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Proceedings Paper

Low Angle X-Ray Scattering Of Chloroplast With CK a-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 1-2 μm by using CKα-radiation with a wavelength of 44.7 Å. For particles of about 1 μm in diameter, the central scattering was not observed accurately with characteristic X-rays such as CuKα. The size, shape and hydration of chloroplast have been measured by using low angle soft X-ray scattering with CKα-radiation, 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 μm, 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 μm3. Absolute measurements were performed directly, without weakening the primary beam, permitting the calculation 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 pm. The central scattering for the chloroplast with a diameter of 6.0 μm was observed with-in 20' of the scattering angle with CKα-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 μm 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 physico-chemical changes of whole cells and organelles with respect to aging, surface, and electrostatic interactions.

Paper Details

Date Published: 24 March 1982
PDF: 12 pages
Proc. SPIE 0316, High Resolution Soft X-Ray Optics, (24 March 1982); doi: 10.1117/12.933130
Show Author Affiliations
Hasko H. Paradies, Freie Universitat Berlin (Germany)

Published in SPIE Proceedings Vol. 0316:
High Resolution Soft X-Ray Optics
Eberhard Adolf Spiller, Editor(s)

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