Measurements of Light Extinction by Single Aerosol Particles.
A Bessel beam optical trap is combined with continuous wave cavity ringdown spectroscopy to measure the extinction cross section of individual aerosol particles. Particles, ∼1 μm in size, can be captured indefinitely and processes that transform size or refractive index studied. The measured light extinction induced by the particle is shown to depend on the position of the particle in the cavity, allowing accurate measurements of the mode structure of a high finesse optical cavity without significant perturbation. The variation in extinction efficiency of a sodium chloride droplet with relative humidity is shown to agree well with predictions from Mie scattering theory.
School of Chemistry, University of Bristol, Bristol, United Kingdom BS8 1TS.
Jim S
JS
Walker
School of Chemistry, University of Bristol, Bristol, United Kingdom BS8 1TS.
Antonia E
AE
Carruthers
School of Chemistry, University of Bristol, Bristol, United Kingdom BS8 1TS.
Andrew J
AJ
Orr-Ewing
School of Chemistry, University of Bristol, Bristol, United Kingdom BS8 1TS.
Jonathan P
JP
Reid
aerosols; cavity ringdown spectroscopy; light scattering and extinction; optical manipulation