Chemical Processes & Instrument Development: Instruments

Fourier Transform Infrared Spectrometer (FTIR)

Principle of the Measurement

A broadband light source passes through a Michelson interferometer, an absorption cell, and then to a detector. The interferogram is generated by making signal measurements at various positions of a moving mirror. A Fourier transform converts the interferogram from a mirror displacement (cm) domain into the inverse domain (cm^-1), creating a spectrum of the signal at discrete wavelengths.

FTIR Instrument Models: Nicolet 560, Nicolet 760, Nicolet iS50

Technical Specifications

Species Measured: various gaseous reactants and products
Accuracy: ±5% at concentrations above detection limit
Spectral Resolution: minimum 0.125 cm^-1
Time Domain: 10-120 s to acquire 1 cm^-1 resolution spectra
Detectors / Beam Splitters:

• KBr beamsplitter (400-4000 cm^-1 spectral range)
• Mercury cadmium telluride (MCT) detectors
• MCT-A 400 cm^-1 cutoff
• MCT-B 650 cm^-1 cutoff

Applications

Infrared absorption cross sections, On-line concentration measurements in kinetics experiments, Photolysis/reaction yield measurement, Determination of Radiative efficiencies and global warming potentials.

Contact

Jim Burkholder

Key Publications

Bernard, F., D.K. Papanastasiou, V.C. Papadimitriou, and J.B. Burkholder, Infrared absorption spectra of N(C_xF_2x+1)₃, x = 2-5 perfluoroamines, Journal of Quantitative Spectroscopy & Radiative Transfer, doi:10.1016/j.jqsrt.2018.02.039, 2018.

Bernard, F., D.K. Papanastasiou, V.C. Papadimitriou, and J.B. Burkholder, Infrared absorption spectra of linear (L₂-L₅) and cyclic (D₃-D₆) permethylsiloxanes, Journal of Quantitative Spectroscopy & Radiative Transfer, doi:10.1016/j.jqsrt.2017.08.006, 2017.