The spectra associated with transitions between the electronic states of molecules. These transitions correspond to the visible or ultraviolet regions of the electromagnetic spectrum. There are changes in vibrational and rotational energy when electronic transitions occur. Consequently there are spectral bands associated with changes in vibrational motion, with these bands having fine structure due to changes in rotational motion. Because electronic transitions are associated with changes in vibrational motion the corresponding spectra are sometimes called vibrational spectra. The electronic spectra of molecules are used to obtain information about energy levels in molecules, interatomic distances, dissociation energies of molecules, and force constants of chemical bonds.