Molecular Beam Studies of Particle-surface Interactions with Emphasis on Atmospheric Ice Particles PDF Download

Author: Patrik Andersson
Publisher:
ISBN: 9789162837068
Category : Amas particules
Languages : en
Pages : 62

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Author: Liza Romero Lejonthun
Publisher:
ISBN: 9789163356278
Category :
Languages : en
Pages : 92

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Author: Martina Suter
Publisher:
ISBN: 9789162870782
Category :
Languages : en
Pages : 34

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Author: Pao K. Wang
Publisher: Elsevier
ISBN: 0080508448
Category : Science
Languages : en
Pages : 287

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Book Description
Atmospheric ice particles play crucial roles in cloud and storm dynamics, atmospheric chemistry, climatological processes, and other atmospheric processes. Ice Microdynamics introduces the elementary physics and dynamics of atmospheric ice particles in clouds; subsequent sections explain their formation from water vapor, why ice crystal shape and concentration in cirrus clouds influence the heating of air, and describe how ice crystals cleanse the atmosphere by scavenging aerosol particles. Pao Wang's lucid writing style will appeal to atmospheric scientists, climatologists, and meteorologists with an interest in understanding the role of ice particles in the atmosphere of our planet.

Author: Russell James@Cooper
Publisher:
ISBN:
Category :
Languages : en
Pages : 0

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Author: Jingsong Zhang
Publisher:
ISBN:
Category :
Languages : en
Pages : 466

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Author: J. A. Barker
Publisher:
ISBN:
Category : Surface (Physics)
Languages : en
Pages : 99

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Author: Amy Leigh Brunsvold
Publisher:
ISBN:
Category :
Languages : en
Pages : 215

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O atoms and N2 molecules in the outer atmosphere of the Earth collide with spacecraft surfaces and various gases that are released from space vehicles. The high relative velocity of the collisions promotes high reaction probability and large energy transfers, leading to materials degradation and chemiluminescent reactions, which may interfere with the mission of the vehicle. The work presented in this thesis uses sophisticated molecular beam and surface science techniques to study materials degradation and individual reactive and inelastic collisions in an effort to understand the complex chemistry and physics that are characteristic of space vehicle interactions with Earth's upper atmosphere. A new space-durable polymer, polyhedral oligomeric silsesquioxane polyimide, has been identified. When exposed to atomic oxygen, this polymer forms a protective SiO2 layer on its surface. Beam-surface scattering experiments showed that collision-induced dissociation becomes an important gas-surface process when the translational energy of the incident atom or molecule is greater than 8 eV. Experiments on the dynamics of gas-phase collisions at hyperthermal collision energies found that inelastic collisions may transfer large amounts of energy into internal degrees of freedom. The scattering dynamics of the reactive 16OC product from the 16O( 3P) + C18O → 16OC + 18O reaction were quite unexpected, with 16OC predominantly forward scattered. Experiments on the reactions of O( 3P) with H2O demonstrated the occurrence of a previously unobserved reaction pathway, O(3P) + H2O → HO2 + H, with a barrier determined to be ∼2.6 eV. These studies of hyperthermal processes with molecular beam techniques have enabled us to identify a promising new material and to understand the detailed collision dynamics in model gas-surface and gas-phase systems. In each case, the experiments have revealed new chemical or energy transfer processes that were not considered earlier. These previously unknown processes reveal trends in hyperthermal collisions that will undoubtedly be critical to the planning and design of missions that put space vehicles in contact with the outer reaches of the Earth's atmosphere.

Author: Sarah Sihvonen
Publisher:
ISBN:
Category :
Languages : en
Pages :

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Aerosol particles impact the climate by serving as the seeds to form water droplets and ice to form clouds. However, these aerosol-cloud interactions are the least understood aspect of our understanding of the climate system. Mineral dust aerosol is the largest global source of ice nucleating particles. During atmospheric transport, mineral dust can be exposed to sulfuric acid, which has been shown to decrease the ice nucleation activity of these particles. Many explanations for this observation, such as chemical changes to the surface or product formation that blocks active sites, have been suggested. Our research focused on building a molecular picture of these surfaces to understand why sulfuric acid exposure reduces the ice nucleation activity of clay minerals such as kaolinite. We performed studies using X-ray diffraction and solid state NMR that investigate the changes that clay minerals undergo as a result of acid exposure. We are the first to show that the formation of a product on the surface of kaolinite was responsible for the decreased ice nucleation activity, not surface changes to the mineral itself. We continued to study aerosol-cloud interactions by using parcel models that explore the impact of ice growth surface kinetics on the competition between heterogeneous and homogeneous ice nucleation in clouds. We found that impaired growth of ice favors homogeneous freezing. The parcel models will be expanded to include our work on clay minerals to explore the impact of chemical aging of ice nuclei on overall cloud properties. We also studied the effect of acidic-processing on coal fly ash samples. Coal fly ash has been found to have a similar atmospheric impact as mineral dust, but is studied to a lesser extent. Like mineral dust, coal fly ash can serve as a source of bioavailable iron to phytoplankton in nutrient limited regions of the ocean. Fly ash has also been found to serve as an ice nucleating material. We performed aqueous sulfuric acid-treatment on fly ash samples representative of the types produced in the United States. We found that a soluble salt, gypsum (hydrated calcium sulfate), formed on three out of four samples. The most iron rich sample did not react with sulfuric acid. However, acidic-processing was shown to increase the amount of soluble iron which has implications for the biogeochemical cycle. These results also demonstrate that further work investigating these fly ash systems is warranted. In addition to our work on ice nucleation, we constructed a photoacoustic spectrometer to measure the absorbance of aerosol particles to study the optical properties of atmospheric aerosol. These measurements will aid in understanding the interactions of aerosol particles with light and the radiative balance of the planet.

Author: Kuo-Nan Liou
Publisher: Cambridge University Press
ISBN: 0521889162
Category : Science
Languages : en
Pages : 461

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Book Description
This volume outlines the fundamentals and applications of light scattering, absorption and polarization processes involving ice crystals.