Institut Nanosciences et Cryogénie

Abstract The catalytic hydrogen‐isotope exchange (HIE) of unactivated C(sp 3 )─H bonds remains a formidable challenge, relevant for the synthesis of high‐purity high‐value perdeuterated NMR solvents such as pentane or tetrahydrofuran. Existing methods primarily rely on precious metal‐based catalysts (eg. Ir, Ru) under homogeneous conditions. In pursuit of more sustainable alternatives, we report the synthesis of the heterobimetallic complex [Ta(CH 2 t Bu) 2 (μ‐CH t Bu) 2 CoCp*], 1 , which is used for the preparation of a novel silica‐supported tantalum–cobalt heterobimetallic catalyst through Surface OrganoMetallic Chemistry (SOMC). This Ta/Co material demonstrated exceptional catalytic efficiency in perdeuterating pentane under mild conditions (room temperature, < 1 bar D 2 , 1 mol% cat.), outperforming both the Ta monometallic and the noble‐metal based Ta/Ir heterobimetallic analogues. Furthermore, we took profit of the complementary arene HIE and deuterogenation activities of the Ta/M (M = Ir, Co) catalysts to develop a tandem catalytic synthetic strategy for the efficient preparation of perdeuterated tetrahydrofuran from furan, achieving up to 94% total deuterium incorporation. This novel catalytic system offers several key advantages such as a) mild reaction conditions, b) atom‐efficient use of D 2 as the deuterium source, and c) simplified handling, allowing for the recovery of pure deuterated solvent via simple condensation, not hampered by the use of solvents nor additives.

The SAFARI-lite instrument on the SALTUS mission with its large 14 meter diameter aperture, will present the astronomical community with an unprecedented observational capability providing extremely sensitive FarIR spectroscopy at high spatial resolution. With the combination of SALTUS’ large collecting area and an array of sensitive Kinetic Inductance Detectors (KIDs) in a compact grating spectrometer configuration the SAFARI-lite instrument will generate R~300 resolution 34-230 μm spectra reaching sensitivities of order 10-20 W/m2 (5σ/1 hour) – an observing capabilityy in the Far Infra-Red domain with both spatial resolution and sensitivity at levels comparable to JWST. The instrument will provide both point source optimized spectroscopy observing modes, as well as spectroscopic imaging for small fields. With this breakthrough capability astronomers will be able to fully address many fundamental astrophysical issues like understanding the evolution of galaxies over cosmic time, following the distribution and role of water in the evolution those galaxies, and unveiling the formation history of planetary systems in general and our own solar system in particular.

A cooperative NHC/nickel catalytic methodology has been developed for the synthesis of ketones employing aromatic aldehydes and tertiary alkyl iodides. All key steps of the postulated catalytic cycle were validated with comprehensive stoichiometric and electrochemical studies, including reduction of NiII by the deprotonated Breslow intermediate, Ni0 promoted halogen-atom abstraction to generate transient tertiary alkyl radicals, and coupling between the latter with the persistent acyl thiazolium radical intermediate. Such a broadly proposed and accepted, yet elusive, acyl thiazolium radical intermediate has been isolated and studied by a single-crystal X-ray diffraction study.

Electrical stimulation has been used successfully for several decades for the treatment of neurodegenerative disorders, including motor disorders, pain, and psychiatric disorders. These technologies typically rely on the modulation of neural activity through the focused delivery of electrical pulses. Recent research, however, has shown that electrically triggered neuromodulation can be further enhanced when coupled with optical stimulation, an approach that can benefit from the development of novel electrode materials that combine transparency with excellent electrochemical and biological performance. In this study, we describe an electrochemically modified, nanostructured indium tin oxide/poly(ethylene terephthalate) (ITO/PET) surface as a flexible, transparent, and cytocompatible electrode material. Electrochemical oxidation and reduction of ITO/PET electrodes in the presence of an ionic liquid based on d-glucopyranoside and bistriflamide units were performed, and the electrochemical behavior, conductivity, capacitance, charge transport processes, surface morphology, optical properties, and cytocompatibility were assessed in vitro. It has been shown that under selected conditions, electrochemically modified ITO/PET films remained transparent and highly conductive and were able to enhance neural cell survival and neurite outgrowth. Consequently, electrochemical modification of ITO/PET electrodes in the presence of an ionic liquid is introduced as an effective approach for tailoring the properties of ITO for advanced bio-optoelectronic applications.

The implementation of Artificial Neural Networks (ANNs) using analog Non-Volatile Memories (NVMs) for synaptic weights storage promises improved energy-efficiency and higher density compared to fully-digital implementations. However, NVMs are prone to variability, resulting in a degradation of the accuracy of ANNs. In this paper, a general methodology to evaluate and enhance the accuracy of neural networks implemented with non-ideal multi-level NVMs is presented. A hardware fault model distinguishing two types of errors, namely static and dynamic, capturing the variability of NVMs is proposed. Considering various neural networks, it is shown that error-aware training highly increases the robustness to errors compared to a standard, error-agnostic, training. Moreover, Recurrent NNs (RNNs) and Spiking NNs (SNNs) are found to be inherently more robust to dynamic errors than Convolutional NNs (CNNs). In addition, new insights on the adaptability of neural networks to noisy multi-level NVMs are presented, which could further improve their robustness in this context. The methodology aims at providing tools for hardware-software co-design, paving the way for a broader use of multi-level NVM-based synapses.

We report on an extensive experimental study of the low-temperature--high-field corner of the $H\text{\ensuremath{-}}T$ phase diagram in FeSe using high-sensitivity specific heat $C$ measurements. Indeed, the superconducting gap and Fermi and Zeeman energies are surprisingly close in this compound, possibly leading to the existence of different superconducting phases as well as Lifshitz transitions in the electronic structure. The nature of this part of the phase diagram hence remains debated, and we show here that two distinct anomalies are visible in $C(H)$ (below $\ensuremath{\sim}3$ K): a (smeared) jump at the superconducting transition and a kink in $C(H)$. This second structure lies either below (for $H$ close to the $ab$ plane) or above (for field orientations close to the $c$ direction) the superconducting transition, indicating that it is most probably related to a field-induced change in the electronic structure. Moreover, quantum oscillations are clearly observed below $\ensuremath{\sim}2$ K, and $C(H)$ can be well described by the Lifshitz-Kosevich formula for fields both above and below the kink (with an effective mass ${m}^{*}\ensuremath{\sim}4{m}_{e}$ and a frequency $F\ensuremath{\sim}200$ T, in good agreement with the values previously inferred from magnetotransport measurements for the hole sheet).

We report the isolation and study of dimers stemming from popular thiazol-2-ylidene organocatalysts. The model featuring 2,6-di(isopropyl)phenyl (Dipp) N-substituents was found to be a stronger reducing agent (Eox = -0.8 V vs SCE) than bis(thiazol-2-ylidenes) previously studied in the literature. In addition, a remarkable potential gap between the first and second oxidation of the dimer also allows for the isolation of the corresponding air-persistent radical cation. The latter is an unexpected efficient promoter of the radical transformation of α-bromoamides into oxindoles.

Barium disilicide (BaSi2), composed of Earth-abundant and nontoxic elements, is a promising material for thin-film solar cells. The control of carrier type and carrier concentration by impurity doping is particularly important for the application of BaSi2 to solar cells. However, the presence of defects in semiconductors such as BaSi2 may have a significant impact on the electrical and optical properties of solar cells. In this study, we chose boron to act as a p-type impurity in BaSi2 and studied boron-related defects using the Quantum Espresso method with density functional theory. The formation energy of interstitial boron defects was found to be lower than that of boron in Si vacancy sites. The hyperfine coupling constants of 137Ba with antisite boron defects (BSi) are very localized and differ significantly from those of 137Ba with interstitial boron defects (Bi). This suggests that neutral BSi and Bi can be identified by electron paramagnetic resonance.

AlxIn1−xN ternary semiconductors have attracted much interest for application in photovoltaic devices. Here, we compare the material quality of AlxIn1−xN layers deposited on Si with different crystallographic orientations, (100) and (111), via radio-frequency (RF) sputtering. To modulate their Al content, the Al RF power was varied from 0 to 225 W, whereas the In RF power and deposition temperature were fixed at 30 W and 300 °C, respectively. X-ray diffraction measurements reveal a c-axis-oriented wurtzite structure with no phase separation regardless of the Al content (x = 0–0.50), which increases with the Al power supply. The surface morphology of the AlxIn1−xN layers improves with increasing Al content (the root-mean-square roughness decreases from ≈12 to 2.5 nm), and it is similar for samples grown on both Si substrates. The amorphous layer (~2.5 nm thick) found at the interface with the substrates explains the weak influence of their orientation on the properties of the AlxIn1−xN films. Simultaneously grown AlxIn1−xN-on-sapphire samples point to a residual n-type carrier concentration in the 1020–1021 cm−3 range. The optical band gap energy of these layers evolves from 1.75 to 2.56 eV with the increase in the Al. PL measurements of AlxIn1−xN show a blue shift in the peak emission when adding the Al, as expected. We also observe an increase in the FWHM of the main peak and a decrease in the integrated emission with the Al content in room-temperature PL measurements. In general, the material quality of the AlxIn1-xN films on Si is similar for both crystallographic orientations.

The EDELWEISS collaboration reports on the search for Dark Matter (DM) particle interactions via Migdal effect with masses between $32$ MeV$\cdot$c$^{-2}$ to $2$ GeV$\cdot$c$^{-2}$ using a $200$ g cryogenic Ge detector sensitive to simultaneously heat and ionization signals and operated underground at the Laboratoire Souterrain de Modane in France. The phonon signal was read out using a Transition Edge Sensor made of a NbSi thin film. The detector was biased at $66$ V in order to benefit from the Neganov-Trofimov-Luke amplification and resulting in a resolution on the energy of electron recoils of $4.46$ eV$_{ee}$ (RMS) and an analysis threshold of $30$ eV$_{ee}$. The sensitivity is limited by a dominant background not associated to charge creation in the detector. The search constrains a new region of parameter space for cross-sections down to $10^{-29}$ cm$^2$ and masses between $32$ and $100$ MeV$\cdot$c$^{-2}$. The achieved low threshold with the NbSi sensor shows the relevance of its use for athermal-phonon sensitive devices for low-mass DM searches.