A Coupled Schrodinger Equation Approach to Modeling Predissociation in Sulfur Monoxide and Carbon Monoxide

Predissociation, a mechanism in which molecules are photodissociated by discrete bands of wavelengths, may help explain some anomalous oxygen and sulfur isotope ratios found in minerals formed at the birth of the solar system and on the early Earth. This thesis presents models of predissociation in two diatomics, sulfur monoxide (SO) and carbon monoxide (CO), using the Coupled Schrodinger Equation (CSE) method. In SO, two interactions were identified that could contribute to observed predissociation. In CO, a new model of predissociation in the B1Σ+-X1Σ+ system was developed

Doctor of Philosophy

dissertationOptical spectra of the supersonically cooled NiCCH radical have been recorded in the 530-650 nm region using the resonant two-photon ionization method, and five of the observed bands have been rotationally resolved. The rotationally resolved studies demonstrate that the ground state of NiCCH is of ð‘‹Ìƒ 2Î"5/2. Most of the observed bands are assigned to the ð´Ìƒ 2Î"5/2 ↠ð‘‹Ìƒ 2Î"5/2 electronic transition, which shows a progression in the Ni-C stretching mode, ν3. In addition, single excitations of the modes ν2 (C≡C stretch), ν4 (C≡C-H bend), and ν5 (Ni-C≡C bend) are observed, allowing these vibrational intervals to be determined for the ð´Ìƒ 2Î"5/2 state. Hot bands also allow the determinationof ν5 in the ground ð‘‹Ìƒ 2Î"5/2 state. The optical spectrum of diatomic OsSi has been investigated for the first time. Two electronic band systems have been identified along with a number of unclassified bands. Nine bands have been investigated at rotational resolution, allowing the ground state to be identified as X 3Σâˆ'+ , arising from the 1σ21Ï€42σ23σ21δ2 configuration. The 0 ground X 3Σâˆ'+state is characterized by re = 2.1207(27) Ã… and Î"G1/2" = 516.315(4) cm-1 0 for the most abundant isotopologue, 192Os28Si (38.63%). The A1 excited electronic state is characterized by T0 = 15 727.7(7) cm-1, ωe = 397.0(7) cm-1, and re = 2.236(16) Ã… for 192Os28Si. The B1 excited electronic state is characterized by T0 = 18 468.71 cm-1, Î"G1/2 = 324.1 cm-1, and re = 2.1987(20) Ã… for 192Os28Si. The abrupt onset of predissociation in the congested electronic spectra of jet- cooled VC, VN, and VS has been observed using resonant two-photon ionization spectroscopy. Using this method, bond dissociation energies of D0(VC) = 4.1086(25) eV, D0(VN) = 4.9968(20) eV, and D0(VS) = 4.5353(25) eV are obtained. These values are compared to previous measurements and to computational results. The precision of these bond dissociation energies makes them good candidates for testing computational chemistry methods, particularly those that employ density functional theory

First International Conference on Laboratory Research for Planetary Atmospheres

Proceedings of the First International Conference on Laboratory Research for Planetary Atmospheres are presented. The covered areas of research include: photon spectroscopy, chemical kinetics, thermodynamics, and charged particle interactions. This report contains the 12 invited papers, 27 contributed poster papers, and 5 plenary review papers presented at the conference. A list of attendees and a reprint of the Report of the Subgroup on Strategies for Planetary Atmospheres Exploration (SPASE) are provided in two appendices

Summaries of FY 1997 Research in the Chemical Sciences

The objective of this program is to expand, through support of basic research, knowledge of various areas of chemistry, physics and chemical engineering with a goal of contributing to new or improved processes for developing and using domestic energy resources in an efficient and environmentally sound manner. Each team of the Division of Chemical Sciences, Fundamental Interactions and Molecular Processes, is divided into programs that cover the various disciplines. Disciplinary areas where research is supported include atomic, molecular, and optical physics; physical, inorganic, and organic chemistry; chemical energy, chemical physics; photochemistry; radiation chemistry; analytical chemistry; separations science; heavy element chemistry; chemical engineering sciences; and advanced battery research. However, traditional disciplinary boundaries should not be considered barriers, and multi-disciplinary efforts are encouraged. In addition, the program supports several major scientific user facilities. The following summaries describe the programs

Proceedings of the NASA Laboratory Astrophysics Workshop

This report is a collection of papers presented at the 2006 NASA Workshop on Laboratory Astrophysics held in the University of Nevada, Las Vegas (UNLV) from February 14 to 16, 2006. This workshop brings together producers and users of laboratory astrophysics data so that they can understand each other's needs and limitations in the context of the needs for NASA's missions. The last NASA-sponsored workshop was held in 2002 at Ames Research Center. Recent related meetings include the Topical Session at the AAS meeting and the European workshop at Pillnitz, Germany, both of which were held in June 2005. The former showcased the importance of laboratory astrophysics to the community at large, while the European workshop highlighted a multi-laboratory approach to providing the needed data. The 2006 NASA Workshop on Laboratory Astrophysics, sponsored by the NASA Astrophysics Division, focused on the current status of the field and its relevance to NASA. This workshop attracted 105 participants and 82 papers of which 19 were invited. A White Paper identifying the key issues in laboratory astrophysics during the break-out sessions was prepared by the Scientific Organizing Committee, and has been forwarded to the Universe Working Group (UWG) at NASA Headquarters. This White Paper, which represented the collective inputs and opinions from experts and stakeholders in the field of astrophysics, should serve as the working document for the future development of NASA's R&A program in laboratory astrophysics

The study of comets, part 2

Flyby missions and systematic observations of comets are projected for studying comet nuclei and cometary dust tail structures

A Study of the Sulfur Isotopic Composition of Martian Meteorites

ABSTRACT Title of Document: A STUDY OF THE SULFUR ISOTOPIC COMPOSITION OF MARTIAN METEORITES Heather B. Franz, Ph.D., 2012 Directed By: Professor James Farquhar, Department of Geology and ESSIC Sulfur is an important tracer for geochemical processes because it possesses four stable isotopes and forms natural compounds in a range of oxidation states. This element has been shown to undergo mass-independent isotopic fractionation (S-MIF) during laboratory photochemical experiments, which may provide clues to processes that have occurred both in the solar nebula and in planetary atmospheres. The surface of Mars has been found to contain ubiquitous sulfate minerals, marking this planet as an ideal candidate for sulfur isotope study. The shergottites comprise the youngest group of martian meteorites and the most representative of mantle-derived igneous rocks. Extraction and isotopic measurement of sulfur from 30 shergottites yield the first estimate of the juvenile martian sulfur composition, which matches within uncertainties that of Cañon Diablo Troilite. Analysis of martian meteorites spanning a range of ages from the shergottites, as young as ~150 Ma, to the nakhlites, ~1.3 Ga, reveals the presence of sulfur characterized by S-MIF compositions. These findings are interpreted as evidence for cycling of sulfur between an atmospheric reservoir where photochemical processing of sulfur-bearing gases occurred and a surface reservoir in which photochemical products were ultimately deposited. Anomalous sulfur has been detected in both sulfate and sulfide minerals, implying assimilation of sulfur from the martian surface into magmas. Differences in the S-MIF compositions of the nakhlites and shergottites may preserve a record of complementary sulfur formed by a single process or may indicate the operation of multiple photochemical processes at different times or geographical locations. Identification of the photochemical mechanism responsible for producing the anomalous sulfur observed in martian meteorites is important for constraining the atmospheric composition at the time the S-MIF signals were generated. Results of laboratory experiments with pure SO2 gas suggest that self-shielding is insufficient to explain the anomalous sulfur isotopic composition. This implies that an optically thick SO2 column in the martian atmosphere may not have been required for production of the observed signal