A new background free IR spectroscopic technique, termed as fluorescence enhancement detected IR (FEDIR) spectroscopy for recording vibrational spectra in the supersonic jets, is presented. An application to the N-H and the C-H stretching vibrations of aniline is demonstrated. High fluorescence quantum yield of the higher vibronic levels in the S-1 state is prerequisite for this spectroscopic technique. A direct comparison of S/N ratio between the present technique and an earlier technique is also presented. (C) 2002 Published by Elsevier Science B.V.