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Glassy magnetic behavior has been observed in a wide range of crystalline magnetic materials called spin glass. Here, we report spin glass behavior in a structural glass of a magnetic ionic liquid, C4mimFeCl4. Magnetization measurements demonstrate that an antiferromagnetic ordering occurs at TN = 2.3 K in the crystalline state, while a spin glass transition occurs at TSG = 0.4 K in the structural glass state. In addition, localized magnetic excitations were found in the spin glass state by inelastic neutron scattering, in contrast to spin-wave excitations in the ordered phase of the crystalline sample. The localized excitation was scaled by the Bose population factor below TSG and gradually disappeared above TSG. This feature is highly reminiscent of boson peaks commonly observed in structural glasses. We suggest the “magnetic” boson peak to be one of the inherent dynamics of a spin glass state.

A novel Sr2+ fluorescent probe, N-(2-hydroxy-3-(1H-benzimidazol-2-yl)-phenyl)-1-aza-18-crown-6-ether (BIC), was synthesized and its fluorescence properties, equilibria, and local structure in solution were studied in detail. The fluorescence intensity of BIC in DMSO was enhanced selectively upon addition of Sr2+ but not Na+, K+, Mg2+, Ca2+, and Ba2+. To employ this rather hydrophobic BIC probe in aqueous media, a sodium laurate (LaNa) micellar solution was used as a good solvent. The detection limit of said LaNa micelle-BIC system (2.02 μM) is lower than that of the H2O system (309 μM), but higher than that of the DMSO system (0.04 μM). Therefore, it is clear that the LaNa micelles have an effect on the detection of Sr2+ by BIC in aqueous solutions. Further structural studies by extended X-ray absorption fine structure and speciation analyses revealed that BIC undergoes complexation equilibria corresponding to the formation of [Sr(BIC)]+ species in all solution types. It was concluded that the changes in the Sr2+-BIC fluorescence in solution are attributed to the formation of such [Sr(BIC)]+ complexes.

A large background scattering originating from the sample matrix is a major obstacle for fine-structure analysis of a nanometric layer buried in a bulk material. As polarization analysis can decrease undesired scattering in a neutron reflectivity (NR) profile, we performed NR experiments with polarization analysis on a polypropylene (PP)/perhydropolysilazane-derived SiO2 (PDS)/Si substrate sample, having a deep-buried layer of SiO2 to elucidate the fine structure of the nano-PDS layer. This method offers unique possibilities for increasing the amplitude of the Kiessig fringes in the higher scattering vector (Qz) region of the NR profiles in the sample by decreasing the undesired background scattering. Fitting and Fourier transform analysis results of the NR data indicated that the synthesized PDS layer remained between the PP plate and Si substrate with a thickness of approximately 109 Å. Furthermore, the scattering length density of the PDS layer, obtained from the background subtracted data appeared to be more accurate than that obtained from the raw data. Although the density of the PDS layer was lower than that of natural SiO2, the PDS thin layer had adequate mechanical strength to maintain a uniform PDS layer in the depth-direction under the deep-buried condition.

We combined the deuterium labeling and neutron reflectivity techniques to determine the fine structure of the electric double layer structure in an imidazolium ionic liquid (IL). For this, a simple and large scale deuteration method for imidazolium ILs was developed, where the deuteration level can be systematically controlled.

A quantitative analysis method for monitoring liquid penetration into nanosize thin layer samples was developed using neutron reflectivity (NR). In this study, we synthesized a partly deuterated ionic liquid (IL) and studied its penetration behavior in perhydropolysilazane-derived silica (PDS) thin layers using NR. The penetration depth of the deuterated IL was estimated to be 184 A for the 24 h IL-submerged sample and 410 A for the 72 h IL-submerged sample. In addition, using the obtained penetration depth, an apparent penetration rate constant (kapp) of 0.024 h−1 was evaluated. Thus liquid penetration behavior in PDS thin layer samples can be quantitatively discussed by evaluation of kapp using NR analysis.

The multilayer structure of Fe/Si and Fe/Ge systems fabricated by ion beam sputtering (IBS) was investigated using X-ray and polarized neutron reflectivity measurements and scanning transmission electron microscopy with energy-dispersive X-ray analysis. The obtained result revealed that the incorporation of sputtering gas particles (Ar) in the Ge layer gives rise to a marked reduction in the neutron scattering length density (SLD) and contributes to the SLD contrast between the Fe and Ge layers almost vanishing for spin-down neutrons. Bundesmann et al. (2015) have shown that the implantation of primary Ar ions backscattered at the target is responsible for the incorporation of Ar particles and that the fraction increases with increasing ion incidence angle and increasing polar emission angle. This leads to a possibility of fine-tuning of the SLD for the IBS, which is required to realize a high polarization efficiency of a neutron polarizing supermirror. Fe/Ge polarizing supermirror with m = 5 fabricated under the same condition showed a spin-up reflectivity of 0.70 at the critical momentum transfer. The polarization was higher than 0.985 for the q z range where the correction for the polarization inefficiencies of the beamline works properly. The result of the polarized neutron reflectivity measurement suggests that the “magnetically-dead” layers formed at both sides of the Fe layer, together with the SLD contrast, play a critical role in determining the polarization performance of a polarizing supermirror.

2-(2'-Hydroxyphenyl)benzimidazole derivatives (X-HBIs), modified by various substituents X (X=H, CH3, OH, OCH3, NO2, NHCOCH3, NH2, N(CH3)2), were synthesized and their fluorescent behaviors and equilibriums in aqueous solution were studied. Strong fluorescence attributed to the tautomer emission was observed in aqueous solution at pH 7.4. The fluorescence intensities of the X-HBIs were enhanced selectively by addition of Zn(2+) but not by addition of Na(+), K(+), Mg(2+), Ca(2+), Mn(2+), Fe(2+), Co(2+), Ni(2+), and Cu(2+). Additionally, the effective ratiometric fluorescence response to Zn(2+) addition was observed in 5-NH2-HBI and 5-N(Me)2-HBI. The pH-titration and speciation studies proved that the X-HBIs have two or three protonation equilibriums and one complexation equilibrium corresponding to the formation of the [Zn(X-HBI)](+) complex. Further structural studies using extended X-ray absorption fine structure analyses and density functional theory calculations identified the dominant Zn(2+) species as the [Zn(HBI)(H2O)3](+) complex in aqueous solution. Based on the substituent effect on the fluorescence properties of X-HBIs and their Zn(2+) complexes in aqueous solution, the maximum fluorescence excitation and fluorescence wavelengths of both the tautomeric form and the Zn(2+) complexes were dependent on the Hammett substituent constants of X, which was attributed to the change of the π-π* energy gap of HBI by introduction of the substituent.

We present evidence that the organic/third phase transition, as may be observed in the Plutonium Uranium Reduction EXtraction process (PUREX) at high metal loading, is an unusual transition between two isotropic, bi-continuous micro-emulsion phases. As this system contains so many components, however, we seek first to investigate the properties of a simpler system, viz. the related metal-free, quaternary system of water/n-dodecane/nitric acid/tri-butyl phosphate (TBP). Under appropriate conditions, this system exhibits three coexisting phases, namely the light organic phase, the third phase and the aqueous phase. In this paper, we focus on the two phase coexistence between the light organic and the third phase. Using Gibbs Ensemble Monte Carlo (GEMC) simulations, we find phase-coexistence between a phase rich in nitric acid and dilute in n-dodecane (the third phase) with a phase more dilute in nitric acid and rich in n-dodecane (the light organic phase). The compositions and densities of these two co-existing phases are in good agreement with experiment. Because the systems are dense and the molecules involved are not simple, the particle exchange rate in the GEMC simulation can be rather low. To show that the system, at a composition intermediate between that of the observed third and organic phases, is indeed unstable with respect to phase separation, we use the Bennett acceptance ratio method to calculate the Gibbs energies of the homogeneous phase and the weighted average of the two co-existing phases, where the compositions of these phases were taken both from GEMC and from experiment. Both demixed states have a statistically significant lower Gibbs energy than the uniform, mixed phase, providing confirmation that GEMC correctly predicts phase separation. Snapshots from the simulations as well as the cluster analysis of the organic and third phases reveal structures akin to bi-continuous micro-emulsion phases, where the polar species reside within a mesh whose surface consists of amphiphilic TBP molecules. The non-polar n-dodecane molecules are outside this mesh. The large-scale structural differences between the two phases lie solely in the dimensions of the mesh. Evidence for the correctness of these structures comes from small-angle X-ray scattering (SAXS), where the profiles obtained for both the organic and third phases agree well with those calculated from simulation. Finally we look at the microscopic structures of the two phases. In the organic phase, the basic motif is that of one nitric acid molecule hydrogen bonded to a TBP. In the third phase, the most common structure was that of the hydrogen bonded chain TBP–HNO3–HNO3. A cluster analysis provides evidence that the TBP forms an extended, connected network in both phases. Studies of the effects of metal ions on these systems will be presented elsewhere, but suffice it to say here that these ions do not change the basic bi-continuous structure of the phases. The metal ions reside inside the mesh along with the other polar molecules.

The structure of perhydropolysilazane (PHPS)-derived silica (PDS) waterproof thin layers synthesized by curing at 60 °C for 1 h and allowed to stand for 48 h at 20 °C on various kinds of substrates was studied. Neutron reflectivity (NR) analysis suggested that uniform PDS thin layers were synthesized on the substrates, and the density of the layers varied depending on the type of substrate. Additionally, since the change in PDS density is correlated with the pKa value of the OH group on the substrate, it can be suggested that the acidity of the substrate would be one of the main factors determining the density of the coated PDS thin layers. For the water penetration structure study, NR analysis revealed that the depth of water penetration into the PDS layers was below 500 A, and the hydration number of the SiO2 molecule was estimated to be 8.0–9.0. From these results, we concluded that water penetration occurred by the formation of water-pool structures in the PDS layers, and the randomly formed nano-air holes lead to a reduction in the probability of water penetration into the deep regions of the PDS layers.

A refined model for tri-n-butyl phosphate (TBP), which uses a new set of partial charges generated from our ab initio density functional theory calculations, has been proposed in this study. Molecular dynamics simulations are conducted to determine the thermodynamic properties, transport properties, and the microscopic structures of liquid TBP, TBP/water mixtures, and TBP/n-alkane mixtures. These results are compared with those obtained from four other TBP models, previously described in the literature. We conclude that our refined TBP model appears to be the only TBP model from this set that, with reasonable accuracy, can simultaneously predict the properties of TBP in bulk TBP, in organic diluents, and in aqueous solution. The other models only work well for two of the three systems mentioned above. This new TBP model is thus appropriate for the simulation of liquid-liquid extraction systems in the nuclear extraction process, where one needs to simultaneously model TBP in both aqueous and organic phases. It is also promising for the investigation of the microscopic structure of the organic phase in these processes and for the characterization of third-phase formation, where TBP again interacts simultaneously with both polar and nonpolar molecules. Because the proposed TBP model uses OPLS-2005 Lennard-Jones parameters, it may be used with confidence to model mixtures of TBP with other species whose parameters are given by the OPLS-2005 force field.