1,720,982 research outputs found
Atomic force acoustic microscopy for quantitative nanomechanical characterization of polymer blends
No full textSub-ps pump and probe photoemission from polycrystalline molybdenum
No full textPump and probe electron photoemission, induced by 150 fs-790 nm laser pulses on polycrystalline molybdenum, is used to investigate the non-linear photoemissive regime. The analysis of these experimental data evidences third and fourth order thermally assisted currents that contribute to the electron yield. In addition, partial yield measurements at very low pulse intensities confirm the above analysis, evidencing a change in the logarithmic slope as predicted by the theory
Saturable Absorption of Femtosecond Laser Pulses at Surface Plasmon Resonance in Gold Nanoshells
No full textFemtosecond nonlinear absorption of gold nanoshells at surface plasmon resonance
No full textThe nonlinear optical absorption of gold nanoshells (Au NSs) of different size, in water, was investigated using open aperture z-scan technique with femtosecond laser pulses at 806 nm. It is found that, in general, NSs behave as saturable absorbers. The level of saturation depends on the Au NSs structure and precisely on the ratio between the core size and shell thickness. The measured values of the nonlinear absorption coefficient show a dependence on both the repetition rate and the pulse energy. An average value of the nonlinear absorption coefficient beta = -4.5 +/- 1.0 x 10(-11) cm W(-1) is obtained from z-scan data of core-shell particles of inner and outer radius 95 and 110 nm, respectively, measured at 20 Hz repetition rate in the energy range 120-300 nJ
Investigation on corrosion morphology and products of ancient tin amalgam mirrors by AFM, SEM–EDS and micro-Raman spectroscopies
No full textThis study detected and investigated the degradation effects and dynamics of the tin amalgam reflective layer of ancient mirrors. The experimental results have been obtained by different spectroscopic techniques: Light Microscopy, Scanning Electron Microscopy with Energy Dispersive X-ray Microanalysis (SEM–EDS), Atomic Force Microscopy (AFM) and μ-Raman Spectroscopy. The latter two were applied for the first time to characterize the amalgam of ancient mirrors. Amalgam alteration products in form of concentric rings with alternate different compositions of tin oxides have been studied on both the amalgam reflective layer inner surface and on its cross-sections. For the first time SEM images of micro-crosssections of different amalgam degradation products, such as amalgam “drops” and craters, have been obtained. The size of the nano-particles of tin oxides, as amalgam degradation products, was estimated around 3–8 nm by AFM and micro-Raman, as already previously detected through TEM. Micro-Raman showed the presence of both cassiterite and romarkite nano-crystals forming the concentric rings, as only previously hypothesized. This investigation allowed to obtain further experimental evidence and a more advanced comprehension about the structure and formation phases
of the amalgam decay products, giving further support to some statements by previous authors and suggesting some assertions different from the ones of previous studies
Highly ordered self-assembled mesostructured hafnia thin films: an example of rewritable mesostructure
No full textFluorophore-doped luminescent silica nanoparticles as efficient labels in DNA microarrays
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