Zeeman effect and its properties ppt.pptx

Zeeman effect

1. ZEEMAN EFFECT By E. Chris Monica Assistant Professor, Department of physics, E.M.G Yadava women’s College, Madurai-14.

2. Zeeman effect is the splitting of a  spectral line  into two or more components of slightly different frequency when the  light  source is placed in a  magnetic field. It was first observed in 1896 by the Dutch physicist  Pieter Zeeman  as a broadening of the yellow D-lines of sodium in a flame held between strong magnetic poles. Later the broadening was found to be a distinct splitting of spectral lines into as many as 15 components . INTRODUCTION

3. The pattern and amount of splitting signify that a magnetic field is present and of its strength. The Zeeman splitting is associated with the atomic level’s orbital angular momentum quantum number L. The quantum number L can assume values that are non-negative integers. The formula 2* L+1 can ascertain the magnetic field splitting in terms of levels. Zeeman Splitting

4. In atomic physics, different letters are used to represent the quantum levels, F or L=0 , “ s” is used L=1 , “ p” is used L=2 , “ d” is used. These denotations are carried on for higher levels as well. It is also customary to precede this designation with the integer principal quantum number n.

5. Thus, the designation "2p" indicates a level that has L equal to 1 and n equal to 2. In order to observe the Zeeman splitting, the Zeeman effect experiment needs to be carried out. This splitting of spectral lines under the magnetic field is also known as Zeeman shifts. 

6. DEFINITION Normal Zeeman effect is the phenomenon that explains the splitting of a spectral line into three components in a magnetic field when observed in a direction perpendicular to the applied magnetic field. This effect is explained by the basis of classical physics. In normal Zeeman effect, only orbital angular momentum is considered. NORMAL ZEEMAN EFFECT

7. The spin angular momentum, in this case, is zero. Normal Zeeman effect is only valid for transitions between singlet states in atoms.   The elements that give the normal Zeeman effect include He, Zn , Cd, Hg , etc . For singlet states, the spin is zero and the total angular momentum J is equal to the orbital angular momentum L.

8. When placed in an external magnetic field the energy of the atom changes because of the energy of its magnetic moment in the field, which is given by

9. DEFINITION Anomalous Zeeman effect is the phenomenon that explains the splitting of a spectral line into four or more components in a magnetic field when viewed in a direction perpendicular to the magnetic field. This effect is more complex unlike normal Zeeman effect . ANOMALOUS ZEEMAN EFFECT

10. It can be explained by basis of quantum mechanics. The atoms with spin angular momentum show the anomalous Zeeman effect. Na , Cr, etc., are elemental sources that show this effect . The anomalous Zeeman effect occurs when the spin of either the initial or the final states, or both, is nonzero.

11. The calculation of the energy-level splitting is complicated a bit by the fact that the magnetic moment due to spin is 1 rather than ½ Bohr magneton. As a result the total magnetic moment is not parallel to the total angular momentum. Consider an atom with orbital angular momentum L and spin S . Its total angular momentum is J = L + S

12. where as the total magnetic moment is Each energy level is split into 2 j + 1 levels, corresponding to the possible values of mj .

13. Normal Zeeman Effect Normal Zeeman Effect is the splitting of spectral lines of an atomic spectrum due to the interaction between the external magnetic field and the orbital magnetic moment . Splitting Pattern: In normal Zeeman effect, one spectral line is split into a triplet . Magnetic Moment:   Normal Zeeman effect occurs due to the presence of orbital magnetic momentum. CONCLUSION

14. Anomalous Zeeman Effect   Anomalous Zeeman Effect is the splitting of spectral lines of an atomic spectrum that is caused by the interaction between the magnetic field and the combined orbital and intrinsic magnetic momentum . Splitting Pattern: In anomalous Zeeman effect, one spectral line is split into different complicated patterns. Magnetic Moment:  Anomalous Zeeman effect occurs due to the presence of both orbital and intrinsic magnetic moment.