Electron - affinity diffraction

All these calculations were performed for the experimental bond distances of 1.458(6) A and 1.401(10) A as determined by electron diffraction [169]. The use of slightly different bond distances as in our earlier calculations [130] gave only minor changes in the eigenvalues. The best agreement with the experimentally determined first ionization potential (7.54 0.04 eV) [170] and electron affinity (2.70 eV) [171] is obtained with the Hedin-Lundqvist exchange-correlation potential and the minimal basis set as defined above. 

The basic pseudohalide unit is a linear triatomic group which exists as an anion in polar and semi-polar crystals. Inter-group differences in ionicity among the solids are a function of the electron affinity of the anions which increase in the order NCS intra-group variations depend to a large degree on the ionization potentials of the metal ions. The structural parameters which will be considered below together with a discussion of phase transformations have been determined by diffraction and vibrational spectroscopic methods. Structural information on some of these materials is available only from infrared spectroscopic data. Detailed diffraction measurements are therefore needed to substantiate these observations and to determine the metric parameters. 

Lindsay Helmholz was born in Chicago on November 11, 1909. From 1926 until 1928 he attended Cornell University and in 1933 received his Ph.D. degree from John Hopkins University, where he was an early student of Joseph E. Mayer. He was one of the few Mayer students to do experimental work and he worked on the Born-(Mayer)-Haber cycle to determine the electron affinities of F. Helmholz came to the California Institute of Technology first as a National Research Fellow (1934-1936) then as an Instructor in Chemistry (1936-1941). At the Institute Helmholz worked with Linus Pauling and became a crystallogra-pher. In 1941 he moved to Dartmouth College as an Assistant Professor and set up his own X-ray diffraction apparatus. 

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