X-ray Photon Correlation Spectroscopy (XPCS) enables direct access to atomic-scale dynamics in disordered materials, revealing both spontaneous and X-ray-induced relaxation processes. Here, we study two compositionally similar alloy glasses near their glass transition temperatures: the phase change material (PCM) Ge15Sb85 and the non-PCM alloy Ge15Te85. Both exhibit X-ray induced atomic motion, yet with markedly different responses. Ge15Sb85 undergoes an immediate transition to a photo-induced yielding state, characterised by stationary dynamics governed solely by the absorbed dose. In contrast, Ge15Te85 shows a progressive slowing-down of the relaxation process, accompanied by a crossover from compressed to stretched exponential decay in the density autocorrelation functions. This behaviour is consistent with the emergence of liquid-like collective motion as supported by de Gennes narrowing in the wave-vector dependence of the dynamics at length scales comparable with the first sharp diffraction peak. Unlike Ge15Sb85, this alloy does not reach a stationary regime within experimental timescales, implying that the yielding transition occurs only after thousands of seconds with the available dose rate. Its response is also temperature dependent: at lower temperatures, the dynamics reflects intrinsic stress relaxation processes, whereas at higher temperatures becomes dose-controlled. These findings demonstrate that the dynamical response to X-ray excitation is not determined solely by chemical composition or bonding character, but results from the interplay between irradiation effects and structural relaxation pathways.

This study investigates the functionalization of Ge-Se-Te chalcogenide thin films using various organosilane precursors, including TEOS, OTES, APTES, ImPTES and MPTMS, to render them more hydrophilic or hydrophobic, or impart surface charges. The integrity of the deposited hybrid layers was confirmed by proton Nuclear Magnetic Resonance spectroscopy after alkaline depolymerization of test samples. The modified surfaces were characterized by Water Contact Angle measurements, Scanning Electron Microscopy and Atomic Force Microscopy. The ability of these functionalized surfaces to immobilize individual or mixed spores of two different varieties, Venturia inaequalis and Penicillium expansum, both responsible for fruit tree diseases, was evaluated. The two spore varieties behaved similarly, whether alone or mixed. Neither spore variety adhered to very hydrophilic surfaces. While the percentage of immobilized Venturia inaequalis spores increased with the surface hydrophobicity, Penicillium expansum spores were not immobilized on highly hydrophobic surfaces. Venturia inaequalis spores, characterized by a very negative zeta potential, were very well immobilized on positively charged surfaces. Consequently, the best immobilization percentage for this spore variety was obtained for the surface functionalized with ImPTES, a precursor characterized by a stable positive charge of imidazolium group. Penicillium expansum spores were less sensitive to positive charges due to their less negative zeta potential. The highest immobilization percentage for this spore variety was obtained with the precursor TEOS. One explanation could be the formation of hydrogen bonds.

The structure of the glassy GexTe1−x system, with x = 0.17, 0.21, 0.28, 0.30, and 0.45, is studied using the small-angle neutron scattering (SANS) technique. The very-low-momentum-transfer region of the diffractogram exhibits distinct behaviour depending on the germanium content. A similar conclusion is drawn from the analysis of the first diffraction peaks observed at higher angles. This system exhibits three composition regions with distinct behaviours: a first zone of low Ge content (up to about 20–25 at.%), a third zone richer in Ge (from about 30 at.% and above), and a second transitional zone between them. These changes are reflected in the parameters that govern Porod’s region, as well as in the region where the first diffraction peaks appear, corroborating previous observations made using other experimental and simulation techniques. Our study provides experimental evidence that could open up new possibilities for conducting simulations using neutron data. The results presented here show that increasing Ge content leads to a strengthening of the intermediate-range order at the expense of a weakening of the short-range order.

Agriculture challenges to reduce its environmental impact and to improve control over agricultural crops of agriculture are numerous. We develop here an optical integrated probe as potential answer to some detection challenges, based on a RIB chalcogenide waveguide. Early results have shown that the fabrication process induces sidewall roughness potentially altering the sensitivity of the probe. The numerical tool used here implements an approximation allowing to take into account sidewall roughness on propagation losses. This code is based on finite element method. Results show that sidewall roughness have a higher impact on losses for thin waveguides. Additionally, etching tests have been carried out to investigate the impact of oxygen concentration in the etching chamber over the quality of the sidewall. Results show that the more oxygen, the more important the roughness of the sidewall.

The project to which this work relates aims to propose an integrated infrared optical solution to meet the current objective of reducing the use of phytosanitary inputs in agriculture. Its main objective is to prove the feasibility of hybrid optical micro-sensors that will allow early detection of plant diseases, via the detection of spores of phytopathogenic fungi. The innovation produced should make it possible to avoid systematic preventive treatments, thanks to a better targeted decision support. Due to their transparency in the infrared range where many absorption lines of spores are located, chalcogenide glasses are materials of choice for the realization of biosensors. The specific functionalization of the chalcogenide waveguides and the multivariate analysis of the spectral measurements will make it possible to increase the sensitivity of the probes and make them selective regarding the different types of spores and to discriminate any other element detected (pollen, dust for example). We are thus currently interested in the functionalization of activated GeSeTe thin layers with monosilylated functional groups. The advantage of sol-gel chemistry is that it allows multi-functionalization in a single step. In the context of spore detection, which generally involves several sites, the immobilization of several functions is therefore be studied.

Amorphous Ge25Se55Te20 chalcogenide thin films have been functionalized with three organosilanes: (3-ami-nopropyl)triethoxysilane, tetraethoxysilane and a mixture of tetraethoxysilane and octyl-trimethoxysilane. The functionalized films have been studied by X-ray photoelectron spectrometry, providing an interesting insight of the surface modification process and chemistry. First, the calculated stoichiometric ratios oxygen/silicon, car-bon/silicon and nitrogen/silicon are in good agreement with the theory, demonstrating the effectiveness of the functionalization and relative precursors homocondensation. Secondly, the deconvolution of the 3d5/2 and 3d3/2 tellurium orbitals before and after functionalization show new oxidized environments. More specifically, the simultaneous disappearance of the bands at 573.0 eV and 583.4 eV attributed to Te-Ge and Te-Te bonds (resp.) and appearance of a Te-O environment (around 576.5 eV and 587.0 eV) strongly suggest covalent anchorage of the three precursors thanks to the formation of new Te-O-Si groups. This is the first report on tellurium anchorage of organosilane precursors onto chalcogenide surface.

We report on two selective functionalization strategies to create a chemical contrast between the active rib waveguides and the passive surrounding areas of a chalcogenide-based optical sensing system. In such configuration, the analyte could be concentrated on the waveguides and interact with the evanescent field, producing a stronger optical signature. The rib waveguides are obtained by photolithography and subsequent ion beam etching of amorphous Ge-Se-Te thin films that allow residual resist to remain above the waveguides. The first functionalization strategy consists in the reuse of the resist as a mask during the following surface modification process. It allows the functionalization of all areas around the waveguides. The second strategy consists of depositing a new sacrificial metal layer, leading to a perfect negative functionalization contrast, modifying only the waveguides. For the two strategies developed, three precursors were used. The use of a silylated fluorescein derivative allowed the validation of the protocols, with the observation of a fluorescence contrast between the functionalized and non-functionalized areas. The use of tetraethoxysilane as a hydrophilic precursor and the mixture of tetraethoxysilane and octyl-trimethoxysilane as a hydrophobic precursor created a clear contrast in wettability between the rib waveguides and the surrounding areas. A spore deposition was performed on functionalized components according to the two proposed strategies, with the two hydrophilic/hydrophobic precursors. The spore immobilization rate was increased by making the waveguides more hydrophobic, as well as by making the areas surrounding the guides more hydrophilic, demonstrating the effectiveness of our two strategies.

Peak Force Quantitative Nano-Mechanical property mapping (PF-QNM) was used to explore the nanomechanical properties of binary GeySe100−y glasses and phase-separated Agx(Ge0.25Se0.75)100−x glasses. The indentation modulus decreases when the selenium content increases in the binary glasses and when the silver content increases in phase-separated ternary glasses as a consequence of the increasing flexibility of the network. At nanoscale level, PF-QNM measurements highlighted a higher indentation modulus for the Ag-rich phase than for the Ag-poor phase, together with a decrease of both local indentation moduli with the increase of silver content in the glass. A model to gain a further insight in the mean coordination numbers and compositions of the Ag-rich and Ag-poor phases, based upon the assumption of a decoupled effect of the variations in Ag and in Ge on the mechanical properties, is described in detail. In the framework of the model, the mean coordination numbers for the Ag-rich phase and Ag-poor phase keep on decreasing when the total silver content in the glasses increases. The Ge concentration differs in Ag-rich and Ag-poor phases. When the silver content in the glass increases, the Ge concentration decreases in both phases. The result, in turn, indicates that an increase in the conductivity of the Ag-rich phase when the total silver content increases, as shown previously by C-AFM, would not be only explained by an increase in silver content but also by a softening of the network and consequently by an increase of charge carrier mobility.

We report the functionalization of chalcogenide thin films with biotinylated 12-mer peptides SVSVGMKPSPRP and LLADTTHHRPWT exhibiting a high binding affinity toward inorganic surfaces, on the one hand, and with (3-aminopropyl)triethoxysilane (APTES), on the other hand. The specific biotin moieties were used to bind streptavidin proteins and demonstrate the efficacy of the biofunctionalizated chalcogenide thin films to capture biomolecules. Atomic force microscopy provided high-resolution images of the interfaces, and water contact angle measurements gave insight into the interaction mechanisms. Fourier transform infrared spectroscopy in attenuated total reflection mode provided information about the secondary structure of the bound proteins, thanks to the deconvolution of the amide I band (1700-1600 cm-1). Following adsorption of the biotinylated peptides or APTES immobilization, a homogenous coverage of the biotin layer exhibiting very low roughness was obtained, also rendering more hydrophilic Ge-Se-Te surfaces. Subsequent capture of streptavidin depends on the functionalization approach, permitting more or less an optimal orientation of the biotin to bind streptavidin. The molecular interface layer formed on Ge-Se-Te is crucial also for retaining the native secondary structure of the protein. Altogether, our results demonstrate that both peptides and APTES were appropriate linkers to build a favorable interface on chalcogenide materials to capture proteins, opening hereby promising biosensing applications.

The leaf coverage surface is a key measurement of the spraying process to maximize spray efficiency. To determine leaf coverage surface, the development of optical micro-sensors that, coupled with a multivariate spectral analysis, will be able to measure the volume of the droplets deposited on their surface is proposed. Rib optical waveguides based on Ge-Se-Te chalcogenide films were manufactured and their light transmission was studied as a response to the deposition of demineralized water droplets on their surface. The measurements were performed using a dedicated spectrophotometric bench to record the transmission spectra at the output of the waveguides, before (reference) and after drop deposition, in the wavelength range between 1200 and 2000 nm. The presence of a hollow at 1450 nm in the relative transmission spectra has been recorded. This corresponds to the first overtone of the O–H stretching vibration in water. This result tends to show that the optical intensity decrease observed after droplet deposition is partly due to absorption by water of the light energy carried by the guided mode evanescent field. The probe based on Ge-Se-Te rib optical waveguides is thus sensitive throughout the whole range of volumes studied, i.e., from 0.1 to 2.5 μL. Principal Component Analysis and Partial Least Square as multivariate techniques then allowed the analysis of the statistics of the measurements and the predictive character of the transmission spectra. It confirmed the sensitivity of the measurement system to the water absorption, and the predictive model allowed the prediction of droplet volumes on an independent set of measurements, with a correlation of 66.5% and a precision of 0.39 μL.

Functionalizing the surface of chalcogenide films is of major interest due to the wide use of these materials in infrared integrated optics. A functionalization route via short peptides that has been already used for silicon, ZnSe and other semiconductors is applied to amorphous films of the ternary Ge-Se-Te system. The biotinylated 12-mer peptides LLADTTHHRPWT and SVSVGMKPSPRP were chosen and used to capture streptavidin. High-resolution atomic force microscopy images highlight that the 12-mer peptide LLADTTHHRPWT provides better interface layers for streptavidin molecule detection.

Nowadays, plant protection still calls on pesticides to prevent disease and pests. This use of phytosanitary inputs became a main issue in the agriculture field, due to the off-target spray particles movement that fails to reach their target when pesticides are applied to crops, these spray drops contaminate the outer regions of the treated area. This spraying loss has a negative impact on environmental, health and economic problems. One of the way to improve the spraying quality is to estimate the off-target volumes, this information could thus help farmers to optimize their planting performances. Several methods to quantify spray deposition in field conditions have been developed [1–4] such as the use Water Sensitive Paper (WSP) cards. However, these methods are time consuming and has a lack of accuracy. ∗Speaker †Corresponding author: anis.taleb-bendiab@irstea.fr ‡Corresponding author: maxime.ryckewaert@limagrain.com §Corresponding author: caroline.vigreux@univ-montp2.fr ¶Corresponding author: kribich@ies.univ-montp2.fr ‖Corresponding author: Raphael.Escalier@univ-montp2.fr ∗∗Corresponding author: ryad.bendoula@irstea.fr sciencesconf.org:nanosen-aqm:260394 The objective of this work is to create an optical sensor based on a RIB waveguide design to characterize the quantity and distribution of a liquid spray deposit. The conception idea is that we assumed that the light guidance properties of these sensors would undergo a modification when spraying droplets are present on their surface. This phenomenon results from partial evanescent wave absorption by the water, highly present in pesticides, which leads to a decrease in the transmitted intensity at the waveguide output. We firstly studied on an optical bench the influence of a droplet deposits on the waveguide using different droplet volumes (0 to 10 μl). The result obtained was a gradual decrease in the output intensity signal due to the water absorbtion of the evanescent field, and this proportionally to the droplet volume; the bigger the droplet, the greater the loss in output intensity. [5] Secondly, we performed a second test by successively adding 2.5 μl droplets alongside the waveguide to analyze their cumulative influence. We found out that the decrease in output intensity is also proportionally related to the number of droplets present on the waveguide. [5]In addition, we performed an other test on a spectral analysis bench in order to highlight the light absorption at the specific water wavelenght using the output spectrum. this test aimed to confirm the link between the volume and the absorption to certify the first approach. We proceeded to a droplet deposition on the waveguide with a volume range from 0,1 to 2.5 μl droplets to analyze the sepctra at the output. The result showed that we can see an absorption at 1450μm wavelenght wich is one of the water wavelenght absoprtion. This investigation also exposed the link between the droplet volume and the absorption rate. To conclude, these first results demonstrate the potential of RIB waveguide sensors to accurately quantify droplet deposits and can potentially be used to analyze a chemical composition of a liquid present on the waveguide surface. Our future work should focus on improving the waveguide architecture in order to estimate deposited volumes and also the number of deposited droplets.

With the aim to develop optical micro-sensors for "on-line" measurement of spray deposits on plant leaves, and thus to optimize the use of phytosanitary inputs in agriculture, straight waveguides based on GeSeTe chalcogenide layers were elaborated and their sensitivity to water droplet deposition was tested. As expected, water, the main constituent of pesticides, absorbed part of the evanescent wave of the guided light, which led to a decrease in the intensity transmitted at the output of the waveguides. Both experimental and simulation results proved that the position of the drop on the waveguide had no impact on the intensity measured at the guide outlet. At the opposite, they highlighted the correlation between the light intensity at the outlet and the volume and number of deposited droplets: the greater the volume of the drop and the greater the number of drops, the greater the decrease in intensity.

The reduction of inputs is a strategic stake for the wine industry, the main consumer of plant protection products. The development of research / experimentation and technical transfer on this topic over the past few years reflect this ambition shared by all actors. If efforts are mainly based on finding alternative products or developing decision support tools (DAOs) to reduce doses of applied products, optimizing the quality of spraying is also an important lever and can be directly mobilized by the winegrowers. The “spray deposit” is an indicator that reveals the dose received locally by the various organs of the plant that the treatment aims to protect. Thus, the “spray deposition” measure provides valuable information for optimizing the use of inputs. At present, the measurement of this surface quantity (surface covered, size of drops) is based on a constraining and tedious implementation based on artificial collectors. This operation requires to install and then retrieve all the collectors (more than a hundred in general) completely manually. Then, the analyzes are done in laboratory, which mobilizes time, manpower and consumables. Thus, automation of this measure would make it possible to acquire more references mobilizable by the manufacturers of sprayers to optimize their machines and the farmers themselves with a view to defining more precisely the optimal dose to be used thus causing a reduction in the use of plant protection products. In this context, our objective would be to develop optical sensors to characterize the quantity and distribution of a liquid spray. These optical sensors will have waveguides as basic bricks: the idea will be to analyze the impact of a liquid spray on the surface of the guides on their light guiding properties.

Chalcogenide glasses and more importantly their glass-ceramics counterparts have been an interesting but very peculiar class of thermoelectric materials, with inherently low thermal conductivity (<0.3W/mK). In this study, we report on the fabrication of glasses in the ternary system Cu-As-Te (CuxAs55-xTe45 [5x20], Cu15As85-yTey [45y70], and Cu20As80-yTey [45y65]) by melt-quenching and subsequent spark plasma sintering treatment. Their thermal and structural properties have been studied by differential scanning calorimetry and Raman spectroscopy, leading to give insights into the structural evolution of the glassy matrix. Coupling this information with the analysis of their electrical transport properties allowed us to deepen further our understanding of the compositional effect on their thermoelectric properties, and indirectly how the evolution of their electronic band structure is at play. Despite exhibiting low ZT values by themselves, Cu-As-Te glasses may still be interesting candidates for thermoelectricity through partial crystallization for which knowing the relationship between composition and properties remains essential.

In a context where the control of gases becomes important in a wide range of applications - health care, industry, housing, transportation, environment - we have in sight the realization of infrared optical micro-sensors. In particular, we wish to develop an optical micro-sensor operating at the wavelength 4.23 μm, wavelength corresponding to an absorption band of carbon dioxide, the main greenhouse gas.

In a context where the control of gases becomes important in a wide range of applications - health care, industry, housing, transportation, environment - we have in sight the realization of infrared optical micro-sensors. In particular, we wish to develop an optical micro-sensor operating at the wavelength 4.23 mu m, wavelength corresponding to an absorption band of carbon dioxide, the main greenhouse gas.The first step consists in manufacturing straight waveguides that were capable of operating at this wavelength. They are obtained by stacking and etching layers of the ternary system Ge-Se-Te. The waveguides opto-geometrical parameters such as refractive indices, thicknesses of the layers, etching depth and waveguide core width are set through a design process to obtain a single mode behaviour at 4.23 mu m. After fabrication, straight waveguides are optically characterized at lambda = 4.23 mu m on a bench dedicated to the study. The second step consists in designing circuits such as Y-junctions or Mach-Zehnder interferometers, still being able to operate at lambda = 4.23 mu m, whereas the last step consists in studying the possibility of integrating a CO2-sensitive layer to the circuits, in order to fabricate a micro-sensor.As this stage, straight waveguides were fabricated and proved to transmit light at lambda = 4.23 mu m, with propagation losses at about 1.3 dBcm(-1). Y-junctions and Mach-Zehnder interferometers are under fabrication, and possible sensitive layers are under investigation.

In a context where the control of gases becomes important in a wide range of applications - health care, industry, housing, transportation, environment, etc. - we have in sight the realization of infrared optical micro-sensors. In particular, we wish to develop an optical micro-sensor operating at the wavelength 4.26 µm, wavelength corresponding to an absorption band of carbon dioxide, the main greenhouse gas. The first step consists in manufacturing straight waveguides, but also circuits such as Y-junctions or interferometers, that are capable of operating at this wavelength. The straight waveguides and other guiding structures are obtained by stacking and etching of layers of the ternary system Ge-Se-Te, a chalcogenide system widely studied for its transparency properties in the infrared. Manufacturing objects are realized by: (i) depositing a first low refractive index Ge-Se-Te layer (buffer layer) on a Si substrate by thermal co-evaporation; (ii) depositing a second layer Ge-Se-Te characterized by a higher refractive index (guiding layer), again by thermal co-evaporation, and (iii) modifying the geometry of the second layer by laser lithography and ion beam etching. The waveguides opto-geometrical parameters such as refractive indices, thicknesses of the layers, etching depth and waveguide core width are set through a design process to obtain a single mode behavior at 4.26 µm. After fabrication, objects are optically characterized at λ = 4.26 µm on a bench dedicated to the study.