S. Bukshpan

ISOMER-SHIFTS OF I-129 IMPURITIES IMPLANTED IN SEMICONDUCTORS

Mössbauer spectra of the 27.8 keV transition in129I have been measured with sources of129mTe implanted in α- and β-tin and α- and β-SiC. The spectra mainly show two single line components, just as those obtained in earlier investigations with sources of129mTe implanted in diamond, silicon and germanium. The component with isomer shift corresponding to a decreased s-electron density relative to the I− ion is attributed to the substitutionally implanted impurities, that with shift corresponding to an increased s-electron density to interstitial impurities. Plots of the shifts of both component show a linear dependence on the lattice constant for diamond, silicon and germanium and α-tin. For SiC, however, the shifts are considerably smaller than expected on the basis of this linear dependence. All shifts can be quantitatively understood on the basis of a simple model that attributes the shifts of the interstitial impurities to a compression in the host lattice and shifts of the substitutional impurities to the combined effect of compression and hybridized bonding.

MOSSBAUER-SPECTROSCOPY OF KRF2 AND KRF2.MF5(M=AS,SB)

Mossbauer spectra of KrF2 and the recently synthesized compounds α‐ and β‐ [KrF]+[AsF6]− and [KrF]+[SbF6]− have been measured using the 9.4 keV transition of 83Kr produced in the decay of an 83RbF source. The results for the values of quadrupole coupling strengths and the isomer shifts indicate that the Kr–F bonding in all compounds studied is very similar. A slight increase of the quadrupole coupling in going from KrF2 to F–Kr–F–MF5 can be interpreted in terms of a shortening of the average Kr–F bond length. A very accurate value, Qex/Qgr=1.958±0.002 for the ratio of the quadrupole moments of the 9.4 keV state and the ground state has also been derived from the measurements.

MOSSBAUER STUDIES OF KR-83 IMPLANTED IN SEMICONDUCTORS AND METALS

Mössbauer spectroscopy of the 9.4 keV transition in83Kr has been performed using sources of83Rb implanted in the group IV semiconductors diamond, silicon, germanium and tin and in the metals Cu, Ag, Au, Mo and W. From the line widths and isomer shifts information has been obtained on possible lattice sites of the impurities. In most cases a site with large isomer shift, thought to correspond to a compression of the krypton atom was observed. This site is interpreted to represent purely substitutional impurities. In Mo and W a well-defined vacancy release stage was observed, leading to a reduction of the isomer shift and a line broadening.