Absorption: general principles
The Beer Lambert Law
ü
üThe absorption strength of a molecule can be determined by absorption measurements using
   The Beer-Lambert Law, which is expressed as:
Absorption (Optical Density) =  log Io / I  = e c l
ü
Io and I are the intensities entering and leaving the
sample respectively
e  is the extinction coefficient or molar absorption index
    ( a molecular property)
e
l  is the pathlength of the sample (1 cm)
Deuterium/
Tungsten
Lamp
                     
PMT sample
PMT reference
I
Io
Mono-
chromotor
sample
blank
Detector
GM
Absorption