Fourier Transform Infrared Analyzers

Question 1

An ______________ creates interfering mixtures of IR radiation to send through the sample

Answer 1

interferometer

Question 2

What category of IR detector is used in an FTIR analyzer and what is the name for the detector signal output over time?

Answer 2

An FTIR uses a wideband non-specific detector that outputs an interferogram

Question 3

What can cause the calibration of an NDIR analyzer to drift over time?

Answer 3

1) Dirty sample cell
2) Weak IR source
3) Decrease in detector sensitivity

Question 4

Explain what would happen to a gas analyzer’s readings if the pressure in the sample cell increased.
Explain what would happen if the temperature in the sample cell increased.

Answer 4

Pressure increase: causes density increase therefore increasing the concentration readout

Temperature increase: causes a density decrease therefore decreasing concentration readout

Question 5

Identify three common NDIR analyzer maintenance activities.

Answer 5

1) Replace faulty IR source bulbs
2) Replace faulty detectors
3) Clean cell windows

Question 6

How are the chemicals in a sample identified by FTIR?

Answer 6

A program that assigns each chemical an absorption frequency