Search Results

Fritz Haber hired Polanyi to work in the Fiber Chemistry Group of the Kaiser Wilhelm Institute in Berlin. Polanyi helped develop the rotating-crystal method of X-ray crystallography, made solid contributions to understanding the structure of cellulose, pressed forward with his work on adsorption catalysis and electrostatic dipoles, laid the foundation for transition rate theory in reaction kinetics, and investigated the bond strength of crystals; he was also forced to give up a cherished theory about quantum jumps in reaction kinetics, which taught him an important lesson about how scientists work together to distinguish real discoveries from mistaken surmises. Polanyi married Magda Kemeny on February 21, 1921, in a civil ceremony; their first child, George Michael Polanyi, was born on October 1, 1922.

This chapter recalls the early developments of X-ray crystallography and how it spread throughout the world, and the first theoretical and experimental investigations that led to the determination of crystal structures, from the simpler trial-and-error methods to the systematic use of space groups and the introduction of Fourier syntheses. The Lorentz and polarization factors and the atomic scattering factor were analysed. W. H. Bragg introduced the concept of integrated intensities, and W. L. Bragg that of absolute intensities. Expressions for the diffracted intensity by small and large perfect crystals were obtained by C. G. Darwin, who also introduced the notion of mosaic crystal to account for the observed diffracted intensities. It is shown how W. L. Bragg determined the structure of the trigonal carbonates from the simple observation of diffracted intensities by various reflecting planes. The discovery of powder diffraction by Debye and Sherrer in Germany and by Hull in the United States is recounted. The first applications of the rotating crystal method to crystal structure determinations are described. Finally, the determination of three landmark crystal structures is explained: hexamethylene tetramine, graphite, and the benzene ring.

This chapter relates the first steps of X-ray crystallography in 1913. It starts with a brief account of the flock of experiments in England and Germany, prompted by Bragg’s experiment with mica. It then tells how Wulff, Laue himself, Ewald, and Friedel interpreted Laue’s relations in terms of the reflection by a set of lattice planes. Laue admitted his early misconceptions and gave a correct interpretation of Friedrich and Knipping’s experiment. The chapter proceeds on with Terada’s and Nishikawa’s early experiments in Japan, and de Broglie’s experiments in France. In England, W. H. Bragg developed the ionization spectrometer, and W. L. Bragg made the first crystal structure determinations. Moseley determined the high-frequency spectra of the elements and established its relations with the atomic numbers. In Zürich, Debye derived the influence of thermal agitation on the intensity of diffracted intensities. In France, de Broglie introduced the rotating crystal method, and Friedel related X-ray diffraction and crystal symmetry. In the United States, the first X-ray spectrometer was built in 1914.