ABSTRACT The authors demonstrate direct electron-beam writing on conjugated polymers as patternin... more ABSTRACT The authors demonstrate direct electron-beam writing on conjugated polymers as patterning route to realize plastic optoelectronic devices. Lithography was carried out by a 20 kV electron beam dose in the range of 0-360 muC/cm2, with no need for masking or development/etching processes. The features could be employed for the fabrication of polymer distributed feedback lasers, exhibiting optically pumped lasing in the range of 607-620 nm, with a spectral linewidth around 1 nm and a threshold excitation fluence of 34 muJ/cm2.
Semiconducting conjugated polymers are attractive ma-terials for applications in optoelectronic d... more Semiconducting conjugated polymers are attractive ma-terials for applications in optoelectronic devices, including polymer light-emitting diodes,1 photodetectors,2 photovoltaic cells,3 full-color displays,4 and field-effect transistors.5 In ad-dition, they present interesting ...
A straightforward, electron-beam induced synthesis and patterning approach to the in situ generat... more A straightforward, electron-beam induced synthesis and patterning approach to the in situ generation of CdS nanocrystals in nanocomposite films and light-emitting electrospun nanofibers is used. Smartly combining room-temperature nanoimprinting, electrospinning, and electron-beam decomposition of nanocrystal precursors and subsequent nucleation of nanoparticles in a polymer matrix allows exploitation of the most favorable flow conditions of organics to produce various nanocomposite nanostructures.
ABSTRACT We report on the unique emission features of light-emitting fibers made of a prototype c... more ABSTRACT We report on the unique emission features of light-emitting fibers made of a prototype conjugated polymer, namely, poly[(9,9-dioctylfluorenyl-2,7-diyl)-co-(1,4-benzo-{2,1′-3}-thiadiazole)] (F8BT), realized by electrospinning with diameters in the range of 500-1000 nm. The fibers display emission polarized along their axis, evidencing a favoured alignment of the polymer molecules. Emission efficiency and time resolved measurements reveal an enhancement of both the quantum efficiency and the radiative rate (up to 22.5%) of the fibers compared to spin-coated films, shedding more light on their potential as miniaturized photon sources in optoelectronic devices requiring high recombination rates.
We have applied pulsed laser deposition (PLD) to fabricate YBCO/YSZ films (short length) onto bia... more We have applied pulsed laser deposition (PLD) to fabricate YBCO/YSZ films (short length) onto biaxially textured NiFe substrates. Macroscopic characterization of the samples has been carried out by electrical measurements, XRD patterns and pole figures. Our best films are characterized by Tcs around 89 K and transition widths around 5-6 K. Bragg-Brentano spectra and pole figures acquired on the {111} peak for YSZ and {013} for YBCO show the achievement of the correct crystalline structure and stoichiometry both in YSZ and in YBCO layers. They are largely in-plane textured (respectively (001) for YSZ and (001) for YBCO), and the superconducting YBCO layer exhibits a relatively low mosaicity. Atomic-force microscopy (AFM) analysis confirmed the presence of large grains (1-2 mum typical dimensions), and the occurrence of a complex morphology in the YBCO layer.
The use of UV light sources is highly relevant in many fields of science, being directly related ... more The use of UV light sources is highly relevant in many fields of science, being directly related to all those detection and diagnosis procedures that are based on fluorescence spectroscopy. Depending on the specific application, UV light-emitting materials are desired to feature a number of opto-mechanical properties, including brightness, optical gain for being used in laser devices, flexibility to conform with different lab-on-chip architectures, and tailorable wettability to control and minimize their interaction with ambient humidity and fluids. In this work, we introduce multifunctional, UV-emitting electrospun fibers with both optical gain and greatly enhanced anisotropic hydrophobicity compared to films. Fibers are described by the onset of a composite wetting state, and their arrangement in uniaxial arrays further favors liquid directional control. The low gain threshold, optical losses, plastic nature, flexibility, and stability of these UV-emitting fibers make them interes...
In metal-enhanced fluorescence (MEF), the localized surface plasmon resonances of metallic nanost... more In metal-enhanced fluorescence (MEF), the localized surface plasmon resonances of metallic nanostructures amplify the absorption of excitation light and assist in radiating the consequent fluorescence of nearby molecules to the far-field. This effect is at the base of various technologies that have strong impact on fields such as optics, medical diagnostics, and biotechnology. Among possible emission bands, those in the near-infrared (NIR) are particularly intriguing and widely used in proteomics and genomics due to its noninvasive character for biomolecules, living cells, and tissues, which greatly motivates the development of effective and, eventually, multifunctional NIR-MEF platforms. Here, we demonstrate NIR-MEF substrates based on Au nanocages micropatterned with a tight spatial control. The dependence of the fluorescence enhancement on the distance between the nanocage and the radiating dipoles is investigated experimentally and modeled by taking into account the local electr...
The experimental set-up exploits a pyramidal funnel, made of two prisms and two mirrors arranged ... more The experimental set-up exploits a pyramidal funnel, made of two prisms and two mirrors arranged in the shape of an inverted pyramid with a small hole (1 mm × 2 mm) at its apex, mounted on a stainless-steel holder inside an ultra high vacuum system. The light for manipulating cesium atoms is produced by diode lasers operating around 850 nm, mounted in the external cavity configuration. The quadrupolar magnetic field for the pyramidal-MOT operation is produced by two coils in anti-Helmholtz configuration. The atomic beam leaving the funnel is characterized, i.e., its density, divergence, longitudinal velocity and temperature are measured. Induced fluorescence images, acquired using a CCD camera, and absorption measurements show a beam divergence of 25 mrad, a longitudinal velocity in the range 10-15 m/s (depending on the trapping parameters) and a flux up to 4 × 109 atoms/s. The atomic beam diameter (FWHM) is 1 cm measured 30 cm downward the funnel apex. The deposition of cesium through a light mask on several kinds of substrates is then performed.
EQEC '05. European Quantum Electronics Conference, 2005., 2005
The work aims to develop an atom lithography apparatus by exploiting cold atoms, differently from... more The work aims to develop an atom lithography apparatus by exploiting cold atoms, differently from conventional implementations where thermal atomic sources are used. The cold atomic beam of the apparatus is produced continuously out of a pyramidal magnetooptical trap (MOT) for cesium atoms, a specific configuration of mirrors mounted as the inner part of a hollow pyramid, with a small
ABSTRACT The authors demonstrate direct electron-beam writing on conjugated polymers as patternin... more ABSTRACT The authors demonstrate direct electron-beam writing on conjugated polymers as patterning route to realize plastic optoelectronic devices. Lithography was carried out by a 20 kV electron beam dose in the range of 0-360 muC/cm2, with no need for masking or development/etching processes. The features could be employed for the fabrication of polymer distributed feedback lasers, exhibiting optically pumped lasing in the range of 607-620 nm, with a spectral linewidth around 1 nm and a threshold excitation fluence of 34 muJ/cm2.
Semiconducting conjugated polymers are attractive ma-terials for applications in optoelectronic d... more Semiconducting conjugated polymers are attractive ma-terials for applications in optoelectronic devices, including polymer light-emitting diodes,1 photodetectors,2 photovoltaic cells,3 full-color displays,4 and field-effect transistors.5 In ad-dition, they present interesting ...
A straightforward, electron-beam induced synthesis and patterning approach to the in situ generat... more A straightforward, electron-beam induced synthesis and patterning approach to the in situ generation of CdS nanocrystals in nanocomposite films and light-emitting electrospun nanofibers is used. Smartly combining room-temperature nanoimprinting, electrospinning, and electron-beam decomposition of nanocrystal precursors and subsequent nucleation of nanoparticles in a polymer matrix allows exploitation of the most favorable flow conditions of organics to produce various nanocomposite nanostructures.
ABSTRACT We report on the unique emission features of light-emitting fibers made of a prototype c... more ABSTRACT We report on the unique emission features of light-emitting fibers made of a prototype conjugated polymer, namely, poly[(9,9-dioctylfluorenyl-2,7-diyl)-co-(1,4-benzo-{2,1′-3}-thiadiazole)] (F8BT), realized by electrospinning with diameters in the range of 500-1000 nm. The fibers display emission polarized along their axis, evidencing a favoured alignment of the polymer molecules. Emission efficiency and time resolved measurements reveal an enhancement of both the quantum efficiency and the radiative rate (up to 22.5%) of the fibers compared to spin-coated films, shedding more light on their potential as miniaturized photon sources in optoelectronic devices requiring high recombination rates.
We have applied pulsed laser deposition (PLD) to fabricate YBCO/YSZ films (short length) onto bia... more We have applied pulsed laser deposition (PLD) to fabricate YBCO/YSZ films (short length) onto biaxially textured NiFe substrates. Macroscopic characterization of the samples has been carried out by electrical measurements, XRD patterns and pole figures. Our best films are characterized by Tcs around 89 K and transition widths around 5-6 K. Bragg-Brentano spectra and pole figures acquired on the {111} peak for YSZ and {013} for YBCO show the achievement of the correct crystalline structure and stoichiometry both in YSZ and in YBCO layers. They are largely in-plane textured (respectively (001) for YSZ and (001) for YBCO), and the superconducting YBCO layer exhibits a relatively low mosaicity. Atomic-force microscopy (AFM) analysis confirmed the presence of large grains (1-2 mum typical dimensions), and the occurrence of a complex morphology in the YBCO layer.
The use of UV light sources is highly relevant in many fields of science, being directly related ... more The use of UV light sources is highly relevant in many fields of science, being directly related to all those detection and diagnosis procedures that are based on fluorescence spectroscopy. Depending on the specific application, UV light-emitting materials are desired to feature a number of opto-mechanical properties, including brightness, optical gain for being used in laser devices, flexibility to conform with different lab-on-chip architectures, and tailorable wettability to control and minimize their interaction with ambient humidity and fluids. In this work, we introduce multifunctional, UV-emitting electrospun fibers with both optical gain and greatly enhanced anisotropic hydrophobicity compared to films. Fibers are described by the onset of a composite wetting state, and their arrangement in uniaxial arrays further favors liquid directional control. The low gain threshold, optical losses, plastic nature, flexibility, and stability of these UV-emitting fibers make them interes...
In metal-enhanced fluorescence (MEF), the localized surface plasmon resonances of metallic nanost... more In metal-enhanced fluorescence (MEF), the localized surface plasmon resonances of metallic nanostructures amplify the absorption of excitation light and assist in radiating the consequent fluorescence of nearby molecules to the far-field. This effect is at the base of various technologies that have strong impact on fields such as optics, medical diagnostics, and biotechnology. Among possible emission bands, those in the near-infrared (NIR) are particularly intriguing and widely used in proteomics and genomics due to its noninvasive character for biomolecules, living cells, and tissues, which greatly motivates the development of effective and, eventually, multifunctional NIR-MEF platforms. Here, we demonstrate NIR-MEF substrates based on Au nanocages micropatterned with a tight spatial control. The dependence of the fluorescence enhancement on the distance between the nanocage and the radiating dipoles is investigated experimentally and modeled by taking into account the local electr...
The experimental set-up exploits a pyramidal funnel, made of two prisms and two mirrors arranged ... more The experimental set-up exploits a pyramidal funnel, made of two prisms and two mirrors arranged in the shape of an inverted pyramid with a small hole (1 mm × 2 mm) at its apex, mounted on a stainless-steel holder inside an ultra high vacuum system. The light for manipulating cesium atoms is produced by diode lasers operating around 850 nm, mounted in the external cavity configuration. The quadrupolar magnetic field for the pyramidal-MOT operation is produced by two coils in anti-Helmholtz configuration. The atomic beam leaving the funnel is characterized, i.e., its density, divergence, longitudinal velocity and temperature are measured. Induced fluorescence images, acquired using a CCD camera, and absorption measurements show a beam divergence of 25 mrad, a longitudinal velocity in the range 10-15 m/s (depending on the trapping parameters) and a flux up to 4 × 109 atoms/s. The atomic beam diameter (FWHM) is 1 cm measured 30 cm downward the funnel apex. The deposition of cesium through a light mask on several kinds of substrates is then performed.
EQEC '05. European Quantum Electronics Conference, 2005., 2005
The work aims to develop an atom lithography apparatus by exploiting cold atoms, differently from... more The work aims to develop an atom lithography apparatus by exploiting cold atoms, differently from conventional implementations where thermal atomic sources are used. The cold atomic beam of the apparatus is produced continuously out of a pyramidal magnetooptical trap (MOT) for cesium atoms, a specific configuration of mirrors mounted as the inner part of a hollow pyramid, with a small
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