Crystal electron diffraction

Although the aminodifluorophosphine (119) is planar about the nitrogen atom in the crystal, electron diffraction shows that in the gaseous phase the molecules are slightly pyramidal, the angle between the RNR plane and the N—P bond being 32° for (119, R = Me), 35° for (119, R = The... 

Strong L, Whitesides GM (1988) Structures of self-assembled monolayer films of organosulfur compounds adsorbed on gold single crystals electron diffraction studies. Langmuir 4 546-558... 

A possible economically attractive alternative would be the production of acrylic acid in a single step process starting from the cheaper base material propane. In the nineteen nineties the Mitsubishi Chemical cooperation published a MoVTeNb-oxide, which could directly oxidise propane to acrylic acid in one step [6], Own preparations of this material yielded a highly crystalline substance. Careful analysis of single crystal electron diffraction patterns revealed that the MoVTeNb-oxide consists of two crystalline phases- a hexagonal so called K-Phase and an orthorhombic I-phase, which is the actual active catalyst phase, as could be shown by preparing the pure phases and testing them separately. 

Honjo, C., N. Kitamura, and K. Mihama (1954). A study of clay minerals by means of single crystal electron diffraction diagrams structure of tubular kaolin. 

Here Sp means by infrared or ultraviolet spectroscopy and M by microwave spectroscopy. Similar values, in general somewhat less reliable, have also been obtained for many molecules by x-ray diffraction of crystals, neutron diffraction of crystals, electron diffraction of gas molecules (ED), or analysis of vibrational frequencies. 

The agreement index from the observed single crystal electron diffraction structure factors (28 separate reflections) compared to the calculated structure factors for the Yokouchi at. model was 0.33. This is far from the values of 0.24 and 0.135 reported for the two published x-ray fiber analyses (14,15). ... 

Comparison of Some Observed (Fo) Structure Factors Derived from X-Ray Fiber Diffraction and Single Crystal Electron Diffraction on PHB. 

BRISSE and MARCHESSAULT Single Crystal Electron Diffraction... 

On present evidence, it is thus probable that the only alite polymorphs found in normal production clinkers are Mj, M, and, occasionally, T, and that those that have been described as R are really M,. However, both XRD and thermal evidence show that some alites formed in the presence of fluoride are rhombohedral (M7). XRD and optical evidence indicates that the commonest polymorph in production clinkers is almost certainly M the presence of which in such a clinker has also been demonstrated using single crystal electron diffraction (HI). 

FIG. 3 X-ray diffraction pattern of a microcrystaliine powder of Cgo- Inset (upper left) is a single-crystal electron diffraction pattern Indexed with Miller indices compatible with the X-ray pattern. The pattern is from a thin platelet such as those in Fig. 1 with the electron beam perpendicular to the flat face. 

Because incident electrons interact strongly with crystals, electron diffraction is capable of yielding detailed structural information from very small crystals... 

Practically, the position of the nucleus can be determined by measuring the vibration-rotation spectra and neutron diffraction, whereas the electron cloud can be determined by X-ray scattering (for crystals), electron diffraction (for the gaseous phase), together with electron spin resonance and nuclear magnetic resonance. 

The single-crystal electron diffraction pattern shown in Figure 6.5 was obtained by viewing the crystal along the c-axis. Also shown is the single-crystal structure of polyethylene, which is typically diamond-shaped (see below). The unit cell is viewed from the c-axis direction, perpendicular to the diamonds. 

Fig. 4.27. Powder X-ray diffraction pattern and single-crystal electron diffraction pattern inset upper left) of buckminsterfullerene. Reproduced with permission from Kratschmer W, Lamb LD, Fostiropoulos K and Huffman DR (1990) Nature 347 354...

The use of polymer single crystal electron diffraction has been very helpful, in the determination of the polymer s unit cell dimensions and to confirm the correctness of the proposed model. 

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