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Solid polymer electrolytes (SPEs) show tremendous potential for solid-state lithium metal batteries; however, challenges such as low ionic conductivity and poor mechanical strength hinder their progress. This study integrates Fe-MIL-101 metal organic framework into a poly(vinylidene fluoride-co-hexafluoro propylene) (PVdF-HFP)-based SPE system to address these limitations. The integration of Fe-MIL-101 offers two critical benefits: (1) interaction of inorganic Fe3+ metal centers with PVdF-HFP enables fast Li+ transport by increasing free Li+ availability in the system through Lewis acid–base interactions. (2) Fe-MIL-101 significantly improves the mechanical strength of the SPE, boosting its structural integrity. Fe-MIL-101-integrated SPE enables excellent room temperature cycling stability in solid-state Li‖LiFePO4 (LFP) full cells, retaining ∼91% capacity after 300 cycles and ∼89% capacity after 400 cycles at 0.2 C. Advanced characteristic techniques such as synchrotron-based in situ X-ray diffraction and X-ray absorption spectroscopy were employed to explore structural evolutions in the LFP cathode and the Fe-MIL-101-integrated SPE during cycling. Furthermore, improved room temperature electrochemical performance is demonstrated in solid-state Li‖LiNi0.6Mn0.2Co0.2O2 (NMC622) batteries with Fe-MIL-101-integrated SPE, retaining 91.4% capacity after 175 cycles at 0.1 C. This work highlights the effectiveness of Fe-MIL-101 in enhancing the SPE properties, paving the way for the advancement of high-performance solid-state lithium metal batteries. [ABSTRACT FROM AUTHOR] more...

Direct ethanol fuel cells (DEFCs) promise the use of ethanol as a bio‐renewable and non‐toxic fuel for energy conversion through the ethanol oxidation reaction (EOR). Well dispersed Pt3Sn and Pt nanoparticles on graphene (denoted Pt3Sn/G and Pt/G) support electrocatalysts made with alcohol reduction were tested towards EOR. The HRTEM and XRD characterizations provide the morphology and crystal phase of the Pt3Sn alloy nanoparticles, which has a uniform particle size of 2.8±0.08 nm, as is consistent with a Pt/G catalyst as reference. According to the in‐situ quick X‐ray‐absorption near‐edge structure (QXANES) spectra during an anodic scan of CV for the EOR test to explain clearly the potential‐dependent electronic state of the prepared electrocatalysts, the white‐line intensities of the Pt L3‐edge QXANES spectra and their spectral profiles vary appreciably with the electrode voltage. Moreover, Pt3Sn/G shows a better EOR performance than Pt/G because SnO2 can improve adsorption and dissociation during the oxidation by an appropriate expansion of the lattice parameters in the PtSn alloy. This work provides insight into the reaction mechanism of dissociative adsorption of ethanol on alloyed Pt surface, which has an important role in enhancing the EOR activity for a complete ethanol oxidation. [ABSTRACT FROM AUTHOR] more...

We have measured threshold photoionization spectra of benzyl+-h7, benzyl+-αd2, and benzyl+-d7 in the ground electronic state (X+ 1A1) using resonant two-photon excitation and detection of electrons by pulsed field ionization. The adiabatic ionization potentials of benzyl-h7, benzyl-αd2, and benzyl-d7 are 58 468±5 cm-1, 58 418±5 cm-1, and 58 386±5 cm-1. Excitation through a variety of vibronically mixed A 2A2–B 2B2 neutral excited states allows observation of cation vibrations of both a1 and b1 symmetries. We directly measure in-plane fundamentals and infer the frequencies of certain out-of-plane fundamentals from their involvement in combinations or overtones. By comparison with harmonic frequencies from ab initio calculations, we assign 35 of 48 observed levels in the -h7 isotopomer, 15 of 22 levels in -αd2, and 25 of 30 levels in -d7. Ab initio calculations permit a detailed comparison of the geometry, chemical bonding, and vibrational frequencies in the benzyl anion, neutral, and cation. The anion and cation, both closed-shell species, have remarkably similar geometries with relatively short exocyclic CC bond (1.371 Å and 1.372 Å, respectively) and with the aromatic ring compressed along the C2 symmetry axis. The neutral free radical has a longer exocyclic CC bond (1.413 Å) and a more nearly sixfold symmetric ring. The natural resonance theory provides bond orders and resonance-structure weights in all three species. While no single resonance structure dominates in any of the three species, the structure with an exocyclic CC double bond is significantly more important in the anion and cation than in the neutral. © 1996 American Institute of Physics. [ABSTRACT FROM AUTHOR] more...

In substituted toluenes, the potential energy barrier to internal methyl rotation and the preferred methyl conformation depend on the position of the fluorine, amino, or methyl substituents and also on the electronic state, either S0, S1, or ground state cation. We present a unified picture of the electronic factors controlling these effects. In S0 and cation, ab initio electronic structure calculations of modest scale produce rotor potentials in good agreement with experiment. The methyl group provides a sensitive probe of local ring geometry. When the geometry of the ring in the vicinity of the rotor has good local C2v symmetry, the barrier is invariably small. In S0 ortho-substituted toluenes, we use natural steric analysis to show that repulsive steric interactions between the halogen lone pair and the methyl CH bonds dominate over attractive donor–acceptor interactions to favor the pseudo-trans conformation. When steric interactions are unimportant, the key determinant of rotor barrier height is the difference in π-bond order between the two ring CC bonds nearest methyl.The barrier height is proportional to the calculated bond order difference, with slope of 950 cm-1 per bond. Attractive donor–acceptor interactions favor the conformation that places the rotor CH bond cis to the ring CC bond of higher order, analogous to the localized case of 2-methylpropene. In toluene cations, π-ionization creates a pattern of long and short ring CC bonds. Simple molecular orbital theory readily explains the coarse bond-order patterns calculated for ortho- and meta-substituted toluene cations. A localized picture of π-bonding from natural resonance theory explains more subtle details of the distribution of CC bond orders about the ring. When π-ionization places the methyl group between ring CC bonds of quite different order, a substantial barrier results. This explains the strong preference of m-fluorotoluene+ for the pseudo-cis... [ABSTRACT FROM AUTHOR] more...

Resonant two-photon ionization (R2PI) and pulsed field ionization (PFI) were used to measure S1–S0 and cation–S1 spectra of internally cold phenylsilane. We measure the adiabatic ionization potentials IP(phenylsilane)=73 680±5 cm-1, IP(phenylsilane ·Ar)=73 517±5 cm-1 and IP(phenylsilane ·Ar2)=73 359±5 cm-1. We assign many low lying torsion–vibration levels of the S1 (A 1A1) state and of X 2B1 of phenylsilane+. In both states, the pure torsional transitions are well fit by a simple sixfold hindered rotor Hamiltonian. The results for the rotor inertial constant B and internal rotation potential barrier V6 are, in S1, B=2.7±0.2 cm-1 and V6=-44±4 cm-1; in the cation, B=2.7±0.2 cm-1 and V6=+19±3 cm-1. The sign of V6 and the conformation of minimum energy are inferred from spectral intensities of bands terminating on the 3a‘1 and 3a‘2 torsional levels. In S1 the staggered conformation is most stable, while in the cation ground state the eclipsed conformation is most stable. For all sixfold potentials whose absolute phase is known experimentally, the most stable conformer is staggered in the neutral states (S0 and S1 p-fluorotoluene, S1 toluene, S1 p-fluorotoluene) and eclipsed in the cationic states (ground state toluene+ and phenylsilane+). In phenylsilane+ we estimate several potential energy coupling matrix elements between torsional and vibrational states.For small V6, the term PαPa in the rigid-frame model Hamiltonian strongly mixes the 6a’1 and 6a’2 torsional states, which mediates further torsion–vibrational coupling. In addition, the cation X 2B1 vibrational structure is badly perturbed, apparently by strong vibronic coupling with the low-lying A 2A2 state. Accordingly, ab initio calculations find a substantial in-plane distortion of the equilibrium geometry of the X 2B1 state, while the A 2A2 state is planar and symmetric. The calculations also... [ABSTRACT FROM AUTHOR] more...

In toluenelike molecules with sixfold internal rotation symmetry, three weak, Franck–Condon forbidden, pure torsional transitions m21, m30, and m41 invariably appear in S1–S0 absorption spectra. The intensities are typically 1%–5% of the allowed bands, m00 and m11. Determination of the preferred conformer in S1 as staggered or eclipsed relies on proper assignment of the upper state of the m30 band as 3a‘1 or 3a‘2 under the molecular symmetry group G12. In addition, inferences of the preferred conformer in S0 and D0 (ground state cation) from band intensities of fluorescence and threshold photoionization spectra have also relied on the same assignment. For a set of six molecules having sixfold rotor potentials, including both –CH3 and –CD3 rotors, we present experimental relative intensities for the three forbidden S1–S0 absorption bands. Within an adiabatic electronic representation, we show how a Fourier expansion of the three components of the S1–S0 electric dipole transition moment predicts relative forbidden band intensities in quantitative agreement with experiment. This fixes the assignment of the upper state of the key m30 transition as 3a‘1, establishes the preferred S1 conformer as staggered for all six molecules, and places earlier inferences of the preferred conformers in S0 and D0 on solid ground. © 1995 American Institute of Physics. [ABSTRACT FROM AUTHOR] more...

High-resolution partial-fluorescence-yield X-ray absorption and resonant X-ray emission spectra were used to characterize the temperature dependence of Sm 4f configurations and orbital/charge degree of freedom in SmB6. The variation of Sm 4f configurations responds well to the formed Kondo gap, below 140 K, and an in-gap state, below 40 K. The topological in-gap state is correlated with the fluctuating population of Sm 4f configurations that arises via carrier transfer between 3d94f6 and 3d94f5 states; both states are partially delocalized, and the mediating 5d orbital plays the role of a transfer path. Complementary results shown in this work thus manifest the importance of configuration fluctuations and orbital delocalization in the topological surface state of SmB6. [ABSTRACT FROM AUTHOR] more...

Multiferroic YMn1−xFexO3(020) (x = 0.125, 0.25, 0.50) epitaxial thin films with an orthorhombic structure (space group Pbnm) were prepared on a YAlO3(010) substrate by pulsed-laser deposition. Upon Fe substitution, the b-axis was clearly shortened, whereas the a- and c-axes were slightly lengthened based on XRD analysis. To understand the influence of orbital polarization and the Jahn–Teller effect of Mn3+ on Fe substitution and also the local octahedral-site distortion of Fe3+ in an environment of Jahn–Teller-active Mn3+ ions in YMn1−xFexO3 films, we measured the polarization-dependent X-ray absorption spectra at the Mn-L2,3 and Fe-L2,3 edges, and also simulated the experimental spectra using configuration-interaction multiplet calculations. Although Δeg for the Mn3+ ion decreased from 0.9 eV in pure YMnO3 to 0.6 eV in the half-Fe-substituted sample, a single eg electron was still strongly constrained to the d3y2−r2 orbital for all the Fe concentrations tested. The largest Δeg, 0.5 eV, for the Fe3+ ion was derived for a sample with 12.5% Fe substitution, and gradually decreased to 0.15 eV for the half-Fe-substituted sample. The local octahedral-site distortion of the Fe3+ ion inside the YMnO3 lattice was similar to that of the Mn3+ ion, whereas the Jahn–Teller distortion and GdFeO3-type distortion of the Mn3+ ion were decreased by the spherical high-spin Fe3+ ions. The combination of the experimental and theoretical data provides both profound insight into the variation of the Jahn–Teller distortion and orbital anisotropy and instructive information about the magnetic structures in these orthorhombic YMn1−xFexO3 thin films. [ABSTRACT FROM AUTHOR] more...

Quantitative structural parameters of pyrochlore Nd2Ru2O7, with temperature dependence, have been derived upon fitting XRD and EXAFS data. An anomalous expansion of the lattice parameter and the Ru–O bond length indicates a structural instability at low temperatures; in particular, an increase in the non-thermal term of the mean square fluctuation in the bond length is the evidence for a static disorder of Ru atoms. This static disorder is closely correlated with a decrease in the average Ru–O–Ru bond angle with decreasing temperature, favoring the short-range ferromagnetic coupling in the material. This ferromagnetic coupling formed thus triggered the spin frustration at low temperature when the contradictory constraints of antiferromagnetic interaction act upon the same Ru site in the corner-sharing tetrahedrons of pyrochlore Nd2Ru2O7. This study demonstrates that the spin frustration arising from the competition of ferromagnetic/antiferromagnetic interactions in pyrochlore Nd2Ru2O7 will cause structural instability especially on the atomic scale, which provides a new point of view to help understand its particular magnetic state. [ABSTRACT FROM AUTHOR] more...