[en] Absorption of gas-phase biomolecules has been studied at the electrostatic ion storage ring ELISA. It is demonstrated that the storage ring technique with long storage times and suitable particle detection is ideal for studies of the photo-physics of chromophores. Here the authors discuss the absorption characteristics of the chromophores of the Green Fluorescent Protein (GFP) and compare authors' gas-phase absorption measurements with absorption profiles of the protein and chromophores in liquids. It is argued that the absorption characteristics of GFP are mainly ascribed to intrinsic chemical properties of the chromophore