130 research outputs found
Shell model and collective high spin states in nuclei: 45,47Ti, 47,49V and 51Mn
No full textSeveral new levels, in particular with high angular momentum, were observed in the odd-A nuclei of the View the MathML source shell 45,47Ti, 47,49V and 51Mn. Several reactions mainly induced by heavy ions were studied: 40Ca(14N, 2pn)51Mn, 50Cr(3He, pn)51Mn, 35Cl(16O, αpn)45Ti, 27Al(24Mg, αpn)45Ti, 44Ca(7Li,p3n)47Ti, 24Mg(32s, α3p)49V, 40Ca(12C, 3p)49V and 24Mg(32S, 2αp)47V with bombarding energies from the Coulomb barrier value up to the maximum corresponding to ≈ 9.5 MV Tandem voltage. Standard techniques of in-beam γ-ray spectroscopy were adopted: γ-ray excitation functions, angular distributions and γ-γ coincidences. Methods of spin assignment are discussed
Photoinduced symmetry-breaking intramolecular charge transfer in a quadrupolar pyridinium derivative
No full textWe report here a joint experimental and theoretical study of a quadrupolar, two-branched pyridinium derivative of interest as a potential non-linear optical material. The spectral and photophysical behaviour of this symmetric system is greatly affected by the polarity of the medium. A very efficient photoinduced intramolecular charge transfer, surprisingly more efficient than in the dipolar asymmetric analogue, is found to occur by femtosecond resolved transient absorption spectroscopy. TD-DFT calculations are in excellent agreement with these experimental findings and predict large charge displacements in the molecular orbitals describing the ground state and the lowest excited singlet state. The theoretical study also revealed that in highly polar media the symmetry of the excited state is broken giving a possible explanation to the fluorescence and transient absorption spectra resembling those of the one-branched analogous compound in the same solvents. The present study may give an important insight into the excited state deactivation mechanism of cationic (donor-π-acceptor-π-donor)(+) quadrupolar compounds characterised by negative solvatochromism, which are expected to show significant two-photon absorption (TPA). Moreover, the water solubility of the investigated quadrupolar system may represent an added value in view of the most promising applications of TPA materials in biology and medicine
Multiple senses of community and acculturation strategies among migrants
No full textBased on the theoretical framework of multiple psychological sense of community (MPSOC) and acculturation models, the study explored the relationships between territorial (TPSOC) and ethnic PSOC (EPSOC) and the acculturation behaviors of 2 groups of immigrants who settled in Italy, namely, Albanians (N = 230) and Sri Lankans (N = 131). Based on survey data and quantitative analyses (general linear models), TPSOC and EPSOC were considered first separately and then combined, according to a bidimensional model of MPSOC that resulted in four combinations (dual membership, receiving society membership, ethnic membership, and no membership). The findings highlighted significant variations across groups. Among Albanian participants, both TPSOC and EPSOC were positively associated with integration and negatively with marginalization. Dual membership was positively associated with integration, prevailing ethnic membership with separation, and no membership with marginalization. Among Sri Lankan participants, EPSOC showed a positive association with separation. Dual membership was associated with marginalization, prevailing receiving society membership with assimilation, prevailing ethnic membership with separation, and no membership with integration
Cosmopolitismo e fedeltà al Principe: appunti e documenti per una biografia di Cosimo Brunetti tra Italia, Francia e Polonia nella seconda metà del XVII secolo
No full textSulla base di nuovi documenti si ricostruisce la biografia di Cosimo Brunetti, viaggiatore cosmopolita fiorentino del XVII secolo, aderente al giansenismo (traduttore di Pascal), corrispondente di scienziati, che si pone senza fortuna al servizio del papa e poi diviene segretario di Giovanni Sobiesk
Three-dimensional network structures based on pyridylcalix[4]arene metal complexes
No full textA new series of supramolecular assemblies is obtained through the interaction of 3-pyridylmethyl-calixarenes and copper or zinc ions. The complexes formed are characterized both in solution and in the solid state. The results offer appealing insights into how the steric crowding of the lower rim and different coordination modes of the metal centers have a great impact on the overall architecture of the complexes with the formation of monomeric, dimeric, or oligomeric/polymeric species
Photoinduced Intramolecular Charge Transfer and Hyperpolarizability Coefficient in Push‐Pull Pyridinium Salts with Increasing Strength of the Acceptor Group
No full textThe synthesis of three push-pull cationic dyes is reported here together with a photophysical study carried out by stationary and ultrafast spectroscopies. The hyperpolarizability (β) values of the three molecules have been estimated through a simple solvatochromic method based on conventional, low-cost equip- ment, which had been tested previously with success in our laboratory. The investigated pyridinium salts showing strong negative solvatochromism bear the same piperidine ring as a strong electron-donor group and the same thiophenes as electron-rich π-linkers, but differ in terms of the N-substituent on the electron-acceptor pyridinium unit, namely N-methyl in compound A, N-pyrimidin-2yl in B and N-2,4-dinitrophenyl in C.
The derived β values were found to increase (in the order A< B < C) along with the increasing electron-acceptor strength of the pyridinium substituent, with the highest polarizability being estimated for the derivative bearing the strongest electron- withdrawing substituent dinitrobenzene. State-of-the-art femto- second transient absorption measurements evidenced fast kinetics and dynamics in the singlet excited state in agreement with charge transfer (CT) processes promoted by excitation, with a proper ICT state observed in the case of C. This finding confirms the efficiency of photoinduced intramolecular CT as a significant factor that affects the NLO response
New Styryl Phenanthroline Derivatives as Model D−π−A−π−D Materials for Non-Linear Optics
No full text- …
