Flame, temperature measurements during electrically assisted aerosol synthesis of nanoparticles

Fourier transform infrared (FTIR) emission/transmission (E/T) spectroscopy is used to measure the temperature during TiO2 formation by titanium tetraisopropoxide (TTIP) oxidation in a premixed flat flame. In the absence of particles, FTIR is systematically compared to coherent anti-Stokes Raman scattering (CARS) in premixed flames in the presence and absence of external electric fields including line-of-sight as well as tomographic reconstructed FTIR measurements. Time resolved CARS flame temperature measurements probe the effect of electric fields on the premixed flat flame. Furthermore, FTIR is used to measure axial and radial flame temperature profiles in TiO2 particle-laden flames at various electric field strengths. Along with the visible reduction in flame height when applying the electric field, the external electric fields reduce the high temperature region of the flame and lead to a steeper temperature gradient further downstream. The maximum flame temperature, however, remains constant. The precision control of particle crystallinity and the specific surface area by external electric fields is confirmed as well as their effect on the anatase to rutile phase transformation is discussed. (C) 2002 by The Combustion Institute.