Electronic absorption spectra of impurities in superfluid helium is developed in time domain, using time-dependent density functional theory to describe liquid He-4 and time-dependent perturbation theory to describe the electronic degrees of freedom of the impurity. Angularly isotropic potentials are used to describe the molecule-helium interactions in the ground and excited electronic states. The calculations rationalize experimentally observed phonon side-bands in He-4 droplets and in bulk helium, and allow assignments of spectral features to specific motions of the liquid. (C) 2004 Elsevier B.V. All rights reserved.