Spectra of the weakly-bound N2O-C2H2 and N2O-C2D2 complexes in the region of the N2O nu(1) fundamental band (similar to 2224 cm (1)) are observed in a pulsed supersonic slit jet expansion probed with a tunable diode laser. Two bands are analyzed for each complex: the fundamental (N-N stretch), and a combination involving the intermolecular torsional (out-of-plane bend) vibration. The resulting torsional frequencies are 44.37 and 40.01 cm (1) for the C2H2 and C2D2 complexes, respectively. This represents the. first observation of the N2O-C2D2 isotopomer, and the. first direct determination of an intermolecular frequency for nitrous oxide-acetylene. (C) 2009 Elsevier B. V. All rights reserved.