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- Guenot, Diego, et al.
(författare)
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Measurements of relative photoemission time delays in noble gas atoms
- 2014
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Ingår i: Journal of Physics B. - : IOP Publishing. - 0953-4075 .- 1361-6455. ; 47:24, s. 245602-
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Tidskriftsartikel (refereegranskat)abstract
- We determine relative photoemission time delays between valence electrons in different noble gas atoms (Ar, Ne and He) in an energy range between 31 and 37 eV. The atoms are ionized by an attosecond pulse train synchronized with an infrared laser field and the delays are measured using an interferometric technique. We compare our results with calculations using the random phase approximation with exchange and multi-configurational Hartree-Fock. We also investigate the influence of the different ionization angular channels.
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| 6. |
- Boll, Rebecca, et al.
(författare)
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Imaging molecular structure through femtosecond photoelectron diffraction on aligned and oriented gas-phase molecules
- 2014
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Ingår i: Faraday Discussions. - : Royal Society of Chemistry (RSC). - 1364-5498. ; 171, s. 57-80
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Tidskriftsartikel (refereegranskat)abstract
- This paper gives an account of our progress towards performing femtosecond time-resolved photoelectron diffraction on gas-phase molecules in a pump-probe setup combining optical lasers and an X-ray free-electron laser. We present results of two experiments aimed at measuring photoelectron angular distributions of laser-aligned 1-ethynyl-4-fluorobenzene (C8H5F) and dissociating, laser-aligned 1,4-dibromobenzene (C6H4Br2) molecules and discuss them in the larger context of photoelectron diffraction on gas-phase molecules. We also show how the strong nanosecond laser pulse used for adiabatically laser-aligning the molecules influences the measured electron and ion spectra and angular distributions, and discuss how this may affect the outcome of future time-resolved photoelectron diffraction experiments.
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| 9. |
- Ekvall, Thomas, 1986, et al.
(författare)
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CO-KCl-SO2 interactions in an 80 kW propane-fired flame
- 2014
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Ingår i: the proceedings of the Impacts of Fuel Quality on Power production conference, 2014. ; , s. 13-
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Konferensbidrag (övrigt vetenskapligt/konstnärligt)abstract
- It is well known that combustion of biomass derived fuels may lead to problems with high-temperature corrosion (HTC). The HTC process is largely based on the release and transformation of chlorine, sulphur and alkali components during the combustion process. However, these components may also interact with other critical parts of the combustion chemistry and the present work focuses on how potassium chloride and sulphur dioxide influence the oxidation of carbon monoxide. This is investigated during combustion of propane (80 kW) applying both air and oxy-fuel combustion conditions. The experiments were carried out in Chalmers 100 kW oxy-fuel test facility in which sulphur dioxide and potassium chloride was added to the flame. The experimental results are also supported by modelling work including a detailed reaction mechanism of the related alkali-S-Cl chemistry. The results show that KCl promotes CO-oxidation in oxy-fuel combustion. However, for the experimental conditions tested in the present work, no significant effect was detected in air combustion. In addition, when adding water as well as SO2 to the flames, there were no significant effects on the measured CO concentrations in the respective flames.
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| 10. |
- Ekvall, Thomas, 1986, et al.
(författare)
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Modeling the Alkali Sulfation Chemistry of Biomass and Coal Co-firing in Oxy-fuel Atmospheres
- 2014
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Ingår i: Energy & Fuels. - : American Chemical Society (ACS). - 1520-5029 .- 0887-0624. ; 28:5, s. 3486-3494
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Tidskriftsartikel (refereegranskat)abstract
- In the present modeling work, the gas-phase alkali sulfation process is investigated. The combined effects of oxyfuel combustion and co-combustion on the sulfation of alkali metals are examined and compared to the corresponding process under air-fired conditions. According to the modeling results, the degree of sulfation of gas-phase alkali metals is generally higher for oxy-fuel combustion than for air fuel combustion. The recirculation strategy, in terms of the flue gas composition in oxy-fuel combustion, is important for the sulfation of alkali metals. The increased contents of sulfur and water contribute significantly to the degree of sulfation of the alkali species. The modeling also reveals that an increased content of HCl, which is present during wet recirculation, has a negative effect on the sulfation. Thus, the degree of sulfation is lower in wet recirculation than in dry recirculation. The effects of other important parameters, such as the sulfur/potassium ratio, oxygen concentration, and temperature, are discussed.
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