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Start Over Author "Lettieri, S." Journal applied physics letters
15 results on '"Lettieri, S."'

5. Unconventional ratiometric-enhanced optical sensing of oxygen by mixed-phase TiO2.

Author

Lettieri, S., Pallotti, D. K., Gesuele, F., and Maddalena, P.

Subjects
*TITANIUM dioxide, *OXYGEN, *OPTICAL sensors, *RATIOMETERS (Electric meters), *PHOTOLUMINESCENCE
Abstract

We show that mixed-phase titanium dioxide (TiO2) can be effectively employed as an unconventional, inorganic, dual-emitting, and ratiometric optical sensor of O2. Simultaneous availability of rutile and anatase TiO2 photoluminescence (PL) and their peculiar "anti-correlated" PL responses to O2 allow using their ratio as a measurement parameter associated with the O2 concentration, leading to an experimental responsivity being by construction larger than the one obtainable for single-phase PL detection. A proof of this concept is given, showing a two-fold enhancement of the optical responsivity provided by the ratiometric approach. Besides the peculiar ratiometricenhanced responsivity, other characteristics of mixed phase TiO2 can be envisaged as favorable for O2 optical probing, namely (a) low production costs, (b) absence of heterogeneous components, and (c) self-supporting properties. These characteristics encourage experimenting with its use for applications requiring high indicator quantities at a competitive price, possibly also tackling the need to develop supporting matrixes that carry the luminescent probes and avoiding issues related to the use of different components for ratiometric sensing. [ABSTRACT FROM AUTHOR]

Published
2016
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6. Unconventional ratiometric-enhanced optical sensing of oxygen by mixed-phase TiO2.

Author

Lettieri, S., Pallotti, D. K., Gesuele, F., and Maddalena, P.

Subjects
TITANIUM dioxide, OXYGEN, OPTICAL sensors, RATIOMETERS (Electric meters), PHOTOLUMINESCENCE
Abstract

We show that mixed-phase titanium dioxide (TiO2) can be effectively employed as an unconventional, inorganic, dual-emitting, and ratiometric optical sensor of O2. Simultaneous availability of rutile and anatase TiO2 photoluminescence (PL) and their peculiar "anti-correlated" PL responses to O2 allow using their ratio as a measurement parameter associated with the O2 concentration, leading to an experimental responsivity being by construction larger than the one obtainable for single-phase PL detection. A proof of this concept is given, showing a two-fold enhancement of the optical responsivity provided by the ratiometric approach. Besides the peculiar ratiometricenhanced responsivity, other characteristics of mixed phase TiO2 can be envisaged as favorable for O2 optical probing, namely (a) low production costs, (b) absence of heterogeneous components, and (c) self-supporting properties. These characteristics encourage experimenting with its use for applications requiring high indicator quantities at a competitive price, possibly also tackling the need to develop supporting matrixes that carry the luminescent probes and avoiding issues related to the use of different components for ratiometric sensing. [ABSTRACT FROM AUTHOR]

Published
2016
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12. Second-harmonic generation in hydrogenated amorphous-Si1-xNx doubly resonant microcavities with periodic dielectric mirrors.

Author

Lettieri, S., Gesuele, F., Maddalena, P., Liscidini, M., Andreani, L. C., Ricciardi, C., Ballarini, V., and Giorgis, F.

Subjects
*DIELECTRICS, *RESONANCE, *INTERFACES (Physical sciences), *WAVELENGTHS, *ANGLE of attack (Aerodynamics), *SILICON nitride
Abstract

We report on the realization of microcavities made of hydrogenated amorphous-Si1-xNx multilayers, with dual-wavelength periodic dielectric mirrors in order to obtain first and second order stop bands. Optical second-harmonic generation with simultaneous resonance for the pump and harmonic waves is demonstrated at finite values of the angle of incidence. The results are in good agreement with a theoretical calculation of the harmonic generation process based on a nonlinear polarization localized at the interfaces between different amorphous layers. [ABSTRACT FROM AUTHOR]

Published
2005
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13. Second-harmonic generation in amorphous silicon nitride microcavities

Author

Stefano Lettieri, S. Di Finizio, P. Maddalena, Fabrizio Giorgis, V. Ballarini, Lettieri, S., DI FINIZIO, S., Maddalena, Pasqualino, Ballarini, V., and Giorgis, F.

Subjects
Materials science, Physics and Astronomy (miscellaneous), business.industry, Physics::Optics, Second-harmonic generation, Polarization (waves), Amorphous solid, Wavelength, Light intensity, Density of states, Optoelectronics, Photonics, business, Order of magnitude
Abstract

We report an experimental observation of optical second-harmonic generation in an amorphous silicon–nitride based planar microcavity. The spectral dependence of the second-harmonic signal is investigated as a function of both wavelength and polarization state of the fundamental beam. The second-harmonic signal is enhanced by two orders of magnitude at the Fabry–Perot resonance. We ascribe the origin of the optical nonlinearity to surface second-harmonic generation occurring at the interfaces of the multilayered structure, where the resonant enhancement is due to the high intracavity fundamental light intensity and to the increase of the photonic density of states. Analysis of polarization dependence shows that interfacial second-order nonlinearity results from a distribution of dipoles directed perpendicularly to the plane of the film and distributed accordingly to an ∞mm point group symmetry.

Published
2002
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14. Ferromagnetism and ferroelectricity in epitaxial BiMnO3 ultra-thin films

Author

Marco Salluzzo, Stefano Lettieri, G. M. De Luca, Daniele Preziosi, R. Di Capua, F. Chiarella, Stefano Gariglio, DE LUCA, GABRIELLA MARIA, Preziosi, D., Chiarella, F., DI CAPUA, Roberto, Gariglio, S., Lettieri, S., and Salluzzo, M.

Subjects
Materials science, Physics and Astronomy (miscellaneous), Ferromagnetic material properties, Condensed matter physics, Mineralogy, ddc:500.2, 02 engineering and technology, Sputter deposition, Island growth, 021001 nanoscience & nanotechnology, 01 natural sciences, Ferroelectricity, Ferroelectricity, ferromagnetism, strained films, piezo force microscopy, Ferromagnetism, Sputtering, 0103 physical sciences, Multiferroics, Thin film, 010306 general physics, 0210 nano-technology
Abstract

We studied the ferroelectric and ferromagnetic properties of compressive strained and unstrained BiMnO3 thin films grown by rf-magnetron sputtering. BiMnO3 samples exhibit a two-dimensional cube-on-cube growth mode and a pseudo-cubic structure up to a thickness of 15 nm and of 25 nm when deposited on (001) SrTiO3 and (110) DyScO3, respectively. Above these thicknesses, we observe a switching to a three-dimensional island growth mode and a simultaneous structural change to a (00l) oriented monoclinic unit cell. While ferromagnetism is observed below a T-C approximate to 100K for all samples, signatures of room temperature ferroelectricity were found only in the pseudo-cubic ultra-thin films, indicating a correlation between electronic and structural orders.

Published
2013
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15. Highly sensitive optochemical gas detection by luminescent marine diatoms

Author

L. De Stefano, Stefano Lettieri, P. Maddalena, Antonio Setaro, Setaro, Antonio, Lettieri, S, DE STEFANO, L, and Maddalena, Pasqualino

Subjects
chemistry.chemical_classification, Langmuir, Photoluminescence, FRUSTULES, Physics and Astronomy (miscellaneous), Chemistry, OXIDE, Photochemistry, Methane, chemistry.chemical_compound, Adsorption, GOLD NANOSTRUCTURES, PHOTOLUMINESCENCE, Compounds of carbon, Nitrogen dioxide, Porosity, Carbon monoxide
Abstract

The modifications of photoluminescence properties of silica frustules of different marine diatoms induced by adsorption of nitrogen dioxide, methane, and carbon monoxide are reported. Different species of diatoms were found to exhibit different relative responses and different gas concentration ranges of sensitivity, depending on the morphology and porosity of their frustules. The photoluminescence quenching shows surface signature, exhibiting a coverage-limited kinetics according to a Langmuir mechanism. Due to the large variety of dimensions, porosities, and surface morphologies available in nature, these materials appear to be promising to improve the selectivity of gas sensing based on photoluminescence optochemical transduction. (c) 2007 American Institute of Physics.

Published
2007
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