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Optical Engineering

Low Angle X-Ray Scattering Of Chloroplast With CKa Radiation
Author(s): Hasko H. Paradies
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Paper Abstract

The operational range of low angle x-ray scattering was extended to particles and structures of about 1 to 2µm by using CKa radiation with a wavelength of 44.7 A . For particles of about 1µm in diameter, the central scattering was not observed accurately with characteristic x rays such as CuKa. The size, shape, and hydration of chloroplasts have been measured by using low angle soft x-ray scattering with CKa radia-tion, emitted from a high power x-ray tube and from synchrotron radiation. Chloroplasts were found to have a radius of gyration of 2.15 ± 0.5 um, corresponding to a particle diameter of 5.8 ± 0.2 µm. The volume was calculated from Porod's invariant and was found to be 41.0 ± 12.0 ttm3. Absolute measurements were performed directly, without weakening the primary beam, permitting the calculations of the mass of a chloroplast. The mass of the chloroplast was found to be 40.0 ± 0.07 pg, containing 0.45 pg H20/pg chloroplast. The maximum enlargement of the chloroplast particle was determined from the pair distribution function and was found to be 5.8 ± 0.2 Am. The central scattering for the chloroplast with a diameter of 6.0 um was observed within 20' of the scattering angle with CKa radiation. The origin of the difference from the nominal value in the Guinier region can be ascribed to the effect of interparticle interference when changing the density of the solvent to 10% glycerol. It should be pointed out that the use of this radiation and a synchrotron source enables us to obtain scattering of particles of Am size, almost free from the influence of the direct beam and parasitic scattering. Furthermore, by recording the intensity autocorrelation function, from which the weight average and number averaged radii of gyration, size, and size distribution can be obtained, we are enabled to study the relative dispersion from dilute particle dispersion within 0.01 arcsec and the physicochemical changes of whole cells and organelles with respect to aging, surface, and electr

Paper Details

Date Published: 1 October 1982
PDF: 7 pages
Opt. Eng. 21(5) 215894 doi: 10.1117/12.7973000
Published in: Optical Engineering Volume 21, Issue 5
Show Author Affiliations
Hasko H. Paradies, Freie Universitat Berlin (Germany)

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