Numerous technologies including solid-state lighting, displays, and traffic signals can benefit from efficient, color-selectable light sources that are driven electrically. Semiconductor nanocrystals are attractive types of chromophores that combine size-controlled emission colors and high emission efficiencies with excellent photostability and chemical flexibility. Applications of nanocrystals in light-emitting technologies, however, have been significantly hindered by difficulties in achieving direct electrical injection of carriers. Here we report the first successful demonstration of electroluminescence from an all-inorganic, nanocrystal-based architecture in which semiconductor nanocrystals are incorporated into a p-n junction formed from GaN injection layers. The critical step in the fabrication of these nanocrystal/GaN hybrid structures is the use of a novel deposition technique, energetic neutral atom beam lithography/epitaxy, that allows for the encapsulation of nanocrystals within a GaN matrix without adversely affecting either the nanocrystal integrity or its luminescence properties. We demonstrate electroluminescence (injection efficiencies of at least 1%) in both single- and two-color regimes using structures comprising either a single monolayer or a bilayer of nanocrystals.

Cationic Rh(III) complex [Cp(PMe(3))Rh(SiPh(3))(CH(2)Cl(2))]BAr(4)' (1) activates the carbon-carbon bond of aryl and alkyl cyanides (R-CN, where R = Ph, (4-(CF(3))C(6)H(4)), (4-(OMe)C(6)H(4)), Me, (i)Pr, (t)Bu) to produce complexes of the general formula [Cp*(PMe(3))Rh(R)(CNSiPh(3))]BAr(4)'. With the exception of the (t)BuCN case, every reaction proceeds at room temperature (t(1/2) < 1 h for aryl cyanides, t(1/2) < 14 h for alkyl cyanides). A general mechanism is presented on the basis of (1) an X-ray crystal structure determination of an intermediate isolated from the reaction involving 4-methoxybenzonitrile and (2) kinetic studies performed on the C-C bond cleavage of para-substituted aryl cyanides. Initial formation of an eta(1)-nitrile species is observed, followed by conversion to an eta(2)-iminoacyl intermediate, which was observed to undergo migration of R (aryl or alkyl) to rhodium to form the product [Cp*(PMe(3))Rh(R)(CNSiPh(3))]BAr(4)'.

(ory, Universi~of California, tirrh Sciences Division, lCyclorron Road, Berkeley, CA 94720. I I PREFACE This report is the second document in a series of reports documenting experimental volubility and speciation studies ofradionuclides ingroundwaters from the Yucca Mountain region. The objectives and experimental concepts were discussed in detail in the first report of this series (Milestone 30 10), titled "Measured Solubilities and Speciations of Neptunium, Plutonium, and Americium in a TypicalGroundwater from the Yucca Mountain Region." I Sections 2,3, and 4 of this report are, except for minor changes, identical totheres~ctive sections of the first repofl, Theyare, however, inchsdedheretomake this report a stand-alone document. Solution concentrations of Z~TNp in contact with precipitate obtained from supersaturation of UE-25p#l groundwater at 25°C as a function of time. pH 6.() f 0.1 (closed circles), pH 7.0* 0.1 (closed triangles), and pH 8.5 * 0.1 (closed squares). The neptunium was added initially (day 0) as NpOZ+; initial concentrations were 4.8 x 103 M (pH 6), 1.5x 10-3M (pH 7), and 1.4x 103 M (pH 8.5) . ....... 22Solution concentrations of 2~TNp in contact with precipitate obtained from supersaturation of UE-25p #1 groundwater at 60°C as a function of time. pH 6.0 + (),1 (closed circles), pH 7.0+ 0.1 (closed trimrgles), and pH 8.5 * 0.1 (closed syuares). The neptunium was added initially (day O)as NpOZ+; initial concentrations were 5.6 x lo-~M (pH 6), 1.5 x 10-~M (pH 7), and 1.5 x 10-3 M (pH 8.5). The volubility-controlling steady-state solids were identified and the speciation and/or oxidation states present in the supematant solutions were determined. The neptunium sohrbility decreased with increasing temperature and pH. Plutonium concentrations significantly decreased with increasing temperature at pH 6 and 7. The concentration at pH 8.5 hardly decreased at all with increasing temperature. At both temperatures the concentrations were highest at pH 8.5, lowest at pH 7, and in between at pH 6. For the americium/neodymium solutions, the solrrbility decreased significantly with increasing temperature and increased somewhat with increasing pH. EXECUTIVE SUMMARYWe studied the soIubiIities of neptunium, plutonium, and americium in a modified UE-25p #1groundwater from the Yucca Mountain region (Nevada) at two temperatures and three hydrogen concentrations. They are 25°and 60°C and pH 6,7, and 8.5. Tables I, II, and III summarize the results for neptunium, plutonium, and americium, respectively. The nuclides were added to UE-25p #1groundwater from oversaturation at the beginning of each experiment as l~7Np02+, z~gpud+, and Nds+ with tracer 241Am~+ added to facilitate nuclear counting. Because we maintained constant pH values of 6,7, and 8.5 during the course of the ex~riments, the final sohrtions were closer to ().1 M in total ionic strength with the primary constituents being sodium and pcrchlorate. The steady-state sotids formed in the experiments may not represent the thermody...

The fabrication of high-quality thin superconducting films is essential for single-photon detectors. Their device performance is crucially affected by their material parameters, thus requiring reliable and nondestructive characterization methods after the fabrication and patterning processes. Important material parameters to know are the resistivity, superconducting transition temperature, relaxation time of quasiparticles, and uniformity of patterned wires. In this work, we characterize micro-patterned thin NbN films by using transport measurements in magnetic fields. We show that from the instability of vortex motion at high currents in the flux-flow state of the IV characteristic, the inelastic life time of quasiparticles can be determined to be about 2 ns. Additionally, from the depinning transition of vortices at low currents, as a function of magnetic field, the size distribution of grains can be extracted. This size distribution is found to be in agreement with the film morphology obtained from scanning electron microscopy and high-resolution transmission electron microscopy images.

Trifluoromethyltrimethylsilane, (CH 3 ) 3 SiCF 3 , in the presence of CsF serves as an excellent CF 3 group-transfer reagent, and reaction with Cp 2 TiF 2 in THF gives the titanocene trifluoromethyl fluoride complex Cp 2 Ti(CF 3 )(F) (1; Cp = C 5 H 5 ) in 60% isolated yield. Reaction of complex 1 with the trimethylsilyl reagents, (CH 3 ) 3 SiX (X = OTf = OSO 2 CF 3 , Cl, Br, I, N 3 , and OSO 2 Ph), in a tetrahydrofuran or toluene solution affords the corresponding Ti−CF 3 derivatives Cp 2 Ti(CF 3 )(X) (X = OTf (2), Cl (12), Br (13), I (14), N 3 (15), and OSO 2 Ph ( 16)) in good isolated yields of 67−84%. These compounds have been characterized by a combination of reactivity studies, IR and 1 H/ 13 C{ 1 H}/ 19 F NMR spectroscopies, and single-crystal X-ray diffraction. The Ti−CF 3 linkage in these complexes is remarkably robust, and although the α-C−F bonds are elongated, there is no evidence of an α-fluoride (Ti•••F−CF 2 ) between the electrophilic Ti(IV) metal center and any of the C−F bonds in the trifluoromethyl group in the solid-state or in solution. In the solid-state, these complexes are shock-sensitive; energetic decomposition of Cp 2 Ti(CF 3 )(F) (1) produces uniform spherical nanoparticles ranging from ∼70 to 120 nm in size and porous fluorinated oligomers and polymers containing both −(CF 2 −CF 2 )− and −(CF 2 −CFH)− units, as determined by a combination of SEM, XRD, XRF, XPS, and 19 F MAS NMR. Density functional theory results show good agreement with experimental structural data obtained for Cp 2 Ti(CF 3 )(X) (X = F (1), OTf (2), Cl (12), N 3 (15)) and accurately predicts longer Ti−CF 3 distances than for each specific CH 3 analogue, and the trend extends to structurally related Zr and Hf analogues. Simpler model compounds from groups 4 and 8 (M(CH 3 ) 4 , M(CH 3 ) 3 (CF 3 ), M(CH 3 ) 3 (CCl 3 ), and M(CH 3 ) 3 (CF 2 CF 2 CF 2 CF 3 ); M = Ti, Zr, Hf, Fe, Ru, Os)) were also examined and show that, for group 4 complexes, π-bonding is a significant factor in shortening the strongly ionic M−CH 3 relative to M−CF 3 , whereas for the predominantly covalent group 8 analogues, π-back-bonding helps to shorten the predominantly covalent M−CF 3 relative to M−CH 3 . The bonding analysis suggests that the significant elongation of C−F bonds α to metals is mainly a consequence of the electropositivity of the group 4 metal centers, with minor, if any, contributions from π-effects; the bond-lengthening effect is most pronounced at the α-position and decays rapidly on moving away from the metal.

Epitaxial metal nitride films are prepared using a general chemical solution approach. A polymer‐assisted deposition to prepare epitaxial cubic TiN, metastable AlN, and ternary nitride Ti1−xAlxN films is demonstrated. The structural, optical and electrical properties of the films are investigated, and may be of interest for many technological applications.

A vast array of new experimental modalities have been enabled in the past several years through the development of pixelated detectors synchronized to probe scanning electronics. Such camera systems can then acquire the rich information present in the central portion of the convergent beam electron diffraction pattern as a function of probe position (4D-STEM). These 4-dimensional (or more) datasets can be readily exploited for phase contrast ptychographic imaging [1], nanoscale strain mapping [2], unit cell resolution quantitative scanning position averaged convergent beam electron diffraction [3], and more. While such detectors are now commercially available from several manufacturers with single electron sensitivity, they are typically limited to approximately 1 millisecond (1 kHz) readout times [4] while conventional integrating-detector HAADF STEM image data is acquired at approximately 10 microsecond (100 kHz) scan rates. This speed constraint places significant limits on accessible fields of view at high resolution due to sample drift, and limits in-situ acquisition to a 4D frame rate of ~1 minute.We present here the development, installation, and characterization of the 4D Camera, a CMOS Active Pixel Sensor that consists of a 576 x 576 array of 10 μm pixels [5] of a design related to the original TEAM detector [6] and an outer HAADF detector with 16 concentric quadrant diodes (Figure 1). Full-frame data from this sensor is read out at 87 kHz, digitized locally at the camera head, and sent over 96 multi-gigabit optical links to 4 Field Programmable Gate Array (FPGA) modules for image assembly, packetization, and routing. In initial tests, the sensor exhibited single electron sensitivity from at accelerating voltages from <30 keV to 300 keV, enabling electron counting methods to effectively eliminate detector readout noise. Initial data has been acquired using a structured mask cut by focused ion beam from a 50nm SiN film coated with 1000 nm of evaporated gold (Figure 2). All data will be streamed in real time via a 400 Gbps 1 km optical link to the Cori supercomputer at the National Energy Research Scientific Computing Center (NERSC), which will perform the 4-dimensional reconstruction and HDF5 file writing before additional asynchronous processing and analysis. By design this is a parallel computational workflow, and NERSC's HPC provides concurrency and a rich software environment to scale up analysis and feedback codes. In-hardware edge-computing on these FPGA devices may also be used to carry out initial data processing (e.g. gain and dark correction, thresholding) before the data is placed on the network.

Crystalline and polycrystalline gallium nitride films have been grown on bare c-axis-oriented sapphire at low temperatures (100 °C to 500 °C) using energetic neutral atom-beam lithography/epitaxy. Surface chemistry is activated by exposing substrates to nitrogen atoms with kinetic energies between 0.5 and 5.0 eV and a simultaneous flux of Ga metal, allowing low-temperature growth of GaN thin films. The as-grown GaN films show semiconducting properties, a high degree of crystallinity, and excellent epitaxial alignment. This method of low-temperature nitride film growth opens opportunities for integrating novel substrate materials with group III nitride technologies.