Napierian Absorbance is the natural (Napierian) logarithm of the reciprocal of the spectral internal transmittance.
$A_e(\lambda) = -ln(\tau(\lambda))$, where $\tau$ is the transmittance at a given wavelength $\lambda$.
Applicable units are those of quantitykind:NapierianAbsorbance
Napierian Absorbance