Two electronic transitions in the near-UV region of six isomeric difluorobenzonitriles—I

• Published in: Spectrochimica acta. Part A: Molecular spectroscopy 1993, Vol.49 (2), p.223-236
• Main Authors: Ramu, K., Rao, C.G.Rama, Santhamma, C.
• Format: Article
• Language: English
• Subjects: Atomic and molecular physics; Exact sciences and technology; Molecular properties and interactions with photons; Molecular spectra; Physics; Ultraviolet spectra
• ISSN: 0584-8539
• DOI: 10.1016/0584-8539(93)80177-C

A new technique—photoacoustic spectroscope (PAS)—is applied to the study of the electronic transitions in the six isomers 3,5-; 2,4-; 2,5-; 3,4-; 2,3-; and 2,6-difluorobenzonitriles. The PAS spectra are compared with solution spectra recorded. The two π-π* transitions analogous to the benzene strong 200 nm, and weak and forbidden 260 nm transitions could be identified in these molecules. An interesting observation is that the origins of the electronic transitions in these molecules are in fairly good agreement with the additive rule which is routed through different starting points and also a prediction of the origin of meta fluorobenzonitrile at 37,536.1 cm −1 from the data of 3,4- and 2,5-difluorobenzonitriles. The fluorescence spectrum for all six isomers is reported here for the first time.