Backscattering Mossbauer spectroscopy

Fig. 3.19 Schematic illustration of the measurement geometry for Mossbauer spectrometers. In transmission geometry, the absorber (sample) is between the nuclear source of 14.4 keV y-rays (normally Co/Rh) and the detector. The peaks are negative features and the absorber should be thin with respect to absorption of the y-rays to minimize nonlinear effects. In emission (backscatter) Mossbauer spectroscopy, the radiation source and detector are on the same side of the sample. The peaks are positive features, corresponding to recoilless emission of 14.4 keV y-rays and conversion X-rays and electrons. For both measurement geometries Mossbauer spectra are counts per channel as a function of the Doppler velocity (normally in units of mm s relative to the mid-point of the spectrum of a-Fe in the case of Fe Mossbauer spectroscopy). MIMOS II operates in backscattering geometry circle), but the internal reference channel works in transmission mode...

The samples were characterized by using X-ray diffraction, Fourier transform infrared spectroscopy, scanning electron microscopy, 57Fe Mossbauer spectroscopy [2] and Rutherford backscattering spectrometry (RBS). 

We have briefly covered some of the important developments in structural characterization techniques. There are many other techniques such as Mossbauer spectroscopy, positron annihilation and Rutherford backscattering which have wide applications. Mossbauer spectroscopy is specially useful to investigate different oxidation states, spin-states and coordinations of metal ions, phase transitions, magnetic ordering. 

All of mentioned irradiative as well as radiationless resonant events enable us to track the Mossbauer effect thus, there is quite wide number of BMS conceptions based on a type of the detected radiation. These include CEMS, conversion X-ray Mossbauer spectroscopy (CXMS), backscattering 7-ray Mossbauer spectroscopy (BGMS), Auger electron Mossbauer spectroscopy (AEMS), and low-ener gy electron Mossbauer spectroscopy (LEEMS). Both first referred spectroscopic approaches will be further discussed. 

Finally, we should also mention the technique of Conversion Electron Mossbauer Spectroscopy (CEMS) [25], which uses the backscattered electrons from a surface produced by alternative decay processes of the excited nuclear state. This is particularly well suited to studying surfaces. 

TABLE II. Backscattering Detection in Mossbauer Spectroscopy Measurements... 

The solid-state chemical, optical, and physical properties of the RE, Y, and Sc orthophosphates have been extensively investigated by means of numerous techniques. Such studies include optical spectroscopy (Trukhin and Boatner 1997), x-ray absorption (Shuh et al. 1994), electron paramagnetic resonance (EPR) spectroscopy (Abraham et al. 1981, Boatner et al. 1981b), Mossbauer (Huray et al. 1982), Rutherford backscattering (Sales et al. 1983), and other techniques. Additionally, scanning ellipsometry has been used by Jellison and Boatner (2000) to determine the spectroscopic refractive indices of the xenotime-structure RE orthophosphates. The extensive range of studies of these orthophosphates was motivated initially by the potential application of the orthophosphates to radioactive waste disposal and subsequently by the other applications... 

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