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Neutrons, protons or $\alpha$ particles with energies of about 1 MeV hitting a nucleus transmit energies of the order of several up to several hundred keV with the result that chemical bonds are always broken. On the other hand, the energies transmitted by absorption of low-energy photons will not rupture chemical bo... | {
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"Header 2": "9.1 General Aspects",
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| <b>Table 9.2.</b> | Breaking of | bonds due to | internal o | conversion | of <sup>80m</sup> Br. |
|-------------------|-------------|--------------|------------|------------|-----------------------|
|-------------------|-------------|--------------|------------|------------|-----------------------|
| Compound ... | {
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"Header 2": "9.1 General Aspects",
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In gases and liquids, intramolecular bonds are only affected to a certain degree by the recoil due to a mononuclear or binuclear reaction occurring in an atom of a molecule or by the kinetic energy transmitted to an atom by an incident projectile. Molecules in gases and liquids are mobile and the intermolecular binding... | {
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"Header 2": "9.4 Gases and Liquids",
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Two possibilities may be distinguished:
- (a) The momentum transmitted is high enough to break all bonds with neighbouring atoms and the atom involved in the reaction is pushed out from its position in the lattice.
- (b) The momentum is too small for a rupture of chemical bonds, and the atom stays at its place withou... | {
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"Header 2": "9.4 Gases and Liquids",
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The background of Szilard-Chalmers reactions has already been mentioned in section 9.4. Isotopic nuclides produced by nuclear reactions can be separated by chemical methods from the target nuclides due to the chemical effects of the nuclear reactions, such as changes of the oxidation state or other changes of chemical ... | {
"Header 1": "**8.12 Nuclear Fusion** - **Thermonuclear Reactions**",
"Header 2": "**9.6 Szilard-Chalmers Reactions**",
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Chemical effects of nuclear reactions do not only cause rupture of chemical bonds, they also lead to formation of new chemical bonds, a result that may be used for preparation of labelled compounds. Recoil labelling and self-labelling both involve radiation-induced reactions and also bclong to the field of radiation ch... | {
"Header 1": "**8.12 Nuclear Fusion** - **Thermonuclear Reactions**",
"Header 2": "**9.7 Recoil Labelling and Self-Labelling**",
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In the preceding chapter chemical effects of nuclear reactions have been discussed. On the other hand, the electronic structure, in particular chemical bonds, may affect nuclear properties. However, because the binding energies of the electrons are smaller by a factor of the order of lo3 to lo6 than the binding energie... | {
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"Header 2": "**10.1 Survey**",
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As already mentioned, changes of transmutation properties are observed if electrons of the electron shell are involved in the transmutations, as in the case of electron capture *(E)* or of emission of conversion electrons (e-). The rate of both processes depends on the electron density at the nucleus. Consequently, the... | {
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"Header 2": "**10.2 Dependence of Half-lives on Chemical Bonding**",
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Mössbauer spectrometry has already been mentioned in discussing the chemical effects of nuclear reactions in solids (section 9.5).
Electrons in the inner orbitals of atoms have a finite probability of entering the nucleus, interacting with the nuclear charge distribution and thereby affecting the nuclear energy level... | {
"Header 1": "10.3 Dependence of Radiation Emission on Chemical Bonding",
"Header 2": "10.4 Mössbauer Spectrometry",
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<sup>57</sup>Co is used as Mössbauer source and iron of natural isotopic composition (2.17% <sup>57</sup>Fe) or enriched <sup>57</sup>Fe as absorber
About 70 other Mössbauer pairs have also been applied, including Mössbauer nuclides such as $^{61}$ Ni, $^{67}$ Zn, $^{83}$ Kr, $^{99}$ Tc, $^{99}$ Ru, $^{101... | {
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"Header 2": "10.4 Mössbauer Spectrometry",
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#### **Mossbauer Spectroscopy**
- R. L. Mossbauer, Kernresonanzfluoreszenz von Gammastrahlen in I9'Ir, Z. Physik *151,* 124 **(1958)**
- R. L. Mossbauer, Recoilless Nuclear Resonance Absorption, Annu. Rev. NLIC~. Sci. 12, 1 **(1962)**
- N. N. Greenwood, T. C. Gibb, Mossbauer Spectroscopy, Chapman and Hall, London, **... | {
"Header 1": "10.3 Dependence of Radiation Emission on Chemical Bonding",
"Header 2": "**Literature**",
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For the production of energy by nuclear fission the following features are decisive:
- The energy $\Delta E$ set free by fission of heavy nuclei is very high (section 8.9).
- As several neutrons are liberated by fission of heavy nuclei ( $\nu = 2-3$ , section 8.9), a chain reaction is possible if at least one of th... | {
"Header 1": "10.3 Dependence of Radiation Emission on Chemical Bonding",
"Header 2": "11.1 Energy Production by Nuclear Fission",
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$\eta = v \frac{\sigma_f}{\sigma_a}$ as a function of the neutron energy for <sup>235</sup>U and <sup>238</sup>U.
The following operation conditions are distinguished:
- Thermal neutrons ( $E_{\rm n} \leq 1~{\rm eV}$ ): Fission of <sup>235</sup>U and <sup>239</sup>Pu prevails ( $\sigma_{\rm n,f} > \sigma_{\rm n,y... | {
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"Header 2": "11.1 Energy Production by Nuclear Fission",
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For the use of nuclides as nuclear fuel, their fissionability is the most important aspect. High fission yields by thermal neutrons are obtained if the binding energy of an additional neutron is higher than the fission barrier. Fission barriers, neutron binding energies and fission cross sections are listed for some nu... | {
"Header 1": "10.3 Dependence of Radiation Emission on Chemical Bonding",
"Header 2": "11.2 Nuclear Fuel and Fuel Cycles",
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The conversion factor, given by the ratio of <sup>233</sup>U produced by reaction (11.5) to the amount of nuclides used up by
**Figure 11.5.** Nuclear reactions with $^{238}$ U ( $\sigma$ [barn] for thermal neutrons).
fission, varies between about 0.65 and 0.95. Mixtures of highly e... | {
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"Header 2": "11.2 Nuclear Fuel and Fuel Cycles",
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The route from uranium ores to uranium concentrates is summarized in Fig. 11.8. The mean concentration of U in the earth's crust is only about 0.0003%. Ores containing high percentages of U are rare. Many uranium ore deposits contain only about 0.1 to 1% U. Relatively high amounts of U are dissolved in the oceans (abou... | {
"Header 1": "10.3 Dependence of Radiation Emission on Chemical Bonding",
"Header 2": "11.3 Production of Uranium and Uranium Compounds",
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**A** great number of plutonium alloys have been investigated with respect to their possible use as nuclear fuel, but they have not found practical application.
Some properties of the ceramic fuels U02 and UC are summarized in Table 1 1.5. U02 is preferably used as nuclear fuel in all modern light-water reactors (LWR... | {
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"Header 2": "11.3 Production of Uranium and Uranium Compounds",
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| Element | Atomic number $Z$ | Absorption cross section for thermal neutrons $\sigma_a$ [barn] | Melting<br>point<br>[°C] | Thermal conductivity at $20^{\circ}\mathrm{C}$ [J cm <sup>-1</sup> s <sup>-1</sup> K <sup>-1</sup> ] | Specific heat $[J g^{-1} K^{-1}]$ | Coefficient of thermal expansion [K <sup>-1</sup> ] | ... | {
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"Header 2": "11.3 Production of Uranium and Uranium Compounds",
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11.12, 11.13, 11.14 and 11.15, respectively.
Power reactors have also been developed and installed for ship propulsion, for instance in submarines (e.g. "Nautilus", USA) or icebreakers (e.g. "Lenin", Russia).
World-wide the production of energy by nuclear power amounts to about 470 GW<sub>e</sub> (1995) and increas... | {
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The absorption cross section oa is relatively low for graph-
| | Absorption cross section for thermal neutrons $\sigma_a$ [barn] | Density at 20 °C [g cm <sup>-3</sup> ] | Melting<br>point<br>[°C] | Boiling<br>point<br>[°C] | Thermal conductivity at 20 °C [J cm <sup>-1</sup> s <sup>-1</sup> K <sup>-1</sup> ]... | {
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An example of the effect of poisoning is the series of isobars with mass number A = 135:
$$U(n,f)^{135}\text{Te} \xrightarrow{\beta^{-}} {}^{135}\text{I} \xrightarrow{6.61 \text{ h}} {}^{135}\text{Xe} \xrightarrow{\beta^{-}} {}^{135}\text{Cs} \xrightarrow{\beta^{-}} {}^{135}\text{Cs} \xrightarrow{\beta^{-}} {}^{135... | {
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"Header 2": "11.6 Reprocessing",
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The ratio of the number of atoms transmuting by $\beta^-$ decay to the number transformed by $(n, \gamma)$ reactions depends on the neutron flux density $\Phi$ :
$$\frac{(\mathrm{d}N/\mathrm{d}t)_{\beta}}{(\mathrm{d}N/\mathrm{d}t)_{\mathrm{n},\gamma}} = \frac{N\lambda}{N\sigma\Phi} = \frac{\lambda}{\sigma\phi\Ph... | {
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"Header 2": "11.6 Reprocessing",
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With respect to non-proliferation of nuclear weapons, strict controls of Pu input and output are necessary to avoid its misuse. Reprocessing of U-Th mixtures comprises separation of uranium, plutonium, thorium and the fission products, including the other actinides.
The details of reprocessing depend on the kind of f... | {
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"Header 2": "11.6 Reprocessing",
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#### 11.7 Radioactive Waste
The radioactive wastes originating from the operation of nuclear reactors and reprocessing plants is classified according to the activity level:
- low-level waste (LLW or LAW, low-active waste);
- medium-level waste (MLW or MAW, medium-active waste);
- high-level waste (HLW or HAW, hig... | {
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"Header 2": "11.6 Reprocessing",
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Chopping and dissolution of the fuel leads to volatilization of T (as T<sub>2</sub> or HTO), <sup>14</sup>C (as CO<sub>2</sub>), <sup>85</sup>Kr, <sup>129</sup>I and <sup>106</sup>Ru (as RuO<sub>4</sub>). The amount of T is relatively high. To avoid release into the air, T may be oxidized to T<sub>2</sub>O by treating ... | {
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"Header 2": "11.6 Reprocessing",
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The temperature must be $\geq 10^8$ K, and $n\tau$ must be $\geq 10^{21}$ s·m<sup>-3</sup> for the D-D reaction and $\geq 10^{20}$ s·m<sup>-3</sup> for the D-T reaction. The triple product $n\tau$ T must be $\geq 5 \cdot 10^4$ s·eV·m<sup>-3</sup>. Since two particles are involved in each collision, the fus... | {
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"Header 2": "11.6 Reprocessing",
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The high amounts of energy liberated by nuclear fission and fusion led very early to the production of nuclear explosives, as already mentioned in section 1 1.1. 235U, 239Pu and 233U can be used as nuclear explosives, because they have sufficiently high cross sections for fission by fast neutons. By use of the equation... | {
"Header 1": "10.3 Dependence of Radiation Emission on Chemical Bonding",
"Header 2": "**11.10 Nuclear Explosives**",
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Rydberg, (Actinide) Solution Chemistry, in: Comprehensive Inorganic Chemistry, Vol. 5, Pergamon, Oxford, 1975
- International Atomic Energy Agency, Management of Radioactive Wastes from the Nuclear Fuel Cycle, Vols. 1 and 2, IAEA, Vienna, 1976
- International Atomic Energy Agency, Int. Conf. on Nuclear Power and its Fu... | {
"Header 1": "10.3 Dependence of Radiation Emission on Chemical Bonding",
"Header 2": "**11.10 Nuclear Explosives**",
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#### 12.1 Production in Nuclear Reactors
Most radionuclides used in science and technology are produced in nuclear reactors, because neutrons are available with high flux densities $\Phi \approx 10^{10}$ to $10^{16}$ cm<sup>-2</sup> s<sup>-1</sup> and because the cross sections of $(n, \gamma)$ reactions are re... | {
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Some radionuclides can be produced by (n, p) and (n, *R)* reactions with thermal neutrons, for example
<sup>3</sup>He(n,p)<sup>3</sup>H (
$$\sigma = 5327$$
b; $t_{1/2} = 12.323$ y) (12.3)
<sup>14</sup>N(n, p)<sup>14</sup>C (
$$\sigma = 1.81 \text{ b}; t_{1/2} = 5730 \text{ y}$$
) (12.4)
<sup>6</sup>Li(n,
$$\a... | {
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Separation of Ba<br>as BaS04. |
| 9<br>9<br>~<br>~ | (a) Adsorption of Mo from 2 M HNO3 on A1203. Elution with 1 M NH3.<br>Separation from I by filtration through freshly precipitated AgCl.<br>(b) Extraction with ether from 6 M HCI. Back-extraction into water.<br>Separation of o... | {
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The various types of accelerators offer the possibility of applying a great variety of projectiles of different energies. The most frequently used projectiles are protons, deuterons and $\alpha$ particles. Some features of the reactions induced by these particles are summarized in Table 12.4. Neutrons may be produced... | {
"Header 1": "12 Production of Radionuclides and Labelled Compounds",
"Header 2": "12.2 Production by Accelerators",
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|
|---------------------------------------|--------------------------|---------------|
|---------------------------------------|--------------------------|---------------|
| Radionuclide | Half-life | Mode of decay $(E_{\beta^+(max)})$ | Nuclear reactions ... | {
"Header 1": "12 Production of Radionuclides and Labelled Compounds",
"Header 2": "12.2 Production by Accelerators",
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**Figure 12.4.** Cross sections of the reactions 14'Pr(y, n)14'Pr and I4'Pr(y, 2n)'39Pr as a function of the photon energy. (According to J. H. Carver, W. Turchinetz: Proc. physic. SOC. **73,** 110 (1959))
The samples may be irradiated inside or outside the accelerator, as shown schem... | {
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"Header 2": "12.2 Production by Accelerators",
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The task of quantitative and effective separation of small amounts of radionuclides has appreciably enhanced the development of modern separation techniques. High radionuclide purity is of great importance for application in nuclear medicine as well as for sensitive measurements. In this context, impurities of long-liv... | {
"Header 1": "12 Production of Radionuclides and Labelled Compounds",
"Header 2": "12.3 Separation Techniques",
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organic ion exchangers carrying chelating groups of high selectivity (preferably "tailor-made") as anchor groups or by application of inorganic ion exchangers. Highly selective organic ion exchangers are synthesized on the basis of polystyrene, cellulose or other substances as matrices. High selectivity with commerci... | {
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"Header 2": "12.3 Separation Techniques",
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Application of short-lived radionuclides has the advantage that the activity vanishes after relatively short periods of time. This aspect is of special importance in nuclear medicine. Short-lived radionuclides may be produced by irradiation in nuclear reactors or by accelerators, but their supply from irradiation facil... | {
"Header 1": "12 Production of Radionuclides and Labelled Compounds",
"Header 2": "**12.4 Radionuclide Generators**",
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(continued)
| | Mother nuclide | e | Daughter nuclide | | | | | | |
|--------------------|--------------------------------|-------------------... | {
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"Header 2": "**12.4 Radionuclide Generators**",
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The activity of the ground state 99Tc is negligible, because of its long half-life. Either 99M0 is produced with relatively low specific activity by neutron irradiation of Mo or it is obtained with high specific activity as a fission product by neutron irradiation of 235U followed by chemical separation. Usually, it is... | {
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"Header 2": "**12.4 Radionuclide Generators**",
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Labelled compounds have found broad application in various fields of science and technology. A great variety of labelled compounds are applied in nuclear medicine. The compounds are produced on a large scale as radiopharmaceuticals in cooperation with nuclear medicine, mainly for diagnostic purposes and sometimes also ... | {
"Header 1": "12 Production of Radionuclides and Labelled Compounds",
"Header 2": "**12.5 Labelled Compounds**",
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$^{18}$ F ( $t_{1/2} = 109.7$ min) is preferably produced by the nuclear reactions $^{18}$ O(p, n) $^{18}$ F and $^{20}$ Ne(d, $\alpha$ ) $^{18}$ F, because of the relatively high yields at moderate projectile energies. If O<sub>2</sub> or Ne gas is used, the chemical form of $^{18}$ F obtained after irradiation... | {
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"Header 2": "**12.5 Labelled Compounds**",
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For Instance, 99mTc0, eluted from a 99Mo/99mTc radionuclide generator can be introduced into organic compounds by various chemical procedures that can be performed by use of special "kits" which allow easy handling.
For routine syntheses of labelled compounds, automated procedures have been developed which enable fas... | {
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"Header 2": "**12.5 Labelled Compounds**",
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Acta 30, 163 **(1982)**
- R. R. Muccino, Organic Syntheses with Carbon-14, Wiley, New York, **1983**
- H. Deckart, P. H. Cox (Eds.), Principles of Radiopharmacology, Developments in Nuclear Medicine, Vol. 11, Kluwer Academic Publ., Dordrecht, Boston, London, **1987**
- G. Stocklin, V. W. Pike (Eds.), Radiopharmaceutica... | {
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"Header 2": "**12.5 Labelled Compounds**",
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#### 13.1 Short-Lived Radionuclides and the Role of Carriers
The most important aspects of the chemistry of short-lived radionuclides are that
- the mass of the radionuclides is small and
- chemical procedures have to be fast.
The mass of a radionuclide is proportional to its half-life:
$$m = A \frac{M}{\ln 2 \... | {
"Header 1": "13 Special Aspects of the Chemistry of Radionuclides",
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In the absence of stable isotopes, the specific activity of radionuclides is given by
$$\frac{A}{m} = \frac{\ln 2}{t_{1/2}} \frac{N_{\text{Av}}}{M} \tag{13.2}$$
where *A,* m, t!p and M are the activity, the mass, the half-life and the atomic mass of the radionuclide, respectively, and NA~ is Avogadro's number. Even... | {
"Header 1": "13 Special Aspects of the Chemistry of Radionuclides",
"Header 2": "**13.2 Radionuclides of High Specific Activity**",
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From the previous sections it is evident that radionuclides of high specific activity often represent very small amounts (microamounts, non-weighable amounts < 1 **pg)** of matter, especially if the half-lives are short. Handling of such microamounts requires special precautions, because in the absence of measurable a... | {
"Header 1": "13 Special Aspects of the Chemistry of Radionuclides",
"Header 2": "**13.3 Microamounts of Radioactive Substances**",
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Wertenbach: *Z.* <sup>70</sup>80 **90** \_- phvsik. Chem., Neue Folge **34,**
If macroamounts of other elements are to be separated from microamounts of radioactive substances by precipitation, isotopic or non-isotopic hold-back carriers may be added to suppress coprecipitation of the radioactive substances.
In io... | {
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"Header 2": "**13.3 Microamounts of Radioactive Substances**",
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Radiocolloids are colloidal forms of microamounts of radioactive substances. Their formation was first observed by Paneth (1913) in his research on the separation of 210Bi and 218Po. Radiocolloids can be separated from aqueous solutions by ultrafiltration, centrifugation, dialysis and electrophoresis. They can be detec... | {
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"Header 2": "**13.4 Radiocolloids**",
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Tracer techniques comprise all methods in which microamounts (traces) of radionuclides or labelled compounds are added to a system, in order to pursue (trace) the fate, transport or chemical reaction of a certain element or compound in that system. Radioactive tracers are preferabley used, because they can be detected ... | {
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"Header 2": "13.5 Tracer Techniques",
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Radioelements are elements existing only in the form of radionuclides, but not as stable isotopes, as already mentioned in section 2.1.
The natural radioelements are listed in Table 14.1. Isotopes of these elements are members of the uranium, actinium and thorium families (Table 1.2, and Tables 4.1 to **4.3).** In th... | {
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Artificial radioelements
| Atomic<br>number<br>Z | Name of the element (Symbol) | Longest-lived<br>nuclide<br>(Half-life) | Discovery | Remarks |
|-----------------------|------------------------------|--------------------------------... | {
"Header 1": "13 Special Aspects of the Chemistry of Radionuclides",
"Header 2": "**14.1 Natural and Artificial Radioelements**",
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After a burn-up of 35 000 MWd per ton of uranium with an initial enrichment of 3% <sup>235</sup>U, the spent fuel contains about 1 kg <sup>99</sup>Tc per ton. The longest-lived isotope of Tc is <sup>98</sup>Tc ( $t_{1/2}=4.2\cdot10^6$ y); in contrast to <sup>99</sup>Tc, it has no practical significance.
Although <su... | {
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"Header 2": "**14.1 Natural and Artificial Radioelements**",
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$\Lambda = \lambda + \Sigma \sigma_i \Phi_i$ is the sum of the decay constant $\lambda$ and all products $\sigma_i \Phi_i$ of binuclear reactions
Figure 14.5. Production of transuranium elements by neutron irradiation of <sup>238</sup>U.
(e.g. nuclear fission) also leading to a ... | {
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"Header 2": "**14.1 Natural and Artificial Radioelements**",
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After milligram amounts of <sup>241</sup>Am had been produced by reaction (14.14), <sup>243</sup>Bk was obtained in 1949 by Thompson, Ghiorso and others by irradiation with $\alpha$ particles:
$$^{241}$$
Am $(\alpha, 2n)^{243}$ Bk (14.17)
Berkelium was named in analogy to terbium after a city (Berkeley).
Califo... | {
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"Header 2": "**14.1 Natural and Artificial Radioelements**",
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Further investigations of the Dubna group revealed that two isotopes of element 104 were formed
$$^{-242}$$
Pu( $^{22}$ Ne, 5n) $^{259}$ Rf; $t_{1/2}$ (sf) = 3.0 s (14.26)
$$^{242}Pu(^{22}Ne, 4n)^{260}Rf; t_{1/2}(sf) = 21 ms$$
(14.27)
In the meantime, the Berkeley group (Ghiorso et al., 1969) was able to produce... | {
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"Header 2": "**14.1 Natural and Artificial Radioelements**",
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Element 107 (bohrium) was synthesized by the GSI group (Münzenberg, Armbruster et al.) in 1981 by the reactions
$$^{209}\text{Bi}(^{54}\text{Cr}, n)^{262}\text{Bh} \xrightarrow{\alpha}_{102 \text{ ms}/8.0 \text{ ms}}^{258}\text{Db} \xrightarrow{\alpha}_{4.4 \text{ s}}^{254}\text{Lr}$$
(14.37)
and
$$^{209}\text{... | {
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"Header 2": "**14.1 Natural and Artificial Radioelements**",
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The half-lives of the longest-lived isotopes of transuranium elements (Fig. 14.8) show a continuous exponential decrease with increasing atomic number Z. Whereas up to element 103 the half-life is mainly determined by $\alpha$ decay, the influence of spontaneous fission seems to become predominant for elements with ... | {
"Header 1": "14.4 Further Extension of the Periodic Table of the Elements",
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All actinides are radioelements and only Th and U have half-lives long enough to justify neglecting their radioactivity in some special chemical or technical operations. Ac and Pa are present in small amounts as decay products of U and Th (Table 11.3). Extremely small amounts of Np and Pu are produced in U by neutrons ... | {
"Header 1": "14.4 Further Extension of the Periodic Table of the Elements",
"Header 2": "14.5 Properties of the Actinides",
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| | M <sup>3+</sup> | $M^{4+}$ | $\mathrm{MO}_2^+$ | $MO_2^{2+}$ | |
|--------------|-----------------|-----------------|-------------------|-------------|--|
| Actinium | Colourless | <u> </u> | _ | _ | |
| Thorium | _ | Colourless ... | {
"Header 1": "14.4 Further Extension of the Periodic Table of the Elements",
"Header 2": "14.5 Properties of the Actinides",
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Np $O_2^+$ is quite stable, whereas $PuO_2^+$ and $AmO_2^+$ disproportionate easily.
The oxidation state VI is preferred by U, but it is also found with Np. **Pu** and Am. In aqueous solution, this oxidation state always exists in the form of "yl" ions MO:' . These ions are not formed by hydrolysis and arc also ... | {
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"Header 2": "14.5 Properties of the Actinides",
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Three ways can be distinguished to elucidate the properties of the transactinides:
- Extrapolation of the properties on the basis of the tendencies in the Periodic Table
of the elements.
- Calculation of the electronic structure of the elements and the energy levels of the electrons in the atoms and their compounds.
... | {
"Header 1": "14.4 Further Extension of the Periodic Table of the Elements",
"Header 2": "14.6 Properties of the Transactinides",
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$^{262}$ Db and $^{263}$ Db are produced by the reactions $^{249}$ Bk( $^{18}$ O, 5n) $^{262}$ Db $(\sigma \approx 6 \, \text{nb})$ and $^{249}$ Bk( $^{18}$ O, 4n) $^{263}$ Db, respectively. The sequence of complex formation and extraction with various extractants, studied with the ARCA apparatus, is Pa > Nb $\g... | {
"Header 1": "14.4 Further Extension of the Periodic Table of the Elements",
"Header 2": "14.6 Properties of the Transactinides",
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| Element | Atomic mass | Electrons in the outer orbitals | Preferred oxidation state | Ionization<br>potential<br>[eV] | Ionic radius<br>in the metallic<br>state [10 <sup>-8</sup> cm] | Density [g/cm <sup>3</sup> ] |
|---------|-------------|---------------------------------|---------------------------|-------------... | {
"Header 1": "14.4 Further Extension of the Periodic Table of the Elements",
"Header 2": "14.6 Properties of the Transactinides",
"token_count": 1826,
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| a redicted electr | on connymations | OI SUDEFACUITIOES |
| Element | Ele | ctror | ns in | the o | uter | orbi | tals | Element | | ctroi | ns in | the or | iter o | orbita | als | |
|---------|-----|-------|-------|-------|------|------|------|---------|----|-------|-------|--------|--------|--------|----... | {
"Header 1": "14.4 Further Extension of the Periodic Table of the Elements",
"Header 2": "14.6 Properties of the Transactinides",
"token_count": 2038,
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Keller, The Chemistry of the Transuranium Elements (Ed. K. H. Lieser), Verlag Chemie, Weinheim, 1971
- K. W. Bagnall (Ed.), International Review of Science, Inorganic Chemistry, Vol. 7, Lanthanides and Actinides, Series One and Two, Butterworths, London, 1972 and 1975
- A. J. Freeman, J. B. Darby, jr. (Eds.), The Actin... | {
"Header 1": "14.4 Further Extension of the Periodic Table of the Elements",
"Header 2": "14.6 Properties of the Transactinides",
"token_count": 2025,
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Herrmann, Superheavy Element Research, Nature (London) 280, 543 (1979)
- Y. T. Oganessian, M. Hussonnois, A. G. Demin, Y. P. Khaitonov, H. Bruchertseifer, O. Constantinescu, Y. Korotkin, S. P. Tretyakova, V. K. Utyonkov, I. V. Shirokovsky, J. Estevez, Experimental Studies on the Formation and Radioactive Decay of Isoto... | {
"Header 1": "14.4 Further Extension of the Periodic Table of the Elements",
"Header 2": "14.6 Properties of the Transactinides",
"token_count": 681,
"source_pdf": "datasets/websources/biochem/Nuclear-and-Radiochemistry-Fundamental-and-Application.pdf"
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A main concern of geochemistry is the investigation of the abundance and the distribution of the elements on the surface and in deeper layers of the earth, and of transport processes. The components of the geosphere are the lithosphere, the hydrosphere and the atmosphere. The relative abundance of the elements on the s... | {
"Header 1": "15.1 Natural Abundances of the Elements and Isotope Variations",
"token_count": 2048,
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The concern of cosmochemistry is the investigation of extraterrestrial matter (sun, moon, planets, stars and interstellar matter) and their chemical changes. Meteorites are an object of special interest in cosmochemistry, because of the nuclear reactions induced by high-energy protons in cosmic radiation (E(p) up to ab... | {
"Header 1": "15.1 Natural Abundances of the Elements and Isotope Variations",
"Header 2": "**15.2 General Aspects of Cosmochemistry**",
"token_count": 521,
"source_pdf": "datasets/websources/biochem/Nuclear-and-Radiochemistry-Fundamental-and-Application.pdf"
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According to the concept of the big bang, a mixture of fundamental particles and energy existed at time zero at an extremely high temperature (of the order of about $10^{30}$ K) and an extremely high density (of the order of about $10^{50}$ g cm<sup>-3</sup>) in an extremely small volume. The unified theory of fund... | {
"Header 1": "15.1 Natural Abundances of the Elements and Isotope Variations",
"Header 2": "15.3 Early Stages of the Universe",
"token_count": 1383,
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With the aggregation of matter in the stars under the influence of gravitation, new processes begin to dominate:
- Gravitational contraction of the stars causes increase of temperature associated with the emission of light and other kinds of electromagnetic radiation.
- If the temperature in the core of the stars bec... | {
"Header 1": "15.1 Natural Abundances of the Elements and Isotope Variations",
"Header 2": "15.4 Synthesis of the Elements in the Stars",
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Nucleogenesis and evolution of stars are strongly correlated. The evolution of the stars comprises different stages and depends mainly on their mass, as already mentioned. In all cases, stars of high density are formed at the end of the evolution.
In stars of small mass (<0.1 times the mass of the sun) the energy lib... | {
"Header 1": "15.1 Natural Abundances of the Elements and Isotope Variations",
"Header 2": "**15.5 Evolution of Stars**",
"token_count": 2044,
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Two types of interstellar clouds are distinguished: optically transparent, diffuse clouds containing < $10^3$ atoms per cm³ (mainly H, but also some compounds such as CO or HCHO) at temperatures of the order of 100 K, and opaque, dense clouds containing $10^4$ to $10^6$ molecules per cm³ (mainly H<sub>2</sub>, but... | {
"Header 1": "15.1 Natural Abundances of the Elements and Isotope Variations",
"Header 2": "**15.5 Evolution of Stars**",
"token_count": 2045,
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Wassenburg (Eds.), Isotopic and Cosmic Chemistry, North-Holland, Amsterdam, 1963
- W. A. Fowler, F. Hoyle, Nucleosyntheis in Massive Stars and Supernovae, University of Chicago Press, Chicago, IL, 1965
- D. D. Clayton, Principles of Stellar Evolution and Nuclear Synthesis, McGraw-Hill, New York, 1968
- J. R. Arnold, H.... | {
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"Header 2": "**15.5 Evolution of Stars**",
"token_count": 776,
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The laws of radioactive decay are the basis of chronology by nuclear methods. From the variation of the number of atoms with time due to radioactive decay, time differences can be calculated rather exactly. This possibility was realized quite soon after the elucidation of the natural decay series of uranium and thorium... | {
"Header 1": "15.1 Natural Abundances of the Elements and Isotope Variations",
"Header 2": "16.1 General Aspects",
"token_count": 1200,
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Cosmogenic radionuclides applicable for dating are listed in Table 16.1. The radionuclides are produced at a certain rate by the interaction of cosmic rays with the components of the atmosphere, mainly in the stratosphere. If the intensity of cosmic rays (protons and neutrons) can be assumed to be constant, the product... | {
"Header 1": "15.1 Natural Abundances of the Elements and Isotope Variations",
"Header 2": "**16.2** Cosmogenic Radionuclides",
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The neutrons liberated by these explosions led to a sharp increase of the <sup>14</sup>C production in the upper layers of the atmosphere, and the <sup>14</sup>C: <sup>12</sup>C ratio increased by a factor of about 2 in the northern hemisphere in 1962/63. With respect to these effects, the relatively small amounts of <... | {
"Header 1": "15.1 Natural Abundances of the Elements and Isotope Variations",
"Header 2": "**16.2** Cosmogenic Radionuclides",
"token_count": 2019,
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Terrestrial mother/daughter nuclide pairs suitable for dating are listed in Table 16.2. Dating by means of these nuclide pairs requires evaluation of eq. (16.1). In doing this, it has to be taken into account that, in general, at time t=0 stable nuclides identical with the radiogenic nuclides are already present. This ... | {
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"Header 2": "16.3 Terrestrial Mother/Daughter Nuclide Pairs",
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The ZoxPb : 232 Th due to radioactive decay of the mother nuclides arc plotted in Fig. 16.1 as a function of the age, provided that no losses have occurrcd. Application of the natural decay series for dating is summarized in Table 16.3. The 238U/'ohPb method and thc 2"'I'h/'"xPb method oKcr thc possibility of dctcrmini... | {
"Header 1": "15.1 Natural Abundances of the Elements and Isotope Variations",
"Header 2": "**16.4 Natural Decay Series**",
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Lead has four stable isotopes, <sup>204</sup>Pb, <sup>206</sup>Pb, <sup>207</sup>Pb and <sup>208</sup>Pb. The stability of <sup>204</sup>Pb has been debated, but the half-life is >10<sup>17</sup> y and, with respect to the age of the earth and the universe, <sup>204</sup>Pb can be considered to be stable. In the course... | {
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"Header 2": "16.5 Ratios of Stable Isotopes",
"token_count": 1094,
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Mother and daughter nuclides of decay series are often separated by natural processes. Such separations are very common if the mother nuclide is dissolved in water (e.g. in the oceans), but they may also occur in solids. By measuring the decay of the separated daughter nuclide or the growth of the daughter nuclide in t... | {
"Header 1": "15.1 Natural Abundances of the Elements and Isotope Variations",
"Header 2": "**16.6 Radioactive Disequilibria**",
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Principles and Applications, Ellis Horwood, Chichester, 1986
- M. A. Geyh, H. Schleicher, Absolute Age Determination, Springer, Berlin, 1990
- H. R. von Gunten, Radioactivity: A Tool to Explore the Past, Radiochim. Acta 70/71, 305 (1995)
#### **More Special**
W. F. Libby, Radiocarbon Dating, University of Chicago P... | {
"Header 1": "15.1 Natural Abundances of the Elements and Isotope Variations",
"Header 2": "**16.6 Radioactive Disequilibria**",
"token_count": 441,
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The low detection limits of radioactive substances are very attractive for use in analytical chemistry. In principle, a single radioactive atom can be detected provided that it is measured at the moment of its decay. In practice, however, a greater number of radioactive atoms is necessary to measure their radioactivity... | {
"Header 1": "15.1 Natural Abundances of the Elements and Isotope Variations",
"Header 2": "**17.1 General Aspects**",
"token_count": 900,
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The activity of naturally radioactive elements is a measure of their mass. Prerequisites of application of the correlation between mass and activity according to eq. (17.1) are that the isotopic composition of the element to be determined is constant and that interfering radioactive impurities are absent. If the daught... | {
"Header 1": "15.1 Natural Abundances of the Elements and Isotope Variations",
"Header 2": "**17.2 Analysis on the Basis of Inherent Radioactivity**",
"token_count": 942,
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Activation analysis is based on the production of radionuclides by nuclear reactions. The specific activity is given by the equation of activation,
$$A_{s} = \sigma \Phi \frac{N_{Av}}{M} H \left( 1 - \left( \frac{1}{2} \right)^{t/t_{1/2}} \right)$$
(17.2)
where $\sigma$ is the cross section of the nuclear reactio... | {
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"Header 2": "17.3 Neutron Activation Analysis (NAA)",
"token_count": 2012,
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Neutron yield of the reaction $t(d, n)\alpha$ as a function of the deuteron energy (target: Ti containing $1 \text{ Ci} = 3.7 \cdot 10^{10} \text{ Bg T}$ ).
**Figure 17.3.** Neutron yield of the reaction <sup>9</sup>Be(d, n)<sup>10</sup>B as a function of the deuteron energy (thick B... | {
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"Header 2": "17.3 Neutron Activation Analysis (NAA)",
"token_count": 1096,
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Charged particles must have a minimum energy (threshold energy) to surmount the Coulomb barrier (section 8.3). In general, the excitation functions exhibit maxima in the range of about 0.1 to 1 b. For acceleration of charged particles, van de Graaff generators are often preferred, because the energy of the particles ca... | {
"Header 1": "15.1 Natural Abundances of the Elements and Isotope Variations",
"Header 2": "**17.4 Activation by Charged Particles**",
"token_count": 1985,
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Photons may induce quite a number of nuclear reactions (section 8.3), and photo-excitation $(\gamma, \gamma')$ may also be applied to activation analysis. In general, the photons are obtained in the form of bremsstrahlung: high-energy electrons produced in an electron accelerator hit a target of high atomic number su... | {
"Header 1": "15.1 Natural Abundances of the Elements and Isotope Variations",
"Header 2": "17.5 Activation by Photons",
"token_count": 1213,
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Due to the high sensitivity, activation analysis is one of the most important methods for determination of microcomponents, in particular trace elements, in materials of high purity (e.g. in semiconductors), in water, in biological samples and in minerals. The main fields of application are:
- geo- and cosmochemistry... | {
"Header 1": "15.1 Natural Abundances of the Elements and Isotope Variations",
"Header 2": "17.6 Special Features of Activation Analysis",
"token_count": 1694,
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The principle of isotope dilution analysis (IDA) is illustrated in Fig. 17.4. The sample contains an unknown number *N,* of atoms or molecules, and it may also contain an unknown number *\*N,* of labelled atoms or molecules of the same kind. Known numbers *N1* and *\*N1* are added. These atoms or molecules (subscript *... | {
"Header 1": "15.1 Natural Abundances of the Elements and Isotope Variations",
"Header 2": "**17.7 Isotope Dilution Analysis**",
"token_count": 2031,
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Further examples are determination of **SO2** by reaction with 10, labelled with **I3lI,** and determination of active hydrogen in organic substances by reaction with LiAlH4 labelled with T.
The isotope exchange method is based on the exchange between two different forms or compounds of the element M to be determined... | {
"Header 1": "15.1 Natural Abundances of the Elements and Isotope Variations",
"Header 2": "**17.7 Isotope Dilution Analysis**",
"token_count": 530,
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Backscattering of *p* radiation can be taken as the basis for surface analysis. It is due to electron-electron interaction, which is nearly independent of the atomic number Z of the material, and to scattering by atomic nuclei, which increases with Z. Both effects overlap, and the saturation value of backscattering inc... | {
"Header 1": "15.1 Natural Abundances of the Elements and Isotope Variations",
"Header 2": "**17.10 Absorption and Scattering of Radiation**",
"token_count": 519,
"source_pdf": "datasets/websources/biochem/Nuclear-and-Radiochemistry-Fundamental-and-Application.pdf"
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The application of radionuclides as radiation sources in X-ray fluorescence analysis is illustrated in Fig.17.5. The X rays or $\gamma$ rays emitted by a radionuclide are absorbed in the sample and the X rays emitted by the sample are measured by means of a semiconductor in combination with a multichannel analyser. Q... | {
"Header 1": "17.11 Radionuclides as Radiation Sources in X-ray Fluorescence Analysis (XFA)",
"token_count": 1905,
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Application of radiotracers in chemistry and in other fields of science is based on two features:
- <sup>~</sup>the high sensitivity of detection of radionuclides, and
- the possibility of labelling of elements or chemical compounds.
The high sensitivity of detection of radionuclides has already been emphasized in ... | {
"Header 1": "17.11 Radionuclides as Radiation Sources in X-ray Fluorescence Analysis (XFA)",
"Header 2": "**18.1 General Aspects**",
"token_count": 283,
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The extraordinarily high sensitivity of radiochemical methods makes it possible to measure solubility equilibria of sparingly soluble compounds or distribution equilibria in the range of very low concentrations. This is illustrated for the silver halides AgCl, AgBr and AgI in Fig. 18.1, in which the concentration of **... | {
"Header 1": "17.11 Radionuclides as Radiation Sources in X-ray Fluorescence Analysis (XFA)",
"Header 2": "**18.2 Chemical Equilibria and Chemical Bonding**",
"token_count": 770,
"source_pdf": "datasets/websources/biochem/Nuclear-and-Radiochemistry-Fundamental-and-Application.pdf"
} |
Radiotracer methods are the methods of choice for investigation of reaction mechanisms. They have also found broad application for determination of kinetic data of chemical reactions such as reaction rates, activation energies and entropies. Only a few examples can be given of the multitude of applications in organic, ... | {
"Header 1": "17.11 Radionuclides as Radiation Sources in X-ray Fluorescence Analysis (XFA)",
"Header 2": "18.3 Reaction Mechanisms in Homogeneous Systems",
"token_count": 2002,
"source_pdf": "datasets/websources/biochem/Nuclear-and-Radiochemistry-Fundamental-and-Application.pdf"
} |
Thus, for the exchange of water molecules in the first coordination sphere of 3d transition elements the following values have been measured: $Cr^{2+}(d^4)$ : $7 \cdot 10^9 \ s^{-1}$ ; $Cr^{3+}(d^3)$ : $5 \cdot 10^{-7} \ s^{-1}$ ; $Mn^{2+}(d^5)$ : $3 \cdot 10^7 \ s^{-1}$ ; $Fe^{2+}(d^6)$ : $3 \cdot 10^6 \ s^{-1... | {
"Header 1": "17.11 Radionuclides as Radiation Sources in X-ray Fluorescence Analysis (XFA)",
"Header 2": "18.3 Reaction Mechanisms in Homogeneous Systems",
"token_count": 1126,
"source_pdf": "datasets/websources/biochem/Nuclear-and-Radiochemistry-Fundamental-and-Application.pdf"
} |
In heterogeneous systems, radiotracer methods also have a wide range of applications with respect to elucidation of reaction mechanisms as well as to the determination of kinetic data.
In heterogeneous reactions, either the reaction at the phase boundary or the transport to or from the reaction zone can be rate-deter... | {
"Header 1": "17.11 Radionuclides as Radiation Sources in X-ray Fluorescence Analysis (XFA)",
"Header 2": "**18.4 Reaction Mechanisms in Heterogeneous Systems**",
"token_count": 1946,
"source_pdf": "datasets/websources/biochem/Nuclear-and-Radiochemistry-Fundamental-and-Application.pdf"
} |
It is based on the even distribution of labelled ions between the surface and a solution to which these ions have been added:
$$\frac{{}^{*}N_{1}}{N_{1}} = \frac{{}^{*}N_{2}}{N_{2}} \tag{18.29}$$
*\*NI* and \*N2 are the numbers of labelled ions on the surface and in solution, respectively, and N1 and N2 are the tot... | {
"Header 1": "17.11 Radionuclides as Radiation Sources in X-ray Fluorescence Analysis (XFA)",
"Header 2": "**18.4 Reaction Mechanisms in Heterogeneous Systems**",
"token_count": 981,
"source_pdf": "datasets/websources/biochem/Nuclear-and-Radiochemistry-Fundamental-and-Application.pdf"
} |
The high sensitivity of radiotracer techniques makes these very attractive for determination of diffusion coefficients. Self-diffusion (i.e. diffusion of the intrinsic components of the substance) is of special interest and can only be measured by indicator methods.
Most investigations of self-diffusion have been mad... | {
"Header 1": "17.11 Radionuclides as Radiation Sources in X-ray Fluorescence Analysis (XFA)",
"Header 2": "**18.5 Diffusion and Transport Processes**",
"token_count": 1488,
"source_pdf": "datasets/websources/biochem/Nuclear-and-Radiochemistry-Fundamental-and-Application.pdf"
} |
Therefore, either the radium isotopes or the thorium isotopes may be incorporated into the solid
(a) Production in the decay series
$$\begin{array}{c}
226 \text{Ra} \xrightarrow{\alpha, \gamma} 222 \text{Rn} \xrightarrow{3.825 \text{d}} 218 \text{Po} \\
228 \text{Th} \xrightarrow{\alpha, \gamma} 1913 \text{ y} 224 ... | {
"Header 1": "17.11 Radionuclides as Radiation Sources in X-ray Fluorescence Analysis (XFA)",
"Header 2": "**18.5 Diffusion and Transport Processes**",
"token_count": 2041,
"source_pdf": "datasets/websources/biochem/Nuclear-and-Radiochemistry-Fundamental-and-Application.pdf"
} |
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