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Journal articles on the topic 'Ion clouds'

Author: Grafiati

Published: 4 June 2021

Last updated: 15 February 2022

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1

Tamura, M., T. Nagata, S. Sato, M. Tanaka, N. Kaifu, J. Hough, I. McLean, I. Gatley, R. Garden, and M. McCaughrean. "Magnetic Field Structure in Dark Clouds." Symposium - International Astronomical Union 115 (1987): 48–50. http://dx.doi.org/10.1017/s0074180900094808.

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The magnetic field geometry in the central regions of two dark clouds has been mapped by measuring the polarization at 2.2 μm of background stars and of stars embedded in the clouds. The observations were done with the Kyoto polarimeter on the Agematsu 1m IR telescope in December 1984 for Heiles Cloud 2 in the Taurus dark cloud complex, and on the UKIRT 3.8m in May and July 1985 for the ρ Ophiuchus dark cloud core. The main results are: i)Most of the stars in both regions show polarization and their maxima are 2.7% in Heiles Cloud 2 and 7.6% in ρ Oph, respectively. There are similar positive relations between polarization degree and extinct ion Av's.ii)The distribution of position angles for Heiles Cloud 2 shows a single mode at about 50° and that for ρ Oph shows a bimode, at about 50° and 150°.iii)The magnetic fields, as delineated by the infrared polarization, appear perpendicular to the flattened elongations of the molecular clouds.

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2

Baum, Carl E. "Motion of Ion Clouds in Air." Electromagnetics 7, no. 3-4 (January 1987): 253–65. http://dx.doi.org/10.1080/02726348708908185.

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3

Smith, David. "The ion chemistry of interstellar clouds." Chemical Reviews 92, no. 7 (November 1992): 1473–85. http://dx.doi.org/10.1021/cr00015a001.

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4

Nikolic, S. "HCO+ in dark molecular clouds." Serbian Astronomical Journal, no. 175 (2007): 1–6. http://dx.doi.org/10.2298/saj0775001n.

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Formyl ion is one of the most important molecules, and primary molecular ion to be found in molecular clouds. This paper reviews chemical pathways of formation and destruction of the molecule, as well as its use as a tool in the study of dark molecular clouds.

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5

Zhou, Limin, and Brian A. Tinsley. "Global Circuit Model with Clouds." Journal of the Atmospheric Sciences 67, no. 4 (April 1, 2010): 1143–56. http://dx.doi.org/10.1175/2009jas3208.1.

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Abstract Cloud data from the International Satellite Cloud Climatology Project (ISCCP) database have been introduced into the global circuit model developed by Tinsley and Zhou. Using the cloud-top pressure data and cloud type information, the authors have estimated the cloud thickness for each type of cloud. A treatment of the ion pair concentration in the cloud layer that depends on the radii and concentration of the cloud droplets is used to evaluate the reduction of conductivity in the cloud layer. The conductivities within typical clouds are found to be in the range of 2%–5% of that of cloud-free air at the same altitude, for the range of altitudes for typical low clouds to typical high clouds. The global circuit model was used to determine the increase in columnar resistance of each grid element location for various months in years of high and low volcanic and solar activity, taking into account the observed fractional cloud cover for different cloud types and thickness in each location. For a single 5° × 5° grid element in the Indian Ocean, for example, with the observed fractional cloud cover amounts for low, middle, and high clouds each near 20%, the ionosphere-to-surface column resistance increased by about 10%. (For 100%, fraction—that is, uniformly overcast conditions—for each of the cloud types, the increase depends on the cloud height and thickness and is about a factor of 10 for each of the lower-level clouds in this example and a factor of 2 for the cirrus cloud.) It was found that treating clouds, in the fraction of each grid element in which they were present, as having zero conductivity made very little difference to the results. The increase in global total resistance for the global ensemble of columns in the ionosphere–earth return path in the global circuit was about 10%, applicable to the several solar and volcanic activity conditions, but this is probably an upper limit, in light of the unavailability of data on subkilometer breaks in cloud cover.

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6

Zhou, Xiaoyu, Xinwei Liu, Wenbo Cao, Xiao Wang, Ming Li, Haoxue Qiao, and Zheng Ouyang. "Study of In-Trap Ion Clouds by Ion Trajectory Simulations." Journal of The American Society for Mass Spectrometry 29, no. 2 (October 17, 2017): 223–29. http://dx.doi.org/10.1007/s13361-017-1814-9.

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7

Høymork, S. H., M. Yamauchi, Y. Ebihara, Y. Narita, O. Norberg, and D. Winningham. "Dense ion clouds of 0.1 − 2 keV ions inside the CPS-region observed by Astrid-2." Annales Geophysicae 19, no. 6 (June 30, 2001): 621–31. http://dx.doi.org/10.5194/angeo-19-621-2001.

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Abstract. Data from the Astrid-2 satellite taken between April and July 1999 show several examples of dense ion clouds in the 0.1–2 keV energy range inside the inner mag-netosphere, both in the northern and southern hemispheres. These inner magnetospheric ion clouds are found predomi-nantly in the early morning sector, suggesting that they could have originated from substorm-related ion injections on the night side. However, their location and density show no cor-relation with Kp, and their energy-latitude dispersion is not easily reproduced by a simple particle drift model. There-fore, these ion clouds are not necessarily caused by substorm-related ion injections. Alternative explanations for the ion clouds are the direct solar wind injections and up-welling ions from the other hemisphere. These explanations do not, however, account for all of the observations.Key words. Magnetospheric physics (energetic particles, trapped; magnetospheric configuration and dynamics; storm and substorms)

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8

Siemers, I., R. Blatt, Th Sauter, and W. Neuhauser. "Dynamics of ion clouds in Paul traps." Physical Review A 38, no. 10 (November 1, 1988): 5121–28. http://dx.doi.org/10.1103/physreva.38.5121.

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9

Gnat, Orly, Amiel Sternberg, and Christopher F. McKee. "METAL-ION ABSORPTION IN CONDUCTIVELY EVAPORATING CLOUDS." Astrophysical Journal 718, no. 2 (July 14, 2010): 1315–31. http://dx.doi.org/10.1088/0004-637x/718/2/1315.

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10

Cohen, R. H., A. Friedman, M. Kireeff Covo, S. M. Lund, A. W. Molvik, F. M. Bieniosek, P. A. Seidl, J. L. Vay, P. Stoltz, and S. Veitzer. "Simulating electron clouds in heavy-ion accelerators." Physics of Plasmas 12, no. 5 (May 2005): 056708. http://dx.doi.org/10.1063/1.1882292.

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11

Lambert, D. L., and A. C. Danks. "On the CH(+) ion in diffuse interstellar clouds." Astrophysical Journal 303 (April 1986): 401. http://dx.doi.org/10.1086/164085.

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12

SMITH, D. "ChemInform Abstract: The Ion Chemistry of Interstellar Clouds." ChemInform 24, no. 22 (August 20, 2010): no. http://dx.doi.org/10.1002/chin.199322341.

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13

Werth, G. "High-resolution microwave spectroscopy on trapped ion clouds." Applied Physics B Lasers and Optics 59, no. 3 (September 1994): 257–63. http://dx.doi.org/10.1007/bf01081394.

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14

Mohnen, Volker A., and Richard J. Vong. "A climatology of cloud chemistry for the eastern United States derived from the mountain cloud chemistry project." Environmental Reviews 1, no. 1 (January 1, 1993): 38–54. http://dx.doi.org/10.1139/a93-005.

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The chemical composition of clouds collected in the eastern United States has been intensely monitored over a 4-year period as part of the Mountain Cloud Chemistry Project. On the basis of these measurements we prepared a climatology for cloud chemistry, using simple statistical analyses tools and incorporating meteorological and cloud physical and chemical information. Five mountain stations have been established for cloud collection covering the northern and southern Appalachian Mountain range: Whiteface Mountain, New York; Mount Moosilauke, New Hampshire; Shenandoah Mountain, Virginia; Whitetop Mountain, Virginia; and Mount Mitchell, North Carolina. This review presents the major result from this 4-year measurement program. Cloud cover and cloud base over the eastern United States were deduced from the global real-time nephanalysis archives produced by the U.S. Air Force, augmented by local observations. Both active and passive cloud collectors were deployed to sample cloud water on an hourly basis, i.e., with sufficient time resolution to resolve synoptic scale phenomena. Chemical analysis of cloud water was performed by a central analytical laboratory with occasional on-site analysis to satisfy quality control procedures. Reliable methods now exist for collecting cloud-water samples in sufficient quantities for detailed chemical analysis. The chemical composition of cloud water varied significantly between sites. However, the differences in cloud-water ion concentration do not necessarily establish a geographic gradient between the sites but rather reflect differences in air-mass trajectories associated with the synoptic air-flow pattern and differences in sample location above cloud base. The dependence of cloud-water ion concentrations on synoptic weather type and observed differences in relative frequencies of warm sector, marine flow, and post-cold frontal synoptic types between northern and southern sites suggest that the north–south differences in cloud-water ion concentrations are related to cloud climatology at the northern sites. When air-mass trajectories shift from southwest to northwest, the concentrations of H+, SO42−, NO3− and NH4+ normally decrease but the southern sites continue to receive high concentrations under northwest flow. The height of cloud-water sample collection above cloud base was found to be an additional source of variability in both cloud-water chemistry and liquid-water content. Seasonal variation in cloud-water chemical composition was investigated at one site only. Sulfate levels were found to be significantly lower in supercooled clouds (i.e., during the 'cold' season) than in 'warm' clouds, but nitrate levels remained about the same.Key words: cloud chemistry, cloud frequency, air-mass trajectories, ANOVA.

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15

Valdivia, Valeska, Benjamin Godard, Patrick Hennebelle, Maryvonne Gerin, Pierre Lesaffre, and Jacques Le Bourlot. "Origin of CH+ in diffuse molecular clouds." Astronomy & Astrophysics 600 (April 2017): A114. http://dx.doi.org/10.1051/0004-6361/201629905.

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Context. Molecular clouds are known to be magnetised and to display a turbulent and complex structure where warm and cold phases are interwoven. The turbulent motions within molecular clouds transport molecules, and the presence of magnetic fields induces a relative velocity between neutrals and ions known as the ion-neutral drift (vd). These effects all together can influence the chemical evolution of the clouds. Aims. This paper assesses the roles of two physical phenomena which have previously been invoked to boost the production of CH+ under realistic physical conditions: the presence of warm H2 and the increased formation rate due to the ion-neutral drift. Methods. We performed ideal magnetohydrodynamical (MHD) simulations that include the heating and cooling of the multiphase interstellar medium (ISM), and where we treat dynamically the formation of the H2 molecule. In a post-processing step we compute the abundances of species at chemical equilibrium using a solver that we developed. The solver uses the physical conditions of the gas as input parameters, and can also prescribe the H2 fraction if needed. We validate our approach by showing that the H2 molecule generally has a much longer chemical evolution timescale compared to the other species. Results. We show that CH+ is efficiently formed at the edge of clumps, in regions where the H2 fraction is low (0.3−30%) but nevertheless higher than its equilibrium value, and where the gas temperature is high (≳ 300 K). We show that warm and out of equilibrium H2 increases the integrated column densities of CH+ by one order of magnitude up to values still ~ 3−10 times lower than those observed in the diffuse ISM. We balance the Lorentz force with the ion-neutral drag to estimate the ion-drift velocities from our ideal MHD simulations. We find that the ion-neutral drift velocity distribution peaks around ~ 0.04 km s-1, and that high drift velocities are too rare to have a significant statistical impact on the abundances of CH+. Compared to previous works, our multiphase simulations reduce the spread in vd, and our self-consistent treatment of the ionisation leads to much reduced vd. Nevertheless, our resolution study shows that this velocity distribution is not converged: the ion-neutral drift has a higher impact on CH+ at higher resolution. On the other hand, our ideal MHD simulations do not include ambipolar diffusion, which would yield lower drift velocities. Conclusions. Within these limitations, we conclude that warm H2 is a key ingredient in the efficient formation of CH+ and that the ambipolar diffusion has very little influence on the abundance of CH+, mainly due to the small drift velocities obtained. However, we point out that small-scale processes and other non-thermal processes not included in our MHD simulation may be of crucial importance, and higher resolution studies with better controlled dissipation processes are needed.

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16

McCall, Benjamin J. "Dissociative recombination of cold and its interstellar implications." Philosophical Transactions of the Royal Society A: Mathematical, Physical and Engineering Sciences 364, no. 1848 (September 22, 2006): 2953–63. http://dx.doi.org/10.1098/rsta.2006.1876.

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plays a key role in interstellar chemistry as the initiator of ion–molecule chemistry. The amount of observed in dense interstellar clouds is consistent with expectations, but the large abundance of seen in diffuse clouds is not easily explained by simple chemical models. A crucial parameter in predicting the abundance of in diffuse clouds is the rate constant for dissociative recombination (DR) with electrons. The value of this constant has been very controversial, because different experimental techniques have yielded very different results, perhaps owing to varying degrees of rotational and vibrational excitation of the ions. If the value of this rate constant under interstellar conditions were much lower than usually assumed, the large abundance could be easily explained. In an attempt to pin down this crucial rate constant, we have performed DR measurements at the CRYRING ion storage ring in Stockholm, using a supersonic expansion ion source to produce rotationally cold ions. These measurements suggest that the DR rate constant in diffuse clouds is not much lower than usually assumed and that the abundant must be due to either a low electron fraction or a high ionization rate.

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17

Dubin, D., and T. O’Neil. "Computer simulation of ion clouds in a Penning trap." Physical Review Letters 60, no. 6 (February 1988): 511–14. http://dx.doi.org/10.1103/physrevlett.60.511.

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18

Siemers, I., R. Blatt, T. Sauter, and W. Neuhauser. "The Kinetic Energy of Ion Clouds in Paul Traps." Physica Scripta T22 (January 1, 1988): 240–42. http://dx.doi.org/10.1088/0031-8949/1988/t22/036.

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19

Milinevsky, G. P., A. I. Kashirin, Yu A. Romanovsky, H. C. Stenbaek-Nielsen, and M. C. Kelley. "Long-lived artificial ion clouds in the Earth's ionosphere." Geophysical Research Letters 20, no. 11 (June 7, 1993): 1019–22. http://dx.doi.org/10.1029/93gl01348.

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20

Edwards, C. S., P. Gill, H. A. Klein, A. P. Levick, and W. R. C. Rowley. "Laser-cooling effects in few-ion clouds of Yb+." Applied Physics B Lasers and Optics 59, no. 2 (August 1994): 179–85. http://dx.doi.org/10.1007/bf01081168.

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21

HOUDE, MARTIN, TALAYEH HEZAREH, HUA-BAI LI, and THOMAS G. PHILLIPS. "AMBIPOLAR DIFFUSION AND TURBULENT MAGNETIC FIELDS IN MOLECULAR CLOUDS." Modern Physics Letters A 26, no. 04 (February 10, 2011): 235–49. http://dx.doi.org/10.1142/s021773231103502x.

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We review the introduction and development of a novel method for the characterization of magnetic fields in star-forming regions. The technique is based on the comparison of spectral line profiles from coexistent neutral and ion molecular species commonly detected in molecular clouds, sites of star formation. Unlike other methods used to study magnetic fields in the cold interstellar medium, this ion/neutral technique is not based on spin interactions with the field. Instead, it relies on and takes advantage of the strong cyclotron coupling between the ions and magnetic fields, thus exposing what is probably the clearest observational manifestation of magnetic fields in the cold, weakly ionized gas that characterizes the interior of molecular clouds. We will show how recent development and modeling of the ensuing ion line narrowing effect leads to a determination of the ambipolar diffusion scale involving the turbulent component of magnetic fields in star-forming regions, as well as the strength of the ordered component of the magnetic field.

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22

Kudoh, Takahiro, and Shantanu Basu. "Three-dimensional MHD simulations of molecular cloud fragmentation regulated by gravity, ambipolar diffusion, and turbulence." Proceedings of the International Astronomical Union 4, S259 (November 2008): 115–16. http://dx.doi.org/10.1017/s1743921309030245.

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AbstractWe find that the star formation is accelerated by the supersonic turbulence in the magnetically dominated (subcritical) clouds. We employ a fully three-dimensional simulation to study the role of magnetic fields and ion-neutral friction in regulating gravitationally driven fragmentation of molecular clouds. The time-scale of collapsing core formation in subcritical clouds is a few ×107 years when starting with small subsonic perturbations. However, it is shortened to approximately several ×106 years by the supersonic flows in the clouds. We confirm that higher-spacial resolution simulations also show the same result.

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23

Harrison, R. Giles, and Maarten H. P. Ambaum. "Enhancement of cloud formation by droplet charging." Proceedings of the Royal Society A: Mathematical, Physical and Engineering Sciences 464, no. 2098 (May 20, 2008): 2561–73. http://dx.doi.org/10.1098/rspa.2008.0009.

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Charge affects the activation of cloud droplets by reducing the minimum supersaturation at which haze droplets begin to grow. Although the droplet charge required to enhance activation is substantial, we show that sufficient charging occurs at the edges of layer clouds because the fair-weather current in the global atmospheric electrical circuit flows through a discontinuity in conductivity. Our theory predicts that droplet neutralization will cause a transient cooling of cloud base. This hypothesis was tested during a period of extreme solar activity, when we detected transient current bursts at the surface beneath a layer of cloud. We attribute these to bursts of ion production, which would cause transient droplet neutralization in the cloud and an associated increase in droplet critical supersaturation. We observed transient decreases in downward long-wave radiation measurements coincident with the transient current bursts. As the vertical current density passing through stratiform clouds is a global phenomenon, there are many regions in which a charge enhancement effect on cloud formation can potentially occur; we find that the effect of charge-enhanced activation on surface radiation in the present-day climate could be as large as 0.1 W m −2 .

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24

Caro, Guillermo M. Muñoz. "Laboratory Simulations of Physico-chemical Processes under Interstellar Conditions." Proceedings of the International Astronomical Union 10, H16 (August 2012): 713–14. http://dx.doi.org/10.1017/s1743921314013039.

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AbstractThe accretion and desorption of gas molecules on cold dust grains play an important role in the evolution of dense clouds and circumstellar regions around YSOs. Some of the gas molecules detected in interstellar clouds were likely synthesized in icy dust grains and ejected to the gas. But in dark cloud interiors, with temperatures as low as 10–20 K, thermal desorption is negligible and a non-thermal mechanism like ice photodesorption is required. Reactions in the ice matrix are driven by energetic processing such as photon and ion irradiation. In circumstellar regions the photon flux (UV and X-rays) is expected to be significantly higher than in dense cloud interiors, icy grain mantles present in the outer parts will experience significant irradiation. The produced radicals lead to the formation of new species in the ice, some of them of prebiotic interest. Laboratory simulations of these processes are required for their understanding. The new ultra-high vacuum set-ups introduce some important improvements.

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25

Duplissy, J., M. B. Enghoff, K. L. Aplin, F. Arnold, H. Aufmhoff, M. Avngaard, U. Baltensperger, et al. "Results from the CERN pilot CLOUD experiment." Atmospheric Chemistry and Physics Discussions 9, no. 5 (September 2, 2009): 18235–70. http://dx.doi.org/10.5194/acpd-9-18235-2009.

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Abstract. During a 4-week run in October–November 2006, a pilot experiment was performed at the CERN Proton Synchrotron in preparation for the CLOUD1 experiment, whose aim is to study the possible influence of cosmic rays on clouds. The purpose of the pilot experiment was firstly to carry out exploratory measurements of the effect of ionising particle radiation on aerosol formation from trace H2SO4 vapour and secondly to provide technical input for the CLOUD design. A total of 44 nucleation bursts were produced and recorded, with formation rates of particles above the 3 nm detection threshold of between 0.1 and 100 cm−3s−1, and growth rates between 2 and 37 nm h−1. The corresponding H2SO4 concentrations were typically around 106 cm−3 or less. The experimentally-measured formation rates and H2SO4 concentrations are comparable to those found in the atmosphere, supporting the idea that sulphuric acid is involved in the nucleation of atmospheric aerosols. However, sulphuric acid alone is not able to explain the observed rapid growth rates, which suggests the presence of additional trace vapours in the aerosol chamber, whose identity is unknown. By analysing the charged fraction, a few of the aerosol bursts appear to have a contribution from ion-induced nucleation and ion-ion recombination to form neutral clusters. Some indications were also found for the accelerator beam timing and intensity to influence the aerosol particle formation rate at the highest experimental SO2 concentrations of 6 ppb, although none was found at lower concentrations. Overall, the exploratory measurements provide suggestive evidence for ion-induced nucleation or ion-ion recombination as sources of aerosol particles. However in order to quantify the conditions under which ion processes become significant, improvements are needed in controlling the experimental variables and in the reproducibility of the experiments. Finally, concerning technical aspects, the most important lessons for the CLOUD design include the stringent requirement of internal cleanliness of the aerosol chamber, as well as maintenance of extremely stable temperatures (variations below 0.1°C). 1CLOUD is an acronym of Cosmics Leaving OUtdoor Droplets.

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26

Caselli, Paola. "The Fractional Ionization in Molecular Cloud Cores." Symposium - International Astronomical Union 197 (2000): 41–50. http://dx.doi.org/10.1017/s0074180900164666.

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Ions and electrons play a key role in the chemical and dynamical evolution of interstellar clouds. Gas phase ion–molecule reactions are major chemical routes to the formation of interstellar molecules. The ionization degree determines the coupling between the magnetic field and the molecular gas through ion–neutral collisions, and thus regulates the rate of star formation. In the theoretical determination of the degree of ionization we run into several sources of uncertainty, including the poorly known cosmic ray flux and metal depletion within the cores, the penetration of UV radiation deep into regions of high visual extinction due to cloud inhomogeneities, and the ionization rate increase in the proximity of young stellar objects which may be strong X–ray emitters. Observational estimates of electron (or ion) fractions x(e) (≡ n(e)/n(H2), where n(e) and n(H2) are the electron and molecular hydrogen number densities, respectively) in dense cloud cores are thus of considerable interest. In this paper, I will review recent improvements in the estimates of the ion fraction in dense cores and point out the difficulties in determining x(e).

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27

Removille, S., R. Dubessy, Q. Glorieux, S. Guibal, T. Coudreau, L. Guidoni, and J. P. Likforman. "Photoionisation loading of large Sr+ ion clouds with ultrafast pulses." Applied Physics B 97, no. 1 (August 8, 2009): 47–52. http://dx.doi.org/10.1007/s00340-009-3686-6.

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28

Dieckmann, M. E. "The formation of relativistic plasma structures and their potential role in the generation of cosmic ray electrons." Nonlinear Processes in Geophysics 15, no. 6 (November 3, 2008): 831–46. http://dx.doi.org/10.5194/npg-15-831-2008.

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Abstract. Recent particle-in-cell (PIC) simulation studies have addressed particle acceleration and magnetic field generation in relativistic astrophysical flows by plasma phase space structures. We discuss the astrophysical environments such as the jets of compact objects, and we give an overview of the global PIC simulations of shocks. These reveal several types of phase space structures, which are relevant for the energy dissipation. These structures are typically coupled in shocks, but we choose to consider them here in an isolated form. Three structures are reviewed. (1) Simulations of interpenetrating or colliding plasma clouds can trigger filamentation instabilities, while simulations of thermally anisotropic plasmas observe the Weibel instability. Both transform a spatially uniform plasma into current filaments. These filament structures cause the growth of the magnetic fields. (2) The development of a modified two-stream instability is discussed. It saturates first by the formation of electron phase space holes. The relativistic electron clouds modulate the ion beam and a secondary, spatially localized electrostatic instability grows, which saturates by forming a relativistic ion phase space hole. It accelerates electrons to ultra-relativistic speeds. (3) A simulation is also revised, in which two clouds of an electron-ion plasma collide at the speed 0.9c. The inequal densities of both clouds and a magnetic field that is oblique to the collision velocity vector result in waves with a mixed electrostatic and electromagnetic polarity. The waves give rise to growing corkscrew distributions in the electrons and ions that establish an equipartition between the electron, the ion and the magnetic energy. The filament-, phase space hole- and corkscrew structures are discussed with respect to electron acceleration and magnetic field generation.

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29

Imajo, Hidetsuka, Kazuhiro Hayasaka, Ryuzo Ohmukai, Utako Tanaka, Masayoshi Watanabe, and Shinji Urabe. "Spatial separation of ion clouds between sympathetically laser-cooledCd+-ion isotopes in a Penning trap." Physical Review A 55, no. 2 (February 1, 1997): 1276–80. http://dx.doi.org/10.1103/physreva.55.1276.

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30

Kirkby, Jasper, Jonathan Duplissy, Kamalika Sengupta, Carla Frege, Hamish Gordon, Christina Williamson, Martin Heinritzi, et al. "Ion-induced nucleation of pure biogenic particles." Nature 533, no. 7604 (May 25, 2016): 521–26. http://dx.doi.org/10.1038/nature17953.

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Abstract Atmospheric aerosols and their effect on clouds are thought to be important for anthropogenic radiative forcing of the climate, yet remain poorly understood1. Globally, around half of cloud condensation nuclei originate from nucleation of atmospheric vapours2. It is thought that sulfuric acid is essential to initiate most particle formation in the atmosphere3,4, and that ions have a relatively minor role5. Some laboratory studies, however, have reported organic particle formation without the intentional addition of sulfuric acid, although contamination could not be excluded6,7. Here we present evidence for the formation of aerosol particles from highly oxidized biogenic vapours in the absence of sulfuric acid in a large chamber under atmospheric conditions. The highly oxygenated molecules (HOMs) are produced by ozonolysis of α-pinene. We find that ions from Galactic cosmic rays increase the nucleation rate by one to two orders of magnitude compared with neutral nucleation. Our experimental findings are supported by quantum chemical calculations of the cluster binding energies of representative HOMs. Ion-induced nucleation of pure organic particles constitutes a potentially widespread source of aerosol particles in terrestrial environments with low sulfuric acid pollution.

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Dremin, Igor M. "Positronia’ Clouds in Universe." Universe 7, no. 2 (February 12, 2021): 42. http://dx.doi.org/10.3390/universe7020042.

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The intense emission of 511 keV photons from the Galactic center and within terrestrial thunderstorms is attributed to the formation of parapositronia clouds. Unbound electron–positron pairs and positronia can be created by strong electromagnetic fields produced in interactions of electrically charged objects, in particular, in collisions of heavy nuclei. Kinematics of this process favors abundant creation of the unbound electron–positron pairs with very small masses and the confined parapositronia states which decay directly to two 511 keV quanta. Therefore, we propose to consider interactions of electromagnetic fields of colliding heavy ions as a source of low-mass pairs which can transform to 511 keV quanta. Intensity of their creation is enlarged by the factor Z4 (Z is the electric charge of a heavy ion) compared to protons with Z = 1. These processes are especially important at very high energies of nuclear collisions because their cross sections increase proportionally to cube of the logarithm of energy and can even exceed the cross sections of strong interactions which may not increase faster than the squared logarithm of energy. Moreover, production of extremely low-mass e+e−-pairs in ultraperipheral nuclear collisions is strongly enhanced due to the Sommerfeld-Gamow-Sakharov (SGS) factor which accounts for mutual Coulomb attraction of non-relativistic electrons to positrons in case of low pair-masses. This attraction may lead to their annihilation and, therefore, to the increased intensity of 511 keV photons. It is proposed to confront the obtained results to forthcoming experimental data at NICA collider.

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32

Cramer, N. F., and S. V. Vladimirov. "Alfvén Waves in Dusty Interstellar Clouds." Publications of the Astronomical Society of Australia 14, no. 2 (1997): 170–78. http://dx.doi.org/10.1071/as97170.

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AbstractDust particles in a plasma can be higWy charged, and can carry a proportion of the negative charge of the plasma. Even if this proportion is quite small, as in interstellar dusty clouds, it can have a large effect on hydromagnetic Alfvén waves propagating at frequencies well below the ion–cyclotron frequency. In particular, the right-hand circularly polarised mode experiences a cutoff due to the presence of the dust. We generalise previous work on Alfvén waves in dusty interstellar plasmas by considering the general dispersion relation for waves propagating at an arbitrary angle with respect to the magnetic field. Wave energy propagating at oblique angles to the magnetic field in an increasing density gradient can be very efficiently damped by the Alfvén resonance absorption process in a dusty plasma, and we consider this damping mechanism for waves in interstellar clouds.

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Ziurys, L. M., and B. E. Turner. "New Interstellar Molecular Detections: Implications for “Shock Chemistry”." Symposium - International Astronomical Union 120 (1987): 289–92. http://dx.doi.org/10.1017/s0074180900154166.

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Several new interstellar species have recently been detected in the molecular gas, including rotationally-excited CH, vibrationally-excited HCN, and a new molecular ion, HCNH+. These detections have raised some interesting questions concerning the relative importance of “shock” or “high temperature” chemistry vs. ion-molecule reactions in the synthesis of interstellar molecules in dense clouds.

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34

Lim, Y. B., Y. Tan, M. J. Perri, S. P. Seitzinger, and B. J. Turpin. "Aqueous chemistry and its role in secondary organic aerosol (SOA) formation." Atmospheric Chemistry and Physics Discussions 10, no. 6 (June 9, 2010): 14161–207. http://dx.doi.org/10.5194/acpd-10-14161-2010.

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Abstract. There is a growing understanding that secondary organic aerosol (SOA) can form through reactions in atmospheric waters (i.e., clouds, fogs, and aerosol water). In clouds and wet aerosols, water-soluble organic products of gas-phase photochemistry dissolve into the aqueous phase where they can react further (e.g. with OH radicals) to form low volatility products that are largely retained in the particle phase. Organic acids, oligomers and other products form via radical- and non-radical reactions, including hemiacetal formation during droplet evaporation, acid/base catalyzation, and reaction of organics with other constituents (e.g. NH4+). This paper uses kinetic modeling, experiments conducted with aqueous carbonyl solutions in the presence and absence of OH radicals, electrospray ionization Fourier transform ion cyclotron resonance mass spectrometry, and the literature to describe aqueous chemistry at cloud- and aerosol-relevant concentrations and during droplet evaporation. At least for aqueous reactions of glyoxal with OH radicals, chemical modeling can reproduce experiments conducted at cloud-relevant concentrations without including radical–radical reactions, whereas radical–radical reactions become dramatically more important at higher concentrations. We demonstrate that reactions with OH radicals tend to be faster and form more SOA than "non-radical" reactions (e.g., acid catalyzation).

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35

Yang, Tiangang, Anyang Li, Gary K. Chen, Qian Yao, Arthur G. Suits, Hua Guo, Eric R. Hudson, and Wesley C. Campbell. "Isomer-specific kinetics of the C+ + H2O reaction at the temperature of interstellar clouds." Science Advances 7, no. 2 (January 2021): eabe4080. http://dx.doi.org/10.1126/sciadv.abe4080.

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The reaction C+ + H2O → HCO+/HOC+ + H is one of the most important astrophysical sources of HOC+ ions, considered a marker for interstellar molecular clouds exposed to intense ultraviolet or x-ray radiation. Despite much study, there is no consensus on rate constants for formation of the formyl ion isomers in this reaction. This is largely due to difficulties in laboratory study of ion-molecule reactions under relevant conditions. Here, we use a novel experimental platform combining a cryogenic buffer-gas beam with an integrated, laser-cooled ion trap and high-resolution time-of-flight mass spectrometer to probe this reaction at the temperature of cold interstellar clouds. We report a reaction rate constant of k = 7.7(6) × 10−9 cm3 s−1 and a branching ratio of formation η = HOC+/HCO+ = 2.1(4). Theoretical calculations suggest that this branching ratio is due to the predominant formation of HOC+ followed by isomerization of products with internal energy over the isomerization barrier.

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36

Kiai, S. M. Sadat, M. Elahi, S. Adlparvar, N. Nemati, S. R. Shafaei, and Leila Karimi. "Investigation of Ne and He Buffer Gases Cooled Ar+Ion Clouds in a Paul Ion Trap." Mass Spectrometry Letters 6, no. 4 (December 31, 2015): 112–15. http://dx.doi.org/10.5478/msl.2015.6.4.112.

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Vladimirov, Gleb, Yury Kostyukevich, Oleg Kharybin, and Eugene Nikolaev. "Effect of ion clouds micromotion on measured signal in Fourier transform ion cyclotron resonance: Computer simulation." European Journal of Mass Spectrometry 23, no. 4 (August 2017): 162–66. http://dx.doi.org/10.1177/1469066717718837.

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38

Currell, F. J., J. Asada, and S. Ohtani. "A new model for the motion of ion clouds inside electron beam ion traps and sources." Physica Scripta T73 (January 1, 1997): 373–74. http://dx.doi.org/10.1088/0031-8949/1997/t73/123.

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39

Vay, J. L., M. A. Furman, P. A. Seidl, R. H. Cohen, A. Friedman, D. P. Grote, M. Kireeff Covo, et al. "Self-consistent simulations of heavy-ion beams interacting with electron-clouds." Nuclear Instruments and Methods in Physics Research Section A: Accelerators, Spectrometers, Detectors and Associated Equipment 577, no. 1-2 (July 2007): 65–69. http://dx.doi.org/10.1016/j.nima.2007.02.013.

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40

Sharp, W. M., D. P. Grote, R. H. Cohen, A. Friedman, J. L. Vay, P. A. Seidl, P. K. Roy, J. E. Coleman, J. Armijo, and I. Haber. "Simulating electron clouds in high-current ion accelerators with solenoid focusing." Nuclear Instruments and Methods in Physics Research Section A: Accelerators, Spectrometers, Detectors and Associated Equipment 577, no. 1-2 (July 2007): 146–49. http://dx.doi.org/10.1016/j.nima.2007.02.046.

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41

Kopp, E., P. Eberhardt, U. Herrmann, and L. G. Björn. "Positive ion composition of the high-latitude summerDregion with noctilucent clouds." Journal of Geophysical Research 90, no. D7 (1985): 13041. http://dx.doi.org/10.1029/jd090id07p13041.

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42

Sugiyama, Takuya. "Ion-recombination nucleation and growth of ice particles in noctilucent clouds." Journal of Geophysical Research 99, A3 (1994): 3915. http://dx.doi.org/10.1029/93ja02822.

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43

Milinevsky, G. P., A. I. Kashirin, Yu A. Romanovsky, H. C. Stenbaek-Nielsen, and M. C. Kelly. "Correction [to “Long-lived artificial ion clouds in the Earth's Ionosphere”]." Geophysical Research Letters 21, no. 25 (December 15, 1994): 2863. http://dx.doi.org/10.1029/94gl02553.

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44

Sultan, Peter J., Michael Mendillo, William L. Oliver, and John M. Holt. "Detection of artificially created negative ion clouds with incoherent scatter radar." Journal of Geophysical Research 97, A4 (1992): 4085. http://dx.doi.org/10.1029/91ja03025.

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45

Kazimura, Yoshihiro, Francesco Califano, Jun-ichi Sakai, Torsten Neubert, Francesco Pegoraro, and Sergei Bulanov. "Magnetic Field Generation during the Collision of Electron-Ion Plasma Clouds." Journal of the Physical Society of Japan 67, no. 4 (April 15, 1998): 1079–82. http://dx.doi.org/10.1143/jpsj.67.1079.

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46

Alexeev, Yuri, Dmitri G. Fedorov, and Alexandre A. Shvartsburg. "Effective Ion Mobility Calculations for Macromolecules by Scattering on Electron Clouds." Journal of Physical Chemistry A 118, no. 34 (August 19, 2014): 6763–72. http://dx.doi.org/10.1021/jp505012c.

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47

Schubert, M., I. Siemers, and R. Blatt. "Kinetic energy and spatial width of ion clouds in paul traps." Applied Physics B Photophysics and Laser Chemistry 51, no. 6 (December 1990): 414–17. http://dx.doi.org/10.1007/bf00329103.

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48

Imajo, H., K. Hayasaka, R. Ohmukai, M. Watanabe, and S. Urabe. "Observation of laser-cooled Be+ -ion clouds in a Penning trap." Applied Physics B Lasers and Optics 61, no. 3 (September 1995): 285–89. http://dx.doi.org/10.1007/bf01082048.

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49

Shimogawa, M., and R. H. Holzworth. "Electric field measurements in a NLC/PMSE region during the MASS/ECOMA campaign." Annales Geophysicae 27, no. 4 (April 1, 2009): 1423–30. http://dx.doi.org/10.5194/angeo-27-1423-2009.

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Abstract. We present results of electric field measurements made during the MASS rocket campaign in Andøya, Norway into noctilucent clouds (NLC) and polar mesospheric summer echoes (PMSE) on 3 August 2007. The instrument used high input-impedance preamps to measure vertical and horizontal electric fields. No large-amplitude geophysical electric fields were detected in the cloud layers, but significant levels of electric field fluctuations were measured. Within the cloud layer, the probe potentials relative to the rocket skin were driven negative by incident heavy charged aerosols. The amplitude of spikes caused by probe shadowing were also larger in the NLC/PMSE region. We describe a method for calculating positive ion conductivities using these shadowing spike amplitudes and the density of heavy charged aerosols.

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50

Zhao, Y., A. G. Hallar, and L. R. Mazzoleni. "Atmospheric organic matter in clouds: exact masses and molecular formula identification using ultrahigh resolution FT-ICR mass spectrometry." Atmospheric Chemistry and Physics Discussions 13, no. 8 (August 7, 2013): 20561–610. http://dx.doi.org/10.5194/acpd-13-20561-2013.

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Abstract. Clouds alter the composition of atmospheric aerosol by acting as a medium for interactions between gaseous and particulate phase substances. To determine the cloud water atmospheric organic matter (AOM) composition and study the cloud processing of aerosols, two samples of supercooled clouds were collected at Storm Peak Laboratory near Steamboat Spring, Colorado (3220 m a.s.l.). Approximately 3000 molecular formulas were assigned to ultrahigh resolution mass spectra of the samples after using a reverse phase extraction procedure to isolate the AOM components from the cloud water. Nitrogen containing compounds (CHNO compounds), sulfur containing compounds (CHOS and CHNOS compounds) and other oxygen containing compounds (CHO compounds) with molecular weights up to 700 Da were observed. Average oxygen-to-carbon ratios of ~0.6 indicate a slightly more oxidized composition than most water-soluble organic carbon identified in aerosol studies, which may result from aqueous oxidation in the clouds. The AOM composition indicates significant influences from biogenic secondary organic aerosol (SOA) and residential wood combustion. We observed 60% of the cloud water CHO molecular formulas to be identical to SOA samples of α-pinene, β-pinene, d-limonene, and β-caryophyllene ozonolysis. CHNO compounds had the highest number frequency and relative abundances and are associated with residential wood combustion and NOx oxidation. We observed multiple nitrogen atoms in the assigned molecular formulas for the nighttime cloud sample composite indicating the significance of nighttime emissions or NOx oxidation on the AOM composition. Several CHOS and CHNOS compounds with reduced sulfur (in addition to the commonly observed oxidized sulfur containing compounds) were also observed, however further investigation is needed to determine the origin of the reduced sulfur containing compounds. Overall, the molecular composition determined using ultrahigh resolution Fourier transform ion cyclotron resonance (FT-ICR) mass spectrometry provides an unambiguous identification of the cloud water organic composition in the Rocky Mountain area which could help to improve the understanding of aqueous phase processes.

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