Browsing Química Física by Issue Date
Now showing items 1-20 of 93
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Competition between tunnel- and viscosity-effects on bimolecular hydrogen-transfer reaction
(International Union of Pure and Applied Chemistry, 1993)The photocyclization of a methylsubstituted diphenylamine results in the formation of a transient zwitterionic dihydrocarbazole. The transient converts into a stable dihydrocarbazole by an intramolecular, sigmatropic ... -
Microemulsións: un avance na obtención de fluídos magnéticos
(Real Academia Galega de Ciencias, 1996)Neste traballo preséntase unha vía alternativa e totalmente orixinal de síntese de nanopartículas para a preparación de fluidos magnéticos, con mellaras respecto ós métodos tradicionais. Para elo, empréganse mezclas ... -
¿Es generalizable la existencia de una transición de primer orden ferromagnética-paramagnética en los materiales con magnetorresistencia colosal R2/3B1/3MnO3 (R=lantanido; B=alcalinoterreo)?
(Real Academia Galega de Ciencias, 1998)En este trabajo se examina la naturaleza de la transición de fase ferromagnética de materiales de manganeso con estructura de perovskita, de gran interés tecnológico por sus enormes variaciones de resistividad eléctrica ... -
I Jornadas Ibéricas de Fotoquímica, VI Congreso de Fotoquímica, 7º Encontro Nacional de Fotoquímica : libro de resúmenes, livro de resumos, Santiago de compostela, España, 18-20 de septiembre de 2003
(Jornadas Ibéricas de Fotoquímica, 2003)En este libro se recogen los resúmenes de las conferencias y comunicaciones que se presentarán en las I Jornadas Ibéricas de Fotoquímica (Santiago de Compostela, 18−20 de septiembre de 2003). Estas Jornadas están organizadas ... -
Host-Guest Complexation Studied by Fluorescence Correlation Spectroscopy: Adamantane–Cyclodextrin Inclusion
(MDPI, 2010)The host-guest complexation between an Alexa 488 labelled adamantane derivative and β-cyclodextrin is studied by Fluorescence Correlation Spectroscopy (FCS). A 1:1 complex stoichiometry and a high association equilibrium ... -
Host-guest complexation studied by fluorescence correlation spectroscopy: adamantane–cyclodextrin inclusion
(MDPI, 2010)The host-guest complexation between an Alexa 488 labelled adamantane derivative and β-cyclodextrin is studied by Fluorescence Correlation Spectroscopy (FCS). A 1:1 complex stoichiometry and a high association equilibrium ... -
Equilibrium constants and protonation site for N-methylbenzenesulfonamides
(Beilstein Institute, 2011)The protonation equilibria of four substituted N-methylbenzenesulfonamides, X-MBS: X = 4-MeO (3a), 4-Me (3b), 4-Cl (3c) and 4-NO2 (3d), in aqueous sulfuric acid were studied at 25 °C by UV–vis spectroscopy. As expected, ... -
Fluorescence of methylated derivatives of hydroxyphenylimidazopyridine. Resolution of strongly overlapping spectra and a new ESIPT dye showing very efficient radiationless deactivation
(Royal Society of Chemistry, 2011)The ground- and excited-state behaviour of the isomeric species 2-(2′-methoxyphenyl)imidazo[4,5-b]pyridine (1-OMe) and 2-(2′-hydroxyphenyl)-4-methylimidazo[4,5-b]pyridine (1-NMe) in neutral and acid media has been studied ... -
The influence of colloidal parameters on the specific power absorption of PAA-coated magnetite nanoparticles
(Springer, 2011)The suitability of magnetic nanoparticles (MNPs) to act as heat nano-sources by application of an alternating magnetic field has recently been studied due to their promising applications in biomedicine. The understanding ... -
Tunneling and Conformational Flexibility Play Critical Roles in the Isomerization Mechanism of Vitamin D
(American Chemical Society, 2011-11-27)The thermal isomerization reaction converting previtamin D to vitamin D is an intramolecular [1,7]-sigmatropic hydrogen shift with antarafacial stereochemistry. We have studied the dynamics of this reaction by means of the ... -
Orbital, charge, and spin couplings in Ru 25+O9 dimers of Ba3CoRu2O9
(APS Physics, 2012)e magnetic, transport, and structural properties of cold-pressed Ba3CoRu2O9 show (i) an antiferromagnetic transition, (ii) a semiconductor-semiconductor electronic transition where the resistivity is dominated by the ... -
Nonmonotonic evolution of the charge gap in ZnV2O4 under pressure
(APS Physics, 2012)A2+V2O4 spinels provide a unique opportunity for studying the evolution of the charge gap of Mott insulators that approach the itinerant electron limit under the application of external pressure. Here we report ... -
A model for monomer and micellar concentrations in surfactant solutions: application to conductivity, NMR, diffusion, and surface tension data
(Elsevier, 2012)An empirical model for the concentrations of monomeric and micellized surfactants in solution is presented as a consistent approach for the quantitative analysis of data obtained with different experimental techniques from ... -
The rainbow instanton method: A new approach to tunneling splitting in polyatomics
(AIP Publishing, 2012-12-11)A new instanton approach is reported to tunneling at zero-temperature in multidimensional (MD) systems in which a “light particle” is transferred between two equivalent “heavy” sites. The method is based on two concepts. ... -
Photoinduced Proton and Charge Transfer in 2‑(2′- Hydroxyphenyl)imidazo[4,5‑b]pyridine
(American Chemical Society, 2013)This paper deals with the interplay between solvent properties and isomerism of 2-(2′-hydroxyphenyl)imidazo[4,5-b]pyridine (1), and the proton and charge-transfer processes that the different isomers undergo in the ... -
Strain-induced enhancement of the thermoelectric power in thin films of hole-doped La2NiO4+δ
(AIP Publishing, 2013)We propose a novel route for optimizing the thermoelectric power of a polaronic conductor, independent of its electronic conductivity. This mechanism is exemplified here in thin-films of La2NiO4+δ. Tensile stress induced ... -
Dissociation of a Strong Acid in Neat Solvents: Diffusion Is Observed after Reversible Proton Ejection Inside the Solvent Shell
(American Chemical Society, 2013)Strong-acid dissociation was studied in alcohols. Optical excitation of the cationic photoacid N-methyl-6-hydroxyquinolinium triggers proton transfer to the solvent, which was probed by spectral reconstruction of picosecond ... -
Low-temperature spin excitations in frustrated ZnCr2O4 probed by high-field thermal conductivity
(APS Physics, 2013)The magnetoelastic excitations of spin frustrated ZnCr2O4 are studied by the magnetic field dependence of the thermal conductivity k down to 50 mK. Above the first-order magnetostructural transition at TN,S≈ 12.5 K, spin ... -
Accurate treatment of two-dimensional non-separable hindered internal rotors
(AIP Publishing, 2013-04-04)This work presents an accurate way for calculating partition functions of strongly coupled hindered rotors in two dimensions. The two-dimensional torsional potential is generated from electronic structure calculations and ... -
Correct Interpretation of How Tunneling Proceeds at Low Temperatures in the Proton Transfer Reactions Involving Thiotropolone: A Comment
(Wiley, 2013-07-05)The correct interpretation is provided of how tunneling proceeds at low temperatures in the proton transfer Reactions (1) and (3) involving thiotropolone and tropolone (see the Arrhenius plots). It is also shown that the ...