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The electronic structure of SmB6 was investigated by X-ray photoelectron spectroscopy (XPS or ESCA). The spectrum of each core level of Sm in SmB6 consists of three peaks. Such a splitting was not observed in Sm2O3, SmF3, and SmB4. The analysis of the results shows that three kinds of Sm ions — Sm2+(4f6), Sm2+(4f55d0.86s0.2), and another Sm2+ — are present in SmB6. The last kind of Sm ions is probably localized in a surface region.

The L 2,3 edges of soft X-ray emission bands of Na, Mg, and Al metals have been measured under the condition in which the self-absorption effects are negligible. The temperature dependence of the L 3 edses of Mg and Al is analyzed over the range from 70 K to 400 K. It is found that the edge spectral shape in the energy range E - E F >-0.2 eV are insensitive to the transition probability and the density of states effects. The peaking parameters for the Mahan-Nozieres-DeDominicis theory are estimated at 0.14, 0.10, and 0.12 for Na, Mg, and Al metals, respectively. These values are smaller than those derived from the absorption edge spectra. The temperature dependent phonon broadening was found in the case of Al metal, but not in Mg metal.

The two external point-charge (TEPC) model for bacteriorhodopsin (bR) has been examined by X-ray photoelectron spectroscopy (XPS) and CNDO/S molecular orbital calculations. A main concern was given to a point charge near the β-ionone ring. XPS measurements were carried out on fluorophenyl retinal (F-ret) and their derivatives (Schiff base, protonated Schiff base and bacteriorhodopsin analogues (F-bR)), paying close attention to the chemical shift of the F 1 s core level. No meaningful differences were observed among these species although numerical calculations on an assumption of the TEPC model have predicted the chemical shift of about 3 eV between F-ret and F-bR. This fact has arisen a serious question to the validity of the TEPC model. The same conclusion has been reached by the present study of absorption maxima of F-ret and their derivatives.

Anisotropic fundamental optical absorption bands have been found at 4.4 eV in K 2 AgI 3 and Rb 2 AgI 3 , and at 4.9 eV in Rb 2 AgBr 3 . The X-ray photoelectron spectrum of Rb 2 AgI 3 indicates that the uppermost valence band is the p-band of halogen. Optical absorption spectra are interpreted in terms of transitions of the charge transfer type from the halogen to the silver ion. The photo-excitation in the fundamental absorption region have been observed to induce luminescence and a radiation damage effect at low temperature.

The fundamental absorption spectra of the chlorides and the bromides of manganese, iron, cobalt, and nickel have been measured over the range from 2 to 40 eV. Fine structures occurring below 10 eV very as the transition metal changes. Spectral profiles 10 eV are simple and alike among the halides of different transition metals. Peaks located at the absorption edge shift systematically toward high energy from nickel halides to manganese halides, and are ascribed to the charge transfer transition from the outermost p orbitals of halogen to the unoccupied 3d orbitals of the transition metal. Comparison with soft X-ray absorption spectra suggests that the transitions from the outermost p orbitals of halogen to the 4 s orbitals of the transition metals produce peaks around 8 eV. Some of the other structures in the spectra are discussed.

X-ray photoemission spectra of the 3 p electrons of transition-metal ions in VCl 3 , CrCl 3 and CrBr 3 have been measured. The results are compared with the existing theoretical spectra calculated on the basis of the ligand field theory. The spectra of V 3+ and Cr 3+ can be explained to some extent by the multiplet splitting due to the interaction between 3 d electrons and a 3 p hole in the crystal field. In contrast with the case of Ni 2+ , the values of the Slater-Condon parameters for V 3+ and Cr 3+ in their halides are nearly equal to those of the free ions and the effect of the hole-induced covalency has little influence on the spectra.

Angle-resolved ultraviolet photoelectron spectra have been measured for well defined Ag/Si(111) submonolayer interfaces of (1) Si(111)( 3 × 3 )R30°-Ag , (2) “Si(111)(6 × 1)-Ag”, and (3) Ag/Si(111) as deposited at room temperature. Non-dispersive and very narrow (FWHM ∼ 0.4–0.5 eV) Ag 4d derived peaks are found at 5.6 and 6.5 eV below the Fermi level for surface (1) and at 5.3 and 6.0 eV for surface (2). Dispersions of sp “binding” states in the energy range between E F and Ag 4d states have been precisely determined for surface (1). Electronic structures similar to those of the Ag(111) surface, including the surface state near E F , have been observed for surface (3).

The electronic band structure of black phosphorus has been studied by angle-resolved ultraviolet photoelectron (ARUPS). The experimental valence band structure has been successfully obtained by the use of the He I and Ne I resonance lines. The binding energies of some special points with almost no interlayer energy dispersion have been experimentally determined and compared with the result of the self-consistent pseudopotential (SCP) band calculation on black phosphorus. The comparison indicates that the SCP calculation overestimates the 3p band width by about 1.0 eV and that the displacement is not necessarily uniform. The conduction band structure has also been studied by the ARUPS with the Ar I resonance line, which is largely modulated by the conduction band structure.

The electronic valence band structure of graphite has been experimentally determined with considerable accuracy for the first time by the highly angle-resolved ultraviolet photoelectron spectroscopy. The photoemission measurements were performed on a synthesized single-crystalline graphite (kish graphite) with the He II resonance line as an exciting source. Some high symmetry points in the Brillouin zone have been successfully identified in the experimentally determined band structure. The present experimental result has been compared with early photoemission experiments and some band calculations presented so far.

The energy spectra of valance electrons photoemitted by excitation with X-rays have been measured on the chlorides and the bromides of nickel, cobalt, iron, and manganese. The profiles of the spectra obtained by deconvoluting raw data with a measured instrumental response function show structures representing the energy dependence of the state-densities of 3d electrons of metal ions. The structures in the spectra are qualitatively in terms of the molecular orbital energy levels. Variations in the spectral among different materials are discussed in connection with the fundamental optical absorption spectra.

In order to study the molecular species of a new allotrope of crystalline selenium (orthorhombic Se), X-ray photoelectron spectroscopy (XPS) has been applied to it for the first time. A comparison of the XPS spectrum of orthorhombic Se with those of rhombohedral and monoclinic Se consisting of Se 6 and Se 8 ring molecules respectively almost excluded the possibility that orthorhombic Se may consist of both Se 6 and Se 8 ring molecules. The CNDO molecular orbital calculations of the electronic structure for several Se 7 ring molecules of various structures suggest that orthorhombic Se is composed of a chair-type Se 7 ring molecule.

Photoelectron spectra of the valence bands of noble metals, europium chalcogenides, cuprous halides, transition metal halides and cadmium sulphide were measured in the exciting photon energy range 40–76 eV by the use of synchrotron radiation from a 1.3 GeV Tokyo Synchrotron. Overall energy resolution was about 0.4 eV. The results show that the radiation is very promising for high resolution photoelectron spectroscopy in XUV photon energy

Ultraviolet (UPS) and X-ray (XPS) photoemission spectra of quasi-two dimensional metal Ag 2 F are presented. Three prominent bands are found at about 2.0 eV, 4.6 eV and 6.0 eV from the Fermi level in the UPS spectrum. They are assigned to the F 2 p state, the Ag 4 d state and the mixture of the two states, respectively. The comparison of the photoemission spectra with a recent LAPW band calculation shows that the calculated 4 d band is shifted toward the lower binding energy by about 1 eV relative to that of the experiment. This discrepancy suggests that the 16th band which forms a small ellipsoidal Fermi surface in the LAPW calculation may be above the Fermi level.

Angle-resolved ultraviolet photoelectron spectra of Si(111) 7 × 7 and 1 × 1 surfaces have been measured as a function of temperature from ambient temperature to ≈ 1120°C. Both the Si(111) 7 × 7 and 1 × 1 surfaces show obvious surface metallic edge at all the temperatures. A middle peak among three surface-state peaks observed for ambient-temperature 7 × 7 surface has been found to disappear for high-temperature 7 × 7 surface. In going from high-T 7 × 7 surface to high-T 1 × 1 surface, no essential changes in the surface-state peaks have been found to occur.

In K 2 CuCl 3 and K 2 CuBr 3 crystals, the fundamental optical absorption has been found to be at about 4.5 eV from the reflectivity measurement. An intrinsic luminescence band due to a forbidden transition has been found at about 3.2 eV in both crystals. From the observation of the X-ray photoelectron spectrum, a conclusion is drawn that the top of the valence band is the d-band of the curprous ion. The properties of the fundamental absorption and the luminescence are consistent with this conclusion.

The spectra of the Ti L 2,3 emission, Ti M 2,3 emission, Ti L 2,3 photoelectron yield, and X-ray photoemission have been measured on titanium oxides, TiO 0.3 , TiO 0.84 , TiO 0.9 , TiO 1.1 and TiO 1.22 , by the use of a grazing incidence spectrometer and an electrostatic electron energy analyzer of hemisphere type. Results are compared with the calculated density of states proposed till now with emphasis on the effect of the oxygen concentration on the electronic structure. It is shown that the major part of the 3 d state in titanium oxides locates at about 5 eV above the Fermi level and has the width of about 4 eV, and this state may extend below the Fermi level.

He + impact collision ion scattering spectroscopy (ICISS) has been applied to the Ge(111)c(2 × 8). Ge(111)7 × 7−Sn. 5 × 5−Sn. and 3 × 3 −Sn surfaces. For the Sn-covered Ge(111) surfaces, it has been found that most Sn atoms occupy top portions of the Ge surfaces. From comparisons of computer simulation for ICISS curves with experiment, it has been concluded that trajectory-dependent neutralization of He + denies a simple view of shadowing and focusing of He + usually assumed in ICISS.

The XPS spectra of valence bands in CuCl, CuBr, and CuI show the existence of two separate bands after appropriate deconvolution. The evaluation of the average p-d mixing rates on the basis of the tight-binding approximation with a few simplifying assumptions indicates, in accordance with optical data, that the upper valence band arises mainly from the 3d state of copper. The XPS spectra coincide qualitatively but not quantitatively with the spectra obtained by excitation with monochromatized synchrotron radiation at 40, 61, and 76 eV. A major difference is that the ratio of integrated intensity of the upper band to that of the lower band is larger in the case of excitation at 40, 61, or 76 eV. The XPS spectra of PbI 2 and CdI 2 have also been measured. In both materials, the valence band spectra have composite structures and give two well-defined peaks after deconvolution. The profile of the spectrum of PbI 2 appears to have some deviation from the reported energy band structure.

Ag M 4 N 4,5 N 4,5 Auger electron diffraction and Ag 3d X-ray photoelectron diffraction from Ag(110) surface have been measured and interpreted kinematically. There is very good agreement between the experiment and the interpretation showing the applicability of the kinematical interpretation.

The photoabsorption spectra of 4d electrons have been measured on LaF 8 , LaCl 3 , CeF 3 , CeCl 8 , and CeBr 3 as well as on metallic La and Ce. The spectra consist of two parts. One is the line structure near the threshold and the other is the broad and intense band (giant band) following the line structure. The observed features of the spectra concerning the line structure are independent of halogen and in agreement with existing atomic theoretical calculations. On the other hand, the profile of the giant band in La-halides is dependent on halogen. The 3 D 1 line in La-halides is found to have an asymmetric line-shape. In the measurements by photographic method using synchrotron radiation, temperature dependence of the spectra is not detected.

Angle-resolved ultraviolet photoemission measurements have shown that the surface electronic structure of the Ge(111)7 ×7-Sn surface is essentially the same as that of the Si(111)7 ×7 surface. Metallic surface states of the Ge(111)7 ×7-Sn surface reveal a slight dispersion of an approximate 2 ×2 periodicity. The so-called dangling- and the back-bond surface states of the Ge(111)“2 ×8” surface also show a slight dispersion. The dangling- and the back-bond surface states of the Ge(111)7 ×7-Sn surface lie at nearly the same binding energies as those for the Ge(111)“2 ×8” surface rather than those for the Si(111)7 ×7 surface.

X-ray photoelectron spectra were measured for the valence bands of 13- cis and all- trans fluorophenyl-retinals. A remarkable difference has been observed in the O 2 s -derived portion of the valence band between the two forms. The experimental results were interpreted using the CNDO/S molecular orbital methods.

X-ray photoelectron diffraction of Sn 3d core levels for Ge (111) 7×7-Sn surface has been measured and analyzed kinematically. On the basis of the finding by Ichikawa and Ino that the Ge (111) 7×7-Sn and Si (111) 7×7 surfaces have essentially the same structure, it is aimed to find a structure of the 12 maxima found in recent scanning tunneling microscopy for Si (111) 7×7 surface. A “tri=pedal” model is proposed in which a tetrahedron of 4 atoms stands on the top of 3 atoms of the first layer.

Valence band structure of rhombohedral arsenic has been studied by angle-resolved photoemission using synchrotron radiation with photon energies between 20 eV and 80 eV. The experimentally determined band structures along the ?T line and in the ?LX and ?WK planes were compared with the self-consistent pseudopotential band calculation performed in this study as well as with some representative band calculations presented so far.

Temperature dependence of angle-resolved ultraviolet photoelectron spectra has been obtained for Si(111) surfaces starting with a thermally quenched “1 × 1” surface and ending with a high temperature “1 × 1” surface. it has been found that the surface state at 0.8 eV below the Fermi level exhibits degradation with the increase in temperature, which explains the difference of surface electronic structures between a quenched “1 × 1” surface and a high temperature “1 × 1” surface. Electron correlation effect in a dangling-bond derived surface state is postulated as a cause for the phenomenon.

Azimuthal X-ray photoelectron and Auger electron diffraction patterns have been measured for the Si(111)√3 × √3-Ga surface. The diffraction patterns have been excellently reproduced by kinematical calculations for an overlayer model in which one third of a monolayer of Ga atoms are arranged on the √3 × √3 sites of the substrate. This is consistent with the T 4 and H 3 models recently proposed for the Si(111)√3 × √3-Group III metal surfaces. The effect of spherical waves on the diffraction patterns has been examined.

The electronic band structure of the first stage alkali-metal graphite intercalation compounds (C8K, C8Rb and C8Cs) was determined by angle-resolved ultraviolet photoelectron spectroscopy. The dispersive feature of the π* bands at $$\tilde K$$ point in the Brillouin zone was clearly observed in all the compounds. The electron occupancies in the π* band of C8K, C8Rb and C8Cs were estimated to be 0.5±0.05 e (e; unit electronic charge), 0.45±0.05 e and 0.4±0.05 e, respectively. This strongly suggests that another half of the unit electronic charge is accommodated in the three-dimensional band at Γ point, which forms a spherical Fermi surface at the center of the Brillouin zone. The character of the three-dimensional band at Γ point was also discussed.

Angle-resolved inverse photoemission spectroscopy (ARIPES) in isochromat mode ( h ω = 9.5 eV ) has been performed for highly oriented pyrolytic graphite. The unoccupied band structure of graphite could be mapped with considerable accuracy in the energy range of 0 – 21 eV above the Fermi level. The experimental results were compared with some previous ARIPES results and band calculations presented so far.

Angle-resolved ultraviolet photoemission spectra of rhombohedral arsenic have been measured for the first time and compared with the self-consistent pseudopotential calculation and with four others presented so far. The electron pocket at the L point in the Brillouin zone and the hole pocket near the T point have been directly identified in the experimentally derived band structure. It has been also elucidated that contrary to the early calculations only one band goes across the Fermi level near the L point, forming the electron pocket. Some special points with high symmetry have been successfully assigned in the experimental band structure.

Angle-resolved ultraviolet photoelectron spectroscopy (ARUPS) was carried out on the stage-1 potassium-graphite intercalation compound C 8 K for the first time. Some valence π- and σ-bands have been identified experimentally in the ARUPS spectra as well as a high density of unoccupied states at about 6.0 eV above E F . The sharp peak at E F in UPS spectra, which has been ascribed to the potassium 4s state, was found to be largely of graphite origin. The experimental results were compared with some theoretical band calculations presented so far.

In situ photoemission (UPS and XPS) measurements have been performed for amorphous GeTe films. The photoemission spectra exhibit a drastic change upon thermal annealing and/or the crystallization of the film. It has been found that an amorphous GeTe film deposited onto a room temperature substrate has a 4-2 coordinated local structure, while a highly disordered amorphous GeTe film evaporated onto a cooled (77 K) substrate is largely 3-3 coordinated, and relaxes into the 4-2 coordinated structure upon thermal annealing within amorphous phase.

Highly-angle-resolved ultraviolet photoelectron spectroscopy was carried out for a C 8 Cs single crystal to study the electronic charge transfer in alkali metal graphite intercalation compounds. The dispersive π ∗ -band at the K point in the Brillouin zone was observed for the first time. The electron occupation in the π ∗ -band was estimated to be 0.45±0.05 unit electronic charge. This strongly suggests that a substantial part of an interlayer band exists below the Fermi level at the γ point, forming a spherical Fermi surface on the center of the Brillouin zone.

Photoemission (XPS and UPS) measurements were performed for elemental Se and Bi and, crystalline and amorphous Bi2Se3 films to terminate the long-standing controversy about the charge transfer in Bi-doped chalcogenide glasses. It was elucidated that the Bi atoms in amorphous Bi2Se3 are positively charged owing to an electronic charge transfer from the Bi atoms to the Se atoms. A comparison of the chemical shift of the core levels and the valence band between amorphous and crystalline Bi2Se3 indicates that the bonding is more covalent in amorphous phase than in crystalline phase, suggesting that although the Bi atoms in crystalline Bi2Se3 are six-fold coordinated by Se atoms, the Bi atoms in the amorphous phase are three-fold coordinated like the As and Sb atoms in amorphous chalcogenides.

Band structure of black phosphorus has been first experimentally determined by the angle-resolved ultraviolet photoemission spectroscopy. The experimental results have been compared with the recently presented band calculations by Asahina et al. The overall features of the valence bands show a good correspondence between them although the observed band width is fairly narrower than the calculated one.

Angle-resolved photoemission spectra of a black-phosphorus single crystal have been measured with very high angular resolution using He I and Ne I resonance lines. The experimentally determined band structure has been compared with the self-consistent pseudopotential calculations. Some special points and bands with almost no energy dispersion along the interlayer direction have been successfully assigned in the experimentally derived band structure.

Photoemission (XPS and UPS) spectra have been measured for an amorphous GeSe film deposited onto a cooled substrate before and after thermal annealing of the film. The photoemission spectra show a remarkable change in the 4p and the Ge 4s region. A comparison of the experimental results with the recently presented electronic structure calculations reveals that an amorphous GeSe film deposited onto a cooled substrate has a 3-3 coordination character and relaxes into a chemically ordered 4-2 coordinated structure upon thermal annealing.

The fundamental optical absorption bands have been found at about 4.5 eV in the alkali cuprous halide (ACH) crystals of K 2 CuCl 3 , K 2 CuBr 3 , Rb 2 CuCl 3 , and Rb 2 CuBr 3 , and from 3.9 to 5.2 eV in Rb 2 CuI 3 . From the measured ultraviolet photoelectron spectra of the ACH's and the alkali silver halide (ASH) crystals, it has been concluded that the uppermost valence band of the ACH and the ASH are the d -band of the cuprous ions and the p -band of the halogen ions, respectively. The energy band structure of K 2 CuCl 3 and Rb 2 AgI 3 has been calculated by an augmented-plane-wave method and it is shown that the direct band gap exists at the Γ point in each crystal. The features of the calculated valence bands are consistent with the optical absorption and the photoelectron spectra. The calculated effective mass of an electron at the bottom of the conduction band shows small anisotropy.

Angle-resolved UPS spectra of 4f levels of Yb metal measured as a function of electron take-off angles have given a direct confirmation that satellite peaks of the 4f levels are due to the surface Yb atoms. Upon oxygen exposure, these surface components of the 4f levels do not show any preferential reduction in intensity and the work function decreases. These suggest the diffusion of adsorbed oxygen atoms underneath the Yb surface. By a mass analysis with hydrogen exposure to the Yb surface, it has been found that the surface is hydrogen free even though the evaporated Yb film contains hydrogen in the bulk. These facts lead to the interpretation that the surface 4f level-shift in Yb metal is not hydrogen-induced but intrinsic.

Final state diffraction of Ag 3d X-ray photoelectrons from the Si(111) ( 3 × 3 )R30°- Ag surface has been measured. From a kinematical analysis of the diffraction patterns, it is found that a buried honeycomb framework of Ag atoms is formed on the surface with lateral displacement of the first Si layer.

The electronic band structure of the first-stage cesium-intercalated graphite C 8 Cs was determined by the highly-angle-resolved ultraviolet photoelectron spectroscopy. We found a prominent energy dispersion of the π * band at \(\tilde{K}\) point for the first time. The experimentally-estimated electron occupancy of the π * band is 0.45±0.05 unit electronic charge. This strongly suggests that another half of a unit electronic charge is accommodated in the interlayer band at the \(\varGamma\) point. The present experimental results have been compared with the theoretical band calculations presented so far as well as with the recently reported experimental results on Cs overlayer on graphite.

Angle-resolved ultraviolet photoelectron spectroscopy has been performed for a C 8 K single crystal. The dispersive π * -band near the \(\tilde{K}\) point and the so-called K 4s band around the Γ point are experimentally identified. The experimentally determined band structure has been compared with two different band calculations to discuss the charge transfer in C 8 K. The observed difference in the spectral feature of the `K 4s' band between the experiment and the calculation are also discussed.

In situ photoemission (UPS and XPS) measurements have been performed for amorphous GeTe and GeSe films deposited onto a cooled substrate during thermal annealing and crystallization of the films. It has been found that an amorphous film prepared at room temperature has a 4-2 coordinated local structure while a highly disordered film deposited onto a 77 K substrate is largely 3-3 coordinated and relaxes into the 4-2 coordinated structure upon thermal annealing.

The K emission band of graphite was observed using a grazing incidence spectrometer, and unfolded with the use of Gaussian window function. The unfolding procedure reveals the intrinsic profile of the state density. The profile consists of four sub-bands. The highest one is π-band and the lower three are σ-bands. The overlapping between them is very small. The height of the Fermi edge is about one fortieth of the peak of the π-band. The width of the π-band is 5.8 5 eV. The ratio of the effective number of electrons per atom for π-and σ-electrons is estimated to be 0.9:3, which suggests a slight mixing between them. It is also estimated that the three σ-electrons are distributed equally into the three parts of the σ-band. The low energy tail is classified as a satellite.

Cl - L 23 absorption spectra of alkali chlorides have been obtained at 80°K with a 2 m grazing incidence spectrograph. Synchrotron radiation emitted from a 1.3 GeV electron synchrotron at INS ∗ has been used as a continuum background. The experimental results are interpreted in terms of X-ray exciton, electronic band structure, and two electron excitation.

X-ray photoelectron spectra have been measured on in situ evaporated films of yttrium, lanthanum, and cerium by the use of an electron energy analyser of the parallel plate electrode type. The binding energies of electronic core levels have been determined. Results are compared with the values cited in typical X-ray atomic energy tables. The binding energies of the M 4 (3 d 3/2 ) and M 5 (3 d 5/2 ) levels of lanthanum and cerium as well as the N 2 (4 p 1/2 ) and N 3 (4 p 3/2 ) levels of lanthanum are all found to be split into two components. Possible origins of the splitting are discussed, although no definite conclusion is drawn out.

The Cl - L 2,3 absorption spectra of alkali chlorides, AgCl and TlCl have been measured using an ordinary X-ray tube with tungsten target as a radiation source. Measurements were performed carefully at 300°K, 90°K and 25°K over the photon energy range from 198 to 220 eV. The counting method for detection was more improved than in the previous report and a toroidal pre-reflector was used. Results are compared with the existing results of energy band calculation. It is concluded that sharp absorption bands near the threshold are caused by core-excitons with holes in the 2 p level of chlorine.

Soft X-ray absorption spectra of Be, Al, Sb and Bi, and Al-Mg alloys have been obtained by the use of synchrotron radiation emitted from the 750 MeV electron synchrotron at the Institute for Nuclear Study, Tokyo, as a continuous light source. The K-absorption structure of beryllium was found to agree with the density of states calculated by Loucks and Cutler. Some correspondence was found between the maxima in the L 2,3 -absorption spectrum and the K-absorption spectrum of aluminum. A remarkable band was observed in the L 2,3 -absorption spectrum of aluminum at 23 eV above the edge. This band is not attributable to the singularity in the state density of the conduction band. A tentative interpretation based on the delayed onset of transitions 2 p -∞ d is proposed. The L 2,3 -absorption spectrum of aluminum in Al-Mg alloy shows a remarkable degeneration of the edge, while the L 2,3 -absorption edge of magnesium in the same alloy seems relatively unaffected. This behavior is similar to the effect reported b...