| 1. |
- Andersson, Patrik U, 1970, et al.
(författare)
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Cluster ions DN + ejected from dense and ultra-dense deuterium by Coulomb explosions: Fragment rotation and D+ backscattering from ultra-dense clusters in the surface phase
- 2012
-
Ingår i: International Journal of Mass Spectrometry. - : Elsevier BV. - 1387-3806. ; 310, s. 32-43
-
Tidskriftsartikel (refereegranskat)abstract
- The two forms of condensed atomic deuterium, dense deuterium D(1) and ultra-dense deuterium D(−1), can be studied by laser-induced Coulomb explosion time-of-flight mass spectrometry and neutral timeof- flight. In the present study pulsed laser intensity below 1014W cm−2 is used. Cluster ions DN + from D(1) are observed with N = 3, 4, 12 and 17, thus not in close-packed forms. Clusters DN(1) are mainly in the form of chains of D2 and D3 groups, a shape derived from the D(−1) material which D(1) is spontaneously converted to. Only atomic ions D+ with initial kinetic energy of hundreds of eV are observed from D(−1). Half of these ions are ejected from the emitter surface, half of them penetrate into the ultra-dense D(−1) layer on the emitter surface. This second half of the ions is reflected completely from the surface layer formed by ultra-dense D(−1) strongly bonded clusters D3(−1) and D4(−1).
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| 2. |
- Andersson, Patrik U, 1970, et al.
(författare)
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Deuteron energy of 15 MK in ultra-dense deuterium without plasma formation: Temperature of the interior of the Sun
- 2010
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Ingår i: Physics Letters A. - 0375-9601. ; 374:28, s. 2856-2860
-
Tidskriftsartikel (refereegranskat)abstract
- Deuterons are released with kinetic energy up to 630 eV from ultra-dense deuterium as shown previously, by Coulomb explosions initiated by ns laser pulses at < 1011 Wcm−2. With higher laser intensity at < 1014 Wcm−2, the initial kinetic energy now observed by TOF-MS with variable acceleration energy is up to 1100 eV per deuteron. This indicates ejection of one deuteron by Coulomb repulsion from two stationary charges in the material. It proves a full kinetic energy release of 1260 eV or a deuteron temperature of 15 MK, similar to the temperature in the interior of the Sun. Plasma processes are excluded by the sharp TOF peaks observed and by the slow signal variation with laser intensity. Deuterons with even higher energy from multiple charge repulsion are probably detected. D + D fusion processes are expected to exist in the ultra-dense phase without plasma formation.
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| 3. |
- Andersson, Patrik U, 1970, et al.
(författare)
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Efficient source for the production of ultradense deuterium D(-1) for laser-induced fusion (ICF)
- 2011
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Ingår i: Review of Scientific Instruments. - : AIP Publishing. - 0034-6748 .- 1089-7623. ; 82
-
Tidskriftsartikel (refereegranskat)abstract
- A novel source which simplifies the study of ultradense deuterium D(-1) is now described. This means one step further toward deuterium fusion energy production. The source uses internal gas feed and D(-1) can now be studied without time-of-flight spectral overlap from the related dense phase D(1). The main aim here is to understand the material production parameters, and thus a relatively weak laser with focused intensity ≤1012 W cm−2 is employed for analyzing the D(-1) material. The properties of the D(-1) material at the source are studied as a function of laser focus position outside the emitter, deuterium gas feed, laser pulse repetition frequency and laser power, and temperature of the source. These parameters influence the D(-1) cluster size, the ionization mode, and the laser fragmentation patterns.
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| 4. |
- Andersson, Patrik U, 1970, et al.
(författare)
-
Fast atoms and negative chain-cluster fragments from laser-induced Coulomb explosions in a super-fluid film of ultra-dense deuterium D(-1)
- 2012
-
Ingår i: Physica Scripta. - : IOP Publishing. - 0031-8949 .- 1402-4896. ; 86:4
-
Tidskriftsartikel (refereegranskat)abstract
- Fragments from laser-induced Coulomb explosions (CE) in a thin super-fluid film of ultra-dense deuterium D(-1) on a vertical surface are now observed by both negative and positive time-of-flight mass spectrometry. The so-called normal phase of the super-fluid is probably associated with D-4 clusters and gives only neutral atomic fragments with a kinetic energy from the CE of 945 eV. The super-fluid phase is associated with long chain clusters D-2N with N deuteron pairs and gives cluster fragments by CE mainly with a kinetic energy of 315 eV from the central cleavage in a neutral, positive or negative form. This indicates that the chain clusters are standing perpendicularly to the surface. The fragment charge state is influenced by the external field, which indicates efficient charge transfer processes.
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| 5. |
- Andersson, Patrik U, 1970, et al.
(författare)
-
Formation of Highly Rovibrationally Excited Ammonia from Dissociative Recombination of NH4
- 2010
-
Ingår i: Journal of Physical Chemistry Letters. - : American Chemical Society (ACS). - 1948-7185. ; 1:17, s. 2519-2523
-
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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| 6. |
- Andersson, Patrik U, 1970, et al.
(författare)
-
Fusion Generated Fast Particles by Laser Impact on Ultra-Dense Deuterium: Rapid Variation with Laser Intensity
- 2012
-
Ingår i: Journal of Fusion Energy. - : Springer Science and Business Media LLC. - 0164-0313 .- 1572-9591. ; 31, s. 249-256
-
Tidskriftsartikel (refereegranskat)abstract
- Nuclear fusion D+D processes are studied by nanosecond pulsed laser interaction with ultra-dense deuterium. This material has a density of 1029 cm-3 as shown in several previous publications. Laser power is \2 W (0.2 J pulses) and laser intensity is\1014 W cm-2 in the 5–10 lm wide beam waist. Particle detection by time-offlight energy analysis with plastic scintillators is used. Metal foils in the particle flux to the detector remove slow ions, and make it possible to convert and count particles with energy well above 1 MeV. The variation of the signal of MeV particles from D?D fusion is measured as a function of laser power. At relatively weak laser-emitter interaction, the particle signal from the laser focus varies as the square of the laser power. This indicates collisions in the ultra-dense deuterium of two fast deuterons released by Coulomb explosions. During experiments with stronger laser-emitter interaction, the signal varies approximately as the sixth power of the laser power, indicating a plasma process. At least 2 9 106 particles are created by each laser pulse at the maximum intensity used. Our results indicate break-even in fusion at a laser pulse energy of 1 J with the same focusing, in approximate agreement with theoretical results for ignition conditions in ultra-dense deuterium. Radiation loss at high temperature will however require higher laser energy at break-even.
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| 7. |
- Andersson, Patrik U, 1970, et al.
(författare)
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Search for Superconductivity in Ultra-dense Deuterium D(-1) at Room Temperature: Depletion of D(-1) at Field Strength > 0.05 T
- 2012
-
Ingår i: Journal of Superconductivity and Novel Magnetism. - : Springer Science and Business Media LLC. - 1557-1939 .- 1557-1947. ; 25:4, s. 873-882
-
Tidskriftsartikel (refereegranskat)abstract
- Ultra-dense deuterium D(-1) is expected to be both a superfluid and a superconductor as shown by recent theoretical research. Condensed D(-1) can be deposited on surfaces by a source which produces a stream of clusters. A magnetic field strongly influences the type of material formed. Very little of D(-1) and of the form D(1), which is strongly coupled to D(-1), exists on the magnet surface or within several mm from the magnet surface. Even the formation of D(-1) on the source emitter is strongly influenced by a magnetic field, with a critical field strength in the range 0.03-0.07 T. Higher excitation levels D(2) and D(3) dominate in a magnetic field. The excitation level D(2) is now observed for the first time. The removal of D(-1) and D(1) in strong magnetic fields is proposed to be due to a Meissner effect in long D(-1) clusters by large-orbit electron motion. The lifting of long D(-1) clusters above the magnet surface is slightly larger than expected, possibly due to the coupling to D(1). The previously reported oscillation between D(-1) and D(1) in an electric field is proposed to be due to destruction of D(-1).
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| 8. |
- Andersson, Patrik U, 1970, et al.
(författare)
-
Superfluid ultra-dense deuterium D(-1) at room temperature
- 2011
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Ingår i: Physics Letters A. - : Elsevier BV. - 0375-9601. ; 375, s. 1344-1347
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Tidskriftsartikel (refereegranskat)abstract
- Ultra-dense deuterium D(−1) is expected to be both superfluid and superconductive. It is deposited on surfaces below a novel source producing a stream of D(−1) clusters. It is studied by laser probing and Coulomb explosions giving cluster fragments which are observed by time-of-flight measurements. It is observed on surfaces at a few cm height above the container below the source, and on the outside of the container. D(−1) is detected above a 1 cm long vertical capillary in vacuum (fountain effect). This suggests the existence of superfluid D(−1) which is the only material that may be superfluid at room temperature.
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| 9. |
- Badiei, Shahriar, 1969, et al.
(författare)
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Laser-driven nuclear fusion D+D in ultra-dense deuterium: MeV particles formed without ignition
- 2010
-
Ingår i: Laser and Particle Beams. - 0263-0346. ; 28:2, s. 313-317
-
Tidskriftsartikel (refereegranskat)abstract
- The short D-D distance of 2.3 pm in the condensed material ultra-dense deuterium means that it is possible that only a small disturbance is required to give D+D fusion. This disturbance could be an intense laser pulse. The high excess kinetic energy of several hundred eV given to the deuterons by laser induced Coulomb explosions in the material increases the probability of spontaneous fusion without the need for a high plasma temperature. The temperature calculated from the normal kinetic energy of the deuterons of 630 eV from the Coulomb explosions is 7 MK, maybe a factor of 10 lower than required for ignition. We now report on experiments where several types of high-energy particles from laser impact on ultra-dense deuterium are detected by plastic scintillators. Fast particles with energy up to 2 MeV are detected at a time-of-flight as short as 60 ns, while neutrons are detected at 50 ns time-of-flight after passage through a steel plate. A strong signal peaking at 22.6 keV u-1 is interpreted as due to mainly T retarded by collisions with H atoms in the surrounding cloud of dense atomic hydrogen.
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| 10. |
- Badiei, Shahriar, 1969, et al.
(författare)
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Laser-induced variable pulse-power TOF-MS and neutral time-of-flight studies of ultradense deuterium
- 2010
-
Ingår i: Physica Scripta. - : IOP Publishing. - 0031-8949 .- 1402-4896. ; 81:4, s. 045601 1-13
-
Tidskriftsartikel (refereegranskat)abstract
- The ultradense atomic deuterium material named D(−1) is conveniently studied by laser-induced Coulomb explosion methods. A well-defined high kinetic energy release (KER) from this material was first reported in Badiei et al (2009 Int. J. Hydrog. Energy 34 487) and a two-detector setup was used to prove the high KER and the complex fragmentation patterns in Badiei et al (2009 Int. J. Mass Spectrom. 282 70). The common KER is 630±30 eV, which corresponds to an interatomic distance D–D of 2.3±0.1 pm. In both ion and neutral time-of-flight (TOF) measurement, two similar detectors at widely different flight distances prove that atomic particles are observed. New results on neutral TOF spectra are now reported for the material D(−1). It is shown that density changes of D(−1) are coupled to similar changes in ordinary dense D(1), and it is proposed that these two forms of dense deuterium are rapidly transformed into each other. The TOF-MS signal dependence on the intensity of the laser is studied in detail. The fast deuteron intensity is independent of the laser power over a large range, which suggests that D(−1) is a superfluid with long-range efficient transport of excitation energy or particles.
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| 11. |
- Badiei, Shahriar, 1969, et al.
(författare)
-
Production of ultradense deuterium: A compact future fusion fuel
- 2010
-
Ingår i: Applied Physics Letters. - 1077-3118. ; 96:12
-
Tidskriftsartikel (refereegranskat)abstract
- Ultradense deuterium as a nuclear fuel in laser-ignited inertial confinement fusion appears to have many advantages. The density of ultradense deuterium D(−1) is as high as 140 kg cm−3 or 10^29 cm−3. This means that D(−1) will be very useful as a target fuel, circumventing the complex and unstable laser compression stage. We show that the material is stable apart from the oscillation between two forms, and can exist for days in the laboratory environment. We also demonstrate that an amount of D(−1) corresponding to tens of kilojoules is produced in each experiment. This may be sufficient for break-even.
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| 12. |
- Kong, Xiangrui, et al.
(författare)
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Environmental molecular beam studies of ice surface processes
- 2011
-
Ingår i: Physics and Chemistry of Ice 2010 (The 12th International Conference on the Physics and Chemistry of Ice, Sapporo, Japan, September 5-10, 2010, Eds. Y. Furukawa, G. Sazaki, T. Uchida, N. Watanabe, Hokkaido University Press, Sapporo, Japan, 2011). - 9784832903616 ; , s. 79-88
-
Konferensbidrag (refereegranskat)abstract
- The development and application of a new molecular beam setup for studies of gas-ice interactions at pressures in the 0.001 mbar range is described. Direct simulation Monte Carlo calculations have been applied to optimize the experimental design with respect to gas transmission through the high pressure zone outside the ice surface and pressure along the surface plane. In a first application of the new setup elastic helium scattering and light scattering have been used to study the formation of water, methanol and water-methanol ice on a graphite surface in the temperature range from 180 to 215 K. Water does not wet the graphite surface under these conditions, in agreement with earlier results obtained below 180 K, while methanol readily forms a thin layer on the surface. Methanol enhances water ice nucleation and influences the properties of the ice formed, but does not have a major impact on ice growth or evaporation once a thick water-containing ice layer has formed. The potential for further development of the molecular beam technique are discussed.
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| 13. |
- Kong, Xiangrui, et al.
(författare)
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Ice Formation via Deposition Mode Nucleation on Bare and Alcohol-Covered Graphite Surfaces
- 2012
-
Ingår i: Journal of Physical Chemistry C. - : American Chemical Society (ACS). - 1932-7447 .- 1932-7455. ; 116:16, s. 8964-8974
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Tidskriftsartikel (refereegranskat)abstract
- Deposition of water on aerosol particles contributes to ice cloud formation in the atmosphere with implications for the water cycle and climate on Earth. The heterogeneous ice nucleation process is influenced by physicochemical properties of the substrate, but the mechanisms remain incompletely understood. Here, we report on ice formation on bare and alcohol-covered graphite at temperatures from 175 to 213 K, probed by elastic helium and light scattering. Water has a low wettability on bare and butanol-covered graphite resulting in the growth of rough ice surfaces. In contrast, preadsorbed methanol provides hydrophilic surface sites and results in the formation of smooth crystalline ice; an effect that is pronounced also for submonolayer methanol coverages. The alcohols primarily reside at the ice surface and at the ice–graphite interface with a minor fraction being incorporated into the growing ice structures. Methanol has no observable effect on gas/solid water vapor exchange, whereas butanol acts as a transport barrier for water resulting in a reduction in ice evaporation rate at 185 K. Implications for the description of deposition mode freezing are discussed.
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| 14. |
- Olofson, K. Frans G., 1976, et al.
(författare)
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Rydberg Matter clusters of alkali metal atoms: the link between meteoritic matter, polar mesosphere summer echoes (PMSE), sporadic sodium layers, polar mesospheric clouds (PMCs, NLCs), and ion chemistry in the mesosphere
- 2010
-
Ingår i: arXiv:1002.1570v1[astro-ph.EP].
-
Tidskriftsartikel (övrigt vetenskapligt/konstnärligt)abstract
- There exists a material which links together the influx of meteoritic matter from interplanetary space, the polar mesosphere summer echoes (PMSE), the sporadic sodium layers, the polar mesospheric clouds (PMCs, NLCs), and the observed ion chemistry in the mesosphere. The evidence in these research fields is here analyzed and found to agree well with the properties of Rydberg Matter (RM). This material has been studied with numerous methods in the laboratory. Alkali atoms, mainly Na, reach the mesosphere in the form of interplanetary (meteoritic, cometary) dust. The planar RM clusters NaN usually contain N = 19, 37 or 61 atoms, and have the density of air at 90 km altitude where they float. The diameters of the clusters are 10-100 nm from laboratory high precision radio frequency spectroscopic studies. Such experiments show that RM clusters interact strongly with radar frequencies: this explains the radio frequency heating and reflection studies of PMSE layers. The clusters give circular polarized scattering and depolarized scattering of visible light in laboratory experiments: similar effects are observed in light scattering and lidar studies of NLCs. The clusters give the low temperature in the mesosphere by efficient selective radiation at long wavelengths, which is observed in RF emission experiments. The lowest possible stable temperature of the mesopause is calculated for the first time to be 121 K in agreement with measurements, based on the strong optical activity at long wavelengths in RM. Sporadic sodium layers are explained in a unique way as due to shockwaves in the RM layers. Due to the high electronic excitation energy in RM clusters, they induce efficient reactions forming ions of all atoms and molecules in the atmosphere thus providing condensation nuclei for water vapour. This finally gives the visible part of the PMC structure. Especially the sporadic sodium layers and the PMSE give direct evidence for the existence of RM layers at the mesopause. The present contribution fills the gap between and partially replaces the separate theories used to describe the various aspects of these intriguing phenomena.
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| 15. |
- Romero Lejonthun, Liza, 1973, et al.
(författare)
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Interactions of N2O5 and Related Nitrogen Oxides with Ice Surfaces: Desorption Kinetics and Collision Dynamics
- 2014
-
Ingår i: Journal of Physical Chemistry B. - : American Chemical Society (ACS). - 1520-6106 .- 1520-5207. ; 118:47, s. 13427-13434
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Tidskriftsartikel (refereegranskat)abstract
- The detailed interactions of nitrogen oxides with ice are of fundamental interest and relevance for chemistry in cold regions of the atmosphere. Here, the interactions of NO, NO2, N2O4, and N2O5 with ice surfaces at temperatures between 93 and 180 K are investigated with molecular beam techniques. Surface collisions are observed to result in efficient transfer of kinetic energy and trapping of molecules on the ice surfaces. NO and NO2 rapidly desorb from pure ice with upper bounds for the surface binding energies of 0.16 +/- 0.02 and 0.26 +/- 0.03 eV, respectively. Above 150 K, N2O4 desorption follows first-order kinetics and is well described by the Arrhenius parameters E-a = 0.39 +/- 0.04 eV and A = 10((15.41.2)) s(1), while a stable N2O4 adlayer is formed at lower temperatures. A fraction of incoming N2O5 reacts to form HNO3 on the ice surface. The N2O5 desorption rates are substantially lower on pure water ice (Arrhenius parameters: Ea = 0.36 +/- 0.02 eV; A = 10(15.3 +/- 0.7) s(-1)) than on HNO3-covered ice (Ea = 0.24 +/- 0.02 eV; A = 10(11.5 +/- 0.7) s(-1)). The N2O5 desorption kinetics also sensitively depend on the sub-monolayer coverage of HNO3, with a minimum in N2O5 desorption rate at a low but finite coverage of HNO3. The studies show that none of the systems with resolvable desorption kinetics undergo ordinary desorption from ice, and instead desorption likely involves two or more surface states, with additional complexity added by coadsorbed molecules.
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| 16. |
- Ryding, Mauritz Johan, 1981, et al.
(författare)
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Isotope exchange in reactions between D2O and size-selected ionic water clusters containing pyridine, H+(pyridine)m(H2O)n
- 2011
-
Ingår i: Physical Chemistry Chemical Physics. ; 13:4, s. 1356-1367
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Tidskriftsartikel (refereegranskat)abstract
- Pyridine contg. water clusters, H+(pyridine)m(H2O)n, have been studied both exptl. by a quadrupole time-of-flight mass spectrometer and by quantum chem. calcns. In the expts., H+(pyridine)m(H2O)n with m = 1-4 and n = 0-80 are obsd. For the cluster distributions obsd., there are no magic nos., neither in the abundance spectra, nor in the evapn. spectra from size selected clusters. Expts. with size-selected clusters H+(pyridine)m(H2O)n, with m = 0-3, reacting with D2O at a center-of-mass energy of 0.1 eV were also performed. The cross-sections for H/D isotope exchange depend mainly on the no. of water mols. in the cluster and not on the no. of pyridine mols. Clusters having only one pyridine mol. undergo D2O/H2O ligand exchange, while H+(pyridine)m(H2O)n, with m = 2, 3, exhibit significant H/D scrambling. These results are rationalized by quantum chem. calcns. (B3LYP and MP2) for H+(pyridine)1(H2O)n and H+(pyridine)2(H2O)n, with n = 1-6. In clusters contg. one pyridine, the water mols. form an interconnected network of hydrogen bonds assocd. with the pyridinium ion via a single hydrogen bond. For clusters contg. two pyridines, the two pyridine mols. are completely sepd. by the water mols., with each pyridine being positioned diametrically opposite within the cluster. In agreement with exptl. observations, these calcns. suggest a "see-saw mechanism" for pendular proton transfer between the two pyridines in H+(pyridine)2(H2O)n clusters. [on SciFinder (R)]
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| 17. |
- Ryding, Mauritz Johan, 1981, et al.
(författare)
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Proton mobility in water clusters
- 2012
-
Ingår i: European Journal of Mass Spectrometry. - : SAGE Publications. - 1469-0667 .- 1751-6838. ; 18:2, s. 215-222
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Tidskriftsartikel (refereegranskat)abstract
- Proton mobility in water occurs quickly according to the so-called Grotthuss mechanism. This process and its elementary reaction steps can be studied in great detail by applying suitable mass spectrometric methods to ionic water clusters. Careful choice of suitable core ions in combination with analysis of cluster size trends in hydrogen/deuterium isotope exchange rates allows for detailed insights into fascinating dynamic systems. Analysis of the experiments has been promoted by extensive and systematic quantum chemical model calculations. Detailed low-energy mechanistic pathways for efficient water rearrangement and proton transfer steps, in particular cases along short preformed "wires" of hydrogen bonds, have been identified in consistency with experimental findings.
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| 18. |
- Ryding, Mauritz Johan, 1981, et al.
(författare)
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Reactions of H+(pyridine)m(H2O)n and H+(NH3)1(pyridine)m(H2O)n with NH3: experiments and kinetic modelling
- 2012
-
Ingår i: Atmospheric Chemistry and Physics. - : Copernicus GmbH. - 1680-7316 .- 1680-7324. ; 12, s. 2809-2822
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Tidskriftsartikel (refereegranskat)abstract
- Reactions between pyridine containing water cluster ions, H+(pyridine)1(H2O)n, H+(pyridine)2(H2O)n and H+(NH3)1(pyridine)1(H2O)n (n up to 15) with NH3 have been studied experimentally using a quadrupole time-of-flight mass spectrometer. The product ions in the reaction between H+(pyridine)m(H2O)n (m = 1 to 2) and NH3 have been determined for the first time. It is found that the reaction mainly leads to cluster ions of the form H+(NH3)1(pyridine)m(H2O)n-x, with x = 1 or 2 depending on the initial size of the reacting cluster ion. For a given number of water molecules (from 5 to 15) in the cluster ion, rate coefficients are found to be slightly lower than those for protonated pure water clusters reacting with ammonia. The rate coefficients obtained from this study are used in a kinetic cluster ion model under tropospheric conditions. The disagreement between ambient ground level measurements and previous models are discussed in relation to the results from our model and future experimental directions are suggested.
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| 19. |
- Salo, Kent, 1967, et al.
(författare)
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Aerosol volatility and enthalpy of sublimation of carboxylic acids.
- 2010
-
Ingår i: The journal of physical chemistry. A. - : American Chemical Society (ACS). - 1520-5215 .- 1089-5639. ; 114:13, s. 4586-94
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Tidskriftsartikel (refereegranskat)abstract
- The enthalpy of sublimation has been determined for nine carboxylic acids, two cyclic (pinonic and pinic acid) and seven straight-chain dicarboxylic acids (C(4) to C(10)). The enthalpy of sublimation was determined from volatility measurements of nano aerosol particles using a volatility tandem differential mobility analyzer (VTDMA) set-up. Compared to the previous use of a VTDMA, this novel method gives enthalpy of sublimation determined over an extended temperature range (DeltaT approximately 40 K). The determined enthalpy of sublimation for the straight-chain dicarboxylic acids ranged from 96 to 161 kJ mol(-1), and the calculated vapor pressures at 298 K are in the range of 10(-6)-10(-3) Pa. These values indicate that dicarboxylic acids can take part in gas-to-particle partitioning at ambient conditions and may contribute to atmospheric nucleation, even though homogeneous nucleation is unlikely. To obtain consistent results, some experimental complications in producing nanosized crystalline aerosol particles were addressed. It was demonstrated that pinonic acid "used as received" needed a further purification step before being suspended as a nanoparticle aerosol. Furthermore, it was noted from distinct differences in thermal properties that aerosols generated from pimelic acid solutions gave two types of particles. These two types were attributed to crystalline and amorphous configurations, and based on measured thermal properties, the enthalpy of vaporization was 127 kJ mol(-1) and that of sublimation was 161 kJ mol(-1). This paper describes a new method that is complementary to other similar methods and provides an extension of existing experimental data on physical properties of atmospherically relevant compounds.
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| 20. |
- Salo, Kent, 1967, et al.
(författare)
-
Thermal characterization of aminium nitrate nanoparticles.
- 2011
-
Ingår i: The journal of physical chemistry. A. - : American Chemical Society (ACS). - 1520-5215 .- 1089-5639. ; 115:42, s. 11671-7
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Tidskriftsartikel (refereegranskat)abstract
- Amines are widely used and originate from both anthropogenic and natural sources. Recently, there is, in addition, a raised concern about emissions of small amines formed as degradation products of the more complex amines used in CO(2) capture and storage systems. Amines are bases and can readily contribute to aerosol mass and number concentration via acid-base reactions but are also subject to gas phase oxidation forming secondary organic aerosols. To provide more insight into the atmospheric fate of the amines, this paper addresses the volatility properties of aminium nitrates suggested to be produced in the atmosphere from acid-base reactions of amines with nitric acid. The enthalpy of vaporization has been determined for the aminium nitrates of mono-, di-, trimethylamine, ethylamine, and monoethanolamine. The enthalpy of vaporization was determined from volatility measurements of laboratory generated aerosol nanoparticles using a volatility tandem differential mobility analyzer set up. The determined enthalpy of vaporization for aminium nitrates range from 54 up to 74 kJ mol(-1), and the calculated vapor pressures at 298 K are around 10(-4) Pa. These values indicate that aminium nitrates can take part in gas-to-particle partitioning at ambient conditions and have the potential to nucleate under high NO(x) conditions, e.g., in combustion plumes.
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| 21. |
- Thomson, Erik S, et al.
(författare)
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Collision Dynamics and Solvation of Water Molecules in a Liquid Methanol Film
- 2011
-
Ingår i: Journal of Physical Chemistry Letters. - : American Chemical Society (ACS). - 1948-7185. ; 2:17, s. 2174-2178
-
Tidskriftsartikel (refereegranskat)abstract
- Environmental molecular beam experiments are used to examine water interactions with liquid methanol films at temperatures from 170 to 190 K. We find that water molecules with 0.32 eV incident kinetic energy are efficiently trapped by the liquid methanol. The scattering process is characterized by an efficient loss of energy to surface modes with a minor component of the incident beam that is inelastically scattered. Thermal desorption of water molecules has a well characterized Arrhenius form with an activation energy of 0.47 ± 0.11 eV and pre-exponential factor of 4.6 × 10^(15±3) s^(–1). We also observe a temperature-dependent incorporation of incident water into the methanol layer. The implication for fundamental studies and environmental applications is that even an alcohol as simple as methanol can exhibit complex and temperature-dependent surfactant behavior.
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| 22. |
- Zatula, Alexey, et al.
(författare)
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Proton mobility and stability of water clusters containing the bisulfate anion, HSO4-(H2O)n
- 2011
-
Ingår i: Physical Chemistry Chemical Physics. - : Royal Society of Chemistry (RSC). - 1463-9076 .- 1463-9084. ; 13:29, s. 13287-13294
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Tidskriftsartikel (refereegranskat)abstract
- Bisulfate water clusters, HSO(4)-(H(2)O)(n), have been studied both experimentally by a quadrupole time-of-flight mass spectrometer and by quantum chemical calculations. For the cluster distributions studied, there are some possible "magic number" peaks, although the increase in abundance compared to their neighbours is small. Experiments with size-selected clusters with n = 0-25, reacting with D(2)O at a center-of-mass energy of 0.1 eV, were performed, and it was observed that the rate of hydrogen/deuterium exchange is lower for the smallest clusters (n < 8) than for the larger (n > 11), with a transition taking place in the range n = 8-11. We propose that the protonic defect of the bisulfate ion remains rather stationary unless the degree of hydration reaches a given level. In addition, it was observed that H/D scrambling becomes close to statistically randomized for the larger clusters. Insight into this size dependency was obtained by B3LYP/6-311++G(2d, 2p) calculations for HSO(4)(-)(H(2)O)(n) with n = 0-10. In agreement with experimental observations, these calculations suggest pronounced effectiveness of a "see-saw mechanism" for pendular proton transfer with increasing HSO(4)(-)(H(2)O)(n) cluster size.
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