M. Girasole

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Papers by M. Girasole

Nanoimaging of Nanostructured Metal Rich Ordinary Chondrites at Different Wavelengths

Introduction: Space Weathering (SW) is an ensemble of processes that act on a body exposed to spa... more Introduction: Space Weathering (SW) is an ensemble of processes that act on a body exposed to space environment. One of SW effects is the development and accumulation of iron nanoparticles (npFe) on the asteroid surface. In fact, according the most qualified scenario, npFe are produced by shock-induced phase transformation of Fe-Ni alloys caused by micro-collisions [1]. These npFe are responsible for the reddening in the asteroids, i.e. the increase of IR reflectance with increasing wavelength, observed through infrared remote sensing measures. This reddening is not observed in spectra of Ordinary Chondrites, whose parent bodies are S-type asteroids, and this confirms that the phenomenon is linked to SW.

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Metal rich Ordinary Chondrites: Near Field analysis and comparison with Finite Integration Technique models

Afm, Fe-Sem and Optical Imaging of a Shocked L/LL Chondrite: Implications for Martensite Formation and Wave Propagation

A study of physical properties and gas-surface interaction of vanadium oxide thin films

by M. Girasole and R. Rella

Thin Solid Films, 1999

Thin films of vanadium oxide were prepared by means of r.f. reactive sputtering. Their physical p... more Thin films of vanadium oxide were prepared by means of r.f. reactive sputtering. Their physical properties were studied as a function of the oxygen content in the sputtering atmosphere. Atomic force microscopy (AFM) and X-ray photoelectron spectromicroscopy (XPSM) investigations have been used for the study of the morphology and the chemical composition. In addition electrical characterisation in controlled atmosphere has

Optical super-resolution using higher harmonics and different acquisition modes in an aperture tapping SNOM

physica status solidi (b), 2010

ABSTRACT Scanning near field optical microscopy (SNOM) is a well-established technique to obtain ... more ABSTRACT Scanning near field optical microscopy (SNOM) is a well-established technique to obtain a sub-wavelength resolution optical characterization, together with nanometer-scale topography images, on any kind of biological or non-biological sample. Recently we have modified a classical SNOM unit to work in the tapping modality, ensuring stability, versatility and good optical resolution and signal to noise ratio. Exploiting the vertical tip movement, in particular, we were able to access two different optical detection modes: light modulation, which can be obtained by a mechanical chopper or by electronically switching the laser on and off; gap modulation in which the tip&#39;s vertical oscillation is used to produce, itself, a modulation of the collected light. Several biological and non-biological samples have been investigated and the data reveal that, despite the signal collected in gap-modulation is at least one order of magnitude smaller than in laser-modulation, resolution, and signal-to-noise ratio in the gap-modulated images is preferable. On the other hand, the higher intensity of the laser-modulation signal allows to deconvolve the optical information at higher harmonics of the tip oscillation frequency. This is a well-known procedure used in the apertureless-SNOM setup to enhance the near-field contribution of the scattered light and reduce the noise content. The interesting results obtained in this Aperture setup are described and commented.

Controlled loading of oligodeoxyribonucleotide monolayers onto unoxidized crystalline silicon; fluorescence-based determination of the surface coverage and of the hybridization efficiency; parallel imaging of the process by Atomic Force Microscopy

by M. Girasole and F. Cattaruzza

Nucleic Acids Research, 2006

Unoxidized crystalline silicon, characterized by high purity, high homogeneity, sturdiness and an... more Unoxidized crystalline silicon, characterized by high purity, high homogeneity, sturdiness and an atomically flat surface, offers many advantages for the construction of electronic miniaturized biosensor arrays upon attachment of biomolecules (DNA, proteins or small organic compounds). This allows to study the incidence of molecular interactions through the simultaneous analysis, within a single experiment, of a number of samples containing small quantities of potential targets, in the presence of thousands of variables. A simple, accurate and robust methodology was established and is here presented, for the assembling of DNA sensors on the unoxidized, crystalline Si(100) surface, by loading controlled amounts of a monolayer DNA-probe through a two-step procedure. At first a monolayer of a spacer molecule, such as 10-undecynoic acid, was deposited, under optimized conditions, via controlled cathodic electrografting, then a synthetic DNA-probe was anchored to it, through amidation in aqueous solution. The surface coverage of several DNA-probes and the control of their efficiency in recognizing a complementary target-DNA upon hybridization were evaluated by fluorescence measurements. The whole process was also monitored in parallel by Atomic Force Microscopy (AFM).

format_quoteAchieved a limit of detection of 0.30 nM for fluorescein, enabling detection of ODNs at submonolayer coverage on silicon.format_quote

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Atomic force microscopy observation of human lymphoid cells chronically infected with the human immunodeficiency virus

by A. Cricenti and M. Girasole

Journal of Vacuum Science & Technology A: Vacuum, Surfaces, and Films, 1999

... A. Cricenti,a) R. Generosi, M. Girasole, MA Scarselli, and P. Perfetti Istituto della Struttu... more

Implementation of a bimorph-based aperture tapping-SNOM with an incubator to study the evolution of cultured living cells

Journal of Microscopy, 2008

We present the implementation of a tapping-mode aperture scanning near-field optical microscope (... more We present the implementation of a tapping-mode aperture scanning near-field optical microscope (Tapping-SNOM) to a Binder CB incubator (Istituto di Struttura della Materia, Rome, Italy). The microscope operates in the intermittent contact mode using a nonbent optical fibre allowing to reduce the perturbation exerted on the sample, while the incubator maintains a constant temperature, humidity and CO(2) level. This instrument can maintain and analyse in a controlled environment different samples, both organic and nonorganic. In particular, the Tapping-SNOM can study different cell lines at nanometric resolution and in physiological buffer, following the evolution of the living cells almost indefinitely. We will present several examples of the capabilities of the tapping scanning near-field optical microscope in the study of different lines of living cells, showing corresponding topographical, optical or phase-lag images of the live samples, evidencing the excellent stability, versatility and resolution of the system.

The response of giant phospholipid vesicles to millimeter waves radiation

by M. Girasole, Amerigo Beneduci, and R. Massa

Biochimica et Biophysica Acta (BBA) - Biomembranes, 2009

Due to the increasing interest in millimeter waves (MMW) applications in medicine and telecommuni... more Due to the increasing interest in millimeter waves (MMW) applications in medicine and telecommunications, the investigation of their potential biological effects is of utmost importance. Here we report results of the study of interaction between low-intensity radiation at 53.37 GHz and giant vesicles. Direct optical observations of vesicles subjected to irradiation enabled the monitoring in real time of the response of vesicles. Physical changes of vesicles, i.e. elongation, induced diffusion of fluorescent dye di-8-ANEPPS, and increased attractions between vesicles are demonstrated. These effects are reversible and occur only during irradiation with a "switch on" of the effect requiring a short time. Since the average temperature change was very small the effects could not be attributed to thermal mechanisms. We assume that the interaction of MMW with lipid membrane leads to changes at the membrane-water interface, where charged and dipolar residues are located.

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AFM and SNOM characterization of ordinary chondrites: A contribution to solving the problem of asteroid reddening

by Fabrizia Somma and M. Girasole

physica status solidi (b), 2010

Space weathering (SW) is an ensemble of processes that act on a body exposed to the space environ... more Space weathering (SW) is an ensemble of processes that act on a body exposed to the space environment. Typically, the exposure to SW results in the accumulation, at the surface, of nanoparticles, that are thought to be produced through a vaporization and subsequent cooling of the metallo-silicaceous components exposed to the space environment. The presence of such nanoparticles is responsible for the so-called reddening of the asteroids' reflectance spectra (i.e., the increase in Vis-NIR reflectance with increase in wavelength) observed by remotesensing measurements. To investigate the mechanism of formation of these nanoparticles, we have employed atomic force microscopy (AFM) and scanning near-field optical microscopy (SNOM) to morphologically and optically characterize ordinary chondrites (OC), the most abundant class of meteorites collected on Earth and whose parent bodies are the S-type asteroids. The AFM study reveals the occurrence of a diffuse nanophase (martensite) in the meteorite's metal inclusions. Since the same areas show a reddening of the reflectivity spectra, this suggests that such spectral modification is based on a shock-induced phase transformation of the metal components of the extraterrestrial body. To gain more insight into this nanophase and on its role in the SW of the asteroids, an optical characterization by SNOM has been performed on OCs. In this work we exploited the peculiarity of this technique to search for a correlation between the topography on the nanoscale and the spectral characteristics, at different wavelengths in the red-NIR range, of the observed nanophase. Indeed, a high-resolution mapping of the optical properties of the meteorite provides an interesting method to discriminate between martensite-based and Fe-silicaceous nanoparticles.

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