Rayleigh Scattering Of Mossbauer Radiation Research Articles

Synchrotron radiation 57Fe-Mössbauer spectroscopy using nuclear monochromator

A synchrotron radiation (SR) Mossbauer spectrometer has been developed by using a nuclear Bragg monochromator (NBM). It enables energy-domain 57Fe SR-Mossbauer spectroscopy (SRMS). Doppler-shifted SR-Mossbauer radiation is produced by pure nuclear Bragg reflection (PNBR) from an oscillating 57FeBO3 crystal near the Neel point. In this paper, we describe the optics and its applications, including high-pressure SRMS, grazing incidence SRMS and γ-ray diffraction studies with the Rayleigh scattering of Mossbauer radiation (RSMR) method.

Application of semiconductor detector for recording the Rayleigh scattering of Mössbauer radiation

The method of the Rayleigh scattering of Mossbauer radiation (RSMR) for the study of dynamics of atoms in polystyrene demonstrating advantages of the application of the semiconductor Si-PIN detector (Amptek Inc.) was used for recording scattered radiation. It has been shown that for recording the RSMR spectra the semiconductor detector can be much more suitable than other types of detection because of the increased quality of spectra under the same collimating conditions. The dependence of probability of the Rayleigh elastic scattering fR on the scattering angle was obtained. By means of the RSMR method the scattering was studied within the angle range at the main Bragg maximum of a polystyrene sample which corresponds to the distance d = 4.44 A approximately equal to the distance between the polymer chains. Keywords: Mossbauer spectroscopy, Rayleigh scattering, detector, dynamics of atoms

Mössbauer acquisition system for Rayleigh scattering experiments

A data acquisition system is reported with a number of improvements over similar systems currently used in Rayleigh scattering of Mössbauer radiation (RSMR) experiments. It is based on a data acquisition board including a Mössbauer function generator with adjustable frequency reference signal delivery, an internal single channel analyzer, and an internal 32 kB random access memory for data storage. The system performances were tested in RSMR measurements on pyrolytic graphite C (002) single crystal by using an iron enriched 57Fe (30 at. %) in rhodium matrix absorber. We want to demonstrate that the reported data acquisition system is suitable for the experimental separation of the elastic and inelastic components of the scattered radiation. The system can be used also in the ordinary Mössbauer measurements as a compact and rapid data acquisition system. In this case it presents the advantage of including also the function generator.

Rayleigh Scattering of Mössbauer Radiation in Hydrated Amylose

The Rayleigh Scattering of Mossbauer Radiation (RSMR) has been used to investigate the temperature dependence of the dynamics of hydrated amylose, one of the saccharide components of starch. The mean square atomic displacements measured from 80 K to 300 K indicate the existence of a “glass-like” dynamic transition at about 220 K, similar to that observed in other biopolymers as for instance globular proteins. The RSMR results have been compared to those obtained by elastic neutron scattering measurements on the same samples.

Effect of hydration on the dynamics of polymeric cation exchangers and polymeric sorbent inferred from the Rayleigh scattering of Mössbauer radiation

Dependences of the dynamics of hydrophilic polymeric nets of acrylate cation exchanger, sulfonated poly(styrenedivinylbenzene) cation exchanger, and hydrophobic poly(divinylbenzeneethylstyrene) sorbent on the degree of hydration were studied by the Rayleigh scattering of Mossbauer radiation (RSMR). Dependences of the integral elastic fraction of RSMR of the polymer—water systems on the water/polymer mass ratio were determined. In the case of the cation exchangers, a considerable decrease in the elastic fraction of RSMR of the polymer during hydration was established. A considerable increase in the mobility of the nets indicates their transition from a glassy state to an elastic state. It was established that the intramolecular mobility of the hydrophobic polymeric sorbent remains unchanged during its hydration, and it contains water culsters with the nonzero elastic fraction of RSMR in its finest pores.

Rayleigh scattering of Mössbauer radiation in oriented fibres of hydrated biopolymers

The Rayleigh scattering of Mossbauer radiation (RSMR) has been measured on films of highly oriented hydrated polynucleotides (A-NaDNA) and polysaccharides (Na-hyaluronate). Both DNA and hyaluronate (HA) have helical secondary structures with a similar pitch (28.2 A for A-DNA, and 32.8 A for Na-HA), but they differ in the basic elements which make up the helices and in the extent of water-biopolymer interactions. These differences are responsible for the diverse stiffness of the polymer backbone, and also affect the dynamics of the first hydration layers. For both samples the elastic scattering intensity shows a sharp peak at about 2 A−1 only for samples oriented withQ parallel to the fibre direction. Its position is close to that of the first maximum in the structure factor of bulk water; it is, however, much narrower than in pure H2O and it is similar to a crystalline Bragg peak. It can be attributed to an ordered structure of water along the double helices. From the temperature dependence of the elastic intensity under the peak maximum, the mean square displacement of water oxygens in the direction parallel to the helices has been deduced. The thermal diffuse scattering intensity is also peaked at the sameQ values of the elastic intensity, indicating the presence of coherent vibrational excitations propagating along the ordered water filaments.

Molecular dynamics of agarose gels investigated by NMR and rayleigh scattering of Mössbauer radiation

NMR, X-ray and Rayleigh scattering of Mossbauer radiation (RSMR) measurements have been performed on agarose-water systems for different levels of water content. The NMR data provided information on the relaxation rates of protons in both polysaccharide and solvent. The RSMR measurement allowed us to determine the mean square atomic displacements as a function of the scattering vector. The values of carbon and oxygen atoms are larger when measured at distances corresponding to the helix diameter than along the chain bonds. At low hydration levels, the water molecules closely associated to the polysaccharide chains follow the dynamics of the polymer. A marked change in the dynamics of both polymer and water has been evidenced when the water weight exceeds 20% of the total weight of the sample.

Rayleigh scattering of Mössbauer radiation (RSMR) in human serum albumin

Abstract. Measurements of Rayleigh Scattering of Mossbauer Radiation have been performed in Human Serum Albumin at different hydrations. Radial distribution function were ob tained from the total and elastic intensities. The values of the mean square displacement have been deduced.