Figure 2. The wave-particle duality of the biodye tetraphenylporphyrin can be revealed by diffracting the molecules in a near-field interferometer of the Talbot–Lau type ( Hackermüller et al., 2003 ).

. Molecules passing the first grating are diffracted and delocalized over several micrometers at the second grating. Diffraction there leads to interference fringes, i.e., a molecular density pattern, at the position of the third mask. This is imaged by scanning grating G₃ and by recording all transmitted molecules in a mass spectrometer.