The excitation of label molecules usable in chemical and biochemical analysis by electrical pulses at electrodes covered with a thin insulating film, and the use of such electrodes in chemical, clinical and biochemical analysis. The electrodes include a conducting base material that has been coated with an organic or inorganic insulating film or multiple layers of such films, so that either one or several label compounds can be excited to an excited state which is deexcited by emission of ultraviolet, visible or infrared light, in aqueous solution providing the basis for reproducible analytical applications in bioaffinity assays such as immunoassays and DNA-probing assays.