| This thesis presents four studies exploring laser particle interactions for particle production and measurement.;An inverted, co-flow burner is created as a source of combustion generated soot for comparing and calibrating current particle measurement techniques, developing new diagnostic techniques, and for inhalation health studies. The burner produces agglomerated soot particles composed of roughly 40 nm spherical primary particles. By varying the net equivalence ratio or by diluting the fuel stream with nitrogen, the burner generates particles with mean electric mobility diameters from 50 to 250 nm and volume concentrations from 2.5 ppt to 3 ppb.;Single laser excimer laser fragmentation fluorescence spectroscopy (ELFFS) is further explored to improve its analytical capabilities. In previous work, atomic carbon fluorescence (1P10 → 1S0) generated by single laser ELFFS was monitored as a signature for combustion generated soot. In this thesis, the atomic carbon fluorescence signal is shown to depend on the volume concentration of soot when irradiated at 34 J/cm2, with an improved detection limit of 60 ppt. The fluorescence signal is independent of the laser fluence for all conditions studied (15 to 60 J/cm2), suggesting the volume concentration dependence holds over this range of fluences. However, the fluence itself is not an accurate parameter for determining the extent of particle disintegration.;A new, non-dimensional parameter is created to estimate the extent of particle disintegration. The PAR is the ratio of the energy absorbed by the particle to the necessary atomization energy of the particle and provides an upper limit of the fraction of atoms liberated by the incident laser pulse. At a PAR of unity, the particle absorbs adequate energy to atomize completely if the disintegration process is perfectly efficient.;Laser-particle interactions are also studied by irradiating a stream of particles flowing through a quartz cuvette. A Scanning Mobility Particle Sizer (SMPS) and Scanning Electron Microscope (SEM) measure the irradiated soot and NaCl particles, determining the modification of the original particle size distribution. Interestingly, irradiation of agglomerated particles produces 40 nm unagglomerated primary particles and spherical agglomerated particles approximately 1 μm in diameter. Two laser ELFFS is developed as another means to measure particles and study laser particle interactions. Two laser pulses, separated in time, irradiate the same probe volume in a jet of particles flowing into an open environment. (Abstract shortened by UMI.). |
