2,670 research outputs found
Il "mestiere" di musicista. Breve profilo musicale di Luigi Pasimeni
No full textL'articolo ha inteso trattare un profilo del musicista mesagnese Luigi Pasimeni (1909-2004) e si inserisce in una pubblicazione di storia locale. Il contributo analizza alcune composizioni del musicista, riportate all'interno, e le inquadra nel contesto storico-culturale del territorio pugliese, in particolare salentino, degli anni '50-'90. Esso altresì riflette sul rapporto tra musica colta, soprattutto d'àmbito sacro e religioso e musica popolare, che si coniugano nella formazione e nell'opera del musicista considerato
Experimental evaluation of the electron-intramolecular-vibration coupling constants of tetramethyltetrathiafulvalene
No full textThe relevant electron-intramolecular vibrations coupling constants of tetramethyltetrathiafulvalene (TMTTF) have been experimentally obtained. The determination was possible studying the optical properties of dimers of TMTTF(+) in polymethyl-methacrylate films on the basis of a Holstein-Hubbard dimer model. Electron paramagnetic resonance measurements of the singlet-triplet energy gap of the dimers made possible the calculation of the coupling constants without the need for absolute values of the optical spectra and the knowledge of structural parameters. The values of the coupling constants show differences with previously reported values for TMTTF or related molecules like TTF and bis-ethylenedithio-TTF (BEDT-TTF)
ESR Investigation of Mn Carbonyl Complexes Formed by Reaction of Mn2(CO)10 with Electron Acceptor Molecules.
No full textTransient EPR emission spectra of a free radical trapped in a single crystal of chloranil
No full textThe EPR spectrum of a free radical trapped in single crystals of chloranil changes its phase from absorption to emission when the crystal is illuminated by visible light. The time evolution of the EPR signal is discussed in terms of the interaction between the doublet species and triplet excitons produced by light excitation
Structural and spectroscopic characterization of Cu(II) [tetrakis-(3,3-dimethyl-l-butoxycarbonyl)] phthalocyanine thin films deposited by the Langmuir—Blodgett technique
No full textLangmuir-Blodgett (LB) films of Cu(II) [tetrakis(3,3-dimethyl-1-butoxycarbonyl)] phthalocyanine were prepared and characterized by X-ray diffraction, and polarized UV-Vis and electron paramagnetic resonance (EPR) spectroscopies. It was found that the phthalocyanine molecules deposited on quartz and polyethylene terephthalate (pet) are arranged edge-on on the substrate with the normal to the molecular plane that lies close to the plane of the film. Polarized W-Vis spectra of films show in-plane anisotropy in the orientation of molecules for LB films deposited on quartz and on pet. EPR spectra also, assigned to CU2+ interacting species, were detected for the LB films deposited on pet. The spectra show a marked in-plane anisotropy of the Zeeman interaction when the magnetic field lies in the support plane. The analysis of their angular dependence confirms that the plane of the phthalocyanine molecule is almost perpendicular to the film plane and gives evidence that the in-plane orientation anisotropy arises from two different distributions of orientations pinned around two average orientations having an angle of 68 degrees between them
EPR Study of the Triplet Excitons in a Single Crystal of DDQ Tetraethylammonium Ion Radical Salt.
No full textDelayed Fluorescence - ODMR spectra of the t-stilbene-(TCNB)2 crystal
No full textThe intensity of the delayed fluorescence (DF) - ODMR spectra of the t-stilbene (TSB) - 1,2,4,5-tetracyanobenzene 1:2 crystal has been studied as a function of frequency nu_M of the amplitude modulation acting on the resonant microwave field over a wide range of nu_M values (1 KHz - 1 MHz). At high values of nu_M (> 100 KHz) the change in the DF yield is due to the microwave transitions induced between annihilating triplet pair substates. Under such conditions the ODMR linewidth gives a measure of the triplet-triplet pair lifetime
FLUORESCENCE LIFETIMES IN THE BIPHENYL-TETRACYANOBENZENE CRYSTAL DOPED WITH TCNQ
No full textTransient optical emission spectra of biphenyl-1,2,4,5-tetracyanobenzene crystal doped with TCNQ have been investigated in the (77-300)K temperature range. Host prompt fluorescence lifetimes have been measured by cross-correlation phase fluorometry. The decay signal is fitted by a biexponential function whose coefficients are strongly dependent on temperature. A thermal activation energy of 300 cm-1 for the diffusion of singlet exciton has been determined
EPR study of in-plane anisotropy in the LB films of a Cu(II)[tetra alkoxy carbonyl] phthalocyanine deposited on mylar sheets
No full textElectron paramagnetic resonance spectroscopy has been applied to obtain information on the in-plane anisotropy of Cu(II) [tetrakis-(3,3-dimethyl-1-butoxy carbonyl)] phthalocyanine (CuPcBC) molecules deposited as a Langmuir-Blodgett film on a biaxially oriented mylar substrate. We have found that the in-plane distribution of orientations of the film molecules depends on the angle between the asis of preferential order identified in the substrate and the dipping direction. The in-plane orientational anisotropy of the material in the film is mainly due to the ability of the substrate to induce oriented growth of CuPcBC molecules which reflects its surface order
Isotropic and anisotropic chlorine hyperfine coupling of dichloro-dicyano benzoquinone anion radical
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