The v 1+v 3 band of 12Cv 2Hv 2 was recorded using a high resolution continuous scan Fourier transform interferometer fitted with a femto OPO absorption source. Various experimental schemes were successfully implemented, including multipass absorption in a cell and also in a supersonic expansion, and cavity enhanced absorption. An optimal rms noise equivalent absorption of 2.2×10 -9cm -1Hz 1/2 per spectral element was reached in the latter case, corresponding to α min=1.5×10 -7cm -1. Performances are illustrated and discussed. Copyright © 2011 Taylor and Francis Group, LLC.