Abstract
In this work, we investigate how much information a conventional infrared spectroscopic technique (FTIR) can yield for NO₂ reference materials in the range of concentrations between 100 to 2500 μmol/mol. The amount fraction of 100 μmol/mol corresponds to the actual maximum for NO₂ emissions by modern Euro 6 vehicles and is suitable for Portable Emissions Measurement Systems (PEMS) calibration. A set of measurements of four reference mixtures was performed. For the analysis, we developed an efficient and simple algorithm, based on the integration of rovibrational bands, yielding the molar fractions of NO₂ (including dimer) and several impurities, such as N₂O and HNO₃. It resembles a Japanese puzzle box, Himitsu Bako, since different mixture components should be addressed in a certain order to unravel a complete composition. The algorithm was successfully applied to the recorded spectra. For example, the uncertainties for low NO₂ amount fractions were shown to be limited essentially by the quality of reference spectroscopic data for the monomer (HITRAN database in the current work), and not by the measurement procedure. Shortcomings, further development, and improvements of the experimental set-up as well as of the evaluation algorithm are addressed.
Citation
@article{Kim2025,
title = {Himitsu Bako of NO₂ Mixtures: Characterization of NO₂ Reference Material Using FTIR Spectroscopy in Middle Infrared Region},
shorttitle = {Himitsu Bako of NO₂ Mixtures},
author = {Kim, Mi Eon and Berezkin, Kirill and Saturno, Jorge and Werwein, Viktor and Li, Gang and Domanskaya, Alexandra},
year = {2025},
month = jan,
journal = {Emission Control Science and Technology},
volume = {11},
number = {1},
pages = {6},
issn = {2199-3629, 2199-3637},
doi = {10.1007/s40825-024-00252-5},
urldate = {2025-01-08},
langid = {english}
}