1 : 3 and 1 : 15, the enrichment factors obtained with respect to bromine isotopes are kenr ≈ 1.05 ± 0.005 and kenr ≈ 1.06 ± 0.007, respectively, under jet irradiation by laser emission in the 9R(30) line (1084.635 cm-1). The results obtained let us assume that this method can be used to control clustering of molecules comprising heavy element isotopes, which have a small isotopic shift in IR absorption spectra.

Beam-profile monitor using a sodium-vapour

CERN Multimedia

1972-01-01

Beam-profile monitor using a sodium-vapour curtain at 45 degrees to the ISR beam in Ring I (sodium generator is in white cylinder just left of centre). Electrons produced by ionization of the sodium vapour give an image of the beam on a fluorescent screen that is observed by a TV camera (at upper right).

Hot-wire chemical vapour deposition of carbon nanotubes

CSIR Research Space (South Africa)

Cummings, FR

2006-07-01

Full Text Available ablation of graphite, carbon-arc discharge and chemical vapour deposition (CVD). However, some of these techniques have been shown to be expensive due to high deposition temperatures and are not easily controllable. Recently hot-wire chemical vapour...

Lasers probe the atomic nucleus

International Nuclear Information System (INIS)

Eastham, D.

1986-01-01

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

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

CERN Document Server

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

2006-01-01

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

Sulfate and sulfide sulfur isotopes (δ34S and δ33S) measured by solution and laser ablation MC-ICP-MS: An enhanced approach using external correction

Science.gov (United States)

Pribil, Michael; Ridley, William I.; Emsbo, Poul

2015-01-01

Isotope ratio measurements using a multi-collector inductively coupled plasma mass spectrometer (MC-ICP-MS) commonly use standard-sample bracketing with a single isotope standard for mass bias correction for elements with narrow-range isotope systems measured by MC-ICP-MS, e.g. Cu, Fe, Zn, and Hg. However, sulfur (S) isotopic composition (δ34S) in nature can range from at least − 40 to + 40‰, potentially exceeding the ability of standard-sample bracketing using a single sulfur isotope standard to accurately correct for mass bias. Isotopic fractionation via solution and laser ablation introduction was determined during sulfate sulfur (Ssulfate) isotope measurements. An external isotope calibration curve was constructed using in-house and National Institute of Standards and Technology (NIST) Ssulfate isotope reference materials (RM) in an attempt to correct for the difference. The ability of external isotope correction for Ssulfate isotope measurements was evaluated by analyzing NIST and United States Geological Survey (USGS) Ssulfate isotope reference materials as unknowns. Differences in δ34Ssulfate between standard-sample bracketing and standard-sample bracketing with external isotope correction for sulfate samples ranged from 0.72‰ to 2.35‰ over a δ34S range of 1.40‰ to 21.17‰. No isotopic differences were observed when analyzing Ssulfide reference materials over a δ34Ssulfide range of − 32.1‰ to 17.3‰ and a δ33S range of − 16.5‰ to 8.9‰ via laser ablation (LA)-MC-ICP-MS. Here, we identify a possible plasma induced fractionation for Ssulfate and describe a new method using external isotope calibration corrections using solution and LA-MC-ICP-MS.

Spatial Distribution of Stable Isotopes of Precipitation in Kumamoto, Japan

Energy Technology Data Exchange (ETDEWEB)

Anoue, M. T.; Shimada, J. [Graduate School of Science and Technology, Kumamoto University (Japan); Ichiyanagi, K. [Graduate School of Science and Technology, Kumamoto University and Japan Agency for Marine-Earth Science and Technology (Japan)

2013-07-15

To understand the spatial distribution of stable isotopic compositions in precipitation, precipitation samples were collected every two weeks from november 2009 to december 2010 at 6 points in Kumamoto, Japan. The {delta}{sup 18}O and {delta}{sup 2}H of precipitation samples were measured by isotope ratio mass spectrometry (Delta-S) with CO{sub 2}/H2{sub O} equivalent method for {delta}{sup 18}O and the chromium reduction method for {delta}2H. The range of {delta}{sup 18}O and d-excess (= {delta}{sup 2}H - 8 {delta}{sup 18}O) in precipitation is from -13.4 per mille to -3.5 per mille and from 2.6 per mille to 35.6 per mille , respectively. Seasonal variability of {delta}{sup 18}O (d-excess) in precipitation was low (high) in winter and high (low) in summer. The seasonal wind of this study area was dominated by south-westerly in summer (from June to August) and north-westerly in winter (from December to February). These wind regimes indicate seasonal variabilities of the water vapour pathway from the origin. In this paper the trend of inland effect to the {delta}{sup 18}O for both south-westerly and north-westerly are also considered. As a result, significant correlation between distances from the coastal line at south-westerly or north-westerly and {delta}{sup 18}O in precipitation was recognized, particularly from 18 February to 7 March and from 29 September to 19 October in 2010 (statistically significant with 5% level). Furthermore, in order to evaluate the course of precipitation, the column total of water vapour flux was considered in the whole period by using JRA-25 and JCDAS. It is interesting that the inland effect corresponded to the column total of water vapour flux at south-westerly (north-westerly). Hence, it is conceivable that the spatial distribution of {delta}{sup 18}O in precipitation was controlled by a column total of water vapour flux in this area. (author)

Medical cannabis use in Canada: vapourization and modes of delivery

Directory of Open Access Journals (Sweden)

Samantha Shiplo

2016-10-01

Full Text Available Abstract Background The mode of medical cannabis delivery—whether cannabis is smoked, vapourized, or consumed orally—may have important implications for its therapeutic efficacy and health risks. However, there is very little evidence on current patterns of use among Canadian medical cannabis users, particularly with respect to modes of delivery. The current study examined modes of medical cannabis delivery following regulatory changes in 2014 governing how Canadians access medical cannabis. Methods A total of 364 approved adult Canadian medical cannabis users completed an online cross-sectional survey between April and June 2015. The survey examined patterns of medical cannabis use, modes of delivery used, and reasons for use. Participants were recruited through a convenience sample from nine Health Canada licensed producers. Results Using a vapourizer was the most popular mode of delivery for medical cannabis (53 %, followed by smoking a joint (47 %. The main reason for using a vapourizer was to reduce negative health consequences associated with smoking. A majority of current vapourizer users reported using a portable vapourizer (67.2 %, followed by a stationary vapourizer (41.7 %, and an e-cigarette or vape pen (19.3 %. Current use of a vapourizer was associated with fewer respiratory symptoms (AOR = 1.28, 95 % CI 1.05–1.56, p = 0.01. Conclusions The findings suggest an increase in the popularity of vapourizers as the primary mode of delivery among approved medical users. Using vapourizers has the potential to prevent some of the adverse respiratory health consequences associated with smoking and may serve as an effective harm reduction method. Monitoring implications of such current and future changes to medical cannabis regulations may be beneficial to policymakers.

High power CW output from low confinement asymmetric structure diode laser

NARCIS (Netherlands)

Iordache, G.; Buda, M.; Acket, G.A.; Roer, van de T.G.; Kaufmann, L.M.F.; Karouta, F.; Jagadish, C.; Tan, H.H.

1999-01-01

High power continuous wave output from diode lasers using low loss, low confinement, asymmetric structures is demonstrated. An asymmetric structure with an optical trap layer was grown by metal organic vapour phase epitaxy. Gain guided 50 µm wide stripe 1-3 mm long diode lasers were studied. 1.8 W

Ethanol vapour induced dilated cardiomyopathy in chick embryos

International Nuclear Information System (INIS)

Kamran, K.; Khan, M.Y.; Minhas, L.A.

2013-01-01

Objective: To study the effects of ethanol vapour inhalation on the heart chambers of chick embryo. Methods: The case-control study was conducted at the College of Physicians and Surgeons Pakistan regional centre in Islamabad from January to October 2007. Both experimental and control groups were divided into three sub-groups each, based on the day of the sacrifice. Each group was dissected on day 7, day 10 and day 22 or hatching whichever was earlier. The experimental sub-groups sacrificed on day 7, day 10 and on hatching, were exposed to ethanol vapours till day 6, 9 and 9 of incubation respectively. The diameter of all 4 chambers was measured in experimental hearts and compared with age-matched controls. SPSS 10 was used for statistical analysis. Results: Ethanol vapour exposure caused widening of all heart chambers in the experimental chick embryos sacrificed on day 7 and day 10 compared to the controls. The chambers of newly hatched chick hearts showed dilatation in all the chambers except the left ventricle. Conclusion: Ethanol vapour exposure during development affects the heart, resulting in the widening of all heart chambers. The exposure is as dangerous as drinking alcohol. Alcohol vapour exposure during development leads to progressive dilatation in different heart chambers, producing dilated cardiomyopathy. (author)

Large odd-even staggering in the very light platinum isotopes from laser spectroscopy

CERN Document Server

Le Blanc, F; Cabaret, L A; Crawford, J E; Duong, H T; Genevey, J; Girod, M; Huber, G; Krieg, M; Lee, J K P; Lettry, Jacques; Lunney, M D; Obert, J; Oms, J; Peru, S; Putaux, J C; Roussière, B; Sauvage, J; Sebastian, V; Zemlyanoi, S G

1998-01-01

Laser spectroscopy measurements have been carried out on very neutron-deficient platinum isotopes with the COMPLIS experimental set-up on line with the ISOLDE-Booster facility. For the first time, Hg alpha -decay was exploited to extend the very light platinum chain. Using the 5d/sup 9/6s /sup 3/D/sub 3/ to 5d/sup 9/6p /sup 3/P /sub 2/ optical transition, hyperfine spectra of /sup 182,181,180,179,178/Pt and /sup 183/Pt/sup m/ were recorded for the first time. The variation of the mean square charge radius between these nuclei, the magnetic moments of the odd isotopes and the quadrupole moment of /sup 183/Pt/sup m/ were thus measured. A large deformation change between /sup 183/Pt/sup 9/ and /sup 183/Pt/sup m/, an odd-even staggering of the charge radius and a deformation drop from A=179 are clearly observed. All these results are discussed and compared with microscopic theoretical predictions using Hartree-Fock- Bogolyubov calculations using the Gogny force. (20 refs).

No sodium in the vapour plumes of Enceladus.

Science.gov (United States)

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

2009-06-25

The discovery of water vapour and ice particles erupting from Saturn's moon Enceladus fuelled speculation that an internal ocean was the source. Alternatively, the source might be ice warmed, melted or crushed by tectonic motions. Sodium chloride (that is, salt) is expected to be present in a long-lived ocean in contact with a rocky core. Here we report a ground-based spectroscopic search for atomic sodium near Enceladus that places an upper limit on the mixing ratio in the vapour plumes orders of magnitude below the expected ocean salinity. The low sodium content of escaping vapour, together with the small fraction of salt-bearing particles, argues against a situation in which a near-surface geyser is fuelled by a salty ocean through cracks in the crust. The lack of observable sodium in the vapour is consistent with a wide variety of alternative eruption sources, including a deep ocean, a freshwater reservoir, or ice. The existing data may be insufficient to distinguish between these hypotheses.

Apparatus for isotopic separation using a high-frequency wave and coherent radiation

International Nuclear Information System (INIS)

Mourier, G.

1983-11-01

The purpose of the present invention is an apparatus for industrial separation of isotopes, using a high-frequency electromagnetic field and coherent radiation such as that from a laser. Separation of isotopes by isotopically selective ionization, followed by entrainment of the ions by means of a magnetic field, is known. The selective ionization operation can be carried out in two consecutive stages: excitation of the chosen isotope, from the ground energy state to a specified excited level, near ionization; the energy required for this first stage can be supplied by means of a laser, the laser radiation being characterized for high power and well-defined frequency; this stage offers the advantage of being easily made isotopically selective; then ionization of the excited atoms by means of supplying relatively weak energy which should be insufficient to ionize the nonexcited ions; this second stage can also be carried out by means of a laser

Prediction of vapour-liquid and vapour-liquid-liquid equilibria of nitrogen-hydrocarbon mixtures used in J-T refrigerators

Science.gov (United States)

Narayanan, Vineed; Venkatarathnam, G.

2018-03-01

Nitrogen-hydrocarbon mixtures are widely used as refrigerants in J-T refrigerators operating with mixtures, as well as in natural gas liquefiers. The Peng-Robinson equation of state has traditionally been used to simulate the above cryogenic process. Multi parameter Helmholtz energy equations are now preferred for determining the properties of natural gas. They have, however, been used only to predict vapour-liquid equilibria, and not vapour-liquid-liquid equilibria that can occur in mixtures used in cryogenic mixed refrigerant processes. In this paper the vapour-liquid equilibrium of binary mixtures of nitrogen-methane, nitrogen-ethane, nitrogen-propane, nitrogen-isobutane and three component mixtures of nitrogen-methane-ethane and nitrogen-methane-propane have been studied with the Peng-Robinson and the Helmholtz energy equations of state of NIST REFPROP and compared with experimental data available in the literature.

Polarized Raman spectroscopy of chemically vapour deposited diamond films

International Nuclear Information System (INIS)

Prawer, S.; Nugent, K.W.; Weiser, P.S.

1994-01-01

Polarized micro-Raman spectra of chemically vapour deposited diamond films are presented. It is shown that important parameters often extracted from the Raman spectra such as the ratio of the diamond to non-diamond component of the films and the estimation of the level of residual stress depend on the orientation of the diamond crystallites with respect to the polarization of the incident laser beam. The dependence originates from the fact that the Raman scattering from the non-diamond components in the films is almost completely depolarized whilst the scattering from the diamond components is strongly polarized. The results demonstrate the importance of taking polarization into account when attempting to use Raman spectroscopy in even a semi-quantitative fashion for the assessment of the purity, perfection and stress in CVD diamond films. 8 refs., 1 tab. 2 figs

Chemical vapour deposition synthetic diamond: materials, technology and applications

International Nuclear Information System (INIS)

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

2009-01-01

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

Oxygen isotope separation by isotopically selective infrared multiphoton dissociation of 2,3-dihydropyran

International Nuclear Information System (INIS)

Yokoyama, Atsushi; Ohba, Hironori; Akagi, Hiroshi; Yokoyama, Keiichi; Saeki, Morihisa; Katsumata, Keiichi

2008-01-01

Oxygen isotopic selectivity on infrared multiphoton dissociation of 2,3-dihydropyran has been studied by the examination of the effects of excitation frequency, laser fluence, and gas pressure on the dissociation probability of 2,3-dihydropyran and isotopic composition of products. Oxygen-18 was enriched in a dissociation product: 2-propenal. The enrichment factor of 18 O and the dissociation probability were measured at laser frequency between 1033.5 and 1057.3 cm -1 ; the laser fluence of 2.2 - 2.3 J/cm 2 ; and the 2,3-dihydropyran pressure of 0.27 kPa. The dissociation probability decreases as the laser frequency being detuned from the absorption peak of 2,3-dihydropyran around 1081 cm -1 . On the other hand, the enrichment factor increases with detuning the frequency. The enrichment factor of 18 O increases with increasing the 2,3-dihydropyran pressure at the laser fluence below 3 J/cm 2 and the laser frequency of 1033.5 cm -1 , whereas the yield of 2-propenal decreases with increasing the pressure. Very high enrichment factor of 751 was obtained by the irradiation of 0.53 kPa of 2,3-dihydropyran at 2.1 J/cm 2 . (author)

Stable isotope studies. Progress report, August 1, 1974--July 31, 1975

International Nuclear Information System (INIS)

Flynn, G.W.; Hsu, D.S.Y.; Preses, J.M.; Spindel, W.; Weston, R.E.

1975-01-01

Progress is reported in the following studies: selective two-step laser-induced photodissociation, unimolecular processes induced by multiple-photon absorption, and vibrational energy transfer processes involving isotopic species of sulfur dioxide. These laser-induced chemical reactions can possibly be applied to isotope separation

Barium Isotopes in Single Presolar Grains

Science.gov (United States)

Pellin, M. J.; Davis, A. M.; Savina, M. R.; Kashiv, Y.; Clayton, R. N.; Lewis, R. S.; Amari, S.

2001-01-01

Barium isotopic compositions of single presolar grains were measured by laser ablation laser resonant ionization mass spectrometry and the implications of the data for stellar processes are discussed. Additional information is contained in the original extended abstract.

Isotopic composition of precipitations in Brazil: isothermic models and the influence of evapotranspiration in the Amazonic Basin

International Nuclear Information System (INIS)

Dall'Olio, Attilio.

1976-11-01

The simplest theoretical models of the isotopic fractionation of water during equilibrium isothermical processes are analized in detail. The theoretical results are applied to the interpretation of the stable isotope concentrations in the precipitations of 11 Brazilian cities that belong to the international network of IAEA/WMO. The analysis shows that the experimental data are fairly consistent with such equilibrium models; no non-equilibrium processes need to be assumed. The study of the stable isotope content of precipitations in the Amazonic Basin suggests some modifications to the models in order that the evapotranspiration contribution to the vapour balance be taken into account [pt

High mass isotope separation arrangement

International Nuclear Information System (INIS)

Eerkens, J.W.

1976-01-01

An isotope separation arrangement for separating a preselected isotope from a mixture of chemically-identical but isotopically-different molecules by either photon-induced pure revibrational or vibronic selective excitation of the molecules containing the atoms of the isotope to be separated from a lower to a higher energy state, and a chemical reaction of the higher energy state molecules with a chemically-reactive agent to form a chemical compound containing primarily the atoms of the isotope to be separated in a physicochemical state different from the physicochemical state of the mixture of chemically-identical but isotopically-different molecules. The chemical compound containing the atoms of the isotope to be separated may be subsequently processed to obtain the isotope. The laser configuration used to generate the photon beam is fully described

Contribution to the liquid-vapour equilibrium of potassium and sodium mixtures

International Nuclear Information System (INIS)

Schreinlechner, I.; Schwarz, N.

1975-10-01

In this paper the phase diagram of the binary system potassium-sodium in the liquid-vapour range was calculated for different pressures and temperatures, assuming the two metals acting as ideal solution. The assumption was verified by experimental results. It is thus possible to calculate the separation factor for the rectification of potassium and to estimate the content of sodium in the vapour phase during experiments with vapourized potassium from the data of the vapour pressures of the pure metals. (author)

Laser spectroscopy of cadmium isotopes: probing the nuclear structure between the neutron 50 and 82 shell closures

CERN Multimedia

Blaum, K; Stroke, H H; Krieger, A R

We propose to study the isotopic chain of cadmium with high-resolution laser spectroscopy for the first time. Our goal is to determine nuclear spins, moments and root-mean-square charge radii of ground and isomeric states between the neutron 50 and 82 shell closures, contributing decisively to a better understanding of the nuclear structure in the vicinity of the doubly-magic $^{100}$Sn and $^{132}$Sn. On the neutron-rich side this is expected to shed light on a shell-quenching hypothesis and consequently on the duration of the r-process along the waiting-point nuclei below $^{130}$Cd. On the neutron-deficient side it may elucidate the role of the cadmium isotopes in the rp-process for rapidly accreting neutron stars.

Selective laser ionization for mass-spectral isotopic analysis

International Nuclear Information System (INIS)

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

1983-01-01

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

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

Energy Technology Data Exchange (ETDEWEB)

Sifi, R

2007-07-15

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

Spatially tracking 13C labeled substrate (bicarbonate) accumulation in microbial communities using laser ablation isotope ratio mass spectrometry

Energy Technology Data Exchange (ETDEWEB)

Moran, James J.; Doll, Charles G.; Bernstein, Hans C.; Renslow, Ryan S.; Cory, Alexandra B.; Hutchison, Janine R.; Lindemann, Stephen R.; Fredrickson, Jim K.

2014-08-25

This is a manuscript we would like to submit for publication in Environmental Microbiology Reports. This manuscript contains a description of a laser ablation isotope ratio mass spectrometry methodology developed at PNNL and applied to a microbial system at a PNNL project location – Hot Lake, Washington. I will submit a word document containing the entire manuscript with this Erica input request form.

Method and device for the enrichment of isotopes

International Nuclear Information System (INIS)

Stehle, H.

1976-01-01

A variation of a method for isotope enrichment by laser radiation is proposed which improves the selectivity and with it the economy of the method by eliminating undesired reactions caused by thermal activation. The method according to the invention is applied discontinuously in three steps: The isotope mixture and the reacting agents are fed to a vessel, a laser beam is passed through, and the contents are emptied into a vacuum tank while expanding adiabatically. The time steps are controlled. The method is explained using the example of separating an isotope mixture of UF 6 . (UWI) [de

Hyperfine structure and isotope shift of the neutron-rich barium isotopes 139-146Ba and 148Ba

International Nuclear Information System (INIS)

Wendt, K.; Ahmad, S.A.; Klempt, W.; Neugart, R.; Otten, E.W.

1988-01-01

The hyperfine structure and isotope shift in the 6s 2 S 1/2 -6p 2 P 3/2 line of Ba II (455.4 nm) have been measured by collinear fast-beam laser spectroscopy for the neutron-rich isotopes 139-146 Ba and 148 Ba. Nuclear moments and mean square charge radii of these isotopes have been recalculated. The isotope shift of the isotope 148 Ba (T 1/2 = 0.64 s) could be studied for the first time, yielding δ 2 > 138,148 = 1.245(3) fm 2 . (orig.)

Environmental isotope data no.1: World survey of isotope concentration in precipitation (1953-1963)

International Nuclear Information System (INIS)

1969-01-01

This volume reports environmental isotope (tritium, deuterium and oxygen-18) concentrations in monthly samples of precipitation taken by a global network of 155 stations in the period 1953-1963. Selected meteorological data (amount of precipitation, vapour pressure and temperature) are presented to aid the user in hydrological and hydrometerological studies. The collection of the precipitation samples is carried out by the meteorological services of 65 countries and territories. Analyses of the network samples are done in co-operating laboratories in Canada, Denmark, India, Israel, New Zealand, Sweden and the United States of America and in the IAEA laboratory in Vienna. 4 refs, 2 figs

Laser-excited atomic-fluorescence spectrometry with electrothermal tube atomization.

Science.gov (United States)

Vera, J A; Leong, M B; Stevenson, C L; Petrucci, G; Winefordner, J D

1989-12-01

The performance of graphite-tube electrothermal atomizers is evaluated for laser-excited atomic-fluorescence spectrometry for several elements. Three pulsed laser systems are used to pump tunable dye lasers which subsequently are used to excite Pb, Ga, In, Fe, Ir, and Tl atoms in the hot graphite tube. The dye laser systems used are pumped by nitrogen, copper vapour and Nd:YAG lasers. Detection limits in the femtogram and subfemtogram range are typically obtained for all elements. A commercial graphite-tube furnace is important for the successful utilization of the laser-based method when the determination of trace elements is intended, especially when complicated matrices may be present.

Advanced uranium enrichment processes

International Nuclear Information System (INIS)

Clerc, M.; Plurien, P.

1986-01-01

Three advanced Uranium enrichment processes are dealt with in the report: AVLIS (Atomic Vapour LASER Isotope Separation), MLIS (Molecular LASER Isotope Separation) and PSP (Plasma Separation Process). The description of the physical and technical features of the processes constitutes a major part of the report. If further presents comparisons with existing industrially used enrichment technologies, gives information on actual development programmes and budgets and ends with a chapter on perspectives and conclusions. An extensive bibliography of the relevant open literature is added to the different subjects discussed. The report was drawn up by the nuclear research Centre (CEA) Saclay on behalf of the Commission of the European Communities

Calculation of vapour bubble growth on the lower generatrix of horizontal tubes

International Nuclear Information System (INIS)

Chajka, V.D.

1987-01-01

The known models of vapour bubble growth are compared with experimental data. Cinematographic study of vapour formation during water boiling was carried out with elements of horizontal tubes of copper 10, 16, 24, 34 and 70 mm in diameter under the pressure of 100 kPa and specific thermal loadings of 20 and 40 kW/m 2 . According to the experimental data the main volume of vapour phase is occupied by vapour bubbles from the lower part of the horizontal tube. Five stages of vapour bubble growth on the lower generatrix of the horizontal tube: nucleation, growth to the point of breaking off from nucleate centre, the breaking off from the nucleate centre, the tube surface flowing around during floating up, the breaking off from the tube surface, were singled out. The shape of vapour volume varied during the whole period of the bubble growth and it was mainly determined by the horizontal tube diameter. The change of vapour bubble radius in time is the function of the horizontal tube diameter. Comparison of the experimental data with the known models of vapour bubble growth has shown, that every stage of vapour bubble growth on the lower generatrix of the tube is determined by the complex of thermal and hydrodynamic conditions, the effect of which depends on the horizontal tube diameter

HF laser

International Nuclear Information System (INIS)

Suzuki, Kazuya; Iwasaki, Matae

1977-01-01

A review is made of the research and development of HF chemical laser and its related work. Many gaseous compounds are used as laser media successfully; reaction kinetics and technological problems are described. The hybrid chemical laser of HF-CO 2 system and the topics related to the isotope separation are also included. (auth.)

Laser and uranium isotope separation

International Nuclear Information System (INIS)

Gilles, L.

1987-07-01

Industrial processes for uranium enrichment, economical context and market are briefly reviewed. Then physical principles of the two lasers processes: SILMO (molecular process) and SILVA (atomic process) are presented insisting on criteria for choosing lasers used in the SILVA process which will be developed in France [fr

System for illuminating a region for isotopically selective photoexcitation

International Nuclear Information System (INIS)

Debaryshe, P.G.; Janes, G.S.; Levy, R.H.; Lindenmeier, C.W.

1979-01-01

A method is described to improve laser beam utilization in isotope separation techniques (using laser induced isotopically selective photoexcitation) by increasing the probability of photon absorption without extreme beam propagation lengths. For this purpose an optical reflection system has been designed for illuminating substantially all of three-dimensional space of a transversely flowing vapor with multiple traversals of a beam of radiation. (UK)

Ethanol vapour sensing properties of screen printed WO 3 thick films

Indian Academy of Sciences (India)

The ethanol vapour sensing properties of these thick films were investigated at different operating temperatures and ethanol vapour concentrations. The WO3 thick films exhibit excellent ethanol vapour sensing properties with a maximum sensitivity of ∼1424.6% at 400°C in air atmosphere with fast response and recovery ...

Intercomparison of TCCON and MUSICA Water Vapour Products

Science.gov (United States)

Weaver, D.; Strong, K.; Deutscher, N. M.; Schneider, M.; Blumenstock, T.; Robinson, J.; Notholt, J.; Sherlock, V.; Griffith, D. W. T.; Barthlott, S.; García, O. E.; Smale, D.; Palm, M.; Jones, N. B.; Hase, F.; Kivi, R.; Ramos, Y. G.; Yoshimura, K.; Sepúlveda, E.; Gómez-Peláez, Á. J.; Gisi, M.; Kohlhepp, R.; Warneke, T.; Dohe, S.; Wiegele, A.; Christner, E.; Lejeune, B.; Demoulin, P.

2014-12-01

We present an intercomparison between the water vapour products from the Total Carbon Column Observing Network (TCCON) and the MUlti-platform remote Sensing of Isotopologues for investigating the Cycle of Atmospheric water (MUSICA), two datasets from ground-based Fourier Transform InfraRed (FTIR) spectrometers with good global representation. Where possible, comparisons to radiosondes are also included. The near-infrared TCCON measurements are optimized to provide precise monitoring of greenhouse gases for carbon cycle studies; however, TCCON's retrievals also produce water vapour products. The mid-infrared MUSICA products result from retrievals optimized to give precise and accurate information about H2O, HDO, and δD. The MUSICA water vapour products have been validated by extensive intercomparisons with H2O and δD in-situ measurements made from ground, radiosonde, and aircraft (Schneider et al. 2012, 2014), as well as by intercomparisons with satellite-based H2O and δD remote sensing measurements (Wiegele et al., 2014). This dataset provides a valuable reference point for other measurements of water vapour. This study is motivated by the limited intercomparisons performed for TCCON water vapour products and limited characterisation of their uncertainties. We compare MUSICA and TCCON products to assess the potential for TCCON measurements to contribute to studies of the water cycle, water vapour's role in climate and use as a tracer for atmospheric dynamics, and to evaluate the performance of climate models. The TCCON and MUSICA products result from measurements taken using the same FTIR instruments, enabling a comparison with constant instrumentation. The retrieval techniques differ, however, in their method and a priori information. We assess the impact of these differences and characterize the comparability of the TCCON and MUSICA datasets.

Online induction heating for determination of isotope composition of woody stem water with laser spectrometry: A methods assessment

Science.gov (United States)

Lazarus, Brynne E.; Germino, Matthew; Vander Veen, Jessica L.

2016-01-01

Application of stable isotopes of water to studies of plant–soil interactions often requires a substantial preparatory step of extracting water from samples without fractionating isotopes. Online heating is an emerging approach for this need, but is relatively untested and major questions of how to best deliver standards and assess interference by organics have not been evaluated. We examined these issues in our application of measuring woody stem xylem of sagebrush using a Picarro laser spectrometer with online induction heating. We determined (1) effects of cryogenic compared to induction-heating extraction, (2) effects of delivery of standards on filter media compared to on woody stem sections, and (3) spectral interference from organic compounds for these approaches (and developed a technique to do so). Our results suggest that matching sample and standard media improves accuracy, but that isotopic values differ with the extraction method in ways that are not due to spectral interference from organics.

Laser diagnostics of a diamond depositing chemical vapour deposition gas-phase environment

Energy Technology Data Exchange (ETDEWEB)

Smith, James Anthony

2002-07-01

Studies have been carried out to understand the gas-phase chemistry underpinning diamond deposition in hot filament and DC-arcjet chemical vapour deposition (CVD) systems. Resonance enhanced Multiphoton lonisation (REMPI) techniques were used to measure the relative H atom and CH{sub 3} radical number densities and local gas temperatures prevalent in a hot filament reactor, operating on Ch{sub 4}/H{sub 2} and C{sub 2}H{sub 2}/H{sub 2} gas mixtures. These results were compared to a 3D-computer simulation, and hence provided an insight into the nature of the gas-phase chemistry with particular reference to C{sub 2}{yields}C{sub 1} species conversion. Similar experimental and theoretical studies were also carried out to explain the chemistry involved in NH{sub 3}/CH{sub 4}/H{sub 2} and N{sub 2}/CH{sub 4}/H{sub 2} gas mixtures. It was demonstrated that the reactive nature of the filament surface was dependent on the addition of NH{sub 3}, influencing atomic hydrogen production, and thus the H/C/N gas-phase chemistry. Studies of the DC-arcjet diamond CVD reactor consisted of optical emission spectroscopic studies of the plume during deposition from an Ar/H{sub 2}/CH{sub 4}/N{sub 2} gas mixture. Spatially resolved species emission intensity maps were obtained for C{sub 2}(d{yields}a), CN(B{yields}X) and H{sub {beta}} from Abel-inverted datasets. The C{sub 2}(d{yields}a) and CN(B{yields}X) emission intensity maps both show local maxima near the substrate surface. SEM and Laser Raman analyses indicate that N{sub 2} additions lead to a reduction in film quality and growth rate. Photoluminescence and SIMS analyses of the grown films provide conclusive evidence of nitrogen incorporation (as chemically bonded CN). Absolute column densities of C{sub 2}(a) in a DC-arcjet reactor operating on an Ar/H{sub 2}/CH{sub 4} gas mixture, were measured using Cavity ring down spectroscopy. Simulations of the measured C{sub 2}(v=0) transition revealed a rotational temperature of {approx

Considering the use of polyethylene vapour barriers in temperate climates

Energy Technology Data Exchange (ETDEWEB)

Lawton, M.D. [Morrison Hershfield Ltd., Vancouver, BC (Canada); Brown, W.C. [Morrison Hershfield Ltd., Ottawa, ON (Canada)

2003-07-01

Most building envelope assemblies in Canada must include a vapour barrier in order to comply with Canadian building codes. The installation of sheet polyethylene between the studs and the interior sheathing has been the most common method because it provides more diffusion resistance than necessary to control condensation within a building envelope assembly. It has been suggested that the presence of a polyethylene vapour barrier on the warm-in-winter side of the insulation may actually cause moisture problems because a very low permeance material increases average moisture levels. This paper examined the theory that a vapour barrier at this location restricts drying of moisture that enters the building from outside. Pacific coastal regions of Canada and the United States were presented as examples. Other ways that a polyethylene vapour barrier affects wall performance were also presented. The advanced hygrothermal model HygIRC, developed by Canada's National Research Council, was used to simulate the performance of a wall assembly. Results indicate that eliminating the low permeance polyethylene vapour barrier does not necessarily reduce the risk of moisture problems. Removal of the vapour barrier may have some negative effects, such as increased risk of periodic moisture accumulation and mold growth on paper-faced gypsum board. 7 refs., 2 tabs., 7 figs.

Detection of polar vapours

International Nuclear Information System (INIS)

Blyth, D.A.

1980-01-01

Apparatus for monitoring for polar vapours in a gas consists of (i) a body member defining a passage through which a continuous stream of the gas passes; (ii) an ionising source associated with a region of the passage such that ionization of the gas stream takes place substantially only within the region and also any polar vapour molecules present therein will react with the gas formed to generate ion clusters; and (iii) an electrode for collecting ions carried by the gas stream, the electrode being positioned in the passage downstream of the region and separated from the region by a sufficient distance to ensure that no substantial number of the gas ions formed in said region remains in the gas stream at the collector electrode whilst ensuring that a substantial proportion of the ion clusters formed in the region does remain in the gas stream at the collector electrode. (author)

The millennium water vapour drop in chemistry–climate model simulations

Directory of Open Access Journals (Sweden)

S. Brinkop

2016-07-01

Full Text Available This study investigates the abrupt and severe water vapour decline in the stratosphere beginning in the year 2000 (the "millennium water vapour drop" and other similarly strong stratospheric water vapour reductions by means of various simulations with the state-of-the-art Chemistry-Climate Model (CCM EMAC (ECHAM/MESSy Atmospheric Chemistry Model. The model simulations differ with respect to the prescribed sea surface temperatures (SSTs and whether nudging is applied or not. The CCM EMAC is able to most closely reproduce the signature and pattern of the water vapour drop in agreement with those derived from satellite observations if the model is nudged. Model results confirm that this extraordinary water vapour decline is particularly obvious in the tropical lower stratosphere and is related to a large decrease in cold point temperature. The drop signal propagates under dilution to the higher stratosphere and to the poles via the Brewer–Dobson circulation (BDC. We found that the driving forces for this significant decline in water vapour mixing ratios are tropical sea surface temperature (SST changes due to a coincidence with a preceding strong El Niño–Southern Oscillation event (1997/1998 followed by a strong La Niña event (1999/2000 and supported by the change of the westerly to the easterly phase of the equatorial stratospheric quasi-biennial oscillation (QBO in 2000. Correct (observed SSTs are important for triggering the strong decline in water vapour. There are indications that, at least partly, SSTs contribute to the long period of low water vapour values from 2001 to 2006. For this period, the specific dynamical state of the atmosphere (overall atmospheric large-scale wind and temperature distribution is important as well, as it causes the observed persistent low cold point temperatures. These are induced by a period of increased upwelling, which, however, has no corresponding pronounced signature in SSTs anomalies in the tropics

Laser beam-plasma plume interaction during laser welding

Science.gov (United States)

Hoffman, Jacek; Moscicki, Tomasz; Szymanski, Zygmunt

2003-10-01

Laser welding process is unstable because the keyhole wall performs oscillations which results in the oscillations of plasma plume over the keyhole mouth. The characteristic frequencies are equal to 0.5-4 kHz. Since plasma plume absorbs and refracts laser radiation, plasma oscillations modulate the laser beam before it reaches the workpiece. In this work temporary electron densities and temperatures are determined in the peaks of plasma bursts during welding with a continuous wave CO2 laser. It has been found that during strong bursts the plasma plume over the keyhole consists of metal vapour only, being not diluted by the shielding gas. As expected the values of electron density are about two times higher in peaks than their time-averaged values. Since the plasma absorption coefficient scales as ~N2e/T3/2 (for CO2 laser radiation) the results show that the power of the laser beam reaching the metal surface is modulated by the plasma plume oscillations. The attenuation factor equals 4-6% of the laser power but it is expected that it is doubled by the refraction effect. The results, together with the analysis of the colour pictures from streak camera, allow also interpretation of the dynamics of the plasma plume.

Separating uranium by laser: the atomic process

Energy Technology Data Exchange (ETDEWEB)

Destro, Marcelo G.; Damiao, Alvaro J.; Neri, Jose W.; Schwab, Carlos; Rodrigues, Nicolau A.S.; Riva, Rudimar [Centro Tecnico Aeroespacial (CTA-IEAv), Sao Jose dos Campos, SP (Brazil). Inst. de Estudos Avancados

1996-07-01

Among the countries around the world that utilizes nuclear energy, several ones are investing significantly in the development of laser techniques applied to isotope separation. In Brazil these studies are concentrated in one research institute, the IEAv (Institute for Advanced Studies), and aim at demonstrating the viability of this process using, as much as possible, resources available in the country. In this paper we briefly describe the laser methods for isotope separation, giving an overview of the present research and development status in this area. We also show some results obtained our laboratories. We focused this report on the atomic route for laser isotope separation, mainly in the areas of laser development and spectroscopy. (author)

Separating uranium by laser: the atomic process

International Nuclear Information System (INIS)

Destro, Marcelo G.; Damiao, Alvaro J.; Neri, Jose W.; Schwab, Carlos; Rodrigues, Nicolau A.S.; Riva, Rudimar

1996-01-01

Among the countries around the world that utilizes nuclear energy, several ones are investing significantly in the development of laser techniques applied to isotope separation. In Brazil these studies are concentrated in one research institute, the IEAv (Institute for Advanced Studies), and aim at demonstrating the viability of this process using, as much as possible, resources available in the country. In this paper we briefly describe the laser methods for isotope separation, giving an overview of the present research and development status in this area. We also show some results obtained our laboratories. We focused this report on the atomic route for laser isotope separation, mainly in the areas of laser development and spectroscopy. (author)

[Atomic Vapor Laser Isotope Separation (AVLIS) program

International Nuclear Information System (INIS)

1992-01-01

This report summarizes work performed for the Atomic Vapor Laser Isotope Separation (AVLIS) program from January through July, 1992. Each of the tasks assigned during this period is described, and results are presented. Section I details work on sensitivity matrices for the UDS relay telescope. These matrices show which combination of mirror motions may be performed in order to effect certain changes in beam parameters. In Section II, an analysis is given of transmission through a clipping aperture on the launch telescope deformable mirror. Observed large transmission losses could not be simulated in the analysis. An EXCEL spreadsheet program designed for in situ analysis of UDS optical systems is described in Section III. This spreadsheet permits analysis of changes in beam first-order characteristics due to changes in any optical system parameter, simple optimization to predict mirror motions needed to effect a combination of changes in beam parameters, and plotting of a variety of first-order data. Optical systems may be assembled directly from OSSD data. A CODE V nonsequential model of the UDS optical system is described in Section IV. This uses OSSD data to build the UDS model; mirror coordinates may thus be verified. Section V summarizes observations of relay telescope performance. Possible procedures which allow more accurate assessment of relay telescope performance are given

In-source laser spectroscopy of mercury isotopes

CERN Multimedia

This proposal follows on from the Letter of Intent, I-153. The neutron-deficient mercury isotopes are one of the prime examples of shape coexistence anywhere in the nuclear chart. Wide-ranging and complementary experimental and theoretical approaches have been used to investigate their structure over the last few years, however mean-square charge radii are unknown for isotopes with $\\textit{A}$ < 181. It is proposed to measure the isotope shift (IS) and hyperfine structure (HFS) of the 253-nm transition in $^{177-182}$Hg in an attempt to study the propagation of the famous odd-even staggering behaviour. At the other end of the chain, no information exists on the optical spectroscopy of Hg isotopes beyond the $\\textit{N}$ = 126 shell closure. There is a well-known "kink" in mean-square charge radii beyond this point in the even $\\textit{Z}$ $\\geq$ 82 elements. It is proposed to measure the IS of $^{207,208}$Hg in order to provide the first information on this effect below $\\textit{Z}$ = 82.

Assessing the ability of isotope-enabled General Circulation Models to simulate the variability of Iceland water vapor isotopic composition

Science.gov (United States)

Erla Sveinbjornsdottir, Arny; Steen-Larsen, Hans Christian; Jonsson, Thorsteinn; Ritter, Francois; Riser, Camilla; Messon-Delmotte, Valerie; Bonne, Jean Louis; Dahl-Jensen, Dorthe

2014-05-01

During the fall of 2010 we installed an autonomous water vapor spectroscopy laser (Los Gatos Research analyzer) in a lighthouse on the Southwest coast of Iceland (63.83°N, 21.47°W). Despite initial significant problems with volcanic ash, high wind, and attack of sea gulls, the system has been continuously operational since the end of 2011 with limited down time. The system automatically performs calibration every 2 hours, which results in high accuracy and precision allowing for analysis of the second order parameter, d-excess, in the water vapor. We find a strong linear relationship between d-excess and local relative humidity (RH) when normalized to SST. The observed slope of approximately -45 o/oo/% is similar to theoretical predictions by Merlivat and Jouzel [1979] for smooth surface, but the calculated intercept is significant lower than predicted. Despite this good linear agreement with theoretical calculations, mismatches arise between the simulated seasonal cycle of water vapour isotopic composition using LMDZiso GCM nudged to large-scale winds from atmospheric analyses, and our data. The GCM is not able to capture seasonal variations in local RH, nor seasonal variations in d-excess. Based on daily data, the performance of LMDZiso to resolve day-to-day variability is measured based on the strength of the correlation coefficient between observations and model outputs. This correlation coefficient reaches ~0.8 for surface absolute humidity, but decreases to ~0.6 for δD and ~0.45 d-excess. Moreover, the magnitude of day-to-day humidity variations is also underestimated by LMDZiso, which can explain the underestimated magnitude of isotopic depletion. Finally, the simulated and observed d-excess vs. RH has similar slopes. We conclude that the under-estimation of d-excess variability may partly arise from the poor performance of the humidity simulations.

Laser assisted ratio analysis - An alternative to GC/IRMS for CO2

International Nuclear Information System (INIS)

Murnick, D.E.

2001-01-01

A new technique for laser based analysis of carbon isotope ratios, with the acronym LARA, based on large isotope shifts in molecular spectra, the use of fixed frequency isotopic lasers, and sensitive detection via the laser optogalvanic effect is reviewed and compared with GC/IRMS for carbon dioxide in specific applications. The possibility for development of new classes of isotope ratio measurement systems with LARA is explored. (author)

Morphological modification of TiC by laser irradiation

International Nuclear Information System (INIS)

Baechli, A.; Blatter, A.

1991-01-01

The technique of laser quenching has been applied to TiC coatings on cemented carbide WC/Co material. In contrast to the original columnar morphology of TiC prepared by chemical vapour deposition, the laser-processed surface is isotropic and flat. With the proper parameters a smooth interface is formed and the TiC is alloyed to the substrate. The chemical composition as well as the beneficial tribological properties can be preserved. (orig.)

Historical review of CEA researches on uranium enrichment

International Nuclear Information System (INIS)

Camarcat, N.

1997-01-01

The various uranium enrichment processes that have been studied at the CEA since 1953 are briefly reviewed: gaseous diffusion (which led to the construction of EURODIF plant), chemical treatments (which were abandoned in 1988 for cost reasons), gaseous ultracentrifugation, electromagnetic processes, laser techniques (since 1980) and especially the SILVA technique (atomic vapour laser isotopic separation) which could take the place of the gaseous diffusion technique when the EURODIF plant will need to be renewed before 2010

Analysis of a combined Rankine-vapour-compression refrigeration cycle

International Nuclear Information System (INIS)

Aphornratana, Satha; Sriveerakul, Thanarath

2010-01-01

This paper describes a theoretical analysis of a heat-powered refrigeration cycle, a combined Rankine-vapour-compression refrigeration cycle. This refrigeration cycle combines an Organic Rankine Cycle and a vapour-compression cycle. The cycle can be powered by low grade thermal energy as low as 60 deg. C and can produce cooling temperature as low as -10 deg. C. In the analysis, two combined Rankine-vapour-compression refrigeration cycles were investigated: the system with R22 and the system with R134a. Calculated COP values between 0.1 and 0.6 of both the systems were found.

Laser ablation molecular isotopic spectrometry of water for {sub 1}D{sup 2}/{sub 1}H{sup 1} ratio analysis

Energy Technology Data Exchange (ETDEWEB)

Sarkar, Arnab [Lawrence Berkeley National Laboratory, University of California, Berkeley, CA 94720 (United States); Fuel Chemistry Division, Bhabha Atomic Research Centre, Mumbai 400085 (India); Mao, Xianglei; Chan, George C.-Y. [Lawrence Berkeley National Laboratory, University of California, Berkeley, CA 94720 (United States); Russo, Richard E., E-mail: rerusso@lbl.gov [Lawrence Berkeley National Laboratory, University of California, Berkeley, CA 94720 (United States)

2013-10-01

Laser Ablation Molecular Isotopic Spectrometry (LAMIS) has been investigated for optical isotopic analysis of the deuterium to protium ratio in enriched water samples in ambient air at atmospheric pressure. Multivariate PLSR (Partial Least Squares Regression) based calibrations were carried out and validated using multiple statistical parameters. Comparisons of results are reported using two spectrometers having two orders of magnitude difference in spectral resolution. The accuracy and precision of isotopic analysis depends on the spectral resolution and the inherent isotope shift of the elements. The requirements for spectral resolution of the measurement system can be significantly relaxed when the isotopic abundance ratio is determined using chemometric processing of the spectra. Large isotopic shifts in the individual rotational branches of OH/OD molecular emission spectra were measured. Optimized temporal conditions for LAMIS measurements were established. Several sub-regions of spectra were used for PLSR calibration and the results demonstrate that both the emission intensity and degree of spectral differentiation affect the quality of the PLSR calibration. LAMIS results also were compared with traditional LIBS results obtained using PLSR and a spectral deconvolution method, demonstrating the advantages of LAMIS over LIBS with respect to isotopic composition determination. - Highlights: • D/H isotopic ratio in water over a large dynamic range was measured by LAMIS. • PLSR based multivariate calibration was used for construction of calibrations. • Region of interest significantly affects the analytical results of isotopic ratio. • LAMIS has improved results over LIBS irrespective of the spectrometer resolution. • The superiority is more prominent in the case using low resolution spectrometer.

Resonance ionization mass spectrometry using tunable diode lasers

International Nuclear Information System (INIS)

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

1990-01-01

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

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

The vapour pressure of americium(III) chloride

International Nuclear Information System (INIS)

Schuster, W.

1983-01-01

Based on the method described by Fischer, an ultramicro-size appratus was developed for static determination of the saturation vapour pressure of highly radioactive materials. The apparatus was tested with MgCl 2 , MnCl 2 , HoCl 3 and ScF 3 . The vapour pressure curves of MgCl 2 and MnCl 2 were in good agreement with other publications and thus proved the efficiency of the apparatus in spite of its difficulties of handling. The values measured for HoCl 3 and ScF 3 differed from those of earlier publications. However, these deviations have been observed before and may be the result of the different measuring principles of static and dynamic methods. For AmCl 3 , the following vapour pressure equation was established: log psub(Torr)=-(11826/T)+10.7. The thermodynamic parameters of the evaporation process were calculated on this basis, and the values for AmBr 3 and PnCl 3 were determined by extrapolation. (orig.) [de

Effect of paint on vapour resistivity in plaster

Directory of Open Access Journals (Sweden)

de Villanueva, L.

2008-12-01

Full Text Available The vapour resistivity of plaster coatings such as paint and their effectiveness as water repellents were studied in several types of plaster. To this end, painted, unpainted and pigmented specimens were tested. Experimental values were collected on diffusion and vapour permeability, or its inverse, water vapour resistivity.The data obtained were very useful for evaluating moisture exchange between plaster and the surrounding air, both during initial drying and throughout the life of the material. They likewise served as a basis for ensuring the proper evacuation of water vapour in walls, and use of the capacity of the porous network in plaster products to regulate moisture content or serve as a water vapour barrier to avoid condensation.Briefly, the research showed that pigments, water-based paints and silicon-based water repellents scantly raised vapour resistance. Plastic paints, enamels and lacquers, however, respectively induced five-, ten- and twenty-fold increases in vapour resistivity, on average.Se estudia el fenómeno de la resistividad al vapor de los de yeso y el efecto impermeabilizante que producen los recubrimientos de pintura sobre diversos tipos de yeso y escayola. Para ello, se ensayan probetas desnudas y recubiertas con distintos tipos de pintura, así como coloreados en masa. Se obtienen valores experimentales de la difusividad o permeabilidad al vapor o su inverso la resistividad al vapor de agua.Los datos obtenidos son muy útiles para valorar el fenómeno del intercambio de humedad entre el yeso y el ambiente, tanto durante el proceso de su secado inicial, como en el transcurso de su vida. Así como para disponer soluciones adecuadas para la evacuación del vapor de agua a través de los cerramientos, para utilizar la capacidad de regulación de la humedad, que proporciona el entramado poroso de los productos de yeso, o para impedir el paso del vapor de agua y evitar condensaciones.Como resumen de la investigación, se

Modelling of infrared multiphoton absorption and dissociation for design of reactors for isotope separation by lasers

International Nuclear Information System (INIS)

Takeuchi, Kazuo; Nakane, Ryohei; Inoue, Cihiro

1981-01-01

A series of experiments were performed on infrared laser beam absorption (multiphoton absorption) and subsequent dissociation (multiphoton dissociation) of CF 3 Cl to propose models for the design of reactors for isotope separation by lasers. A parallel beam geometry was utilized in batch irradiation experiments to make direct compilation of lumped-parameter data possible. Multiphoton absorption is found to be expressed by a power-law extension of the law of Lambert and by an addition of a new term for buffer gas effect to the law of Beer. For reaction analysis, a method to evaluate the effect of incomplete mixing on apparent reaction rates is first presented. Secondly, multiphoton dissociation of Cf 3 Cl is found to occur in pseudo-first order fashion and the specific reaction rates for different beam fluence are shown to be correlated to the absorbed energy. (author)

Laser-assisted shape selective fragmentation of nanoparticles

Energy Technology Data Exchange (ETDEWEB)

Kazakevich, P.V. [Wave Research Center, General Physics Institute of the Russian Academy of Sciences, 38, Vavilov street, 117942 Moscow (Russian Federation); Simakin, A.V. [Wave Research Center, General Physics Institute of the Russian Academy of Sciences, 38, Vavilov street, 117942 Moscow (Russian Federation); Shafeev, G.A. [Wave Research Center, General Physics Institute of the Russian Academy of Sciences, 38, Vavilov street, 117942 Moscow (Russian Federation)]. E-mail: shafeev@kapella.gpi.ru; Viau, G. [ITODYS, UMR 7086, Universite Paris 7-Denis Diderot, case 7090, 2 place Jussieu, 75251 Paris Cedex 05 (France); Soumare, Y. [ITODYS, UMR 7086, Universite Paris 7-Denis Diderot, case 7090, 2 place Jussieu, 75251 Paris Cedex 05 (France); Bozon-Verduraz, F. [ITODYS, UMR 7086, Universite Paris 7-Denis Diderot, case 7090, 2 place Jussieu, 75251 Paris Cedex 05 (France)

2007-07-31

Experimental results are presented on laser-assisted fragmentation of gold-containing nanoparticles suspended in liquids (either ethanol or water). Two kinds of nanoparticles are considered: (i) elongated Au nanorods synthesized by laser ablation of a gold target immersed in liquid phase; (ii) gold-covered NiCo nanorods with high aspect ratio ({theta} {approx} 10) synthesized by wet chemistry processes. The shape selectivity induced by laser fragmentation of these nanorods is gained via tuning the wavelength of laser radiation into different parts of the spectrum of their plasmon resonance corresponding to different aspect ratios {theta}. Fragmentation is performed using three laser wavelengths, involving a Cu vapour laser (510 and 578 nm) and a Nd:YAG (1064 nm). Nanoparticles are characterized by UV-vis spectrometry, Transmission Electron Microscopy (TEM). The effect of laser pulse duration (nanosecond against picosecond range) is also studied in the case of fragmentation with an IR laser radiation.

Claims in vapour device (e-cigarette) regulation: A Narrative Policy Framework analysis.

Science.gov (United States)

O'Leary, Renée; Borland, Ron; Stockwell, Tim; MacDonald, Marjorie

2017-06-01

The electronic cigarette or e-cigarette (vapour device) is a consumer product undergoing rapid growth, and governments have been adopting regulations on the sale of the devices and their nicotine liquids. Competing claims about vapour devices have ignited a contentious debate in the public health community. What claims have been taken up in the state arena, and how have they possibly influenced regulatory outcomes? This study utilized Narrative Policy Framework to analyze the claims made about vapour devices in legislation recommendation reports from Queensland Australia, Canada, and the European Union, and the 2016 deeming rule legislation from the United States, and examined the claims and the regulatory outcomes in these jurisdictions. The vast majority of claims in the policy documents represented vapour devices as a threat: an unsafe product harming the health of vapour device users, a gateway product promoting youth tobacco uptake, and a quasi-tobacco product impeding tobacco control. The opportunity for vapour devices to promote cessation or reduce exposure to toxins was very rarely presented, and these positive claims were not discussed at all in two of the four documents studied. The dominant claims of vapour devices as a public health threat have supported regulations that have limited their potential as a harm reduction strategy. Future policy debates should evaluate the opportunities for vapour devices to decrease the health and social burdens of the tobacco epidemic. Copyright © 2017 Elsevier B.V. All rights reserved.

13CO2/12CO2 isotope ratio analysis in human breath using a 2 μm diode laser

Science.gov (United States)

Sun, Mingguo; Cao, Zhensong; Liu, Kun; Wang, Guishi; Tan, Tu; Gao, Xiaoming; Chen, Weidong; Yinbo, Huang; Ruizhong, Rao

2015-04-01

The bacterium H. pylori is believed to cause peptic ulcer. H. pylori infection in the human stomach can be diagnosed through a CO2 isotope ratio measure in exhaled breath. A laser spectrometer based on a distributed-feedback semiconductor diode laser at 2 μm is developed to measure the changes of 13CO2/12CO2 isotope ratio in exhaled breath sample with the CO2 concentration of ~4%. It is characterized by a simplified optical layout, in which a single detector and associated electronics are used to probe CO2 spectrum. A new type multi-passes cell with 12 cm long base length , 29 m optical path length in total and 280 cm3 volume is used in this work. The temperature and pressure are well controlled at 301.15 K and 6.66 kPa with fluctuation amplitude of 25 mK and 6.7 Pa, respectively. The best 13δ precision of 0.06o was achieved by using wavelet denoising and Kalman filter. The application of denoising and Kalman filter not only improved the signal to noise ratio, but also shorten the system response time.

Lasers in atomic, molecular and nuclear physics

International Nuclear Information System (INIS)

Letokhov, V.S.

1986-01-01

This book presents papers on laser applications in atomic, molecular and nuclear physics. Specifically discussed are: laser isotope separation; laser spectroscopy of chlorophyll; laser spectroscopy of molecules and cell membranes; laser detection of atom-molecule collisions and lasers in astrophysics

Retrieving mesospheric water vapour from observations of volume scattering radiances

Directory of Open Access Journals (Sweden)

P. Vergados

2009-02-01

Full Text Available This study examines the possibility for a theoretical approach in the estimation of water vapour mixing ratios in the vicinity of polar mesospheric clouds (PMC using satellite observations of Volume Scattering Radiances (VSR obtained at the wavelength of 553 nm. The PMC scattering properties perturb the underlying molecular Rayleigh scattered solar radiance of the background atmosphere. As a result, the presence of PMC leads to an enhancement in the observed VSR at the altitude of the layer; the PMC VSRs are superimposed on the exponentially decreasing with height Rayleigh VSR, of the PMC-free atmosphere. The ratio between the observed and the Rayleigh VSR of the background atmosphere is used to simulate the environment in which the cloud layer is formed. In addition, a microphysical model of ice particle formation is employed to predict the PMC VSRs. The initial water vapour profile is perturbed until the modelled VSRs match the observed, at which point the corresponding temperature and water vapour profiles can be considered as a first approximation of those describing the atmosphere at the time of the observations. The role of temperature and water vapour in the cloud formation is examined by a number of sensitivity tests suggesting that the water vapour plays a dominant role in the cloud formation in agreement with experimental results. The estimated water vapour profiles are compared with independent observations to examine the model capability in the context of this study. The results obtained are in a good agreement at the peak of the PMC layer although the radiance rapidly decreases with height below the peak. This simplified scenario indicates that the technique employed can give a first approximation estimate of the water vapour mixing ratio, giving rise to the VSR observed in the presence of PMC.

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

International Nuclear Information System (INIS)

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

2012-01-01

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

Fission product vapour - aerosol interactions in the containment: simulant fuel studies

International Nuclear Information System (INIS)

Beard, A.M.; Benson, C.G.; Bowsher, B.R.

1988-12-01

Experiments have been conducted in the Falcon facility to study the interaction of fission product vapours released from simulant fuel samples with control rod aerosols. The aerosols generated from both the control rod and fuel sample were chemically distinct and had different deposition characteristics. Extensive interaction was observed between the fission product vapours and the control rod aerosol. The two dominant mechanisms were condensation of the vapours onto the aerosol, and chemical reactions between the two components; sorption phenomena were believed to be only of secondary importance. The interaction of fission product vapours and reactor materials aerosols could have a major impact on the transport characteristics of the radioactive emission from a degrading core. (author)

Sensing response of copper phthalocyanine salt dispersed glass with organic vapours

Energy Technology Data Exchange (ETDEWEB)

Ridhi, R.; Sachdeva, Sheenam; Saini, G. S. S.; Tripathi, S. K., E-mail: surya@pu.ac.in [Department of Physics, Center of Advanced Study in Physics, Panjab University, Chandigarh-160 014 (INDIA) Fax: +91-172-2783336; Tel.:+91-172-2544362 (India)

2016-05-06

Copper Phthalocyanine and other Metal Phthalocyanines are very flexible and tuned easily to modify their structural, spectroscopic, optical and electrical properties by either functionalizing them with various substituent groups or by replacing or adding a ligand to the central metal atom in the phthalocyanine ring and accordingly can be made sensitive and selective to various organic species or gaseous vapours. In the present work, we have dispersed Copper Phthalocyanine Salt (CuPcS) in sol-gel glass form using chemical route sol-gel method and studied its sensing mechanism with organic vapours like methanol and benzene and found that current increases onto their exposure with vapours. A variation in the activation energies was also observed with exposure of vapours.

The Atomic Vapor Laser Isotope Separation Program

International Nuclear Information System (INIS)

1992-01-01

This report provides the finding and recommendations on the audit of the Atomic Vapor Laser Isotope Separation (AVLIS) program. The status of the program was assessed to determine whether the Department was achieving objectives stated in its January 1990 Plan for the Demonstration, Transition and Deployment of AVLIS Technology. Through Fiscal Year 1991, the Department had spent about $1.1 billion to develop AVLIS technology. The January 1990 plan provided for AVLIS to be far enough along by September to enable the Department to make a determination of the technical and economic feasibility of deployment. However, the milestones needed to support that determination were not met. An estimated $550 million would be needed to complete AVLIS engineering development and related testing prior to deployment. The earliest possible deployment date has slipped to beyond the year 2000. It is recommended that the Department reassess the requirement for AVLIS in light of program delays and changes that have taken place in the enrichment market since January 1990. Following the reassessment, a decision should be made to either fully support and promote the actions needed to complete AVLIS development or discontinue support for the program entirely. Management's position is that the Department will successfully complete the AVLIS technology demonstration and that the program should continue until it can be transferred to a Government corporation. Although the auditors recognize that AVLIS may be transferred, there are enough technical and financial uncertainties that a thorough assessment is warranted

Krypton isotope analysis using near-resonant stimulated Raman spectroscopy

International Nuclear Information System (INIS)

Whitehead, C.A.; Cannon, B.D.; Wacker, J.F.

1994-12-01

A method for measuring low relative abundances of 85 Kr in one liter or less samples of air has been under development here at Pacific Northwest Laboratory. The goal of the Krypton Isotope Laser Analysis (KILA) method is to measure ratios of 10 -10 or less of 85 Kr to more abundant stable krypton. Mass spectrometry and beta counting are the main competing technologies used in rare-gas trace analysis and are limited in application by such factors as sample size, counting times, and selectivity. The use of high-resolution lasers to probe hyperfine levels to determine isotopic abundance has received much attention recently. In this study, we report our progress on identifying and implementing techniques for trace 85 Kr analysis on small gas samples in a static cell as well as limitations on sensitivity and selectivity for the technique. High-resolution pulsed and cw lasers are employed in a laser-induced fluorescence technique that preserves the original sample. This technique, is based on resonant isotopic depletion spectroscopy (RIDS) in which one isotope is optically depleted while preserving the population of a less abundant isotope. The KILA method consists of three steps. In the first step, the 1s 5 metastable level of krypton is populated via radiative cascade following two-photon excitation of the 2p 6 energy level. Next, using RBDS, the stable krypton isotopes are optically depleted to the ground state through the 1s 4 level with the bulk of the 85 Kr population being preserved. Finally, the remaining metastable population is probed to determine 85 Kr concentration. The experimental requirements for each of these steps are outlined below

High resolution laser spectroscopy of radioactive isotopes using a RFQ cooler-buncher at CERN-ISOLDE

CERN Document Server

Mané, E

2009-01-01

At CERN, the European Organization for Nuclear Research, radioactive nuclear beams are produced at the On-Line Isotope Mass Separator facility, ISOLDE. This facility provides a variety of exotic nuclear species for multidisciplinary experiments including nuclear physics. A gas-filled linear Paul trap was commissioned off-line and on-line and now is fully integrated at the focal plane of the high resolution separator magnets of ISOLDE. Ion beams with reduced transverse emitance and energy spread are now available for all experiments located downstream the separator beam line. This device is also able to accumulate the ion beam and release the collected sample in short bunches. Typical accumulation times are 100 ms and the released bunch width is 5-20 $\\mu{s}$. Such bunching capabilities has substantially increased the sensitivity of collinear laser spectroscopy with fluorescence detection by reducing the background from laser scatter by up to four orders of magnitude. The spectroscopic quadrupole moments of $^...

Modelling the Spatial Isotope Variability of Precipitation in Syria

Energy Technology Data Exchange (ETDEWEB)

Kattan, Z.; Kattaa, B. [Department of Geology, Atomic Energy Commission of Syria (AECS), Damascus (Syrian Arab Republic)

2013-07-15

Attempts were made to model the spatial variability of environmental isotope ({sup 18}O, {sup 2}H and {sup 3}H) compositions of precipitation in syria. Rainfall samples periodically collected on a monthly basis from 16 different stations were used for processing and demonstrating the spatial distributions of these isotopes, together with those of deuterium excess (d) values. Mathematically, the modelling process was based on applying simple polynomial models that take into consideration the effects of major geographic factors (Lon.E., Lat.N., and altitude). The modelling results of spatial distribution of stable isotopes ({sup 18}O and {sup 2}H) were generally good, as shown from the high correlation coefficients (R{sup 2} = 0.7-0.8), calculated between the observed and predicted values. In the case of deuterium excess and tritium distributions, the results were most likely approximates (R{sup 2} = 0.5-0.6). Improving the simulation of spatial isotope variability probably requires the incorporation of other local meteorological factors, such as relative air humidity, precipitation amount and vapour pressure, which are supposed to play an important role in such an arid country. (author)

Vapour Pressure of Diethyl Phthalate

Czech Academy of Sciences Publication Activity Database

Roháč, V.; Růžička, K.; Růžička, V.; Zaitsau, D. H.; Kabo, G. J.; Diky, V.; Aim, Karel

2004-01-01

Roč. 36, č. 11 (2004), s. 929-937 ISSN 0021-9614 Institutional research plan: CEZ:AV0Z4072921 Keywords : vapour pressure * diethyl phthalate * correlation Subject RIV: CF - Physical ; Theoretical Chemistry Impact factor: 1.144, year: 2004

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

Energy Technology Data Exchange (ETDEWEB)

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

2017-11-15

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

Comparison of femtosecond and nanosecond laser ablation inductively coupled plasma mass spectrometry for uranium isotopic measurements

Energy Technology Data Exchange (ETDEWEB)

Havrilla, George Joseph [Los Alamos National Lab. (LANL), Los Alamos, NM (United States); McIntosh, Kathryn Gallagher [Los Alamos National Lab. (LANL), Los Alamos, NM (United States); Judge, Elizabeth [Los Alamos National Lab. (LANL), Los Alamos, NM (United States); Dirmyer, Matthew R. [Los Alamos National Lab. (LANL), Los Alamos, NM (United States); Campbell, Keri [Los Alamos National Lab. (LANL), Los Alamos, NM (United States); Gonzalez, Jhanis J. [Applied Spectra Inc., Fremont, CA (United States)

2016-10-20

Feasibility tests were conducted using femtosecond and nanosecond laser ablation inductively coupled plasma mass spectrometry for rapid uranium isotopic measurements. The samples used in this study consisted of a range of pg quantities of known 235/238 U solutions as dried spot residues of 300 pL drops on silicon substrates. The samples spanned the following enrichments of ²³⁵U: 0.5, 1.5, 2, 3, and 15.1%. In this direct comparison using these particular samples both pulse durations demonstrated near equivalent data can be produced on either system with respect to accuracy and precision. There is no question that either LA-ICP-MS method offers the potential for rapid, accurate and precise isotopic measurements of U10Mo materials whether DU, LEU or HEU. The LA-ICP-MS equipment used for this work is commercially available. The program is in the process of validating this work for large samples using center samples strips from Y-12 MP-1 LEU-Mo Casting #1.

Collinear Laser Spectroscopy of Manganese Isotopes using the Radio Frequency Quadrupole Cooler and Buncher at ISOLDE

CERN Document Server

AUTHOR|(CDS)2083426

The hyperfine structure of the odd-even $^{51−63}$Mn isotopes (N = 26 − 38) were measured using bunched beam collinear laser spectroscopy with the COLLAPS experimental setup at ISOLDE, CERN. The properties of these nuclei were investigated over the course of two experiments. During the first experiment, nuclear spins and magnetic dipole moments were extracted from spectroscopy on manganese atoms. These nuclear properties were then compared to the predictions of two large-scale shell model effective interactions (GXPF1A [1, 2] and LNPS [3]) which use different model spaces. In the case of $^{61,63}$Mn, these results show the increasing importance of neutron excitations across the proposed N = 40 subshell closure, and of proton excitations across the Z = 28 shell gap. These measurements provide the first direct proof that proton and neutron excitations across shell gaps are playing an important role in the ground state wave functions of the neutron-rich Mn isotopes. The electric quadrupole moment provides c...

Comparison of femtosecond and nanosecond laser ablation inductively coupled plasma mass spectrometry for uranium isotopic measurements

International Nuclear Information System (INIS)

Havrilla, George Joseph; McIntosh, Kathryn Gallagher; Judge, Elizabeth; Dirmyer, Matthew R.; Campbell, Keri; Gonzalez, Jhanis J.

2016-01-01

Feasibility tests were conducted using femtosecond and nanosecond laser ablation inductively coupled plasma mass spectrometry for rapid uranium isotopic measurements. The samples used in this study consisted of a range of pg quantities of known 235/238 U solutions as dried spot residues of 300 pL drops on silicon substrates. The samples spanned the following enrichments of 235 U: 0.5, 1.5, 2, 3, and 15.1%. In this direct comparison using these particular samples both pulse durations demonstrated near equivalent data can be produced on either system with respect to accuracy and precision. There is no question that either LA-ICP-MS method offers the potential for rapid, accurate and precise isotopic measurements of U10Mo materials whether DU, LEU or HEU. The LA-ICP-MS equipment used for this work is commercially available. The program is in the process of validating this work for large samples using center samples strips from Y-12 MP-1 LEU-Mo Casting #1.

Estimation of vapour pressure and partial pressure of subliming ...

Indian Academy of Sciences (India)

Administrator

conditions of (total) pressure by using thermogravimetry under those conditions. Further, from the partial pressure P, it is possible to determine the number of moles of material in the vapour phase using the ideal gas equation, PV = nRT, where P is the partial pressure, V the volume, n number of moles (of the vapour), R the ...

Discrete vapour cavity model with improved timing of opening and collapse of cavities

NARCIS (Netherlands)

Bergant, A.; Tijsseling, A.S.; Vítkovský, J.P.; Simpson, A.R.; Lambert, M.F.

2007-01-01

Transient vaporous cavitation occurs in hydraulic piping systems when the liquid pressure falls to the vapour pressure. Cavitation may occur as a localized vapour cavity (large void fraction) or as distributed vaporous cavitation (small void fraction). The discrete vapour cavity model (DVCM) with

Studies of the kinetics and mechanism of the oxidation of uranium by dry and moist air A model for determining the oxidation rate over a wide range of temperatures and water vapour pressures

Science.gov (United States)

McGillivray, G. W.; Geeson, D. A.; Greenwood, R. C.

1994-01-01

The rate of oxidation of uranium metal by moist air has been measured at temperatures from 115 to 350°C and water vapour pressures from 0 to 47 kPa (350 Torr). From this and from previously reported data, a model has been developed which allows the rate of uranium oxidation to be calculated at any particular combination of temperature and water vapour pressure of interest, in the range 0-350°C and 0-101.3 kPa (760 Torr). The model is based on the assumption that the surface concentration of water determines the rate of reaction and that the adsorption of water onto the oxide follows a Langmuir type isotherm. Theoretical plots of rate as a function of water vapour pressure and Arrhenius plots derived from the model have been shown to be in good agreement with experimental data. The model assumes separate contributions to the overall observed rate from oxygen and water vapour. Surface studies have been carried out using SIMS (secondary ion mass spectrometry). Depth profiling of the oxide produced by isotopically labelled reagents ( 18O 2 and H 218O), has shown that oxygen from both reactants is incorporated into the oxide layer in the ratio predicted by the kinetic model. This supports a mechanism in which oxygen and water vapour produce separate diffusing species (possibly O 2- and OH -).

Isotope shifts and hyperfine splittings in 144-154Sm I

International Nuclear Information System (INIS)

England, J.G.; Grant, I.S.; Newton, G.W.A.; Walker, P.M.

1990-01-01

The isotope shifts and hyperfine splittings have been measured in 144-154 Sm I using the crossed-beam laser fluorescence method. Transitions at 598.98 nm and 570.68 nm were investigated for all isotopes except 146 Sm and 153 Sm, in which measurements were only obtained at 570.68 nm. Laser-induced fluorescence has not previously been reported for 145 Sm. The magnetic dipole and electric quadrupole moments of the odd isotopes and the changes in mean square radii of the even ones are shown to be consistent with the information obtained from nuclear spectroscopy. (author)

Selective photoionization of gadolinium isotopes with a polarized laser

International Nuclear Information System (INIS)

Le Guyadec, E.

1990-06-01

The aim of this study is the use of gadolinium 157 as burnable poison in nuclear reactors. Spectroscopic isotopic displacements between Gd 156 and Gd 157 are low and the separation method studied is based on differentiated behavior, concerning polarized light, of even and odd gadolinium isotopes coming from their difference of nuclear spin. On this principle is based the simplest photoionization scheme. Selective ionization of odd isotopes is realized from the fundamental state with three resonating photons colinearly polarized. The experimental study confirms the possibility of efficient photoionization. The measured selectivity between Gd 157 and even isotope is over 48 in defined conditions because it can be destroyed by a magnetic field or if photons are not well polarized. Calculations and observations are in good agreement. Odd gadolinium isotope separation is feasible and effects preventing separation are evidenced [fr

Modelling water vapour permeability through atomic layer deposition coated photovoltaic barrier defects

Energy Technology Data Exchange (ETDEWEB)

Elrawemi, Mohamed, E-mail: Mohamed.elrawemi@hud.ac.uk [EPSRC Centre for Innovative Manufacturing in Advanced Metrology, School of Computing and Engineering, University of Huddersfield, Huddersfield (United Kingdom); Blunt, Liam; Fleming, Leigh [EPSRC Centre for Innovative Manufacturing in Advanced Metrology, School of Computing and Engineering, University of Huddersfield, Huddersfield (United Kingdom); Bird, David, E-mail: David.Bird@uk-cpi.com [Centre for Process Innovation Limited, Sedgefield, County Durham (United Kingdom); Robbins, David [Centre for Process Innovation Limited, Sedgefield, County Durham (United Kingdom); Sweeney, Francis [EPSRC Centre for Innovative Manufacturing in Advanced Metrology, School of Computing and Engineering, University of Huddersfield, Huddersfield (United Kingdom)

2014-11-03

Transparent barrier films such as Al{sub 2}O{sub 3} used for prevention of oxygen and/or water vapour permeation are the subject of increasing research interest when used for the encapsulation of flexible photovoltaic modules. However, the existence of micro-scale defects in the barrier surface topography has been shown to have the potential to facilitate water vapour ingress, thereby reducing cell efficiency and causing internal electrical shorts. Previous work has shown that small defects (≤ 3 μm lateral dimension) were less significant in determining water vapour ingress. In contrast, larger defects (≥ 3 μm lateral dimension) seem to be more detrimental to the barrier functionality. Experimental results based on surface topography segmentation analysis and a model presented in this paper will be used to test the hypothesis that the major contributing defects to water vapour transmission rate are small numbers of large defects. The model highlighted in this study has the potential to be used for gaining a better understanding of photovoltaic module efficiency and performance. - Highlights: • A model of water vapour permeation through barrier defects is presented. • The effect of the defects on the water vapour permeability is investigated. • Defect density correlates with water vapour permeability. • Large defects may dominate the permeation properties of the barrier film.

Vapour phase motion in cryogenic systems containing superheated and subcooled liquids

Science.gov (United States)

Kirichenko, Yu. A.; Chernyakov, P. S.; Seregin, V. E.

The development of vent pipelines, and venting storage tanks for cryogenic liquids requires the knowledge of the law of motion as well as regularities of vapour content variation in the liquid and heat dissipation by the vapour phase. This is a theoretical study of the effect of superheating (subcooling) of the liquid, relative acceleration and reduced pressure upon the size and velocity of noninteracting vapour bubbles, moving in the liquid, and upon their resistance and heat transfer coefficients.

Enriching stable isotopes: Alternative use for Urenco technology

International Nuclear Information System (INIS)

Rakhorst, H.; de Jong, P.G.T.; Dawson, P.D.

1996-01-01

The International Urenco Group utilizes a technologically advanced centrifuge process to enrich uranium in the fissionable isotope 235 U. The group operates plants in the United Kingdom, the Netherlands, and Germany and currently holds a 10% share of the multibillion dollar world enrichment market. In the early 1990s, Urenco embarked on a strategy of building on the company's uniquely advanced centrifuge process and laser isotope separation (LIS) experience to enrich nonradioactive isotopes colloquially known as stable isotopes. This paper summarizes the present status of Urenco's stable isotopes business

Shape-coexistence and shape-evolution studies for bismuth isotopes by insource laser spectroscopy and $\\beta$-delayed fission in $^{188}$Bi

CERN Multimedia

The proposal aims at the two main goals: \\\\ \\\\1) the studies of shape-coexistence and shape-evolution phenomena in the long chain of bismuth isotopes (Z=83) by in-source laser spectroscopy measurements of isotopic shifts (IS) and hyperfine structures (hfs), and \\\\ 2) $\\beta$-delayed fission ($\\beta$DF) of two isomeric states in $^{188}$Bi. \\\\ \\\\Isomer-selective $\\beta$DF studies for $^{188m1, 188m2}$Bi isomers will enable us for the first time to investigate the spin-dependence of the $\\beta$DF process and to check theoretical predictions of asymmetrical fission fragment mass-distribution in this region of nuclei. The measurements will be performed with the well-proven Windmill and MR-TOF MS/Penning Trap techniques.

Nuclear moments and deformation changes in the lightest Pt isotopes measured by laser spectroscopy

CERN Document Server

Roussière, B; Crawford, J; Duong, H T; Genevey, J; Girod, M; Huber, G; Ibrahim, F; Krieg, M; Le Blanc, F; Lee, J K P; Obert, J; Oms, J; Peru, S; Pinard, J; Putaux, J C; Sauvage, J; Sebastian, V; Zemlyanoi, S G; Forkel-Wirth, Doris; Lettry, Jacques

1999-01-01

Laser spectroscopy measurements are performed with the lightest neutron-deficient platinum isotopes using the experimental setup COMPLIS installed at the ISOLDE-Booster facility. The hyperfine spectra of /sup 182-178/Pt and /sup 183m/Pt are recorded for the first time from the optical transition 5d/sup 9/6s/sup 3/D/sub 3/ to 5d/sup 9/6p/sup 3/P/sub 2/. The variation in the mean-square charge radius of these nuclei and the magnetic and quadrupole (for I>or=1) moments of the odd isotope nuclei are found. A large deformation change between the /sup 183g/Pt and /sup 183m/Pt nuclei, quite large inverted odd-even staggering of the charge radius around the neutron midshell N=104, and a nuclear deformation drop in the region A=179 are revealed. All the results are discussed in terms of nuclear shape variation and are compared with the results of Hartree-Fock- Bogoliubov calculations involving the Gogny force. Comparison of the deformation measured from /sup 183g, m/Pt to the odd-odd isotone /sup 184g, m/Au shows that...

Drivers of radial growth and carbon isotope discrimination of bur oak (Quercus macrocarpa Michx.) across continental gradients in precipitation, vapour pressure deficit and irradiance.

Science.gov (United States)

Voelker, Steven L; Meinzer, Frederick C; Lachenbruch, Barbara; Brooks, J Renée; Guyette, Richard P

2014-03-01

Tree-ring characteristics are commonly used to reconstruct climate variables, but divergence from the assumption of a single biophysical control may reduce the accuracy of these reconstructions. Here, we present data from bur oaks (Quercus macrocarpa Michx.) sampled within and beyond the current species bioclimatic envelope to identify the primary environmental controls on ring-width indices (RWIs) and carbon stable isotope discrimination (Δ(13) C) in tree-ring cellulose. Variation in Δ(13) C and RWI was more strongly related to leaf-to-air vapour pressure deficit (VPD) at the centre and western edge of the range compared with the northern and wettest regions. Among regions, Δ(13) C of tree-ring cellulose was closely predicted by VPD and light responses of canopy-level Δ(13) C estimated using a model driven by eddy flux and meteorological measurements (R(2)  = 0.96, P = 0.003). RWI and Δ(13) C were positively correlated in the drier regions, while they were negatively correlated in the wettest region. The strength and direction of the correlations scaled with regional VPD or the ratio of precipitation to evapotranspiration. Therefore, the correlation strength between RWI and Δ(13) C may be used to infer past wetness or aridity from paleo wood by determining the degree to which carbon gain and growth have been more limited by moisture or light. © 2013 John Wiley & Sons Ltd.

Laser parameters of a Fe : ZnSe crystal in the 85-255-K temperature range

NARCIS (Netherlands)

Voronov, AA; Kozlovskii, [No Value; Korostelin, YV; Podmar'kov, YP; Frolov, MP

The temperature dependence of the efficiency of a laser based on a Fe:ZnSe crystal grown from the vapour phase by the free-growth method is studied in the 85-255-K temperature range. As the temperature was increased, the slope efficiency of the laser with respect to absorbed energy decreased from

uv dye lasers

International Nuclear Information System (INIS)

Abakumov, G.A.; Fadeev, V.V.; Khokhlov, R.V.; Simonov, A.P.

1975-01-01

The most important property of visible dye lasers, that is, continuous wavelength tuning, stimulated the search for dyes capable to lase in uv. They were found in 1968. Now the need for tunable uv lasers for applications in spectroscopy, photochemistry, isotope separation, remote air and sea probing, etc. is clearly seen. A review of some recent advances in uv dye lasers is reviewed

Soil Carbon: Compositional and Isotopic Analysis

Energy Technology Data Exchange (ETDEWEB)

Moran, James J.; Alexander, M. L.; Laskin, Alexander

2016-11-01

This is a short chapter to be included in the next edition of the Encyclopedia of Soil Science. The work here describes techniques being developed at PNNL for investigating organic carbon in soils. Techniques discussed include: laser ablation isotope ratio mass spectrometry, laser ablation aerosol mass spectrometry, and nanospray desorption electrospray ionization mass spectrometry.

An Analysis of Precipitation Isotope Distributions across Namibia Using Historical Data.

Directory of Open Access Journals (Sweden)

Kudzai Farai Kaseke

Full Text Available Global precipitation isoscapes based on the Global Network for Isotopes in Precipitation (GNIP network are an important toolset that aid our understanding of global hydrologic cycles. Although the GNIP database is instrumental in developing global isoscapes, data coverage in some regions of hydrological interest (e.g., drylands is low or non-existent thus the accuracy and relevance of global isoscapes to these regions is debatable. Capitalizing on existing literature isotope data, we generated rainfall isoscapes for Namibia (dryland using the cokriging method and compared it to a globally fitted isoscape (GFI downscaled to country level. Results showed weak correlation between observed and predicted isotope values in the GFI model (r2 < 0.20 while the cokriging isoscape showed stronger correlation (r2 = 0.67. The general trend of the local cokriging isoscape is consistent with synoptic weather systems (i.e., influences from Atlantic Ocean maritime vapour, Indian Ocean maritime vapour, Zaire Air Boundary, the Intertropical Convergence Zone and Tropical Temperate Troughs and topography affecting the region. However, because we used the unweighted approach in this method, due to data scarcity, the absolute values could be improved in future studies. A comparison of local meteoric water lines (LMWL constructed from the cokriging and GFI suggested that the GFI model still reflects the global average even when downscaled. The cokriging LMWL was however more consistent with expectations for an arid environment. The results indicate that although not ideal, for data deficient regions such as many drylands, the unweighted cokriging approach using historical local data can be an alternative approach to modelling rainfall isoscapes that are more relevant to the local conditions compared to using downscaled global isoscapes.

Nuclear Spectroscopy with Copper Isotopes of Extreme N/Z Ratios

CERN Multimedia

La commara, M; Roeckl, E; Van duppen, P L E; Schmidt, K A; Lettry, J

2002-01-01

The collaboration aims to obtain detailed nuclear spectroscopy information on isotopes close to the magic proton number Z=28 Very neutron-rich and neutron-deficient copper isotopes are ionized with the ISOLDE resonance ionization laser ion source (RILIS) to provide beams with low cross contamination.\\\\ \\\\On the neutron-deficient side the high $Q_\\beta$-values of $^{56}$Cu (15~MeV) and $^{57}$Cu (8.8~MeV) allow to study levels at high excitation energies in the doubly magic nucleus $^{56}$Ni and the neighbouring $^{57}$Ni. On the neutron-rich side the spectroscopy with separated copper isotopes allows presently the closest approach to the doubly magic $^{78}$Ni at an ISOL facility. Up to now no suitable target material with a rapid release was found for nickel itself. A slow release behaviour has to be assumed also for the chemically similar elements iron and cobalt.\\\\ \\\\Using a narrow-bandwidth dye laser and tuning of the laser frequency allows to scan the hyperfine splittings of the copper isotopes and isome...

Studies of isotopic effects in the excited electronic states of molecular systems

International Nuclear Information System (INIS)

1982-01-01

Rare gas halogen (RGH) lasers serve as convenient tools for a range of photophysical processes which exhibit isotope effects. This document summarizes progress in the production of molecular systems in their electronic excited states with the aid of RGH lasers, and the various isotopic effects one can study under these conditions. We conclude that the basic physical mechanisms involved in the isotopically sensitive characteristics of excited molecular electronic states are sufficiently selective to be useful in both the detection and separation of many atomic materials

Method for separating gaseous mixtures of isotopes

International Nuclear Information System (INIS)

Neimann, H.J.; Schuster, E.; Kersting, A.

1976-01-01

A gaseous mixture of isotopes is separated by laser excitation of the isotope mixture with a narrow band of wavelengths, molecularly exciting mainly the isotope to be separated and thereby promoting its reaction with its chemical partner which is excited in a separate chamber. The excited isotopes and the chemical partner are mixed, perhaps in a reaction chamber to which the two excited components are conducted by very short conduits. The improvement of this method is the physical separation of the isotope mixture and its partner during excitation. The reaction between HCl and the mixture of 238 UF 6 and 235 UF 6 is discussed

A static analytical apparatus for vapour pressures and (vapour + liquid) phase equilibrium measurements with an internal stirrer and view windows

International Nuclear Information System (INIS)

Guo, Hao; Gong, Maoqiong; Dong, Xueqiang; Wu, Jianfeng

2014-01-01

Highlights: • A new static analytical apparatus for vapour pressures and VLE data was designed. • The {R600a + R245fa} system was selected as a verification system. • Correlation of VLE data was made using PRvdWs and PRHVNRTL model. • Good agreement can be found with the literature data. - Abstract: A new static analytical apparatus for reliable vapour pressures and (vapour + liquid) equilibrium data of small-scale cell (≈150 mL) with internal stirrer and view windows was designed. In this work, the compositions of the phases were analyzed by a gas chromatograph connected on-line with TCD detectors. The operating pressure ranges from (0 to 3000) kPa, and the operating temperature range from (293 to 400) K. Phase equilibrium data for previously reported systems were first measured to test the credibility of the newly developed apparatus. The test included vapour pressure of 1,1,1,3,3-pentafluoropropane (R245fa) and isobutane (R600a), VLE of the (R600a + R245fa) system from T = (293.150 to 343.880) K. The measured VLE data are regressed with thermodynamic models using Peng–Robinson EoS with two different models, viz. the van der Waals mixing rule, and the Huron–Vidal mixing rule utilising the non-random two-liquid activity coefficient model. Thermodynamic consistency testing is also performed for the newly measured experimental data