Combined particle- and time-of-flight mass spectrometry in flame-based nanoparticle synthesis

点击翻译按钮获取中文摘要

Flame-based nanoparticle synthesis is governed by a complex interplay between homogeneous gas-phase reactions, particle inception, growth, and dynamics as well as surface chemistry. To establish a deeper understanding of the processes involved the synthesis of nanoparticles in a laminar, premixed, low-pressure, flat-flame reactor will be studied as a function of reaction time and flame composition (equivalence ratio, fuel, precursor) using molecular-beam mass spectrometry. Within the first period of the project, promising experiments utilizing analysis of gas-phase chemistry via time-of-flight mass-spectrometry (TOF-MS) in combination with particle-size distributions measured by particle mass spectrometry (PMS) emerged. For the first time we were able to measure concentration profiles of metal oxide clusters in good agreement with the growth of the first stable nanoparticles during gas-phase synthesis.The aim of this proposal is to continue the research strategy described in the proposal for the first funding period. One important improvement will be to use single-photon photoionization with VUV photons (9.8 eV) for the time-of-flight mass spectrometer to reduce the formation of multiply-charged clusters and molecular fragments. The possibility to study the stoichiometry of the particle inline should be validated by comparing detailed TOF-MS measurements with ex situ photo electron spectroscopy (XPS) and Auger spectroscopy (SAM). The results of the project will be used on the one hand to validate existing chemical kinetics mechanisms for the flame synthesis of tailored nanomaterials and on the other hand to establish new reaction mechanisms if needed.