Medium: Taschenbuch, Einband: Kartoniert / Broschiert, Titel: Potassium Dating of Iron Meteorites, Autor: Shankar, Nirmala, Verlag: LAP Lambert Academic Publishing, Sprache: Englisch, Rubrik: Wirtschaft // Wirtschaftsratgeber, Seiten: 252, Informationen: Paperback, Gewicht: 392 gr, Verkäufer: averdo
Luminescence Dating using single grains was a major technological advance as it provided for possibilities of dealing with heterogeneously bleached grain, with the prospect of isolating grain that were optically most bleached at the time of deposition. However at single grain level, complication due to heterogeneity in natural beta dose arises due to the fact that the entire potassium of a sediment matrix is contributed by few grains of K-feldspars with up to 14% potassium. And depending on the distance of a quartz grain from a feldspar grain the beta dose changes which leads to a range of beta doses. In this thesis, we computed this distribution of beta doses in natural samples using configuration averaging and Laplace Transform techniques. The spread in the dose distribution was explained solely with the number and positional fluctuations of feldspar grains in the sediment matrix. We then developed a new protocol for age computation using single grain that includes in it the effects of heterogeneous distribution of beta doses. Go through it and you will get new ideas to improve on it
This research involves the determination of the cosmic ray exposure ages of iron meteorites using 39K-40K-41K dating. Potassium was separated from nickel using ~ 4 mL of Chelex-100 resin and 15 mL of ammonium acetate (a mixture of equal volumes of 2 M acetic acid and 3 M aqueous ammonia) as eluent. Nickel was retained as a complex and potassium elutes out. The method is effective because of a low value for the blanks (~ 50 ng of potassium) that could be achieved. The concentration of the separated K, measured using Graphite furnace atomic absorption spectrometry (GFAAS), inductively coupled mass spectrometry (ICPMS) and isotope dilution mass spectrometry (IDMS) and will be used for the calculation of 39K-40K-41K exposure ages of iron meteorites. Potassium was successfully separated from multiple samples of 8 iron meteorites. The calculated CRE age (378 Ma) agrees for the meteorite Brownfield (355 Ma, Voshage and Feldmann, 1979) with the literature value. The literature value (645 Ma, Voshage and Feldmann, 1979) is ~3 times the value calculated (190 Ma, this work) for Picacho.
Please note that the content of this book primarily consists of articles available from Wikipedia or other free sources online. The name "organic" is historical, dating back to the 1st century.For many centuries, Western alchemists believed in vitalism, the theory that certain compounds could only be synthesized from their classical elements Earth, Water, Air and Fire by action of a "life-force" possessed only by organisms. The theory implied that these "organic" compounds were fundamentally different from the "inorganic" compounds that could be obtained from the elements by chemical manipulation. Vitalism survived for a while even after the rise of modern atomic theory and the replacement of the Aristotelian elements by those we know today. It first came under question in 1824, when Friedrich Wöhler synthesized oxalic acid, a compound known to occur only in living organisms, from cyanogen. A more decisive experiment was Wöhler''s 1828 synthesis of urea from the inorganic salts potassium cyanate and ammonium sulfate.