| 1. |
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| 2. |
- Aldén, Anna, et al.
(författare)
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HPLC analysis of carbohydrate deficient transferrin isoforms isolated by the Axis-Shield %CDT method
- 2005
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Ingår i: Clinica Chimica Acta. - : Elsevier BV. - 0009-8981 .- 1873-3492. ; 356:1-2, s. 143-146
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Tidskriftsartikel (refereegranskat)abstract
- Background: Carbohydrate-deficient transferrin (CDT) is elevated during prolonged overconsumption of alcohol and CDT is considered to be the most specific biochemical marker for alcohol overconsumption. However, an accurate method for analysing CDT is necessary because the test is frequently used for example in legal matters. Methods: Patient serum samples were analysed with the Axis-Shield %CDT and eluates were pooled together. Transferrin was purified from the pool by affinity chromatography and further analysed with HPLC to determine the ratios of different transferrin isoforms. Results: In the eluates using the Axis-Shield %CDT method, a substantial amount of trisialo transferrin was found, which is generally not considered a CDT isoform. Conclusions: The fact that trisialo transferrin is present may generate falsely elevated CDT results and it could at least partly explain the discrepancy between results of the Axis-Shield %CDT assay and HPLC in routine analysis. © 2005 Elsevier B.V. All rights reserved.
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| 3. |
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| 4. |
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| 5. |
- Borggren, Jesper, et al.
(författare)
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Temperature imaging in low-pressure flames using diode laser two-line atomic fluorescence employing a novel indium seeding technique
- 2016
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Ingår i: Applied Physics B. - : Springer Science and Business Media LLC. - 0946-2171 .- 1432-0649. ; 122:3
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Tidskriftsartikel (refereegranskat)abstract
- The use of diode lasers for spatially resolved temperature imaging is demonstrated in low-pressure premixed methane–air flames using two-line atomic fluorescence of seeded indium atoms. This work features the advantages of using compact diode lasers as the excitation sources with the benefits of two-dimensional planar imaging, which is normally only performed with high-power pulsed lasers. A versatile and reliable seeding technique with minimal impact on flame properties is used to introduce indium atoms into the combustion environment for a wide range of flame equivalence ratios. A spatial resolution of around 210 µm for this calibration-free thermometry technique is achieved for three equivalence ratios at a pressure of 50 mbar in a laminar flat flame.
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| 6. |
- Borggren, Jesper, et al.
(författare)
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Temperature imaging in low-pressure flames using diode lasers
- 2014
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Ingår i: Imaging and Applied Optics - Laser Applications to Chemical, Security and Environmental Analysis, LACSEA 2014. - Washington, D.C. : OSA. - 2162-2701. - 9781557523082 - 9781557523082
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Konferensbidrag (refereegranskat)abstract
- We present a calibration free technique for spatially resolved imaging of flame temperature. Its application is demonstrated in a low pressure premixed methane flame seeded with indium. Temperature measurements over a range of equivalence ratios are investigated.
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| 7. |
- De Marinis, Yang, et al.
(författare)
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Detection of SARS-CoV-2 by rapid antigen tests on saliva in hospitalized patients with COVID-19
- 2021
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Ingår i: Infection Ecology and Epidemiology. - : Informa UK Limited. - 2000-8686. ; 11:1
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Tidskriftsartikel (refereegranskat)abstract
- Background: The COVID-19 pandemic presents great challenges on transmission prevention, and rapid diagnosis is essential to reduce the disease spread. Various diagnostic methods are available to identify an ongoing infection by nasopharyngeal (NPH) swab sampling. However, the procedure requires handling by health care professionals, and therefore limits the application in household and community settings. Objectives: In this study, we aimed to determine if the detection of SARS-CoV-2 can be performed alternatively on saliva specimens by rapid antigen test. Study Design: Saliva and NPH specimens were collected from 44 patients with confirmed COVID-19. To assess the diagnostic accuracy of point-of-care SARS-CoV-2 rapid antigen test on saliva specimens, we compared the performance of four test products. Results: RT-qPCR was performed and NPH and saliva sampling had similar Ct values, which associated with disease duration. All four antigen tests showed similar trend in detecting SARS-CoV-2 in saliva, but with variation in the ability to detect positive cases. The rapid antigen test with the best performance could detect up to 67% of the positive cases with Ct values lower than 25, and disease duration shorter than 10 days. Conclusion: Our study therefore supports saliva testing as an alternative diagnostic procedure to NPH testing, and that rapid antigen test on saliva provides a potential complement to PCR test to meet increasing screening demand.
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| 8. |
- Hogstedt, Lasse, et al.
(författare)
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Low-noise mid-IR upconversion detector for improved IR-degenerate four-wave mixing gas sensing
- 2014
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Ingår i: Optics Letters. - 0146-9592. ; 39:18, s. 5321-5324
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Tidskriftsartikel (refereegranskat)abstract
- We compare a nonlinear upconversion detector with a conventional cryogenic InSb detector for the detection of coherent infrared light showing near-shot-noise-limited performance in the upconversion system. The InSb detector is limited by dark noise, which results in a 500 times lower signal-to-noise ratio. The two detectors are compared for the detection of a coherent degenerate four-wave mixing (DFWM) signal in the mid-infrared, and applied to measure trace-level acetylene in a gas flow at atmospheric pressure, probing its fundamental rovibrational transitions. In addition to lower noise, the upconversion system provides image information of the signal, thus adding new functionality compared to standard point detection methods. We further show that the upconversion detector system can be implemented as a simple replacement of the cryogenic detector. (C) 2014 Optical Society of America
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| 9. |
- Hot, Dina, et al.
(författare)
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Investigation of laser-induced grating spectroscopy of O2 for accurate temperature measurements towards applications in harsh environments
- 2021
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Ingår i: Journal of Raman Spectroscopy. - : Wiley. - 0377-0486 .- 1097-4555. ; 52:9, s. 1569-1581
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Tidskriftsartikel (refereegranskat)abstract
- We present an in-depth investigation of laser-induced grating spectroscopy (LIGS) for temperature measurements in practical applications using a narrow-band dye laser with 760 nm wavelength and a pulse duration of 8 ns as the source for the pump beams creating the laser-induced grating. The pump laser wavelength was set to be either resonant with the (Formula presented.) transition from the (Formula presented.) band of O2 for generation of thermal LIGS or nonresonant for generation of purely electrostrictive LIGS. Signals were generated in ambient air as well as in high-pressure or high-temperature dry air mixtures. Pump laser irradiances up to 11 GW/cm2 were used, which resulted in strong electrostrictive contribution to the overall LIGS signals at atmospheric pressure, with a low thermal contribution due to the weak absorption by the singlet O2 (Formula presented.). The advantage and disadvantage of thermal or electrostrictive LIGS for temperature measurements are discussed, as well as potential applications in high-pressure environments. Furthermore, the precision of the temperature measurement is discussed by comparing different analysis methods.
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| 10. |
- Hot, Dina, et al.
(författare)
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Mid-infrared laser-induced thermal grating spectroscopy of hot water lines for flame thermometry
- 2021
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Ingår i: Proceedings of the Combustion Institute. - : Elsevier BV. - 1540-7489. ; 38:1, s. 1885-1893
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Tidskriftsartikel (refereegranskat)abstract
- In this work we report the impact of using mid-infrared laser-induced thermal grating spectroscopy (IRLITGS) for temperature measurements in flames by probing hot water lines. The measurements have been performed in the product zone of laminar atmospheric CH 4 /H 2 /air flat flames with equivalence ratio ranging between 0.6 and 1.05. LITGS is a technique based on thermalization through collisions of the excited molecules for generation of a laser-induced grating, which then decays through thermal diffusion. As such, it tends to have limited application in atmospheric flames compared to flame measurements at elevated pressures due to the faster decay at low gas densities. However, by using mid-IR pump laser beams, it enables the generation of laser-induced gratings with large grating spacing, resulting in strong signal intensities and long signal durations. Single-shot IR-LITGS signals were recorded in the different CH 4 /H 2 /air flames that covered a temperature range between 1500 and 1800 K. To test the accuracy, the IR-LITGS flame temperature measurements were compared with laser Rayleigh scattering measurements and the result were in good agreement with each other. The IR-LITGS flame temperature measurements show a repetitive single-shot temperature precision better than 1% and an accuracy of 2.5% of the flame temperature. An IR-LITGS excitation scan of water in the flame shows that some ro-vibrational transitions exhibit no IR-LITGS signal, probably due to less efficient collisional energy transfer mechanism. This is important when deciding the wavelength to use for IR-LITGS flame temperature measurements using water absorption.
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| 11. |
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| 12. |
- Kiefer, Johannes, et al.
(författare)
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Gas-Phase and Combustion Diagnostics by Infrared Laser-Induced Grating Spectroscopy
- 2016
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Ingår i: Optics and Photonics for Energy and the Environment, E2 2016. - 9781557528209
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Konferensbidrag (refereegranskat)abstract
- Infrared laser-induced grating spectroscopy (IR-LIGS) is a powerful method for the detection of molecules in atmospheric and combustion chemistry by exploiting their strong and species-specific fundamental vibrations. This work discusses potentials and limitations of the method.
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| 13. |
- Kiefer, Johannes, et al.
(författare)
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Misalignment Effects in Laser-Induced Grating Experiments
- 2016
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Ingår i: Applied Spectroscopy. - : SAGE Publications. - 0003-7028 .- 1943-3530. ; 70:12, s. 2025-2028
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Tidskriftsartikel (refereegranskat)abstract
- Laser-induced grating spectroscopy (LIGS) is an experimental method in which two pulsed laser beams and a continuous-wave laser beam have to be superimposed under well-defined angles to generate a coherent signal beam. In this Note, the possible effects of different forms of misalignment are examined. This includes the overlap of the pump lasers as well as the influence of the probe laser alignment on the temporal profile of the signal.
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| 14. |
- Lindmark Månsson, Helena, et al.
(författare)
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Two-dimensional gel electrophoresis of proteins and peptides in bovine milk
- 2005
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Ingår i: International Dairy Journal. - : Elsevier BV. - 0958-6946. ; 15:2, s. 111-121
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Tidskriftsartikel (refereegranskat)abstract
- Proteins and peptides in bovine milk and colostrum were separated by two-dimensional gel electrophoresis (2-DE). The proteins were separated in the first dimension by isoelectric focusing in the pH ranges 4-7 and 6-11, and in the second dimension by sodium dodecyl sulphate polyacrylamide gel electrophoresis on 12.5% T homogeneous gels. The peptides were separated in the pH range 3-10 in the first dimension, while 15% T homogeneous gels were used in the second dimension. 2-DE evaluation of samples with various somatic cell counts showed an increased number of peptides with increased cell count. 2-DE analysis of samples heated at 65 and 85 degreesC for 30 min showed a decrease in the number of proteins and peptides with increased temperature. Colostrum exhibited a peptide pattern in which the intensity and number of spots decreased with time postpartum. These results show that 2-DE is a useful tool to detect variations of proteins and peptides in milk.
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| 15. |
- Mandenius, Carl-Fredrik, 1954-, et al.
(författare)
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Monitoring of influenza virus hemagglutinin in process samples using weak affinity ligands and surface plasmon resonance
- 2008
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Ingår i: Analytica Chimica Acta. - : Elsevier. - 0003-2670 .- 1873-4324. ; 623, s. 66-75
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Tidskriftsartikel (refereegranskat)abstract
- Surface plasmon resonance (SPR) was used to screen the interaction between a variety of affinity ligands and hemagglutinin (HA) from human influenza virus, with the aim of identifying low affinity ligands useful for the development of a rapid bioanalytical sensor. Three sialic acid-based structures and four lectins were evaluated as sensor ligands. The sialic acid-based ligands included a natural sialic acid-containing glycoprotein, human α1-acid glycoprotein (α1-AGP), and two synthetic 6′-sialyllactose-conjugates, with varying degree of substitution. The interaction of HA with the four lectin-based ligands, concanavalin A (Con A), wheat germ agglutinin (WGA), Maackia amurensis lectin (MAL), and Sambucus nigra agglutinin (SNA), showed a wide variation of affinity strengths. Affinity and kinetics data were estimated. Strong affinities were observed for Con A, WGA, α1-AGP, and a 6′-sialyllactose-conjugate with a high substitution degree, and low affinities were observed for MAL and a 6′-sialyllactose-conjugate with low substitution. The main objective, to identify a low affinity ligand which could be used for on-line monitoring and product quantification, was met by a 6′-sialyllactose–ovalbumin conjugate that had 0.6 mol ligand per mol carrier protein. The apparent affinity of this ligand was estimated to be 1.5 ± 0.03 μM (KD) on the SPR surface. Vaccine process samples containing HA were analyzed in the range 10–100 μg HA mL−1 and correlated with single-radial immunodiffusion. The coefficient of variation on the same chip was between 0.010 and 0.091.
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| 16. |
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| 17. |
- Sahlberg, Anna Lena, et al.
(författare)
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Investigation of ro-vibrational spectra of small hydrocarbons at elevated temperatures using infrared degenerate four-wave mixing
- 2016
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Ingår i: Journal of Raman Spectroscopy. - : Wiley. - 0377-0486. ; 47:9, s. 1130-1139
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Tidskriftsartikel (refereegranskat)abstract
- The ro-vibrational spectra around 3 µm of four small hydrocarbons (C2H2, CH4, C2H6 and C2H4) at 296, 550 and 820 K have been investigated using infrared degenerate four-wave mixing (IR-DFWM). The spectra were recorded in gas flows of nitrogen with small admixtures of the hydrocarbons. A fused silica glass tube surrounded by an electric heating wire was used to heat the gas flows. The recorded IR-DFWM spectra are compared with simulations using the spectral information available in the HITRAN database, in order to identify spectral lines. The measurements demonstrate good signal to noise ratio and good sensitivity even at elevated temperatures. Several weak hot lines were detected that are not included in the current database. This paper demonstrates the potential of IR-DFWM for purposes of investigating spectral lines at elevated temperatures, which is often a challenging task with conventional absorption spectroscopy techniques. The possibility of applying IR-DFWM for combustion diagnostics of small hydrocarbons is discussed from the detection limits of the measurements and the potential water line interference. Because of the non-linear nature of the DFWM technique, it provides much higher contrast for strong lines of small molecules over backgrounds of high-density weak lines, which commonly exist in hot gas flows of thermochemical reactions.
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| 18. |
- Sahlberg, Anna Lena, et al.
(författare)
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Mid-infrared laser-induced thermal grating spectroscopy in flames
- 2017
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Ingår i: Proceedings of the Combustion Institute. - : Elsevier BV. - 1540-7489. ; 36:3, s. 4515-4523
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Tidskriftsartikel (refereegranskat)abstract
- For the first time, laser-induced thermal grating spectroscopy (LITGS) in the spectral range around 3. μm is demonstrated as a versatile diagnostic tool. This spectral region is of particular interest in combustion diagnostics as many relevant species such as hydrocarbons and water exhibit fundamental vibrational modes and hence can be probed with high sensitivity. Another benefit of the IR-LITGS is that it allows performing spectroscopy in the infrared combined with signal detection in the visible. Hence, the strong thermal radiation inherent in flames does not represent an interference. As the first step, we present the application of IR-LITGS to cold gas flows, where traces of ethylene and water vapor are detected. The time-resolved LITGS signals, which can be acquired in a single laser shot, are rich in information and allow deriving temperature and to some extend chemical composition. In the second step, the IR-LITGS technique is applied to ethylene/air flames stabilized on a flat flame burner. A proof-of-concept study is carried out, in which the temperature is determined in the burned region of flames with systematically varied equivalence ratio (0.72 < Φ <. 2.57). Moreover, in a highly sooty flame, LITGS signals were recorded as a function of height above the burner and allowed the determination of the temperature profile. The proposed IR-LITGS method has the potential for enabling single-shot measurements of several parameters at a time. Its applicability to sooty flame environments opens up new opportunities to study the complex formation of carbonaceous particles in flames.
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| 19. |
- Sahlberg, Anna-Lena, et al.
(författare)
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Mid-Infrared Polarization Spectroscopy Measurements of Species Concentrations and Temperature in a Low-Pressure Flame
- 2019
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Ingår i: Applied Spectroscopy. - : SAGE Publications. - 1943-3530 .- 0003-7028. ; 73:6, s. 653-664
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Tidskriftsartikel (refereegranskat)abstract
- Quantitative measurements of CH4 mole fractions at different HAB in the flame were realized by a calibration measurement in a low pressure gas flow of N2 with a small admixture of known amount of CH4. A comprehensive study of the collision effects on the IRPS signal was performed in order to quantify the flame measurement. The concentration and temperature measurements were found to agree reasonably well with simulations using Chemkin. These measurements We demonstrate quantitative measurements of CH4 mole fractions in a low pressure fuel-rich premixed dimethyl ether/oxygen/argon flat flame (Φ =1.87, 37 mbar) using mid-infrared polarization spectroscopy (IRPS). Non-intrusive in situ detection of CH4, C2H2 and C2H6 in the flame was realized by probing the fundamental asymmetric C-H stretching vibration bands in the respective molecules in the spectral range 2970-3340 cm-1. The flame was stabilized on a McKenna-type porous plug burner hosted in a low pressure chamber. The temperature at different heights above the burner (HAB) was measured from the line ratio of temperature sensitive H2O spectral lines recorded using IRPS. prove the potential of IRPS as a sensitive, non-intrusive, in situ technique in low pressure flames.
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| 20. |
- Sahlberg, Anna Lena, et al.
(författare)
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Mid-infrared pumped laser-induced thermal grating spectroscopy for detection of acetylene in the visible spectral range
- 2016
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Ingår i: Applied Spectroscopy. - : SAGE Publications. - 0003-7028 .- 1943-3530. ; 70:6, s. 1034-1043
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Tidskriftsartikel (refereegranskat)abstract
- We present mid-infrared laser-induced thermal grating spectroscopy (IR-LITGS) using excitation radiation around 3 μm generated by a simple broadband optical parametric oscillator (OPO). Acetylene as a typical small hydrocarbon molecule is used as an example target species. A mid-infrared broadband OPO pumped by the fundamental output of a neodymium-doped yttrium aluminum garnet (Nd:YAG) laser was used to generate the pump beams, with pulse energies of 6-10 mJ depending on the wavelength. The line width of the OPO idler beam was ∼5 cm-1, which is large enough to cover up to six adjacent acetylene lines. The probe beam was the radiation of a 532 nm cw solid state laser with 190 mW output power. Signals were generated in atmospheric pressure gas flows of N2, air, CO2 and Ar with small admixtures of C2H2. A detection limit of less than 300 ppm was found for a point measurement of C2H2 diluted in N2. As expected, the oscillation frequency of the IR-LITGS signal was found to have a large dependency on the buffer gas, which allows determination of the speed of sound. Moreover, the results reveal a very strong collisional energy exchange between C2H2 and CO2 compared to the other gases. This manifests as significant local heating. In summary, the MIR-LITGS technique enables spectroscopy of fundamental vibrational transitions in the infrared via detection in the visible spectral range.
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| 21. |
- Sahlberg, Anna-Lena, et al.
(författare)
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Non-intrusive in situ detection of methyl chloride in hot gas flows using infrared degenerate four-wave mixing
- 2015
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Ingår i: Journal of Raman Spectroscopy. - : Wiley. - 1097-4555 .- 0377-0486. ; 46:8, s. 695-701
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Tidskriftsartikel (refereegranskat)abstract
- We demonstrate the potential of infrared degenerate four-wave mixing (IR-DFWM) as a tool for non-intrusive in situ spatially resolved detection of CH3Cl in reactive hot gas flows especially feasible for applications to biomass combustion and gasification. IR-DFWM spectra of CH3Cl, by probing ro-vibrational transitions belonging to the fundamental stretching modes v(1) and v(4), have been successfully recorded in gas flows diluted with nitrogen at atmospheric pressure and elevated temperatures up to 820K. In order to identify the spectral lines of CH3Cl, the recorded IR-DFWM spectra are compared with simulations using molecular parameters extracted from the HITRAN database. The potential interference from water vapor is discussed from measurements of H2O spectrum at 820K combined with simulations of H2O IR-DFWM spectrum based on the HITEMP database, and it was found that the (Q)Q(6) line of the v(1) band is relatively free from water interference at elevated temperatures. At atmospheric pressure, the detection limits for temperatures at 296, 550 and 820K were estimated to be 2.1, 3.1 and 6.2 (x10(15) molecules/cm(3)), respectively, by scanning the (Q)Q(6) line of the v(1) band. These results show the potential of interference free detection of CH3Cl with IR-DFWM in harsh environments like combustion. Copyright (c) 2015 John Wiley & Sons, Ltd.
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