Energy Dispersive X-ray Diffraction - Report Example

ENERGY DISPERSIVE X-RAY DIFFRACTION Name Course, Class, Semester Institution Instructor Date Energy Dispersive X-ray Diffraction Introduction Energy dispersive x-ray diffraction is a method for material characterization that uses analytical techniques (Brunken, Krause & Ellmer 2012). Through this process full diffraction patterns can be collected within the shortest time. This analytical technique is normally used together with synchrotron radiation. X-ray diffraction methods are very crucial for the structural study of various materials. Gordon, Giessen and Buras among others separately introduced the idea of using this new energy dispersive X-ray diffraction to obtain structural information. This paper presents a summary of energy dispersive x-ray diffraction. The energy dispersive x-ray diffraction method works on the basis of the good energy resolution in semi conductor detectors. Collimated white colored x-rays are spread out in the sample via a maximized angle 2. A semi conductor detector that is connected to a pulse height analyzer with many channels is used to analyze the distribution of energy in the dispersed photons. When the distribution of energy in the spread out x-rays is measured, it shows differently formed peaks. This is similar to what is seen when angle dispersive technique of diffraction is used (Brunken et al 2012, pp. 12). This provides the much needed information for studying the structures of materials. The Energy dispersive x-ray diffraction (EDXRD) is advantageous in several ways when compared to the conventional ADXRD method. The EDXRD method has various benefits. One of these benefits is the fixed scattering angle method. When using the EDXRD method, only one exit window and one entrance are necessary (Wang 2006, pp. 34). The second benefit is the reduction in the time of exposure. This enables a person to make a quick analysis of structure and this method is appropriate for studying materials that are not stable over short durations. The other benefit is that it is possible to simultaneously get the entire radiation spectrum diffracted through the sample. This makes the technique suitable for structure and texture studies whereby the change in the rate of the structure within the sample relies on crystallographic dimensions. In addition, since the whole pattern recording is at one particular moment, it is possible to do away with variations in the environment of the sample from one peak in the diffraction to the other. However, there are difficulties in making use of the EDXRD technique. One of these difficulties is that the peaks tend to be more than one magnitude order wide when compared to ADXRD (Wang 2006, pp. 23). The spreading out in terms of spectral intensity of the white incident x-rays that can be obtained from a conventional target is limited and it is also not limited. Another problem is the polarization influence that the basic x-ray beam has on integrated intensities. There is also the need for absorption corrections that are dependent on energy. Another issue is the there are fluorescent peaks present in this technique. There is also the problem of the restricted input rate of counting. The entire input rate of counting for all the photons getting into the detector should not be more than 5,000 and 10,000 photons per second. This is so because the present condition of electronics presents serious limitations. Some of the problems mentioned above can be done away with through the use of the X-radiation that comes from synchrotrons that possess lofty energy amounts. The radiation made by the synchrotrons, more so from the storage ring appears as the appropriate source of X-rays for EDXRD. The high intensity of synchrotron radiation, its properly defined polarization and its smooth spectrum make it manageable to get quantitative intensity measurements. In addition, one can obtain data that has very high values. Within a 10 year period, the EDXRD method has become a remarkable and very much recognized tool among conventional diffraction methods. EDXRD depends on the study of the meeting of a certain source of excitation of x-rays and a particular sample (Zhao 2007, pp. 67). Its abilities of characterization are because of the basic idea that every one of the elements has a peculiar atomic formation which allows a unique set of peaks on its X-ray spectrum. So as to trigger the release of specific X-ray beams from a particular specimen, a beam with a lot of energy with particles full of charge like protons and electrons or alternatively, an x-ray beam must be directed at the sample under study. While not in motion, a single atom within this sample has motionless state or in other words, electrons that are not excited in separate energy levels or shells in which the electrons exist that are normally attached on the nucleus. The incident rays can excite one electron within the inner energy level, forcing it out of the shell and making a hole in the place where the electron existed. An electron originating in a higher and outer energy level occupies that hole and the energy gap between the lower and higher energy shells can be set free as X-rays. The amount and the X-ray energy that is released from a particular specimen may be measured by way of an energy dispersive spectrometer. Since the X-ray energy are used to show the energy difference between the 2 energy levels as well as that between the atomic structure of the element that they are emitted from, this makes it possible for a person to measure the composition of elements in the specimen (Garrat-Reed & Bell (n.d, pp. 4). The technique utilizes a set up of components including the source of excitation which may be an X-ray or beam of electrons, the detector for x-rays, the analyzer and pulse processor. The excitation of electron beams is used within electron microscopes, scanning transmission electron microscopes and other electron microscopes used for purposes of scanning. The excitation of X-ray beams is used in x-ray fluorescence spectrometers. A detector should be used for the purpose of converting X-ray energy into the voltage signals. This information is then sent to the pulse processor that gauges the signals before passing them to an analyzer for the analysis and display of data. The most popular detector being used is Si (Li) detector that is cooled down to very low temperatures using liquefied nitrogen. Nevertheless, new systems normally come with silicon drift detectors that have better cooling systems (Wang 2006, pp. 67). The X-ray diffraction method is used in many places for the study of the structure of materials in different conditions of thermodynamics where pressure and temperature differences are involvd (Zhao, 2007, pp. 87. The X-ray diffraction method has two variants which are the ADXRD and the EDXRD. In the energy method of dispersion, a sample normally visibly exposes to the X-rays with white color and the X-rays under diffraction are analyzed by use of energy and at a fixed angle. The Energy dispersive X-ray diffraction technique is normally useful in conditions where there is the relevance for temporary progressive change in a sample or where the measurements need constrained geometry like the one for different samples at extremely high temperatures and extremely lofty pressures among other conditions (Garrat-Reed & Bell (pp. 4). As opposed to area detectors that are used in the method of ADXRD variant in which a diffraction pattern is visible only when the measurement is ending the use of an energy sensitive detector that has a multichannel analyzer in the EDXRD makes it possible for people to do online viewing of the entire pattern of diffraction while the data is being collected. This is an important feature of the EDXRD technique that makes it appropriate for kinetics studies. In general terms the EDXRD technique avails data over a wide area (Brunken et al 2012, pp. 2). Future development of the EDXRD The EDXRD is growing to address the issues surrounding the enhancement of nano-technologies by way of moving forward spatial resolution. Because of this there have been huge developments the instruments used in laboratories and dedicated synchrotron beam lines all over the world and a very competitive context should be expected in the future (Yang, Shen, Wang & Mao (pp. 3). Towards this end energy dispersive X-ray diffraction will play a critical role by providing peculiar capabilities in the analysis and investigation of complex systems. At the end of it, this complexity can be seen in three ways which are spatial, compositional and temporal. Normal experiments may be divided into 2 categories which include morphological studies that need high spatial resolution and also studies that deal with co-localization as well as the speciation of tiny elements found within diverse systems. Scans done for X-ray microprobes by use of different modes of detection are suitable for the subsequent cases that often need low measures of detection as well as spectroscopic investigation capability for chemical make up and in comparison to other techniques, energy dispersive X-ray diffraction has a very unique feature combination. When related with a system of detection of lofty efficiency there is very low radiation damage and it is possible to have accurate quantification (Ma, Mao, Hemley, Gramsch, Shen & Somayazulu 2001, pp. 32). More so, the probability of experiments done without movement is still a rare aspect of the EDXRD. When x-rays penetrate physically, it makes it possible for particular sample environments to be created for the study of realistic systems within the environment that is close to their native environment instead of going in the form of a model system. The possibility of analyzing in situ within environmental cavities like low or high temperatures, high pressure or even wet cells gives a reason as to why there is an increased interest from communities like microbiology, earth sciences and environmental science. In the recent past, there have been developments that have made it possible to have fluorescence tomography in which two dimensional slices can be obtained via a 3 –dimensional object with no physical sectioning (Kvick, Mills and Ohta 2006, pp. 56). Read More

The spreading out in terms of spectral intensity of the white incident x-rays that can be obtained from a conventional target is limited and it is also not limited. Another problem is the polarization influence that the basic x-ray beam has on integrated intensities. There is also the need for absorption corrections that are dependent on energy. Another issue is the there are fluorescent peaks present in this technique. There is also the problem of the restricted input rate of counting. The entire input rate of counting for all the photons getting into the detector should not be more than 5,000 and 10,000 photons per second.

This is so because the present condition of electronics presents serious limitations. Some of the problems mentioned above can be done away with through the use of the X-radiation that comes from synchrotrons that possess lofty energy amounts. The radiation made by the synchrotrons, more so from the storage ring appears as the appropriate source of X-rays for EDXRD. The high intensity of synchrotron radiation, its properly defined polarization and its smooth spectrum make it manageable to get quantitative intensity measurements.

In addition, one can obtain data that has very high values. Within a 10 year period, the EDXRD method has become a remarkable and very much recognized tool among conventional diffraction methods. EDXRD depends on the study of the meeting of a certain source of excitation of x-rays and a particular sample (Zhao 2007, pp. 67). Its abilities of characterization are because of the basic idea that every one of the elements has a peculiar atomic formation which allows a unique set of peaks on its X-ray spectrum.

So as to trigger the release of specific X-ray beams from a particular specimen, a beam with a lot of energy with particles full of charge like protons and electrons or alternatively, an x-ray beam must be directed at the sample under study. While not in motion, a single atom within this sample has motionless state or in other words, electrons that are not excited in separate energy levels or shells in which the electrons exist that are normally attached on the nucleus. The incident rays can excite one electron within the inner energy level, forcing it out of the shell and making a hole in the place where the electron existed.

An electron originating in a higher and outer energy level occupies that hole and the energy gap between the lower and higher energy shells can be set free as X-rays. The amount and the X-ray energy that is released from a particular specimen may be measured by way of an energy dispersive spectrometer. Since the X-ray energy are used to show the energy difference between the 2 energy levels as well as that between the atomic structure of the element that they are emitted from, this makes it possible for a person to measure the composition of elements in the specimen (Garrat-Reed & Bell (n.d, pp. 4).

The technique utilizes a set up of components including the source of excitation which may be an X-ray or beam of electrons, the detector for x-rays, the analyzer and pulse processor. The excitation of electron beams is used within electron microscopes, scanning transmission electron microscopes and other electron microscopes used for purposes of scanning. The excitation of X-ray beams is used in x-ray fluorescence spectrometers. A detector should be used for the purpose of converting X-ray energy into the voltage signals.

This information is then sent to the pulse processor that gauges the signals before passing them to an analyzer for the analysis and display of data. The most popular detector being used is Si (Li) detector that is cooled down to very low temperatures using liquefied nitrogen. Nevertheless, new systems normally come with silicon drift detectors that have better cooling systems (Wang 2006, pp. 67). The X-ray diffraction method is used in many places for the study of the structure of materials in different conditions of thermodynamics where pressure and temperature differences are involvd (Zhao, 2007, pp. 87.

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