A new supersonic expansion made of several, up to 31 aligned nozzles, on top of a set of powerful Roots blowers has been built. Adequate optics allowed the recording of infrared absorption spectra in a cell with a Fourier transform interferometer, at high spectral resolution. The system was tested with N2O, between 2000 and 4800 cm(-1). The nu(1) + 2 nu(2) + nu(3) combination band, estimated to be some 10000 times weaker than the nu(3) fundamental, could be observed among all the other expected bands, thus setting a limit for the sensitivity of the system. The formation of large N2O clusters was observed.