Atmospheric Chemistry and Physics www.atmos-chem-phys.net 1680-7316 1680-7324 6 10 2006 10.5194/acp-6-2981-2006 http://www.atmos-chem-phys.net/6/2981/2006/ http://www.atmos-chem-phys.net/6/2981/2006/acp-6-2981-2006.html http://www.atmos-chem-phys.net/6/2981/2006/acp-6-2981-2006.pdf 2981 2990 2006-07-18 Strong spectral dependence of light absorption by organic carbon particles formed by propane combustion M. Schnaiter martin.schnaiter@imk.fzk.de M. Gimmler I. Llamas C. Linke C. Jäger H. Mutschke Institute of Meteorology and Climate Research, Forschungszentrum Karlsruhe, Germany Astrophysical Institute and University Observatory, University of Jena, Germany We have measured the extinction and absorption cross sections of carbon particles emitted by a propane diffusion flame both in an aerosol chamber and on size-segregated samples deposited on optical windows. The absorption cross section, the single scattering albedo, and the Ångström exponent show drastic dependencies both on the C/O ratio and on the particle size. This is interpretated as being due to the appearance of nucleation modes of smaller organic particles at higher C/O ratios, which were detected by SMPS measurements and partially by TEM analysis. The spectral range of the validity of the absorption power-law (Ångström exponent) model is investigated by vacuum ultraviolet extinction measurements. These measurements give also indications for a preferentially aromatic nature of the OC component of the flame products. Apicella, B., Alfe, M., Barbella, R., Tregrossi, A., and Ciajolo, A.: Aromatic structures of carbonaceous materials and soot inferred by spectroscopic analysis, Carbon, 42, 1583–1589, 2004. Bond, T C.: Spectral dependence of visible light absorption by carbonaceous particles emitted from coal combustion, Geophys. Res. Lett., 28, 4075–4078, 2001. Bond, T C. and Bergstrom, R.: Light absorption by carbonaceous particles: an investigative review, Aerosol Sci. Technol., 39, 1–41, 2006. Bond, T C., Anderson, T L., and Campbell, D.: Calibration and intercomparison of filter-based measurements of visible light absorption by aerosols, Aerosol Sci. Technol., 30, 582–600, 1999. Bond, T C., Streets, D G., Yarber, K F., Nelson, S M., Woo, J H., and Klimont, Z.: A technology-based global inventory of black and organic carbon emissions from combustion, J. Geophys. Res.-Atmos., 109, D14203, doi:10.1029/2003JD003697, 2004. Dobbins, R A., Fletcher, R A., and Chang, H C.: The evolution of soot precursor particles in a diffusion flame, Combust Flame, 115, 285–298, 1998. Fletcher, R A., Dobbins, R A., and Chang, H C.: Mass spectrometry of particles formed in a deuterated ethene diffusion flame, Anal. Chem., 70, 2745–2749, 1998. Homann, K H.: Fullerenes and soot formation – New pathways to large particles in flames, Angew. Chem. Int. Edit., 37, 2435–2451, 1998. Kirchstetter, T W., Novakov, T., and Hobbs, P V.: Evidence that the spectral dependence of light absorption by aerosols is affected by organic carbon, J. Geophys. Res.-Atmos., 109, D21208, doi:10.1029/2004JD04999, 2004. Naumann, K.-H.: COSIMA – a computer program simulating the dynamics of fractal aerosols, J. Aerosol Sci., 34, 1371–1397, 2003. Robertson, J.: Diamond-like amorphous carbon, Mat. Sci. Eng. R., 37, 129–281, 2002. Schnaiter, M., Horvath, H., Möhler, O., Naumann, K H., Saathoff, H., and Schöck, O W.: UV-VIS-NIR spectral optical properties of soot and soot-containing aerosols, J. Aerosol Sci., 34, 1421–1444, 2003. Schnaiter, M., Schmid, O., Petzold, A., Fritzsche, L., Klein, K F., Andreae, M O., Helas, G., Thielmann, A., Gimmler, M., Möhler, O M., Linke, C., and Schurath, U.: Measurement of wavelength-resolved light absorption by aerosols utilizing a UV-VIS extinction cell, Aerosol Sci. Technol., 39, 249–260, 2005. Slowik, J., Stainken, K., Davidovits, P., Williams, L., Jayne, J., Kolb, C., Worsnop, D., Rudich, Y., DeCarlo, P., and Jimenez, J.: Particle Morphology and Density Characterization by Combined Mobility and Aerodynamic Diameter Measurements. Part 2: Application to Combustion-Generated Soot Aerosols as a Function of Fuel Equivalence Ratio, Aerosol Sci. Technol., 38, 1206–1222, 2004. Ulrich, E., Beckmann, C., and Isra\"el, G.: The Characterization of Carbon Species in Particulate Matter by Successive Thermal-Desorption, J. Aerosol Sci., 21, S609–S612, 1990. Vander~Wal, R L.: Soot precursor carbonization: Visualization using LIF and LII and comparison using bright and dark field TEM, Combust Flame, 112, 607–616, 1998. VDI: Measurement of soot (Ambient Air) – Thermographical determination of elemental carbon after thermal desorption of organic carbon, VDI 2465/2, in VDI/DIN manual Air Pollution Prevention Volume 4: Analysis and Measurement Methods, Beuth, Berlin, Germany, 1999. Weingartner, E., Saathoff, H., Schnaiter, M., Streit, N., Bitnar, B., and Baltensperger, U.: Absorption of light by soot particles: determination of the absorption coefficient by means of aethalometers, J. Aerosol Sci., 34, 1445–1463, 2003.