Electron Microscopy Imaging of Lab-generated Aerosol Particles

Amrita Chakraborty, Deepak Sapkota, Yuhui Guo, James Hu, Harris Xie, Ian Wu, Zhenpeng Qin, HUI OUYANG, University of Texas at Dallas

     Abstract Number: 698
     Working Group: Aerosol Physics

Abstract
It is important to characterize the structure and compositions of aerosol particles for aerosol transport applications, such as bioaerosols and atmospheric aerosol transport. In this study, we develop an experimental imaging approach that can pave the way to probe the microenvironmental conditions of desiccated bioaerosols with various chemical compositions. Starting with the salt solutions (KCl and NaCl), a BLAM nebulizer is used for aerosolization. Aerosol particles are dried and collected onto Silicon wafers and TEM grids, which sit onto the impaction plates in a standard 8-stage Andersen impactor. Particles with different sizes are collected at different stages for scanning (SEM) and scanning transmission electron microscopic (STEM) imaging, respectively. Further, STEM energy dispersive X-ray spectroscopy measurements are performed to reveal the elemental distribution in the bioaerosol. The results show that salts deviate from spherical structures and form crystals instead under the low relative humidity condition (RH = 30%). Elements mapping also shows a separation between Na and K when a solution of the mixture of NaCl and KCl is aerosolized together. Separation is also presented when aerosolizing salt and Bovine serum albumin (BSA) protein. Adding organics will shift the structure towards spherical shape. Our study reveals morphological insight into aerosol particles under different composition and sizes.