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Resonance enhanced multiphoton and single-photon ionization of molecules and molecular fragments. Annual technical report, May 1, 1994--April 30, 1995

Description: The overall objective of this work is to carry out quantitative theoretical studies of these laser-driven ionization processes in molecules so as to provide both a robust description of key spectral features of interest in applications and related experiments and needed insight into these spectra. A major focus of this effort is combined theoretical-experimental studies of molecular ion spectra which are being widely studied by the zero-kinetic-energy (ZEKE) technique. This ZEKE technique, which is base3d on pulsed-field ionization (PFI) of very high Rydberg states, makes it possible to obtain ion distributions with sub-wavenumber resolution and is clearly opening up entirely new vistas in studies of molecular ionization. Some highlights of the progress include: (1) The author has extended the theoretical formulation and computational procedures used in these studies of molecular ionization spectra to general polyatomic systems; (2) He has completed combined theoretical-experimental studies of the molecular ion distributions for photoionization of H{sub 2}S, H{sub 2}CO, and CH{sub 3} by coherent VUV radiation; (3) He has carried out the first calculations of the molecular ion rotational distributions for electronically excited states of NO{sup +} (a {sup 3}{Sigma}{sup +}) and CO{sup +} (A {sup 2}{Pi}); (4) he has also completed calculations of the ion rotational distributions for laser ionization of the small prototypical radicals OH, NH, and CH; and (5) Extensions of the studies of molecular photoionization processes of interest here to large polyatomic molecules are computationally quite demanding. These computational demands arise primarily from complexities associated with the quantum mechanical equations which must be solved to obtain the photoelectron wavefunctions required in these studies. To meet these computational needs the author is currently developing strategies for carrying out these calculations on massively parallel computers such as the Intel Paragon and Cray T3D.
Date: December 31, 1995
Creator: McKoy, V.
Partner: UNT Libraries Government Documents Department

Resonance enhanced multiphoton ionization spectra of molecules and molecular fragments. Annual progress report, March 1992--February 1993

Description: In this report, the author will review the progress made in his studies of ion rotational distributions resulting from resonance enhanced multiphoton ionization of excited electronic states and from single-photon ionization of ground electronic states of jet-cooled molecules by coherent VUV and XUV radiation. To do so he will select a few examples from his studies which serve to highlight his progress and to identify the background and significance of the specific spectral features and systems he has chosen to study.
Date: December 31, 1993
Partner: UNT Libraries Government Documents Department

Interaction of far-infrared and mid-infrared laser transitions in the ammonia laser

Description: Mid-infrared laser emission in ammonia is usually observed on a P(J + 2) transition when a CO/sub 2/ laser is used to optically pump a near resonant R(J) absorption feature. However, by generating simultaneous FIR ammonia laser emission in the same optical cavity, mid-infrared emission is obtained exclusively on the P(J) transition.
Date: January 1, 1980
Creator: Nelson, L.Y.; Buchwald, M.I. & Jones, C.R.
Partner: UNT Libraries Government Documents Department

Development of Regenerable High Capacity Boron Nitrogen Hydrides as Hydrogen Storage Materials

Description: The objective of this three-phase project is to develop synthesis and hydrogen extraction processes for nitrogen/boron hydride compounds that will permit exploitation of the high hydrogen content of these materials. The primary compound of interest in this project is ammonia-borane (NH{sub 3}BH{sub 3}), a white solid, stable at ambient conditions, containing 19.6% of its weight as hydrogen. With a low-pressure on-board storage and an efficient heating system to release hydrogen, ammonia-borane has a potential to meet DOE's year 2015 specific energy and energy density targets. If the ammonia-borane synthesis process could use the ammonia-borane decomposition products as the starting raw material, an efficient recycle loop could be set up for converting the decomposition products back into the starting boron-nitrogen hydride. This project is addressing two key challenges facing the exploitation of the boron/nitrogen hydrides (ammonia-borane), as hydrogen storage material: (1) Development of a simple, efficient, and controllable system for extracting most of the available hydrogen, realizing the high hydrogen density on a system weight/volume basis, and (2) Development of a large-capacity, inexpensive, ammonia-borane regeneration process starting from its decomposition products (BNHx) for recycle. During Phase I of the program both catalytic and non-catalytic decomposition of ammonia borane are being investigated to determine optimum decomposition conditions in terms of temperature for decomposition, rate of hydrogen release, purity of hydrogen produced, thermal efficiency of decomposition, and regenerability of the decomposition products. The non-catalytic studies provide a base-line performance to evaluate catalytic decomposition. Utilization of solid phase catalysts mixed with ammonia-borane was explored for its potential to lower the decomposition temperature, to increase the rate of hydrogen release at a given temperature, to lead to decomposition products amenable for regeneration, and direct catalytic hydrogenation of the decomposition products. Two different approaches of heating ammonia-borane are being investigated: (a) 'heat to material approach' in ...
Date: February 3, 2010
Creator: Damle, A.
Partner: UNT Libraries Government Documents Department

Development of a complex compound chill storage system

Description: A thermal energy storage system applicable to industrial refrigeration needs at temperatures as low as {minus}28{degree}C has been developed. The system is based on the chemical bonding between a gaseous refrigerant and a solid salt. The system has been tested successfully in the laboratory and a small unit capable of holding 4 ton-h has been constructed in a factory environment. Much of the development efforts have centered on designing the reactor/heat exchanger where the salt and the refrigerant are combined. Economic evaluations have been made and show an estimated simple rate of return between 30 and 50%. 6 refs., 30 figs.
Date: August 1, 1991
Creator: Rockenfelleer, U. & Kirol, L.
Partner: UNT Libraries Government Documents Department

Ammonia as a hydrogen energy-storage medium. [LH/sub 2/, MeOH, and NH/sub 3/]

Description: Liquid Hydrogen (LH/sub 2/), Methanol (MeOH), and Ammonia (NH/sub 3/) are compared as hydrogen energy-storage media on the basis of reforming the MeOH to produce H/sub 2/ and dissociating (cracking) the NH/sub 3/ to release H/sub 2/. The factors important in this storage concept are briefly discussed. Results of the comparison show that, in terms of energy input for media manufacture from natural gas, hydrogen energy content of the medium, and energy cost ($/10/sup 6/ Btu), NH/sub 3/ has a wide advantage and comes the closest to matching gasoline. The tasks required in developing a safe and practicial hydrogen energy-storage system based on the storage and cracking of NH/sub 3/ are listed. Results of the technical and economic evaluation of this concept will provide the basis for continued development.
Date: August 1, 1980
Creator: Strickland, G
Partner: UNT Libraries Government Documents Department

User's manual for the BNW-II optimization code for dry/wet-cooled power plants

Description: This volume provides a listing of the BNW-II dry/wet ammonia heat rejection optimization code and is an appendix to Volume I which gives a narrative description of the code's algorithms as well as logic, input and output information.
Date: May 1, 1978
Creator: Braun, D.J.; Bamberger, J.A.; Braun, D.J.; Faletti, D.W. & Wiles, L.E.
Partner: UNT Libraries Government Documents Department

Development of solar driven absorption air conditioners and heat pumps

Description: The objective of this project is the development of absorption refrigeration systems for solar active heating and cooling applications. The approaches being investigated are those using air-cooled condenser-absorbers and those leading to coefficient of performances (COP) that increase continuously with heat source temperature. This is primarily an experimental project, with the emphasis on designing, fabricating and testing absorption chillers in operating regimes that are particularly suited for solar energy applications. The first phase of this project has been concluded and has experimentally demonstrated that the conventional single-effect ammonia-water absorption cycle can be used (with minor modifications) for solar cooling. The second phase of this project explores the commercial potential of the single-effect (SE) NH/sub 3//H/sub 2/O absorption air conditioner. (WHK)
Date: March 1, 1980
Creator: Dao, K.; Wahlig, M.; Wali, E.; Rasson, J. & Molishever, E.
Partner: UNT Libraries Government Documents Department

Molecular laser studies in the 7-16. mu. m range. Annual report, 1 June 1975-30 September 1976

Description: An exploratory research effort to find new molecular lasers in the 7-16 ..mu..m wavelength range, in particular lasers with wavelengths at 7.7, 8.6, and 16 ..mu..m wavelengths, is described. The specific initial objectives were: (1) to explore Raman scattering of CO/sub 2/ radiation in a liquid and molecular gas and (2) to explore chemically excited metal fluorides as laser candidates for the 12-16 ..mu..m wavelength range.
Date: October 1, 1976
Creator: Colemen, P.D.
Partner: UNT Libraries Government Documents Department

Multiconfigurational electronic wavefunctions in the full optimized reaction space: the isomerization of nitrosyl hydride to nitrogen hydroxide in the lowest singlet and triplet states

Description: Energy curves are determined for the lowest singlet and triplet states of the HNO molecule. The geometry is varied in that the hydrogen moves through 13 positions around the NO core to describe the isomerization reaction HNO yields HON. Quantitatively determined are the stable and metastable equilibrium positions in both states, the energy differences between these two equilibrium positions and between the two states, and the barriers with respect to isomerization. The calculations are carried out using a novel configuration interaction approach called the Full Optimized Reaction Space method, which involves multiconfigurational self-consistent field calculations as an integral part. In order to interpret the bonding changes occurring during the reaction, a novel type of orbital is developed and calculated. These are called Directed Localized Reaction Orbitals. With their help it proves possible to give an interpretation of the isomerization in terms of concepts which fit chemical intuition.
Date: December 1, 1977
Creator: Dombek, M. G.
Partner: UNT Libraries Government Documents Department

Two-photon optically pumped molecular gas visible laser. [Ammonia]

Description: Recent investigations of the multiphoton ionization (MPI) spectrum of gaseous ammonia have led to the discovery of a novel two-photon pumped molecular gas electronic transition laser. Resonant, two-photon electronic excitation of NH/sub 3/ in the near uv (approx. 305 nm) leads to the first observation of fluorescence from NH/sub 3/ excited states (B and C'), and, at higher pressures, to lasing action (approx. 570 nm) between numerous C' and A state vibronic levels. A frequency-doubled Nd:YAG pumped dye laser (a few mJ) is focused into a cell containing NH/sub 3/ (or ND/sub 3/). Stimulated emission is observed in the forward and backward direction at NH/sub 3/ pressures greater than approx. 200 torr, without external mirrors to provide feedback. Conversion coefficiencies (output NH/sub 3/ pulse energy/input pulse energy) as high as 2% have been observed.
Date: January 1, 1983
Creator: Quick, C.R. Jr.; Glownia, J.H.; Tiee, J.J. & Archuleta, F.L.
Partner: UNT Libraries Government Documents Department

[Homogeneous-hetergeneous combustion: Thermal and chemical coupling: Annual report]

Description: Fundamental studies of reactions at low pressures and of boundary layers give microscopic information on homogeneous-heterogeneous reactions. Ignition and extinction studies over simple geometries give basic bifurcation behavior with which to characterize multiple steady states and their stabilities and (hopefully) to identify the types of behavior which may occur. Oxidation of methane, propane, and ammonia were studied; other fuels will be studied. Catalytic monoliths will be used. Modeling will be performed.
Date: January 1, 1993
Partner: UNT Libraries Government Documents Department

Study of the comparative costs of five wet/dry cooling tower concepts

Description: A previous study undertaken to ascertain the economic incentives for further development of advanced dry/wet cooling towers showed that an advanced dry cooling concept using ammonia as an intermediate cooling fluid reduced the incremental cost of dry cooling by approximately 25 to 30%. This paper presents the projected costs of five alternative dry/wet concepts, one of which involves a similar use of ammonia. This study concludes that although absolute quantitative cost estimates for these cooling systems are uncertain, the relative cost studies indicate that wet/dry cooling systems using ammonia may be competitive with commercially available systems and that the deluge system which links dry and evaporative cooling in an ammonia system should be developed in order to provide a more accurate assessment of the system cost and reliability. (LCL)
Date: June 1, 1977
Creator: Allemann, R T; Feletti, D W; Johnson, B M; Parry, H L; Smith, G C; Tokarz, R D et al.
Partner: UNT Libraries Government Documents Department

Extended Hueckel $beta$ parameters applied to diatomic molecules

Description: From international symposium on atomic, molecular, solidstate theory, and quantum statistics; Sanibel lsland, Florida, USA (20 Jan 1974). Atom-atom separations predicted by extended Huckel theory using four BETA parameter approximations are compared for 15 diatomic molecules. Equilibrium separations R/ sub e/ determined from a new proposed formula for the BETA parameter are compared with R/sub e/'s resulting from the Mulliken-Wolfsberg-Helmholtz, Cusachs, and Jug BETA formulas. Results show that the new BETA formula is best in its prediction of R/sub e/'s. The new formula has the required property of yielding rotationally invariant results. (auth)
Date: January 1, 1974
Creator: Engelke, S.Z.
Partner: UNT Libraries Government Documents Department

Development of working fluid thermodynamic properties information for geothermal cycles. Phase I. Annual report, September 1, 1976-December 31, 1977

Description: During the first year (Phase I) of this research program, the following elements of research have been performed: (1) the collection and processing of data for pure components, (2) the evaluation of the generalized MBWR equation of state for halocarbon saturated thermodynamic properties, (3) the determination of pure component parameters for the MBWR equation for ten halocarbons, isobutane and, over a limited range, for ammonia and water, (4) the investigation of modifications of the MBWR equation for improved prediction of properties of hydrogen bonding and polar fluids. With the results of the present work, MBWR parameters have now been determined for twenty-seven pure fluids, making the use of the MBWR equation in geothermal cycle calculations feasible for most candidate working fluids. From this research, it has been concluded that the MBWR equation can be used to correlate the thermodynamic properties of many of the hydrocarbons and halocarbons which are presently potential candidate working fluids for geothermal binary cycles. However, for ammonia and water, the MBWR equation cannot accurately describe behavior in the complete range of fluid states. In anticipation of future needs to describe complex fluids (such as fluorinol-water mixtures) which have been proposed as working fluids, efforts have been initiated to develop an equation of state capable of describing the behavior of hydrogen bonding and polar as well as nonpolar fluids.
Date: January 1, 1977
Creator: Starling, K.E.; Sliepcevich, C.M.; Fish, L.W.; Goin, K.M.; Aboul-Fotouh, K.H.; Kumar, K.H. et al.
Partner: UNT Libraries Government Documents Department

Isotopic dependences of the dielectric strength of gases: new observations, classification, and possible origins

Description: In this paper we report: (1) the finding that the CH/sub 4//CD/sub 4/ nonuniform field behavior is polarity dependent (i.e., the V/sub s/ of CD/sub 4/ is lower than the V/sub s/ of CH/sub 4/ for negative polarity which is just the opposite of that observed for positive polarity); (2) discuss the origins of the observed isotope effects and predict new isotopic dependences of V/sub s/; and (3) report results on the V/sub s/ of H/sub 2/S and D/sub 2/S for negative polarity which confirm their predicted isotopic behavior.
Date: January 1, 1985
Creator: Christophorou, L.G.; Rodrigo, H.; Marode, E. & Bastien, F.
Partner: UNT Libraries Government Documents Department

Isotope dependence of the breakdown strength of gases

Description: It has been found that while the highly nonuniform direct current breakdown voltages, V/sub s/, of H/sub 2/ and NH/sub 3/ exceed, respectively, those of D/sub 2/ and ND/sub 3/, the V/sub s/ of CH/sub 4/ is substantially lower than that of CD/sub 4/. The former (direct) isotope effect may be attributed to the higher ionization coefficients for the deuterated species compared with the nondeuterated, and the latter (inverse) isotope effect may result from differences in the electron-impact-induced dissociation processes of the isotopic pairs of molecules.
Date: January 1, 1983
Creator: Christophorou, L.G.; Mathis, R.A. & James, D.R.
Partner: UNT Libraries Government Documents Department

Homogeneous production and removal of NO/sub x/ from combustion exhaust gases. Sixth quarterly technical summary report

Description: The final reaction rate constants for NH/sub 2/ + NO have been determined. A measurement of the fraction of product channels which form OH provides an approximate value of 0.2, but the uncertainties in the method used make this value a lower limit. Preliminary rate measurements for the reaction of OH + NH/sub 3/ ..-->.. NH/sub 2/ + H/sub 2/O agree well with previous room temperature experiments and appear to show a simple Arrhenius dependence with temperatures to 1200/sup 0/K. A chemical model of the NO/sub x/ chemistry has been developed and includes approximately 50 reactions at this time. Preliminary runs using this set have reproduced the gross temperature dependence of the thermal deNO/sub x/ process.
Date: March 1, 1980
Creator: Silver, J.A.; Gozewski, C.M. & Kolb, C.E.
Partner: UNT Libraries Government Documents Department

Discussion of enhancement in condensers

Description: A brief discussion of Professor Ralph L. Webb's paper, The Use of Enhanced Surface Geometries in Condensers, is given with emphasis on the importance of overall cost optimization in the application of heat transfer enhancement. A review of ORNL condensation experiments with enhanced surfaces is presented. The work has centered on optimizing the design variables associated with fluted surfaces on vertical tubes and comparing the tube performance with available enhanced tubes either for vertical or horizontal operation. Data with seven fluids including a hydrocarbon, fluorocarbons, and ammonia condensing on up to 30 different tubes have been obtained. The primary conclusion from this work is that fluted tubes can provide an enhancement in condensation coefficient of a factor of 6 over smooth vertical tubes and a factor of 2 over enhanced commercial tubes either operating vertically or horizontally. These data, together with field test data, have formed the basis for designing a prototype condenser for the 500 kWe East Mesa, California, direct-contact geothermal demonstration plant.
Date: January 1, 1980
Creator: Michel, J.W.
Partner: UNT Libraries Government Documents Department

Enhanced condensation heat transfer

Description: For the past four years, work has been in progress at ORNL to develop improved condensers for geothermal binary power cycles. The work has centered on optimizing the design variables associated with fluted surfaces on vertical tubes and comparing the tube performance with available enhanced tubes either for vertical or horizontal operation. Data with seven fluids including a hydrocarbon, fluorocarbons, and ammonia condensing on up to 30 different tubes have been obtained. Data for tubes of different effective lengths (1/2 to 4 ft) and inclination have also been obtained. The primary conclusion from this work is that the best fluted tubes can provide an enhancement in condensation coefficient by a factor of approximately 6 over smooth vertical tube performance and a factor of approximately 2 over the best enhanced commercial tubes either operating vertically or horizontally. These data, together with field test data have formed the basis for designing two prototype condensers, one for the 60 kWe Raft River, Idaho, pilot plant and one for the 500 kWe East Mesa, California, direct-contact demonstration plant.
Date: January 1, 1980
Creator: Michel, J.W. & Murphy, R.W.
Partner: UNT Libraries Government Documents Department