Showing papers on "Brillouin zone published in 2005"
TL;DR: It is demonstrated that stimulated Brillouin scattering can be used to generate all-optical slow-light pulse delays of greater than a pulse length for pulses as short as 16 ns in a single-mode fiber, and strongly suggest that analogous delays can be achieved using stimulated Raman scattering at telecommunication data rates.
Abstract: We demonstrate a technique for generating tunable all-optical delays in room temperature single-mode optical fibers at telecommunication wavelengths using the stimulated Brillouin scattering process. This technique makes use of the rapid variation of the refractive index that occurs in the vicinity of the Brillouin gain feature. The wavelength at which the induced delay occurs is broadly tunable by controlling the wavelength of the laser pumping the process, and the magnitude of the delay can be tuned continuously by as much as 25 ns by adjusting the intensity of the pump field. The technique can be applied to pulses as short as 15 ns. This scheme represents an important first step towards implementing slow-light techniques for various applications including buffering in telecommunication systems.
868 citations
TL;DR: A manifestly gauge-invariant description of Chern numbers associated with the Berry connection defined on a discretized Brillouin zone provides an efficient method of computing (spin) Hall conductances without specifying gauge-fixing conditions.
Abstract: We present a manifestly gauge-invariant description of Chern numbers associated with the Berry connection defined on a discretized Brillouin zone. It provides an efficient method of computing (spin) Hall conductances without specifying gauge-fixing conditions. We demonstrate that it correctly reproduces quantized Hall conductances even on a coarsely discretized Brillouin zone. A gauge-dependent integer-valued field, which plays a key role in the formulation, is evaluated in several gauges. An extension to the non-Abelian Berry connection is also given.
795 citations
IBM1
TL;DR: The electron-phonon scattering and binding in semiconducting carbon nanotubes, within a tight-binding model, is calculated and the mobility as a function of temperature, electric field, and nanotube chirality are well reproduced by a simple interpolation formula.
Abstract: We calculate the electron-phonon scattering and binding in semiconducting carbon nanotubes, within a tight-binding model. The mobility is derived using a multiband Boltzmann treatment. At high fields, the dominant scattering is interband scattering by $LO$ phonons corresponding to the corners $K$ of the graphene Brillouin zone. The drift velocity saturates at approximately half the graphene Fermi velocity. The calculated mobility as a function of temperature, electric field, and nanotube chirality are well reproduced by a simple interpolation formula. Polaronic binding give a band-gap renormalization of $\ensuremath{\sim}70\text{ }\text{ }\mathrm{m}\mathrm{e}\mathrm{V}$, an order of magnitude larger than expected. Coherence lengths can be quite long but are strongly energy dependent.
315 citations
TL;DR: The momentum- and frequency-dependent longitudinal spin structure factor for the spin-1/2 XXZ Heisenberg spin chain in a magnetic field is computed, using exact determinant representations for form factors on the lattice.
Abstract: We compute the momentum- and frequency-dependent longitudinal spin structure factor for the spin-$1/2$ $XXZ$ Heisenberg spin chain in a magnetic field, using exact determinant representations for form factors on the lattice. Multiparticle (i.e., multispinon) contributions are computed numerically throughout the Brillouin zone, yielding saturation of the sum rule to high precision.
223 citations
TL;DR: A spin-polarized first-principles calculation of the atomic and electronic structure of the graphene/Ni(111) interface is presented in this article, where different structural models have been considered, which differ in the positions of the carbon atoms with respect to the nickel topmost layer.
Abstract: A spin-polarized first-principles calculation of the atomic and electronic structure of the graphene/Ni(111) interface is presented. Different structural models have been considered, which differ in the positions of the carbon atoms with respect to the nickel topmost layer. The most probable structure, which has the lowest energy, has been determined. The distance between the floating carbon layer and the nickel surface is found smaller than the distance between graphene sheets in bulk graphite, in accordance with experimental measurements. The electronic structure of the graphene layer is strongly modified by interaction with the substrate and the magnetic moment of the surface nickel atoms is lowered in the presence of the graphene layer. Several interface states have been identified in different parts of the interface two-dimensional Brillouin zone. Their influence on the electron energy loss spectra has been evaluated.
214 citations
TL;DR: In this article, the authors presented DMM calculations of the thermal conductance of Al-Si, Al-Ge, Cu-Si and Cu-Ge interfaces by taking into account the full phonon dispersion relationship over the entire Brillouin zone obtained using the Born-von Karman model (BKM).
Abstract: The acoustic mismatch model (AMM) and the diffuse mismatch model (DMM) have been traditionally used to calculate the thermal boundary conductance of interfaces. In these calculations, the phonon dispersion relationship is usually approximated by a linear relationship (Debye approximation). This is accurate for wave vectors close to the zone center, but deviates significantly for wave vectors near the zone edges. Here, we present DMM calculations of the thermal conductance of Al–Si, Al–Ge, Cu–Si, and Cu–Ge interfaces by taking into account the full phonon dispersion relationship over the entire Brillouin zone obtained using the Born-von Karman model (BKM). The thermal boundary conductance thus calculated deviates significantly from DMM predictions obtained using the Debye model in all cases.
212 citations
TL;DR: In this article, a manifestly gauge-invariant description of Chern numbers associated with the Berry connection defined on a discretized Brillouin zone is presented. But it does not specify gauge-fixing conditions.
Abstract: We present a manifestly gauge-invariant description of Chern numbers associated with the Berry connection defined on a discretized Brillouin zone. It provides an efficient method of computing (spin) Hall conductances without specifying gauge-fixing conditions. We demonstrate that it correctly reproduces quantized Hall conductances even on a coarsely discretized Brillouin zone. A gauge-dependent integer-valued field, which plays a key role in the formulation, is evaluated in several gauges. An extension to the non-Abelian Berry connection is also given.
177 citations
TL;DR: In this article, the results of first-principles calculations on two possible terminations of the (0, 0, 1) surfaces of the perovskite crystals were presented.
169 citations
TL;DR: A Brillouin gain coefficient gB of 6.0 x 10(-9) m/W, about 134 times larger than that of fused silica fiber, is obtained for As2Se3 single mode fiber from measurements of BrillouIn threshold power and the gain linewidth.
Abstract: Strong stimulated Brillouin scattering in single-mode As2Se3 chalcogenide fiber is observed using a cw laser at 1.55 microm wavelength region. Brillouin threshold for a 5-m-long fiber is as small as 85 mW. The Brillouin frequency shift vB and the gain linewidth DeltavB are 7.95 GHz and 13.2 MHz, respectively, measured with heterodyne detection and an RF spectrum analyzer. A Brillouin gain coefficient gB of 6.0 x 10(-9) m/W, about 134 times larger than that of fused silica fiber, is obtained for As2Se3 single mode fiber from measurements of Brillouin threshold power and the gain linewidth.
160 citations
TL;DR: A novel method for simultaneous distributed measurement of temperature and strain based on spatially resolving both spontaneous Raman and Brillouin backscattered anti-Stokes signals is reported.
Abstract: We report on a novel method for simultaneous distributed measurement of temperature and strain based on spatially resolving both spontaneous Raman and Brillouin backscattered anti-Stokes signals. The magnitude of the intensity of the anti-Stokes Raman signal permits the determination of the temperature. The Brillouin frequency shift is dependent on both the temperature and the strain of the fiber; once the temperature has been determined from the Raman signal, the strain can then be computed from the frequency measurement of the Brillouin signal.
127 citations
TL;DR: In this article, a Brillouin light scattering study and theoretical interpretation of spin-wave modes in arrays of in-plane magnetized micron-size rectangular elements are reported, and the frequency spectra and spatial profiles of these eigenmodes are calculated both analytically and numerically.
Abstract: A Brillouin light scattering study and theoretical interpretation of spin-wave modes in arrays of in-plane magnetized micron-size rectangular ${\mathrm{Ni}}_{80}{\mathrm{Fe}}_{20}$ elements are reported. It is shown that two-dimensional spin-wave eigenmodes of these elements can be approximately described as products of one-dimensional spin-wave eigenmodes of longitudinally and transversely magnetized long finite-width permalloy stripes. The lowest eigenmodes of rectangular elements are of dipole-exchange nature and are localized near the element edges, while the higher eigenmodes are of a mostly dipolar nature and are weakly localized near the element center. The frequency spectra and spatial profiles of these eigenmodes are calculated both analytically and numerically, and are compared with the results of the Brillouin light scattering experiment.
TL;DR: In this article, the increase of the stimulated Brillouin scattering threshold in dispersion-shifted fibers (DSFs) by applying three different tensile-strain distributions was investigated.
Abstract: We study, experimentally and numerically, the increase of the stimulated Brillouin scattering (SBS) threshold in dispersion-shifted fibers (DSFs) by applying three different tensile-strain distributions. The best results are obtained with a 40-step stair-ramp distribution, for which we demonstrate a 8-dB SBS threshold increase in a 580-m DSF. The Brillouin frequency is observed to shift as a function of the strain at a rate of 0.464 GHz/%. We discuss the potentials and drawbacks of this technique for application in nonlinear devices.
TL;DR: Quantized spin-wave eigenmodes in single, 16 nm thick and 0.75 to 4 mum wide square permalloy islands with a fourfold closure domain structure have been investigated by microfocus Brillouin light scattering spectroscopy and time resolved scanning magneto-optical Kerr microscopy.
Abstract: Quantized spin-wave eigenmodes in single, 16 nm thick and 0.75 to $4\text{ }\ensuremath{\mu}\mathrm{m}$ wide square permalloy islands with a fourfold closure domain structure have been investigated by microfocus Brillouin light scattering spectroscopy and time resolved scanning magneto-optical Kerr microscopy. Up to six eigenmodes were detected and classified. The main direction of the spin-wave quantization in the domains was found to be perpendicular to the local static magnetization. An additional less pronounced quantization along the direction parallel to the static magnetization was also observed.
TL;DR: This work investigates the electronic properties of water at ambient conditions using ab initio density-functional theory within the generalized gradient approximation (DFT/GGA), focusing on the unoccupied subspace of Kohn-Sham eigenstates, and finds that the density of occupied states of this molecular liquid is well described.
Abstract: In the last decade, computational studies of liquid water have mostly concentrated on ground-state properties. However, recent spectroscopic measurements have been used to infer the structure of water, and the interpretation of optical and x-ray spectra requires accurate theoretical models of excited electronic states, not only of the ground state. To this end, we investigate the electronic properties of water at ambient conditions using ab initio density-functional theory within the generalized gradient approximation (DFT/GGA), focusing on the unoccupied subspace of Kohn-Sham eigenstates. We generate long (250 ps) classical trajectories for large supercells, up to 256 molecules, from which uncorrelated configurations of water molecules are extracted for use in DFT/GGA calculations of the electronic structure. We find that the density of occupied states of this molecular liquid is well described with 32-molecule supercells using a single k point (k=0) to approximate integration over the first Brillouin zone. However, the description of the unoccupied electronic density of states (u-EDOS) is sensitive to finite size effects. Small, 32-molecule supercell calculations, using the Gamma-point approximation, yield a spuriously isolated state above the Fermi level. Nevertheless, the more accurate u-EDOS of large, 256-molecule supercells may be reproduced using smaller supercells and increased k-point sampling. This indicates that the electronic structure of molecular liquids such as water is relatively insensitive to the long-range disorder in the molecular structure. These results have important implications for efficiently increasing the accuracy of spectral calculations for water and other molecular liquids.
TL;DR: The eigenfield distribution and the band structure of a photonic crystal waveguide have been measured with a phase-sensitive near-field scanning optical microscope and the lateral mode profile for modes separated by one reciprocal lattice vector is found to be different.
Abstract: The eigenfield distribution and the band structure of a photonic crystal waveguide have been measured with a phase-sensitive near-field scanning optical microscope. Bloch modes, which consist of more than one spatial frequency, are visualized in the waveguide. In the band structure, multiple Brillouin zones due to zone folding are observed, in which positive and negative dispersion is seen. The negative slopes are shown to correspond to a negative phase velocity but a positive group velocity. The lateral mode profile for modes separated by one reciprocal lattice vector is found to be different.
TL;DR: In this paper, an extensive Raman study combined with x-ray diffraction (XRD) and dielectric measurements confirmed the presence of the incommensurate (INC) phase in sodium niobate.
Abstract: Raman spectra of sodium niobate (NaNbO3) were obtained in all phases and revealed a significant disorder in the high-temperature U, T2 and T1 phases and ac omplicated folding of the Brillouin zone at the transitions into modulated S, R, P and N phases associated with the competitive zone-boundary soft mode s( in-phase and out-of phase octahedral tilts) along the M–T–R line. An extensive Raman study combined with x-ray diffraction (XRD) and dielectric measurements confirmed the presence of the incommensurate (INC) phase in sodium niobate. XRD experiments revealed the invar effect in the temperature interval 410–460 K corresponding to the INC phase associated with rotations of the NbO6 octahedra modulated along the b-direction. Our experiments suggest that the phase P consists of three phases: monoclinic (Pm) between 250 and 410 K, INC between 410 and 460 K, and orthorhombic (Po) between 460 and 633 K. At the low-temperature transition to the ferroelectric rhombohedral N phase all folded modes originating from the M- and T-points of the Brillouin zone abruptly disappear, Raman spectra in the N phase become much simpler and all peaks were assigned.
TL;DR: It is shown that a new resonant magnetic excitation at incommensurate momenta, observed recently by inelastic neutron scattering experiments on YBa2Cu3O6.85 and YBa 2Cu3 O6.6, is a spin exciton, located in the Brillouin zone and determined by the momentum dependence of the particle-hole continuum.
Abstract: We show that a new resonant magnetic excitation at incommensurate momenta, observed recently by inelastic neutron scattering experiments on YBa2Cu3O6.85 and YBa2Cu3O6.6, is a spin exciton. Its location in the Brillouin zone and its frequency are determined by the momentum dependence of the particle-hole continuum. We identify several features that distinguish this novel mode from the previous resonance mode observed near Q=(pi,pi).
TL;DR: A novel experimental technique is presented that facilitates mapping the borders of the extended Brillouin zones and the areas of normal and anomalous dispersion in photonic lattices with and without defects.
Abstract: We present a novel, real-time, experimental technique for linear and nonlinear Brillouin zone spectroscopy of photonic lattices. The method relies on excitation with random-phase waves and far-field visualization of the spatial spectrum of the light exiting the lattice. Our technique facilitates mapping the borders of the extended Brillouin zones and the areas of normal and anomalous dispersion within each zone. For photonic lattices with defects (e.g., photonic crystal fibers), our technique enables far-field visualization of the defect mode overlaid on the extended Brillouin zone structure of the lattice. The technique is general and can be used for photonic crystal fibers as well as for periodic structures in areas beyond optics.
TL;DR: In this article, a simple model of thermal conductivity, based on the harmonic theory of solids, is used to study the heat transfer in nanostructures, which is obtained by summing the contribution of all the vibration modes of the system.
Abstract: A simple model of thermal conductivity, based on the harmonic theory of solids, is used to study the heat transfer in nanostructures. The thermal conductivity is obtained by summing the contribution of all the vibration modes of the system. All the vibrational properties (dispersion curves and relaxation time) that are used in the model are obtained using the data for bulk samples. The size effect is taken into account through the sampling of the Brillouin zone and the distance that a wave vector can travel between two boundaries in the structure. The model is used to predict the thermal conductivity of silicon nanowires and nanofilms, and demonstrates a good agreement with experimental results. Finally, using this model, the quality of the silicon interatomic potential, used for molecular-dynamics simulations of heat transfer, is evaluated.
TL;DR: In this paper, the authors used Bloch waves to represent the full solution of Maxwell's equations in periodic media, and showed that only a few of the nonvanishing Bloch wave vectors contribute to the complete solution.
Abstract: Using Bloch waves to represent the full solution of Maxwell's equations in periodic media, we study the limit where the material's period becomes much smaller than the wavelength. It is seen that for steady state fields, only a few of the Bloch waves contribute to the full solution. Effective material parameters can be explicitly represented in terms of dyadic products of the mean values of the nonvanishing Bloch waves, providing a new means of homogenization. The representation is valid for an arbitrary wave vector in the first Brillouin zone.
TL;DR: In this paper, the authors examined the details of Joule heating in silicon with a Monte Carlo method including efficient, analytic models for the electron bands, acoustic and optical phonon dispersion.
Abstract: This work examines the details of Joule heating in silicon with a Monte Carlo method including efficient, analytic models for the electron bands, acoustic and optical phonon dispersion. We find that a significant portion of the initially generated phonons have low group velocity, and therefore low contribution to heat transport, e.g., optical phonons or acoustic modes near the Brillouin zone edge. The generated phonon spectrum in strained silicon is different from bulk silicon at low electric fields due to band splitting and scattering selection rules which favor g-type and reduce f-type phonon emission. However, heat generation is essentially the same in strained and bulk silicon at high fields, when electrons have enough energy to emit across the entire phonon spectrum despite the strain-induced band splitting. The results of this study are important for electro-thermal analysis of future silicon nanoscale devices.
TL;DR: In this article, a novel dark-pulse-based technique has been used for the first time in a Brillouin scattering-based distributed fiber sensor, which is capable of strain and temperature measurement as conventional pulse-based systems but at much higher spatial resolution.
Abstract: A novel dark-pulse-based technique has been used for the first time in a Brillouin scattering-based distributed fiber sensor. Experimentally obtained Brillouin spectra demonstrate that the dark-pulse configuration is as capable of strain and temperature measurement as conventional pulse-based systems but at much higher spatial resolution. A spatial resolution of 50 mm is reported with a strain measurement accuracy of 6 /spl mu//spl epsiv/ on a 100-m sensing fiber.
TL;DR: In this paper, a Brillouin pulse is defined and is shown to possess near optimal (if not optimal) penetration into a given Debye-type dielectric for remote sensing.
Abstract: When an ultrawide-band electromagnetic pulse penetrates into a causally dispersive dielectric, the interrelated effects of phase dispersion and frequency dependent attenuation alter the pulse in a fundamental way that results in the appearance of so-called precursor fields. For a Debye-type dielectric, the dynamical field evolution is dominated by the Brillouin precursor as the propagation depth typically exceeds a single penetration depth at the carrier frequency of the input pulse. This is because the peak amplitude in the Brillouin precursor decays only as the square root of the inverse of the propagation distance. This nonexponential decay of the Brillouin precursor makes it ideally suited for remote sensing. Of equal importance is the frequency structure of the Brillouin precursor. Although the instantaneous oscillation frequency is zero at the peak amplitude point of the Brillouin precursor, the actual oscillation frequency of this field structure is quite different, exhibiting a complicated dependence on both the material dispersion and the input pulse characteristics. Finally, a Brillouin pulse is defined and is shown to possess near optimal (if not optimal) penetration into a given Debye-type dielectric.
TL;DR: An explicit expression for the Kadowaki-Woods ratio in correlated metals is derived by invoking saturation of the high-frequency Fermi-liquid scattering rate at the Mott-Ioffe-Regel limit as discussed by the authors.
Abstract: An explicit expression for the Kadowaki-Woods ratio in correlated metals is derived by invoking saturation of the (high-frequency) Fermi-liquid scattering rate at the Mott-Ioffe-Regel limit. Significant deviations observed in a number of oxides are quantitatively explained due to variations in carrier density, dimensionality, unit cell volume and the number of individual sheets in the Brillouin zone. A generic re-scaling of the original Kadowaki-Woods plot is also presented.
TL;DR: In this article, a numerical technique for temperature/strain profile reconstruction based on Brillouin optical-fibre time-domain analysis (BOTDA) sensors is presented.
Abstract: The experimental validation of a numerical technique for temperature/strain profile reconstruction based on Brillouin optical-fibre time-domain analysis (BOTDA) sensors is presented. In this approach, we search directly for the Brillouin frequency shift profile along the fibre that matches the measured data. The algorithm is based on a harmonic expansion of the unknown profile, whose coefficients are determined by means of a multidimensional minimization. Experimental measurements have been carried out in order to reveal the influence of nonlocalities in Brillouin measurements, and to prove the capability of the proposed algorithm to compensate for these effects.
TL;DR: In this paper, a detailed and systematic lattice dynamical calculation of the newly discovered intermetallic superconductor was performed by using a lattice dynamic model theory based on pairwise interactions under the framework of the rigid ion model.
Abstract: This paper reports a detailed and systematic lattice dynamical calculation of the newly discovered intermetallic superconductor $\mathrm{Mg}\mathrm{C}{\mathrm{Ni}}_{3}$ by using a lattice dynamical model theory based on pairwise interactions under the framework of the rigid ion model. The results bring out the anomalous vibrational mode instability in the phonon dispersion curves and phonon density of states of $\mathrm{Mg}\mathrm{C}{\mathrm{Ni}}_{3}$. The calculated phonon dispersion curves and phonon density of states are in good agreement with the measured and density functional theoretical (DFT) data. The study also illustrates the contradicting results on the magnitude of phonon frequencies due to Mg atoms and the region of the unstable modes in the Brillouin zone of the previously computed two DFT results. The present study on DOS has enabled an atomic level understanding of the phonon density of states. The phonon density of states has been used to compute the specific heat at constant volume. The Debye temperature and temperature-dependent vibrational amplitudes of the different species are also reported. The present calculation suggests that the superconductivity in $\mathrm{Mg}\mathrm{C}{\mathrm{Ni}}_{3}$ is governed by the BCS mechanism.
22 May 2005
TL;DR: In this article, the authors demonstrated that stimulated Brillouin scattering can be used to generate all-optical slow-light pulse delays of greater than a pulse length for pulses as short as 16 ns in a singlemode fiber.
Abstract: We have demonstrated that stimulated Brillouin scattering can be used to generate all-optical slow-light pulse delays of greater than a pulse length for pulses as short as 16 ns in a single-mode fiber. Since the induced delay is generated for wavelengths detuned from the pump field by the Brillouin frequency, tuning near an electronic resonance of the material is not required and thus delays can be induced at telecommunication wavelengths. This represents a significant improvement over previous demonstrations of slow light in solids and is an important step towards developing an all-optical tunable delay line for telecommunications. In addition, these results strongly suggest that analogous delays can be achieved using stimulated Raman scattering at telecommunication data rates.
TL;DR: The optical properties of the both perovskites in the core-level spectra are investigated by the first principles under scissor approximation and the optical constants like refractive index and extinction coefficient were derived from the calculated real and imaginary parts of the dielectric function.
TL;DR: In this article, the electron-phonon matrix elements were calculated for the radial breathing mode (RBM) and the $G$-band $A$ symmetry mode of single-wall carbon nanotubes.
Abstract: The electron-phonon matrix elements are calculated for the radial breathing mode (RBM) and the $G$-band $A$ symmetry mode of single-wall carbon nanotubes. The RBM intensity decreases with increasing nanotube diameter and chiral angle. The RBM intensity at van Hove singular $k$ points is larger outside the two-dimensional Brillouin zone around the $K$ point than inside the Brillouin zone. For the $G$ band $A$ symmetry mode, the matrix element shows that all semiconducting nanotubes have nonzero LO mode intensity, and the LO mode generally has a larger intensity than the TO mode, while the ratio of the intensity of the LO mode to that of the TO mode decreases with increasing chiral angle. In particular, zigzag nanotubes have zero intensity for the TO mode, and armchair nanotubes have zero intensity for the LO mode. Using the matrix elements thus obtained, the resonance Raman excitation profiles are calculated for nanotube samples under different broadening factor $\ensuremath{\gamma}$ regimes. For semiconducting nanotubes, the excitation profiles for the RBM are consistent with experiments. For metallic nanotubes, a quantum interference effect in the Raman intensity is found for both the RBM and LO modes. For the RBM and LO modes, different kinds of excitation profiles are discussed for nanotube samples in the large and small $\ensuremath{\gamma}$ regimes by considering the electron-phonon matrix element and the trigonal warping effect. For nanotube samples in the large $\ensuremath{\gamma}$ regime, a shift in the energy of the peak in the RBM intensity relative to the corresponding peak in the joint density of states is found.
21 Jul 2005-Nuclear Instruments & Methods in Physics Research Section A-accelerators Spectrometers Detectors and Associated Equipment
TL;DR: In this article, the prospects for extending X-ray photoelectron spectroscopy (XPS) and Xray photo-electron diffraction (XPD) measurements into the high-energy regime of 5-15 kV excitation energies are discussed from a fundamental point of view, in some cases using prior results obtained in the 1-2 kV range as starting points of discussion, together with theoretical estimates of behavior at higher energies.
Abstract: The prospects for extending X-ray photoelectron spectroscopy (XPS) and X-ray photoelectron diffraction (XPD) measurements into the hard X-ray regime of 5–15 keV excitation energies are discussed from a fundamental point of view, in some cases using prior results obtained in the 1–2 keV range as starting points of discussion, together with theoretical estimates of behavior at higher energies. Subjects treated are: the instrumentation improvements needed to optimize peak intensities; the tuning of experimental conditions to achieve bulk or surface sensitivity; the use of grazing incidence to suppress spectral backgrounds; the use of standing waves created by Bragg reflection from crystal planes or synthetic multilayers to achieve position-sensitive densities of states, compositions, and magnetizations; photoelectron diffraction and Kikuchi-band effects as element-specific local structure probes; and valence-level measurements, including the role of non-dipole effects and mechanisms leading to complete Brillouin zone averaging and density-of-states like spectra. Several distinct advantages are found for such high-energy extensions of the XPS and XPD techniques.