Photometric Linearity; Introduction - ABB MB3000 Series Installation And User Manual

Appendix C Spectroscopy Background

Photometric Linearity

Introduction

Beer's law relates the absorbance intensity of spectral bands to the concentration of
the analyte and the pathlength of the light beam through the sample. In an FTIR
Absorbance is not measured directly, but is derived via the negative logarithm of the
ratio of sample spectrum divided by background spectrum.
series of six absorbance spectra of pure Toluene recorded with a variable
path length liquid cell. The pathlength settings are 1000 μ
250 u
AA003700-01 rev. G. 2.0
Appendix C Spectroscopy Background
μ μ
m, 100 m and 33
Figure C- 1. Series of toluene spectra
μ
m for highest to lowest absorbance intensity.
Photometric Linearity
Figure C- 1 shows a
μ μ
m, 750 m, 500 m,
53