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Combustion Physics

Lund University

X-ray scattering on particles and precursors

Linda Vallenhag, Frederik Ossler, Sophie Canton* and Jörgen Larsson**

Contact person: Frederik Ossler

There is a great need of understanding the processes that control particle production in combustion. Soot is known to be produced in different combustion processes and is known to have negative effects on human health and environment. During the last years more and more evidence has turned up from different research groups that smaller particles, potentially more harmful than soot, are released from combustion sources. In order to understand the dynamics of the particle production processes one needs instruments with sufficient structural resolution. This project aims at measuring these particles in-situ with a structural resolution below the nanometer scale using X-ray scattering diagnostics, which should give new possibilities to investigate the details of particle generation processes and structural dynamics.

The wavelength of the X-rays are of the order 1000 times shorter that the wavelength from visible and ultraviolet radiation yielding a much higher resolving power than for instance laser techniques. Therefore X-ray scattering techniques can be used a complementary tool in combustion studies. Photons in the hard X-ray region (5 keV-12 keV energy, or 2.5 Å to 1.0 Å wavelength) from a synchrotron source are sent into a flame. The photons scattered by the molecules and particles inside the flame are analyzed angularly resolved with a special detector. The resulting scattering patterns as a function of scattering angle or momentum exchange are analyzed and compared with scattering calculations in order to retrieve information about the size and structure of the species present.

The research involves studies of particle generation and dynamics, development of diagnostic tools (detectors and methodology) and combining X-ray and laser diagnostics as complementary tools.

*   Department of Chemical Physics, Lund University

** Division of Atomic Physics, Department of Physics, Lund University

 

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