Search results for "temi"
showing 10 items of 3194 documents
L'Area Metropolitana di Madrid
2008
Optical absorption and electron paramagnetic resonance of the E’_alfa center in amorphous silicon dioxide
2008
We report a combined study by optical absorption OA and electron paramagnetic resonance EPR spectroscopy on the E point defect in amorphous silicon dioxide a-SiO2. This defect has been studied in -ray irradiated and thermally treated oxygen-deficient a-SiO2 materials. Our results have pointed out that the E center is responsible for an OA Gaussian band peaked at 5.8 eV and having a full width at half maximum of 0.6 eV. The estimated oscillator strength of the related electronic transition is 0.14. Furthermore, we have found that this OA band is quite similar to that of the E center induced in the same materials, indicating that the related electronic transitions involve states highly locali…
Optical absorption band at 5.8 eV associated with the E’_gamma centers in amorphous silicon dioxide: Optical absorption and EPR measurements
2008
Line shape modifications induced by thermal treatment in the optical absorption and electron paramagnetic resonance EPR signals associated with the E center are experimentally investigated in various types of -irradiated amorphous silicon dioxide a-SiO2. The g values of the EPR main resonance line of the E center show a shift correlated with the peak energy variation of the absorption band at about 5.8 eV associated with this defect. These spectroscopic changes are proposed to originate from structural modifications of the defect environment. The correlation is theoretically explained considering that the spin-orbit interaction couples the g-tensor’s elements and the electronic energy level…
Role of H2O in the thermal annealing of the E’_gamma center in amorphous silicon dioxide
2009
Generazione di ietogrammi sintetici per l’analisi di frequenza degli allagamenti in ambiente urbano
2011
Psicologia di comunità e sistemi di reciprocità: soluzioni "inusuali" per fronteggiare la crisi
2014
Qanāts and historical irrigated landscapes in Palermo’s suburban area (Sicily)
2020
La città di Palermo e la sua valle circostante sono un importante paesaggio storico irriguo, caratterizzato da strutture idrauliche sotterranee e da una lunga tradizione di sistemi di irrigazione ereditati dalla presenza islamica in Sicilia nel medioevo (IX-XI secolo). La “rivo- luzione verde” islamica ha radicalmente innovato i sistemi di irrigazione siciliani e questo portò all’introduzione e alla diffusione di nuove specie coltivate. Nell’area suburbana di Pa- lermo sono stati indagati 63 infrastrutture idrauliche e tunnel di scolo, classificati in 4 ca- tegorie: 1) qanāts; 2) qanāts ciechi; 3) pozzi collegati; 4) gallerie di scolo emergenti. Que- ste strutture, nonostante alcuni dubbi c…