Infrared spectroscopy and modeling of co-crystalline CO2·C2H2 aerosol particles: II. The structure and shape of co-crystalline CO2·C2H2 aerosol particles

Abstract

Infrared absorption spectra of co-crystalline CO2·C2H2 aerosol particles were modeled using a combination of two methods. Density functional theory was used to model several bulk CO2·C2H2 co-crystal structures and to calculate their lattice energies and frequency-dependent dielectric tensors. This was necessary as there currently exists no crystallographic or refractive index data on co-crystalline CO2·C2H2 due to its metastability. The discrete dipole approximation was then used to calculate infrared absorption spectra of different model particles using the dielectric tensors calculated using density functional theory. Results from these simulations were compared to the experimental spectrum of co-crystalline CO2·C2H2 aerosol particles. The aerosol particles after the decomposition of the co-crystalline phase were studied in Part I.