Hydrogen magnetic structures

X. W. Wang, J. Zhu, S. G. Louie, and S. Fahy (1990) Magnetic structure and equation of state of bcc solid hydrogen A variational quantum Monte Carlo study. Phys. Rev. Lett. 65, p. 2414... 

Yvon, K. and Fisher, R, Crystal structure and magnetic structures of ternary metal hydride a comprehensive review, in Hydrogen in Intermetallic Compounds I Electronic, Thermodynamic, and Crystallographic Properties, Preparation, L. Schlapbach, Editor. 1988, Springer Verlag Berlin, p. 88-138. 

Experimental support for Breit s suggestion comes not only from hydrogen hyperfine structure, but also from experiments in which atomic magnetic moments are compared directly through their precessional frequencies in the same field. Kusch and Foley [78] compared the moments of gallium in the... 

Neutrons, generated in a nuclear reactor, are useful for complementing X-ray diffraction information. They interact with the atomic nuclei, and with the magnetic moments of unpaired electrons if they are present in a structure. Hydrogen atoms, which are difficult to locate using X-rays (the contain one electron, if at all, near the proton), give a far better contrast in neutron diffraction experiments. The exact positions of atomic nuclei permit X minus N structure determinations, so that the location of valence electrons can be made observable. Furthermore, the magnetic structure of a material can be determined. 

The incompletely filled 4f-shell confers a magnetic moment to the lanthanide ions and it is the Ruderman-Kittel-Kasuya-Yosida (RKKY) mechanism via polarization of the conduction electrons which is responsible for the occurrence of long-range ordered magnetic structures in the lanthanide metals. Details can be foimd in numerous reviews, among others in vol. 1, chs. 3, 6 and 7 (1978) of this Handbook series and a recent one by Jensen and Mackintosh (1991). The addition of hydrogen, both in solution or resulting in hydride formation, leads to a decrease of the conduction electron density e (cf. sect. 5)... 

Ketimines and aldimines proved to be good substrates [73]. Based on the structure modification, nuclear magnetic resonance (NMR) study, kinetic study, and computational study, they proposed a double hydrogen bond structure between the acidic N-H protons and the imine lone pair to activate the electrophile toward the attack by the cyanide ion (Figure 2.15) [74]. The catalyst system is applicable to the Mannich-type reaction of N-Boc-aldimine with ketene silyl acetals to give corresponding P-amino esters in 86-98% ee (Scheme 2.25) [75]. Hydrophospho-nylation of aldimines with bis(2-nitrobenzyl)phosphite by means of (4d) furnished a-amino phosphonates in good enantioselectivity (Scheme 2.26) [76]. 

One has seen that the number of individual components in a hydrocarbon cut increases rapidly with its boiling point. It is thereby out of the question to resolve such a cut to its individual components instead of the analysis by family given by mass spectrometry, one may prefer a distribution by type of carbon. This can be done by infrared absorption spectrometry which also has other applications in the petroleum industry. Another distribution is possible which describes a cut in tei ns of a set of structural patterns using nuclear magnetic resonance of hydrogen (or carbon) this can thus describe the average molecule in the fraction under study. 

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