Mossbauer resonance

Mossbauer resonance of Zn to study the influence of the gravitational field on electromagnetic radiation. A Ga ZnO source (4.2 K) was used at a distance of 1 m from an enriched ZnO absorber (4.2 K). A red shift of the photons by about 5% of the width of the resonance line was observed. The corresponding shift with Fe as Mossbauer isotope would be only 0.01%. The result is in accordance with Einstein s equivalence principle. Further gravitational red shift experiments using the 93.3 keV Mossbauer resonance of Zn were performed later employing a superconducting quantum interference device-based displacement sensor to detect the tiny Doppler motion of the source [66, 67]. 

Another study of the temperature dependence of the 6.2 keV Mossbauer resonance of Ta has been carried out by Salomon et al. [197] for sources of WAV metal and W/Ta metal in the temperature range from 15 to 457 K. In more recent investigations, Salomon et al. [198] have extended such studies of the temperature behavior of the 6.2 keV Mossbauer transition of Ta in tantalum metal to temperatures up to 2,300 K which has been the highest temperature range for any Mossbauer study so far. 

Ta metal Stroboscopic detection of nuclear forward scattered synchrotron radiation is used to detect the high-resolution 6.2 keV Mossbauer resonance of Ta in Ta metal... 

Nb, and V matrices plotted versus the corresponding shifts for the 77 keV Mossbauer resonance in Au. The sign of the Hg shifts has been reversed with respect to the experimental results in order to be consistent with the absorber convention. The shifts are given relative to Hgp2 and metallic gold for Hg and Au, respectively (from [483])... 

At 5 K, the spectrum is dominated (area fraction of 80%) by a singlet, typical for one of the rare cases of cubic local symmetry for low-spin Fe(II). In addition, two distinct high-spin Fe(II) doublets are observed, contributing 16 and 4%, respectively. The presence of two high-spin Fe(II) doublets together with the fact that the Mossbauer resonance lines arising from the... 

The isomer shift associated with Mossbauer resonance spectra also provides information on chemical bonding. The isomer shift is given by... 

Example Problem Calculate the natural line width of the state at 14.4 keV in 57Fe given that t1/2 = 98 ns. Then calculate the velocity of the source lattice that would correspond to twice the natural width and would lie outside the Mossbauer resonance effect ... 

A bimetallic iron tricarbonyl cation C8H9Fe2(CO)6 + (IV) is derived from cyclooctatriene (157). The Mossbauer resonance of spectrum of (IV) and the related cycloheptatrienyl-Fe2(CO)6 cation (V) (73) suggest that these cations may be considered as containing a bis(7r-allyl) and an allyl-diene system, respectively. In the second case (V), rapid valence tautomerism is invoked to account for the unique proton NMR signal in solution. 

Bargeron, C. B., Avinor, M. Drickamer, H. G. (1971) The effect of pressure on the Mossbauer resonance for 57Fe in MnS2. Inorg. Chem., 10,1338-9. 

More recently, NH FeF was studied by susceptibility and Mossbauer resonance measurements14. From an expansion series, a value of -13 K was obtained for J/k and TN = 135 K from Mossbauer data. The law of variation of the hyperfine field with temperature has the form... 

For Rb2FeF5, agreement is also observed between magnetization and Mossbauer resonance data under a high applied field202,203 232. ... 

In A2FeFj compounds (A = K, Rb, Cs) an important spin reduction has been detected by neutron diffraction202 203 and Mossbauer resonance measurements230-232. The calculations are based only on the spin-wave theory disregardering the kinematic interactions since the spin value is important. Figure 36 describes the variation of the zero-point spin reduction with the anisotropy factor a. a is here (1 - coA/(oE) 2 where mA and a E are the Larmor frequencies corresponding to the anisotropy and exchange fields, respectively. 

PROBLEM 11.26.2 If Eq. (11.26.1) gives for 26Fe57 a linear speed vr = 81.21 m/s, whereas the experimental linear speed for detecting the Mossbauer resonance is only 0.194 mm/s, what is the "effective mass" ... 

Domeneghetti MC, Steffen G (1992) Ml, M2 site populations and distortion parameters in synthetic Mg-Fe orthopyroxenes from Mossbauer spectra and X-Ray stmcture refinements. Phys Chem Min 19 298-306 Drickamer HG, Vaughn RW, Champion AR (1969) High-pressure Mossbauer resonance studies with iron-57. Accounts Chem Res 2 40-47... 

Rancourt DG, Klingelhofer G (1994) Possibility of a Mossbauer resonant-electron microscope. Fourth Seeheim Workshop on Mossbauer Spectroscopy, p 129 Rancourt DG, Mcdondd AM, Lalonde AE, Ping JY (1993) Mossbauer absorber thicknesses for accurate site populations in Fe-bearing minerals. Am Mineral 78 1-7 Riedel E, Karl R (1980) Mossbauer studies of thiospinels. 1. The system FeCr2S4-FeRh2S4. J Sol State Chem 35 77-82... 

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... 

Fig. 11. a Mossbauer resonance spectrum of CaTiojFeo.gOi o at 4.2 K. b Idealized structure of this phase, c cationic environment of the O, and 02 sites... 

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