Infrared Flashcards
(7 cards)
1
Q
Important features of molecules
A
- atoms in a molecule vibrate back and forth
- ‘bond length’ is an average value
- a diatomic molecule (e.g. HCl) can only undergo a stretching vibration
- more complex molecules exhibit both stretching and bending vibrations
- vibrational motion is excited within a single electronic state by infrared light
2
Q
Importance of hydrogen in vibration bonds
A
Vibration bonds involving hydrogen are very significant as atoms of low mass move a lot more in comparison to atoms of higher mass
3
Q
Hooke’s law
A
The force to compress or extend a spring is:
F(r) = -k x (r-re)
Where k is the force constant (strength of bond) and r refers to actual length and equilibrium length
Units are N m-1
4
Q
How to work out potential energy in a spring
A
V (r) = 1/2 x k x (r - re)^2
5
Q
What is Eb?
A
The bond dissociation energy
6
Q
How is vibrational frequency calculated?
A
V = 1/ 2π x √k/µ
Units is Hz or s-1
7
Q
What is the reduced mass?
A
