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1
Bir, David J. "The development of a radio frequency plasma within a graphite furnace." Virtual Press, 1992. http://liblink.bsu.edu/uhtbin/catkey/834507.
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Graphite Furnace Atomic Absorption Spectroscopy (GFAA) and Inductively Coupled Plasma Atomic Emission Spectroscopy (ICP-AES) are two primary means of analyzing metals at the elemental level. Both techniques are widely accepted as tools for basic research. Each technique is performed differently and has its own distinct advantages as well as disadvantages. The choice of which technique to employ is determined by the needs of the analysis and the limitations of the instrumental technique.The idea to merge the two techniques was originallydeveloped by the research group of Dr. Michael W. Blades of the University of British Columbia, Vancouver, in 1989, who successfully demonstrated a "mini" plasma within a graphite furnace. The goal of the research was to design a device that would combine the advantages of both techniques and hopefully eliminate or minimize the unfavorable characteristics of each technique.The sustaining of a "mini" plasma has been demonstrated by this group. Although the end result was similar to that of Blades' group, the method of achieving the plasma was such that the "new" instrument could easily be mounted onto the furnace via a small Interface/Power Coupling device. The advantages of this system are: existing GFAA instruments can be used; modification of the furnace and RF supply is minimal; RF electronics can be remotely located; removal of the interface device is quickly achieved; and sample introduction, through the use of an autosampler, can be facilitated with small modification.Background spectra were acquired using helium, argon, and a mixture of argon/helium. It was found that all the plasmas have highly structured backgrounds and demonstrate the potential for many analysis regions. Two methods of sample introduction were used in acquiring the line emission of magnesium: injection through the sample inlet port to the furnace and end window injection. Inlet port injection suffers from a loss of sensitivity, when compared to end cap injection, but is more easily performed.Department of Chemistry
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Simpson, Emma. "Attosecond transient absorption spectroscopy in atomic species." Thesis, Imperial College London, 2016. http://hdl.handle.net/10044/1/44970.
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When high intensity laser light is focused into a gaseous target, high energy photons can be produced through the strongly nonlinear effect of high order harmonic generation. For a 30 fs, 800 nm or 1400 nm wavelength laser pulse, the result is a train of attosecond pulses produced at odd harmonic frequencies of the driving laser field, spanning energy ranges into the 100s eV. These attosecond pulses can access timescales characteristic to the movement of electrons in atoms, and by exploiting their properties as an ultrafast probe, electron dynamics in evolving atomic systems can be observed. This thesis presents the development of a pump-probe beamline capable of performing transient absorption spectroscopy experiments with resolution better than 150 as. Accompanying a full description of the experimental setup and methods, investigations are made into the attosecond transient absorption from strong field dressed helium and krypton atoms around their first ionisation edge, and 3d ionisation edge respectively. The result of the delay dependent transient absorption measurement is modulations to the recorded absorption amplitude for the harmonic orders around the respective ionisation thresholds. We investigated intensity regimes with an 800 nm laser field approaching the strong field ionisation threshold in helium. Experimental results are presented considering first the response of strong field dressed helium using an 800 nm laser field, and second the response of strong field dressed helium and krypton using a 1400 nm laser field. The use of the longer 1400 nm wavelength allows access to higher energy probe harmonics, enabling laser dressed krypton core to continuum, and core to Rydberg state transitions to be studied. By comparing the effect to the delay dependent absorption modulation as additional parameters are varied, information can be gained about the behaviour of the electrons. The parameters studied as a function of delay include: the dressing field intensity, target backing pressure and dressing field relative linear polarisation, aligned both parallel and perpendicular with respect to the probing harmonic pulse train. Key results include a strong suppression of the modulation amplitude for the above ionisation threshold harmonic orders when the dressing field linear polarisation is changed from parallel to perpendicular in the helium target. This is reproduced at both 800 nm and 1400 nm driving wavelengths.
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Conkey, Donald B. "On-Chip Atomic Spectroscopy." Diss., CLICK HERE for online access, 2007. http://contentdm.lib.byu.edu/ETD/image/etd1746.pdf.
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O'Grady, C. E. "Fundamental research into aerosols for analytical atomic absorption spectroscopy." Thesis, University of Aberdeen, 1987. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.377568.
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The material presented in this thesis falls into three main sections: 1) The measurement of nebulizer suction and its applications. Three methods of measurement of nebulizer suction were evaluated. The potential and limitations of each method was assessed. The most reliable and generally applicable method was measurement with a mercury manometer via a T-piece during aspiration, but after correction for suction drops along all the nebulizer capillaries and across connections. The measurement of suction was then applied to practical problems in AAS, i.e. the lack of dependence of signal on sample solution temperature, and to provide immediate warning of drift in aspiration rate. 2) Observations and causes of deposition in spray chambers. The deposition patterns of aerosol lost in the spray chamber was studied using a lithium tracer. Areas of high turbulence were identified and their positions related to the deposition patterns. The nebulizer/spray chamber system was considered to fulfill a sub-sampling role and the dual roles of pneumatic nebulizer as pumps and sub-samplers were critically discussed. 3) Observations on impactors in flame AAS. Five techniques for the evaluation of the effects of impact beads and other impactors were evaluated, i) aerosol droplet size distributions ii) aspiration of dye solutions iii) aerosol sizing with a second species introduced through the bead iv) effects on linear absorbance range v) effects on the extent of chemical interference The advantages and disadvantages of each technique were considered and the value of impactors critically appraised. An assessment was then made of the extent to which an impact cup or bead may be used to regulate sensitivity in flame AAS with a view to increasing the useful working ranges of calibration graphs.
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Hutton, Jonathan Craig Carleton University Dissertation Chemistry. "Some theoretical and experimental studies in atomic absorption spectrometry." Ottawa, 1992.
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French, Holly. "Trace metal analysis of street drugs by atomic absorption spectroscopy." Thesis, University of Kent, 2013. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.591083.
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The aim of the study was to ascertain the capabilities of the graphite furnace atomic absorption spectroscopy (OF AAS) system to discriminate between the two separate ecstasy batches according to the differing concentrations of trace metals. Previous studies have utilised rcp techniques such as rCP-AES and rCP-MS to determine trace metal concentrations in ecstasy tablets with particular interest in potential synthesis marker metals such as Pt, B and Hg. Five metals: Cu, Ba, Ni, Cr and Ph were quantified with good repeatability and reproducibility. The selection of elements comprises of metals that may be present due to additives, dyes, reducing agents, catalysts and elements recorded to be commonly present in ecstasy tablets, for example Ba. Elements Cu, Cr and Pb have been observed previously to be more homogenous within batches than elemental markers for synthesis routes suggesting these trace metals will be of use for indicating linkages between batches. Two separate batches of seized ecstasy tablets were analysed by GF AAS following digestion with nitric acid and hydrogen peroxide. Ecstasy tablets were acquired from the TICTAC unit at St George's Hospital London Tooting. HPLC analysis conducted at St. George's indicated that Batch 21573 of 20 tablets contained significant quantities of MDMA while Batch 26237 of 20 tablets contained predominantly caffeine. The small sample size has allowed for careful interpretation of intra-batch variation and inter-batch variation in the metal concentrations determined for each ecstasy batch. A previous study has used a similar sample size. The current study has successfully demonstrated the quantitation of five trace metals in ecstasy tablets for the first time via OF AAS. Large intra-batch variations were fOlU1d as expected for tablets produced in clandestine laboratories. Nickel in the MDMA containing batch 21573 was present in the range 0.47-13.1 ppm and in the caffeine containing batch 26237 in the range 0.35-9.06 ppm, very similar to previous reports of 1- 25 ppm and 0.3-16 ppm. The Cr levels detenmined in the current study (MDMA batch: 0.12-3.16 ppm, caffeine batch: 0.10-1.36 ppm) are lower than reported previously (0.7-34 ppm). The range ofPb concentrations (MDMA batch: 0.1 1-3.81 ppm, caffeine batch: 0.12- 4.91 ppm) are similar to previously reported (0.02-10 ppm). The copper levels in these samples were found to be particularly high (MDMA batch: 4-2379 ppm, caffeine batch: 17-1851 ppm) compared with previous studies using ICP techniques which fOlU1d ranges of 1-19 ppm and 0.8-38 ppm in ecstasy tablets. Barium concentrations were relatively similar within each batch with significantly higher concentrations found in the caffeine containing batch 26237 (rv1DMA batch: 0.19-0.66 ppm, caffeine batch: 3.77-5.47 ppm). Barium was the only element to offer discrimination between the two batches of tablets. AAS systems are well established, cheaper to install and run, and require less user skill as well as less sample volume. The addition that the current study offers in light of previous literature in the area is evidence of the capabilities of GF AAS to perform analyses on ecstasy tablets, with good detection limits, good precision and small sample volume, but with a technique that is well establish, fmancially less challenging and readily available in forensic laboratories in comparison to the more powerful ICP-MS technique
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De, Jager Lionel Louis. "Permanent modifiers for electrothermal atomization atomic absorption spectometry." Diss., Access to E-Thesis, 2000. http://upetd.up.ac.za/thesis/available/etd-11162006-161158/.
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Sims, Gary Robert. "Characterization of a charge injection device detector for atomic emission spectroscopy." Diss., The University of Arizona, 1989. http://hdl.handle.net/10150/184735.
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A Charge Injection Device (CID) detector has been evaluated as a detector for simultaneous multielement atomic emission spectroscopy. The CID was incorporated into a special liquid nitrogen cooled, computer controlled camera system. Electro-optical characterization of the CID and camera system included determination of readout noise, quantum efficiency, spatial crosstalk, temporal hysteresis, spatial response uniformity, and linear dynamic range. The CID was used as a spectroscopic detector for an echelle grating spectrometer equipped with a direct current plasma emission source. The spectrometer was a standard commercial instrument modified to provide a reduced image format more suitable for use with the CID detector. The optical characteristics of this spectrometer, including wavelength coverage, and optical aberrations are described. The spectroscopic system was evaluated with respect to detection limits, linear dynamic range, and accuracy in both single element and simultaneous multielement modes. Detection limits compared well to literature values reported for photomultiplier tube detector based systems under similar conditions. CID detection limits were superior in the near infrared and visible wavelength region, comparable in the middle UV, and higher in the far UV. The detection limits were determined to be limited by background radiation shot noise. Several elements of a certified standard reference material were simultaneously determined in order to assess the accuracy of the spectroscopic system. The results were highly accurate, even when operating near or below the 3σ limits of detection. Spectral interferences for elements were avoided by using several analytical lines for each element. The results of these investigations indicate that the CID is a superior multichannel detector for analytical atomic emission spectrometry. The capability to simultaneously monitor a wide, continuous spectral range with high spatial resolution, high dynamic range, low readout noise, and insignificant signal crosstalk is now possible. Many analytical benefits of this approach, such as the potential capability to perform rapid qualitative and semiquantitative analysis and the ability to select the optimum spectral lines for highly accurate quantitative analysis are now readily achievable.
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Thompson, Alexander W. J. "Multimode absorption spectroscopy of CO and CO₂ gas mixtures." Thesis, University of Oxford, 2013. http://ora.ox.ac.uk/objects/uuid:ebcb2031-1165-414e-88d8-69465bdaf291.
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The development of multimode absorption spectroscopy (MUMAS) for multi-species detec- tion and its potential for process control or environmental monitoring is reported. The simultaneous detection of CO and CO2 is demonstrated in a proof-of-principle experiment for applications in industrially relevant gas species monitoring. The technique of MUMAS is extended to the near infrared in order to detect these and other industrially relevant species. A laser was designed and constructed to emit a multimode spectrum in the region of 1.57um to take advantage of the spectral overlap of the second vibrational overtone of CO and the combination band 3ν1 + ν3 of CO2. The laser consisted of a semi-confocal cavity employing an Er:Yb glass chip as the gain medium. The laser was pumped by a 1W laser diode at 980nm and emitted up to 30mW in a bandwidth of 180GHz. The laser emitted between 6-10 modes depending upon the selective cavity length. Mode spacings varied between 18GHz to 33GHz with an individual mode linewidth of less than 8MHz. The laser modes were simultaneously scanned using a piezo-electric transducer (PZT) in order to modulate the cavity length at frequencies between 1Hz and 10Hz. A system for linearizing the MUMAS spectra with respect to frequency was devised based on a transmission spectra of a confocal Fabry-Perot etalon. Refinements to the MUMAS fitting code were developed to improve the computational efficiency. An initial demonstration of MUMAS on a known gas mixture of CO and CO2 was per- formed. The ratio of CO:CO2 concentrations in the gas mixture was measured with an accuracy of 0.4% which was within the supplier’s quoted uncertainty. MUMAS is then applied to the detection of CO and CO2 concentrations in exhaust gas produced by a 1.3 litre 4-cylinder turbo-charged spark ignition engine. Relative and absolute concentrations were derived from MUMAS signals and values compared to measurements using a 4-gas analyser. Concentrations of CO and CO2 were measured using MUMAS to a precision of 0.17% and 0.23% respectively compared to less than 0.1% for the 4-gas analyser. Ratios of CO and CO2 were determined with a precision of 0.28 using MUMAS compared to 0.11 with the 4-gas analyser. The detection limit of CO was found to be 1486ppm in these circumstances. Finally a discussion is presented of potential improvements arising from wavelength mod- ulation spectroscopy and cavity enhancement techniques.
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Lei, Tian. "Selenium speciation by high performance liquid chromatography -atomic absorption spectrometry." Thesis, McGill University, 1994. http://digitool.Library.McGill.CA:80/R/?func=dbin-jump-full&object_id=55507.
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Selenium has been shown to have multiple biochemical effects ranging from nutrient deficiency at low levels to toxicity at high levels. This duality of concern has led to a demand for increased numbers of highly accurate and precise determinations of selenium in biological materials. A convenient procedure was developed for determining selenoamino acids by HPLC-THG-AAS, based on the derivatization of these analytes with Sanger's reagent. Selenomethionine, selenocystine and selenocysteine (after blocking the free selenol group with phenylmercurio cation) were converted to their N-2,4-dinitrophenyl derivatives, and separated on a Nucleosil 5-NO$ sb2$ column with methanolic mobile phase containing acetic acid and triethylamine. Furthermore, an improved HPLC-AAS interface design was modified and optimized for the detection of selenium in HPLC column eluate. The new design was (i) compatible with aqueous mobile phases containing volatile buffers and (ii) provided equivalent molar response to analytes containing Se($-$II), Se(+IV) and Se(+VI). A method for simultaneously determination of selenate, selenite, selenocystine, selenomethionine and selenoethionine was developed by using the HPLC-AAS system with aqueous acetic acid containing ammonium acetate as eluate solution on the cyanopropyl column. The equivalent low ng limits of detection (1-2 ng as Se) for different oxidation states of selenium analytes were obtained using several different mobile phases and/or columns. A phenol extraction procedure for selenate, selenite, selenocystine, selenomethionine and selenoethionine was evaluated for the determination of these selenium analytes in natural waters and wheat samples. The current HPLC-AAS system provides an inexpensive alternative to conventional techniques for the determination of selenium analytes in environmental samples.
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Chan, Mau Hing. "Photothermal deflection spectroscopy of novel electronic materials." HKBU Institutional Repository, 1996. http://repository.hkbu.edu.hk/etd_ra/66.
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Williams, Robert Hamilton. "Trace metals analysis using continuum source simultaneous multielement graphite furnace atomic absorption spectroscopy." Diss., The University of Arizona, 2000. http://hdl.handle.net/10150/284168.
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A novel instrument for simultaneous multielement graphite furnace atomic absorption is described. This instrument employs a continuum light source and an echelle-charge injection device array detector system to achieve both simultaneous analysis of multiple wavelengths and true simultaneous background correction. The charge injection device detector also allows continuous wavelength coverage from 400-190 nm. Multichannel GFAAS analysis improves not only analytical speed but enables the use of elements resistant to matrix effects to assist in the identification of matrix effects in other elements and confirmation of calibration accuracy. The research project described discusses not only basic instrument design but also practical application of the new design to current analytical problems. Analysis of Ag, Pb, Tl, Cr, and Mn in drinking water, and red table wine allowed not only evaluation and investigation of instrumental problems but also allowed investigation of the various chemical problems associated with simultaneous multielement determinations in general. Multielement analysis involves the use of compromise furnace conditions, and matrix effects can further complicate multielement determinations. The use of chemical modifiers such as a mixed Pd(NO₃)₂ and Mg(NO₃)₂ modifier provide a partial solution to some of the problems associated with multielement determinations. For the two applications, the analytes were split into two groups. One group analyzed Ag, Pb, and Tl and the other analyzed Cr and Mn. The modifier system was applied to the Ag, Pb, and Tl analysis. For drinking water, analytical results were obtained with errors and RSD's less than 10%. The modifier system was not effective when water solutions contained high levels of Na and Ca. For red wines, the modifier system was effective for Ag, Pb and Tl. However, maximum pretreatment temperatures were approximately 100-200°C lower than that of high purity water. No detectable levels of Ag or Tl were found in any of the wine samples analyzed. Trace levels of approximately 20 ppb Pb and Cr were detected in several red wines. Levels of Mn approached 1 ppm. Matrix effects were found to suppress the Pb signal and enhance the Tl signal. Sample recoveries for both elements typically ranged from 80-120%.
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Liang, Dong Cuan. "Development and characterization of atmospheric pressure radio frequency capacitively coupled plasmas for analytical spectroscopy." Thesis, University of British Columbia, 1990. http://hdl.handle.net/2429/30590.
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An atmospheric pressure radio frequency capacitively coupled plasma (CCP) has been developed and characterized for applications in atomic emission spectrometry (AES), atomic absorption spectrometry (AAS) and gas chromatography (GC).
The CCP torch was initially designed as an atom reservoir for carrying out elemental analysis using atomic absorption. Functionally, the device consists of two parts, the CCP discharge tube and the tantalum strip electrothermal vaporization sample introduction system. The torch design provides for very effective energy transfer from the power supply to the plasma by capacitive coupling. Therefore, the plasma can be generated at atmospheric pressure with a flexible geometry. The plasma can be operated at very low rf input powers (30-600 W) enabling optimal conditions for atom resonance line absorption measurements. Absorption by the analyte takes place within the plasma discharge which is characterized by a long path length (20 cm) and low support gas flow rate (0.2 L/Min). Both of these characteristics ensure a relatively long residence time. The device exhibits linear calibration plots and provides sensitivities in the range of 3.5-40 pg. A preliminary measurement gave a Fe I excitation temperature of approximately 4000 K for the discharge. At this temperature, potential chemical interferences are likely to be minimal. Chemical interferences for Fe, Al, As, Ca, Co, Cd, Li, Mo and Sr were negligible in the determination of silver. Chloride interference, which is prevalent in GF-AAS, was not found. The amount of Ag found in a SMR#1643b (NIST) water sample was 9.5 ± 0.5 ng/g which fell in the certified range of 9.8 ± 0.8 ng/g. Spikes of 30 ng/g and 60 ng/g of silver were added to the SRM and recoveries were found to be in a range from 105 % to 96.2 %. The RSD obtained for 7 replicates of 270 pg silver was 4.6 %.
The results for the CCP AES are even more promising. The interferences of thirteen elements are negligible in the determination of silver. The chloride interference was not found. The detection limits for Ag, Cd, Li, Sb and B are 0.7, 0.7, 2, 80 and 400 pg respectively. The amount of silver found in a SRM#1643b (NIST) water sample was 9.3 ± 0.5 ng/g which also fell in the certified range of 9.8 ±0.8 ng/g. Spikes of 30 ng/g and 60 ng/g of silver were added into the SRM#1643b (NIST) samples; the recoveries were found to range from 97 % to 104 %. The RSD obtained for 7 analyses of 270 pg silver were 1.5 % for CCP-AES. It was also found that the signal to noise ratios (S/N) are higher in the AES mode than those in the AAS mode in the same CCP atomizer.
In order to exploit advantages inherent in both GF-AAS and I CP-AES, an atmospheric pressure capacitively coupled plasma sustained inside a graphite furnace was developed. This source combines the high efficiency of atomization in furnaces and the high efficiency of the excitation in atmospheric pressure plasmas. In general, plasma sources are able to effectively excite high-lying excited states for most metals and non-metals and can also ionize vaporized elements. Therefore the possibility exists of using non-resonance lines to avoid the effects of self-absorption at high analyte concentrations. Ion lines may also be used in cases where they provide better sensitivity or freedom from spectral interferences. This source also offers the ability to independently optimize vaporization and excitation. However, the most important aspect of this new source is that it can be used for simultaneous, multielement determinations of small sized samples in a graphite furnace atomizer, a design which has been proven to be effective over many years of use. Preliminary quantitative characteristics of this new atmospheric pressure plasma emission source have been studied. The detection limit for Ag of 0.3 pg is lower than the value of 0.4 pg reported for GF-AAS.
Variants of the CCP, including a gas chromatography (GC) detector, combinations of laser ablation - CCP, rf sputtering - CCP direct solid analysis, and its application as an intense spectral lamp have been developed and are reported in this dissertation.Science, Faculty of
Chemistry, Department of
Graduate
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Erdem, Arzu Eroğlu Ahmet E. "Use Of Different Gold Amalgamation Techniques In Mercury Determination By Cold Vapor Atomic Absorption Spectrometry/." [s.l.]: [s.n.], 2005. http://library.iyte.edu.tr/tezler/master/kimya/T000354.pdf.
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Thesis (Master)--İzmir Institute of Technology, İzmir, 2005.Keywords: Mercury, atomic absorption spectrometry, gold, amalgamation, cold vapor. Includes bibliographical references (leaves 48-51).
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Yersel, Müşerref Eroğlu Ahmet E. thesis advisor. "Separation of trace antimony and arsenic prior to hydride generation atomic absortion spectrometric determination/." [s.l.]: [s.n.], 2005. http://library.iyte.edu.tr/tezler/master/kimya/T000392.pdf.
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Zayas-Cruz, Jorge I. "Studies on the atomization mechanism of selenium in graphite furnace atomic absorption spectrometry /." The Ohio State University, 1987. http://rave.ohiolink.edu/etdc/view?acc_num=osu148758688918748.
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Tasana, Nomalanga Gloria. "Optimisation and evaluation of boron analysis for pressurized Water reactor plants." Thesis, Cape Peninsula University of Technology, 2016. http://hdl.handle.net/20.500.11838/2328.
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Thesis (MTech (Chemistry))--Cape Peninsula University of Technology, 2016.Boron concentration analysis is an important and critical analysis performed by the Analytical Chemistry Laboratory at Koeberg Nuclear Power Station (KNPS), because boron controls reactivity and the concentration determination is a Technical Specification Parameter (safety parameter). Hence accurate, precise results for boron concentration produced by laboratories and on-line analysers are important because of their operational implications associated with reactivity control and also for nuclear safety. The project focused on comparing the quality of chemical analysis results of boron produced by analysis techniques/ methods used at Koeberg Nuclear Power Station namely; Potentiometric Titration, Atomic Absorption Spectrophotometry (Flame) and UV-VIS Azomethine-H method. The methods were described, optimised, evaluated and compared in terms of uncertainty of measurement, accuracy, precision, analysis range, limitations, appropriateness and applicability for boron analysis in 2500 mg B/kg concentration range. For Potentiometric Titration method, the measurement uncertainty = 2500 ±16 mg B/kg, accuracy= 0.2%, precision= 0.08% the range of analysis= 5-800 mg B/kg. For Atomic Absorption Spectrophotometry (Flame) the measurement uncertainty= 2500 ±51 mg B/kg, accuracy= 0.12%, precision= 0.44% the range of analysis= 0 -500 mg B/kg. For UV-VIS Azomethine-H the measurement uncertainty= 2500 ±72 mg B/kg, accuracy= 0.08%, precision= 0.44% the range of analysis= 0 -10 mg B/kg. The INPOs 95% accuracy and precision criteria for boron is ± 1%. So these techniques could be used for boron analysis in PWR. Based on the evaluation and assessments mentioned above; the Potentiometric Titration was found to be the most preferred method for boron analysis for Pressurised Water Reactors followed by Atomic Absorption Spectrophotometry (Flame) that can be of good use in determining boron especially in waste samples and samples with complex matrices. The UV-VIS Azomethine-H methods can only be used when it is really necessary to determine very low levels of boron between 0- 10mg B/kg of which it was never required before. Since it is specifically the B-10 isotope that is responsible for the ability to control reactivity, the implementation of isotopic boron analysis (by Inductively Coupled Plasma – Mass Spectrometry) at KNPS is explained and the advantage of the programme is illustrated. Although the current state of instrumental capabilities is adequate for 10B isotope determination, further work of optimising the methodology for even better results is recommended.
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Haider, Nazre. "The collisional behaviour of atomic carbon and germanium investigated by time-resolved resonance absorption spectroscopy." Thesis, University of Cambridge, 1995. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.308254.
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Marshall, P. "Kinetic studies of sodium atoms at elevated temperatures by time-resolved atomic resonance absorption spectroscopy." Thesis, University of Cambridge, 1985. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.355262.
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Sombers, Leslie A. "Determination of Trace Levels of Lead in Whole Blood by Graphite Furnace Atomic Absorption Spectroscopy." W&M ScholarWorks, 1998. https://scholarworks.wm.edu/etd/1539626166.
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Northern, Jonathen Henry. "Multi-species detection using Infrared Multi-mode Absorption Spectroscopy." Thesis, University of Oxford, 2013. http://ora.ox.ac.uk/objects/uuid:10f3bd62-4c81-4eaf-854d-1f388af73be9.
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This thesis reports work extending the scope of a recently developed gas sensing technique, multi-mode absorption spectroscopy (MUMAS). The ability of MUMAS to simultaneously detect multiple species from a mixture is demonstrated for the first time. The technique is subsequently extended to mid-infrared wavelengths, realising large gains in sensitivity. A solid-state, multi-mode laser has been developed to provide a high-performance comb source for use with MUMAS. This in-house constructed, diode-pumped, Er/Yb:glass laser operates on 10 longitudinal modes, separated by 18 GHz and centred close to 1565 nm. The extensive development and prototyping work leading to this final laser design is described. Multi-species detection with MUMAS is reported for the first time, thus demonstrating the ability of this technique to perform multi-gas sensing using a single laser and simple detection scheme. The previously described Er/Yb multi-mode laser was used to record MUMAS signals from a sample containing CO, C2H2, and N2O. The components of the mixture were detected simultaneously by identifying multiple transitions in each of the species. Temperature- and pressure-dependent modelled spectral fits to the data were used to determine the partial pressures of each species in the mixture with an uncertainty better than +/-2%. Multi-mode radiation has been successfully generated at 3.3 μm using quasi phase matched difference frequency generation (QPM-DFG). A mid-infrared laser comb was produced by optically mixing the near-infrared, multi-mode comb produced by the previously developed Er/Yb:glass laser with the single-mode output of a Nd:YAG laser operating at 1064 nm. This multi-frequency laser source was characterised to verify performance, and subsequently used to perform proof-of-principle MUMAS measurements on the strong transitions found in this spectral region. Spectra were recorded of NH3 and CH4 both individually and as components of a mixture. A minimum detection level for this system was determined to be 4.3 μbar m-1 for CH4, a sensitivity increase of 300 over similar measurements performed in the near-IR.
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Sealy, I. P. "A kinetic study of lead atoms at elevated temperatures by time-resolved atomic resonance absorption spectroscopy." Thesis, University of Cambridge, 1986. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.383938.
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Marchand, Bruno Carleton University Dissertation Chemistry. "Studies on matrix interferences and mechanisms of atomization of chromium in graphite furnace atomic absorption spectroscopy." Ottawa, 1987.
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Wu, Shun. "Direct fiber laser frequency comb stabilization via single tooth saturated absorption spectroscopy in hollow-core fiber." Diss., Kansas State University, 2014. http://hdl.handle.net/2097/18373.
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Doctor of PhilosophyDepartment of Physics
Kristan L. Corwin
Portable frequency references are crucial for many practical on-site applications, for example, the Global Position System (GPS) navigation, optical communications, and remote sensing. Fiber laser optical frequency combs are a strong candidate for portable reference systems. However, the conventional way of locking the comb repetition rate, frep, to an RF reference leads to large multiplied RF instabilities in the optical frequency domain. By stabilizing a comb directly to an optical reference, the comb stability can potentially be enhanced by four orders of magnitude. The main goal of this thesis is to develop techniques for directly referencing optical frequency combs to optical references toward an all-fiber geometry. A big challenge for direct fiber comb spectroscopy is the low comb power. With an 89 MHz fiber ring laser, we are able to optically amplify a single comb tooth from nW to mW (by a factor of 10^6) by building multiple filtering and amplification stages, while preserving the comb signal-to-noise ratio. This amplified comb tooth is directly stabilized to an optical transition of acetylene at ~ 1539.4 nm via a saturated absorption technique, while the carrier-envelope offset frequency, f0, is locked to an RF reference. The comb stability is studied by comparing to a single wavelength (or CW) reference at 1532.8 nm. Our result shows a short term instability of 6 x10^(-12) at 100 ms gate time, which is over an order of magnitude better than that of a GPS-disciplined Rb clock. This implies that our optically-referenced comb is a suitable candidate for a high precision portable reference. In addition, the direct comb spectroscopy technique we have developed opens many new possibilities in precision spectroscopy for low power, low repetition rate fiber lasers. For single tooth isolation, a novel cross-VIPA (cross-virtually imaged phase array) spectrometer is proposed, with a high spectral resolution of 730 MHz based on our simulations. In addition, the noise dynamics for a free space Cr:forsterite-laser-based frequency comb are explored, to explain the significant f0 linewidth narrowing with knife insertion into the intracavity beam. A theoretical model is used to interpret this f0 narrowing phenomenon, but some unanswered questions still remain.
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曾令建 and Ling-kin Simon Tsang. "Graphite furnace capacitively coupled plasma atomic emission spectrometry in the determination of trace metals in biological andenvironmental samples." Thesis, The University of Hong Kong (Pokfulam, Hong Kong), 1998. http://hub.hku.hk/bib/B31220009.
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Tsang, Ling-kin Simon. "Graphite furnace capacitively coupled plasma atomic emission spectrometry in the determination of trace metals in biological and environmental samples /." Hong Kong : University of Hong Kong, 1998. http://sunzi.lib.hku.hk/hkuto/record.jsp?B19737403.
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Basu, Subhash Chandra. "Reactions of Si and Ge atoms with unsaturated organic molecules by time-resolved atomic resonance absorption spectroscopy." Thesis, University of Cambridge, 1989. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.293497.
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André, Johansson. "A photodegradation study of conjugated polymers for organic solar cells by absorption spectroscopy and atomic force microscopy." Thesis, Karlstads universitet, Institutionen för ingenjörsvetenskap och fysik (from 2013), 2021. http://urn.kb.se/resolve?urn=urn:nbn:se:kau:diva-84049.
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The effect of light exposure in ambient air on thin films made from an electron acceptor polymer poly{[N,N'-bis(2-octyldodecyl)naphthalene-1,4,5,8-bis(dicarboximide)-2,6-diyl]-alt-5,5'-(2,2'-bithiophene)} (N2200), an electron donor polymer Poly[[2,3-bis(3-octyloxyphenyl)-5,8-quinoxalinediyl]-2,5-thiophenediyl] (TQ1) and their blends, has been studied using UV-vis spectroscopy and Atomic Force Microscopy (AFM). For solutions of TQ1, N2200 and blends, the linearity of the Beer-Lambert law for absorption spectroscopy has been verified. The measured UV-vis spectra show that TQ1 thin films are more sensitive to degradation by simulated sunlight than N2200 films. They also show that among the polymer blends, the N2200-rich blend with volume ratio 1:2 (TQ1:N2200) was less sensitive to degradation by simulated sunlight than blends of ratio 1:1 and 2:1. The AFM images showed a change in roughness between the undegraded and degraded films, where the TQ1, 1:1 and 1:2 films obtained lower roughness after 45 hours of degradation, and the N2200 and the 2:1 films obtained higher roughness.Effekten av simulerad solljusexponering i omgivande luft på tunna filmer gjorda av en elektronaccepterande polymer poly{[N,N'-bis(2-octyldodecyl)naphthalene-1,4,5,8-bis(dicarboximide)-2,6-diyl]-alt-5,5'-(2,2'-bithiophene)} (N2200), en elektrondonerande polymer Poly[[2,3-bis(3-octyloxyphenyl)-5,8-quinoxalinediyl]-2,5-thiophenediyl] (TQ1) och deras blandningar, har undersökts genom ultraviolett-synlig-spektroskopi (UV-vis-spektroskopi) och atomkraftsmikroskopi (AFM). Genom lösningar av TQ1, N2200 och blandningar, har det linjära förhållandet i Beer Lamberts lag för absorptionsspektroskopi verifierats. De mätta UV-vis-spektrumen visar att tunna TQ1-filmer är känsligare mot degradering genom simulerat solljus än tunna N2200-filmer. De visar också att den N2200-rika blandningen med ett volymförhållande av 1:2 (TQ1:N2200) var mindre känslig för degradering av simulerat solljus än blandningar med volymförhållandet 1:1 och 2:1. AFM-bilderna visade en förändring i råhet mellan degraderade och icke-degraderade filmer, där TQ1-, 1:1-, och 1:2-filmerna fick en lägre ytråhet efter 45 timmar av degradering, och N2200- och 2:1-filmera fick en högre ytråhet.
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Chen, Xi 1970. "Quasi-stable slurries for the determination of trace elements by graphite furnace atomic absorption spectrometry." Thesis, McGill University, 2000. http://digitool.Library.McGill.CA:80/R/?func=dbin-jump-full&object_id=33386.
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High-pressure homogenization using a new flat valve homogenizer in combination with enzymatic digestion with a crude protease was investigated as a means of releasing Se compounds from zoological and botanical matrices prior to slurry introduction GF-AAS. Timed trials with four zoological certified reference materials (CRMs), three botanical reference materials (RMs), and a food crop indicated that Se release was quantitative after homogenization or became quantitative within 1 h of digestion at 60°C.The same technique was employed on five animal feed samples.
A new model of homogenizer equipped with ceramic homogenizing valve was evaluated in terms of analyte metal contamination levels within the final sample dispersion.
Five animal feed samples and four wood pulp samples, were investigated for their content of Cu, Fe and Mn using high-pressure homogenization as the sample preparation technique prior to GF-AAS. Dispersions of dried animal feeds were sub-sampled reliably after 7 days of storage at 4°C. Trials on pulp samples indicated that pulps could be sub-sampled reliably after 1 day of storage. (Abstract shortened by UMI.)
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Liao, Chen-Ting, and Arvinder Sandhu. "XUV Transient Absorption Spectroscopy: Probing Laser-Perturbed Dipole Polarization in Single Atom, Macroscopic, and Molecular Regimes." MDPI AG, 2017. http://hdl.handle.net/10150/624358.
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We employ an extreme ultraviolet (XUV) pulse to impulsively excite dipole polarization in atoms or molecules, which corresponds to coherently prepared superposition of excited states. A delayed near infrared (NIR) pulse then perturbs the fast evolving polarization, and the resultant absorbance change is monitored in dilute helium, dense helium, and sulfur hexafluoride (SF6) molecules. We observe and quantify the time-dependence of various transient phenomena in helium atoms, including laser-induced phase (LIP), time-varying (AC) Stark shift, quantum path interference, and laser-induced continuum structure. In the case of dense helium targets, we discuss nonlinear macroscopic propagation effects pertaining to LIP and resonant pulse propagation, which account for the appearance of new spectral features in transient lineshapes. We then use tunable NIR photons to demonstrate the wavelength dependence of the transient laser induced effects. In the case of molecular polarization experiment in SF6, we show suppression of XUV photoabsorption corresponding to inter-valence transitions in the presence of a strong NIR field. In each case, the temporal evolution of transient absorption spectra allows us to observe and understand the transient laser induced modifications of the electronic structure of atoms and molecules.
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Franklin, Dean E. "A novel approach to determine arsenic contamination in the environment /." Online version of thesis, 2007. http://hdl.handle.net/1850/5341.
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Stollar, Sarah. "A chemical investigation of the 18 day creation of lead oil /." Norton, MA : Wheaton College, 2008. http://hdl.handle.net/10090/5528.
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PACHECO, LUCIANA FERNANDES. "CO-SITE DIGITAL MICROSCOPY AND ATOMIC ABSORPTION SPECTROSCOPY IN THE ANALYSIS OF THE CHELATING EFFECT ON HUMAN DENTINE." PONTIFÍCIA UNIVERSIDADE CATÓLICA DO RIO DE JANEIRO, 2008. http://www.maxwell.vrac.puc-rio.br/Busca_etds.php?strSecao=resultado&nrSeq=12984@1.
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PONTIFÍCIA UNIVERSIDADE CATÓLICA DO RIO DE JANEIROA partir dos anos 70 constatou-se a formação de uma massa aderida às paredes do canal radicular, após a instrumentação, que foi denominada smear layer. Esta camada é composta de material orgânico e inorgânico, tecido pulpar e bactérias, e contribui para obliterar os túbulos dentinários. A remoção desta camada melhora a adaptação entre o material obturador e as paredes dentinárias, elimina bactérias, limpa e alarga os túbulos. Essa remoção é realizada por soluções quelantes, mas a substância e o tempo ideais permanecem desconhecidos. Os quelantes atuam removendo Cálcio da microestrutura dentinária. No presente estudo, foi analisado o poder quelante de MTAD, HEBP e EDTA sobre a dentina coronária, avaliando a fração de área tubular aberta (AreaP) e a massa de Cálcio quelado (MNC (Ca)). Três hipóteses foram propostas e testadas: Não existe diferença entre os quelantes quanto a AreaP (H1) e quanto a MNC(Ca) (H2); existe correlação entre AreaP e MNC(Ca) (H3). Através de Microscopia Óptica Co-localizada (MCL) foram capturadas imagens de vários campos de cada amostra, em diferentes tempos de ataque ácido. Uma seqüência de processamento e análise de imagens foi utilizada para medir AreaP versus tempo, para cada quelante. Esta análise foi complementada qualitativamente com Microscopia Eletrônica de Varredura (MEV). As medidas de MNC(Ca) foram realizadas por Espectroscopia de Absorção Atômica (AA) sobre as soluções quelantes utilizadas no experimento de MCL. H1 foi negada, com MTAD sendo o mais potente e HEBP o menos potente dos quelantes. Os resultados de MEV corroboram os resultados de MCL. Os resultados de AA apresentaram grande dispersão, mas indicam que H2 é falsa. H3 foi rejeitada.
In the 70's it was discovered that after instrumentation of the root canal there was the formation of a smear layer, attached to the walls of the canal. This layer is composed of organic and inorganic material, pulp tissue and bacteria, and contributes to the obliteration of the dentine tubules. The removal of this layer improves the adaptation of the filling material to the dentine walls, eliminates bacteria, cleans and enlarges the tubules. Smear layer removal is achieved through the use of chelators but the ideal substance and application time remain unknown. Chelators act through the removal of Calcium from the dentine microstructure. In the present study, the chelating power of MTAD, HEBP and EDTA on coronal dentine was analyzed through the measurement of the area fraction of open tubules (AreaP) and of the chelated Calcium mass (MNC(Ca)). Three hypotheses were proposed and tested: There is no difference between chelators regarding AreaP (H1) and regarding MNC(Ca) (H2); there is correlation between AreaP and MNC(Ca) (H3). Images of several fields of each sample, for different chelation times, were acquired through Co-Site Optical Microscopy (CSOM). An image processing and analysis sequence was employed to measure AreaP versus time, for each chelator. This analysis was qualitatively complemented by Scanning Electron Microscopy (SEM). Measurements of MNC(Ca) were obtained by Atomic Absorption Spectroscopy (AA) from the chelator solutions used during the CSOM experiments. H1 was denied, with MTAD found to be the most powerful chelator while HEBP was the weakest. SEM results corroborate these findings. AA results showed wide dispersion but indicate that H2 is false. H3 was rejected.
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Deeyamulla, Mahendra Priyantha. "Kinetic studies of ground state carbon atoms by time-resolved atomic resonance absorption spectroscopy in the vacuum ultraviolet." Thesis, University of Cambridge, 2005. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.614983.
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Barrett, N. T. "Glancing angle X-ray absorption spectroscopy to investigate changes in the local atomic structure around uranium in leached glasses." Thesis, University of Strathclyde, 1987. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.382385.
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Knabe, Kevin. "Using saturated absorption spectroscopy on acetylene-filled hollow-core fibers for absolute frequency measurements." Diss., Manhattan, Kan. : Kansas State University, 2010. http://hdl.handle.net/2097/4126.
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Kuznetsova, Yelena Anatolyevna. "Atomic and nuclear interference phenomena and their applications." Texas A&M University, 2005. http://hdl.handle.net/1969.1/2428.
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In this work, interference and coherence phenomena, appearing in atomic and
molecular ensembles interacting with coherent light sources, as electromagnetically
induced transparency (EIT), coherent population trapping (CPT), and slow group
velocity of light are investigated. The goal of the project is to make the steps towards
various applications of these phenomena, first, by studying them in solid media (which
are the most advantageous for applications), second, by suggesting some novel applications
such as CPT-based plasma diagnostics, and realization of new types of
solid-state lasers (based on suppression of excited-state absorption via EIT). The
third goal of the project is extension of coherence and interference effects well-known
in optics to the gamma-ray range of frequencies and, correspondingly, from atomic to
nuclear transitions. A particular technique of chirped pulse compression applied to
M??ossbauer transitions is considered and the possibility of compression of M??ossbauer
radiation into ultrashort gamma-ray pulses is analyzed.
The theoretical treatment of the interference and coherence effects is based on
the semiclassical description of atom-light interaction, which is sufficient for correct
analysis of the phenomena considered here. Coherent media are considered in two-,
three-, and four-level approximations while their interaction with light is studied both
analytically and numerically using the Maxwell-Bloch set of equations.
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Siaka, I. Made, of Western Sydney Nepean University, and Faculty of Science and Technology. "The application of atomic absorption spectroscopy to the determination of selected trace elements in sediments of the Coxs River Catchment." THESIS_FST_XXX_Siaka_I.xml, 1998. http://handle.uws.edu.au:8081/1959.7/238.
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An investigation of heavy metal concentrations in sediments from Coxs River catchment, a tributary of the Hawkesbury-Nepean River system, has been undertaken. A number of digestion methods were assessed for the determination of Pb, Cu, Cd, Zn, Ni, Mn, Fe, Co and Cr in reference materials by flame AAS. The method that produced the best recovery is reverse aqua regia, HNO3-HC1 with ultrasonification followed by heating on a hotplate. Based on analysis of sediments from 133 sites, background concentrations were established. Elevated heavy metal concentrations were recorded in some samples. The three most polluted areas were investigated for heavy metal associations and distributions. Metal bioavailability was assessed from sediment samples by using selective extraction techniques. The association of heavy metals with different solid phases was assessed by a sequential extraction technique involving a series of extraction reagents. Pd, Cu, Fe and Cr were mainly associated with Fe/Mn oxides and organic matter plus sulphide phases. While Cd, Zn, Ni and Co which behave similarly were extracted from each step, the largest percentages of these metals were found in Fe/Mn oxides and organic matter phases. Mn was different to other metals, in that it predominantly associated with the ion exchangeable form.Master of Science (Hons)
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Siaka, I. Made. "The application of atomic absorption spectroscopy to the determination of selected trace elements in sediments of the Coxs River Catchment /." View thesis, 1998. http://library.uws.edu.au/adt-NUWS/public/adt-NUWS20030829.150226/index.html.
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余東民 and Tung-man Yu. "Graphite furnace: capacitively coupled plasma- atomic spectrometry and inductively coupled plasma - massspectrometry for the determination of silica and trace metals in water." Thesis, The University of Hong Kong (Pokfulam, Hong Kong), 2002. http://hub.hku.hk/bib/B29911643.
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Geng, J. "Kinetic studies of alkaline-earth atoms in specific electronic states by resonance absorption spectroscopy and laser-induced atomic and molecular emission." Thesis, University of Cambridge, 1998. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.599351.
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Investigations of the kinetics and dynamics of elementary gas-phase collisional processes and reactions have proved to be of major significance in many areas of both pure and applied physics and chemistry. A thorough understanding, both experimental and theoretical, of the collisional processes of defined quantum states of atoms and molecules is required. This includes physical processes such as energy transfer, collisional quenching, diffusion, charge transfer and ionisation, and chemical processes such as reaction rates, mechanism branching ratios and reaction potential energy surfaces. These topics have long been important in a variety of systems, including atmospheric chemistry, gaseous plasmas, combustion science and developing novel chemical laser systems. The primary motivation for the present work is to extend our knowledge about the collisional behaviour and reaction kinetics of alkaline-earth atoms in specific electronic states. The first part of this thesis (chapters 1-5) is directed towards a kinetic investigation of ground state atoms, in particular, Ca[4s2(1S0)], generated by flash photolysis of gaseous iodide molecules and whose decay is monitored by time-resolved atomic resonance absorption spectroscopy in the 'single-shot mode'. A new body of data for the absolute rate constants for the F, Cl, Br and I-atom abstraction reactions of Ca[4s2(1S0)] with a range of halide molecules are reported. The diffusional behaviour of this atom in noble gases, He, Kr and Xe and also N2, is also investigated in this work and the diffusion coefficients are consequently presented here. It is envisaged in broader terms that these studies have not only provided some new kinetic data for use in related areas but also contribute to form a framework for theoretical considerations and comparisons between the ground state and excited state reactions involving this atom. It is also considered that this type of research can be helpful in the area of exploring the relationship between reaction rate constants and the atomic or molecular electronic structures. In this work, the influence of molecular structure on the reaction rate when increasing the number of carbon atoms in the alkyl-halide chains is also investigated. Some measurements of the absorption cross-sections of gaseous MI2 (M = Ca, Sr, Ba) molecules by UV radiation as a function of wavelength are also made in this work but are presented in the appendices of this thesis.
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Liu, Weiming, and University of Lethbridge Faculty of Arts and Science. "Scanning tunneling microscopy and spectroscopy simulations of the silicon (111)-(7x7) surface." Thesis, Lethbridge, Alta. : University of Lethbridge, Faculty of Arts and Science, 2006, 2006. http://hdl.handle.net/10133/543.
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Since 1982, the Si (111)-(7x7) surface has been extensively studied both theoretically and experimentally with the modern powerful tools of STM and Scanning Tunneling Spectroscopy (STS). In this work, a simple atomic orbital model for the Si (111)-(7x7) surface is developed to simulate the experimental results of STM and STS. Based on Tersoff-Hamann’s theory for the tunneling current, simulations of clean Si (111)-(7x7) constant-current images are presented. The direct, real-space simulated topographic images of the surface are compared to experimental results qualitatively and quantitatively. The simulation of spectroscopic imaging and normalized conductance spectra are also included. The adsorption of atomic hydrogen atoms onto the Si (111)-(7x7) surface is also simulated.xiv, 146 leaves ; 29 cm.
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Favier, Marine. "Vers un instrument commercial pour la mesure des rapports isotopiques par Optical Feedback Cavity Enhanced Absorption Spectroscopy." Thesis, Université Grenoble Alpes (ComUE), 2017. http://www.theses.fr/2017GREAY106.
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Les isotopes stables ont permis de faire des découvertes majeures en science, comme, la datation de l'apparition de l'oxygène sur Terre à partir des isotopes du soufre [1] et l'analyse des échanges entre le carbone atmosphérique et celui des autres réservoirs (biosphère, océans) à partir du rapport isotopique 13C/12C [2].Traditionnellement, les rapports isotopiques sont mesurés avec des spectromètres de masse dédiés (IRMS : « isotope ratio mass spectrometer »). Depuis une dizaine d’années, ils sont également remplacés par des spectromètres commerciaux basés sur la spectroscopie infrarouge. Ces nouveaux instruments peuvent quantifier en temps réel et in-situ les rapports isotopiques des petites molécules d’intérêt environnemental en phase gazeuse (notamment l’eau et le dioxyde de carbone). Cependant, dans certains cas, ces instruments sont inadaptés. Ils utilisent soit trop d'échantillon, ou sont trop coûteux, ou ne mesurent pas certains isotopes. C'est en particulier le cas des isotopes du soufre.Nous montrons dans ce travail deux prototypes d’instruments qui mesurent des rapports isotopiques par Optical Feedback Cavity Enhanced Absorption Spectroscopy (OFCEAS). Le premier instrument détermine le rapport 13C/12C dans des échantillons d’air atmosphérique contenant entre 200 et 500 ppmv de CO2. Les concentrations les plus basses de cette gamme sont typiques de celles de l’air atmosphérique datant d’une dizaine de milliers d’années. On retrouve cet air dans les bulles emprisonnées dans les carottes de glace. Les concentrations les plus élevées correspondent à celles de l’air atmosphérique actuel. Pour cet instrument nous avons mis en évidence, grâce à une étude systématique des variables du système, l'impact de la pression, de la température et des franges optiques sur la mesure du rapport 13C/12C. En limitant ces sources de bruit, nous avons obtenu une précision de 0.2‰ en 2 minutes sur la mesure du rapport 13C/12C avec une concentration de CO2 autour de 280 ppmv. Nous avons obtenu une précision de 0.05‰ en référençant alternativement la mesure d'un échantillon à celle d'un gaz standard dans un cycle de mesure d'une durée de 2h par échantillon.Le deuxième prototype est le premier opérant dans le proche infrarouge capable d’analyser les rapports isotopiques 33S/32S et 34S/32S. Pour cela, il utilise la molécule H2S en phase gazeuse. Les composés de soufre, tels que les sulfates, sont en effet facilement convertis en H2S, contrairement au SF6 et au SO2, qui sont les gaz employés par la méthode IRMS conventionnelle. Les performances de l'instrument ont été examinées en réalisant des mesures statique sur trois mélanges de H2S et d'azote, présentant trois enrichissements en soufre différents. Ces trois mélanges ont été synthétisés au laboratoire. Les trois enrichissements relatifs en soufre-34 (0‰, 42.6‰ et 83.6‰) et en soufre-33 (0 ‰, 2.81‰, 5.39‰) ont été rigoureusement calibrés par IRMS. Nos mesures OFCEAS s'accordent à 1‰ près avec les valeurs obtenues par spectrométrie de masse. La précision obtenue en moyennant les résultats de 3 injections comportant 12 minutes de mesure est de 0.08‰ sur les deux rapports isotopiques 33S/32S et 34S/32SThe study of stable isotopes has led to many important advances in science, such as, for example, the determination of the timing of the oxygenation of Earth’s atmosphere using sulfur isotopes [1] and the quantification of the exchanges of carbon between the atmosphere and other reservoirs (biosphere, oceans) from the analysis of the 13C/12C isotope ratio [2].The conventional method to measure such isotopic ratios is by means of isotope ratio mass spectrometry (IRMS). About ten years ago, commercial instruments appeared that enabled the measurement of isotopic ratios using infrared spectroscopy of small molecules in the gas phase of interest for environmental studies (notably water and carbon dioxide). However, for some applications these instruments are not well adapted, for example, because they require too much material, or too expensive, or not able to measure isotopes in question. This is in particular the case for sulfur isotopes.During this work two prototype instruments were developed for the analysis of isotopic ratios by means of Optical Feedback Cavity Enhanced Absorption Spectroscopy (OFCEAS). The first targets the 13C/12C isotopic ratio in atmospheric air samples containing between 200 and 500 ppmv of CO2.The lowest concentration of this range is typical of paleo-air trapped in bubbles in ice cores, whereas the higher concentrations are encountered in modern air samples. For this instrument we have shown, through a detailed and systematic study, the effect of pressure, temperature, and optical interference fringes on the measurement of the isotopic ratio. Mitigating these sources of errors has led to a performance characterized by a precision of 0.2‰ in 2 minutes on measurements at a concentration of about 280 ppmv and a precision of 0.05‰ when alternatingly referencing the sample measurement to that of a standard material in a measurement cycle with duration of 2h for one sample.The second instrument is the first of its kind being able to analyze the 33S/32S and 34S/32S ratios through near-infrared spectroscopy on H2S gas. Sulfur compounds, such as sulfate, are easily converted to H2S, but this is not the case for SF6 or SO2, which are the common gases used in the conventional IRMS method. The instrument was demonstrated by performing static measurements on three isotopically different samples of H2S – nitrogen mixtures. These local standard materials were synthesized by us, and shown to have relative enrichment levels of 0‰, 42.6‰ and 83.6‰ for 34S/32S, and 0 ‰, 2.81‰, and 5.39‰ for 33S/32S by IRMS analyses. Our laser spectrometer measurements agree to within 1‰ with the calibrated IRMS values. The precision obtained after averaging three 12-minute measurements is 0.08‰ for both isotopic ratios
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Tsang, Chi-kin. "Analysis and control of organic vapours in air and determination of metals and toxic elements in fish samples by differential pulse voltammetry and atomic absorption spectrophotometry /." [Hong Kong : University of Hong Kong], 1991. http://sunzi.lib.hku.hk/hkuto/record.jsp?B13408914.
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Botha, G. N. "Development of an external cavity diode laser for application to spectroscopy and laser cooling and trapping of rubidium." Thesis, Stellenbosch : University of Stellenbosch, 2009. http://hdl.handle.net/10019.1/2307.
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Thesis (MSc (Physics))--University of Stellenbosch, 2009.In the presented study a diode laser was characterised and used for spec- troscopy, measuring the resonance lines of atomic rubidium. The characteristics of diode lasers and external cavity diode lasers (ECDL) for the purposes of ab- sorption spectroscopy were investigated and an experimental setup for tunable diode laser spectroscopy using an ECDL was developed. In external cavity diode lasers, the advantages of low cost, small size and e ciency of a diode laser is combined with tunability and a narrow frequency bandwidth. The ECDL was applied in experimental setups for absorption spectroscopy and saturated ab- sorption spectroscopy. Measurement of the absorption of atomic rubidium's D2 line near 780 nm is discussed. The Doppler broadened, as well as the Doppler free spectrum of the ne and hyper ne structure of the D2 line were measured and is discussed. Finer control of the ECDL's stability and frequency, using a servo circuit, were investigated and tested. An overview is given of laser cool- ing and trapping of neutral rubidium atoms, which is the main application the ECDL were developed for.
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Yang, Xin. "Study of the hydrogen-tungsten interaction for fusion : measurement of the atomic reflection coefficient by laser spectroscopy." Thesis, Aix-Marseille, 2017. http://www.theses.fr/2017AIXM0232.
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Les interactions plasma surface (PSI) sont considérées comme l'un des défis scientifiques majeurs de la fusion nucléaire magnétique contrôlée. L'interaction entre les isotopes d'hydrogène et les matériaux de l’enceinte à plasma tels que le tungstène revêt une importance particulière. Le coefficient de perte en surface des isotopes atomiques (γ) est un point clé dans les études PSI. Il peut donner des informations sur le recyclage de l'hydrogène atomique à la paroi et constitue ainsi un paramètre clé dans les modélisations des interactions plasma surface. Le but de ce projet est de déterminer les coefficients de perte de surface de l'hydrogène atomique et du deutérium sur échantillons de tungstène (W) et de nitrure de tungstène (WN) en utilisant une technique de fluorescence induite par plasma (PIF) et une technique de fluorescence induite par laser à deux photons (TALIF). Ce projet s'effectue dans le réacteur CAMITER qui est un réacteur plasma radiofréquence à basse pression au laboratoire PIIM de l'Université Aix-MarseillePlasma surface interaction (PSI) is considered to be one of the key scientific challenges in nuclear fusion. The interaction between hydrogen isotopes and plasma-facing materials such as tungsten is of particular importance. The atomic hydrogen isotope surface loss coefficient (γ) is a key point in PSI studies. It can give information on hydrogen isotope inventory and is an important input for modeling and theoretical work. The aim of this project is to determine atomic hydrogen and deuterium surface loss coefficients on tungsten (W) sample by using two-photon-absorption laser induced fluorescence (TALIF) and pulsed induced fluorescence (PIF) technique. This project is carried out in CAMITER reactor which is a low-pressure radio-frequency ICP reactor at PIIM laboratory in Aix-Marseille University
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Blais, Jean-Simon. "HPLC-AAS interfaces for the determination of ionic alkyllead, arsonium and selenonium compounds." Thesis, McGill University, 1990. http://digitool.Library.McGill.CA:80/R/?func=dbin-jump-full&object_id=74637.
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Three direct interfaces for coupling high performance liquid chromatography (HPLC) with atomic absorption spectrometry (AAS) were developed and optimized for the determination of ionic organolead, organoselenium and organoarsenic compounds. The first all-quartz interface consisted of a thermospray nebulizer and a flame microatomizer in which ionic alkyllead analytes (R$ sb{ rm n}$Pb$ sp{ rm (4-n)+};$ R = CH$ sb3,$ C$ sb2$H$ sb5)$ were atomized by a methanol (from HPLC eluent)-oxygen kinetic flame, and channeled in a quartz tube (atom keeper) mounted into the AAS optical beam. Alternately, the classical electrothermal atomization technique for organolead species (quartz furnace under hydrogen atmosphere) was coupled with a post-column derivatization-volatilization apparatus based on the ethylation of ionic alkylleads by sodium tetraethylborate. The limits of detection provided by these two approaches were 1.0-3.4 ng and 0.10-0.15 ng, respectively. Arsonium ((CH$ sb3) sb3$RAs$ sp+;$ R = CH$ sb3,$ CH$ sb2$CH$ sb2$OH, CH$ sb2$COOH) and selenonium ((CH$ sb3) sb2$RSe$ sp+;$ R = CH$ sb3,$ CH$ sb2$CH$ sb2$OH) species were quantified using a novel HPLC-AAS approach based on a direct coupling of three processes: thermospray nebulization, thermochemical hydride generation using hydrogen gas, and diffuse flame atomization. Direct evidences for the thermochemical hydride generation process was obtained by injecting (CH$ sb3) sb3$SeI and SeO$ sb2$ into the interface and capturing the gaseous end products in liquid chemical traps specific for SeH$ sb2$ and Se(IV). Both analytes were derivatized to SeH$ sb2$ only in the presence of hydrogen in the interface. Reverse- and normal-phase high pressure liquid chromatographic methods were also developed and adapted for the HPLC-AAS analyses of alkyllead, arsonium and selenonium compounds in real samples. The limit of detection of the arsonium and selenonium cations were 7.6-13.3 ng and 31.0-43.9 ng, respectively.
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Ehsan, Sadia. "High pressure homogenization of wood pulp samples prior to slurry introduction for the determination of Cu, Mn and Fe by graphite furnace atomic absorption spectrometry." Thesis, McGill University, 2001. http://digitool.Library.McGill.CA:80/R/?func=dbin-jump-full&object_id=31225.
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The scope of these studies was two-fold: to evaluate high pressure homogenized slurries as a rapid means of screening wood pulps for their Cu, Mn and Fe content and to evaluate the high pressure homogenization in combination with chelating agents or enzymatic digestion for the liberation/extraction of metal ions from this matrix.Cu, Mn and Fe were determined successfully in pulp samples using high-pressure homogenization prior to slurry introduction-GF-AAS. The analysis time of the method from sample acquisition to determination was of the order of a few minutes per sample.
Different cellulose swelling/dissolution agents were evaluated for the generation of quasi-stable pulp suspensions, rich in cellulose. High-pressure homogenization alone or in combination with chelating agents or enzymatic digestion was also investigated as a means of quantitatively releasing these metal ions into the liquid phases.
A new model of homogenizer equipped with ceramic homogenizing valve with a few modifications was evaluated in terms of metal contamination levels within the final sample dispersion. (Abstract shortened by UMI.)
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Rodriguez, Kenneth Ralph. "The extraordinary infrared transmission of metal microarrays for enhanced absorption spectroscopy of monolayers, nanocoatings, and catalytic surface reactions." Columbus, Ohio : Ohio State University, 2007. http://rave.ohiolink.edu/etdc/view?acc%5Fnum=osu1189549712.
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