2.2. IR Dispersive Analyzer The IR dispersive analyzer utilizes infrared absorption spectroscopy, which is recognized as one of the best analysis techniques for identification of molecules in the vapor phase, for the analysis of the vapors captured by VPC. A MEMS thermal emitter, namely the EMIRS IR-55 from Axetris AG, Kaegiswil, Switzerland, was selected as the lightweight and low power consumption compact source to generate IR radiation over a wide spectral range.