Ftir
FTIR ANALYSIS
Ed Hare, Ph.D.
FTIR (Fourier Transform Infrared) analysis provides spectral information that is essentially a molecular fingerprint for organic, polymeric, and in some case inorganic materials. This technique is extremely useful for identifying base polymer compositions and organic contaminants. The FTIR spectrum of the unknown material can be compared for “best matches” with libraries of spectra that have been cataloged for known materials.
An example of an FTIR spectrum for Poly(oxymethylene) or POM or DelrinTM (DuPont trademark) is shown as Fig. A. The x-axis is wavenumber (cm-1), which is the inverse of wavelength (cm). The y-axis is absorbance normalized on a scale of 0 – 1 where 0 = no absorption and 1 = maximum absorption.
TM
Fig. A - FTIR spectrum for Poly(oxymethylene) or POM or Delrin .
1
The monomer for POM is shown in Fig. B.
The major peak at wavenumber
-1
903 cm is due to the C-O-C symmetric stretch absorption.
The peak at wavenumber
1097 cm-1 is due to the C-O-C asymmetric stretch. The peak at wavenumber 2923 cm-1 is due to the CH2-O asymmetric stretch. All of these vibration modes are indications of the specific molecular bonding within the sample and can be used to identify the material.
TM
Fig. B - Poly(oxymethylene) or POM or Delrin
monomer.
The library of FTIR spectra available in this laboratory includes more than 9400 spectra of organic, polymeric, and inorganic materials. These spectra are compared to the unknown sample spectra using computer software to identify the “best match”. Many times this type of library search is sufficient to answer the frequent question “what is this material or substance?”
Web based libraries of FTIR spectra can also be searched online when a suitable match is not available using reference spectra on hand. The online database contains nearly 71,000 FTIR spectra that can be compared with the unknown material.
THE SPECTROMETER
This laboratory utilizes a
Ed Hare, Ph.D.
FTIR (Fourier Transform Infrared) analysis provides spectral information that is essentially a molecular fingerprint for organic, polymeric, and in some case inorganic materials. This technique is extremely useful for identifying base polymer compositions and organic contaminants. The FTIR spectrum of the unknown material can be compared for “best matches” with libraries of spectra that have been cataloged for known materials.
An example of an FTIR spectrum for Poly(oxymethylene) or POM or DelrinTM (DuPont trademark) is shown as Fig. A. The x-axis is wavenumber (cm-1), which is the inverse of wavelength (cm). The y-axis is absorbance normalized on a scale of 0 – 1 where 0 = no absorption and 1 = maximum absorption.
TM
Fig. A - FTIR spectrum for Poly(oxymethylene) or POM or Delrin .
1
The monomer for POM is shown in Fig. B.
The major peak at wavenumber
-1
903 cm is due to the C-O-C symmetric stretch absorption.
The peak at wavenumber
1097 cm-1 is due to the C-O-C asymmetric stretch. The peak at wavenumber 2923 cm-1 is due to the CH2-O asymmetric stretch. All of these vibration modes are indications of the specific molecular bonding within the sample and can be used to identify the material.
TM
Fig. B - Poly(oxymethylene) or POM or Delrin
monomer.
The library of FTIR spectra available in this laboratory includes more than 9400 spectra of organic, polymeric, and inorganic materials. These spectra are compared to the unknown sample spectra using computer software to identify the “best match”. Many times this type of library search is sufficient to answer the frequent question “what is this material or substance?”
Web based libraries of FTIR spectra can also be searched online when a suitable match is not available using reference spectra on hand. The online database contains nearly 71,000 FTIR spectra that can be compared with the unknown material.
THE SPECTROMETER
This laboratory utilizes a