Features and problems of metrological traceability of gas mixtures using UV absorption, FTIR, and CRD spectroscopy

¹ D. I. Mendeleyev Institute for Metrology (VNIIM), Saint Petersburg, Russia
² University of Information Technologies, Mechanics and Optics (ITMO), Saint Petersburg, Russia

Abstract

Metrological traceability is usually realized by comparing the high precision gas mixtures (reference standards (RS)) and working standards used for calibration of gas analyzers. The procedures with the use of UV absorption, FTIR, and CRD spectroscopy for the transfer of the mole fraction from the RS to the working standards are developed, in order to reduce the required number of RS and improve the accuracy of measurements. For the successful use of existing spectroscopic databases, the most accurate data was necessary to identify and attribute the uncertainty, based on our own experimental work carried out using the RS. Further on the transfer of the mole fraction from the RS to the working standards can be done without the use of the RS. In the case of CRDS, when the matrix of the studied gas mixture is different from air, the broadening of the spectral lines associated with the interactions between molecules leads to significant error in the measurement of concentration of the studied gas. The effects leveling benefits of the CRDS method are studied.