Improvement of on-line characterization of aerosol particles by means of laser based ionization techniques in a time-of-flight mass spectrometer

人为环境气溶胶对健康有负面影响（颗粒物问题），并与气候有关（凝结核特性、光吸收等）。由于气溶胶的高度动态特性，在线实时分析技术的发展在气溶胶理化性质检测中占有突出地位。单颗粒气溶胶激光飞行时间质谱法（S-ATOFMS）允许对单个颗粒的粒度和化学组成进行表征。随着新的S-ATOFMS技术，其中有机分子的颗粒分辨解吸（LD/TD）和软光电离方法（REMPI/SPI）相结合，第一次质谱检测单个气溶胶颗粒中的有机化合物变得可行。例如，可以实现对致癌和有毒的多环芳烃（PAH）的在线检测。然而，到目前为止，可以研究单个颗粒的无机或有机成分。在拟议项目的框架内，将开发和测试一种新的仪器S-ATOFMS概念。因此，气溶胶颗粒在其通过离子源的飞行中通过尺寸测定之后，将首先被激光解吸并通过质谱法研究有机分子（具有REMPI的PAH）。几微秒后，同一颗粒核心的无机基质将通过另一种质谱技术（LDI）进行测量。除了一个新的激光电离和电离室设置的发展，在使用的双极飞行时间质谱仪中的一个非常快速的极性反转的实施是必要的。在线获取单个气溶胶粒子的无机和有机成分的信息是非常重要的，因为只有这种方法允许一个强大的和全面的，单粒子分辨的粒子集合源属性。新技术的第一个测试应用包括除了环境测量之外，船舶柴油发动机的特别相关的排放（特别是当由重质燃料油驱动时）。后一项测量将与罗斯托克大学活塞机和内燃机系主任合作进行。

Anthropogenic ambient aerosols exhibit negative health effects (particulate matter problem) and are relevant for the climate (condensation nucleus properties, light absorption etc.). Due to the highly dynamic character of aerosols the development of on-line real-time analytical techniques takes a prominent position for the detection of their physico-chemical properties. Single particle aerosol laser time-of-flight mass spectrometry (S-ATOFMS) allows for characterization of individual particles toward both, particle size and chemical composition. With a new S-ATOFMS technique, where particle resolved desorption of organic molecules (LD/TD) and soft photo-ionization methods (REMPI/SPI) are combined, for the first time mass spectrometric detection of organic compounds from single airborne aerosol particles became feasible. For example, an on-line detection of carcinogenic and toxic polycyclic aromatic hydrocarbons (PAH) could be realized. However, until now, individual particles could be investigated for either inorganic or organic components. In the framework of the proposed project a novel instrumental S-ATOFMS concept will be developed and tested. Thereby, an aerosol particle, after passing the size determination on its flight through the ion source, will first be laser-desorbed and investigated for organic molecules (PAH with REMPI) by mass spectrometry. A few micro seconds later, the inorganic matrix of the same particle core will be measured by another mass spectrometric technique (LDI). Besides the development of a new laser ionization and ionization chamber setup, the implementation of a very fast polarity reversal in the utilized bipolar time-of-flight mass spectrometer is necessary. The on-line acquisition of information about inorganic and organic components of single aerosol particles is of great importance, since only this approach permits a robust and comprehensive, single particle resolved source attribution of particle ensembles. First test applications of the novel technique comprise besides ambient measurements the particularly relevant emissions of ship diesel engines (especially when driven by heavy fuel oil). The latter measurements will be conducted in cooperation with the chair of piston machines and internal combustion engines at the university of Rostock.