Metal Mesh Enables Dust Scrutiny

Trapping individual dust particles in the holes of a metal mesh provides a new way to study their physical and chemical properties (J. Phys. Chem. Lett., DOI: 10.1021/jz300057z). Understanding the interplay of chemical identity, size, shape, and crystallinity of airborne particles is of particular interest in health, because such particles cause respiratory and cardiovascular disease, as well as in environmental research, because they affect weather and climate. A group led by James V. Coe at Ohio State University used a nickel screen to trap individual dust particles in 5-µm-wide square holes. When irradiated, the conducting electrons of the metal mesh develop surface waves, or surface plasmon polaritons, which enable collection of the particle’s infrared spectrum to determine its chemical composition. The same particle’s size, shape, and crystallinity can be determined by scanning electron microscopy. Studying laboratory dust, Coe and colleagues found that the dust contains variable amounts of carbonate minerals, clays, sulfates, nitrates, and organic matter (J. Phys. Chem. C, DOI: 10.1021/jp205383h). The researchers now plan to create a library of spectra of pure, single-component particles to enable study of other dusts.