Inner-shell electron spectroscopy and chemical properties of atoms and small molecules (open access)

Inner-shell electron spectroscopy and chemical properties of atoms and small molecules

The program has been concerned with gas-phase carbon 1s photoelectron spectroscopy of a number of molecules of potential chemical interest. The primary goals have been to determine carbon 1s ionization energies with a view of relating these to other chemical properties such as electronegativity, acidity, basicity, and reactivity, in order to provide a better understanding of these fundamental properties. The role of electron-donating (methyl) and electron-withdrawing (fluoro) substituents on the carbon 1s ionization energies of substituted benzenes has been studied., and these results have been related to measurements of the reactivities of the same molecule as well as to their affinities for protons (basicity). Opportunities for investigation in unplanned areas have arisen, and the program has been modified to take advantage of these. One has been the realization that, under certain circumstances, inner-shell ionization energies may depend on the molecular conformation. Several examples of this phenomenon have been investigated and it has been shown that this technique provides a tool for the measurement of the energy differences between different conformers of the same substance. The other has been the demonstration that photoelectron recoil can lead to the excitation of vibrational modes that are forbidden in the normal view of photoemission …
Date: January 21, 2009
Creator: Thomas, T. Darrah
Object Type: Report
System: The UNT Digital Library
TECHNOLOGY NEEDS AND STATUS ON CLOSURE OF DOE RADIOACTIVE WASTE TANK ANCILLARY SYSTEMS (open access)

TECHNOLOGY NEEDS AND STATUS ON CLOSURE OF DOE RADIOACTIVE WASTE TANK ANCILLARY SYSTEMS

This paper summarizes the current state of art of sampling, characterizing, retrieving, transferring and treating the incidental waste and stabilizing the void space in tank ancillary systems and the needs involved with closure of these systems. The overall effort for closing tank and ancillary systems is very large and is in the initial stages of being addressed in a systematic manner. It was recognized in doing this effort, that gaps in both technology and material application for characterization and removal of residual waste and closure of ancillary systems would be identified. Great efficiencies are to be gained by defining the technology need areas early in the closure process and providing recommendations for technical programs to improve the closure strategies. Therefore, this paper will not only summarize the state of closure of ancillary systems but also provide recommendations to address the technology gaps identified in this assessment.
Date: January 21, 2009
Creator: Burns, H; Sharon Marra, S & Christine Langton, C
Object Type: Article
System: The UNT Digital Library
The Mercury Laser Advances Laser Technology for Power Generation (open access)

The Mercury Laser Advances Laser Technology for Power Generation

The National Ignition Facility (NIF) at Lawrence Livermore Laboratory is on target to demonstrate 'breakeven' - creating as much fusion-energy output as laser-energy input. NIF will compress a tiny sphere of hydrogen isotopes with 1.8 MJ of laser light in a 20-ns pulse, packing the isotopes so tightly that they fuse together, producing helium nuclei and releasing energy in the form of energetic particles. The achievement of breakeven will culminate an enormous effort by thousands of scientists and engineers, not only at Livermore but around the world, during the past several decades. But what about the day after NIF achieves breakeven? NIF is a world-class engineering research facility, but if laser fusion is ever to generate power for civilian consumption, the laser will have to deliver pulses nearly 100,000 times faster than NIF - a rate of perhaps 10 shots per second as opposed to NIF's several shots a day. The Mercury laser (named after the Roman messenger god) is intended to lead the way to a 10-shots-per-second, electrically-efficient, driver laser for commercial laser fusion. While the Mercury laser will generate only a small fraction of the peak power of NIF (1/30,000), Mercury operates at higher average power. The design …
Date: January 21, 2009
Creator: Ebbers, C A; Caird, J & Moses, E
Object Type: Article
System: The UNT Digital Library
Comparison of Complementary Reactions in the Production of Mt (open access)

Comparison of Complementary Reactions in the Production of Mt

The new reaction 208Pb(59Co,n)266Mt was studied using the Berkeley Gas-filled Separator at the Lawrence Berkeley National Laboratory 88-Inch Cyclotron. A cross section of 7.7+5.2-3.3 pb was measured at a compound nucleus excitation energy of 14.9 MeV. The measured decay properties of 266Mt and its daughters correspond well with existing data. We compare this experimental result to transactinide compound nucleus formation model predictions, and the previously studied 209Bi(58Fe,n)266Mt reaction.
Date: January 21, 2009
Creator: Nelson, Sarah; Gregorich, Kenneth; Dragojevic, Irena; Ellison, Paul; Garcia, Mitch Andre; Gates, Jacklyn et al.
Object Type: Article
System: The UNT Digital Library
Photodissociation of the Propargyl (C3D3) Radicals at 248 nm and 193 nm (open access)

Photodissociation of the Propargyl (C3D3) Radicals at 248 nm and 193 nm

The photodissociation of perdeuterated propargyl (D{sub 2}CCCD) and propynyl (D{sub 3}CCC) radicals was investigated using fast beam photofragment translational spectroscopy. Radicals were produced from their respective anions by photodetachment at 540 nm and 450 nm (below and above the electron affinity of propynyl). The radicals were then photodissociated by 248 nm or 193 nm light. The recoiling photofragments were detected in coincidence with a time- and position-sensitive detector. Three channels were observed: D{sub 2} loss, CD + C{sub 2}D{sub 2}, and CD{sub 3} + C{sub 2}. Obervation of the D loss channel was incompatible with this experiment and was not attempted. Our translational energy distributions for D{sub 2} loss peaked at nonzero translational energy, consistent with ground state dissociation over small (< 1 eV) exit barriers with respect to separated products. Translational energy distributions for the two heavy channels peaked near zero kinetic energy, indicating dissociation on the ground state in the absence of exit barriers.
Date: January 21, 2009
Creator: Neumark, Daniel M.; Crider, Paul E.; Castiglioni, Luca & Kautzman, Kathryn E.
Object Type: Article
System: The UNT Digital Library