| Sidewall Covalent Functionalization of Single Wall Carbon Nanotubes through C-N Bond Forming Reactions of Fluoronanotubes with Urea, Guanidine and Thiourea (Preprint) |
Apr 2007 |
22 pages |
| Authors:
Merlyn X Pulikkathara; Valery N Khabashesku; RICE UNIV HOUSTON TX DEPT OF CHEMISTRY
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 | Sidewall covalent functionalization of carbon nanotubes is necessary to achieve smaller bundles, link to other functional moieties, and to aid in better dispersion in composites. In the present study, we present a one-step functionalization method which uses fluorinated single wall carbon nanotubes (F-SWNTs) as starting materials in the reactions with either urea, thiourea, or guanidine. Through these reactions, the derivatives with terminal amide and heteroamide groups on the nanotube sidewalls ... |
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| A Study of the Formation, Purification, Ligand Substitution Chemistry, and Application as a SWNT Growth Catalyst of the Nanocluster (Preprint) |
FEB 2006 |
55 pages |
| Authors:
Robin E. Anderson; Jr. Colorado Ramon; Christopher Crouse; Douglas Ogrin; Christopher L. Edwards; Elizabeth Whitsitt; Valerie C. Moore; Dorothy Koveal; Corina Lupu; Michael Stewart; RICE UNIV HOUSTON TX DEPT OF CHEMISTRY
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| The synthetic conditions for the isolation of the iron-molybdenum nanoc1uster FeMoC, along with its application as a catalyst precursor for VLS growth of SWNTs have been studied. As prepared FeMoC is contaminated with the Keplerate cage without the Keggin template; however, extraction of pure FeMoC may be accomplished by Soxhlet extraction with EtOH. The resulting EtOH solvate is consistent with the replacement of the water ligands coordinated to Fe being ... |
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| Solid State Synthesis and Characterization of Carbo-Nitride Materials |
10 JUL 2000 |
12 pages |
| Authors:
Valery N. Khabashesku; John L. Margrave; RICE UNIV HOUSTON TX DEPT OF CHEMISTRY
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| The preparation of stoichiometric sp(sup 2)-bonded amorphous carbon nitride a-C3N4 in gram quantities was successfully achieved by performing a solid-state reaction of cyanuric halides C3N3X3 (X=Cl, F) with lithium nitride L3N at temperatures 300-380 deg C. Addition of boron precursors, e. g., NaBF4, resulted in preparation of a nitrogen-rich BC-N powder of approximately B3C3N7 composition and showing thermal stability up to temperatures of 1000 deg ... |
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| Group III Materials: New Phases and Nano-Particles with Applications in Electronics and Optoelectronics |
31 DEC 1999 |
6 pages |
| Authors:
Andrew R. Barron; RICE UNIV HOUSTON TX DEPT OF CHEMISTRY
|
| Objectives: 1. Demonstrate molecular control for the MOCVD growth of gallium and indium chalcogenides. 2. Demonstrate a molecular model approach to the prediction of suitable binding groups to semiconductor surfaces. 3. Demonstrate the application of surface coordination chemistry to the control over the electronic properties of semiconductor nanoparticles. |
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| Density Functional Theory for Large Molecular Systems and Application to Metcars |
FEB 1998 |
7 pages |
| Authors:
Gustavo E. Scuseria; RICE UNIV HOUSTON TX DEPT OF CHEMISTRY
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| During the grant period, we developed a major improvement in the calculation of the Coulomb term appearing in ab initio electronic structure methods based on Gaussian orbitals. Our efficient implementation of the Gaussian very Fast Multipole Method (GvFMM) combines speed, accuracy, and linear scaling properties. The method is clearly superior to state-or-the-art analytic integration techniques of Gaussian functions. Our benchmarks on graphitic sheets containing more than 400 atoms and 3,500 ... |
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| Energy and Chemical Change |
28 FEB 97 |
4 pages |
| Authors:
James L. Kinsey; Raphael D. Levine; RICE UNIV HOUSTON TX DEPT OF CHEMISTRY
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| This theoretical proposal sought to characterize processes in systems in extreme disequilibrium with special reference to the role of electronically non adiabatic processes. The two major accomplishments are: (1) The demonstration that real chemistry (i.e., bond formation, rearrangements etc). is possible under extreme conditions of temperature and pressure. In particular, it was proposed how air can be made to 'burn'. Private communication (December 1996) from two laboratories are that this ... |
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| Tert-Butyl Alumoxanes: Synthetic Analogs for Methyl Alumoxane (MAO) and New Catalytic Routes to Polyolefins and Polyketones |
01 JUL 96 |
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| Authors:
Andrew R. Barron; RICE UNIV HOUSTON TX DEPT OF CHEMISTRY
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 | Alumoxanes are the products from the partial hydrolysis of aluminum compounds. While they have been known for over 30 years, and as a class of chemical are highly important industrially, there has been almost no basic understanding of their structure, reactivity, or potential as new inorganic polymers. The aim of this research was to gain a fundamental understanding of alumoxanes and to enable multiple practical applications to be generated from ... |
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| Group III Materials: Molecular Design of New Phases with Applications in Electronics and Optoelectronics |
JUL 96 |
9 pages |
| Authors:
Andrew R. Barron; RICE UNIV HOUSTON TX DEPT OF CHEMISTRY
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| Determination of Thermophysical Properties of Liquid Metals at High Temperatures by Levitation Methods |
1994 |
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| Authors:
John L. Margrave; RICE UNIV HOUSTON TX DEPT OF CHEMISTRY
|
| Levitation techniques offer unique opportunities for the accurate determination of thermophysical properties of liquid metals and alloys at high temperatures. supercooled liquid metals can be studied at temperatures 200-500 k below their freezing points. keywords: tic, aluminum, copper, niobium, platinum, silicon, titanium, zirconium, borides, carbides, crystallization, ellipsometry, enthalpy, heat of fusion, nucleation, oxides, reflectivity, refractive index, skin, spectral radiance, surface tension, viscosity, optical pyrometry, thermophysical properties. |
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| Progress Toward Atomic Layer Epitaxy of Diamond Using Radical Chemistry |
29 MAY 93 |
14 pages |
| Authors:
R. Gat; T. I. Hukka; M. P. D'Evelyn; RICE UNIV HOUSTON TX DEPT OF CHEMISTRY
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| A novel method for atomic layer epitaxy (ALE) of diamond using radical reactants under medium vacuum conditions is being developed. Precursor molecules are injected into a stream of thermally-dissociated fluorine atoms, generating radicals in a chemically specific way. We have grown diamond particles at rates of approximately 0.1 micrometers/hr on polycrystalline copper and nickel wire substrates seeded by diamond particles from continuous flows of F/F2, H2, and C2H3 or Ch4 ... |
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| Infrared Spectroscopy of Hydrogen and Water on Diamond (100) |
29 MAY 93 |
11 pages |
| Authors:
L. M. Struck; M. P. D'Evelyn; RICE UNIV HOUSTON TX DEPT OF CHEMISTRY
|
| The absorption of deuterium and water on diamond (100) has been investigated by infrared multiple-internal-reflection spectroscopy using a natural type IIa diamond internal reflection element. Evidence was seen for both monohydride surface species (CD deformation mode at 901/cm) and dihydride species (CD2 deformation mode at 1125/cm). Following exposure to water at elevated temperature, infrared modes were detected at 1280, 1200, 1125, 1080, and 720/cm, and are assigned to ether (C-O-C), ... |
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| Investigation of Diamond Homoepitaxy by In Situ Fizeau Interferometry: The Role of Oxygen |
29 MAY 93 |
9 pages |
| Authors:
Robin E. Rawles; Carter Kittrell; Mark P. D'Evelyn; RICE UNIV HOUSTON TX DEPT OF CHEMISTRY
|
| Optical Fizeau interferometry has been employed as an in situ probe of growth rate and surface morphology in diamond homoepitaxy. The spatial fringe pattern produced by interference between HeNe laser light reflected from the front and back faces of a diamond single crystal is imaged, providing a map of the local substrate thickness. Growth causes the fringe pattern to propagate laterally, enabling in situ monitoring of thickness changes as small ... |
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| Progress Toward Atomic Layer Epitaxy of Diamond: Diamond Films Grown One Layer at a Time |
MAY 93 |
5 pages |
| Authors:
Roy Gat; Terttu I. Hukka; Robin E. Rawles; Mark P. D'Evelyn; RICE UNIV HOUSTON TX DEPT OF CHEMISTRY
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| Diamond would be the ultimate coating for many applications: it is the hardest material known, is chemically inert in most environments, has a thermal conductivity five times that cooper, and is optically transparent from ultraviolet through the mid- and far-infrared. However, conventional CVD methods for diamond have important limitations-many substrates of interest cannot withstand the 500-1000 degree C temperatures commonly employed, and the typically low nucleation density generates films with ... |
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| Surface Pi Bonding and the Near-First-Order Desorption Kinetics of Hydrogen from Ge(100)2x1 |
11 DEC 92 |
12 pages |
| Authors:
Mark P. D'Evelyn; Stephen M. Cohen; Eric Rouchouze; Yuemei L. Yang; RICE UNIV HOUSTON TX DEPT OF CHEMISTRY
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| We show by temperature-programmed desorption that hydrogen desorbs from Ge(100)2xl near 570 K with near-first-order kinetics, similar to the behavior of hydrogen on Si(100)2xl. The near-first-order desorption Kinetics are attributed to pairing on surface dimers induced by the n bond on unoccupied dimer atoms, and a pairing enthalpy of 5 + or - 1 kcal/mol is inferred. However, a comparison between the pairing enthalpies for H atoms on Ge(100) and ... |
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| Pairing and Clustering of Hydrogen on Si(100)2x1: Monte Carlo Studies |
11 DEC 92 |
16 pages |
| Authors:
Yuemei L. Yang; Mark P. D'Evelyn; RICE UNIV HOUSTON TX DEPT OF CHEMISTRY
|
| We consider a generalization of the doubly-occupied dimer model we proposed recently to explain the near-first-order desorption kinetics of H2 from Si(100)2xl, incorporating effective nearest-neighbor interactions between paired hydrogen atoms on adjacent dimers. We have performed Monte Carlo simulations of the generalized model, and compare the pairing and cluster-size distributions with those observed recently by scanning tunneling microscopy (STM). The agreement is reasonable but the cluster size distributions differ in ... |
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| Competitive Pairing and the Chemistry of Coadsorbed Hydrogen and Halogens on Ge(100) |
11 DEC 92 |
8 pages |
| Authors:
Yuemei L. Yang; Stephen M. Cohen; Mark P. D'Evelyn; RICE UNIV HOUSTON TX DEPT OF CHEMISTRY
|
| The chemistry of coadsorbed H and X (X=Cl, Br) on semiconductor surfaces is important in epitaxial growth of silicon from chlorosilanes and of Si(x)Ge(l-x) alloys, in hydrogenating/ halogenating cycles in atomic layer epitaxy, and also provides an interesting model system, yet has received little attention to date. We have investigated the interaction of HCl and HBr with Ge(100) by temperature-programmed desorption, and find that H2, HCl and HBr each desorb ... |
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| Low-Pressure Diamond Growth Using a Secondary Radical Source |
11 DEC 92 |
8 pages |
| Authors:
Terttu I. Hukka; Robin E. Rawles; Mark P. D'Evelyn; RICE UNIV HOUSTON TX DEPT OF CHEMISTRY
|
| A novel method for chemical vapor deposition and atomic layer epitaxy using radical precursors under medium vacuum conditions is being developed. Fluorine atoms are generated by thermal dissociation in a hot tube and abstract hydrogen atoms from precursor molecules injected immediately downstream of the source, generating radicals with complete chemical specificity. The radical precursors are then transported to the growing substrate surface under nearly collision-free conditions. To date we have ... |
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| Interaction of Hydrogen and Water with Diamond (100): Infrared Spectroscopy |
DEC 92 |
15 pages |
| Authors:
Lisa M. Struck; Mark P. D'Evelyn; RICE UNIV HOUSTON TX DEPT OF CHEMISTRY
|
| We report the first investigation of the adsorption of deuterium and water on diamond (100) by infrared multiple-internal-reflection spectroscopy using a natural type IIa diamond internal reflection element. Infrared evidence was seen for the monohydride surface structure, with one hydrogen atom per surface carbon atom (Delta CD mode at 901 cm-1), while the dihydride (CD2) structure was not observed. Following exposure to water at elevated temperature, infrared absorption features were ... |
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| Hydrogen-Halogen Chemistry on Semiconductor Surfaces |
29 JUN 92 |
12 pages |
| Authors:
Stephen M. Cohen; Terttu I. Hukka; Mark P. D'Evelyn; RICE UNIV HOUSTON TX DEPT OF CHEMISTRY
|
| The chemistry of coadsorbed H and X (X-Cl, Br) on semiconductor surfaces is important in epitaxial growth of silicon from chlorosilanes and of SixGe1-x in hydrogenating/halogenating cycles in atomic layer epitaxy, and also provides an interesting model system, yet has received little attention to date. We have investigated the interaction of H, HCl, and HBr with Ge(100) by temperature-programmed desorption, and find that H2, HCl, and HBr each absorb with ... |
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| Growth Kinetics of (100), (110), and (111) Homoepitaxial Diamond Films |
29 JUN 92 |
10 pages |
| Authors:
C. J. Chu; R. H. Hauge; J. L. Margrave; M. P. D'Evelyn; RICE UNIV HOUSTON TX DEPT OF CHEMISTRY
|
| Diamond film growth by chemical vapor deposition (CVD) has burgeoned rapidly during the past decade, accompanied by considerable progress in fundamental understanding. Particular progress has been made in understanding chemistry taking place in the gas phase above the substrate and in identification of the precuror(s) primarily responsible for growth, but the details of reactions taking place on the growing surface are as yet unknown. However, despite the commercial importance of ... |
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| Novel Method for Chemical Vapor Deposition and Atomic Layer Epitaxy Using Radical Chemistry |
29 JUN 92 |
17 pages |
| Authors:
T. I. Hukka; R. E. Rawles; M. P. D'Evelyn; RICE UNIV HOUSTON TX DEPT OF CHEMISTRY
|
| A novel method for chemical vapor deposition and atomic layer epitaxy using radical precursors under high vacuum conditions is being developed. The combination of selectively- generated radicals and high vacuum is ideal for low- temperature growth: growth rates remain relatively high because activation energies for radical reactions are typically small, and contamination and segregation are minimized by keeping the surface 'capped' by adsorbed intermediates and working under ultraclean conditions. Fluorine ... |
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| Chemistry of Hydrogen on Diamond (100) |
29 JUN 92 |
19 pages |
| Authors:
Y. L. Yang; L. M. Ulvick; L. F. Sutcu; M. P. D'Evelyn; RICE UNIV HOUSTON TX DEPT OF CHEMISTRY
|
| Hydrogen plays a crucial role in diamond film growth by chemical vapor deposition and is likely to be similarly critical to atomic layer epitaxy, yet the surface chemistry of hydrogen on diamond is only beginning to be understood. We have investigated the adsorption of hydrogen and deuterium on diamond (100) by temperature-programmed desorption and by infrared multiple- internal-reflection spectroscopy using a natural type IIa diamond internal reflection element. Complementary theoretical ... |
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| Homoepitaxial Growth Rate Studies on Diamond (110), (111), and (100) Surfaces in a Hot-Filament Reactor |
29 MAY 92 |
8 pages |
| Authors:
C. J. Chu; Benjamin J. Bai; Norma J. Komplin; Donald E. Patterson; Mark P. D'Evelyn; RICE UNIV HOUSTON TX DEPT OF CHEMISTRY
|
| Growth rates of homoepitaxial (1 10), (I 1 1), and (100) diamond films were experimentally determined, for the first time, in a hot filament reactor using methane and carbon tetrachloride as the carbon source. Methane concentrations from 0.07% to 1.03% in H2 were studied at a subsum temperature of 970 'C. Growth ran were found to be crystal-face dependent with respect to methane concentration, being linear or first order for ... |
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| Theoretical Studies of Clean and Hydrogenated Diamond (100) by Molecular Mechanics |
29 MAY 92 |
18 pages |
| Authors:
Yuemei L. Yang; Mark P. D'Evelyn; RICE UNIV HOUSTON TX DEPT OF CHEMISTRY
|
| The atomic structure and energetics of the clean (100)-(2xl), (100)- (2xl):H monohydride, (100)-(1xl):2H full dihydride, (100)-(3xl): 1.33H intermediate dihydride, and other intermediate hydride surfaces obtained by local removal of H atoms from or addition of H atoms to the (2xl) monohydride, are investigated by molecular mechanics (MM3). The monohydride phase is found to be the most stable thermodynamically and is predicted to be the dominant phase under chemical vapor deposition ... |
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| Atomic Force Microscopy of (100), (110), and (111) Homoepitaxial Diamond Films |
29 MAY 92 |
33 pages |
| Authors:
L. F. Sutcu; C. J. Chu; M. S. Thompson; R. H. Hauge; J. L. Musgrave; RICE UNIV HOUSTON TX DEPT OF CHEMISTRY
|
| We present atomic force microscopy images of diamond films grown by chemical vapor deposition epitaxially on diamond (100), (110), and (111) substrates. The films were grown from 0.2-1.6% mixtures of CH4 and C2H2 and H2 in a hot-filament reactor at a total pressure of 25 Torr. The substrate and filament temperatures were held at 810-1000 deg C and 2000-2150 deg C, respectively. A (100)-oriented diamond film grown with 0.3% CH4 ... |
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| Semiconductor Cluster Surface Chemistry |
02 AUG 90 |
21 pages |
| Authors:
Richard E. Smalley; RICE UNIV HOUSTON TX DEPT OF CHEMISTRY
|
| The combination of laser-vaporization supersonic cluster beam techniques with the technology of fourier transform ion cyclotron resonance, FT- ICR, has opened a new approach to the detailed fundamental understanding of semiconductor surface chemistry. With this apparatus it is possible to trap clusters of a specific size in a superconducting magnet under ultrahigh vacuum conditions. Through collisions with an inert thermalizing gas it is possible to slowly cool the clusters down ... |
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| Ultraviolet Photoelectron Spectra of Gallium Arsenide Clusters |
23 JUL 90 |
18 pages |
| Authors:
C. Jin; K. J. Taylor; J. Conceicao; R. E. Smalley; RICE UNIV HOUSTON TX DEPT OF CHEMISTRY
|
| The ultraviolet photoelectron spectra (UPS) of mass-selected negative gallium arsenide cluster ions in the 2-50 atom size range was measured with a photon energy of 7.9 eV. The measured photodetachment thresholds displayed a strong even/odd oscillation through the largest clusters in this range, suggesting the presence of a substantial HOMO-LUMO gap in the corresponding neutral clusters which evolves to the band gap of bulk GaAs crystals. Keywords: Surface chemistry; Ultraviolet ... |
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| Ethylene Chemisorption on Levitated Silicon Cluster Ions: Evidence for Annealing |
23 JUL 90 |
23 pages |
| Authors:
K. R. Anderson; S. Maruyama; R. E. Smalley; RICE UNIV HOUSTON TX DEPT OF CHEMISTRY
|
| Mass-selected silicon clusters were levitated in a Fourier transform ion cyclotron resonance mass spectrometer (FT-ICR), and monitored during chemisorption reaction with ethylene. The reactivity of the six positively charged clusters studied here varied sharply as a function of cluster size, indicating that ethylene is as sensitive a probe of the cluster surface chemistry as reported previously for ammonia. As with ammonia, the 39th and the 45th clusters were found to ... |
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| Ammonia Chemisorption on Gallium Arsenide Clusters |
23 JUL 90 |
19 pages |
| Authors:
Lihong Wang; L. P. Chibante; F. K. Tittel; R. F. Curl; R. E. Smalley; RICE UNIV HOUSTON TX DEPT OF CHEMISTRY
|
| Gallium arsenide clusters in the 6-16 atom size range were generated by laser vaporization in a supersonic nozzle and trapped as positive ions in Fourier transform ion-cyclotron resonance mass spectrometer. Measurements of the rate of attachment of ammonia revealed that all clusters larger than seven atoms were most reactive near the 1/1 composition ratio of gallium/arsenic. The results suggest that even at this small size the clusters begin to adopt ... |
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| Laser Annealing of Silicon Clusters |
23 JUL 90 |
12 pages |
| Authors:
S. Maruyama; Lila R. Anderson; Richard E. Smalley; RICE UNIV HOUSTON TX DEPT OF CHEMISTRY
|
| Positive silicon cluster ions prepared by laser vaporization in a supersonic beam and trapped in an ion cyclotron resonance cell were probed in chemisorption reactions with ethylene and ammonia. Clusters in the 36-51 atom size range were effectively annealed to unique structural forms by excitation with an XeCl excimer laser followed by cooling through infrared radiation and collisions with argon. Keywords: Surface chemistry; Laser annealing; Silicon clusters; Laser vaporization. (jhd) ... |
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| Direct Injection Supersonic Cluster Beam Source for FT-ICR Studies of Clusters |
23 JUL 90 |
23 pages |
| Authors:
Shigeo Maruyame; Lila R. Anderson; Richard E. Smalley; RICE UNIV HOUSTON TX DEPT OF CHEMISTRY
|
| A miniaturized pulsed supersonic beam source has been developed using laser vaporization of a computer-controlled target disc, producing intense beams of cluster ions with excellent repeatability and control. Due to its small size and narrow pulse width, the entire source is adequately pumped by a single 170 1/s turbopump. The resultant vacuum quality permits this source to be attached to a fourier transform ion cyclotron resonance apparatus (FT-ICR) such that ... |
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| Ammonia Chemisorption Studies on Silicon Cluster Ions |
23 JUL 90 |
46 pages |
| Authors:
J. M. Alford; R. T. Laaksonen; R. E. Smalley; RICE UNIV HOUSTON TX DEPT OF CHEMISTRY
|
| Silicon clusters in the size range from 5 to 66 atoms were generated by laser vaporization in a supersonic nozzle and injected into the ion trap of a specially-designed Fourier transform ion cyclotron resonance apparatus. On the positively charged clusters ammonia chemisorption reaction rates were found to vary by over three orders of magnitude as a function of cluster size, with clusters of 21, 25, 33, 39, and 45 atoms ... |
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| THERMODYNAMIC AND KINETIC STUDIES OF BORIDES AND OTHER REFRACTORY MATERIALS AT HIGH TEMPERATURES. |
MAY 1966 |
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| Authors:
John L. Margrave; RICE UNIV HOUSTON TX DEPT OF CHEMISTRY
|
| The reactions of elementary fluorine with several refractory elements (B, C, Si, Zr and Ir) and with several refractory compounds (TiC, TiB2, WC and W2B5) have been quantitatively observed and rate equations derived. The products of fluorination have isolated and studied to provide further information. For example, solid CF(x), the reaction product between graphite and F2 at low temperatures, has been thermally decomposed and the products characterized by gas chromatography ... |
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| CHEMICAL REACTIONS IN HIGH TEMPERATURE SYSTEMS. |
11 APR 1966 |
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| Authors:
John L. Margrave; RICE UNIV HOUSTON TX DEPT OF CHEMISTRY
|
| The possibilities of utilizing DC- and RF-plasma jet devices for chemical synthesis are being explored. The successful synthesis of NO is described. Other major efforts were directed to the use of plasma devices for studying high temperature reactions (all gas or gas-solid) in various environments (N2, O2, Cl2, F2). Techniques for introduction and reaction of solids were evaluated by studying oxidation, nitridation, chlorination, and thermal decomposition reactions. (Author) |
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| THERMODYNAMIC AND KINETIC STUDIES OF BORIDES AND OTHER REFRACTORY MATERIALS AT HIGH TEMPERATURE. |
AUG 1965 |
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| Authors:
John L. Margrave; RICE UNIV HOUSTON TX DEPT OF CHEMISTRY
|
| The fluorination rates of elementary boron, silican and carbon and of TiB2 have been determined over wide ranges of temperature and fluorine partial pressures. The thermal decomposition of solid CF has been shown by gas chromatographic and mass spectrometric techniques to yield a variety of perfluorocarbons with up to 16 carbon atoms. High temperature heat capacities have been measured and analytical expressions representing experimental data over wide ranges of temperature ... |
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