Nanoparticle production by UV irradiation of combustion generated soot particles
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 fluences ranging from 0.07 to 0.26 J/cm{sup 2} with repetition rates of 20 and 100 Hz produces a large number of small, unagglomerated particles, and a smaller number of spherical agglomerated particles. Mean particle diameters from 20 to 50 nm are produced from soot originally having a mean electric mobility diameter of 265nm. We use a non-dimensional parameter, called the photon/atom ratio (PAR), to aid in understanding the photofragmentation process. This parameter is the ratio of the number of photons striking the soot particles to the number of the carbon atoms contained in the soot particles, and is a better metric than the laser fluence for analyzing laser-particle interactions. These results suggest that UV photofragmentation can be effective in controlling particle size and morphology, and can be a useful diagnostic for studying elements of the laser ablation process.
- Research Organization:
- Lawrence Berkeley National Lab. (LBNL), Berkeley, CA (United States)
- Sponsoring Organization:
- US Department of Energy (US)
- DOE Contract Number:
- AC03-76SF00098
- OSTI ID:
- 840577
- Report Number(s):
- LBNL-55790; R&D Project: 80XN01; TRN: US0502061
- Journal Information:
- Journal of Nanoparticle Research, Vol. 6, Issue 5; Other Information: Submitted to Journal of Nanoparticle Research: Volume 6, No.5; Journal Publication Date: 10/2004; PBD: 1 Jul 2004
- Country of Publication:
- United States
- Language:
- English
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