Attenuated Total Reflectance (ATR)$99 Base price Go to quote list
Fourier-transformed infrared spectroscopy (FTIR) is a nondestructive, optical technique used to analyze chemical composition and the optical properties of a material.
In an FTIR measurement, an initially wide range of infrared wavelengths are simultaneously shone upon an area of the sample. Using an interferometer, the FTIR system then extracts a specific wavelength band at a time and measures its light intensity: selectively detecting either reflected or transmitted beams. The operator will determine whether to target transmittance or reflectance intensity based on the sample’s composition and topography. After this initial measurement, the extracted wavelength band is subsequently scanned over the entirety of the wavelength range, capturing an intensity measurement at each band. The resulting values are then fourier-transformed to produce the initial sample spectrum. To isolate the real sample spectrum, a reference – or ‘blank’ – trial is conducted without any material inserted in the beam path. This spectrum is used to normalize the sample spectrum and to isolate the relevant specimen information from the total signal. In the wavelength range of interest, different types of chemical bonds absorb at different wavelengths: providing a spectral signature which is material dependent. The resulting background-subtracted spectrum can then be used to qualitatively identify chemical functional groups and trace chemicals present in the specimen.
ATR-FTIR is a variant FTIR measurement mode which uses a specialized crystal to generate multiple internal reflections along the lateral dimension of the sample, increasing signal-to-noise and surface sensitivity.
- Rapid results
- Nondestructive analysis
- Particularly well suited for organic chemical analysis
- Robust reference libraries are available
- Requires reference or a standard / control sample to make positive chemical identifications
- Most inorganic molecules do not exhibit an FTIR spectrum
- Solid or liquid phase
- Flat surface is ideal; other topographies are accepted, may impact data quality
- Material must not be too reflective (e.g. high-reflection metallics), nor too transmissive (e.g. some glasses), for best results
Thermo Fisher Nicolet 6700 IR Spectrometer
- 4 Analytical Modes / Measurement Accessories:
- Specular Reflectance
- Attenuated Total Reflectance (ATR): both Ge and Diamond-C sampling systems
- NicPlan IR Microscope (transmittance and reflectance mapping with 20 µm spot size)
FTIR spectra from 3 plastic polymer materials – Polyethylene terephthalate (PET), Polyethylene (PE), Polypropylene (PP) – overlaid for comparison
Simple FTIR spectrum contrasting raw measurement (blue) to reference (red) on HVAC sample