Direct two-photon excitation of Sm3+, Eu3+, Tb3+, Tb.DOTA−, and Tb.propargylDO3A in solution

► Emission is observed following two-photon excitation of Sm(III), Eu(III) and Tb(III). ► Two-photon excitation spectra reported for Eu(III) and Tb(III). ► Complexes of Tb(III) have been addressed by two-photon excitation.