Time resolved fluorescence polarization anisotropy of carbonaceous particles produced in combustion systems

The size of nanometric carbonaceous particles produced in
various combustion systems is determined by means of time resolved
fluorescence polarization anisotropy (TRFPA). We also compare the
performances of two different experimental implementations of the
technique, which are complementary in terms of cost, simplicity and
resolution. Both methods are first employed on standard molecules to
demonstrate the reliability of the results. A study of the sizes of nanometric
particles collected at the exhaust of diesel and gasoline vehicle engine, as
well as from controlled laminar flames is presented. The high sensitivity
(0.04 nm) achieved with the use of a streak camera as detector makes the
TRFPA technique particularly suitable for characterizing nanometric
particles.