Synchrotron radiation Mössbauer spectra of a rotating absorber with implications for testing velocity and acceleration time dilation

Many Mössbauer spectroscopy (MS) experiments have used a rotating absorber in order to measure the second-order transverse Doppler (TD) shift, and to test the validity of the Einstein time dilation theory. From these experiments, one may also test the clock hypothesis (CH) and the time dilation caused by acceleration. In such experiments the absorption curves must be obtained, since it cannot be assumed that there is no broadening of the curve during the rotation. For technical reasons, it is very complicated to keep the balance of a fast rotating disk if there are moving parts on it. Thus, the Mössbauer source on a transducer should be outside the disk. Friedman and Nowik have already predicted that the X-ray beam finite size dramatically affects the MS absorption line and causes its broadening. We provide here explicit formulas to evaluate this broadening for a synchrotron Mössbauer source (SMS) beam. The broadening is linearly proportional to the rotation frequency and to the SMS beam width at the rotation axis. In addition, it is shown that the TD shift and the MS line broadening are affected by an additional factor assigned as thealignment shiftwhich is proportional to the frequency of rotation and to the distance between the X-ray beam center and the rotation axis. This new shift helps to align the disk's axis of rotation to the X-ray beam's center. To minimize the broadening, one must focus the X-ray on the axis of the rotating disk and/or to add a slit positioned at the center, to block the rays distant from the rotation axis of the disk. Our experiment, using the57Fe SMS, currently available at the Nuclear Resonance beamline (ID18) at the ESRF, with a rotating stainless steel foil, confirmed our predictions. With a slit installed at the rotation axis (reducing the effective beam width from 15.6 µm to 5.4 µm), one can measure a statistically meaningful absorption spectrum up to 300 Hz, while, without a slit, such spectra could be obtained up to 100 Hz only. Thus, both the broadening and the alignment shift are very significant and must be taken into consideration in any rotating absorber experiment. Here a method is offered to measure accurately the TD shift and to test the CH.

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Nondestructive Inspection of Thin, Low-Z Samples using Multiplexed Compton Scatter Tomography

MRS Proceedings ◽

10.1557/proc-503-297 ◽

1997 ◽

Vol 503 ◽

Cited By ~ 1

Author(s):

B. L. Evans ◽

J. B. Martin ◽

L. W. Burggraf

Keyword(s):

Signal To Noise Ratio ◽

Reconstruction Algorithm ◽

Filtered Backprojection ◽

Line Broadening ◽

Compton Scatter ◽

X Ray ◽

Tomography System ◽

Transmission Computed Tomography ◽

High Purity Germanium ◽

Scattered Energy

ABSTRACTThe viability of a Compton scattering tomography system for nondestructively inspecting thin, low Z samples for corrosion is examined. This technique differs from conventional x-ray backscatter NDI because it does not rely on narrow collimation of source and detectors to examine small volumes in the sample. Instead, photons of a single energy are backscattered from the sample and their scattered energy spectra are measured at multiple detector locations, and these spectra are then used to reconstruct an image of the object. This multiplexed Compton scatter tomography technique interrogates multiple volume elements simultaneously. Thin samples less than 1 cm thick and made of low Z materials are best imaged with gamma rays at or below 100 keV energy. At this energy, Compton line broadening becomes an important resolution limitation. An analytical model has been developed to simulate the signals collected in a demonstration system consisting of an array of planar high-purity germanium detectors. A technique for deconvolving the effects of Compton broadening and detector energy resolution from signals with additive noise is also presented. A filtered backprojection image reconstruction algorithm with similarities to that used in conventional transmission computed tomography is developed. A simulation of a 360–degree inspection gives distortion-free results. In a simulation of a single-sided inspection, a 5 mm × 5 mm corrosion flaw with 50% density is readily identified in 1-cm thick aluminum phantom when the signal to noise ratio in the data exceeds 28.

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Generalized Laue dynamical theory for x-ray reflectivity at low and high incidence angles on ideal crystals of finite size

Physical Review B ◽

10.1103/physrevb.55.105 ◽

1997 ◽

Vol 55 (1) ◽

pp. 105-112 ◽

Cited By ~ 6

Author(s):

Liberato De Caro ◽

Leander Tapfer

Keyword(s):

Finite Size ◽

Dynamical Theory ◽

X Ray ◽

High Incidence

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Eco-Friendly Nitrogen-Doped Graphene Preparation and Design for the Oxygen Reduction Reaction

Molecules ◽

10.3390/molecules26133858 ◽

2021 ◽

Vol 26 (13) ◽

pp. 3858

Author(s):

Monica Dan ◽

Adriana Vulcu ◽

Sebastian A. Porav ◽

Cristian Leostean ◽

Gheorghe Borodi ◽

...

Keyword(s):

Oxygen Reduction Reaction ◽

Oxygen Reduction ◽

Rotating Disk ◽

Reduction Reaction ◽

Machine Learning Algorithms ◽

Rotating Disk Electrode ◽

X Ray ◽

Synthesis Conditions ◽

Characterization Techniques ◽

Doped Graphene

Four N-doped graphene materials with a nitrogen content ranging from 8.34 to 13.1 wt.% are prepared by the ball milling method. This method represents an eco-friendly mechanochemical process that can be easily adapted for industrial-scale productivity and allows both the exfoliation of graphite and the synthesis of large quantities of functionalized graphene. These materials are characterized by transmission and scanning electron microscopy, thermogravimetry measurements, X-ray powder diffraction, X-ray photoelectron and Raman spectroscopy, and then, are tested towards the oxygen reduction reaction by cyclic voltammetry and rotating disk electrode methods. Their responses towards ORR are analysed in correlation with their properties and use for the best ORR catalyst identification. However, even though the mechanochemical procedure and the characterization techniques are clean and green methods (i.e., water is the only solvent used for these syntheses and investigations), they are time consuming and, generally, a low number of materials can be prepared, characterized and tested. In order to eliminate some of these limitations, the use of regression learner and reverse engineering methods are proposed for facilitating the optimization of the synthesis conditions and the materials’ design. Thus, the machine learning algorithms are applied to data containing the synthesis parameters, the results obtained from different characterization techniques and the materials response towards ORR to quickly provide predictions that allow the best synthesis conditions or the best electrocatalysts’ identification.

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Temperature-induced structural phase transitions in RERhSn (RE = Y, Gd-Tm, Lu)

Zeitschrift für Kristallographie - Crystalline Materials ◽

10.1515/zkri-2021-2008 ◽

2021 ◽

Vol 0 (0) ◽

Author(s):

Simon Engelbert ◽

Rolf-Dieter Hoffmann ◽

Jutta Kösters ◽

Steffen Klenner ◽

Rainer Pöttgen

Keyword(s):

Rare Earth ◽

Phase Transitions ◽

Driving Force ◽

Room Temperature ◽

Structural Phase ◽

Structural Phase Transitions ◽

Line Broadening ◽

X Ray Diffraction ◽

Temperature Dependent ◽

X Ray

Abstract The structures of the equiatomic stannides RERhSn with the smaller rare earth elements Y, Gd-Tm and Lu were reinvestigated on the basis of temperature-dependent single crystal X-ray diffraction data. GdRhSn crystallizes with the aristotype ZrNiAl at 293 and 90 K. For RE = Y, Tb, Ho and Er the HP-CeRuSn type (approximant with space group R3m) is already formed at room temperature, while DyRhSn adopts the HP-CeRuSn type below 280 K. TmRhSn and LuRhSn show incommensurate modulated variants with superspace groups P31m(1/3; 1/3; γ) 000 (No. 157.1.23.1) (γ = 3/8 for TmRhSn and γ = 2/5 for LuRhSn). The driving force for superstructure formation (modulation) is a strengthening of Rh–Sn bonding. The modulation is expressed in a 119Sn Mössbauer spectrum of DyRhSn at 78 K through line broadening.

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X-Ray Diffraction Study of Hep Metals. I. Line Broadening in Polycrystalline Cd Powder

Zeitschrift für Naturforschung A ◽

10.1515/zna-1974-1211 ◽

1974 ◽

Vol 29 (12) ◽

pp. 1771-1777 ◽

Cited By ~ 3

Author(s):

N. C. Haider ◽

S. H. Hunter

Keyword(s):

Room Temperature ◽

Small Deformation ◽

Correction Factors ◽

Line Broadening ◽

X Ray Diffraction ◽

Fault Probability ◽

Large Particle Size ◽

X Ray ◽

Melting Temperatures ◽

Diffraction Patterns

Powder Cd of 99.999% purity was prepared at room temperature (25 °C) and x-ray diffraction patterns were obtained using CuKaα radiation with Ni-filter. The line broadening was analyzed after incorporating the appropriate correction factors. At room temperature Cd was found to have large particle size (653 A), small root mean square strain (.001), small deformation fault probability a (.003). and negligible growth fault probability β(0). Compared to other hep metals which have been studied earlier and which have higher melting temperatures, metal Cd is much less affected by mechanical deformation at room temperature.

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Long-range internal stresses and asymmetric X-ray line-broadening in tensile-deformed [001]-orientated copper single crystals

Philosophical Magazine A ◽

10.1080/01418618608245293 ◽

1986 ◽

Vol 53 (6) ◽

pp. 793-813 ◽

Cited By ~ 216

Author(s):

H. Mughrabi ◽

T. Ungár ◽

W. Kienle ◽

M. Wilkens

Keyword(s):

Single Crystals ◽

Long Range ◽

Internal Stresses ◽

Line Broadening ◽

X Ray ◽

Copper Single Crystals

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Characteristically Asymmetric X-Ray Line Broadening, an Indication of Residual Long-Range internal Stresses

Materials Science Forum ◽

10.4028/www.scientific.net/msf.166-169.23 ◽

1994 ◽

Vol 166-169 ◽

pp. 23-44 ◽

Cited By ~ 5

Author(s):

Tamás Ungár

Keyword(s):

Long Range ◽

Internal Stresses ◽

Line Broadening ◽

X Ray

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Investigation of Residual Strains of the Second Kind in Plastically Deformed Metallic Materials

MRS Proceedings ◽

10.1557/proc-376-409 ◽

1994 ◽

Vol 376 ◽

Cited By ~ 2

Author(s):

M. Vrána ◽

P. Klimanek ◽

T. Kschidock ◽

P. Lukáš ◽

P. Mikula

Keyword(s):

High Resolution ◽

Neutron Diffraction ◽

Stacking Faults ◽

Metallic Materials ◽

Line Broadening ◽

X Ray Diffraction ◽

X Ray ◽

Neutron Diffractometer ◽

Residual Strains ◽

Good Agreement

ABSTRACTInvestigation of strongly distorted crystal structures caused by dislocations, stacking-faults etc. in both plastically deformed f.c.c. and b.c.c. metallic materials was performed by the analysis of the neutron diffraction line broadening. Measurements were realized by means of the high resolution triple-axis neutron diffractometer equipped by bent Si perfect crystals as monochromator and analyzer at the NPI Řež. The substructure parameters obtained in this manner are in good agreement with the results of X-ray diffraction analysis.

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