Spectroscopic properties of Pr3+ and Er3+ ions in lead-free borate glasses modified by BaF2

Lead-free oxyfluoride borate glasses singly doped with Pr³⁺ and Er³⁺ were prepared and next investigated using absorption and luminescence spectroscopy. In the studied glass system, barium oxide was substituted by BaF₂. Two luminescence bands of Pr³⁺ located at visible spectral region are observed, which correspond to ³P₀–³H₄ (blue) and ¹D₂–³H₄ (reddish orange) transitions, respectively. The luminescence bands due to ¹D₂–³H₄ transition of Pr³⁺ are shifted to shorter wavelengths, when BaO was substituted by BaF₂. Near-infrared luminescence spectra of Er³⁺ ions in lead-free borate glasses modified by BaF₂ correspond to ⁴I_13/2–⁴I_15/2 transition. Their spectral linewidths increase with increasing BaF₂ concentration. The changes in measured lifetimes of rare earth ions are well correlated with the bonding parameters calculated from the optical absorption spectra.     

Spectroscopic properties and amplified spontaneous emission of fluorescein laser dye in ionic liquids as green media

The use of ionic liquids (ILs) as milieu materials for laser dyes is a promising field and quite competitive with volatile organic solvents and solid state-dye laser systems. This paper investigates some photo-physical parameters of fluorescein dye incorporated into ionic liquids; 1-Butyl-3-methylimidazolium chloride (BMIM Cl), 1-Butyl-3-methylimidazolium tetrachloroaluminate (BMIM AlCl₄) and 1-Butyl-3-methylimidazolium tetrafluoroborate (BMIM BF₄) as promising host matrix in addition to ethanol as reference. These parameters are: absorption and emission cross-sections, fluorescence lifetime and quantum yield, in addition to the transition dipole moment, the attenuation length and oscillator strength were also investigated. Lasing characteristics such as amplified spontaneous emission (ASE), the gain, and the photostability of fluorescein laser dye dissolved in different host materials were assessed. The composition and properties of the matrix of ILs were found that it has great interest in optimizing the laser performance and photostability of the investigated laser dye. Under transverse pumping of fluorescein dye by blue laser diode (450 nm) of (400 mW), the initial ASE for dye dissolved in BMIM AlCl₄ and ethanol were decreased to 39% and 36% respectively as time progressed 132 min. Relatively high efficiency and high fluorescence quantum yield (11.8% and 0.82% respectively) were obtained with good photostability in case of fluorescein in BMIM BF₄ that was decreased to ∼56% of the initial ASE after continuously pumping with 400 mW for 132 min.     

CMP后的晶圆的测量和评估方法研究

综述了CMP后的晶圆测量方法,比较指出：光学干涉法适宜于测量较厚的薄膜,而椭圆偏振法精度较高,但成本高昂,适宜于测量薄的薄膜。CMP后需要检测晶圆的表面状况,列举了常用的扫描电子显微镜、原子力显微镜和光散射探测仪。扫描电子显微镜常用于特征线宽的测量,其精度可达4nm;原子力显微镜是根据范德华力的原理制造,其探测精度高达0．1nm：但二者最大的缺陷就是操作复杂,成像十分费时。散射探测仪根据光的散射理论制造。可以快捷地全表面成二维图像,是值得推荐的一种测量手段。最后,指出今后的测量技术对半导体工艺的影响。     

Temperature-driven local rearrangement in the Er environment of Er-doped silica glass films prepared by rf-cosputtering deposition

In this paper, an experimental study is presented on Er:SiO₂ films prepared by an rf-cosputtering deposition technique, and then annealed in the 100-1200 °C range. Samples were characterized by spectrally resolved cathodoluminescence, UV-VIS photoluminescence and Rutherford Backscattering Spectrometry (RBS). Strong optical modifications with temperature were observed, connecting the peculiar features of the Er luminescence activity to those of the silica matrix, namely, the density of nonbridging oxygen hole centers, oxygen-deficient sites and OH groups. In general, a complex phenomenology was observed, involving major local rearrangements of the Er environment. RBS data allowed to evidence migration phenomena, resulting in a compositional change of the films, thus indicating the progressive modification of the system as well as the possible formation of Er nanoclusters for high temperatures.     

Synthesis, crystal structures, and optical properties of NaCdPnS3 (Pn = As, Sb)

Two compounds NaCdPnS₃ (Pn = As (1), Sb (2)) were synthesized as transparent yellow and red platelets by reacting cadmium powder with the molten mixtures of Na₂S/As₂S₃/S and Na₂S/Sb/S at 500 °C. Both compounds are plagued with crystal twinning and acceptable crystal structure refinement could only be obtained by identifying the type of the twinning laws. NaCdAsS₃ (1) crystallizes in the monoclinic space group P2₁/n (no. 14) with a = 5.6561(8), b = 16.5487(15), c = 5.6954(8) Å, β = 90.315(11)°, and Z = 4. NaCdSbS₃ (2) crystallizes in the monoclinic space group C2/c (no. 15) with a = 8.1329(6), b = 8.1296(4), c = 17.2600(13) Å, β = 103.499(6)°, and Z = 8. The structures of both compounds feature a ²_∞[CdPnS₃]⁻ layer composed of [CdS₄] tetrahedra and [AsS₃] or [SbS₃] pyramidal units. Between the ²_∞[CdPnS₃]⁻ (Pn = As, Sb) layers the Na⁺ cations reside in a distorted octahedral environment of S atoms. Compound 1 is characterized with UV/Vis diffuse reflectance spectroscopy and IR and Raman spectra.     

CMP中薄膜厚度问题研究

就目前CMP建模当中没有考虑到芯片表面的薄膜氧化所需时间对模型建立所产生的影响,以至最后模型的预测结果与试验结果相差甚多的问题进行探讨.在基于理论分析的基础上提出以椭偏仪法测定出芯片表面薄膜生成厚度与浸泡时间精确的对应关系.试验结果表明:在模型建立时,芯片表面薄膜厚度的生成时间对模型的建立有着重要影响,精确测定其时间对应关系将有助于使得所建模型的预测结果与试验结果进一步吻合.     

Mixed-valence state of Ce and its individual atomic moments in Ce2Fe14B studied by soft X-ray magnetic circular dichroism

We performed soft X-ray absorption spectroscopy (XAS) and X-ray magnetic circular dichroism (XMCD) measurements at Fe L_2,3-edges and Ce M_4,5-edges on Ce₂Fe₁₄B at 300 K. The valence and total atomic moment of Ce in Ce₂Fe₁₄B were determined to be ∼+3.12 and ∼0.100 μ _B, respectively, which mainly stem from a large portion of the well-localized 4f ¹ configurations. Besides, the individual orbital and spin moments of Ce in Ce₂Fe₁₄B as well as those of Fe were determined for the first time with consideration of the magnetic dipole term.     

荧光法研究Gemini表面活性剂与BSA的相互作用

应用荧光法研究了Gemini表面活性剂(G14-3-14)与牛血清白蛋(BSA)在不同温度条件下的荧光猝灭现象,利用荧光猝灭双倒数图计算了G14-3-14与BSA之间的结合常数,并根据热力学参数确定了二者之间的作用力类型.用内源荧光法求得它们在30℃和35℃温度下的结合常数分别为K1=1.01×105 L·mol-1和...     

Photoluminescence of dysprosium doped antimony-magnesium-strontium-oxyfluoroborate glasses

Dysprosium (Dy³⁺)-doped antimony-magnesium-strontium-oxyfluoroborate (B₂O₃ MgF₂ SrO Sb₂O₃ Dy₂O₃, BMFSrSbD), glasses were synthesized by traditional melt-quenching method. The synthesized samples have been analyzed by X-ray diffraction, optical absorption and fluorescence techniques for deriving various characteristic properties. Emission spectra of Dy³⁺: samples were exhibit three well resolved emission bands at around 482, 575 and 666?nm which originated from the ⁴F_9/2→⁶H_15/2,⁴F_9/2→⁶H_13/2 and ⁴F_9/2→⁶H_11/2 transitions upon excitation of wavelength at 452?nm. Decay curves of the ⁴F_9/2 level of Dy³⁺ ion were display mono-exponential at low Dy³⁺ concentration (0.1?mol%) and deviated to non-exponential behavior at high concentration of Dy³⁺ ions (≥?0.5?mol%). Lifetime of the ⁴F_9/2 level was decreased with increase of Dy³⁺ ions concentration. Chromaticity coordinates (x,y) of Dy³⁺:BMFSrSbD samples were evaluated and represented in CIE 1931 chromaticity diagram, appear in the whitish-yellow region. The results suggest that these glasses could be utilized as a potential candidate for the development of display devices and lasers at a wavelength of 575?nm.     

Spectroscopic ellipsometry characterization of amorphous carbon and amorphous, graphitic and fullerene-like carbon nitride thin films

Carbon nitride (CN_x) and amorphous carbon (a-C) thin films are deposited by reactive magnetron sputtering onto silicon (001) wafers under controlled conditions to achieve amorphous, graphitic and fullerene-like microstructures. As-deposited films are analyzed by Spectroscopic Ellipsometry in the UV-VIS-NIR and IR spectral ranges in order to get further insight into the bonding structure of the material. Additional characterization is performed by High Resolution Transmission Electron Microscopy, X-ray Photoelectron Spectroscopy, and Atomic Force Microscopy. Between eight and eleven resonances are observed and modeled in the ellipsometrically determined optical spectra of the films. The largest or the second largest resonance for all films is a feature associated with C-N or C-C modes. This feature is generally associated with sp³ C-N or sp³ C-C bonds, which for the nitrogen-containing films instead should be identified as a three-fold or two-fold sp² hybridization of N, either substituted in a graphite site or in a pyridine-like configuration, respectively. The π→π? electronic transition associated with sp² C bonds in carbon films and with sp² N bonds (as N bonded in pyridine-like manner) in CN_x films is also present, but not as strong. Another feature present in all CN_x films is a resonance associated with nitrile often observed in carbon nitrides. Additional resonances are identified and discussed and moreover, several new, unidentified resonances are observed in the ellipsometric spectra.