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An oriented single crystal sample of the dichalcogen layer intercalation compound, TaS2⋅Sn, has been examined by 119Sn Mossbauer effect spectroscopy both at room temperature and over the temperature range 4.2⩽T⩽295 °K. From the angular dependence of the intensity ratio of the two components of the doublet spectrum at room temperature, as well as from the insensitivity of this ratio as a function of temperature at a fixed observational angle, it is concluded that there is a single lattice site for the tin atom in the layer structure. Comparison of the single crystal Mossbauer data with that obtained for a polycrystalline, (nearly) randomly oriented sample shows that even in the latter, there is a small residual orientation effect which must be corrected for in determining the anisotropy of the tin atom motion. From the isomer shift data it is clear that the tin atom is formally Sn2+ and acts as an electron donor to the TaS2 lattice. From the temperature dependence of the isomer shift parameter, it is infer...

A number of FeOCl Lewis base intercalation compounds have been prepared and characterized by chemical analysis, x‐ray powder diffraction, and Mossbauer spectroscopy. Detailed temperature dependent Mossbauer studies show these materials to be mixed valence compounds with electron exchange occurring on the time scale of the Mossbauer effect at temperatures above 100 K. In the magnetically ordered state the relative orientation of the EFG principal axis with respect to the magnetic field axis is a function of the nature of the intercalated material. These results indicate that a charge transfer model (as contrasted to a local interaction model) can provide an appropriate description of the guest‐host interaction in these compounds.

The infrared, Raman, and 119Sn Mossbauer spectra of seven organotin tropolonates (R2SnT2), (C6H5)SnT3, and bis tropolonatotin(IV) dichloride have been examined in detail. The diorganotin(IV) compounds have a six‐coordinate structure with the two organic ligands occupying either cis (R=CH3, C6H5, and C6H5CH2) or trans (R=C2H5, n‐C3H7, n‐C4H9) positions. Owing to the asymmetric nature of the tropolone ligand, none of these structures have a center of symmetry in the solid state and both the symmetric and asymmetric Sn–C stretching vibrations are Raman active. The temperature dependence of the recoil‐free fraction for the diorganotin(IV) tropolonates has been determined over the temperature range 78?T

Mossbauer effect studies using the 23.8 keV gamma transition in 119Sn have been carried out on the system SnS2−xSex (0⩽x⩽2) on both microcrystalline powders and single crystal samples. The composition dependence of the isomer shift parameter for the single line resonance spectrum shows that the covalency increases as x increases; the 5s electron population of tin in SnSe2 is ∼0.13 greater than it is in SnS2. From the temperature dependence of the area under the resonance curve it is possible to extract a Mossbauer lattice temperature ϑM which is only weakly dependent on composition for samples prepared in an identical manner. Single crystal orientation experiments with SnS2 and SnSe2 have been carried out at 295±1 K to investigate the anisotropy in the metal atom motion parallel and perpendicular to the crystallographic c axis (perpendicular and parallel to the easy cleavage plane). The vibrational anisotropy ratio, 〈x∥〉/〈x∥〉, is found to be 2.25 in SnS2 and 1.58 in SnSe2 at room temperature. The absolute...

The reaction of pyridine with the high‐spin Fe(III) layer compound FeOCl gives rise to well defined intercalation compounds which have previously been examined by detailed 57Fe temperature dependent Mossbauer effect studies. These studies have shown the presence of Fe(II) in the lattice resulting from electron transfer from the guest to the host species. The presence of pyridinium ion and 4,4′ bipyridine, postulated as originating from the redox intercalation process, as well as of the parent pyridine, in the host matrix, is inferred from the observation of characteristic absorptions in the infrared spectra of the intercalation compounds. Fourier transform IR spectra at 2 cm−1 resolution have been obtained at room temperature for a number of pyridine intercalates of FeOCl, and the IR spectroscopic characterization of these samples is found to be in good agreement with the results obtained from the 57 Fe Mossbauer effect studies in the temperature range 78≤T≤300 K.

The resonance absorption of 14.4 keV gamma rays in Fe57 (Mossbauer effect) has been observed in Fe(III) and Co(III) acetylacetonate, the former used as an absorber against a source of Co57 diffused into metallic chromium, the latter as a Co57 labeled source against an K4Fe(CN)6 (38%Fe57) absorber. The Fe(III) acetylacetonate absorber spectrum shows a single broad line (Γ½=1.83±0.09 mm sec—1) with an isomer shift of 0.50±0.09 mm sec—1. The Co(III) acetylacetonate source shows a complex spectrum which can be resolved into a single peak assigned to Fe(III) and a quadrupole split pair of lines assigned to Fe(II). These data are interpreted in terms of the chemical consequences following K capture in Co57, and suggest a twofold preference for the stabilization of the higher charge state in the Co(III) acetylacetonate matrix. No evidence for ionic charge states higher than 3+ is observed, and it is assumed that these species—if formed as a consequence of the prior nuclear event—have been reduced to the observed states in times short compared to 10—7 sec.

Mossbauer effect measurements have been carried out on (CH3)3SnCN in the temperature range 9°K 0) around the metal atom and show that the vibrational amplitudes involving this atom approach an isotropic behavior in the low‐temperature limit.

The hyperfine structure in the Mossbauer spectrum of Fe57 in ferrocene and in related compounds shows that the bonding of the iron atom is not affected by ring substitution. The temperature dependence of the fraction of recoil‐free absorption events in these compounds indicates that the Debye temperature is low (∼150°K) and that the optical modes make only a minor contribution to the reduction of the recoil‐free fraction at low temperature.

The Mossbauer parameters of a number of butyltin compounds have been determined in order to elucidate the relationship between molecular structure and spectroscopic properties of such species. The temperature dependence of the resonance effect magnitude (Debye–Waller factor) has been determined in the range 85

The temperature dependent asymmetry in the intensity of the two components of the Mossbauer resonance doublet in dimethyl tin difluoride can be related to the mean‐square amplitudes of vibration parallel and perpendicular to the cylindrical molecular symmetry axis, and hence to the anisotropy of the Mossbauer–Lamb faction (the Gol'danskii–Karyagin effect). With an assignment of the Δm = 1 and Δm = 0 transition in the Mossbauer spectrum based on a simple bond character description, an asymmetry ratio A = Mπ / Mσ of 0.78 ± 0.06 is derived from the Mossbauer data. This is in good agreement with the value A = 0.72 derived from precision x‐ray diffraction data on (CH3)2SnF2 and constitutes an independent check on the presence of the Gol'danskii–Karyagin effect in such solids.

Nuclear quadrupole interaction in some tin compounds has been investigated by the use of the Mossbauer effect. Stannic oxide shows a partially resolvable quadrupole splitting of 0.49±0.06 mm/sec at 1 atm pressure. The origin of the nuclear quadrupole interaction is attributed to the characteristic rutile crystal structure in SnO2. The absence of resolvable quadrupole splitting in stannic bromide and diphenyltin indicates that interpretations concerning the electric field gradient tensor based on the Mossbauer effect in 119Sn alone are not always sufficient to warrant definitive conclusions about molecular structures. It has been shown that this restriction is largely due to the relatively broad total natural linewidth for 119Sn, I=32+. Quadrupole‐splitting and isomer‐shift data for some phthalocyaninotin complexes indicate that simple correlations between chemical parameters, e.g., electronegativities, and Mossbauer parameters are not generally valid.

The Mossbauer spectra of 49 organo‐tin compounds have been studied at liquid‐nitrogen absorber temperatures, using a ceramic 119SnO2m source at room temperature with a parabolic motion spectrometer. The linear relationship between isomer shift and ligand electronegativity suggested by Goldanskii for compounds of the type SnX4 has been extended to organo‐tin compounds with mixed ligands. On the basis of the observed isomer‐shift range, the percentage of ionic character in organo‐tin compounds is estimated as lying within an interval of ±5% of a mean value of ∼15%. Binuclear tin compounds of the type R3Sn—SnR3 show no resolvable quadrupole splitting. In aryl‐tin compounds, para and meta substitution has little or no effect on the s character of the carbon—tin bond. The ratio ρ of the quadrupole splitting to the isomer shift (with respect to SnO2) has a value larger than 2.10 for compounds in which the Sn atom is sp3d hybridized or in which there is significant departure from tetrahedral symmetry, while ρ va...

The Mossbauer spectrum in a potassium ferrate absorber has been determined at 78° and 298°K using a source of Co57 in stainless steel. A single resonance line is observed with a full width at half‐maximum of 0.43 mm sec—1. This linewidth is known to arise mainly in the stainless‐steel source, which indicates that the quadrupole splitting of the resonance peak is less than 1 Mc sec—1. The isomer shift is —0.69 mm sec—1 at 78°K and —0.79 mm sec—1 at 298°K. This shift is smaller than that predicted for a 3d2 electron configuration, presumably because the 3d electron density is augmented by d3s hybridization in the tetrahedral ferrate ion.

A rapid, convenient, and reproducible method has been developed for the radioassay of volatile materials labeled with beta emitters of more than 0.15‐Mev energy. The sensitive detection element is a thin‐walled aluminum G. M. tube sealed into an annular jacket and attached directly to a high‐vacuum manifold. Analysis data for SiCl436 is presented, and application of the method to several tracer problems is suggested.

The kinetics of the isotopic chlorine exchange between SiCl4 and HCl have been measured using the tracer Cl36. The reaction is first order in HCl and second order in SiCl4. E‡ and S‡ are 22.4 K cal mole—1 and —17.6 cal deg—1 mole—1, respectively. A mechanism for the exchange is proposed.

The vibrational states of FeOCl are studied from observations of the far‐infrared absorption spectra.(AIP)