Topic 24 Flashcards
Describe the interaction of light with matter
Light emission is connected with changes in the state of outer electrons
X-rays are a consequence of inner electrons change of state
Describe light emission
When an electrons goes from excited state back to ground state, releasing energy as light.
Energy released is the difference between exciteed state and ground state
Which ways can photons be emitted?
Spontaneously or stimulated
What is Rayleigh Scattering?
Emission of a photon with the the same frequency of an incoming photon
High Probability
What is Raman Scattering?
Emission of photons with higher or lower frequency
Low probability
What is compton scattering?
Photon collides with a free electron, changing its energy
Describe Absorption
If frequency of incoming photon is enough to raise the energy state, it will be totally absorbed.
What is photoluminescence?
Light emission which is produced by light
What is fluorescence?
Electron goes from excited state to ground level directly
When illumination stops, so does fluoresence.
What is Phosphorescence?
Electron goes from excited to ground level via intermediate levels.
When illumination stops, the matter still illuminates partially.
What is the law of light attenuation in matter?
When light is passing through a medium, energy is transmitted to the medium and attenuate.
Give the equation for the Lambert law
I = I0e-µd
- I = Intensity*
- d = Thickness of material*
- µ = Attenuation coefficient*
Give the equation for the beer-lambert law
I = I010-εdc
ε = Molar exctinction coefficient
c = molar concentration
Equation to calculate % transmission
100 * I/I0
Equation to calculate absorbance
log(I/I0)
