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Dr. Ram Hashmonay ARCADIS 4915 Prospectus Dr., Suite F Durham, NC 27713

Extinction Spectroscopy for Characterization of Particulate Matter Size and Concentration in Fugitive Plumes. Dr. Ram Hashmonay ARCADIS 4915 Prospectus Dr., Suite F Durham, NC 27713. Method Description. OP-FTIR is an accepted method for gas measurements

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Dr. Ram Hashmonay ARCADIS 4915 Prospectus Dr., Suite F Durham, NC 27713

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  1. Extinction Spectroscopy for Characterization of Particulate Matter Size and Concentration in Fugitive Plumes Dr. Ram Hashmonay ARCADIS 4915 Prospectus Dr., Suite F Durham, NC 27713

  2. Method Description • OP-FTIR is an accepted method for gas measurements • Particulate matter (PM) presence reveals a unique baseline structure (see below)

  3. Method Description (cont.) • Baseline structure can be predicted for a given size distribution and optical constants using Mie theory • We developed an inversion algorithm to retrieve the aerosol size distribution from extinction (scattering+absorption) measurements • Optical properties (constants) of specific PM may be determined using a bench-top FTIR spectrometer

  4. Mie Theory Size Parameter a d - particle diameter l - wavelength

  5. Mie Theory (cont.) Complex Refractive Index m(l) = n(l)-ik(l) n – scattering term (refraction and reflection) k – absorption term

  6. Mie Theory (cont.) Extinction Efficiency: • Extinction efficiency of water in different part of the FTIR spectrum

  7. Extinction as Function of Wavelength • sei - extinction for the ithwavelength • Qeij- dimensionless extinction efficiencies • Nj- number density for the jth aerosol size • dj- is the aerosol jth size class (diameter)

  8. Shower Experiment • OP-FTIR beam through water condensation aerosol • Size distribution confirmed by aerosol probe • Known optical constants (see below)

  9. Shower Experiment Results

  10. Predicted Smoke Extinction Spectrum

  11. Smoke PM Extinction

  12. Water Condensation Aerosol

  13. 2.5 mm Mean Size; 2 mm SD Gaussian Fit

  14. Sahara Dust Optical Constant

  15. Louisville Landfill Set-Up Landfill Dirt Road OP-FTIR Beam

  16. Diesel PM

  17. Predicted Diesel Spectrum

  18. Diesel Extinction Spectrum 2.3 mm 3.9 mm 9 mm

  19. Path-Integrated Lidar

  20. Enhanced Range Lidar

  21. Conclusions • The first open-path optical technique to obtain real-time fugitive dust measurement and sizing • Measurement of liquid aerosol like water or pesticide drift • OP-FTIR can be used in field to gather multiple gases and PM emission data simultaneously • Extending the spectral range to the UV/VIS range will allow sizing of submicron PM

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