Abstract

Methods for determining the size and refractive index of single, homogeneous, micrometer-sized aerosol particles using Mie resonance spectroscopy are studied using measurements from optically trapped particles and light-scattering calculations based on Mie theory. We consider both single-particle broadband light scattering and cavity-enhanced Raman scattering (CERS) and demonstrate that, when resonances observed in either type of spectroscopy are fitted using Mie theory, the accuracy of the best fits are similar. However, broadband measurements can yield more resonances than CERS, thus reducing the uncertainty in the retrieved parameters of best fit and increasing the range of particles that can be characterized. Resonance fitting methods are also compared to methods that fit the entire Mie scattering spectrum. Through calculations, it is shown that measured scattering spectra are sensitive to small changes in how light is collected, while Mie resonance positions are much less sensitive. This means that additional parameters are required to accurately fit entire light-scattering spectra using Mie theory, but these parameters are not needed to accurately determine Mie resonance positions.

© 2018 Optical Society of America

Determining the size and refractive index of microspheres using the mode assignments from Mie resonances

Thomas C. Preston and Jonathan P. Reid
J. Opt. Soc. Am. A 32(11) 2210-2217 (2015)

Accurate and efficient determination of the radius, refractive index, and dispersion of weakly absorbing spherical particle using whispering gallery modes

Thomas C. Preston and Jonathan P. Reid
J. Opt. Soc. Am. B 30(8) 2113-2122 (2013)

Determination of the Complex Index of Refraction of Spherical Aerosol Particles

R. Eiden
Appl. Opt. 10(4) 749-754 (1971)

Extinction spectra of suspensions of microspheres: determination of the spectral refractive index and particle size distribution with nanometer accuracy

Jonas Gienger, Markus Bär, and Jörg Neukammer
Appl. Opt. 57(2) 344-355 (2018)

Influence of Refractive Index on the Accuracy of Size Determination of Aerosol Particles with Light-Scattering Aerosol Counters

H. Quenzel
Appl. Opt. 8(1) 165-169 (1969)