Photophoresis of Irradiated Spheres: Evaluation of the Complex Index of Refraction

Wayne M. Greene, R. Erik Spjut, John P. Longwell, Adel F. Sarofim, Ezra Bar-Ziv

Research output: Contribution to journalArticlepeer-review

24 Scopus citations


The photophoretic force on micron-sized particles within the continuum regime has been evaluated for a range of size parameters and complex indices of refraction. A dimensionless quantity, the asymmetry factor divided by the absorption efficiency, J/Qabs, which can be obtained both experimentally and theoretically, is shown to provide a useful measure for determining the complex refractive index. For large size parameters, J/Qabs provides a measure of the extinction coefficient, k; it is insensitive to the real part of the refractive index, n, and depends weakly on the size parameter α. For small size parameters, J/Qabs depends strongly on α, n, and k. n and k can be obtained by measuring J/Qabs as a function of a.

Original languageEnglish
Pages (from-to)361-365
Number of pages5
Issue number3
StatePublished - 1 Jan 1985
Externally publishedYes

ASJC Scopus subject areas

  • General Materials Science
  • Condensed Matter Physics
  • Surfaces and Interfaces
  • Spectroscopy
  • Electrochemistry


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