| Spectroscopy and Dynamics of Transient and Energetic Species |
Apr-2009 |
14 pages |
| Authors:
Daniel M Neumark; CALIFORNIA UNIV BERKELEY DEPT OF CHEMISTRY
|
 | Free radicals, weakly bound van der Waals complexes, and metal and semiconductor clusters are characterized by photodetachment of the corresponding negative ions using slow electron velocity-map imaging (SEVI), a recently developed, high-resolution (2-3 cm-1) variant of negative ion photoelectron spectroscopy. The SEVI spectrum of a negative ion yields the electron affinity of the neutral, term values for excited states accessible via one-photon detachment, and accurate vibrational frequencies for the ground ... |
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| Predissociation and Quenching Dynamics of Electronically Excited Hydroxyl Radicals |
31 MAY 2004 |
8 pages |
| Authors:
Marsha I. Lester; PENNSYLVANIA UNIV PHILADELPHIA DEPT OFCHEMISTRY
|
| A series of studies has been conducted to examine the sources and sinks of electronically excited hydroxyl radicals via photon-assisted, unimolecular, and collision-induced processes. Significant progress has been made on three different fronts: (1) simulation of ultraviolet emission data from the Space Shuttle's thruster plume as originating from solar-induced and collision-induced electronic excitation of hydroxyl radicals; (2) detection of hydroxyl radicals in various vibrational levels of the ground electronic state ... |
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| Energy Transfer and Vibrationally Mediated Photodissociation in Liquids |
MAR 2004 |
11 pages |
| Authors:
F. F. Crim; WISCONSIN UNIV-MADISON DEPT OF CHEMISTRY
|
| Vibrational energy is a central aspect of chemical reactivity. Because a few vibrationally energized molecules are the ones that actually overcome the barriers to reaction to form products, the means by which molecules acquire and lose energy is at the heart of chemistry. Thus, vibrationally excited molecules are important in an enormous variety of environments, ranging from the conventional, such as solutions, to the exotic, such as plasmas. The authors ... |
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| Instrumentation for Frequency-Modulation Spectroscopy and Phase- Sensitive Detection of Photon Echoes for Hole Burning Optical Storage |
21 FEB 97 |
8 pages |
| Authors:
A. Gorokhovsky; I. Zeylikovich; R. R. Alfano; NEW YORK CITY COMMUNITY COLL BROOKLYN
|
| Instrumentation for frequency modulation spectroscopy studies of hole burning materials for optical storage, and a phase sensitive interferometric correlator for photon echoes detection has been purchased. Applications of phase sensitive correlator to phase stability characterization and heterodyne detection of optical signals were demonstrated using the equipment. |
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| Photofragmentation Spectroscopy and Photodissociation Dynamics of Polyatomic Molecules |
01 MAR 96 |
23 pages |
| Authors:
Brad R. Weiner; PUERTO RICO UNIV RIO PIEDRAS DEPT OF CHEMISTRY
|
| The detailed reaction dynamics of several gas phase polyatomic systems has been established in this research at the Department of Chemistry at the University of Puerto Rico. Real time dynamics of sulfur monoxide photoelimination reactions have been studied by laser induced fluorescence spectroscopy of the nascent SO fragment on the B(3) sigma(-) - X(3) sigma(-) transition in the region of 237-310 nm. The following group of molecules has been studied: ... |
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| Photodissociation Studies of Sulfur Oxides |
01 MAR 96 |
21 pages |
| Authors:
Brad R. Weiner; PUERTO RICO UNIV RIO PIEDRAS DEPT OF CHEMISTRY
|
| The detailed reaction dynamics of several gas phase polyatomic systems has been established in this research at the Department of Chemistry at the University of Puerto Rico. Real time dynamics of sulfur monoxide photoelimination reactions have been studied by laser induced fluorescence spectroscopy of the nascent SO fragment on the B(3)sigma (-) - X(3)sigma(-) transition in the region of 237-310 nm. The following group of molecules has been studied: Sulfur ... |
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| Collisional and Dissociative Processes Involving Molecular Free Radicals |
13 APR 95 |
23 pages |
| Authors:
Paul J. Dagdigian; Millard H. Alexander; JOHNS HOPKINS UNIV BALTIMORE MD
|
| A collaborative experimental and theoretical study of a number of elementary collisional processes involving small molecular free radicals of importance in combustion and in the decomposition of propellants has been carried out. These have involved chemical reactions and photodissociation, as well as nonreactive collision-induced rotational and electronic transitions. Information on non-bonding interactions involving free radicals was also obtained from analysis of the electronic spectrum of van der Waals complexes of ... |
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| State Resolved Differential Cross Sections for Reactions Important to the Decomposition of Energetic Materials |
01 SEP 94 |
10 pages |
| Authors:
Paul L. Houston; CORNELL UNIV ITHACA NY DEPT OF CHEMISTRY
|
| This final report describes the research whose goal was to develop a new technique for characterizing the velocity distributions of state-selected reaction products and to use this technique to study reactions of importance to the decomposition of energetic materials. In this technique, the three- dimensional product velocity distribution is determined by ionizing the appropriate species, waiting for a delay while the species separate along their trajectories, and then projecting the ... |
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| Excess Energy and Structural Dependence of the Rate of Energy Redistribution During the Photodissociation of Iodotoluenes |
27 MAY 94 |
39 pages |
| Authors:
John E. Freitas; Hyun J. Hwang; M. A. El-Sayed; CALIFORNIA UNIV LOS ANGELES
|
| The ortho (2-), meta (3-1), and para (4-) iodotolunes (C7H7I) photodissociated at 266 nm and 30.4 nm and studied with state-selective one- dimensional photo-fragment translational spectroscopy with state-selective velocity, and translational energy distributions are obtained for the ground I(2P3/2) and spin-orbit excited state I*(2P1/2) iodine atoms produced photodissociation. As has been observed in iodobenzene, the ground state I channel observed in each isomer of iodotoluene exhibits both a prompt alkyl ... |
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| Vacuum Ultraviolet Studies of Molecular Dynamics |
08 APR 94 |
7 pages |
| Authors:
Paul L. Houston; CORNELL UNIV ITHACA NY DEPT OF CHEMISTRY
|
| Tunable vacuum ultraviolet radiation generated by four-wave mixing will be used to probe collisional energy transfer and photodissociation. Collisional relaxation of the S((1)D) velocity distribution by rare gases has been measured to learn to what extent this simple process can be described by a hard-sphere, elastic interaction. E yielding V transfer was studied from S((1)D) to CO and N2, both by examining the Doppler profile of the relaxed atoms and ... |
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| Photofragmentation Spectroscopy and Photodissociation Dynamics of Polyatomic Molecules |
31 JAN 94 |
10 pages |
| Authors:
Brad R. Weiner; PUERTO RICO UNIV RIO PIEDRAS DEPT OF CHEMISTRY
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| Numerical Analysis of the Photo-Dissociation/Radical Oxidation of Formaldehyde by Ultraviolet Light in a Photolytic Reactor |
DEC 93 |
73 pages |
| Authors:
Robert O. Fetter; PENNSYLVANIA STATE UNIV UNIVERSITY PARK DEPT OF MECHANICAL ENGINEERING
|
| The release of volatile organic compounds (VOC's) into the atmosphere has come under fore by the Environmental Protection Agency (EPA) and state regulatory agencies in the past several years. These releases come from a wide variety of sources from gasoline filling stations to industrial and military operations. A new pollution control technology currently under development utilizes ultraviolet (UV) light to break down the volatile organic compounds (VOC's) contained in an ... |
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| The Photodissociation Dynamics of ICN at 304.67 nm by State-Selective One Dimensional Translational Fragmentation Spectroscopy |
09 NOV 93 |
24 pages |
| Authors:
Jennifer A. Griffiths; M. A. El-Sayed; CALIFORNIA UNIV LOS ANGELES DEPT OF CHEMISTRY AND BIOCHEMISTRY
|
| The photodissociation dynamics of ICN to CN + I 2P3/2) are investigated by state selective one dimensional photofragmentation translation spectroscopy at 304.67 nm. Translational energy release, laboratory anisotropy factors, and energy distributions are obtained from analysis of the velocity and spatial distributions of the photodissociated iodine atoms. Two velocity distributions peaks are deconvoluted which are found to be separated by 2000 / cm, which is the CN stretching vibration of ... |
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| Photodissociation Dynamics of Cluster Ions |
06 AUG 93 |
4 pages |
| Authors:
Michael T. Bowers; CALIFORNIA UNIV SANTA BARBARA DEPT OF CHEMISTRY
|
| Progress was made in the following two areas: (1) Photodissociation Dynamics of Small Cluster Ions (work was completed on one system and preliminary work done on several others) (2) Generation, Structure and Reactivity of Metallic and Semiconductor Clusters (two papers published and a large amount of preliminary work accomplished) |
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| Extracavity Frequency Doubling Study of a Pulsed Photodissociation Iodine Laser |
20 JUL 93 |
9 pages |
| Authors:
Yizhu Sun; Yuqi Jin; Tieji Gui; FOREIGN AEROSPACE SCIENCE AND TECHNOLOGY CENTER WRIGHT- PATTERSON AFB OH
|
| An extra-cavity lithium metaniobate (LiNbO3) crystal and the angle- phase matching technique were used for extracavity frequency doubling investigation of a pulsed photodissociation iodine laser. Frequency doubled laser beam of 0.657 micron wavelength and maximum energy conversion efficiency of 9.6% were obtained. ANNOTATION: Extracavity Frequency Doubling Study of a Pulsed Photodissociation Iodine Laser--Translation. |
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| Electronically Metastable Molecules of High Symmetry |
MAY 93 |
131 pages |
| Authors:
Hanspeter Helm; SRI INTERNATIONAL MENLO PARK CA
|
| This project is part of the search for a novel propellant based on molecules with excess internal energy for use in the combustion process. Spectroscopic properties of neutral molecules of triatomic hydrogen, tetraoxygen, superexcited oxygen, and hydronium were investigated using laser ionization, laser photodissociation, and charge neutralization techniques. The neutrals were prepared in a fast beam by electron transfer from stationary gas targets to mass selected ions. Excited state lifetimes ... |
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| Photodissociation Dynamics of Cluster Ions |
18 SEP 92 |
6 pages |
| Authors:
Michael T. Bowers; CALIFORNIA UNIV SANTA BARBARA DEPT OF CHEMISTRY
|
| There are two somewhat different objectives of this grant, unified by their common interest in clusters. We have made substantial progress both in photodissociation of atmospheric clusters (11 papers) and in the generation and reactivity of semiconductor and metallic clusters (7 papers). Of particular interest is our development of a new ion chromatography technique that allows determination of the shape of clusters, or other species, in the gas phase. ... |
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| Final Report for Grant Number AFOSR-89-0132, California University |
31 AUG 92 |
12 pages |
| Authors:
H. Metiu; CALIFORNIA UNIV SANTA BARBARA DEPT OF CHEMISTRY
|
| We have achieved two objectives: (1) we developed the theory of electron scattering by adsorbed molecule and used it to demonstrate that electron scattering is a good probe of the orientation of a chemisorbed molecule. (2) We developed the theory of photodissociation with ultrashort pulses, analyzed existing experiments and showed that coherence and interference play a central role in the dissociation process. By using numerical simulations we proposed and documented ... |
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| Photodissociation Dynamics of S4N4 at 222 and 248 nm |
Jul-1992 |
12 pages |
| Authors:
Andrew P Ongstad; Robert I Lawconnell; Thomas L Henshaw; FRANK J SEILER RESEARCH LAB UNITED STATES AIR FORCE ACADEMY CO
|
| Emission from several electronically excited states of NS is observed when the energetic molecule S4N4 is photolyzed with radiation from an excimer laser. Photolysis at 248 nm generates fluorescence from the B2 Pi sub 1/2,3/2, H2 Pi sub 1/2, G2 Sigma(-), and I2 Sigma (+) states of NS. NS(B2 Pi sub 1/2,3/2) and NS(C2 Sigma(+) fluorescence is observed when the photolysis wavelength is changed to 222 nm. The NS(H) and ... |
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| A Time-Resolved Two-Laser Probe of Cr(CO)6 Photodissociation Dynamics |
01 JUN 92 |
15 pages |
| Authors:
William R. Peifer; James F. Garvey; Robert DeLeon; STATE UNIV OF NEW YORK AT BUFFALO DEPT OF CHEMISTRY
|
| We have examined the photodissociation of jet-cooled Cr(CO)6 using a time-resolved, two-laser multiphoton dissociation (MPD) technique with fluorescence detection of the atomic photofragments. We have observed that the rate of appearance of Cr(CO)4 via 248-nm photolysis of Cr(CO)6 is slower if the Cr(CO)6 has first been cooled in a supersonic expansion. We suggest the difference in the observed rates is due to slower intersystem crossing in the transient Cr(CO)5 following ... |
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| Photodynamics within (CH3OH)nCr(CO)6 Heteroclusters: Observation of an Isotope Effect |
01 JUN 92 |
24 pages |
| Authors:
William R. Peifer; James F. Garvey; STATE UNIV OF NEW YORK AT BUFFALO DEPT OF CHEMISTRY
|
| We have recently examined the multiphoton dissociation and ionization dynamics of mixed van der Waals heteroclusters of Cr(CO)6 solvated by methanol, and have inferred from photoion fragmentation branching ratios that CD30D is more efficient than CH30H in relaxing excess internal energy of the nascent photoion via intracluster energy transfer. Multiphoton ionization is suggested to proceed via single photon photodissociation of the solvated Cr(CO)6, followed by two-photon ionization of the coordinatively ... |
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| A Time-resolved Two-laser Probe of Cr(CO)6 Photodissociation Dynamics |
01 JUN 92 |
16 pages |
| Authors:
William R. Peifer; James F. Garvey; Robert DeLeon; STATE UNIV OF NEW YORK AT BUFFALO DEPT OF CHEMISTRY
|
| We have examined the photodissociation of jet-cooled Cr(CO)6 using a time-resolved, two-laser multiphoton dissociation (MPD) technique with fluorescence detection of the atomic photofragments. We have observed that the rate of appearance of Cr(CO)4 via 248-nm photolysis of Cr(CO)6 is slower if the Cr(CO)6 has first been cooled in a supersonic expansion. We suggest the difference in the observed rates is due to slower intersystem crossing in the transient Cr(CO)5 following ... |
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| New Applications of Ionization and Fluorescence Techniques for Detecting and Characterization of Open-Shell Organometallics in the Gas Phase |
01 JUN 92 |
32 pages |
| Authors:
William R. Peifer; Robert L. DeLeon; James F. Garvey; STATE UNIV OF NEW YORK AT BUFFALO DEPT OF CHEMISTRY
|
| Recent advances are discussed in the development of electronic spectroscopic probes for the study of excited-state structure and photodissociation dynamics of gas-phase organometallics. Because of the short time - scale for intermolecular energy transfer within van der Waals clusters, the UV photodissociation dynamics of cluster-bound transition metal carbonyls differs considerably from the photodissociation dynamics of the naked species in the gas phase. It is therefore possible to employ multiphoton ionization ... |
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| A Mechanism for the Photodissociation of Carbon Monoxide at 193 nm |
JUN 92 |
33 pages |
| Authors:
Brad E. Forch; Clifton N. Merrow; ARMY BALLISTIC RESEARCH LAB ABERDEEN PROVING GROUND MD
|
| The photodissociation of carbon monoxide at 193 nm has been investigated using resonance enhanced multiphoton ionization detection of atomic oxygen and carbon fragments. The results of these experiments indicate a quadratic photodissociation process in CO at 12.8 eV. In addition, the nascent fine structure branching ratios of atomic oxygen 2p4 (3p 2,1,0) produced in the 193-nm photodissociation of CO are reported using both multiphoton laser-induced fluorescence and ionization detection. Analysis ... |
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| New Applications of Ionization and Fluorescence Techniques for Detecting and Characterization of Open-Shell Organometallics in the Gas Phase |
29 MAY 92 |
31 pages |
| Authors:
William R. Peifer; Robert L. DeLeon; James F. Garvey; STATE UNIV OF NEW YORK AT BUFFALO DEPT OF CHEMISTRY
|
| Recent advances are discussed in the development of electronic spectroscopic probes for the study of excited-state structure and photodissociation dynamics of gas-phase organometallics. Because of the short timescale for intermolecular energy transfer within van der Waals clusters, the UV photodissociation dynamics of cluster-bound transition metal carbonyls differs considerably from the photodissociation dynamics of the naked species in the gas phase. It is therefore possible to employ multiphoton ionization to produce ... |
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| Photodissociation of CF3I at 304 nm: Effects of Photon Energy and Curve Crossing on the Internal Excitation of CF3 |
27 MAY 92 |
38 pages |
| Authors:
Hyun J. Hwang; M. A. El-Sayed; CALIFORNIA UNIV LOS ANGELES DEPT OF CHEMISTRY AND BIOCHEMISTRY
|
| We present correlated measurements of the CF3 internal energy, the initial electronic excitation, and the final iodine state in the photodissociation of CF31 at 304 nm by using state-selective photofragment translational spectroscopy. The simultaneous determination of the three properties is achieved by measuring the translational energy distribution of the state-selected iodine fragment as a function of its recoil angle with respect to the electric vector of the photolysis laser. We ... |
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| Photodissociation of Azulene Under UV-Laser Irradiation At 325 nm |
18 MAY 92 |
9 pages |
| Authors:
S. Hassoon; D. L. Snavely; I. Oref; BOWLING GREEN STATE UNIV OH CENTER FOR PHOTOCHEMICAL SCIENCES
|
| UV-laser photodissociation of azulene at 325 nm is reported. The photodissociation reaction occurs by a two photon absorption process producing acetylene. The quantum yield for acetylene produced by irradiation of neat azulene and azulene/ argon mixtures is reported. The quantum yield of acetylene produced after irradiation of peat azulene at its normal vapor pressure is approximately (5.85+/-1.46)xlO-6. Photodissociation, Azulene. |
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| Dissolution Inhibition in Positive Novolak Resists |
MAY 92 |
8 pages |
| Authors:
Kenneth J. Wynne; POLYTECHNIC UNIV BROOKLYN NY
|
| The inhibition of novolak dissolution by various light-sensitive compounds is the basis of the most important imaging materials of the semiconductor device industry. A formidable amount of empirical information on these systems is available in the literature, yet in spite of this the molecular mechanism of the inhibition phenomenon is not understood and progress in this area is made largely by trial and error. The purpose of this part of ... |
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| Gas-Surface Interactions Near Dissociation Threshold |
26 MAR 92 |
12 pages |
| Authors:
Hanna Reisler; Curt Wittig; UNIVERSITY OF SOUTHERN CALIFORNIA LOS ANGELES DEPT OF CHEMISTRY
|
| The main thrust of our program was directed towards the study collision-induced dissociation (CID) of hyperthermal molecules on insulators (MgO), semiconductors (GaAs) and metals (Ag). Supersonic beams of nitroso compounds entered the UHV chamber with kinetic energies variable between 0.5 and 7 eV. NO products were detected state-selectively using two-frequency laser ionization. CTD yields were measured as a function of surface temperature and incident kinetic energy, and complete energy deposition ... |
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| Vacuum Ultraviolet Studies of Molecular Dynamics |
15 JAN 92 |
9 pages |
| Authors:
Paul L. Houston; CORNELL UNIV ITHACA NY DEPT OF CHEMISTRY
|
| This research grant used tunable vacuum ultraviolet radiation generated by four-wave mixing to probe collisional energy transfer, reactive encounters, and photodissociations. Translation-to-vibration/rotation energy transfer was examined in the H + CO system to learn how the extent of transfer depends on the collision energy and to determine the vibrational and rotational distribution of the product. The quenching of S(1D) by N2 was studied to learn the branching ratio for quenching ... |
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| The Pathways and Dynamics of Molecular Decomposition |
12 DEC 91 |
25 pages |
| Authors:
F. F. Crim; WISCONSIN UNIV-MADISON DEPT OF CHEMISTRY
|
| Molecular decompositions often control complex chemical reactions by producing a highly reactive fragment that determines the subsequent chemistry. Despite the importance of such processes, there is little detailed information available for testing theoretical models and guiding the analysis of practical systems. This report describes experiments that produce, characterize, and dissociate highly energized molecules in order to uncover the details of molecular decomposition. These experiments create highly energized molecules either by ... |
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| DURIP FTIR Studies of Solid State Reaction Dynamics |
24 JAN 90 |
35 pages |
| Authors:
Charles A. Wight; UTAH UNIV SALT LAKE CITY
|
| The origin of metastability in high symmetry molecules was studied by photoionization and photodissociation techniques. We have studied one- and two- photon ionization processes in the Triatomic hydrogen molecule and photodissociation of H3. We have also observed photoionization of Diatomic helium, Triatomic nitrogen, and D3O and performed a background study of metastable HD, H2, and He2. A new source for formation of H3 and H5 has been developed. Keywords: Photochlorination, ... |
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| Electronically Metastable Molecules of High Symmetry |
01 JAN 90 |
72 pages |
| Authors:
Hanspeter Helm; SRI INTERNATIONAL MENLO PARK CA
|
| In this research, we studied of the metastable electronic states of small molecules such as Tritium. Our goal was to obtain precise information on the origin of metastability in molecular systems of high symmetry and on structural, spectroscopic, and dynamic properties of such species. The research was performed in two experimental setups, both using fast neutral molecular beams that we form by charge transfer of an electron from a suitable ... |
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| NO2 Photodissociation Dynamics |
SEP 89 |
89 pages |
| Authors:
Tom G. Slanger; SRI INTERNATIONAL MENLO PARK CA
|
| The studies carried out under the present contract have all involved investigations of the photophysics and photochemistry of two nitrogen oxide molecules, NO and NO2. As well as being intrinsically interesting, these molecules are important from the point of view of atmospheric chemistry, and the NO2 molecule is a leading candidate as the emitting molecule that has been observed in the space shuttle glow. Major findings of these studies include ... |
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| Photodissociation of XeF2 (Xenon Difluoride) at 193 nm |
30 JUN 89 |
24 pages |
| Authors:
Jerry F. Bott; Raymond F. Heidner; John S. Holloway; John B. Koffend; AEROSPACE CORP EL SEGUNDO CA AEROPHYSICS LAB
|
| Interest in the spectroscopy of xenon difluoride (XeF2) has been stimulated by the xenon fluoride (XeF) laser, which operates on the B-X transitions at 351 and 353 nm and the C-A transitions at 483 nm. The vacuum ultraviolet (VUV) photolysis of XeF2 can be used either to obtain laser action on these transitions or to produce the several electronic states of XeF for kinetic studies. The XeF2 photodissociation laser has ... |
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| State to State Collision Induced Dissociation and Gas/Surface Interactions |
01 MAR 89 |
19 pages |
| Authors:
Curt Wittig; Hanna Reisler; UNIVERSITY OF SOUTHERN CALIFORNIA LOS ANGELES DEPT OF CHEMISTRY
|
| The main thrust of our contract was directed towards the study of gas surface interactions and the complementary collisionless photodissociation processes. Our initial experiments were concerned with NO scattering from an insulating MgO(100) single crystal surfaces, and the preliminary results have been published in Chem. Phys. Lett. We are now conducting experiments in which molecules with high kinetic energy are dissociated and/or ionized upon impact on surfaces. Our preliminary results, ... |
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| Molecular Dynamics in the Vacuum Ultraviolet |
30 JAN 89 |
8 pages |
| Authors:
Paul L. Houston; CORNELL UNIV ITHACA NY DEPT OF CHEMISTRY
|
| The photodissociation of OCS at 222-nm has been examined by using tunable vacuum ultraviolet laser radiation to probe the Carbon monoxide and Sulfur products. Products of both the monomer and polymer dissociation have been identified and characterized, with particular emphasis on vector correlations. The vacuum ultraviolet radiation used to probe the CO and S products is generated by four-wave mixing in magnesium vapor. The photodissociation of OCS at 157 nm ... |
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| Laser Studies of Gas Phase Radical Reactions |
JAN 89 |
91 pages |
| Authors:
G. Hancock; OXFORD UNIV (ENGLAND) PHYSICAL CHEMISTRY LAB
|
| A series of measurements on free radicals produced by chemical reaction and photodissociation has been made, using laser methods for formation and in some cases, detection. Highly exothermic reactions between oxygen atoms and both CF2 and CHF radicals have been studied by time resolved Fourier transform infrared emission spectroscopy, yielding information on the reaction pathway, emitting products, kinetics of formation and quenching, and the nascent vibrational distributions. Emitting species hydrogen ... |
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| Collaborative Experimental and Theoretical Study of the Photodissociation and Reactions of the Azide Radical |
22 FEB 88 |
6 pages |
| Authors:
Paul J. Dagdigian; Millard H. Alexander; JOHNS HOPKINS UNIV BALTIMORE MD
|
| A theoretical investigation of the energetics of the dissociation of ground state hydrazoic acid HN3 and the azide radical N3 has been carried out through complete active space SCF and multi-reference configuration interaction calculations with large basis sets. Of particular interest was (a) The determination of the bond dissociation energies of HN3 and N3, (b) The location of the geometry and topology of the transition state for spin-forbidden decomposition and ... |
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| Photochemistry at Structured Surfaces: A Classical Electromagnetic Approach |
FEB 88 |
|
| Authors:
Daniel A. Jelski; P. T. Leung; Thomas F. George; STATE UNIV OF NEW YORK AT BUFFALO DEPT OF CHEMISTRY
|
 | This review article discusses several important aspects of photochemistry at structured metallic surfaces. The electromagnetic field above the surface is calculated using the Rayleigh expansion. Conditions under which this expansion is valid and simplifying approximations which make it easier to use are discussed in detail. This formalism is then applied to three different but related phenomena. First, the photodissociation rate of a molecule above a surface is calculated for laser ... |
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| Kinetic, Thermochemical, and Photodissociation Studies of Sulfur- Containing Atmospheric Ions |
29 AUG 87 |
45 pages |
| Authors:
Timothy F. Thomas; MISSOURI UNIV-KANSAS CITY DEPT OF CHEMISTRY
|
| The rate constants of 25 reactions involving sulfur-containing ions or molecules at 298 K have been measured. Based on the results obtained a new condition for efficient charge transfer is proposed and reactions leading to formation of stratospheric ions with m/z=60, 78, and 98 are identified. The first complete mass spectra of sulfuric acid vapor have been obtained, its ionization potential has been found to be 12.40 + or - ... |
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| Infrared Multiphoton Dissociation of the Nitrobenzene Cation |
20 SEP 86 |
|
| Authors:
M. Moini; J. R. Eyler; FLORIDA UNIV GAINESVILLE DEPT OF CHEMISTRY
|
| Infrared multiphoton dissociation (IRMPD) of nitrobenzene cations has been shown to proceed via three pathways of ca. 1-2 eV activation energy to produce C6H5, C5H5, and NO ions. Observation of these three fragment ions and not C6H5, which has approximately the same appearance energy, suggests that they are produced from high vibrational levels of the ground electronic state of the cation, while the C6H5 either has a higher appearance energy ... |
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| Photodissociation of Gaseous Ions Formed by Laser Desorption |
20 SEP 86 |
|
| Authors:
Clifford H. Watson; Gokhan Baykut; John R. Eyler; FLORIDA UNIV GAINESVILLE DEPT OF CHEMISTRY
|
| Both pulsed and gated continuous wave carbon dioxide lasers have been employed to desorb ions and then to photodissociate them in a Fourier transform ion cyclotron resonance mass spectrometer. Pulsed CO2 laser irradation was most successful in laser desorption experiments, while a gated continuous wave laser was used for a majority of the successful infrared multiphoton dissociation studies. Fragmentation of ions with m/z values in the range 400-1300 was induced ... |
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| Investigation of a Cesium Iodide Photodissociation Laser as a Source at 455.5 nm |
SEP 86 |
|
| Authors:
Frank Hanson; NAVAL OCEAN SYSTEMS CENTER SAN DIEGO CA
|
| This investigation is concerned with both the feasibility of generating a spectrally narrow laser source at 455.5-nm by photodissociation of cesium iodide, and the possibility of amplifying this output in a parametric process using a suitable nonlinear material. Experiments using a 193-nm ArF laser as a photodissociation source are described. Only very weak output at 455. 5-nm was observed, perhaps due to competition from other lines which depleted the 7P3/2 ... |
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| The Gordon Research Conference on Multiphoton Processes Held in New London, New Hampshire on 9-13 June 1986 |
13 JUN 86 |
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| Authors:
Patricia M. Dehmer; Philip M. Johnson; ARGONNE NATIONAL LAB IL ENVIRONMENTAL RESEARCH DIV
|
| The program coverd all aspects of Multiphoton Processes in atoms and molecules. There were sessions devoted to multiphoton ionization of atoms, multiphoton ionization in intense laser fields, multiphoton ionization and dissociation processes in small molecules, multiphoton dissociation processes in larger molecules (including picosecond processes), and general interest sessions. The complete Conference program is appended. |
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| High-Resolution Spectroscopy and Dynamics of Multiphoton Processes in Atoms and Molecules |
02 JUN 86 |
|
| Authors:
Patricia M. Dehmer; Joseph L. Dehmer; ARGONNE NATIONAL LAB IL
|
| This report summarizes research on resonantly enhanced multiphoton absorption, dissociation, and ionization processes in atoms and molecules. Multiphoton processes are studied using from one to three independently tunable visible and/or UV laser beams in order to establish both the underlying physics and the high degree of selectivity of multiphoton processes. Measurements are made to probe both the formation of excited molecular states and the subsequent behavior of excited states either ... |
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| Photodissociation of Molecules at Structured Metallic Surfaces |
JUN 86 |
|
| Authors:
P. T. Leung; Thomas F. George; STATE UNIV OF NEW YORK AT BUFFALO DEPT OF CHEMISTRY
|
| Direct photodissociation of molecules at structured metallic surfaces is considered, where the concepts of optimal and critical distances are introduced into the description of this phenomenon. Numerical results for the distortion of the line shape and the enhancement ratio are obtained for a shallow sinusoidal grating. |
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| Photolysis of BrCN between 193 and 266 nm |
30 JAN 86 |
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| Authors:
Jeffrey A. Russell; Ian A. McLaren; William M. Jackson; Joshua B. Halpern; HOWARD UNIV WASHINGTON D C
|
| Measurement of the quantum state distributions of CN (X2 Sigma + State) fragments from the photolysis of BrCN at several wavelengths between 193 and 266 nm shows that there is very little excitation of v > 1 levels in the nascent distributions for photolysis below 230 nm. Above this wavelength, significant population is found in excited vibrational states. Scaling of the distribtuions indicates that the potential energy surface on which ... |
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| The Infrared Multiphoton Dissociation of Three Nitrolkanes |
24 JAN 86 |
|
| Authors:
A. M. Wodtke; E. J. Hintsa; Y. T. Lee; CALIFORNIA UNIV BERKELEY DEPT OF CHEMISTRY
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| Infrared multiphoton dissociation in a molecular beam has been studied in order to elucidate the collision free, 'thermal' chemistry and dynamics of nitromethane, nitroethane and 2-nitropropane. The isomerization of CH3NO2 to CH3ONO was observed by detecting the CH3O and NO products from the dissociation of the very internally hot, isomerized nitromethane. A novel application of RRKM theory was used to estimate the barrier height to isomerization at 55.5 kcal/mol. The ... |
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| Infrared Multiphoton and Collision Induced Dissociation Studies of Some Gaseous Alkylamine Ions |
01 JAN 86 |
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| Authors:
C. H. Watson; G. Baykut; M. A. Battiste; J. R. Eyler; FLORIDA UNIV GAINESVILLE DEPT OF CHEMISTRY
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| Collision induced dissociation and infrared multiphoton dissociation of ions formed in di- and triethylamine, di- and tri-n-propylamine, and diisopropylamine were investigated by Fourier transform ion cyclotron resonance mass spectrometry. Molecular ions of all amines except di-n-propylamine produced similar fragment ions when subjected to either dissociation technique. The initial fragmentation involved C(alpha)-C(beta) bond cleavage, loss of an alkyl radical, and formation of an immonium ion. Subsequent fragmentations of the immonium ions ... |
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