Generation, Processing, and Transferring of CCD Camera Images in Electron Crystallography

1996 ◽  
Vol 54 ◽  
pp. 426-427
Author(s):  
Z. G. Li ◽  
L. Liang ◽  
R. L. Harlow ◽  
K.E. Lehman ◽  
N. Herron
Keyword(s):  
Electron Diffraction ◽  
Diffraction Data ◽  
Dynamic Range ◽  
Structural Information ◽  
Ccd Camera ◽  
High Dynamic Range ◽  
Electron Diffraction Data ◽  
Electron Crystallography ◽  
Camera Model ◽  
University Of New Mexico

Recently, CCD camera has been more and more used in the electron microscopy particularly for electron crystallography [1]. Use of CCD camera in this field as a recording medium possesses many significant advantages over conventional photographic films. A CCD camera has a very high dynamic range (reliable) and produces images directly in digital form which can be conveniently processed and transferred. We have initiated a program to obtain crystal structural information of plate-like materials by processing electron diffraction data from a CCD detector. As part of our program, we have developed a complete and routine procedure to convert images to diffraction data (h, k, l’s and intensities).Figure 1 is a schematic representation of the procedure. Images are initially obtained using a 1024×1024 Gatan CCD camera (model 794) which was attached to JEM-2000EX electron microscope. The collection of the images is controlled by a MAC computer which also stores the data and allows the data to be viewed. Then, the digitized electron diffraction patterns are transferred to a Sun station computer where, using Khoros software, the CCD images are processed. The Khoros system is a very complete image analysis and image processing software developed by University of New Mexico [2].

Electron Crystallography of Phthalocyanines

1999 ◽  
Vol 03 (07) ◽  
pp. 672-678 ◽  
Author(s):  
J. R. FRYER
Keyword(s):  
Electron Microscopy ◽  
High Resolution ◽  
Electron Diffraction ◽  
Diffraction Data ◽  
Structural Information ◽  
High Resolution Electron Microscopy ◽  
Electron Diffraction Data ◽  
Electron Crystallography ◽  
Resolution Electron ◽  
Copper Phthalocyanines

It is shown that it is possible to obtain structural information from small (<100 nm) phthalocyanine crystals by using crystallographic direct phasing methods applied to electron diffraction data. This technique is both quantitative and does not suffer from the difficulties associated with high-resolution electron microscopy. Structural information has been obtained from both tetra- and octa chloro-copper phthalocyanines, and the results compared with the hydrogenated and perchloro members of the series.

scholarly journals Ab initiostructure determination of nanocrystals of organic pharmaceutical compounds by electron diffraction at room temperature using a Timepix quantum area direct electron detector

2016 ◽  
Vol 72 (2) ◽  
pp. 236-242 ◽  
Author(s):  
E. van Genderen ◽  
M. T. B. Clabbers ◽  
P. P. Das ◽  
A. Stewart ◽  
I. Nederlof ◽  
...  
Keyword(s):  
Electron Diffraction ◽  
Room Temperature ◽  
Dynamic Range ◽  
Signal To Noise Ratio ◽  
Three Dimensional ◽  
Direct Methods ◽  
Liquid Nitrogen Temperature ◽  
High Dynamic Range ◽  
Electron Diffraction Data ◽  
High Signal

Until recently, structure determination by transmission electron microscopy of beam-sensitive three-dimensional nanocrystals required electron diffraction tomography data collection at liquid-nitrogen temperature, in order to reduce radiation damage. Here it is shown that the novel Timepix detector combines a high dynamic range with a very high signal-to-noise ratio and single-electron sensitivity, enablingab initiophasing of beam-sensitive organic compounds. Low-dose electron diffraction data (∼0.013 e− Å−2 s−1) were collected at room temperature with the rotation method. It was ascertained that the data were of sufficient quality for structure solution using direct methods using software developed for X-ray crystallography (XDS,SHELX) and for electron crystallography (ADT3D/PETS,SIR2014).

scholarly journals Single Crystal 3D Rotation Electron Diffraction from Nano-sized Crystals

2014 ◽  
Vol 70 (a1) ◽  
pp. C366-C366
Author(s):  
Xiaodong Zou
Keyword(s):  
Electron Diffraction ◽  
Data Collection ◽  
Data Processing ◽  
Single Crystal ◽  
Diffraction Data ◽  
Structure Determination ◽  
Reciprocal Lattice ◽  
Electron Diffraction Data ◽  
Electron Crystallography ◽  
Structure Solution

Electron crystallography is an important technique for structure analysis of nano-sized materials. Crystals too small or too complicated to be studied by X-ray diffraction can be investigated by electron crystallography. However, conventional TEM methods requires high TEM skills and strong crystallographic knowledge, which many synthetic materials scientists and chemists do not have. We recently developed the software-based Rotation Electron Diffraction (RED) method for automated collection and processing of 3D electron diffraction data. Complete single crystal 3D electron diffraction data can be collected from nano- and micron-sized crystals in less than one hour by combining electron beam tilt and goniometer tilt, which are controlled by the RED – data collection software.3 The unit cell, possible space groups and electron diffraction intensities can be obtained from the RED data using the RED data processing software. The figure below illustrates the data collection and data processing of a zeolite silicalite-1 by RED. 1427 ED frames were collected in less than 1 hour from a crystal of 800 x 400 x 200 nm in size. A 3D reciprocal lattice of silicalite-1 was reconstructed from the ED frames, from which the unit cell parameters and space group were determined (P21/n, a=20.02Å, b=20.25Å, c=13.35Å, alfa=90.130, beta=90.740, gamma=90.030. It was possible to cut the 3D reciprocal lattice perpendicular to any directions and study the reflection conditions. The reflection intensities could be extracted. The structure of the calcined silicalite-1 could be solved from the RED data by routine direct methods using SHELX-97. All 78 unique Si and O atoms could be located and refined to an accuracy better than 0.08 Å. The RED method has been applied for structure solution of a wide range of crystals and shown to be very powerful and efficient. Now a structure determination can be achieved within a few hours, from the data collection to structure solution. We will present several examples including unknown inorganic compounds, metal-organic frameworks and organic structures solved from the RED data. Different parameters that affect the RED data quality and thus the structure determination will be discussed. The methods are general and can be applied to any crystalline materials.

Quantitative Electron Diffraction for Crystal Structure Determination

2009 ◽  
Vol 1184 ◽  
Author(s):  
Peter Oleynikov ◽  
Daniel Grüner ◽  
Daliang Zhang ◽  
Junliang Sun ◽  
Xiaodong Zou ◽  
...  
Keyword(s):  
Electron Diffraction ◽  
Data Quality ◽  
Diffraction Data ◽  
Ccd Camera ◽  
Electron Diffraction Data ◽  
X Ray Diffraction ◽  
Quantitative Investigation ◽  
Critical Question ◽  
Selected Area Electron Diffraction

AbstractWe present a quantitative investigation of data quality using electron precession, compared to standard selected-area electron diffraction (SAED). Data can be collected on a CCD camera and automatically extracted by computer. The critical question of data quality is addressed – can electron diffraction data compete with X-ray diffraction data in terms of resolution, completeness and quality of intensities?

scholarly journals A Method to Characterize and Correct Elliptical Distortion in Electron Diffraction Patterns

2008 ◽  
Vol 16 (3) ◽  
pp. 36-41
Author(s):  
Vincent D.-H. Hou ◽  
Du Li
Keyword(s):  
Image Processing ◽  
Electron Diffraction ◽  
Diffraction Data ◽  
Electron Diffraction Data ◽  
Objective Lens ◽  
Lens System ◽  
Electron Crystallography ◽  
Diffraction Ring ◽  
Diffraction Patterns ◽  
Instrument Level

One of the main obstacles to performing electron crystallography analysis in a TEM is that the acquired electron diffraction data often exhibits some form of distortion introduced by the lens system. Recognizing this problem, Capitani et al. has proposed a method to detect such distortion, which is primarily elliptical, by using a single crystal standard. Once such elliptical distortion is characterized, electron diffraction data acquired later can then be corrected by means of image processing. However, it may be desirable to correct such distortion at the instrument level. In this article, a different approach to measuring diffraction elliptical distortion is proposed by characterizing diffraction ring patterns and it is demonstrated that by varying the objective lens stigmation settings, it is possible to eliminate this elliptical distortion completely.

Crystal Structure Determination of Glycerol-Containing Lipids from Electron Diffraction Data. Use of Analog Compounds Based upon Configurational Isomers of Cyclopentane-1, 2, 3-TRIOL

1977 ◽  
Vol 35 ◽  
pp. 24-25
Author(s):  
Douglas L. Dorset ◽  
Anthony J. Hancock
Keyword(s):  
Crystal Structure ◽  
Electron Diffraction ◽  
Diffraction Data ◽  
Structure Determination ◽  
Crystal Surface ◽  
Coherent Scattering ◽  
Crystal Structure Determination ◽  
Electron Diffraction Data ◽  
Polar Group ◽  
Axis Orientation

Lipids containing long polymethylene chains were among the first compounds subjected to electron diffraction structure analysis. It was only recently realized, however, that various distortions of thin lipid microcrystal plates, e.g. bends, polar group and methyl end plane disorders, etc. (1-3), restrict coherent scattering to the methylene subcell alone, particularly if undistorted molecular layers have well-defined end planes. Thus, ab initio crystal structure determination on a given single uncharacterized natural lipid using electron diffraction data can only hope to identify the subcell packing and the chain axis orientation with respect to the crystal surface. In lipids based on glycerol, for example, conformations of long chains and polar groups about the C-C bonds of this moiety still would remain unknown.One possible means of surmounting this difficulty is to investigate structural analogs of the material of interest in conjunction with the natural compound itself. Suitable analogs to the glycerol lipids are compounds based on the three configurational isomers of cyclopentane-1,2,3-triol shown in Fig. 1, in which three rotameric forms of the natural glycerol derivatives are fixed by the ring structure (4-7).

Merging of electron-diffraction intensities acquired with a slow-scan CCD camera of crotoxin complex crystals to 3.5Å resolution

1994 ◽  
Vol 52 ◽  
pp. 104-105
Author(s):  
Jaap Brink ◽  
Wah Chiu
Keyword(s):  
Electron Diffraction ◽  
Ccd Camera ◽  
Crystal Thickness ◽  
Local Contrast ◽  
Camera Model ◽  
Data Set ◽  
3 Dimensional ◽  
Diffraction Mode ◽  
Diffraction Patterns ◽  
Complex Crystals

Crotoxin complex is the principal neurotoxin of the South American rattlesnake, Crotalus durissus terrificus and has a molecular weight of 24 kDa. The protein is a heterodimer with subunit A assigneda chaperone function. Subunit B carries the lethal activity, which is exerted on both sides ofthe neuro-muscular junction, and which is thought to involve binding to the acetylcholine receptor. Insight in crotoxin complex’ mode of action can be gained from a 3 Å resolution structure obtained by electron crystallography. This abstract communicates our progress in merging the electron diffraction amplitudes into a 3-dimensional (3D) intensity data set close to completion. Since the thickness of crotoxin complex crystals varies from one crystal to the other, we chose to collect tilt series of electron diffraction patterns after determining their thickness. Furthermore, by making use of the symmetry present in these tilt data, intensities collected only from similar crystals will be merged.Suitable crystals of glucose-embedded crotoxin complex were searched for in the defocussed diffraction mode with the goniometer tilted to 55° of higher in a JEOL4000 electron cryo-microscopc operated at 400 kV with the crystals kept at -120°C in a Gatan 626 cryo-holder. The crystal thickness was measured using the local contrast of the crystal relative to the supporting film from search-mode images acquired using a 1024 x 1024 slow-scan CCD camera (model 679, Gatan Inc.).

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