The spin-forbidden b(1)Sigma(g)(+)(v' = 0) <-- X(3)Sigma(g)(-) (v" = 0) band of molecular oxygen in air has been measured to show that broad band continuous wave phase shift cavity ring down spectroscopy can be combined with Fourier transform g spectroscopy. In contrast to ordinary cavity ring down spectroscopy, where a laser is used to excite the ring down cavity, here, an incoherent continuous broad band light source is used. This opens the way to build a Fourier transform spectrometer with which absorption measurements can be performed at a resolution determined by the Michelson interferometer and over a wavelength range from 10 mum to 250 nm with a sensitivity increase of about three orders of magnitude, as compared to standard Fourier transform spectrometers. (C) 2002 Elsevier Science B.V. All rights reserved.