1. Absorption Spectroscopy
Topic 4 part 1
Biophysics

2. Energy and Absorption Absorption is proportional to
Get resonance at hf = ħw = Eb – Ea

3. Transition Probability and transition dipole moment
mba = transition dipole moment =
- like
, it has three Cartesian coordinates

4. Absorption Broadening
Every electronic state (eg S0 and S1) has several vibrational and rotational substates.
Each of the sharp peaks is further broadened by Doppler shifts and solvent effects and quantum probabilities.
pubs.rsc.org/ej/DT/2000/B002123G/

5. Extinction Coefficient
Sample with pathlength l
Light Source I0 l
monochromator
Detector I Or
monochromator
Light Source
Beam
Splitter
Reference I0 l
Detector I1
Sample with pathlength l I2
A(l) = log (I0/I)
A(l) = Ce(l)l

6. Cross Section and Connecting Macroscopic to Micropscopic
= sNA/1000

7. Biopolymer absorption
Protein Secondary Structure
Protein Aromatics
Blood