Computational resolution enhancement: congested overtone spectrum of diacetylene

Abstract

The first CH stretching overtone band system of diacetylene (1,3-butadiyne) in the range of 6350–6750 cm⁻¹ has been recorded with a high resolution Fourier transform infrared interferometer at room temperature. Although the spectrum obtained may be resolved rotationally, two different computational procedures have been used to enhance the resolution due to severe congestion in the central parts of the band system. It has become possible both to find one new band and to achieve higher precision. Altogether five bands with the lower state being the ground vibrational state have been analysed rotationally. The results obtained are discussed in the context of a previous molecular beam study of a small part of the same band system.