MRI: Development of an Aerosol Impact Spectrometer

有了这个由化学研究仪器和设施（CRIF）和化学测量和成像（CMI）计划共同资助的主要研究仪器（MRI）计划的奖项，来自加州圣地亚哥大学的Robert Continetti教授将建立一个新型的气溶胶撞击光谱仪（AIS）。AIS将提供一种新的实验方法，用于研究50纳米至1微米尺寸范围内的带电气溶胶颗粒的化学性质，利用激光解吸电离和超高速撞击惰性表面来分析化学成分和形态。分析过程包括一系列精心设计的步骤。该仪器将首先在四极离子阱中捕获颗粒/气溶胶，如果需要，可以对其进行化学修饰，然后将其依次喷射到图像电荷质谱仪中以确定质量和电荷状态。然后，颗粒将在冲击单晶金刚石表面之前被加速到高速。带电产物的化学分析将采用飞行时间质谱（TOF-MS），碰撞脱附的中性物质将采用真空紫外激光光电离TOF-MS进行分析。碰撞速度的变化将为研究质量分辨单粒子的化学性质随深度的变化提供新的变量，产生一种类似于广泛使用的二次离子质谱（西姆斯）技术的气溶胶研究技术，该技术使用已知离子颗粒的影响来表征表面。气溶胶和纳米颗粒的化学性质对于理解环境和生物系统具有广泛的重要性，并且进一步发展技术以理解颗粒的化学性质作为尺寸的函数，例如质谱法，是必不可少的。质谱法通过多种方法蒸发和电离样品。粒子（母离子和碎片离子）流入质谱仪，在那里测量它们的质荷比。这种高灵敏度的技术可以确定颗粒的质量，它们的化学成分，并使人们能够推断出复杂混合物中物质的结构。将开发的仪器将在质谱法（超高速撞击）中应用一种新的分析工具，该工具将广泛应用于以单粒子质量分辨的详细程度表征复杂的纳米粒子和气溶胶。这将产生关于气溶胶和颗粒化学的独特信息，并将在化学，生物学和环境研究等不同领域中有用。研究的最初重点将是大气气溶胶和生物改性合成纳米颗粒。这个研究项目也将有助于培养新一代的乐器演奏家在国家的最先进的技术。

With this award from the Major Research Instrumentation (MRI) Program that is co-funded by the Chemistry Research Instrumentation and Facilities (CRIF) and the Chemical Measurements and Imaging (CMI) Programs, Professor Robert Continetti from the University of California San Diego will build a novel aerosol impact spectrometer (AIS). The AIS will provide a new experimental approach for the study of the chemistry of charged aerosol particles in the 50 nm to 1 micron size range, providing analysis of the chemical composition and morphology using both laser desorption ionization (LDI) and hypervelocity impact on an inert surface. The analytical process involves a series of carefully choreographed steps. The instrument will first trap particles/aerosols in a quadrupole ion trap, where they can be chemically modified if desired, and sequentially eject them into an image-charge mass spectrometer to determine the mass and charge state. The particles will then be accelerated to a high velocity prior to impact on a single-crystal diamond surface. Chemical analysis of charged products will be performed by time-of-flight mass spectrometry (TOF-MS) and neutral species desorbed on impact will be analyzed by vacuum ultraviolet laser photoionization TOF-MS. Variation of the velocity of impact will provide a new variable for studying the chemical properties of mass-resolved single particles as a function of depth, yielding a technique for aerosol studies analogous to the widely used secondary ion mass spectrometry (SIMS) technique that uses the impact of known ionic particles to characterize surfaces. The chemistry of aerosols and nanoparticles has broad importance to understanding environmental and biological systems, and further development of techniques to understand the chemistry of particles as a function of size, such as mass spectrometry, is essential. Mass spectrometry vaporizes and ionizes a sample by a variety of methods. The particles (parent and fragment ions) flow into a mass spectrometer where their mass/charge ratios are measured. This highly sensitive technique allows determination of the masses of the particles, their chemical composition and enables one to deduce the structure of the substances in a complex mixture. The instrument that will be developed will apply a new analytical tool in mass spectrometry (hypervelocity impact) that will have broad application for the characterization of complex nanoparticles and aerosols at a single-particle mass-resolved level of detail. This will yield unique information on the chemistry of aerosols and particles and will be useful in fields as diverse as Chemistry, Biology and Environmental studies. The initial focus of the studies will be on atmospheric aerosols and biologically modified synthetic nanoparticles. This research project will also help train a new generation of instrumentalists in state-of-the-art techniques.