Laser-based diagnostics for the in situ characterization of non-soot nanoparticles

基于激光的非烟灰纳米颗粒原位表征诊断

基本信息

批准号：
222540104
负责人：
Professor Dr. Christof Schulz
金额：
--
依托单位：
Lehrstuhl für Reaktive Fluide
依托单位国家：
德国
项目类别：
Research Grants
财政年份：
2013
资助国家：
德国
起止时间：
2012-12-31 至 2020-12-31
项目状态：
已结题

来源：
https://gepris.dfg.de/gepris/projekt/222540104?language=en
关键词：
Laser based diagnostics situ characterization

项目摘要

Methods that allow an in situ characterization of inorganic nanoparticles during gas-phase synthesis are only little explored - despite the importance to produce defined product qualities. This deficiency is not only due to the poorly known optical properties of such nanomaterials but also because experiments are missing enable direct comparison of optical in situ measurements and conventional (ex situ) particle characterization. The aim of this project is, based on laser-induced incandescence (LII) as a method established for soot diagnostics, to further develop diagnostics for particle size and volume fraction of the inorganic materials systems silicon (Si), germanium (Ge), iron (Fe), and copper (Cu). New insights obtained for Si within the project SCHU 1369/14-1 will be further deepened towards applicability and extended to the other material systems whose optical properties are so far incompletely known in the relevant temperature range. The nanoparticles are generated and optically analyzed in a microwave-plasma reactor at pressures between 30 and 900 mbar. First, the wavelength-dependent absorption function (E(m)) will be determined via line-of-sight absorption (LOSA) investigating the optical properties of the particles both in the absence and the presence of a heating laser pulse that is used for LII. Photodiodes or a combination of a spectrometer and a streak camera will serve as detection units. It is also planned to demonstrate the applicability of a phenomenon that has been discovered for Si in the first proposal period: Liquid-solid phase transitions can be observed via their absorption/emission spectra. This will also be further pursued for the other materials systems. In addition, fluence-dependent incandescence spectra and their temporal development (time-resolved LII) will be recorded for all materials systems and analyzed with respect to their emission properties in the context of particle-size determination. Fluence values will be increased into the range where full particle evaporation is achieved without gas breakdown. This allows to explore the origin of non-thermal emissions that can interfere with the LII signal (Bremsstrahlung, "anomalous cooling" during the LII-process). Particle-based atomic emissions will be investigated (intensity, emission lifetimes) during low-fluence LIBS (laser-induced breakdown) processes in the context of practical applicability. With the optical measurements, particle-size distributions will be determined using inline particle mass spectrometry (PMS) from within the same probe volume. In addition, by thermophoretic sampling and ex situ transmission electron microscopy (TEM) and Raman analysis, particle size and crystallinity will be investigated. All results taken together will strongly increase our knowledge in in particle optical properties and diagnostics and provide valuable input parameters for the underlying models that are required for quantitative analysis of LII and LIBS signals.

尽管很少探索生产定义的产品质量，但允许在气相合成过程中允许原位表征无机纳米颗粒的原位表征。这种缺陷不仅是由于此类纳米材料的光学特性鲜为人知，而且还因为实验缺失了能够直接比较光学原位测量值和常规（EX）粒子表征。该项目的目的是基于激光诱导的白炽灯（LII）作为用于烟灰诊断的方法，以进一步开发无机材料系统硅尺寸和体积分数硅（SI），锗（GE），铁（Fe），铁（FE）和铜（CU）的诊断。 Schu 1369/14-1中SI获得的新见解将进一步加深适用性，并扩展到其他材料系统，其光学特性到目前为止在相关温度范围内尚不完全了解。在30至900 MBAR之间的压力下，在微波式等离子反应器中生成并在微波式等离子反应器中进行光学分析。首先，将通过研究颗粒的光学特性（LOSA）在不存在和存在用于LII的加热激光脉冲的情况下研究颗粒的光学特性来确定依赖波长的吸收功能（E（M））。光电二极管或光谱仪和条纹摄像头的组合将用作检测单元。还计划证明在第一个提案期间发现SI的现象的适用性：可以通过其吸收/发射光谱观察液固相变。对于其他材料系统，这也将进一步追求。此外，将记录所有材料系统的依赖性依赖性白炽灯及其时间发育（时间分辨LII），并在粒度确定的背景下对其发射特性进行分析。通量值将增加到无气体破坏而实现全颗粒蒸发的范围。这允许探索可能干扰LII信号的非热排放的起源（Bremsstrahlung，在Lii-Process期间“异常冷却”）。在实际适用性的情况下，将研究基于粒子的原子排放（强度，发射寿命）（激光诱导的分解）过程。通过光学测量，将使用同一探针体积内的内联粒子质谱法（PMS）确定粒度分布。另外，将研究通过嗜热抽样和现场透射电子显微镜（TEM）和拉曼分析，粒度和结晶度。所有结果一起将大大提高我们在粒子光学性能和诊断方面的知识，并为LII和LIBS信号定量分析所需的基础模型提供有价值的输入参数。