Isotopic Effect In Extended X-Ray-Absorption Fine Structure of Germanium

Purans, J.; Afify, N. D.; Dalba, G.; Grisenti, R.; Panfilis, Simone De; Kuzmin, Alexei; Ozhogin, V. I.; Rocca, F.; Sanson, Andrea; Tiutiunnikov, S. I.; Fornasini, P.

doi:10.1103/physrevlett.100.055901

Cited by 45 publications

(43 citation statements)

References 22 publications

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“…h -=2ð k k Þ 1=2 and depends on the reduced mass. The tiny mass effect on the low-temperature DW exponent has been recently detected by EXAFS measurements on the isotopes 70 and 76 of germanium below 150 K (Purans et al, 2008).…”

Section: Einstein Modelmentioning

confidence: 99%

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On EXAFS Debye-Waller factor and recent advances

2015

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The effects of structural and vibrational disorder on the EXAFS signals are parameterized in terms of the Debye Waller (DW) factor. Here the vibrational contribution is addressed, which for most systems can be singled out by studying the temperature dependence of the EXAFS DW factor, which corresponds to a good accuracy to the parallel mean square relative displacement (MSRD) around the inter-atomic equilibrium distance. By comparing the first-shell EXAFS thermal expansion with the crystallographic thermal expansion one can evaluate the perpendicular MSRD. The results of recent measurements on copper and on several tetrahedral semiconductors are here critically compared and some properties of the MSRDs are discussed, such as the dependence of correlation, force constants and vibrational anisotropy on crystal structure and bond ionicity as well as the relative merits of the correlated Debye and Einstein models. The anharmonic contribution to the parallel MSRD of CdTe has been evaluated and a quasi-harmonic analysis has been attempted, leading to an estimation of the bond Grü neisen parameter.

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Section: Einstein Modelmentioning

confidence: 99%

“…From parallel and perpendicular MSRD one can reconstruct the ellipsoid of relative vibrations of nearestneighbour atoms (Ahmed et al, 2013;Fornasini, 2015b). The high accuracy of measurements has allowed the detection of the tiny isotopic effects on the low-temperature values of the parallel MSRD in germanium (Purans et al, 2008).…”

Section: Introductionmentioning

confidence: 99%

On EXAFS Debye-Waller factor and recent advances

2015

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“…They opened new perspectives for the understanding of phenomena connected to the local vibrational dynamics, such as negative thermal expansion 11,12 and isotopic effects. 13 GaAs is widely employed in the manufacture of electronic and optoelectronic devices, both in bulk form and as nanoparticles and nanowires. To our knowledge, the last EX-AFS study of thermal properties of bulk GaAs dates back to the 1990s and is limited to the investigation of the parallel MSRD in the temperature range from liquid nitrogen to room temperature.…”

Section: Introductionmentioning

confidence: 99%

Local vibrational properties of GaAs studied by extended X-ray absorption fine structure

Ahmed

Aquilanti

Novello

et al. 2013

The Journal of Chemical Physics

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Extended X-ray absorption fine structure (EXAFS) has been measured at both the K edges of gallium and arsenic in GaAs, from 14 to 300 K, to investigate the local vibrational and thermodynamic behaviour in terms of bond expansion, parallel, and perpendicular mean square relative displacements and third cumulant. The separate analysis of the two edges allows a self-consistent check of the results and suggests that a residual influence of Ga EXAFS at the As edge cannot be excluded. The relation between bond expansion, lattice expansion, and expansion due to anharmonicity of the effective potential is quantitatively clarified. The comparison with previous EXAFS results on other crystals with the diamond or zincblende structure shows that the values of a number of parameters determined from EXAFS are clearly correlated with the fractional ionicity and with the strength and temperature interval of the lattice negative expansion. © 2013 AIP Publishing LLC.

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“…The temperature dependences of the MSRDs determined within the two force-field models are compared with that obtained from the experimental EXAFS data [1,2] in Fig. Figure 1.…”

Section: Resultsmentioning

confidence: 99%

“…The accurate analysis of the Ge K-edge extended xray absorption fine structure (EXAFS) in germanium is a long standing problem due to the presence of multiplescattering (MS) contributions, which strongly influences the "classical" EXAFS analysis based on the singlescattering (SS) approach [1]. Our previous analysis [2] of thermal effects in the two isotopes of 70 Ge and 76 Ge within the first three coordination shells has been performed using both SS and MS models.…”

Section: Introductionmentioning

confidence: 99%