Information about the polydispersity of soot can in principle be gained from time-resolved laser-induced incandescence (LII) using pre-assumed particle-size distributions. This paper introduces an alternative method, called two-exponential reverse fitting (TERF) that is based on combined mono-exponential fits to the LII signal decay at various delay times. The method approximates the particle-s...

Light absorption by carbon soot increases when the particles are internally mixed with nonabsorbing materials, leading to increased radiative forcing, but the magnitude of this enhancement is a subject of great uncertainty. We have performed laboratory experiments of the optical properties of fresh and internally mixed carbon soot aerosols with a known particle size, morphology, and the mixing ...

The size distributions of nanoparticles in flames are measured using a novel particle mass spectrometer (PMS), which is developed for the size range between 0.3 and 50 nm and for number concentrations between 10(9) and 10(13). Using this instrument the particles are sampled without prior dilution from the flame into a molecular beam. The charged nanoparticles are then deflected by an electric f...

Measurements of aerosol particle number size distributions (18–700 nm), mass concentrations (PM2.5 and PM10) and NOx were performed in the Plabutsch tunnel, Austria, and in the Kingsway tunnel, United Kingdom. These two tunnels show different characteristics regarding the roadway gradient, the composition of the vehicle fleet and the traffic frequency. The submicron particle size distributions ...

Soot particulates are sampled from a EURO-IV standards diesel engine and investigated by high-resolution electron microscopy (HRTEM) and thermal gravimetry (TG). The experiments reveal a drastic reduction of primary particle size down to less than 20 nm, much smaller than that emitted by earlier diesel engines (EURO I-III). HRTEM reveals primary particles with deformed fullerenoid structures. T...

Laser ablation of surfaces normally produce high temperature plasmas that are difficult to control. By irradiating small particles in the gas phase, we can better control the size and concentration of the resulting particles when different materials are photofragmented. Here, we irradiate soot with 193 nm light from an ArF excimer laser. Irradiating the original agglomerated particles at fluenc...

Chemical composition, size, and mixing state of atmospheric particles are critical in determining their effects on the environment. There is growing evidence that soot aerosols play a particularly important role in both climate and human health, but still relatively little is known of their physical and chemical nature. In addition, the atmospheric residence times and removal mechanisms for soo...

Particles containing soot, or black carbon, are generally considered to contribute to global warming. However, large uncertainties remain in the net climate forcing resulting from anthropogenic emissions of black carbon (BC), to a large extent due to the fact that BC is co-emitted with gases and primary particles, both organic and inorganic, and subject to atmospheric ageing processes. In this ...

Investigations into the chemical composition of soot particles often rely on samples extracted from the flame environment for subsequent analysis by mass spectrometry. These mass spectra have contributed to the general consensus that polycyclic aromatic hydrocarbons (PAHs) are involved in soot nucleation and surface growth processes. In the pioneering work of Dobbins et al., soot and soot precu...

We report the first mass-specific absorption and extinction cross sections for size- and mass-selected laboratory-generated soot aerosol. Measurement biases associated with aerosols possessing multiple charges were eliminated using mass selection to isolate singly charged particles for a specified electrical mobility diameter. Aerosol absorption and extinction coefficients were measured using p...