A criterion to define soot maturity, a theoretical modeling approach to simulate it, and its effects on the surface reactivity of soot primary particles in laminar premixed and diffusion flames are presented in the first two chapters. It is shown that the core-shell internal nanostructure of soot primary particles is a function of the overall soot Hydrogen to Carbon (H/C) ratio and can be used to distinguish nascent from mature soot primary particles. The importance of considering dehydrogenation to predict the H/C ratio and maturity of soot is illustrated. It is shown that the decay of soot surface reactivity with maturity, i.e. soot aging, is a strong function of the internal nanostructure of soot primary particles. The necessity of simulating soot maturity for comparison with experimental measurements is discussed. Structural effects of biodiesel in terms of unsaturation, i.e. C-C double bond, its position, and the presence of the ester moiety on soot formation are investigated in chapters four and five. It is shown that unsaturation increases soot formation by higher production of soot chemical growth species while more centrally located double bond increases soot formation by producing more soot nucleating species. However, the ester moiety decreases soot formation by reducing the concentration of soot chemical growth species such as acetylene. Several experimental techniques for measuring flame temperature, soot volume fraction, primary particle diameter, and aggregate structure are compared to each other in the last chapter. It is shown that Time Resolved Laser Induced Incandescence is the most reliable method to measure the volume fraction and the primary particle diameter of mature soot particles. The sensitivity of thermocouple measurements to radiation correction is analyzed and it is shown that for accurate temperature measurement with a thermocouple, it is essential to use a locally measured variable emissivity to estimate radiation cooling effects.

Our interest in Mulhouse for carbon black and soot began some 30 years ago when J.B. Donnet developed the concept of surface chemistry of carbon and its involvement in interactions with gas, liquid and solid phases. In the late sixties, we began to study soot formation in pyrolytic systems and later on in flames. The idea of organ1z1ng a meeting on soot formation originated some four or five years ago, through discussions among Professor J.B. Howard, Dr. A. D'Alessio and ourselves. At that time the scientific community was becoming aware of the necessity to strictly control soot formation and emission. Being involved in the study of surface properties of carbon black as well as of formation of soot, we realized that the combustion community was not always fully aware of the progress made by the physical-chemists on carbon black. Reciprocally, the carbon specialists were often ignoring the research carried out on soot in flames. One objective of this workshop was to stimulate discussions between these two scientific communities. During the preparation of the meeting, and especially during the review process by the Material Science Committee of the Scientific Affairs Division of N.A.T.O. the toxicological aspect emerged as being an important component to be addressed during the workshop. To reflect these preoccupations we invited biologists, physical chemists and engineers, all leaders in their field. The final programme is a compromise of the different aspects of the subject and was divided in five sessions.

Soot Formation in Combustion represents an up-to-date overview. The contributions trace back to the 1991 Heidelberg symposium entitled "Mechanism and Models of Soot Formation" and have all been reedited by Prof. Bockhorn in close contact with the original authors. The book gives an easy introduction to the field for newcomers, and provides detailed treatments for the specialists. The following list of contents illustrates the topics under review:

During the first year of the present grant, efforts have concentrated on examining the effects of fuel molecular structure on soot formation in diffusion flames. Studies involving alkane, alkene, alkyne and aromatic fuel species have been studied with specific attention given to the surface growth process. Analysis of these studies has demonstrated a strong fuel structure dependence for the amount of soot formed, the conversion percentage of fuel carbon to soot, and the soot particle surface area present in these diffusion flames. However, when surface area taken into account, similar specific surface growth rate coefficients are observed for all the fuels studied. These results point to a similar surface growth process for all the fuels. Consistent with premixed flame results, the present studies show a continual decrease in this specific surface growth rate coefficient with time. Other effects of fuel structure observed include an acceleration of the inception of soot particles to lower locations and, thus, earlier times in the flame as soot conversion percentage increases. These results also point to the importance of the initial particle inception process which appears to control subsequent soot particle evolution. Keywords: Soot formation; Soot particles; Diffusion flames.

Effects of fuel doping and fuel chemistry on soot formation were studied in laminar diffusion flames at elevated pressures. Soot spectral emission is used to obtain radial temperature, soot volume fraction, and soot yield profiles. This thesis first investigated addition of 0%-40% ethanol in ethylene flames at 3-10 bar. 10% ethanol-doped flames didn't exhibit measurable soot synergy, whereas 20%-40% ethanol displayed lower soot yields. Secondly, 7.5% of benzene, cyclo-hexane and n-hexane was added into methane flames at 1.4-10 bar. Pressure dependence of sooting propensity is lowest for benzene. Thirdly, 3% of m-xylene and n-octane was mixed with methane at 1.4-10 bar. m-Xylene doped methane flames produced highest soot yields but lowest pressure dependency in soot yields. Results indicate that pressure dependence of highly sooting aromatics weakens compared to that of less sooting n-alkanes at high pressures.