Diosmacycloalkanes as models for the formation of hydrocarbons from surface methylenes (open access)

Diosmacycloalkanes as models for the formation of hydrocarbons from surface methylenes

We have obtained a neutron diffraction data set for Os{sub 2}(CO){sub 8}({mu}-C{sub 2}H{sub 4}). While the structure is still being solved, it is already clear that the hybridization at both of the ethylene carbons is sp{sup 3}. Our first interpretation of our liquid crystal NMR results had suggested a very acute H-C-H angle. We have also obtained {sup 13}C liquid crystal data for Os{sub 2}(CO){sub 8}({mu}-C{sub 2}H{sub 4}). Liquid crystal NMR ({sup 13}C as well as {sup 1}H) spectra have been obtained for Os(CO){sub 4}(C{sub 2}H{sub 4}) and its solution structure determined, in order to test our methodology on a molecule with a rigid structure. The normal modes of Os(CO){sub 4}({mu}-C{sub 2}H{sub 4}) and its deuterated and {sup 13}C-labelled isotopomers have been completely assigned. A partial vibrational analysis of Os{sub 2}(CO){sub 8}({mu}-propene), Os{sub 2}(CO){sub 8}(trans-2-butene), and Os{sub 2}(CO){sub 8}(1-butene) has been completed. We have prepared Os(CO){sub 4}({mu}-CH{sub 2}CH{sub 2}CH{sub 2}) and its 3,3-dideuterio analog. In the course of this work the reaction of Na{sub 2}Os(CO){sub 4} with a number of 1,3-propanediol derivatives has been examined. 1,3-Propanediol ditosylate afforded much better yields of the osmacycle than did either the ditriflate or diiodide. 2,2-Dideutero-1,3-propanediol ditosylate was used to prepare the deuterium-labelled osmacyclobutane.
Date: January 1, 1989
Creator: Norton, J.R.
Object Type: Report
System: The UNT Digital Library
Diosmacycloalkanes as models for the formation of hydrocarbons from surface methylenes. Progress report, April 1, 1988--March 31, 1989 (open access)

Diosmacycloalkanes as models for the formation of hydrocarbons from surface methylenes. Progress report, April 1, 1988--March 31, 1989

We have obtained a neutron diffraction data set for Os{sub 2}(CO){sub 8}({mu}-C{sub 2}H{sub 4}). While the structure is still being solved, it is already clear that the hybridization at both of the ethylene carbons is sp{sup 3}. Our first interpretation of our liquid crystal NMR results had suggested a very acute H-C-H angle. We have also obtained {sup 13}C liquid crystal data for Os{sub 2}(CO){sub 8}({mu}-C{sub 2}H{sub 4}). Liquid crystal NMR ({sup 13}C as well as {sup 1}H) spectra have been obtained for Os(CO){sub 4}(C{sub 2}H{sub 4}) and its solution structure determined, in order to test our methodology on a molecule with a rigid structure. The normal modes of Os(CO){sub 4}({mu}-C{sub 2}H{sub 4}) and its deuterated and {sup 13}C-labelled isotopomers have been completely assigned. A partial vibrational analysis of Os{sub 2}(CO){sub 8}({mu}-propene), Os{sub 2}(CO){sub 8}(trans-2-butene), and Os{sub 2}(CO){sub 8}(1-butene) has been completed. We have prepared Os(CO){sub 4}({mu}-CH{sub 2}CH{sub 2}CH{sub 2}) and its 3,3-dideuterio analog. In the course of this work the reaction of Na{sub 2}Os(CO){sub 4} with a number of 1,3-propanediol derivatives has been examined. 1,3-Propanediol ditosylate afforded much better yields of the osmacycle than did either the ditriflate or diiodide. 2,2-Dideutero-1,3-propanediol ditosylate was used to prepare the deuterium-labelled osmacyclobutane.
Date: January 1, 1989
Creator: Norton, J. R.
Object Type: Report
System: The UNT Digital Library
Consultation draft: Site characterization plan overview, Deaf Smith County Site, Texas: Nuclear Waste Policy Act (Section 113) (open access)

Consultation draft: Site characterization plan overview, Deaf Smith County Site, Texas: Nuclear Waste Policy Act (Section 113)

The Department of Energy (DOE) is preparing a site characterization plan for the candidate site in Deaf Smith County, Texas. The DOE has provided, for information and review, a consultation draft of the plan to the State of Texas and the US Nuclear Regulatory Commission. The site characterization plan is a lengthy document that describes in considerable detail the program that will be conducted to characterize the geologic, hydrologic, and other conditions relevant to the suitability of the site for a repository. The overview presented here consists of brief summaries of important topics covered in the consultation draft of the site characterization plan; it is not a substitute for the site characterization plan. The arrangement of the overview is similar to that of the plan itself, with brief descriptions of the repository system - the site, the repository, and the waste package - preceding the discussion of the characterization program to be carried out at the Deaf Smith County site. It is intended primarily for the management staff of organizations involved in the DOE's repository program or other persons who might wish to understand the general scope of the site-characterization program, the activities to be conducted, and the facilities to …
Date: January 1, 1988
Creator: unknown
Object Type: Report
System: The UNT Digital Library
Interplanetary propulsion using inertial fusion (open access)

Interplanetary propulsion using inertial fusion

Inertial fusion can be used to power spacecraft within the solar system and beyond. Such spacecraft have the potential for short-duration manned-mission performance exceeding other technologies. We are conducting a study to assess the systems aspects of inertial fusion as applied to such missions, based on the conceptual engine design of Hyde (1983) we describe the required systems for an entirely new spacecraft design called VISTA that is based on the use of DT fuel. We give preliminary design details for the power conversion and power conditioning systems for manned missions to Mars of total duration of about 100 days. Specific mission performance results will be published elsewhere, after the study has been completed.
Date: January 1, 1987
Creator: Orth, C.D.; Hogan, W.J.; Hoffman, N.; Murray, K.; Klein, G. & Diaz, F.C.
Object Type: Article
System: The UNT Digital Library
Analysis of temperature-time data from 3 m drillholes at Crystal Hot Springs, Utah (open access)

Analysis of temperature-time data from 3 m drillholes at Crystal Hot Springs, Utah

A method for determining the background geothermal gradient values through the analysis of temperature measurements at multiple depths to 3 m and recorded over a time span of several days is presented. The analysis is based on the amplitude decay and phase shift of temperature waves with depth. Diurnal and other high frequency temperature variations are used to compute thermal diffusivities which in turn are used to model and remove the effect of the annual temperature wave. The analysis considers both a homogeneous half space and a two layer medium consisting of an overburden of finite thickness overlying a semi-infinite substratum. The method was tested in three holes in the Crystal Hot Springs geothermal field. Temperatures in each hole were recorded once a minute over a period of three days with a probe containing thermistors at eight different depths. Five of the thermistors were positioned at shallow depths (less than or equal to 0.5 m) to monitor diurnal and other high frequency waves and three at greater depths (greater than or equal to 1 m) to measure lower frequency variations. Since measurements were recorded at only three sites, the accuracy and reliability of the method is not fully evaluated. Potential …
Date: January 1, 1986
Creator: Howell, Jack & Chapman, David S.
Object Type: Report
System: The UNT Digital Library
Comparison of the Response of a Nai Scintillation Crystal With a Pressurized Ionization Chamber as a Function of Altitude, Radiation Level and RA-226 Concentration (open access)

Comparison of the Response of a Nai Scintillation Crystal With a Pressurized Ionization Chamber as a Function of Altitude, Radiation Level and RA-226 Concentration

The Grand Junction Uranium Mill Tailings Remedial Action-Radiological Survey Activities Group (UMTRA-RASA) program employs a screening method in which external exposure rates are used to determine if a property contaminated with uranium mill tailings is eligible for remedial action. Portable NaI detectors are used by survey technicians to locate contaminated areas and determine exposure rates. The exposure rate is calculated using a regression equation derived from paired measurements made with a pressurized ionization chamber (PIC) and a NaI detector. During July of 1985 extensive measurements were taken using a PIC and a NaI scintillator with both analogue and digital readout for a wide range of exposure rates and at a variety of elevations. The surface soil was sampled at most of these locations and analyzed for /sup 226/Ra. The response of the NaI detectors was shown to be highly correlated to radiation level but not to /sup 226/Ra concentration or elevation.
Date: January 1, 1986
Creator: Provencher, R.; Smith, G.; Borak, T.B. & Kearney, P.
Object Type: Article
System: The UNT Digital Library
MHD waves detected by ice at distances > 28 x 10/sup 6/ km from Comet Halley: Cometary or solar wind origin (open access)

MHD waves detected by ice at distances > 28 x 10/sup 6/ km from Comet Halley: Cometary or solar wind origin

Spectral analyses of the high resolution magnetic field data are employed to determine if there is evidence of cometary heavy ion pickup when ICE was closest to Halley, approx.28 x 10/sup 6/ km. No evidence is found for the presence of heavy ion cyclotron waves. However, from this search, two new wave modes are discovered in the solar wind: electromagnetic ion cyclotron waves and drift mirror mode waves. Both modes have scales of 10 to 60 s (1 to 6 T/sub p/) in the spacecraft frame. The possibility of wave generation by cometary hydrogen pickup is explored. Theoretical arguments and further experimental evidence indicates that cometary origin is improbable. The most likely source is plasma instabilities associated with solar wind stream-stream interactions. VLF electrostatic emissions are found to occur in field minima or at gradients of the drift mirror structures. Possible generation mechanisms of drift mirror mode waves, cyclotron waves and electrostatic waves are discussed.
Date: January 1, 1986
Creator: Tsurutani, B. T.; Brinca, A. L.; Smith, E. J.; Thorne, R. M.; Scarf, F. L.; Gosling, J. T. et al.
Object Type: Article
System: The UNT Digital Library
Observations of heavy energetic ions for upstream from comet Halley (open access)

Observations of heavy energetic ions for upstream from comet Halley

On March 25, 1986, the ICE spacecraft came within 28 x 10/sup 6/ km of the nucleus of comet Halley. For several days around this time, bursts of heavy ions were observed by the ICE energetic ion experiment. These bursts were observed only during periods when the solar wind velocity was considerably higher than its nominal value. We examine the characteristics of these ions, in particular their anisotropies. Using the well known formulae for transformation of distributions from the solar wind frame of reference to the spacecraft frame, we examine the angular distributions expected from either protons, or heavy ions from the water group, and show that the measurements are consistent with heavy ions, and not with protons. We discuss other sources of heavy ions and conclude that the most likely source of these ions is comet Halley. 9 refs., 5 figs.
Date: January 1, 1986
Creator: Sanderson, T. R.; Wenzel, K. P.; Daly, P. W.; Cowley, S. W. H.; Hynds, R. J.; Richardson, I. G. et al.
Object Type: Article
System: The UNT Digital Library
The P/Giacobini-Zinner Magnetotail (open access)

The P/Giacobini-Zinner Magnetotail

On September 11, 1985 the International Cometary Explorer passed behind Comet Giacobini-Zinner with a closest approach distance of 7800 km. In agreement with Alfven's interplanetary magnetic field line draping model of cometary type I tails, a well defined 1 x 10/sup 4/ km diameter magnetotail was observed downstream of the inner coma. This study uses the ICE magnetic field, plasma electron, plasma wave, and energetic ion observations to investigate the structure and stability of the Giacobini-Zinner magnetic tail. Emphasis is placed on the identification of differences and similarities between cometary and planetary magnetotails. Finally, the ICE magnetotail observations are discussed in relation to the global solar wind interaction with P/Giacobini-Zinner. 33 refs., 8 figs.
Date: January 1, 1986
Creator: Slavin, J. A.; Smith, E. J.; Daly, P. W.; Flammer, K. R.; Gloeckler, G.; Goldberg, B. A. et al.
Object Type: Article
System: The UNT Digital Library
Rapid estimation of /sup 226/Ra in soil for the Grand Junction RASA/UMTRA project (open access)

Rapid estimation of /sup 226/Ra in soil for the Grand Junction RASA/UMTRA project

The Radiological Survey Activities (RASA) Group of the Health and Safety Research Division at Oak Ridge National Laboratory (ORNL) is an Inclusion Survey Contractor (ISC) for the Uranium Mill Tailings Remedial Action Program (UMTRAP). The purpose of the ISC is to survey designated sites potentially contaminated with radioactive material originating from the 24 inactive uranium mill sites and make recommendations as to whether the site should be included in or excluded from further consideration by UMTRAP. An important aspect of the program is a prompt and inexpensive estimation of Radium-226 (/sup 226/Ra) concentration in soil samples. A large sodium iodide (NaI) well crystal coupled to a multichannel analyzer is used to count soil samples. Count data are currently analyzed with an algorithm that utilizes three regions of interest (ROI). A lack of agreement was observed when samples were also analyzed with lithium-drifted germanium (GeLi) spectrometers. The average estimate of /sup 226/Ra obtained using the current algorithm was 19% greater than the GeLi determination. Some possible reasons for these differences were examined. In 8.5% of the samples, the relative concentration of Cesium-137 (/sup 137/Cs) was highly correlated to the extent of error. Using alternative analysis techniques, the error for /sup 226/Ra …
Date: January 1, 1986
Creator: Kark, J.B.; Borak, T.B.; Kearney, P.D. & Rood, A.S.
Object Type: Article
System: The UNT Digital Library
Steepened magnetosonic waves in the high. beta. plasma surrounding Comet Giacobini-Zinner (open access)

Steepened magnetosonic waves in the high. beta. plasma surrounding Comet Giacobini-Zinner

We extend the previous studies of intense hydromagnetic waves at Giacobini-Zinner to investigate the mode and direction of wave propagation. Simultaneous high-resolution measurements of electron density fluctuations demonstrate that the long period (approx.100 s) waves are propagating in the magnetosonic mode. Principal axis analyses of the long period waves and accompanying partial rotations show that the sum of the wave phase rotations is 360/sup 0/C, indicating that both are parts of the same wave oscillation. From the time sequence of the steepened waveforms observed by ICE, we demonstrate that the waves must propagate towards the sun with C/sub ph/ < V/sub sw/. All available observations are consistent with wave generation by the resonant ion ring or ion beam instability which predicts right-hand polarized waves propagating in the ion beam (solar) direction. The large amplitudes ..delta.. polarized B/absolute value of Bapprox.0(1) and small scale sizes (rotational discontinuities) of the cometary waves suggest that rapid pitch-angle scattering and energy transfer with energetic ions should occur. Since the waves are highly compressive, ..delta.. absolute value of B/absolute value of B = 0(0.5), one can also anticipate first-order Fermi acceleration. 15 refs., 6 figs.
Date: January 1, 1986
Creator: Tsurutani, B. T.; Smith, E. J.; Thorne, R. M.; Gosling, J. T. & Matsumoto, H.
Object Type: Article
System: The UNT Digital Library
Dual arm master controller development (open access)

Dual arm master controller development

The advanced servomanipulator (ASM) slave was designed with an anthropomorphic stance, gear/torque tube power drives, and modular construction. These features resulted in increased inertia, friction, and backlash relative to tape-driven manipulators. Studies were performed which addressed the human factors design and performance trade-offs associated with the corresponding master controller best suited for the ASM. The results of these studies, as well as the conceptual design of the dual arm master controller, are presented. This work was performed as part of the Consolidated Fuel Reprocessing Program at the Oak Ridge National Laboratory. 5 refs., 7 figs., 1 tab.
Date: January 1, 1985
Creator: Kuban, D. P. & Perkins, G. S.
Object Type: Article
System: The UNT Digital Library
Influence of Geometry on Natural Convection in Buildings (open access)

Influence of Geometry on Natural Convection in Buildings

Strong free convection airflows occur within passive solar buildings resulting from elevated temperatures of surfaces irradiated by solar energy compared with the cooler surfaces not receiving radiation. The geometry of a building has a large influence on the directions and magnitudes of natural airflows, and thus heat transfer between zones. This investigation has utilized a variety of reduced-scale building configurations to study the effects of geometry on natural convection heat transfer. Similarity between the reduced-scale model and a full-scale passive solar building is achieved by having similar geometries and by replacing air with Freon-12 gas as the model's working fluid. Filling the model with Freon-12 gas results in similarity in Prandtl numbers and Rayleigh numbers based on temperature differences in the range from 10/sup 9/ to 10/sup 11/. Results from four geometries are described with an emphasis placed on the effects of heat loss on zone temperature stratification shifts.
Date: January 1, 1985
Creator: White, M. D.; Winn, C. B.; Jones, G. F. & Balcomb, J. D.
Object Type: Article
System: The UNT Digital Library
Low Energy X-Ray Spectra Measured With a Mercuric Iodide Energy Dispersive Spectrometer in a Scanning Electron Microscope (open access)

Low Energy X-Ray Spectra Measured With a Mercuric Iodide Energy Dispersive Spectrometer in a Scanning Electron Microscope

A mercuric iodide energy dispersive x-ray spectrometer, with Peltier cooling provided for the detector and input field effect transistor, has been developed and tested in a scanning electron microscope. X-ray spectra were obtained with the 15 keV electron beam. An energy resolution of 225 eV (FWHM) for Mn-K/sub ..cap alpha../ at 5.9 keV and 195 eV (FWHM) for Mg-K line at 1.25 keV has been measured. Overall system noise level was 175 eV (FWHM). The detector system characterization with a carbon target demonstrated good energy sensitivity at low energies and lack of significant spectral artifacts at higher energies. 16 refs., 5 figs.
Date: January 1, 1985
Creator: Iwanczyk, J. S.; Dabrowski, A. J.; Huth, G. C.; Bradley, J. G.; Conley, J. M. & Albee, A. L.
Object Type: Article
System: The UNT Digital Library
Neutral sheet crossings in the distant magnetotail (open access)

Neutral sheet crossings in the distant magnetotail

We have analyzed the magnetic field data from ISEE-3 in the distant magnetotail for 18 crossings of the cross-tail current sheet (or so-called natural sheet) to determine the direction of the normal component B/sub z/. The crossings occurred near the middle of the aberrated magnetotail (0 < y < 30 R/sub e, -10 < z < 5) in GSM coordinates, at a distance of about 220 R/sub e/, January 28 to February 12, 1983; in each case the plasma flow velocity was tailward. In 2 cases we found B/sub z/ negative (southward), as would be required with a magnetic neutral line (reconnection line) earthward of the spacecraft. In 12 cases B/sub z/ was clearly northward (B/sub z/ > 0.4 nT), consistent with closed field lines connected to the earth. In 3 cases B/sub z/ was very close to zero; in several instances there was structure in B/sub y/, suggesting localized currents with x or z directions. One may have been a magnetopause crossing. The strong preponderance of northward B/sub z/ favors a model of the magnetotail which is dominated by boundary layer plasma, flowing tailward on closed magnetic field lines, which requires the existence of an electric field in the …
Date: January 1, 1985
Creator: Heikkila, W. J.; Slavin, J. A.; Smith, E. J.; Baker, D. N. & Zwickl, R. D.
Object Type: Article
System: The UNT Digital Library
Launch vehicle integration requirements for SP-100 (open access)

Launch vehicle integration requirements for SP-100

SP-100 is the designation for a nuclear reactor-based power plant being developed for both civil and military missions beginning in the 1990s for such potential space applications as communication satellites, space radar, electric propulsion and space stations. Typically, a system using the SP-100 along with a selected upper stage system would be launched by the National Space Transportation System (NSTS) Space Shuttle System into a near-earth orbit, deployed, and through upper stage propulsion burn(s) be inserted/transferred to its mission orbit. The nature of the advanced design SP-100 gives rise to a set of issues that require special attention to assure that payloads using this power plant are physically and functionally compatible with the NSTS and meet the safety requirements thereof. The purpose of this document is to define and present the requirements and interface provisions that, when satisfied, will ensure technical compability between SP-100 systems and the NSTS.
Date: January 31, 1984
Creator: Shaw, L. T. Jr. & Womack, J. R.
Object Type: Report
System: The UNT Digital Library
Dual arm master controller concept (open access)

Dual arm master controller concept

The Advanced Servomanipulator (ASM) slave was designed with an anthropomorphic stance, gear/torque tube power drives, and modular construction. These features resulted in increased inertia, friction, and backlash relative to tape-driven manipulators. Studies were performed which addressed the human factors design and performance trade-offs associated with the corresponding master controller best suited for the ASM. The results of these studies, as well as the conceptual design of the dual arm master controller, are presented. 6 references, 3 figures.
Date: January 1, 1984
Creator: Kuban, D.P. & Perkins, G.S.
Object Type: Article
System: The UNT Digital Library
External flow radiators for reduced space powerplant temperatures. Technical information report (open access)

External flow radiators for reduced space powerplant temperatures. Technical information report

Nuclear space powerplants can operate at temperatures below 900 K and use stainless steel construction without a weight penalty if new radiator concepts can achieve radiator weights of 1-3 kg/m{sup 2}. Conventional tube-and-fin radiators weight about 10 kg/m{sup 2} because of heavy tube walls to prevent meteroid puncture. Radiator designs that do not require meteroid protection are possible; they operate with fluids of low vapor pressure that can be exposed directly to space in external-flow radiators. An example is the {open_quotes}rotating disk radiator{close_quotes} in which centrifugal force drives a liquid film radially outward across a thin rotating metal disk; meteroid punctures cause no loss of fluid other than from evaporation, which can be small. An even lighter concept is the liquid drop radiator in which heat is radiated directly from moving liquid drops. Such radiator concepts look practical, and they may be much easier to develop than the high-temperature, refractory-metal power systems necessitated by conventional radiators.
Date: January 1, 1984
Creator: Elliott, D. G.
Object Type: Article
System: The UNT Digital Library
Multifoil insulation study for weight reduction. Technical information report (open access)

Multifoil insulation study for weight reduction. Technical information report

The purpose of the present task is to develop high temperature multi-foil insulation suitable for use in the SP-100 thermoelectric converter project. Part of this task involves careful examination of alternative foil and foil spacing materials with the goal of effecting significant weight savings over current state-of-the-art foil insulation. This task involved the determination of the state-of-the-art foils, ascertaining what data is available, what additional data is required, preliminary assessment of the suitability of alternate foil and spacer materials, and specific recommendations for additional tests required to qualify new and existing insulation designs for use in the SP-100.
Date: January 1, 1984
Creator: Glazer, S. D.
Object Type: Report
System: The UNT Digital Library
Space nuclear power system and the design of the nuclear electric propulsion OTV (open access)

Space nuclear power system and the design of the nuclear electric propulsion OTV

Payload increases of three to five times that of the Shuttle/Centaur can be achieved using nuclear electric propulsion. Various nuclear power plant options being pursued by the SP-100 Program are described. These concepts can grow from 100 kW/sub e/ to 1MW/sub e/ output. Spacecraft design aspects are addressed, including thermal interactions, plume interactions, and radiation fluences. A baseline configuration is described accounting for these issues. Safety aspects of starting the OTV transfer from an altitude of 300 km indicate no significant additional risk to the biosphere.
Date: January 1, 1984
Creator: Buden, D. & Garrison, P.W.
Object Type: Article
System: The UNT Digital Library
Geothermal Resources of Southern Idaho (open access)

Geothermal Resources of Southern Idaho

The geothermal resource of southern Idaho as assessed by the U.S. Geological Survey in 1978 is large. Most of the known hydrothermal systems in southern Idaho have calculated reservoir temperatures of less than 150 C. Water from many of these systems is valuable for direct heat applications. A majority of the known and inferred geothermal resources of southern Idaho underlie the Snake River Plain. However, major uncertainties exist concerning the geology and temperatures beneath the plain. The largest hydrothermal system in Idaho is in the Bruneau-Grang View area of the western Snake River Plain with a calculated reservoir temperature of 107 C and an energy of 4.5 x 10 to the 20th power joules. No evidence of higher temperature water associated with this system was found. Although the geology of the eastern Snake River Plain suggests that a large thermal anomaly may underlie this area of the plain, direct evidence of high temperatures was not found. Large volumes of water at temperatures between 90 and 150 C probably exist along the margins of the Snake River Plain and in local areas north and south of the plain.
Date: January 1, 1983
Creator: Mabey, Don R.
Object Type: Report
System: The UNT Digital Library
Refractory materials for high-temperature thermoelectric energy conversion (open access)

Refractory materials for high-temperature thermoelectric energy conversion

Theoretical work of two decades ago adequately explained the transport behavior and effectively guided the development of thermoelectric materials of high conversion efficiencies of conventional semiconductors (e.g., SiGe alloys). The more significant contributions involved the estimation of optimum doping concentrations, the reduction of thermal conductivity by solid solution doping and the development of a variety of materials with ZT approx. 1 in the temperature range 300 K to 1200 K. It was also shown that ZT approx. 1 is not a theoretical limitation although, experimentally, values in excess of one were not achieved. Work has continued with emphasis on higher temperature energy conversion. A number of promising materials have been discovered in which it appears that ZT > 1 is realizable. These materials can be divided into two classes: (i) the rare-earth chalcogenides, which behave as itinerant highly-degenerate n-type semiconductors at room-temperature, and (ii) the boron-rich borides, which exhibit p-type small-polaronic hopping conductivity.
Date: January 1, 1983
Creator: Wood, C. & Emin, D.
Object Type: Article
System: The UNT Digital Library
Semiconductor processing with excimer lasers (open access)

Semiconductor processing with excimer lasers

The advantages of pulsed excimer lasers for semiconductor processing are reviewed. Extensive comparisons of the quality of annealing of ion-implanted Si obtained with XeCl and ruby lasers have been made. The results indicate that irrespective of the large differences in the optical properties of Si at uv and visible wavelengths, the efficiency of usage of the incident energy for annealing is comparable for the two lasers. However, because of the excellent optical beam quality, the XeCl laser can provide superior control of the surface melting and the resulting junction depth. Furthermore, the concentrations of electrically active point defects in the XeCl laser annealed region are 2 to 3 orders of magnitude lower than that obtained from ruby or Nd:YAG lasers. All these results seem to suggest that XeCl lasers should be suitable for fabricating not only solar cells but also the more advanced device structures required for VLSI or VHSIC applications.
Date: January 1, 1983
Creator: Young, R.T.; Narayan, J.; Christie, W.H.; van der Leeden, G.A.; Rothe, D.E. & Cheng, L.J.
Object Type: Article
System: The UNT Digital Library
Approximation of continuity of lenticular Mesaverde Group sandstone lenses utilizing close-well correlations, Piceance Basin, NW Colorado. SPE 11610 (open access)

Approximation of continuity of lenticular Mesaverde Group sandstone lenses utilizing close-well correlations, Piceance Basin, NW Colorado. SPE 11610

Mesaverde Group sandstone units in 13 closely-spaced wells in the central and southern Piceance Basin of Colorado were correlated utilizing wireline log response quantitatively and qualitatively. Based on these correlations, the environmental subdivisions of the Mesaverde Group were characterized as follows: (1) paralic (upper mixed-marine) zone, occurring in the uppermost Mesaverde Group, includes thick sandstone units which are interpreted to be regionally continuous, (2) fluvial zone, containing point-bars 20 to 30+ ft thick, is interpreted to be correlatable to a maximum of 6800 ft, and (3) paludal zone has insufficient data to adequately characterize the sand units. However, 63 percent of the units are correlatable across at least 139 ft. An approximation of the dimensional characteristics of Mesaverde sandstone units has potential applications in designing hydraulic fracturing treatments and estimating gas reserves more accurately. 15 figures, 2 tables.
Date: January 1, 1982
Creator: Peterson, Richard E. & Kohout, Julie B.
Object Type: Report
System: The UNT Digital Library