High-resolution FTIR spectrum of the nu(9) band of ethylene-D-4 (C2D4)

The spectrum of the nu(9) fundamental band of ethylene-d(4) (C2D4) has been measured with an unapodized resolution of 0.004 cm-L in the frequency rang e of 2300-2400 cm(-1) using a Fourier transform infrared spectrometer. A to tal of 549 transitions have been assigned and fitted using a Watson' s A-re duced Hamiltonian in the I' representation to derive rovibrational constant s for the upper state (nu(9) = 1) up to five quartic terms with a standard deviation of 0.00087 cm(-1). They represent the most accurate rovibrational constants for the nu(9) band so far. About 30 transitions of K'(a) = 0, on e transition of nu(9) which were identified to be perturbed possibly by the nearby nu(11) and nu(2) + nu(12) transitions, were not included in the fin al fit. The nu(9) band of C2D4 was found to be basically B-type with an unp erturbed band center at 2341.836 94 +/- 0.000 13 cm(-1). (C) 2000 Academic Press.