[News Clip: Aylor] captions transcript

[News Clip: Aylor]

Video footage from the KXAS-TV/NBC station in Fort Worth, Texas, to accompany a news story.
Date: August 1, 1994, 5:00 p.m.
Creator: KXAS-TV (Television station : Fort Worth, Tex.)
Object Type: Video
System: The UNT Digital Library
Measurement of {alpha}{sub s} from hadronic event observables at the Z{sup 0} resonance (open access)

Measurement of {alpha}{sub s} from hadronic event observables at the Z{sup 0} resonance

The authors have measured the strong coupling {alpha}{sub s} using hadronic decays of Z{sup 0} bosons collected by the SLD experiment at SLAC. The data were compared with QCD predictions both at fixed order, O({alpha}{sub s}{sup 2}), and including resummed analytic formulae based on the leading and next-to-leading logarithm approximation. The study includes event shapes, jet rates, and particle correlations. They checked the consistency between {alpha}{sub s} extracted from these different measures and found the dominant uncertainty on {alpha}{sub s} to be from uncalculated higher order contributions.
Date: August 1, 1994
Creator: Ohnishi, Yukiyoshi
Object Type: Article
System: The UNT Digital Library
A summary of the report on prospects for pyrolysis technologies in managing municipal, industrial, and Department of Energy cleanup wastes (open access)

A summary of the report on prospects for pyrolysis technologies in managing municipal, industrial, and Department of Energy cleanup wastes

Pyrolysis converts portions of municipal solid wastes, hazardous wastes and special wastes such as tires, medical wastes and even old landfills into solid carbon and a liquid or gaseous hydrocarbon stream. In the past twenty years, advances in the engineering of pyrolysis systems and in sorting and feeding technologies for solid waste industries have ensured consistent feedstocks and system performance. Some vendors now offer complete pyrolysis systems with performance warranties. This report analyzes the potential applications of pyrolysis in the Long Island region and evaluates the four most promising pyrolytic systems for their readiness, applicability to regional waste management needs and conformity with DOE environmental restoration and waste management requirements. This summary characterizes the engineering performance, environmental effects, costs, product applications and markets for these pyrolysis systems.
Date: August 1, 1994
Creator: Reaven, S. J.
Object Type: Report
System: The UNT Digital Library
Models for recurrent gas release event behavior in hazardous waste tanks (open access)

Models for recurrent gas release event behavior in hazardous waste tanks

Certain radioactive waste storage tanks at the United States Department of Energy Hanford facilities continuously generate gases as a result of radiolysis and chemical reactions. The congealed sludge in these tanks traps the gases and causes the level of the waste within the tanks to rise. The waste level continues to rise until the sludge becomes buoyant and ``rolls over``, changing places with heavier fluid on top. During a rollover, the trapped gases are released, resulting, in a sudden drop in the waste level. This is known as a gas release event (GRE). After a GRE, the wastes leading to another GRE. We present nonlinear time waste re-congeals and gas again accumulates leading to another GRE. We present nonlinear time series models that produce simulated sample paths that closely resemble the temporal history of waste levels in these tanks. The models also imitate the random GRE, behavior observed in the temporal waste level history of a storage tank. We are interested in using the structure of these models to understand the probabilistic behavior of the random variable ``time between consecutive GRE`s``. Understanding the stochastic nature of this random variable is important because the hydrogen and nitrous oxide gases released from …
Date: August 1, 1994
Creator: Anderson, D. N. & Arnold, B. C.
Object Type: Article
System: The UNT Digital Library
Basic TRUEX process for Rocky Flats Plant (open access)

Basic TRUEX process for Rocky Flats Plant

The Generic TRUEX Model was used to develop a TRUEX process flowsheet for recovering the transuranics (Pu, Am) from a nitrate waste stream at Rocky Flats Plant. The process was designed so that it is relatively insensitive to changes in process feed concentrations and flow rates. Related issues are considered, including solvent losses, feed analysis requirements, safety, and interaction with an evaporator system for nitric acid recycle.
Date: August 1, 1994
Creator: Leonard, R. A.; Chamberlain, D. B.; Dow, J. A.; Farley, S. E.; Nunez, L.; Regalbuto, M. C. et al.
Object Type: Report
System: The UNT Digital Library
Adventures in the evolution of a high-bandwidth network for central servers (open access)

Adventures in the evolution of a high-bandwidth network for central servers

In a small network, clients and servers may all be connected to a single Ethernet without significant performance concerns. As the number of clients on a network grows, the necessity of splitting the network into multiple sub-networks, each with a manageable number of clients, becomes clear. Less obvious is what to do with the servers. Group file servers on subnets and multihomed servers offer only partial solutions -- many other types of servers do not lend themselves to a decentralized model, and tend to collect on another, well-connected but overloaded Ethernet. The higher speed of FDDI seems to offer an easy solution, but in practice both expense and interoperability problems render FDDI a poor choice. Ethernet switches appear to permit cheaper and more reliable networking to the servers while providing an aggregate network bandwidth greater than a simple Ethernet. This paper studies the evolution of the server networks at SLAC. Difficulties encountered in the deployment of FDDI are described, as are the tools and techniques used to characterize the traffic patterns on the server network. Performance of Ethernet, FDDI, and switched Ethernet networks is analyzed, as are reliability and maintainability issues for these alternatives. The motivations for re-designing the SLAC …
Date: August 1, 1994
Creator: Swartz, K. L.; Cottrell, L. & Dart, M.
Object Type: Article
System: The UNT Digital Library
Pilot-scale treatability test plan for the 100-HR-3 operable unit (open access)

Pilot-scale treatability test plan for the 100-HR-3 operable unit

This document presents the treatability test plan for pilot-scale pump-and-treat testing at the 100-HR-3 Operable Unit. The test will be conducted in fulfillment of interim Milestone M-15-06E to begin pilot-scale pump-and-treat operations by August 1994. The scope of the test was determined based on the results of lab/bench-scale tests (WHC 1993a) conducted in fulfillment of Milestone M-15-06B. These milestones were established per agreement between the U.S. Department of Energy (DOE), the Washington State Department of Ecology and the U.S. Environmental Protection Agency (EPA), and documented on Hanford Federal of Ecology Facility Agreement and Consent Order Change Control Form M-15-93-02. This test plan discusses a pilot-scale pump-and-treat test for the chromium plume associated with the D Reactor portion of the 100-HR-3 Operable Unit. Data will be collected during the pilot test to assess the effectiveness, operating parameters, and resource needs of the ion exchange (IX) pump-and-treat system. The test will provide information to assess the ability to remove contaminants by extracting groundwater from wells and treating extracted groundwater using IX. Bench-scale tests were conducted previously in which chromium VI was identified as the primary contaminant of concern in the 100-D reactor plume. The DOWEX 21K{trademark} resin was recommended for pilot-scale testing …
Date: August 1, 1994
Creator: unknown
Object Type: Report
System: The UNT Digital Library
High gradient tests of SLAC Linear Collider Accelerator Structures (open access)

High gradient tests of SLAC Linear Collider Accelerator Structures

This paper describes the current SLAC R&D program to develop room temperature accelerator structures for the Next Linear Collider (NLC). The structures are designed to operate at 11.4 GHz at an accelerating gradient in the range of 50 to 100 MV/m. In the past year a 26 cm constant-impedance traveling-wave section, a 75 cm constant-impedance traveling-wave section, and a 1.8 m traveling-wave section with detuned deflecting modes have been high-power tested. The paper presents a brief description of the RF test setup, the design and manufacturing details of the structures, and a discussion of test results including field emission, RF processing, dark current spectrum and RF breakdown.
Date: August 1, 1994
Creator: Wang, J. W.; Deruyter, H.; Eichner, J.; Fant, K. H.; Hoag, H. A.; Koontz, R. F. et al.
Object Type: Article
System: The UNT Digital Library
A finite element analysis of room temperature silicon crystals for the Advanced Photon Source bending-magnet and insertion-device beams (open access)

A finite element analysis of room temperature silicon crystals for the Advanced Photon Source bending-magnet and insertion-device beams

The third generation of synchrotron radiation sources, such as the Advanced Photon Source (APS), will provide users with a high brilliance x-ray beam with high power and power densities. In many cases, the first optical component to intercept the x-ray beam is a silicon-crystal monochromator. Due to extreme heat loading, the photon throughput and brilliance will be severely degraded if the monochromator is not properly designed (or cooled). This document describes a series of finite element analyses performed on room temperature silicon for the three standard APS sources, namely, the bending magnet, Wiggler A, and Undulator A. The modeling is performed with the silicon cooled directly with water or liquid gallium through rectangular channels. The temperature distributions and thermally induced deformations are presented.
Date: August 1, 1994
Creator: Assoufid, L.; Lee, W. K. & Mills, D. M.
Object Type: Report
System: The UNT Digital Library
The analysis and specification of large high-pressure, high-temperature valves for combustion turbine protection in second-generation PFB power plants: Topical report (open access)

The analysis and specification of large high-pressure, high-temperature valves for combustion turbine protection in second-generation PFB power plants: Topical report

The purpose of this study was to provide a specification for the high-pressure/high-temperature valves for turbine overspeed protection in a commercial-scale second-generation pressurized fluidized bed combustion (PFBC) power plant. In the event of a loss of external (generator) load, the gas turbine rapidly accelerates from its normal operating speed. Protection from excessive overspeed can be maintained by actuation of fuel isolation and air bypass valves. A design specification for these valves was developed by analyses of the turbine/compressor interaction during a loss of load and analyses of pressure and flow transients during operation of the overspeed protection valves. The basis for these analyses was the Phase 1 plant conceptual design prepared in 1987.
Date: August 1, 1994
Creator: unknown
Object Type: Report
System: The UNT Digital Library
A chemical model for the major electrolyte components of the Hanford waste tanks. The binary electrolytes in the system: Na-NO{sub 3}-NO{sub 2}-SO{sub 4}-CO{sub 3}-F-PO{sub 4}-OH-AI(OH){sub 4}-H{sub 2}O (open access)

A chemical model for the major electrolyte components of the Hanford waste tanks. The binary electrolytes in the system: Na-NO{sub 3}-NO{sub 2}-SO{sub 4}-CO{sub 3}-F-PO{sub 4}-OH-AI(OH){sub 4}-H{sub 2}O

An aqueous thermodynamic model is developed, based on the equations of Pitzer, which accurately model the major binary electrolytes in the Na-NO{sub 3}-NO{sub 2}-SO{sub 4}-CO{sub 3}-F-PO{sub 4}-OH-Al(OH){sub 4}-H{sub 2}O chemical system. This model was developed both from existing data in the literature, and from new osmotic and solubility measurements made as part of this study. Some of the new experimental data developed as part of this study include measurements of osmotic coefficients for NaNO{sub 3}, NaNO{sub 2}, and Na{sub 3}PO{sub 4} at both 50 and 100{degrees}C as well as selected measurements of NaF at 100{degrees}C. In addition, the solubility of gibbsite was measured in mixed NaOH-NaNO{sub 3} solutions to determine the reliability of existing thermodynamic models of aluminum hydroxide solubility when applied to concentrated nitrate. In general the final model proposed here is valid from dilute solution to salt saturation over the temperature range 25-100{degrees}C. The accuracy of the model is tested by comparisons of the model predictions with experimental data in selected common-ion ternary systems. When necessary a few commonion ternary ion interaction parameters for the Pitzer model were developed.
Date: August 1, 1994
Creator: Felmy, A. R.; Rustad, J. R.; Mason, M. J. & Bretonne, R. de la
Object Type: Article
System: The UNT Digital Library
Identification of radionuclides of concern in Hanford Site environmental cleanup (open access)

Identification of radionuclides of concern in Hanford Site environmental cleanup

The purpose of this document is to consider which radionuclides should be included in conducting environmental surveys relative to site remediation at Hanford. During the operation of the Hanford site, the fission product radionuclides and a large number of activation products including the transuranic radionuclides were formed. The reactor operations and subsequent chemical processing and metallurgical operations resulted in the environmental release of gaseous and liquid effluents containing some radionuclides; however, the majority of the radionuclides were stored in waste tanks or disposed to trenches and cribs. Since some contamination of both soils and subsurface waters occurred, one must decide which radionuclides still remain in sufficient amounts to be of concern at the time when site remediation is to be complete. Many of the radionuclides which have constituted the principal hazard during site operation have half-lives on the order of a year or less; therefore, they will have decayed to insignificant amounts by the year 2030, a possible date for completion of the remediation process.
Date: August 1, 1994
Creator: Perkins, R. W. & Jenquin, U. P.
Object Type: Report
System: The UNT Digital Library
Faster magnet sorting with a threshold acceptance algorithm (open access)

Faster magnet sorting with a threshold acceptance algorithm

The authors introduce here a new technique for sorting magnets to minimize the field errors in permanent magnet insertion devices. Simulated annealing has been used in this role, but they find the technique of threshold acceptance produces results of equal quality in less computer time. Threshold accepting would be of special value in designing very long insertion devices, such as long FEL`s. Their application of threshold acceptance to magnet sorting showed that it converged to equivalently low values of the cost function, but that it converged significantly faster. They present typical cases showing time to convergence for various error tolerances, magnet numbers, and temperature schedules.
Date: August 1, 1994
Creator: Lidia, S. & Carr, R.
Object Type: Article
System: The UNT Digital Library
A study of K{sub s} {Lambda} and {bar {Lambda}} production in hadronic Z{sup 0} decays (open access)

A study of K{sub s} {Lambda} and {bar {Lambda}} production in hadronic Z{sup 0} decays

We present a preliminary measurement of the inclusive production rates of K{sub s}, A and X hadrons produced in e{sup +}e{sup {minus}} annihilation at the Z{sup 0} pole. The analysis is based upon approximately 50K Z{sup 0} decays collected in the SLD experiment at SLAC in 1993. The observed rates of (K{sub s}) = 1.02 {plus_minus} 0.02 {plus_minus} 0.09 and ({Lambda}) + ({bar {Lambda}}) = 0.38 {plus_minus} 0.01 {plus_minus} 0.04 are consistent with previous measurements. Our differential cross section peak-position results are shown to be consistent with QCD predictions based on the modified leading logarithm approximation and local parton-hadron duality.
Date: August 1, 1994
Creator: Baird, K. G.
Object Type: Article
System: The UNT Digital Library
Phase II Water Rental Pilot Project: Snake River Resident Fish and Wildlife Resources and Management Recommendations. (open access)

Phase II Water Rental Pilot Project: Snake River Resident Fish and Wildlife Resources and Management Recommendations.

The Idaho Water Rental Pilot Project was implemented in 1991 as part of the Non-Treaty Storage Fish and Wildlife Agreement between Bonneville Power Administration and the Columbia Basin Fish and Wildlife Authority. The goal of the project is to quantify resident fish and wildlife impacts resulting from salmon flow augmentation releases made from the upper Snake River Basin. Phase I summarized existing resource information and provided management recommendations to protect and enhance resident fish and wildlife habitat resulting from storage releases for the I improvement of an adromous fish migration. Phase II includes the following: (1) a summary of recent biological, legal, and political developments within the basin as they relate to water management issues, (2) a biological appraisal of the Snake River between American Falls Reservoir and the city of Blackfoot to examine the effects of flow fluctuation on fish and wildlife habitat, and (3) a preliminary accounting of 1993--1994 flow augmentation releases out of the upper Snake, Boise, and Payette river systems. Phase III will include the development of a model in which annual flow requests and resident fish and wildlife suitability information are interfaced with habitat time series analysis to provide an estimate of resident fish and …
Date: August 1, 1994
Creator: Stovall, Stacey H.
Object Type: Report
System: The UNT Digital Library
Pilot-scale treatability test plan for the 200-BP-5 operable unit (open access)

Pilot-scale treatability test plan for the 200-BP-5 operable unit

This document presents the treatability test plan for pilot-scale pump and treat testing at the 200-BP-5 Operable Unit. This treatability test plan has been prepared in response to an agreement between the U.S. Department of Energy (DOE), the U.S. Environmental Protection Agency (EPA), and the State of Washington Department of Ecology (Ecology), as documented in Hanford Federal Facility Agreement and Consent Order (Tri-Party Agreement, Ecology et al. 1989a) Change Control Form M-13-93-03 (Ecology et al. 1994) and a recent 200 NPL Agreement Change Control Form (Appendix A). The agreement also requires that, following completion of the activities described in this test plan, a 200-BP-5 Operable Unit Interim Remedial Measure (IRM) Proposed Plan be developed for use in preparing an Interim Action Record of Decision (ROD). The IRM Proposed Plan will be supported by the results of this treatability test plan, as well as by other 200-BP-5 Operable Unit activities (e.g., development of a qualitative risk assessment). Once issued, the Interim Action ROD will specify the interim action(s) for groundwater contamination at the 200-BP-5 Operable Unit. The treatability test approach is to conduct a pilot-scale pump and treat test for each of the two contaminant plumes associated with the 200-BP-5 Operable …
Date: August 1, 1994
Creator: unknown
Object Type: Report
System: The UNT Digital Library
Melter feed tank operating map from the FA-10.02 test data (open access)

Melter feed tank operating map from the FA-10.02 test data

The operability of the Melter Feed Tank (MFT) feed loops has been tested during the DWPF-FA-10.02 test. The ability to feed the melter at three distinct melter feed rates (0.20, 0.45, and 0.90 gpm), two distinct agitator speeds (65 and 130 rpm), varying liquid levels, and varying slurry rheologies was tested. This report correlates the operability of the feed loops with the above mentioned variables. The data are presented in the form of operating maps, Figs. 1 through 4, which are plots of the liquid level versus the wt% total solids (and yield stress) for two agitator speeds. The maps are divided into regions of acceptable feed loop operation and unacceptable feed loop operation. This report does not consider how closely the compositions of the MFT, the melter feed lines, and the Hydragard samples agree. The significant observations in this report are as follows: Both feed loops satisfy the operability criteria down to a liquid level below the upper impeller blade at low speed agitation (65 rpm). Under high speed agitation (130 rpm), feed loop No. 2 operates much more poorly than feed loop No. 1. The uncertainty associated with the wt% total solids of a slurry sample is larger …
Date: August 1, 1994
Creator: Spatz, T. L.
Object Type: Report
System: The UNT Digital Library
A solubility model for amorphous silica in concentrated electrolytes (open access)

A solubility model for amorphous silica in concentrated electrolytes

Silica is one of the major constituents of the earth`s crust and is ubiquitously present in most natural materials. The solubility of silica and other silica-containing compounds is, therefore, of primary concern in geochemistry and in chemical processing applications where silica scale formation, resulting from changes in temperature and electrolyte composition, can cause problems in process design and operation. This paper describes the development of an aqueous thermodynamic model for accurately predicting the solubility of amorphous silica and other silica-containing compounds in the system Na{sup +}-H{sup +}-Mg{sup 2+}-NO{sub 3}{sup {minus}}-SO{sub 4}{sup 2{minus}}-Cl{sup {minus}}-H{sub 2}O to high concentration and across the temperature range 25--100 C. This model, which utilizes the aqueous thermodynamic model of Pitzer, includes only one dissolved silica species, H{sub 4}SiO{sub 4}(aq), and is valid in neutral to very acidic solutions. The model is parameterized from the extensive set of solubility data in the literature as well as from new experimental data on amorphous silica solubility in HNO{sub 3} and HCl developed as part of this study. The accuracy of the model is tested on solutions more complex than those used in model parameterization.
Date: August 1, 1994
Creator: Felmy, A. R.; Schroeder, C. C. & Mason, M. J.
Object Type: Report
System: The UNT Digital Library
The discovery of the tau lepton: Part 1, The early history through 1975; Part 2, Confirmation of the discovery and measurement of major properties, 1976--1982 (open access)

The discovery of the tau lepton: Part 1, The early history through 1975; Part 2, Confirmation of the discovery and measurement of major properties, 1976--1982

Several previous papers have given the history of the discovery of the {tau} lepton at the Stanford Linear Accelerator Center (SLAC). These papers emphasized (a) the experiments which led to our 1975 publication of the first evidence for the existence of the {tau}, (b) the subsequent experiments which confirmed the existence of the r, and (c) the experiments which elucidated the major properties of the {tau}. That history will be summarized in Part 2 of this talk. In this Part 1, I describe the earlier thoughts and work of myself and my colleagues at SLAC in the 1960`s and early 1970`s which led to the discovery. I also describe the theoretical and experimental events in particle physics in the 1960`s in which our work was immersed. I will also try to describe for the younger generations of particle physicists, the atmosphere in the 1960`s. That was before the elucidation of the quark model of hadrons, before the development of the concept of particle generations The experimental paths to program we hot as clear as they are today and we had to cast a wide experimental net.
Date: August 1, 1994
Creator: Perl, M. L.
Object Type: Article
System: The UNT Digital Library
Low-cost packaging of high-performance optoelectronic components (open access)

Low-cost packaging of high-performance optoelectronic components

Optoelectronic component costs are often dominated by the costs of attaching fiber optic pigtails--especially for the case of single transverse mode devices. We present early results of our program in low-cost packaging. We are employing machine-vision controlled automated positioning and silicon microbench technology to reduce the costs of optoelectronic components. Our machine vision approach to automated positioning has already attained a positional accuracy of less than 5 microns in less than 5 minutes; accuracies and times are expected to improve significantly as the development progresses. Complementing the machine vision assembly is our manufacturable approach to silicon microbench technology. We will describe our silicon microbench optoelectronic device packages that incorporate built-in heaters for solder bonding reflow.
Date: August 1, 1994
Creator: Lowry, M.; Lu, Shin-Yee; Pocha, M. & Strand, O. T.
Object Type: Article
System: The UNT Digital Library
Wide-area traffic: The failure of Poisson modeling (open access)

Wide-area traffic: The failure of Poisson modeling

Network arrivals are often modeled as Poisson processes for analytic simplicity, even though a number of traffic studies have shown that packet interarrivals are not exponentially distributed. The authors evaluate 21 wide-area traces, investigating a number of wide-area TCP arrival processes (session and connection arrivals, FTPDATA connection arrivals within FTP sessions, and TELNET packet arrivals) to determine the error introduced by modeling them using Poisson processes. The authors find that user-initiated TCP session arrivals, such as remote-login and file-transfer, are well-modeled as Poisson processes with fixed hourly rates, but that other connection arrivals deviate considerably from Poisson; that modeling TELNET packet interarrivals as exponential grievously underestimates the burstiness of TELNET traffic, but using the empirical Tcplib[DJCME92] interarrivals preserves burstiness over many time scales; and that FTPDATA connection arrivals within FTP sessions come bunched into ``connection bursts``, the largest of which are so large that they completely dominate FTPDATA traffic. Finally, they offer some preliminary results regarding how the findings relate to the possible self-similarity of wide-area traffic.
Date: August 1, 1994
Creator: Paxson, V. & Floyd, S.
Object Type: Article
System: The UNT Digital Library
Savannah River Technology Center monthly report: August 1994 (open access)

Savannah River Technology Center monthly report: August 1994

Short summaries are given for 45 projects concerned with tritium, separations, environmental, and general topics. Included in the general topics are the following: Burst test qualification analysis of Defense Waste Processing Facility canister-plug weld; Design and development of sampling plans for non-radioactive hazardous waste; Thermal fluids laboratory melter feed test; FRR spent fuel dry storage development; SRTC buildings fire hazards analysis; and SRTC plutonium vulnerability study.
Date: August 1, 1994
Creator: unknown
Object Type: Report
System: The UNT Digital Library
The solubility of Cr(OH){sub 3}(am) in concentrated NaOH and NaOH-NaNO{sub 3} solutions (open access)

The solubility of Cr(OH){sub 3}(am) in concentrated NaOH and NaOH-NaNO{sub 3} solutions

Chromium is a major component of the Hanford waste tank sludges, and the presence of Cr in the sludges is a significant concern in the disposal of these sludges because Cr can interfere with the formation of waste glasses. One of the current pretreatment strategies for removing constituents that can interfere with glass formation, such as P and Cr, is to wash/dissolve the sludges in basic NaOH solutions. The solubility of Cr(OH){sub 3}(am) was measured in concentrated NaOH ranging in concentration from 0.1M to 6.0M and in NaOH-NaNO{sub 3} solutions with fixed NaOH concentration and variable NaNO{sub 3} concentration at room temperature (22--23 C). Equilibrium between solids and solutions was approached relatively slowly and required approximately 60--70 days before steady-state concentrations were reached. A thermodynamic model, based upon the Pitzer equations, was developed from the solubility data in NaOH, which includes only two aqueous Cr species (Cr(OH){sub 4}{sup {minus}} and NaCr(OH){sub 4}(aq)) and ion-interaction parameters for Na{sup +} with Cr(OH){sub 4}{sup {minus}}. This model was then tested in the mixed NaOH-NaNO{sub 3} solutions and found to be reliable.
Date: August 1, 1994
Creator: Felmy, A. R.; Rai, D. & Fulton, R. W.
Object Type: Report
System: The UNT Digital Library
Photoemission and optical properties of C{sub 60} fullerites (open access)

Photoemission and optical properties of C{sub 60} fullerites

A theory is presented for excitations in undoped, solid C{sub 60} involving addition or removal of an electron, as well as creation of an electron-hole pair. Excitation energies are computed using a quasiparticle description of electrons and holes, plus a model for electron-hole interactions. Results are compared with those of direct and inverse photoelectron and optical absorption spectroscopy studies. Reasonable agreement is found in such comparisons, while more complete modeling of experimental spectra might include neglected matrix-element and vibrational effects. These results give values for simple, conceptual parameters, such as a molecular Hubbard U. Some results could also be relevant in doped fullerites.
Date: August 1, 1994
Creator: Shirley, E. L. & Louie, S. G.
Object Type: Article
System: The UNT Digital Library