Energy dispersion of image states and surface states near the surface-Brillouin-zone boundary

AbstractWe demonstrate that nanochannel glass (NCG) materials are ideal for investigating twodimensional (2D) photonic band-structure effects. The NCG materials we have studied consist of triangular arrays of glass cylinders embedded in a glass matrix, having center-tocenter nearest-neighbor separations from 0.54 to 1.08 μm. The indices of refraction of the two glasses differ by less than 0.02 in the relevant spectral region. Narrow attenuation features occur whenever the dispersion relation for light propagating within such a periodic dielectric structure crosses a Brillouin zone boundary. The attenuations corresponding to the first Brillouin zone appear in the near-infrared (IR), at wavelengths between 1 and 3 μm, in good agreement with calculations.

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NEW ELECTRONIC STATES ON CLEAN Si(110)-“16×2” SURFACES

Surface Review and Letters ◽

10.1142/s0218625x95000546 ◽

1995 ◽

Vol 02 (05) ◽

pp. 573-577 ◽

Cited By ~ 5

Author(s):

A. CRICENTI ◽

B. NESTERENKO ◽

P. PERFETTI ◽

G. LE LAY ◽

C. SEBENNE

Keyword(s):

Electronic Properties ◽

Brillouin Zone ◽

Photoelectron Spectroscopy ◽

Structural Model ◽

Electronic States ◽

Surface States ◽

Ultraviolet Photoelectron Spectroscopy ◽

Surface Brillouin Zone ◽

Differential Reflectivity

The electronic properties of a clean Si (110)-“16×2” surface have been studied by angle-resolved ultraviolet photoelectron spectroscopy (ARUPS) and surface differential reflectivity (SDR). Four surface states have been recognized by ARUPS and their dispersions have been mapped along the main symmetry lines in the surface Brillouin zone. SDR experiments revealed transitions between filled and empty surface states at ~ 1.8, 2.4, and 2.9 eV. The results are explained on the basis of a new structural model of the Si (110)-“16×2” phase.

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Tilt and acoustic instabilities in ABX 4, A 2 BX 4 and ABX 3 perovskite structure types: their role in the incommensurate phases of the organic–inorganic perovskites

Acta Crystallographica Section B Structural Science ◽

10.1107/s0108768105028879 ◽

2005 ◽

Vol 61 (6) ◽

pp. 616-626 ◽

Cited By ~ 18

Author(s):

Ian Peter Swainson

Keyword(s):

Brillouin Zone ◽

Three Dimensional ◽

Low Frequency ◽

Zone Boundary ◽

Brillouin Zone Boundary ◽

Perovskite Layer ◽

Modulated Phases ◽

Acoustic Instabilities ◽

Incommensurate Phases ◽

Zero Frequency

An examination of the tilt modes and other low-frequency modes is made for an isolated, untilted perovskite layer, which maps very simply to the ABX 4 perovskites. A sheet of pure tilts exists at the Brillouin Zone boundary at {ξ, ½, ζ}. An instability is also found at all wavevectors which can be described as continuously varying from pure tilts to pure layer displacements as a function of the wavevector. Analysis is extended by considering the stacking of layers in the I-centered A 2 BX 4-layer perovskites. The effect of freezing in the commensurate tilt required to generate the Cmca tilt system, pertinent to the modulated phases of propylammonium salts, is examined. The zero-frequency modes are restricted to two planes in the Brillouin Zone. All of the observed wavevectors associated with modulated phases, and the commensurately tilted propylammonium tetrachlorocadmate, are consistent with this calculation. The effect of full three-dimensional connectivity is briefly reviewed for the true ABX 3 perovskites. While pure tilt incommensurates appear to be hypothetically possible, they do not appear to have been observed to date.

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