Topic 5

Question 1

What λ represents?`

Answer 1

Angular momuntum along the internuclear axis

Question 2

What is λ analogous in atom to?

Answer 2

To m_l, e.g. a p orbital has l=1, m_l=0, ±1

Question 3

What bond is σ?

Answer 3

The one that as we move around intermolecular acis, no change in the sign of wavefunction occurs.

Question 4

What bond is formed when we combine two p_z (m_l=0) orbitals?

Answer 4

σ and σ^* (λ=0)

Question 5

What bonds are formed when we combine p_x,y (m_l=±1) orbitals?

Answer 5

π and π* (λ=±1)

Question 6

What bond is π?

Answer 6

The one that as we move around the intermolecular axis, a change in the sign of the wavefunction occurs.

Question 7

What is label g represents?

Answer 7

That there is a symmetry in molecule through the centre.

Question 8

What does label u represents?

Answer 8

That there is no symmetry in molecule through the centre.

Question 9

What are term symbols for diatomic molecular electronic states?

Answer 9

Question 10

In what case we get a g label when combining diatomic molecules?

Answer 10

When we gave g and g molecules or we have u and u

Question 11

In what case we get a u label when combining diatomic molecules?

Answer 11

When we have g and u molecules

Question 12

What is sigma (Σ) term?

Answer 12

We denote the symmetry (+/-) with respect to reflection in a plane containing the internuclear axis. If sign changes under reflection then it is -, if it stays the same it is +

Question 13

What is the term symbol for all closed-shell homoniclear diatomic molecules?

Answer 13

¹Σ⁺_g

Question 14

When do we get Σ^- states?

Answer 14

Just with configurations like π²

Question 15

What lable is given to ground state?

Answer 15

X

Question 16

What labels are given to higher electron states with the same spin multiplicity as the ground state?

Answer 16

A, B, C…

Question 17

What labels are given to higher electron states with different spin multiplicity as the ground state?

Answer 17

a, b, c

Question 18

What is the Franck- Condon principle?

Answer 18

It is an assumption that electroniv transitions take place on such a short timescale that the nuclei remain frozen (R unchanged) during the transition.

Question 19

What is Franck-Condon factors?

Answer 19

The square of the overlap of the two vibrational wavefunctions.

Question 20

What are two vibrational transitions?

Answer 20

Adianatic - between v’=0 and v’‘=0

Vertical- the ones that has the highest overlap between the ground and excited vibrational wave function

Question 21

When does the loss of the structrure occurs in vibrational transitions?

Answer 21

v₀+D’₀

Question 22

How to calculate enrgy of the maximum v?

Answer 22