Mid-infrared complex refractive indices for oleic acid and optical properties of model oleic acid/water aerosols.

Frequency-dependent, complex refractive indices for oleic acid in the mid-infrared have been retrieved from aerosol extinction spectroscopy from 750 to 5000 cm(-1). The major absorption bands can be attributed to the relevant vibrational modes of the acid, including those that originate with the hydrogen bond induced dimerization through the carboxylic group. The newly reported indices for oleic acid are used to investigate the optical properties of model core-shell aerosols formed by coating a water droplet with a layer of oleic acid.