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| Optical scatter imaging: Detection limits | Parent topic |
Fig. 1. An image, obtained with a total internal reflection microscope, of individual diamond nanoparticles spun-coated onto a glass surface and illuminated by a Gaussian laser beam at 532 nm via total internal reflection to reduce the background (left panel), and a horizontal irradiance profile (right panel) across several bright spots just above the center of the image. The height of an irradiance peak in the right panel indicates the intensity of light scattered by a particle, proportional to a product of the particle area and scattering efficiency, while the width of a peak indicates the size of the particle image. Note an invariance of the peak widths and a dramatic difference between the peaks heights corresponding to particles with only slightly different diameters, D = 62 and 53 nm, whose ratio, ~2.8 (as estimated from the graph), roughly agrees with a ratio of (62/53)^6 = ~2.9 implied by the Rayleigh law: ~D6 (the Rayleigh law of scattering for D << λ, Eq. 3 in Mie theory: Small-particle limit equations) expressed for the particle diameter, D, with λ being the wavelength of light.
| CITATION: Zvyagin A. V., Plakhotnik T. 2006. Optical scatter imaging: Detection limits (www.tpdsci.com/Tpc/OSIDetLim.php). In: Top. Part. Disp. Sci. (www.tpdsci.com). |
HISTORY: Published: 24-Nov-2006 Modified: 15-Jan-2007 Peer-reviewed: PENDING |
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