  Even 100 years after its introduction by Louis de Broglie, the wave-nature of
matter is often regarded as a mind-boggling phenomenon. To give an intuitive
introduction to this field, we here discuss the diffraction of massive
molecules through a single, double, and triple slit, as well as a
nanomechanical grating. While the experiments are in good agreement with
undergraduate textbook predictions, we also observe pronounced differences
resulting from the molecules' mass and internal complexity. The molecules'
polarizability causes an attractive van der Waals interaction with the slit
walls, which can be modified by rotating the nanomechanical mask with respect
to the molecular beam. The text is meant to introduce students and teachers to
the concepts of molecule diffraction, supported by problems and solutions that
can be discussed in class.
