Mass-specific optical absorption coefficients and imaginary part of the complex refractive indices of mineral dust components measured by a multi-wavelength photoacoustic spectrometer

[摘要] Mass-specific optical absorption coefficients (MACs) and the imaginary part(κ) of the refractive indices of various mineral dust componentsincluding silicate clays (illite, kaolin and bentonite), oxides (quartz,hematite and rutile), and carbonate (limestone) were determined at thewavelengths of 1064, 532, 355 and 266 nm. The MAC values were calculatedfrom aerosol optical absorption coefficients measured by a multi-wavelengthphotoacoustic (PA) instrument, the mass concentration and the number sizedistribution of the generated aerosol samples as well as the size transferfunctions of the measuring instruments. Values ofκ were calculatedfrom the measured and particle-loss-corrected data by using a Mie-theory-based retrieval algorithm. The determined values could be used forcomparisons with calculated wavelength-dependent κ values typicallydeduced from bulk-phase measurements by using indirect measurement methods.Accordingly, the presented comparison of the measured and calculated aerosoloptical absorption spectra revealed the strong need for standardized samplepreparation and measurement methodology in case of bulk-phase measurements.

[学科分类] 几何与拓扑