Size dependent partitioning of organic material: evidence for the formation of organic coatings on aqueous aerosols     

T. Anttila  A. Kiendler-Scharr  Th. F. Mentel  R. Tillmann 《Journal of Atmospheric Chemistry》2007,57(3):215-237

Organic aerosol formation resulting from the ozonolysis of α-pinene, myrcene and sabinene was investigated in a large aerosol chamber in the presence of aqueous seed aerosols. The chemical composition of the particles was monitored by an aerosol mass spectrometer (Aerodyne Research Inc.) as a function of time and the particle size. Smaller particles were found to contain more organics relative to sulfate than the larger ones. In contrast, the water to sulfate mass ratio was not dependent on the particle size. These experimental findings indicate the formation of organic layers on the particles. With the aid of an aerosol dynamic model we demonstrate that the observations are consistent with the formation of multilayered organic films having thicknesses of approximately 10 nm. The results also suggest that the films were formed through condensation of low-volatile oxidation products that did not take up water considerably. Even though dissolution of oxidation products into the particle aqueous phase cannot be conclusively ruled out, the most plausible interpretation of the results is that the monoterpene ozonolysis lead to the formation of organic coatings on aqueous aerosols. Such films are likely to form in regions with monoterpene emissions.  相似文献   

A novel high-resolution small ion spectrometer to study ion nucleation of aerosols in ambient indoor and outdoor air     

A.P. Fews  N.K. Holden  P.A. Keitch  D.L. Henshaw 《Atmospheric Research》2005,76(1-4):29

An electrically based ion spectrometer is described, capable of measuring particle sizes and mobilities from molecular ions (small ions) to aerosol particles across a size range of 0.4 to 30 nm in diameter. It consists of a single cylindrical capacitor divided into three electrically insulated sections. The current arriving at the central section is measured by an electrometer and represents the ion flux over a known range of mobilities determined by the applied voltage. The applied voltage is scanned in steps to measure the ion fluxes over a large number of overlapping mobility ranges. The recorded signal and the response function of the instrument are unfolded using a maximum entropy procedure to give a high-resolution measured mobility spectrum. The maximum entropy approach offers a considerable improvement over traditional aspiration collectors and can approach the resolution of a drift tube system. In this way, the spectrometer successfully overcomes the diffusion limit to small ion resolution. Illustrative spectra are shown, demonstrating for the first time the presence of some resolved structure within the small ion spectrum at the highest mobilities. It is demonstrated that the actual mobility spectrum of small ions falls in the range 0.8–2.0 × 10⁻⁴ m² V⁻¹ s⁻¹. This represents a narrower range than that previously measured which is attributed to improved spectral resolution in the present work.  相似文献   

地下水中NO-3的15N和18O同位素测试新技术--密封石英管燃烧法   总被引：10，自引：0，他引：10  

杨琰  蔡鹤生  刘存富  周爱国 《水文地质工程地质》2005,32(2):20-24

近40年来,硝酸盐(NO-3)已成为最普遍的地下水污染源之一。在本文中,介绍了在野外用阴离子交换树脂收集地下水中的NO-3的新技术;用AgNO3和氧化铜丝及铜颗粒燃烧反应测定氮同位素比值;用AgNO3 C(石墨)测定NO-3中氧同位素比值的密封石英管燃烧法,它们是1995年以后发展起来的最新测试技术。  相似文献   

成像干涉光谱仪信噪比分析   总被引：7，自引：2，他引：5  

金锡哲  向阳  禹秉熙 《遥感学报》2000,4(3):194-196

以Ｓａｇｎａｃ型成像干涉（傅里叶变换）光谱仪为例,详细推导了空间笛制型成像干涉光谱仪信噪比的一般表达式,分析了各种因素与信噪比之间的关系并得出了相应的结论。  相似文献   

OMIS成像光谱数据信噪比的估算   总被引：7，自引：1，他引：6  

陈秋林  薛永祺 《遥感学报》2000,4(4):284-289

实用型模块化成像光谱仪 (OperationalModularImagingSpectrometerOMIS)是一种带有稳定平台的新型机载遥感器。具有 12 8波段 ,覆盖了从可见光到热红外的光谱范围 ,其应用范围有地质、农业、林业和海洋等领域。在分析OMIS数据中的噪声特性之后 ,指出OMIS系统中各通道的噪声是和信号无关的加性噪声 ,噪声自身并不相关。并且对比分析了现有的 4种信噪比估算方法。指出基于空间和光谱维去相关的方法比较可靠 ,并给出实际的计算结果。最后指出在大气订正后 ,图像数据的信噪比能充分反映仪器的信噪比性能。  相似文献   

一种新的实用型城市基础信息采集系统--轻型飞机成像光谱集成技术系统     

岑长华  肖青  张杰林  刘京晶  于宏  何钟琦  崔振奎 《铀矿地质》2000,16(2):115-120

1∶5 0 0 0比例尺城市用地和建筑物分类制图是目前城市规划和管理领域迫切需要的基本图件之一。本文从该图件对机载成像光谱图像数据的客观要求出发 ,介绍了一种新的城市基础信息采集系统的组成、应解决的关键技术问题、所采集的成像光谱数据的几何和分类精度及实际生产作业效果  相似文献   

野外多道伽马能谱测量在核环境地质评价中的应用   总被引：5，自引：2，他引：3  

方方  李宽良  侯新生  吴允平  王小琴  祖秀兰 《物探与化探》2000,24(1):7-11

介绍了最新研制的CD-10野外便携式伽马全谱仪工作原理和主要技术指标。该仪器对伽马射线能量分析范围是30～3000keV,分析道数为1024道,对¹³⁷Cs的能量分辨率小于12%,取消了放射性稳谱参考源,采用数字稳谱技术,实现了无干扰天然伽马射线全谱(30～3000keV)测量,并以在核环境地质评价中的应用实例,说明了伽马全谱仪的主要特点和应用前景。  相似文献   

冀北凹陷高于庄组与洪水庄组在岩芯、露头中多赋存态生物标志物的对比     

崔景伟 《沉积学报》2011,29(3):593-598

利用气相色谱-质谱联用仪对采自燕山地区冀北凹陷的中元古界长城系高于庄组(Chg)灰岩和蓟县系洪水庄组(Jxh)泥页岩露头和岩芯中不同赋存状态生物标志物进行了分析.正构烷烃和萜类生物标志物显示从高于庄组(Chg)到洪水庄组(Jxh)生源由浮游类和底栖类为主转变为浮游类为主,而沉积水体的盐度则由高变低.露头样品和相应岩芯中...  相似文献   

γ能谱测井分层解释中实用形态系数的模型实测法研究     

尹旺明  佘冠军  汤彬 《铀矿地质》2011,27(2):108-114

从γ测井分层解释方法形态系数的物理意义出发,探讨了利用模型测定实用形态系数的原理与方法,提出了实用形态系数的近似计算公式。同时采用HPGeγ谱仪对饱和测井模型进行了试验测量,结果理想,论证了该方法的可行性。  相似文献   

一种仿黑皮仔料拼合石的鉴定特征     

周钊  杨明星  支颖雪  姜宏远 《地质科学译丛》2011,(4):39-42

和田仔料随着市场的追捧,其价格越来越高,仿制品层出不穷。借助宝石显微镜、偏光显微镜、X射线粉末衍射和红外光谱等测试手段,对武汉市徐东古玩珠宝市场上出现的一种仿黑皮仔料材料进行了宝石学、矿物学以及谱学特征鉴定。结果显示,该仿黑皮仔料材料由黑色霞石岩、白色软玉以及有机黑胶三部分拼合而成;其与黑皮仔料的主要鉴定特征在于：前者在横截面上有明显的拼合痕迹以及特征的红外光谱有机官能团区吸收峰。  相似文献