L-RESONANCE EFFECTS IN C2H-2 NEAR 13.7 MU-M .2. THE 2 QUANTUM HOTBANDS

This article is the second part on l-resonance effects on the rotation -vibration bands of acetylene observed in the nu5 fundamental region. While the first part concentrated on the energy level analysis of the fundamental and the seven strongest hotbands originating in the nu4 an d nu5 excited states for both major isotopes [Spectrochim. Acta 48A, 1 203 (1992)], this article summarizes the results of the analysis of th e hotbands 2nu4 + nu5 <-- 2nu4, nu4 + 2nu5 <-- nu4 + nu5, and 3nu5 <-- 2nu5 from which improved molecular constants for the 2nu4 and three q uantum energy levels were derived for the major isotope (C2H2)-C-12. T he mixing levels within the excited vibrational states due to vibratio nal and rotational l-resonance effects are discussed which lead to the identification of the strong ''forbidden'' DELTAl = 3 band, 2nu4 + nu 5(3) <-- 2nu4(0e) as a result of l-resonance intensity perturbation.