摘要：Light extinction by atmospheric particles is strongly dependent on the size, chemical
composition, and water content of the aerosol. Since light extinction by particles
directly impacts climate and visibility, measurements of the extinction at various
relative humidities (RHs) are needed. In this work, the optical growth factors,
fRHext (80%RH, Dry) have been measured using cavity ring-down aerosol extinction spectroscopy
at 532 nm for particles of varying organic/sulfate compositions. Specifically, slightly soluble,
multifunctional aromatic compounds resulting from biomass burning have been
investigated. In general, the organic compounds studied exhibit much smaller optical
growth than inorganic compounds such as ammonium sulfate. Also, a linear relationship
between mass fraction organic and optical growth has been observed for most organic
compounds studied, in agreement with previous studies of more water-soluble organics. The
role of particle density for mixtures that do not follow a linear relationship is also explored.
