Spectroscopy and vibrational couplings in the 3v₃ region of acetylene

14 rovibrational bands are observed in the 1 micron region of the absorption spectrum of C2H2, between 9300 and 10 500 cm-1, and rotationally analysed. Transition induced dipole moments are estimated for all the cold bands involving upper levels of σ u + symmetry. Those various data are used to demonstrate the leading role of the 0030000 level in the vibrational mixings and also to deal quantitatively with a possible picture of the couplings occurring among the cluster of levels in resonance with 0030000.