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We compare the performance, stability and microstructure of Si/Gd multilayers containing thin barrier layers of W, [B.sub.4] C, or Si[N.sub.x], and determine that multilayers containing 0.6 nm thick W barrier layers at each interface provide the best compromise between high peak reflectance in the extreme ultraviolet near [lambda] 60 nm and good stability upon heating. The Si/W/Gd films have sharper interfaces and also show vastly superior thermal stability relative to Si/Gd multilayers without barrier layers. We find that these structures have relatively small compressive film stresses, and show good temporal stability thus far. We measured a peak reflectance of 29.7% at [lambda] = 62.5 nm, and a spectral bandpass of [DELTA][lambda] = 9 nm (FWHM), for an optimized Si/W/Gd multilayer having a period d = 32.0 nm. [c] 2009 Optical Society of America OCIS codes: 230.4170, 310.1620, 310.6860, 340.0340, 350.1260.

The high-power continuous-wave (CW) laser performance of isostructural Yb-doped vanadates, including three ordered crystals of Yb:YV[O.sub.4], Yb:GdV[O.sub.4] and Yb:LuV[O.sub.4] and two mixed ones with compositional disorder is examined. A high-power diode laser is used as the pump source for comparing CW laser operation of the different vanadates under nearly identical conditions and the spectroscopic properties related to the laser performance are compared to the Yb-doped vanadates.

Planar waveguides formed in the Raman-active crystal KGd[(W[O.sub.4]).sub.2] is characterized by using swift carbon, fluorine and oxygen ion irradiation. Raman spectroscopy measurements have shown the details of the Raman properties of the crystal in the waveguiding region in relation to the rest of the sample for the different ion irradiations and both these measurements are important for use of KGd[(W[O.sub.4]).sub.2] in integrated Raman-active devices.

A highly efficient and widely tunable bifunctional laser based on Yb:GdYAB crystal was operated at both infrared and self-frequency doubling (SFD). Results suggest the achievement of an optical conversion efficiency of 67.9 percent and a slope efficiency of 86 percent at 1048 nm.

We grew a Gd-doped lead chloride single crystal by the Bridgman method and investigated scintillation properties of the crystals at low temperature. We measured the relative light yield, energy resolution, fluorescence decay time, and proportionality of the crystals for the [gamma]-ray at low temperature. The energy resolution is measured to be 25.6% for the [sup.137] Cs 662 keV [gamma]-ray, and the fluorescence decay time of the crystal is composed of two components with decay times of 1.35 and 6.20/[micro]s at 173 K. Index Terms--Crystal growth, gadolinium, lead compound, scintillation detector.

The growth, spectral properties and the laser demonstration of the [Yb.sup.3+]: Ba[Gd.sub.2][(Mo[O.sub.4).sub.4] cleavage crystal, which is normally grown by the Czochralski method is explained. The analysis reveals that the compound can be used for the tunable and ultrashot laser generations of short wavelength.

The optical and magneto-optical properties of elemental rare earth gadolinium are examined by using the linear augmented plane wave method and spin-orbit coupling. The calculations have shown that the local spin density approximation (LSDA) results have an edge over the Coulomb corrected local spin density approximation (LSDA+U) results.

The synthesis of a lithium gadolinium phosphate crystal, Li[Gd.sub.5][P.sub.5][O.sub.13] was carried out by a high temperature solution reaction and solved by single-crystal X-ray diffraction data. Li[Gd.sub.5][P.sub.5][O.sub.13] presents a new structural type and is built up from [[Gd.sub.5][P.sub.2][O.sub.13]].sup.-] layers and one-dimensional Li chains with an unusual Li-Li distance.

The structural and optical properties of europium-doped gadolinium oxide nanoparticles synthesized by the flame pyrolysis method, with specific emphasis on full spectral characterization and fluorescence kinetics is examined. The emission-excitation characterization revealed the presence of predominantly monoclinic but also highly luminescent cubic phases with a prominent oxygen-to-europium charge-transfer band in the 230-260 nm range.

Cerium doped [Gd.sub.2] Si[O.sub.5] (GSO:Ce) single crystal is used as a scintillator for Positron Emission Tomography (PET). GSO:Ce has a good balance of every scintillation properties, but the only disadvantage is the decreasing light output by coloring caused by a small amount of [Ce.sup.4+] in the crystal especially at higher concentration of Ce. In order to improve the scintillation performance, we have tried to grow co-doped GSO:Ce single crystal using conventional starting materials with additional impurities, and evaluate the scintillation performance. Zr doping is found to be effective in preventing coloring and in improving light output. Around 200 ppm Zr doped GSO:Ce have shown maximum light output which is about 20% larger than that of conventional GSO:Ce. This improvement can be explained by the fact that the amount of [Ce.sup.4+] in the crystal might be changed to [Ce.sup.3+] due to charge compensation caused by dopant [Zr.sup.4+] in a [Gd.sup.3+] site thereby decreasing the light absorption in the crystal. Index Terms--Crystal growth, gadolinium compounds, positron emission tomography, scintillation detectors.

An 8-layer depth of interaction (DOI) detector was designed based on the technique we have developed for 4-layer DOI detectors. The new detector achieves 8-layer DOI encoding by pulse shape discrimination (2-layer DOI encoding) and an optimized reflector arrangement in a 3-dimensional crystal array (4-layer DOI encoding). Its capability was proved with an 8-layer 10 x 10 [Gd.sub.2] Si[O.sub.5] (GSO) crystal array coupled to a 256-channel flat panel position sensitive photomultiplier tube (256ch FP-PMT). The dimensions of each crystal element were 2.90 mm x 2.90 mm x 3.75 mm and the interval between 16 x 16 multi anodes in the 256ch FP-PMT was 3.04 mm. Two different dopant concentrations in GSO were chosen for pulse shape discrimination: GSO crystals of 0.5 mol% and 1.5 mol% Ce dopant that have 60 ns and 35 ns scintillation decay times, respectively. In the crystal array, Layer-l, the farthest from the 256ch FP-PMT, and Layers-3, -5 and -7 were composed of GSO crystals of 0.5 mol% Ce dopant. All other layers were composed of GSO crystals of 1.5 mol% Ce dopant. Performance of the 8-layer DOI detector was evaluated by irradiating with 662 keV uniform gamma-rays and the capability was judged to be good. To prove the validity of the layer encoding, a fan-beam of 662 keV gamma-rays was irradiated onto the side face of each layer. The obtained 2-dimensional position histograms showed the right structure in each corresponding layer clearly. Light output uniformity among DOI layers and energy resolutions were measured on the pulse height distributions of the central crystal in each layer. The crystals in Layer-2 and Layer-3 showed the smallest light output and their full energy peak channels were 62% to the largest peak channel of the Layer-8 crystal distribution. Energy resolutions were about 15% for all eight layers. Index Terms--Depth of interaction (DOI), GSO, positron emission tomography (PET).

The satellite pulse generation in diode-pumped passively Q-switched Nd: GdV[O.sub.4] lasers with C[r.sup.4+]: YAG saturable absorber is investigated experimentally and numerically. Results demonstrate that not only could a slow Q-switch cause multiple Q-switched pulses, but a slow ion relaxation from the lower laser level to the ground state can also generate the same effect.

The electroluminescence (EL) properties of the [Gd.sup.3+] ultraviolet (UV) luminescent centers in Si[O.sub.2] metal-oxide-semiconductor light emitting devices (MOSLEDs) are investigated. The strong EL quenching related to a negative charge trapping around the optically active [Gd.sup.3+] luminescent centers is observed during excitation by hot electron injection, suggesting different methods for improving the EL stability of rare-earth doped MOSLEDs.

The first efficient laser operation of a novel laser material Y[b.sup.3+]:G[d.sub.2]Si[O.sub.5] (GSO) is presented. The results indicate that the Yb:GSO crystal is a very promising laser gain medium for developing a new all-solid-state ultrashort pulse source.

Blue and ultraviolet luminescence in (P[r.sup.3+], G[d.sup.3+]) doped fluoroindate glass is studied for excitation in the red region. The characterization of the luminescence signals allow to determine energy transfer (ET) rate among the P[r.sup.3+] ions and provides evidence of interconfigurational ET between G[d.sup.3+] and P[r.sup.3+] ions.

[Gd.sub.2]Si[O.sub.5] :Ce (GSO:Ce) is a high-Z, nonhygroscopic fast emitting scintillator used in detectors of positron emission tomography (PET) systems. The purpose of this study was to evaluate the luminescence efficiency of GSO:Ce scintillator under irradiation conditions employed in X-ray medical imaging, since findings may be of value in novel applications such as computed tomography breast imaging or modern fast image producing X-ray computed tomography. To this aim the absolute luminescence efficiency (emitted light flux over X-ray exposure), the spectral matching factor (compatibility to optical detectors), and the effective efficiency (the product of absolute efficiency and spectral compatibility) were determined for X-ray tube voltages ranging from 20 to 140 kV. The efficiency of GSO:Ce was found to increase with increasing X-ray tube voltage, while the GSO:Ce spectrum, peaking at 440 and 490 nm, was found compatible to most optical detectors (photodiodes, photocathodes, and charge-coupled devices). Index Terms--Inorganic scintillators, luminescence efficiency, matching factor, radiation detectors.

A study isolates the luminescent two-dimensional (2D) coordination polymers of Eu(III), Gd(III), and Tb(III) with isophthalato and thiophenylisophthalato ligands. Metals ions show that the derivatization of isophthalato with the thiophenyl moiety leads to an increase in emission quantum yield.

The microstructure of GdBa2Cu3O7-delta/La0.6Sr0.4MnO3 superlattices grown on MgO substrates by high-resolution transmission electron microscopy was studied. The crystallography of the interfaces found between the layers and the defects was analyzed and their role ion the physical properties of the superlattices was discussed.

Phase model spectroscopic ellipsometric is used to characterize Gd2O3 films deposited by e-beam evaporation on quartz substrates. The experimental ellipsometric data are fitted with theoretically generated spectra to derive information regarding the sample structure and dispersion of optical constants of the Gd2O3 films.

A study demonstrates two self-frequency conversions from the bifunctional laser and optical nonlinear GdAl3 (BO3) 4:Nd (super 3+) crystals. The highest yield was 0.12% and New Sellmeier formulas valid at least up to 2600nm are established from the results obtained by the demonstration.

A simple growth technique for preparation of metal-organic bilayer films consisting magnetic Gd and nonmagnetic Au metalic layers is presented. The bilayer films are an essentially nanostructured network of islands and interconnects that exhibit nonohmic I-V characteristics when measured laterally across the film using a conducting AFM tip.

The optical transmission spectroscopy of the gadolinium trihydrides GdH(sup 3) for the spectral range from 0.05 to 6 eV is investigated. The analysis indicates that GdH(sub 3) is a wide-gap semiconductor with an energy gap of 2.55 eV.

The absorption cross section, the emission cross section, and the potential laser gain near 1.9 mum are investigated for both sigma and pi polarizations. The potential laser gain curves indicate that more than 200 nm tenability range is expected for this material.

The direct pumping into the emitting level of Nd(super 3+) in Nd:YVO4 crystal has a much larger global effect on the intracavity frequency doubling of the 1064-nm emission than for Nd:YAG. These results indicate that the modality of pumping could be instrumental in the enhancement of performances of second-harmonic devices based on Nd vanadates or of other strongly absorbing Nd laser materials and for their scaling to higher power.

The study reports on magnetic dichroism in photoemission from the Gd 4l (l=s, p, d, f) core level of in-plane magnetized Gd films excited with linearly, circularly, and unpolarized light. The experimental results are compared to three-step photoemission cluster calculations based on a relativistic full potential algorithm respecting magnetic exchange.

Several photothermal measurements are conducted to explain the thermomechanical properties exhibited by the ytterbium doped laser crystals. The different impacts of ytterbium doping concentration are also analyzed.

The synthesis of a polylysine dendron containing eight GdDOTA units conjugated to a peptoid dimer exhibiting a high affinity for the vascular endothelial growth factor receptor 2 (VEGFR2) is described. The simple low molecular weight system with a molecular [r.sub.1] relaxivity could be used to enhance MR images of tumors grown in mice in vivo.

Several studies are conducted to explain the various effects of the distorted lattice and nonequal-valence substitution observed on the long lasting phosphorescence of [Eu.sup.2+] and [Gd.sup.3+] doped R[Mg.sub.2][([PO.sub.4]).sub.2] (R = Sr,Ba) phosphors. The electron storage ability of the compounds is shown to get highly enhanced because of the codoping of [Gd.sup.3+].

Several studies are conducted to explain the magnetic, as well as the optical properties of the different multiferroic GdMn[O.sub.3] nanoparticles that are synthesized by a polymerized complex method. The three shoulder absorption peaks exhibited by these nanoparticles are also explained.

A new magneto-optical imaging technique is employed to determine the coercivity and the properties of the various GdFe-spin-valve structures. The coercivity of the structures is shown to significantly reduce with the formation of patterns of the nucleation centers.

The photoluminescence and x-ray luminescence of lanthanum-stabilized cubic barium chloride with europium ([Eu.sup.2+]) doping. The measurement of the x-ray luminescence intensity when compared to a standard commercial [Gd.sub.2][O.sub.2]S:Tb phosphor sheet has shown equal brightness.

Luminescence, lifetime, and quantum yield studies of crystalline nanoneedles of [Eu.sup.3+]-doped GdP[O.sub.4] and [Eu.sup.3+]-doped GdP[O.sub.4] covered with GdP[O.sub.4] shell are reported. The nanoparticles which are redispersible in water, ethanol, or chloroform could find applications in biological labeling and the dispersed particles incorporated in polymer-based films could find use in display devices.

A method is described for editing NMR spectra by using a soluble gadolinium complex that broadens nuclear spins being at or close to the macromolecule-solvent interface. The number of signals is reduced helping to minimize spectral spectral overlap in large proteins and the method has provided information about the localization of spins being helpful for structure determination of large complexes.

The impact of the [Ce.sup.3+] codoping on the optical absorption and other mechanisms of the enhanced near-infrared quantum cutting in the Gd[BO.sub.3]:[Tb.sup.3+],[Yb.sup.3+] phosphors is discussed. The codoping phenomenon is shown to highly enhance the absorption linewidth and absorption cross-sections in the visible region.

Nanoassembled capsules (NACs) formed by using the MRI contrast agent GdDOT[P.sup.5-] in the internal polymer aggregate are described, the smaller of which has shown promise as potential MRI contrast agents. The greatest gains in relaxivity are observed for smaller NACs, for which water accessibility has remained high but molecular rotation of the [Gd.sup.3+] chelate is restricted.

The upconversion (UC) efficient [Gd.sub.2][O.sub.3]:[Er.sup.3+] nanophosphor powder is prepared through the combustion route by using urea as a reducing agent. The pump power dependence of the emission intensity has shown that two photons are involved in creating one upconverted photon and that excited state absorption is the excitation mechanism.

Gadolinium ([Gd.sup.3+]) vibronic sideband luminescence spectroscopy (GVSBLS) is used to probe the changes in the OH stretching frequency derived from first-shell waters of aqueous [Gd.sup.3+] and of [Gd.sup.3+] coordinated to three different types of molecules, as a function of added Hofmeister series salts. The results indicated a mechanism of action for Hofmeister series ions in which hydrogen bonding among hydration shell waters is modulated by several factors.

The exceptional photoluminescence of microporous AV-24, [K.sub.7][[Ln.sub.3][Si.sub.12][O.sub.32]].x[H.sub.2]O ([Ln.sup.3+] = [Sm.sup.3+], [Eu.sup.3+], [Gd.sup.3+] and Tb.sup.3+]), the first silicate possessing [Ln.sup.3+]-O-[Ln.sup.3+] dimers is described. The molecular orbital model has shown that the [Eu.sup.3+]-O-[Eu.sup.3+] dimers are more stable than the individual metal ions.

Visible green and red upconversion (UC) emissions with anomalous power dependence observed in [Gd.sub.2][O.sub.3:[Er.sup.3+] nanocrystals at room temperature under diode laser excitation of 970 nm are described. A closed positive looping UC mechanism that differs from conventional PA mechanism which explain the observed five- or six-photon processes in the s-shape power dependence are also demonstrated.