Search results for "resolve"
showing 10 items of 258 documents
Nano-Oxides produced by ns laser ablation in liquids
2014
Laser ablation in liquids was successfully applied to produce nanosized oxides from Si, Ti and Zn targets. The obtained colloidal solutions of nanoparticles were investigated by complementary techniques: AFM, IR and Raman spectroscopies; optical absorption and time resolved photoluminescence. The results demonstrate the production of SiO2, TiO2 and ZnO. The absorption and emission properties of these material have been also investigated and appear to be promising for optical applications.
Mixed complexes of alkaline earth uranyl cabonates: A laser-induced time-resolved fluorescence spectroscopic study
2008
The interaction of the alkaline earth ions Mg2+, Sr2+ and Ba2+ with the uranyl tricarbonate complex has been studied by time resolved laser-induced fluorescence spectroscopy. In contrast to the non-luminescent uranyl tricarbonate complex the formed products show slight luminescence properties. These have been used to determine the stoichiometry and complex stabilities of the formed compounds. As the alkaline earth elements are located in an outer shell of the complex the influence of the type of the alkaline earth element on the stability constant is not very drastic. Therefore all obtained data were averaged in order to derive an common stability constant for the described complexes. These…
Optical magnetic circular dichroism in threshold photoemission from a magnetite thin film
2011
Threshold photoemission excited by polarization-modulated ultraviolet femtosecond laser light is exploited for phase-sensitive detection of magnetic circular dichroism (MCD) for a magnetite thin film. Magnetite (Fe(3)O(4)) shows a magnetic circular dichroism of ∼(4.5 ± 0.3) × 10(-3) for perpendicularly incident circularly polarized light and a magnetization vector switched parallel and antiparallel to the helicity vector by an external magnetic field. The asymmetry in threshold photoemission is discussed in comparison to the magneto-optical Kerr effect. The optical MCD contrast in threshold photoemission will provide a basis for future laboratory photoemission studies on magnetic surfaces.
Structural and luminescence properties of amorphous SiO2 nanoparticles
2011
We report an experimental study on the photoluminescence band peaked at 2.7 eV (blue band) induced by thermal treatments in nanometric amorphous SiO 2. In particular the emission dependence on the nanometric particles size as a function of their mean diameter from 7 nm up to 40 nm is investigated. We found that the emission amplitude increases on decreasing the particle diameter, showing a strong correlation between the blue band and the nanometric nature of the particles. By Raman spectroscopy measurements it is evidenced that the SiO2 nanoparticles matrix is significantly affected by the reduction of size. Basing on the shell-like model, these findings are interpreted assuming that the de…
Wide range excitation of visible luminescence in nanosilica
2010
The visible luminescence of nanometer-sized silica particles (7 nm mean diameter) was investigated using time resolved spectroscopy. This luminescence is characterized by a wide excitation in the visible and ultraviolet range. The emission spectrum is centred at 2.72 eV with a full width at half maximum of 0.70 eV when excited above 3.5 eV, whereas it progressively empties on the high energy side when excited below 3.5 eV. Moreover, the lifetime falls in the ns timescale and decreases on increasing the emission energy. These features are due to the exceptionally broad inhomogeneous distribution of the emitting centres peculiar to the silica nanoparticles. © 2010 Elsevier B.V. All rights res…
High-Resolution Spectroscopy in Fast Atomic Beams
1977
Narrow optical resonances have been observed in fast beams of Na and Cs atoms, obtained from ion beams by charge-transfer collisions with Na, K, or Cs. Corresponding to the narrowing of the velocity distribution, occurring by acceleration, the Doppler width along the beam direction is considerably reduced [1, 2].
Study of the defects in La3Ta0.5Ga5.5O14 single crystals
2016
Abstract Defects that are formed during crystal growth pose a serious obstacle for potential application of La 3 Ga 5.5 Ta 0.5 O 14 (LGT) as a laser or piezoelectric crystal. We have performed the study of the defects origin in LGT crystals grown in different atmospheres using optical, EPR and time-resolved luminescence characterization methods. The absorption bands detected in the transparency region at 290, 360 and 490 nm ( T =300 K) demonstrate different dependence on crystal annealing in vacuum and air. EPR analysis demonstrated that the defects responsible for these bands are non-paramagnetic. X-ray irradiation results in hole trapping by oxygen ions thus forming O − centers perturbed …
Observation of quantized subband states and evidence for surface electron accumulation in CdO from angle-resolved photoemission spectroscopy
2008
The electronic structure of well-ordered single-crystal thin films of CdO100 has been studied using angleresolved photoemission spectroscopy. Quantized electron subbands are observed above the valence-band maximum. The existence of these states provides evidence of an intrinsic electron accumulation space-charge layer near the CdO surface, an interpretation supported by coupled Poisson-Schrodinger calculations. The origin of the accumulation layer result is discussed in terms of the bulk band structure of CdO calculated using quasiparticle-corrected density-functional theory, which reveals that the conduction-band minimum at the Brillouin-zone center lies below the charge neutrality level.
Magnetic dichroism in photoemission with unpolarized light.
1994
A magnetic dichroism in photoemission from ferromagnets induced by unpolarized light is observed for the first time in the valence band region as well as for surface states. The study was carried out with magnetized Fe(110), Co(0001), and Gd(0001) films grown epitaxially on W(110). This phenomenon leads to an intensity asymmetry for opposite directions of the sample magnetization. It can be easily used for a routine laboratory diagnostic of magnetic behavior. A simple theoretical interpretation of the phenomenon based on the atomic model is given.
Formation and Growth of Pd Nanoparticles Inside a Highly Cross-Linked Polystyrene Support: Role of the Reducing Agent
2014
Simultaneous time-resolved SAXS and XANES techniques were employed to follow in situ the formation of Pd nanoparticles in a porous polystyrene support, using palladium acetate as a precursor and gaseous H2 or CO as reducing agents. These results, in conjunction with data obtained by diffuse reflectance UV–vis and DRIFT spectroscopy and TEM measurements, allowed unraveling of the different roles played by gaseous H2 and CO in the formation of the Pd nanoparticles. In particular, it was found that the reducing agent affects (i) the reduction rate (which is faster in the presence of CO) and (ii) the properties of the hosted nanoparticles, in terms of size (bigger with CO), morphology (spherica…