Mossbauer resonant atom

If the resonant atoms of the screen are identical to the researched atom (containing the excited nucleus) than we have = d - For the case when the excited nucleus is a Mossbauer one, the screen is made from Mossbauer resonant atoms and the usual condition G I, Afi I holds, at exactly resonant state o) o — + o) = 0 we have... 

The linewidth (corrected for instrumental effects) may also provide important chemical information of several types. For example, if the chemical environment of a resonant atom is not the same for all of the atoms in the sample, then a broadening of the observed resonance is expected. That is, the observed resonance is a sum of the contributions from each atom, the latter not all having the same Mossbauer parameters. Thus for a small catalyst particle, interesting particle size information might be contained in the linewidth due to the contribution from the surface atoms to the Mossbauer spectrum. The distribution (clustered or uniform) of resonant atoms throughout a multicomponent catalyst particle may also be reflected in the linewidth. 

In Mossbauer spectroscopy of 57Fe, the radiation is specific for the 57Fe which eliminates the complications caused by the presence of other atoms. Most elements do not have a suitable isotope available for Mossbauer spectroscopy. Because iron is of such paramount importance in the molecules of life it is indeed fortunate that 57Fe exhibits such a good Mossbauer resonance. If a biological molecule contains iron, it is almost... 

Dynamic groperties of the lattice in which the resonant atom is bound. The area of the absorption spectrum is governed by the probability of a nucleus absorbing a y-photon emitted by the source without recoil. The Mossbauer effect is actually the quantum-mechanical result that such a resonant absorption process should have a non-vanishing probability of taking place, given... 

FeSn2 is antiferromagnetic below 377 K with a field of 115 kG at 295 K. In all cases (except FesSna) a field of between 30 and 110 kG is also recorded at the tin nucleus in the Sn Mossbauer resonance (see Chapter 14). This results from exchange polarisation of the diamagnetic tin atoms by the iron [118-120],... 

The equivalence of the iron atoms in [CsHsFeCO] is also demonstrated by the presence of a single quadru-pole split Mossbauer resonance (250). The laser Raman spectrum of [CsHsFeCO] (91 M = Fe) was obtained... 

Since the hyperfine interactions are determined principally by the electron density and the inhomogeneous electric field as well as by the effective magnetic flux density at the nucleus, the Mossbauer spectrum patterns differ from site to site where these physical quantities are different. Thus, a single-phase material may be characterized by a complex M5ssbauer spectrum superimposed from a number of simple M5ssbauer patterns belonging to resonant atoms experiencing different hyperfine interactions. 

Abstract This chapter describes a general introduction of the Mossbauer spectroscopy. What is the Mossbauer effect and what is the characteristic feature of the Mossbauer spectroscopy These questions are answered briefly in this chapter. Mossbauer spectroscopy is based on recoilless emission and resonant absorption of gamma radiation by atomic nuclei. Since the electric and magnetic hyperfine interactions of Mossbauer probe atom in solids can be described from the Mossbauer spectra, the essence of experiments, the hyperfine interactions and the spectral line shape are discussed. In addition, the experiments and the new resonance technique with synchrotron radiation have been also briefly described. 

Isomeric shift phys chem Shift in the Mossbauer resonance caused by the effect of the valence of the atom on the interaction of the electron density at the nucieus with the nuclear charge. Also known as chemical shift. [r-sajmer-ik shift) isomerism chem The phenomenon whereby certain chemicai compounds have structures that are different although the compounds possess the same elemental composition. I T sam-3,riz-am I... 

Three factors may be identified as responsible for the widespread use of Mossbauer spectroscopy in both fundamental and applied research. First is the highest relative energy resolution R AE/E and rather good absolute energy resolution AE (the natural line width) (sometimes 10" eV). Secondly, the absolute selectivity of Mossbauer spectroscopy means that in each experiment a response is registered from only one isotope of the element. Thirdly, Mossbauer spectroscopy has a high sensitivity that is determined by the minimum number of resonant atoms needed to produce a detectable response. In transmission Mossbauer spectroscopy for T e, a response is given by a monolayer with an area of the order of 1 cm. Also important is the absence of any limitation on experimental conditions other than that the sample should be a solid. 

Mosshauer effect The resonance fluorescence by y-radiation of an atomic nucleus, returning from an excited state to the ground state. The resonance energy is characteristic of the chemical environment of the nucleus and Mossbauer spectroscopy may be used to yield information about this chemical environment. Used particularly in the study of Fe. Sn and Sb compounds. 

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