PX282 - C6a - radiation-matter interactions

• consider light with an intensity, $I_{\lambda }$ passing through a material of thickness, $dz$
• the emergent light will have a new intensity, $I_{\lambda }^{\prime }$

absorption

• the change in specific intensity with respect to the depth due to absorption:

where, $\rho =$ density, and ${\kappa }_{\lambda }=$ the absorption coefficient/opacity

scattering

• the change in specific intensity with respect to the depth due to scattering:

where, ${\sigma }_{\lambda }=$ scattering coefficient, sometimes included in $\kappa$

emission

• the change in specific intensity with respect to the depth due to emission:

where, ${ϵ}_{\lambda }=$ emission coefficient