What is the formula to find the absorption coefficients of materials?
Asked by: Michelle May
Answer
Well, according to 'principles of optics' from Born & Wolf (p614) the absorption coefficient formula is the following:
X=(2Wnk)/c=(4Pik)/L
Where x is the absorption coefficient,W the frequency of
light in the vacuum, c the speed of light in vacuum, l is
the wavelength inside the medium and n and k
are the refractive index and the attenuation index (also called
extinction coefficient) respectively.
The quantities n and K may be easily be expressed in terms of
the material constants (dielectric constant, the electrical
conductivity and the magnetic permeability)
Note that this expression of the absorption coefficient is
a good approximation if the dielectric constant is real and
the excitation frequency is low (long wavelength)
Answered by: Alex Bouhelier, Ph.D Physics, Uni Basel (CH)
'The true spirit of delight, the exaltation, the sense of being more than Man, which is the touchstone of the highest excellence, is to be found in mathematics as surely as in poetry.'