IR Flashcards
what is IR spectroscopy
IR radiation is shone through a sample. certain frequencies are absorbed/ ( a photon is absorbed).this causes the sample to vibrate at a higher level.
what does 100% transmission mean in IR
No energy is absorbed.
how to prepare a liquid for IR Spec
it is applied as a thin film between two nacl platyes
how to prepare a solid for IR Spec
grind it with nujol to create mull. it is applied as a thin film between 2 nacl plates
how to prepare a gas for IR Spec
a glass cell if filled with sample, the window is made with inorganic salt as glass absorbs IR.
what happens when A molecule absorb IR photon
They gain vibrational energy. the bonds vibrate more.
names of vibration energy levels
v= 0 , v = 1 ground state or fundemental
v = 2 first overtone
v =3 second overtone
size of intensities of energy levels
v= 0,1 is greater than v=2 , v=2 is greater than v= 3.
It mimics the spacing of vibrational levels.
How to model vibration of diatomic molecules
two balls on a spring.
what can bonds do
compress and stretch
what happens when the bonds stretch and compress
the energy of the system rises to go back to the equilibrium length
harmonic oscillator
a model use to describe small oscillations
frequency of oscillations
v = 1/2 pi * sqrt Kf / m
formula for u (mew )
u = m1 m2 / m1 + m2
what is mew
reduced mass
