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  • 1
    Electronic Resource
    Electronic Resource
    Springer
    Applied physics 3 (1974), S. 1-7 
    ISSN: 1432-0630
    Keywords: Positronium ; Molecular substances
    Source: Springer Online Journal Archives 1860-2000
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Notes: Abstract The progress of research into the behavior of the positronium in molecular substances in the last several years is reviewed. The Ps atom can be treated as a solute in a liquid. The repulsive exchange force is the dominant force which reacts against the van der Waals attractive force. One of the most useful general relationships found is the one between the pick-off quenching rate and the surface tension of the liquid. The pick-off quenching rate is found, in general, to be an additive property of the functional groups of a molecule. The quenching of theo-Ps atom by an active quenching agent in an inert solvent has been found to be primarily diffusion controlled. Some deviations from the simple Arrhenius equation have been found. For gases, more theoretical work on the collision problems of Ps with atoms or molecules is needed. For amorphous molecular solids, it is likely that the property of pick-off quenching ofo-Ps is similar to that in liquids. However, in crystalline molecular solids, the situation is quite different. A few definite cases have been found where a Ps atom does not form or exist. Further work in this area should be very interesting. The foregoing leads us to believe that positronium or positron annihilation can be useful in the study of fundamental properties of molecular liquids and solids.
    Type of Medium: Electronic Resource
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  • 2
    Electronic Resource
    Electronic Resource
    Springer
    Applied physics 16 (1978), S. 409-411 
    ISSN: 1432-0630
    Keywords: 29 ; 02 ; 71
    Source: Springer Online Journal Archives 1860-2000
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Notes: Abstract The relationship between some popularly used arbitrary parameters and the variance of the Doppler broadening spectra of positron annihilation γ-rays is discussed. The experimental results are found to agree well with the theoretically derived formulas.
    Type of Medium: Electronic Resource
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  • 3
    ISSN: 1432-0630
    Keywords: Positronium ; Diffusion
    Source: Springer Online Journal Archives 1860-2000
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Notes: Abstract The temperature effect on positronium quenching rates for p-benzoquinone and iodine in several solvents was determined. The quenching rate constantk 1 follows ak 1∝1/η relationship better than thek 1∝T/η one, predicted by ordinary theory. A simple theoretical treatment based on diffusion theory shows that the temperatureT of the solute, positronium, may not be the same as the temperature of the solvent if the positronium is not fully thermalized. This temperature is found to be about twice the room temperature for the solvents investigated. The findings further support the theory that positronium reactions are “diffusion controlled” in liquid solutions. The activation energies of all the positronium reactions studied are either negligible or less than 0.1 eV.
    Type of Medium: Electronic Resource
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  • 4
    Publication Date: 2016-03-18
    Description: Knowledge of the contribution that individual countries have made to global radiative forcing is important to the implementation of the agreement on "common but differentiated responsibilities" reached by the United Nations Framework Convention on Climate Change. Over the past three decades, China has experienced rapid economic development, accompanied by increased emission of greenhouse gases, ozone precursors and aerosols, but the magnitude of the associated radiative forcing has remained unclear. Here we use a global coupled biogeochemistry-climate model and a chemistry and transport model to quantify China's present-day contribution to global radiative forcing due to well-mixed greenhouse gases, short-lived atmospheric climate forcers and land-use-induced regional surface albedo changes. We find that China contributes 10% +/- 4% of the current global radiative forcing. China's relative contribution to the positive (warming) component of global radiative forcing, mainly induced by well-mixed greenhouse gases and black carbon aerosols, is 12% +/- 2%. Its relative contribution to the negative (cooling) component is 15% +/- 6%, dominated by the effect of sulfate and nitrate aerosols. China's strongest contributions are 0.16 +/- 0.02 watts per square metre for CO2 from fossil fuel burning, 0.13 +/- 0.05 watts per square metre for CH4, -0.11 +/- 0.05 watts per square metre for sulfate aerosols, and 0.09 +/- 0.06 watts per square metre for black carbon aerosols. China's eventual goal of improving air quality will result in changes in radiative forcing in the coming years: a reduction of sulfur dioxide emissions would drive a faster future warming, unless offset by larger reductions of radiative forcing from well-mixed greenhouse gases and black carbon.〈br /〉〈span class="detail_caption"〉Notes: 〈/span〉Li, Bengang -- Gasser, Thomas -- Ciais, Philippe -- Piao, Shilong -- Tao, Shu -- Balkanski, Yves -- Hauglustaine, Didier -- Boisier, Juan-Pablo -- Chen, Zhuo -- Huang, Mengtian -- Li, Laurent Zhaoxin -- Li, Yue -- Liu, Hongyan -- Liu, Junfeng -- Peng, Shushi -- Shen, Zehao -- Sun, Zhenzhong -- Wang, Rong -- Wang, Tao -- Yin, Guodong -- Yin, Yi -- Zeng, Hui -- Zeng, Zhenzhong -- Zhou, Feng -- England -- Nature. 2016 Mar 17;531(7594):357-61. doi: 10.1038/nature17165.〈br /〉〈span class="detail_caption"〉Author address: 〈/span〉Sino-French Institute for Earth System Science, Laboratory for Earth Surface Processes, College of Urban and Environmental Sciences, Peking University, Beijing 100871, China. ; Jiangsu Center for Collaborative Innovation in Geographical Information Resource Development and Application, Nanjing, 210023, China. ; Laboratoire des Sciences du Climat et de l'Environnement, CEA-CNRS-UVSQ, 91191 Gif-sur-Yvette, France. ; Centre International de Recherche en Environnement et Developpement, CNRS-PontsParisTech-EHESS-AgroParisTech-CIRAD, 94736 Nogent-sur-Marne, France. ; Key Laboratory of Alpine Ecology and Biodiversity, Institute of Tibetan Plateau Research, Center for Excellence in Tibetan Earth Science, Chinese Academy of Sciences, Beijing 100085, China. ; Laboratoire de Meteorologie Dynamique, CNRS, Universite Pierre et Marie Curie-Paris 6, 75252 Paris, France.〈br /〉〈span class="detail_caption"〉Record origin:〈/span〉 〈a href="http://www.ncbi.nlm.nih.gov/pubmed/26983540" target="_blank"〉PubMed〈/a〉
    Keywords: Aerosols/analysis/chemistry ; Air Pollution/*analysis ; Atmosphere/*chemistry ; Carbon Dioxide/analysis ; China ; Fossil Fuels ; *Greenhouse Effect ; Methane/analysis ; Soot/analysis ; Sulfates/analysis ; Sulfur Dioxide/analysis ; Uncertainty
    Print ISSN: 0028-0836
    Electronic ISSN: 1476-4687
    Topics: Biology , Chemistry and Pharmacology , Medicine , Natural Sciences in General , Physics
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