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With the increasing importance of light-responsive materials, it is vital to analyze the relationship between function and structural changes induced by light irradiation. Small-angle scattering (SAS) is effective for such structural analysis. However, quantitatively capturing local molecular structure formation and molecular reactions at a scale of less than 1 nm via SAS is difficult. In this study, to analyze the structure of non-equilibrium phenomena in light-responsive materials, a new sample environment has been developed for a time-of-flight small- and wide-angle neutron scattering instrument (TAIKAN), comprising a UV–Vis irradiation system, UV–Vis absorption measurement equipment and photodetector. Simultaneous measurement of small-angle neutron scattering and UV–Vis absorption was achieved. This system was used to demonstrate the in situ observation of UV–Vis irradiation-induced structural change of micelles formed by 4-butylazobenzene-4′-(oxyethyl)trimethylammonium bromide, which is a light-responsive surfactant, in an aqueous solution. The results showed that the present measuring system provides direct information on the interplay between changes in micelle structure and changes in molecular configuration.

Amorphous and liquid selenium exhibit interesting photo-induced changes due to photo-flexibility of lone-pair semiconductors. This study conducts a detailed investigation of the photo-structural changes in amorphous and liquid selenium. We performed photo-induced optical absorption measurement of amorphous and liquid selenium using a nanosecond pulsed laser with a weak intensity of 1.0 mJ/pulse. The measurement indicated photo-induced absorption in the time region from 10−7 to 10−2 s in both amorphous and liquid selenium, which is referred to as fast photodarkening. This suggests a local structural change around a Se atom, such as a formation of three-fold coordination, which produces branched chains in the network, and deviations in the bond angle and dihedral angles. Durable photodarkening, which is semi-permanently preserved after prolonged light illumination, can be attributed to the local structure; however, it also requires an extended network structure. Our findings yield a profound insight into a variety of photo-induced structural changes in a network of selenium chains.

Reversible amorphous to crystalline phase transition introduces high contrast in the optical and electrical properties of chalcogenide glasses. This effect can be utilized by a designated temperature sensor based on optical power measurement as a function of temperature for temperature monitoring. For this purpose, crystallization kinetics and crystal structures of Ge–Se binary chalcogenide glasses were studied with Differential Scanning Calorimetry, Raman spectroscopy, and X-ray diffraction spectroscopy. The refractive index as a function of temperature was also measured to correlate the effect of structural rearrangement at the phase transition point with optical properties. Based on these data, the crystallization process is interpreted as being homogeneous for the stoichiometric composition and heterogeneous for either chalcogenide- or germanium-rich compositions. This specifically affects the optical performance of the films as a function of temperature and suggests the application of chalcogen- or germanium-rich compositions for building the sensor.

Silver photodiffusion is one of the attractive photo-induced changes observed in amorphous chalcogenides. In this research, we focus on amorphous S-rich germanium sulphide and study the kinetics of the silver photodiffusion by neutron reflectivity, as well as optical reflectivity. It was found from the neutron reflectivity profiles with 30 s time resolution that silver dissolved into the germanium sulphide layer, forming a metastable reaction layer between the Ag and the germanium sulphide layers, within 2 min of light exposure. Subsequently, silver slowly diffused from the metastable reaction layer to the germanium sulphide host layer until the Ag concentration in both layers became identical, effectively forming one uniform layer; this took approximately 20 min. Optical reflectivity reveals the electronic band structure of the sample, complementary to neutron reflectivity. It was found from the optical reflectivity measurement that the metastable reaction layer was a metallic product. The product could be Ag8GeS6-like form, which is regarded as the combination of GeS2 and Ag2S, and whose backbone is composed of the GeS4 tetrahedral units and the S atoms. We attribute the first quick diffusion to the capture of Ag ions by the latter S atoms, which is realised by the S–S bond in amorphous S-rich germanium sulphide, while we attribute the second slow diffusion to the formation of the Ag–Ge–S network, in which Ag ions are captured by the former GeS4 tetrahedral units.

Chalcogenide glasses are one of the most versatile materials that have been widely researched because of their flexible optical, chemical, electronic, and phase change properties. Their application is usually in the form of thin films, which work as active layers in sensors and memory devices. In this work, we investigate the formulation of nanoparticle ink of Ge–Se chalcogenide glasses and its potential applications. The process steps reported in this work describe nanoparticle ink formulation from chalcogenide glasses, its application via inkjet printing and dip-coating methods and sintering to manufacture phase change devices. We report data regarding nanoparticle production by ball milling and ultrasonication along with the essential characteristics of the formed inks, like contact angle and viscosity. The printed chalcogenide glass films were characterized by Raman spectroscopy, X-ray diffraction, energy dispersive spectroscopy and atomic force microscopy. The printed films exhibited similar compositional, structural, electronic and optical properties as the thermally evaporated thin films. The crystallization processes of the printed films are discussed compared to those obtained by vacuum thermal deposition. We demonstrate the formation of printed thin films using nanoparticle inks, low-temperature sintering and proof for the first time, their application in electronic and photonic temperature sensors utilizing their phase change property. This work adds chalcogenide glasses to the list of inkjet printable materials, thus offering an easy way to form arbitrary device structures for optical and electronic applications.

Photo-induced rapid control of molecular assemblies, such as micelles and vesicles, enables effective and on-demand release of drugs or active components, with applications such as drug delivery systems (DDS) and cosmetics. Thus far, no attempts to optimize the responsiveness of photoresponsive molecular assemblies have been published. We previously reported photoresponsive surfactants bearing a lophine dimer moiety that exhibit fast photochromism in confined spaces, such as inside a molecular assembly. However, rapid control of the micelle structures and solubilization capacity have not yet been demonstrated. In the present work, photo-induced morphological changes in micelles were monitored using in-situ small-angle neutron scattering (SANS) and UV/Vis absorption spectroscopy. An amphiphilic lophine dimer (3TEG-LPD) formed elliptical micelles. These were rapidly elongated by ultraviolet light irradiation, which could be reversed by dark treatment, both within 60 s. For a solution of 3TEG-LPD micelles solubilizing calcein as a model drug molecule, fluorescence and SANS measurements indicated rapid release of the incorporated calcein into the bulk solvent under UV irradiation. Building on these results, we investigated rapid controlled release via hierarchical chemical processes: photoisomerization, morphological changes in the micelles, and drug release. This rapid controlled release system allows for effective and on-demand DDS.

As one of the features in the sample environment (SE) in Japanese neutron scattering facilities, some SE equipment that are frequently used at an instrument, such as the closed-cycle refrigerator (...

Precise x-ray diffraction measurements using high-energy x rays of synchrotron radiation and systematic Raman scattering measurements were carried out for ${\mathrm{Ge}}_{x}{\mathrm{S}}_{100\ensuremath{-}x}$ $(10\ensuremath{\leqslant}x\ensuremath{\leqslant}40)$ network glasses. The structural models of the network glasses were proposed based on the results. In the stoichiometric composition ${\mathrm{Ge}}_{33}{\mathrm{S}}_{67}$, ${\mathrm{GeS}}_{4}$ tetrahedral units are connected forming either corner-sharing or edge-sharing structures. In the S-rich glasses, S atoms are inserted between two neighboring ${\mathrm{GeS}}_{4}$ tetrahedra, resulting in a flexible floppy network. In a much more S-rich region, some ${\mathrm{S}}_{8}$ ring molecules are isolated from the network, and assemble to form a crystal in nanoscopic scale. In this respect, ${\mathrm{Ge}}_{10}{\mathrm{S}}_{90}$ samples are regarded as crystallized glasses. In the Ge-rich region, the ${\mathrm{GeS}}_{4}$ tetrahedra are connected with bridging Ge atoms. The connection makes a new rigid network. The bridging Ge-S bond is weaker than the intratetrahedron bond, and this leads to drastic changes in the optical properties.

Silver photodiffusion into amorphous chalcogenides involves the movement of ions controlled by a UV-visible light illumination, and has potential application to memory devices. Understanding the kinetics of this phenomenon will expand the range of possible applications. Herein, we report the excitation photon energy dependence of the silver photodiffusion kinetics in Ag/amorphous Ge20S80/Si substrate stacks, probed by neutron reflectivity using four light-emitting diodes with different peak wavelengths. Time-dependent changes were clearly observed in all three of the Ag/Ag-doped reaction/chalcogenide host layers, in terms of layer thickness, scattering length density, and roughness. Silver photodiffusion effectively occurred when the excitation photon energy was greater than the optical gap of the chalcogenide host material. Excitation of lone-pair electrons to anti-bonding states at the chalcogenide layer therefore appears to play a crucial role in triggering silver photodiffusion.

3 He neutron spin filters require a homogeneous magnetic field, otherwise the nuclear polarization of the 3 He gas will easily be lost by small magnetic field gradients. Magnetic cavities with field gradients of 10−4/cm or better are often in demand, and many such cavities - Helmholtz coils, solenoids, permanent magnet circuits, etc - have been developed [1] . These magnetic cavities are designed mostly by using simulations, but the actual magnetic fields may differ from the calculations because of the presence of the environmental magnetic field as well as nearby magnetic materials. To evaluate the real magnetic fields, a precision magnetometry system with a precision of 10-5 was developed.

In small angle neutron scattering spectrometer, SANS-J-II at Japan Research Reactor No. 3 (JRR-3), a polarization analysis setup has been equipped, which is composed of transmission-type supermirror polarizer, radial-bender-type supermirror analyzer, π flipper, and solenoids for generating guide magnetic field. This setup was applied to the structural study of polymer electrolyte membrane, Nafion under water-swollen state. The sample is known to exhibit several characteristic peaks at wide angle region, which is related to water transporting channels. By use of polarization analysis technique, the coherent and incoherent contributions were successfully separated. Consequently, we obtained reliable information about decaying power law of ionic cluster peak and the shape of the broad peak, relating to ordering with short distance (5.6 A).

A polarized 3 He neutron spin filter requires a suitably homogeneous magnetic environment to avoid depolarization of 3 He nuclear spin. In the present study, we discussed the required performance of the magnetic shield for an in-situ spin exchange optical pumping neutron spin filter system and designed a magnetic shield with T 1mag > 100 h under a magnetic field of 3.5 mT perpendicular to the guide field. We then constructed the magnetic shield and confirmed its performance. Finally, we succeeded in developing a magnetic shield for a polarized 3 He neutron spin filter system for J-PARC.

A new neutron reflectometer SHARAKU with vertical sample-plane geometry was installed on the beam line 17 (BL17) at Materials and Life science experiment Facility (MLF) at J-PARC. Magnetism in a thin magnetic film is one of the main targets on SHARAKU and polarizing devices and neutron spin flippers are required. Since polarized neutrons of wavelength from 0.24 nm to 0.64 nm can be used on SHARAKU, a neutron spin flipper has to control white neutron beam. A two-coil neutron spin flipper (Drabkin spin flipper) is one of the powerful devices to control neutron spin with white beam. In this study, the two-coil flipper was designed and installed in SHARAKU. Demonstration of the two-coil flipper was also performed and polarization of more than 0.95 with wavelengths ranging from 0.24 nm to 0.64 nm was obtained.

Using a transportable 3 He spin filter neutron polariser, we have constructed a polarised thermal neutron diffraction (PND) instrument on a powder neutron diffractometer. To minimise the inhomogeneity of the magnetic fields around the 3 He spin filter, an optimised compact non-adiabatic two-coil spin flipper for the PND instrument was developed. Magnetic field criteria were discussed for the design of the flipper. Using the PND instrument with the flipper, we succeeded in observing a difference in the magnetic field dependence of the deposited ferromagnetic phases in nanocomposite materials.

Polarized neutron spin filters are being developed based on spin-exchange optical pumping. In the present study a high-power diode laser (85 W) was used to excite Rb atoms and the laser linewidth was narrowed using an external cavity. The optics in the external cavity were designed by ray tracing. The ray-trace calculations demonstrated that a doublet lens in front of the laser eliminates aberrations. The maximum spectral peak height in the doublet optics was found to be 25% higher than for a singlet lens.

Glass cells play an important role in polarized 3 He neutron spin filters. To evaluate the scattering and absorption contribution from glass cells during neutron scattering experiments, we measured small-angle scattering and neutron transmission in GE180 and other glasses. The small-angle neutron scattering measurements revealed that the glasses used for 3 He spin filters have acceptably lower scattering: dΣ ( Q )/ dΩ =4–7×10 −4 cm −1 at Q =0.03–0.12 A −1 . The transmission measurement was performed at J-PARC. Neutron transmission of about 92% through empty GE180 cells was observed over a wide wavelength range 0.014–7.0 A. To pursue the possibility of being a structural influence on 3 He spin relaxation in GE180 glass cells, we performed precise X-ray diffraction measurement using synchrotron radiation at SPring-8. From these measurements, a structural difference was observed among GE180 glasses with different thermal treatments.

Polarized 3He neutron spin filters are suitable devices for polarizing neutrons at spallation neutron facilities because of the wide coverage in energy range and the large solid-angles. The glass cell plays an important role in the 3He spin filters. In order to get good quality of glass cells, the investigation on the microscopic structure would be helpful. In this paper, we report on the results of X-ray diffraction for several glasses. We observed a correlation between the position of the first peak and the helium permeation velocity. We also observed a small difference in the diffraction curve among GE180 glasses with different thermal treatment. Desirable structure for 3He spin filters is discussed.

This paper presents a study of Cu diffusion at various temperatures in thin SiO 2 films and the influence of diffusion conditions on the switching of Programmable Metallization Cell (PMC) devices formed from such Cu-doped films. Film composition and diffusion products were analyzed using secondary ion mass spectroscopy, Rutherford backscattering spectrometry, X-ray diffraction and Raman spectroscopy methods. We found a strong dependence of the diffused Cu concentration, which varied between 0.8 at.% and 10 − 3 at.%, on the annealing temperature. X-ray diffraction and Raman studies revealed that Cu does not react with the SiO 2 network and remains in elemental form after diffusion for the annealing conditions used. PMC resistive memory cells were fabricated with such Cu-diffused SiO 2 films and device performance, including the stability of the switching voltage, is discussed in the context of the material characteristics.

We are reporting our results of Raman and X-ray diffraction (XRD) studies on amorphous Ge 46 S 54 thin films and the films after silver photodiffusion. Based on the Raman scattering studies, a structural model for amorphous Ge 46 S 54 is suggested including the formation of single Ge-S chains with a vibrational mode at 410 cm -1 . The result of XRD measurement indicates that there exists a medium-range order with about 6 A even at such Ge-rich composition. After the introduction of silver, the medium-range order is lost and there was a change in the diffraction curve indicative of the change in the local atomic order. The experimental results are explained in terms of our structural model, in connection with the application for fast switching memory devices.

Silver diffuses into chalcogenide films upon light exposure, and the kinetics of photodiffusion has been a subject of various investigations because of the difficulties in the in situ determination of the time-dependent Ag reaction and diffusion development in the chalcogenide layers. In this paper, we report the results of time-resolved neutron reflectivity measurement of Ag/Ge40S60/Si substrates under light exposure to clarify the kinetics of Ag photodiffusion into Ge-rich Ge chalcogenides. It reveals that Ag ions diffuse all over the Ge chalcogenide host layer once Ag dissolves into the layer without forming a metastable reaction layer unlike the case of S-rich Ge chalcogenide such as Ge20S80. The decay curve suggests that the Ag dissolution is determined by two types of Ag capturing chalcogen sites. Also, the observed relaxation time showed anomalous chalcogenide layer thickness dependence. This is attributed to an additional diffusion-driven accelerating factor, which is unique to the silver photodif...

The Raman spectra of Ge-S glasses in the Ge-rich re gion from Ge 33 to 46 % have been investigated in order to know the structural develo pment of the network glasses. From the detailed curve fits, we have found that there is an unassign ed peak at 410 cm -1 and it becomes larger with increasing Ge composition. To clarify the structura l origin of the peak, we virtually constructed the atomic arrangement of the glassy state starting from the crystalline state through the liquid state and changed the composition gradually depleti ng the medium in sulfur. From the consideration of the structural modeling and the at omic orbital theory, we suggest that single Ge-S chain is a probable structural origin of the peak.

We report our results of continuous illumination of Ge 46 S 54 chalcogenide glass films with bandgap light in air. The outcome of this process is the formation of Ge-S backbone depleted in germanium. We relate this to consumption of some of the germanium available in the initial material due to the occurrence of a photoinduced oxidation. This is proved using energy dispersion spectroscopy which shows the presence of 17.68at.% oxygen in the glass post-radiation. Raman spectra demonstrate that the initial material, shows breathing modes, characteristic for Ge 46 S 54 glass. After prolonged illumination Raman spectra reveal structure characteristic for the composition of the Ge-S backbone close to Ge 33 S 67 . The oxide forms a film on the surface and this changes the surface relief, studied by atomic force microscopy, but the oxidation is not surface-limited. The oxidation process in these glasses is discussed and the higher priority of germanium oxidation compared to the oxidation of sulphur is stated.

We have performed precise measurements of the transient optical absorption spectra of amorphous (a-) As 2 Se 3 and As 2 S 3 at room temperature in the nanosecond and microsecond domains. From the measurements, we have observed the photodarkening in the nanosecond and microsecond domains for both of the samples. For a-As 2 Se 3 , a broad absorption peak in the range from 420 to 730 nm was observed. The peak maximum changed to longer wavelength with time. For a-As 2 S 3 , a sharp absorption peak in the range from 420 to 510 nm and a long absorption tail in the range from 510 to 600 nm were observed. The peak maximum does not change with time. Based on the experimental results, we discuss the nanosecond dynamics of the photodarkening in terms of the local structural changes.

We report our recent results on the photoinduced transient optical absorption measurements of amorphous (a-) As2Se3 and a-As2S3, after the illumination of nanosecond pulsed laser. From the measurements, we have observed a photodarkening in the nanosecond and microsecond domains for the first time. Since the fast photodarkening was also observed in the liquid state, the structural origin of the photodarkening should be different from the conventional metastable photodarkening, which is observed only below the glass transition temperature. We have also examined accumulated photoinduced changes for the stronger repeated pulsed laser illumination. From the measurements, we have found for As2S3 that there exists an accumulated photoinduced absorption in the supercooled liquid state. On the basis of the detailed results of the transient optical absorption measurements, structural origin of the photodarkening is discussed.

Accumulation and decay processes in photodarkening of amorphous chalcogenide have been investigated by measuring photoinduced transient optical absorption of amorphous As 2 Se 3 and As 2 S 3 . From the measurements, we observed accumulation of the photoinduced effect for an illumination of repeated pulsed laser. After stopping the illumination, a decay of the photoinduced change and the saturation of the decay were observed, which is related to transient photodarkening and durable photodarkening, respectively. The difference of the two types of photodarkening clearly observed in the repeated experimental procedure composed of illuminated and non-illuminated period and the temperature dependence. From the measurements of the photoinduced absorption spectra, a peak located at the energy higher than the optical gap was observed in the spectra during and after stopping illumination.

液体硫黄は 159℃ で八員環分子から鎖状高分子と八員環分子の混合液体へと重合転移をおこす．筆者らは最近，光照射によりこのような重合を重合転移温度以下で実現できること，さらに，レーザー光強度によって制御される三段階の光誘起構造変化，すなわち，(1)弱いレーザー光によって生成される八員環分子と鎖状高分子の間の中間生成物の生成，(2)強いレーザー光によって生成される鎖状高分子の生成，(3)より強いレーザー光の照射によって生成される秩序化した巨大高分子の生成，があることを見いだした．本報では，この光誘起構造変化の詳細を報告し，さらにこの変化の起源を孤立電子対を有する硫黄高分子の電子構造にもとづいて議論する．

Nuclear-polarized 3 He gas has recently been widely used in neutron facilities around the world for polarized neutron scattering. The large neutron absorption cross-section of 3 He depends strongly on the 3 He-spin and the neutron-spin directions, and a polarized neutron beam can be easily obtained by passing the beam through polarized 3 He gas, thus constituting a neutron spin filter (NSF). The relationships between neutron polarization Pn, neutron transmission Tn, and 3 He polarization PHe are

Photodarkening in the nano- and microsecond domain was observed in amorphous As2Se3 from measurements of the transient photoinduced optical absorption spectra in the high absorption region using a specially designed optical cell which prepared a submicrometre-size melt-quenched amorphous film. This photodarkening was also observed in the liquid state. The observed optical change suggests the presence of a photoinduced structural change in the time domain. The origin of this photodarkening is discussed.

We have begun the development of an in-situ spin-exchange optical pumping (SEOP) system aiming to use it as a neutron spin filter for incident beam polarization at the Japan Proton Accelerator Research Complex (J-PARC). To use it, it is recommended that the optics be adjusted easily, have high stability, and have a small size. In this paper we improved our previous SEOP system aiming to use it in J-PARC and performed a neutron beam test at the JRR-3 NOP beamline to see the performance of the neutron spin filter (NSF). The polarization of the 3 He gas reached 73%. This paper gives the present status of the development of in-situ SEOP system in J-PARC.

Polarized Raman scattering spectra of Sr 14- x Ca x Cu 24 O 41 have been measured for x =0 and 11.5 at ambient pressure. In the spectra, the intra-molecular vibrations due to the unit structure of (Sr/Ca) 2 Cu 2 O 3 and CuO 2 have been clearly observed below 700 cm -1 . A comparison of the number of the observed peaks with the results of a factor group analysis indicates that the crystallographic symmetry of the ladder is F 222 for x =0 and 11.5, instead of centro-symmetric F m m m , while that of the chain is A m m a for both compositions. However the symmetry of the chain for x =11.5 is close to F 222 or F m m m . That is, the structure of the chains changes from an incomplete staggered structure to almost complete staggered one with increasing x . In the ( c , c ) and ( a , a ) spectra, the broad two-magnon peaks have been observed at around 3000 cm -1 . From the analysis of the recent theory of the magnetic scattering in the 2-leg spin ladder system done by Natsume et al. , the following magnetic para...

We present a specially designed optical cell made of quartz preparing submicrometer-size films of liquid semiconductors. Using our technique, liquid film with the thickness of 0.3 μm could be produced. We applied the technique to the laser excited transient absorption measurement for liquid sulfur and the transient direct-current (dc) conductivity measurement for liquid selenium. It was found from the transient absorption measurement for liquid sulfur that the photoinduced polymerization occurs in liquid sulfur. The result of the transient dc conductivity measurement for liquid selenium indicated a possibility of the photoinduced semiconductor-metal transition in liquid selenium.

Transient dc conductivity and transient absorption of liquid selenium after illuminating with a pulsed laser have been investigated. From the transient dc conductivity measurement, we have found that the conductivity increased from 3.7 × 10−4 to 12 Ω −1 cm−1 when a pulsed laser with an intensity of 20 mJ/pulse illuminates liquid selenium at 580°C, which indicates that a photoinduced semiconductor–metal transition occurs. From the transient absorption measurement, induced absorption more than 50% and induced transmission more than 100% were observed. On the basis of our findings, we discuss the photoinduced effect on liquid selenium.

The transient dc conductivity of liquid selenium after illumination with a pulsed laser has been investigated as a function of temperature over the range and as a function of the laser intensity over the range 2-20 mJ/pulse. For the measurements, a new type of cell, made of quartz, of the authors' design was developed. We found that the conductivity increased up to when the pulsed laser illuminated liquid selenium at with the intensity of 20 mJ/pulse, which suggests that a photoinduced semiconductor-metal transition occurs. We also observed three types of relaxation, depending on the laser intensity and the temperature. The existence of these relaxations may suggest that there are several types of photoinduced structure in liquid selenium. We discuss the observed photoinduced effects in terms of the photoinduced structural changes.

Transient absorption spectra of liquid selenium after illumination with a pulsed laser have been investigated. It was found that a giant photodarkening occurs and the optical gap disappears when the pulsed laser illuminates liquid selenium at with the intensity of 15 mJ/pulse. The possibility of a photoinduced semiconductor-metal transition is discussed.

The pattern which appears in liquid sulfur when a pulsed laser with an intensity more than 20 mJ/pulse illuminates the sample below the polymerization temperature was investigated. For the investigation, specially designed quartz cells with sample thicknesses from 0.3 μm to 2.0 mm were developed. When the sample is very thin, there appears a colored pattern like a rainbow. Observation using a microscope revealed an inhomogeneous region, which seems to consist of macromolecules with an ordered structure. In contrast, when the sample is very thick, another new pattern, which seems to be a thin film with wrinkles, was found. On the basis of these findings, the origin of these patterns is discussed.