This paper presents a realization of a self-sensing ionic polymer-metal composite (IPMC) device by patterning its surface
electrodes and thus creating separate actuator and sensor parts. The sensor and actuator elements of such device are still
electrically coupled through the capacitance and/or conductivity of the ionic polymer. By creating a separate grounded
shielding electrode between the two parts, it is possible to suppress significantly the undesired cross-talk from the
actuator to the sensor. The paper at hand compares three different methods for separating sensor and actuator parts:
manual scraping, machine milling, and laser ablation. The basis of comparison of the methods is the electrical
characteristics of the device after realizing the surface patterns and the convenience of manufacturing.
Diamond like-carbon films were fabricated by pulsed laser ablation of a liquid target (vacuum oil) in a very small
(volume below 1 cm3) vacuum chamber, where the film was deposited onto the inner surface of the chamber window.
The synthesis was carried out at room temperature using 248 nm KrF excimer laser. The sp3 hybridization carbon
formation was additionally promoted by gaseous H2O2 flow through the reaction chamber.
Deposited diamond-like carbon films were characterized by Raman scattering spectroscopy, optical and atomic force
microscopy. The results indicated that higher sp3 content was present in the film areas exposed to the laser irradiation
during the deposition. The surface roughness of these areas was lower compared with that of the non-irradiated areas.
Optical microscopy observations indicated that the films had interference-colored regions on laser irradiated areas. These
colored regions were significantly different from their surroundings, which were grey or brown. Thus, the interferencecolored
regions have very wide band gap (&Dgr;E > 3 eV) and accordingly, high sp3 hybridized carbon content.
An essential factor for the creation of oxygen sensors based on luminescence quenching is the long-term stability of the
parameters determining the luminescence decay. In the present work, the effects of material aging and photobleaching on
decay parameters are studied for Pd-tetraphenylporphyrin and Pd-pentafluoro-tetraphenylporphyrin molecules embedded
into different polymer films. In polymethylmethacrylate host the decay was well described by stretched exponent
function. During annealing of PMMA films at different temperatures between 20 and 70 °C during 9 months a
logarithmic decrease of the material sensitivity occurred due to the physical aging of the polymer. The photostability
studies of PMMA films showed an opposite effect: the photobleaching was accompanied by a decrease in natural decay
time, whereas the oxygen sensitivity remained practically constant. Luminescence quenching in polystyrene and
polycarbonate films had different character as compared to PMMA, and was interpreted with a two-site model, combined
with a nonlinear gas transport model. In these polymer hosts the oxygen sensitivity increased during the first stage of
aging, which was ascribed to the changes in the Langmuir component of gas transport, i.e., to the evaluation of
microvoids in these glassy polymers.
New method for 3D nano-scale imaging was developed that combines a traditional scanning probe techniques with a local laser ablation processing of the surface of a sample. The technology opens new possibilities for ultra precise (down to atomic resolution) subsurface studies, whereas the traditional SPM sensitivity is limited to only few atomic layers. We demonstrate that our new experimental set-up can also be used for other investigations, e.g. in in situ characterization of surface processing. The approach is potentially interesting for many applications, like volume nano-imaging, in situ studies of a stimulated nano-assembling or growth, monitoring of laser processing and cleaning, etc.
Thin films of erbium-doped YAG (Y3Al5O12) were grown by pulsed laser deposition, followed by high temperature (>1100 degree(s)C) post-annealing. The deposition was carried out on MgO and MgAl2O4 substrates in ultra-high vacuum chamber with KrF excimer laser at fluences 2.5-3 J/cm2. Influence of growth conditions (substrate temperature, gas environment, annealing temperature) on structural, topographical, and optical properties was investigated by using optical spectroscopy, X-ray diffraction, and atomic force microscopy.
When modern spectral hole burning applications for high-density information storage under noncryogenic temperatures are envisioned, it is necessary to develop new frequency-selective photoactive materials for this purpose. Mixed compounds of the PbFCI family, doped with samarium (II) ions, exhibit promising and true room-temperature hole burning capabilities. We investigate this class of systems (and related ones) by combining material synthesis and high-resolution spectroscopy. Whole groups of isomorphous crystals were synthesized with varying degrees of halide anion and/or cation substitutions. Thin films of fluoride-based materials were made in a laboratory-built molecular beam epitaxy system. An extended x-ray study, differential thermal analysis, luminescence, and Raman measurements allowed the characterization of the materials. Formal models were developed for both the inhomogeneous zero-phonon optical line shapes of the Samarium (II) and the time evolution of hole burning.
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