J.M. Trooster

Analysis of57Fe Mössbauer hyperfine spectra

It is emphasized that Mössbauer spectra of57Fe nuclei subjected to a combined magnetic dipole- and electric quadrupole interaction cannot give a unique solution for all parameters involved in these interactions, even if intensities are taken into account. Expressions are derived with which the full range of possible solutions can be calculated and we apply these to some recently published results in which the ambiguity was not recognized.

Removal of X-ray satellites from Mg Kα excited photoelectron spectra

Abstract A numerical method is described to remove X-ray satellite lines from photoelectron spectra excited with Mg K α radiation. The satellite intensity

An X-ray photoelectron spectroscopy of PdSb, PtBi and AuSn

The alloys PdSb, PtBi and AuSn as well as the pure constituent metals have been studied with X-ray photoelectron spectroscopy (XPS). The d bands of Pd, Pt and Au reduce in width and shift to higher binding energies on alloying. A relatively high electron density of states (DOS) at the Fermi level persists in PtBi, indicating an important contribution of the Pt 5d electrons to the DOS at the Fermi level. Relating XPS and Auger shifts on alloying, values for the screened two-hole Coulomb interaction in Pd, Sn and Sb were derived. Both for the pure metals and the alloys the measured intensities of the XPS lines are compared with theoretical cross sections. In general, good agreement is found except for the outer electron levels for which the theoretical cross sections are too low.

Application of an integrating counting method to Mössbauer spectroscopy of gold

Abstract It is shown that by an integrating counting method the acquisition speed of Mossbauer spectra of 197 Au is considerably increased at the expense of a relatively small loss in absorption intensity.

The resolution obtainable in X-ray photoelectron spectroscopy with unmonochromatized Mg Kα radiation

Abstract The resolution obtainable in photoelectron spectra excited with unmonochromatized Mg K α radiation is discussed and the various contributions to the instrumental resolution function considered; theoretical estimates are given. Experimental results are compared with theory. It is found that the instrumental resolution is 0.64 eV for a pass energy of 50 eV, with a lower limit of 0.57 ± 0.03 eV owing to the width of the exciting Mg K α 1,2 radiation. However, the measured resolution is not much less than the values quoted for monochromator-equipped spectrometers.

A Mössbauer study of gold(I) and gold(III) dithiolate complexes related to anti-arthritic drugs

Abstract The sensitivity of the 197 Au Mossbauer isomer shift and quadrupole splitting to gold oxidation state has enabled characterization of new stable, water—soluble Au(I) and Au(III) complexes of dimercaptosuccinic acid. The Au(I) complex exhibits a curious asymmetric line—broadening effect. Comparisons are also made with dimercaptopropanol and dithiocarbamate complexes. Relationships to existing and potential gold drugs are discussed.

Slow electronic spin relaxation in high spin hexakis(pyridine-N-oxide)iron(II)perchlorate

Abstract Hexakis(pyridine-N-oxide)iron(II)perchlorate Fe(C6H5NO)6(ClO4)2, has been studied by 57Fe Mossbauer spectroscopy at temperatures between 0.4 and 4.2 K and at 297 K, in external magnetic fields up to 2 T. Below the ordering temperature of 0.72 K the spectrum consists of a magnetic hyperfine pattern. The Mossbauer spectra recorded between 0.72 K and 4.2 K show slow relaxation phenomena. These spectra have been fitted with a simple stochastic electronic spin relaxation model, assuming the presence of two components, each characterized by considerably different relaxation rates. Similar measurements on the diluted compounds FexZn1−x(C6H5NO)6(ClO4)2 show that spin-pin interactions dominate the relaxation process between the two electronic ground state levels of the high spin Fe2− ion. It is demonstrated, that the magnitude of the zero field splitting of the ground state doublet determines the relaxation rate.

Antimony-121 Mössbauer spectroscopic studies of antimony dithiocarbamate complexes

Fifteen antimony dithiocarbamate complexes and five related complexes have been studied using 121Sb Mossbauer spectroscopy. These include the series Sb(S2CNEt2)3–nXn(X = Cl, Br, or I; n= 0–3), SbRn(S2CNEt2)3–n(R = Me or Ph; n= 1 or 2), Sb(S2CNBu2)3, Sb(S2CNBu2)2L (L = 0.5Cd2I6 or I3), SbMe4(S2CNEt2), and SbMe3(S2CNMe2)2. Isomer shifts, quadrupole-coupling constants, and asymmetry parameters are used to discuss the antimony–ligand bonds and the structure. Four of the complexes studied contain SbV, while the others contain SbIII. The sterically active lone-pair electrons are quite important in understanding the bonding and structural properties of the antimony(III) complexes.

Synthesis and 121Sb Mössbauer study of a number of organoantimony(III) compounds containing antimony-main group V element bonds

Abstract The synthesis of organoantimony(III) compounds of the type R 2 SbMR′ 2 in which R,R′=Et or Ph and M=N, P or As has been investigated. Diphenylaminodiethylstibine and diphenylaminodiphenylstibine were successfully synthesized. Attempts to prepare phosphinostibines and arsinostibines of the type R 2 SbMR′ 2 (M=P, As) failed and resulted in the formation of the corresponding diphosphines, diarsines, and distibines Only in the case of the synthesis of Ph 2 AsSbPh 2 was an analytically pure product obtained. A series of antimony(III) compounds containing antimony-main group V element bonds has been investigated by 121 Sb Mossbauer spectroscopy. The near consistency in the isomer shift (−4.0 to −4.6 mm/s relative to InSb) implies almost no change in the s-character in the total antimony-ligand bonds. Variation in the values of the quadrupole coupling constant and the asymmetry factor are discussed in terms of structure and/or changes in the p-character of the antimony-ligand bonds.

A 3He cooling system for Mössbauer experiments

Abstract A cooling system is described which consists of a 4 He bath cryostat suitable for Mossbauer measurements, provided with a 3 He insert. The insert is a closed circuit and is operated with an adsorption pump. The operation cycle is 15 h at a minimum sample temperature of (0.38 ± 0.01) K. By controlled heating of the pump higher temperatures can be obtained, with an accuracy of 0.002 K. 151 Eu Mossbauer experiments on EuSO 4 are used to obtain an independent temperature calibration. The size of the insert is such, that it can be placed in the bore of a small superconducting magnet on the bottom of the cryostat.