ESR and FTIR studies on electron beam‐irradiated low‐density polyethylene blends

Low‐density polyethylene (LDPE) composites modified with a resin based on ethylene/methacrylic acid copolymer (surlyn) and/or citric acid were electron beam‐irradiated and investigated by electron spin resonance (ESR) at room temperature. ESR studies were carried out directly after irradiation and after various time intervals up to 72 h postirradiation. The irradiated samples showed the ESR spectrum of seven lines that was assigned to the formation of allyl radical. The nature and yield of the allyl radical of the different LDPE samples were analyzed as a function of time after irradiation. Also, the radical concentration, decay, decay rate, and kinetics of radical decay were evaluated. Fourier transform infrared (FTIR) analysis at a series of different temperatures upon cooling from room temperature to ?175°C and the reverse heating to +125°C was also carried out. The structural changes while cooling and heating of LDPE samples were investigated using FTIR spectrometry. The results showed that cooling of unirradiated LDPE samples to ?175°C results in a decrease of the intensities of IR bands. However, heating the samples from ?175°C up to +125°C led to a consequence increase in the intensities of the IR bands. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 103: 3461–3469, 2007     

Trapped and transient radicals observed in ethylene–propylene–diene terpolymers

Radicals formed by irradiation by high energy electron in ethylene–propylene–hexadiene terpolymer (EP–HD) have been studied using electron spin resonance (ESR). Two methods were used to analyse the different radicals formed by irradiation: firstly, classical low temperature irradiations were carried out, secondly, rapid quenching in liquid nitrogen of the material after high dose rate irradiation.

The feasibility and the efficiency of the latter method to observe short-lived radicals have been demonstrated. This type of experiment provides unique information concerning the rate of production and the rate of reaction of radicals.     

聚合物阴极钽电解电容器被膜技术研究

研究了以导电聚合物PEDOT作为阴极材料的高频低ESR有机片式固体钽电解电容器的被膜技术,重点讨论不同的聚合温度、掺杂浓度和驱溶温度对降低片式固体钽电解电容器ESR的影响.研究结果表明当聚合温度为0～10℃、掺杂浓度为3%(W),驱溶温度80℃时,将得到致密的主链掺杂有效的PE-DOT膜层,从而得到较低的ESR,并表现...     

Experimental and theoretical investigation of defects at (1 0 0) Si1−xGex/oxide interfaces

The identification of a nontrigonal Ge dangling bond at SiO₂/Si_1−xGe_x/SiO₂ heterostructures and its electrical activity are discussed, both from experimental and theoretical points of view. This dangling bond is observed from multifrequency electron-spin resonance experiments performed at 4.2 K, for typical Ge concentrations in the range 0.4 ≤ x ≤ 0.85. The electrical activity of this defect is revealed from capacitance-voltage characteristics measured at 300 and 77 K, and is found to behave like an acceptor defect. First-principles calculations of the electronic properties of this Ge dangling bond indicate that its energy level approaches the valence band edge of the Si_1−xGe_x layer as the Ge content increases, confirming its acceptor-like nature.     

Properties of radicals created by γ-ray irradiation of silk fabrics

The properties of radicals from γ-ray irradiated silk fabrics were studied by electron spin resonance method (ESR). The ESR spectra of silk fabrics irradiated in N2 showed a doublet at room temperature. The doublet became a singlet at g=2.0057 after placing the sample in air for 24 hours. This can be explained by formation of peroxide radicals. The radical concentration of the irradiated silk fabric and the decay rate of radicals are significantly affected by irradiation conditions, which include the absorbed dose, atmosphere, and water content of the silk fabric samples. However, no dose rate effect on the radical concentration was observed. The results are of help in our practice of property modification of silk products by radiation graft copolymerization.     

提高工业辐照剂量测量准确度的研究

基于丙氨酸/ESR剂量测量技术，利用LAEA/IDAS剂量核验提供服务，对保证辐照产品质量和促进幅照加工产业化发挥了重要作用。本文研究和讨论了剂量核验技术，它涉及基本概念、模体、误差、剂量水平和在剂量核验中质量控制的技术细节。     

ESR法测牙珐琅化石年龄中累积剂量测量的初步研究

研究了牙珐琅化石的ＥＳＲ信号对辐射剂量的响应关系，讨论了用指数函数拟合定牙珐琅累积剂量ＡＤ的适用范围和所产生的系统误差的大小，并以郧县古人类遗址牙珐琅样品为实例检验了上述研究结果。     

Study on ESR Properties of a-Si_(1-x)Gd_x Films

ESR studies have been undertaken for various chemical composition of electron beam evapo-rated a-Si_(1-x)Gd_x films with 0ESR spectrum based on the characteristics of the ESRparameters.It was shown that the changes of ESR parameters depend on the compensation of Gd atoms forthe dangling bonds in a-Si film,and the exchange interaction between the conduction electrons and the spinsin the host materials.     

NO分解催化剂Cu/分子筛的ESR研究 Ⅰ.水合铜分子筛的ESR研究

系统地比较了在各种不同制备条件下制得的Ｃｕ／ＺＳＭ－５、Ｃｕ／丝光沸石、Ｃｕ／镁碱沸石和Ｃｕ／毛沸石的ＥＳＲ谱，至少六种水合Ｃｕ物种被发现，而且发现分子筛的腔结构对Ｃｕ物种的存在状态有很大的影响。