Photoionization mass spectrometry for the investigation of combustion generated nascent nanoparticles and their relation to laser induced incandescence
Photoionization mass spectrometry for the investigation of combustion generated nascent nanoparticles and their relation to laser induced incandescence
复制标题
用于研究燃烧产生的新生纳米粒子及其与激光诱导白炽光的关系的光电离质谱法
DOI：
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发表时间：
2011
期刊：
影响因子：
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通讯作者：
K. Hoffmann
中科院分区：
文献类型：
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作者：
H. Grotheer;K. Wolf;K. Hoffmann
利用光电离质谱（PIMS）技术研究了乙烯预混层流平板火焰对初生纳米粒子的作用。使用一个大气的麦肯纳燃烧器和乙烯空气火焰耦合到一个大气采样系统，在一个相对较窄的C/O范围内，发现这些粒子的两种模式，这可以清楚地区分它们的温度依赖性，它们的反应性，和它们的电离行为。在柴油机后面观察到了同样的颗粒，这些结果用低压乙烯-O2火焰与高分辨率质谱仪联用得到了证实。在这种情况下，由于特殊的入口系统，可以在相当宽的C/O范围内操作火焰而不会堵塞入口喷嘴。这允许追求的发展，颗粒尺寸分布函数（PSDF）以及成熟的烟灰的制度。此外，在低质量侧的粒子光谱测量与统一的分辨率是可能的，这允许获得有关它们的生长机制和结构的信息。最后，在试图模仿激光诱导白炽（LII）实验的煤烟负载的分子束暴露于红外辐射。这导致在LII典型的注量下新生颗粒几乎完全被破坏。发现了3 ~ 17个C原子的小C原子团簇，此外，在高得多的强度下，还检测到了包含数百个C原子的团簇，后者甚至在完全不存在小团簇的非常低的能量密度下也能检测到。
Premixed laminar flat ethylene flames were investigated for nascent nanoparticles through photoionization mass spectrometry (PIMS). Using an atmospheric McKenna burner and ethylene air flames coupled to an atmospheric sampling system, within a relatively narrow C/O range two modes of these particles were found, which can be clearly distinguished with regard to their temperature dependence, their reactivity, and their ionization behaviour. Behind a diesel engine the same particles were observed.These results were corroborated using a low pressure ethylene–O2 flame coupled to a high resolution mass spectrometer. In this case, due to a special inlet system, it was possible to operate the flame in a fairly wide C/O range without clogging of the inlet nozzles. This allowed pursuing the development of particle size distribution functions (PSDF) well into the regime of mature soot. In addition, on the low mass side of the particle spectra measurements with unity resolution were possible and this allowed gaining information concerning their growth mechanism and structure.Finally, in an attempt to mimic Laser Induced Incandescence (LII) experiments the soot-laden molecular beam was exposed to IR irradiation. This resulted in a near complete destruction of nascent particles under LII typical fluences. Small C clusters between 3 and 17 C atoms were found. In addition and with much higher intensities, clusters comprising several hundreds of C atoms were also detected, the latter even at very low fluences when small clusters were totally absent.