Abstract

We conducted a series of spectral extinction measurements on a variety of aerosolized chemical and biological simulants over the spectral range 3–13 μm using conventional Fourier-transform IR (FTIR) aerosol spectroscopy. Samples consist of both aerosolized particulates and atomized liquids. Materials considered include Bacillus subtilis endospores, lyophilized ovalbumin, polyethylene glycol, dimethicone (SF-96), and three common background materials: kaolin clay (hydrated aluminum silicate), Arizona road dust (primarily SiO2), and diesel soot. Aerosol size distributions and mass density were measured simultaneously with the FTIR spectra. As a result, all optical parameters presented here are mass normalized, i.e., in square meters per gram. In an effort to establish the utility of using Mie theory to predict such parameters, we conducted a series of calculations. For materials in which the complex indices of refraction are known, e.g., silicone oil (SF-96) and kaolin, measured size distributions were convolved with Mie theory and the resultant spectral extinction calculated. Where there was good agreement between measured and calculated extinction spectra, absorption, total scattering, and backscatter were also calculated.

© 2004 Optical Society of America

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References

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  1. K. P. Gurton, D. Ligon, R. Kvavilashvili, “Measured infrared spectral extinction for aerosolized Bacillus subtilis var. niger endospores from 3 to 13 μm,” Appl. Opt. 40, 4443–4448 (2001).
    [CrossRef]
  2. A. Deepak, Atmospheric Aerosols: Their Formation, Optical Properties, and Effects (Spectrum, Hampton, Va., 1982).
  3. H. Gerber, E. Hindman, Light Absorption by Aerosol Particles (Spectrum, Hampton, Va., 1982).
  4. D. W. Wieliczka, M. R. Querry, “Four techniques to measure complex refractive indices of liquids and solids at carbon dioxide laser wavelengths in the infrared spectral region,” CRDEC-CR-062 (Chemical Research, Development, and Engineering Center, Aberdeen Proving Grounds, Md., 1990).
  5. D. Ligon, J. Gillespie, P. Pellegrino, “Aerosol properties from spectral extinction and backscatter estimated by an inverse Monte Carlo method,” Appl. Opt. 39, 4402–4410 (2000).
    [CrossRef]
  6. C. Bruce, Measuring Aerosol Density using Nephelometry and Dosimetry (Center for Atmospheric Sciences, Las Cruces, N.Mex., 1987).
  7. M. R. Querry, “Optical constants of minerals and other materials from the millimeter to the ultraviolet,” CRDEC-CR88009 (Chemical Research, Development, and Engineering Center, Aberdeen Proving Grounds, Md., 1987).
  8. C. W. Bruce, K. P. Gurton, T. F. Stromberg, “Trans-spectral absorption and scattering of electromagnetic radiation by diesel soot,” Appl. Opt. 30, 1537–1546 (1991).
    [CrossRef] [PubMed]

2001 (1)

2000 (1)

1991 (1)

Bruce, C.

C. Bruce, Measuring Aerosol Density using Nephelometry and Dosimetry (Center for Atmospheric Sciences, Las Cruces, N.Mex., 1987).

Bruce, C. W.

Deepak, A.

A. Deepak, Atmospheric Aerosols: Their Formation, Optical Properties, and Effects (Spectrum, Hampton, Va., 1982).

Gerber, H.

H. Gerber, E. Hindman, Light Absorption by Aerosol Particles (Spectrum, Hampton, Va., 1982).

Gillespie, J.

Gurton, K. P.

Hindman, E.

H. Gerber, E. Hindman, Light Absorption by Aerosol Particles (Spectrum, Hampton, Va., 1982).

Kvavilashvili, R.

Ligon, D.

Pellegrino, P.

Querry, M. R.

D. W. Wieliczka, M. R. Querry, “Four techniques to measure complex refractive indices of liquids and solids at carbon dioxide laser wavelengths in the infrared spectral region,” CRDEC-CR-062 (Chemical Research, Development, and Engineering Center, Aberdeen Proving Grounds, Md., 1990).

M. R. Querry, “Optical constants of minerals and other materials from the millimeter to the ultraviolet,” CRDEC-CR88009 (Chemical Research, Development, and Engineering Center, Aberdeen Proving Grounds, Md., 1987).

Stromberg, T. F.

Wieliczka, D. W.

D. W. Wieliczka, M. R. Querry, “Four techniques to measure complex refractive indices of liquids and solids at carbon dioxide laser wavelengths in the infrared spectral region,” CRDEC-CR-062 (Chemical Research, Development, and Engineering Center, Aberdeen Proving Grounds, Md., 1990).

Appl. Opt. (3)

Other (5)

A. Deepak, Atmospheric Aerosols: Their Formation, Optical Properties, and Effects (Spectrum, Hampton, Va., 1982).

H. Gerber, E. Hindman, Light Absorption by Aerosol Particles (Spectrum, Hampton, Va., 1982).

D. W. Wieliczka, M. R. Querry, “Four techniques to measure complex refractive indices of liquids and solids at carbon dioxide laser wavelengths in the infrared spectral region,” CRDEC-CR-062 (Chemical Research, Development, and Engineering Center, Aberdeen Proving Grounds, Md., 1990).

C. Bruce, Measuring Aerosol Density using Nephelometry and Dosimetry (Center for Atmospheric Sciences, Las Cruces, N.Mex., 1987).

M. R. Querry, “Optical constants of minerals and other materials from the millimeter to the ultraviolet,” CRDEC-CR88009 (Chemical Research, Development, and Engineering Center, Aberdeen Proving Grounds, Md., 1987).

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Figures (10)

Fig. 1
Fig. 1

Measured size distribution for particulates and liquid droplets.

Fig. 2
Fig. 2

Complex indices of refraction for BG endospores.7.

Fig. 3
Fig. 3

Complex indices for liquid silicone SF-96 grade 50.7.

Fig. 4
Fig. 4

Complex indices of refraction for kaolin clay.7.

Fig. 5
Fig. 5

Measured (red curve) and calculated (thick blue curve) spectral extinction for aerosolized BG endospores. Also shown are the Mie theory predicted total scatter (thin blue curve), absorption (orange curve), and backscatter (green curve).

Fig. 6
Fig. 6

Measured (thick red curve) and calculated (thick blue curve) spectral extinction for nebulized liquid silicone SF-96 grade 50. Also shown are the Mie theory predicted total scatter (thin blue curve), absorption (orange curve), and backscatter (green curve).

Fig. 7
Fig. 7

Measured (thick red curve) and calculated (thick blue curve) spectral extinction for aerosolized kaolin clay. Also shown are the Mie theory predicted total scatter (thin blue curve), absorption (orange curve), and backscatter (green curve).

Fig. 8
Fig. 8

Measured spectral extinction for PEG 200, diesel soot,1 Arizona road dust, and ovalbumin.

Fig. 9
Fig. 9

Comparison of the measured extinction spectra for ovalbumin (lyophilized egg white) with a Mie calculation in which the indices of refraction for BG endospores were used.

Fig. 10
Fig. 10

Measured extinction for agglomerated Cab-O-Sil aerogel at various concentrations. The flat spectral extinction is synonymous with large-sized parameter particles (compared with the wavelength).

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