Part 1 : Nanoparticles Module 5 : Absorption and scattering by a particle
Lecture 3 : Extinction, scattering and absorption
 
Extinction, scattering and absorption :
Let the rate at which the em energy is received by the detector D (see Fig. 5.5) downstream be $U$, and $U_o$ if the collection of particles are removed; clearly $U_o>U$. The presence of the particles result in extinction of the incident beam. If the embedding medium is non-absorbing, then the difference $U_o-U$ can only be due to absorption in the particles, and scattering by the particles. The extinction depends on the detailed nature of the particles, viz., their chemical composition, shape, orientation, the surrounding medium, the number of particles, and the polarization state and frequency of the incident beam.

Fig. 5.5: Schematic for extinction and scattering