The Experts below are selected from a list of 297 Experts worldwide ranked by ideXlab platform
Salvatore Iannotta - One of the best experts on this subject based on the ideXlab platform.
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Structural and morphological phase control by Supersonic Beams on titanyl phthalocyanine: An investigation on the growth
Organic Electronics, 2016Co-Authors: Nicola Coppedè, Elisa Bonnini, Francesco Mezzadri, Giuseppe Tarabella, Paolo Ranzieri, Luisa Barba, Gianmichele Arrighetti, Luca Lutterotti, Salvatore IannottaAbstract:Abstract Titanyl Phthalocyanine (TiOPc) is a cyclic oligomer widely used in organic electronics for its good stability, optical properties and charge mobility. Several polymorphs of TiOPc are known, showing different physical properties and consequently, in particular in the growth of thin films, the full control over the crystal phase formation is critical to effectively tune the conductive properties of the material. As a consequence, the availability of growth techniques allowing a precise control of both the morphology and crystal phase of the obtained films is crucial for the production of devices. In this work the structural properties and polymorphism of titanyl phthalocyanine thin films, grown on silicon substrates, have been systematically studied by synchrotron radiation grazing incidence X-rays diffraction and atomic force microscopy. Films obtained by the use of hyperthermal seeded Supersonic Beams technique allowed to unveil the key role played by the kinetic energy of the molecules in stabilizing specific polymorphs of TiOPc. The different growth conditions lead to grain dimensions in a range from the nanometric to the micrometric scale, depending on the substrate temperature and on the kinetic energy of the beam, while a high degree of fiber-like crystallographic order is observed in all the analyzed samples. The excellent control over phase selection, grain size and shape together with the production of well oriented high quality crystals makes of the hyperthermal seeded Supersonic Beams technique a promising tool for the realization of TiOPc thin films with structural and morphologic properties suitable for electronic application.
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Supersonic molecular Beams deposition of α quaterthiophene enhanced growth control and devices performances
Organic Electronics, 2009Co-Authors: Tullio Toccoli, Armin Pallaoro, Nicola Coppedè, M. Tonezzer, Paolo Bettotti, S Larcheri, L Pavesi, Salvatore IannottaAbstract:The alpha-quatertiophene is widely considered an interesting material for the realization of organic electronics and opto-electronics. Compared to other oligothiophenes, the performances of transistors based on this compound are limited by its kind of growth on the typical materials used for device realization. Here we show that via seeded Supersonic Beams we can lead to a nice improvement of both morphological and electrical properties of the film grown, through a better control of the initial state of the precursor in the vapor phase. Using the high kinetic energy achievable in the Supersonic Beams, we increase the dimensions of the grains and the coalescence of different islands, limiting the grain boundary formation. As consequence, the performance of the realized field effect transistors is enhanced of one order of magnitude.
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Novel nano-hybrid gas sensor based on n-TiO2 functionalized by phthalocyanines via Supersonic beam co-deposition: Performance and application to automotive air quality
SENSORS 2008 IEEE, 2008Co-Authors: Tullio Toccoli, Armin Pallaoro, Nicola Coppedè, Fábio Siviero, M. Tonezzer, Salvatore Iannotta, M Mazzola, Clara Corradi, A. ForleoAbstract:Supersonic Beams of TiO2 clusters and metal phthalocyanines have been developed for the synthesis of hybrid for gas-sensing applications. This approach allows high degree of control on the properties of the synthesized materials and on the interface between clusters and organic molecules, so that new functional materials with novel and promising sensing properties are obtained. These materials can be synthesized in different architectures, shape and phases, and are constituted by nanocrystalline clusters of TiO2 functionalized during the growth by the co-deposited molecules. The outcome is a porous nanostructured material characterized by a diffused organic-inorganic interface at the nanoscale. The properties of the codeposited interfaces, where the functionalization of the hybrid material plays a crucial role, can be tailored directly acting on the beam parameters of the cluster (mass size distribution, phase) and of the organic molecules (kinetic energy, deposition rate).
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Organic, Cluster Assembled and Nano-Hybrid Materials Produced by Supersonic Beams: Growth and Applications to Prototype Device Development
2005Co-Authors: Lucrezia Aversa, Tullio Toccoli, Armin Pallaoro, Nicola Coppedè, Fábio Siviero, Salvatore Iannotta, A. Boschetti, S. Chiarani, Margherita Nardi, Roberto VerucchiAbstract:An approach to the growth of films of π-conjugated organic materials, cluster assembled and nanohybrid materials combining Supersonic free jets with a UHV deposition apparatus including surface characterization methods will be discussed. The unique control achievable with Supersonic Beams on initial kinetic energy, momentum and state of aggregation enables the growth of materials with controlled properties at different length scales. Results obtained with organic semiconductors and oligomers point out the crucial role of kinetic energy in growing organic crystalline films with well controlled morphologies and structures. By means of Supersonic Beams of clusters, nanocrystalline metal oxide films can be grown without annealing, so that grain size and morphology can be better controlled. In a co-deposition scheme these interesting features are combined in order to obtain a new class of hybrid functional materials with appealing properties for electronics, gas sensing and photovoltaic applications.
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Titanium dioxide thin films prepared by seeded Supersonic Beams for gas sensing applications
Sensors and Actuators B: Chemical, 2004Co-Authors: Antonella M. Taurino, Tullio Toccoli, Armin Pallaoro, Simonetta Capone, Pietro Siciliano, A. Boschetti, Roberto Verucchi, Salvatore IannottaAbstract:Abstract This paper reports on the preparation, surface and electrical characterisation of titanium dioxide thin-films for highly selective gas sensor devices. Seeded Supersonic beam deposition technique was used to prepare nanostructured thin films for gas sensors application. Two different typologies of sensors, prepared under different deposition conditions, were investigated. They showed gas-sensing properties comparable to most of the TiO 2 films realised with other more conventional techniques.
Tullio Toccoli - One of the best experts on this subject based on the ideXlab platform.
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Supersonic molecular Beams deposition of α quaterthiophene enhanced growth control and devices performances
Organic Electronics, 2009Co-Authors: Tullio Toccoli, Armin Pallaoro, Nicola Coppedè, M. Tonezzer, Paolo Bettotti, S Larcheri, L Pavesi, Salvatore IannottaAbstract:The alpha-quatertiophene is widely considered an interesting material for the realization of organic electronics and opto-electronics. Compared to other oligothiophenes, the performances of transistors based on this compound are limited by its kind of growth on the typical materials used for device realization. Here we show that via seeded Supersonic Beams we can lead to a nice improvement of both morphological and electrical properties of the film grown, through a better control of the initial state of the precursor in the vapor phase. Using the high kinetic energy achievable in the Supersonic Beams, we increase the dimensions of the grains and the coalescence of different islands, limiting the grain boundary formation. As consequence, the performance of the realized field effect transistors is enhanced of one order of magnitude.
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Novel nano-hybrid gas sensor based on n-TiO2 functionalized by phthalocyanines via Supersonic beam co-deposition: Performance and application to automotive air quality
SENSORS 2008 IEEE, 2008Co-Authors: Tullio Toccoli, Armin Pallaoro, Nicola Coppedè, Fábio Siviero, M. Tonezzer, Salvatore Iannotta, M Mazzola, Clara Corradi, A. ForleoAbstract:Supersonic Beams of TiO2 clusters and metal phthalocyanines have been developed for the synthesis of hybrid for gas-sensing applications. This approach allows high degree of control on the properties of the synthesized materials and on the interface between clusters and organic molecules, so that new functional materials with novel and promising sensing properties are obtained. These materials can be synthesized in different architectures, shape and phases, and are constituted by nanocrystalline clusters of TiO2 functionalized during the growth by the co-deposited molecules. The outcome is a porous nanostructured material characterized by a diffused organic-inorganic interface at the nanoscale. The properties of the codeposited interfaces, where the functionalization of the hybrid material plays a crucial role, can be tailored directly acting on the beam parameters of the cluster (mass size distribution, phase) and of the organic molecules (kinetic energy, deposition rate).
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Organic, Cluster Assembled and Nano-Hybrid Materials Produced by Supersonic Beams: Growth and Applications to Prototype Device Development
2005Co-Authors: Lucrezia Aversa, Tullio Toccoli, Armin Pallaoro, Nicola Coppedè, Fábio Siviero, Salvatore Iannotta, A. Boschetti, S. Chiarani, Margherita Nardi, Roberto VerucchiAbstract:An approach to the growth of films of π-conjugated organic materials, cluster assembled and nanohybrid materials combining Supersonic free jets with a UHV deposition apparatus including surface characterization methods will be discussed. The unique control achievable with Supersonic Beams on initial kinetic energy, momentum and state of aggregation enables the growth of materials with controlled properties at different length scales. Results obtained with organic semiconductors and oligomers point out the crucial role of kinetic energy in growing organic crystalline films with well controlled morphologies and structures. By means of Supersonic Beams of clusters, nanocrystalline metal oxide films can be grown without annealing, so that grain size and morphology can be better controlled. In a co-deposition scheme these interesting features are combined in order to obtain a new class of hybrid functional materials with appealing properties for electronics, gas sensing and photovoltaic applications.
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Deposition from Supersonic Beams (SuMBE): a Kinetic Approach for Controlling Thin Film Properties
AIP Conference Proceedings, 2005Co-Authors: Armin Pallaoro, Tullio Toccoli, Nicola Coppedè, M Mazzola, A. Boschetti, Lucrezia Aversa, S. Chiarani, Margherita Nardi, C. Corradi, Fábio SivieroAbstract:Supersonic Beams of organic molecules seeded in light carrier gases are a viable method to control the deposition of highly ordered thin films, to activate kinetically chemical reactions to functionalize surfaces or to synthesize hybrid compounds. The advantage of Supersonic molecular beam deposition (SuMBE) with respect to the more standard OMBE/OMBD method is the control of the energetic parameters of the precursors that we have shown to give an unprecedented control on structural, morphological and hence functional properties in the deposition of organic thin films. The basic mechanism is envisaged to be a sort of local annealing activated by the kinetic energy of the molecules that collides with the surface. Depending on the molecular precursor used and on the kinetic energy achievable this same method can be exploited to activate reactivity at the surface and hence to synthesize different structures. Here we report on a few examples including the deposition of highly ordered organic thin films of pentacene, the synthesis of SiC at moderate temperatures and the functionalization of inorganic nanostructured materials such as TiO2.
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Titanium dioxide thin films prepared by seeded Supersonic Beams for gas sensing applications
Sensors and Actuators B: Chemical, 2004Co-Authors: Antonella M. Taurino, Tullio Toccoli, Armin Pallaoro, Simonetta Capone, Pietro Siciliano, A. Boschetti, Roberto Verucchi, Salvatore IannottaAbstract:Abstract This paper reports on the preparation, surface and electrical characterisation of titanium dioxide thin-films for highly selective gas sensor devices. Seeded Supersonic beam deposition technique was used to prepare nanostructured thin films for gas sensors application. Two different typologies of sensors, prepared under different deposition conditions, were investigated. They showed gas-sensing properties comparable to most of the TiO 2 films realised with other more conventional techniques.
Edvardas Narevicius - One of the best experts on this subject based on the ideXlab platform.
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sub kelvin collision temperatures in merged neutral Beams by correlation in phase space
Journal of Physical Chemistry C, 2013Co-Authors: Yuval Shagam, Edvardas NareviciusAbstract:Recent merged neutral beam experiments have introduced the possibility of measuring reactive collisions in the cold regime down to 10 mK. The lowest temperature attained in these experiments cannot be explained using the standard formalism developed for crossed molecular beam scattering. These low temperatures become accessible because pulsed Supersonic Beams develop a correlation in velocity-position space during free propagation such that the local velocity standard deviation decreases. This effect is responsible for a reduction in the attainable collision energy by more than 2 orders of magnitude along with an order of magnitude improvement in the resolution. We show that Supersonic nozzles with short pulsed opening durations compared to the time-of-flight, such as the Even-Lavie valve, have a clear advantage in achieving low collision energies with improved resolution. We discuss possible improvements in the energy resolution by varying the detection time duration.
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observation of resonances in penning ionization reactions at sub kelvin temperatures in merged Beams
Science, 2012Co-Authors: Alon Henson, Julia Narevicius, Yuval Shagam, Sasha Gersten, Edvardas NareviciusAbstract:Experiments have lagged theory in exploring chemical interactions at temperatures so low that translational degrees of freedom can no longer be treated classically. The difficulty has been to realize in the laboratory low-enough collisional velocities between neutral reactants to access this regime. We report here the realization of merged neutral Supersonic Beams and the manifestation of clear nonclassical effects in the resulting reactions. We observed orbiting resonances in the Penning ionization reaction of argon and molecular hydrogen with metastable helium, leading to a sharp absolute ionization rate increase in the energy range corresponding to a few degrees kelvin down to 10 millikelvin. Our method should be widely applicable to many canonical chemical reactions.
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stopping paramagnetic Supersonic Beams the advantage of a co moving magnetic trap decelerator
Physical Chemistry Chemical Physics, 2011Co-Authors: Etay Lavertofir, Julia Narevicius, Alon Henson, Sasha Gersten, Liron David, Edvardas NareviciusAbstract:The long standing goal of chemical physics is finding a convenient method to create slow and cold Beams intense enough to observe chemical reactions in the temperature range of a few Kelvin. We present an extensive numerical analysis of our moving magnetic trap decelerator showing that a 3D confinement throughout the deceleration process enables deceleration of almost all paramagnetic particles within the original Supersonic expansion to stopping velocities. We show that the phase space region containing the decelerating species is larger by two orders of magnitude as compared to other available deceleration methods.
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stopping Supersonic Beams with a series of pulsed electromagnetic coils an atomic coilgun
Physical Review Letters, 2008Co-Authors: Edvardas Narevicius, Uzi Even, Agnieszka Libson, Christian G. Parthey, Julia Narevicius, Isaac Chavez, Mark G RaizenAbstract:We report the stopping of an atomic beam, using a series of pulsed electromagnetic coils. We use a Supersonic beam of metastable neon created in a gas discharge as a monochromatic source of paramagnetic atoms. A series of coils is fired in a timed sequence to bring the atoms to near rest, where they are detected on a microchannel plate. Applications to fundamental problems in physics and chemistry are discussed.
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Stopping Supersonic Beams with an Atomic Coilgun
arXiv: Atomic Physics, 2008Co-Authors: Edvardas Narevicius, Uzi Even, Agnieszka Libson, Christian G. Parthey, Julia Narevicius, Mark G RaizenAbstract:Sackler School of Chemistry, Tel-Aviv University, Tel-Aviv, Israel(Dated: February 3, 2008)We report the stopping of an atomic beam, using a series of pulsed electromagnetic coils. Weuse a Supersonic beam of metastable neon created in a gas discharge as a monochromatic source ofparamagnetic atoms. A series of coils is fired in a timed sequence to bring the atoms to near-rest,where they are detected on a micro-channel plate. Applications to fundamental problems in physicsand chemistry are discussed.
Maurizio Speranza - One of the best experts on this subject based on the ideXlab platform.
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chiral aggregates of indan 1 ol with secondary alcohols and water laser spectroscopy in Supersonic Beams
Physical Chemistry Chemical Physics, 2002Co-Authors: D Scuderi, M Satta, Maurizio Speranza, S Piccirillo, A Paladini, Daniele Catone, Giardini A GuidoniAbstract:One color, mass selected resonant two-photon ionization (1cR2PI) spectra of Supersonically expanded bare (R)-(−)indan-1-ol (IR) and its complexes with chiral and achiral molecules (solv) have been investigated. The excitation spectrum of bare IR has been analyzed and discussed on the basis of theoretical predictions at the B3LYP/6-31G** level of theory. The excitation spectra of its diastereomeric complexes with (R)-(−)-and (S)-(+)hexan-2-ol (XR or XS, respectively) and water (W) are characterized by significant shifts of their S0 ← S1 band origin relative to that of bare IR. The extent and the direction of these shifts are found to depend upon the structure and the configuration of solv and are attributed to different short-range interactions in the ground and excited [IR·solv] complexes. In particular the [IR·W]n complexes display band origins blue-shifted relative to that of bare IR, attributed to the presence of an O–H⋯π electrostatic interaction between IR and W in [IR·W]n. The [IR·XR] and [IR·XS] equilibrium structures have been calculated by a molecular dynamical (MM3) sampling and PM3 semiempirical local optimization.
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short range interactions within molecular complexes formed in Supersonic Beams structural effects and chiral discrimination
Chemistry: A European Journal, 2000Co-Authors: A Latini, Susanna Piccirillo, M Satta, Anna Giardini Guidoni, Maurizio SperanzaAbstract:One- and two-color, mass-selected R2PI spectra of the S1<--S0 transitions in the bare chiral chromophore R-(+)-1-phenyl-1-propanol (R) and its complexes with a variety of alcoholic solvent molecules (solv), namely methanol, ethanol, 1-propanol, 2-propanol, 1-butanol, S-(+)-2-butanol, R-(-)-2-butanol, 1-pentanol, S-(+)-2-pentanol, R-(-)-2-pentanol, and 3-pentanol, were recorded after a Supersonic molecular beam expansion. Spectral analysis, coupled with theoretical calculations, indicate that several hydrogen-bonded [R.solv] conformers are present in the beam. The R2PI excitation spectra of [R.solv] are characterized by significant shifts of their band origin relative to that of bare R. The extent and direction of these spectral shifts depend on the structure and configuration of solv and are attributed to different short-range interactions in the ground and excited [R.solv] complexes. Measurement of the binding energies of [R.solv] in their neutral and ionic states points to a subtle balance between attractive (electrostatic and dispersive) and repulsive (steric) forces, which control the spectral features of the complexes and allow enantiomeric discrimination of chiral solv molecules.
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Short-range interactions within molecular complexes formed in Supersonic Beams: structural effects and chiral discrimination
Chemistry (Weinheim an der Bergstrasse Germany), 2000Co-Authors: A Latini, Susanna Piccirillo, Mauro Satta, Anna Giardini Guidoni, Maurizio SperanzaAbstract:One- and two-color, mass-selected R2PI spectra of the S1
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chirality and intermolecular forces studies using r2pi experiments in Supersonic Beams
Physical Chemistry Chemical Physics, 2000Co-Authors: Giardini A Guidoni, Susanna Piccirillo, D Scuderi, M Satta, T M Di Palma, Maurizio SperanzaAbstract:One- and two-color, mass-selected resonant two-photon ionization (R2PI) spectra of the S1←S0 transitions in the bare (R)-(+)-1-phenylethan-1-ol (ER) and its complexes with a solvent molecule (solv: (S)-(+)butan-2-ol (BS), (R)-(−)butan-2-ol (BR), or water (W)) have been recorded after a Supersonic molecular beam expansion. The excitation spectrum of bare ER conforms to theoretical predictions at the B3LYP/6-31G** level of theory by pointing to the formation of a single conformer. The one-color R2PI excitation spectra of the diastereomeric complexes [ER–solv] (solv: BS or BR) are characterized by significant shifts of their band origin relative to that of bare ER. The extent and the direction of these spectral shifts are found to depend upon the structure and the configuration of solv and are attributed to different short-range interactions in the ground and excited [ER–solv] complexes. In analogy with strictly related diastereomeric complexes, the phenomenological binding energy of the homochiral [ER–BR] is found to be greater that of the heterochiral one [ER–BS]. The one-color R2PI excitation spectra of the [ER–W] complex displays two signals blue shifted by 54 and 73 cm−1, relative to the S1←S0 band origin of bare ER, which indicate the presence of a O–H···π electrostatic interaction between ER and W.
Takayuki Ebata - One of the best experts on this subject based on the ideXlab platform.
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Vibrational Spectroscopy of Gas Phase Functional Molecules and Their Complexes Cooled in Supersonic Beams
Vibrational Spectroscopy, 2012Co-Authors: Takayuki Ebata, Ryoji Kusaka, Yoshiya InokuchiAbstract:Functional molecules and supramolecules are the assemble of molecules, which are bound by noncovalent interactions, such as dispersion force, coordinate-bonding, hydrogenbonding, etc. They exhibit special functions by forming regular high dimensional structures controlled by those weak interactions. The concept of the supramolecule was first proposed by Jean-Marie Lehn, who succeeded in synthesizing cryptand (Lehn, 1995). In the early stage, many studies have been carried out for host-guest complexes of crown ether (Gokel, 1991; Izatt et al., 1969; Pedersen, 1967; Pedersen & Frensdorff, 1972), calixarene (Atwood et al., 2002; Gutsche, 1998; Purse et al., 2005; Thallapally et al., 2005), and cyclodextrin (Brocos et al., 2010; Szejtli, 1988). These studies are extended to larger size systems built by several units, such as protein, LangmuirBlodgett (LB) film, self assembled monolayer (SAM), and liquid crystal. In addition, more complicated molecular assemblies, rotaxane, catenane, and molecular capsules, are synthesized. Also, many functional groups have been used to applications such as sensing and basic chemical research, by covalently linking fluorescent dyes, nanoparticles, proteins, DNA, and other compounds of interest. Biomolecules may also be categorized to the functional molecules. In the biomolecules, many units form high dimensional structure through noncovalent interactions and exhibit special functions which are not possible for each unit. Among many experimental studies on the functional molecules, vibrational spectroscopy is one of the most general methods. By examining the frequency shift and intensity change of the specific vibrations sensitive to the local interaction, we can study which part or site of the molecule bound for the complexation. In this sense, it is necessary to investigate vibrational spectra not only of the complexes but also of each unit under the isolated condition. By the comparison of the spectra at different conditions, we understand how the molecules change their initial structures or which conformer is preferred for the complexation. A problem for this study is that in most cases they have flexible structures so that the structures are affected by many factors, such as temperature, local environment, solvent molecules as well as the phases. These effects result in the homogenous and inhomogeneous broadening of the spectra, which leads to the difficulty to analyze the spectra. In this chapter, we describe the vibrational spectroscopic study of gas phase small size functional molecules cooled in the Supersonic jet. The Supersonic jet technique enables us to
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Relaxation dynamics of NH stretching vibrations of 2-aminopyridine and its dimer in a Supersonic beam
Proceedings of the National Academy of Sciences of the United States of America, 2008Co-Authors: Yuji Yamada, Naohiko Mikami, Takayuki EbataAbstract:Picosecond time-resolved IR–UV pump–probe spectroscopy has been carried out to elucidate vibrational energy relaxation (VER) of the NH stretching vibrations of 2-aminopyridine monomer (2AP) and dimer [(2AP)2] in Supersonic Beams. In bare 2AP, intramolecular vibrational energy redistribution (IVR) of the NH vibrations is described by the two-bath mode model, in which the initial vibrational energy flows to the doorway states rapidly (6.5 ps) and then dissipates into the dense bath states with a time constant of ≈20 ps. No clear difference was observed in the IVR lifetime between the symmetric and asymmetric NH2 stretch modes. In (2AP)2, IVR and vibrational predissociation (VP) were involved in VER. It was found that the rate constants of both IVR and VP of the hydrogen-bonded NH stretching vibration are larger than those of the free NH.
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Real-time detection of doorway states in the intramolecular vibrational energy redistribution of the OH/OD stretch vibration of phenol
Journal of Chemical Physics, 2004Co-Authors: Yuji Yamada, Naohiko Mikami, Takayuki EbataAbstract:A picosecond time-resolved IR-UV pump–probe spectroscopic study was carried out for the intramolecular vibrational energy redistribution of the OH/OD stretching vibration of isolated phenol and its isotopomers in Supersonic Beams. The time evolution due to IVR showed a significant isotope effect; the OH stretch vibration showed a single exponential decay and its lifetime is greatly lengthened upon the deuterium substitution of the CH group. The OD stretch vibration exhibited prominent quantum beats. Especially, in phenol-d1 (C6H5OD), the electronic transitions from the doorway states were clearly observed. They exhibited an out-of-phase quantum beat with respect to that of the OD stretch level and disappeared due to further IVR to the dense bath states. The transient spectra as well as the time evolution clearly evidenced the tier-model of the description of intramolecular vibrational energy redistribution.