| 1. |
|
|
| 2. |
|
|
| 3. |
|
|
| 4. |
- Vigren, Erik, et al.
(författare)
-
Dissociative recombination of fully deuterated protonated acetonitrile, CD3CND+ : Product branching fractions, absolute cross section and thermal rate coefficient
- 2008
-
Ingår i: Physical Chemistry, Chemical Physics - PCCP. - : Royal Society of Chemistry (RSC). - 1463-9076 .- 1463-9084. ; 10, s. 4014-4019
-
Tidskriftsartikel (refereegranskat)abstract
- The dissociative recombination of fully deuterated protonated acetonitrile, CD3CND+, has been investigated at the CRYRING heavy ion storage ring, located at the Manne Siegbahn Laboratory, Stockholm, Sweden. Branching fractions were measured at similar to 0 eV relative collision energy between the ions and the electrons and in 65% of the DR events there was no rupture of bonds between heavy atoms. In the remaining 35%, one of the bonds between the heavy atoms was broken. The DR cross-section was measured between similar to 0 eV and 1 eV relative collision energy. In the energy region between 1 meV and 0.1 eV the cross section data were best fitted by the expression sigma = 7.37 x 10(-16) (E/eV)(-1.23) cm(2), whereas sigma = 4.12 x 10(-16) (E/eV)(-1.46) cm(2) was the best fit for the energy region between 0.1 and 1.0 eV. From the cross section a thermal rate coefficient of alpha(T) = 8.13 x 10(-7) (T/300)(-0.69) cm(3) s(-1) was deduced.
|
|
| 5. |
- Vigren, Erik, et al.
(författare)
-
Dissociative Recombination of Protonated Formic Acid : Implications for Molecular Cloud and Cometary Chemistry
- 2010
-
Ingår i: Astrophysical Journal. - 0004-637X .- 1538-4357. ; 709:2, s. 1429-1434
-
Tidskriftsartikel (refereegranskat)abstract
- At the heavy ion storage ring CRYRING in Stockholm, Sweden, we have investigated the dissociative recombination of DCOOD2+ at low relative kinetic energies, from similar to 1 meV to 1 eV. The thermal rate coefficient has been found to follow the expression k(T) = 8.43 x 10(-7) (T/300)(-0.78) cm(3) s(-1) for electron temperatures, T, ranging from similar to 10 to similar to 1000 K. The branching fractions of the reaction have been studied at similar to 2 meV relative kinetic energy. It has been found that similar to 87% of the reactions involve breaking a bond between heavy atoms. In only 13% of the reactions do the heavy atoms remain in the same product fragment. This puts limits on the gas-phase production of formic acid, observed in both molecular clouds and cometary comae. Using the experimental results in chemical models of the dark cloud, TMC-1, and using the latest release of the UMIST Database for Astrochemistry improves the agreement with observations for the abundance of formic acid. Our results also strengthen the assumption that formic acid is a component of cometary ices.
|
|
| 6. |
- Vigren, Erik, et al.
(författare)
-
Dissociative Recombination of Protonated Propionitrile, CH3CH2CNH+ : Implications for Titan's Upper Atmosphere
- 2010
-
Ingår i: Astrophysical Journal. - 0004-637X .- 1538-4357. ; 722:1, s. 847-850
-
Tidskriftsartikel (refereegranskat)abstract
- The dissociative recombination of protonated propionitrile, CH3CH2CNH+, has been investigated at the heavy ion storage ring, CRYRING, at the Manne Siegbahn Laboratory, Stockholm University, Sweden. The thermal rate coefficient has been deduced to follow k(T) = (1.5 ± 0.2) × 10–6 (T/300)–0.76 ± 0.02 cm3 s–1 for electron temperatures ranging from ~10 to ~1000 K. Measurements of the branching fractions were performed at ~0 eV relative kinetic energy. It has been found that in 43% ± 2% of the reactions the four heavy atoms remain in the same product fragment. An equal portion of the reactions leads to products where one of the heavy atoms is split off from the other three and 14% ± 1% result in a breakup into two heavy fragments containing two heavy atoms each. We discuss the significance of the data to Titan's upper atmosphere.
|
|
| 7. |
- Vigren, Erik, et al.
(författare)
-
Dissociative recombination of the acetaldehyde cation, CH3CHO
- 2010
-
Ingår i: Physical Chemistry, Chemical Physics - PCCP. - : Royal Society of Chemistry (RSC). - 1463-9076 .- 1463-9084. ; 12:37, s. 11670-11673
-
Tidskriftsartikel (refereegranskat)abstract
- The dissociative recombination of the acetaldehyde cation, CH3CHO+, has been investigated at the heavy ion storage ring CRYRING at the Manne Siegbahn Laboratory in Stockholm, Sweden. The dependence of the absolute cross section of the reaction on the relative kinetic energy has been determined and a thermal rate coefficient of k(T) = (1.5 +/- 0.2) x 10(-6) (T/300)(-0.70 +/- 0.02) cm(3) s(-1) has been deduced, which is valid for electron temperatures between similar to 10 and 1000 K. The branching fractions of the reaction were studied at similar to 0 eV relative kinetic energy and we found that breaking one of the bonds between two of the heavy atoms occurs in 72 +/- 2% of the reactions. In the remaining events the three heavy atoms stay in the same product fragment. While the branching fractions are fairly similar to the results from an earlier investigation into the dissociative recombination of the fully deuterated acetaldehyde cation, CD3CDO+, the thermal rate coefficient is somewhat larger for CH3CHO+. Astrochemical implications of the results are discussed.
|
|
| 8. |
- Vigren, Erik, et al.
(författare)
-
Dissociative recombination of the deuterated acetaldehyde ion, CD3CDO+ : product branching fractions, absolute cross sections and thermal rate coefficient
- 2007
-
Ingår i: Physical Chemistry, Chemical Physics - PCCP. - 1463-9076 .- 1463-9084. ; 9:22, s. 2856-2861
-
Tidskriftsartikel (refereegranskat)abstract
- Dissociative recombination of the deuterated acetaldehyde ion CD3CDO+ has been studied at the heavy-ion storage ring CRYRING, located at the Manne Siegbahn Laboratory, Stockholm, Sweden. Product branching fractions together with absolute DR cross-sections were measured. The branching fractions were determined at a relative collision energy between the ions and the electrons of 0 eV. With a probability of 34% the DR events resulted in no ruptures of bonds between heavy atoms (i.e. no breakage of the C–C bond or the CO bond). In the remaining 66% of the events one of the bonds between the heavy atoms was broken. The energy-dependent cross-section for the DR reaction was measured between 0 and 1 eV relative kinetic energy. In the energy region between 1 meV and 0.2 eV the absolute cross section could be fitted by the expression σ(E) = 6.8 × 10−16E−1.28 cm2, whereas in the energy interval between 0.2 and 1 eV the data were best fitted by σ(E) = 4.1 × 10−16E−1.60 cm2. From these cross section data the thermal rate coefficient (as a function of the electron temperature), α(T) = 9.2 × 10−7 (T/300)−0.72 cm3 s−1 was obtained.
|
|
| 9. |
- Zhaunerchyk, Vitali, et al.
(författare)
-
Investigation into the vibrational yield of OH products in the OH plus H plus H channel arising from the dissociative recombination of H3O
- 2009
-
Ingår i: Journal of Chemical Physics. - : AIP Publishing. - 0021-9606 .- 1089-7690. ; 130:21, s. 214302-
-
Tidskriftsartikel (refereegranskat)abstract
- The vibrational population of the hydroxyl radical, OH, formed in the OH+H+H channel arising from the dissociative recombination of the hydronium ion, H3O+, has been investigated at the storage ring CRYRING using a position-sensitive imaging detector. Analysis shows that the OH fragments are predominantly produced in the v=0 and v=1 states with almost equal probabilities. This observation is in disagreement with earlier FALP experiments, which reported OH(v=0) as the dominant product. Possible explanations for this difference are discussed.
|
|
| 10. |
- Zhaunerchyk, Vitali, et al.
(författare)
-
Sequential formation of the CH3+H+H channel in the dissociative recombination of CH5
- 2009
-
Ingår i: Physical Review A. Atomic, Molecular, and Optical Physics. - 1050-2947 .- 1094-1622. ; 79:3, s. 30701-
-
Tidskriftsartikel (refereegranskat)abstract
- The fragmentation dynamics in the CH3+H+H channel arising from the dissociative recombination of protonated methane, CH5+, has been investigated with an imaging detector at the CRYRING storage ring. The experimental results imply that this channel proceeds via two-step break-up in which the intermediate CH4 molecule is sufficiently internally excited to further fragment. These observations could go some way to explaining the discrepancy in results reported from ion storage rings and FALP apparatus.
|
|
