| A Novel Photochemical Interfacial Approach to the Degradation of Hazardous Materials |
01 JUL 97 |
5 pages |
| Authors:
Nicholas J. Turro; COLUMBIA UNIV NEW YORK DEPT OF CHEMISTRY
|
 | Two studies are described. The first involved the use of time resolved electron spin resonance as a mechanistic and spectroscopic probe of two fundamental reactions of ketone photochemistry: intermolecular hydrogen abstraction by the triplet state of benzophenone and triplet state alpha- cleavage of 1,3-diphenylacetone (dibenzyl ketone). It was found that the forces restricting the ground state conformations of these ketones also restrict the triplet state conformations. The second study used ... |
|
| A Supramolecular Approach to the Mechanisms of Photomineralization of Hazardous Materials |
04 NOV 96 |
5 pages |
| Authors:
Nicholas J. Turro; COLUMBIA UNIV NEW YORK DEPT OF CHEMISTRY
|
| Supramolecular photochemistry provides experimental tools and mechanistic concepts pertinent to the examination of the fate of Air Force chemicals and how they may be photochemically transformed into environmentally benign substances. This benefication process of converting AF chemicals to environmentally benign materials is termed mineralization. A biomimetic strategy is adopted for which the laboratory model of benefication is based on processes occurring in nature. This biomimetic model provided us with the ... |
|
| A Supramolecular Approach to the Mechanisims of Photomineralization of Hazardous Materials |
NOV 96 |
5 pages |
| Authors:
Nicholas J. Turro; COLUMBIA UNIV NEW YORK DEPT OF CHEMISTRY
|
| Supramolecular photochemistry provides experimental tools and mechanistic concepts pertinent to the examination of the fate of Air Force chemicals and how they may be photochemically transformed into environmentally benign substances. This benefication process of converting AF chemicals to environmentally benign materials is termed mineralization. A 'biomimetic' strategy is adopted for which the laboratory model of benefication is based on processes occurring in nature. This biomimetic model provided us with the ... |
|
| Investigation of Chemical Fate of Hazardous Aerospace Materials in Environment: A Supramolecular Photochemical Investigation of Materials Absorbed on Metal Oxides and Porous Solids |
19 APR 96 |
5 pages |
| Authors:
Nicholas J. Turro; COLUMBIA UNIV NEW YORK DEPT OF CHEMISTRY
|
| Supramolecular photochemistry provides experimental tools and mechanistic concepts pertinent to the examination of the fate of Air Force chemicals and how they may be photochemically transformed into environmentally benign substances. This benefication process of converting AF chemicals to environmentally benign materials is termed mineralization. A 'biomemetic' strategy is adopted for which the laboratory model of benefication is based on processes occurring in nature. This biomimetic model provided us with the ... |
|
| STABILIZATION AND CONTROL OF HIGH ENERGY INTERMEDIATES THROUGH ADSORPTION ON RESTRICTED SPACES |
16 SEP 94 |
12 pages |
| Authors:
Nicholas J. Turro; COLUMBIA UNIV NEW YORK DEPT OF CHEMISTRY
|
| The research supported by this AFOSR grant has involved a multi- technique (NMR, ESR, laser flash photolysis, single photon counting, photoluminescence, tailor-made syntheses, computer simulation) approach to address problems concerning the structure and dynamics of transient high energy intermediates. These techniques have been employed to investigate the behavior of these intermediates when the latter are confined to the interfacial regions of restricted reaction spaces such as micelles, zeolites, cyclodextrins, water ... |
|
| Applications of Second Harmonic and Sum Frequency Generation to Graphite and Silica Type Interfaces |
AUG 1994 |
17 pages |
| Authors:
E. Borguet; A. N. Tarmovsky; X. Wang; D. Zhang; K. B. Eisenthal; COLUMBIA UNIV NEW YORK DEPT OF CHEMISTRY
|
| Second Harmonic (SHG) and Sum-Frequency Generation (SFG) have enabled the investigation of the physical and chemical properties of aqueous interfaces, yielding new information and considerable insight into the structure and dynamics at a molecular level. Novel behavior has been observed and valuable new methodologies have been developed. IR-Visible SFG has enabled the behavior of distinct chromophores within a molecular species at an aqueous interface to be monitored for the first ... |
|
| ASSERT-92: A Novel Photochemical and Interfacial Approach to the Degradation of Hazardous Materials |
14 JUN 94 |
5 pages |
| Authors:
Nicholas J. Turro; COLUMBIA UNIV NEW YORK DEPT OF CHEMISTRY
|
| An intriguing proposal is that the intramolecular hydrogen bond of 3Bz 'locks' the species into a conformation unfavorable to reaction. We have begun to study this reaction with many of the techniques used previously to study 3BP and 3DBK. Recently, theorists have studied the use of coherent laser excitation to select pathways for chemical reactions -- to use light to shape the wavefunctions of the molecules' excited states. With this ... |
|
| Scanning Tunneling Microscopy Investigations of Metal Dichalcogenide Materials |
25 OCT 93 |
44 pages |
| Authors:
Charles M. Lieber; COLUMBIA UNIV NEW YORK DEPT OF CHEMISTRY
|
| Scanning tunneling microscopy (STM) and atomic force microscopy (AFM) have been used to characterize the atomic level structure of electronic properties, reactivity and wear of metal dichalcogenide materials that are or have potential as solid state lubricants. Single crystals Of MoS2, Ni(x)Mo(l-x) S2, MoS(2-x)Se(x) and MoS(2-x)Te(x) have been prepared to determine how chemical modifications affect the local structure and electronic properties of this lubricant. STM images of Ni-doped MoS2 show ... |
|
| The Synthesis of Artificial Enzymes |
93 |
12 pages |
| Authors:
Ronald Breslow; COLUMBIA UNIV NEW YORK DEPT OF CHEMISTRY
|
| A previously reported paper with Chung (1) showed that there can be such a thing as too much rigidity in an enzyme model, and that some freedom of movement must be maintained even though in general flexibility is deleterious in catalysis. The point here is that hydrolysis of an ester by an enzyme such as chymotrypsin requires an interesting geometric change: the attacking hydroxyl group of the enzyme must approach ... |
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| TEMPO Radicals as EPR Probes to Monitor the Adsorption of Different Species into X Zeolite |
1993 |
14 pages |
| Authors:
M. F. Ottaviani; Miguel Garcia-Garibay; Nicholas J. Turro; COLUMBIA UNIV NEW YORK DEPT OF CHEMISTRY
|
| A computer-aided analysis of the electron paramagnetic resonance (EPR) spectra of TEMPO radicals adsorbed in X zeolites is performed under various experimental conditions, both in the absence and in the presence of various species. In dehydrated NaX zeolites the radical gives rise to two superimposed signals corresponding to species characterized by different mobility and polarity and by a different temperature dependence. Controlled addition of water leads to an increase of ... |
|
| Determination of Hyperfine Splittings of Biradical Termini by Combining Biradical Trapping and Time-Resolved ESR Techniques |
1993 |
8 pages |
| Authors:
Igor V. Koptyug; Naresh Ghatlia; Nicholas J. Turro; William S. Jenks; COLUMBIA UNIV NEW YORK DEPT OF CHEMISTRY
|
| ESR detection of spin-polarized short-lived biradicals has been shown to be a valuable tool in studying the mechanisms of photochemical reactions and in the investigation of the properties of biradicals. However, some important spectroscopic features of these species are not readily available because of certain peculiarities of biradical ESR spectra. This difficulty can be overcome through the conservation of spin polarization by the controlled scavenging of a biradical into a ... |
|
| Singlet State Photochemistry of Dibenzyl Ketone and its o-Tolyl Derivatives |
1993 |
14 pages |
| Authors:
Taehee Noh; Eugene Step; Nicholas J. Turro; COLUMBIA UNIV NEW YORK DEPT OF CHEMISTRY
|
| The singlet state contribution of alpha cleavage in the photochemistry of dibenzyl ketone (DBK) and o-tolylmethylbenzyl ketone (TBK) was investigated. The fitting of a master Stern-Volmer equation for the simultaneous quenching of the S1 and T1 states of DBK and TBK leads to the conclusion that in both ketones alpha cleavage occurs in the singlet state, but to a lesser (20- 30%) extent than in the triplet. Comparison of the ... |
|
| Picosecond Studies of Chemical Intermediates |
MAY 91 |
59 pages |
| Authors:
K. B. Eisenthal; COLUMBIA UNIV NEW YORK DEPT OF CHEMISTRY
|
| Surface second harmonic generation (SSHG) has been used to study the chemical and physical properties of liquid interfaces. Information about the thermodynamics of neat liquid surfaces has been found by observing the SH signal as a function of temperature. Extensive studies using monolayers at the air/ water interface have been undertaken. Studies of acid/base equilibrium and monolayer phase transitions have been performed. The gas-liquid coexistence region and an orientational phase ... |
|
| Polymer Syntheses and Mechanisms of Polymerization |
18 MAR 91 |
6 pages |
| Authors:
Thomas J. Katz; COLUMBIA UNIV NEW YORK DEPT OF CHEMISTRY
|
| The major outcome of the research was the discovery that acetylenes induce metal-derivatives to initiate methatheses of olefins. This discovery provides a simple way to synthesize a variety of polymers from cyclic olefins. Research to demonstrate the mechanism by which acetylenes induce methatheses showed that polyacetylenes appear as a block at the start of polyalkenamer chains. The initiation of the olefin methathesis quenches the acetylene polymerization. The size of the ... |
|
| Photoluminescence Probes of Aqueous Solutions of Micelles and Related Colloidal Systems |
15 MAR 89 |
5 pages |
| Authors:
Nicholas J. Turro; COLUMBIA UNIV NEW YORK DEPT OF CHEMISTRY
|
| The goals of this research have been (1) to generate knowledge concerning the nature and dynamics of adsorption of surfactants in aqueous solutions and (2) to generate innovative and fundamental paradigms that will allow an understanding of the adsorption at the molecular level. The spectroscopic probe technique has been employed to investigate aqueous solutions of micelles, polyelectrolytes, cyclodextrins and DNA. In addition, the interactions of aqueous suspension of surfactants and ... |
|
| Picosecond Laser Studies of Excited State Processes |
30 SEP 87 |
|
| Authors:
Kenneth B. Eisenthal; COLUMBIA UNIV NEW YORK DEPT OF CHEMISTRY
|
 | The completed research was directed at fundamental investigations of ultra fast chemical reactions, the generation and decay of reactive chemical intermediates, as well as the role of the solvent and molecular motions on chemical dynamics. The construction of an amplified CPM laser enabled the opportunity to prove chemical events occuring in the femtosecond time domain. The effects of molecular geometry, solvent and solute steric effects, on the chemical dynamics was ... |
|
| Picosecond Laser Studies of Excited State Processes |
87 |
|
| Authors:
Kenneth B. Eisenthal; COLUMBIA UNIV NEW YORK DEPT OF CHEMISTRY
|
| The completed research was directed at fundamental investigations of ultra fast chemical reactions, the generation and decay of reactive chemical intermediates, as well as the role of the solvent and molecular motions on chemical dynamics. The construction of an amplified CPM laser enabled the opportunity to probe chemical events occuring in the femtosecond time domain. The effects of molecular geometry, solvent and solute steric effects, on the chemical dynamics was ... |
|
| Luminescence Probes for the Investigation of the Structure and Dynamics of Aqueous Solutions of Micelles and Related Systems |
09 APR 86 |
|
| Authors:
Nicholas J. Turro; COLUMBIA UNIV NEW YORK DEPT OF CHEMISTRY
|
| Among the important results discovered by this research are 1) The ability of luminescence probes to determine the nature and extent of binding of substrates to cyclodextrins; 2) The use of fluorescence probes to determine critical micelle concentrations, to reveal surfactant/polymer interactions; 3) The utility of fluorescence probes for investigation of non-ionic surfactants and of ionic/non-ionic surfactant interactions; 4) The ability of fluorescence probes to investigate the interactions of metals ... |
|
| Modification of Chemical Reactivity via Inclusion Complex Formation: Photochemistry of Dibenzyl Ketones and Benzyl Phenylacetates |
86 |
|
| Authors:
Bantu N. Rao; Nicholas J. Turro; Vaidhyanathan Ramamurthy; COLUMBIA UNIV NEW YORK DEPT OF CHEMISTRY
|
| In the context of employing inclusion complexes as a medium for organic photochemical reactions, we have investigated the photochemical behavior of dibenzyl ketones and benzyl phenylacetates using deoxycholic acid (DCA), Dianin's compound, and cyclodextrin (CD) as hosts in the solid state. Results on cage effect suggest that the translational motion of the benzyl radical pairs is restricted in all three media and totally in Dianin's compound. Products resulting from rearrangement ... |
|
| Polarity Dependent Barriers and the Photoisomerization Dynamics of Polar Molecules in Solution |
86 |
|
| Authors:
J. M. Hicks; M. T. Vandersall; E. V. Sitzmann; K. B. Eisenthal; COLUMBIA UNIV NEW YORK DEPT OF CHEMISTRY
|
| To investigate the effects of the solvent on the photoisomerization kinetics of DMABN, we have carried out studies in a series of linear alcohols, alcohol/alkane mixtures, linear nitriles and nitrile/alkane mixtures (part of the data has been reported). |
|
| Catalytic Hydrolysis of a Phosphate Triester by Tetracoordinated Zinc Complexes. |
04 OCT 1985 |
|
| Authors:
Ronald Breslow; Samuel H. Gellman; Russell Petter; COLUMBIA UNIV NEW YORK DEPT OF CHEMISTRY
|
| A zinc complex of a tetraaza macrocycle catalyzes the hydrolysis of diphenyl p-nitrophenyl phosphate in aqueous acetonitrile. The principal products derive from loss of p-nitrophenol, but some alternative hydrolysis with loss of phenol is also observed. Kinetic studies show that the catalytic zinc species is a zinc hydroxide complex with a PK A of 8.7 (or its kinetic equivalent). The greater kinetic effectiveness of this weak base than of free ... |
|
| A Procedure Identifying a Polyacetylene Initiator of Olefin Metathesis. The Reactivities of Metal-Carbenes Toward Alkenes and Alkynes |
10 JUL 85 |
|
| Authors:
C. C. Han; T. J. Katz; COLUMBIA UNIV NEW YORK DEPT OF CHEMISTRY
|
| fWhen phenylacetylene plus tungsten hexachloride initiate the metathesis of cyclopentene, poly(phenylacetylene) is found attached to the resulting polypentenamer chains. The average amount of this poly(phenylacetylene) does not vary as the growth of the polypentenamer chains is checked by added diphenylacetylene, showing it to be present as a block at their start. The implication is that the metathesis is initiated by the growning acetylene writing with the olefin, strong evidence for ... |
|
| Synthesis of Phenols from Metal-Carbynes and Diynes |
07 MAR 85 |
|
| Authors:
T. M. Sivavec; T. J. Katz; COLUMBIA UNIV NEW YORK DEPT OF CHEMISTRY
|
| Metal-carbynes RC-M(CO)4BrTriple bond) with diacetylenes give specific phenols in good yield. The reactions take only a few minutes at or below room temperature. Metal-carbynes, unlike metal-carbenes, have rarely been considered reagents for organic synthesis although those illustrated by structre 1 have been known for a dozen years and are fairly easy to prepare. We reported recently that a number of tungsten metal-carbynes, by polymerizing a variety of acetylenes and cyclic ... |
|
| The Mechanisms of Phenylacetylene Polymerization by Molybdenum and Titanium Initiators |
18 FEB 85 |
|
| Authors:
T. J. Katz; S. M. Hacker; R. D. Kendrick; C. S. Yannoni; COLUMBIA UNIV NEW YORK DEPT OF CHEMISTRY
|
| Polymerizing phenylacetylene, a few of whose molecules are doubly labeled by 13C's on the triple bond, gives poly(phenylacetylene) in which labels are separated by a double bond when the initiator is titanium tetrabutoxide plus triethylaluminum and by a single bond when it is molybdenum pentachloride plus tetraphenytin. This tallies with the idea that the acetylene polymeri- zations induced by derivatives of molybdenum are olefin metatheses, while those induced by derivatives ... |
|
| Fluorescence Probes for Aqueous Solutions of Nonionic Micelles |
85 |
|
| Authors:
N. J. Turro; P. L. Kuo; COLUMBIA UNIV NEW YORK DEPT OF CHEMISTRY
|
| Three fluorescence probes, pyrenecarboxaldehyde (PA), pyrene (P), and an ionic indole labeled detergent (In), have been employed to investigate nonionic (Triton) micelles of varying EO number. PA serves as a probe of the surface of micelle, P serves as a probe of the inner layer of micelles, and In serves as a probe of the inner core of micelles. Measurement of fluorecence parameters for PA, P, and In as a ... |
|
| Fluorescence Quenching of Methoxybenzyl Alcohols by the Hydronium Ion in Aqueous Solution: Acid-Catalyzed Formation of Methoxybenzyl Cations from the Singlet Excited State |
85 |
|
| Authors:
N. J. Turro; P. Wan; COLUMBIA UNIV NEW YORK DEPT OF CHEMISTRY
|
| The photochemical and photophysical behavior of a number of methoxy- substituted benzyl alcohols has been studied in aqueous solution as a function of pH. Evidence is presented which indicates that, on excitation to the singlet excited state, the ortho and meta methoxy-substituted benzyl alcohols undergo proton-assisted loss of hydroxide ion to give the corresponding benzyl cations. These results are discussed with reference to the photoselectivity observed by Zimmerman and Sandel ... |
|
| A Metal-Catalyzed Rearrangement of Alkene-Alkynes and the Stereochemistry of Metallacyclobutene Ring Opening |
27 DEC 1984 |
|
| Authors:
T. J. Katz; T. M. Sivavec; COLUMBIA UNIV NEW YORK DEPT OF CHEMISTRY
|
| A molecular rearrangement is described that demonstrates how alkyl- metal-carbenes are generated when metal derivatives combine with acetylenes and olefins and shows that tungsten-carbenes not stabilized by heteroatoms insert into acetylenes. It reveals that this insertion can be remarkably stereo- selective. With catalytic amounts of carbene-tungsten carbonyls, biphenyls substituted at the 2 and 2' positions by vinyl and acetylene groups yield isomeric 9-vinylphenanthrenes. With stoichiometric amounts, they yield 9-vinyl- phenanthrenes ... |
|
| Dialkylaminobenzonitriles as Fluorescence Polarity Probes for Aqueous Solutions of Cyclodextrins |
1984 |
|
| Authors:
G. S. Cox; P. J. Hauptman; N. J. Turro; COLUMBIA UNIV NEW YORK DEPT OF CHEMISTRY
|
|
| Photoluminescence Probes for the Investigation of Interactions between Sodium Dodecyl Sulfate and Water-Soluble Polymers |
1984 |
|
| Authors:
N. J. Turro; B. H. Baretz; P. L. Kuo; COLUMBIA UNIV NEW YORK DEPT OF CHEMISTRY
|
|
| Photoluminescent Probes for Water-Soluble Polymers. Pressure and Temperature Effects on a Polyol Surfactant |
84 |
|
| Authors:
N. J. Turro; C. J. Chung; COLUMBIA UNIV NEW YORK DEPT OF CHEMISTRY
|
| Five photoluminescent probes have been employed to investigate the behavior of a poly(ethylene oxide)-poly(propylene oxide) block copolymer in aqueous solution. The measured fluorescence probe parameters, at fixed probe concentration, were found to be dependent on the concentration of copolymers and to demonstrate a low-, medium-, and high-concentration domain. In the high- concentration domain the parameters were found to be extremely sensitive to temperature and pressure. The results are interpreted in ... |
|
| The Mechanism of Ziegler-Natta Polymerization of Acetylene: A Nutation NMR Study |
09 DEC 1983 |
|
| Authors:
T. C. Clarke; C. S. Yannoni; T. J. Katz; COLUMBIA UNIV NEW YORK DEPT OF CHEMISTRY
|
| Using nutation NMR spectroscopy the distance between adjacent 13C labels was measured in samples of polyacetylene prepared by polymerizing a dilute solution of double 13C-labelled acetylene in 12C-acetylene using titanium tetra-n-butoxide plus triethylaluminum as a catalyst. The experiments accord with expectation if the polymerization proceeds by a four-center insertion mechanism rather than by a metallacycle mechanism involving metal-carbenes. (Author) |
|
| Polymerizations of Acetylenes and Cyclic Olefins Induced by Metal- Carbynes |
09 DEC 1983 |
|
| Authors:
T. J. Katz; T. H. Ho; N. Shih; Y. Ying; V. I. W. Stuart; COLUMBIA UNIV NEW YORK DEPT OF CHEMISTRY
|
| Trans-(bromotetracarbonyl(phenylmethylidyne)tungsten) and related metal-carbynes induce acetylenes and cycloalkenes to polymerize. The acetylenes include examples that are monosubstituted, disubstituted, and unsubstituted, as well as the first reported functionalized acetylenes in which the functional groups (the nitrile, ester, and halogen functions were studied) are not attached to the triple bond. The cycloalkenes yield polyalkenamers whose double bonds are largely cis. This last polymerization is speeded by the presence of oxygen. The stereochemistries ... |
|
| Polymerization of Functionalized Acetylenes |
09 DEC 1983 |
|
| Authors:
T. H. Ho; T. J. Katz; COLUMBIA UNIV NEW YORK DEPT OF CHEMISTRY
|
| The initiator that has most frequently been used to metathesize functionalized olefins---WCl6 + (CH3)4Sn---is an effective initiator for the polymerizations of acetylenes substituted by cyano, ester, and halogen groups. Various initiators effective for acetylenic hydrocarbons fail with these funtionalized derivatives. (Author) |
|
| Picosecond Laser Studies of Excited State Processes |
15 NOV 1983 |
|
| Authors:
K. B. Eisenthal; COLUMBIA UNIV NEW YORK DEPT OF CHEMISTRY
|
| Progress is reported in studies of key chemical and physical processes by which molecules in excited electronic states dissipate their excess energy. Many of these energy relaxing mechanisms and related molecular motions are so extremely rapid, especially in liquids, that they require special techniques for their study. To this end sophisticated picosecond laser systems were constructed which enable detection of transient absorption, emission and scattering events on the picosecond time ... |
|
| Structural and Dynamic Studies of Materials Possessing High Energy Content |
31 OCT 1983 |
|
| Authors:
N. J. Turro; COLUMBIA UNIV NEW YORK DEPT OF CHEMISTRY
|
| This final report updates and summarizes the research accomplished under this grant during the period of November 1, 1980 through October 31, 1983. We have emphasized investigations in the following areas: photochemical mechanisms through the use of time-resolved laser flash spectroscopy; Carbenes, radical pairs, ylides, singlet molecular oxygen and other high energy species; Detailed and systematic determination of the absolute rate constants for the addition of carbenes to ethylenes; Application ... |
|
| Induction of Olefin Metathesis by Phenylacetylene Plus Tungsten Hexachloride |
21 JUN 1982 |
|
| Authors:
Thomas J. Katz; Chien-Chung Han; COLUMBIA UNIV NEW YORK DEPT OF CHEMISTRY
|
| Phenylacetylene induces tungsten hexachloride to initiate metathesis of cis-2-pentene, cyclopentene, cycloheptene, and cyclooctene. In too large amounts, however, it is ineffective. The reactions are run in the atmosphere. The stereo-selectivities for cis-olefins are moderate. (Author) |
|
| Preparation of Polymers Using Metal-Carbenes. |
07 FEB 1980 |
|
| Authors:
Thomas J. Katz; Steven J. Lee; Michael A. Shippey; COLUMBIA UNIV NEW YORK DEPT OF CHEMISTRY
|
| Metal-carbenes initiate the polymerizations of cycloalkenes to polyalkenamers that are stereoselectively cis, cyclic trisubstituted olefins to polymers that are translationally invariant, and acetylenes to polyacetylenes. Some implications are described. (Author) |
|
| Energy Distribution of the Fragments Produced by Photodissociation of CS2 at 193 nm, |
02 OCT 1979 |
|
| Authors:
S. C. Yang; A. Freedman; M. Kawasaki; R. Bersohn; COLUMBIA UNIV NEW YORK DEPT OF CHEMISTRY
|
|
| Organometallic Compounds. |
14 MAY 1979 |
|
| Authors:
Thomas J. Katz; COLUMBIA UNIV NEW YORK DEPT OF CHEMISTRY
|
| Studies are described aimed at testing whether novel polymeric chemical structures can be synthesized in which hydrocarbon rings and metal atoms alternate. A number of appropriate hydrocarbon dianions have been synthesized for the first time, as have a number of molecules containing two metal atoms sandwiched between a pair of planar hydrocarbons. Structures like this were not known before the start of the work. Some properties of these novel materials ... |
|
| Metal Combustion Processes as Studied by Chemi-luminescence and Chemi-ionization. |
FEB 1978 |
|
| Authors:
Richard N. Zare; COLUMBIA UNIV NEW YORK DEPT OF CHEMISTRY
|
| Metal combustion processes have been studied (1) by observing and spectroscopically analyzing visible emission; (2) by detecting dark states through their characteristic laser-induced fluorescence; and (3) by determining the nature and type of ionic products produced in some of these highly exothermic reactions. In the course of this work we seek general principals that can tell us about the various ways of disposing of excess reaction energy in the products. ... |
|
| Structural and Dynamic Studies of Materials Possessing High Energy Content. |
30 JAN 1978 |
|
| Authors:
Nicholas J. Turro; COLUMBIA UNIV NEW YORK DEPT OF CHEMISTRY
|
| The goal of this research is to provide a theoretical and experimental basis for the understanding of the properties of excited molecules and their emission characteristics. A particular emphasis has been directed toward the identification of chemiluminescent systems which might have the highest likelihood of providing a framework for the development of operating chemical lasers which emit in the visible spectral range. The thermal chemistry and photochemistry of dioxetanes and ... |
|
| Laser Fluorescence Study of Vibrational Energy Equilibration in CH3F:O2 Mixtures: 'Impurity' Molecules as Probes of Mode to Mode Energy Flow Pathways, |
15 AUG 1977 |
|
| Authors:
J. M. Preses; G. W. Flynn; COLUMBIA UNIV NEW YORK DEPT OF CHEMISTRY
|
|
| Laser Excited Infrared Fluorescence in COF2: Equilibration and Relaxation of the C=O and C-F Stretching Modes, |
18 MAY 1977 |
|
| Authors:
Kent H. Casleton; George W. Flynn; COLUMBIA UNIV NEW YORK DEPT OF CHEMISTRY
|
|
| State Identification of Reaction Products. |
MAR 1977 |
|
| Authors:
Richard N. Zare; COLUMBIA UNIV NEW YORK DEPT OF CHEMISTRY
|
| The final scientific report contains a chronological bibliography of 14 publications supported by this contract, as well as a brief summary emphasizing our attempts to make a prototype chemically-driven electronic transition laser. (Author) |
|
| Determination of Absolute Photon Yields in Chemiluminescent Reactions. |
DEC 1976 |
|
| Authors:
Richard N. Zare; COLUMBIA UNIV NEW YORK DEPT OF CHEMISTRY
|
| An experimental procedure is presented to measure the absolute photon yield, the percentage probability of emitting a visible photon per reactant molecule consumed, for chemiluminescent reactions under single collision conditions. Using a well-defined metal beam directed into a scattering gas at sub-millitorr pressures, this procedure is applied to the reactions Sm+N2O, Sm+F2, Ba+N2O, and Ba+NO2 to obtain the photon yields in the 350-800 nm range of 0.18%, 5.5%, 1.1% and ... |
|
| Project LABSTAR: Study of the Formation and Structure of Excited High-Temperature Metal Compounds. |
MAR 1976 |
|
| Authors:
Richard N. Zare; COLUMBIA UNIV NEW YORK DEPT OF CHEMISTRY
|
| The chemiluminescent reactions of metal atoms with various oxidizer gases had been investigated under single-collision conditions using a beam-plus-gas experimental arrangement. From these studies we have established new ground state dissociation energy for CAO, SRO, BAO, PBO, EUO, EUF, SMO and SMF. Much of the interest assoicated with these reactions is the possibility of constructing a chemically-driven short-wavelength laser. For this purpose we have made lifetime measurements of various excited ... |
|
| Chemical Reactions Initiated by Infrared Lasers. |
20 MAY 1975 |
|
| Authors:
George Flynn; COLUMBIA UNIV NEW YORK DEPT OF CHEMISTRY
|
| This report summarizes research in the areas of laser initiated chemical reactions, mode to mode energy transfer in polyatomic molecules, and molecular relaxation processes. (Author) |
|
| Structural and Dynamic Studies of Materials Possessing High Energy Content. |
1974 |
|
| Authors:
Nicholas J. Turro; COLUMBIA UNIV NEW YORK DEPT OF CHEMISTRY
|
| Chemiluminescence is observed when solutions of tetramethyl-1,2-dioxetane (1) are heated. Recent research has been direct toward elucidation of the mechanism of the chemiexcitation step which converts the exothermicity of decomposition of (1) into electronic excitation which then eventuates in light emission. The chemiluminescence from solutions of (1) can be employed as a powerful tool in the study of reaction mechanisms and can be used to develop novel and efficient chemiluminescent ... |
|
| Development of Metal Halide Lasers. |
01 JUN 1973 |
|
| Authors:
Richard N. Zare; COLUMBIA UNIV NEW YORK DEPT OF CHEMISTRY
|
| Work was initiated to assess the feasibility of constructing a visible laser employing electronically excited metal halide molecules as an active media. Special attention was focussed on the group IIA metal monohalides. Fluorescence intensity versus time is plotted and a method of measuring radiative lifetime is developed. |
|
| Microwave Studies of Molecular Magnetism. |
30 JUN 1972 |
|
| Authors:
Benjamin P. Dailey; COLUMBIA UNIV NEW YORK DEPT OF CHEMISTRY
|
| The magnetic properties of carbonyl sulfide have been studied in the past by various authors using both conventional microwave spectroscopy and molecular beam electric resonance. The molecular beam techniques give very precise results but are difficult and relatively inflexible and it has been found possible to study a much wider variety of molecules using microwave techniques. As part of a program to improve the microwave method so that it might ... |
|
Reports by Corporate Author
