Vol. 23, issue 04, article # 2

Rakhimov R.F., Makienko E.V., Shmargunov V.P. Refractive index variations and particle size distributions of smoke aerosols produced by thermal decomposition of some wood materials. // Optika Atmosfery i Okeana. 2010. V. 23. No. 04. P. 248-258 [in Russian].
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Abstract:

Measurements of the aerosol angular scattering coefficients of a smoke mixture are carried out in the framework of the smoke experiment at five scattering angles qj = 15; 45; 110; 135; 165° and nine wavelengths in the range 440-690 nm in the big aerosol chamber of IAO SB RAS (volume 1800 m3). The duration of measurements was ~ 100 hours. The parameters of microstructure and the complex refractive index were determined from the results of spectral nephelometric measurements in three ranges of dispersity based on the improved technique for inverting the aerosol light scattering characteristics. The specific manner of formation of the microstructure of a complex multi-component disperse media, obtained by successive mixing the products of pyrolysis of different kinds of wood, is considered. The estimates of the optical constants of aerosol particles show that variations of real and imaginary parts of CRI of large particles with r > 300 nm in the composition of the successively mixed smokes are not so substantial as that of fine fraction. In particular, for the aforementioned particles n ~ 1.58-1.62, c ~0.008-0.03, i.e. they are weakly and moderately absorbing. The finest fraction of smoke particles has quite strong absorption and, depending on the kind of combustible materials, varies in the wide range n ~ 1.78-2.20, c ~ 0.1-0.8. Particles in the intermediate size range 100<r<300 nm have the real part of CRI, mainly close to n ~ 1.64, and c ~ 0.045 for large particles. The aforementioned characteristics noticeably increase for the birch and asp rind, and approach to the estimates obtained for the fine fraction, namely n ~ 1.80, c ~ 0.20.

Keywords:

complex refractive index, nephelometric measurements, smoke mixture, inverting methods, aerosol light scattering

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