Abstract:For the first time, to the best of our knowledge, laser-induced incandescence (LII) has successfully been applied to carbon black suspensions. A linear correlation between the experimentally derived signal decay time and the mean primary particle size, determined by transmission electron microscopy, for different carbon black particles was found. Moreover, a nonlinear relation similar to that known from measurements of aerosols was observed for the peak LII signal and the laser fluence. Despite different heat … Show more
“…In 2007, Sommer and Leipertz [509] carried out an investigation devoted to the pulsed-LIIsignal decay times of carbon-black dispersions. For the ten carbon blacks employed, they found a linear correlation between the LII-decay time and the primary-particle size from TEM.…”
The understanding of soot formation in combustion processes and the optimization of practical combustion systems require in situ measurement techniques that can provide important characteristics, such as particle concentrations and sizes, under a variety of conditions. Of equal importance are techniques suitable for characterizing soot particles produced from incomplete combustion and emitted into the environment. Additionally, the production of engineered nanoparticles, such as carbon blacks, may benefit from techniques developed. This review discusses considerations for selection of laser and detection characteristics to address application-specific needs. The benefits of using LII for measurements of a range of nanoparticles in the fields mentioned above are demonstrated with some typical examples, covering simple flames, internal-combustion engines, exhaust emissions, the ambient atmosphere, and nanoparticle production. We also remark on less well-known studies employing LII for particles suspended in liquids.An important aspect of the paper is to critically assess the improvement in the understanding of the fundamental physical mechanisms at the nanoscale and the determination of underlying parameters; we also identify further research needs in these contexts. Building on this enhanced capability in describing the underlying complex processes, LII has become a workhorse of particulate measurement in a variety of fields, and its utility continues to be expanding. When coupled with complementary methods, such as light scattering, probe-sampling, molecular-beam techniques, and other nanoparticle instrumentation, new directions for research and applications with LII continue to materialize.
“…In 2007, Sommer and Leipertz [509] carried out an investigation devoted to the pulsed-LIIsignal decay times of carbon-black dispersions. For the ten carbon blacks employed, they found a linear correlation between the LII-decay time and the primary-particle size from TEM.…”
The understanding of soot formation in combustion processes and the optimization of practical combustion systems require in situ measurement techniques that can provide important characteristics, such as particle concentrations and sizes, under a variety of conditions. Of equal importance are techniques suitable for characterizing soot particles produced from incomplete combustion and emitted into the environment. Additionally, the production of engineered nanoparticles, such as carbon blacks, may benefit from techniques developed. This review discusses considerations for selection of laser and detection characteristics to address application-specific needs. The benefits of using LII for measurements of a range of nanoparticles in the fields mentioned above are demonstrated with some typical examples, covering simple flames, internal-combustion engines, exhaust emissions, the ambient atmosphere, and nanoparticle production. We also remark on less well-known studies employing LII for particles suspended in liquids.An important aspect of the paper is to critically assess the improvement in the understanding of the fundamental physical mechanisms at the nanoscale and the determination of underlying parameters; we also identify further research needs in these contexts. Building on this enhanced capability in describing the underlying complex processes, LII has become a workhorse of particulate measurement in a variety of fields, and its utility continues to be expanding. When coupled with complementary methods, such as light scattering, probe-sampling, molecular-beam techniques, and other nanoparticle instrumentation, new directions for research and applications with LII continue to materialize.
“…LII has historically been used to characterise combustion aerosols using pulsed lasers, [41][42][43][44] but has been observed only recently for particles in liquid suspensions. 45 The ability to observe incandescence depends on whether the absorbed energy can be dissipated at a sufficiently high rate and therefore depends on numerous factors: particle surface/volume ratio, heat conductivity of the surroundings, laser flux and the occurrence of chemical reactions and phase changes. 44 In our case, we did not observe qualitative differences in emission between particles of different specific surface area.…”
Section: Raman-optical Tweezer Studies Of Carbon Microspheresmentioning
Carbon based materials are attractive for biological applications because of their excellent biocompatibility profile. Porous carbons with high specific surface area are particularly interesting because it is possible in principle to leverage their properties to deliver high drug payloads. In this work, porous carbon microspheres with high specific surface area were prepared and studied in solution and in cells. Raman optical tweezer trapping of microspheres, excited by 532 nm, results in graphitization and 10 incandescence in solvents that display poor heat conduction. Fluorescence confocal microscopy imaging was used to demonstrate the uptake of fluorescently labelled microspheres by cells and the ability to leverage their optical absorptivity in order to cause carbon graphitization and cell death.
“…The variation of peak temperature or peak incandescence with laser fluence (a so-called “fluence curve”) also provides important insight into absorption efficiency and evaporation. These measurements have been carried out for carbon black [ 187 , 188 ], CNTs [ 175 , 180 , 181 ], and FLG [ 41 ] (Fig. 16 ).…”
Laser-induced incandescence (LII) is a widely used combustion diagnostic for in situ measurements of soot primary particle sizes and volume fractions in flames, exhaust gases, and the atmosphere. Increasingly, however, it is applied to characterize engineered nanomaterials, driven by the increasing industrial relevance of these materials and the fundamental scientific insights that may be obtained from these measurements. This review describes the state of the art as well as open research challenges and new opportunities that arise from LII measurements on non-soot nanoparticles. An overview of the basic LII model, along with statistical techniques for inferring quantities-of-interest and associated uncertainties is provided, with a review of the application of LII to various classes of materials, including elemental particles, oxide and nitride materials, and non-soot carbonaceous materials, and core–shell particles. The paper concludes with a discussion of combined and complementary diagnostics, and an outlook of future research.
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