γ射线与N离子辐照类金刚石薄膜的机理研究

对类金刚石 (以下简称 DLC)薄膜受 γ射线与 N离子辐照的结果进行了比较 .通过 Raman光谱分析得出 :γ射线辐照造成薄膜中 SP3C— H和 SP2C— H键的减少及 SP3C— C键的增加 ,与此同时氢原子结合成氢分子 ,并从膜中释出 ,薄膜的类金刚石特征更加明显.当辐照剂量达1 0×104Gy时 ,SP3C—H键减少了约 5 0 % .N离子辐照使 DLC薄膜中 SP3C— C键、SP2 C—H键及 SP3C—H键的含量均变少 ,并伴随着氢分子的释出 ,直接导致 DLC薄膜的进一步石墨化,其对 SP3C—H及 SP2C— H键的破坏程度远大于γ射线 .两者在辐照机理上截然不同.The results of the diamond like carbon films(the following is called for short DLC film) irradiated by γ rays and N ion were reported. It showed that SP 3C—H and SP 2C—H bonds were decreased, and SP 3C—C bonds were increased by γ ray irradiation, and induced hydrogen recombination with H 2 molecules, and subsequently released from the surface of the films. When the γ ray irradiation dose reached 10×104Gy, the numbers of SP3C—H bonds were decreased by about 50%...     

γ射线辐照对a-SiC:H薄膜结构与特性的影响

 采用射频（13.56 MHz）反应溅射方法制备a-SiC:H 薄膜，并将其在空气中进行高能γ射线(平均为1.25 MeV)辐照，5个样品的吸收剂量分别为0，2×10⁴，4×10⁴，6×10⁴，8×10⁴ Gy。采用拉曼及红外光谱对薄膜的结构进行表征,得到了其结构与特性的变化规律。研究与分析表明：随样品吸收剂量的增加，陷入空穴中的电子会被激发，a-SiC:H薄膜中的SiC成份增加，电阻率变小，数量级为105Ω·cm；薄膜存在结晶化的趋势,其主要原因在于由Si－O－Si键断裂而产生的Si取代膜中C－C键中的C而形成晶态SiC，在此过程中出现了Si－O－Si键及a-SiC:H的减少，晶态SiC的增加。经γ射线辐照后薄膜的氢含量降低，折射率从5.19增大到5.53，辐照后薄膜的透过率均低于原膜的透过率。在500~2 300 cm^-1(对应波长为20.00~5.29 μm)波段内，a-SiC:H薄膜存在一定的增透作用。     

A comparison of ionizing radiation damage in CMOS devices from 60Co gamma rays, electrons and protons

Radiation hardened CC4007RH and non-radiation hardened CC4011 devices were irradiated using 80Co gamma rays, 1 MeV electrons and 1--9 MeV protons to compare the ionizing radiation damage of the gamma rays with the charged particles. For all devices examined, with experimental uncertainty, the radiation induced threshold voltage shifts (△Vth) generated by 60Co gamma rays are equal to that of 1 MeV electron and 1-7 MeV proton radiation under 0 gate bias condition. Under 5 V gate bias condition, the distinction of threshold voltage shifts (△Vth) generated by 60Co gamma rays and 1 MeV electrons irradiation are not large, and the radiation damage for protons below 9 MeV is always less than that of 60Co gamma rays. The lower energy the proton has, the less serious the radiation damage becomes.     

EPR and UV spectrometry investigation of sucrose irradiated with carbon particles

Solid state/EPR (SS/EPR) dosimeters of carbon ions irradiated sucrose are studied with EPR, and their water solutions – with UV spectroscopy. Doses between 20 and 200 Gy are used with linear energy transfer (LET) values for carbon ions of 63, 77, 96 and 230 keV μm^?1. After irradiation all samples show typical for irradiated sucrose EPR and UV spectra. The obtained data are compared with those previously reported for nitrogen particles and gamma rays irradiated sucrose. The identical shape of both the EPR and UV spectra of irradiated with various type radiation samples suggests that generated free radicals are not influenced by the nature of radiation. The lack of difference in the line width of the separate lines or the whole EPR spectrum, obtained for gamma and heavy particles irradiation, suggests negligible spin–spin interaction among the radiation-generated free radicals in the samples. The linear dependence of the EPR response on the absorbed dose radiation is found to be higher when generated by gamma rays, than by the same absorbed dose of heavy particles. In addition, the EPR response for carbon ions is higher than that for nitrogen ions. Water solutions of irradiated sucrose exhibit UV spectrum with absorption maximum at 267 nm, attributed to the recombination products of free radicals. The UV band intensity depends on the absorbed dose radiation. The UV spectra obtained for carbon, nitrogen and gamma rays irradiated sucrose are also compared.     

Spectral,X-ray diffraction,surface morphological and thermal studies of gamma-irradiated potassium bis(oxalato)zincate(II)dihydrate

ABSTRACT

Potassium bis(oxalato)zincate(II)dihydrate was prepared and characterized. The sample was irradiated with ⁶⁰Co gamma rays up to 900?kGy. Infrared, Raman and photoluminescence spectra, X-ray diffraction pattern, surface morphology by AFM and SEM and non-isothermal decomposition of the complex were studied before and after irradiation. Spectral studies suggested significant radiation damage. X-ray diffraction studies showed reduction in unit cell volume and average crystallite size. Both unirradiated and irradiated samples of the complex belong to the hexagonal crystal system. Surface morphology of the complex changed upon irradiation. Thermal decomposition was enhanced.     

Electrochemical deposition of cerium on porous silicon to improve photoluminescence properties

In this work, we present results for Cerium (Ce) doping effects on photoluminescence (PL) properties of porous silicon (PS). Cerium was deposited using electrochemical deposition on porous silicon prepared by electrochemical anodization of P-type (100) Si. From the photoluminescence spectroscopy, it was shown that porous silicon treated with cerium can lead to an increase of photoluminescence when they are irradiated by light compared to the porous silicon layer without cerium. In order to understand the contribution of cerium to the enhanced photoluminescence, energy dispersive X-ray (EDX) spectroscopy, Fourier transmission infrared spectroscopy (FTIR), X-ray diffraction (XRD) and atomic force microscopy (AFM) were performed, and it was shown that the improved photoluminescence may be attributed to the change of Si–H bonds into Si–O–Ce bonds and to a newly formed PS layer during electrochemical Ce coating.     

Effect of radiation dose with low dose rate on degradation of propylene–ethylene copolymer

Medical grade propylene–ethylene (P–E) copolymer was irradiated by gamma rays. The radicals generated in the irradiated P–E copolymer were identified by using electron spin resonance (ESR) technique and the structural changes in the polymer were monitored with Fourier transform infrared spectroscopy (FTIR). The ESR spectra were analysed with computer simulations. The ESR studies show the formation of macro (～CH₂–?H–CH₂～), peroxy (POO˙), methyl and acyl (R–?=O) radicals and the asymmetric doublet, characteristic of peroxy radicals in the case of the sample irradiated at low dose (1 Mrad) and high doses (30 and 40 Mrad), respectively. The FTIR spectra of irradiated P–E copolymer indicate an increase in the concentration of peroxide groups. The absorption bands of –C=O and –OH groups were increased and the decline in the intensity of –CH₃ group absorption band is reported.     

Investigations of positronium formation and destruction using 3gamma/2gammaannihilation-ratio measurements

Positronium (Ps) produced by 4 to 40 eV positrons colliding with Ne, Ar, Kr, CO2, and O2 is investigated by measuring the ratio of signals of two gamma rays in coincidence resulting from (a) three gamma annihilation of ortho-Ps and (b) two annihilation gamma rays due to para-Ps decay and destruction of ortho-Ps at an aluminum scattering cell surface. These ratios provide evidence that relates to the kinetic energy dependence of ortho-Ps interactions with an aluminum surface, the Ps formation potential at this surface, and the fact that Ps is being formed with inner orbital electrons for CO2 and O2.     

Influence of 60Co gamma irradiation on the structural and optical properties of 2-aminopyridinium 4-nitrophenolate 4-nitrophenol crystals

In this article, effect of gamma irradiation on the structural and optical properties of 2-aminopyridinium 4-nitrophenolate 4-nitrophenol (2AP4N) has been reported. The grown crystals of 2AP4N were exposed to ⁶⁰Co gamma rays with a dose of 50 kGy and 100 kGy. The radiation-induced effects were analyzed using X-ray diffraction, FT-IR, UV–visible, photoluminescence techniques. The refractive index was determined using a long arm spectrometer. The structural properties of the pristine and irradiated crystals were studied using powder XRD. The peak intensity decrease after irradiation may be attributed to the formation of point defects. The UV visible study reveals that the energy gap has decreased after irradiation and then has increased for the higher dose. The intensity variation in the PL spectra is due to colour center mechanism. The SHG efficiency of 2AP4N crystals was found to be unaffected by gamma irradiation.     

重离子辐照玉米种子M1代诱变效应研究

用重离子^7Li和^12C以及^60Co的γ射线分别辐照玉米种子胚，研究重离子束辐照玉米种子M1代的生物学效应．结果表明:^60Co的丫射线使种子的发芽势和发芽率降低，重离子^7Li和^12C对发芽势和发芽率的抑制作用不明显；重离子辐照后，单株之间光合速率差异增大；M1代植株在雄性育性、叶片颜色及株高等方面发生了多种变化，并产生了一株双胚苗．应用随机多态性DNA分析技术，发现双胚苗的大、小苗之间及其与亲本自交系478在随机多态性DNA指纹上存在的差异，从分子水平上初步证实了双胚苗为自交系478的变异类型．In order to study M_(1) biological effects of heavy ion irradiation on maize seeds, the embryos of dry maize seeds are irradiated with~(7)Li ions and~(12)C ions as well as ~( 60)Co gamma rays. The results are as follows: ~( 60)Co gamma rays decrease germination impetus and germination rate of maize seeds, while the inhibitory effects of germination impetus and germination rate induced by the heavy ions~(7)Li and~(12)C are not significant. The difference of photosynthetic rates among the plants irradiate...     

Structural,electrical and optical properties of gamma irradiated methyl para-hydroxy benzoate single crystals

ABSTRACT

Nonlinear optical materials (NLO) have been garnering attention due to their role in optical data storage, optical communication and laser technology. Organic crystals have emerged as an extremely important class of NLO materials, since their NLO properties compare very well with traditional inorganic NLO materials like KCl, LiNbO₃, KDP (potassium dihydrogen phosphate), etc. They offer the additional advantage that they can be grown relatively inexpensively from solution close to room temperature, unlike the inorganic NLO materials which are grown from high temperature melts. In the present work, organic transparent single crystals of methyl para-hydroxy benzoate (MHB) were grown by slow evaporation solution growth technique (SEST) from aqueous solution at room temperature. The changes in structural, electrical and optical properties of gamma irradiated MHB single crystals were studied using X-ray diffraction (XRD), UV–Visible absorption spectroscopy, Photo-luminescence (PL), Fourier transform infrared (FTIR) spectroscopy and AC conductivity measurements at room temperature. The polished MHB single crystals were irradiated with gamma rays of doses 10 and 15 kilogray (kGy). From the XRD analysis, it was observed that gamma irradiation for these doses drastically decreases the crystallinity. The optical absorption constants were examined by UV-Visible absorption spectroscopy, measured over the wavelength range of 200–800?nm, at normal incidence. The optical band gap as estimated from the Tauc plot ((αhν)² vs hν) was found to be reduced with increasing gamma irradiation doses. PL spectra showed emission at wavelengths of 361?nm (3.43?eV) and 452?nm (2.74?eV), with enhanced intensities for the irradiated crystals. FTIR spectroscopy was utilised to identify the functional groups of MHB and indicated the rupture of specific types of bonds with gamma irradiation. Apart from that, the enhancement of AC conductivity with gamma irradiation was also observed for the gamma irradiated crystals.     

Effects of Total-Ionizing-Dose Irradiation on Single-Event Burnout for Commercial Enhancement-Mode AlGaN/GaN High-Electron Mobility Transistors

We investigate the synergism effect of total ionizing dose(TID) on single-event burnout(SEB) for commercial enhancement-mode Al Ga N/Ga N high-electron mobility transistors. Our experimental results show that the slight degradation of devices caused by gamma rays can affect the stability of the devices during the impact of high energy particles. During heavy ion irradiation, the safe working values of drain voltage are significantly reduced for devices which have already been irradiated by ~(60)Co gamma rays before. This could be attributed to more charges trapped caused by ~(60)Co gamma rays, which make Ga N devices more vulnerable to SEB. Moreover, the electrical parameters of Ga N devices after ~(60)Co gamma and heavy-ion irradiations are presented, such as the output characteristic curve, effective threshold voltages, and leakage current of drain. These results demonstrate that the synergistic effect of TID on SEB for Ga N power devices does in fact exist.     

Photoluminescence measurements of LiF TL detectors

The properties of standard lithium fluoride (LiF) thermoluminescent (TL) detectors, which are routinely used in radiation protection systems, were investigated under light stimulation. The luminescence of different types of LiF detectors, which were irradiated with gamma rays of energy up to 300 Gy and alpha particles with a fluence up to 5*10⁹ cm⁻², were stimulated by a blue light and were heated up to temperature of 240 °C or 400 °C, depending on the type of detectors. The irradiated LiF detectors during the blue-light (460 nm) stimulation emit green photoluminescence (PL) with a wavelength of 530 nm. The LiF detectors showed a PL effect of much higher efficiency after they were irradiated with alpha particles than after they were irradiated with gamma rays. However, in contrast to PL, the TL readout showed a significantly lower efficiency of LiF detectors after alpha particle irradiation. These effects result from the different trap mechanisms that are responsible for TL and PL phenomena. The temperature stability of the traps responsible for the PL effect for both types of LiF detectors was studied.     

Radiation-induced formation of ZnO nanoparticles on the ZnSe single-crystal surface

The possible formation of ZnO nanocrystals was studied as a result of radiolysis of a ZnSe crystal surface exposed to zinc vapor and irradiated with gamma rays and in producing ZnSe-ZnO heterostructures. Under ⁶⁰Co gamma radiation in air, nanocrystals ～27 nm in size are formed from nanoscopic ZnO nuclei. Under a mixed flux of gamma rays and thermal-neutron radiation, a twin structure is formed in the host ZnSe lattice and ZnO is removed. The oxide layer is also destroyed under proton irradiation in vacuum. It is found that the growth of ZnO nanocrystallites causes a manyfold increase in the luminescence intensity in the ～600-nm band and in microhardness and also a decrease in the resistance and blocking and threshold voltages irrespective of polarity. Thus, gamma irradiation brings about the formation of light-emitting ZnSe-ZnO: Zn semiconductor structures with a p-n junction.     

12C和X射线辐照人肺癌细胞H1299的生物学效应

用高传能线密度（LET）的12C离子束和低LET的X射线辐照体外培养的非小细胞肺癌H1299(p53基因缺失), 研究它们的辐照生物学效应的差异。 用克隆形成率法测定了细胞对射线的辐射敏感性; 用AnnexinV/PI试剂盒检测了细胞早期凋亡; 用流式细胞仪检测了细胞周期变化。 实验结果表明, 12C离子束辐照H1299细胞的存活率明显低于用X射线辐照的; 12C离子束引起H1299细胞的早期凋亡率明显高于X射线辐照引起的, 且持续时间更长; 12C离子束引起的H1299细胞G2/M期的抑制更明显。 说明H1299细胞对高LET的12C离子束的辐射敏感性高于对X射线的, 重离子对p53基因缺失型肿瘤的治疗可实施较低的照射剂量、 较少的照射次数和较长的时间间隔。     

Modifications induced by gamma irradiation upon structural,optical and chemical properties of polyamide nylon-6,6 polymer

The effects of gamma rays were studied on the optical, structural and chemical properties of the PA-66 polymer samples. The polymer samples obtained from Goodfellow (Cambridge, UK) were irradiated with gamma rays at various doses ranging from 100 to 1250 kGy. The pristine and gamma rays irradiated samples were characterized by UV–visible (UV–VIS) spectroscopy, X-ray diffraction (XRD) and Fourier transform infrared (FTIR) spectroscopy. UV–VIS shows a shift in absorption toward the visible region for irradiated samples and a decrease in band gap energy (E_g). The XRD analyses show an increase in the crystalline nature of the polymer at higher doses as a result of significant decrease in the peak width of XRD patterns. The FTIR spectra show decrease in intensity and shift of various bands with increase in gamma dose.     

Gamma-irradiation effect on a commercial composite anticorrosive pigment and acidity-to-alkalinity conversion

A commercial composite anticorrosive pigment based on aluminum dihydrogen tripolyphosphate was studied after exposure to gamma irradiation (Co⁶⁰, 0, 20, 50, 100 and 150?kGy) using FTIR, XRD, TGA and acid-base titration technologies. Although the FTIR spectra showed that the effect of the irradiation on functional groups in the pigments was not obvious, the decrease in the crystal lattice parameters of the irradiated pigments was observed in the XRD spectra compared to the non-irradiated sample. But the extent of the lattice parameter decrease monotonically with the increase of absorbed dose from 20 to 150?kGy, which was attributed to the decomposition of water and the simultaneous occurrence of lattice damage when the pigments were exposed to gamma rays. Of particular significance was the displayed basicity of the aqueous solutions of the irradiated pigments compared to the acidity of the solution of the non-irradiated pigment, which was attributed to the decomposition of P-OH groups (combined water).     

Effect of gamma-irradiation on thermal decomposition kinetics,X-ray diffraction pattern and spectral properties of tris(1,2-diaminoethane)nickel(II)sulphate

Tris(1,2-diaminoethane)nickel(II)sulphate was prepared, and characterised by various chemical and spectral techniques. The sample was irradiated with ⁶⁰Co gamma rays for varying doses. Sulphite ion and ammonia were detected and estimated in the irradiated samples. Non-isothermal decomposition kinetics, X-ray diffraction pattern, Fourier transform infrared spectroscopy, electronic, fast atom bombardment mass spectra, and surface morphology of the complex were studied before and after irradiation. Kinetic parameters were evaluated by integral, differential, and approximation methods. Irradiation enhanced thermal decomposition, lowering thermal and kinetic parameters. The mechanism of decomposition is controlled by R₃ function. From X-ray diffraction studies, change in lattice parameters and subsequent changes in unit cell volume and average crystallite size were observed. Both unirradiated and irradiated samples of the complex belong to trigonal crystal system. Decrease in the intensity of the peaks was observed in the infrared spectra of irradiated samples. Electronic spectral studies revealed that the M–L interaction is unaffected by irradiation. Mass spectral studies showed that the fragmentation patterns of the unirradiated and irradiated samples are similar. The additional fragment with m/z 256 found in the irradiated sample is attributed to S₈⁺. Surface morphology of the complex changed upon irradiation.     

Thermoluminescence de la glace

Different samples of normal and heavy water are irradiated with gamma rays at Liquid Nitrogen temperature and, then, progressively warmed up. During this period the thermoluminescent glow is recorded and its intensity and emission spectrum analyzed in function of temperature and irradiation dose. One of the two emission peaks appear to be directly linked to the network structure within the ice.     

TL and PTTL in natural fluorite previously irradiated with gamma rays and heavy ions

The effect of annealing temperature on the phototransfer thermoluminescence (PTTL) signal was studied to determine the appropriate annealing temperature for treating the natural powder before irradiation. The temperatures used to anneal virgin natural fluorite samples (only natural dose without giving the samples any artificial doses) were 150, 250, 350, 450, 550, 650 and 750°C for a duration of 1 h in each case. The results show that the PTTL response did not change for anneal temperatures up to 450°C, but at higher temperatures the signal decreased rapidly. The height of the 90°C peak decreased by two orders of magnitude as the anneal temperature increased from 450 to 750°C, whilst the height of the 180°C peak decreased by three orders of magnitude between the same two annealing temperatures. In order to investigate the effect of previous gamma rays and heavy ion irradiation on thermoluminescence (TL) and PTTL signals, powdered samples of natural fluorite from Cornwall, England, were annealed at 500°C and then irradiated (at GSI, Darmstadt, Germany) with ¹⁶¹Dy ions of energy 13 Mev/n; the range of fluences used was from 10⁴ to 10¹² ion cm⁻². Identical samples were given gamma doses in the range 1 Gy to 2.6 × 10⁴ Gy in order to compare the effects of gamma rays and heavy ions. The sensitivities of TL and PTTL were studied by giving the samples a gamma test dose of 1 Gy after annealing the samples at 500°C for 30 min in order to eliminate the TL resulting from previous gamma or heavy ion irradiation.