SPECTROSCOPY: MAGNETICS

Question 1

What is spin angular moment

Answer 1

The spin of the different poles of an electron in a magnetic field and the movement of the electron gives rise to a small magnetic field (rotating around pole) and the spin quantum number (+1/2 and -1/2)

Question 2

What is orbital angular momentum

Answer 2

Orbital motion of the electron around the nucleus. Circulation of charge around the nucleus

Question 3

What is magnetic susceptibility

Answer 3

Measure of how much a material will become magnetised in an applied magnetic field

Question 4

What are para and dia magnetisim

Answer 4

Paramagnetism: X > 0, alignment/attraction with the magnetic field

Diamagnetism: X < 0, alignment against/push away the magnetic field

Question 5

What is magnetic moment

Answer 5

represents the orientation and torque acted on a sample in a magnetic field

Question 6

What is the conceptual difference between magnetic susceptibility and effective magnetic moment

Answer 6

Magnetic susceptibility is a fundamental property of magnetic materials

Ueff is arbitrarily derived from magnetic susceptibility to relate to spin and unpaired electrons

Question 7

What is the equation for ueff to Xm

Answer 7

ueff = 2.828 x sqroot(XmT)

Question 8

What is the equation between spin and unpaired electrons

Answer 8

S = n/2

Question 9

What is the difference between uSO and ueff

Answer 9

ueff takes into consideration all types of momentum including spin and orbital angular momentum

uSO is only spin angular momentum

Question 10

What are the equations between uSO and S and n

Answer 10

uSO = 2 x sqroot(S(S+1))

uSO = sqroot(n(n+2))

Question 11

What is magnetic susceptibility the sum of

Answer 11

the diamagnetic and paramagnetic susceptibilities

Question 12

How do we calculate a diamagnetic correction

Answer 12

We use constants added together by the number of specific atoms in the compound to give the diamagnetic susceptibility.

Question 13

Why is uSO sometimes not similar to ueff

Answer 13

It is due to the orbital angular momentum especially when there are unpaired electrons in the t2g orbitals

Question 14

When does an unpaired electron contribute to OAM

Answer 14

When it is in an orbital that can transform into identical degenerate orbitals by simple rotation. This rotation generates OAM\

dxy, dyz, dxz = t2g orbitals

Question 15

What do A, E and T molecular term symbols represent

Answer 15

A = singly degenerate

E = doubly degenerate

T = triply degenerate

of all the d electrons in all d orbitals

Question 16

Which molecular term symbol has OAM

Answer 16

T

Question 17

If we have a T molecular term symbol then temperature …

Answer 17

affects magnetic moment

Question 18

What is the reasoning behind some A and E term complexes having a difference between uSO and ueff

Answer 18

If a T term lies close in energy (such as an excited state) with the same spin

This can lead to mixing in of OAM by spin orbit coupling

Question 19

What is the equation to find spin orbit coupling

Answer 19

ueff = uSO (1- a x lambda/delta oct)

a = 2 for E terms

a = 4 for A terms

Question 20

Why is ueff is indirectly proportional to delta oct

Answer 20

Larger splitting, less likely effect on u as the energy difference is quite large