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[en] A series of thirteen regiospecifically chlorine-37 labeled polychlorodibenzo-p-dioxins were synthesized via the Sandmeyer reaction. Nitrochlorodibenzodioxins which were obtained by a base promoted condensation of catechols and dinitropolyhalobenzenes were reduced and converted to the diazonium salts. Chlorine-37 was introduced using cuprous chloride-37. The isotopic enrichment was in the range 75-96%. (Author)
[en] With this method the element whose isotopes are to be separated is selectively excited by laser radiation and the excited isotope is brought in contact with a reaction partner (scavenger). In order to enrich 37Cl vaporous iodine monochloride in acetylene is exposed to the radiation of a rhodamine-GG dye laser resulting in the formation of cis-1.2-iodine-chlorine-acetylene. For enrichment of a chlorine isotope resp. of 34S or 36S there is used a mixture of Cl2 and SO2, irradiated by 4200 A resp. 3500-3800 A, and the additive reaction Cl2 + SO2 → SO2Cl2. With the same mixture one of the oxygen isotopes 17O and 18O can be excited. (RW)
[de]Bei dem Verfahren wird das Element, dessen Isotopen zu trennen sind, durch Laserstrahlung selektiv angeregt und das angeregte Isotop mit einem Reaktionspartner (Scavenger) in Verbindung gebracht. Zur Anreicherung des 37Cl wird dampffoermiges Jodmonochlorid in Acetylen der Strahlung eines Rhodamin-GG-Farbstofflasers ausgesetzt, wobei Cis-1,2-Jod-Chlor-Aethylen entsteht. Zur Anreicherung eines Chlorisotops bzw. von 34S oder 36S dient das Reaktionsgemisch Cl2 und SO2 mit Bestrahlung mit 4200 A bzw. 3500-2800 A und die Additionsreaktion Cl2 + SO2 → SO2Cl2. Mit dem gleichen Gemisch kann eines der Sauerstoffisotope 17O und 18O angeregt werden. (RW)
[en] Highlights: • The vibronic and cation spectra of 4-chlorostyrene are recorded. • The electronic excitation and ionization energies are precisely determined. • The spectra show a frequency shift for the isotopologues of 4-chlorostyrene. The first electronic excitation and adiabatic ionization energies of 35Cl and 37Cl 4-chlorostyrene were similar, with values of 33,977 ± 2 and 67,972 ± 5 cm−1, respectively. The general features in the obtained vibronic and cation spectra of the two isotopologues were similar. A frequency shift of 1–5 cm−1 was observed on many active vibrations of the 35Cl and 37Cl isotopologues of 4-chlorostyrene in the S1 and D0 states. This frequency difference at each mode may reflect the degree of Cl atom involvement in the overall vibration.
[en] [37Cl2]Chloramphenicol was synthesized from D-threo-2-amino-1-(4-nitrophenyl)-1,3-propanediol and ethyl[37Cl 2]dichloroacetate. Ethyl[37Cl2]dichloroacetate was prepared by chlorination with 37Cl2 of ethyldiazoacetate. 37Cl2 was obtained by reaction of a solution of Na37Cl in 30% hydrogen peroxide with fuming sulfuric acid. The overall yield (from Na37Cl) was 36%. (author)
[en] In 1986-87, when the speaker first became involved in neutrino studies at BNL, the GALLEX collaboration was forming and the Gran Sasso Underground Laboratory was being built in Italy. The key scientific questions at that time were: First, is the solar neutrino deficit claimed by BNL's Ray Davis et al. real? And, second, if yes, then what is the explanation? At that time, only two neutrino experiments were operating: Ray's chlorine-37 radiochemical neutrino detector in the U.S., and the real-time detector, Kamiokande, in Japan. Since then, several new experiments -- GALLEX, SAGE, Super-Kamiokande, SNO (Sudbury Neutrino Observatory), and KamLAND -- have obtained significant results that have greatly expanded our understanding of neutrino physics. SNO plus Super-Kamiokande solved the long-standing solar neutrino problem -- and Ray Davis won the Nobel Prize. So, people in the neutrino field say that we have left the era of discovery and have recently entered an era of precision 'New Physics,' during which we will learn about the detailed properties of neutrinos, such as their masses and their mixing angles. In this talk, the speaker will review highlights of the last 20 years and discuss a few ideas for new precision neutrino experiments, some of which will involve collaborative efforts of his group in the Chemistry Department and colleagues in the Physics Department.
[en] The saline spring 'Fonte da Pipa' (or 'Fonte da Bica', as there is some dispute on the name) is the only remaining actively exploited terrestrial salina in Portugal. The spring contains some 137 gram per liter dissolved solids of which 97% is NaCl. The salt is extracted from this brine in a two-stage process and commercialized by the 'Cooperativa Agricola dos Produtores de Sal de Rio Maior'. Despite its importance to the local economy, both as a natural resource and a tourist attraction its geochemistry has never been studied beyond one preliminary water analysis in 1936. In this study we have used stable Cl isotopes to develop a model for the origin of the saline spring. As this spring contains nearly pure NaCl it also is a perfect location to study progressive Cl isotope fractionation during evaporation processes
[en] The Christiansen-filter technique was used to measure the coherent scattering lengths b for the bound atoms of the chlorine isotopes 35Cl and 37Cl. The results are b(Cl-35) = 11.70 +- 0.09 fm/atom and b(Cl-37) = 3.08 +- 0.06 fm/atom. Furthermore, the total cross section of natural chlorine for neutron energies 1.2 eV and 5.2 eV was determined by means of transmission measurements with rotating resonance detectors. From these data the spin state scattering lengths a+(J = 2) and a-(J = 1) were obtained for the free nuclei of the isotopes. The derived values of the spin- and isotopically incoherent scattering cross section at 'zero energy' are well consistent with previously published resonance data. The present results combined with the resonance parameters make possible a complete description of the interaction of slow neutrons with the chlorine nuclei. (orig.)
[de]Mit Hilfe der Christiansenfiltertechnik wurden die kohaerenten Streulaengen b fuer die gebundenen Atome der Chlorisotope 35Cl und 37Cl gemessen. Die Ergebnisse: b(Cl-35) = 11,70 +- 0,09 fm/Atom, b(Cl-37) = 3,08 +- 0,06 fm/Atom. Ferner wurde der Gesamtwirkungsquerschnitt von natuerlichem Chlor fuer die Neutronenenergien 1,2 eV und 5,2 eV mit Durchlassmessungen an Drehresonanzdetektoren bestimmt. Aus diesen Werten ergaben sich die Spinzustandsstreulaengen a+(J = 2) and a-(J = 1) fuer die freien Kerne der Isotope. Die abgeleiteten Werte fuer die spin- und isotopeninkohaerenten Streuquerschnitte und den Gesamtstreuquerschnitt bei 'Energie null' sind mit frueher veroeffentlichten Resonanzdaten gut vereinbar. Die vorliegenden Ergebnisse ermoeglichen zusammen mit den Resonanzparametern eine vollstaendige Beschreibung der Wechselwirkung zwischen langsamen Neutronen und den Chlorkernen. (orig.)
[en] The 37Cl(3He, αγ)36Cl reaction was studied at 18 MeV, using an enriched CaCl2 target. The γ rays coincident with the α particles emitted at forward angle were detected by two Ge(Li) detectors located at theta=90degree and 125degree. Forty-two levels were observed in 36Cl, essentially those seen in the (p,d) reaction. The γ-decay schemes of the two lowest lying T=2 levels of 36Cl (analogs of the first two levels of 36S, J/sup pi/=0+ and 2+, respectively) have been determined. The lowest T=2 level at E/subx/=4299.5+-1.1 keV, feeds three levels: E/subx/=1165 keV (J/sup pi/=1+, 65+-8%), E/subx/=1601 keV (J/sup pi/=1+, 28+-5%), and E/subx/=2677 keV (J/sup pi/=1+, 7+-3%). The second one at E/subx/=7564+-4 keV feeds the levels at E/subx/=1601 keV (42+-6%), E/subx/=1960 keV (J/sup pi/=2+, 40+-6%), and E/subx/=2491 keV (J/sup pi/=2+, 18+-4%). These decay schemes are compared with shell model predictions. Some other levels of 36Cl are also discussed