Determination of N and O‐atoms and N2 (A) Metastable Molecule Densities in the Afterglows of N2‐H2, Ar‐N2‐H2 and Ar‐N2‐O2 Microwave Discharges

Early afterglows of N₂‐H₂, Ar‐N₂‐H₂ and Ar‐N₂‐O₂ flowing microwave discharges are characterized by optical emission spectroscopy. The N and O atoms and the N₂ (A) metastable molecule densities are determined by optical emission spectroscopy after calibration by NO titration for N and O‐atoms and measurements of NO and N₂ band intensities. If an uncertainty of 30% is estimated on N‐atomic density, an inaccuracy of one order of magnitude is obtained on the O and N₂ (A) densities. In N₂‐(0.05‐2.5%)H₂ and Ar‐(1‐50%)N₂‐(0.05‐2.5%) H₂ gas mixtures, the O‐atoms are coming from O₂ impurities in the discharge. Concentrations of N and O‐atoms and of N₂ (A) densities are compared to the ones obtained in Ar‐(5‐50%)N₂‐(0.2‐2.5%) O₂ gas mixtures in which a controlled amount of O₂ is added. (© 2014 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)     

不同激发波长对Sr3Al2O6∶Eu2+,Dy3+红色长余辉发光材料发射光谱的影响

采用高温固相法合成了Sr3Al2O6∶Eu2+,Dy3+长余辉发光材料。用X射线衍射仪及荧光分光光度计对材料物相及光谱性能进行了分析。结果表明:所得样品为Sr3Al2O6的纯相,在360nm波长的激发下,得到波峰为537nm的宽带发射光谱;在468nm波长的激发下,得到波峰为590nm的宽带发射光谱;在波长为394nm的激发下,537和590nm的峰同时出现。根据晶格场效应和电子云膨胀效应,对不同激发波长对Sr3Al2O6∶Eu2+,Dy3+发射光谱的影响进行了解释。结果表明:在Sr3Al2O6∶Eu2+,Dy3+中发光中心因其5d能级劈裂幅度不同及4f65d1能带重心不同而导致发光颜色的不同。     

Etching of polyethylene terephthalate thin films by neutral oxygen atoms in the late flowing afterglow of oxygen plasma

Films of polyethylene terephthalate were deposited on quartz crystals and exposed to oxygen atoms to study their etching characteristics and quantify the etching rate. Oxygen (O) atoms were created by passing molecular oxygen through plasma created in a microwave discharge. The discharge power was fixed at 250 W, while the pressure of oxygen was 50 Pa. Before exposure to oxygen atoms, a thin polymer film of polyethylene terephthalate (PET) was deposited uniformly over a crystal with a diameter of 12 mm. The crystal was mounted on a quartz crystal microbalance to accurately determine the thickness of the polymer film. The polymer film was exposed to O atoms in the flowing afterglow. The density of O atoms was measured with a cobalt catalytic probe mounted next to the sample and was determined to be 1.2 × 10²¹ m^–3. Samples were treated with O atoms for different periods of up to 120 min. The thickness of the film decreased linearly with treatment time. After 90 min of treatment, a 65‐nm‐thick polymer film was completely removed. Therefore, the etching rate was 0.5 nm/min, so the interaction probability between an O atom and an atom in the sample was extremely low, just 1.4 × 10^–6. Samples treated for different periods were investigated by atomic force microscopy and X‐ray photoelectron spectroscopy to examine the etching characteristics of O atoms in the flowing afterglow. Copyright © 2012 John Wiley & Sons, Ltd.     

Afterglow工作模式下ECR离子源脉冲束的产生

为满足国家大科学工程兰州重离子冷却储存环的要求,在14.5GHz ECR 离子源上进行afterglow工作模式的实验,首次产生了高电荷态脉冲束流Ar¹¹⁺和Ar¹²⁺,给出了初步实验结果,并对结果进行了分析和解释.     

An Investigation of the Positive Column of a Cd–Ne Glow Discharge: II. Afterglow

The afterglow of a Cd–Ne glow discharge is investigated theoretically and experimentally. The time-dependent electron Boltzmann equation and the balance equations for the Cd excited states and charged particles have been self-consistently solved. The temporal relaxation of the electron energy distribution function, electron, and cadmium excited states densities is reported and the influence of neon and cadmium vapor pressure on the plasma characteristics in the afterglow is studied. The modeling compares favorably with experimental results.     

Ar (3P0,2 )与SO2反应产生SO (A″ 3Σ+)的光谱

On the flowing afterglow apparatus, in the energy transfer reaction between Ar (3P0,2) and SO2, two series of spectra were observed at two different downstream optical windows from the discharge region. According to the data obtained in this group’s report on the discharge of the mixture of Ar with SO2 and spectral simulation, the two spectrum progressions in the range of 320 and 600 nm were assigned to SO (A″3Σ+→X 3Σ-) and SO (c 1Σ-→X 3Σ-), respectively. The spectroscopic constants for the new electronic state were obtained by spectral simulation based on the method of the least square and shown as follows: T00 =(30460±18.0) cm-1, ωe′=(685±0.8) cm-1 and ωe′χe′=(7.7±8.0) cm-1.     

Pb在锗酸镉基质中的长余辉发光特性

通过高温固相反应在空气中制得单相Cd₂Ge₇O₁₆:Pb²⁺长余辉发光材料.分析了Cd₂Ge₇O₁₆和Cd₂Ge₇O₁₆:Pb²⁺的激发光谱和发射光谱,指出Pb²⁺的发光是该离子的³P₁-¹S₀跃迁产生的;分析了Cd₂Ge₇O₁₆:Pb²⁺的发光存在基质对Pb²⁺的能量传递;并把长余辉性质归结为基质中Cd离子的挥发产生的空穴陷阱.提出了长余辉发光机理模型.     

Mn4+掺杂的新型铝酸盐红色长余辉材料

用高温固相法合成了红色长余辉发光材料LiAl₅O₈:Mn⁴⁺,Li₅AlO₄:Mn⁴⁺,LiAlO₂:Mn⁴⁺,发现前两种材料有红色余辉,这方面并没有报道过,并对这两种材料的发光性能作了研究,指明了不同基质中发光强弱不同原因。对不同Mn⁴⁺掺杂浓度的材料做了浓度依赖关系研究,确认Mn⁴⁺的发光是²E→⁴A₂的跃迁。Mn⁴⁺的发光是个宽带谱,材料在紫外区有强的吸收,发射谱范围可达620~770nm,峰值在675nm。对长余辉机制进行了探讨。     

高超音速流场中锥体边界层转捩图象的纹影显示及处理

本文介绍了一种大画幅纹影成像技本,应用该技术,显示了高超音速流场中锥体边界层转捩。将所得到的纹影图象在显微密度计图象处理系统中进行处理与测量,并结合纹影法原理进行了分析计算,得到了边界层诸截面相对密度变化曲线以及边界层转捩位置等实验结果,该结果与有关气动理论和实践结果进行了比较。     

(Eu2+,Nd3+): CaAl2O4的长余辉发光及机理的研究

采用高温固相反应法制备了Eu²⁺: CaAl₂O₄、(Eu²⁺,Nd³⁺): CaAl₂O₄, 等系列材料.测量了其激发、发射光谱及余辉衰减曲线.分析了掺杂稀土离子对长余辉发光的作用.并对其发光机理进行了深入地探讨.