20 research outputs found

    Critical factors in quantitative Atomic Force Acoustic Microscopy

    No full text
    Atomic Force Acoustic Microscopy (AFAM) is a scanning probe technique for advanced research in nanomechanical properties, using local elasticity to provide direct and non-destructive mapping of Young's modulus and related surface parameters.In this work, an experimental study is presented, addressing the performance of quantitative AFAM characterization. Different influencing factors are analysed, mainly arising from probe characteristics (such as cantilever geometry, force constant and ultimately resonance frequency) and scan settings (speed and sample vibration frequency). Investigations encompassed a commercial instrument equipped with three different probes, featuring different dimensions and mechanical properties

    Saturable absorption of femtosecond laser pulses at surface plasmon resonance in gold nanoshells

    No full text
    In this work, we present an investigation of the nonlinear optical properties of nanoshells of different size in solutions and deposited on glass substrates using a single beam z-scan method at a wavelength of 806 nm with laser duration of 170 fs. Structural properties of gold nanoshells of about 150 and 220 nm, prepared in water, are characterized by AFM and TEM microscopy. It is found that, in general, they behave as saturable absorbers. The level of saturation depends on the relative overlap between the plasmon resonance of nanoshells and the laser excitation wavelengths. The nonlinear absorption coefficient, obtained by fitting the experimental results, is of the order of -10-11 cmW-1

    Sub-ps pump and probe photoemission from polycrystalline molybdenum

    No full text
    5nonenonePARMIGIANI F.; PELOI M.; BANFI G.; SCHIAVUTA P.; PARMIGIANI F.Parmigiani, Fulvio; Peloi, M.; Banfi, G.; Schiavuta, P.; Parmigiani, F

    Formation of monoclinic <i>hafnium titanate</i> thin films via the sol-gel method

    No full text
    Hafnium titanate films are generating increasing interest because of their potential application as high-k dielectrics materials for the semiconductor industry. We have investigated sol-gel processing as an alternative route to obtain hafnium titanate thin films. Hafnia-titania films of different compositions have been synthesized using HfCl4 and TiCl4 as precursors. The HfO2-TiO2 system composition with 50 mol% of TiO2 and 50 mol% of HfO2 has allowed the formation of a hafnium titanate film after annealing at 1000°C. The films exhibited a homogeneous nanocrystalline structure and a monoclinic hafnium titanate phase that has never been obtained before in thin films. The films resulted in the formation of homogeneously distributed nanocrystals with an average size of 50 nm. Different compositions, with higher or lower hafnia contents, produced anatase crystalline films after annealing at 1000°C

    Thermal drift study on different commercial scanning probe microscopes during the initial warming-up phase

    No full text
    Scanning probe microscopy (SPM) allows surface topography imaging with the highest resolution, as a result of accurate actuation combined with the sharpness of tips. The scanning process is inherently slow and commonly suffers from instrumental drift. Drift evaluation and control is an important issue for quantitative metrology. Drift characterization is essential in order to establish an appropriate method for eliminating, compensating or correcting it, allowing the improvement of measurement quality and accuracy. Drift distortions are often regarded as temperature-dependent phenomena, associated with temperature gradients and transients that may occur both in the single components of the equipment and in the measuring volume. Commercial SPMs are designed and manufactured with different approaches, e. g. combining different scanners' architectures, with selected hardware, software and materials, in order to optimize specific instrument performances such as accuracy and scanning speed. Hence, different SPMs on the market have different drift depending on instrument design and materials. In this work, a set of experiments was conducted on different instruments operating under varying controlled environmental conditions, for drift estimation, with particular reference to the initial warming-up phase. The experimental procedure for drift evaluation was based on repeated measurements on a structured reference grating. Temperature was monitored using an infrared camera. Six different SPMs were compared based on the analysis of the evolution of horizontal and vertical drift over time, allowing correlation of the drift trend with instrument architecture

    Sub-ps pump and probe photoemission from polycrystalline molybdenum

    No full text
    Pump 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
    corecore