Determination of refractive index of rod-shaped bacteria from spectral extinction measurements

Aleksei E. Balaev; Konstanten N. Dvoretski; Valeri A. Doubrovski

doi:10.1117/12.518853

13 October 2003 Determination of refractive index of rod-shaped bacteria from spectral extinction measurements

Aleksei E. Balaev, Konstanten N. Dvoretski, Valeri A. Doubrovski

Proceedings Volume 5068, Saratov Fall Meeting 2002: Optical Technologies in Biophysics and Medicine IV; (2003) https://doi.org/10.1117/12.518853
Event: Saratov Fall Meeting 2002 Laser Physics and Photonics, Spectroscopy, and Molecular Modeling III; Coherent Optics of Ordered and Random Media III, 2002, Saratov, Russian Federation

Abstract

The T-matrix method together with the approximate theories such as the Rayleigh-Gans and anomalous diffraction approximations are used for the refractive index determination of bacterial cells from spectral extinction measurements. The water suspension of Escherichia coli K12 cells in exponential phase of growth is modeled as a system of randomly oriented homogeneous circular cylinders with identical radii and different lengths. In the case of length monodispersity the results of the approximate theories are compared with those obtained by the exact T-matrix method. Assuming the gamma distribution of bacterial lengths, the influence of the length polydispersity on the refractive index is investigated using the Rayleigh-Gans approximation. It is shown that the effect of the length polydispersity degree upon the refractive index of rod-shaped bacteria is negligible. The wavelength dependence of the refractive index of E. coli cells obtained gives the value of 1.397 at 589 nm what is in a good agreement with the result of immersion refractometry (1.395±0.005).

Citation Download Citation

Aleksei E. Balaev, Konstanten N. Dvoretski, and Valeri A. Doubrovski "Determination of refractive index of rod-shaped bacteria from spectral extinction measurements", Proc. SPIE 5068, Saratov Fall Meeting 2002: Optical Technologies in Biophysics and Medicine IV, (13 October 2003); https://doi.org/10.1117/12.518853

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