Determination of concentrations in ternary and quaternary molecular gas mixtures using femtosecond Raman spectroscopy

Measurements of concentrations in gas mixtures of three and four molecular components are presented. They rely on a femtosecond time-resolved pump–probe technique based on Raman-induced polarization spectroscopy. The rotational time response of the molecular gas mixture is measured as a function of the pump–probe time delay. No selective frequency tunability is needed as the molecular rotational spectra are excited within the laser bandwidth. The results obtained from experiments performed at room temperature in N<INF>2</INF>O–CO<INF>2</INF>–N<INF>2</INF> and N<INF>2</INF>O–CO<INF>2</INF>–O<INF>2</INF>–N<INF>2</INF> mixtures are presented and the accuracy of the method is discussed. Copyright © 2002 John Wiley & Sons, Ltd.