Diffraction methods, review

There are several approaches to gain the required surface sensitivity with diffraction methods. We review several of these here, emphasizing the case of solid/vacuum interfaces some of these also apply to other interfaces. 

J. P. Hunt and H. L. Friedman, Prog. Inorg. Chem. 30, 359 (1983). This review is concerned with the structure of hydration complexes of ions and includes a discussion of the x-ray or neutron diffraction method for determining structure of ions in solution. 

For further discussion of the already extensive experimental information, the reader is referred to the review by Spackman (1992). Spackman concludes that, while the diffraction method may never become the routine method of choice for... 

Pb UPD on Ag(lll) and Ag(lOO) has been studied using X-ray diffraction method, electrochemical impedance spectroscopy, and in situ scanning probe microscopy [272, 286-288]. This process has been reviewed in [265, 270], see Table 2. Both structure and voltammetric behavior are dependent on the Ag(h, k, 1) plane [265, 289]. 

Studies of solvent structure are usually carried out by analyzing radial distribution functions that are obtained by X-ray or neutron diffraction methods. Monte Carlo (MC) or molecular dynamics (MD) calculations are also used. Studies of the structure of lion-aqueous and mixed solvents are not extensive yet but some of the results have been reviewed. Pure and mixed solvents included in the reviews... 

X-ray and neutron diffraction methods and EXAFS spectroscopy are very useful in getting structural information of solvated ions. These methods, combined with molecular dynamics and Monte Carlo simulations, have been used extensively to study the structures of hydrated ions in water. Detailed results can be found in the review by Ohtaki and Radnai [17]. The structural study of solvated ions in lion-aqueous solvents has not been as extensive, partly because the low solubility of electrolytes in 11011-aqueous solvents limits the use of X-ray and neutron diffraction methods that need electrolyte of -1 M. However, this situation has been improved by EXAFS (applicable at -0.1 M), at least for ions of the elements with large atomic numbers, and the amount of data on ion-coordinating atom distances and solvation numbers for ions in non-aqueous solvents are growing [15 a, 18]. For example, according to the X-ray diffraction method, the lithium ion in for-mamide (FA) has, on average, 5.4 FA molecules as nearest neighbors with an... 

Mpst of the structural information about complex gas molecules has been obtained by the electron-diffraction method. Values of interatomic distances and bond angles determined by this method before 1950 are summarized in a review article by P. W. Allen and L. E. Sutton, Acta Cryst. 3, 46 (1950). ValueB of interatomic distances and bond angles for organic molecules determined by both x-ray diffraction of crystals and electron diffraction of gas molecules are summarized in a 90-page table in G. W. Wheland s book Resonance in Organic Chemistry, John Wiley and Sons, New York, 1955, and by L. E. Sutton in Tables of Interatomic Distances and Configurations in Molecules and Ions, Chemical Society, London, 1958. (Later references to the latter book will be to Sutton Interatomic Distances.)... 

Introduction.—The compilation of the inorganic chemistry of niobium and tantalum has been revised.341 Reviews have appeared on the physicochemical properties of tantalum compounds and alloys,498,499 on the extraction, properties, and uses of niobium and tantalum,500 and on the structures of their compounds determined by diffraction methods.339 The half-life of 182Ta has been determined as 114.74 + 0.08 days.501... 

K. Kuchitsu, in MTP International Review of Science, Physical Chemistry Series One , Vol. 2 Molecular Structure and Properties , cd. G. Allen, Butterworths, London, 1973. A. G. Robiette, in Molecular Structure by Diffraction Methods , ed. G. A. Sim and L. E. Sutton (Specialist Periodical Reports), The Chemical Society, London, 1973. Vol. I, p. 160. 

The methods of synthesis, the spectral and photochromic properties in solution, in polymer film and in vacuum-deposited thin films, and the structural determinations by X-ray diffraction are reviewed as is the electrochemical behavior of this family of switchable materials. 

Elloway HF, Isaac DH, Atkins EDT (1980) Review of the structures of Klebsiella polysaccharides by X-ray diffraction. Chap. 27. In French AD, Gardner KH (eds) Fiber diffraction methods. Am Chem Soc Symp Ser 141 429-458... 

METHODS OF OBTAINING atomically-clean surfaces of solids are listed with comments on their advantages and limitations. The method of argon-ion bombardment is reviewed with a discussion of the operating conditions and precautions necessary for successful results. The low-energy electron-diffraction method is used to determine the condition of the surface. Experimental results indicate that the relative positions of the atoms in the clean (100) surface planes of germanium and silicon are not the same as those of similar planes in the bulk crystals. 

Recent reviews have surveyed X-ray and electron diffraction structures of organomagnesium compounds (see Diffraction Methods in Inorganic Chemistry), literature citations for both metals are also included in other reviews." ... 

To date, the stractures of more than four hundred organomercury compounds have been determined by X-ray diffraction methods. Detailed reviews by Warden, Holloway, and Melknik, and Casas, have already been published covering the relevant literature up to the end of 1997. Consequently, only a representative set of recent examples will be discussed in this section. 

The primary goal of this chapter is to review comprehensively the x-ray diffraction literature concerned with normal, diseased, and penetration-enhancer-treated skin. Because diffraction methods have not been widely utilized in SC structural studies until rather recently, we begin the chapter with a review of the basic principles of diffraction not only as an aid to the reader but also to encourage others to consider the possibility of using x-ray diffraction as means of studying the stratum comeum and its lipids. 

Predominant among the nonspectroscopic instrumental methods is X-ray diffraction. This technique has been known for many years for example, Brill used it to work out the structure of Fe2(CO)9 in 1927 (32). However, important and extensive application of this technique to organometallic chemistry came only when computer technology had been sufficiently advanced to speed up the computations involved. X-Ray diffraction is reviewed by Baenziger (10). Electron and neutron diffraction have also been used. Tsutsui has covered these various methods in a two-volume series (267). 

X-ray analyses have also proved useful in unraveling other complex structural problems in this field, and we shall review some work done on ascorbates by diffraction methods. 

Detailed treatments of chemical analysis by x-ray diffraction are given by Klug and Alexander [G.39] and Zwell and Danko [14.1]. Nenadic and Grable [14.24] have reviewed diffraction methods of determining quartz, asbestos, and talc in industrial dusts all of these minerals can cause lung disease. 

The goal of this article is to present a review of die methods and techniques used to determine gas phase molecular structures from higfr resolution spectroscopic data. The review covers the period from about 1980 to 1998 with the emphasis on the structures of fairly rigid molecules. The particular problems of determining structures of floppy molecules wife low-frequency large-amplitude internal motions or of Van der Waals complexes are not addressed. Likewise, fee determination of structures by a combined analysis of spectroscopic and diffraction data is not a topic of this review. The other principal technique to obtain structures of molecules in the gas phase, electron diffraction, is reviewed in another article in this volume [1]. 

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