| 1. |
- Andersson, Patrik U, 1970, et al.
(författare)
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Formation of Highly Rovibrationally Excited Ammonia from Dissociative Recombination of NH4
- 2010
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Ingår i: Journal of Physical Chemistry Letters. - : American Chemical Society (ACS). - 1948-7185. ; 1:17, s. 2519-2523
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Tidskriftsartikel (refereegranskat)abstract
- The internal energy distribution of ammonia formed in the dissociative recombination (DR) of NH4+ with electrons has been studied by an imaging technique at the ion storage ring CRYRING. The DR process resulted in the formation of NH3 + H (0.90 ± 0.01), with minor contributions from channels producing NH2 + H2 (0.05 ± 0.01) and NH2 + 2H (0.04 ± 0.02). The formed NH3 molecules were highly internally excited, with a mean rovibrational energy of 3.3 ± 0.4 eV, which corresponds to 70% of the energy released in the neutralization process. The internal energy distribution was semiquantitatively reproduced by ab initio direct dynamics simulations, and the calculations suggested that the NH3 molecules are highly vibrationally excited while rotational excitation is limited. The high internal excitation and the translational energy of NH3 and H will influence their subsequent reactivity, an aspect that should be taken into account when developing detailed models of the interstellar medium and ammonia-containing plasmas.
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| 3. |
- Ceco, Ema, et al.
(författare)
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The detection limit of imaging Raman spectroscopy for 2,4,6-TNT, 2,4-DNT, and RDX
- 2012
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Ingår i: Optics and photonics for counterterrorism, crime fighting, and defence VIII. - : SPIE - International Society for Optical Engineering. ; , s. 854604-
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Konferensbidrag (refereegranskat)abstract
- At the Swedish Defence Research Agency, FOI, Raman spectroscopy is used to detect explosives at stand-off distances. A technique based on imaging Raman spectroscopy has been shown to have the potential to detect trace amounts of explosives at stand-off distances. In this publication we provide limits of detection with the current imaging Raman setup for four different substances, cyclotrimethylenetrinitramine (RDX), 2,4-dinitrotoluene (DNT), 2,4,6-trinitrotoluene (TNT), and sulfur. The limits of detection for DNT and TNT were found to be about 0,5 μg while the lowest limit of detection was achieved for sulfur at 200 ng. The detection limit for RDX is 25,9 μg.
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| 4. |
- Danielsson, Mathias, et al.
(författare)
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The cross-section and branching fractions for dissociative recombination of the diacetylene cation C4D2
- 2008
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Ingår i: International Journal of Mass Spectrometry. - : Elsevier BV. - 1387-3806 .- 1873-2798. ; 273:3, s. 111-116
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Tidskriftsartikel (refereegranskat)abstract
- In this paper we report the results of a study on the dissociative recombination (DR) of the diacetylene cation, C4D2+, which has been carried out at the ion storage ring CRYRING in Stockholm, Sweden. The energy-dependent absolute DR cross-section as well as the branching fractions at 0 eV collision energy were measured. The DR cross-section was best fitted using the expression σ(E) = (7.5 ± 1.5) × 10−16 × E−(1.29±0.03) cm2 over the collision energy range 1–100 meV. The thermal rate coefficient was deduced from the cross-section to be α(T) = (1.10 ± 0.15) × 10−6 × (T/300)−(0.79±0.03) cm3/s. The reported branching fractions for C4D2+ agree with previous experiments on the DR of C4H2+ performed at the ASTRID storage ring in Aarhus, Denmark, and furthermore, indicate that the DR of C4D2+ possesses only two channels leading to the following products: C4D + D (75%) and C2D + C2D (25%).
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| 6. |
- Ehlerding, Anneli, 1978-
(författare)
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Electron-Ion Recombination in Atmospheric and Laboratory Plasmas
- 2006
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- In this thesis, the measurements performed at CRYRING, Stockholm University, on the dissociative recombination of C2H+, C2H4+, C2D5+, C3H7+, C3D7+, C4D9+, Na+(D2O), CF+, CF2+ and CO2+ are presented. The dissociative recombination is the reaction in which a positive molecular ion captures an electron and stabilizes the capture by dissociation into neutral fragments. This reaction is of importance in many plasma environments, both naturally occurring, such as planetary atmospheres and interstellar clouds, and man-made, such as plasma enhanced reactors.The results from this study show that the hydrocarbon ions have a large probability for breaking several hydrogen bonds as well as a carbon-carbon bond. In the DR reaction of Na+(D2O), the fracture of the cluster bond is by far the dominating pathway, and the single F detachment is shown to be the main dissociation channel for the fluorocarbon ions. The carbon dioxide cation, CO2+, dissociates exclusively into CO and O, which makes a difference in atmospheric models. The DR rate coefficient is also presented for the different ions. Besides a discussion of the results, this thesis also includes a presentation of the experimental technique and analyzing procedure.
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