Raman and infrared absorption spectra of ${\mathrm{Mg}}_{1\ensuremath{-}x}{\mathrm{Al}}_{x}{\mathrm{B}}_{2}$ have been collected for $0<~x<~0.5$ in the frequency range phonon spectrum. The data show a remarkable dependence on Al content. carefully analized x peak frequency, width intensity modes obtained. results allow us to distinguish between two regimes low high content regions. In particular onset phase evidenced previous structural studies is marked by new spectral components at...

The infrared absorption of charge density waves coupled to a magnetic background is first observed in two manganites ${\mathrm{La}}_{1\ensuremath{-}x}{\mathrm{Ca}}_{x}{\mathrm{MnO}}_{3}$ with $x\phantom{\rule{0ex}{0ex}}=\phantom{\rule{0ex}{0ex}}0.5$ and $x\phantom{\rule{0ex}{0ex}}=\phantom{\rule{0ex}{0ex}}0.67$. In both cases BCS-like gap $2\ensuremath{\Delta}(T)$, which for follows the hysteretic ferromagnetic-antiferromagnetic transition, fully opens at finite ${T}_{0}<{T}_{N}$,...

We have grown LaMnO3 thin films on (001) LaAlO3 substrates by pulsed laser deposition. X-ray diffraction confirms that the are only slightly relaxed and oriented “square square” relative to substrate. The measured Raman spectra closely resemble observed in bulk LaMnO3, which indicates no relevant distortions of MnO6 octahedra induced epitaxial strain. Therefore, detectable changes lattice dynamics occurred our strained case. Mn55 nuclear magnetic resonance identifies presence localized Mn4+...

Raman spectroscopy has been used to investigate different conformational states of bovine pancreatic insulin: the native form and several structurally modified with extent denaturation induced by thermo‐chemical treatment applying very high pressure (up 8 GPa) using a diamond anvil cell. High‐pressure results confirm peculiar strength volume compression insulin largely extend range its structural stability (0–4.2 GPa). Above 4.2 GPa, undergoes an irreversible transition that, once is...

Organo-lead halide perovskites are nowadays considered to be an emerging photovoltaic material.It is clear that the peculiar hybrid nature of this class materials central for their outstanding optical and transport properties.However, role organic cation its interplay with inorganic framework remains elusive.To get insight into interactions at play, highpressure Raman, infrared, X-ray absorption spectroscopy measurements were performed on MAPbBr 3 (MA = CH NH + ).Since lattice compression...

The infrared absorption spectra of polycrystalline ${\mathrm{LaMnO}}_{3}$ and ${\mathrm{CaMnO}}_{3}$ measured in the frequency range transverse optical phonons are reported, discussed, compared with calculations lattice dynamics. For spectrum is consistent expected orthorhombic structure. reflects a symmetry lower than that cubic perovskite. We find close correspondence between two materials which suggests similarity their structures.

Low-resolution transmittance and reflectance spectra of high-quality chemical-vapor deposition (CVD) diamond windows were measured in the infrared 2.5–500-μm wavelength range (20–4000 cm-1). High-resolution measurements on a window with nearly parallel surfaces show well defined interference fringes at low frequencies. By standard procedures optical constants n k CVD determined, for first time to author's knowledge, far-infrared region. It is shown that large wedge angle, close 1°, does not...

An extended temperature and pressure-dependent investigation is carried out on a La0.75Ca0.25MnO3 sample exploiting the infrared absorption technique coupled to diamond anvil cell. The pressure dependence of insulator metal transition T(IM) determined for first time up 11.2 GPa. T(IM)(P) curve we propose model present data has an exponential-like behavior with associated characteristic P* playing role decay constant. It found that equivalence between external internal (chemical) holds over...

The collision-induced translational–rotational spectrum of H 2 has been accurately measured in the region from about 30 to 2000 cm −1 at 195 and 297 K. A very weak feature due hexadecapole-induced dipole, U 0 (1) line, detected K around 1622 . These spectra can be represented by a simple, semi-empirical line shape. effect double transitions are considered explicit expressions for these given. Spectral integrals proportional zero first moments determined experimentally compared with...

The aim of the present work was to investigate how native signal observed in electron paramagnetic resonance (EPR) spectrum tooth enamel and dentin is associated with organic content two tissues. This achieved by comparing EPR optical bands (Raman infrared, IR) components dentin, natural deproteinated samples. main results were: (a) samples, are more intense than enamel, contrast which shows similar intensity tissues; (b) after deproteination, completely suppressed both while eliminated only...

Ambient-condition Raman spectra were collected in the strongly correlated NiS${}_{1\ensuremath{-}x}$Se${}_{x}$ pyrite ($0\ensuremath{\le}x\ensuremath{\le}1.2$). Two samples ($x=0$ and $x=0.55$) studied as a function of pressure up to 10 GPa, for $x=0.55$ sample dependence infrared reflectivity was also measured (0--10 GPa). This gave complete picture optical response that system on approaching metallic state both by application pres-sure and/or Se alloying, which corresponds volume...

We report on the infrared absorption spectra of three oxides, where charged superlattices have been recently observed in diffraction experiments. In ${\mathrm{La}}_{1.67}$${\mathrm{Sr}}_{0.33}$Ni${\mathrm{O}}_{4}$, polaron localization is found to suppress low-energy conductivity through opening a gap and split ${E}_{2u}\ensuremath{-}{A}_{2u}$ vibrational manifold oxygen octahedra. Similar effects are detected ${\mathrm{Sr}}_{1.5}$${\mathrm{La}}_{0.5}$Mn${\mathrm{O}}_{4}$...

The metal to insulator transition in the charge-transfer ${\text{NiS}}_{2\ensuremath{-}x}{\text{Se}}_{x}$ compound has been investigated through infrared reflectivity. Measurements performed by applying pressure pure ${\text{NiS}}_{2}$ (lattice contraction) and Se alloying expansion) reveal that both cases an anomalous metallic state is obtained. We find optical results are not compatible with linear Se-alloying vs pressure-scaling relation previously established transport, thus pointing out...

We present high-quality optical data and density functional perturbation theory calculations for the vibrational spectrum of solid picene (C${}_{22}$H${}_{14}$) under pressure up to 8 GPa. First-principles reproduce with a remarkable accuracy effects on both frequency intensities observed phonon peaks. use projection molecular eigenmodes unambiguously fit experimental spectra, resolving complicated spectral structures, in system hundreds modes. With these projections, we can also quantify...

Reflectance measurements in properly selected samples of Nd$_{1.96}$Ce$_{0.04}$CuO$_{4+y}$ with different carrier concentrations provide a firm evidence Fano antiresonances for the four transverse optical $E_u$ phonons $a-b$ plane. Fits performed without any previous subtraction electronic background, as well dependence on temperature renormalized phonon frequencies, show that continuum repsonsible effect is polaron band found all parent compounds high-T$_c$ superconductors.

The possibility of multiband conductivity and multigap superconductivity is explored in oriented ${\text{V}}_{3}\text{Si}$ thin films by means reflectance transmittance measurements at terahertz frequencies. temperature dependence the spectra normal state gives evidence two bands contributing to film conductivity. This outcome consistent with electronic structure calculations performed within density functional theory. On this basis, we a detailed data analysis found that all optical can be...

Abstract Micro‐Raman measurements were performed on two Etruscan polychromes architectural terracotta panels now display at the Villa Giulia Museum in Rome. These painted panels, dated from 530 to 520 B . C ., are of particular interest because unusual presence green and blue layers. Etruscans Archaic Age indeed mainly used white, red, black colours for panels. Raman spectra allowed analytical identification (malachite) (Egyptian blue) pigments employed by this kind artistic production. This...

AbstractAbstractThis paper reports a detailed study of the degradation phenomena exhibited by painted bas-relief sculpture on portal Basilica San Zeno Maggiore in Verona. This extends wide diagnostic project started previously Istituto Centrale per il Restauro (ICR, Rome). Micro-Raman measurements polished cross-sections samples from lunette allowed identification species present different layers, thanks to high spatial resolution and chemical selectivity this technique. One most interesting...

Journal Article Post-Hospital Home Care for African-American and White Elderly Get access Letha A. Chadiha, PhD, PhD 2 2Address correspondence to George Warren Brown School of Social Work, Washington University, Box 1196, St. Louis, MO 63130-4899. Search other works by this author on: Oxford Academic PubMed Google Scholar Enola K. Proctor, Assistant Professor 3Professor social work Director the Center Mental Health Services Researchsupported grant no. 5R24 MH50857-02National Institute Nancy...

We measured the pressure dependence of room-temperature infrared absorption spectrum pseudocubic ${\mathrm{La}}_{0.75}{\mathrm{Ca}}_{0.25}{\mathrm{MnO}}_{3}$ manganite. On increasing up to 10 Gpa we observe increase a broad band associated with polaronic absorption, which partially screens high-frequency phonon at high pressures. also spectra same sample as function temperature, and layered ${\mathrm{Sr}}_{1.5}{\mathrm{La}}_{0.5}{\mathrm{MnO}}_{4}$ manganite pressure. The comparison between...

The optical response of the two-band superconductor $\mathrm{Mg}{\mathrm{B}}_{2}$ has been studied in $0.7--4\phantom{\rule{0.3em}{0ex}}\mathrm{THz}$ range on films with very low impurity level. effect high-energy $\ensuremath{\sigma}$ gap is observed ratio ${R}_{S}∕{R}_{N}$ between normal and superconducting state reflectance, while a neutron irradiated film slightly higher level, mainly $\ensuremath{\pi}$ evident, as reported previous experiments. At terahertz frequencies, electrodynamics...