作者:Wu, Y (Wu, Yu)[ 1 ] ; Cheng, TH (Cheng, Tianhai)[ 1 ] ; Zheng, LJ (Zheng, Lijuan)[ 1 ] ; Chen, H (Chen, Hao)[ 1 ]

AEROSOL SCIENCE AND TECHNOLOGY

卷: 49  期: 10  页: 941-949

DOI: 10.1080/02786826.2015.1083938

出版年: 2015

摘要

The diameters of soot monomers may not be constant in the single fractal aggregated soot particle. The optical properties of light absorbing soot particles aggregated with poly-disperse monomers were studied using the superposition T-matrix method. Soot aggregates were generated with different lognormal probability distribution functions (PDF) of soot monomer diameter, according to the same soot volumes and monomer numbers. The single scattering properties of soot particles were calculated at a wavelength of 550 nm, assuming a soot refractive index of 1.95 + 0.79i and a mass density of 1.8 g/cm(3). The random-orientation averaging results indicated that the optical properties of soot aggregates were fairly varied for the different distributions of the monomer diameters. In these simulations, the extinction and absorption of soot aggregates were slightly (<10%) affected by the monomer poly-dispersity. The simulated mass absorption cross-sections (MAC) of fresh dry soot particles aggregated with poly-disperse monomers reached up to 6.62 +/- 0.07 m(2)/g, which was closer to the measurement (7.5 +/- 1.2 m(2)/g) than the assumption of volume-equivalent mono-disperse monomer (6.36 +/- 0.06 m(2)/g). Moreover, the optical properties of soot coated with an organic shell were calculated, and the optical results showed that the absorption cross-sections of the internally mixed soot particles were also slightly (< 8%) influenced by the monomer poly-dispersity. We found that the effect of the monomer poly-dispersity on the light scattering and the single scattering albedo may be considerably large (up to (similar to)50% in extreme cases) for fresh dry soot aggregates. This effect on light scattering should be taken into account for those aggregates composed of monomers with widely distributed diameters.

通讯作者地址: Cheng, TH (通讯作者)

Chinese Acad Sci, State Key Lab Remote Sensing Sci, Inst Remote Sensing & Digital Earth, Datun Rd 20, Beijing 100101, Peoples R China.

地址:

[ 1 ] Chinese Acad Sci, State Key Lab Remote Sensing Sci, Inst Remote Sensing & Digital Earth, Beijing 100101, Peoples R China