Full Width At The Half Maximum Research Articles

Advancing MR‐TADF OLED Toward True‐Blue CIE Value via Asymmetric Host Materials with Amorphous Morphology

AbstractThe new host materials are reported to boost the multiple resonance‐induced thermally activated delayed fluorescence (MR‐TADF) based pure deep‐blue organic light emitting diodes (OLEDs) toward further shortening the emission full width at the half maximum (FWHM). Based on an unusual asymmetric design concept, two new host compounds Bz2cb and Bz2cbz are synthesized. Despite possessing a compact and rigid molecular packing in crystal, Bz2cbz shows pure amorphous morphology via vapor deposition, as confirmed by the grazing‐incidence wide‐angle X‐ray scattering (GIWAXS) analysis. Via incorporating a promising MR‐TADF emitter, ν‐DABNA‐O‐Me, into Bz2cb and Bz2cbz films, highly pure deep‐blue OLEDs are successfully demonstrated. Remarkably, the Bz2cbz device exhibits a 464 nm electroluminescence (EL) with narrow FWHM of 22 nm, accompanied by the reduction of the 0–1 vibronic sideband, and a maximum external quantum efficiency (EQEmax) of 28.2%, which, overall, reaches the true‐blue Commission Internationale de l'Eclairage coordinates (CIE) of (0.13, 0.07) and the high blue index of 253. The amorphous film formation turns out to be an important factor that is previously unrecognized to externally fine‐tune the MR‐TADF OLEDs toward even higher color purity.

Synthesis, crystal structure and luminescence properties of ultra-broadband full-visible-spectral emission phosphor NaBa3Si2O7F: Bi3+

In this paper, NaBa3Si2O7F: Bi3+ phosphor was synthesized by solid phase method, and its first-principles calculations, crystal structure and luminescence properties were investigated. First-principles calculations showed that NaBa3Si2O7F is a direct bandgap fluorosilicate. The X-ray powder diffraction (XRD) patterns of the prepared phosphors were synchronized with the referenced data. The morphology of the prepared phosphors was analyzed by transmission electron microscope (TEM) and high-resolution transmission electron microscope (HRTEM). The excitation and emission spectra showed that in NaBa3Si2O7F: 7%Bi3+ single-phase phosphor, the multi-site occupancy of Bi3+ in the phosphor can realize the ultra-broadband full-visible-spectral emission from 300 to 800 nm, with the full width at the half maximum (FWHM) = 428 nm. All these results indicate that NaBa3Si2O7F: Bi3+ phosphor is a promising ultra-broadband full-visible-spectral emission luminescence phosphor.

500 Hz single-frequency, pulsed Er:YAG laser in the double corner cube retroreflector resonator

We have demonstrated an injection-seeded, single-frequency Q-switched Er:YAG laser at the pulse repetition frequency (PRF) of 500 Hz with the ‘double piezoelectric transducers (PZTs) structure’, in a double corner cube retroreflector (DCCR) resonator. With the ‘ramp-hold-fire’ method, the maximum 1.34 mJ pulse energy with a pulse width of 482 ns has been achieved. With the heterodyne beating technique, the full width at the half maximum (FWHM) of the laser spectrum is 1.12 MHz. And the M2 factors of the 500 Hz, single-frequency pulsed laser are 1.2, 1.24 along the horizontal and vertical directions.

Effects of Temperature on the Physicochemical Properties of Bioinspired, Synthetic, and Biogenic Hydroxyapatites Calcinated under the Same Thermal Conditions.

The paper studies the changes in physicochemical properties of three types of hydroxyapatite (HAp): HAp-HB (from bovine sources), HAp-SC (chemically synthesized), and bioinspired HAp-SE (synthesized using eggshells) calcined under identical thermally controlled conditions from room temperature to 400, 500, 600, 650, 680, 700, 720, 750, 800, and 900 °C in furnace air. The thermogravimetric analysis (TGA) indicated distinct thermal transitions and coalescence phenomena at different temperatures for these samples due to their sources and mineral composition differences. Inductively coupled plasma (ICP) showed that HAp-H (human), HAp-HB (bovine), and HAp-SE (bioinspired) have similar Ca, P, and Mg contents. Scanning electron microscopy (SEM) and transmission electron microscopy (TEM) revealed that the coalescence phenomena increased in the crystallite size as the temperature increased. X-Ray diffraction (XRD) patterns revealed partial phase changes in the bioinspired sample (HAp-SE) and crystallite growth in all samples, resulting in full width at the half maximum (FWHM) and peak position alterations. Fourier-transform infrared spectroscopy (FTIR) showed that HAp-SE exhibited a partial phase change due to dehydroxylation and the presence of functional groups (PO43-, OH, and CO32-) with varying vibrational modes influenced by the obtained method and calcination temperature. Raman spectra of the HAp-SE samples exhibited fluorescence at 400 °C and revealed vibrational modes of surface P-O. It observed the bands of the internal phosphates of the crystal lattice and shifts in the band positions at higher temperatures indicated phosphorus interacting with carbon and oxygen, triggering dehydroxylation.

Temporally ultralong biphotons with a linewidth of 50 kHz

We report the generation of biphotons, with a temporal full width at the half maximum (FWHM) of 13.4 ± 0.3 µs and a spectral FWHM of 50 ± 1 kHz, via the process of spontaneous four-wave mixing with laser-cooled atoms. The temporal width is the longest, and the spectral linewidth is the narrowest to date. This is also the first biphoton result that obtains a linewidth below 100 kHz, reaching a new milestone. The very long biphoton wave packet has a signal-to-background ratio of 3.4, which violates the Cauchy–Schwarz inequality for classical light by 4.8 folds. Furthermore, we demonstrated a highly tunable-linewidth biphoton source and showed that while the biphoton source’s temporal and spectral width were controllably varied by about 24 folds, its generation rate only changed by less than 15%. A spectral brightness or generation rate per pump power per linewidth of 1.2× 106 pairs/(s mW MHz) was achieved at the temporal width of 13.4 µs. The above results were made possible by the low decoherence rate and high optical depth of the experimental system, as well as a novel scheme of classical fields’ and biphotons’ propagation directions in the experiment. This work has demonstrated a high-efficiency ultranarrow-linewidth biphoton source and has made substantial advancements in quantum technology utilizing heralded single photons.

YBa2Cu3O7 films grown onto SrTiO3 and YSZ substrates by chemical solution deposition of trifluoroacetates

We report the preparation and characterization of YBa2Cu3O7 (YBCO) films grown onto SrTiO3 and YSZ substrates by the trifluoroacetates chemical solution deposition method and following sintering with oxygen atmosphere at 860 °C. The X-ray diffraction (XRD) reveals (00ℓ) – oriented crystallites indicating epitaxial growth of the films in the c-direction. Despite granular morphology and the presence of Y2BaCuO5 and CuO as minor secondary phases, the technique shows the successful formation of the superconducting YBCO and preventing the formation of the unwanted BaCO3 phase. Rocking curve measurements of the (005) reflection for the YBCO/SrTiO3 was fitted with one Gaussian function with full width at the half maximum (FWHM) of 0.44° confirming that it consists of YBCO crystallites with different texture. For the sample grown on YSZ, the rocking curve was fitted with two Gaussian functions, one corresponding to the YBCO layer (FWHM = 0.4°) and another to the substrate (FWHM = 0.3°). The magnetic measurements taken in zero field cooling and field cooling modes confirm the formation of the superconducting YBCO with critical temperatures (TC) 91.8 and 85.7 K for the samples grown onto YSZ and SrTiO3, respectively. The critical current density (JC) curves indirectly calculated by using the Bean´s model from the M(T) loops were JC ~ 109 A/cm2 for the sample deposited onto YSZ and JC ~ 107A/cm2 for the YBCO deposited onto SrTiO3. Overall, the difference in TC and JC values between both samples could be related to their difference in oxygen content, porosity, hole concentration per Cu ion and the presence of secondary phases.

Fluorescence Thermometry Based on PL Spectra and PL Image from Ti Doped Al2O3

Temperature dependences of photoluminescence (PL) from Ti doped sapphire (Ti doped Al2O3) crystals peaking at λ = 725 nm is evaluated for a fluorescence thermometry application. PL intensity from Ti doped sapphire decreases with temperatures increasing from 20 to 250 oC. 2-dimensional (2-D) PL images were observed from Ti doped sapphire using a CCD camera under a blue LED illumination. Brightness (intensity of red signal) of the PL image decreases linearly with temperature as is seen in PL peak intensity. The tendency of the temperature change of the PL peak intensity, intensity ratio, and full width at the half maximum (FWHM) of PL peak, and the brightness of the PL image from Ti doped Al2O3 are found to be useful for a fluorescence thermometry.

Tunable Mode Converter Device Based on Photonic Crystal Fiber with a Thermo-Responsive Liquid Crystal Core

A compact tunable mode converter device based on the thermo-optically characteristics of liquid crystals (LCs) is proposed and numerically analyzed herein. The proposed mode converter consists of an asymmetric dual-core photonic crystal fiber (PCF) with a highly thermo-responsive LC core. The verification of the proposed mode converter was ensured through an accurate PCF analysis based on the vector finite element method. With an appropriate choice of the design parameters associated with the LC core, phase matching at a single wavelength is available in the important O-band wavelength region. The simulation results showed that high conversion efficiencies between LP01 and LP11 mode are readily achieved over a broad wavelength range from 1278 nm to 1317 nm. Likewise, the tunable capability of the proposed mode converter was evaluated when it was submitted to thermal changes; thus, we evidence the strong thermo-responsive dependence of the operating wavelength, mode conversion efficiency and full-width at the half maximum (FWHM) bandwidth. Finally, the fabrication tolerances of the devices were also investigated. Therefore, the thermo-responsive characteristics of this novel PCF mode converter can be of fundamental importance in the future space division multiplexing technology.

Humidity and Temperature Annealing Effect on Light Emission Characteristics of SSI-LEDs

The solid-state incandescent light emitting device (SSI-LED) can emit the broadband white light similar to that of the sunlight in the visible wavelength range [1-4]. The light emitting principle is the thermal excitation of nano-resistors formed from the dielectric breakdown of a MOS capacitor [5]. The intensity of the emitted light is proportional to the intensity of the current passing through nano-resistors [6]. The SSI-LED has a long lifetime of more than 20,000 hours [7]. There are many potential applications of this kind of device, such as lighting and on-chip optical interconnect. In this paper, authors investigated the influence of the humidity and temperature exposure on the light emission characteristics of the SSI-LED. The SSI-LED was made from the dielectric breakdown of a MOS capacitor that contained a Zr-doped HfO2 (ZrHfO) gate dielectric on a p-type Si wafer with an ITO gate electrode. The fabrication process is described in refs. 3 and 5. The top ITO gate electrode has a diameter of 200 µm, 300 µm, or 400 µm. Before and after the exposure of the SSI-LED to the 80% humidity at 80℃ for 1 hour (Association Environmental System BHD-403 7316), the emission spectra were measured at the gate voltage (Vg ) of -30 V using a StellawNet spectra detector with the SpetraWiz Shortcut program. Figure 1 shows the spectra of a 200 µm sized device before and after the annealing. The spectrum shifted toward the long wavelength direct after the annealing, i.e., the peak moved from 601 nm to 641 nm. The same phenomenon has been observed on the 300 µm and 400 µm diameter devices. If the temperature can be estimated from the following Wien’s equation [8], the temperature was lowered by the annealing step, i.e., 4,521K vs. 4,822K. T λpeak = 2.898 x 10-3 [1] where T is the temperature in Kelvin and λpeak is the peak wavelength in m. If the color correlated temperature (CCT) is estimated from the SpetraWiz Shortcut program, the number was also lowered after the annealing, i.e., 4,109K vs. 3,801K. Also, the CIE chart location of the device was moved toward the ward light region, i.e., (CIEx, CIEy) (0.384, 0.370) vs. (0.378,0.380). Figure 2 shows curves of the full width at the half maximum (FWHM) of the emission spectrum vs. the diameter of the device before and after the humidity and temperature annealing. The FWHM was increased after the humidity and temperature exposure. It was reported that the diffusion of H2O through the nano-resistor structure can cause the formation of charge transfer complexes [9], which lowers the resistance and changed the emission spectrum. A detailed discussion of the cause will be presented. Lingguang Liu acknowledge the financial support of National Natural Science Foundation of China (Grant Number: 61771382) and the Shaanxi International Science and Technology Cooperation and Exchange Program (2018KW-034). J. Yan, Y. Kuo, and J. Lu, ECS Solid State Lett., 10, H199-H202 (2007)C. Hobbs, et al., IEDM, 30.1.1 - 30.1.4 (2001).Y. Kuo and C.-H. Lin, Appl. Phys. Lett., 102, 031117 (2013)Y. Kuo, IEEE Trans. Elec. Dev., 62(11), 3536-3540 (2015).C.-H. Lin and Y. Kuo, ECS JSS, 3(10), Q182-Q189 (2014).L. L. Liu, X. N Zhang, B.J. Yu, Y. Y. Lin and H. Zhang, Mat. Sci. Semi. Proc., 93, 226-230 (2019).S. Zhang, Y. Kuo, ECS. Trans., 77(2), 79-83(2017)Y. Kuo, and C- H Lin, ECS Solid State Lett., 2(8) Q59-Q61 (2013). Figure 1

Synthesis and luminescence characterization of microcrystalline Nd-doped calcium sulfate

In the present study, the precipitation method was used to synthesize microcrystalline Nd-doped CaSO4 phosphor. Structural and morphological analysis of the phosphor samples were performed by using X-ray diffraction (XRD) and scanning electron microscopy (SEM) methods. In addition, luminescent properties of the samples were characterized by thermoluminescence (TL) and optically stimulated luminescence (OSL) methods. The results of XRD analysis and SEM images showed that the prepared CaSO4:Nd powder samples have an orthorhombic crystal structure and almost spherical in size with an average between 3 and 17 μm. In the light of the luminescence analysis, the optimum preheat temperature required to evacuate the low temperature electron traps was determined as 170 °C. It was also presented that CaSO4:Nd samples have the potential to be used as a dosimetric material with a linear dose sensitivity between 1 and 20 Gy (as TL dosimeter), and 1 and 10 Gy (as an OSL dosimeter) when they are exposed to beta irradiation. In addition, the full width at the half maximum (FWHM) values of the main TL peaks presented no independence of HR.

Preparation and photoelectric properties of CsPbBr<sub>3</sub> perovskite nanoplates

All inorganic cesium lead halide (CsPbX3, X=Cl, Br, I) perovskites, as a best candidate in perovskite family, have attracted great interest due to their fascinating optical, chemical and semiconducting properties and have demonstrated as potential building blocks in various applications such as photodetectors, light-emitting diodes, solar cells and lasers. Numerous efforts have been made to develop various CsPbBr3 perovskites with tunable morphology such as quantum dots (0-D), nanowires (1-D) and nanoplates (2-D) to achieve desired properties. Among them, anisotropic colloidal quasi- two-dimensional nanoplates have been attracting a great deal of research enthusiasm. In this work, all-inorganic CsPbBr3 perovskite nanoplates were prepared by precisely controlling the synthesis temperature and time in the hot-injection method. The reaction was performed under the protective atmosphere of nitrogen, at 110°C for 5 s and the reaction mixture was cooled by ice-water bath. Afterwards, the solution was purified by centrifugation at 12000 r min-1 and the precipitates were dissolved in n-octane. The structure, morphology and optical properties of as-synthesized CsPbBr3 perovskite nanoplates were characterized and analyzed by the series of characterization techniques. The results show that a sharp PL emission was detected at the peak of 500 nm with a narrow full width at the half maximum (FWHM) of 26 nm. The high-resolution transmission electron microscopy (HR-TEM) showed that the as-prepared CsPbBr3 nanoplates were uniform in size, with an average length of 20–21 nm and a thickness of 3–5 nm. All the above studies evidenced that, the improved high temperature-injection method have yielded the CsPbBr3 perovskite nanoplates with uniform size distribution, high color purity and improved optical properties. In addition, light emitting diode (LED) with CsPbBr3 perovskite nanoplates as the perovskite luminescent layer were fabricated by the simple solution spin-coating and vacuum evaporation technique. The device structure of the LED is ITO/PEDOT:PSS/TFB/CsPbBr3 NPs/TPBI/LiF/Al. In the device configuration, the patterned ITO is used as the anode, the spin-coated TFB with larger hole mobility is used as the hole transport layer, vacuum evaporated TPBI is chosen as the electron transport layer, as-prepared CsPbBr3 perovskite nanoplates are used as the light emitting active layer, and the vacuum evaporated LiF as the electron injection layer with Al cathode. The external quantum efficiency (EQE) of 1.71% and the luminous brightness of 297 cd m-2 was achieved for the LED devices fabricated by the solution method. Moreover, the densification and roughness of CsPbBr3 perovskite nanoplates as the luminescent layers were measured by atomic force microscopy (AFM). The improved efficiency and performance of our device was directly related to the compact and smooth surface of CsPbBr3 luminescent active layer. This result lays a foundation for the fabrication of high efficiency light emitting diode devices by utilizing all-inorganic CsPbBr3, and provides a relatively simple method for the synthesis of CsPbBr3 nanoplates, as well as good repeatability of thin film device fabrication process.

Influence of growth conditions on the quality of strained InAlGaAs/AlGaAs quantum wells grown by MOCVD

Compressive-strained InAlGaAs quantum wells (QWs) were grown on GaAs substrates by metal organic chemical vapor deposition (MOCVD). The influences of reactor pressure, V/III ratio, growth temperature, and substrate orientation on the quality of InAlGaAs QWs were studied using high resolution X-ray diffraction (HR-XRD), photoluminescence (PL) and atomic force microscope (AFM) measurements. The PL results indicate that the PL intensity and full width at the half-maximum (FWHM) of QWs are very sensitive to the growth conditions such as reactor pressure, growth temperature, and substrate orientation. The AFM results demonstrate that the growth mode of epilayer is dominated by the orientation of substrate. The growth mode of samples grown on 0.5° miscut and 2° miscut substrates is step flow and step bunching, respectively. The samples grown on 0.5° miscut substrates have higher PL intensity comparison with the samples grown on 2° miscut substrates at the same growth conditions. The PL and AFM results of sample grown at 700 °C and a pressure of 50 mbar with a V/III ratio of 100 indicated that these growth parameters are close to the optimum growth conditions for InAlGaAs QWs.

Monte Carlo simulation of accurate dose distribution with high resolution for the single source channel of Leksell 4C gamma knife

Objective To obtain the high-resolution dose distribution for the single source channel of Leksell 4C gamma knife. Methods A parallel computing platform based on the Message Passing Interface (MPI) and Monte Carlo Code MCNPX was established. The ring-shaped detector and two pre-validated variance reduction techniques (emission direction-biased sampling of source and termination of electron tracking in partial structures) were adopted to derive the high-resolution dose distribution for the single source channel of Leksell 4C gamma knife. The effect of cut-off energy for both photon and electron on the accuracy of simulation outcomes was evaluated and statistically compared. Results Compared with previous findings, the spatial resolution of the dose distribution for the single source channel obtained in this study was higher (radial resolution=0.1 mm) with less statistical error (<1%). The calculation time was acceptable (approximately 24 h). For the 4-, 8-, 14-and 18-mm variable collimators, the penumbra and full width at the half maximum (FWHM) for single side were 1.0, 1.1, 1.2, 1.3 mm and 2.2, 4.3, 7.3, 9.3 mm, respectively, which were consistent with previous studies. The difference of the simulation results was extremely small between different cut-off energy for photon (1 keV vs.10 keV). However, the simulation results significantly differ between 1 and 521 keV electronic cut-off energy. Conclusions The MCNPX parallel computing platform based on the MPI environment can be utilized to derive highly accurate dose distribution with high resolution in acceptable calculation time. The cut-off energy of the photon and electron should be cautiously set up during simulation. Key words: Gamma knife; Monte Carlo simulation; Leksell 4C; Single source channel

Perovskite nanocrystals: across-dimensional attachment, film-scale assembly on a flexible substrate and their fluorescence properties

Perovskite nanocrystals (NCs), which are a good fluorescence candidate with excellent photoelectric properties, have opened new avenues in the fabrication of highly efficient solar cells, light-emitting diodes (LEDs), and other optoelectronic devices. Further advances will rely on the multitude of compositional, structural variants that enable the formation of lower-dimensionality layered and three-dimensional (3D) perovskites with architectural innovations. In this work, the perovskite film was fabricated on a flexible substrate using simple dip-coating technology and 3D assemblies of perovskite NCs were obtained through an attachment process. Original perovskite NCs had a rectangular or square morphology with high particle uniformity and the narrow and symmetric fluorescence emission peak was adjustable at 515–527 nm. The controllable self-assembly of the micron size cuboid-like 3D assembly had an apparent enhancement on peak (111) in the x-ray diffraction (XRD) pattern. Surface ligands not only play a role in the attachment process but also keep the independence of each NC in 3D assemblies. Such assembly of the perovskite film maintained the original perovskite NCs fluorescence emission peak and narrow full width at the half-maximum (FWHM), which is of great importance for the investigation of future devices.

Normal and anomalous heating rate effects on thermoluminescence of Ce-doped ZnB2O4

The effect of heating rate (HR) on thermoluminescence (TL) glow curves of 1%, 4%, and 10% Ce3 + doped ZnB2O4 phosphors was investigated in detail. The glow peaks are examined and, activation energy (E) and frequency factor (s) are determined by using various heating rate (VHR) method. In the obtained glow curves with nine different HRs between 2 and 10°C/s, it was observed that the TL intensities of the first peaks of all three samples and the second peak of 10% Ce3 + doped sample decrease with increasing HR. The decrease in TL intensity was investigated whether it may be due to the presence of thermal quenching or not. On the other hand, the second glow peaks of 1, 4% Ce3 + doped ZnB2O4 phosphors show an anomalous TL behavior, which the probability of the radiative processes increases due to recombination of free electrons, so the TL intensity increases with the HR. The graphs of full width at the half maximum (FWHM) versus HR were also plotted to evaluate the influence of HR on TL intensity. In this paper, we suggest that the non-localized Schön – Klasens model may give an explanation for the second peaks of 1, 4% Ce3 + doped ZnB2O4 phosphors showing an unexpected increase with the increasing HR. In addition, the calculated E values of all doped phosphors were found similar in the range of 0.47–0.53eV for peak 1 and 0.61–0.66eV for peak 2. However, s values of Ce3 + doped ZnB2O4 phosphors were found slightly different according to the dopant amount and the equation used. Furthermore, different amount of Ce3 + doped samples indicate the similar properties for the repeated cycles of 5Gy in the same irradiation conditions.

Simultaneous seeing measurement through the Subaru Telescope in the visible and near-infrared bands for the wavelength dependence evaluation

Stellar images have been obtained under natural seeing at visible and near-infrared wavelengths simultaneously through the Subaru Telescope at Mauna Kea. The image quality is evaluated by the full-width at the half-maximum (FWHM) of the stellar images. The observed ratio of FWHM in the V-band to the K-band is 1.54 ± 0.17 on average. The ratio shows tendency to decrease toward bad seeing as expected from the outer scale influence, though the number of the samples is still limited. The ratio is important for simulations to evaluate the performance of a ground-layer adaptive optics system at near-infrared wavelengths based on optical seeing statistics. The observed optical seeing is also compared with outside seeing to estimate the dome seeing of the Subaru Telescope.

Effects of Hydrogen Concentration on the Growth of High Purity 4H-SiC Single Crystal Grown by Sublimation Method

In this paper, the effects of hydrogen concentration on growth rate, micropipe density and nitrogen concentration of 4H-SiC crystals were discussed. It was shown that the growth rate is a linear function of the hydrogen concentration, which can be explained not only by C/Si ratio but also the temperature gradient. It was also found that the micropipe density was increased rapidly when the hydrogen concentration exceed a critical value, because the defects such as Si droplets, carbon inclusions and polytype formation were generated at that time. The results of secondary ion mass spectroscopy (SIMS) showed that with increasing the hydrogen concentration, the nitrogen concentration falls down but reaches a constant value which meets the requirements for high purity semi-insulating (HPSI) SiC single crystal growth. Finally, the HPSI 4H-SiC crystals were obtained using 15% hydrogen concentration, the resistivities of wafers cut from these crystals were more than 109Ω•cm, micropipe densities were less than 5cm-2, the full width at the half-maximum (FWHM) were between 30-40 arcsec, making these wafers suitable for microwave devices fabrication.

Theoretical Analysis of Surface Waves: Revisited

The surface wave for the strongly adsorbed redox spices on electrode is one of the fundamental electrochemical issues, because we don’t need considering the mass transfer of redox species and can calculate voltammogram easily. The ideal voltammogram of the surface wave is symmetric for the forward and the backward scan and it is well known the full-width-at-the-half-maximum (FWHM) is 91 mV. Recently Nieh et al. proposed the potentiometric coulometry based on charge accumulation with a peroxidase/osmium polymer-immobilized electrode for sensitive determination of hydrogen peroxide [1]. In this potentiometric coulometry the peak shape and width of the surface wave is the key point to get the amount of the hydrogen peroxide in the polymer film. Kakutati and Senda [2] and Laviron [3] showed that the interaction between the adsorbed redox species change the FWHM of the surface wave, i.e. the FWHM is decreased (increased) when e(O-O) + e(R-R) – 2e(O-R) < 0 (> 0). In this study we have reformulated the chemical potential of the interacting redox species based on Bragg-Williams and Bethe-Guggenheim approximation, and the surface wave voltammogram is evaluated. For the attractive interaction we have found the limiting case that the FWHM become almost zero and the current diverges. In the Monte Carlo simulation for Kawasaki dynamics system we have confirmed chemical potential obtained by the Bethe-Guggenheim approximation is good enough approximation for the nearest-neighbor interaction model. We also proposed that the asymmetry of surface wave voltammogram is due to the counter-ion binding interaction for the redox species.

Preparation of c-axis textured Bi-2212 thin films on silver substrates by using chemical solution deposition

The silver sheath material plays an important role in the preparation of Bi-2212 and Bi-2223 tape conductors. In this paper, a chemical solution deposition method was proposed to fabricate the Bi-2212 thin film on Ag substrates after polishing and annealing. The influences of the sintering temperature were investigated. After sintered at 780 °C or 790 °C for 5 h in 8% O2 (N2 balanced), samples with almost pure and highly c-axis textured Bi-2212 phase were prepared. And the full width at the half maximum (FWHM) value of the rocking curves for the Bi-2212 (0012) plane reached below 5.8°.

Application of a conic glass monocapillary in Beijing synchrotron radiation facility

A conic glass monocapillary was developed and used at the Biological Macromolecules Station (BMS) in Beijing Synchrotron Radiation Facility (BSRF). The structure and transmission property of this optics is reported here in details. The experiments have shown that the value of full width at the half maximum (FWHM) of the X-ray beams transmitted through this optics was nearly unchanged within a short distance. This is very convenient for further measurement of samples. The power diffraction experiments of CeO2 revealed that the Debye rings are much clearer in the case of applying this optics. The ratio of error in the diffraction peak position is reduced significantly to the value as less as 0.042%.