Characterizing the size and absorption of single nonspherical aerosol particles from angularly-resolved elastic light scattering

• Published in: Journal of quantitative spectroscopy & radiative transfer 2019-02, Vol.224, p.439-444
• Main Authors: Walters, Sequoyah, Zallie, Jason, Seymour, Gabriel, Pan, Yong-Le, Videen, Gorden, Aptowicz, Kevin B.
• Format: Article
• Language: English
• Subjects: Absorption; Aerosol; Elastic light scattering; Single particle
• ISSN: 0022-4073; 1879-1352
• DOI: 10.1016/j.jqsrt.2018.12.005

•Speckle size from two-dimensional angular optical scattering (TAOS) is strongly negatively correlated with cluster size of aerosol.•Simulations show that analysis of two-dimensional angular optical scattering (TAOS) is able to distinguish between non-absorbing, weakly-absorbing, and strongly-absorbing single aerosol particles. Measuring the absorption of a single aerosol particle is a challenging endeavor. Of the few techniques available, none are suitable for measuring the single-particle absorption of coarse-mode nonspherical aerosols. Analysis of two-dimensional angular optical scattering (TAOS) patterns provide a possible pathway to perform this measurement. Using a Multiple-Sphere T-Matrix (MSTM) code, we simulate the captured TAOS patterns with geometries similar to a previously designed instrument. By analyzing the size of the speckle and the integrated irradiance of these simulated TAOS patterns, we are able to distinguish between high-absorbing, weak-absorbing, and non-absorbing particles over the size range of 2 µm to 10 µm. In particular, the speckle present in the scattering patterns provides a means to estimate the size of the particle. Once the size of the particle is known, the integrated irradiance provides insight into the absorption of the particle.