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Award Detail

Doing Business As Name:Kansas State University
  • Matthew J Berg
  • (785) 317-3378
Award Date:05/20/2021
Estimated Total Award Amount: $ 399,196
Funds Obligated to Date: $ 399,196
  • FY 2021=$399,196
Start Date:06/01/2021
End Date:05/31/2024
Transaction Type:Grant
Awarding Agency Code:4900
Funding Agency Code:4900
CFDA Number:47.050
Primary Program Source:040100 NSF RESEARCH & RELATED ACTIVIT
Award Title or Description:Multi-Spectral Digital Holography for Aerosol Material Characterization
Federal Award ID Number:2107715
DUNS ID:929773554
Parent DUNS ID:041146432
Program:Physical & Dynamic Meteorology
Program Officer:
  • Chungu Lu
  • (703) 292-7110

Awardee Location

Awardee Cong. District:01

Primary Place of Performance

Organization Name:Kansas State University
Cong. District:01

Abstract at Time of Award

Aerosols are small particles of solid or liquid material dispersed in a gas and they are common in everyday life. Familiar examples include the water-droplets forming clouds, the dust and combustion particles forming haze, and pollen particles emitted by plants. When in the atmosphere, aerosols affect the Earth’s energy budget by absorbing and scattering sunlight, which can lead to cooling or heating effects on the climate. The amount of light absorbed or scattered is determined by the shape, size, and composition of a particle. Consequently, it is of interest to develop methods to determine these properties of aerosol particles, whether that be to better understand their impact on the climate or as a way to study what types of particles are present in a given environment. This project develops a new way to characterize aerosols where images of free-flowing particles are obtained without the need to collect or immobilize the particles. The core of the approach involves digital holography (DH), which is functionally analogous to microscopy, except no lenses are needed and particle images are focused post-measurement in computational manner. The images obtained thus reveal the shape and size of the particles under investigation. In the conventional approach, however, the images are gray-scale in nature, and so, there is little sensitivity to the particle’s material. By extending DH to operate at three wavelengths (colors) simultaneously, this project brings color to the particle images. This presents the possibility of gaining particle-material information in a non-contact manner. Systematic studies of particles of different shapes and materials will be conducted to determine the quality of the color images. By applying a color analysis to such images, the project will test the ability to merge shape, size, and color information to differentiate between particle types. The outcome of this work could significantly advance the ability to characterize aerosols across multiple domains of scientific and applied interests. With conventional DH, gray-scale images of individual aerosol particles can be obtained in a contact-free manner. This capability has been adopted by numerous scientists and has advanced our understanding for the size and shape of particles in the atmosphere. What is missing in DH, however, is information about the particle material. By extending the principles of DH across the spectral domain, this project will bring color to images of free-flowing aerosol particles. The project applies chromaticity analysis to the images as a quantitative way to describe the colors exhibited. Because particles of different material absorb and reflect colors differently, this analysis has the potential to distinguish between categories of material. For example, mineral dust (MD) particles with radiatively absorbing components like iron oxides could be distinguished from particles with strongly scattering components like silicates. Biological particles could be distinguished from MD. The work will focus on the coarse mode aerosol (CMA), i.e., particles larger than one micrometer. Such particles are ubiquitous and include, e.g., wind-blown MD and biological particles. Not only is a particle’s size and shape revealed with DH, but the interference nature of the method allows the particle’s extinction cross section to be measured as well. The project will assemble a collection of CMA particles, characterize their material composition with X-ray diffraction and other analytical techniques, and perform chromaticity analysis on stationary particles from the collection. By aerosolizing these samples and capturing color DH images of the free-flowing particles, the study can test the ability of the analysis to associate observed particles with categories of known materials. The outcomes of the work will establish the feasibility and utility of color DH for aerosol characterization, from which future efforts could develop instruments for field studies of the atmospheric CMA at an unprecedented level of detail. This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.

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