![ This type of assymetry is weak ∆EQ= Small
For example:
Fe(CN)₆⁴−
Ligand assymetry absent
[Fe(CN)₅NO]−−
Ligand assymetry present](https://image.slidesharecdn.com/quadrapoleandzeemansplitting-201010145644/85/Quadrapole-and-zeeman-splitting-8-320.jpg)
![[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](https://image.slidesharecdn.com/quadrapoleandzeemansplitting-201010145644/85/Quadrapole-and-zeeman-splitting-10-320.jpg)
![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]+](https://image.slidesharecdn.com/quadrapoleandzeemansplitting-201010145644/85/Quadrapole-and-zeeman-splitting-11-320.jpg)
![ 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)](https://image.slidesharecdn.com/quadrapoleandzeemansplitting-201010145644/85/Quadrapole-and-zeeman-splitting-15-320.jpg)
![ [Fe(ptz₃)₆]²+
d⁶ - high spin
Electronic asymmetry
Ligand symmetry](https://image.slidesharecdn.com/quadrapoleandzeemansplitting-201010145644/85/Quadrapole-and-zeeman-splitting-16-320.jpg)
![[Fe(phen)₃(H₂O)]²−
D⁶ - Low spin –electronic symmetry
For 4d 5d transition metal complexes no
spin crossover is observed.](https://image.slidesharecdn.com/quadrapoleandzeemansplitting-201010145644/85/Quadrapole-and-zeeman-splitting-17-320.jpg)
![[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](https://image.slidesharecdn.com/quadrapoleandzeemansplitting-201010145644/85/Quadrapole-and-zeeman-splitting-22-320.jpg)
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.