Rapid chemical separation

The chemical and physical form of the target or Irradiated sample must be selected so as to facilitate a rapid chemical separation. A material In the salt form, which Is easily soluble In an appropriate solvent. Is very suitable for the ejqjeriment. A rock sample which must be fused for dissolution should be powdered as finely as possible before Irradiation. 

Figure 6. Gas-flow system for rapid chemical separation of bromine to permit study of short-lived activities (212).

G. Herrmann, O. Denschlag, Rapid Chemical Separations, Annu. Rev. Nucl. Sci. 19, 1 (1969)... 

N. Trautmann, G. Herrmann, Rapid Chemical Separation Procedures, J. Radioanal. Chem. 32, 533 (1976)... 

W. W. Meinke (Ed.), Monographs on the Radiochemistry of the Elements, Subcommittee on Radiochemistry, National Academy of Sciences, National Research Council, Nuclear Science Series, NAS-NS 3001-3058, Washington, DC, 1959-1962 W, W. Meinke (Ed.), Monographs on Radiochemical Techniques, Subcommittee on Radiochemistry, National Academy of Sciences, National Research Council, Nuclear Science Series NAS-NS 3101-3120, Washington, DC, 1960-1965 I. Zvara, One Atom at a Time Chemical Studies of Transactinide Elements, in Transplutonium Elements (Eds. W. Muller, R. Lindner), North-Holland, Amsterdam, 1976 G. Herrmann, N. Trautmann, Rapid Chemical Separation Procedures, J. Radioanal. Chem. 32, 533 (1976)... 

Rapid chemical separations and radiation measurements for important radionuclides with little or no gamma-ray emission... 

Md produced in the Am( C,3n) reaction was identified by using the Automated Chromatographic Chemical Element Separator System, ACCESS, in which ammonium a-hydroxy isobutyrate (a-HIB) was used for the separation of Md (Kadkhodayan et al. 1992). The other rapid chemical separation apparatus is described in the reviews (Herrmann and Trautmann 1982 Trautmann 1995) and also in Chap. 20 of this Volume. 

Abstract In this chapter, the chemical properties of the man-made transactinide elements rutherfordium, Rf (element 104), dubnium, Db (element 105), seaborgium, Sg (element 106), bohrium, Bh (element 107), hassium, Hs (element 108), and copernicium, Cn (element 112) are reviewed, and prospects for chemical characterizations of even heavier elements are discussed. The experimental methods to perform rapid chemical separations on the time scale of seconds are presented and comments are given on the special situation with the transactmides where chemistry has to be studied with single atoms. It follows a description of theoretical predictions and selected experimental results on the chemistry of elements 104 through 108, and element 112. 

Abstract An overview over the chemical separation and characterization experiments of the four transactinide elements so far studied in liquid phases, rutherfordium (Rf), dubnium (Db), seaborgium (Sg), and hassium (Hs), is presented. Results are discussed in view of the position of these elements in the Periodic Table and of their relation to theoretical predictions. Short introductions on experimental techniques in liquid-phase chemistry, specifically automated rapid chemical separation systems, are also given. Studies of nuclear properties of transactinide nuclei by chemical isolation will be mentioned. Some perspectives for further liquid-phase chemistry on heavier elements are briefly discussed. 

Comar, D. and lePoec, C. The Use of Exchange Resins for Rapid Chemical Separation In Activation Analysis Determination of Iodine in Biological Fluids. Vienna, International Atomic Energy Agency. 1964. Preprint SM-55/79. 12 p. (CONF-641001-50). (In French). 19 5818... 

Biomolecule Separations. Advances in chemical separation techniques such as capillary zone electrophoresis (cze) and sedimentation field flow fractionation (sfff) allow for the isolation of nanogram quantities of amino acids and proteins, as weU as the characterization of large biomolecules (63—68) (see Biopolymers, analytical techniques). The two aforementioned techniques, as weU as chromatography and centrifugation, ate all based upon the differential migration of materials. Trends in the area of separations are toward the manipulation of smaller sample volumes, more rapid purification and analysis of materials, higher resolution of complex mixtures, milder conditions, and higher recovery (69). 

The first (inconclusive) work bearing on the synthesis of element 104 was published by the Dubna group in 1964. However, the crucial Dubna evidence (1969-70) for the production of element 104 by bombardment of 94PU with loNe came after the development of a sophisticated method for rapid in situ chlorination of the product atoms followed by their gas-chromatographic separation on an atom-by-atom basis. This was a heroic enterprise which combined cyclotron nuclear physics and chemical separations. As we have seen, the actinide series of elements ends with 103 Lr. The next element should be in Group 4 of the transition elements, i.e. a heavier congenor of Ti, Zr and Hf. As such it would be expected to have a chloride... 

By painstaking chemical separations, and careful study of the style and longevity of radioactivity from the resulting separates, these series were rapidly added to and only a year later more than 15 discrete radioactive substances were known, each with measured half-lives, and all arranged into four decay series from U, Th, Ac, and Ra (Rutherford 1904). 

Inductive or polar effects. These effects involve electron displacements that are transmitted along a chain of atoms without any reorganization of the formal chemical bonds in the molecule. For example, the introduction of a methyl group in a pyridine ring involves a displacement of electrons to the nitrogen atom from the methyl group. This effect falls off rapidly with separation distance. 

Zinc oxide in solid or fine particle form is kept in a reactor cavity that is subjected to irradiation from solar concentrators [92], The dissociation products are zinc (vapor) and oxygen for this first reaction AG=0 at about 2235K [91], The reactor is made of materials like inconel steel, zirconia, silicon carbide or graphite [68,89,92], The graphite is used in special designs to avoid direct contact with chemical species [68], The dissociation products are then cooled rapidly to separate zinc and oxygen, transporting the... 

The 147Sm-143Nd system was first used in cosmochemistry by Lugmair et al. (1975a), who published a precise isochron age for an Apollo 17 basalt (Fig. 8.11). The system developed rapidly thereafter. Note that the spread in 147Sm/144Nd in the mineral phases of this basalt is less than 50%, not factors of ten, several hundred, or even a few thousand, as can be seen in other systems. The fact that precise isochron ages can still be obtained is a testament to the care taken in chemical separation of samarium and neodymium and the precision of modem mass spectrometric analysis. 

In most chemical separation procedures, the goal is to selectively transfer the species of interest from one phase to another, leaving behind any unwanted species. The phase-to-phase transfer is rapid, but the procedures to place the species in the proper form for transfer to occlu are slow. The goal of rapid radiochemical separations is to speed up existing chemical procedrues or to use new, very fast chemical transformations. 

Apostolidis, C., Molinet, R., Richir, P., Ougier, M., and Mayer, K., Development and validation of a simple, rapid, and robust method for the chemical separation of uranium and plutonium, Radiochim. Acta, 83, 21-25, 1998. 

We report on a number of on-line chemical procedures which were developed for the study of short-lived fission products and products from heavy-ion interactions. These techniques combine gas-jet recoil-transport systems with I) multistage solvent extraction methods using high-speed centrifuges for rapid phase separation and II) thermochromatographic columns. The formation of volatile species between recoil atoms and reactive gases is another alternative. We have also coupled a gas-jet transport system to a mass separator equipped with a hollow cathode- or a high temperature ion source. Typical applications of these methods for studies of short-lived nuclides are described. 

Nuclear reactions producing exotic nuclei at the limits of stability are usually very non-specific. For the fast and efficient removal of typically several tens of interfering elements with several hundreds of isotopes from the nuclides selected for study mainly mass separation [Han 79, Rav 79] and rapid chemical procedures [Her 82] are applied. The use of conventional mass separators is limited to elements for which suitable ion sources are available. There exists a number of elements, such as niobium, the noble metals etc., which create problems in mass separation due to restrictions in the diffusion-, evaporation- or ionization process. Such limitations do not exist for chemical methods. Although rapid off-line chemical methods are still valuable for some applications, continuously operated chemical procedures have been advanced recently since they deliver a steady source of activity needed for measurements with low counting efficiencies and for studies of rare decay modes. The present paper presents several examples for such techniques and reports briefly actual applications of these methods for the study of exotic nuclei. 

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