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

Profits, explain abnormal profits and normal profits

explain abnormal profits and normal profits

Economics, Ask questiowhat are the importance of the branches of economics

Ask questiowhat are the importance of the branches of economics

Determinants of private demand for education, Determinants of Private Deman...

Determinants of Private Demand for Education Rates of return on investment in education is only one of the factors determining the demand for private investment though it is

Tort liability, Construct a table indicating the social expected loss corre...

Construct a table indicating the social expected loss corresponding to each combination of precaution choices by the two individuals. (ii) What is the socially efficient combinatio

Private property regime , Normal 0 false false false EN...

Normal 0 false false false EN-IN X-NONE X-NONE MicrosoftInternetExplorer4

Financial relationship with the imf, Financial relationship with the IMF: ...

Financial relationship with the IMF: IMF provides temporary assistance to member countries to tide over BOP deficits. When a country requires foreign exchange, its tenders its

What are accounting costs and economic costs, It is necessary for the prope...

It is necessary for the proper understanding of the price theory to know the various concepts of cost that are often employed. When an entrepreneur undertakes production of a commo

Price elasticity of demand , Describe what the price elasticity of demand i...

Describe what the price elasticity of demand is and why it is of interest in examining markets.  Might it be beneficial in the airline industry?  Why?

Unemployment, Unemployment: Unemployment refers to a situation where p...

Unemployment: Unemployment refers to a situation where people who are willing and able to work do not find jobs at the existing wage rate.For a person to be referred to as une

Equilibrium level of economic output, Provide an economic explanation of wh...

Provide an economic explanation of what you have shown in your diagram above.  Iceland was a small open economy with perfect capital mobility. Consequently, the equilibrium domesti

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