Paper No. 1
Presentation Time: 8:05 AM
INTERPRETATIONS OF X-RAY SCATTERING DATA FROM NANO-PARTICLES INSIDE AND OUTSIDE THEIR PROTEIN COATS: PAST AND PROSPECTS
PARISE, John B., Geosciences, Stony Brook University, Stony Brook, NY 11794-2100, HARRINGTON, Richard, Chemistry, Stony Brook University, Stony Brook, 11794-2100 and NEDER, Reinhard, Institut für Physik der kondensierten Materie, Kristallographie und Strukturphysik Staudtstr. 3, Erlangen, D-91058, john.parise@sunysb.edu
X-ray and neutron powder diffraction patterns from nanocrystals are often mistakenly presented as broadened versions of the Bragg-dominated diffraction patterns from corresponding bulk materials. Calculations based on the Debye equation [1, 2] show clearly that not only atomic arrangements but also information about the size and the shape of nanocrystals greatly affects the total scattering. This dependence on structure, size, shape and growth axis can form the basis for regression analysis that provides more information than Rietveld and Scherrer analysis [3, 4]. Fitting data with models of grain properties works best if the atomic arrangements in the nano-particles are known and used to constrain the overall fit [3, 4]. This structure determination is most conveniently done in real space by fitting the Pair Distribution Function (PDF), the Fourier transform of the total scattering function. The PDF at low r is particularly sensitive to the core structure of the nano-crystal and less sensitive to grain-properties.
Protein cages such as ferritins and virus capsids have been used as containers to synthesize a wide variety of protein-templated inorganic nanoparticles. Removal of the protein coat produces the bare nano-particle. The analysis of data from nano-particles derived from capsids, of the loaded capsids and from inorganic routes, will provide an illustration of the scattering principles outlined above.
[1] P. Debye (1915) Ann. Phys. 46: 804
[2] A. Cervellino, C. Giannini, A. Guagliardi, (2003), J. Appl. Cryst., 36: 1148
[3] F. Niederdraenk, K. Seufert, P. Luczak, S.K. Kulkarni, Ch. Chory, R.B., Neder, Ch. Kumpf (2007) phys. stat. sol., (c), 4: 3234
[4] R.B. Neder, V.I. Korsunskiy, Ch. Chory, G. Müller, A. Hofmann, S. Dembski, Ch. Graf, E. Rühl (2007) phys.stat.sol., (c), 4: 3221
