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General chemistry, physical chemistry, Chimie générale, chimie physique, Metallurgy, welding, Métallurgie, soudage, Atomic molecular physics, Physique atomique et moléculaire, Sciences exactes et technologie, Exact sciences and technology, Chimie, Chemistry, Chimie generale et chimie physique, General and physical chemistry, Solutions, Solvatation. Propriétés des solvants, Solvation. Solvent properties, Agent surface anionique, Anionic surfactant, Agente superficie aniónico, Benzène(bromo), Diffusion multiple, Multiple scattering, Difusión múltiple, Etude expérimentale, Experimental study, Estudio experimental, Hexane, Hexano, Hydrocarbure bromé, Bromocarbon, Hidrocarburo bromado, Interaction intermoléculaire, Intermolecular interaction, Interacción intermolecular, Rubidium Composé, Rubidium Compounds, Rubidio Compuesto, Simulation ordinateur, Computer simulation, Simulación computadora, Sodium Composé, Sodium Compounds, Sodio Compuesto, Solubilisation, Solubilization, Solubilización, Solution aqueuse, Aqueous solution, Solución acuosa, Solution micellaire, Micellar solution, Solución micelar, Spectrométrie absorption RX, X ray absorption spectrometry, Espectrometría absorción RX, Sulfate organique, Organic sulfate, Sulfato orgánico, Sulfate(lauryl), Dodécane(1-bromo), Ethane(bromo), Propane(1-bromo), Propane(2-bromo), Propane(2-bromo-2-méthyl), Rubidium désoxycholate, and Sodium désoxycholate

X-ray absorption measurements performed on various systems containing brominated hydrocarbons showed remarkable differences in the bromine K-edge spectra recorded in polar or nonpolar media. For this reason, the brominated hydrocarbons can be used to monitor the polarity of the medium in which they are buried. By determining the coordination of the bromine atom, information on the interactions between the probe molecule and several systems such as micelles, macromolecules, membranes, solvent molecules, and host molecules in inclusion compounds can be obtained. Brominated hydrocarbons in aqueous micellar solutions of sodium and rubidium deoxycholate and sodium dodecyl sulfate have been investigated by means of the XAS technique. Experimental and calculated EXAFS spectra and Fourier transform functions are presented.

General chemistry, physical chemistry, Chimie générale, chimie physique, Metallurgy, welding, Métallurgie, soudage, Atomic molecular physics, Physique atomique et moléculaire, Sciences exactes et technologie, Exact sciences and technology, Chimie, Chemistry, Chimie generale et chimie physique, General and physical chemistry, Physicochimie de surface, Surface physical chemistry, Interface solide-gaz, Solid-gas interface, Métal transition Composé, Transition metal Compounds, Metal transición Compuesto, Adsorbant minéral, Inorganic adsorbent, Adsorbente inorgánico, Adsorbat minéral, Inorganic adsorbate, Adsorbato inorgánico, Adsorption gaz solide, Gas solid adsorption, Adsorción gas sólido, Ammoniac, Ammonia, Amoníaco, Caractérisation, Characterization, Caracterización, Composé binaire, Binary compound, Compuesto binario, Désorption gaz solide, Gas solid desorption, Desorción gas sólido, Eau, Water, Agua, Etude expérimentale, Experimental study, Estudio experimental, Interface gaz solide, Gas solid interface, Interfase gas sólido, Matériau modifié, Modified material, Material modificado, Silicate, Silicates, Silicato, Spectrométrie EXAFS, EXAFS spectrometry, Espectrometría EXAFS, Spectrométrie UV visible, Ultraviolet visible spectrometry, Espectrometría UV visible, Spectrométrie XANES, XANES spectrometry, Espectrometría XANES, Structure surface, Surface structure, Estructura superficie, Tamis moléculaire, Molecular sieve, Tamiz molecular, Titane Oxyde, Titanium Oxides, Titanio Óxido, Transformation Fourier, Fourier transformation, Transformación Fourier, H N, H O, H2O, NH3, and O Si Ti

X-ray absorption at the Ti K edge (both XANES and EXAFS) of a very pure Ti-silicalite containing a small fraction of Ti(IV) substituting for Si(IV) has been performed in order to study the effect of the presence or absence of ligands such as H2O and NH3 on the Ti(IV) coordination sphere. In particular, the effect of an outgassing treatment at 400 K and of the interaction with NH3 has been studied and described in detail. It has been found that the Ti(IV) is fourfold coordinated in the samples outgassed at 400 K and expands its coordination sphere number with action of adsorbates. The process is partially reversible at room temperature.

General chemistry, physical chemistry, Chimie générale, chimie physique, Metallurgy, welding, Métallurgie, soudage, Atomic molecular physics, Physique atomique et moléculaire, Sciences exactes et technologie, Exact sciences and technology, Physique, Physics, Etat condense: structure, proprietes mecaniques et thermiques, Condensed matter: structure, mechanical and thermal properties, Structure des liquides et des solides; cristallographie, Structure of solids and liquids; crystallography, Fullerènes et matériaux apparentés, Fullerenes and fullerene-related materials, Chimie, Chemistry, Chimie generale et chimie physique, General and physical chemistry, Physicochimie de surface, Surface physical chemistry, Interface solide-liquide, Solid-liquid interface, Etat colloïdal et états dispersés, Colloidal state and disperse state, Etudes physiques et chimiques. Granulométrie. Phénomènes électrocinétiques, Physical and chemical studies. Granulometry. Electrokinetic phenomena, Clusters, nanoparticles, and nanocrystalline materials, Métal transition Composé, Transition metal Compounds, Metal transición Compuesto, Métal transition, Transition metal, Metal transición, Adsorbat minéral, Inorganic adsorbate, Adsorbato inorgánico, Adsorption gaz solide, Gas solid adsorption, Adsorción gas sólido, Analyse surface, Surface analysis, Análisis superficie, Cadmium Séléniure, Cadmium Selenides, Cadmio Seleniuro, Caractérisation, Characterization, Caracterización, Composé binaire, Binary compound, Compuesto binario, Dimension particule, Particle size, Dimensión partícula, Etude expérimentale, Experimental study, Estudio experimental, Interface gaz solide, Gas solid interface, Interfase gas sólido, Interface liquide solide, Liquid solid interface, Interfase líquido sólido, Nanocristal, Nanocrystal, Or, Gold, Oro, Oxydation, Oxidation, Oxidación, Oxygène Molécule, Oxygen Molecules, Oxígeno Molécula, Particule colloïdale, Colloid particle, Partícula coloidal, Particule sous micronique, Submicron particle, Partícula submicrónica, Rayon X, X ray, Rayos X, Réaction surface, Surface reaction, Reacción superficie, Spectrométrie optique, Optical spectrometry, Espectrometría óptica, Spectrométrie photoélectron, Photoelectron spectrometry, Espectrometría fotoelectrón, Support, Soporte, Suspension particule, Particle suspension, Suspensión partícula, Sélénium Oxyde, Selenium Oxides, Selenio Óxido, Toluène, Toluene, Tolueno, Au, Cd Se, CdSe, O Se, O2, and SeO2

We report the use of X-ray photoelectron spectroscopy (XPS) to determine the surface composition of semiconductor nanocrystals. Crystalline, nearly monodisperse CdSe nanocrystals ranging in radius from 9 to 30 Å were chemically synthesized and covalently bound to Au and Si surfaces for study. XPS core level peak positions for Cd and Se were in agreement with those of bulk CdSe. We have determined that the majority of Se atoms on the surface are unbonded as prepared and that Cd atoms are bonded to the surface ligand, tri-n-octylphosphine oxide, to the extent that such bonding is sterically allowed. We have determined that the total ligand saturation of the nanocrystal surface varies from 60% in the smaller nanocrystals to 30% in the larger nanocrystals.

General chemistry, physical chemistry, Chimie générale, chimie physique, Metallurgy, welding, Métallurgie, soudage, Atomic molecular physics, Physique atomique et moléculaire, Sciences exactes et technologie, Exact sciences and technology, Chimie, Chemistry, Chimie generale et chimie physique, General and physical chemistry, Etat colloïdal et états dispersés, Colloidal state and disperse state, Membranes, Diffraction RX, X ray diffraction, Difracción RX, Effet milieu, Medium effect, Efecto medio, Equilibre liquide solide, Liquid solid equilibrium, Equilibrio líquido sólido, Equilibre phase, Phase equilibrium, Equilibrio fase, Etude expérimentale, Experimental study, Estudio experimental, Membrane, Membrana, Phosphatidylcholine, Fosfatidilcolina, Phospholipide, Phospholipid, Fosfolípido, Structure lamellaire, Lamellar structure, Estructura lamelar, Température, Temperature, Temperatura, Vésicule, Vesicle, Vesícula, Fluor 19, Glycérol(1,2-di-O-myristoyl) phosphate(2-[triméthylammonio]éthyl), Glycérol(2-O-[12,12-difluoromyristoyl]-1-O-myristoyl) phosphate(2-[triméthylammonio]éthyl), Glycérol(2-O-[4,4-difluoromyristoyl]-1-O-myristoyl) phosphate(2-[triméthylammonio]éthyl), and Glycérol(2-O-[8,8-difluoromyristoyl]-1-O-myristoyl) phosphate(2-[triméthylammonio]éthyl)

Low-angle and wide-angle X-ray diffraction was used to examine the phase behavior, as a function of temperature, of fully hydrated multilamellar vesicles of dimyristoylphosphatidylcholine (DMPC) labeled with a difluoromethylene group in the sn:2 acyl chain at position 4, 8, or 12. At temperatures near 5°C, DMPC and 2-[12,-12-F2]DMPC are both in the Lβ' (gel) phase with a D-spacing of 59.5±0.5 Å, 2-[8,8-F2]DMPC is in the Pβ' (rippled) phase with a D-spacing of 65.0±0.5 Å, and 2-[4,4-F2]DMPC is in the Lc (subgel) phase with a D-spacing of 56.5±0.5 Å.

General chemistry, physical chemistry, Chimie générale, chimie physique, Metallurgy, welding, Métallurgie, soudage, Atomic molecular physics, Physique atomique et moléculaire, Sciences exactes et technologie, Exact sciences and technology, Physique, Physics, Physique atomique et moleculaire, Atomic and molecular physics, Processus de collision et interactions atomiques et moléculaires, Atomic and molecular collision processes and interactions, Théories générales et modèles des interactions et collisions atomiques et moléculaires (incluant les théories statistiques, les modèles de l'état de transition, stochastiques et de traject, General theories and models of atomic and molecular collisions and interactions (including statistical theories, transition state, stochastic and trajectory models, etc.), Approximation semiclassique, Semiclassical approximation, Champ électrique, Electric fields, Collision, Collisions, Dynamique, Dynamics, Equation Schrödinger, Schroedinger equation, Etude théorique, Theoretical study, Interaction, Interactions, Opérateur densité, Density operator, Operador densidad, Potentiel Morse, Morse potential, Probabilité transition, Transition probabilities, Théorie Wigner, Wigner theory, Trajectoire, and Trajectories

The possibility of introducing an interaction picture in the semiclassical Wigner method is investigated. This is done with an interaction picture description of the density operator dynamics as starting point. We show that the dynamics of the density operator dynamics as starting point. We show that the dynamics of the interaction picture Wigner function is solved by running a swarm of trajectories in the classical interaction picture introduced previously in the literature. Solving the Wigner method dynamics of collision processes in the interaction picture ensures that the calculated transition probabilities are unambiguous even when the asymptotic potentials are anharmonic.

General chemistry, physical chemistry, Chimie générale, chimie physique, Metallurgy, welding, Métallurgie, soudage, Atomic molecular physics, Physique atomique et moléculaire, Sciences exactes et technologie, Exact sciences and technology, Chimie, Chemistry, Chimie generale et chimie physique, General and physical chemistry, Physicochimie de surface, Surface physical chemistry, Interface gaz-liquide et liquide-liquide, Gas-liquid interface and liquid-liquid interface, Agent surface non ionique, Non ionic surfactant, Agente superficie no iónica, Alcane, Alkane, Alcano, Angle contact, Contact angle, Angulo contacto, Diagramme phase, Phase diagram, Diagrama fase, Effet milieu, Medium effect, Efecto medio, Ether polymère, Ether polymer, Eter polímero, Ethylène oxyde polymère, Ethylene oxide polymer, Etileno óxido polímero, Etude expérimentale, Experimental study, Estudio experimental, Hexadécane, Hexadecane, Hexadecano, Hydrocarbure, Hydrocarbon, Hidrocarburo, Interface liquide liquide, Liquid liquid interface, Interfase líquido líquido, Mouillage, Wetting, Remojo, Paramètre critique, Critical parameter, Parámetro crítico, Solution aqueuse, Aqueous solution, Solución acuosa, Température critique, Critical temperature, Temperatura crítica, Température transition, Transition temperature, Temperatura transición, Température, Temperature, Temperatura, Tension interfaciale, Interface tension, Tensión interfacial, Ethylène oxyde polymère éther alkyle, Octadécane, and Tétradécane

There is a controversial problem concerning the wetting properties in the three-liquid-phase region of the system water +n-hexadecane+C6E2, where CiEj denotes the nonionic surfactant poly(oxyethylene) alcohol CiH2i+1(OCH2CH2)jOH. In this study, both interfacial tension measurements and direct contact angle measurements are used to further reconfirm that the middle phase of this system does exhibit a wetting at the interface separating the upper and the lower phase as temperature is increased towards the upper critical consolute temperature. The effect of chain length of oil on the wetting transition is also discussed in the ternary system water+n-alkane+C6E2 by using three different oils: n-tetradecane, n-hexadecane, and n-octadecane.

General chemistry, physical chemistry, Chimie générale, chimie physique, Metallurgy, welding, Métallurgie, soudage, Atomic molecular physics, Physique atomique et moléculaire, Sciences exactes et technologie, Exact sciences and technology, Chimie, Chemistry, Chimie generale et chimie physique, General and physical chemistry, Physicochimie des réactions induites par rayonnements, particules et ultrasons, Physical chemistry of induced reactions (with radiations, particles and ultrasonics), Photochimie, Photochemistry, Physicochimie de surface, Surface physical chemistry, Interface solide-gaz, Solid-gas interface, Métal transition, Transition metal, Metal transición, Adsorbant métallique, Metallic adsorbent, Adsorbente metálico, Adsorbat minéral, Inorganic adsorbate, Adsorbato inorgánico, Adsorption gaz solide, Gas solid adsorption, Adsorción gas sólido, Argent, Silver, Plata, Composé binaire, Binary compound, Compuesto binario, Degré recouvrement, Coverage rate, Grado recubrimiento, Dissociation chimique, Chemical dissociation, Disociación química, Désorption gaz solide, Gas solid desorption, Desorción gas sólido, Etude expérimentale, Experimental study, Estudio experimental, Face cristalline, Crystal face, Cara cristal, Interface gaz solide, Gas solid interface, Interfase gas sólido, Irradiation, Irradiación, Méthode temps vol, Time of flight method, Método tiempo vuelo, Photochimie, Photochemistry, Fotoquímica, Rayonnement UV, Ultraviolet radiation, Radiación ultravioleta, Réaction surface, Surface reaction, Reacción superficie, Soufre dioxyde, Sulfur dioxide, Dióxido sulfúrico, Thermodésorption, Thermodesorption, Desabsorción térmica, Ag, O S, and SO2

Using pulsed laser excitation, and focusing on multilayers, the photochemistry of SO2 adsorbed on Ag(111) has been studied by time-of-flight mass spectrometry, complemented by temperature-programmed desorption and Auger electron spectroscopy. At 193, 248, and 351 nm, irradiation of multilayers, but not of monolayers, leads to reactions that break sulfur-oxygen bonds. Photochemistry in the multilayer tracks the SO2 absorption. At 437 and 500 nm, where SO2 does not absorb, no dissociation products (O, SO, or SO3) were detected during (time-of-flight) or after (temperature-programmed desorption and Auger electron spectroscopy) irradiation. Only 193-nm photons induce unimolecular bond dissociation, whereas parent desorption and a bimolecular photoreaction are evident at three wavelengths (193, 248, and 351 nm).

General chemistry, physical chemistry, Chimie générale, chimie physique, Metallurgy, welding, Métallurgie, soudage, Atomic molecular physics, Physique atomique et moléculaire, Sciences exactes et technologie, Exact sciences and technology, Physique, Physics, Physique atomique et moleculaire, Atomic and molecular physics, Propriétés moléculaires et interactions avec les photons, Molecular properties and interactions with photons, Résonance et relaxation nucléaires, Nuclear resonance and relaxation, Composé minéral, Inorganic compounds, Lanthanide complexe, Rare earth complexes, Agent contraste paramagnétique, Paramagnetic contrast agent, Agente contraste paramagnético, Chélate, Chelates, Cinétique, Kinetics, Constante vitesse, Rate constant, Constante velocidad, Coordinat organique, Organic ligand, Ligando orgánico, Domaine pression, Pressure range, Domaine température 0273-0400 K, Temperature range 0273-0400 K, Domaine température 0400-1000 K, Temperature range 0400-1000 K, Déplacement chimique, Chemical shift, Effet champ magnétique, Magnetic field effects, Energie libre, Free energy, Enthalpie, Enthalpy, Entropie, Entropy, Etat rotationnel, Rotational states, Etude expérimentale, Experimental study, Gadolinium complexe, Gadolinium complexes, Hydrate, Hydrates, Imagerie RMN, NMR imaging, Oxygène 17, Oxygen 17, Propriété thermodynamique, Thermodynamic properties, Relaxation électron, Electron relaxation, Relajación electrón, Solution aqueuse, Aqueous solutions, Spectre RMN, NMR spectra, Temps relaxation, Relaxation time, and Diéthylènetriamine-«N,N,N',N'',N''»-pentaacétique acide dérivé

17O NMR longitudinal and transverse relaxation rates and chemical shifts have been measured for aqueous solutions of the chelate complex [Gd(DTPA-BMA)(H2O)] at variable temperature, pressure, and magnetic field. The results were analyzed in terms of the water-exchange kinetics, the rotational motion of the chelate complex, and the electronic relaxation of the Gd3+ ion in the chelate complex. The water-exchange kinetic parameters are kex298=(4.3±0.2)×105 s-1, ΔH=46.6±1.3 kJ mol-1, ΔS=+18.9±4.0 J K-1 mol-1, and ΔV0=+7.3±0.2 cm-1 mol-1.

General chemistry, physical chemistry, Chimie générale, chimie physique, Metallurgy, welding, Métallurgie, soudage, Atomic molecular physics, Physique atomique et moléculaire, Sciences exactes et technologie, Exact sciences and technology, Physique, Physics, Physique atomique et moleculaire, Atomic and molecular physics, Structure électronique des atomes, des molécules et de leurs ions: théorie, Electronic structure of atoms, molecules and their ions: theory, Calculs de corrélation électronique pour les atomes et les molécules, Electron correlation calculations for atoms and molecules, Composé organique, Organic compounds, Acétaldéhyde, Acetaldehyde, Calcul ab initio, Ab initio calculations, Corrélation électronique, Electron correlation, Energie potentielle, Potential energy, Etat excité, Excited states, Etat vibronique, Vibronic states, Etude théorique, Theoretical study, Méthode Hartree Fock, Hartree-Fock method, Partition Moller Plesset, Moller Plesset partition, Partición Moller Plesset, Structure électronique, and Electronic structure

The T1←S0 electronic band spectrum in acetaldehyde was simulated from RHF and UHF/MP2/6-311G(d,p) ab initio calculations for the two electronic states. The torsion-wagging energy levels were evaluated by the variational method using free rotor basis functions expressed as symmetrized double-Fourier expansions. A comparison of the calculated band spectrum to the long-path absorption spectrum allowed for the assignment of a number of clearly defined bands and placed the origin at 27 240 cm-1. The calculated height of the barrier to internal rotation for the lower S0 state of 415 cm-1 yielded levels in excellent agreement with the torsional levels derived from far infrared measurements.

General chemistry, physical chemistry, Chimie générale, chimie physique, Metallurgy, welding, Métallurgie, soudage, Atomic molecular physics, Physique atomique et moléculaire, Sciences exactes et technologie, Exact sciences and technology, Chimie, Chemistry, Chimie generale et chimie physique, General and physical chemistry, Electrochimie, Electrochemistry, Propriétés des électrolytes: conductivité, Properties of electrolytes: conductivity, Sciences appliquees, Applied sciences, Physicochimie des polymeres, Physicochemistry of polymers, Polymères organiques, Organic polymers, Propriétés et caractérisation, Properties and characterization, Propriétés électriques, magnétiques et optiques, Electrical, magnetic and optical properties, Acide polymère, Polyacid, Acido polímero, Ammonium quaternaire composé, Quaternary ammonium compound, Amonio cuaternario compuesto, Argent Ion, Silver Ions, Plata Ión, Caractérisation, Characterization, Caracterización, Coefficient diffusion, Diffusion coefficient, Coeficiente difusión, Conduction ionique, Ionic conduction, Conducción iónica, Césium Ion, Cesium Ions, Cesio Ión, Diffusion ion, Ion scattering, Difusión ión, Effet concentration, Concentration effect, Efecto concentración, Electrode disque, Disk electrode, Electrodo disco, Etude expérimentale, Experimental study, Estudio experimental, Ion antagoniste, Counter ion, Ion antagonista, Lithium Ion, Lithium Ions, Litio Ión, Microélectrode, Microelectrode, Microeléctrodo, Méthode électrochimique, Electrochemical method, Método electroquímico, Platine, Platinum, Platino, Polyélectrolyte, Polyelectrolyte, Polielectrolito, Propriété transport, Transport properties, Propiedad transporte, Sodium Ion, Sodium Ions, Sodio Ión, Solution aqueuse, Aqueous solution, Solución acuosa, Solution électrolyte, Electrolyte solution, Solución electrólito, Styrènesulfonique acide polymère, Styrenesulfonic acid polymer, Estireno sulfónico ácido polímero, Transport ion, Ion transport, Transporte iónica, Voltammétrie, Voltammetry, Voltametría, Ag ip 1, Ammonium(tétraméthyl), Cs ip 1, Li ip 1, Na ip 1, and Pt

The transport of hydrogen counterions was studied in solutions of the strong polymer acid poly(styrenesulfonic acid) (PSSA) by voltammetric measurements at Pt disc microelectrodes. Use of voltammetric microelectrodes makes measurement possible in the absence of supporting electrolyte. Very strong interactions between counterion and polyion were observed under these conditions. Results obtained for polyacid solutions were compared with results for simple strong acids. The experimentally determined limiting value (with no electrolyte) of D/D0 was 0.345, where D and D0 are diffusion coefficients of counterion with and without PSSA.

General chemistry, physical chemistry, Chimie générale, chimie physique, Metallurgy, welding, Métallurgie, soudage, Atomic molecular physics, Physique atomique et moléculaire, Sciences exactes et technologie, Exact sciences and technology, Physique, Physics, Physique atomique et moleculaire, Atomic and molecular physics, Structure électronique des atomes, des molécules et de leurs ions: théorie, Electronic structure of atoms, molecules and their ions: theory, Calculs et techniques mathématiques en physique atomique et moléculaire (sauf les calculs de corrélation électronique), Calculations and mathematical techniques in atomic and molecular physics (excluding electron correlation calculations), Calculs ab initio, Ab initio calculations, Propriétés moléculaires et interactions avec les photons, Molecular properties and interactions with photons, Propriétés des molécules et des ions moléculaires, Properties of molecules and molecular ions, Constantes rotationnelles, vibrationnelles et rovibrationnelles, Rotation, vibration and vibration-rotation constants, Interactions des photons avec les molécules, Photon interactions with molecules, Ionisation et excitation multiphotoniques vers des états hautement excités (ex.: états de rydberg), Multiphoton ionization and excitation to highly excited states (e.g., rydberg states), Vibronic, rovibronic, and rotation-electron-spin interactions, Multiphoton ionization and excitation to highly excited states (eg, Rydberg states), Calcul ab initio, Ab initio calculations, Composé bicyclique, Bicyclic compound, Compuesto bicíclico, Etat excité, Excited states, Etat vibrationnel, Vibrational states, Etat vibronique, Vibronic states, Etude expérimentale, Experimental study, Etude théorique, Theoretical study, Hétérocycle azote, Nitrogen heterocycle, Heterociclo nitrógeno, Méthode Hartree Fock, Hartree-Fock method, Méthode temps vol, Time-of-flight method, Spectre 2 photons, Two-photon spectra, Spectre IR, Infrared spectra, Spectre Raman, Raman spectra, Spectrométrie masse ionisation résonnante, Resonance ionization mass spectroscopy, Indole(«4»-fluoro), Indole(«5»-fluoro), and Indole(«6»-fluoro)

The excitation spectra of 4-, 5-, and 6-fluoroindole have been obtained with jet-cooled one-color resonant two-photon ionization (1 C R2PI) time-of-flight mass spectrometry (TOFMS). The 1C R2PI spectra have been vibronically analyzed in the spectral region of 000 to 000+842 cm-1 in 4-fluoroindole and 000 to 000+∼1100 cm-1 in 5- and 6-fluoroindole. All transitions observed in the 4-, 5-, and 6-fluoroindole excitation spectra are assigned as 1Lb←1A' transitions. Assignments of both ground- and excited-state vibrational modes were based upon those previously assigned for indole.4.9 As with indole, the ground-state vibrational frequencies were also calculated using ab initio methods as well as being obtained from infrared and Raman studies.

General chemistry, physical chemistry, Chimie générale, chimie physique, Metallurgy, welding, Métallurgie, soudage, Atomic molecular physics, Physique atomique et moléculaire, Sciences exactes et technologie, Exact sciences and technology, Physique, Physics, Physique atomique et moleculaire, Atomic and molecular physics, Propriétés moléculaires et interactions avec les photons, Molecular properties and interactions with photons, Propriétés des molécules et des ions moléculaires, Properties of molecules and molecular ions, Constantes rotationnelles, vibrationnelles et rovibrationnelles, Rotation, vibration and vibration-rotation constants, Intensités et profils des raies et bandes moléculaires, Intensities and shapes of molecular spectral lines and bands, Profils et largeurs des raies et des bandes, déplacements spectraux, Line and band widths, shapes, and shifts, Vibronic, rovibronic, and rotation-electron-spin interactions, Composé transfert charge, Charge transfer complexes, Couplage électron électron, Electron-electron coupling, Etat excité, Excited states, Etat vibronique, Vibronic states, Etude théorique, Theoretical study, Hamiltonien, Hamiltonians, Principe Franck Condon, Franck-Condon principle, Profil raie, Line shape, Simulation ordinateur, Computerized simulation, Spectre absorption, Absorption spectra, Transition interdite, and Forbidden transitions

We consider an excited-state manifold in which an allowed transition is strongly coupled electronically to a forbidden (dark) state and use nonperturbative methods to determine the effects of this coupling on the optical properties. We find that the strong coupling limit is qualitatively different from the usual weak coupling case; in particular, the bright state spectrum is substantially altered, displaying renormalized Franck-Condon faction which can be observed in absorption, hole burning, and resonance Raman experiments. We map out the magnitude of this renormalization as a function of various parameters in the theory and note that there is a phase-transition-like behavior as one paues from the weak to the strong coupling regimes.

General chemistry, physical chemistry, Chimie générale, chimie physique, Metallurgy, welding, Métallurgie, soudage, Atomic molecular physics, Physique atomique et moléculaire, Sciences exactes et technologie, Exact sciences and technology, Physique, Physics, Physique atomique et moleculaire, Atomic and molecular physics, Propriétés moléculaires et interactions avec les photons, Molecular properties and interactions with photons, Fluorescence et phosphorescence; transitions non radiatives, extinction (conversion intersystèmes, conversion interne), Fluorescence and phosphorescence; radiationless transitions, quenching (intersystem crossing, internal conversion), Spectres de fluorescence et de phosphorescence, Fluorescence and phosphorescence spectra, Processus de collision et interactions atomiques et moléculaires, Atomic and molecular collision processes and interactions, Diffusion des atomes, molécules et ions, Scattering of atoms, molecules and ions, Transferts d'énergie rotationnelle et vibrationnelle, Rotational and vibrational energy transfer, Composé minéral, Inorganic compounds, Cinétique, Kinetics, Coefficient Einstein, Einstein coefficients, Collision faisceau, Colliding beams, Constante vitesse, Rate constant, Constante velocidad, Diagramme Stern Volmer, Stern Volmer diagram, Diagrama Stern Volmer, Désexcitation, De-excitation, Etat vibrationnel, Vibrational states, Etude expérimentale, Experimental study, Faisceau électron, Electron beams, Ozone, Rayonnement IR proche, Near infrared radiation, Relaxation vibrationnelle, Vibrational relaxation, Relajación vibracional, Relaxation, Spectrométrie fluorescence, and Fluorescence spectroscopy

Collisional relaxation of the coupled ν3, ν1 stretching modes of O3 at 90 K has been investigated by monitoring time and pressure variations of the infrared emission at 9.6 μm. Spectral modeling was utilized to determine the temporal variations in the populations of each vibrational level. A single quantum collisional relaxation model was used to evaluate total decay rates out of each vibrational level in this highly coupled system. Total decay rates at several different pressures were subjected to a Stern-Volmer analysis and have yielded level specific rate coefficients for collisional quenching of 03 with up to three vibrational quanta.

General chemistry, physical chemistry, Chimie générale, chimie physique, Metallurgy, welding, Métallurgie, soudage, Atomic molecular physics, Physique atomique et moléculaire, Sciences exactes et technologie, Exact sciences and technology, Physique, Physics, Physique atomique et moleculaire, Atomic and molecular physics, Processus de collision et interactions atomiques et moléculaires, Atomic and molecular collision processes and interactions, Diffusion des atomes, molécules et ions, Scattering of atoms, molecules and ions, Excitation électronique et ionisation de molécules; états moléculaires intermédiaires (incluant durées de vie, mélange d'états, etc.), Electronic excitation and ionization of molecules; intermediate molecular states (including lifetimes, state mixing, etc.), Carbone sulfure, Carbon sulfides, Carbonyle, Carbonyls, Collision réactive, Reactive collision, Colisión reactiva, Collision électron molécule, Electron-molecule collisions, Composé binaire, Binary compounds, Composé minéral, Inorganic compounds, Composé ternaire, Ternary compounds, Dissociation chimique, Chemical dissociation, Disociación química, Dissociation, Energie dissociation, Dissociation energy, Enthalpie, Enthalpy, Etat excité, Excited states, Etat vibrationnel, Vibrational states, Etude expérimentale, Experimental study, Impact électron, Electron impact, Impacto electrón, Propriété thermodynamique, Thermodynamic properties, Radical libre minéral, Inorganic free radical, Radical libre inorgánico, Rayonnement UV proche, Near ultraviolet radiation, Section efficace, Cross sections, Spectre émission, Emission spectra, Sulfure, Sulfides, C O S, C S, CS2, CS, and OCS

The CS(A1Π-X1Σ+) emission spectra produced by electron impact on CS2 and OCS have been measured from threshold up to 120 eV. Emission cross sections of this band from CS2 and OCS are 10±2 and (0.75±0.15) ×10-18 cm2, respectively, at 100 eV. At low impact energies (below 20 eV), the vibrational state distributions of CS(A1Π, ν'=0-8) measured from CS2 and OCS can be represented by temperatures of 12 500±2000 and 26 000±4000 K, respectively, while the rotational temperature of the ν'=0 level is estimated to be 3850± 400 K from both parents.

General chemistry, physical chemistry, Chimie générale, chimie physique, Metallurgy, welding, Métallurgie, soudage, Atomic molecular physics, Physique atomique et moléculaire, Sciences exactes et technologie, Exact sciences and technology, Physique, Physics, Physique atomique et moleculaire, Atomic and molecular physics, Propriétés moléculaires et interactions avec les photons, Molecular properties and interactions with photons, Propriétés des molécules et des ions moléculaires, Properties of molecules and molecular ions, Constantes rotationnelles, vibrationnelles et rovibrationnelles, Rotation, vibration and vibration-rotation constants, Spectres moléculaires, Molecular spectra, Spectres raman et rayleigh (y compris les phénomènes de diffusion correspondants), Raman and rayleigh spectra (including optical scattering), Chimie, Chemistry, Chimie generale et chimie physique, General and physical chemistry, Solutions, Propriétés des solutions, Solution properties, Raman and Rayleigh spectra (including optical scattering), Vibrational analysis, Composé organique, Organic compounds, Effet isotopique, Isotope effects, Energie potentielle, Potential energy, Etat vibrationnel, Vibrational states, Etude expérimentale, Experimental study, Etude théorique, Theoretical study, Hexadécane, Hexadecane, Hydrocarbure, Hydrocarbons, Hydrogène isotope, Hydrogen isotopes, Isotropie, Isotropy, Mélange binaire, Binary mixtures, Pentane, Simulation ordinateur, Computerized simulation, Spectre Raman, Raman spectra, Deutérium, and Eicosane

The isotropic Raman spectra of the liquid n-alkanes C5H12 through C20H42 along with C16D34 were calculated using a simple intensity model. The calculated spectra closely resemble the observed spectra. Well-defined patterns in the spectra are revealed when the frequencies of the Raman bands are assembled together for the liquids C5-C20. The patterns observed are associated with the existence of band progressions. These resemble the progressions found in the spectra of the all-trans chains in the crystal. The introduction of conformational disorder into an assembly of ordered chains affects the frequencies of the bands much less than the distribution of intensity. A rationale for this behavior is presented.

General chemistry, physical chemistry, Chimie générale, chimie physique, Metallurgy, welding, Métallurgie, soudage, Atomic molecular physics, Physique atomique et moléculaire, Sciences exactes et technologie, Exact sciences and technology, Physique, Physics, Physique atomique et moleculaire, Atomic and molecular physics, Propriétés moléculaires et interactions avec les photons, Molecular properties and interactions with photons, Spectres moléculaires, Molecular spectra, Spectres raman et rayleigh (y compris les phénomènes de diffusion correspondants), Raman and rayleigh spectra (including optical scattering), Raman and Rayleigh spectra (including optical scattering), Composé organique, Organic compounds, Déphasage, Phase shift, Effet concentration, Quantity ratio, Etat vibrationnel, Vibrational states, Etude expérimentale, Experimental study, Fonction corrélation, Correlation functions, Hydrocarbure alicyclique halogéné, Halogenated alicyclic hydrocarbons, Indice extinction, Extinction index, Indice extinción, Isomère géométrique, Geometrical isomer, Isómero geométrico, Moment dipolaire, Dipole moments, Spectre IR, Infrared spectra, Spectre Raman, Raman spectra, Temps corrélation, Correlation time, Transition dipolaire, Dipolar transition, Transición dipolar, Cyclohexane(bromo), Cyclohexane(chloro), and Cyclohexane(iodo)

The Raman and IR spectra of the C-X stretching modes (X=Cl, Br, I) in the axial and the equatorial positions of cyclohexyl halides have been measured at room temperature. The band broadening mechanisms and the differences in the rate of vibrational dephasing of the axial and the equatorial conformers have been discussed. It has been found that intermolecular long-range transition dipole-transition dipole coupling gives the main contribution to the differences in vibrational dephasing rate. This paper demonstrates that a simultaneous study of the vibrational dephasing of different conformers provides a method to isolate the individual relaxation mechanisms.

General chemistry, physical chemistry, Chimie générale, chimie physique, Metallurgy, welding, Métallurgie, soudage, Atomic molecular physics, Physique atomique et moléculaire, Sciences exactes et technologie, Exact sciences and technology, Physique, Physics, Etat condense: structure electronique, proprietes electriques, magnetiques et optiques, Condensed matter: electronic structure, electrical, magnetic, and optical properties, Propriétés optiques, spectroscopie et autres interactions de la matière condensée avec les particules et le rayonnement, Optical properties and condensed-matter spectroscopy and other interactions of matter with particles and radiation, Photoluminescence, Matériaux organiques solides, Solid organic materials, Composé organique, Organic compounds, Cinétique, Kinetics, Constante vitesse, Rate constant, Constante velocidad, Conversion intersystème, Intersystem crossing, Conversión intersistema, Domaine température 0000-0013 K, Temperature range 0000-0013 K, Domaine température 0013-0065 K, Temperature range 0013-0065 K, Déclin luminescence, Luminescence decay, Decadencia luminiscencia, Etat excité, Excited states, Etat vibrationnel, Vibrational states, Etude expérimentale, Experimental study, Haute résolution, High resolution, Alta resolucion, Hydrocarbure, Hydrocarbons, Monocristal, Monocrystals, Phosphorescence, Rayonnement visible, Visible radiation, Stilbène, Stilbene, Triplet, and Triplets

The vibrationally well-resolved phosphorescence spectrum of a trans-stilbene single crystal at 4.2 K is observed for the first time. There is no progression of the ethylenic double-bond torsional mode in the spectrum. This observation shows that there is little geometry change in the twist angle around the central double bond in the phosphorescent triplet state relative to the ground state. The possibility of torsion around C(ethylene)-C(phenyl), rather than C(ethylene)=C(ethylene), is indicated. The intensity distribution over the progression of ethylenic C=C stretching differs very much from that in the SI0-TI1 absorption already reported. The anomaly of the absence of mirror image is attributed to the existence of the next triplet state at about a few thousand wavenumbers higher than the T1 origin.

General chemistry, physical chemistry, Chimie générale, chimie physique, Metallurgy, welding, Métallurgie, soudage, Atomic molecular physics, Physique atomique et moléculaire, Sciences exactes et technologie, Exact sciences and technology, Chimie, Chemistry, Chimie organique, Organic chemistry, Réactivité et mécanismes, Reactivity and mechanisms, Cinétique et mécanisme des réactions, Kinetics and mechanisms, Chaleur formation, Heat of formation, Calor formación, Chaleur réaction, Heat of reaction, Calor reacción, Cinétique, Kinetics, Cinética, Constante vitesse, Rate constant, Constante velocidad, Disilane, Disilano, Dissociation chimique, Chemical dissociation, Disociación química, Décomposition thermique, Thermal decomposition, Descomposición térmica, Effet milieu, Medium effect, Efecto medio, Energie dissociation, Dissociation energy, Energía disociación, Enthalpie, Enthalpy, Entalpía, Entropie, Entropy, Entropía, Etude expérimentale, Experimental study, Estudio experimental, Propriété thermodynamique, Thermodynamic properties, Propiedad termodinámica, Pyrolyse, Pyrolysis, Pirólisis, Radical libre organique, Organic free radical, Radical libre orgánico, Silane organique, Organic silane, Silano orgánico, Température, Temperature, Temperatura, Théorie RRKM, RRKM theory, Teoría RRKM, Disilane(hexaméthyl), and Triméthylsilyle

The thermal unimolecular decomposition of hexamethyldisilane (HMDS), Me3SiSiMe3, has been investigated over the temperature range 893-1248 K by using the technique of very-low-pressure pyrolysis (VLPP). The major primary reaction pathway is the expected Si-Si bond fission to form the trimethylsilyl radical, Me3Si. A minor primary reaction pathway is Si-C bond fission but this accounts for <5% of the HMDS decomposition. RRKM calculations yield the extrapolated high-pressure rate parameters at 1000 K given by the expressions k1,∞=1016.5±03 exp(-314.3±8.0 kJ mol-1/RT) s-1 for Si-Si fission and k6,∞~1017.3 exp(352 kJ mol-1/RT) for Si-C fission.