FT-IR
Fourier Transform Infrared Spectrophotometer
It is not too exaggerating to say Fourier Transform Infrared Spectrophotometer is the most dominant analysis technologies
for organic substance (solid state). When analyzing organic substance, it is very common to measure with FT-IR in the first
place. The technology is utilized in analyzing foreign material, etc.
When irradiate infrared beam on substance, light beams with specific wave length are selectively absorbed; and resulting infrared
absorption spectrum is inherent to independent solid-state substance, just like the finger print is inherent to individual.
Further, since the timing of wavelength infrared absorption is associated with partial structure of the substance, knowing
infrared absorption spectrum enables us to identify chemical structure of unknown substance. In FT-IR, light emitted from
infrared light source comes into interferometer to produce interference wave (interferogram), which pass through the specimen.
In passing, lights are selectively absorbed depending on their vibration frequency specific to vibration energy of atom or
atomic group in molecule constituting the specimen.
The signal captured in detector is transformed (Fourier transform) in computer, to provide infrared spectrum specific to the
specimen.
Example
Analysis of foreign material contaminating memory module
Foreign material
Measure foreign material (about 0.1mm) contaminating memory module by means of FT-IR.
IR spectrum of black foreign material
IR spectrum for black connectors
Form the spectrum, the foreign material was identified as nylon resin, which is same to the substance used in connector. For confirmation, onnector was analyzed with FT-IR, the spectrum obtained was same as that of foreign material. Foreign material was identified as scrap coming from connector cutting.
FT-IR chart: ABS resin composition
From given infrared absorption spectrum, calculate composition ratio of acrylonitrile, butadiene, and styrene. Checking composition ratio is essential to keep resin characteristics such as mechanical strength at the stable appropriate level.