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Transparent conducting oxides are used as transparent electrical contacts in a variety of applications, including in electrochromic smart windows. In the present work, we performed a study of transparent conducting antimony-doped tin oxide (ATO) thin films by chronopotentiometry in a Li+-containing electrolyte. The open circuit potential vs. Li was used to investigate ATO band lineups, such as those of the Fermi level and the ionization potential, as well as the dependence of these lineups on the preparation conditions for ATO. Evidence was found for Li+ intercalation when a current pulse was set in a way so as to drive ions from the electrolyte into the ATO lattice. Galvanostatic intermittent titration was then applied to determine the lithium diffusion coefficient within the ATO lattice. The electrochemical density of states of the conducting oxide was studied by means of the transient voltage recorded during the chronopotentiometry experiments. These measurements were possible because, as Li+ intercalation took place, charge compensating electrons filled the lowest part of the conduction band in ATO. Furthermore, the charge insertion modified the optical properties of ATO according to the Drude model. [ABSTRACT FROM AUTHOR]

Indium tin oxide (ITO) thin films have been grown onto soda-lime glass substrates by sputtering at room temperature with various oxygen to argon partial pressure ratios. After deposition, the samples have been annealed at temperatures ranging from 100 to 500 °C in nitrogen or in air. The structure, optical, and electrical characteristics of the ITO coatings have been analyzed as a function of the deposition and the annealing parameters by x-ray diffraction, spectrophotometry, and Hall effect measurements. It has been found that the as-grown amorphous layers crystallize in the cubic structure by heating above 200 °C. Simultaneously, the visible optical transmittance increases and the electrical resistance decreases, in proportions that depend mainly on the sputtering conditions. The lowest resistivity values have been obtained by annealing at 400 °C in nitrogen, where the highest carrier concentrations are achieved, related to oxygen vacancy creation. Some relationships between the analyzed properties have been established, showing the dependence of the cubic lattice distortion and the infrared optical characteristics on the carrier concentration. [ABSTRACT FROM AUTHOR]

Local piezoelectric deformation is investigated in (Pb,La)TiO3 (PLT) and Pb(Zr,Ti)O3 (PZT) thin films via scanning force microscopy (SFM) as a function of the ac voltage Vac applied between the conducting tip and the bottom electrode. Thus obtained voltage dependence of the effective piezoelectric coefficient (local piezoelectric nonlinearity) is compared with the corresponding macroscopic piezoelectric behavior determined by laser interferometry. As expected, the local piezoresponse of PLT films measured inside uniformly polarized areas (ferroelectric domains) remains almost linear with increasing Vac until the driving voltage becomes comparable with the coercive one. The corresponding macroscopic response is substantially nonlinear, suggesting significant contribution from the motion of 90° domain walls. On the contrary, in PZT films the local piezoelectric behavior is strongly nonlinear, whereas the macroscopic piezoelectric coefficient is almost field independent. Moreover, depending on the polarity of probed as-grown domains, the local piezocoefficient of PZT films is found to display either enhancement or reduction with increasing ac voltage. The "positive" domains si.e., domains having polarization vector pointing to the film-free surfaced are often unstable with increasing Vac and switch into the opposite polarization state under an ac voltage several times smaller than that required for global polarization reversal. This effect is explained by the presence of charged domain boundaries below the surface and their local depinning induced by external field. It is envisaged that SFM can be used not only for polarization mapping of ferroelectric surfaces but also as a probe for studying local polarization profiles beneath the SFM tip. [ABSTRACT FROM AUTHOR]

The excitation of a fullerene-cage vibrational mode by inelastic tunneling electrons has been observed on single C[sub 60] molecules adsorbed on Ag(110). The vibration is assigned to the H[sub g](ω[sub 2]) mode. A critical enhancement of the inelastic signal was found on fullerenes oriented along one of their symmetry axis upon adsorption. In strong coincidence, those fullerenes maintain a resonance structure at the Fermi level that resembles the first unoccupied molecular orbital distribution of a free molecule, as determined by comparison with ab initio calculations. The degree of symmetry of the adsorbed fullerene is found to be crucial for resonant mechanism of vibrational excitation. We also propose that mode degeneracy splitting may reduce mode detection. [ABSTRACT FROM AUTHOR]

We have performed a careful study of the adsorption of C[sub 60] molecules on a Au(111) surface by using scanning tunneling microscopy and spectroscopy at room temperature. In coincidence with results from other techniques, differential conductance spectra give a value of 2.3 eV for the HOMO–LUMO gap of a monomolecular layer, with the LUMO level located at 0.6 eV above the Fermi level as a consequence of electronic charge transfer from the substrate into the molecule. Small differences in position (and shape) of the LUMO-derived resonance, in the order of 0.1 eV, are found on molecules adsorbed at step edges. We consider the Smoluchowski effect, i.e., the interaction of the molecules with a charge-depleted region, to explain the observed differences in their bonding nature. On some molecules forming part of bidimensional fullerene islands, similar differences were also detected with spatially resolved scanning tunneling spectroscopy, giving rise to a 2×2 commensurate structure of the molecular adlayer with respect to the substrate. This finding is attributed to different electronic properties of the adsorption site, indicating that molecules adsorbed on the top position are less charged than those on bridge sites. © 2002 American Institute of Physics. [ABSTRACT FROM AUTHOR]

Presents a study which examined the photovoltaic activity of electrodeposited copper indium diselenide thin films in aqueous acidic solutions. Use of the model of G&aumi;rtner to extract values of effective optoelectronic parameters of the copper indium diselenide films; Experimental details; Discussion.

Presents a study which measured the electrical properties of arsenic grown and heat treated copper indium diselenide thin films. Experimental details; Results and discussion; Conclusions.

Presents information on a study which determined optical absorption coefficients of electrodeposited CuInSe[sub2] thin films from the measured transmittance and reflectance at normal incidence of light. Electrodeposition of the films on titanium-coated glass substrates; Calculation of absorption coefficients for as-grown and heated samples; Changes in the optical characteristics resulting from the heat treatment of the films.

Sonic crystals have been demonstrated to be good candidates to substitute for conventional diffusers in order to overcome the need for extremely thick structures when low frequencies have to be scattered, however, their performance is limited to a narrow band. In this work, multiobjective evolutionary algorithms are used to extend the bandwidth to the whole low frequency range. The results show that diffusion can be significantly increased. Several cost functions are considered in the paper, on the one hand to illustrate the flexibility of the optimization and on the other hand to demonstrate the problems associated with the use of certain cost functions. A study of the robustness of the optimized diffusers is also presented, introducing a parameter that can help to choose among the best candidates. Finally, the advantages of the use of multiobjective optimization in comparison with conventional optimizations are discussed. [ABSTRACT FROM AUTHOR]

An exhaustive study has been made into the potential improvement in attenuation and focusing of phononic crystal arrays resulting from the deliberate creation of vacancies. Use is made of a stochastic search algorithm based on evolutionary algorithms called the epsilon variable multi-objective genetic algorithm which, in conjunction with the application of multiple scattering theory, enables the design of devices for effectively controlling sound waves. Several parameters are analyzed, including the symmetries used in the distribution of holes and the optimum number of holes. The validity and utility of the general rules obtained have been confirmed experimentally. [ABSTRACT FROM AUTHOR]

In this work we briefly describe the most relevant features of WSXM, a freeware scanning probe microscopy software based on MS-Windows. The article is structured in three different sections: The introduction is a perspective on the importance of software on scanning probe microscopy. The second section is devoted to describe the general structure of the application; in this section the capabilities of WSXM to read third party files are stressed. Finally, a detailed discussion of some relevant procedures of the software is carried out. [ABSTRACT FROM AUTHOR]

A numerical study of bifurcations and stability of the steady convective flow of air in a cubical enclosure heated from below was carried out using a Galerkin spectral method. The set of basis functions was chosen so that all boundary conditions and the continuity equation were implicitly satisfied. A parameter continuation method was applied to determine the steady solutions and bifurcations of the nonlinear governing equations as a function of Rayleigh number (Ra) for values of Ra up to 1.5×105. The eigenvalue problem associated with the stability analysis of the steady solutions along the different branches of solutions was solved using the Arnoldi method. The convergence of the method was consistent with the number of modes used and the results were also verified by a numerical solution of the unsteady equations of motion using a finite-difference solver. Present results show that different stable convective flow patterns can coexist for different ranges of the Rayleigh number. [ABSTRACT FROM AUTHOR]

An improvement in the attenuation capabilities of acoustic metamaterials by means of the creation of defects is considered here as a multiobjective optimization problem. From this point of view, it is possible to define the optimum strategy in the creation of defects to achieve an important increase in acoustic attenuation in a predetermined range of frequencies. A powerful multiobjective optimization algorithm called evMOGA has been used to solve this problem. The study has been restricted to the case of a two-dimensional sonic crystal formed by rigid cylinders in air, the defects being vacancies in the initial structure. [ABSTRACT FROM AUTHOR]

A theoretical method for the imaging of metallic objects in electrostatic force microscopy is presented. The technique, based on the generalized image charge method, includes intrinsically the mutual polarization between the tip, the sample, and the metallic objects. Taking also into account the cantilever and macroscopic shape of the tip, the theory gives us a quantitative value for the electrostatic interaction between the tip and the objects over the surface. Experimental data of frequency shifts in an oscillating tip induced by grounded and isolated nanotubes are analyzed finding an excellent quantitative agreement between experimental data and numerical calculations. [ABSTRACT FROM AUTHOR]

We propose a mode of dynamic scanning probe microscopy based on parametric resonance for highly sensitive nanoscale imaging and force spectroscopy. In this mode the microcantilever probe is excited by means of a closed-loop electronic circuit that modulates the microcantilever stiffness at a frequency close to twice its natural resonance frequency. Under ambient conditions this parametric pumping leads to self-sustained oscillations in a narrow frequency bandwidth thereby resulting in exquisitely sharp, controllable, and non-Lorentzian resonance peaks. We discuss and demonstrate the potential of imaging and force spectroscopy using this mode. [ABSTRACT FROM AUTHOR]

In this work theoretical considerations of the performance of scanning force microscopy jumping mode and tapping mode in liquids are discussed. A priori, jumping mode should improve in a liquid environment compared to in air while the situation for tapping mode should become worse. In order to confirm this we present jumping and tapping mode images of DNA molecules absorbed on a mica substrate immersed in water. The experiments demonstrate that jumping mode is a suitable scanning force microscopy method by which to image soft samples in liquid and that it has similar or even better performance than those exhibited by tapping, but without the complex experimental requirements of this mode. [ABSTRACT FROM AUTHOR]

Presents a method to perform current versus voltage measurements of single-walled carbon nanotubes (SWNT) using scanning force microscopy. Application of the method to check the ballistic transport of SWNT; Effects of applying stresses to a SWNT; Impact to the electrical properties of SWNT.

In this letter, a method is presented to qualitatively investigate the electrical connection between single-walled carbon nanotubes and gold electrodes. By applying a time independent bias voltage to the scanning force microscope tip, there is a clear apparent growth effect in the topography of the electrically connected carbon nanotubes. This effect is induced by the electrostatic interaction of the tip with the free charges located at the conducting areas of the surface. This is a general method that could be applied to any molecular conducting nanowire. © 2001 American Institute of Physics. [ABSTRACT FROM AUTHOR]

Examines the use of real time electron microscopy in inspecting high temperature processes in tungsten free standing wires (FSW). Efficiency of fabricated FSW in investigating quantum mechanics phenomena; Usage of electrochemical etching in fabricating tungsten FSW; Effect of strong thermal gradient on migration mechanisms.

Acoustic dynamic force microscopy in liquids is a fundamental technique for the investigation of biological samples under physiological conditions. However, it shows an important drawback that consists of producing a myriad of resonance peaks, known as the forest of peaks, which hides the natural resonance frequency of the cantilever and prevents an optimum operation of the microscope. In this work, we propose a simple remedy for this problem, which consists on adding a small clay damper to the dither piezoelectric. The resulting frequency spectrum exhibits a single resonance peak that is comparable with the one obtained using magnetic excitation. [ABSTRACT FROM AUTHOR]

We report surface potential maps of few layered graphene oxide films on different substrates. Kelvin probe force microscopy images reveal that the surface potential decreases in steps with increasing number of layers on the substrate until five layers are reached, where it saturates to a constant value. This intrinsic behavior is smeared out in the presence of ambient humidity where the surface potential is shielded by the presence of a thin water layer on the surface. This effect can be exploited to quickly determine the number of layers of graphene oxide on a substrate. [ABSTRACT FROM AUTHOR]

Presents a corrected version of the article 'Performing Current Versus Voltage Measurements of Single-Walled Carbon Nanotubes Using Scanning Force Microscopy,' published in the journal 'Applied Physics Letter,' vol. 80, no. 1462.

Provides a corrected reprint to an article previously published in the February 2002 issue of the 'Applied Physics Letters.'

In this letter, we present a new scanning probe microscopy mode, jumping mode, which allows the simultaneous measurement of the topography and of some other physical property of the sample. Essentially, at each image point first the topography of the sample is measured during a feedback phase of a cycle, and then the tip–sample interaction is evaluated in real time as the tip is moved away and towards the sample. Since the lateral motion is done out of contact the method is free, or nearly free, of shear forces. The general advantages of jumping mode are discussed. Finally, two different applications of this mode are presented. In addition to the topography, the first application measures the adhesion between the tip and the sample, while the second determines the corresponding electrostatic interaction.© 1998 American Institute of Physics. [ABSTRACT FROM AUTHOR]

Here we present experimental evidence of the strong modification of the CdS photoluminescence when it is embedded in a SiO[sub 2] colloidal photonic crystal. When the emitted light matches a forbidden photonic band in the matrix, inhibition of the semiconductor photoluminescence is achieved. In this work we prove the effective control of this effect by means of the photonic lattice parameter of the host. CdS was grown by chemical bath deposition and its quality has been checked employing Raman spectroscopy and x-ray diffraction. Scanning electron microscopy is used to study the morphology of the composite. © 1998 American Institute of Physics. [ABSTRACT FROM AUTHOR]

Most of studies in protein nanomechanics have used the atomic force microscope (AFM) in its force-measuring mode on immobilized protein repeats (polyproteins) as single-molecule markers. Here, we add imaging capabilities to a standard, state-of-the-art AFM "puller" and integrate the most powerful programs of analysis available for both AFM modes. This unique instrument allows high-resolution, quasi-simultaneous imaging/force spectroscopy in aqueous solution. We demonstrate its capabilities using polyproteins of a model system (titin I27 domain). This tool should greatly facilitate the development of a much needed universal functionalization system for AFM, one that should allow better sample control and an improved efficiency of protein immobilization.