Particle formation from pulsed laser irradiation of soot aggregates studied with a scanning mobility particle sizer, a transmission electron microscope, and a scanning transmission x-ray microscope.
We investigated the physical and chemical changes induced in soot aggregates exposed to laser radiation using a scanning mobility particle sizer, a transmission electron microscope, and a scanning transmission x-ray microscope to perform near-edge x-ray absorption fine structure spectroscopy. Laser-induced nanoparticle production was observed at fluences above 0.12 J/cm(2) at 532 nm and 0.22 J/cm(2) at 1064 nm. Our results indicate that new particle formation proceeds via (1) vaporization of small carbon clusters by thermal or photolytic mechanisms, followed by homogeneous nucleation, (2) heterogeneous nucleation of vaporized carbon clusters onto material ablated from primary particles, or (3) both processes.
Michelsen
Hope A
HA
Combustion Research Facility, Sandia National Laboratory, P.O. Box 969, Mail Stop 9055, Livermore, California 94551-0969, USA. hamiche@sandia.gov
Tivanski
Alexei V
AV
Gilles
Mary K
MK
van Poppel
Laura H
LH
Dansson
Mark A
MA
Buseck
Peter R
PR