Neutron diffraction, chemistry, Microeconomics

Assignment Help:

chemistry assignmentsNeutron diffraction supplements x-ray diffraction and is particularly helpful in locating hydrogen atoms.

An x-ray beam is scattered primarily as a result of interaction with the electrons that surround each atom of an ion or molecule. Thus the atomic scattering factors are approximately proportional to atomic numbers. As a result, it is difficult to locate low atomic number in the presence of high atomic number atoms. Thus the position of hydrogen atoms generally cannot be deduced from x-ray diffraction studies. (A positive attitude to this difficulty is the recognition add to the complexity of many already complex structure determinations.) Within a factor of 3 or 4, all nuclei or, more conveniently, deuterium nuclei can be located in the presence fo behavior atoms.

Neutron diffraction is also distinguished by the noticeable role of the magnetic moment of the neutron when diffraction occurs from crystals with ordered atomic magnetic moments. Neutrons diffraction can be used to study the orientation of atomic magnetic moments in ferromagnetic and antiferromagnetic crystals. Neutron diffraction is thus a specialized adjunct to z-ray diffraction.

A neutron beam is usually formed from the thermal neutrons of a nuclear reactor. A velocity selector device augmented by crystal diffraction provides a monochromatic beam. The wavelength associated with the neutron beam can be calculated from the de Broglie relation. The momentum term mv is obtained for thermal neutrons by setting

½ mv2 = 3/2 kT

And rearranging to get;

Mv = √3mkT

With appropriate numerical values, including 1.675 × 10-27 kg for the mass of a neutron, we obtain,

1.46 ×10-10 m = 146 pm

A beam of thermal neutrons therefore has a wavelength suitable for diffraction studies of crystals. A diffraction pattern like those obtained for x-ray diffraction except that a longer wavelength beam is used is obtained.

Typically crystals, whose structures are known, except for the postions of hydrogen atoms, are studied. The transform procedure is used that the positions fo these remaining nuclei are found. The smallness of the nuclei would lead to sharp peaks on a nuclear density map, but thermal motion produces some spreading of these peaks. 


Related Discussions:- Neutron diffraction, chemistry

Domestic development agenda, Problem : (a) Using examples of Least Deve...

Problem : (a) Using examples of Least Developed Countries, explain the: (i) causes of market failures; and (ii) consequences of market failures (b) Describe the common

Explain total fixed and variable costs, Fixed costs are those which are ind...

Fixed costs are those which are independent of output that is they do not change with changes in output. These costs are a fixed amount which must be incurred by a firm in the shor

Depreciation, Depreciation: This signifies the loss of value from an existi...

Depreciation: This signifies the loss of value from an existing stock of real capital (for an individual company or for whole economy), reflecting normal wear-and-tear of machinery

Explain the concept of land economic, (a) Give an overview of the Concept ...

(a) Give an overview of the Concept of Land Economic (b) Provide a definition of Land/Economics (c) Discuss the origin of Land Economics (d) Modern and Traditional Land Ec

Assignement, need help for my micro assignment

need help for my micro assignment

Examine recent developments in demand theory, Critically examine recent dev...

Critically examine recent developments in demand theoryon #Minimum 100 words accepted#

Economic system, explain the fundamental task of economic system usin tomat...

explain the fundamental task of economic system usin tomatoes as an example

Marginal utility theory, discuss whether marginal utility is a realistic pi...

discuss whether marginal utility is a realistic piece of economy analysis in a consumer demand

Write Your Message!

Captcha
Free Assignment Quote

Assured A++ Grade

Get guaranteed satisfaction & time on delivery in every assignment order you paid with us! We ensure premium quality solution document along with free turntin report!

All rights reserved! Copyrights ©2019-2020 ExpertsMind IT Educational Pvt Ltd