The ir spectrum of isoquinoline has been investigated in the region 700–4000 cm−1. The observed frequencies have been correlated to the Raman frequencies and assigned to different modes of vibrations. The electronic absorption spectrum of the molecule has also been recorded in vapor phase in the region 2900–3200 Å. The system has been assigned to n–π* transition with the electronic origin at 31 984 cm−1. A vibrational analysis for the system is proposed.
R. Ammini Amma, S. N. Thakur, and K. P. R. Nair, "Infrared and Electronic Absorption Spectra of Isoquinoline," Appl. Spectrosc. 24, 344-347 (1970)