The authors are with University of Washington, Department of Civil Engineering, Environment Engineering & Science Program, Seattle, Washington 98195. USA
Antony D. Clarke and Alan P. Waggoner, "Measurement of particle optical absorption, imaginary refractive index, mass concentration, and size at First International LAAP Workshop," Appl. Opt. 21, 398-402 (1982)
The modified integrating plate method was used in conjunction with ancillary equipment to obtain the absorption coefficient, specific absorption, and single-scattering albedo for a variety of generated aerosols. A computer driven multichannel optical particle counter also provided real-time output for particle size distributions. Size segregated sampling was done for appropriate aerosols, and inferences made on values for the complex refractive index. A new technique (paper in preparation) was also used for samples having low values of absorption, and results for these samples are included. These results are considered the most accurate and take precedence over values obtained by the original method (retained for completeness and inter-comparison purposes).
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Latter two aerosol mixes have not had above values adjusted for relative component masses, and the imaginary index of refraction should not be considered realistic for these samples.
Table II
Averaged and/or Most Representative Preferred Values for Samples Selected From Initial Data
See Table III for revised values as these values are not considered correct.
From Barry Bodhaine’s nephelometer at λ = 550 nm.
Simultaneous collection with and without cyclone. Note: Complex refractive index as it appears in the table represents a rough estimate only based on numerous assumptions including the Table I values for particle density and real refractive index.
Table III
Remeasured Values for Low Absorbers Using Alternate “Integrating Sandwich” Method—Supplement to Table II
Large mass uncertainty.
Relatively large absorption present for filter 43 was found to be due to contamination by large particles containing methylene blue, the origin of which is uncertain.
Numbers in parenthesis refer to fraction of methylene blue present by mass relative to ammonium sulfate.
Latter two aerosol mixes have not had above values adjusted for relative component masses, and the imaginary index of refraction should not be considered realistic for these samples.
Table II
Averaged and/or Most Representative Preferred Values for Samples Selected From Initial Data
See Table III for revised values as these values are not considered correct.
From Barry Bodhaine’s nephelometer at λ = 550 nm.
Simultaneous collection with and without cyclone. Note: Complex refractive index as it appears in the table represents a rough estimate only based on numerous assumptions including the Table I values for particle density and real refractive index.
Table III
Remeasured Values for Low Absorbers Using Alternate “Integrating Sandwich” Method—Supplement to Table II
Large mass uncertainty.
Relatively large absorption present for filter 43 was found to be due to contamination by large particles containing methylene blue, the origin of which is uncertain.
Numbers in parenthesis refer to fraction of methylene blue present by mass relative to ammonium sulfate.