Crystal Clear? Microspectroscopic Imaging and Physicochemical Characterization of Indoor Depositions on Window Glass

Deposition and surface-mediated reactions of adsorbed species can play a role in the level of exposure of occupants to indoor pollutants, which include gases and particles. Detailed molecular-level descriptions of these processes occurring on indoor surfaces are difficult to obtain because of the ever-increasing types of surfaces and their proximity to a variety of different indoor emission sources. The results of an investigation of interactions of glass surfaces in unique indoor environments are described here. Window glass, a ubiquitous indoor surface, was placed vertically in six different locations to assess differences in particle and coating depositions. Atomic force microscopy photothermal infrared (AFM-PTIR) spectroscopic analysis of these glass surfaces reveals differences in morphology and chemical composition, which reflects the diversity of surface processes found in local environments indoors. Overall, this detailed micro spectroscopic imaging method shows deposition of particles and the formation of organic thin films that increase the surface area and surface roughness of the glass surface. PTIR spectroscopy demonstrates that depositions can be linked to primary emitters intrinsic to each of the different local environments.