Carrier isotopic

Since the carrier effect is not general for all analytes and all additives, quantitative studies using the particle-beam interface should only be carried out after a very careful choice of experimental conditions and standard(s) to be used, with isotopic-dilution methodology being advocated for the most accurate results. 

The only respect in which the hot atom chemistry of organometallic compounds has so far been applied to other fields of study is in the area of isotope enrichment. Much of this has been done for isolation of radioactive nuclides from other radioactive species for the purpose of nuclear chemical study, or for the preparation of high specific activity radioactive tracers. Some examples of these applications have been given in Table II. The most serious difficulty with preparation of carrier-free tracers by this method is that of radiolysis of the target compound, which can be severe under conditions suited to commercial isotope production, so that the radiolysis products dilute the enriched isotopes. A balance can be struck in some cases, however, between high yield and high specific activity (19, 7J),... 

Eichler and Wahl have attempted an isotopic study ( Os and Os) of the exchange reaction between Os(dipy)3 and Os(dipy)3 using a direct injection technique so that reaction times 7 x 10 sec were possible. With total osmium 10" M in aqueous sulphate media at 0 °C complete exchange was observed. The separation methods used were, (a) perchlorate precipitation (in presence of iron(II) carrier) and (6) extraction with p-toluenesulphonic acid in nitromethane, of the osmium(II) complex. A lower limit of 1 x 10 l.mole. sec was placed on the rate coefficient (0 °C, 3.0 M H2SO4). Dietrich and Wahl using the line broadening effect produced by Os(dipy)3 on the nmr spectrum of Os(dipy)3 have been able to propose a value of > 5x 10" l.mole . sec at 6 °C in D2O (0.14 M [Cr] and 5x10 M [D- ]). 

The two Mossbauer levels of Pt, 99 keV and 130 keV, are populated by either EC of Au(fi/2 = 183 days) or isomeric transition of Pt(fi/2 = 4.1 days). Only a few authors, e.g., [323, 324] reported on the use of Pt, which is produced by thermal neutron activation of " Pt via " Pt(n, y) Pt. The source used in the early measurements by Harris et al. [322, 325] was carrier-free Au diffused into platinum metal. Walcher [326] irradiated natural platinum metal with deuterons to obtain the parent nuclide Au by (d, xn) reactions. After the decay of short-lived isotopes, especially Au(fi/2 = 6.18 days), Au was extracted with ethyl acetate, and the Au/Pt source prepared by induction melting. Buym and Grodzins [323] made use of (a, xn) reactions when bombarding natural iridium with... 

Figure 8. Schematic outline of a second-generation MC-ICPMS instrument (Nu Instalments Nu Plasma), equipped with a multiple-Faraday collector block for the simultaneous measurement of up to 12 ion beams, and three electron multipliers (one operating at high-abundance sensitivity) for simultaneous low-intensity isotope measurement. This instmment uses zoom optics to obtain the required mass dispersion and peak coincidences in place of motorized detector carriers. [Used with permission of Nu Instruments Ltd.]...

Gunther D, Heimich CA (1999) Enhanced sensitivity in laser ablation-ICP mass spectrometry using helium-argon mixtures as aerosol carrier. J Anal At Spectrom 14 1363-1368 Habfast K (1998) Fractionation correction and multiple collectors in thermal ionization isotope ratio mass spectrometry. Inti J Mass Spectrom 176 133-148... 

To resolve the problem applying methods of collimated atom beams, equilibrium vapour as well as radioactive isotopes, the Hall effect and measurement of conductivity in thin layers of semiconductor-adsorbents using adsorption of atoms of silver and sodium as an example the relationship between the number of Ag-atoms adsorbed on a film of zinc oxide and the increase in concentration of current carriers in the film caused by a partial ionization of atoms in adsorbed layer were examined. 

Evaporation temperature, c Ag atoms flow intensity, isotope method, atoms s l Current carrier concentration variation rate in the film, semiconductor sensor method, Vg- 10 , electrons s Ve... 

Moskalev, Yu.I. (1961b). Influence of an isotope carrier on distribution of cerium-144, page 154 in Distribution, Biological Effects and Migration of Radioactive Isotopes, Report No. AEC-tr-7512, Lebedinskii, A. V. and Moskalev, Yu.I., Eds. (National Technical Information Service, Springfield, Virginia). 

A range of functionalized polythioethers have been developed as carriers for radio-isotopes such as "mTc, 105Rh and 188Re for diagnostic and therapeutic applications.168,169... 

The direct proof that H is present in certain centers in Ge came from the substitution of D for H, resulting in an isotopic energy shift in the optical transition lines. The main technique for unraveling the nature of these defects, which are so few in number, is high-resolution photothermal ionization spectroscopy, where IR photons from an FTIR spectrometer excite carriers from the ls-like ground state to bound excited states. Phonons are used to complete the transitions from the excited states to the nearest band edge. The transitions are then detected as a photocurrent. 

Imura and Suzuki36 have prepared labelled organotin compounds from artificial tin isotopes produced in a cyclotron. The carrier-free tin-113 radioisotope was produced by irradiating indium-115 oxide with 40-MeV protons (equation 33). 

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