Elusive History of m=1.57-0.56i for the Refractive Index of Soot. Brief Communication.
Elusive History of m=1.57-0.56i for the Refractive Index
of Soot. Brief Communication.
Smyth, K. C.; Shaddix, C. R.
Combustion and Flame, Vol. 107, No. 3, 314-320,
soot; refractive index; time measurement
Soot volume fractions, number densities, and particle
sizes have been extensively measured in laboratory
flames using combined extinction and scattering methods.
In order to obtain quantitative results, a value of the
complex refractive index of the soot must be chosen,
appropriate for the wavelength employed in the
experimental measurements. Recent quantitative soot
volume fraction determinations using laser-induced
incandesence also rely on a proper calibration, which is
usually based on extinction-derived soot concentrations.
Soot refractive indices have been reported for over 30
years, during which time measurement techniques have
evolved considerably. Extractive, room-temperature
compressed pellet reflectance methods have been
replaced, for example, by in situ determinations using
combined classical and dynamic light scattering.
Despite many measurements of the refractive index of
soot, m=1.57 - 0.56i is still by far the result most
often cited in the combustion community for visible
wavelengths. This value has been widely attributed to
Dalzell and Sarofim, although it is not included in
their experimental data in either the visible or near-IR