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

Explain about the deadweight loss and elasticitie, Explain about the deadwe...

Explain about the deadweight loss and elasticitie s. Deadweight Loss and Elasticities The general rule for economic policy is the other things equivalent; you need to choose

Bains model of limit pricing., explain diagrammatically the bains model of ...

explain diagrammatically the bains model of limit pricing.

Demand and supply, identify which curve (demand or supply) will be affected...

identify which curve (demand or supply) will be affected?

Explain the appliance for household use be treated, In an updated GDP that ...

In an updated GDP that contains household production, how would the purchase of a car or appliance for household use be treated? A car or appliance would be treated as a househ

Neer vs reer, NEER Vs REER: In a situation where there are multiple tr...

NEER Vs REER: In a situation where there are multiple trade partners, the effect of cross-currency movements are judged by nominal effective exchange rate (NEER) and real effe

Production possibilities curve .., How does the production possibilietes cu...

How does the production possibilietes curve relate to present day economics?

A significant majority of consumers, Normal 0 false false f...

Normal 0 false false false EN-IN X-NONE X-NONE MicrosoftInternetExplorer4 The demand schedule c

State the keynesian theory of employment, Q. State the Keynesian Theory of ...

Q. State the Keynesian Theory of employment? Under employment Theory, Govt interference Aggregate Demand- Aggregate supply- Effective demand, Income and employment consumption

Subsitution and income effect, subsitution effect dominate tha income effec...

subsitution effect dominate tha income effect in which good case?

Short notes, Amartya Sen''s concept of poverty and welfare.

Amartya Sen''s concept of poverty and welfare.

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