Vacuum Ultraviolet Free-Electron Laser Photoionization Mass Spectrometry of Alpha-pinene Ozonolysis

\begin{document}$\alpha$\end{document}-pinene is the most abundant monoterpene that represents an important family of volatile organic compounds. Molecular identification of key transient compounds during the \begin{document}$\alpha$\end{document}-pinene ozonolysis has been proven to be a challenging experimental target because of a large number of intermediates and products involved. Here we exploit the recently developed hybrid instruments that integrate aerosol mass spectrometry with a vacuum ultraviolet free-electron laser to study the \begin{document}$\alpha$\end{document}-pinene ozonolysis. The experiments of \begin{document}$\alpha$\end{document}-pinene ozonolysis are performed in an indoor smog chamber, with reactor having a volume of 2 m\begin{document}$^3$\end{document} which is made of fluorinated ethylene propylene film. Distinct mass spectral peaks provide direct experimental signatures of previously unseen compounds produced from the reaction of \begin{document}$\alpha$\end{document}-pinene with O\begin{document}$_3$\end{document}. With the aid of quantum chemical calculations, plausible mechanisms for the formation of these new compounds are proposed. These findings provide crucial information on fundamental understanding of the initial steps of \begin{document}$\alpha$\end{document}-pinene oxidation and the subsequent processes of new particle formation.     

Ion chromatograph with three-dimensional printed absorbance detector for indirect ultraviolet absorbance detection of phosphate in effluent and natural waters

An ion chromatography system employing a low-cost three-dimensional printed absorbance detector for indirect ultraviolet detection towards portable phosphate analysis of environmental and industrial waters has been developed. The optical detection cell was fabricated using stereolithography three-dimensional printing of nanocomposite material. Chromatographic analysis and detection of phosphate were carried out using a CS5A 4 × 250 mm analytical column with indirect ultraviolet detection using a 255 nm light-emitting diode. Isocratic elution using a 0.6 mM potassium phthalate eluent combined with 1.44 mM sodium bicarbonate was employed at a flow rate of 0.75 mL/min. A linear calibration range of 0.5 to 30 mg/L PO₄³⁻ applicable to environmental and wastewater analysis was achieved. For retention time and peak area repeatability, relative standard deviation values were 0.68 and 4.09%, respectively. Environmental and wastewater samples were analyzed with the optimized ion chromatography platform and the results were compared to values obtained by an accredited ion chromatograph. For the analysis of environmental samples, relative errors of <14 % were achieved. Recovery analysis was also carried out on both freshwater and wastewater samples and recovery results were within the acceptable range for water analysis using standard ion chromatography methods.     

真空紫外光电离质谱技术进展及其在快速分析中的应用

真空紫外光电离源(VUV-PI)是一种普适性的质谱软电离源,真空紫外光电离质谱谱图无碎片、易解析、灵敏度高,适合于在线快速分析。真空紫外光电离质谱根据分析对象不同可以直接采用单光子电离或添加掺杂剂实现化学电离,能实现气、液、固体分析,也可实现成像分析。该文介绍了真空紫外光电离源的电离原理、光源类型,分析了光电离质谱灵敏度的影响因素及其技术改进措施,并阐述了真空紫外光电离质谱技术在环境污染物、化工产物在线分析、国家安全分析以及生物医学分析中的相关应用研究。最后,总结了真空紫外光电离源的优缺点,并对真空紫外光电离技术在性能和应用方面的发展前景进行了展望。     

Mediated Generation of Conjugate Acid by UV and Blue Sensitizers with Upconversion Nanoparticles at 980 nm

NIR and UV exposure of systems comprising upconversion nanoparticles ( UCNP ) based on NaYF₄:Tm/Yb@NaYF₄, a sensitizer absorbing either in the blue or UV region, and an onium salt with weak coordinating anion resulted in formation of conjugate acid (con-H⁺). That was namely Ivocerin (di(4-methoxybenzoyl)diethylgermane), ITX (2-iso-propyl thioxanthone), anthracene, pyrene, rubrene, camphore quinone, and a strong fluorescent coumarin (1,1,6,6,8-pentamethyl-2,3,5,6-tetrahyhdro-1H,4H-11-oxa-3a-aza-benzo[de]anthracene-10-one). Quantification occurred by treatment with Rhodamine B lactone whose color switched to intensive red after photolytic formation of con-H⁺. Exposure with a NIR laser at 980 nm resulted in less con-H⁺ compared to 395 nm where all sensitizers absorb radiation. UCNP did not mainly interfered formation of con-H⁺. The different rates obtained in both experiments responsibly explain the failure and success to initiate polymerization of epoxides applying ether 980 nm or 395 nm excitation, respectively.     

用于宽谱带发射白色发光二极管的黄色荧光粉Sr8MgAl(PO4)7∶xEu2+的制备及发光性能

通过高温固相反应合成了一系列宽谱带发射黄色荧光粉Sr_8MgAl(PO_4)_7∶x Eu~(2+)(SMAP∶x Eu~(2+)),并对其物质结构、发光性能及其在白色发光二极管(WLED)领域的应用进行了探究。X射线衍射(XRD)测试结果表明,SMAP∶x Eu~(2+)系列荧光粉具有单斜结构和C2/m空间群,激活剂Eu~(2+)离子能够很好地进入SMAP基质中并占据Sr~(2+)离子的晶格位点。漫反射光谱分析显示SMAP基质属于宽带隙材料,带隙宽度为3.60 e V。此外,SMAP∶x Eu~(2+)具有较宽的激发范围(280～500 nm),对应于Eu~(2+)离子的4f~7→4f~65d~1跃迁;在380 nm近紫外光激发下,呈现出450～800 nm的多发光中心的非对称黄光发射,发射峰位于590 nm处。基于高斯多峰拟合结果,得到3个发光中心,分别位于528、600和680 nm。最后,将已制备的黄色荧光粉SMAP∶0.05Eu~(2+)与商业化蓝粉Ba Mg Al_(10)O_(17)∶Eu~(2+)混合涂覆到400 nm芯片上制得色温较好(3 344 K)、显色指数较高(90.1)的WLED。     

Upgrade of beamline BL08B at Taiwan Light Source from a photon‐BPM to a double‐grating SGM beamline

During the last 20 years, beamline BL08B has been upgraded step by step from a photon beam‐position monitor (BPM) to a testing beamline and a single‐grating beamline that enables experiments to record X‐ray photo‐emission spectra (XPS) and X‐ray absorption spectra (XAS) for research in solar physics, organic semiconductor materials and spinel oxides, with soft X‐ray photon energies in the range 300–1000 eV. Demands for photon energy to extend to the extreme ultraviolet region for applications in nano‐fabrication and topological thin films are increasing. The basic spherical‐grating monochromator beamline was again upgraded by adding a second grating that delivers photons of energy from 80 to 420 eV. Four end‐stations were designed for experiments with XPS, XAS, interstellar photoprocess systems (IPS) and extreme‐ultraviolet lithography (EUVL) in the scheduled beam time. The data from these experiments show a large count rate in core levels probed and excellent statistics on background normalization in the L‐edge adsorption spectrum.     

微弱日盲紫外电晕自动实时检测方法

针对目前商用日盲紫外/可见光双谱段电晕探测仪对故障的判定效率低且容易受噪声干扰问题,本文提出了一种微弱日盲紫外电晕自动实时检测方法。在分析电晕目标和噪声时间域统计特性的基础上,该方法利用电晕目标在时间域连续的特点,首先完成灰度图像二值化、形态学膨胀等预处理,其次将N帧连续图像累加后阈值化,最后进行特征提取,获取电晕位置、面积等特征信息,实现电晕的自动实时检测。在完成设备辐射标定的基础上,可立即回溯得到故障的光子计数参考值。建立了该方法的探测概率、虚警率数学模型。将其在高速数字处理平台TMS320DM642上实现并输入测试视频,结果表明:在典型参数情况下该方法单次检测虚警概率为2.85×10^-5,处理时间小于120 ms,可实现微弱日盲紫外电晕的实时检测。     

SnO_2/TiO_2纳米管复合光催化剂的性能及失活再生

基于微波水热法和微乳液法合成SnO2/TiO2纳米管复合光催化剂.通过X射线衍射(XRD)、配有能量色散X射线光谱仪(EDX)的透射电镜(TEM)和电化学手段对光催化剂进行表征.以甲苯为模型污染物,考察光催化剂在紫外光(UV)和真空远紫外光(VUV)下的性能及失活再生.结果表明,SnO2/TiO2纳米管复合光催化剂形成三元异质结(锐钛矿相TiO2(A-TiO2)/金红石相TiO2(R-TiO2)、A-TiO2/SnO2和R-TiO2/SnO2异质结),促使光生电子-空穴对的有效分离,提高光催化活性.SnO2/TiO2表现出最佳的光催化性能,UV和VUV条件下的甲苯降解率均达100%,CO2生成速率(k2)均为P25的3倍左右.但由于UV光照矿化能力不足,中间产物易在催化剂表面累积.随着UV光照时间的增加,SnO2/TiO2逐渐失活,20 h后k2由138.5 mg·m-3·h-1下降到76.1 mg·m-3·h-1.利用VUV再生失活的SnO2/TiO2,过程中产生的·OH、O2-·、O(1D)、O(3P)、O3等活性物质可氧化吸附于催化剂活性位的难降解中间产物,使催化剂得以再生,12 h后k2恢复到143.6 mg·m-3·h-1.UV和VUV的协同效应使UV降解耦合VUV再生成为一种可持续的光催化降解污染物模式.     

Determination of tetraethyl ammonium by ion-pair chromatography with indirect ultraviolet detection using 4-aminophenol hydrochloride as background ultraviolet absorbing reagent

A method was developed for the determination of tetraethyl ammonium (TEA) by reversed-phase ionpair chromatography with indirect ultraviolet detection. Chromatographic separation was achieved on a reversed-phase C18 column using background ultraviolet absorbing reagent - ion-pair reagent - organic solvent as mobile phase. The effects of the background ultraviolet absorbing reagents, detection wavelength, ion-pair reagents, organic solvents and column temperature on the determination method were investigated and the retention rules discussed. Results found that TEA could be successfully analyzed by using 0.7 μmol/L 4-aminophenol hydrochloride and 0.15 μmol/L 1-heptanesulfonic acid sodium mixed with 20% (v/v) methanol asmobile phase at a UV detection wavelength of 230 nm. Under these conditions, the retention time of tetraethyl ammonium was 2.85 min. The detection limit (S/N = 3) for TEA was 0.06 mg/L. The relative standard deviations (n = 5) for peak area and retention time were 0.35% and 0.02%, respectively. The method has been successfully applied to the determination of synthesized tetraethyl ammonium bromide. Recovery of tetraethyl ammonium after spiking was 99.1%.     

紫外荧光硫分析仪用燃烧管的结构改进研究

对紫外荧光硫分析仪用石英燃烧管进行了结构改进,在原结构设计的基础上,增加了裂解氧预热管、挡板和氧气反吹口等。实验表明,相比于原结构设计的石英燃烧管进样量20μL和检出限0.2 mg/L,改进后的燃烧管进样量提高到了100μL,检出限达0.05 mg/L,线性范围为0.1～600 mg/L,相关系数大于0.999。采用改进后的燃烧管测定10.0 mg/L硫含量标准物质,其相对偏差为–1.5%～3.1%,测定结果的相对标准偏差为1.77%(n=10),两者均符合油品硫含量检测要求。改进后的燃烧管可替代市场上的其它国产石英燃烧管,进行油品中硫含量的测定。