Quadrapole and Zeeman splitting

1. SUBMITTED BY:
Pragya Parmita Dwivedi
M.Sc. II SEM-III
ISABELLA THOBURN COLLEGE

2.  Nuclear interactions
 Electric quadrapole moment of nuclei
 What is a electric quadrapole?
 What is electric quadrapole splitting?
 Ligand asymmetry
 Electronic asyymetry
 Effect of temperature on mossbauer spectra
 Zeeman splitting
 References

3.  Typically, three types of nuclear
interactions may be observed in Mossabeaur
spectroscopy:
1. the Isomer shift due to differences in nearby
electron densities (also called the chemical
shift ).
2. Quadrupole splitting due to atomic-scale
electric field gradients.
3. Magnetic Zeeman splitting due to non-
nuclear magnetic fields.

4. Charge separation over two sites (1+ve ,1-ve) gives a dipole
Charge separation over four sites (2+ve,2-ve) gives a quadrapole.

5.  The nuclear electric quadrapole moment is
the measure of deviation of nuclear charge
distribution from a spherical shape(Q₀).

6.  It arises due to interaction between Electric Quadrapole
Moment of nucleus and Electric Field Gradient
 Defines no. of peaks in spectrum(no. of lines=I+1/2)
It occurs when nuclei Spin> ½
Assymetric charge distribution
Assymetry Ligand Assymetry
electronic assymetry
•Without EFG(EFG=0) all the energy levels are degenrate (singlet signal)
i.e., no quadrapole splitting
•With EFG(EFG≠0) Energy levels will split into I+1/2 energy levels
(doublet signal)i.e.,quadrapole splitting takes place.

8.  This type of assymetry is weak ∆EQ= Small
 For example:
Fe(CN)₆⁴−
Ligand assymetry absent
[Fe(CN)₅NO]−−
Ligand assymetry present

9.  This type of assymetry is strong.∆EQ=large

10. [Fe(H2o)₅Cl]²+
Ligand asymmetry
d⁵-high spin
Electronic symmetry
Weak splitting
[Fe(H₂O)₆]²+
d⁶-high spin
Ligand symmetry
Electronic asymmetry
Moderate splitting
[Fe(H₂O)₅Cl]+
d⁶ -High spin
Ligand asymmetry
Electronic asymmetry
Large splitting

11. In cis form there is some kind of asymmetry present due to cl atoms
Cis and trans form can be differntiated with Mossabaur spectra as
cis form gives 2 peaks and trans form gives one peak.
[Fe(H₂0)₄Cl₂]+

12. SnCl₄ , SnI₄ , SnF₄ , SnBr₄
EWG in Sn compounds decreases isomer shift.
 Tetrahedral-Sncl₄, SnBr₄,SnCl₄
 body centred tetragonal-SnF₄

13. IF₆‾
No electronic asymmetry
Ligand asymmetry present because
IF₆‾ has distorted octahedral
structure
Quadrapole splitting observed.

15.  In spin crossover studies at higher temperatures a high
spin complex is preferred and at low temperature a low
spin complex is preffered.
 [Fe(phen)₂(NCS)₂]
 Phen is a Sfl but NCS is a WFl so overall this complex is
high spin(d⁶)

16.  [Fe(ptz₃)₆]²+
 d⁶ - high spin
 Electronic asymmetry
 Ligand symmetry

17. [Fe(phen)₃(H₂O)]²−
 D⁶ - Low spin –electronic symmetry
 For 4d 5d transition metal complexes no
spin crossover is observed.

18. 18
• In the presence of a magnetic field the
nuclear spin moment experiences a dipolar
interaction with the magnetic field ie Zeeman
splitting
• The total effective magnetic field at the
nucleus, Beff is givenby
Beff = (Bcontact + Borbital + Bdipolar) +
Bapplied

19. • The first three terms being due to the
atom's own partially filled electron
shells.
• Bcontact is due to the spin on those
electrons polarising the spin density
at the nucleus
• Borbital is due to the orbital moment
on those electrons, and Bdipolaris the
dipolar field due to the spin of those
electrons.
Energy of the nuclear levels
Em= -gμNBmI
19

20. • This magnetic field splits nuclear levels
with a spin of I into (2I+1) substates.
• Transitions between the excited state
and ground state can only occur where
mI changes by 0 or 1.
• This gives six possible transitions for a
3/2 to 1/2 transition, giving a sextet ,
with the line spacing being
proportional to Beff.
20

21. 21
• The outer, middle and inner line
intensities are related by:
3 : (4sin2θ)/(1+cos2θ) : 1
Selection rule, ∆ms=0,±1

22. [NiF₆]²¯
No.of quadrapole splitting = I+1/2
=5/2+1
=3
No. of Zeeman splittng lines=2I+1
=2*5/2+1
=6
2*3/2+1=4
2*1/2+1=2
Total zeeman lines=12

23. Generally this type of splitting occurs in ferromagmetic and
antiferromagnetic

24. https://www.tau.ac.il/~lab3/MOSSBAUE
R/Literature/Mossbauer_Harvard.pdf
 https://www.uni-
muenster.de/imperia/md/content/physik
alische_chemie/app_moessbaueren.pdf
Fundamentals of Molecular
spectroscopy(fourth edition) Collin
Banwell and Elainem.