We report on our current status towards the development of a prototype Fourier transform infrared phase shift cavity ring down spectrometer (FTIR-PS-CRDS) system under a U.S. EPA SBIR contract. Our system uses the inherent wavelength-dependent modulation imposed by the FTIR on a broadband thermal source for the phase shift measurement. This spectrally-dependent phase shift is proportional to the spectrally-dependent ring down time, which is proportional to the losses of the cavity including those due to molecular absorption. Our approach is a broadband and spectral range enhancement to conventional CRDS which is typically done in the near IR at a single wavelength; at the same time our approach is a sensitivity enhancement to traditional FTIR owing to the long effective path of the resonant cavity. In this paper we present a summary of the theory including performance projections and the design details of the prototype FTIR-PS-CRDS system.

Date Published: 29 May 2013
PDF: 12 pages
Proc. SPIE 8726, Next-Generation Spectroscopic Technologies VI, 87260Z (29 May 2013); doi: 10.1117/12.2014392

Published in SPIE Proceedings Vol. 8726:
Next-Generation Spectroscopic Technologies VI
Mark A. Druy; Richard A. Crocombe, Editor(s)