Production and Characterization of Deposited Mono-Sized Clusters

1990 ◽  
Vol 206 ◽  
Author(s):  
Donald M. Cox ◽  
Barbara Kessler ◽  
Pierre Fayet ◽  
Wolfgang Eberhardt ◽  
Rex D. Sherwood ◽  
...  
Keyword(s):  
Cluster Size ◽  
Surface Coverage ◽  
Metal Clusters ◽  
High Energy ◽  
Cluster Ions ◽  
Rare Gas ◽  
Ion Sputtering ◽  
Transition Metal Clusters ◽  
X Ray

ABSTRACTUsing high energy rare gas ion sputtering of metal targets, we are able to produce nanoamps of mass selected transition metal clusters. Mono-sized cluster ions are deposited at low kinetic energy upon substrates, e.g. silica or carbon, and are then characterized using UV and x-ray photoemission. In this paper we will discuss photoemission measurements of the 4f7/2 core level energies of Au (1–5,7 atom samples) clusters deposited on silica. From such studies we are beginning to understand how electronic structure, cluster stability and mobility depend on (deposited) cluster size, surface coverage, and substrate temperature.

HIGH ENERGY SYNCHROTRON X-RAY MICROSPECTROSCOPY FOR GEOCHEMICAL CHARACTERIZATION OF TERRESTRIAL AND EXTRATERRESTRIAL SAMPLES

2016 ◽  
Author(s):  
Antonio Lanzirotti ◽  
◽  
Stephen R. Sutton ◽  
Matt Newville ◽  
Jeffrey P. Fitts ◽  
...  
Keyword(s):  
High Energy ◽  
Geochemical Characterization ◽  
X Ray

scholarly journals Characterization of Advanced High-Energy Density Li-S Batteries by FE-AEM, SEM/EDS X-ray Spectral Imaging and Feature Sizing/Chemical Typing Techniques

2009 ◽  
Vol 15 (S2) ◽  
pp. 1398-1399 ◽  
Author(s):  
VP Oleshko ◽  
C Scordilis-Kelley ◽  
A Xiao ◽  
J Affinito ◽  
Y Talyossef ◽  
...  
Keyword(s):  
Energy Density ◽  
Spectral Imaging ◽  
High Energy ◽  
High Energy Density ◽  
X Ray

Extended abstract of a paper presented at Microscopy and Microanalysis 2009 in Richmond, Virginia, USA, July 26 – July 30, 2009

scholarly journals Microfluidic electrochemical cell for in situ structural characterization of amorphous thin-film catalysts using high-energy X-ray scattering

2019 ◽  
Vol 26 (5) ◽  
pp. 1600-1611 ◽  
Author(s):  
Gihan Kwon ◽  
Yeong-Ho Cho ◽  
Ki-Bum Kim ◽  
Jonathan D. Emery ◽  
In Soo Kim ◽  
...  
Keyword(s):  
Thin Film ◽  
Thin Films ◽  
Electrochemical Cell ◽  
Porous Electrode ◽  
High Energy ◽  
Porous Electrodes ◽  
X Ray ◽  
Pdf Analysis ◽  
Thin Film Catalysts

Porous, high-surface-area electrode architectures are described that allow structural characterization of interfacial amorphous thin films with high spatial resolution under device-relevant functional electrochemical conditions using high-energy X-ray (>50 keV) scattering and pair distribution function (PDF) analysis. Porous electrodes were fabricated from glass-capillary array membranes coated with conformal transparent conductive oxide layers, consisting of either a 40 nm–50 nm crystalline indium tin oxide or a 100 nm–150 nm-thick amorphous indium zinc oxide deposited by atomic layer deposition. These porous electrodes solve the problem of insufficient interaction volumes for catalyst thin films in two-dimensional working electrode designs and provide sufficiently low scattering backgrounds to enable high-resolution signal collection from interfacial thin-film catalysts. For example, PDF measurements were readily obtained with 0.2 Å spatial resolution for amorphous cobalt oxide films with thicknesses down to 60 nm when deposited on a porous electrode with 40 µm-diameter pores. This level of resolution resolves the cobaltate domain size and structure, the presence of defect sites assigned to the domain edges, and the changes in fine structure upon redox state change that are relevant to quantitative structure–function modeling. The results suggest the opportunity to leverage the porous, electrode architectures for PDF analysis of nanometre-scale surface-supported molecular catalysts. In addition, a compact 3D-printed electrochemical cell in a three-electrode configuration is described which is designed to allow for simultaneous X-ray transmission and electrolyte flow through the porous working electrode.

Single Crystal Wurtzitic Aluminum Nitride Growth on Silicon Using Supersonic Gas Jets

1995 ◽  
Vol 395 ◽  
Author(s):  
S. A. Ustin ◽  
L. Lauhon ◽  
K. A. Brown ◽  
D. Q. Hu ◽  
W. Ho
Keyword(s):  
Aluminum Nitride ◽  
Growth Rates ◽  
High Energy ◽  
X Ray Diffraction ◽  
Rutherford Back Scattering ◽  
X Ray ◽  
Supersonic Molecular Beam ◽  
Supersonic Beams ◽  
Wide Range

ABSTRACTHighly oriented aluminum nitride (0001) films have been grown on Si(001) and Si (111) substrates at temperatures between 550° C and 775° C with dual supersonic molecular beam sources. Triethylaluminum (TEA;[(C2H5)3Al]) and ammonia (NH3) were used as precursors. Hydrogen, helium, and nitrogen were used as seeding gases for the precursors, providing a wide range of possible kinetic energies for the supersonic beams due to the disparate masses of the seed gases. Growth rates of AIN were found to depend strongly on the substrate orientation and the kinetic energy of the incident precursor; a significant increase in growth rate is seen when seeding in hydrogen or helium as opposed to nitrogen. Growth rates were 2–3 times greater on Si(001) than on Si(111). Structural characterization of the films was done by reflection high energy electron diffraction (RHEED) and x-ray diffraction (XRD). X-ray rocking curve (XRC) full-width half-maxima (FWHM) were seen as small as 2.5°. Rutherford back scattering (RBS) was used to determine the thickness of the films and their chemical composition. Films were shown to be nitrogen rich, deviating from perfect stoichiometry by 10%–20%. Surface analysis was performed by Auger electron spectroscopy (AES).

Synthesis of Transition Metal Clusters and Their Catalytic and Optical Properties

1992 ◽  
Vol 286 ◽  
Author(s):  
J. P. Wilcoxon ◽  
A. Martino ◽  
R.L. Baughmann ◽  
E. Klavetter ◽  
A.P. Sylwester
Keyword(s):  
Optical Properties ◽  
Metal Clusters ◽  
Control Strategies ◽  
Size Control ◽  
Transition Metal Clusters ◽  
X Ray ◽  
Surfactant Aggregates ◽  
Gold Silver ◽  
Pd Clusters ◽  
Average Size

ABSTRACTMetal Clusters may be synthesized in the interior of surfactant aggregates called inverse micelles. These nanosize chemical reactors permit the controlled growth of several types of metal clusters. We describe this process for the formation of Au, Ag, Pd, Pt and Ir clusters and cluster alloys. Two size-control strategies are described: 1)variation of micelle size by alteration of the surfacant and/or solvent combination used, and 2) judicious use of micelle interactions or phase behavior. Using these two methods size control in the range of 1-100 nm is possible. The optical properties of metal clusters of gold, silver, and gold/silver alloys are described and the surface plasmon resonances are shown to have dramatic blue shifts and extensive line broadening with decreasing size in the range of 10-1 nm. In the case of gold clusters, the distinct resonancein the visible disappears for sizes less than 2.0 nm and new features appear in the UV. The optical spectra of alloys of gold and silver are shown to differ dramatically from their homoatomic counterparts of the same average size. We use electron and X-ray diffraction to determine the phase structure of the metal clusters and small angle X-ray scattering, neutron scattering, light scattering and TEM to characterize the average size and size distributions of these clusters. Finally, we describe measurements of the catalytic activity of Pd clusters and demonstrate a dramatic increase in hydrogenation activity on the size range of 2-10 nm.

Interface Characterization of PbTe/BaSi/Si Heterostructures Grown Using MBE

1992 ◽  
Vol 281 ◽  
Author(s):  
F. Santiago ◽  
D. Woody ◽  
T. K. Chu ◽  
C. A. Huber
Keyword(s):  
Photoelectron Spectroscopy ◽  
High Energy ◽  
Substrate Material ◽  
Interfacial Region ◽  
X Ray ◽  
Interface Characterization ◽  
Spectroscopy Studies ◽  
Molecular Layers ◽  
Similar Growth

ABSTRACTA new substrate material consisting of a buffer layer of a Ba-Si compound was developed by making use of the chemical reaction between BaF2 and Si. This substrate is very promising for the integration of IV-VI semiconductor materials with silicon. PbTe films of excellent quality, as determined by X-ray and Reflected High Energy Electron Diffraction spectra, have been deposited over (111)- and (100)-oriented silicon wafers of 3 inch diameter. These PbTe films are (100)-oriented irrespective of the Si orientation. X-ray photoelectron spectroscopy studies reveal very interesting chemistry at the interface between Ba-Si and Te. They suggest that BaTe may form between PbTe and Ba-Si at their interface. This interfacial region, which is of the order of only a few molecular layers, appears to be critical in the success of the deposition. Thermal cycling showed that the PbTe/BaSi/Si system is mechanically very stable. The possibility of a similar growth mechanism for the deposition of II-VI semiconductors such as CdTe is considered.

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