What describes the technology used by the intoxilyzer

The intoxilyzer uses infrared (IR) spectroscopy. This method can identify particles by the amount of the IR light they absorb.  The bonds that hold these particles together also absorb IR light in specific ways.  Combining this information provides a unique identifier, almost like a fingerprint.  In turn, not only will the intoxilyzer identify a chemical such as ethanol, but it will also provide the ability to understand how much is present.