Nuclear spectroscopies

In nuclear spectroscopy fine structure arises from coupling between nuclear spins. 

When performing 2D-NMR experiments one must keep in mind that the second frequency dimension (Fx) is digitized by the number of tx increments. Therefore, it is important to consider the amount of spectral resolution that is needed to resolve the correlations of interest. In the first dimension (F2), the resolution is independent of time relative to F. The only requirement for F2 is that the necessary number of scans is obtained to allow appropriate signal averaging to obtain the desired S/N. These two parameters, the number of scans acquired per tx increment and the total number of tx increments, are what dictate the amount of time required to acquire the full 2D-data matrix. 2D-homo-nuclear spectroscopy can be summarized by three different interactions, namely scalar coupling, dipolar coupling and exchange processes. 

The problem of missing labels is discussed in detail in connection with nuclear spectroscopy (Iachello and Arima, 1987). 

Although the theoretical studies predict solvent medium breakdown before the onset of actinium electrodeposition, there have been reports of Ac(0) electrodeposition from aqueous solutions utilizing several different methods [8, 9]. One set of studies [8] describes the electrodeposition of actinium from nitric acid solutions, with varying pH values (1.0-4.0) being set to the appropriate level by the addition of sodium hydroxide. The anode and cathode in these studies were platinum metal, and the current density was varied from 50 to 200 mA cm . The authors found that quantitative electrodeposition of actinium could be achieved under various conditions, with the shortest electrolysis time of 1 h being obtained with a current density of200 mA cm and a pH of 2.0. A second study employed a saturated aqueous solution of urea oxalate (ca 6.6% at 30 °C) as an electrolyte for the electrodeposition of Ac onto a nickel foil cathode [9]. The authors of this study found that the yield of electrodeposited Ac increased with time and reached a near quantitative maximum yield of 97% at a current density of 53 mAcm after 2 h. The Ac electrodeposits were suitable for further study using nuclear spectroscopy. 

If high temperatures eventually lead to an almost equal population of the ground and excited states of spectroscopically active structure elements, their absorption and emission may be quite weak, particularly if relaxation processes between these states are slow. The spectroscopic methods covered in Table 16-1 are numerous and not equally suited for the study of solid state kinetics. The number of methods increases considerably if we include particle radiation (electrons, neutrons, protons, atoms, or ions). We note that the output radiation is not necessarily of the same type as the input radiation (e.g., in photoelectron spectroscopy). Therefore, we have to restrict this discussion to some relevant methods and examples which demonstrate the applicability of in-situ spectroscopy to kinetic investigations at high temperature. Let us begin with nuclear spectroscopies in which nuclear energy levels are probed. Later we will turn to those methods in which electronic states are involved (e.g., UV, VIS, and IR spectroscopies). 

Nuclei provide a large number of spectroscopic probes for the investigation of solid state reaction kinetics. At the same time these probes allow us to look into the atomic dynamics under in-situ conditions. However, the experimental and theoretical methods needed to obtain relevant results in chemical kinetics, and particularly in atomic dynamics, are rather laborious. Due to characteristic hyperfine interactions, nuclear spectroscopies can, in principle, identify atomic particles and furthermore distinguish between different SE s of the same chemical component on different lattice sites. In addition to the analytical aspect of these techniques, nuclear spectroscopy informs about the microscopic motion of the nuclear probes. In Table 16-2 the time windows for the different methods are outlined. 

In Table 16-2, the time scale for elementary activated motion is given in the first place. It is converted into an energy scale by virtue of the E = (2n-h/t) relation, If we assume that the atomic jump length a is 2 A, the time scale may be converted into a diffusion coefficient scale by D = az/(2-t). One notes that (with the exception of /J-NMR) nuclear spectroscopies monitor the atomic jump behavior of relatively fast diffusing species. 

Table 16-3 gives some more information on nuclei used in spectroscopy. When the kinetic problem dictates small dimensions of the sample (e.g., in thin film oxidation), the concentration needed to apply a nuclear spectroscopy may be considerably higher than indicated in Thble 16-3. 

Table 16-3. Comparison between different nuclear spectroscopies...

Figure 18.21 Schematic diagram of a simple pulse height analysis system for nuclear spectroscopy. (From Wang et al., 1975.)...

B. F. Beiman. Lectures on Applications of the Group Theory to Nuclear Spectroscopy, Fizmatgiz, Moscow, 1961 (in Russian). 

MEY85] R.A.Meyer,S.Brant, V.Paar and D.Vretenar, to be published PAA84 V.Paar, in In-Beam Nuclear Spectroscopy, Ed. Zs. Dcmbradi and T. 

BEC84] J. A. Becker, S. D. Bloom, and E. K. Warburton, in Proceedings of the International Symposium on IN-BEAM NUCLEAR SPECTROSCOPY, Debrecen, Hungary (1984). 

BRU77 P.J. Brussaard and P.W.M. Glaudemans, Shell-model applications in nuclear spectroscopy, North-Holland Publishing Company, Amsterdam 1977. 

K. Sistemich et al., Proc. Int. Symp. on In-Beam Nuclear Spectroscopy, Debrecen, Hungary, Vol. I 51 (1984), and Refs, therein. 

In-Beam Nuclear Spectroscopy, Zs. DombrUdi and T. Fgnyes, eds. (Akademiai Kiad6, Budapest, 1984). 

The most serious problem associated with the use of neutron scattering for nuclear spectroscopy comes from the fact that the resolution for neutron detection is typically rather poor, and the sensitivity to small transition probabilities is also poor when neutron detection is being employed. These difficulties can be alleviated by observing the y rays which de-excite the excited levels rather than the inelastically scattered neutrons. 

Nuclear spectroscopy Mossbauer spectroscopy Nuclear quadrupole resonance... 

M. Naito, H. Nishihara and T. Butz, in Nuclear Spectroscopy on Charge Density Wave Systems , ed. T. Butz, Kluwer Academic Publishers, 1992, p. 35. 

F. Ajzenberg-Selove (Ed.), Nuclear Spectroscopy, Part B, Academic Press, New York, 1960... 

J. A. Rasmussen, Models of Heavy Nuclei, in Nuclear Spectroscopy and Reactions, Part C (Ed. J. Cerny), Academic Press, New York, 1974... 

A. H. Wapstra, G. J. Nijgh, R. van Lieshout, Nuclear Spectroscopy Tables, North Holland, Amsterdam, 1959... 

K. Bachmann, Messung radioaktiver Nuklide (Ed. K. II. Lieser), Verlag Chemie, Weinheim, 1970 J. H. Hamilton (Ed.), Radioactivity in Nuclear Spectroscopy, Modern Techniques and Applications, Vols. I and II, Gordon and Breach, New York, 1972 J. Krugers (Ed.), Instrumentation in Applied Nuclear Chemistry. Plenum Press, New York. 1973 J. Ceniy (Ed.), Nuclear Spectro.scopy and Reactions, Vols. A, B and C, Academic Press, New York, 1974... 

Semiconductor Radiation Detectors, in Nuclear Spectroscopy and Reactions, Vol. A (Ed. J. 

The constant value of e for different types of radiation and for different energies contributes to the versatility and flexibility of semiconductor detectors for use in nuclear spectroscopy. The low value of compared with the average energy necessary to create an electron-ion pair in a gas (typically 15 to 30 eV) results in the superior spectroscopic performance of semiconductor detectors. 

V.P. Perminov, M.S. Grigoriev, M.P. Glazunov, N.N. Krot, Abstracts on XXXII Meeting on Nuclear Spectroscopy and Structure of Nuclear Cell. Leningrad. Nauka, 1982. P. 510. R.A. Permeman, J.S. Coleman, T.K Keenan, J. Inorg. Nucl. Chem. 17 (1961) 138. 

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