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

Utitility, In November 2010, every Mzumbe University student had an income ...

In November 2010, every Mzumbe University student had an income of 150000/= per month,facing the price of meal (X) 1000/= and average price of other goods (Y) 1000/=.The initial ut

Define regressive tax, Q. Define Regressive Tax? Regressive Tax: A tax ...

Q. Define Regressive Tax? Regressive Tax: A tax in that lower-income individuals or households bear a proportionately greater burden of the tax. Sales taxes aretypically consid

Assignment, suppose you have a coffee shop. list of fixed input and variabl...

suppose you have a coffee shop. list of fixed input and variable input for operating the shop. ques-2 describe the condition under in which labour treated as variable cost and whic

What do you meant by fiscal policy, Question 1: (a) Describe what is Ec...

Question 1: (a) Describe what is Economic growth and describe its relationship with standard of living? (b) Assuming you are the government economist, what policy measures

Demand-pull inflation, The average price level has increased at a relativel...

The average price level has increased at a relatively rapid rate since 2008 even though the deep recession that UK experienced in 2008/09. The growth in the price level has been dr

Elasticity of Demand, the price elasticity for gizmos is known to be 1, if ...

the price elasticity for gizmos is known to be 1, if sellers of gizmos increase their

Implementation of economic policy, Implementation of economic policy: ...

Implementation of economic policy: On the ability of civil servants and Government to learn, Government must possess the following qualities to ensure implementation of econom

Current account deficit, Current Account Deficit (CAD): Boon or Bane ...

Current Account Deficit (CAD): Boon or Bane The general belief is that high CADs are dangerous. In general, this is correct. But the converse that low CADs are good is not. A

Explain about employment rate, Q. Explain about Employment Rate? Emplo...

Q. Explain about Employment Rate? Employment Rate: This measures share of working age adults who are in fact employed in a paying position. Employment rate can be a better in

Theories of the firm, how a firm will choose its optimal inputs, isocosts a...

how a firm will choose its optimal inputs, isocosts and isoquants explanation

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