Bomem-GRAMS User's Guide

Appendix D
Glossary
Analyzer
Spectrometer
Source
Interferometer
• modulates light from source
Laser
• provides precise, stable reference
for interferometer
Detector
• converts modulated light to electrical
signal after it passes through the sample
• is in spectrometer or sampling accessory
Sampling system (if required)
• brings a sample of the process to the
sampling accessory
• may include valves, filters, pumps, etc.,
controlled by the software
Sampling accessory
• allows modulated light beam to interact
with the sample
• is mounted on spectrometer or linked
by fiber-optic cable
Analyzer software
• performs FFT calculation, analysis of
spectra, reporting, data archiving, etc.
• may control the sampling system(s)
Figure D-1. Analyzer
background spectrum (see reference spectrum)
beamsplitter
A semi-reflecting mirror in the interferometer used to divide the radiation
from the infrared source into two beams, and to recombine the two beams
into a single beam.
Beer-Lambert’s law
An equation relating the absorption of light by a sample to the absorption
coefficient of the sample, the path length, and the concentration.
A λ
= ε λ
× b × C
where
A λ is the sample’s absorbance value at a specific wavelength (λ)
ε λ is the absorption coefficient of the material at that wavelength
(l⋅mol -1 ⋅ cm -1 ).
b is the path length through the sample (cm)
C is the concentration of the analyte (mol⋅l -1 )
BK7
A high quality optical glass.
BK7 is not hygroscopic. Its refractive index is 1.50 at 8000 cm -1 . Its spectral
range is from 25000 cm -1 to 3700 cm -1 .
48 Bomem-GRAMS User's Guide