Attenuated Total Reflection (ATR) Fourier Transform Infrared Spectroscopy (FTIR)

The Science:

Infrared Spectroscopy

Infrared Spectroscopy allows analysts to identify the unknown components of both organic and inorganic samples as well as provide us with a quantitative analysis. The process begins by passing an infrared beam through the sample. The sample will absorb specific wavelengths based on the molecular structure of the sample. The result from a detector yields an infrared spectrum, or molecular fingerprint, of the sample, which is a representation of the molecular (trendline???) and structure of the sample.

Fourier Transform Infrared Spectroscopy (FTIR)

Fourier Transform is a rapid method used by analysts for infrared spectroscopy. It overcomes the limitations of the older methods using dispersive instruments, which measured discrete frequencies through a prism (orgrestiny??) dispersion system. The FT-IR method uses a device called an interferometer, which produces a signal that is encoded with all the IR frequencies, and are (determined?) simultaneously. Then, using a mathematical technique called Fourier Transformation, the instrument is able to decode the individual frequencies and provide the analyst with a ‘spectrum’ of the components. FT-IR technology is a faster determination of the spectra.

Attenuated Total Reflection (ATR)

Attenuated Total Reflection allows us to introduce a sample, liquid or solid, to the instrument without any special preparation. This is achieved by adding an ATR crystal, and through a series of internal reflections, the IR beam passes through the crystal into the surface of the sample and reflected to the IR detector. Identification is accomplished by (preliminary?) search of over 80 commercial and private (something??) containing over 110,000 spectra. Armstrong Forensic Laboratory is equipped with diamond crystal ATR-FTIR instrumentation so we can provide our clients with accurate, reliable data in a timely manner.

Common Applications:

  • Identification of Unknown Substances
  • Identification of Fuel Contaminants
  • Identification of Oil Contaminants
  • Identification of Illegal Substances
  • Paint Characterization
  • Identification of Polymers
  • Quantification of Selected Components