High resolution studies in the electronic absorption spectra of mono-substituted naphthalenes 1-fluoro- and 1-chloro-naphthalene

Abstract

The vapor phase absorption spectra of 1-fluoronaphthalene (1-FN) and 1-chloronaphthalene (1-ClN) have been recorded under high resolution. The vibronic bands involving ground and excited state normal vibrations have been assigned on the basis of their rotational contours. Whereas the prominent bands in the spectrum of 1-FN have only one type of rotational contour, those of 1-ClN show at least three different types of rotational contours. A planar vibration involving the ring carbon atoms appears with slightly more intensity than the 0 0 0 band in the case of 1-ClN and this vibration has been correlated with the in-plane ring deformation vibration which is effective in H-T intensity borrowing mechanism in the electronic spectrum of naphthalene. Fermi-type resonances have been observed in sequence bands of 1-FN as well as 1-ClN.