Towards truly simultaneous PIXE and RBS analysis of layered objects in cultural heritage

For a long time, RBS and PIXE techniques have been used in the field of cultural heritage. Although the complementarity of both techniques has long been acknowledged, its full potential has not been yet developed due to the lack of general purpose software tools for analysing the data from both techniques in a coherent way. In this work we provide an example of how the recent addition of PIXE to the set of techniques supported by the DataFurnace code can significantly change this situation. We present a case in which a non homogeneous sample (an oxidized metal from a photographic plate -heliography- made by Niepce in 1827) is analysed using RBS and PIXE in a straightforward and powerful way that can only be performed with a code that treats both techniques simultaneously as a part of one single and coherent analysis. The optimization capabilities of DataFurnace, allowed us to obtain the composition profiles for these samples in a very simple way.Comment: 9 pages, 3 figure

Simultaneous PIXE and RBS data analysis using Bayesian Inference with the DataFurnace code

The Rutherford Backscattering Spectroscopy (RBS) and Particle Induced X-ray Emission (PIXE) techniques can be used to obtain complementary information about the characteristics of a sample but, traditionally, a gap has separated the available computer codes for analyzing data from each technique, being hard to simultaneously analyze data from the same sample. The recent development of a free and open source library, LibCPIXE, for PIXE simulation and analysis of arbitrary multilayered samples, has permitted to integrate this technique into the DataFurnace code which already handles many other IBA techniques such as Rutherford and non-Rutherford backscattering, elastic recoil detection, and non-resonant nuclear reaction analysis. The fitting capabilities of DataFurnace can therefore now be applied to PIXE spectra as well, including the Bayesian Inference analysis and the simultaneous and coherent fitting of multiple spectra from different techniques. Various examples are presented in which the simultaneous RBS and PIXE analysis allows us to obtain consistent results that cannot be obtained by independent analysis of the data from each technique.Comment: 10 pages, 5 figures. Paper initially presented to IBA2005. Please cite the published version (DOI:10.1016/j.nimb.2006.03.190

LibCPIXE: a PIXE simulation open-source library for multilayered samples

Most particle induced X-ray emission (PIXE) data analysis codes are not focused on handling multilayered samples. We have developed an open-source library called "LibCPIXE", for PIXE data analysis. It is written in standard C and implements functions for simulating X-ray yields of PIXE spectra taken from arbitrary samples, including multilayered targets. The library is designed to be fast, portable, modular and scalable, as well as to facilitate its incorporation into any existing program. In order to demonstrate the capabilities of the library, a program called CPIXE was developed and used to analyze various real samples involving both bulk and layered samples. Just as the library, the CPIXE source code is freely available under the General Public License. We demonstrate that it runs both under GNU/Linux systems as well as under MS Windows. There is in principle no limitation to port it to other platforms

Color tunable pressure sensors based on polymer nanostructured membranes for optofluidic applications

We demonstrate an integrated optical pressure sensing platform for multiplexed optofluidics applications. The sensing platform consists in an array of elastomeric on-side nanostructured membranes -effectively 2D photonic crystal- which present colour shifts in response to mechanical stress that alter their nanostructure characteristical dimensions, pitch or orientation. The photonic membranes are prepared by a simple and cost-effective method based on the infiltration of a 2D colloidal photonic crystal (CPC) with PDMS and their integration with a microfluidic system. We explore the changes in the white light diffraction produced by the nanostructured membranes when varying the pneumatic pressure in the microfluidics channels as a way to achieve a power-free array of pressure sensors that change their reflective colour depending on the bending produced on each sensor. The structural characterization of these membranes was performed by SEM, while the optical properties and the pressure-colour relation were evaluated via UV-Vis reflection spectrometry. Maximum sensitivities of 0.17 kPa is obtained when measuring at Littrow configuration (θ = −θ ), and close to the border of the membranes. The reflected colour change with pressure is as well monitorized by using a smartphone camera

Mechanochromic detection for soft opto-magnetic actuators

Altres ajuts: ICN2 is funded by the CERCA programme/Generalitat de Catalunya.New multi-stimuli responsive materials are required in smart systems applications to overcome current limitations in remote actuation and to achieve versatile operation in inaccessible environments. The incorporation of detection mechanisms to quantify in real time the response to external stimuli is crucial for the development of automated systems. Here, we present the first wireless opto-magnetic actuator with mechanochromic response. The device, based on a nanostructured-iron (Fe) layer transferred onto suspended elastomer structures with a periodically corrugated backside, can be actuated both optically (in a broadband spectral range) and magnetically. The combined opto-magnetic stimulus can accurately modulate the mechanical response (strength and direction) of the device. The structural coloration generated at the corrugated back surface enables to easily map and quantify, in 2D, the mechanical deflections by analyzing in real time the hue changes of images taken using a conventional RGB smartphone camera, with a precision of 0.05°. We demonstrate the independent and synergetic optical and magnetic actuation and detection with a detection limit of 1.8 mW·cm -2 and 0.34 mT, respectively. The simple operation, versatility, and cost-effectiveness of the wireless multiactuated device with highly sensitive mechanochromic mapping paves the way to a new generation of wirelessly controlled smart systems

Ag fractals formed on top of a porous TiO2 thin film

This work demonstrates the formation of Ag fractals on top of a Ag:TiO2 thin film. The dendrite-type objects emerged from a homogeneous and highly transparent Ag:TiO2 nanocomposite, via the mechanism of diffusion-limited-aggregation of Ag atoms, during heat-treatment at 500 ºC. A porous TiO2 matrix was also formed during this process, opening a wide range of possible applications, namely in sensing-based ones, together with surface enhanced spectroscopies. Furthermore, fractals incorporate a wide range of shapes and spatial scales, inducing a potentially interesting optical response, over the whole visible range, presumably related with localized surface plasmon modes with very broad spectral distribution.This research was sponsored by FEDER funds through the COMPETE program (Programa Operacional Factores de Competitividade) and by FCT (Fundação para a Ciência e a Tecnologia), under the projects UID/FIS/04650/2013 and PEstOE/MAT/UI0013/2014. A. Ferreira and C. Lopes acknowledge also FCT for grants SFRH/BPD/102402/2014 and SFRH/BD/103373/2014

Optical and structural analysis of solar selective absorbing coatings based on AlSiOx:W cermets

It is reported in this work the development and study of the optical and structural properties of a solar selective absorber cermet based on AlSiOx:W. A four-layer composite film structure, W/AlSiOx:W(HA)/AlSiOx:W(LA)/AlSiOx, was deposited on stainless steel substrates using the magnetron sputtering deposition method. Numerical calculations were performed to simulate the spectral properties of multilayer stacks with varying metal volume fraction cermets and film thickness. The chemical analysis was performed using X-ray photoelectron spectroscopy and the results show that in the high metal volume fraction cermet layer, AlSiOx:W(HA), about one third of W atoms are in the W-O oxidation state, another third in the Wx+ oxidation state and the last third in the W4+, W5+ and W6+ oxidation states. The X-ray diffractograms of AlSiOx:W layers show a broad peak indicating that both, W and AlSiOx, are amorphous. These results indicate that this film structure has a good spectral selective property that is suitable for solar thermal applications, with the coatings exhibiting a solar absorptance of 94-95.5% and emissivities of 8-9% (at 100 degrees C) and 10-14% (at 400 degrees C). The samples were subjected to a thermal annealing at 450 degrees C, in air, and 580 degrees C, in vacuum and showed very good oxidation resistance and thermal stability. Morphological characterizations were carried out using scanning electron microscopy and atomic force microscopy. Rutherford Backscattering experiments were also performed to analyze the tungsten depth profile.The authors acknowledge the support of the Portuguese Foundation for Science and Technology (FCT) in the framework of the Strategic Funding UID/FIS/04650/2013. The authors are also grateful to the financial support of FCT, POCI and PORL operational programs through the project POCI-01-0145-FEDER-016907 (PTDC/CTM-ENE/2882/2014), co-financed by European community fund FEDER. The authors also acknowledge GIST Japan for using the XPS-Kratos.info:eu-repo/semantics/publishedVersio