Diffraction by gases

V. P. Spiridonov, G. I. Mamaeva, Study of the Zirconium Borohydride Molecule by Electron Diffraction by Gases. Zh. Strukt. Khim. 1969, 10, 132-135. 

E.A.V. Ebsworth, D.W.H. Rankin and S. Cradock (1991) Structural Methods in Inorganic Chemistry, 2nd edn, CRC Press, Boca Raton, FL - A chapter on diffraction methods includes electron diffraction by gases and liquids. 

Planje MC, Toneman LH, Dallinga G (1965) Electron diffraction by gases - molecular structure of monochlorodimethyl ether. Rec Trav Chim 84 232-240... 

Sutton LE (1940) Electron diffraction by gases and vapours and electric dipole moments. Ann Rep Chem Soc 37 36-80... 

L. S. Bartell, Electron Diffraction by Gases , in Physical Methods of Chemistry , ed. A. Weissberger and B. W. Rossiter, Wiley-Interscience, New York, 1972, Vol. 1, Part 3D, Chapter 2. 

Bartell, L.S. (I972) Electron Diffraction by Gases. Physical Methods in Organic ChemistiTy (ed Weissberger, A. and Eossiter, Interscience, New York. 

Hukins DWL. X-Ray Diffraction by Disordered and Ordered Systems Covering X-Ray Diffraction by Gases, Liquids, and Solids and Indicating How the Theory of Diffraction by these Different States of Matter Is Related and How It Can be Used to Solve Structural Problems. Oxford Pergamon Press 1981. 

A subject emphasized in this article concerns the role of non-negativity in structural research in terms of its immediate applications, its special mathematical features and the use of additional probabilistic insights. The experimental techniques considered are electron diffraction by gases and X-ray diffraction by crystals. 

There is a rough parallel here with the method for making point atoms in electron diffraction by gases. Structure factors representing point atoms are the type of quantity normally used in phase-determining procedures. Instea(l of equation (21), we have... 

In this historical outline of some of the main contributions of mathematics to structural research in the areas of electron diffraction by gases and X-ray diffraction by crystals, it has been seen that these areas have benefited considerably by the application of mathematics. The same is true of other areas of structural research. It is also so that improvements in the mathematical techniques bode well for the future. In view of the broad implications of structural research to many fields of science, it may be said that structural research is an example of a discipline in which those who enjoy the application of mathematics to scientific problems can also enjoy the broad fruitfulness of the results. 

It is of interest to attempt to cast the absorption-edge spectrum in a form resembling a diffraction function. In conventional diffraction of X-rays or electrons by gases, liquids, or crystals, the general diffraction function expresses the ratio of scattered intensity, 7 to incident intensity, 7o, as a function of (sin 0)/, where d is half the scattering angle ... 

Widely used treatises and monographs on the theory and the applications of MRR-spectroscopy are available [8-//], also comprehensive reviews on all aspects of obtaining molecular structure from MRR-spectra [6,12,13], including rovib interactions [14] and the reliability of the results [15-17], Molecular structural and other data obtained from MRR spectroscopy have been compiled over the past decades [18,19], The most recent compilation is MOGADOC (short for Molecular Gas Phase Documentation ), a computerized database and retrieval system that is updated periodically and today contains more than 20,000 references, which were critically selected and evaluated by means of keywords. Included is work done by MRR-spectroscopy, electron diffraction of gases, and molecular radio astronomy the documentation refers to more than 6000 compounds. As an additional feature, MOGADOC contains explicit numerical data on the structure of approximately 2000 compounds. A detailed description can be found in ref. [20],... 

G.7 R. W. James. The Crystalline State. Vol. 11 The Optical Principles of the Diffraction of X-Rays (London George Bell, 1948). Excellent book on advanced theory of x-ray diffraction. Includes thorough treatments of diffuse scattering (due to thermal agitation, small particle size, crystal imperfections, etc.), the use of Fourier series in structure analysis, and scattering by gases, liquids, and amorphous solids. 

Introduction.— The theory necessary to carry out a fairly accurate electron-diffraction investigation was developed many years ago. The bases of the theory are to be found in papers by Rutherford, Debye, and Ehrenfest. Thus most of the theory was available when Davisson and Germer and Thomson made their famous experiments on the diffraction of electrons by crystals and so verified de Broglie s relation, and when Mark and Wierl carried out the first experiments on scattering of electrons by gases. An important contribution to the theory was also made by Fax n and Holtsmark in 1927, but their results were not applied to structure determinations by gas electron diffraction until about two decades ago. ... 

The form of fi(Q) is analogous to the expression for elastic electron diffraction by molecular gases [31. 

The previous chapter has emphasised the use of neutron scattering in conjunction with X-ray diffraction for studying the structural characteristics of different molecular liquids. In some respects, the structure is only an intermediate piece of information which helps to establish the parameters needed to describe an effective interaction potential. It is therefore of some interest to study molecular systems of low density where pair interactions predominate and the potential can be studied more directly. The first section therefore deals with neutron diffraction by molecular gases and the interpretation in terms of the structural second virial... 

Note that the form of Eq. 10.19 is analogous to that used to describe diffraction of electrons by gases (Eq. 10.4), with the variable k in one equivalent to s in the other, and so the principles of analysis are much the... 

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