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Photoemission from the CsCl structure, n-type semiconductor CsAu confirms the presence of an adsorbed Cs layer on films produced by vapor phase reaction between bulk Au and Cs vapor. Cs 4d and 5p spectra yield a well-defined Cs core-electron binding-energy shift of −0.58 ± 0.06 eV for this layer relative to the Cs in bulk CsAu. The Au 4f and 5d spectra do not exhibit a measurable surface-atom binding-energy shift. Annealing of reacted CsAu films produced by the reaction of Au(100) with Cs vapor show ordered diffraction patterns that are coverage dependent.

Photoemission spectra of CaxC60, SrxC60, and BaxC60 show successive filling of the tlu-derived LUMO and the tlg-derived LUMO + 1 bands, for 0 < x < 6. For x < 2 compounds of Ca and Ba exhibit a well defined Fermi cut-off; compounds of Sr do not. In this range of composition, the resistivity remains activated, suggesting that the metallic character in photoemission is due to a surface phase. Stoichiometric compounds with formula A3C60 differ in both structure and electronic properties. The Ca compound retains the fcc stacking of C60, and is an insulator. The Sr compound transforms partially to the A15 structure but remains an insulator. The Ba compound has the A15 structure and is weakly metallic. For 3 < x < 6 metallic behavior is weak in the Ca and Sr compounds, but well defined in the Ba compound, indicating that the LUMO + 1 band is filled progressively by Ba. This is in accord with the superconductivity of these systems, which is found in compounds with x near 5, when the Fermi level is in the tlg band.

Surface-ion core-level shifts from evaporated films of K, Rb, and Cs chlorides, bromides and iodides have been identified in high resolution photoemission spectra. The measured shifts of the alkali-metal surface ions in the six NaCl-structure compounds average 0.45 ± 0.03 eV to higher binding energy. Subtracting from these shifts the change in Madelung potential at the surface gives the corresponding change in the surface polarization energies, averaging 0.17 ± 0.02 eV. Shifts of the halide surface ions are found to be significantly smaller. All of these results are in qualitative agreement with theoretical expectations of surface Madelung potential and polarization energy changes, both of which are positive for the cation but of opposite sign for the anion. The data from the Cs compounds have a much larger scatter due to the polymorphism upon thin film growth.

Layers of C 60 deposited on W(100) show charge donation into the LUMO of the molecules in contact with the metal surface, but there is no evidence for formation of a bulk compound. We present a simple formulation which accounts for the known successes and failures in metal−C 60 compound formation. Hypothetical compounds with the transition metals are unstable against precipitation of the metal clusters.

Photoemission spectra from thin films of ${\mathrm{K}}_{\mathit{x}}$${\mathrm{C}}_{60}$ prepared by vapor-phase reaction of ${\mathrm{C}}_{60}$ with K vapor consist of superpositions of distinct bulk and surface contributions. The spectra of ${\mathrm{K}}_{3}$${\mathrm{C}}_{60}$ and ${\mathrm{K}}_{6}$${\mathrm{C}}_{60}$ are identified and shown to be in very good agreement with band-structure calculations. The surface layer of molecules does not contribute to the metallic conductivity for any bulk composition.

Compounds of the form BaxC60 with x=3 and 6 resulting from the reaction of C60 with Ba have been prepared and characterized by photoemission. For x=3 the t1u band derived from the LUMO fo C60 is filled, resulting in an electronic structure similar to that of K6C60. Upon further exposure to Ba, the t1g band becomes occupied, but the system remains metallic at the largest Ba concentration that could be achieved. The superconductivity is associated with the t1g band.

Photoemission spectra of vacuum deposited layers of C 60 , before and after exposure to K vapor, show that the K donates its conduction electron into the band derived from the lowest unoccupied molecular orbital. A compound with composition of K 3 C 60 , corresponding to the maximum conductivity, has been prepared. In it the potassium atoms presumably occupy both the octahedral and the two tetrahedral interstitial sites of the face-centered-cubic (fcc) C 60 structure.

Photoemission data on alkali-doped C 60 are reinterpreted in the light of the finding that the electron mean free path (escape depth) in typical experiments is comparable to or less than the diameter of the molecular unit. Data are consequently dominated by the signal from the surface layer of molecules which have distinct electronic properties. This accounts for the weakness of the Fermi cut-off found in all photoemission studies.

High resolution 4f photoemission spectra from clean W(110) show that the natural lifetime width and the singularity index, which characterizes the conduction electron screening, are both larger in the first atomic layer than in the bulk. The phonon broadening of the surface and bulk components are smaller than earlier theoretical estimates. The excess broadening at the surface is compatible with a simple Debye model. These findings are very different from the interpretation previously given surface-atom core-level line shapes and have implications extending to other systems.

We investigate the electron affinity of aluminum nitride surfaces prepared by nitrogen sputtering and annealing via x-ray, ultraviolet, and inverse photoemission spectroscopy. The combination of these techniques leads to a precise determination of the relative positions of the Fermi level, valence-band maximum, conduction-band minimum, and vacuum level at the semiconductor surface. We demonstrate that, in spite of the presence of a sharp photoemission onset feature previously associated with negative electron affinity, the electron affinity is clearly positive on these surfaces.

Photoemission spectra of vacuum deposited layers of C(60), before and after exposure to K vapor, show that the K donates its conduction electron into the band derived from the lowest unoccupied molecular orbital. A compound with composition of K(3)C(60), corresponding to the maximum conductivity, has been prepared. In it the potassium atoms presumably occupy both the octahedral and the two tetrahedral interstitial sites of the face-centered-cubic (fcc) C(60) structure.

Rb 4p core-electron photoemission spectra obtained with He II resonance radiation exhibit a well-resolved response from the first atomic layer of atoms. The surface-atom core-level shift is 190 ± 3 meV, and the singularity index of the conduction electron screening response is 0.205 ± 0.005. Within the quoted experimental uncertainties both are identical to those of Na. The phonon broadenings at 100K are 65 meV for the bulk and 85 meV for the surface, showing the enhanced vibrational broadening at the surface previously found in Na.

The (7×7) reconstructed (1 1 1) surface of silicon is found to be an excellent surface for the nucleation of epitaxial aluminum nitride, despite the +23.4% misfit in the AlN/Si system. AlN nucleated above the (7×7) to (1×1) transition temperature (830°C) is found to contain 30° misoriented grains, while films nucleated below the transition temperature are single orientation. Optimized aluminum nitride films grown on (7×7) silicon surfaces make excellent substrates for GaN heteroepitaxy.

Complex faceted features of micrometer sizes and with intense luminescence rise 200-300 nm above the surface of a GaN thin film grown by molecular beam epitaxy on (0001) sapphire. Cathodoluminescence measurements at room temperature and at 8K were used to investigate the luminescence properties of these microfeatures in comparison with those of the background GaN material. The morphology of the micro-features was studied by scanning electron microscopy and by atomic force microscopy.GaN and related compounds have been considered as promising materials for light emitting devices in the short wavelength visible and UV spectral regions because of their direct, wide band gaps and high luminescence efficiency. Remarkable, rapid success has been achieved in developing devices based on III-V nitrides, which allows these material systems to rival other systems under development [1]. Blue-green LEDs fabricated from InGaN/AlGaN double-heterostructure layers on sapphire substrates by Nichia Chemical Industries in Japan are commercially available, despite the presence of high extended defect densities in the 1010 /cm2 range [2]. In December 1995, an important milestone in the development of nitride lasers was reached; Nakamura et al. in Nichia demonstrated the first nitride-based laser diode which operated at 417 nm under pulsed conditions at room temperature [3].The morphology and spatial distribution of luminescence in GaN thin films have been investigated by several research groups [4], [5], [6], although most efforts have been directed to developing appropriate growth conditions for improved film quality. From observations by scanning electron microscopy (SEM) and atomic force microscopy (AFM), Trager-Cowan et al. described an MBE-grown GaN film which contained an assembly of oriented hexagonal crystallites rising above a background of polycrystalline or amorphous material [4]. All the crystallites, oriented in a similar fashion, had roughly the same sizes, 1 or 2 μm across a hexagonal face and about 1 μm high. These crystallites were much brighter than the surrounding background material in panchromatic low-temperature cathodoluminescence (CL) images. Trager-Cowan et al. concluded that the crystallites were of better quality than the background material. They also observed a green emission band, attributed to impurities, which became weaker for higher electron beam voltages, generating luminescence from deeper in the film. From this observation, they concluded that higher quality material is located closer to the film's outer surface. Spatial variation of the luminescence efficiency from MOCVD-grown films has also been observed by Ponce et al[5]. in their room-temperature CL microscopy studies. Their results showed significant nonuniformities in both the band-edge and yellow band emissions. Although they reported no faceted island structures, one of their samples had “marked surface features” and consisted of hexagonal crystals 10 to 50 μm in diameter. The crystals gave strong band-to-band (364 nm) luminescence.In this paper, the morphology of a GaN film grown on (0001) sapphire by MBE is characterized by SEM and AFM, and CL measurements are used to investigate the luminescence properties of the film at room temperature and at 8K. Some regions of this film are similar to the one described by Trager-Cowan et al. [4] in having micron sized, brightly luminescent islands. The hexagonal facet angles and bright luminescence of islands in our film also resemble the larger scale, more regularly shaped hexagonal crystals of Ponce et al. [5]. These regions lie on the boundary of excess gallium growth conditions. Our results differ from those of Trager-Cowan in terms of the island morphologies and the spectral character of luminescence from the islands and from the background material. Possible causes of the large variations in luminescence efficiency are discussed.

We have used plasma molecular beam epitaxy on (0001) and (000 % % MathType!MTEF!2!1!+- % feaahqart1ev3aaatCvAUfeBSjuyZL2yd9gzLbvyNv2CaerbuLwBLn % hiov2DGi1BTfMBaeXatLxBI9gBaerbd9wDYLwzYbItLDharqqtubsr % 4rNCHbGeaGqiVu0Je9sqqrpepC0xbbL8F4rqqrFfpeea0xe9Lq-Jc9 % vqaqpepm0xbba9pwe9Q8fs0-yqaqpepae9pg0FirpepeKkFr0xfr-x % fr-xb9adbaqaaeGaciGaaiaabeqaamaabaabaaGcbaGabGymayaara % aaaa!36C6! $$\bar 1$$ ) ZnO substrates to induce epitaxial growth of GaN of a known polarity. The polarity of the ZnO substrates can be easily and unambiguously determined by measuring the sign of the piezoelectric coefficient. If we assume that N-face GaN grows on O face ZnO and that Ga-face GaN grows on Zn face ZnO, then we can study the growth of both Ga and N faces. The most striking difference is the doping behavior of the two faces. Growth on the Ga-face is characterized by a higher carrier concentration and a lower threshold for Ga droplet formation.

Valence-band photoemission spectra from a variety of alkali halides are shown to be well represented by a phonon-broadened density-of-states histogram with well-determined bandwidths and three or four main peaks. The bandwidths are generally in good agreement with band-structure calculations. The phonon broadening is typically 85% of that calculated for anion core levels, indicating that the valence-band holes are localized.

We report the use of ScAlMgO4 as a substrate for the epitaxial growth of wurzitic GaN. The low misfit (+1.8%) allows coherent epitaxy of GaN, as observed by RHEED. The congruent melting of ScAlMgO4 makes Czochralski growth possible, suggesting that large, high quality substrates can be realized. Boules about 17mm in diameter are reported. We have used nitrogen-plasma molecular beam epitaxy to grow GaN epitaxial films onto ScAlMgO4 substrates. Band-gap photoluminescence has been observed from some of these films, depending primarily on the deposition conditions. A 3×3 superstructure has been observed by RHEED on the GaN surfaces. Structural analysis by x-ray diffraction indicates very good in-plane alignment of the GaN films. We also report thermal expansion measurements for ScAlMgO4.

Photoemission spectra of compounds prepared by the reaction of C(60) films with calcium show two distinct metallic phases, whereas alkali-doped C(60) films have only one. In the first phase the bulk t(1u) band, derived from the lowest unoccupied molecular orbital of C(60), is partially occupied. This is followed by an insulating phase that has the composition Ca(3)C(60) in which the t(1u) band is filled and has properties analogous to those of K(6)C(60). Continued exposure to calcium produces a second metallic phase in which electrons are donated into the t(1g) band. The superconductivity of Ca(5)C(60) is associated with the t(1g) band.

High-resolution photoemission spectra from the shallow core levels of alkali metals and of In have been obtained between 78 K and room temperature. The data yield values for the alkali-metal surface-atom core-level shift and show thermal shifts of comparable size for bulk and surface. The positive surface shifts are due to the spill-out of conduction-electron charge, which is responsible for the surface dipole layer. The surface shifts are in good agreement with values obtained from a Born-Haber cycle expressed in terms of surface energies. The thermal shifts are proportional to the lattice expansion, and arise from both initial-state and final-state effects. As the lattice expands, the Fermi level decreases, decreasing the core-electron binding energy. At the same time, the expansion of the conduction-electron charge increases {ital r}{sub {ital s}}, thereby decreasing the potential at the core level and increasing the binding energy. The expansion also decreases the relaxation energy, further increasing the core-electron binding energy. In the alkali metals, the combined potential- and relaxation-energy terms dominate the Fermi-level term, making the shifts positive. In divalent metals the three terms tend to cancel, while in trivalent metals it is the Fermi-level term that dominates, making the shifts negative.

In Cs 5p core-electron photoemission spectra obtained with He resonance radiation, the response from the first atomic layer is well resolved and shifted 228 meV from the bulk line at 11.79 eV. The singularity index of the conduction-electron screening response is 0.18, i.e., comparable to the values close to 0.20 obtained for the other alkali metals. In contrast, the edge exponent of the Cs 5p absorption edge is only 1/6 that of the Na 2p edge and is incompatible with the phase shifts deduced from the Cs singularity index. This result sharpens a long-standing problem regarding the interpretation of the emission and absorption edges.

We have studied submonolayer adsorption, at room temperature, of iodine on the (111) faces of silver and copper, using LEED and XPS. In both systems the √3 × √3 LEED pattern appears at ∼0.2 monolayer (ML) coverage; no other superlattice pattern was observed. The I 4 d 5 2 core electron binding energy in both cases decreases by ∼0.15 eV between very dilute coverage and 0.33 ML. The leveling-off of the binding energy for I/Ag(111) for coverages >0.2 ML is shown to be a unique experimental manifestation of an indirect, substrate-mediated adatom-adatom interaction, an attraction of several meV between next-nearest neighbor iodine atoms. The more nearly linear decrease in the I binding energy on Cu(111) is shown to imply a significantly weaker next-nearest neighbor interaction on this surface. The appearance of the √3 × √3 LEED pattern at low coverages on Cu is shown to be consistent with short-range order produced merely by a size effect, that is, by nearest neighbor exclusion. These conclusions are reached with the help of Monte Carlo calculations of a triangular lattice gas.

An x-ray photoemission spectroscopy study of the blue molybdenum bronze ${\mathrm{K}}_{0.30}$${\mathrm{MoO}}_{3}$ shows a conduction band of Mo 4d character extending 2 eV below the Fermi level. The valence band lies between 2 and 10 eV. The Mo 3d core-electron spectrum has components at binding energies previously identified with ${\mathrm{Mo}}^{5+}$ and ${\mathrm{Mo}}^{6+}$ ions in related molybdenum oxide compounds. In this metallic system these two states are, however, of final-state origin, representing alternate screening channels and do not indicate that discrete valences are present in the initial state.

A comparison of photoemission data and linear augmented-plane-wave results for ${\mathrm{Cu}}_{3}$Au serves to elucidate the Au partial density of states.

The multicomponent structure of the $3d$ x-ray photoemission spectra of the light rare-earth metals is elucidated in terms of recent x-ray absorption and appearance-potential spectroscopy results for these materials. Both multiplet splitting due to $3d\ensuremath{-}4f$ exchange and satellite structure due to two competing screening mechanisms are identified. The main component of the $3d$ line arises when the core hole is screened by $5d$ conduction electrons; the satellite from a $4{f}^{n}\ensuremath{\rightarrow}4{f}^{n+1}$ process. The satellites in the metals occur at lower binding energies because the empty $4f$ level falls below the Fermi energy. This interpretation is supported by an "equivalent cores" argument.

X-ray photoemission spectra of the band structures of WO3, crystalline HxWO3 and the tetragonal and cubic bronzes MxWO3 (M=Li, Na) exhibit great similarity. In the bronzes tungsten 5d conduction band states are occupied. The tungsten 4f core level spectra of these materials have an unusual, but characteristic structure attributed to a combination of final state screening and hydrogen or alkali ion neighbor effects. The band structure of amorphous electrochromic WO3 films differs in characteristic ways from that of the crystalline bronzes.

Small tin clusters supported on amorphous carbon substrates were studied by X-ray photoelectron spectroscopy for comparison with earlier work on noble and transition metals in order to assess the role of the d -band in core electron binding energy shifts. Comparable shifts are found in all cases, indicating that they have their origin in the net unit positive charge due to the emission of a photoelectron, which remains on cluster during the life time of the core hole. The limiting value of this shift in the smallest clusters is given by the metallic screening energy.

The growth and composition of cesium-tin and cesium-gold compounds were investigated. A quartz crystal oscillator thickness gauge was used to measure the total mass as cesium vapor was allowed to diffuse into and react with an evaporated layer of tin or gold. Equiatomic compounds of CsSn and CsAu were produced.

Photoemission spectra of the 4d level of metallic tin, taken with 90 meV resolution exhibit crystal field splittings of the j= 3 2 and 5 2 spin-orbit components amounting to 115 and 146 meV, respectively. The room temperature phonon broadening is approximately 50 meV, in good agreement with a recent theoretical estimate.

Mean free paths for inelastic scattering (λ) of low energy electrons in poly(methylmethacrylate) (PMMA) have been determined by measuring Al Kα excited C 1s and Si 2s photoelectron signal intensities as a function of ellipsometrically determined thicknesses of PMMA overlayers on silicon substrates. The λ values obtained are 29 ± 4 A for 1196 eV electrons and 33 ± 5 A for 1328 eV electrons. These data are necessary for the quantitative analysis of the surface region of PMMA and similar polymers by X-ray photoelectron spectroscopy (XPS). The magnitude of the λ values determined indicates that XPS measurements can provide chemical information about the surface region of polymers, such as PMMA, in the depth range of ∼6 to 100 A. The results of this study are compared and discussed with respect to λ values determined for other organic compounds.

Guided by the criteria of strong oxygen affinity and strong tendency toward surface segregation over Nb, artificial tunnel barriers of thin Mg(10-65 A), and Y(4-30 A) overlayers on Nb were investigated. Very high-quality tunnel junctions of the types Nb/Mg-oxide/Pb 0.9 Bi 0.1 and Nb/Y-oxide/Pb 0.9 Bi 0.1 were obtained, particularly in the latter case, with Δ Nb of 1.57 meV and excess conduction at 2 mV to be 1.4 × 10-3of that at 4 mV. As characterized by the XPS technique, Mg and Y overlayers as thin as 10 A are sufficient to protect the underlying Nb film from oxidation. The Mg-oxide and Y-oxide formed on the surface by air oxidation are mainly hydrated. The rapid loss of metallic Mg and Y near the surface can be accounted for by the grain boundary diffusion mechanism previously invoked to explain results on Nb/Al overlayers. The Nb spectrum of the Nb/30 A Y sample shows remarkably clean, metallic Nb feature, very comparable to that obtained on a Nb foil in-situ scrape-cleaned in ultrahigh vacuum. Artificial barriers formed by oxidation of thin rare-earth metal layers Er(5.1-20.4A) were also attempted. Good-quality tunnel junctions of the type Nb/Er-oxide/Pb 0.9 Bi 0.1 were made, but inferior to those made with Al, Mg, and Y overlayers. XPS shows clearly that the surface oxide consists of both Er-oxide and Nb-oxide.

Carbon-core-electron binding energies, measured with the use of x-ray photoelectron spectroscopy, give direct information on the distribution of the transferred electronic charge in graphite intercalation compounds. Both the stage-one and stage-two compounds, K${\mathrm{C}}_{8}$ and K${\mathrm{C}}_{24}$, with all carbon atoms in bounding layers, should be well suited to the study of the in-plane charge distribution; however, cleaved samples of K${\mathrm{C}}_{8}$ proved to be extremely unstable at room temperature in ultrahigh vacuum. For the stage-two compound, the C $1s$ spectra reveal an electronic charge distribution which is very strongly localized on those carbon atoms which are nearest the intercalant ions.

Core-electron binding energies of iodine adsorbed on Pt(111) surfaces have been measured as a function of coverage in both the ($\sqrt{3}\ifmmode\times\else\texttimes\fi{}\sqrt{3}$) and ($\sqrt{7}\ifmmode\times\else\texttimes\fi{}\sqrt{7}$) regimes. In the former, in which the iodines occupy the threefold hollows, the binding energy decreases only slightly up to the saturation coverage of ⅓ monolayer. In the latter regime two distinct binding energies are obtained, one close to the value in the ($\sqrt{3}\ifmmode\times\else\texttimes\fi{}\sqrt{3}$) regime, the other smaller by 0.95 eV. The smaller binding energy corresponds to atoms in the atop sites of the ($\sqrt{7}\ifmmode\times\else\texttimes\fi{}\sqrt{7}$) structure. The initial- and final-state contributions to this binding-energy shift are examined.

X-ray phtoemission spectra of palladium prepared by vacuum evaporation and by argon ion sputtering are compared. The former show a close correlation with calculated band structures but the latter exhibit much less detail, strongly suggesting that the sputtered surface is amorphous. The narrow core lines of the evaporated samples show the asymmetry predicted to arise from the hole-conduction electron interaction.

Born-Haber cycles which relate core-electron binding energies of adsorbed isolated atoms and monolayers to adsorption enthalpies and monolayer cohesive energies are used to interpret the measured shifts for Au on Ag, Au, and Pt substrates and to deduce the cohesive interaction within the adlayer. For one monolayer of Au on Ag(111) the core-electron binding-energy shift is negative, but smaller in magnitude than that of surface atoms on bulk gold. The 5d band of the Au monolayers is, however, significantly narrower than that of the first monolayer on bulk gold, but not as much as expected on the basis of the reduced gold coordination number.

The charge transfer in HfPt{sub 3} is discussed on the basis of the 4{ital f} core-electron binding-energy shifts of the constituent elements. Based on binding energies measured relative to the Fermi levels, both Hf and Pt have positive shifts in the compound. According to a Born-Haber cycle analysis these shifts are directly attributable to the large enthalpy of formation of HfPt{sub 3}. Corrections for the differences in reference level and final-state screening between the element and the compound make the shift of the Hf larger and that of the Pt smaller, and presumably negative, indicating a net flow of electronic charge from Hf to Pt. This is in accord with expectations based on the electronegativity difference and with the semiempirical model of Miedema {ital et} {ital al}., but counter to the direction of charge flow in the Engel-Brewer analysis of bonding.

X-ray photoemission spectra of the d-bands of Cu, Ag, Au, Rh, and Pd are compared with corresponding U.V. photoemission data and with APW band structure calculations. It is found that there is a reasonable correspondence between the two experimental techniques, as well as between theory and experiment.

Submonolayer coverages of iodine deposited on clean Ag(111) have been studied by x-ray photoelectron spectroscopy. The adsorbate core-electron binding energy is found to be 0.1-eV smaller at saturation than in the dilute limit, indicating that the iodine carries only a small negative charge. The low-energy electron diffraction evidence for clustering of the adatoms into the $\sqrt{3}\ifmmode\times\else\texttimes\fi{}\sqrt{3}$ structure at coverages considerably less than $\frac{1}{3}$ monolayer is confirmed by the observation, at those coverages, of a constant $14d$ binding energy. The excitation of silver surface plasmons by the core ionization of the adsorbate has also been observed.

The thermal shift of the $^{57}\mathrm{Fe}$ M\"ossbauer $\ensuremath{\gamma}$ ray in rhombohedral Fe${\mathrm{F}}_{3}$ gives a weak indication of a magnetization-dependent Debye temperature. A small isomer-shift discontinuity exists at the transition to cubic structure at high temperature.

The $^{57}\mathrm{Fe}$ M\"ossbauer effect has been used to measure the sublattice magnetization $M(T)={M}_{0}D{(1\ensuremath{-}\frac{T}{{T}_{N}})}^{\ensuremath{\beta}}$ of Fe${\mathrm{F}}_{3}$ in the region $0.85l\frac{T}{{T}_{N}}l0.9995$. The behavior in the critical region yields $\ensuremath{\beta}=0.352\ifmmode\pm\else\textpm\fi{}0.005$ and $D=1.207\ifmmode\pm\else\textpm\fi{}0.015$. The critical exponent differs appreciably from those reported in Mn${\mathrm{F}}_{2}$ and Fe${\mathrm{F}}_{2}$ but is similar to those reported for liquid-vapor transitions and for other ferromagnets.

High-field Mossbauer measurements show that the a-site iron in Fe2Ti has a vanishing magnetic moment. This accounts for the absence of a-site magnetic hyperfine splitting in the antiferromagnetic compound below the Neel temperature.