| 1. |
- Alnis, Janis, et al.
(författare)
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Laser spectroscopy of free molecular oxygen dispersed in wood materials
- 2003
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Ingår i: Applied Physics B. - : Springer Science and Business Media LLC. - 0946-2171 .- 1432-0649. ; 77:6-7, s. 691-695
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Tidskriftsartikel (refereegranskat)abstract
- The recently introduced Gas in Scattering Media Absorption Spectroscopy (GASMAS) technique is applied to the study of various wood samples. Molecular oxygen in the pores of the strongly scattering material is detected using diode laser spectroscopy around 760 nm. Diffuse light propagation in these media is studied by time-dispersion measurements. Furthermore, anisotropy related to the fibre structure of wood and gas diffusion properties are studied. Promising extensions of the experiments are discussed.
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| 2. |
- Alnis, J, et al.
(författare)
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Sum-frequency generation with a blue diode laser for mercury spectroscopy at 254 nm
- 2000
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Ingår i: Applied Physics Letters. - : AIP Publishing. - 0003-6951 .- 1077-3118. ; 76:10, s. 1234-1236
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Tidskriftsartikel (refereegranskat)abstract
- Blue diode lasers emitting 5 mW continuous-wave power around 400 nm have recently become available. We report on the use of a blue diode laser together with a 30 mW red diode laser for sum-frequency generation around 254 nm. The ultraviolet power is estimated to be 0.9 nW, and 35 GHz mode-hop-free tuning range is achieved. This is enough to perform high-resolution ultraviolet spectroscopy of mercury isotopes. The possibility to use frequency modulation in the ultraviolet is demonstrated; however, at present the ultraviolet power is too low to give advantages over direct absorption monitoring. Mercury detection at atmospheric pressure is also considered which is of great interest for environmental monitoring. (C) 2000 American Institute of Physics. [S0003-6951(00)02810-2].
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| 3. |
- Biemont, E, et al.
(författare)
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Measurement of radiative lifetimes and determination of transition probabilities of astrophysical interest in HoIII
- 2001
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Ingår i: Monthly Notices of the Royal Astronomical Society. - : Oxford University Press (OUP). - 1365-2966 .- 0035-8711. ; 328:4, s. 1085-1090
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Tidskriftsartikel (refereegranskat)abstract
- Lifetimes of six levels belonging to the 4f(10)6p configuration of Ho III have been measured for the first time using the time-resolved laser-induced fluorescence method. They are compared with multiconfigurational pseudo-relativistic Hartree-Fock calculations. A very good agreement is found. Using the experimental lifetimes and theoretical branching fractions, a first set of transition probabilities of astrophysical interest has been obtained for this ion.
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| 4. |
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| 5. |
- Gustafsson, U, et al.
(författare)
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Frequency-modulation spectroscopy with blue diode lasers
- 2000
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Ingår i: Applied Optics. - 2155-3165. ; 39:21, s. 3774-3780
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Tidskriftsartikel (refereegranskat)abstract
- Frequency-modulation spectroscopy provides ultrasensitive absorption measurements. The technique is especially adaptable to diode lasers, which can be modulated easily, and has been used extensively in the near-infrared and infrared spectral regions. The availability of blue diode lasers now means that the accessible wavelength region can be increased. We successfully demonstrate wavelength-modulation spectroscopy and two-tone frequency-modulation spectroscopy for the weak second resonance line of potassium at 404.8 nm and for the transition at 405.8 nm in lead, starting from the thermally populated 6p(2) P-3(2) metastable level, information on the modulation parameters is obtained with a fitting procedure. Experimental signal-to-noise ratios: at different absorption levels are compared with theoretical signal-to-noise ratios and show good agreement. Detection sensitivities of 2 x 10(-6) and 5 x 10(-6) for wavelength and two-tone frequency-modulation spectroscopy, respectively, for a 120-Hz bandwidth are demonstrated. (C) 2000 Optical Society of America.
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| 6. |
- Nordqvist, Joakim, et al.
(författare)
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Perspectives on performance and policy in industry – Environmental and quality concerns to enhance energy efficiency
- 2003
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Ingår i: [Host publication title missing].
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Konferensbidrag (refereegranskat)abstract
- Energy efficiency in industry has been a priority in Chinese policy and planning for more than twenty years. Great achievements in this area have been made. Still, in many cases a considerable potential for improved industrial energy efficiency remains, not least in terms of enhancement of technical capacity. Cement production is one sector where this is evident. Policies have been devised to address this issue and to raise performance within the industry in an extensive market-transforming effort. Among the most forceful in their intended effects are policies banning certain production technologies, and the decreed closures of badly performing plants. In many cases, however, compliance with such policies falters. Alongside energy efficiency and technical capacity there are other industrial goals. Three conceivable goals in cement production, concurring with energy efficiency are, on the one hand, improving the grade (quality) of cement produced, and, on the other, the environmental challenges of reducing local air pollution and mitigating climate change. Policies and instruments to promote such objectives might help boost performance in energy efficiency, but careful policy design is important. Whereas improving overall cement grades and curbing pollution are recognised as worthwhile objectives by many actors within China's cement sector, very few relate cement production to climate issues. From this vantage-point, the current paper analyses the present situation in China to examine how different policies and instruments that target grade, pollution, and climate may or may not affect future performance of the country's cement industry.
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| 7. |
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| 8. |
- Sjöholm, Mikael, et al.
(författare)
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Analysis of gas dispersed in scattering media
- 2001
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Ingår i: Optics Letters. - 0146-9592. ; 26:1, s. 16-18
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Tidskriftsartikel (refereegranskat)abstract
- Monitoring of free gas embedded in scattering media, such as wood, fruits, and synthetic materials, is demonstrated by use of diode laser spectroscopy combined with sensitive modulation techniques. Gas detection is made possible by the contrast of the narrow absorptive feature of the free-gas molecules with the slow wavelength dependence of the absorption and scattering cross sections in solids and liquids. An absorption sensitivity of 2.5 x 10(-4), corresponding to a 1.25-mm air column, is demonstrated by measurements of dispersed molecular oxygen. These techniques open up new possibilities for characterization and diagnostics, including internal gas pressure and gas-exchange assessment, in organic and synthetic materials. (C) 2001 Optical Society of America. OCIS codes: 300.6360, 290.7050, 290.5820, 170.3660, 020.3690, 160.4890.
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| 9. |
- Sjöholm, Mikael, et al.
(författare)
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Gas transport in wood assessed by laser spectroscopy
- 2003
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Ingår i: 2003 Conference on Lasers and Electro-Optics Europe (CLEO/Europe 2003) (IEEE Cat. No.03TH8666). - 0780377346 ; , s. 505-505
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Konferensbidrag (refereegranskat)abstract
- The Gas in scattering media absorption spectroscopy (GASMAS) technique provides new opportunities to nondestructively study gas in highly scattering natural and man-made porous materials. In this paper, we report applications of the GASMAS method on wood samples using diode-laser-based spectroscopy on molecular oxygen. And the integrated oxygen absorption for wood of different densities and the anisotropy related to the fibre structure was also investigated
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| 10. |
- Somesfalean, Gabriel, et al.
(författare)
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Concentration measurement of gas embedded in scattering media by employing absorption and time-resolved laser spectroscopy
- 2002
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Ingår i: Applied Optics. - 2155-3165. ; 41:18, s. 3538-3544
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Tidskriftsartikel (refereegranskat)abstract
- Diode-laser-based absorption spectroscopy for the evaluation of embedded gas concentrations in porous materials is demonstrated in measurements of molecular oxygen dispersed throughout scattering polystyrene foam, used here as a generic test material. The mean path length of light scattered in the material is determined with the temporal characteristics of the radiation transmitted through the sample. This combined with sensitive gas-absorption measurements employing wavelength-modulation spectroscopy yields an oxygen concentration in polystyrene foam of 20.4% corresponding to a foam porosity of 98%, which is consistent with manufacturing specifications. This feasibility study opens many possibilities for quantitative measurements by using the method of gas-in-scattering-media absorption spectroscopy. (C) 2002 Optical Society of America.
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