SOLID STATE - CRYSTAL STUDIES

Bragg's spectrometer method

•  X-rays are used to study the crystal structures.

•  Bragg's spectrometer works on the principle of diffraction.When X-rays produced from coolidge tube are made to fall on the crystal at a particular angle of incidence,the rays gets diffracted and enter the ionisation chamber and ionise the gas present in it.Thus current is produced,which is measured by an electrometer.

• The current strength is a direct measure of intensity of the diffracted rays.
• Here you can see a real Bragg's spectrometer

 Note the deflection in the electrometer i.e, at this angle the current is very low

 The current strength is gradually increasing

 At this angle the maximum diffraction occurs,thus it is taken as first order reflection i.e., n = 1

 Again when you increase the angle current drops to minimum and maximum reflection occurs at another higher angle,which can be taken as second order reflection.