IngentaConnect Nanoparticle production by UV irradiation of combustion generated...

Authors: Christopher Stipe¹; Jong Choi¹; Donald Lucas²; Catherine Koshland³; Robert Sawyer¹

Source: Journal of Nanoparticle Research, Volume 6, Number 5, October 2004 , pp. 467-477(11)

Publisher: Springer

Abstract:

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/cm² 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 265 nm. 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.

Keywords: ablation; aerosols; nanoparticles; particles; photofragmentation; soot

Document Type: Research article

DOI: 10.1007/s11051-004-2162-9

Affiliations: 1: Mechanical Engineering Department, University of California at Berkeley, CA, USA, 2: Environmental Energy Technologies Division, Lawrence Berkeley National Laboratory, CA, USA, Email: d_lucas@lbl.gov 3: School of Public Health, University of California at Berkeley, CA, USA,

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Nanoparticle production by UV irradiation of combustion generated soot particles