首页 | 本学科首页   官方微博 | 高级检索  
相似文献
 共查询到20条相似文献,搜索用时 46 毫秒
1.
Preliminary results are described of a123Xe filled device to serve as a combination123I generator/iodination kit.123X was produced in the Brookhaven Linac Isotope Producer (BLIP) by the reaction127I(p, 5n)123Xe. The device consists of a small glass ampoule containing an internal glass breakseal and a flanged neck on which was crimped a multi-injection type septum. The ampoule contained a hydrogen sulfide atmosphere to assure that the iodine generated from the decay of the xenon was in the form of iodide. Following an adequate period for123Xe to decay (this period can be used for shipment), a needle is forced through the septum breaking the seal and residual gases are pumped off. The123I in the form of iodide can then be rinsed from the ampoule with any desired solvent or reagent added directly to the device to carry out an iodination in an enclosed environment. Preliminary results of both iodine recovery and iodinations have been promising. This research was supported by the US Department of Energy under Contract No. DE-ACO2-76CH0016.  相似文献   

2.
The solid-state structure of 4-iodobenzoic acid has been confirmed by variable temperature X-ray diffraction, variable temperature solid-state NMR and differential scanning calorimetry. 4-iodobenzoic acid crystallizes in the space group P2(1)/n, and dimerizes in the solid state about a center of inversion. Using extensive X-ray crystallographic data collections, the placement of the carboxylate H atoms from the residual electron density in difference Fourier maps was determined. The position of the electron density associated with the proton is found to vary with temperature in that the population of the disordered sites changes with varying temperature. Determination of the crystal structure between the temperatures of 248 and 198 K was not possible due to a phase transition, an endothermic event occurring at 230.77 K. The phase transition is also indicated by a change in the relaxation time of the ring carbon atoms in the solid-state NMR data. Though the dominating force in the dimeric unit in the solid state is the presence of strong hydrogen bonds, there are also van der Waals forces present between the iodine atoms. In the layered structure, the iodine-iodine distance is within the van der Waals contact radii, an interaction which causes a deformation in the electron density of the iodine atoms.  相似文献   

3.
Common‐metal‐based single‐atom catalysts (SACs) are quite difficult to design due to the complex synthesis processes required. Herein, we report a single‐atom nickel iodide (SANi‐I) electrocatalyst with atomically dispersed non‐metal iodine atoms. The SANi‐I is prepared via a simple calcination step in a vacuum‐sealed ampoule and subsequent cyclic voltammetry activation. Aberration‐corrected high‐angle annular dark‐field scanning transmission electron microscopy and synchrotron‐based X‐ray absorption spectroscopy are applied to confirm the atomic‐level dispersion of iodine atoms and detailed structure of SANi‐I. Single iodine atoms are found to be isolated by oxygen atoms. The SANi‐I is structural stable and shows exceptional electrocatalytic activity for the hydrogen evolution reaction (HER). In situ Raman spectroscopy reveals that the hydrogen adatom (Hads) is adsorbed by a single iodine atom, forming the I‐Hads intermediate, which promotes the HER process.  相似文献   

4.
Cheap and environmentally benign electrochemical energy conversion and storage devices, including a dye-sensitized solar cell (DSSC) using an AlI3-ethanol electrolyte and a new Al/I2 primary battery, are reported. The AlI3-ethanol electrolyte can be prepared simply by adding aluminum powder and iodine into ethanol at ambient conditions. The DSSC using this AlI3-ethanol electrolyte achieved an energy conversion efficiency of 5.9% at AM 1.5 (100 mW/cm-2). In the Al/I2 battery, AlI3 is formed spontaneously when aluminum and iodine electrodes are brought into contact at room temperature. Then I- anions transport across the AlI3 solid electrolyte for further electrochemical reactions.  相似文献   

5.
The Infrared, Raman, and UV-VIS Spectra of Iodine Azide in Solutions The infrared and Raman spectra of iodine azide in solid dichloromethane were recorded at low temperatures. An assignment of the fundamentals according to a Cs symmetry is given. The uv-vis spectra at room temperature are reported. The preparation of iodine azide in organic solvents is described.  相似文献   

6.
Research on rare earth chalcogenides has been an active.area of solid state chemistry due to their rich structural chemistry and various interesting physical properties[1-3]. In our attempts to search for potential infrared ceramic materials in the rare-earth-transition-metal chalcogenide system, two new quaternary selenides, KHo2CuSe4 and KEr2CuSe4, were obtained by a two-step synthetic route. Precursors from the first-step solid state reaction were mixed with excess amount of the KCl flux. The pressed pellet was placed into a sealed silica ampoule and thermally equilibrated at 930℃ for 8 days prior to slow cooling to room temperature. Red,transparent, and columnar single crystals of these two phases were isolated from the flux by a suction filtration technique with the products washed with distilled water. The incidental incorporation of the flux cation leads to the formation of the new phases.  相似文献   

7.
A flow injection analysis (FIA)-background correction method comprising two solid-phase reactors and spectrophotometry for determination of ascorbic acid (AsA) is proposed. A polyethylene mini-column filled with solid iodine (30% m/m suspended on silica gel beads), reactor 1, and other column filled only with silica gel, reactor 2, which are then incorporated in a flow system so that solid iodine reagent in reactor 1 is affected as the sample passes through the column. The sample blank is produced by the oxidation of the AsA by iodine to form dehydroascorbic acid, insensitive to ultraviolet at 267 nm. AsA in samples is determined after injected in reactor 2; the difference in two analytical signal observed is related to amount of AsA. The linear range of the system is up to 50 μg ml−1 with a detection limit of 0.08 μg ml−1, R.S.D. of better than 1.0% and sampling frequency of 110 sample h−1. The method is successfully applied to the determination of AsA in pharmaceuticals and foods.  相似文献   

8.
Precise control of spin transition temperature (T(c)) is one of the most important challenges in molecular magnetism. A Hofmann-type porous coordination polymer {Fe(pz)[Pt(II)(CN)(4)]} (1; pz = pyrazine) exhibited cooperative spin transition near room temperature (T(c)(up) = 304 K and T(c)(down) = 284 K) and its iodine adduct {Fe(pz)[Pt(II/IV)(CN)(4)(I)]} (1-I), prepared by oxidative addition of iodine to the open metal sites of Pt(II), raised the T(c) by 100 K. DSC and microscopic Raman spectra of a solid mixture of 1-I and 1 revealed that iodine migrated from 1-I to 1 through the grain boundary after heating above 398 K. We have succeeded in precisely controlling the iodine content of {Fe(pz)[Pt(CN)(4)(I)(n)]} (1-In; n = 0.0-1.0), which resulted in consecutive modulation of T(c) in the range 300-400 K while maintaining the hysteresis width. Furthermore, it was demonstrated that iodine migration in the solid mixture was triggered by the spin transition of 1-I. The magnetically bistable porous framework decorating guest interactive open-metal-site in the pore surface makes it possible to modulate T(c) ad arbitrium through unique postsynthetic method using iodine migration.  相似文献   

9.
本文首次报道了铁氰化钾在室温下与碘化钾、硫化钾的固相氧化还原反应,实验发现在固相下铁氰化钾与碘化钾混合后,生成单质碘和亚铁氰化钾,而在溶液中该反应是反方向进行的.实验还发现,在固相下铁氰化钾与还原剂硼氢化钠不反应,而在溶液中,该反应却能进行.对反应机制进行了初步探讨.  相似文献   

10.
本文首次报道了铁氰化钾在室温下与碘化钾、硫化钾的固相氧化还原反应,实验发现在固相下铁氰化钾与碘化钾混合后,生成单质碘和亚铁氰化钾,而在溶液中该反应是反方向进行的.实验还发现,在固相下铁氰化钾与还原剂硼氢化钠不反应,而在溶液中,该反应却能进行.对反应机制进行了初步探讨.  相似文献   

11.
The 183.038 nm resonance absorption transition of I(2P3/2) has been studied using a flash photolysis set-up for gas-phase chemistry and a radio frequency powered electrodeless discharge lamp filled with iodine. The dependence of self-absorption and self-reversal on iodine partial pressure in the discharge volume was measured. The optimum iodine partial pressure, with self-absorption minimized and acceptable intensity, is determined to be approximately 2.5×10−3 mbar. A method is described to estimate the temperature of the emitting atoms using direct measurements of relative absorption at different absorber concentrations. This yields an emission temperature of 923±50 K. Using this temperature, the oscillator strength for the I(2P3/2) transition at 183.038 nm is determined to be f=(3.87±0.57)×10−3, corresponding to an absorption cross-section at the center of the line of σ=(5.42±0.8)×10−14 cm2 atom−1. This shows a difference from one of two earlier measurements, but is close to the other. The remaining difference from the latter measurement is probably due to tendencies of opposite biases inherent to the experiments.  相似文献   

12.
本文设计了集热解析和进样功能为一体的固相微萃取-电感耦合等离子体质谱(SPMP-ICP-MS)联用的接口单元。利用I2在常温下连续稳定升华的物理特性,进行联用系统的气路调节的最佳化。以四乙基铅溶液为例探讨了SPME—ICP—MS接口的分析性能。采用峰面积的数据采集方式,获得了较好的重现性以及线性范围,其检出限为0.009ng/mL。  相似文献   

13.
Poly(diiododiacetylene) (PIDA) is a conjugated polymer containing an all-carbon backbone and only iodine atom substituents. Adding a Lewis base to the blue PIDA suspension at room temperature leads first to rapid disappearance of the absorption peaks attributed to PIDA, followed more slowly by release of free iodine. The resulting solid material gives a Raman scattering spectrum consistent with graphitic carbon, and it has a much higher conductivity than PIDA itself. Further investigation has led to the discovery of a previously unreported transformation, the reaction of a Lewis base such as pyrrolidine with a trans-diiodoalkene to form the corresponding alkyne. The generality of this iodine elimination further suggests that reaction of PIDA with Lewis bases dehalogenates the polymer, presenting a new method to prepare carbon nanomaterials at room temperature under very mild conditions.  相似文献   

14.
Measurements of the electrical conductivity were performed with bromine and iodine in the liquid and the solid states, both containing low concentrations of the corresponding halide ions. In bromine the specific conductivity increases dramatically upon solidification and in iodine it changes only slightly. In both systems the conductivity in the solid is rather high, with remarkably low temperature coefficients, pointing to an unusual mechanism of conduction (of the Grotthuss type) requiring very little movement of the heavy nuclei while the charge is transferred. In mixtures of bromine with a small amount of nitrobenzene (NB) an equivalent conductivity as high as 12 cm2 mol?1 Ω?1 was observed at ?25°C. In iodine the specific conductivity reached a value of about 0.01 Ω?1 cm?1 at 100°C. The energy of activation for conduction in bromine down to ?40°C was found to be about 23 kJ mol?1, increasing sharply below this temperature. In iodine, values of about 21–27 kJ mol?1 were observed over the whole temperature range measured.  相似文献   

15.
From the reaction of elemental iodine with ozone in anhydrous HF crystalline iodine trifluoride is formed. The hydrolysis of iodine trifluoride in HF yields a colourless crystalline solid. The Raman spectra of both compounds are described.  相似文献   

16.
Determination of Temperature Dependent Partial Pressures in Closed Systems. A New Improved Method. The Heat of Formation of RhI3,s An improved method to determine temperature dependent partial pressures of gaseous species in equilibria with condensed phases in closed systems (silica ampoules) at temperatures up to 1000 °C and pressures pi 0.1 < pi < 15 bar is presented. The method is based on the determination of the change of mass in the gasphase caused by solid gas transition at higher temperatures concerning substances which are deposited at one end of the ampoule. The results of the measurements give informations about reaction mechanisms, and enthalpies. The reliability of the method is demonstrated at the example of the heat of formation of RhI3,sBH°(RhI3,s, 298) = –142.2 kJ · mol–1).  相似文献   

17.
Nano-structured calcium silicate hydrate can physisorb or chemisorb iodine, making it interesting for medical or materials science applications, where a slow, controlled release of iodine is desired. It was found that iodine can be sorbed and released by applying the elemental halogen in solution, either as a gas or as a solid. At ambient temperatures the sorption and desorption process is quantitative and physical, meaning that the same amount of iodine is taken up and released. At temperatures above 32.5 °C (305.7 K) iodine reacts with the calcium silicate hydrate forming a complex, which is stable above the sublimation temperature of iodine. The formation energy for the iodine calcium silicate hydrate complex was established to be 41.8 ± 0.8 kJ mol−1 by calorimetry and the nature of the complex was investigated using X-ray photoelectron spectroscopy.  相似文献   

18.
Summary In order to prepare a large single crystal, tetraoxymethylene recrystallized by distilled water adjusted to pH 8 was sealed in an ampoule at a reduced pressure of 1 mm Hg and was crystallized in a furnace with the temperature gradient of 6 °C/cm. The lowering rate of the ampoule was required to be 6 cm/day for preparing the single crystal with 1 cm diameter and to be 3 cm/day for one with 2 cm diameter. The optimum angle at the pointing end of the ampoule, where a seed crystal is formed, was about 40°. The b-axis of the obtained single crystal was parallel to the direction of the crystal growth i. e. the wall of the ampoule. It was polymerized byγ-ray under conditions which prevent the growth of the twin crystal. The obtained polyoxymethylene was porous, because the polymerization yield of 100% could not be attained. However, it was so tough that a specimen for measurements could be cut down by a diamond cutter. Its fiber axis was parallel to the direction of the wall of the ampoule. It did not contain the so-called amorphous regions, although it did contain defects. It was characterized with the extremely high orientation of the polymer chains.
Zusammenfassung Zur Pr?parierung gro?er Einkristalle wurde rekristallisiertes Tetraoxymethylen in destilliertem Wasser von pH 8 in eine Ampulle bei einem reduzierten Quecksilberdruck von 1 mm eingefüllt und in einem Ofen mit einem Temperaturgradienten von 6 °C/cm kristallisiert. Die Abkühlgeschwindigkeit der Ampulle betrug etwa 6 cm/Tag für die Pr?paration eines Einkristalls mit 1 cm ? und 3 cm/Tag für einen solchen mit 2 cm ?. Der optimale Winkel am spitzen Ende der Ampulle, wo der Keimkristall gebildet wird, betrug etwa 40°. Dieb-Achse des Einkristalls war parallel zur Wachstumsrichtung, d. h. zur Wand der Ampulle. Der Kristall wurde durch R?ntgenstrahlen polymerisiert unter Bedingungen, die das Wachsen eines Zwillingskristalls vermeiden. Das erhaltene Polyoxymethylen war por?s, doch konnte eine Polymerisationsausbeute von 100% nicht erhalten werden. Doch war der Einkristall so z?h, da? für Messungen eine Probe mit dem Diamantschneider abgeschnitten werden konnte. Die Faserachse war parallel zur Wandrichtung der Ampulle. Das kristalline Material enthielt keine sogenannten amorphen Bereiche, allerdings Defekte. Es war durch extrem hohe Orientierungen der Polymerketten charakterisiert.


We are greatly indebted to Dr.Y. Miyake of Mitsui Toatsu Co., Ltd. for providing the tetraoxymethylene. Thanks are to due Dr.M. Nishii of Osaka Laboratories, Japan Association for Radiation Research on Polymer for the radiation polymerization, to Mr.T. Tsukihara for the X-ray measurement, and to Mrs.H. Tanaka for the help with the electron microscopy. We are also grateful to Prof.S. Seki for offering the use of differential scanning calorimeter.  相似文献   

19.
The ampoule method provides a promising pathway towards the controllable synthesis of novel electrocatalysts for water electrolysis due to its straightforward manipulation of reaction conditions, accessible experimental design, and controlled environment. This Concept introduces the development of the ampoule method and anticipates its application in electrocatalyst synthesis for water electrolysis. First, the history, device configuration, and merits of the ampoule method are briefly introduced. Afterwards, typical materials synthesized by the ampoule method are discussed. Then, recent process in applying the ampoule method to synthesize electrocatalysts for water electrolysis is highlighted. Finally, opportunities and potentials of this method in facilitating electrocatalyst synthesis for water electrolysis are discussed.  相似文献   

20.
The surface of carbon black (CB) nanoparticles was functionalized with poly(vinylidene fluoride) (PVDF) either by trapping of macroradicals or by cycloaddition. PVDF with two iodine end groups (I‐PVDF‐I) obtained from iodine transfer polymerization in supercritical CO2 was heated in the presence of CB and the C? I bond was cleaved resulting in a reaction between the macroradical and the CB surface. To allow for cycloaddition of PVDF to the CB surface for a number of polymers, the iodine end groups were replaced by azide end groups. In addition, microwave irradiation was applied to the functionalization. The influence of temperature, time, polymer concentration, and polymer molar mass on the functionalization reaction was examined. © 2010 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem, 2010  相似文献   

设为首页 | 免责声明 | 关于勤云 | 加入收藏

Copyright©北京勤云科技发展有限公司  京ICP备09084417号