A theoretical evaluation of the radiative properties of ammonium sulfate and caffeine aerosols at 632 nm
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- 作者：Peñ ; aloza ; Marcos ; Colbeck ; Ian
- 关键词：Ammonium Sulfate ; Caffeine ; Spherical and Cylindrical Aerosols ; Mie Scattering
- 刊名：Journal of Aerosol Science
- 出版年：1996
- 出版时间：September, 1996
- 年：1996
- 卷：27
- 期：Supplement 1
- 页码：S553-S554
- 全文大小：147 K
文摘
To evaluate theoretically the radiative properties of ammonium sulfate and caffeine aerosols at 632 nm a study of their optical properties was made under the condition of normal incidence of light, for both parallel and perpendicular plane polarisation modes. Ammonium sulfate aerosol was generated by a constant output atomiser (COA) and caffeine by a monodisperse aerosol generator (MAGE) (Laboro e Ambiente. Bologna). These samples, obtained with a low level of relative humidity (below 20 % ), were examined with scanning electron microscopy to investigate shape and basic dimensions. The results indicated that the COA was able to generate submicron monodisperse spherical aerosol of ammonium sulfate, with an average geometric diameter of 0.228 μm and a geometric standard deviation of 1.15. For caffeine, the results indicated that the MAGE was an appropriate generator to produce circular-cylindrical monodisperse aerosol of caffeine with an average geometric width of 1.36 μm and an average length of 4.96 μm; the respectives geometric standard deviations were 1.21 and 1.44. From the data the size parameter found for each sample was 1.13 for ammonium sulfate and 6.76 for caffeine. Using this experimental information and the respective refraction indices, a Mie computer code was applied in order to calculate the extinction, scattering and absorption efficiency coefficients for each substance.