Carbon-black filled rubbers are widely used materials, yet the radical processes occurring within the elastomer matrix, particularly during vulcanization, remain poorly understood. Electron Paramagnetic Resonance (EPR) spectroscopy could provide direct insight into these mechanisms by probing unpaired electrons. However, radicals associated with carbon black particles generate a very broad signal, masking the weaker and narrower contribution of the organic radicals from the elastomer phase. By employing multiharmonic EPR detection to selectively observe the organic radicals, this work enables access to these previously hidden radicals and opens new opportunities to investigate vulcanization mechanisms in reinforced rubber materials.

Usually, the conventional electron paramagnetic resonance (EPR) spectroscopy and imaging use a microwave cavity operating at X-band, i.e. with an excitation frequency of around 9.6GHz, and remains the most popular mode in the magnetic characterization of lithium batteries to date. We provide here the first low-frequency EPR investigations for monitoring the metallic lithium structures in the solid-state pouch cell batteries. We show that L-band, i.e. a microwave frequency of around 1GHz, is an invaluable method to probe in depth the electrode components through a standard pouch cell using aluminum laminated film for packaging without opening the battery. These results offer a new approach for monitoring the nucleation of micrometric and sub-micrometric lithium particles such as dendritic lithium structures which is an important step in the development of reliable solid-state batteries.

Monitoring in real time and operating condition the graphite (de)lithiation process and the nucleation of undesired submicrometric metallic lithium aggregates in aluminum-laminated pouch cell lithium-ion batteries is challenging. In an industrial context, we performed an operando L-band electron paramagnetic resonance (EPR) investigation of Li(Ni0.8Co0.15Al0.05)O2-LiFePO4 (10-90 wt %) versus graphite (NCA-LFP parallel to graphite) Li-ion batteries assembled inside a flexible aluminum-laminated pouch. L-band EPR reveals valuable information about the coexistence of lithiated graphite species and lithium deposits in a nondestructive way, i.e., without opening the pouch. An EPR spectrum exhibiting a g-value near the free electron g-value of 2.0026 is found, as expected for lithiated graphite species (Li X C6; 0 <= x <= 1). After 125 galvanostatic cycles, the voltage profile indicates a capacity loss of 60% likely caused by degradation mechanisms. EPR measurements, combining 1st harmonic and 2nd harmonic detection modes, provide evidence of an additional sharp signal displaying, in the limit of resolution of the L-band, a g-value similar to that of Li X C6. The measured line width of this additional peak appears much smaller than the Li X C6 line (by a factor of 10), and its asymmetrical ratio A/B is around 1.8, as expected for nondendritic metallic lithium deposits. The correlation between spatial-spatial and spectral-spatial EPR imaging at the L-band helped us locate both species inside the pouch cell.

The degradation behaviors of the encapsulant and the imbedded additives significantly determine the reliability of solar modules. Nevertheless, a link between the degradation of the encapsulant, including the additive interactions, and the longevity of the overall module is rarely established until now. Herein, mini‐modules containing ethylene‐vinyl acetate copolymer (EVA) as encapsulant are subject to damp heat (DH) or ultraviolet (UV) weathering based on IEC 61215. Macroscopically, the degradation under both weathering types characterized by I–V measurements and electroluminescence (EL) measurements is diverging in dependence on the used stressor. Using electron paramagnetic resonance and orbitrap mass spectrometry, it is shown that deacetylation of the EVA occurs significantly for both types of weathering. In the case of DH, however, the mechanism of action of the UV stabilizer is hindered, so that strong encapsulant degradation is observed despite a lower energy input in comparison with UV. Furthermore, the produced acetic acid under DH weathering leads to the observed reduction in EL, an increase in series resistance, and, a reduction of the performance of the modules. The work carried out shows that the degradation of the solar modules is strongly dependent on the behavior of the UV stabilizer.

We have investigated metallic lithium particle nucleation following lithiation and delithiation steps of the graphite electrode using X-band electron paramagnetic resonance (EPR). Metallic lithium aggregates like dendrites and/or filaments which are formed during electrochemical cycling on the graphite anode are complex structures which may lead to internal short-circuit and safety issues. Understanding and following, in real conditions, this nucleation process is necessary to improve the development of Li-ion batteries. The complexity to detect metallic lithium structures inside Li-ion batteries depends on the number of EPR lines and their linewidth. The presence of lithiated graphite phases affects the detection of micrometric Li-metal elements. Herein, we report a new approach using cw-EPR (continuous-wave EPR) spectroscopy and imaging, combining the first- and second-harmonic detection schemes to provide evidence for the metallic lithium aggregate nucleation in these negative electrodes. Although the first harmonic gives all the EPR signals present in the sample, it is found that the second-harmonic EPR signal is mainly sensitive to metallic lithium depositions.

Advanced EPR techniques such as ENDOR and pulsed EPR are used to investigate the enigmatic black coatings of ancient Egyptian mummies, consisting in a complex and heterogeneous mixtures of conifer resins, wax, fat and oil with variable amounts of bitumen. Natural bitumen always contains traces of vanadyl porphyrin complexes that we used here as internal probes to explore the nanoscale environment of V4+ ions in these black coatings by hyperfine spectroscopy. Four types of vanadyl porphyrins were identified from the analysis of 14N hyperfine interactions. Three types (referred to as VO-P1, VO-P2 and VO-P3) are present in natural bitumen from the Dead Sea, among which VO-P1 and VO-P2 are also present in black coatings of mummies. The absence of VO-P3 in mummies, which is replaced by another complex VO-P4, may be due to its transformation during preparation of the black matter for embalming. Analysis of 1H hyperfine interaction shows that bitumen and other natural substances are intimately mixed in these black coatings, with bitumen aggregate sizes not larger than a few nanometres.

Small TiO2 contents in the slag-glass significantly reduce their cementitious reactivity. We investigated the role of Ti in the glass network and its influence on slag-glass dissolution. XANES and EPR analysis showed that 67% of Ti was present as Ti(IV) with about 70% in Ti-[5] and 30% in Ti-[4] coordination, and 33% as Ti(III). The presence of Ti had only a minor impact on initial dissolution rates at pH 11 (R asymptotic to 10(-6) molglass.s(-1).m(-2)). During dissolution, Ti accumulated in an amorphous layer at the glass-surface. Ti-coordination in this layer was 50% Ti-[5] and 50% Ti-[6]. At pH 11, the layer was mainly composed of TiO2 (66 wt%), but intermixed with a hydrotalcite-like phase at pH 13. The loss of cementitious reactivity in the presence of Ti appears to be not only due to stabilization of the glass structure but also to the formation of a Ti-rich surface-layer, that may become passivating.

Advanced EPR techniques such as ENDOR and pulsed EPR are used to investigate the enigmatic black coatings of ancient Egyptian mummies, consisting in a complex and heterogeneous mixtures of conifer resins, wax, fat and oil with variable amounts of bitumen. Natural bitumen always contains traces of vanadyl porphyrin complexes that we used here as internal probes to explore the nanoscale environment of V4+ ions in these black coatings by hyperfine spectroscopy. Four types of vanadyl porphyrins were identified from the analysis of 14N hyperfine interactions. Three types (referred to as VO-P1, VO-P2 and VO-P3) are present in natural bitumen from the Dead Sea, among which VO-P1 and VO-P2 are also present in black coatings of mummies. The absence of VO-P3 in mummies, which is replaced by another complex VO-P4, may be due to its transformation during preparation of the black matter for embalming. Analysis of 1H hyperfine interaction shows that bitumen and other natural substances are intimately mixed in these black coatings, with bitumen aggregate sizes not larger than a few nanometres.

Monitoring the formation of dendrites or filaments of lithium is of paramount importance for Li-based battery technologies, hence the intense activities in designing in situ techniques to visualize their growth. Herein we report the benefit of correlating in situ electron paramagnetic resonance (EPR) spectroscopy and EPR imaging to analyze the morphology and location of metallic lithium in a symmetric Li/LiPF 6 /Li electrochemical cell during polarization. We exploit the variations in shape, resonance field and amplitude of the EPR spectra to follow, operando, the nucleation of sub-micrometric Li particles (narrow and symmetrical signal) that conjointly occurs with the fragmentation of bulk Li on the opposite electrode (asymmetrical signal). Moreover, in situ EPR correlated spectroscopy and imaging (spectral-spatial EPR imaging) allows the identification (spectral) and localization (spatial) of the sub-micrometric Li particles created by plating (deposition) or stripping (altered bulk Li surface). We finally demonstrate the possibility to visualize, via in situ EPR imaging, dendrites formed through the separator in the whole cell. Such a technique could be of great help in mastering the Li-electrolyte interface issues that plague the development of solid-state batteries.

The black matter employed in funeral context by ancient Egyptian is a complex mixture of plant-based compounds with variable amounts of bitumen. Asphaltene, the most resistant component of bitumen, contain Vanadyl porphyrins and carbonaceous radicals which can be used as paramagnetic probes to investigate embalming materials without sample preparation. Electron Paramagnetic Resonance (EPR) at X-band, combining in-phase and out-of-phase detection schemes, provides new information in a non-destructive way about the presence, the origin, and the evolution of bitumen in these complex materials. It is found that the relative EPR intensity of radicals and vanadyl porphyrins is sensitive to the origin of the bitumen. The presence of non-porphyrinic vanadyl complexes in historical samples is likely due to the complexation of VO2+ ions by carboxylic functions at the interface between bitumen and other biological components of the embalming matter. The absence of such oxygenated vanadyl complex in natural bitumen and in one case of historical human mummy acquired by a museum in the 19th century reveals a possible, non-documented, ancient restoration of this mummy by pure bitumen. The linear correlation between in-phase and out-of phase EPR intensities of radicals and vanadyl porphyrins in balms and in natural bitumen, reveals a nanostructuration of radicals and vanadyl porphyrin complexes, which was not affected by the preparation of the balm. This points to the remarkable chemical stability of paramagnetic probes in historical bitumen in ancient Egypt.

Monitoring the formation of dendrites or filaments of lithium is of paramount importancefor Li-based battery technologies, hence the intense activities in designing in situ techniquesto visualize their growth. Herein we report the benefit of correlating in situ electron para4 magnetic resonance (EPR) spectroscopy and EPR imaging to analyze the morphology andlocation of metallic lithium in a symmetric Li/LiPF6/Li electrochemical cell during polariza6 tion. We exploit the variations in shape, resonance field and amplitude of the EPR spectrato follow, operando, the nucleation of sub-micrometric Li particles (narrow and symmetricalsignal) that conjointly occurs with the fragmentation of bulk Li on the opposite electrode(asymmetrical signal). Moreover, in situ EPR correlated spectroscopy and imaging (spectral10 spatial EPR imaging) allows the identification (spectral) and localization (spatial) of the sub11 micrometric Li particles created by plating (deposition) or stripping (altered bulk Li surface).We finally demonstrate the possibility to visualize, via in situ EPR imaging, dendrites formedthrough the separator in the whole cell. Such a technique could be of great help in masteringthe Li-electrolyte interface issues that plague the development of solid-state batteries.

Nuclear magnetic resonance is one of the rare techniques able to probe selectively the ions inside the nanoporous network in supercapacitor devices. With a magnetic resonance imaging method able to detect all ions (adsorbed and nonadsorbed), we record one-dimensional concentration profiles of the active ions in supercapacitors with an electrode configuration close to that used in industry. Larger anionic concentration changes are probed upon charge and discharge in a carbide-derived carbon (CDC) with micropores smaller than 1 nm compared to a conventional nanoporous carbon (CC) with a larger distribution of pore sizes, up to 2 nm. They highlight the increased interaction of the anions with CDC and provide a better understanding of the enhanced capacitance in CDC-based supercapacitors.

We have investigated the charge ordering phase of the quasi-one-dimensional quantum antiferromagnet (TMTTF)2X (X = SbF6, AsF6, and PF6) using high-fields/frequency electron paramagnetic resonance. In addition to the uniform displacement of the counteranions involved in the charge-order phase, we report the existence of a superlattice between the spin chains in the direction c, caused by the space modulation of the charge order. When the field is high enough, the magnetic decoupling of the spin chains allows us to estimate the interaction between the chains, J c < 1 mK, three orders of magnitude lower than expected from the mean field theory.

The multilevel system 55 Mn 2+ is used to generate two pseudoharmonic level systems, as representations of the same electronic sextuplet at different nuclear spin projections. The systems are coupled using a forbidden nuclear transition induced by the crystalline anisotropy. We demonstrate Rabi oscillations between the two representations in conditions similar to two coupled pseudoharmonic quantum oscillators. Rabi oscillations are performed at a detuned pumping frequency which matches the energy difference between electronuclear states of different oscillators. We measure a coupling stronger than the decoherence rate to indicate the possibility of fast information exchange between the systems.

Ce travail de these porte sur l'etude par la resonance paramagnetique electronique (RPE) des sels a transfert de charge quasi-unidimensionnels (TMTTF)$ {2}$X (X=AsF$ {6}$, PF$ {6}$, SbF$ {6}$), materiaux modeles de chaines de spins quantiques. Tout d'abord, nous avons examine en onde continue et sur une large gamme de temperature et de frequence, la phase d'ordre de charge deja observee dans ces materiaux en dessous de la temperature T$ {CO}$. Nous avons mis en evidence deux nouveaux phenomenes a T < T$ {CO}$: la rotation des axes principaux du facteur g et une modification structurale liee a un dedoublement de la maille cristallographique. Un calcul de chimie quantique a ete realise a l'aide de la methode DFT confirmant nos resultats experimentaux. Dans la seconde partie de ces travaux de these, nous avons presente les resultats obtenus par RPE en onde continue et en onde pulsee sur l'etude des defauts correles dans les systemes a chaines de spins. En onde continue, nous avons detecte pour la premiere fois une raie RPE fine a basse temperature, suggerant la presence de defauts correles ayant les caracteristiques de solitons. Les mesures par RPE pulsee nous ont permis d'observer les premieres oscillations de Rabi de solitons pieges et de determiner leur caractere robuste. Ces derniers resultats offrent une approche alternative aux qubits a base de spins pour le traitement de l’information quantique.

Most of qubit systems known to date are isolated paramagnetic centres in magnetically diluted samples since their dilution allows to considerably weaken the dipole-dipole inter-qubit interaction and thus to prevent the decoherence. Here we suggest an alternative approach for spin qubits which are built on spin S = 1/2 defects in magnetically concentrated strongly correlated systems - spin chains. The corresponding qubits are made of spin solitons resulting from local breaking of transitional symmetry associated with point-defects. We provide the first evidence for coherence and Rabi oscillations of spin solitons in isotropic Heisenberg chains, simple antiferromagnetic-Ńeel or spin-Peierls, proving that they can be manipulated as single spin S = 1/2. The entanglement of these many-body soliton states over macroscopic distances along chains gives rise to networks of coupled qubits which could easily be decoupled at will in extensions of this work.

C-doped Mn5Ge3 compound is ferromagnetic at temperature up to 430K. Hence it is a potential spin injector into group-IV semiconductors. Segregation and diffusion of Mn at the Mn5Ge3/Ge interface could severely hinder the efficiency of the spin injection. To avoid these two phenomena we investigate the growth of Mn5Ge3 and C-doped Mn5Ge3 films on Ge(111) substrates by molecular beam epitaxy at room-temperature. The reactive deposition epitaxy method is used to deposit these films. Reflection high energy electron diffraction, X-ray diffraction analysis, transmission electron microscopy and atomic force microscopy indicate that the crystalline quality is very high. Magnetic characterizations by superconducting quantum interference device and ferromagnetic resonance reinforce the structural analysis results on the thin film quality.

We have performed a comprehensive EPR investigation of the quasi-one-dimensional organic systems (TMTTF)2X with centrosymmetrical anions X (X = SbF6, AsF6, and PF6). We observe a strong rotation of g-factor principal axes when the temperature decreases below charge-ordering temperature TCO. The possible origin of this rotation is analyzed on the basis of quantum chemical calculations performed using density functional theory method. A good agreement between theory and experiment is found.