https://doi.org/10.1351/goldbook.D01605
The inverse of the @A00037@. If the decadic @A00037@, \(a\), is used, the depth of penetration (\(\frac{1}{a}\)) is the distance at which the @R05046@, \(P_{\lambda }\), decreases to one tenth of its incident value, \(P_{\lambda }^{0}\). If the Naperian @A00037@, \(\alpha \), is used, the depth of penetration (\(\frac{1}{\alpha } = \beta \) in this case) is the distance at which the @R05046@ decreases to \(\frac{1}{\text{e}}\) of its incident value.
See:
absorbance
, attenuance