depth of penetration

of light
https://doi.org/10.1351/goldbook.D01605
The inverse of the
absorption coefficient
. If the decadic
absorption coefficient
, a, is used, the depth of penetration (1a) is the distance at which the
radiant power
, Pλ, decreases to one tenth of its incident value, Pλ0. If the Naperian
absorption coefficient
, α, is used, the depth of penetration (1α=β in this case) is the distance at which the
radiant power
decreases to 1e of its incident value.
See:
absorbance
,
attenuance
Source:
PAC, 1996, 68, 2223. (Glossary of terms used in photochemistry (IUPAC Recommendations 1996)) on page 2235 [Terms] [Paper]