I-RESONANCE PERTURBATION OF IR INTENSITIES IN (C2H2)-C-12 NEAR 13.7-MU-M

Using TDL and FT spectrometric data at 0.0005 and 0.0025 cm-1 spectral resolution, respectively, individual line intensities of the nu5 fundamental and the seven strongest hot bands, nu4+ nu5 <-- nu4 and 2nu5 <-- nu5, of (C2H2)-C-12 in the 13.7-mum region have been measured. Except for the 2nu5(2f) <-- nu5(1f) hot band, strong intensity perturbation due to l-type doubling and resonances have been quantitatively determined for all hot bands. The zeroth-order vibrational dipole moment derivative for the nu5 bending mode is identical within 10% for all bands observed. Since an extra factor of 1/2 appears in the square vibrational transition moment for the combination band, its intenSity is reduced by half and is comparable in magnitude to the 2nu5 <-- nu5 hot bands. For the nu5 fundamental a square dipole moment derivative of GAMMA(upsilon)2 = 0.09069(24)D2 has been determined. (C) 1994 Academic Press, Inc.