Wavelength-dependent optical extinction of carbonaceous particles in atmospheric aerosols and interstellar dust

摘要

Optical extinction spectra for particles of structurally disordered carbonaceous material (carbon black, soot) are discussed in terms of the effects of size and shape and the difference between coagulated and coalesced particles. For this purpose, the orientation-averaged specific extinction for several compact and open aggregates of spherical particles is calculated and compared with the specific extinction by homogeneous particles, i.e., volume-equivalent spheres and elongated spheroids. The extinction spectra are calculated for wavelengths from 0.2 to 1000 μm by use of the optical constants for the carbonaceous materials of Jager et al. [Astron. Astrophys. 332, 291 (1998)] and Schnaiter et al. [Astrophys. J. 498, 486 (1998)]. Comparisons with the model case of particles composed of graphite and with measurements of diesel soot aerosols are made.