Hyperfine splitting

atomic and molecular science

1. Hyperfine splitting Its role in A tomic transition Roll no: 15251510-002

2. Definition Interaction between electron spin and nuclear spin is known as hyperfine interaction and splitting occur due to this interaction is called hyperfine splitting. When the electron spin interacts with nuclear spin then each electron spin state split into 2I+1 level this is known as hyperfine splitting.

3. Rules to determine nuclear spin: A nucleus with an even number of proton and even no of neutron has zero spin I= 0 for example , A Nucleus with an odd number of proton and odd no of neutron has an integral spin. for example A nucleus with an odd mass has half integral spin for example  

4. Cont…. I= nuclear spin quantum no The nuclear spin can have several orientations for example; I=1 , may have =+1,0,-1 I=1/2 may have I=7/2 may have that is total of 2l+1  

5. Example: Hydrogen One unpaired electron ( of hydrogen interacts with its nuclear spin. I value of H is ½, therefore Each state will interact with value and split into 2I+1 . The energy of particular tate will be affected by nuclear spin –electron spin interaction energy. This energy varies the product of A is the hyperfine splitting constant. The energy of different levels are given by  

6. Cont…

7. Deuterium: It has one unpaired electron( interacts with nuclear spin. I value of therefore  

8. Applications: Astrophysics: In radio astronomy, heterodyne receivers  are widely used in detection of the electromagnetic signals from celestial objects. The separations among various components of a hyperfine structure are usually small enough to fit into the receiver's  IF  band.  Nuclear technology: The  atomic vapor laser isotope separation (AVLIS) process uses the hyperfine splitting between optical transitions in  uranium-235  and  uranium-238  to selectively photo-ionize only the uranium-235 atoms and then separate the ionized particles from the non-ionized ones. The hyperfine structure transition can be used to make a  microwave  notch filter with very high stability, repeatability and Q factor, which can thus be used as a basis for very precise atomic clocks.