Rotational band contour analysis in the Ã1A′-[Xtilde]1A′ electronic systems of substituted naphthalenes

The 00 0 bands of the à 1 A′-[Xtilde] 1 A′ systems of 1-fluoro, 1-hydroxy and 1-aminonaphthalene have been investigated by rotational band contour analysis. The 00 0 bands in 1-fluoro and 1-hydroxynaphthalene are 70 per cent type A and 30 per cent type B, and 75 per cent type A and 25 per cent type B hybrids respectively: the electronic transition moment vector has been rotated by about 15° towards the carbon atom C3 by the F and OH substituents compared to naphthalene (in which, in the Ã-[Xtilde] system, it is along the long in-plane axis). In 1-aminonaphthalene it seems likely that the 00 0 band is predominantly type A, but it could not be observed with sufficient intensity to be able to obtain the excited state rotational constants with any certainty.