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

Liberalisation of the economy, Liberalisation of the Economy: Removal...

Liberalisation of the Economy: Removal of Industrial Licensing: All industrial licensing was abolished but for a shortlist of 18 industries related to security and strategic

Elastics and inelastics, You just opened a flower shop and are trying to un...

You just opened a flower shop and are trying to understand pricing issues. You were told that elasticities are very important in determining prices and what products to supply, so

Rule of thumb method, Rule of Thumb Method Sir Ashby had been requeste...

Rule of Thumb Method Sir Ashby had been requested in 1960 by the Government of Nigeria to submit a report on manpower development in Nigeria. In doing so, in the absence of re

Demand curve for a consumer for coffee, Suppose the demand curve for a cons...

Suppose the demand curve for a consumer for coffee is: Q = 6 – 2P, where Q represents the number of cups per day and P is the price of coffee per cup.   Question: Suppose the

Production having two outputs - economies of scope, Production having Two O...

Production having Two Outputs -Economies of Scope *  Economies of scope exist when joint output of a single firm is greater than the output which could be achieved by two diffe

Demand and supply, Dance fans switches away from Dance music to R&B music A...

Dance fans switches away from Dance music to R&B music AND the price of MP3 players increases

Keynesian model, in the keynesian model the price is assumed to be what? a....

in the keynesian model the price is assumed to be what? a.exogeneous and remaaining constant b. endogeneous and remaining constant which is correct?

What are the functions of money, Functions of Money Money performs sev...

Functions of Money Money performs several important functions. It serves as a medium of exchange, a unit of account, a store of value and a standard of deferred payments. In a

Explain the development process of a developing country, Explain how foreig...

Explain how foreign aid might help in the development process of a developing country. Definition/outline of various forms of aid, i.e. donor aid, tied aid, bilateral aid etc.

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