MoBbauer spectroscopy

The next available full-shell cluster that has been investigated by MoBbauer spectroscopy was the four-shell cluster Pt309phen 3603o+io (phen = 4,7-p-C6H4S03Na substituted 1,10-phenanthroline) [17]. Its inner core consists of 147 atoms. However, since platinum is not MoBbauer-active, the cluster sample had to be irradiated with thermal neutrons to transfer a fraction of the Pt... 

PAD (perturbed angular distribution) is a variation of PAC with nuclear excitation by a particle beam from an accelerator. QMS is quasielastic MdBbauer-spectroscopy, QNS is quasielastic neutron spectroscopy. For MOBbauer spectroscopy (MS), perturbed angular correlation (PAC), and /J-nuclear magnetic resonance (/3-NMR), the accessible SE jump frequencies are determined by the life time (rN) of the nuclear states involved in the spectroscopic process. Since NMR is a resonance method, the resonance frequency of the experiment sets the time window. With neutron scattering, the time window is determined by the possible energy resolution of the spectrometer as explained later. 

The aim of this chapter is to present a review of the high pressure optical studies on rare-earth ions in non-metallic compounds. Other methods, as for example neutron scattering, magnetic resonance techniques or MoBbauer spectroscopy will not be considered here, unless they provide additional valuable information to the optical studies. It will be demonstrated that the problem of host lattice structural dependence of 4f/v states can be effectively tackled by high pressure techniques and hopefully the interest for further, more refined high pressure studies of this problem can be stimulated. 

Coordination compounds containing the electron-donating ferrocenyl group (Fc) directly attached to a transition metal center are useful models in which the localisation of electric charges and intramolecular interactions can be studied by way of cyclic voltammetry and MoBbauer spectroscopy at the ferrocene iron, which acts as a probe. 

XSC X-ray single crystal diffraction (ADPs), XPD X-ray powder diffraction (ADPs), NSC neutron single crystal diffraction (ADPs), NPD neutron powder diffraction (ADPs), Cp heat capacity data, TC thermal conductivity data, INS inelastic neutron scattering, NIS nuclear inelastic scattering, MOE MoBbauer spectroscopy, MA microwave absorption spectroscopy, EXAFS extended X-ray absorption fine structure spectroscopy, RA Raman spectroscopy, FTE fits to thermal expansion data, ElRes fit to electrical resistivity data, RUS resonant ultrasound spectroscopy... 

The prepared materials were examined for their stoichiometry by combined TG/DTA measurements, by H-NMR spectroscopy and Fe MoBbauer spectroscopy. The results show that all adducts have a PcFe L ratio of 1 2 (see Tables 4-6) [14, 63-74]. 

Fe MoBbauer spectroscopy also confirms the hexacoordination of the iron atom. Table 6 [68-74] summarizes the MoBbauer data for some of the synthesized complexes. 

Structural analyses showed that non-leached catalysts are often dominated by decomposition products [37, 38, 41, 42,104,116,164]. In such a case, with TEM, XRD, MoBbauer spectroscopy, and EXAFS analysis, mostly metal particles, carbides, nitrides, and sometimes oxides were detected. In Fig. 16.15, a Mossbauer spectrum of an as-prepared catalyst (HT 800, 2 h at 800°C in Ar) and its acid-leached product (HT 800, washed) are shown. 

A homogeneous distribution of active sites was obtained when the phenanthroline is pyrolyzed in the presence of iron oxalate. Such catalysts exhibited an excellent performance in RDE measurements, even without sulfur addition [134]. As indicated by a change of color, already during the mixing of the precursors, a complexation of iron with phenanthroline occurs. These catalysts show similar structural features in MoBbauer spectroscopy and exhibit similar iron contents as those catalysts prepared by the oxalate-supported pyrolysis of porphyrins. 

Ohya T, Kobayashi N, Sato M (1987) Bonding character in tetracoordinate (phthalocyanato) iron(II) complexes with electron-withdrawing substituents as studied by MoBbauer spectroscopy. Inorg Chem 26 2506-2509... 

This view is supported by the detection of Fe species via MoBbauer spectroscopy [15-18]. Moreover, in order to get high conversion one had to add initiator portion by portion. The following scheme may explain the effect of the initiator on the basis of intermole-cular electron transfer ... 

The results with other metals are less advanced. The study of the iron system suggested the use of MoBbauer spectroscopy. Unfortunately, the spectra showed a very modest resolution because of the experimental conditions (c(Fe) < 8%, airtight cuvette, no enrichment of Fe-57 isotope). The spectra cannot be interpreted conclusively [24]. 

MoBbauer spectroscopy is another important method to obtain additional information about the structure of the bridged phthalocyaninatoiron compounds. The isomer shift (6) and the quadrupol splitting (AE ) have been measured for the monomer (6 = 0.11 mm/s, AE = 0.65 mm/a). The data of [PcFe(Me dib)] 6 = 0.14 mm/s and AE = O.o9 mm/s are another definite proof for the hexacoordination of tne dib-bridged compounds. 

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