PPT Slide
- Most importantly, FTIR instruments have a single beam, whereas dispersive instruments usually have a double beam.
- Assuming there is no change in atmospheric conditions throughout the experiment, this does not cause a problem.
- However, for highly sensitive work, and experiments which take along time, changes in infrared absorbing gas concentrations can severely affect the results.
- Therefore, in these cases, when using an FTIR instrument, it is necessary to purge the instrument of CO2 and water vapour using an infrared transparent gas such as nitrogen.