Scatter-Free IR Absorption Spectra of Individual, 3–5 μm, Airborne Dust Particles Using Plasmonic Metal Microarrays: A Library of 63 Spectra

While the concentration of airborne particulate matter is well-known to be correlated with people’s health, a chemical evaluation must also be important. Noting that airborne dust particles in the 3–5 μm size regime are among the largest that get into people’s lungs, such particles were collected by pumping air through plasmonic metal films with a 12.6 μm square lattice of 5 μm square holes. Capture of a dust particle in a metallic hole enables the recording of “scatter-free” infrared absorption spectra whose peaks reveal the infrared active components. The study of the spectra of individual particles allows minority components to be characterized in a way that is quite incisive which is difficult with bulk samples. A library of 63 spectra of individual particles captured from our laboratory air is presented along with a preliminary analysis of the contributing components.