Preferred Label : Beer–Lambert law;
Detailed label : Beer–Lambert law (or Beer–Lambert–Bouguer law);
IUPAC definition : The absorbance of a beam of collimated monochromatic radiation in a homogeneous isotropic
medium is proportional to the absorption path length, l, and to the concentration,
c, or — in the gas phase — to the pressure of the absorbing species. The law can be
expressed as: \[A {log}_{10}\left ( \frac{P_{\lambda } {0}}{P_{\lambda }} \right
) \varepsilon \:c\:l\] or \[P_{\lambda } P_{\lambda } {0}10 {-\varepsilon \: c\:
l}\] where the proportionality constant, ɛ, is called the molar (decadic) absorption
coefficient. For l in cm and c in mol dm-3 or M, ɛ will result in dm 3 mol-1 cm-1
or M cm-1, which is a commonly used unit. The SI unit of ɛ is m2 mol-1. Note that
spectral radiant power must be used because the Beer–Lambert law holds only if the
spectral bandwidth of the light is narrow compared to spectral linewidths in the spectrum.;
Origin ID : B00626;
See also
The absorbance of a beam of collimated monochromatic radiation in a homogeneous isotropic
medium is proportional to the absorption path length, l, and to the concentration,
c, or — in the gas phase — to the pressure of the absorbing species. The law can be
expressed as: \[A {log}_{10}\left ( \frac{P_{\lambda } {0}}{P_{\lambda }} \right
) \varepsilon \:c\:l\] or \[P_{\lambda } P_{\lambda } {0}10 {-\varepsilon \: c\:
l}\] where the proportionality constant, ɛ, is called the molar (decadic) absorption
coefficient. For l in cm and c in mol dm-3 or M, ɛ will result in dm 3 mol-1 cm-1
or M cm-1, which is a commonly used unit. The SI unit of ɛ is m2 mol-1. Note that
spectral radiant power must be used because the Beer–Lambert law holds only if the
spectral bandwidth of the light is narrow compared to spectral linewidths in the spectrum.
